In Situ Chemical Imaging of Solid-Electrolyte Interphase Layer Evolution in Li–S Batteries

DOE PAGES

Nandasiri, Manjula I.; Camacho-Forero, Luis E.; Schwarz, Ashleigh M.; ...

2017-05-03

Parasitic reactions of electrolyte and polysulfide with the Li-anode in lithium sulfur (Li-S) batteries lead to the formation of solid-electrolyte interphase (SEI) layers, which are the major reason behind severe capacity fading in these systems. Despite numerous studies, the evolution mechanism of the SEI layer and specific roles of polysulfides and other electrolyte components are still unclear. Here, we report an in-situ X-ray photoelectron spectroscopy (XPS) and chemical imaging analysis combined with ab initio molecular dynamics (AIMD) computational modeling to gain fundamental understanding regarding the evolution of SEI layers on Li-anodes within Li-S batteries. A multi-modal approach involving AIMD modelingmore » and in-situ XPS characterization uniquely reveals the chemical identity and distribution of active participants in parasitic reactions as well as the SEI layer evolution mechanism. The SEI layer evolution has three major stages: the formation of a primary composite mixture phase involving stable lithium compounds (Li 2S, LiF, Li 2O etc); and formation of a secondary matrix type phase due to cross interaction between reaction products and electrolyte components, which is followed by a highly dynamic mono-anionic polysulfide (i.e. LiS 5) fouling process. In conclusion, these new molecular-level insights into the SEI layer evolution on Li- anodes are crucial for delineating effective strategies for the development of Li–S batteries.« less

Simulation Protocol for Prediction of a Solid-Electrolyte Interphase on the Silicon-based Anodes of a Lithium-Ion Battery: ReaxFF Reactive Force Field.

PubMed

Yun, Kang-Seop; Pai, Sung Jin; Yeo, Byung Chul; Lee, Kwang-Ryeol; Kim, Sun-Jae; Han, Sang Soo

2017-07-06

We propose the ReaxFF reactive force field as a simulation protocol for predicting the evolution of solid-electrolyte interphase (SEI) components such as gases (C 2 H 4 , CO, CO 2 , CH 4 , and C 2 H 6 ), and inorganic (Li 2 CO 3 , Li 2 O, and LiF) and organic (ROLi and ROCO 2 Li: R = -CH 3 or -C 2 H 5 ) products that are generated by the chemical reactions between the anodes and liquid electrolytes. ReaxFF was developed from ab initio results, and a molecular dynamics simulation with ReaxFF realized the prediction of SEI formation under real experimental conditions and with a reasonable computational cost. We report the effects on SEI formation of different kinds of Si anodes (pristine Si and SiO x ), of the different types and compositions of various carbonate electrolytes, and of the additives. From the results, we expect that ReaxFF will be very useful for the development of novel electrolytes or additives and for further advances in Li-ion battery technology.

Phosphorus Enrichment as a New Composition in the Solid Electrolyte Interphase of High-Voltage Cathodes and Its Effects on Battery Cycling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Pengfei; Zheng, Jianming; Kuppan, Saravanan

2015-11-10

Immersion of a solid into liquid often leads to the modification of both the structure and chemistry of surface of the solid, which subsequently affects the chemical and physical properties of the system. For the case of the rechargeable lithium ion battery, such a surface modification is termed as solid electrolyte interphase (SEI) layer, which has been perceived to play critical role for the stable operation of the batteries. However, the structure and chemical composition of SEI layer and its spatial distribution and dependence on the battery operating condition remain unclear. By using aberration corrected scanning transmission electron microscopy coupledmore » with ultra-high sensitive energy dispersive x-ray spectroscopy, we probed the structure and chemistry of SEI layer on several high voltage cathodes. We show that layer-structured cathodes, when cycled at a high cut off voltage, can form a P-rich SEI layer on their surface, which is a direct evidence of Li-salt (LiPF6) decomposition. Our systematical investigations indicate such cathode/Li-salt side reaction shows strong dependence on structure of the cathode materials, operating voltage and temperature, indicating the feasibility of SEI engineering. These findings provide us valuable insights into the complex interface between the high-voltage cathode and the electrolyte.« less

Nanoscale imaging of fundamental li battery chemistry: solid-electrolyte interphase formation and preferential growth of lithium metal nanoclusters.

PubMed

Sacci, Robert L; Black, Jennifer M; Balke, Nina; Dudney, Nancy J; More, Karren L; Unocic, Raymond R

2015-03-11

The performance characteristics of Li-ion batteries are intrinsically linked to evolving nanoscale interfacial electrochemical reactions. To probe the mechanisms of solid electrolyte interphase (SEI) formation and to track Li nucleation and growth mechanisms from a standard organic battery electrolyte (LiPF6 in EC:DMC), we used in situ electrochemical scanning transmission electron microscopy (ec-S/TEM) to perform controlled electrochemical potential sweep measurements while simultaneously imaging site-specific structures resulting from electrochemical reactions. A combined quantitative electrochemical measurement and STEM imaging approach is used to demonstrate that chemically sensitive annular dark field STEM imaging can be used to estimate the density of the evolving SEI and to identify Li-containing phases formed in the liquid cell. We report that the SEI is approximately twice as dense as the electrolyte as determined from imaging and electron scattering theory. We also observe site-specific locations where Li nucleates and grows on the surface and edge of the glassy carbon electrode. Lastly, this report demonstrates the investigative power of quantitative nanoscale imaging combined with electrochemical measurements for studying fluid-solid interfaces and their evolving chemistries.

The Effect of Fluoroethylene Carbonate as an Additive on the Solid Electrolyte Interphase on Silicon Lithium-Ion Electrodes

DOE PAGES

Schroder, Kjell; Li, Juchuan; Dudney, Nancy J.; ...

2015-08-03

Fluoroethylene carbonate (FEC) has become a standard electrolyte additive for use with silicon negative electrodes, but how FEC affects solid electrolyte interphase (SEI) formation on the silicon anode’s surface is still not well understood. Herein, SEI formed from LiPF6-based carbonate electrolytes, with and without FEC, were investigated on 50 nm thick amorphous silicon thin film electrodes to understand the role of FEC on silicon electrode surface reactions. In contrast to previous work, anhydrous and anoxic techniques were used to prevent air and moisture contamination of prepared SEI films. This allowed for accurate characterization of the SEI structure and composition bymore » X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry depth profiling. These results show that FEC reduction leads to fluoride ion and LiF formation, consistent with previous computational and experimental results. Surprisingly, we also find that these species decrease lithium-ion solubility and increase the reactivity of the silicon surface. We conclude that the effectiveness of FEC at improving the Coulombic efficiency and capacity retention is due to fluoride ion formation from reduction of the electrolyte, which leads to the chemical attack of any silicon-oxide surface passivation layers and the formation of a kinetically stable SEI comprising predominately lithium fluoride and lithium oxide.« less

Artificially-built solid electrolyte interphase via surface-bonded vinylene carbonate derivative on graphite by molecular layer deposition

NASA Astrophysics Data System (ADS)

Chae, Seulki; Lee, Jeong Beom; Lee, Jae Gil; Lee, Tae-jin; Soon, Jiyong; Ryu, Ji Heon; Lee, Jin Seok; Oh, Seung M.

2017-12-01

Vinylene carbonate (VC) is attached in a ring-opened form on a graphite surface by molecular layer deposition (MLD) method, and its role as a solid electrolyte interphase (SEI) former is studied. When VC is added into the electrolyte solution of a graphite/LiNi0.5Mn1.5O4 (LNMO) full-cell, it is reductively decomposed to form an effective SEI on the graphite electrode. However, VC in the electrolyte solution has serious adverse effects due to its poor stability against electrochemical oxidation on the LNMO positive electrode. A excessive acid generation as a result of VC oxidation is observed, causing metal dissolution from the LNMO electrode. The dissolved metal ions are plated on the graphite electrode to destroy the SEI layer, eventually causing serious capacity fading and poor Coulombic efficiency. The VC derivative on the graphite surface also forms an effective SEI layer on the graphite negative electrode via reductive decomposition. The detrimental effects on the LNMO positive electrode, however, can be avoided because the bonded VC derivative on the graphite surface cannot move to the LNMO electrode. Consequently, the graphite/LNMO full-cell fabricated with the VC-attached graphite outperforms the cells without VC or with VC in the electrolyte, in terms of Coulombic efficiency and capacity retention.

Lithium Dendrite Suppression and Enhanced Interfacial Compatibility Enabled by an Ex Situ SEI on Li Anode for LAGP-Based All-Solid-State Batteries.

PubMed

Hou, Guangmei; Ma, Xiaoxin; Sun, Qidi; Ai, Qing; Xu, Xiaoyan; Chen, Lina; Li, Deping; Chen, Jinghua; Zhong, Hai; Li, Yang; Xu, Zhibin; Si, Pengchao; Feng, Jinkui; Zhang, Lin; Ding, Fei; Ci, Lijie

2018-06-06

The electrode-electrolyte interface stability is a critical factor influencing cycle performance of All-solid-state lithium batteries (ASSLBs). Here, we propose a LiF- and Li 3 N-enriched artificial solid state electrolyte interphase (SEI) protective layer on metallic lithium (Li). The SEI layer can stabilize metallic Li anode and improve the interface compatibility at the Li anode side in ASSLBs. We also developed a Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 -poly(ethylene oxide) (LAGP-PEO) concrete structured composite solid electrolyte. The symmetric Li/LAGP-PEO/Li cells with SEI-protected Li anodes have been stably cycled with small polarization at a current density of 0.05 mA cm -2 at 50 °C for nearly 400 h. ASSLB-based on SEI-protected Li anode, LAGP-PEO electrolyte, and LiFePO 4 (LFP) cathode exhibits excellent cyclic stability with an initial discharge capacity of 147.2 mA h g -1 and a retention of 96% after 200 cycles.

Computational Exploration of the Li-Electrode|Electrolyte Interface in the Presence of a Nanometer Thick Solid-Electrolyte Interphase Layer [Computational exploration of the Li-electrode|electrolyte interface complicated by a nanometer thin solid-electrolyte interphase (SEI) layer

DOE PAGES

Li, Yunsong; Leung, Kevin; Qi, Yue

2016-09-30

A nanometer thick passivation layer will spontaneously form on Li-metal in battery applications due to electrolyte reduction reactions. This passivation layer in rechargeable batteries must have “selective” transport properties: blocking electrons from attacking the electrolytes, while allowing Li + ion to pass through so the electrochemical reactions can continue. The classical description of the electrochemical reaction, Li + + e → Li 0, occurring at the Li-metal|electrolyte interface is now complicated by the passivation layer and will reply on the coupling of electronic and ionic degrees of freedom in the layer. We consider the passivation layer, called “solid electrolyte interphasemore » (SEI)”, as “the most important but the least understood in rechargeable Li-ion batteries,” partly due to the lack of understanding of its structure–property relationship. In predictive modeling, starting from the ab initio level, we find that it is an important tool to understand the nanoscale processes and materials properties governing the interfacial charge transfer reaction at the Li-metal|SEI|electrolyte interface. Here, we demonstrate pristine Li-metal surfaces indeed dissolve in organic carbonate electrolytes without the SEI layer. Based on joint modeling and experimental results, we point out that the well-known two-layer structure of SEI also exhibits two different Li + ion transport mechanisms. The SEI has a porous (organic) outer layer permeable to both Li + and anions (dissolved in electrolyte), and a dense (inorganic) inner layer facilitate only Li + transport. This two-layer/two-mechanism diffusion model suggests only the dense inorganic layer is effective at protecting Li-metal in electrolytes. This model suggests a strategy to deconvolute the structure–property relationships of the SEI by analyzing an idealized SEI composed of major components, such as Li 2CO 3, LiF, Li 2O, and their mixtures. After sorting out the Li+ ion diffusion carriers and their diffusion pathways, we design methods to accelerate the Li + ion conductivity by doping and by using heterogonous structure designs. We will predict the electron tunneling barriers and connect them with measurable first cycle irreversible capacity loss. We note that the SEI not only affects Li + and e – transport, but it can also impose a potential drop near the Li-metal|SEI interface. Our challenge is to fully describe the electrochemical reactions at the Li -metal|SEI|electrolyte interface. This will be the subject of ongoing efforts.« less

Computational Exploration of the Li-Electrode|Electrolyte Interface in the Presence of a Nanometer Thick Solid-Electrolyte Interphase Layer [Computational exploration of the Li-electrode|electrolyte interface complicated by a nanometer thin solid-electrolyte interphase (SEI) layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yunsong; Leung, Kevin; Qi, Yue

A nanometer thick passivation layer will spontaneously form on Li-metal in battery applications due to electrolyte reduction reactions. This passivation layer in rechargeable batteries must have “selective” transport properties: blocking electrons from attacking the electrolytes, while allowing Li + ion to pass through so the electrochemical reactions can continue. The classical description of the electrochemical reaction, Li + + e → Li 0, occurring at the Li-metal|electrolyte interface is now complicated by the passivation layer and will reply on the coupling of electronic and ionic degrees of freedom in the layer. We consider the passivation layer, called “solid electrolyte interphasemore » (SEI)”, as “the most important but the least understood in rechargeable Li-ion batteries,” partly due to the lack of understanding of its structure–property relationship. In predictive modeling, starting from the ab initio level, we find that it is an important tool to understand the nanoscale processes and materials properties governing the interfacial charge transfer reaction at the Li-metal|SEI|electrolyte interface. Here, we demonstrate pristine Li-metal surfaces indeed dissolve in organic carbonate electrolytes without the SEI layer. Based on joint modeling and experimental results, we point out that the well-known two-layer structure of SEI also exhibits two different Li + ion transport mechanisms. The SEI has a porous (organic) outer layer permeable to both Li + and anions (dissolved in electrolyte), and a dense (inorganic) inner layer facilitate only Li + transport. This two-layer/two-mechanism diffusion model suggests only the dense inorganic layer is effective at protecting Li-metal in electrolytes. This model suggests a strategy to deconvolute the structure–property relationships of the SEI by analyzing an idealized SEI composed of major components, such as Li 2CO 3, LiF, Li 2O, and their mixtures. After sorting out the Li+ ion diffusion carriers and their diffusion pathways, we design methods to accelerate the Li + ion conductivity by doping and by using heterogonous structure designs. We will predict the electron tunneling barriers and connect them with measurable first cycle irreversible capacity loss. We note that the SEI not only affects Li + and e – transport, but it can also impose a potential drop near the Li-metal|SEI interface. Our challenge is to fully describe the electrochemical reactions at the Li -metal|SEI|electrolyte interface. This will be the subject of ongoing efforts.« less

Ab initio molecular dynamics simulations of the initial stages of solid-electrolyte interphase formation on lithium ion battery graphitic anodes.

PubMed

Leung, Kevin; Budzien, Joanne L

2010-07-07

The decomposition of ethylene carbonate (EC) during the initial growth of solid-electrolyte interphase (SEI) films at the solvent-graphitic anode interface is critical to lithium ion battery operations. Ab initio molecular dynamics simulations of explicit liquid EC/graphite interfaces are conducted to study these electrochemical reactions. We show that carbon edge terminations are crucial at this stage, and that achievable experimental conditions can lead to surprisingly fast EC breakdown mechanisms, yielding decomposition products seen in experiments but not previously predicted.

Nanoscale imaging of fundamental Li battery chemistry: solid-electrolyte interphase formation and preferential growth of lithium metal nanoclusters

DOE PAGES

Sacci, Robert L; Black, Jennifer M.; Wisinger, Nina; ...

2015-02-23

The performance characteristics of Li-ion batteries are intrinsically linked to evolving nanoscale interfacial electrochemical reactions. To probe the mechanisms of solid electrolyte interphase formation and Li electrodeposition from a standard battery electrolyte, we use in situ electrochemical scanning transmission electron microscopy for controlled potential sweep-hold electrochemical measurements with simultaneous BF and ADF STEM image acquisition. Through a combined quantitative electrochemical measurement and quantitative STEM imaging approach, based upon electron scattering theory, we show that chemically sensitive ADF STEM imaging can be used to estimate the density of evolving SEI constituents and distinguish contrast mechanisms of Li-bearing components in the liquidmore » cell.« less

Component-/structure-dependent elasticity of solid electrolyte interphase layer in Li-ion batteries: Experimental and computational studies

NASA Astrophysics Data System (ADS)

Shin, Hosop; Park, Jonghyun; Han, Sangwoo; Sastry, Ann Marie; Lu, Wei

2015-03-01

The mechanical instability of the Solid Electrolyte Interphase (SEI) layer in lithium ion (Li-ion) batteries causes significant side reactions resulting in Li-ion consumption and cell impedance rise by forming further SEI layers, which eventually leads to battery capacity fade and power fade. In this paper, the composition-/structure-dependent elasticity of the SEI layer is investigated via Atomic Force Microscopy (AFM) measurements coupled with X-ray Photoelectron Spectroscopy (XPS) analysis, and atomistic calculations. It is observed that the inner layer is stiffer than the outer layer. The measured Young's moduli are mostly in the range of 0.2-4.5 GPa, while some values above 80 GPa are also observed. This wide variation of the observed elastic modulus is elucidated by atomistic calculations with a focus on chemical and structural analysis. The numerical analysis shows the Young's moduli range from 2.4 GPa to 58.1 GPa in the order of the polymeric, organic, and amorphous inorganic components. The crystalline inorganic component (LiF) shows the highest value (135.3 GPa) among the SEI species. This quantitative observation on the elasticity of individual components of the SEI layer must be essential to analyzing the mechanical behavior of the SEI layer and to optimizing and controlling it.

Modeling Solvation Structure and Charge Transfer at the Solid Electrolyte Interphase for Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Raguette, Lauren Elizabeth

Rechargeable lithium-ion battery technology is providing a revolution in energy storage. However, in order to fully realize this revolution, a better understanding is required of both the bulk properties of battery materials and their interfaces. This work endeavors to use classical molecular dynamics (MD) to investigate the electrochemical interfaces present in lithium-ion batteries to understand the impact of chemical reactions on ion transport. When batteries containing cyclic carbonates and lithium salts are charge cycled, both species can react with the electrodes to form complex solid mixtures at the electrode/electrolyte interface, known as a solid electrolyte interphase (SEI). While decades of experiments have yielded significant insights into the structure of these films and their chemical composition, there remains a lack of connection between the properties of the films and observed ion transport when interfaced with the electrolyte. A combination of MD and enhanced sampling methods will be presented to elucidate the link between the SEI, containing mixtures of dilithium ethylene dicarbonate (Li2EDC), lithium fluoride, and lithium carbonate, and battery performance. By performing extensive free energy calculations, clarity is provided to the impact of ion desolvation on the measured resistance to ion transport within lithium ion batteries.

Developing Battery Computer Aided Engineering Tools for Military Vehicles

DTIC Science & Technology

2013-12-01

Task 1.b Modeling Bullet penetration. The purpose of Task 1.a was to extend the chemical kinetics models of CoO2 cathodes developed under CAEBAT to...lithium- ion batteries. The new finite element model captures swelling/shrinking in cathodes /anodes due to thermal expansion and lithium intercalation...Solid Electrolyte Interphase (SEI) layer decomposition 80 2 Anode — electrolyte 100 3 Cathode — electrolyte 130 4 Electrolyte decomposition 180

Designer interphases for the lithium-oxygen electrochemical cell

PubMed Central

Choudhury, Snehashis; Wan, Charles Tai-Chieh; Al Sadat, Wajdi I.; Tu, Zhengyuan; Lau, Sampson; Zachman, Michael J.; Kourkoutis, Lena F.; Archer, Lynden A.

2017-01-01

An electrochemical cell based on the reversible oxygen reduction reaction: 2Li+ + 2e− + O2 ↔ Li2O2, provides among the most energy dense platforms for portable electrical energy storage. Such Lithium-Oxygen (Li-O2) cells offer specific energies competitive with fossil fuels and are considered promising for electrified transportation. Multiple, fundamental challenges with the cathode, anode, and electrolyte have limited practical interest in Li-O2 cells because these problems lead to as many practical shortcomings, including poor rechargeability, high overpotentials, and specific energies well below theoretical expectations. We create and study in-situ formation of solid-electrolyte interphases (SEIs) based on bromide ionomers tethered to a Li anode that take advantage of three powerful processes for overcoming the most stubborn of these challenges. The ionomer SEIs are shown to protect the Li anode against parasitic reactions and also stabilize Li electrodeposition during cell recharge. Bromine species liberated during the anchoring reaction also function as redox mediators at the cathode, reducing the charge overpotential. Finally, the ionomer SEI forms a stable interphase with Li, which protects the metal in high Gutmann donor number liquid electrolytes. Such electrolytes have been reported to exhibit rare stability against nucleophilic attack by Li2O2 and other cathode reaction intermediates, but also react spontaneously with Li metal anodes. We conclude that rationally designed SEIs able to regulate transport of matter and ions at the electrolyte/anode interface provide a promising platform for addressing three major technical barriers to practical Li-O2 cells. PMID:28439557

Auger Electrons as Probes for Composite Micro- and Nano- structured Materials: Application to Solid Electrolyte Interphases in Graphite and Silicon-Graphite Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalaga, Kaushik; Shkrob, Ilya A.; Haasch, Richard T.

In this study, Auger electron spectroscopy (AES) combined with ion sputtering profilometry, Xray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) have been used in a complementary fashion to examine chemical and microstructural changes in graphite (Gr) and silicon/graphite (Si/Gr) blends contained in the negative electrodes of lithium-ion cells. We demonstrate how AES can be used to characterize morphology of the solid-electrolyte interphase (SEI) deposits in such heterogeneous media, complementing well-established methods, such as XPS and SEM. In this way we demonstrate that the SEI does not consist of uniformly thick layers on the graphite and silicon; the thickness ofmore » the SEI layers in cycle-life aged electrodes follows an exponential distribution with a mean of ca. 13 nm for the graphite and ca. 20-25 nm for the silicon nanoparticles (with a crystalline core of 50-70 nm in diameter). Furthermore, a “sticky-sphere” model, in which Si nanoparticles are covered with a layer of polymer binder (that is replaced by the SEI during cycling) of variable thickness is introduced to account for the features observed.« less

Auger Electrons as Probes for Composite Micro- and Nano- structured Materials: Application to Solid Electrolyte Interphases in Graphite and Silicon-Graphite Electrodes

DOE PAGES

Kalaga, Kaushik; Shkrob, Ilya A.; Haasch, Richard T.; ...

2017-10-05

In this study, Auger electron spectroscopy (AES) combined with ion sputtering profilometry, Xray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) have been used in a complementary fashion to examine chemical and microstructural changes in graphite (Gr) and silicon/graphite (Si/Gr) blends contained in the negative electrodes of lithium-ion cells. We demonstrate how AES can be used to characterize morphology of the solid-electrolyte interphase (SEI) deposits in such heterogeneous media, complementing well-established methods, such as XPS and SEM. In this way we demonstrate that the SEI does not consist of uniformly thick layers on the graphite and silicon; the thickness ofmore » the SEI layers in cycle-life aged electrodes follows an exponential distribution with a mean of ca. 13 nm for the graphite and ca. 20-25 nm for the silicon nanoparticles (with a crystalline core of 50-70 nm in diameter). Furthermore, a “sticky-sphere” model, in which Si nanoparticles are covered with a layer of polymer binder (that is replaced by the SEI during cycling) of variable thickness is introduced to account for the features observed.« less

Prediction of battery storage ageing and solid electrolyte interphase property estimation using an electrochemical model

NASA Astrophysics Data System (ADS)

Ashwin, T. R.; Barai, A.; Uddin, K.; Somerville, L.; McGordon, A.; Marco, J.

2018-05-01

Ageing prediction is often complicated due to the interdependency of ageing mechanisms. Research has highlighted that storage ageing is not linear with time. Capacity loss due to storing the battery at constant temperature can shed more light on parametrising the properties of the Solid Electrolyte Interphase (SEI); the identification of which, using an electrochemical model, is systematically addressed in this work. A new methodology is proposed where any one of the available storage ageing datasets can be used to find the property of the SEI layer. A sensitivity study is performed with different molecular mass and densities which are key parameters in modelling the thickness of the SEI deposit. The conductivity is adjusted to fine tune the rate of capacity fade to match experimental results. A correlation is fitted for the side reaction variation to capture the storage ageing in the 0%-100% SoC range. The methodology presented in this paper can be used to predict the unknown properties of the SEI layer which is difficult to measure experimentally. The simulation and experimental results show that the storage ageing model shows good accuracy for the cases at 50% and 90% and an acceptable agreement at 20% SoC.

Connecting the irreversible capacity loss in Li-ion batteries with the electronic insulating properties of solid electrolyte interphase (SEI) components.

DOE PAGES

Leung, Kevin; Lin, Yu -Xiao; Liu, Zhe; ...

2016-01-01

The formation and continuous growth of a solid electrolyte interphase (SEI) layer are responsible for the irreversible capacity loss of batteries in the initial and subsequent cycles, respectively. In this article, the electron tunneling barriers from Li metal through three insulating SEI components, namely Li 2CO 3, LiF and Li 3PO 4, are computed by density function theory (DFT) approaches. Based on electron tunneling theory, it is estimated that sufficient to block electron tunneling. It is also found that the band gap decreases under tension while the work function remains the same, and thus the tunneling barrier decreases under tensionmore » and increases under compression. A new parameter, η, characterizing the average distances between anions, is proposed to unify the variation of band gap with strain under different loading conditions into a single linear function of η. An analytical model based on the tunneling results is developed to connect the irreversible capacity loss, due to the Li ions consumed in forming these SEI component layers on the surface of negative electrodes. As a result, the agreement between the model predictions and experimental results suggests that only the initial irreversible capacity loss is due to the self-limiting electron tunneling property of the SEI.« less

New Insights on the Structure of Electrochemically Deposited Lithium Metal and Its Solid Electrolyte Interphases via Cryogenic TEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xuefeng; Zhang, Minghao; Alvarado, Judith

Lithium metal has been considered as the “holy grail” anode material for rechargeable batteries though the dendritic growth and low Coulombic efficiency (CE) have crippled its practical use for decades. Its high chemical reactivity and low stability make it difficult to explore the intrinsic chemical and physical properties of the electrochemically deposited lithium (EDLi) and its accompanied solid electrolyte interphase (SEI). To prevent the dendritic growth and enhance the electrochemical reversibility, it is crucial to understand the nano- and meso- structures of EDLi. However, Li metal is very sensitive to beam damage and has low contrast for commonly used characterizationmore » techniques such as electron microscopy. Inspired by biological imaging techniques, this work demonstrates the power of cryogenic (cryo)- electron microscopy to reveal the detailed structure of EDLi and the SEI composition at the nano scale while minimizing beam damage during imaging. Surprisingly, the results show that the nucleation dominated EDLi (five minutes at 0.5 mA cm-2) is amorphous while there is some crystalline LiF present in the SEI. The EDLi grown from various electrolytes with different additives exhibits distinctive surface properties. Consequently, these results highlight the importance of the SEI and its relationship with the CE. Our findings not only illustrate the capabilities of cryogenic microscopy for beam (thermal)-sensitive materials, but it yields crucial structural information of the EDLi evolution with and without electrolyte additives.« less

Active Mechanism of the Interphase Film-Forming Process for an Electrolyte Based on a Sulfolane Solvent and a Chelato-Borate Complexe.

PubMed

Li, Chunlei; Wang, Peng; Li, Shiyou; Zhao, Dongni; Zhao, Qiuping; Liu, Haining; Cui, Xiao-Ling

2018-06-14

Electrolytes based on sulfolane (SL) solvents and lithium bis(oxalato)borate (LiBOB) chelato-borate complexes have been reported many times for use in advanced lithium-ion batteries due to their many advantages. This study aims to clarify the active mechanism of the interphase film-forming process to optimize the properties of these batteries by experimental analysis and theoretical calculations. The results indicate that the self-repairing film-forming process during the first cycle is divided into three stages: the initial film formation with an electric field force of ~1.80 V, the further growth of the preformation solid electrolyte interface (SEI) film at ~1.73 V, and the final formation of a complete SEI film at a potential below 0.7 V. Additionally, we can deduce that the decomposition of LiBOB and SL occurs throughout nearly the entire process of the formation of the SEI film. The decomposition product of BOB- anions tends to form films with an irregular structure, while the decomposition product of SL is in favor of the formation of a uniform SEI film.

Interfacial reactions in lithium batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Zonghai; Amine, Rachid; Ma, Zi-Feng

The lithium-ion battery was first commercially introduced by Sony Corporation on 1991 using LiCoO 2 as the cathode material and mesocarbon microbeads as the anode material. After continuous research and development for 25 years, lithium-ion batteries have been the dominant energy storage devices for modern portable electronics, as well as for the emerging application for electric vehicles and smart grids. It has been a common sense that the success of lithium-ion technologies is rooted to the existence of a solid electrolyte interphase (SEI) that kinetically suppresses the parasitic reactions between the lithiated 2 graphitic anodes and the carbonate-based non-aqueous electrolytes.more » Recently, major attention has been paid to the importance of a similar passivation/protection layer on the surface of cathode materials, aiming for rational design of high-energy-density lithiumion batteries with extended cycle/calendar life. In this article, the physical model of the solid electrolyte interphase, as well as the recent research effort to under the nature and role SEI are summarized, and future perspectives on this important research field will also be presented.« less

Interfacial reactions in lithium batteries

DOE PAGES

Chen, Zonghai; Amine, Rachid; Ma, Zi-Feng; ...

2017-06-29

The lithium-ion battery was first commercially introduced by Sony Corporation on 1991 using LiCoO 2 as the cathode material and mesocarbon microbeads as the anode material. After continuous research and development for 25 years, lithium-ion batteries have been the dominant energy storage devices for modern portable electronics, as well as for the emerging application for electric vehicles and smart grids. It has been a common sense that the success of lithium-ion technologies is rooted to the existence of a solid electrolyte interphase (SEI) that kinetically suppresses the parasitic reactions between the lithiated 2 graphitic anodes and the carbonate-based non-aqueous electrolytes.more » Recently, major attention has been paid to the importance of a similar passivation/protection layer on the surface of cathode materials, aiming for rational design of high-energy-density lithiumion batteries with extended cycle/calendar life. In this article, the physical model of the solid electrolyte interphase, as well as the recent research effort to under the nature and role SEI are summarized, and future perspectives on this important research field will also be presented.« less

In Situ Potentiodynamic Analysis of the Electrolyte/Silicon Electrodes Interface Reactions - A Sum Frequency Generation Vibrational Spectroscopy Study

DOE PAGES

Horowitz, Yonatan; Han, Hui-Ling; Ross, Philip N.; ...

2015-12-11

The key factor in long-term use of batteries is the formation of an electrically insulating solid layer that allows lithium ion transport but stops further electrolyte redox reactions on the electrode surface, hence solid electrolyte interphase (SEI). In this paper, we have studied a common electrolyte, 1.0 M LiPF 6/ethylene carbonate (EC)/diethyl carbonate (DEC), reduction products on crystalline silicon (Si) electrodes in a lithium (Li) half-cell system under reaction conditions. We employed in situ sum frequency generation vibrational spectroscopy (SFG-VS) with interface sensitivity in order to probe the molecular composition of the SEI surface species under various applied potentials wheremore » electrolyte reduction is expected. We found that, with a Si(100)-hydrogen terminated wafer, a Si-ethoxy (Si-OC 2H 5) surface intermediate forms due to DEC decomposition. Our results suggest that the SEI surface composition varies depending on the termination of Si surface, i.e., the acidity of the Si surface. We provide the evidence of specific chemical composition of the SEI on the anode surface under reaction conditions. This supports an electrochemical electrolyte reduction mechanism in which the reduction of the DEC molecule to an ethoxy moiety plays a key role. Finally, these findings shed new light on the formation mechanism of SEI on Si anodes in particular and on SEI formation in general.« less

Controlling Solid-Electrolyte-Interphase Layer by Coating P-Type Semiconductor NiOx on Li4Ti5O12 for High-Energy-Density Lithium-Ion Batteries.

PubMed

Jo, Mi Ru; Lee, Gi-Hyeok; Kang, Yong-Mook

2015-12-23

Li4Ti5O12 is a promising anode material for rechargeable lithium batteries due to its well-known zero strain and superb kinetic properties. However, Li4Ti5O12 shows low energy density above 1 V vs Li(+)/Li. In order to improve the energy density of Li4Ti5O12, its low-voltage intercalation behavior beyond Li7Ti5O12 has been demonstrated. In this approach, the extended voltage window is accompanied by the decomposition of liquid electrolyte below 1 V, which would lead to an excessive formation of solid electrolyte interphase (SEI) films. We demonstrate an effective method to improve electrochemical performance of Li4Ti5O12 in a wide working voltage range by coating Li4Ti5O12 powder with p-type semiconductor NiOx. Ex situ XRD, XPS, and FTIR results show that the NiOx coating suppresses electrochemical reduction reactions of the organic SEI components to Li2CO3, thereby promoting reversibility of the charge/discharge process. The NiOx coating layer offers a stable SEI film for enhanced rate capability and cyclability.

Tris(trimethylsilyl) Phosphite as an Efficient Electrolyte Additive To Improve the Surface Stability of Graphite Anodes.

PubMed

Yim, Taeeun; Han, Young-Kyu

2017-09-27

Tris(trimethylsilyl) phosphite (TMSP) has received considerable attention as a functional additive for various cathode materials in lithium-ion batteries, but the effect of TMSP on the surface stability of a graphite anode has not been studied. Herein, we demonstrate that TMSP serves as an effective solid electrolyte interphase (SEI)-forming additive for graphite anodes in lithium-ion batteries (LIBs). TMSP forms SEI layers by chemical reactions between TMSP and a reductively decomposed ethylene carbonate (EC) anion, which is strikingly different from the widely known mechanism of the SEI-forming additives. TMSP is stable under cathodic polarization, but it reacts chemically with radical anion intermediates derived from the electrochemical reduction of the carbonate solvents to generate a stable SEI layer. These TMSP-derived SEI layers improve the interfacial stability of the graphite anode, resulting in a retention of 96.8% and a high Coulombic efficiency of 95.2%. We suggest the use of TMSP as a functional additive that effectively stabilizes solid electrolyte interfaces of both the anode and cathode in lithium-ion batteries.

Solid State Multinuclear Magnetic Resonance Investigation of Electrolyte Decomposition Products on Lithium Ion Electrodes

NASA Technical Reports Server (NTRS)

DeSilva, J .H. S. R.; Udinwe, V.; Sideris, P. J.; Smart, M. C.; Krause, F. C.; Hwang, C.; Smith, K. A.; Greenbaum, S. G.

2012-01-01

Solid electrolyte interphase (SEI) formation in lithium ion cells prepared with advanced electrolytes is investigated by solid state multinuclear (7Li, 19F, 31P) magnetic resonance (NMR) measurements of electrode materials harvested from cycled cells subjected to an accelerated aging protocol. The electrolyte composition is varied to include the addition of fluorinated carbonates and triphenyl phosphate (TPP, a flame retardant). In addition to species associated with LiPF6 decomposition, cathode NMR spectra are characterized by the presence of compounds originating from the TPP additive. Substantial amounts of LiF are observed in the anodes as well as compounds originating from the fluorinated carbonates.

Multiprobe Study of the Solid Electrolyte Interphase on Silicon-Based Electrodes in Full-Cell Configuration

PubMed Central

Moreau, P.; De Vito, E.; Quazuguel, L.; Boniface, M.; Bordes, A.; Rudisch, C.; Bayle-Guillemaud, P.; Guyomard, D.

2016-01-01

The failure mechanism of silicon-based electrodes has been studied only in a half-cell configuration so far. Here, a combination of 7Li, 19F MAS NMR, XPS, TOF-SIMS, and STEM-EELS, provides an in-depth characterization of the solid electrolyte interphase (SEI) formation on the surface of silicon and its evolution upon aging and cycling with LiNi1/3Mn1/3Co1/3O2 as the positive electrode in a full Li-ion cell configuration. This multiprobe approach indicates that the electrolyte degradation process observed in the case of full Li-ion cells exhibits many similarities to what has been observed in the case of half-cells in previous works, in particular during the early stages of the cycling. Like in the case of Si/Li half-cells, the development of the inorganic part of the SEI mostly occurs during the early stage of cycling while an incessant degradation of the organic solvents of the electrolyte occurs upon cycling. However, for extended cycling, all the lithium available for cycling is consumed because of parasitic reactions and is either trapped in an intermediate part of the SEI or in the electrolyte. This nevertheless does not prevent the further degradation of the organic electrolyte solvents, leading to the formation of lithium-free organic degradation products at the extreme surface of the SEI. At this point, without any available lithium left, the cell cannot function properly anymore. Cycled positive and negative electrodes do not show any sign of particles disconnection or clogging of their porosity by electrolyte degradation products and can still function in half-cell configuration. The failure mechanism for full Li-ion cells appears then very different from that known for half-cells and is clearly due to a lack of cyclable lithium because of parasitic reactions occurring before the accumulation of electrolyte degradation products clogs the porosity of the composite electrode or disconnects the active material particles. PMID:27212791

Suppression of Dendritic Lithium Growth by in Situ Formation of a Chemically Stable and Mechanically Strong Solid Electrolyte Interphase.

PubMed

Wan, Guojia; Guo, Feihu; Li, Hui; Cao, Yuliang; Ai, Xinping; Qian, Jiangfeng; Li, Yangxing; Yang, Hanxi

2018-01-10

The growth and proliferation of Li dendrites during repeated Li cycling has long been a crucial issue that hinders the development of secondary Li-metal batteries. Building a stable and robust solid state electrolyte interphase (SEI) on the Li-anode surface is regarded as a promising strategy to overcome the dendrite issues. In this work, we report a simple strategy to engineer the interface chemistry of Li-metal anodes by using tiny amounts of dimethyl sulfate (DMS, C 2 H 6 SO 4 ) as the SEI-forming additive. With the preferential reduction of DMS, an SEI layer composed of Li 2 S/Li 2 O forms on the Li surface. This inorganic SEI layer features high structural modulus and low interfacial resistant, enabling a dense and dendrite-free Li deposition as evidenced by scanning electron microscopy, atomic force microscopy, and in situ optical images. In addition, this SEI layer can prevent the deposited Li from direct contact with corrosive electrolytes, thus rendering an improved cycling stability of Li anodes with an average Coulombic efficiency of 97% for up to 150 cycles. When the DMS additive is introduced into a Li/NCM full cell, the cycle life of Li-metal batteries can be also improved significantly. This work demonstrates a feasible route to suppress Li dendrite growth by designing appropriate film-forming additives to regulate the interfacial properties of the SEI layer, and also the sulfonyl-based derivatives revealed in this work represent a large variety of new film-forming molecules, providing a broad selectivity for constructing high efficiency and cycle-stable Li anodes to address the intrinsic problems of rechargeable Li-metal batteries.

Morphological evolution of carbon nanofibers encapsulating SnCo alloys and its effect on growth of the solid electrolyte interphase layer.

PubMed

Shin, Jungwoo; Ryu, Won-Hee; Park, Kyu-Sung; Kim, Il-Doo

2013-08-27

Two distinctive one-dimensional (1-D) carbon nanofibers (CNFs) encapsulating irregularly and homogeneously segregated SnCo nanoparticles were synthesized via electrospinning of polyvinylpyrrolidone (PVP) and polyacrylonitrile (PAN) polymers containing Sn-Co acetate precursors and subsequent calcination in reducing atmosphere. CNFs synthesized with PVP, which undergoes structural degradation of the polymer during carbonization processes, exhibited irregular segregation of heterogeneous alloy particles composed of SnCo, Co3Sn2, and SnO with a size distribution of 30-100 nm. Large and exposed multiphase SnCo particles in PVP-driven amorphous CNFs (SnCo/PVP-CNFs) kept decomposing liquid electrolyte and were partly detached from CNFs during cycling, leading to a capacity fading at the earlier cycles. The closer study of solid electrolyte interphase (SEI) layers formed on the CNFs reveals that the gradual growth of fiber radius due to continuous increment of SEI layer thickness led to capacity fading. In contrast, SnCo particles in PAN-driven CNFs (SnCo/PAN-CNFs) showed dramatically reduced crystallite sizes (<10 nm) of single phase SnCo nanoparticles which were entirely embedded in dense, semicrystalline, and highly conducting 1-D carbon matrix. The growth of SEI layer was limited and saturated during cycling. As a result, SnCo/PAN-CNFs showed much improved cyclability (97.9% capacity retention) and lower SEI layer thickness (86 nm) after 100 cycles compared to SnCo/PVP-CNFs (capacity retention, 71.9%; SEI layer thickness, 593 nm). This work verifies that the thermal behavior of carbon precursor is highly responsible for the growth mechanism of SEI layer accompanied with particles detachment and cyclability of alloy particle embedded CNFs.

Artificial Solid Electrolyte Interphase-Protected LixSi Nanoparticles: An Efficient and Stable Prelithiation Reagent for Lithium-Ion Batteries.

PubMed

Zhao, Jie; Lu, Zhenda; Wang, Haotian; Liu, Wei; Lee, Hyun-Wook; Yan, Kai; Zhuo, Denys; Lin, Dingchang; Liu, Nian; Cui, Yi

2015-07-08

Prelithiation is an important strategy to compensate for lithium loss in lithium-ion batteries, particularly during the formation of the solid electrolyte interphase (SEI) from reduced electrolytes in the first charging cycle. We recently demonstrated that LixSi nanoparticles (NPs) synthesized by thermal alloying can serve as a high-capacity prelithiation reagent, although their chemical stability in the battery processing environment remained to be improved. Here we successfully developed a surface modification method to enhance the stability of LixSi NPs by exploiting the reduction of 1-fluorodecane on the LixSi surface to form a continuous and dense coating through a reaction process similar to SEI formation. The coating, consisting of LiF and lithium alkyl carbonate with long hydrophobic carbon chains, serves as an effective passivation layer in the ambient environment. Remarkably, artificial-SEI-protected LixSi NPs show a high prelithiation capacity of 2100 mA h g(-1) with negligible capacity decay in dry air after 5 days and maintain a high capacity of 1600 mA h g(-1) in humid air (∼10% relative humidity). Silicon, tin, and graphite were successfully prelithiated with these NPs to eliminate the irreversible first-cycle capacity loss. The use of prelithiation reagents offers a new approach to realize next-generation high-energy-density lithium-ion batteries.

Lithium dendrite and solid electrolyte interphase investigation using OsO4

NASA Astrophysics Data System (ADS)

Zier, Martin; Scheiba, Frieder; Oswald, Steffen; Thomas, Jürgen; Goers, Dietrich; Scherer, Torsten; Klose, Markus; Ehrenberg, Helmut; Eckert, Jürgen

2014-11-01

Osmium tetroxide (OsO4) staining, commonly used to enhance scattering contrast in electron microscopy of biologic tissue and polymer blends, has been adopted for studies of graphite anodes in lithium-ion batteries. OsO4 shows a coordinated reaction with components of the solid electrolyte interphase (SEI) and lithium dendrites, thereby increasing material contrast for scanning electron microscopy investigations. Utilizing the high affinity of lithium metal to react with osmium tetroxide it was possible to localize even small lithium deposits on graphite electrodes. In spite of their reaction with the OsO4 fume, the lithium dendrite morphology remains almost untouched by the staining procedure, offering information on the dendrite growth process. Correlating the quantity of osmium detected with the amount of residual ("dead") lithium of a discharged electrode, it was possible to obtain a practical measure for lithium plating and stripping efficiencies. EDX mappings allowed for a localization of electrochemically stripped lithium dendrites by their residual stained SEI shells. Cross sections, prepared by focused ion beam (FIB) of cycled graphite electrodes treated with OsO4, revealed important information about deposition and distribution of metallic lithium and the electrolyte reduction layer across the electrode.

The Role of Cesium Cation in Controlling Interphasial Chemistry on Graphite Anode in Propylene Carbonate-Rich Electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiang, Hongfa; Mei, Donghai; Yan, Pengfei

2015-09-10

Propylene carbonate (PC) is seldom used in lithium-ion batteries (LIBs) due to its sustained co-intercalation into graphene structure and the eventual graphite exfoliation, despite potential advantages it brings, such as wider liquid range and lower cost. Here we discover that cesium cation (Cs+), originally used to suppress dendrite growth of Li metal anode, directs the formation of solid electrolyte interphase (SEI) on graphitic anode in PC-rich electrolytes through preferential solvation. Effective suppression of PC-decomposition and graphite-exfoliation was achieved when the ratio of ethylene carbonate (EC)/PC in electrolytes was so adjusted that the reductive decomposition of Cs+-(EC)m (1≤m≤2) complex precedes thatmore » of Li+-(PC)n (3≤n≤5). The interphase directed by Cs+ is stable, ultrathin and compact, leading to significant improvements in LIB performances. In a broader context, the accurate tailoring of SEI chemical composition by introducing a new solvation center represents a fundamental breakthrough in manipulating interfacial reactions processes that once were elusive.« less

Artificial solid electrolyte interphase for aqueous lithium energy storage systems

PubMed Central

Zhi, Jian; Yazdi, Alireza Zehtab; Valappil, Gayathri; Haime, Jessica; Chen, Pu

2017-01-01

Aqueous lithium energy storage systems address environmental sustainability and safety issues. However, significant capacity fading after repeated cycles of charge-discharge and during float charge limit their practical application compared to their nonaqueous counterparts. We introduce an artificial solid electrolyte interphase (SEI) to the aqueous systems and report the use of graphene films as an artificial SEI (G-SEI) that substantially enhance the overall performance of an aqueous lithium battery and a supercapacitor. The thickness (1 to 50 nm) and the surface area (1 cm2 to 1 m2) of the G-SEI are precisely controlled on the LiMn2O4-based cathode using the Langmuir trough–based techniques. The aqueous battery with a 10-nm-thick G-SEI exhibits a discharge capacity as high as 104 mA·hour g−1 after 600 cycles and a float charge current density as low as 1.03 mA g−1 after 1 day, 26% higher (74 mA·hour g−1) and 54% lower (1.88 mA g−1) than the battery without the G-SEI, respectively. We propose that the G-SEI on the cathode surface simultaneously suppress the structural distortion of the LiMn2O4 (the Jahn-Teller distortion) and the oxidation of conductive carbon through controlled diffusion of Li+ and restricted permeation of gases (O2 and COx), respectively. The G-SEI on both small (~1 cm2 in 1.15 mA·hour cell) and large (~9 cm2 in 7 mA·hour cell) cathodes exhibit similar property enhancement, demonstrating excellent potential for scale-up and manufacturing. PMID:28913426

Lithium loss in the solid electrolyte interphase: Lithium quantification of aged lithium ion battery graphite electrodes by means of laser ablation inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectroscopy

NASA Astrophysics Data System (ADS)

Schwieters, Timo; Evertz, Marco; Mense, Maximilian; Winter, Martin; Nowak, Sascha

2017-07-01

In this work we present a new method using LA-ICP-MS to quantitatively determine the lithium content in aged graphite electrodes of a lithium ion battery (LIB) by performing total depth profiling. Matrix matched solid external standards are prepared using a solid doping approach to avoid elemental fractionation effects during the measurement. The results are compared and matched to the established ICP-OES technique for bulk quantification after performing a microwave assisted acid digestion. The method is applied to aged graphite electrodes in order to determine the lithium immobilization (= "Li loss") in the solid electrolyte interphase after the first cycle of formation. For this, different samples including a reference sample are created to obtain varying thicknesses of the SEI covering the electrode particles. By applying defined charging voltages, an initial lithiation process is performed to obtain specific graphite intercalation compounds (GICs, with target stoichiometries of LiC30, LiC18, LiC12 and LiC6). Afterwards, the graphite electrode is completely discharged to obtain samples without mobile, thus active lithium in its lattice. Taking the amount of lithium into account which originates from the residues of the LiPF6 (dissolved in the carbon components containing electrolyte), it is possible to subtract the amount of lithium in the SEI.

Ionic liquid electrolytes for Li-air batteries: lithium metal cycling.

PubMed

Grande, Lorenzo; Paillard, Elie; Kim, Guk-Tae; Monaco, Simone; Passerini, Stefano

2014-05-08

In this work, the electrochemical stability and lithium plating/stripping performance of N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) are reported, by investigating the behavior of Li metal electrodes in symmetrical Li/electrolyte/Li cells. Electrochemical impedance spectroscopy measurements and galvanostatic cycling at different temperatures are performed to analyze the influence of temperature on the stabilization of the solid electrolyte interphase (SEI), showing that TFSI-based ionic liquids (ILs) rank among the best candidates for long-lasting Li-air cells.

Ionic Liquid Electrolytes for Li–Air Batteries: Lithium Metal Cycling

PubMed Central

Grande, Lorenzo; Paillard, Elie; Kim, Guk-Tae; Monaco, Simone; Passerini, Stefano

2014-01-01

In this work, the electrochemical stability and lithium plating/stripping performance of N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) are reported, by investigating the behavior of Li metal electrodes in symmetrical Li/electrolyte/Li cells. Electrochemical impedance spectroscopy measurements and galvanostatic cycling at different temperatures are performed to analyze the influence of temperature on the stabilization of the solid electrolyte interphase (SEI), showing that TFSI-based ionic liquids (ILs) rank among the best candidates for long-lasting Li–air cells. PMID:24815072

Building Organic/Inorganic Hybrid Interphases for Fast Interfacial Transport in Rechargeable Metal Batteries.

PubMed

Zhao, Qing; Tu, Zhengyuan; Wei, Shuya; Zhang, Kaihang; Choudhury, Snehashis; Liu, Xiaotun; Archer, Lynden A

2018-01-22

We report a facile in situ synthesis that utilizes readily accessible SiCl 4 cross-linking chemistry to create durable hybrid solid-electrolyte interphases (SEIs) on metal anodes. Such hybrid SEIs composed of Si-interlinked OOCOR molecules that host LiCl salt exhibit fast charge-transfer kinetics and as much as five-times higher exchange current densities, in comparison to their spontaneously formed analogues. Electrochemical analysis and direct optical visualization of Li and Na deposition in symmetric Li/Li and Na/Na cells show that the hybrid SEI provides excellent morphological control at high current densities (3-5 mA cm -2 ) for Li and even for notoriously unstable Na metal anodes. The fast interfacial transport attributes of the SEI are also found to be beneficial for Li-S cells and stable electrochemical cycling was achieved in galvanostatic studies at rates as high as 2 C. Our work therefore provides a promising approach towards rational design of multifunctional, elastic SEIs that overcome the most serious limitations of spontaneously formed interphases on high-capacity metal anodes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Additive effect on reductive decomposition and binding of carbonate-based solvent toward solid electrolyte interphase formation in lithium-ion battery.

PubMed

Ushirogata, Keisuke; Sodeyama, Keitaro; Okuno, Yukihiro; Tateyama, Yoshitaka

2013-08-14

The solid-electrolyte interphase (SEI) formed through the reductive decomposition of solvent molecules plays a crucial role in the stability and capability of a lithium-ion battery (LIB). Here we investigated the effects of adding vinylene carbonate (VC) to ethylene carbonate (EC) solvent, a typical electrolyte in LIBs, on the reductive decomposition. We focused on both thermodynamics and kinetics of the possible processes and used density functional theory-based molecular dynamics with explicit solvent and Blue-moon ensemble technique for the free energy change. We considered Li(+) in only EC solvent (EC system) and in EC solvent with a VC additive (EC/VC system) to elucidate the additive effects. In addition to clarifying the equilibrium properties, we evaluated the free energy changes along several EC or VC decomposition pathways under one-electron (1e) reduction condition. Two-electron (2e) reduction and attacks of anion radicals to intact molecules were also examined. The present results completely reproduce the gaseous products observed in the experiments. We also found a new mechanism involving the VC additive: the VC additive preferentially reacts with the EC anion radical to suppress the 2e reduction of EC and enhance the initial SEI formation, contrary to the conventional scenario in which VC additive is sacrificially reduced and its radical oligomerization becomes the source of SEI. Because our mechanism needs only 1e reduction, the irreversible capacity at the SEI formation will decrease, which is also consistent with the experimental observations. These results reveal the primary role of VC additive in the EC solvent.

Designed synergetic effect of electrolyte additives to improve interfacial chemistry of MCMB electrode in propylene carbonate-based electrolyte for enhanced low and room temperature performance.

PubMed

Wotango, Aselefech Sorsa; Su, Wei-Nien; Haregewoin, Atetegeb Meazah; Chen, Hung-Ming; Cheng, Ju-Hsiang; Lin, Ming-Hsien; Wang, Chia-Hsin; Hwang, Bing-Joe

2018-05-09

The performance of lithium ion batteries rapidly falls at lower temperatures due to decreasing conductivity of electrolytes and Solid Electrolyte Interphase (SEI) on graphite anode. Hence, it limits the practical use of lithium ion batteries at sub-zero temperatures and also affects the development of lithium ion batteries for widespread applications. The SEI formed on the graphite surface is very influential in determining the performance of the battery. Herein, a new electrolyte additive, 4-Chloromethyl-1,3,2-dioxathiolane-2-oxide (CMDO), is prepared to improve the properties of commonly used electrolyte constituents - ethylene carbonate (EC), and fluoroethylene carbonate (FEC). The formation of an efficient passivation layer in propylene carbonate (PC) -based electrolyte for MCMB electrode was investigated. The addition of CMDO resulted in a much less irreversible capacity loss and induces thin SEI formation. However, the combination of the three additives played a key role to enhance reversible capacity of MCMB electrode at lower or ambient temperature. The electrochemical measurement analysis showed that the SEI formed from a mixture of the three additives gave better intercalation-deintercalation of lithium ions.

Thick solid electrolyte interphases grown on silicon nanocone anodes during slow cycling and their negative effects on the performance of Li-ion batteries.

PubMed

Luo, Fei; Chu, Geng; Xia, Xiaoxiang; Liu, Bonan; Zheng, Jieyun; Li, Junjie; Li, Hong; Gu, Changzhi; Chen, Liquan

2015-05-07

Thickness, homogeneity and coverage of the surface passivation layer on Si anodes for Li-ion batteries have decisive influences on their cyclic performance and coulombic efficiency, but related information is difficult to obtain, especially during cycling. In this work, a well-defined silicon nanocone (SNC) on silicon wafer sample has been fabricated as a model electrode in lithium ion batteries to investigate the growth of surface species on the SNC electrode during cycling using ex situ scanning electronic microscopy. It is observed that an extra 5 μm thick layer covers the top of the SNCs after 25 cycles at 0.1 C. This top layer has been proven to be a solid electrolyte interphase (SEI) layer by designing a solid lithium battery. It is noticed that the SEI layer is much thinner at a high rate of 1 C. The cyclic performance of the SNCs at 1 C looks much better than that of the same electrode at 0.1 C in the half cell. Our findings clearly demonstrate that the formation of the thick SEI on the naked nanostructured Si anode during low rate cycling is a serious problem for practical applications. An in depth understanding of this problem may provide valuable guidance in designing Si-based anode materials.

Decomposition of the fluoroethylene carbonate additive and the glue effect of lithium fluoride products for the solid electrolyte interphase: an ab initio study.

PubMed

Okuno, Yukihiro; Ushirogata, Keisuke; Sodeyama, Keitaro; Tateyama, Yoshitaka

2016-03-28

Additives in the electrolyte solution of lithium-ion batteries (LIBs) have a large impact on the performance of the solid electrolyte interphase (SEI) that forms on the anode and is a key to the stability and durability of LIBs. We theoretically investigated effects of fluoroethylene carbonate (FEC), a representative additive, that has recently attracted considerable attention for the enhancement of cycling stability of silicon electrodes and the improvement of reversibility of sodium-ion batteries. First, we intensively examined the reductive decompositions by ring-opening, hydrogen fluoride (HF) elimination to form a vinylene carbonate (VC) additive and intermolecular chemical reactions of FEC in the ethylene carbonate (EC) electrolyte, by using density functional theory (DFT) based molecular dynamics and the blue-moon ensemble technique for the free energy profile. The results show that the most plausible product of the FEC reductive decomposition is lithium fluoride (LiF), and that the reactivity of FEC to anion radicals is found to be inert compared to the VC additive. We also investigated the effects of the generated LiF on the SEI by using two model systems; (1) LiF molecules distributed in a model aggregate of organic SEI film components (SFCs) and (2) a LiF aggregate interfaced with the SFC aggregate. DFT calculations of the former system show that F atoms form strong bindings with the Li atoms of multiple organic SFC molecules and play as a joint connecting them. In the latter interface system, the LiF aggregate adsorbs the organic SFCs through the F-Li bindings. These results suggest that LiF moieties play the role of glue in the organic SFC within the SEI film. We also examined the interface structure between a LiF aggregate and a lithiated silicon anode, and found that they are strongly bound. This strong binding is likely to be related to the effectiveness of the FEC additive in the electrolyte for the silicon anode.

Identifying compatibility of lithium salts with LiFePO4 cathode using a symmetric cell

NASA Astrophysics Data System (ADS)

Tong, Bo; Wang, Jiawei; Liu, Zhenjie; Ma, Lipo; Zhou, Zhibin; Peng, Zhangquan

2018-04-01

The electrochemical performance of lithium-ion batteries is dominated by the interphase electrochemistry between the electrolyte and electrode materials. A multitude of efforts have been dedicated to the solid electrolyte interphase (SEI) formed on the anode. However, the interphase on the cathode, namely the cathode electrolyte interphase (CEI), is left aside, partially due to the fact that it is hard to single out the CEI considering the complicated anode-cathode inter-talk. Herein, a partially delithiated lithium iron phosphate (Li0.25FePO4) electrode is used as the anode. Owing to a high voltage plateau (≈3.45 V vs. Li/Li+), negligible reduction reactions of electrolyte occur on the L0.25FePO4 anode. Therefore, the CEI can be investigated exclusively. Using a LiFePO4|Li0.25FePO4 symmetric cell configuration, we scrutinize the compatibility of the electrolytes containing a wide spectrum of lithium salts, Li[(FSO2)(Cm F2m+1SO2)N] (m = 0, 1, 2, 4), with the LiFePO4, in both cycling and calendar tests. It is found that the Li[(FSO2)(n-C4F9SO2)N] (LiFNFSI)-based electrolyte exhibits the highest compatibility with LiFePO4.

Anion-Dependent Potential Precycling Effects on Lithium Deposition/Dissolution Reaction Studied by an Electrochemical Quartz Crystal Microbalance.

PubMed

Smaran, Kumar Sai; Shibata, Sae; Omachi, Asami; Ohama, Ayano; Tomizawa, Eika; Kondo, Toshihiro

2017-10-19

The electrochemical quartz crystal microbalance technique was employed to study the initial stage of the electrodeposition and dissolution of lithium utilizing three kinds of electrolyte solutions such as LiPF 6 , LiTFSI, or LiFSI in tetraglyme. The native-SEI (solid-electrolyte interphase) formed by a potential prescan before lithium deposition/dissolution in all three solutions. Simultaneous additional SEI (add-SEI) deposition and its dissolution with lithium deposition and dissolution, respectively, were observed in LiPF 6 and LiTFSI. Conversely, the add-SEI dissolution with lithium deposition and its deposition with lithium dissolution were observed in LiFSI. Additional potential precycling resulted in the accumulation of a "pre-SEI" layer over the native-SEI layer in all of the solutions. With the pre-SEI, only lithium deposition/dissolution were significantly observed in LiTFSI and LiFSI. On the basis of the potential dependences of the mass and resistance changes, the anion-dependent effects of such a pre-SEI layer presence/absence on the lithium deposition/dissolution processes were discussed.

Self-Formed Hybrid Interphase Layer on Lithium Metal for High-Performance Lithium-Sulfur Batteries.

PubMed

Li, Guoxing; Huang, Qingquan; He, Xin; Gao, Yue; Wang, Daiwei; Kim, Seong H; Wang, Donghai

2018-02-27

Lithium-sulfur (Li-S) batteries are promising candidates for high-energy storage devices due to high theoretical capacities of both the sulfur cathode and lithium (Li) metal anode. Considerable efforts have been devoted to improving sulfur cathodes. However, issues associated with Li anodes, such as low Coulombic efficiency (CE) and growth of Li dendrites, remain unsolved due to unstable solid-electrolyte interphase (SEI) and lead to poor capacity retention and a short cycling life of Li-S batteries. In this work, we demonstrate a facile and effective approach to fabricate a flexible and robust hybrid SEI layer through co-deposition of aromatic-based organosulfides and inorganic Li salts using poly(sulfur-random-1,3-diisopropenylbenzene) as an additive in an electrolyte. The aromatic-based organic components with planar backbone conformation and π-π interaction in the SEI layers can improve the toughness and flexibility to promote stable and high efficient Li deposition/dissolution. The as-formed durable SEI layer can inhibit dendritic Li growth, enhance Li deposition/dissolution CE (99.1% over 420 cycles), and in turn enable Li-S batteries with good cycling stability (1000 cycles) and slow capacity decay. This work demonstrates a route to address the issues associated with Li metal anodes and promote the development of high-energy rechargeable Li metal batteries.

Studying Degradation in Lithium-Ion Batteries by Depth Profiling with Lithium-Nuclear Reaction Analysis

NASA Astrophysics Data System (ADS)

Schulz, Adam

Lithium ion batteries (LIBs) are secondary (rechargeable) energy storage devices that lose the ability to store charge, or degrade, with time. This charge capacity loss stems from unwanted reactions such as the continual growth of the solid electrolyte interphase (SEI) layer on the negative carbonaceous electrode. Parasitic reactions consume mobile lithium, the byproducts of which deposit as SEI layer. Introducing various electrolyte additives and coatings on the positive electrode reduce the rate of SEI growth and lead to improved calendar lifetimes of LIBs respectively. There has been substantial work both electrochemically monitoring and computationally modeling the development of the SEI layer. Additionally, a plethora of spectroscopic techniques have been employed in an attempt to characterize the components of the SEI layer. Despite lithium being the charge carrier in LIBs, depth profiles of lithium in the SEI are few. Moreover, accurate depth profiles relating capacity loss to lithium in the SEI are virtually non-existent. Better quantification of immobilized lithium would lead to improved understanding of the mechanisms of capacity loss and allow for computational and electrochemical models dependent on true materials states. A method by which to prepare low variability, high energy density electrochemical cells for depth profiling with the non-destructive technique, lithium nuclear reaction analysis (Li-NRA), is presented here. Due to the unique and largely non-destructive nature of Li-NRA we are able to perform repeated measurement on the same sample and evaluate the variability of the technique. By using low variability electrochemical cells along with this precise spectroscopic technique, we are able to confidently report trends of lithium concentration while controlling variables such as charge state, age and electrolyte composition. Conversion of gamma intensity versus beam energy, rendered by NRA, to Li concentration as a function of depth requires calibration and modeling of the nuclear stopping power of the substrate (electrode material). A methodology to accurately convert characteristic gamma intensity versus beam energy raw data to Li % as a function of depth is presented. Depth profiles are performed on the electrodes of commercial LIBs charged to different states of charge and aged to different states of health. In-lab created Li-ion cells are prepared with different electrolytes and then depth profiled by Li-NRA. It was found lithium accumulates within the solid electrolyte interphase (SEI) layer with the square root of time, consistent with previous reports. When vinylene carbonate (VC) is introduced to electrolyte lithium accumulates at a rapidly reduced rate as compared to cells containing ethylene carbonte (EC). Additionally, lithium concentration within the positive electrode surface was observed to decrease linearly with time independent of electrolyte tested. Future experiments to be conducted to finish the work and the underpinnings of a materials based capacity loss model are proposed.

Separators for Li-Ion and Li-Metal Battery Including Ionic Liquid Based Electrolytes Based on the TFSI− and FSI− Anions

PubMed Central

Kirchhöfer, Marija; von Zamory, Jan; Paillard, Elie; Passerini, Stefano

2014-01-01

The characterization of separators for Li-ion or Li-metal batteries incorporating hydrophobic ionic liquid electrolytes is reported herein. Ionic liquids made of N-butyl-N-methylpyrrolidinium (PYR14+) or N-methoxyethyl-N-methylpyrrolidinium (PYR12O1+), paired with bis(trifluoromethanesulfonyl)imide (TFSI−) or bis(fluorosulfonyl)imide (FSI−) anions, were tested in combination with separators having different chemistries and morphologies in terms of wetting behavior, Gurley and McMullin number, as well as Li/(Separator + Electrolyte) interfacial properties. It is shown that non-functionalized microporous polyolefin separators are poorly wetted by FSI−-based electrolytes (contrary to TFSI−-based electrolytes), while the ceramic coated separator Separion® allows good wetting with all electrolytes. Furthermore, by comparing the lithium solid electrolyte interphase (SEI) resistance evolution at open circuit and during cycling, depending on separator morphologies and chemistries, it is possible to propose a scale for SEI forming properties in the order: PYR12O1FSI > PYR14FSI > PYR14TFSI > PYR12O1TFSI. Finally, the impact the separator morphology is evidenced by the SEI resistance evolution and by comparing Li electrodes cycled using separators with two different morphologies. PMID:25153637

Influence of Polar Organic Solvents in an Ionic Liquid Containing Lithium Bis(fluorosulfonyl)amide: Effect on the Cation-Anion Interaction, Lithium Ion Battery Performance, and Solid Electrolyte Interphase.

PubMed

Lahiri, Abhishek; Li, Guozhu; Olschewski, Mark; Endres, Frank

2016-12-14

Ionic liquid-organic solvent mixtures have recently been investigated as potential battery electrolytes. However, contradictory results with these mixtures have been shown for battery performance. In this manuscript, we studied the influence of the addition of polar organic solvents into the ionic liquid electrolyte 1 M lithium bis(fluorosulfonyl)amide (LiFSI)-1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)amide ([Py 1,4 ]FSI) and tested it for lithium ion battery applications. From infrared and Raman spectroscopy, clear changes in the lithium solvation and cation-anion interactions in the ionic liquid were observed on addition of organic solvents. From the lithiation/delithiation studies on electrodeposited Ge, the storage capacity for the ionic liquid-highly polar organic solvent (acetonitrile) mixture was found to be the highest at low C-rates (0.425 C) compared to using an ionic liquid alone and ionic liquid-less polar solvent (dimethyl carbonate) mixtures. Furthermore, XPS and AFM were used to evaluate the solid electrolyte interphase (SEI) and to correlate its stability with Li storage capacity.

Research Progress towards Understanding the Unique Interfaces between Concentrated Electrolytes and Electrodes for Energy Storage Applications

PubMed Central

Lochala, Joshua A.; Kwok, Alexander; Deng, Zhiqun Daniel

2017-01-01

The electrolyte is an indispensable component in all electrochemical energy storage and conversion devices with batteries being a prime example. While most research efforts have been pursued on the materials side, the progress for the electrolyte is slow due to the decomposition of salts and solvents at low potentials, not to mention their complicated interactions with the electrode materials. The general properties of bulk electrolytes such as ionic conductivity, viscosity, and stability all affect the cell performance. However, for a specific electrochemical cell in which the cathode, anode, and electrolyte are optimized, it is the interface between the solid electrode and the liquid electrolyte, generally referred to as the solid electrolyte interphase (SEI), that dictates the rate of ion flow in the system. The commonly used electrolyte is within the range of 1–1.2 m based on the prior optimization experience, leaving the high concentration region insufficiently recognized. Recently, electrolytes with increased concentration (>1.0 m) have received intensive attention due to quite a few interesting discoveries in cells containing concentrated electrolytes. The formation mechanism and the nature of the SEI layers derived from concentrated electrolytes could be fundamentally distinct from those of the traditional SEI and thus enable unusual functions that cannot be realized using regular electrolytes. In this article, we provide an overview on the recent progress of high concentration electrolytes in different battery chemistries. The experimentally observed phenomena and their underlying fundamental mechanisms are discussed. New insights and perspectives are proposed to inspire more revolutionary solutions to address the interfacial challenges. PMID:28852621

Research Progress towards Understanding the Unique Interfaces between Concentrated Electrolytes and Electrodes for Energy Storage Applications

DOE PAGES

Zheng, Jianming; Lochala, Joshua A.; Kwok, Alexander; ...

2017-03-31

The electrolyte is an indispensable component in all electrochemical energy storage and conversion devices, for example, batteries. While most research efforts have been pursued on the materials side, the progress for the electrolyte is slow due to the decomposition of salts and solvents at low potentials, not to mention their complicated interactions with the electrode materials. The general properties of bulk electrolytes such as ionic conductivity, viscosity, and stability all affect the cell performance. However, for a specific electrochemical cell in which the cathode, anode and electrolyte are optimized, it is the interface between the solid electrode and the liquidmore » electrolyte, generally referred to as the solid electrolyte interphase (SEI), that dictates the rate of ion flow in the system. The commonly used electrolyte is within the range of 1-1.2 M based on the prior optimization experience, leaving the high concentration region insufficiently recognized. Recently, electrolytes with increased concentration (> 1.0 M) have received additional attention due to quite a few interesting discoveries in cells containing concentrated electrolytes. The formation mechanism and the nature of the SEI layers derived from concentrated electrolytes could be fundamentally different from those of the traditional SEI and thus enable unusual functions that cannot be realized using regular electrolytes. In this article, we provide an overview on the recent progress of high concentration electrolytes in different battery chemistries. The experimentally observed phenomena and their underlying fundamental mechanism are discussed. As a result, new insights and perspectives are proposed to inspire more revolutionary solutions to address the interfacial challenges.« less

Research Progress towards Understanding the Unique Interfaces between Concentrated Electrolytes and Electrodes for Energy Storage Applications.

PubMed

Zheng, Jianming; Lochala, Joshua A; Kwok, Alexander; Deng, Zhiqun Daniel; Xiao, Jie

2017-08-01

The electrolyte is an indispensable component in all electrochemical energy storage and conversion devices with batteries being a prime example. While most research efforts have been pursued on the materials side, the progress for the electrolyte is slow due to the decomposition of salts and solvents at low potentials, not to mention their complicated interactions with the electrode materials. The general properties of bulk electrolytes such as ionic conductivity, viscosity, and stability all affect the cell performance. However, for a specific electrochemical cell in which the cathode, anode, and electrolyte are optimized, it is the interface between the solid electrode and the liquid electrolyte, generally referred to as the solid electrolyte interphase (SEI), that dictates the rate of ion flow in the system. The commonly used electrolyte is within the range of 1-1.2 m based on the prior optimization experience, leaving the high concentration region insufficiently recognized. Recently, electrolytes with increased concentration (>1.0 m) have received intensive attention due to quite a few interesting discoveries in cells containing concentrated electrolytes. The formation mechanism and the nature of the SEI layers derived from concentrated electrolytes could be fundamentally distinct from those of the traditional SEI and thus enable unusual functions that cannot be realized using regular electrolytes. In this article, we provide an overview on the recent progress of high concentration electrolytes in different battery chemistries. The experimentally observed phenomena and their underlying fundamental mechanisms are discussed. New insights and perspectives are proposed to inspire more revolutionary solutions to address the interfacial challenges.

Research Progress towards Understanding the Unique Interfaces between Concentrated Electrolytes and Electrodes for Energy Storage Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jianming; Lochala, Joshua A.; Kwok, Alexander

The electrolyte is an indispensable component in all electrochemical energy storage and conversion devices, for example, batteries. While most research efforts have been pursued on the materials side, the progress for the electrolyte is slow due to the decomposition of salts and solvents at low potentials, not to mention their complicated interactions with the electrode materials. The general properties of bulk electrolytes such as ionic conductivity, viscosity, and stability all affect the cell performance. However, for a specific electrochemical cell in which the cathode, anode and electrolyte are optimized, it is the interface between the solid electrode and the liquidmore » electrolyte, generally referred to as the solid electrolyte interphase (SEI), that dictates the rate of ion flow in the system. The commonly used electrolyte is within the range of 1-1.2 M based on the prior optimization experience, leaving the high concentration region insufficiently recognized. Recently, electrolytes with increased concentration (> 1.0 M) have received additional attention due to quite a few interesting discoveries in cells containing concentrated electrolytes. The formation mechanism and the nature of the SEI layers derived from concentrated electrolytes could be fundamentally different from those of the traditional SEI and thus enable unusual functions that cannot be realized using regular electrolytes. In this article, we provide an overview on the recent progress of high concentration electrolytes in different battery chemistries. The experimentally observed phenomena and their underlying fundamental mechanism are discussed. As a result, new insights and perspectives are proposed to inspire more revolutionary solutions to address the interfacial challenges.« less

First-Principles Modeling of Mn(II) Migration above and Dissolution from Li x Mn 2 O 4 (001) Surfaces

DOE PAGES

Leung, Kevin

2016-12-10

The density functional theory and ab initio molecular dynamics simulations are applied to investigate the migration of Mn(II) ions to above-surface sites on spinel Li xMn 2O 4 (001) surfaces, the subsequent Mn dissolution into the organic liquid electrolyte, and the detrimental effects on graphite anode solid electrolyte interphase (SEI) passivating films after Mn(II) ions diffuse through the separator. The dissolution mechanism proves complex; the much-quoted Hunter disproportionation of Mn(III) to form Mn(II) is far from sufficient. Key steps that facilitate Mn(II) loss include concerted liquid/solid-state motions; proton-induced weakening of Mn–O bonds forming mobile OH – surface groups; and chemicalmore » reactions of adsorbed decomposed organic fragments. Mn(II) lodged between the inorganic Li 2CO 3 and organic lithium ethylene dicarbonate (LEDC) anode SEI components facilitate electrochemical reduction and decomposition of LEDC. Our findings help inform future design of protective coatings, electrolytes, additives, and interfaces.« less

Developing High-Performance Lithium Metal Anode in Liquid Electrolytes: Challenges and Progress.

PubMed

Li, Sa; Jiang, Mengwen; Xie, Yong; Xu, Hui; Jia, Junyao; Li, Ju

2018-04-01

Lithium metal anodes are potentially key for next-generation energy-dense batteries because of the extremely high capacity and the ultralow redox potential. However, notorious safety concerns of Li metal in liquid electrolytes have significantly retarded its commercialization: on one hand, lithium metal morphological instabilities (LMI) can cause cell shorting and even explosion; on the other hand, breaking of the grown Li arms induces the so-called "dead Li"; furthermore, the continuous consumption of the liquid electrolyte and cycleable lithium also shortens cell life. The research community has been seeking new strategies to protect Li metal anodes and significant progress has been made in the last decade. Here, an overview of the fundamental understandings of solid electrolyte interphase (SEI) formation, conceptual models, and advanced real-time characterizations of LMI are presented. Instructed by the conceptual models, strategies including increasing the donatable fluorine concentration (DFC) in liquid to enrich LiF component in SEI, increasing salt concentration (ionic strength) and sacrificial electrolyte additives, building artificial SEI to boost self-healing of natural SEI, and 3D electrode frameworks to reduce current density and delay Sand's extinction are summarized. Practical challenges in competing with graphite and silicon anodes are outlined. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Atomic force microscopy studies on molybdenum disulfide flakes as sodium-ion anodes.

PubMed

Lacey, Steven D; Wan, Jiayu; von Wald Cresce, Arthur; Russell, Selena M; Dai, Jiaqi; Bao, Wenzhong; Xu, Kang; Hu, Liangbing

2015-02-11

A microscale battery comprised of mechanically exfoliated molybdenum disulfide (MoS2) flakes with copper connections and a sodium metal reference was created and investigated as an intercalation model using in situ atomic force microscopy in a dry room environment. While an ethylene carbonate-based electrolyte with a low vapor pressure allowed topographical observations in an open cell configuration, the planar microbattery was used to conduct in situ measurements to understand the structural changes and the concomitant solid electrolyte interphase (SEI) formation at the nanoscale. Topographical observations demonstrated permanent wrinkling behavior of MoS2 electrodes upon sodiation at 0.4 V. SEI formation occurred quickly on both flake edges and planes at voltages before sodium intercalation. Force spectroscopy measurements provided quantitative data on the SEI thickness for MoS2 electrodes in sodium-ion batteries for the first time.

Self-Formed Hybrid Interphase Layer on Lithium Metal for High-Performance Lithium–Sulfur Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Guoxing; Huang, Qingquan; He, Xin

Lithium–sulfur (Li–S) batteries are promising candidates for high-energy storage devices due to high theoretical capacities of both the sulfur cathode and lithium (Li) metal anode. Considerable efforts have been devoted to improving sulfur cathodes. However, issues associated with Li anodes, such as low Coulombic efficiency (CE) and growth of Li dendrites, remain unsolved due to unstable solid-electrolyte interphase (SEI) and lead to poor capacity retention and a short cycling life of Li–S batteries. In this paper, we demonstrate a facile and effective approach to fabricate a flexible and robust hybrid SEI layer through co-deposition of aromatic-based organosulfides and inorganic Limore » salts using poly(sulfur-random-1,3-diisopropenylbenzene) as an additive in an electrolyte. The aromatic-based organic components with planar backbone conformation and π–π interaction in the SEI layers can improve the toughness and flexibility to promote stable and high efficient Li deposition/dissolution. The as-formed durable SEI layer can inhibit dendritic Li growth, enhance Li deposition/dissolution CE (99.1% over 420 cycles), and in turn enable Li–S batteries with good cycling stability (1000 cycles) and slow capacity decay. Finally, this work demonstrates a route to address the issues associated with Li metal anodes and promote the development of high-energy rechargeable Li metal batteries.« less

Self-Formed Hybrid Interphase Layer on Lithium Metal for High-Performance Lithium–Sulfur Batteries

DOE PAGES

Li, Guoxing; Huang, Qingquan; He, Xin; ...

2018-01-29

Lithium–sulfur (Li–S) batteries are promising candidates for high-energy storage devices due to high theoretical capacities of both the sulfur cathode and lithium (Li) metal anode. Considerable efforts have been devoted to improving sulfur cathodes. However, issues associated with Li anodes, such as low Coulombic efficiency (CE) and growth of Li dendrites, remain unsolved due to unstable solid-electrolyte interphase (SEI) and lead to poor capacity retention and a short cycling life of Li–S batteries. In this paper, we demonstrate a facile and effective approach to fabricate a flexible and robust hybrid SEI layer through co-deposition of aromatic-based organosulfides and inorganic Limore » salts using poly(sulfur-random-1,3-diisopropenylbenzene) as an additive in an electrolyte. The aromatic-based organic components with planar backbone conformation and π–π interaction in the SEI layers can improve the toughness and flexibility to promote stable and high efficient Li deposition/dissolution. The as-formed durable SEI layer can inhibit dendritic Li growth, enhance Li deposition/dissolution CE (99.1% over 420 cycles), and in turn enable Li–S batteries with good cycling stability (1000 cycles) and slow capacity decay. Finally, this work demonstrates a route to address the issues associated with Li metal anodes and promote the development of high-energy rechargeable Li metal batteries.« less

Studies of electrochemical interfaces by TOF neutron reflectometry at the IBR-2 reactor

NASA Astrophysics Data System (ADS)

Petrenko, V. I.; Gapon, I. V.; Rulev, A. A.; Ushakova, E. E.; Kataev, E. Yu; Yashina, L. V.; Itkis, D. M.; Avdeev, M. V.

2018-03-01

The operation performance of electrochemical energy conversion and storage systems such as supercapacitors and batteries depends on the processes occurring at the electrochemical interfaces, where charge separation and chemical reactions occur. Here, we report about the tests of the neutron reflectometry cells specially designed for operando studies of structural changes at the electrochemical interfaces between solid electrodes and liquid electrolytes. The cells are compatible with anhydrous electrolytes with organic solvents, which are employed today in all lithium ion batteries and most supercapacitors. The sensitivity of neutron reflectometry applied at the time-of-flight (TOF) reflectometer at the pulsed reactor IBR-2 is discussed regarding the effect of solid electrolyte interphase (SEI) formation on metal electrode surface.

Highly Stable Lithium Metal Batteries Enabled by Regulating the Solvation of Lithium Ions in Nonaqueous Electrolytes.

PubMed

Zhang, Xue-Qiang; Chen, Xiang; Cheng, Xin-Bing; Li, Bo-Quan; Shen, Xin; Yan, Chong; Huang, Jia-Qi; Zhang, Qiang

2018-05-04

Safe and rechargeable lithium metal batteries have been difficult to achieve because of the formation of lithium dendrites. Herein an emerging electrolyte based on a simple solvation strategy is proposed for highly stable lithium metal anodes in both coin and pouch cells. Fluoroethylene carbonate (FEC) and lithium nitrate (LiNO 3 ) were concurrently introduced into an electrolyte, thus altering the solvation sheath of lithium ions, and forming a uniform solid electrolyte interphase (SEI), with an abundance of LiF and LiN x O y on a working lithium metal anode with dendrite-free lithium deposition. Ultrahigh Coulombic efficiency (99.96 %) and long lifespans (1000 cycles) were achieved when the FEC/LiNO 3 electrolyte was applied in working batteries. The solvation chemistry of electrolyte was further explored by molecular dynamics simulations and first-principles calculations. This work provides insight into understanding the critical role of the solvation of lithium ions in forming the SEI and delivering an effective route to optimize electrolytes for safe lithium metal batteries. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical performance and interfacial investigation on Si composite anode for lithium ion batteries in full cell

NASA Astrophysics Data System (ADS)

Shobukawa, Hitoshi; Alvarado, Judith; Yang, Yangyuchen; Meng, Ying Shirley

2017-08-01

Lithium ion batteries (LIBs) containing silicon (Si) as a negative electrode have gained much attention recently because they deliver high energy density. However, the commercialization of LIBs with Si anode is limited due to the unstable electrochemical performance associated with expansion and contraction during electrochemical cycling. This study investigates the electrochemical performance and degradation mechanism of a full cell containing Si composite anode and LiFePO4 (lithium iron phosphate (LFP)) cathode. Enhanced electrochemical cycling performance is observed when the full cell is cycled with fluoroethylene carbonate (FEC) additive compared to the standard electrolyte. To understand the improvement in the electrochemical performance, x-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) are used. Based on the electrochemical behavior, FEC improves the reversibility of lithium ion diffusion into the solid electrolyte interphase (SEI) on the Si composite anode. Moreover, XPS analysis demonstrates that the SEI composition generated from the addition of FEC consists of a large amount of LiF and less carbonate species, which leads to better capacity retention over 40 cycles. The effective SEI successively yields more stable capacity retention and enhances the reversibility of lithium ion diffusion through the interphase of the Si anode, even at higher discharge rate. This study contributes to a basic comprehension of electrochemical performance and SEI formation of LIB full cells with a high loading Si composite anode.

Fluorinated Electrolytes for Li-S Battery: Suppressing the Self-Discharge with an Electrolyte Containing Fluoroether Solvent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azimi, N.; Xue, Z.; Rago, N. D.

The fluorinated electrolyte containing a fluoroether 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) was investigated as a new electrolyte for lithium-sulfur (Li-S) batteries. The low solubility of lithium polysulfides (LiPS) in the fluorinated electrolyte reduced the parasitic reactions with Li anode and mitigated the self-discharge by limiting their diffusion from the cathode to the anode. The use of fluorinated ether as a co-solvent and LiNO3 as an additive in the electrolyte shows synergetic effect in suppressing the self-discharge of Li-S battery due to the formation of the solid electrolyte interphase (SEI) on both sulfur cathode and the lithium anode. The Li-S cell with themore » fluorinated electrolyte showed prolonged shelf life at fully charged state.« less

Interfacial reactions in lithium batteries

NASA Astrophysics Data System (ADS)

Chen, Zonghai; Amine, Rachid; Ma, Zi-Feng; Amine, Khalil

2017-08-01

The lithium-ion battery was first commercially introduced by Sony Corporation in 1991 using LiCoO2 as the cathode material and mesocarbon microbeads (MCMBs) as the anode material. After continuous research and development for 25 years, lithium-ion batteries have been the dominant energy storage device for modern portable electronics, as well as for emerging applications for electric vehicles and smart grids. It is clear that the success of lithium-ion technologies is rooted to the existence of a solid electrolyte interphase (SEI) that kinetically suppresses parasitic reactions between the lithiated graphitic anodes and the carbonate-based non-aqueous electrolytes. Recently, major attention has been paid to the importance of a similar passivation/protection layer on the surface of cathode materials, aiming for a rational design of high-energy-density lithium-ion batteries with extended cycle/calendar life. In this article, the physical model of the SEI, as well as recent research efforts to understand the nature and role of the SEI are summarized, and future perspectives on this important research field will also be presented.

A rechargeable Li-O2 battery using a lithium nitrate/N,N-dimethylacetamide electrolyte.

PubMed

Walker, Wesley; Giordani, Vincent; Uddin, Jasim; Bryantsev, Vyacheslav S; Chase, Gregory V; Addison, Dan

2013-02-13

A major challenge in the development of rechargeable Li-O(2) batteries is the identification of electrolyte materials that are stable in the operating environment of the O(2) electrode. Straight-chain alkyl amides are one of the few classes of polar, aprotic solvents that resist chemical degradation in the O(2) electrode, but these solvents do not form a stable solid-electrolyte interphase (SEI) on the Li anode. The lack of a persistent SEI leads to rapid and sustained solvent decomposition in the presence of Li metal. In this work, we demonstrate for the first time successful cycling of a Li anode in the presence of the solvent, N,N-dimethylacetamide (DMA), by employing a salt, lithium nitrate (LiNO(3)), that stabilizes the SEI. A Li-O(2) cell containing this electrolyte composition is shown to cycle for more than 2000 h (>80 cycles) at a current density of 0.1 mA/cm(2) with a consistent charging profile, good capacity retention, and O(2) detected as the primary gaseous product formed during charging. The discovery of an electrolyte system that is compatible with both electrodes in a Li-O(2) cell may eliminate the need for protecting the anode with a ceramic membrane.

Analysis of a Li-Ion Nanobattery with Graphite Anode Using Molecular Dynamics Simulations

DOE PAGES

Ponce, Victor; Galvez-Aranda, Diego E.; Seminario, Jorge M.

2017-05-19

In this work, molecular dynamics simulations were performed of the initial charging of a Li-ion nanobattery with a graphite anode and lithium hexaflourphosphate (LiPF 6) salt dissolved in ethylene carbonate (CO 3C 2H 4) solvent as the electrolyte solution. The charging was achieved through the application of external electric fields simulating voltage sources. A variety of force fields were combined to simulate the materials of the nanobattery, including the solid electrolyte interphase, metal collectors, and insulator cover. Some of the force field parameters were estimated using ab initio methods and others were taken from the literature. We studied the behaviormore » of Li-ions traveling from cathode to anode through electrolyte solutions of concentrations 1.15 and 3.36 M. Time-dependent variables such as energy, temperature, volume, polarization, and mean square displacement are reported; a few of these variables, as well as others such as current, resistance, current density, conductivity, and resistivity are reported as a function of the external field and charging voltage. A solid electrolyte interphase (SEI) layer was also added to the model to study the mechanism behind the diffusion of the Li-ions through the SEI. As the battery is charged, the depletion of Li atoms in the cathode and their accumulation in the anode follow a linear increase of the polarizability in the solvent, until reaching a saturation point after which the charging of the battery stops, i.e., the energy provided by the external source decays to very low levels. Lastly, the nanobattery model containing the most common materials of a commercial lithium-ion battery is very useful to determine atomistic information that is difficult or too expensive to obtain experimentally; available data shows consistency with our results.« less

High performance red phosphorus electrode in ionic liquid-based electrolyte for Na-ion batteries

NASA Astrophysics Data System (ADS)

Dahbi, Mouad; Fukunishi, Mika; Horiba, Tatsuo; Yabuuchi, Naoaki; Yasuno, Satoshi; Komaba, Shinichi

2017-09-01

Electrochemical performance of the red phosphorus electrode was examined in ionic-liquid electrolyte, 0.25 mol dm-3 sodium bisfluorosulfonylamide (NaFSA) dissolved N-methyl-N-propylpyridinium-bisfluorosulfonylamide (MPPFSA), at room temperature. We compared its electrochemical performance to conventional EC/PC/DEC, EC/DEC, and PC solutions containing 1 mol dm-3 NaPF6. The electrode in NaFSA/MPPFSA demonstrated a reversible capacity of 1480 mAh g-1 and excellent capacity retention of 93% over 80 cycles, which is much better than those in the conventional electrolytes. The difference in capacity retention for the electrolytes correlates to the different solid electrolyte interphase (SEI) layer formed on the phosphorus electrode. To understand the SEI formation in NaFSA/MPPFSA and its evolution during cycling, we investigate the surface layer of the red phosphorus electrodes with hard X-ray photoelectron spectroscopy (HAXPES) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). A detailed analysis of HAXPES spectra demonstrates that SEI layer consists of major inorganic and minor organic species, originating from decomposition of MPP+ and FSA-. Homogenous surface layer is formed during the first cycle in NaFSA/MPPFSA while in alkyl carbonate ester electrolytes, continuous growth of surface film up to the 20th cycle is observed. Possibility of red phosphorous electrode for battery applications with pure ionic liquid is discussed.

In Situ Raman Spectroscopic Studies on Concentration of Electrolyte Salt in Lithium-Ion Batteries by Using Ultrafine Multifiber Probes.

PubMed

Yamanaka, Toshiro; Nakagawa, Hiroe; Tsubouchi, Shigetaka; Domi, Yasuhiro; Doi, Takayuki; Abe, Takeshi; Ogumi, Zempachi

2017-03-09

Lithium-ion batteries have attracted considerable attention due to their high power density. The change in concentration of salt in the electrolyte solution in lithium-ion batteries during operation causes serious degradation of battery performance. Herein, a new method of in situ Raman spectroscopy with ultrafine multifiber probes was developed to simultaneously study the concentrations of ions at several different positions in the electrolyte solution in deep narrow spaces between the electrodes in batteries. The total amount of ions in the electrolyte solution clearly changed during operation due to the low permeability of the solid-electrolyte interphase (SEI) at the anode for Li + permeation. The permeability, which is a key factor to achieve high battery performance, was improved (enhanced) by adding film-forming additives to the electrolyte solution to modify the properties of the SEI. The results provide important information for understanding and predicting phenomena occurring in a battery and for designing a superior battery. The present method is useful for analysis in deep narrow spaces in other electrochemical devices, such as capacitors. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multinuclear NMR Study of the Solid Electrolyte Interface Formed in Lithium Metal Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan, Chuan; Xu, Suochang; Hu, Mary Y.

The composition of the solid electrolyte interphase (SEI) layers associated with a high performance Cu|Li cell using lithium bis(fluorosulfonyi)imide (LiFSI) in 1,2-dimethoxyethane (DME) as electrolyte is determined by a multinuclear (6Li, 19F, 13C and 1H) solid-state MAS NMR study at high magnetic field (850 MHz). This cell can be cycled at high rates (4 mA•cm-2) for more than 1000 cycles with no increase in the cell impedance at high Columbic efficiency (average of 98.4%) in a highly concentrated LiFSI-DME electrolyte (4 M). LiFSI, LiF, Li2O2 (and/or CH3OLi), LiOH, Li2S and Li2O are observed in the SEI and validated by comparingmore » with the spectra acquired on standard compounds and literature reports. To gain further insight into the role of the solute and its concentration dependence on the formation of SEIs while keeping the solvent of DME unchanged, the SEIs from different concentrations of LiFSI-DME and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-DME electrolyte are also investigated. It is found that LiF, a lithiated compound with superior mechanical strength and good Li+ ionic conductivity, is observed in the concentrated 4.0 M LiFSI-DME and the 3.0 M LiTFSI-DME systems but not in the diluted 1.0 M LiFSI-DME system. Li2O exists in both low and high concentration of LiFSI-DME while no Li2O is observed in the LiTFSI system. Furthermore, the dead metallic Li is reduced in the 4 M LiFSI-DME system compared with that in the 1 M LiFSI-DME system. Quantitative 6Li MAS results indicate that the SEI associated with the 4 M LiFSI-DEME is denser or thicker than that of the 1 M LiFSI-DME and the 3 M LiTFSI-DME systems. These findings are likely the reasons for explaining the high electrochemical performance associated with the high concentration LiFSI-DME system.« less

First-Principles Modeling of the Initial Stages of Organic Solvent Decomposition on Li xMn 2O 4 (100) Surfaces [First principles modeling of Mn(II) migration to and dissolution from Li xMn 2O 4 (100) surfaces

DOE PAGES

Leung, Kevin

2012-04-13

Density functional theory and ab initio molecular dynamics simulations are applied to investigate the migration of Mn(II) ions to above-surface sites on spinel Li xMn 2O 4 (100) surfaces, the subsequent Mn dissolution into the organic liquid electrolyte, and the detrimental effects on anode solid electrolyte interphase (SEI) passivating films after Mn(II) ions diffuse through the separator. The dissolution mechanism proves complex; the much-quoted Hunter disproportionation of Mn(III) to form Mn(II) is necessary but far from sufficient. Key steps that facilitate Mn(II) ion migration include concerted liquid/solid-state motions, proton-induced weakening of Mn-O bonds forming mobile OH - surface groups; andmore » chemical reactions of adsorbed decomposed organic fragments. Mn(II) lodged between the inorganic Li 2CO 3 and organic lithium ethylene dicarbonate (LEDC) anode SEI component facilitates electrochemical reduction and decomposition of LEDC. These findings help inform future design of protective coatings, electrolytes, additives, and interfaces.« less

Fluorinated End-Groups in Electrolytes Induce Ordered Electrolyte/Anode Interface Even at Open-Circuit Potential as Revealed by Sum Frequency Generation Vibrational Spectroscopy

DOE PAGES

Horowitz, Yonatan; Han, Hui-Ling; Ralston, Walter T.; ...

2017-05-12

Fluorine-based additives have a tremendously beneficial effect on the performance of lithium-ion batteries, yet the origin of this phenomenon is unclear. This study shows that the formation of a solid-electrolyte interphase (SEI) on the anode surface in the first five charge/discharge cycles is affected by the stereochemistry of the electrolyte molecules on the anode surface starting at open-circuit potential (OCP). This study shows an anode-specific model system, the reduction of 1,2-diethoxy ethane with lithium bis(trifluoromethane)sulfonimide, as a salt on an amorphous silicon anode, and compares the electrochemical response and SEI formation to its fluorinated version, bis(2,2,2-trifluoroethoxy) ethane (BTFEOE), by summore » frequency generation (SFG) vibrational spectroscopy under reaction conditions. The SFG results suggest that the —CF 3 end-groups of the linear ether BTFEOE change their adsorption orientation on the a-Si surface at OCP, leading to a better protective layer. Finally, supporting evidence from ex situ scanning electron microscopy and X-ray photoelectron spectroscopy depth profiling measurements shows that the fluorinated ether, BTFEOE, yields a smooth SEI on the a-Si surface and enables lithium ions to intercalate deeper into the a-Si bulk.« less

Fluorinated End-Groups in Electrolytes Induce Ordered Electrolyte/Anode Interface Even at Open-Circuit Potential as Revealed by Sum Frequency Generation Vibrational Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horowitz, Yonatan; Han, Hui-Ling; Ralston, Walter T.

Fluorine-based additives have a tremendously beneficial effect on the performance of lithium-ion batteries, yet the origin of this phenomenon is unclear. This study shows that the formation of a solid-electrolyte interphase (SEI) on the anode surface in the first five charge/discharge cycles is affected by the stereochemistry of the electrolyte molecules on the anode surface starting at open-circuit potential (OCP). This study shows an anode-specific model system, the reduction of 1,2-diethoxy ethane with lithium bis(trifluoromethane)sulfonimide, as a salt on an amorphous silicon anode, and compares the electrochemical response and SEI formation to its fluorinated version, bis(2,2,2-trifluoroethoxy) ethane (BTFEOE), by summore » frequency generation (SFG) vibrational spectroscopy under reaction conditions. The SFG results suggest that the —CF 3 end-groups of the linear ether BTFEOE change their adsorption orientation on the a-Si surface at OCP, leading to a better protective layer. Finally, supporting evidence from ex situ scanning electron microscopy and X-ray photoelectron spectroscopy depth profiling measurements shows that the fluorinated ether, BTFEOE, yields a smooth SEI on the a-Si surface and enables lithium ions to intercalate deeper into the a-Si bulk.« less

Poly(isobutylene-alt-maleic anhydride) binders containing lithium for high-performance Li-ion batteries

NASA Astrophysics Data System (ADS)

Ku, Jun-Hwan; Hwang, Seung-Sik; Ham, Dong-Jin; Song, Min-Sang; Shon, Jeong-Kuk; Ji, Sang-Min; Choi, Jae-Man; Doo, Seok-Gwang

2015-08-01

Anode materials including graphite are known to be thermodynamically unstable toward organic solvents and salts and become covered by a passivating film (Solid electrolyte interphase, SEI) which retards the kinetics because of the high electronic resistivity. To achieve high performance in lithium ion batteries (LIBs), the SEIs are required to be mechanically stable during repeated cycling and possess highly ion-conductive. In this work, we have investigated an artificial pre-SEI on graphite electrode using a polymer binder containing lithium (i.e., a Li-copolymer of isobutylene and maleic anhydride, Li-PIMA) and its effect on the anode performances. During charging, the polymer binder with the functional group (-COOLi) acts as a SEI component, reducing the electrolyte decomposition and providing a stable passivating layer for the favorable penetration of lithium ions. Hence, by using the binder containing lithium, we have been able to obtain the first Coulombic efficiency of 84.2% (compared to 77.2% obtained using polyvinylidene fluoride as the binder) and a capacity retention of 99% after 100 cycles. The results of our study demonstrate that binder containing lithium we have used is a favorable candidate for the development of high-performance LIBs.

Organosulfide-plasticized solid-electrolyte interphase layer enables stable lithium metal anodes for long-cycle lithium-sulfur batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Guoxing; Gao, Yue; He, Xin

Lithium metal is a promising anode candidate for the next-generation rechargeable battery due to its highest specific capacity (3860 mA h g -1) and lowest potential, but low Coulombic efficiency and formation of lithium dendrites hinder its practical application. Here, we report a self-formed flexible hybrid solid-electrolyte interphase layer through co-deposition of organosulfides/organopolysulfides and inorganic lithium salts using sulfur-containing polymers as an additive in the electrolyte. The organosulfides/organopolysulfides serve as “plasticizer” in the solid-electrolyte interphase layer to improve its mechanical flexibility and toughness. The as-formed robust solid-electrolyte interphase layers enable dendrite-free lithium deposition and significantly improve Coulombic efficiency (99% overmore » 400 cycles at a current density of 2mAcm -2). A lithium-sulfur battery based on this strategy exhibits long cycling life (1000 cycles) and good capacity retention. This study reveals an avenue to effectively fabricate stable solid-electrolyte interphase layer for solving the issues associated with lithium metal anodes.« less

Organosulfide-plasticized solid-electrolyte interphase layer enables stable lithium metal anodes for long-cycle lithium-sulfur batteries

DOE PAGES

Li, Guoxing; Gao, Yue; He, Xin; ...

2017-10-11

Lithium metal is a promising anode candidate for the next-generation rechargeable battery due to its highest specific capacity (3860 mA h g -1) and lowest potential, but low Coulombic efficiency and formation of lithium dendrites hinder its practical application. Here, we report a self-formed flexible hybrid solid-electrolyte interphase layer through co-deposition of organosulfides/organopolysulfides and inorganic lithium salts using sulfur-containing polymers as an additive in the electrolyte. The organosulfides/organopolysulfides serve as “plasticizer” in the solid-electrolyte interphase layer to improve its mechanical flexibility and toughness. The as-formed robust solid-electrolyte interphase layers enable dendrite-free lithium deposition and significantly improve Coulombic efficiency (99% overmore » 400 cycles at a current density of 2mAcm -2). A lithium-sulfur battery based on this strategy exhibits long cycling life (1000 cycles) and good capacity retention. This study reveals an avenue to effectively fabricate stable solid-electrolyte interphase layer for solving the issues associated with lithium metal anodes.« less

A Synopsis of Interfacial Phenomena in Lithium-Based Polymer Electrolyte Electrochemical Cells

NASA Technical Reports Server (NTRS)

Baldwin, Richard S.; Bennett, William R.

2007-01-01

The interfacial regions between electrode materials, electrolytes and other cell components play key roles in the overall performance of lithium-based batteries. For cell chemistries employing lithium metal, lithium alloy or carbonaceous materials (i.e., lithium-ion cells) as anode materials, a "solid electrolyte interphase" (SEI) layer forms at the anode/electrolyte interface, and the properties of this "passivating" layer significantly affect the practical cell/battery quality and performance. A thin, ionically-conducting SEI on the electrode surface can beneficially reduce or eliminate undesirable side reactions between the electrode and the electrolyte, which can result in a degradation in cell performance. The properties and phenomena attributable to the interfacial regions existing at both anode and cathode surfaces can be characterized to a large extent by electrochemical impedance spectroscopy (EIS) and related techniques. The intention of the review herewith is to support the future development of lithium-based polymer electrolytes by providing a synopsis of interfacial phenomena that is associated with cell chemistries employing either lithium metal or carbonaceous "composite" electrode structures which are interfaced with polymer electrolytes (i.e., "solvent-free" as well as "plasticized" polymer-binary salt complexes and single ion-conducting polyelectrolytes). Potential approaches to overcoming poor cell performance attributable to interfacial effects are discussed.

Ion Diffusivity through the Solid Electrolyte Interphase in Lithium-Ion Batteries

DOE PAGES

Benitez, Laura; Seminario, Jorge M.

2017-05-17

Understanding the transport properties of the solid electrolyte interface (SEI) is a critical piece in the development of lithium ion batteries (LIB) with better performance. We studied the lithium ion diffusivity in the main components of the SEI found in LIB with silicon anodes and performed classical molecular dynamics (MD) simulations on lithium fluoride (LiF), lithium oxide (Li 2O) and lithium carbonate (Li 2CO 3) in order to provide insights and to calculate the diffusion coefficients of Li-ions at temperatures in the range of 250 K to 400 K, which is within the LIB operating temperature range. We find amore » slight increase in the diffusivity as the temperature increases and since diffusion is noticeable at high temperatures, Li-ion diffusion in the range of 130 to 1800 K was also studied and the diffusion mechanisms involved in each SEI compound were analyzed. We observed that the predominant mechanisms of Li-ion diffusion included vacancy assisted and knock-off diffusion in LiF, direct exchange in Li 2O, and vacancy and knock-off in Li 2CO 3. Moreover, we also evaluated the effect of applied electric fields in the diffusion of Li-ions at room temperature.« less

Ion Diffusivity through the Solid Electrolyte Interphase in Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benitez, Laura; Seminario, Jorge M.

Understanding the transport properties of the solid electrolyte interface (SEI) is a critical piece in the development of lithium ion batteries (LIB) with better performance. We studied the lithium ion diffusivity in the main components of the SEI found in LIB with silicon anodes and performed classical molecular dynamics (MD) simulations on lithium fluoride (LiF), lithium oxide (Li 2O) and lithium carbonate (Li 2CO 3) in order to provide insights and to calculate the diffusion coefficients of Li-ions at temperatures in the range of 250 K to 400 K, which is within the LIB operating temperature range. We find amore » slight increase in the diffusivity as the temperature increases and since diffusion is noticeable at high temperatures, Li-ion diffusion in the range of 130 to 1800 K was also studied and the diffusion mechanisms involved in each SEI compound were analyzed. We observed that the predominant mechanisms of Li-ion diffusion included vacancy assisted and knock-off diffusion in LiF, direct exchange in Li 2O, and vacancy and knock-off in Li 2CO 3. Moreover, we also evaluated the effect of applied electric fields in the diffusion of Li-ions at room temperature.« less

High-Performance Cells Containing Lithium Metal Anodes, LiNi0.6Co0.2Mn0.2O2 (NCM 622) Cathodes, and Fluoroethylene Carbonate-Based Electrolyte Solution with Practical Loading.

PubMed

Salitra, Gregory; Markevich, Elena; Afri, Michal; Talyosef, Yosef; Hartmann, Pascal; Kulisch, Joern; Sun, Yang-Kook; Aurbach, Doron

2018-06-13

We report on the highly stable lithium metal|LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM 622) cells with practical electrodes' loading of 3.3 mA h g -1 , which can undergo many hundreds of stable cycles, demonstrating high rate capability. A key issue was the use of fluoroethylene carbonate (FEC)-based electrolyte solutions (1 M LiPF 6 in FEC/dimethyl carbonate). Li|NCM 622 cells can be cycled at 1.5 mA cm -2 for more than 600 cycles, whereas symmetric Li|Li cells demonstrate stable performance for more than 1000 cycles even at higher areal capacity and current density. We attribute the excellent performance of both Li|NCM and Li|Li cells to the formation of a stable and efficient solid electrolyte interphase (SEI) on the surface of the Li metal electrodes cycled in FEC-based electrolyte solutions. The composition of the SEI on the Li and the NCM electrodes is analyzed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. A drastic capacity fading of Li|NCM cells is observed, followed by spontaneous capacity recovery during prolonged cycling. This phenomenon depends on the current density and the amount of the electrolyte solution and relates to kinetic limitations because of SEI formation on the Li anodes in the FEC-based electrolyte solution.

Insights into the Li Intercalation and SEI Formation on LiSi Nanoclusters

DOE PAGES

Hankins, Kie; Soto, Fernando A.; Balbuena, Perla B.

2017-01-01

We report a first-principles atomic level assessment of the lithiation and reactivity of pre-lithiated Si clusters. Density functional theory formation energy calculations reveal that the pre-lithiated Li 16Si 16 cluster exposed to two different Li fluxes can store Li between the concentrations of Li 2.5Si and Li 3.5Si. This increase in storage capacity is attributed to the start of an amorphization process in the cluster, and more importantly these results show that the intercalation reaction can be controlled by the flux of the Li-ions. However, in a real battery, the lithiation of the anode occurs simultaneously to the electrode-electrolyte reactions.more » Here we simulate the solid-electrolyte interphase (SEI) formation and simultaneous lithiation of a Li 16Si 16 cluster in contact with two different electrolyte solutions: one with pure ethylene carbonate (EC), and another with a 1 M solution of LiPF 6 in EC. Our ab initio molecular dynamics simulations show that the solvent and salt are decomposed leading to the initial stages of the SEI layer formation and large part of the added Li becomes part of the SEI. Interestingly, the pure EC solution results in lower storage capacity and higher reactivity, whereas the presence of the salt causes the opposite effect: higher lithiation and reduced reactivity.« less

In Situ Study of Silicon Electrode Lithiation with X-ray Reflectivity

DOE PAGES

Cao, Chuntian; Steinrück, Hans-Georg; Shyam, Badri; ...

2016-10-26

Surface sensitive X-ray reflectivity (XRR) measurements were performed to investigate the electrochemical lithiation of a native oxide terminated single crystalline silicon (100) electrode in real time during the first galvanostatic discharge cycle. This allows us to gain nanoscale, mechanistic insight into the lithiation of Si and the formation of the solid electrolyte interphase (SEI). We describe an electrochemistry cell specifically designed for in situ XRR studies and have determined the evolution of the electron density profile of the lithiated Si layer (Li xSi) and the SEI layer with subnanometer resolution. We propose a three-stage lithiation mechanism with a reaction limited,more » layer-by-layer lithiation of the Si at the Li xSi/Si interface.« less

Alkyl Pyrocarbonate Electrolyte Additives for Performance Enhancement of Li Ion Cells

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Surampudi, S.

2000-01-01

Lithium ion rechargeable batteries are being developed for various aerospace applications under a NASA-DoD Interagency program. These applications require further improvements in several areas, specifically in the cycle life for LEO and GEO satellites and in the low temperature performance for the Mars Lander and Rover missions. Accordingly, we have been pursuing research studies to achieve improvement in the low temperature performance, long cycle life and active life of Li ion cells. The studies are mainly focused on electrolytes, to identify newer formulations of new electrolyte additives to enhance Li permeability (at low temperatures) and stability towards the electrode. The latter approach is particularly aimed at the formation suitable SEI (solid electrolyte interphase) on carbon electrodes. In this paper, we report the beneficial effect of using alkyl pyrocarbonates as electrolyte additives to improve the low temperature performance of Li ion cells.

Electrolyte Structure near Electrode Interfaces in Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Lordi, Vincenzo; Ong, Mitchell; Verners, Osvalds; van Duin, Adri; Draeger, Erik; Pask, John

2014-03-01

The performance of lithium-ion secondary batteries (LIBs) is strongly tied to electrochemistry and ionic transport near the electrode-electrolyte interface. Changes in ion solvation near the interface affect ion conductivity and also are associated with the formation and evolution of solid-electrolyte interphase (SEI) layers, which impede transport but also passivate the interface. Thus, understanding these effects is critical to optimizing battery performance. Here we present molecular dynamics (MD) simulations of typical organic liquid LIB electrolytes in contact with graphite electrodes to understand differences in molecular structure and solvation near the interface compared to the bulk electrolyte. Results for different graphite terminations are presented. We compare the results of density-functional based MD to the empirical reactive forcefield ReaxFF and the non-reactive, non-polarizable COMPASS forcefield. Notable differences in the predictive power of each of these techniques are discussed. Prepared by LLNL under Contract DE-AC52-07NA27344.

Development of Lithium Dimethyl Phosphate as an Electrolyte Additive for Lithium Ion Batteries

DOE PAGES

Milien, Mickdy S.; Tottempudi, Usha; Son, Miyoung; ...

2016-04-27

The novel electrolyte additive lithium dimethyl phosphate (LiDMP) has been synthesized and characterized. Incorporation of LiDMP (0.1% wt) into LiPF 6 in ethylene carbonate (EC) / ethyl methyl carbonate (EMC) (3:7 wt) results in improved rate performance and reduced impedance for graphite / LiNi 1/3Mn 1/3Co 1/3O 2 cells. Ex-situ surface analysis of the electrodes suggests that incorporation of LiDMP results in a modification of the solid electrolyte interphase (SEI) on the anode. A decrease in the concentration of lithium alkyl carbonates and an increase in the concentration of lithium fluoro phosphates are observed. The change in the anode SEImore » structure is responsible for the increased rate performance and decreased cell impedance.« less

The effect of fluoroethylene carbonate additive content on the formation of the solid-electrolyte interphase and capacity fade of Li-ion full-cell employing nano Si-graphene composite anodes

NASA Astrophysics Data System (ADS)

Bordes, Arnaud; Eom, KwangSup; Fuller, Thomas F.

2014-07-01

When fluoroethylene carbonate (FEC) is added to the ethylene carbonate (EC)-diethyl carbonate (DEC) electrolyte, the capacity and cyclability of full-cells employing Si-graphene anode and lithium nickel cobalt aluminum oxide cathode (NCA) cathode are improved due to formation of a thin (30-50 nm) SEI layer with low ionic resistance (∼2 ohm cm2) on the surface of Si-graphene anode. These properties are confirmed with electrochemical impedance spectroscopy and a cross-sectional image analysis using Focused Ion Beam (FIB)-SEM. Approximately 5 wt.% FEC in EC:DEC (1:1 wt.%) shows the highest capacity and most stability. This high capacity and low capacity fade is attributed to a more stable SEI layer containing less CH2OCO2Li, Li2CO3 and LiF compounds, which consume cyclable Li. Additionally, a greater amount of polycarbonate (PC), which is known to form a more robust passivation layer, thus reducing further reduction of electrolyte, is confirmed with X-ray photoelectron spectroscopy (XPS).

Electrode-Electrolyte Interfaces in Lithium-Sulfur Batteries with Liquid or Inorganic Solid Electrolytes.

PubMed

Yu, Xingwen; Manthiram, Arumugam

2017-11-21

Electrode-electrolyte interfacial properties play a vital role in the cycling performance of lithium-sulfur (Li-S) batteries. The issues at an electrode-electrolyte interface include electrochemical and chemical reactions occurring at the interface, formation mechanism of interfacial layers, compositional/structural characteristics of the interfacial layers, ionic transport across the interface, and thermodynamic and kinetic behaviors at the interface. Understanding the above critical issues is paramount for the development of strategies to enhance the overall performance of Li-S batteries. Liquid electrolytes commonly used in Li-S batteries bear resemblance to those employed in traditional lithium-ion batteries, which are generally composed of a lithium salt dissolved in a solvent matrix. However, due to a series of unique features associated with sulfur or polysulfides, ether-based solvents are generally employed in Li-S batteries rather than simply adopting the carbonate-type solvents that are generally used in the traditional Li + -ion batteries. In addition, the electrolytes of Li-S batteries usually comprise an important additive, LiNO 3 . The unique electrolyte components of Li-S batteries do not allow us to directly take the interfacial theories of the traditional Li + -ion batteries and apply them to Li-S batteries. On the other hand, during charging/discharging a Li-S battery, the dissolved polysulfide species migrate through the battery separator and react with the Li anode, which magnifies the complexity of the interfacial problems of Li-S batteries. However, current Li-S battery development paths have primarily been energized by advances in sulfur cathodes. Insight into the electrode-electrolyte interfacial behaviors has relatively been overshadowed. In this Account, we first examine the state-of-the-art contributions in understanding the solid-electrolyte interphase (SEI) formed on the Li-metal anode and sulfur cathode in conventional liquid-electrolyte Li-S batteries and how the resulting chemical and physical properties of the SEI affect the overall battery performance. A few strategies recently proposed for improving the stability of SEI are briefly summarized. Solid Li + -ion conductive electrolytes have been attempted for the development of Li-S batteries to eliminate the polysulfide shuttle issues. One approach is based on a concept of "all-solid-state Li-S battery," in which all the cell components are in the solid state. Another approach is based on a "hybrid-electrolyte Li-S battery" concept, in which the solid electrolyte plays roles both as a Li + -ion conductor for the electrochemical reaction and as a separator to prevent polysulfide shuttle. However, these endeavors with the solid electrolyte are not able to provide an overall satisfactory cell performance. In addition to the low ionic conductivity of solid-state electrolytes, a critical issue lies in the poor interfacial properties between the electrode and the solid electrolyte. This Account provides a survey of the relevant research progress in understanding and manipulating the interfaces of electrode and solid electrolytes in both the "all-solid-state Li-S batteries" and the "hybrid-electrolyte Li-S batteries". A recently proposed "semi-solid-state Li-S battery" concept is also briefly discussed. Finally, future research and development directions in all the above areas are suggested.

Capacity Fade and Its Mitigation in Li-Ion Cells with Silicon-Graphite Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bareno, Javier; Shkrob, Ilya A.; Gilbert, James A.

Silicon-graphite (Si-Gr) electrodes typically contain lithiated carboxylates as polymer binders that are introduced through aqueous processing. Li-ion cells with such electrodes show significantly faster capacity fade than cells with graphite (Gr) electrodes. Here we examine the causes for capacity loss in Si-Gr cells containing LiPF 6-based electrolytes. The presence of SiO xF y in the Si-Gr electrode, fluorophosphate species in the electrolyte, and silica on the positive electrode indicates the crucial role of the hydrolytic cycle. In particular, HF acid that is generated through LiPF 6 hydrolysis corrodes Si particles. As it reacts, the released water re-enters the cycle. Wemore » trace the moisture initiating this detrimental cycle to the hydration water in the lithiated binders that cannot be fully removed by thermal treatment. The rate of HF corrosion can be reduced through the use of electrolyte additives. For the fluoroethylene carbonate (FEC) additive, the improved performance arises from changes to the solid electrolyte interphase (SEI) that serves as a barrier against HF attack. Here, we propose that the greater extent of polymer cross-linking, that gives FEC-derived SEI elastomer properties, slows down HF percolation through this SEI membrane and inhibits the formation of deep cracks through which HF can access and degrade the Si surface.« less

Capacity Fade and Its Mitigation in Li-Ion Cells with Silicon-Graphite Electrodes

DOE PAGES

Bareno, Javier; Shkrob, Ilya A.; Gilbert, James A.; ...

2017-09-06

Silicon-graphite (Si-Gr) electrodes typically contain lithiated carboxylates as polymer binders that are introduced through aqueous processing. Li-ion cells with such electrodes show significantly faster capacity fade than cells with graphite (Gr) electrodes. Here we examine the causes for capacity loss in Si-Gr cells containing LiPF 6-based electrolytes. The presence of SiO xF y in the Si-Gr electrode, fluorophosphate species in the electrolyte, and silica on the positive electrode indicates the crucial role of the hydrolytic cycle. In particular, HF acid that is generated through LiPF 6 hydrolysis corrodes Si particles. As it reacts, the released water re-enters the cycle. Wemore » trace the moisture initiating this detrimental cycle to the hydration water in the lithiated binders that cannot be fully removed by thermal treatment. The rate of HF corrosion can be reduced through the use of electrolyte additives. For the fluoroethylene carbonate (FEC) additive, the improved performance arises from changes to the solid electrolyte interphase (SEI) that serves as a barrier against HF attack. Here, we propose that the greater extent of polymer cross-linking, that gives FEC-derived SEI elastomer properties, slows down HF percolation through this SEI membrane and inhibits the formation of deep cracks through which HF can access and degrade the Si surface.« less

Compact-Nanobox Engineering of Transition Metal Oxides with Enhanced Initial Coulombic Efficiency for Lithium-Ion Battery Anodes.

PubMed

Zhu, Yanfei; Hu, Aiping; Tang, Qunli; Zhang, Shiying; Deng, Weina; Li, Yanhua; Liu, Zheng; Fan, Binbin; Xiao, Kuikui; Liu, Jilei; Chen, Xiaohua

2018-03-14

A novel strategy is proposed to construct a compact-nanobox (CNB) structure composed of irregular nanograins (average diameter ≈ 10 nm), aiming to confine the electrode-electrolyte contact area and enhance initial Coulombic efficiency (ICE) of transition metal oxide (TMO) anodes. To demonstrate the validity of this attempt, CoO-CNB is taken as an example which is synthesized via a carbothermic reduction method. Benefiting from the compact configuration, electrolyte can only contact the outer surface of the nanobox, keeping the inner CoO nanograins untouched. Therefore, the solid electrolyte interphase (SEI) formation is reduced. Furthermore, the internal cavity leaves enough room for volume variation upon lithiation and delithiation, resulting in superior mechanical stability of the CNB structure and less generation of fresh SEI. Consequently, the SEI remains stable and spatially confined without degradation, and hence, the CoO-CNB electrode delivers an enhanced ICE of 82.2%, which is among the highest values reported for TMO-based anodes in lithium-ion batteries. In addition, the CoO-CNB electrode also demonstrates excellent cyclability with a reversible capacity of 811.6 mA h g -1 (90.4% capacity retention after 100 cycles). These findings open up a new way to design high-ICE electrodes and boost the practical application of TMO anodes.

Origin of Outstanding Stability in the Lithium Solid Electrolyte Materials: Insights from Thermodynamic Analyses Based on First-Principles Calculations

DOE PAGES

Zhu, Yizhou; He, Xingfeng; Mo, Yifei

2015-10-06

First-principles calculations were performed to investigate the electrochemical stability of lithium solid electrolyte materials in all-solid-state Li-ion batteries. The common solid electrolytes were found to have a limited electrochemical window. Our results suggest that the outstanding stability of the solid electrolyte materials is not thermodynamically intrinsic but is originated from kinetic stabilizations. The sluggish kinetics of the decomposition reactions cause a high overpotential leading to a nominally wide electrochemical window observed in many experiments. The decomposition products, similar to the solid-electrolyte-interphases, mitigate the extreme chemical potential from the electrodes and protect the solid electrolyte from further decompositions. With the aidmore » of the first-principles calculations, we revealed the passivation mechanism of these decomposition interphases and quantified the extensions of the electrochemical window from the interphases. We also found that the artificial coating layers applied at the solid electrolyte and electrode interfaces have a similar effect of passivating the solid electrolyte. Our newly gained understanding provided general principles for developing solid electrolyte materials with enhanced stability and for engineering interfaces in all-solid-state Li-ion batteries.« less

Silicon algae with carbon topping as thin-film anodes for lithium-ion microbatteries by a two-step facile method

NASA Astrophysics Data System (ADS)

Biserni, E.; Xie, M.; Brescia, R.; Scarpellini, A.; Hashempour, M.; Movahed, P.; George, S. M.; Bestetti, M.; Li Bassi, A.; Bruno, P.

2015-01-01

Silicon-based electrodes for Li-ion batteries (LIB) attract much attention because of their high theoretical capacity. However, their large volume change during lithiation results in poor cycling due to mechanical cracking. Moreover, silicon can hardly form a stable solid electrolyte interphase (SEI) layer with common electrolytes. We present a safe, innovative strategy to prepare nanostructured silicon-carbon anodes in a two-step process. The nanoporosity of Si films accommodates the volume expansion while a disordered graphitic C layer on top promotes the formation of a stable SEI. This approach shows its promises: carbon-coated porous silicon anodes perform in a very stable way, reaching the areal capacity of ∼175 μAh cm-2, and showing no decay for at least 1000 cycles. With requiring only a two-step deposition process at moderate temperatures, this novel very simple cell concept introduces a promising way to possibly viable up-scaled production of next-generation nanostructured Si anodes for lithium-ion microbatteries.

Effects of High and Low Salt Concentration in Electrolytes at Lithium–Metal Anode Surfaces

DOE PAGES

Camacho-Forero, Luis E.; Smith, Taylor W.; Balbuena, Perla B.

2016-12-16

The use of high concentration salts in electrolyte solutions of lithium-sulfur (Li-S) batteries has been shown beneficial for mitigating some effects such as polysulfide shuttle and dendrite growth at the Li metal anode. Such complex solutions have structural, dynamical, and reactivity associated issues that need to be analyzed for a better understanding of the reasons behind such beneficial effects. A passivation interfacial layer known as solid-electrolyte interphase (SEI) is generated during battery cycling as a result of electron transfer from the metal anode causing electrolyte decomposition. Here in this work, we investigate using density functional theory and ab initio molecularmore » dynamics simulations the salt decomposition, solvation effects, interactions among intermediate products and other species, and potential components of the SEI layer as a function of chemical nature and concentration of the salt, for lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI) at 1M and 4M concentrations in dimethoxyethane. It is found that LiTFSI undergoes a less complete reduction and facilitates charge transfer from the anode, whereas LiFSI shows a more complete decomposition forming LiF as one of the main SEI products. In addition, the specific decomposition mechanisms of each salt clearly point to the initial SEI components and the potential main products derived from them. Finally, very complex networks are found among the salt and solvent molecules in their attempt to maximize Li ion solvation that is quantified through the determination of coordination numbers.« less

Development of wide temperature electrolyte for graphite/ LiNiMnCoO2 Li-ion cells: High throughput screening

NASA Astrophysics Data System (ADS)

Kafle, Janak; Harris, Joshua; Chang, Jeremy; Koshina, Joe; Boone, David; Qu, Deyang

2018-07-01

In this report, we demonstrate that the low temperature power capability of a Li-ion battery can be substantially improved not by adding commercially unavailable additives into the electrolyte, but by rational design of the composition of the most commonly used solvents. Through the detail analysis with electrochemical impedance spectroscopy, the formation of a homogenous solid electrolyte interface (SEI) layer on the carbon anode surface is found to be critical to ensure the performance of a Li-ion battery in a wide temperature range. The post mortem analysis of the negative electrode by XPS revealed that all the electrolyte compositions form similar compounds in the solid electrolyte interphase. However, the electrolytes which give higher capacities at low temperature showed higher percentage of LiF and lower percentage of carbon containing species such as lithium carbonate and lithium ethylene di-carbonate. The electrolyte compositions where cyclic carbonates make up less than 25% of the total solvent showed increased low temperature performance. The solvent composition with higher percentage of linear short chain carbonates showed an improved low temperature performance. The high temperature performances were similar in almost all the combinations.

Fluoroethylene Carbonate as a Directing Agent in Amorphous Silicon Anodes: Electrolyte Interface Structure Probed by Sum Frequency Vibrational Spectroscopy and Ab Initio Molecular Dynamics.

PubMed

Horowitz, Yonatan; Han, Hui-Ling; Soto, Fernando A; Ralston, Walter T; Balbuena, Perla B; Somorjai, Gabor A

2018-02-14

Fluorinated compounds are added to carbonate-based electrolyte solutions in an effort to create a stable solid electrolyte interphase (SEI). The SEI mitigates detrimental electrolyte redox reactions taking place on the anode's surface upon applying a potential in order to charge (discharge) the lithium (Li) ion battery. The need for a stable SEI is dire when the anode material is silicon as silicon cracks due to its expansion and contraction upon lithiation and delithiation (charge-discharge) cycles, consequently limiting the cyclability of a silicon-based battery. Here we show the molecular structures for ethylene carbonate (EC): fluoroethylene carbonate (FEC) solutions on silicon surfaces by sum frequency generation (SFG) vibrational spectroscopy, which yields vibrational spectra of molecules at interfaces and by ab initio molecular dynamics (AIMD) simulations at open circuit potential. Our AIMD simulations and SFG spectra indicate that both EC and FEC adsorb to the amorphous silicon (a-Si) through their carbonyl group (C═O) oxygen atom with no further desorption. We show that FEC additives induce the reorientation of EC molecules to create an ordered, up-right orientation of the electrolytes on the Si surface. We suggest that this might be helpful for Li diffusion under applied potential. Furthermore, FEC becomes the dominant species at the a-Si surface as the FEC concentration increases above 20 wt %. Our finding at open circuit potential can now initiate additive design to not only act as a sacrificial compound but also to produce a better suited SEI for the use of silicon anodes in the Li-ion vehicular industry.

Enhancing cycling durability of Li-ion batteries with hierarchical structured silicon-graphene hybrid anodes.

PubMed

Loveridge, Melanie J; Lain, Michael J; Huang, Qianye; Wan, Chaoying; Roberts, Alexander J; Pappas, George S; Bhagat, Rohit

2016-11-09

Hybrid anode materials consisting of micro-sized silicon (Si) particles interconnected with few-layer graphene (FLG) nanoplatelets and sodium-neutralized poly(acrylic acid) as a binder were evaluated for Li-ion batteries. The hybrid film has demonstrated a reversible discharge capacity of ∼1800 mA h g -1 with a capacity retention of 97% after 200 cycles. The superior electrochemical properties of the hybrid anodes are attributed to a durable, hierarchical conductive network formed between Si particles and the multi-scale carbon additives, with enhanced cohesion by the functional polymer binder. Furthermore, improved solid electrolyte interphase (SEI) stability is achieved from the electrolyte additives, due to the formation of a kinetically stable film on the surface of the Si.

Homogeneous lithium electrodeposition with pyrrolidinium-based ionic liquid electrolytes.

PubMed

Grande, Lorenzo; von Zamory, Jan; Koch, Stephan L; Kalhoff, Julian; Paillard, Elie; Passerini, Stefano

2015-03-18

In this study, we report on the electroplating and stripping of lithium in two ionic liquid (IL) based electrolytes, namely N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl) imide (Pyr14FSI) and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI), and mixtures thereof, both on nickel and lithium electrodes. An improved method to evaluate the Li cycling efficiency confirmed that homogeneous electroplating (and stripping) of Li is possible with TFSI-based ILs. Moreover, the presence of native surface features on lithium, directly observable via scanning electron microscope imaging, was used to demonstrate the enhanced electrolyte interphase (SEI)-forming ability, that is, fast cathodic reactivity of this class of electrolytes and the suppressed dendrite growth. Finally, the induced inhomogeneous deposition enabled us to witness the SEI cracking and revealed previously unreported bundled Li fibers below the pre-existing SEI and nonrod-shaped protuberances resulting from Li extrusion.

New Insights into the Electroreduction of Ethylene Sulfite as Electrolyte Additive for Facilitating Solid Electrolyte Interphase of Lithium Ion Battery

PubMed Central

Sun, Youmin; Wang, Yixuan

2017-01-01

To help understand the solid electrolyte interphase (SEI) formation facilitated by electrolyte additives of lithium-ion batteries (LIB) the supermolecular clusters [(ES)Li+(PC)m](PC)n (m=1–2; n=0, 6, and 9) were used to investigate the electroreductive decompositions of the electrolyte additive, ethylene sulfite (ES), as well as the solvent, propylene carbonate (PC) with density functional theory. The results show that ES can be reduced prior to PC, resulting in a reduction precursor that will then undergo a ring opening decomposition to yield a radical anion. A new concerted pathway (path B) was located for the ring opening of the reduced ES, which has much lower energy barrier than the previously reported stepwise pathway (path A). The transition state for the ring opening of PC induced by the reduced ES (path C, indirect path) is closer to that of path A than path B in energy. The direct ring opening of the reduced PC (path D) has lower energy barrier than those of paths A, B and C, yet it is less favorable than the latter paths in terms of thermodynamics (vertical electron affinity or the reduction potential dissociation energy). The overall rate constant including the initial reduction and the subsequent ring opening for path B is the largest among the four paths, followed by paths A>C>D, which further signifies the importance of the concerted new path in facilitating the SEI. The hybrid models, the supermolecular cluster augmented by polarized continuum model, PCM-[(ES)Li+(PC)2](PC)n (n=0,6, and 9), were used to further estimate the reduction potential by taking into account both explicit and implicit solvent effects. The second solvation shell of Li+ in [(ES)Li+(PC)2](PC)n (n=6, and 9) partially compensates the overestimation of solvent effects arising from the PCM model for the naked (ES)Li+(PC)2, and the theoretical reduction potential with PCM-[(ES)Li+(PC)2](PC)6 (1.90–1.93V) agrees very well with the experimental one (1.8–2.0V). PMID:28220165

New insights into the electroreduction of ethylene sulfite as an electrolyte additive for facilitating solid electrolyte interphase formation in lithium ion batteries.

PubMed

Sun, Youmin; Wang, Yixuan

2017-03-01

To help understand the solid electrolyte interphase (SEI) formation facilitated by electrolyte additives of lithium-ion batteries (LIBs) the supermolecular clusters [(ES)Li + (PC) m ](PC) n (m = 1-2; n = 0, 6 and 9) were used to investigate the electroreductive decompositions of the electrolyte additive ethylene sulfite (ES) as well as the solvent propylene carbonate (PC) with density functional theory. The results show that ES can be reduced prior to PC, resulting in a reduction precursor that will then undergo a ring opening decomposition to yield a radical anion. A new concerted pathway (path B) was located for the ring opening of the reduced ES, which has a much lower energy barrier than the previously reported stepwise pathway (path A). The transition state for the ring opening of PC induced by the reduced ES (path C, indirect path) is closer to that of path A than path B in energy. The direct ring opening of the reduced PC (path D) has a lower energy barrier than paths A, B and C, yet it is less favorable than the latter paths in terms of thermodynamics (vertical electron affinity or reduction potential and dissociation energy). The overall rate constant including the initial reduction and the subsequent ring opening for path B is the largest among the four paths, followed by paths A > C > D, which further signifies the importance of the concerted new path in facilitating the SEI formation. The hybrid models, the supermolecular clusters augmented by a polarized continuum model, PCM-[(ES)Li + (PC) 2 ](PC) n (n = 0, 6 and 9), were used to further estimate the reduction potential by taking into account both explicit and implicit solvent effects. The second solvation shell of Li + in [(ES)Li + (PC) 2 ](PC) n (n = 6 and 9) partially compensates the overestimation of solvent effects arising from the PCM for the naked (ES)Li + (PC) 2 , and the theoretical reduction potential of PCM-[(ES)Li + (PC) 2 ](PC) 6 (1.90-1.93 V) agrees very well with the experimental one (1.8-2.0 V).

The Electrochemical Performance of Silicon Nanoparticles in Concentrated Electrolyte.

PubMed

Chang, Zeng-Hua; Wang, Jian-Tao; Wu, Zhao-Hui; Gao, Min; Wu, Shuai-Jin; Lu, Shi-Gang

2018-06-11

Silicon is a promising material for anodes in energy-storage devices. However, excessive growth of a solid-electrolyte interphase (SEI) caused by the severe volume change during the (de)lithiation processes leads to dramatic capacity fading. Here, we report a super-concentrated electrolyte composed of lithium bis(fluorosulfonyl)imide (LiFSI) and propylene carbonate (PC) with a molar ratio of 1:2 to improve the cycling performance of silicon nanoparticles (SiNPs). The SiNP electrode shows a remarkably improved cycling performance with an initial delithiation capacity of approximately 3000 mAh g -1 and a capacity of approximately 2000 mAh g -1 after 100 cycles, exhibiting about 6.8 times higher capacity than the cells with dilute electrolyte LiFSI-(PC) 8 . Raman spectra reveal that most of the PC solvent and FSI anions are complexed by Li + to form a specific solution structure like a fluid polymeric network. The reduction of FSI anions starts to play an important role owing to the increased concentration of contact ion pairs (CIPs) or aggregates (AGGs), which contribute to the formation of a more mechanically robust and chemically stable complex SEI layer. The complex SEI layer can effectively suppress the morphology evolution of silicon particles and self-limit the excessive growth, which mitigates the crack propagation of the silicon electrode and the deterioration of the kinetics. This study will provide a new direction for screening cycling-stable electrolytes for silicon-based electrodes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comprehensive Insights into the Reactivity of Electrolytes Based on Sodium Ions.

PubMed

Eshetu, Gebrekidan Gebresilassie; Grugeon, Sylvie; Kim, Huikyong; Jeong, Sangsik; Wu, Liming; Gachot, Gregory; Laruelle, Stephane; Armand, Michel; Passerini, Stefano

2016-03-08

We report a systematic investigation of Na-based electrolytes that comprise various NaX [X=hexafluorophosphate (PF6 ), perchlorate (ClO4 ), bis(trifluoromethanesulfonyl)imide (TFSI), fluorosulfonyl-(trifluoromethanesulfonyl)imide (FTFSI), and bis(fluorosulfonyl)imide (FSI)] salts and solvent mixtures [ethylene carbonate (EC)/dimethyl carbonate (DMC), EC/diethyl carbonate (DEC), and EC/propylene carbonate (PC)] with respect to the Al current collector stability, formation of soluble degradation compounds, reactivity towards sodiated hard carbon (Nax -HC), and solid-electrolyte interphase (SEI) layer formation. Cyclic voltammetry demonstrates that the stability of Al is highly influenced by the nature of the anions, solvents, and additives. GC-MS analysis reveals that the formation of SEI telltales depends on the nature of the linear alkyl carbonates and the battery chemistry (Li(+) vs. Na(+) ). FTIR spectroscopy shows that double alkyl carbonates are the main components of the SEI layer on Nax -HC. In the presence of Na salts, EC/DMC and EC/DEC presented a higher reactivity towards Nax -HC than EC/PC. For a fixed solvent mixture, the onset temperature follows the sequence NaClO4

Quantitative investigation of the gassing behavior in cylindrical Li4Ti5O12 batteries

NASA Astrophysics Data System (ADS)

Wang, Qian; Zhang, Jian; Liu, Wei; Xie, Xiaohua; Xia, Baojia

2017-03-01

The Li4Ti5O12 gassing behavior is a critical limitation for applications in lithium-ion batteries. The impact of electrode/electrolyte interface, as well as the underlying mechanisms involved during the gassing process, are still debated. Herein, a quantitative evolution of the internal pressure in 18650-type cylindrical Li4Ti5O12 batteries is investigated using a self-designed pressure testing device. The results indicate that the internal pressure significantly increases during the formation cycle and continues growing during the following cycles. After several charge and discharge cycles, the pressure finally reaches constant. Simultaneously, the formation of the solid electrolyte interphase (SEI) film is also investigated. The results suggest that the initial formed SEI film has a thickness of 24 nm, and is observed to shrink during the following cycles. Furthermore, no apparent increase in thickness accompanying the pressure rising is noticed. These comparative investigations reveal a possible mechanism of the gassing behavior. We suggest that the gassing behavior is associated with side reactions which are determined by the potential of the Li4Ti5O12 electrode, where the active sites of the electrode/electrolyte interface manage the extent of the reaction.

Enhanced charging capability of lithium metal batteries based on lithium bis(trifluoromethanesulfonyl)imide-lithium bis(oxalato)borate dual-salt electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiang, Hongfa; Shi, Pengcheng; Bhattacharya, Priyanka

2016-06-01

Rechargeable lithium (Li) metal batteries with conventional LiPF6-carbonate electrolytes have been reported to fail quickly at charging current densities of about 1.0 mA cm-2 and above. In this work, we demonstrate the rapid charging capability of the Li||LiNi0.8Co0.15Al0.05O2 (NCA) cells enabled by a dual-salt electrolyte of LiTFSI-LiBOB in a carbonate solvent mixture. It is found that the thickness of solid electrolyte interphase (SEI) layer on Li metal anode largely increases with increasing charging current density. However, the cells using the LiTFSI-LiBOB dual-salt electrolyte significantly outperforms those using the LiPF6 electrolyte at high charging current densities. At the charging current densitymore » of 1.50 mA cm-2, the Li||NCA cells with the dual-salt electrolyte can still deliver a discharge capacity of 131 mAh g-1 and a capacity retention of 80% after 100 cycles, while those with the LiPF6 electrolyte start to show fast capacity fading after the 30th cycle and only exhibit a low capacity of 25 mAh g-1 and a low retention of 15% after 100 cycles. The reasons for the good chargeability and cycling stability of the cells using LiTFSI-LiBOB dual-salt electrolyte can be attributed to the good film-formation ability of the electrolyte on lithium metal anode and the highly conductive nature of the sulfur-rich interphase layer.« less

The effect of water-containing electrolyte on lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Wu, Heng-Liang; Haasch, Richard T.; Perdue, Brian R.; Apblett, Christopher A.; Gewirth, Andrew A.

2017-11-01

Dissolved polysulfides, formed during Li-S battery operation, freely migrate and react with both the Li anode and the sulfur cathode. These soluble polysulfides shuttle between the anode and cathode - the so-called shuttle effect - resulting in an infinite recharge process and poor Columbic efficiency. In this study, water present as an additive in the Li-S battery electrolyte is found to reduce the shuttle effect in Li-S batteries. Batteries where water content was below 50 ppm exhibited a substantial shuttle effect and low charge capacity. Alternatively, addition of 250 ppm water led to stable charge/discharge behavior with high Coulombic efficiency. XPS results show that H2O addition results in the formation of solid electrolyte interphase (SEI) film with more LiOH on Li anode which protects the Li anode from the polysulfides. Batteries cycled without water result in a SEI film with more Li2CO3 likely formed by direct contact between the Li metal and the solvent. Intermediate quantities of H2O in the electrolyte result in high cycle efficiency for the first few cycles which then rapidly decays. This suggests that H2O is consumed during battery cycling, likely by interaction with freshly exposed Li metal formed during Li deposition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shkrob, Ilya A.; Pupek, Krzysztof Z.; Gilbert, James A.

Lithium hexafluorophosphate (LiPF 6) is ubiquitous in commercial lithium-ion batteries, but it is hydrolytically unstable and corrosive on electrode surfaces. Using a more stable salt would confer multiple benefits for high-voltage operation, but many such electrolyte systems facilitate anodic dissolution and pitting corrosion of aluminum current collectors that negate their advantages. Lithium 2-trifluoromethyl-4,5-dicyanoimidazolide (LiTDI) is a new salt that was designed specifically for high-voltage cells. In this study we demonstrate that in carbonate electrolytes, LiTDI prevents anodic dissolution of Al current collectors, which places it into a select group of corrosion inhibitors. However, we also demonstrate that LiTDI becomes reducedmore » on lithiated graphite, undergoing sequential defluorination and yielding a thick and resistive solid-electrolyte interphase (SEI), which increases impedance and lowers electrode capacity. The mechanistic causes for this behavior are examined using computational chemistry methods in the light of recent spectroscopic studies. Here, we demonstrate that LiTDI reduction can be prevented by certain electrolyte additives, which include fluoroethylene carbonate, vinylene carbonate and lithium bis(oxalato)borate. This beneficial action is due to preferential reduction of these additives over LiTDI at a higher potential vs. Li/Li +, so the resulting SEI can prevent the direct reduction of LiTDI at lower potentials on the graphite electrode.« less

Capacity Fade and Its Mitigation in Li-Ion Cells with Silicon-Graphite Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bareño, Javier; Shkrob, Ilya A.; Gilbert, James A.

In this study we scrutinize the causes for capacity fade in lithium-ion cells containing silicongraphite (Si-Gr) blends in the negative electrode and examine approaches for minimizing this fade. The causal mechanisms are inferred from data obtained by electrochemistry, microscopy, spectroscopy and thermogravimetry techniques. The presence of SiOxFy signals in the Si-Gr electrode, LixPOyFz compounds in the electrolyte, and SiO2 species on the NCM523 positive electrode, highlight the crucial role of hydrolytically generated HF, which accelerates the degradation of Si particles. The hydrolysis could result from residual moisture in the current electrode fabrication process, which uses aqueous binders. Water can alsomore » be released when silanol groups on the Si nanoparticles react with HF to form Si-F compounds. We note that the primary cause of capacity fade in the full cells is the loss of solid electrolyte interphase (SEI) integrity resulting from volume changes in Si particles during electrochemical cycling. Adding fluoroethylene carbonate (FEC) to the conventional electrolyte slows capacity fade through the formation of a cross linked polymer with elastomeric properties. Further gains in cell longevity are possible by excluding water during electrode fabrication, using hydrolytically stable lithium salts, and adopting electrolyte systems that provide more elasticity to the SEI layers.« less

Electrolyte volume effects on electrochemical performance and solid electrolyte interphase in Si-graphite/NMC lithium-ion pouch cells

DOE PAGES

An, Seong Jin; Li, Jianlin; Daniel, Claus; ...

2017-05-15

This study aims to explore the correlations between electrolyte volume, electrochemical performance, and properties of the solid electrolyte interphase in pouch cells with Si-graphite composite anodes. The electrolyte is 1.2 M LiPF 6 in ethylene carbonate:ethylmethyl carbonate with 10 wt.% fluoroethylene carbonate. Single layer pouch cells (100 mAh) were constructed with 15 wt.% Si-graphite/LiNi 0.5Mn 0.3CO 0.2O 2 electrodes. It is found that a minimum electrolyte volume factor of 3.1 times the total pore volume of cell components (cathode, anode, and separator) is needed for better cycling stability. Less electrolyte causes increases in ohmic and charge transfer resistances. Lithium dendritesmore » are observed when the electrolyte volume factor is low. The resistances from the anodes become significant as the cells are discharged. As a result, solid electrolyte interphase thickness grows as the electrolyte volume factor increases and is non-uniform after cycling.« less

Effects of Propylene Carbonate Content in CsPF6-Containing Electrolytes on the Enhanced Performances of Graphite Electrode for Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jianming; Yan, Pengfei; Cao, Ruiguo

2016-02-10

Cesium salt has been demonstrated as an efficient electrolyte additive in suppressing the lithium (Li) dendrite formation and directing the formation of an ultrathin and stable solid electrolyte interphase (SEI) even in propylene carbonate (PC)-ethylene carbonate (EC)-based electrolytes. Here, we further investigate the effect of PC content in the presence of CsPF6 additive (0.05 M) on the performances of graphite electrode in Li||graphite half cells and in graphite||LiNi0.80Co0.15Al0.05O2 (NCA) full cells. It is found that the performance of graphite electrode is also affected by PC content even though CsPF6 additive is present in the electrolytes. An optimal PC content ofmore » 20% by weight in the solvent mixtures is identified. The enhanced electrochemical performance of graphite electrode is attributed to the synergistic effects of the Cs+ additive and the PC solvent. The formation of a robust, ultrathin and compact SEI layer containing lithium-enriched species on the graphite electrode, directed by Cs+, effectively suppresses the PC co-intercalation and thus prevents the graphite exfoliation. This SEI layer is only permeable for de-solvated Li+ ions and allows fast Li+ ion transport through it, which therefore largely alleviates the Li dendrite formation on graphite electrode during lithiation even at high current densities. The presence of low-melting-point PC solvent also enables the sustainable operation of the graphite||NCA full cells under a wide spectrum of temperatures. The fundamental findings of this work shed light on the importance of manipulating/maintaining the electrode/electrolyte interphasial stability in a variety of energy storage devices.« less

Designable ultra-smooth ultra-thin solid-electrolyte interphases of three alkali metal anodes.

PubMed

Gu, Yu; Wang, Wei-Wei; Li, Yi-Juan; Wu, Qi-Hui; Tang, Shuai; Yan, Jia-Wei; Zheng, Ming-Sen; Wu, De-Yin; Fan, Chun-Hai; Hu, Wei-Qiang; Chen, Zhao-Bin; Fang, Yuan; Zhang, Qing-Hong; Dong, Quan-Feng; Mao, Bing-Wei

2018-04-09

Dendrite growth of alkali metal anodes limited their lifetime for charge/discharge cycling. Here, we report near-perfect anodes of lithium, sodium, and potassium metals achieved by electrochemical polishing, which removes microscopic defects and creates ultra-smooth ultra-thin solid-electrolyte interphase layers at metal surfaces for providing a homogeneous environment. Precise characterizations by AFM force probing with corroborative in-depth XPS profile analysis reveal that the ultra-smooth ultra-thin solid-electrolyte interphase can be designed to have alternating inorganic-rich and organic-rich/mixed multi-layered structure, which offers mechanical property of coupled rigidity and elasticity. The polished metal anodes exhibit significantly enhanced cycling stability, specifically the lithium anodes can cycle for over 200 times at a real current density of 2 mA cm -2 with 100% depth of discharge. Our work illustrates that an ultra-smooth ultra-thin solid-electrolyte interphase may be robust enough to suppress dendrite growth and thus serve as an initial layer for further improved protection of alkali metal anodes.

Co-solvents with high coulombic efficiency in propylene carbonate based electrolytes

DOEpatents

Liu, Gao; Zhao, Hui; Park, Sang-Jae

2017-06-27

A homologous series of cyclic carbonate or propylene carbonate (PC) analogue solvents with increasing length of linear alkyl substitutes were synthesized and used as co-solvents with PC for graphite based lithium ion half cells. A graphite anode reaches a capacity around 310 mAh/g in PC and its analogue co-solvents with 99.95% Coulombic efficiency. Cyclic carbonate co-solvents with longer alkyl chains are able to prevent exfoliation of graphite when used as co-solvents with PC. The cyclic carbonate co-solvents of PC compete for solvation of Li ion with PC solvent, delaying PC co-intercalation. Reduction products of PC on graphite surfaces via single-electron path form a stable Solid Electrolyte Interphase (SEI), which allows the reversible cycling of graphite.

Chemical stability of Lithium 2-trifluoromethyl-4,5-dicyanoimidazolide, an electrolyte salt for Li-ion cells

DOE PAGES

Shkrob, Ilya A.; Pupek, Krzysztof Z.; Gilbert, James A.; ...

2016-12-01

Lithium hexafluorophosphate (LiPF 6) is ubiquitous in commercial lithium-ion batteries, but it is hydrolytically unstable and corrosive on electrode surfaces. Using a more stable salt would confer multiple benefits for high-voltage operation, but many such electrolyte systems facilitate anodic dissolution and pitting corrosion of aluminum current collectors that negate their advantages. Lithium 2-trifluoromethyl-4,5-dicyanoimidazolide (LiTDI) is a new salt that was designed specifically for high-voltage cells. In this study we demonstrate that in carbonate electrolytes, LiTDI prevents anodic dissolution of Al current collectors, which places it into a select group of corrosion inhibitors. However, we also demonstrate that LiTDI becomes reducedmore » on lithiated graphite, undergoing sequential defluorination and yielding a thick and resistive solid-electrolyte interphase (SEI), which increases impedance and lowers electrode capacity. The mechanistic causes for this behavior are examined using computational chemistry methods in the light of recent spectroscopic studies. Here, we demonstrate that LiTDI reduction can be prevented by certain electrolyte additives, which include fluoroethylene carbonate, vinylene carbonate and lithium bis(oxalato)borate. This beneficial action is due to preferential reduction of these additives over LiTDI at a higher potential vs. Li/Li +, so the resulting SEI can prevent the direct reduction of LiTDI at lower potentials on the graphite electrode.« less

Guided Lithium Metal Deposition and Improved Lithium Coulombic Efficiency through Synergistic Effects of LiAsF 6 and Cyclic Carbonate Additives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Xiaodi; Zhang, Yaohui; Engelhard, Mark H.

Spatial and morphology control over lithium (Li) metal nucleation/growth, as well as improving Li Coulombic efficiency (CE) are of the most challenging issues for rechargeable Li metal batteries. Here, we report that LiAsF6 and vinylene carbonate (VC) can work synergistically to address these challenges. It is revealed that AsF6- can be reduced to Li3As and LiF, which can act as seeds for Li growth and form a robust solid electrolyte interphase (SEI) layer, respectively. The addition of VC is critical because it not only enables uniform AsF6- reduction by passivating the defect sites on Cu substrate, but also improves themore » SEI layer flexibility during the reductive polymerization process. As a result, highly compact, uniform and dendrite-free Li film with vertically aligned columns structure can be obtained with greatly increased Li CE, and the Li metal batteries using the electrolyte with both LiAsF6 and VC additives can have much improved cycle life.« less

Designing solid-liquid interphases for sodium batteries.

PubMed

Choudhury, Snehashis; Wei, Shuya; Ozhabes, Yalcin; Gunceler, Deniz; Zachman, Michael J; Tu, Zhengyuan; Shin, Jung Hwan; Nath, Pooja; Agrawal, Akanksha; Kourkoutis, Lena F; Arias, Tomas A; Archer, Lynden A

2017-10-12

Secondary batteries based on earth-abundant sodium metal anodes are desirable for both stationary and portable electrical energy storage. Room-temperature sodium metal batteries are impractical today because morphological instability during recharge drives rough, dendritic electrodeposition. Chemical instability of liquid electrolytes also leads to premature cell failure as a result of parasitic reactions with the anode. Here we use joint density-functional theoretical analysis to show that the surface diffusion barrier for sodium ion transport is a sensitive function of the chemistry of solid-electrolyte interphase. In particular, we find that a sodium bromide interphase presents an exceptionally low energy barrier to ion transport, comparable to that of metallic magnesium. We evaluate this prediction by means of electrochemical measurements and direct visualization studies. These experiments reveal an approximately three-fold reduction in activation energy for ion transport at a sodium bromide interphase. Direct visualization of sodium electrodeposition confirms large improvements in stability of sodium deposition at sodium bromide-rich interphases.The chemistry at the interface between electrolyte and electrode plays a critical role in determining battery performance. Here, the authors show that a NaBr enriched solid-electrolyte interphase can lower the surface diffusion barrier for sodium ions, enabling stable electrodeposition.

Offset Initial Sodium Loss To Improve Coulombic Efficiency and Stability of Sodium Dual-Ion Batteries.

PubMed

Ma, Ruifang; Fan, Ling; Chen, Suhua; Wei, Zengxi; Yang, Yuhua; Yang, Hongguan; Qin, Yong; Lu, Bingan

2018-05-09

Sodium dual-ion batteries (NDIBs) are attracting extensive attention recently because of their low cost and abundant sodium resources. However, the low capacity of the carbonaceous anode would reduce the energy density, and the formation of the solid-electrolyte interphase (SEI) in the anode during the initial cycles will lead to large amount consumption of Na + in the electrolyte, which results in low Coulombic efficiency and inferior stability of the NDIBs. To address these issues, a phosphorus-doped soft carbon (P-SC) anode combined with a presodiation process is developed to enhance the performance of the NDIBs. The phosphorus atom doping could enhance the electric conductivity and further improve the sodium storage property. On the other hand, an SEI could preform in the anode during the presodiation process; thus the anode has no need to consume large amounts of Na + to form the SEI during the cycling of the NDIBs. Consequently, the NDIBs with P-SC anode after the presodiation process exhibit high Coulombic efficiency (over 90%) and long cycle stability (81 mA h g -1 at 1000 mA g -1 after 900 cycles with capacity retention of 81.8%), far more superior to the unsodiated NDIBs. This work may provide guidance for developing high performance NDIBs in the future.

Transition metal dissolution, ion migration, electrocatalytic reduction and capacity loss in Lithium-ion full cells

DOE PAGES

Gilbert, James A.; Shkrob, Ilya A.; Abraham, Daniel P.

2017-01-05

Continuous operation of full cells with layered transition metal (TM) oxide positive electrodes (NCM523) leads to dissolution of TM ions and their migration and incorporation into the solid electrolyte interphase (SEI) of the graphite-based negative electrode. These processes correlate with cell capacity fade and accelerate markedly as the upper cutoff voltage (UCV) exceeds 4.30 V. At voltages ≥ 4.4 V there is enhanced fracture of the oxide during cycling that creates new surfaces and causes increased solvent oxidation and TM dissolution. Despite this deterioration, cell capacity fade still mainly results from lithium loss in the negative electrode SEI. Among TMs,more » Mn content in the SEI shows a better correlation with cell capacity loss than Co and Ni contents. As Mn ions become incorporated into the SEI, the kinetics of lithium trapping change from power to linear at the higher UCVs, indicating a large effect of these ions on SEI growth and implicating (electro)catalytic reactions. Lastly, we estimate that each Mn II ion deposited in the SEI causes trapping of ~10 2 additional Li + ions thereby hastening the depletion of cyclable lithium ions. Using these results, we sketch a mechanism for cell capacity fade, emphasizing the conceptual picture over the chemical detail.« less

Multistage Mechanism of Lithium Intercalation into Graphite Anodes in the Presence of the Solid Electrolyte Interface.

PubMed

Dinkelacker, Franz; Marzak, Philipp; Yun, Jeongsik; Liang, Yunchang; Bandarenka, Aliaksandr S

2018-04-25

A so-called solid electrolyte interface (SEI) in a lithium-ion battery largely determines the performance of the whole system. However, it is one of the least understood objects in these types of batteries. SEIs are formed during the initial charge-discharge cycles, prevent the organic electrolytes from further decomposition, and at the same time govern lithium intercalation into the graphite anodes. In this work, we use electrochemical impedance spectroscopy and atomic force microscopy to investigate the properties of a SEI film and an electrified "graphite/SEI/electrolyte interface". We reveal a multistage mechanism of lithium intercalation and de-intercalation in the case of graphite anodes covered by SEI. On the basis of this mechanism, we propose a relatively simple model, which perfectly explains the impedance response of the "graphite/SEI/electrolyte" interface at different temperatures and states of charge. From the whole data obtained in this work, it is suggested that not only Li + but also negatively charged species, such as anions from the electrolyte or functional groups of the SEI, likely interact with the surface of the graphite anode.

Effects of Propylene Carbonate Content in CsPF 6 -Containing Electrolytes on the Enhanced Performances of Graphite Electrode for Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jianming; Yan, Pengfei; Cao, Ruiguo

2016-02-15

The effects Of propylene carbonate (PC) content in CsPF6-containing electrolytes on the performances of graphite electrode in lithium half cells and in graphite parallel to LiNi0.80Co0.15Al0.05O2 (NCA) full cells are investigated. It is found that the performance of graphite electrode is significantly-affected by PC content in the CsPF6-containing electrolytes. An optimal PC content of 20% by weight in the solvent mixtures is identified. The enhanced electrochemical performance of graphite electrode can be attributed to the synergistic effects of the PC solvent and the Cs+ additive. The synergistic effects of Cs+ additive and appropriate amount of PC enable the formation ofmore » a robust, ultrathin, and compact solid electrolyte interphase (SEI) layer on the surface of graphite electrode, which is only permeable for desolvated Li+ ions and allows fast Li+ ion transport through it. Therefore, this SEI layer effectively suppresses the PC cointercalation and largely alleviates the Li dendrite formation on graphite electrode during lithiation even at relatively high current densities. The presence of low-melting-point PC solvent improves the sustainable operation of graphite parallel to NCA full cells under a wide temperature range. The fundamental findings also shed light On the importance of manipulating/maintaining the electrode/electrolyte interphasial stability in various energy-storage devices.« less

Structure and Li+ ion transport in a mixed carbonate/LiPF6 electrolyte near graphite electrode surfaces: a molecular dynamics study.

PubMed

Boyer, Mathew J; Vilčiauskas, Linas; Hwang, Gyeong S

2016-10-12

Electrolyte and electrode materials used in lithium-ion batteries have been studied separately to a great extent, however the structural and dynamical properties of the electrolyte-electrode interface still remain largely unexplored despite its critical role in governing battery performance. Using molecular dynamics simulations, we examine the structural reorganization of solvent molecules (cyclic ethylene carbonate : linear dimethyl carbonate 1 : 1 molar ratio doped with 1 M LiPF 6 ) in the vicinity of graphite electrodes with varying surface charge densities (σ). The interfacial structure is found to be sensitive to the molecular geometry and polarity of each solvent molecule as well as the surface structure and charge distribution of the negative electrode. We also evaluated the potential difference across the electrolyte-electrode interface, which exhibits a nearly linear variation with respect to σ up until the onset of Li + ion accumulation onto the graphite edges from the electrolyte. In addition, well-tempered metadynamics simulations are employed to predict the free-energy barriers to Li + ion transport through the relatively dense interfacial layer, along with analysis of the Li + solvation sheath structure. Quantitative analysis of the molecular arrangements at the electrolyte-electrode interface will help better understand and describe electrolyte decomposition, especially in the early stages of solid-electrolyte-interphase (SEI) formation. Moreover, the computational framework presented in this work offers a means to explore the effects of solvent composition, electrode surface modification, and operating temperature on the interfacial structure and properties, which may further assist in efforts to engineer the electrolyte-electrode interface leading to a SEI layer that optimizes battery performance.

Stable, fast and high-energy-density LiCoO2 cathode at high operation voltage enabled by glassy B2O3 modification

NASA Astrophysics Data System (ADS)

Zhou, Aijun; Wang, Weihang; Liu, Qin; Wang, Yi; Yao, Xu; Qing, Fangzhu; Li, Enzhu; Yang, Tingting; Zhang, Long; Li, Jingze

2017-09-01

In this work, commercial LiCoO2 is modified with a glassy B2O3 by solution mixing with H3BO3 followed by post-calcination in order to enhance its high-voltage electrochemical performance. The glassy B2O3 coating/additive is believed to serve as an effective physiochemical buffer and protection between LiCoO2 and liquid electrolyte, which can suppress the high-voltage induced electrolyte decomposition and active material dissolution. During the early cycling and due to the electrochemical force, the as-coated B2O3 glasses which have 3D open frameworks tend to accommodate some mobile Li+ and form a more chemically-resistant and ion-conductive lithium boron oxide (LBO) interphase as a major component of the solid electrolyte interphase (SEI), which consequently enables much easier Li+ diffusion/transfer at the solid-liquid interfaces upon further cycling. Due to the synergetic effects of B2O3 coating/modification, the high-voltage capacity and energy density of the B2O3-modified LiCoO2 cathode are promisingly improved by 35% and 30% after 100 cycles at 1 C within 3.0-4.5 V vs. Li/Li+. Meanwhile, the high-rate performance of the B2O3-modified electrode is even more greatly improved, showing a capacity of 105 mAh g-1 at 10 C while the bare electrode has dropped to no more than 30 mAh g-1 under this rate condition.

Cycling behavior of NCM523/graphite lithium-ion cells in the 3–4.4 V range: Diagnostic studies of full cells and harvested electrodes

DOE PAGES

Gilbert, James A.; Bareño, Javier; Spila, Timothy; ...

2016-09-22

Energy density of full cells containing layered-oxide positive electrodes can be increased by raising the upper cutoff voltage above the current 4.2 V limit. In this article we examine aging behavior of cells, containing LiNi 0.5Co 0.2Mn 0.3O 2 (NCM523)-based positive and graphite-based negative electrodes, which underwent up to ~400 cycles in the 3-4.4 V range. Electrochemistry results from electrodes harvested from the cycled cells were obtained to identify causes of cell performance loss; these results were complemented with data from X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) measurements. Our experiments indicate that the full cell capacitymore » fade increases linearly with cycle number and results from irreversible lithium loss in the negative electrode solid electrolyte interphase (SEI) layer. The accompanying electrode potential shift reduces utilization of active material in both electrodes and causes the positive electrode to cycle at higher states-of-charge. Here, full cell impedance rise on aging arises primarily at the positive electrode and results mainly from changes at the electrode-electrolyte interface; the small growth in negative electrode impedance reflects changes in the SEI layer. Our results indicate that cell performance loss could be mitigated by modifying the electrode-electrolyte interfaces through use of appropriate electrode coatings and/or electrolyte additives.« less

Suppression of dendritic lithium growth in lithium metal-based batteries.

PubMed

Li, Linlin; Li, Siyuan; Lu, Yingying

2018-06-19

Lithium metal-based batteries offer promising prospects as alternatives to today's lithium-ion batteries, due to their ultra-high energy density. Unfortunately, the application of lithium metal is full of challenges and has puzzled researchers for more than 40 years. In this feature article, we describe the history of the development of lithium metal batteries and their existing key challenges, which include non-uniform electrodeposition, volume expansion, high reactivity of the lithium metal/unstable solid electrolyte interphase (SEI), and the shuttling of active cathode materials. Then, we focus on the growth mechanisms of uneven lithium electrodeposition and extend the discussion to the approaches to inhibit lithium dendrites. Finally, we discuss future directions that are expected to drive progress in the development of lithium metal batteries.

Estimating the thickness of diffusive solid electrolyte interface

NASA Astrophysics Data System (ADS)

Wang, XiaoHe; Shen, WenHao; Huang, XianFu; Zang, JinLiang; Zhao, YaPu

2017-06-01

The solid electrolyte interface (SEI) is a hierarchical structure formed in the transition zone between the electrode and the electrolyte. The properties of lithium-ion (Li-ion) battery, such as cycle life, irreversible capacity loss, self-discharge rate, electrode corrosion and safety are usually ascribed to the quality of the SEI, which are highly dependent on the thickness. Thus, understanding the formation mechanism and the SEI thickness is of prime interest. First, we apply dimensional analysis to obtain an explicit relation between the thickness and the number density in this study. Then the SEI thickness in the initial charge-discharge cycle is analyzed and estimated for the first time using the Cahn-Hilliard phase-field model. In addition, the SEI thickness by molecular dynamics simulation validates the theoretical results. It has been shown that the established model and the simulation in this paper estimate the SEI thickness concisely within order-of-magnitude of nanometers. Our results may help in evaluating the performance of SEI and assist the future design of Li-ion battery.

Understanding electrical conduction in lithium ion batteries through multi-scale modeling

NASA Astrophysics Data System (ADS)

Pan, Jie

Silicon (Si) has been considered as a promising negative electrode material for lithium ion batteries (LIBs) because of its high theoretical capacity, low discharge voltage, and low cost. However, the utilization of Si electrode has been hampered by problems such as slow ionic transport, large stress/strain generation, and unstable solid electrolyte interphase (SEI). These problems severely influence the performance and cycle life of Si electrodes. In general, ionic conduction determines the rate performance of the electrode, while electron leakage through the SEI causes electrolyte decomposition and, thus, causes capacity loss. The goal of this thesis research is to design Si electrodes with high current efficiency and durability through a fundamental understanding of the ionic and electronic conduction in Si and its SEI. Multi-scale physical and chemical processes occur in the electrode during charging and discharging. This thesis, thus, focuses on multi-scale modeling, including developing new methods, to help understand these coupled physical and chemical processes. For example, we developed a new method based on ab initio molecular dynamics to study the effects of stress/strain on Li ion transport in amorphous lithiated Si electrodes. This method not only quantitatively shows the effect of stress on ionic transport in amorphous materials, but also uncovers the underlying atomistic mechanisms. However, the origin of ionic conduction in the inorganic components in SEI is different from that in the amorphous Si electrode. To tackle this problem, we developed a model by separating the problem into two scales: 1) atomistic scale: defect physics and transport in individual SEI components with consideration of the environment, e.g., LiF in equilibrium with Si electrode; 2) mesoscopic scale: defect distribution near the heterogeneous interface based on a space charge model. In addition, to help design better artificial SEI, we further demonstrated a theoretical design of multicomponent SEIs by utilizing the synergetic effect found in the natural SEI. We show that the electrical conduction can be optimized by varying the grain size and volume fraction of two phases in the artificial multicomponent SEI.

Behavior of Lithium Metal Anodes under Various Capacity Utilization and High Current Density in Lithium Metal Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiao, Shuhong; Zheng, Jianming; Li, Qiuyan

Lithium (Li) metal batteries (LMBs) are regarded as the most promising power sources for electric vehicles. Besides the Li dendrite growth and low Li Coulombic efficiency, how to well match Li metal anode with a high loading (normally over 3.0 mAh cm-2) cathode is another key challenge to achieve the real high energy density battery. In this work, we systematically investigate the effects of the Li metal capacity usage in each cycle, manipulated by varying the cathode areal loading, on the stability of Li metal anode and the cycling performance of LMBs using the LiNi1/3Mn1/3Co1/3O2 (NMC) cathode and an additive-containingmore » dual-salt/carbonate-solvent electrolyte. It is demonstrated that the Li||NMC cells show decent long-term cycling performance even with NMC areal capacity loading up to ca. 4.0 mAh cm-2 and at a charge current density of 1.0 mA cm-2. The increase of the Li capacity usage in each cycle causes variation in the components of the solid electrolyte interphase (SEI) layer on Li metal anode and generates more ionic conductive species from this electrolyte. Further study reveals for the first time that the degradation of Li metal anode and the thickness of SEI layer on Li anode show linear relationship with the areal capacity of NMC cathode. Meanwhile, the expansion rate of consumed Li and the ratio of SEI thickness to NMC areal loading are kept almost the same value with increasing cathode loading, respectively. These fundamental findings provide new perspectives on the rational evaluation of Li metal anode stability for the development of rechargeable LMBs.« less

A self-cleaning Li-S battery enabled by a bifunctional redox mediator

NASA Astrophysics Data System (ADS)

Ren, Y. X.; Zhao, T. S.; Liu, M.; Zeng, Y. K.; Jiang, H. R.

2017-09-01

The polysulfide shuttle effect and lithium dendrite growth in lithium-sulfur (Li-S) batteries can repeatedly breach the anodic solid electrolyte interphase (SEI) over cycling. As a result, irreversible short-chain sulfide side products (Li2Sx, x = 1, 2) keep depositing on the Li anode, leading to the active material loss, increasing the Li+ transport resistance, and thereby reducing the cycle life. In this work, indium iodide (InI3) is investigated as a bifunctional electrolyte additive for Li-S batteries to protect the Li anode and decompose the side products spontaneously. On the one hand, Indium (In) is electrodeposited onto the Li anode prior to Li plating during the initial charging process, forming a chemically and mechanically stable SEI to prevent the Li anode from reacting with soluble polysulfide species to form Li2Sx (x = 1, 2) side products. On the other hand, by adequately overcharging the battery, the triiodide/iodide redox mediator is capable of chemically transforming side products deposited on the Li anode and separator into soluble polysulfides, which can be recycled by the cathode. It is shown that the battery with the InI3 additive exhibits a prolonged cycle life, and is capable of retrieving its capacity by a facile overcharging process.

Double-plasma enhanced carbon shield for spatial/interfacial controlled electrodes in lithium ion batteries via micro-sized silicon from wafer waste

NASA Astrophysics Data System (ADS)

Chen, Bing-Hong; Chuang, Shang-I.; Duh, Jenq-Gong

2016-11-01

Using spatial and interfacial control, the micro-sized silicon waste from wafer slurry could greatly increase its retention potential as a green resource for silicon-based anode in lithium ion batteries. Through step by step spatial and interfacial control for electrode, the cyclability of recycled waste gains potential performance from its original poor retention property. In the stages of spatial control, the electrode stabilizers of active, inactive and conductive additives were mixed into slurries for maintaining architecture and conductivity of electrode. In addition, a fusion electrode modification of interfacial control combines electrolyte additive, technique of double-plasma enhanced carbon shield (D-PECS) to convert the chemical bond states and to alter the formation of solid electrolyte interphases (SEIs) in the first cycle. The depth profiles of chemical composition from external into internal electrode illustrate that the fusion electrode modification not only forms a boundary to balance the interface between internal and external electrodes but also stabilizes the SEIs formation and soothe the expansion of micro-sized electrode. Through these effect approaches, the performance of micro-sized Si waste electrode can be boosted from its serious capacity degradation to potential retention (200 cycles, 1100 mAh/g) and better meet the requirements for facile and cost-effective in industrial production.

Effects of Anion Mobility on Electrochemical Behaviors of Lithium–Sulfur Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Kee Sung; Chen, Junzheng; Cao, Ruiguo

The electrolyte is a crucial component of lithium-sulfur (Li-S) batteries, as it controls polysulfide dissolution, charge shuttling processes, and solid-electrolyte interphase (SEI) layer formation. Experimentally, the overall performance of Li-S batteries varies with choice of solvent system and Li-salt used in the electrolyte, and a lack of predictive understanding about the effects of individual electrolyte components inhibits the rational design of electrolytes for Li-S batteries. Here we analyze the role of the counter anions of common Li salts (such as TfO-, FSI-, TFSI-, and TDI-) when dissolved in DOL/DME (1:1 vol.) for use in Li-S batteries. The evolution of ion-ionmore » and ion-solvent interactions due to vari-ous anions was analyzed using 17O NMR and pulsed-field gradient (PFG) NMR and then correlated with electrochemi-cal performance in Li-S cells. These data reveal that the for-mation of the passivation layer on the anode and the loss of active materials from the cathode (evidenced by polysulfide dissolution) are related to anion mobility and affinity with lithium polysulfide, respectively. For future electrolyte de-sign, anions with lower mobility and weaker interactions with lithium polysulfides may be superior candidates for increasing the long-term stability of Li-S batteries.« less

Fluorinated phosphazene co-solvents for improved thermal and safety performance in lithium-ion battery electrolytes

NASA Astrophysics Data System (ADS)

Rollins, Harry W.; Harrup, Mason K.; Dufek, Eric J.; Jamison, David K.; Sazhin, Sergiy V.; Gering, Kevin L.; Daubaras, Dayna L.

2014-10-01

The safety of lithium-ion batteries is coming under increased scrutiny as they are being adopted for large format applications especially in the vehicle transportation industry and for grid-scale energy storage. The primary short-comings of lithium-ion batteries are the flammability of the liquid electrolyte and sensitivity to high voltage and elevated temperatures. We have synthesized a series of non-flammable fluorinated phosphazene liquids and blended them with conventional carbonate solvents. While the use of these phosphazenes as standalone electrolytes is highly desirable, they simply do not satisfy all of the many requirements that must be met such as high LiPF6 solubility and low viscosity, thus we have used them as additives and co-solvents in blends with typical carbonates. The physical and electrochemical properties of the electrolyte blends were characterized, and then the blends were used to build 2032-type coin cells. We have evaluated the performance of the electrolytes by determining the physical properties, thermal stability, electrochemical window, cell cycling data, and the ability to form solid electrolyte interphase (SEI) films. This paper presents our most recent results on a new series of fluorinated cyclic phosphazene trimers, the FM series, which has exhibited numerous beneficial effects on battery performance, lifetimes, and safety aspects.

Fast formation cycling for lithium ion batteries

DOE PAGES

An, Seong Jin; Li, Jianlin; Du, Zhijia; ...

2017-01-09

The formation process for lithium ion batteries typically takes several days or more, and it is necessary for providing a stable solid electrolyte interphase on the anode (at low potentials vs. Li/Li +) for preventing irreversible consumption of electrolyte and lithium ions. An analogous layer known as the cathode electrolyte interphase layer forms at the cathode at high potentials vs. Li/Li +. However, several days, or even up to a week, of these processes result in either lower LIB production rates or a prohibitively large size of charging-discharging equipment and space (i.e. excessive capital cost). In this study, a fastmore » and effective electrolyte interphase formation protocol is proposed and compared with an Oak Ridge National Laboratory baseline protocol. Graphite, NMC 532, and 1.2 M LiPF 6 in ethylene carbonate: diethyl carbonate were used as anodes, cathodes, and electrolytes, respectively. Finally, results from electrochemical impedance spectroscopy show the new protocol reduced surface film (electrolyte interphase) resistances, and 1300 aging cycles show an improvement in capacity retention.« less

Critical evaluation of the stability of highly concentrated LiTFSI - Acetonitrile electrolytes vs. graphite, lithium metal and LiFePO4 electrodes

NASA Astrophysics Data System (ADS)

Nilsson, Viktor; Younesi, Reza; Brandell, Daniel; Edström, Kristina; Johansson, Patrik

2018-04-01

Highly concentrated LiTFSI - acetonitrile electrolytes have recently been shown to stabilize graphite electrodes in lithium-ion batteries (LIBs) much better than comparable more dilute systems. Here we revisit this system in order to optimise the salt concentration vs. both graphite and lithium metal electrodes with respect to electrochemical stability. However, we observe an instability regardless of concentration, making lithium metal unsuitable as a counter electrode, and this also affects evaluation of e.g. graphite electrodes. While the highly concentrated electrolytes have much improved electrochemical stabilities, their reductive decomposition below ca. 1.2 V vs. Li+/Li° still makes them less practical vs. graphite electrodes, and the oxidative reaction with Al at ca. 4.1 V vs. Li+/Li° makes them problematic for high voltage LIB cells. The former originates in an insufficiently stable solid electrolyte interphase (SEI) dissolving and continuously reforming - causing self-discharge, as observed by paused galvanostatic cycling, while the latter is likely caused by aluminium current collector corrosion. Yet, we show that medium voltage LiFePO4 positive electrodes can successfully be used as counter and reference electrodes.

Self-healing SEI enables full-cell cycling of a silicon-majority anode with a coulombic efficiency exceeding 99.9%

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Yang; Li, Sa; Kushima, Akihiro

Despite active developments, full-cell cycling of Li-battery anodes with >50 wt% Si (a Si-majority anode, SiMA) is rare. The main challenge lies in the solid electrolyte interphase (SEI), which when formed naturally (nSEI), is fragile and cannot tolerate the large volume changes of Si during lithiation/delithiation. An artificial SEI (aSEI) with a specific set of mechanical characteristics is henceforth designed; we enclose Si within a TiO 2 shell thinner than 15 nm, which may or may not be completely hermetic at the beginning. In situ TEM experiments show that the TiO 2 shell exhibits 5× greater strength than an amorphousmore » carbon shell. Void-padded compartmentalization of Si can survive the huge volume changes and electrolyte ingression, with a self-healing aSEI + nSEI. The half-cell capacity exceeds 990 mA h g -1 after 1500 cycles. To improve the volumetric capacity, we further compress SiMA 3-fold from its tap density (0.4 g cm -3) to 1.4 g cm -3, and then run the full-cell battery tests against a 3 mA h cm -2 LiCoO 2 cathode. Despite some TiO 2 enclosures being inevitably broken, 2× the volumetric capacity (1100 mA h cm -3) and 2× the gravimetric capacity (762 mA h g -1) of commercial graphite anode is achieved in stable full-cell battery cycling, with a stabilized areal capacity of 1.6 mA h cm -2 at the 100th cycle. The initial lithium loss, characterized by the coulombic inefficiency (CI), is carefully tallied on a logarithmic scale and compared with the actual full-cell capacity loss. In conclusion, it is shown that a strong, non-adherent aSEI, even if partially cracked, facilitates an adaptive self-repair mechanism that enables full-cell cycling of a SiMA, leading to a stabilized coulombic efficiency exceeding 99.9%.« less

Self-healing SEI enables full-cell cycling of a silicon-majority anode with a coulombic efficiency exceeding 99.9%

DOE PAGES

Jin, Yang; Li, Sa; Kushima, Akihiro; ...

2017-01-06

Despite active developments, full-cell cycling of Li-battery anodes with >50 wt% Si (a Si-majority anode, SiMA) is rare. The main challenge lies in the solid electrolyte interphase (SEI), which when formed naturally (nSEI), is fragile and cannot tolerate the large volume changes of Si during lithiation/delithiation. An artificial SEI (aSEI) with a specific set of mechanical characteristics is henceforth designed; we enclose Si within a TiO 2 shell thinner than 15 nm, which may or may not be completely hermetic at the beginning. In situ TEM experiments show that the TiO 2 shell exhibits 5× greater strength than an amorphousmore » carbon shell. Void-padded compartmentalization of Si can survive the huge volume changes and electrolyte ingression, with a self-healing aSEI + nSEI. The half-cell capacity exceeds 990 mA h g -1 after 1500 cycles. To improve the volumetric capacity, we further compress SiMA 3-fold from its tap density (0.4 g cm -3) to 1.4 g cm -3, and then run the full-cell battery tests against a 3 mA h cm -2 LiCoO 2 cathode. Despite some TiO 2 enclosures being inevitably broken, 2× the volumetric capacity (1100 mA h cm -3) and 2× the gravimetric capacity (762 mA h g -1) of commercial graphite anode is achieved in stable full-cell battery cycling, with a stabilized areal capacity of 1.6 mA h cm -2 at the 100th cycle. The initial lithium loss, characterized by the coulombic inefficiency (CI), is carefully tallied on a logarithmic scale and compared with the actual full-cell capacity loss. In conclusion, it is shown that a strong, non-adherent aSEI, even if partially cracked, facilitates an adaptive self-repair mechanism that enables full-cell cycling of a SiMA, leading to a stabilized coulombic efficiency exceeding 99.9%.« less

NREL Research Overcomes Major Technical Obstacles in Magnesium-Metal

Science.gov Websites

Chunmei Ban are co-authors of the Nature Chemistry white paper, "An Artificial Interphase Enables corresponding author of the paper, "An Artificial Interphase Enables Reversible Magnesium Chemistry in an artificial solid-electrolyte interphase from polyacrylonitrile and magnesium-ion salt that

Caramel popcorn shaped silicon particle with carbon coating as a high performance anode material for Li-ion batteries.

PubMed

He, Meinan; Sa, Qina; Liu, Gao; Wang, Yan

2013-11-13

Silicon is a very promising anode material for lithium ion batteries. It has a 4200 mAh/g theoretical capacity, which is ten times higher than that of commercial graphite anodes. However, when lithium ions diffuse to Si anodes, the volume of Si will expand to almost 400% of its initial size and lead to the crack of Si. Such a huge volume change and crack cause significant capacity loss. Meanwhile, with the crack of Si particles, the conductivity between the electrode and the current collector drops. Moreover, the solid electrolyte interphase (SEI), which is generated during the cycling, reduces the discharge capacity. These issues must be addressed for widespread application of this material. In this work, caramel popcorn shaped porous silicon particles with carbon coating are fabricated by a set of simple chemical methods as active anode material. Si particles are etched to form a porous structure. The pores in Si provide space for the volume expansion and liquid electrolyte diffusion. A layer of amorphous carbon is formed inside the pores, which gives an excellent isolation between the Si particle and electrolyte, so that the formation of the SEI layer is stabilized. Meanwhile, this novel structure enhances the mechanical properties of the Si particles, and the crack phenomenon caused by the volume change is significantly restrained. Therefore, an excellent cycle life under a high rate for the novel Si electrode is achieved.

The Effect of Electrolyte Additives upon the Lithium Kinetics of Li-Ion Cells Containing MCMB and LiNi(x)Co(1-x)O2 Electrodes and Exposed to High Temperatures

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Gozdz, A. S.; Mani, S.

2009-01-01

With the intent of improving the performance of lithium-ion cells at high temperatures, we have investigated the use of a number of electrolyte additives in experimental MCMB- Li(x)Ni(y)Co(1-y)O2 cells, which were exposed to temperatures as high as 80 C. In the present work, we have evaluated the use of a number of additives, namely vinylene carbonate (VC), dimethyl acetamide (DMAc), and mono-fluoroethylene carbonate (FEC), in an electrolyte solution anticipated to perform well at warm temperature (i.e., 1.0M LiPF6 in EC+EMC (50:50 v/v %). In addition, we have explored the use of novel electrolyte additives, namely lithium oxalate and lithium tetraborate. In addition to determining the capacity and power losses at various temperatures sustained as a result of high temperature cycling (cycling performed at 60 and 80 C), the three-electrode MCMB-Li(x)Ni(y)Co(1-y)O2 cells (lithium reference) enabled us to study the impact of high temperature storage upon the solid electrolyte interphase (SEI) film characteristics on carbon anodes (MCMB-based materials), metal oxide cathodes, and the subsequent impact upon electrode kinetics.

Li 2OHCl crystalline electrolyte for stable metallic lithium anodes

DOE PAGES

Hood, Zachary D.; Wang, Hui; Samuthira Pandian, Amaresh; ...

2016-01-22

In a classic example of stability from instability, we show that Li 2OHCl solid electrolyte forms a stable solid electrolyte interface (SEI) with metallic lithium anode. The Li 2OHCl solid electrolyte can be readily achieved through simple mixing of air-stable LiOH and LiCl precursors with a mild processing temperature under 400 °C. Additionally, we show that continuous, dense Li 2OHCl membranes can be fabricated at temperatures less than 400 °C, standing in great contrast to current processing temperatures of over 1600 °C for most oxide-based solid electrolytes. The ionic conductivity and Arrhenius activation energy were explored for the LiOH-LiCl systemmore » of crystalline solid electrolytes where Li 2OHCl with increased crystal defects was found to have the highest ionic conductivity and reasonable Arrhenius activation energy. The Li 2OHCl solid electrolyte displays stability against metallic lithium, even in extreme conditions past the melting point of lithium metal. Furthermore, to understand this excellent stability, we show that SEI formation is critical in stabilizing the interface between metallic lithium and the Li 2OHCl solid electrolyte.« less

A Fluorinated Ether Electrolyte Enabled High Performance Prelithiated Graphite/Sulfur Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Shuru; Yu, Zhaoxin; Gordin, Mikhail L.

Lithium/sulfur (Li/S) batteries have attracted great attention as a promising energy storage technology, but so far their practical applications are greatly hindered by issues of polysulfide shuttling and unstable lithium/electrolyte interface. To address these issues, a feasible strategy is to construct a rechargeable prelithiated graphite/sulfur batteries. In this study, a fluorinated ether of bis(2,2,2-trifluoroethyl) ether (BTFE) was reported to blend with 1,3-dioxolane (DOL) for making a multifunctional electrolyte of 1.0 M LiTFSI DOL/BTFE (1:1, v/v) to enable high performance prelithiated graphite/S batteries. First, the electrolyte significantly reduces polysulfide solubility to suppress the deleterious polysulfide shuttling and thus improves capacity retentionmore » of sulfur cathodes. Second, thanks to the low viscosity and good wettability, the fluorinated electrolyte dramatically enhances the reaction kinetics and sulfur utilization of high-areal-loading sulfur cathodes. More importantly, this electrolyte forms a stable solid-electrolyte interphase (SEI) layer on graphite surface and thus enables remarkable cyclability of graphite anodes. Lastly, by coupling prelithiated graphite anodes with sulfur cathodes with high areal capacity of ~3 mAh cm -2, we demonstrate prelithiated graphite/sulfur batteries that show high sulfur-specific capacity of ~1000 mAh g -1 and an excellent capacity retention of >65% after 450 cycles at C/10.« less

A Fluorinated Ether Electrolyte Enabled High Performance Prelithiated Graphite/Sulfur Batteries

DOE PAGES

Chen, Shuru; Yu, Zhaoxin; Gordin, Mikhail L.; ...

2017-02-03

Lithium/sulfur (Li/S) batteries have attracted great attention as a promising energy storage technology, but so far their practical applications are greatly hindered by issues of polysulfide shuttling and unstable lithium/electrolyte interface. To address these issues, a feasible strategy is to construct a rechargeable prelithiated graphite/sulfur batteries. In this study, a fluorinated ether of bis(2,2,2-trifluoroethyl) ether (BTFE) was reported to blend with 1,3-dioxolane (DOL) for making a multifunctional electrolyte of 1.0 M LiTFSI DOL/BTFE (1:1, v/v) to enable high performance prelithiated graphite/S batteries. First, the electrolyte significantly reduces polysulfide solubility to suppress the deleterious polysulfide shuttling and thus improves capacity retentionmore » of sulfur cathodes. Second, thanks to the low viscosity and good wettability, the fluorinated electrolyte dramatically enhances the reaction kinetics and sulfur utilization of high-areal-loading sulfur cathodes. More importantly, this electrolyte forms a stable solid-electrolyte interphase (SEI) layer on graphite surface and thus enables remarkable cyclability of graphite anodes. Lastly, by coupling prelithiated graphite anodes with sulfur cathodes with high areal capacity of ~3 mAh cm -2, we demonstrate prelithiated graphite/sulfur batteries that show high sulfur-specific capacity of ~1000 mAh g -1 and an excellent capacity retention of >65% after 450 cycles at C/10.« less

A stable lithiated silicon-chalcogen battery via synergetic chemical coupling between silicon and selenium.

PubMed

Eom, KwangSup; Lee, Jung Tae; Oschatz, Martin; Wu, Feixiang; Kaskel, Stefan; Yushin, Gleb; Fuller, Thomas F

2017-01-05

Li-ion batteries dominate portable energy storage due to their exceptional power and energy characteristics. Yet, various consumer devices and electric vehicles demand higher specific energy and power with longer cycle life. Here we report a full-cell battery that contains a lithiated Si/graphene anode paired with a selenium disulfide (SeS 2 ) cathode with high capacity and long-term stability. Selenium, which dissolves from the SeS 2 cathode, was found to become a component of the anode solid electrolyte interphase (SEI), leading to a significant increase of the SEI conductivity and stability. Moreover, the replacement of lithium metal anode impedes unwanted side reactions between the dissolved intermediate products from the SeS 2 cathode and lithium metal and eliminates lithium dendrite formation. As a result, the capacity retention of the lithiated silicon/graphene-SeS 2 full cell is 81% after 1,500 cycles at 268 mA g SeS2 -1 . The achieved cathode capacity is 403 mAh g SeS2 -1 (1,209 mAh cm SeS2 -3 ).

Recent Progress in Synthesis and Application of Low-Dimensional Silicon Based Anode Material for Lithium Ion Battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yuandong; Liu, Kewei; Zhu, Yu

Silicon is regarded as the next generation anode material for LIBs with its ultra-high theoretical capacity and abundance. Nevertheless, the severe capacity degradation resulting from the huge volume change and accumulative solid-electrolyte interphase (SEI) formation hinders the silicon based anode material for further practical applications. Hence, a variety of methods have been applied to enhance electrochemical performances in terms of the electrochemical stability and rate performance of the silicon anodes such as designing nanostructured Si, combining with carbonaceous material, exploring multifunctional polymer binders, and developing artificial SEI layers. Silicon anodes with low-dimensional structures (0D, 1D, and 2D), compared with bulkymore » silicon anodes, are strongly believed to have several advanced characteristics including larger surface area, fast electron transfer, and shortened lithium diffusion pathway as well as better accommodation with volume changes, which leads to improved electrochemical behaviors. Finally, in this review, recent progress of silicon anode synthesis methodologies generating low-dimensional structures for lithium ion batteries (LIBs) applications is listed and discussed.« less

Recent Progress in Synthesis and Application of Low-Dimensional Silicon Based Anode Material for Lithium Ion Battery

DOE PAGES

Sun, Yuandong; Liu, Kewei; Zhu, Yu

2017-07-31

Silicon is regarded as the next generation anode material for LIBs with its ultra-high theoretical capacity and abundance. Nevertheless, the severe capacity degradation resulting from the huge volume change and accumulative solid-electrolyte interphase (SEI) formation hinders the silicon based anode material for further practical applications. Hence, a variety of methods have been applied to enhance electrochemical performances in terms of the electrochemical stability and rate performance of the silicon anodes such as designing nanostructured Si, combining with carbonaceous material, exploring multifunctional polymer binders, and developing artificial SEI layers. Silicon anodes with low-dimensional structures (0D, 1D, and 2D), compared with bulkymore » silicon anodes, are strongly believed to have several advanced characteristics including larger surface area, fast electron transfer, and shortened lithium diffusion pathway as well as better accommodation with volume changes, which leads to improved electrochemical behaviors. Finally, in this review, recent progress of silicon anode synthesis methodologies generating low-dimensional structures for lithium ion batteries (LIBs) applications is listed and discussed.« less

Influence of EDTA in poly(acrylic acid) binder for enhancing electrochemical performance and thermal stability of silicon anode

NASA Astrophysics Data System (ADS)

Lee, Sun-Young; Choi, Yunju; Hong, Kyong-Soo; Lee, Jung Kyoo; Kim, Ju-Young; Bae, Jong-Seong; Jeong, Euh Duck

2018-07-01

The crucial roles of ethylenediaminetetraacetic acid (EDTA) in the poly(acrylic acid) (PAA)-binder system were investigated for the high electrochemical performance silicon anode in lithium-ion batteries. The EDTA supports the construction of a mechanically robust network through the formation of sbndCOOH linkage with the SiO2 layer of the Si nanoparticles. The mixture of the PAA/EDTA binder and the conductive agent exhibited an improved elastic modulus and peeling strength. The creation of hydrogen fluoride (HF) was effectively suppressed through the elimination of the H2O. An H2O-phosphorous pentafluoride (PF5) reaction, which is known for its use in the etching of metal oxides including its creation of the solid electrolyte interphase (SEI) layer, generates the HF. A remarkably sound cyclability with a discharge capacity of 2540 mA h g-1 was achieved as a result of the synergistic effect between robust mechanical properties and suppression of the HF creation for the stability of the SEI layer.

Low temperature sulfur and sodium metal battery for grid-scale energy storage application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Gao; Wang, Dongdong

A re-chargeable battery comprising a non-dendrite forming sodium (Na)/potassium (K) liquid metal alloy anode, a sulfur and polyacrylonitrile (PAN) conductive polymer composite cathode, a polyethyleneoxide (PEO) solid electrolyte, a solid electrolyte interface (SEI) formed on the PEO solid electrolyte; and a cell housing, wherein the anode, cathode, and electrolyte are assembled into the cell housing with the PEO solid electrolyte disposed between the cathode and anode.

Mussel-Inspired Polydopamine Coating for Enhanced Thermal Stability and Rate Performance of Graphite Anodes in Li-Ion Batteries.

PubMed

Park, Seong-Hyo; Kim, Hyeon Jin; Lee, Junmin; Jeong, You Kyeong; Choi, Jang Wook; Lee, Hochun

2016-06-08

Despite two decades of commercial history, it remains very difficult to simultaneously achieve both high rate capability and thermal stability in the graphite anodes of Li-ion batteries because the stable solid electrolyte interphase (SEI) layer, which is essential for thermal stability, impedes facile Li(+) ion transport at the interface. Here, we resolve this longstanding challenge using a mussel-inspired polydopamine (PD) coating via a simple immersion process. The nanometer-thick PD coating layer allows the formation of an SEI layer on the coating surface without perturbing the intrinsic properties of the SEI layer of the graphite anodes. PD-coated graphite exhibits far better performances in cycling test at 60 °C and storage test at 90 °C than bare graphite. The PD-coated graphite also displays superior rate capability during both lithiation and delithiation. As evidenced by surface free energy analysis, the enhanced performance of the PD-coated graphite can be ascribed to the Lewis basicity of the PD, which scavenges harmful hydrofluoric acid and forms an intermediate triple-body complex among a Li(+) ion, solvent molecules, and the PD's basic site. The usefulness of the proposed PD coating can be expanded to various electrodes in rechargeable batteries that suffer from poor thermal stability and interfacial kinetics.

Wide Operating Temperature Range Electrolytes for High Voltage and High Specific Energy Li-Ion Cells

NASA Technical Reports Server (NTRS)

Smart, M. C.; Hwang, C.; Krause, F. C.; Soler, J.; West, W. C.; Ratnakumar, B. V.; Amine, K.

2012-01-01

A number of electrolyte formulations that have been designed to operate over a wide temperature range have been investigated in conjunction with layered-layered metal oxide cathode materials developed at Argonne. In this study, we have evaluated a number of electrolytes in Li-ion cells consisting of Conoco Phillips A12 graphite anodes and Toda HE5050 Li(1.2)Ni(0.15)Co(0.10)Mn(0.55)O2 cathodes. The electrolytes studied consisted of LiPF6 in carbonate-based electrolytes that contain ester co-solvents with various solid electrolyte interphase (SEI) promoting additives, many of which have been demonstrated to perform well in 4V systems. More specifically, we have investigated the performance of a number of methyl butyrate (MB) containing electrolytes (i.e., LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + MB (20:20:60 v/v %) that contain various additives, including vinylene carbonate, lithium oxalate, and lithium bis(oxalato)borate (LiBOB). When these systems were evaluated at various rates at low temperatures, the methyl butyrate-based electrolytes resulted in improved rate capability compared to cells with all carbonate-based formulations. It was also ascertained that the slow cathode kinetics govern the generally poor rate capability at low temperature in contrast to traditionally used LiNi(0.80)Co(0.15)Al(0.05)O2-based systems, rather than being influenced strongly by the electrolyte type.

Formation of Reversible Solid Electrolyte Interface on Graphite Surface from Concentrated Electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Dongping; Tao, Jinhui; Yan, Pengfei

2017-02-10

Interfacial phenomena have always been key determinants for the performance of energy storage technologies. The solid electrolyte interfacial (SEI) layer, pervasive on the surfaces of battery electrodes for numerous chemical couples, directly affects the ion transport, charge transfer and lifespan of the entire energy system. Almost all SEI layers, however, are unstable resulting in the continuous consumption of the electrolyte. Typically, this leads to the accumulation of degradation products on/restructuring of the electrode surface and thus increased cell impedance, which largely limits the long-term operation of the electrochemical reactions. Herein, a completely new SEI formation mechanism has been discovered, inmore » which the electrolyte components reversibly self-assemble into a protective surface coating on a graphite electrode upon changing the potential. In contrast to the established wisdom regarding the necessity of employing the solvent ethylene carbonate (EC) to form a protective SEI layer on graphite, a wide range of EC-free electrolytes are demonstrated for the reversible intercalation/deintercalation of Li+ cations within a graphite lattice, thereby providing tremendous flexibility in electrolyte tailoring for battery couples. This novel finding is broadly applicable and provides guidance for how to control interfacial reactions through the relationship between ion aggregation and solvent decomposition at polarized interfaces.« less

First-Principles Analysis of Defect Thermodynamics and Ion Transport in Inorganic SEI Compounds: LiF and NaF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yildirim, Handan; Kinaci, Alper; Chan, Maria K. Y.

The formation mechanism and composition of the solid electrolyte interphase (SEI) in lithium ion batteries has been widely explored. However, relatively little is known about the function of the SEI as a transport medium. Such critical information is directly relevant to battery rate performance, power loss, and capacity fading. To partially bridge this gap in the case of inorganic SEI compounds, we report herein the results of first-principles calculations on the defect thermodynamics, the dominant diffusion carriers, and the diffusion pathways associated with crystalline LiF and NaF, which are stable components of the SEI in Li-ion and Na-ion batteries, respectively.more » The thermodynamics of common point defects are computed, and the dominant diffusion carriers are determined over a voltage range of 0-4 V, corresponding to conditions relevant to both anode and cathode SEI's. Our analyses reveal that for both compounds, vacancy defects are energetically more favorable, therefore form more readily than interstitials, due to the close-packed nature of the crystal structures. However, the vacancy concentrations are very small for the diffusion processes facilitated by defects. Ionic conductivities are calculated as a function of voltage, considering the diffusion carrier concentration and the diffusion barriers as determined by nudged elastic band calculations. These conductivities are more than ten orders of magnitude smaller in NaF than in LiF. As compared to the diffusivity of Li in other common inorganic SEI compounds, such as Li2CO3 and Li2O,the cation diffusivity in LiF and NaF is quite low, with at least three orders of magnitude lower ionic conductivities. The results quantify the extent to which fluorides pose rate limitations in Li and Na batteries.« less

Fluorinated Phosphazene Co-solvents for Improved Thermal and Safety Performance in Lithium-Ion Battery Electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harry W. Rollins; Mason K. Harrup; Eric J. Dufek

2014-10-01

The safety of lithium-ion batteries is coming under increased scrutiny as they are being adopted for large format applications especially in the vehicle transportation industry and for grid-scale energy storage. The primary short-comings of lithium-ion batteries are the flammability of the liquid electrolyte and sensitivity to high voltage and elevated temperatures. We have synthesized a series of non-flammable fluorinated phosphazene liquids and blended them with conventional carbonate solvents. While the use of these phosphazenes as standalone electrolytes is highly desirable, they simply do not satisfy all of the many requirements that must be met such as high LiPF6 solubility andmore » low viscosity, thus we have used them as additives and co-solvents in blends with typical carbonates. The physical and electrochemical properties of the electrolyte blends were characterized, and then the blends were used to build 2032-type coin cells which were evaluated at constant current cycling rates from C/10 to C/1. We have evaluated the performance of the electrolytes by determining the conductivity, viscosity, flash point, vapor pressure, thermal stability, electrochemical window, cell cycling data, and the ability to form solid electrolyte interphase (SEI) films. This paper presents our results on a series of chemically similar fluorinated cyclic phosphazene trimers, the FM series, which has exhibited numerous beneficial effects on battery performance, lifetimes, and safety aspects.« less

Multifunctional interphase

NASA Astrophysics Data System (ADS)

Rosy, Noked, Malachi

2018-04-01

Realization of rechargeable batteries with alkali metal anodes is challenged by their high reactivity and dendritic growth. Now, an alloy-based, artificial solid electrolyte interphase is shown to allow smooth metal deposition, enhance interfacial charge transfer, protect against parasitic reactions and offer extra energy storage.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehdi, Beata L.; Qian, Jiangfeng; Nasybulin, Eduard

Lithium (Li)-ion batteries are currently used for a wide variety of portable electronic devices, electric vehicles and renewable energy applications. In addition, extensive worldwide research efforts are now being devoted to more advanced “beyond Li-ion” battery chemistries - such as lithium-sulfur (Li-S) and lithium-air (Li-O2) - in which the carbon anode is replaced with Li metal. However, the practical application of Li metal anode systems has been highly problematic. The main challenges involve controlling the formation of a solid-electrolyte interphase (SEI) layer and the suppression of Li dendrite growth during the charge/discharge process (achieving “dendrite-free” cycling). The SEI layer formationmore » continuously consumes the electrolyte components creating highly resistive layer, which leads to the rapid decrease of cycling performance and degradation of the Li anode. The growth of Li metal dendrites at the anode contributes to rapid capacity fading (the presence of “dead Li” created during the discharge leads to an increased overpotential) and, in the case of continuous growth, leads to internal short circuits and extreme safety issues. Here we demonstrate the application of an operando electrochemical scanning transmission electron microscopy (ec-(S)TEM) cell to study the SEI layer formation and the initial stages of Li dendrite growth - the goal is to develop a mechanism for mitigating the degradation processes and increasing safety. Bright field (BF) STEM images in Figure 1 A-C show Li metal deposition and dissolution processes at the interface between the Pt working electrode and the lithium hexafluorophosphate (LiPF6) in propylene carbonate (PC) electrolyte during three charge/discharge cycles. A contrast reversal caused by Li metal being lighter/less dense than surrounding electrolyte (Li appears brighter than the background in BF STEM images) allows Li to be uniquely identified from the other components in the system - the only solid material that is less dense than the electrolyte is Li metal. Using these images, we can precisely quantify the total volume of Li deposition, the thickness of the SEI layer (observed as a ring of positive contrast around the electrode) and alloy formation due to Li+ ion insertion during each cycle. Furthermore, at the end of each discharge cycle we can quantify the presence of “dead Li” detached from the Pt electrode, thereby demonstrating the degree of irreversibility (and degradation of Pt electrode) associated with insertion/removal of Li+during this process with direct correlation to electrochemical performance. Such analyses provide significant insights into Li metal dendrite growth, which is critical to understand the complex interfacial reactions needed to be controlled for future Li-based and next generation energy storage systems.« less

Tin anode for sodium-ion batteries using natural wood fiber as a mechanical buffer and electrolyte reservoir.

PubMed

Zhu, Hongli; Jia, Zheng; Chen, Yuchen; Weadock, Nicholas; Wan, Jiayu; Vaaland, Oeyvind; Han, Xiaogang; Li, Teng; Hu, Liangbing

2013-07-10

Sodium (Na)-ion batteries offer an attractive option for low cost grid scale storage due to the abundance of Na. Tin (Sn) is touted as a high capacity anode for Na-ion batteries with a high theoretical capacity of 847 mAh/g, but it has several limitations such as large volume expansion with cycling, slow kinetics, and unstable solid electrolyte interphase (SEI) formation. In this article, we demonstrate that an anode consisting of a Sn thin film deposited on a hierarchical wood fiber substrate simultaneously addresses all the challenges associated with Sn anodes. The soft nature of wood fibers effectively releases the mechanical stresses associated with the sodiation process, and the mesoporous structure functions as an electrolyte reservoir that allows for ion transport through the outer and inner surface of the fiber. These properties are confirmed experimentally and computationally. A stable cycling performance of 400 cycles with an initial capacity of 339 mAh/g is demonstrated; a significant improvement over other reported Sn nanostructures. The soft and mesoporous wood fiber substrate can be utilized as a new platform for low cost Na-ion batteries.

Engineering empty space between Si nanoparticles for lithium-ion battery anodes.

PubMed

Wu, Hui; Zheng, Guangyuan; Liu, Nian; Carney, Thomas J; Yang, Yuan; Cui, Yi

2012-02-08

Silicon is a promising high-capacity anode material for lithium-ion batteries yet attaining long cycle life remains a significant challenge due to pulverization of the silicon and unstable solid-electrolyte interphase (SEI) formation during the electrochemical cycles. Despite significant advances in nanostructured Si electrodes, challenges including short cycle life and scalability hinder its widespread implementation. To address these challenges, we engineered an empty space between Si nanoparticles by encapsulating them in hollow carbon tubes. The synthesis process used low-cost Si nanoparticles and electrospinning methods, both of which can be easily scaled. The empty space around the Si nanoparticles allowed the electrode to successfully overcome these problems Our anode demonstrated a high gravimetric capacity (~1000 mAh/g based on the total mass) and long cycle life (200 cycles with 90% capacity retention). © 2012 American Chemical Society

Non-aqueous electrolytes for electrochemical cells

DOEpatents

Zhang, Zhengcheng; Dong, Jian; Amine, Khalil

2016-06-14

An electrolyte electrochemical device includes an anodic material and an electrolyte, the electrolyte including an organosilicon solvent, a salt, and a hybrid additiving having a first and a second compound, the hybrid additive configured to form a solid electrolyte interphase film on the anodic material upon application of a potential to the electrochemical device.

Elucidating electrolyte decomposition under electron-rich environments at the lithium-metal anode.

PubMed

Camacho-Forero, Luis E; Balbuena, Perla B

2017-11-22

The lithium metal anode is one of the key components of the lithium-sulfur (Li-S) batteries, which are considered one of the most promising candidates for the next generation of battery systems. However, one of the main challenges that have prevented Li-metal anodes from becoming feasible to be used in commercial batteries is the continuous decomposition of the electrolyte due to its high reactivity, which leads to the formation of solid-electrolyte interphase (SEI) layers. The properties of the SEI can dramatically affect the performance of the batteries. Thus, a rigorous understanding of the electrolyte decomposition is crucial to elucidate improvements in performance of the Li-S technology. In this work, using density functional theory (DFT) and ab initio molecular dynamics simulations (AIMD), we investigate the effect of electron-rich environments on the decomposition mechanism of electrolyte species in pure 1,2-dimethoxyethane (DME) solvent and 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI) salt solutions. It is found that systems with pure DME require an average environment of at least ∼0.9 |e| per molecule for a DME to decompose into CH 3 O - and C 2 H 4 2- via a 4-electron transfer. In the case of mixtures, the salts are very prone to react with any excess of electrons. In addition, DME dehydrogenation due to reactions with fragments coming from the salt decompositions was detected. Formation of oligomer anionic species from DME and salt fragments were also identified from the AIMD simulations. Finally, the thermodynamics and kinetics of the most relevant electrolyte decomposition reactions were characterized. DME decomposition reactions predicted from the AIMD simulations were found to be thermodynamically favorable under exposure to Li atoms and/or by reactions with salt fragments. In most cases, these reactions were shown to have low to moderate activation barriers.

Role of additives in formation of solid-electrolyte interfaces on carbon electrodes and their effect on high-voltage stability.

PubMed

Qu, Weiguo; Dorjpalam, Enkhtuvshin; Rajagopalan, Ramakrishnan; Randall, Clive A

2014-04-01

The in situ modification of a lithium hexafluorophosphate-based electrolyte using a molybdenum oxide catalyst and small amount of water (1 vol %) yields hydrolysis products such as mono-, di-, and alkylfluorophosphates. The electrochemical stability of ultrahigh-purity, high-surface-area carbon electrodes derived from polyfurfuryl alcohol was tested using the modified electrolyte. Favorable modification of the solid electrolyte interface (SEI) layer on the activated carbon electrode increased the cyclable electrochemical voltage window (4.8-1.2 V vs. Li/Li(+)). The chemical modification of the SEI layer induced by electrolyte additives was characterized by using X-ray photoelectron spectroscopy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Degradation Mechanisms of Electrochemically Cycled Graphite Anodes in Lithium-ion Cells

NASA Astrophysics Data System (ADS)

Bhattacharya, Sandeep

This research is aimed at developing advanced characterization methods for studying the surface and subsurface damage in Li-ion battery anodes made of polycrystalline graphite and identifying the degradation mechanisms that cause loss of electrochemical capacity. Understanding microstructural aspects of the graphite electrode degradation mechanisms during charging and discharging of Li-ion batteries is of key importance in order to design durable anodes with high capacity. An in-situ system was constructed using an electrochemical cell with an observation window, a large depth-of-field digital microscope and a micro-Raman spectrometer. It was revealed that electrode damage by removal of the surface graphite fragments of 5-10 mum size is the most intense during the first cycle that led to a drastic capacity drop. Once a solid electrolyte interphase (SEI) layer covered the electrode surface, the rate of graphite particle loss decreased. Yet, a gradual loss of capacity continued by the formation of interlayer cracks adjacent to SEI/graphite interfaces. Deposition of co-intercalation compounds, LiC6, Li2CO3 and Li2O, near the crack tips caused partial closure of propagating graphite cracks during cycling and reduced the crack growth rate. Bridging of crack faces by delaminated graphite layers also retarded crack propagation. The microstructure of the SEI layer, formed by electrochemical reduction of the ethylene carbonate based electrolyte, consisted of ˜5-20 nm sized crystalline domains (containing Li2CO3, Li2O 2 and nano-sized graphite fragments) dispersed in an amorphous matrix. During the SEI formation, two regimes of Li-ion diffusion were identified at the electrode/electrolyte interface depending on the applied voltage scan rate (dV/dt). A low Li-ion diffusion coefficient ( DLi+) at dV/dt < 0.05 mVs-1 produced a tubular SEI that uniformly covered the graphite surface and prevented damage at 25°C. At 60°C, a high D Li+ formed a Li2CO3-enriched SEI and ensued a 28% increase in the battery capacity at 25°C. On correlating the microscopic information to the electrochemical performance, novel Li2CO3-coated electrodes were fabricated that were durable. The SEI formed on pre-treated electrodes reduced the strain in the graphite lattice from 0.4% (for uncoated electrodes) to 0.1%, facilitated Li-ion diffusion and hence improved the capacity retention of Li-ion batteries during long-term cycling.

Interfacial Chemistry Regulation via a Skin-Grafting Strategy Enables High-Performance Lithium-Metal Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Yue; Zhao, Yuming; Li, Yuguang C.

The lithium (Li) metal anode suffers severe interfacial instability from its high reactivity toward liquid electrolytes, especially carbonate-based electrolytes, resulting in poor electrochemical performance of batteries that use 4 V high-capacity cathodes. In this paper, we report a new skin-grafting strategy that stabilizes the Li metal–liquid electrolyte interface by coating the Li metal surface with poly((N-2,2-dimethyl-1,3-dioxolane-4-methyl)-5-norbornene-exo-2,3-dicarboximide), a chemically and electrochemically active polymer layer. This layer, composed of cyclic ether groups with a stiff polycyclic main chain, serves as a grafted polymer skin on the Li metal anode not only to incorporate ether-based polymeric components into the solid-electrolyte interphase (SEI) butmore » also to accommodate Li deposition/dissolution under the skin in a dendrite/moss-free manner. Consequently, a Li-metal battery employing a Li metal anode with the grafted skin paired with LiNi 0.5Co 0.2Mn 0.3O 2 cathode has a 90.0% capacity retention after 400 charge/discharge cycles and a capacity of 1.2 mAh/cm 2 in a carbonate-based electrolyte. Finally, this proof-of-concept study provides a new direction for regulating the interfacial chemistry of Li metal anodes and for enabling high-performance Li-metal batteries.« less

Interfacial Chemistry Regulation via a Skin-Grafting Strategy Enables High-Performance Lithium-Metal Batteries

DOE PAGES

Gao, Yue; Zhao, Yuming; Li, Yuguang C.; ...

2017-10-06

The lithium (Li) metal anode suffers severe interfacial instability from its high reactivity toward liquid electrolytes, especially carbonate-based electrolytes, resulting in poor electrochemical performance of batteries that use 4 V high-capacity cathodes. In this paper, we report a new skin-grafting strategy that stabilizes the Li metal–liquid electrolyte interface by coating the Li metal surface with poly((N-2,2-dimethyl-1,3-dioxolane-4-methyl)-5-norbornene-exo-2,3-dicarboximide), a chemically and electrochemically active polymer layer. This layer, composed of cyclic ether groups with a stiff polycyclic main chain, serves as a grafted polymer skin on the Li metal anode not only to incorporate ether-based polymeric components into the solid-electrolyte interphase (SEI) butmore » also to accommodate Li deposition/dissolution under the skin in a dendrite/moss-free manner. Consequently, a Li-metal battery employing a Li metal anode with the grafted skin paired with LiNi 0.5Co 0.2Mn 0.3O 2 cathode has a 90.0% capacity retention after 400 charge/discharge cycles and a capacity of 1.2 mAh/cm 2 in a carbonate-based electrolyte. Finally, this proof-of-concept study provides a new direction for regulating the interfacial chemistry of Li metal anodes and for enabling high-performance Li-metal batteries.« less

Decomposition of Imidazolium-Based Ionic Liquids in Contact with Lithium Metal.

PubMed

Schmitz, Paulo; Jakelski, Rene; Pyschik, Marcelina; Jalkanen, Kirsi; Nowak, Sascha; Winter, Martin; Bieker, Peter

2017-03-09

Ionic liquids (ILs) are considered to be suitable electrolyte components for lithium-metal batteries. Imidazolium cation based ILs were previously found to be applicable for battery systems with a lithium-metal negative electrode. However, herein it is shown that, in contrast to the well-known IL N-butyl-N-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide ([Pyr 14 ][TFSI]), 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C2MIm][TFSI]) and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C4MIm][TFSI]) are chemically unstable versus metallic lithium. A lithium-metal sheet was immersed in pure imidazolium-based IL samples and aged at 60 °C for 28 days. Afterwards, the aged IL samples were investigated to deduce possible decomposition products of the imidazolium cation. The chemical instability of the ILs in contact with lithium metal and a possible decomposition starting point are shown for the first time. Furthermore, the investigated imidazolium-based ILs can be utilized for lithium-metal batteries through the addition of the solid-electrolyte interphase (SEI) film-forming additive fluoroethylene carbonate. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

New insights into pre-lithiation kinetics of graphite anodes via nuclear magnetic resonance spectroscopy

NASA Astrophysics Data System (ADS)

Holtstiege, Florian; Schmuch, Richard; Winter, Martin; Brunklaus, Gunther; Placke, Tobias

2018-02-01

Pre-lithiation of anode materials can be an effective method to compensate active lithium loss which mainly occurs in the first few cycles of a lithium ion battery (LIB), due to electrolyte decomposition and solid electrolyte interphase (SEI) formation at the surface of the anode. There are many different pre-lithiation methods, whereas pre-lithiation using metallic lithium constitutes the most convenient and widely utilized lab procedure in literature. In this work, for the first time, solid state nuclear magnetic resonance spectroscopy (NMR) is applied to monitor the reaction kinetics of the pre-lithiation process of graphite with lithium. Based on static 7Li NMR, we can directly observe both the dissolution of lithium metal and parallel formation of LiCx species in the obtained NMR spectra with time. It is also shown that the degree of pre-lithiation as well as distribution of lithium metal on the electrode surface have a strong impact on the reaction kinetics of the pre-lithiation process and on the remaining amount of lithium metal. Overall, our findings are highly important for further optimization of pre-lithiation methods for LIB anode materials, both in terms of optimized pre-lithiation time and appropriate amounts of lithium metal.

In situ analytical techniques for battery interface analysis.

PubMed

Tripathi, Alok M; Su, Wei-Nien; Hwang, Bing Joe

2018-02-05

Lithium-ion batteries, simply known as lithium batteries, are distinct among high energy density charge-storage devices. The power delivery of batteries depends upon the electrochemical performances and the stability of the electrode, electrolytes and their interface. Interfacial phenomena of the electrode/electrolyte involve lithium dendrite formation, electrolyte degradation and gas evolution, and a semi-solid protective layer formation at the electrode-electrolyte interface, also known as the solid-electrolyte interface (SEI). The SEI protects electrodes from further exfoliation or corrosion and suppresses lithium dendrite formation, which are crucial needs for enhancing the cell performance. This review covers the compositional, structural and morphological aspects of SEI, both artificially and naturally formed, and metallic dendrites using in situ/in operando cells and various in situ analytical tools. Critical challenges and the historical legacy in the development of in situ/in operando electrochemical cells with some reports on state-of-the-art progress are particularly highlighted. The present compilation pinpoints the emerging research opportunities in advancing this field and concludes on the future directions and strategies for in situ/in operando analysis.

Degradation of lithium ion batteries employing graphite negatives and nickel-cobalt-manganese oxide + spinel manganese oxide positives: Part 2, chemical-mechanical degradation model

NASA Astrophysics Data System (ADS)

Purewal, Justin; Wang, John; Graetz, Jason; Soukiazian, Souren; Tataria, Harshad; Verbrugge, Mark W.

2014-12-01

Capacity fade is reported for 1.5 Ah Li-ion batteries containing a mixture of Li-Ni-Co-Mn oxide (NCM) + Li-Mn oxide spinel (LMO) as positive electrode material and a graphite negative electrode. The batteries were cycled at a wide range of temperatures (10 °C-46 °C) and discharge currents (0.5C-6.5C). The measured capacity losses were fit to a simple physics-based model which calculates lithium inventory loss from two related mechanisms: (1) mechanical degradation at the graphite anode particle surface caused by diffusion-induced stresses (DIS) and (2) chemical degradation caused by lithium loss to continued growth of the solid-electrolyte interphase (SEI). These two mechanisms are coupled because lithium is consumed through SEI formation on newly exposed crack surfaces. The growth of crack surface area is modeled as a fatigue phenomenon due to the cyclic stresses generated by repeated lithium insertion and de-insertion of graphite particles. This coupled chemical-mechanical degradation model is consistent with the observed capacity loss features for the NCM + LMO/graphite cells.

A stable lithiated silicon–chalcogen battery via synergetic chemical coupling between silicon and selenium

PubMed Central

Eom, KwangSup; Lee, Jung Tae; Oschatz, Martin; Wu, Feixiang; Kaskel, Stefan; Yushin, Gleb; Fuller, Thomas F.

2017-01-01

Li-ion batteries dominate portable energy storage due to their exceptional power and energy characteristics. Yet, various consumer devices and electric vehicles demand higher specific energy and power with longer cycle life. Here we report a full-cell battery that contains a lithiated Si/graphene anode paired with a selenium disulfide (SeS2) cathode with high capacity and long-term stability. Selenium, which dissolves from the SeS2 cathode, was found to become a component of the anode solid electrolyte interphase (SEI), leading to a significant increase of the SEI conductivity and stability. Moreover, the replacement of lithium metal anode impedes unwanted side reactions between the dissolved intermediate products from the SeS2 cathode and lithium metal and eliminates lithium dendrite formation. As a result, the capacity retention of the lithiated silicon/graphene—SeS2 full cell is 81% after 1,500 cycles at 268 mA gSeS2−1. The achieved cathode capacity is 403 mAh gSeS2−1 (1,209 mAh cmSeS2−3). PMID:28054543

Structure formation and surface chemistry of ionic liquids on model electrode surfaces—Model studies for the electrode | electrolyte interface in Li-ion batteries

NASA Astrophysics Data System (ADS)

Buchner, Florian; Uhl, Benedikt; Forster-Tonigold, Katrin; Bansmann, Joachim; Groß, Axel; Behm, R. Jürgen

2018-05-01

Ionic liquids (ILs) are considered as attractive electrolyte solvents in modern battery concepts such as Li-ion batteries. Here we present a comprehensive review of the results of previous model studies on the interaction of the battery relevant IL 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMP]+[TFSI]-) with a series of structurally and chemically well-defined model electrode surfaces, which are increasingly complex and relevant for battery applications [Ag(111), Au(111), Cu(111), pristine and lithiated highly oriented pyrolytic graphite (HOPG), and rutile TiO2(110)]. Combining surface science techniques such as high resolution scanning tunneling microscopy and X-ray photoelectron spectroscopy for characterizing surface structure and chemical composition in deposited (sub-)monolayer adlayers with dispersion corrected density functional theory based calculations, this work aims at a molecular scale understanding of the fundamental processes at the electrode | electrolyte interface, which are crucial for the development of the so-called solid electrolyte interphase (SEI) layer in batteries. Performed under idealized conditions, in an ultrahigh vacuum environment, these model studies provide detailed insights on the structure formation in the adlayer, the substrate-adsorbate and adsorbate-adsorbate interactions responsible for this, and the tendency for chemically induced decomposition of the IL. To mimic the situation in an electrolyte, we also investigated the interaction of adsorbed IL (sub-)monolayers with coadsorbed lithium. Even at 80 K, postdeposited Li is found to react with the IL, leading to decomposition products such as LiF, Li3N, Li2S, LixSOy, and Li2O. In the absence of a [BMP]+[TFSI]- adlayer, it tends to adsorb, dissolve, or intercalate into the substrate (metals, HOPG) or to react with the substrate (TiO2) above a critical temperature, forming LiOx and Ti3+ species in the latter case. Finally, the formation of stable decomposition products was found to sensitively change the equilibrium between surface Li and Li+ intercalated in the bulk, leading to a deintercalation from lithiated HOPG in the presence of an adsorbed IL adlayer at >230 K. Overall, these results provide detailed insights into the surface chemistry at the solid | electrolyte interface and the initial stages of SEI formation at electrode surfaces in the absence of an applied potential, which is essential for the further improvement of future Li-ion batteries.

Facile synthesis of hollow Sn-Co@PMMA nanospheres as high performance anodes for lithium-ion batteries via galvanic replacement reaction and in situ polymerization

NASA Astrophysics Data System (ADS)

Yu, Xiaohui; Jiang, Anni; Yang, Hongyan; Meng, Haowen; Dou, Peng; Ma, Daqian; Xu, Xinhua

2015-08-01

Polymethyl methacrylate (PMMA)-coated hollow Sn-Co nanospheres (Sn-Co@PMMA) with superior electrochemical performance had been synthesized via a facile galvanic replacement method followed by an in situ emulsion polymerization route. The properties were investigated in detail and results show that the hollow Sn-Co nanospheres were evenly coated with PMMA. Benefiting from the protection of the PMMA layers, the hollow Sn-Co@PMMA nanocomposite is capable of retaining a high capacity of 590 mAh g-1 after 100 cycles with a coulomb efficiency above 98%, revealing better electrochemical properties compared with hollow Sn-Co anodes. The PMMA coating could help accommodate the mechanical strain caused by volume expansion and stabilize the solid electrolyte interphase (SEI) film formed on the electrode. Such a facile process could be further extended to other anode materials for lithium-ion batteries.

High performance sandwich structured Si thin film anodes with LiPON coating

NASA Astrophysics Data System (ADS)

Luo, Xinyi; Lang, Jialiang; Lv, Shasha; Li, Zhengcao

2018-06-01

The sandwich structured silicon thin film anodes with lithium phosphorus oxynitride (LiPON) coating are synthesized via the radio frequency magnetron sputtering method, whereas the thicknesses of both layers are in the nanometer range, i.e. between 50 and 200 nm. In this sandwich structure, the separator simultaneously functions as a flexible substrate, while the LiPON layer is regarded as a protective layer. This sandwich structure combines the advantages of flexible substrate, which can help silicon release the compressive stress, and the LiPON coating, which can provide a stable artificial solid-electrolyte interphase (SEI) film on the electrode. As a result, the silicon anodes are protected well, and the cells exhibit high reversible capacity, excellent cycling stability and good rate capability. All the results demonstrate that this sandwich structure can be a promising option for high performance Si thin film lithium ion batteries.

Understanding and improving lithium ion batteries through mathematical modeling and experiments

NASA Astrophysics Data System (ADS)

Deshpande, Rutooj D.

There is an intense, worldwide effort to develop durable lithium ion batteries with high energy and power densities for a wide range of applications, including electric and hybrid electric vehicles. For improvement of battery technology understanding the capacity fading mechanism in batteries is of utmost importance. Novel electrode material and improved electrode designs are needed for high energy- high power batteries with less capacity fading. Furthermore, for applications such as automotive applications, precise cycle-life prediction of batteries is necessary. One of the critical challenges in advancing lithium ion battery technologies is fracture and decrepitation of the electrodes as a result of lithium diffusion during charging and discharging operations. When lithium is inserted in either the positive or negative electrode, there is a volume change associated with insertion or de-insertion. Diffusion-induced stresses (DISs) can therefore cause the nucleation and growth of cracks, leading to mechanical degradation of the batteries. With different mathematical models we studied the behavior of diffusion induces stresses and effects of electrode shape, size, concentration dependent material properties, pre-existing cracks, phase transformations, operating conditions etc. on the diffusion induced stresses. Thus we develop tools to guide the design of the electrode material with better mechanical stability for durable batteries. Along with mechanical degradation, chemical degradation of batteries also plays an important role in deciding battery cycle life. The instability of commonly employed electrolytes results in solid electrolyte interphase (SEI) formation. Although SEI formation contributes to irreversible capacity loss, the SEI layer is necessary, as it passivates the electrode-electrolyte interface from further solvent decomposition. SEI layer and diffusion induced stresses are inter-dependent and affect each-other. We study coupled chemical-mechanical degradation of electrode materials to understand the capacity fading of the battery with cycling. With the understanding of chemical and mechanical degradation, we develop a simple phenomenological model to predict battery life. On the experimental part we come up with a novel concept of using liquid metal alloy as a self-healing battery electrode. We develop a method to prepare thin film liquid gallium electrode on a conductive substrate. This enabled us to perform a series of electrochemical and characterization experiments which certify that liquid electrode undergo liquid-solid-liquid transition and thus self-heals the cracks formed during de-insertion. Thus the mechanical degradation can be avoided. We also perform ab-initio calculations to understand the equilibrium potential of various lithium-gallium phases. KEYWORDS: Lithium ion batteries, diffusion induced stresses, self-healing electrode, coupled chemical and mechanical degradation, life-prediction model.

Ionic liquids as electrolytes for Li-ion batteries-An overview of electrochemical studies

NASA Astrophysics Data System (ADS)

Lewandowski, Andrzej; Świderska-Mocek, Agnieszka

The paper reviews properties of room temperature ionic liquids (RTILs) as electrolytes for lithium and lithium-ion batteries. It has been shown that the formation of the solid electrolyte interface (SEI) on the anode surface is critical to the correct operation of secondary lithium-ion batteries, including those working with ionic liquids as electrolytes. The SEI layer may be formed by electrochemical transformation of (i) a molecular additive, (ii) RTIL cations or (iii) RTIL anions. Such properties of RTIL electrolytes as viscosity, conductivity, vapour pressure and lithium-ion transport numbers are also discussed from the point of view of their influence on battery performance.

General method to predict voltage-dependent ionic conduction in a solid electrolyte coating on electrodes

NASA Astrophysics Data System (ADS)

Pan, Jie; Cheng, Yang-Tse; Qi, Yue

2015-04-01

Understanding the ionic conduction in solid electrolytes in contact with electrodes is vitally important to many applications, such as lithium ion batteries. The problem is complex because both the internal properties of the materials (e.g., electronic structure) and the characteristics of the externally contacting phases (e.g., voltage of the electrode) affect defect formation and transport. In this paper, we developed a method based on density functional theory to study the physics of defects in a solid electrolyte in equilibrium with an external environment. This method was then applied to predict the ionic conduction in lithium fluoride (LiF), in contact with different electrodes which serve as reservoirs with adjustable Li chemical potential (μLi) for defect formation. LiF was chosen because it is a major component in the solid electrolyte interphase (SEI) formed on lithium ion battery electrodes. Seventeen possible native defects with their relevant charge states in LiF were investigated to determine the dominant defect types on various electrodes. The diffusion barrier of dominant defects was calculated by the climbed nudged elastic band method. The ionic conductivity was then obtained from the concentration and mobility of defects using the Nernst-Einstein relationship. Three regions for defect formation were identified as a function of μLi: (1) intrinsic, (2) transitional, and (3) p -type region. In the intrinsic region (high μLi, typical for LiF on the negative electrode), the main defects are Schottky pairs and in the p -type region (low μLi, typical for LiF on the positive electrode) are Li ion vacancies. The ionic conductivity is calculated to be approximately 10-31Scm-1 when LiF is in contact with a negative electrode but it can increase to 10-12Scm-1 on a positive electrode. This insight suggests that divalent cation (e.g., Mg2+) doping is necessary to improve Li ion transport through the engineered LiF coating, especially for LiF on negative electrodes. Our results provide an understanding of the influence of the environment on defect formation and demonstrate a linkage between defect concentration in a solid electrolyte and the voltage of the electrode.

Lithium Dinitramide as an Additive in Lithium Power Cells

NASA Technical Reports Server (NTRS)

Gorkovenko, Alexander A.

2007-01-01

Lithium dinitramide, LiN(NO2)2 has shown promise as an additive to nonaqueous electrolytes in rechargeable and non-rechargeable lithium-ion-based electrochemical power cells. Such non-aqueous electrolytes consist of lithium salts dissolved in mixtures of organic ethers, esters, carbonates, or acetals. The benefits of adding lithium dinitramide (which is also a lithium salt) include lower irreversible loss of capacity on the first charge/discharge cycle, higher cycle life, lower self-discharge, greater flexibility in selection of electrolyte solvents, and greater charge capacity. The need for a suitable electrolyte additive arises as follows: The metallic lithium in the anode of a lithium-ion-based power cell is so highly reactive that in addition to the desired main electrochemical reaction, it engages in side reactions that cause formation of resistive films and dendrites, which degrade performance as quantified in terms of charge capacity, cycle life, shelf life, first-cycle irreversible capacity loss, specific power, and specific energy. The incidence of side reactions can be reduced through the formation of a solid-electrolyte interface (SEI) a thin film that prevents direct contact between the lithium anode material and the electrolyte. Ideally, an SEI should chemically protect the anode and the electrolyte from each other while exhibiting high conductivity for lithium ions and little or no conductivity for electrons. A suitable additive can act as an SEI promoter. Heretofore, most SEI promotion was thought to derive from organic molecules in electrolyte solutions. In contrast, lithium dinitramide is inorganic. Dinitramide compounds are known as oxidizers in rocket-fuel chemistry and until now, were not known as SEI promoters in battery chemistry. Although the exact reason for the improvement afforded by the addition of lithium dinitramide is not clear, it has been hypothesized that lithium dinitramide competes with other electrolyte constituents to react with lithium on the surface of the anode to form a beneficial SEI. Apparently, nitrides and oxides that result from reduction of lithium dinitramide on the anode produce a thin, robust SEI different from the SEIs formed from organic SEI promoters. The SEI formed from lithium dinitramide is more electronically insulating than is the film formed in the presence of an otherwise identical electrolyte that does not include lithium dinitramide. SEI promotion with lithium dinitramide is useful in batteries with metallic lithium and lithium alloy anodes.

Effect of Vinylene Carbonate and Fluoroethylene Carbonate on SEI Formation on Graphitic Anodes in Li-Ion Batteries

DOE PAGES

Nie, Mengyun; Demeaux, Julien; Young, Benjamin T.; ...

2015-07-23

Binder free (BF) graphite electrodes were utilized to investigate the effect of electrolyte additives fluoroethylene carbonate (FEC) and vinylene carbonate (VC) on the structure of the solid electrolyte interface (SEI). The structure of the SEI has been investigated via ex-situ surface analysis including X-ray Photoelectron spectroscopy (XPS), Hard XPS (HAXPES), Infrared spectroscopy (IR) and transmission electron microscopy (TEM). The components of the SEI have been further investigated via nuclear magnetic resonance (NMR) spectroscopy of D2O extractions. The SEI generated on the BF-graphite anode with a standard electrolyte (1.2 M LiPF6 in ethylene carbonate (EC) / ethyl methyl carbonate (EMC), 3/7more » (v/v)) is composed primarily of lithium alkyl carbonates (LAC) and LiF. Incorporation of VC (3% wt) results in the generation of a thinner SEI composed of Li2CO3, poly(VC), LAC, and LiF. Incorporation of VC inhibits the generation of LAC and LiF. Incorporation of FEC (3% wt) also results in the generation of a thinner SEI composed of Li2CO3, poly(FEC), LAC, and LiF. The concentration of poly(FEC) is lower than the concentration of poly(VC) and the generation of LAC is inhibited in the presence of FEC. The SEI appears to be a homogeneous film for all electrolytes investigated.« less

A Highly Reversible Room-Temperature Sodium Metal Anode

PubMed Central

2015-01-01

Owing to its low cost and high natural abundance, sodium metal is among the most promising anode materials for energy storage technologies beyond lithium ion batteries. However, room-temperature sodium metal anodes suffer from poor reversibility during long-term plating and stripping, mainly due to formation of nonuniform solid electrolyte interphase as well as dendritic growth of sodium metal. Herein we report for the first time that a simple liquid electrolyte, sodium hexafluorophosphate in glymes (mono-, di-, and tetraglyme), can enable highly reversible and nondendritic plating–stripping of sodium metal anodes at room temperature. High average Coulombic efficiencies of 99.9% were achieved over 300 plating–stripping cycles at 0.5 mA cm–2. The long-term reversibility was found to arise from the formation of a uniform, inorganic solid electrolyte interphase made of sodium oxide and sodium fluoride, which is highly impermeable to electrolyte solvent and conducive to nondendritic growth. As a proof of concept, we also demonstrate a room-temperature sodium–sulfur battery using this class of electrolytes, paving the way for the development of next-generation, sodium-based energy storage technologies. PMID:27163006

A Highly Reversible Room-Temperature Sodium Metal Anode.

PubMed

Seh, Zhi Wei; Sun, Jie; Sun, Yongming; Cui, Yi

2015-11-25

Owing to its low cost and high natural abundance, sodium metal is among the most promising anode materials for energy storage technologies beyond lithium ion batteries. However, room-temperature sodium metal anodes suffer from poor reversibility during long-term plating and stripping, mainly due to formation of nonuniform solid electrolyte interphase as well as dendritic growth of sodium metal. Herein we report for the first time that a simple liquid electrolyte, sodium hexafluorophosphate in glymes (mono-, di-, and tetraglyme), can enable highly reversible and nondendritic plating-stripping of sodium metal anodes at room temperature. High average Coulombic efficiencies of 99.9% were achieved over 300 plating-stripping cycles at 0.5 mA cm(-2). The long-term reversibility was found to arise from the formation of a uniform, inorganic solid electrolyte interphase made of sodium oxide and sodium fluoride, which is highly impermeable to electrolyte solvent and conducive to nondendritic growth. As a proof of concept, we also demonstrate a room-temperature sodium-sulfur battery using this class of electrolytes, paving the way for the development of next-generation, sodium-based energy storage technologies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seh, Zhi Wei; Sun, Jie; Sun, Yongming

Owing to its low cost and high natural abundance, sodium metal is among the most promising anode materials for energy storage technologies beyond lithium ion batteries. However, room-temperature sodium metal anodes suffer from poor reversibility during long-term plating and stripping, mainly due to formation of nonuniform solid electrolyte interphase as well as dendritic growth of sodium metal. Herein we report for the first time that a simple liquid electrolyte, sodium hexafluorophosphate in glymes (mono-, di-, and tetraglyme), can enable highly reversible and nondendritic plating–stripping of sodium metal anodes at room temperature. High average Coulombic efficiencies of 99.9% were achieved overmore » 300 plating–stripping cycles at 0.5 mA cm –2. In this study, the long-term reversibility was found to arise from the formation of a uniform, inorganic solid electrolyte interphase made of sodium oxide and sodium fluoride, which is highly impermeable to electrolyte solvent and conducive to nondendritic growth. As a proof of concept, we also demonstrate a room-temperature sodium–sulfur battery using this class of electrolytes, paving the way for the development of next-generation, sodium-based energy storage technologies.« less

AlF 3 Surface-Coated Li[Li 0.2 Ni 0.17 Co 0.07 Mn 0.56 ]O 2 Nanoparticles with Superior Electrochemical Performance for Lithium-Ion Batteries

DOE PAGES

Sun, Shuwei; Yin, Yanfeng; Wan, Ning; ...

2015-06-24

For Li-rich layered cathode materials considerable attention has been paid owing to their high capacity performance for Li-ion batteries (LIBs). In our work, layered Li-rich Li[Li 0.2Ni 0.17Co 0.07Mn 0.56]O 2 nanoparticles are surface-modified with AlF 3 through a facile chemical deposition method. The AlF 3 surface layers have little impact on the structure of the material and act as buffers to prevent the direct contact of the electrode with the electrolyte; thus, they enhance the electrochemical performance significantly. The 3 wt% AlF 3-coated Li-rich electrode exhibits the best cycling capability and has a considerably enhanced capacity retention of 83.1%more » after 50 cycles. Moreover, the rate performance and thermal stability of the 3 wt% AlF3-coated electrode are also clearly improved. Finally, surface analysis indicates that the AlF 3 coating layer can largely suppress the undesirable growth of solid electrolyte interphase (SEI) film and, therefore, stabilizes the structure upon cycling.« less

Facile Stabilization of the Sodium Metal Anode with Additives: Unexpected Key Role of Sodium Polysulfide and Adverse Effect of Sodium Nitrate.

PubMed

Wang, Huan; Wang, Chuanlong; Matios, Edward; Li, Weiyang

2018-06-25

Sodium metal is an attractive anode for next-generation energy storage systems owing to its high specific capacity, low cost, and high abundance. Nevertheless, uncontrolled Na dendrite growth caused by the formation of unstable solid electrolyte interphase (SEI) leads to poor cycling performance and severe safety concerns. Sodium polysulfide (Na 2 S 6 ) alone is revealed to serve as a positive additive or pre-passivation agent in ether electrolyte to improve the long-term stability and reversibility of the Na anode, while Na 2 S 6 -NaNO 3 as co-additive has an adverse effect, contrary to the prior findings in the lithium anode system. A superior cycling behavior of Na anode is first demonstrated at a current density up to 10 mA cm -2 and a capacity up to 5 mAh cm -2 over 100 cycles. As a proof of concept, a high-capacity Na-S battery was prepared by pre-passivating the Na anode with Na 2 S 6 . This study gives insights into understanding the differences between Li and Na systems. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Time resolved impedance spectroscopy analysis of lithium phosphorous oxynitride - LiPON layers under mechanical stress

NASA Astrophysics Data System (ADS)

Glenneberg, Jens; Bardenhagen, Ingo; Langer, Frederieke; Busse, Matthias; Kun, Robert

2017-08-01

In this paper we present investigations on the morphological and electrochemical changes of lithium phosphorous oxynitride (LiPON) under mechanically bent conditions. Therefore, two types of electrochemical cells with LiPON thin films were prepared by physical vapor deposition. First, symmetrical cells with two blocking electrodes (Cu/LiPON/Cu) were fabricated. Second, to simulate a more application-related scenario cells with one blocking and one non-blocking electrode (Cu/LiPON/Li/Cu) were analyzed. In order to investigate mechanical distortion induced transport property changes in LiPON layers the cells were deposited on a flexible polyimide substrate. Morphology of the as-prepared samples and deviations from the initial state after applying external stress by bending the cells over different radii were investigated by Focused Ion Beam- Scanning Electron Microscopy (FIB-SEM) cross-section and surface images. Mechanical stress induced changes in the impedance were evaluated by time-resolved electrochemical impedance spectroscopy (EIS). Due to the formation of a stable, ion-conducting solid electrolyte interphase (SEI), cells with lithium show decreased impedance values. Furthermore, applying mechanical stress to the cells results in a further reduction of the electrolyte resistance. These results are supported by finite element analysis (FEA) simulations.

The Application of Poly(3-hexylthiophene-2,5-diyl) as a Protective Coating for High Rate Cathode Materials

DOE PAGES

Lai, Chun-Han; Ashby, David S.; Lin, Terri C.; ...

2018-03-01

Poly (3-hexylthiophene-2,5-diyl) (P3HT), a conducting polymer studied extensively for its optoelectronic devices, offers a number of advantageous properties when used as a conductive binder for lithium-ion battery cathode materials. By mixing with carbon nanotubes (CNT), P3HTCNT serves as a surface coating for the cathode material LiNi 0.8Co 0.15Al 0.05O 2 (NCA). Oxidation of the P3HT enables high electronic and ionic conductivity to be achieved over the potential range where the NCA is electrochemically active. In addition to the conductivity benefits from electrochemical doping, the P3HT-CNT coating suppresses electrolyte breakdown, thus inhibiting growth of the solid electrolyte interphase (SEI) layer andmore » preventing intergranular cracking in the NCA particles. In conclusion, The use of the P3HT-CNT binder system leads to improved cycling for NCA at high power density with capacities of 80 mAh g -1 obtained after 1000 cycles at 16C, a value that is 4 times greater than what is achieved in the control electrode.« less

The Application of Poly(3-hexylthiophene-2,5-diyl) as a Protective Coating for High Rate Cathode Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, Chun-Han; Ashby, David S.; Lin, Terri C.

Poly (3-hexylthiophene-2,5-diyl) (P3HT), a conducting polymer studied extensively for its optoelectronic devices, offers a number of advantageous properties when used as a conductive binder for lithium-ion battery cathode materials. By mixing with carbon nanotubes (CNT), P3HTCNT serves as a surface coating for the cathode material LiNi 0.8Co 0.15Al 0.05O 2 (NCA). Oxidation of the P3HT enables high electronic and ionic conductivity to be achieved over the potential range where the NCA is electrochemically active. In addition to the conductivity benefits from electrochemical doping, the P3HT-CNT coating suppresses electrolyte breakdown, thus inhibiting growth of the solid electrolyte interphase (SEI) layer andmore » preventing intergranular cracking in the NCA particles. In conclusion, The use of the P3HT-CNT binder system leads to improved cycling for NCA at high power density with capacities of 80 mAh g -1 obtained after 1000 cycles at 16C, a value that is 4 times greater than what is achieved in the control electrode.« less

Planar Solid-Oxide Fuel Cell Research and Development

DTIC Science & Technology

2013-03-28

electrolyte membrane ( PEM ) fuel cells ", Applied Surface Sei., 227 (2004) 56-72. [10] Grujicic, M., and Chittajallu, K. M., "Optimization of the...cathode geometry in polymer electrolyte membrane ( PEM ) fuel cells ", Chem. Eng. Sei., 59 (2004) 5883-5895. 36 [11] Anderson, W.K., Newman, J.C., Whitfield...M., Djilali, N, Suleman, A., "Optimization of a planar self-breathing PEM fuel cell cathode", AIAA 2006-6917, 11th AIAA/ISSMO Multidisciplinary

Designing solid-liquid interphases for sodium batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhury, Snehashis; Wei, Shuya; Ozhabes, Yalcin

Secondary batteries based on earth-abundant sodium metal anodes are desirable for both stationary and portable electrical energy storage. Room-temperature sodium metal batteries are impractical today because morphological instability during recharge drives rough, dendritic electrodeposition. Chemical instability of liquid electrolytes also leads to premature cell failure as a result of parasitic reactions with the anode. Here we use joint density-functional theoretical analysis to show that the surface diffusion barrier for sodium ion transport is a sensitive function of the chemistry of solid–electrolyte interphase. In particular, we find that a sodium bromide interphase presents an exceptionally low energy barrier to ion transport,more » comparable to that of metallic magnesium. We evaluate this prediction by means of electrochemical measurements and direct visualization studies. These experiments reveal an approximately three-fold reduction in activation energy for ion transport at a sodium bromide interphase. Direct visualization of sodium electrodeposition confirms large improvements in stability of sodium deposition at sodium bromide-rich interphases.« less

Designing solid-liquid interphases for sodium batteries

DOE PAGES

Choudhury, Snehashis; Wei, Shuya; Ozhabes, Yalcin; ...

2017-10-12

Secondary batteries based on earth-abundant sodium metal anodes are desirable for both stationary and portable electrical energy storage. Room-temperature sodium metal batteries are impractical today because morphological instability during recharge drives rough, dendritic electrodeposition. Chemical instability of liquid electrolytes also leads to premature cell failure as a result of parasitic reactions with the anode. Here we use joint density-functional theoretical analysis to show that the surface diffusion barrier for sodium ion transport is a sensitive function of the chemistry of solid–electrolyte interphase. In particular, we find that a sodium bromide interphase presents an exceptionally low energy barrier to ion transport,more » comparable to that of metallic magnesium. We evaluate this prediction by means of electrochemical measurements and direct visualization studies. These experiments reveal an approximately three-fold reduction in activation energy for ion transport at a sodium bromide interphase. Direct visualization of sodium electrodeposition confirms large improvements in stability of sodium deposition at sodium bromide-rich interphases.« less

Fundamental Investigation of Silicon Anode in Lithium-Ion Cells

NASA Technical Reports Server (NTRS)

Wu, James J.; Bennett, William R.

2012-01-01

Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is 10 times of graphite and it is an abundant element on Earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. Understanding solid electrolyte interphase (SEI) formation along with the lithium ion insertion/de-insertion kinetics in silicon anodes will provide greater insight into overcoming these issues, thereby lead to better cycle performance. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of a Si anode during the first cycle; the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes, and the combination of cyclic voltammetry with impedance spectroscopy provides a useful tool to evaluate the effectiveness of the design modifications on the Si anode performance.

Fast-pulverization enabled simultaneous enhancement on cycling stability and rate capability of C@NiFe2O4 hierarchical fibrous bundle

NASA Astrophysics Data System (ADS)

Chen, Zerui; Zhang, Yu; Wang, Xiaoling; Sun, Wenping; Dou, Shixue; Huang, Xin; Shi, Bi

2017-09-01

Electrochemical-grinding induced pulverization is the origin of capacity fading in NiFe2O4. Increasing current density normally accelerates the pulverization that deteriorates lithium storage properties of NiFe2O4. Here we show that the high current induced fast-pulverization can serve as an efficient activation strategy for quick and simultaneous enhancement on cycling stability and rate capability of NiFe2O4 nanoparticles (NPs) that are densely packed on the hierarchically structured carbon nanofiber strand. At a high current density, the pulverization of NiFe2O4 NPs can be accomplished in a few cycles exposing more active surface. During the fast-pulverization, the hierarchically structured carbon nanofiber strand maintains conductive contact for the densely packed NiFe2O4 NPs regardless of charge or discharge, which also effectively suppresses the repetitive breaks and growths of solid-electrolyte-interphase (SEI) via multiple-level structural adaption that favourites the quick formation of a thin and dense SEI, thus providing strong interparticle connectivity with enhancement on cycling stability and rate capability (e.g. doubled capacity). Our findings demonstrate the potential importance of high current induced fast-pulverization as an efficient activation strategy for achieving durable electrode materials suffering from electrochemical-grinding effects.

Electrochemical investigations of ionic liquids with vinylene carbonate for applications in rechargeable lithium ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Xiao-Guang; Dai, Sheng

2010-01-01

Ionic liquids based on methylpropylpyrrolidinium (MPPY) and methylpropylpiperidinium (MPPI) cations and bis(trifluoromethanesulfionyl)imide (TFSI) anion have been synthesized and characterized by thermal analysis, cyclic voltammetry, impedance spectroscopy as well as gavanostatic charge/discharge tests. 10 wt% of vinylene carbonate (VC) was added to the electrolytes of 0.5 M LiTFSI/MPPY.TFSI and 0.5 M LiTFSI/MPPI.TFSI, which were evaluated in Li || natural graphite (NG) half cells at 25 oC and 50 oC under different current densities. At 25 oC, due to their intrinsic high viscosities, the charge/discharge capacities under the current density of 80 A cm-2 were much lower than those under the currentmore » density of 40 A cm-2. At 50 oC, with reduced viscosities, the charge/discharge capacities under both current densities were almost indistinguishable, which were also close to the typical values obtained using conventional carbonate electrolytes. In addition, the discharge capacities of the half cells were very stable with cycling, due to the effective formation of solid electrolyte interphase (SEI) on the graphite electrode. On the contrary, the charge/discharge capacities of the Li || LiCoO2 cells using both ionic liquid electrolytes under the current density of 40 A cm-2 decreased continually with cycling, which were primarily due to the low oxidative stability of VC on the surface of LiCoO2.« less

Perfluoroalkyl-substituted ethylene carbonates: Novel electrolyte additives for high-voltage lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhu, Ye; Casselman, Matthew D.; Li, Yan; Wei, Alexander; Abraham, Daniel P.

2014-01-01

A new family of polyfluoroalkyl-substituted ethylene carbonates is synthesized and tested as additives in lithium-ion cells containing EC:EMC + LiPF6-based electrolyte. The influence of these compounds is investigated in Li1.2Ni0.15Mn0.55Co0.1O2//graphite cells via a combination of galvanostatic cycling and electrochemical impedance spectroscopy (EIS) tests. Among the four additives studied in this work (4-(trifluoromethyl)-1,3-dioxolan-2-one (TFM-EC), 4-(perfluorobutyl)-1,3-dioxolan-2-one (PFB-EC), 4-(perfluorohexyl)-1,3-dioxolan-2-one (PFH-EC), and 4-(perfluorooctyl)-1,3-dioxolan-2-one (PFO-EC)), small amounts (0.5 wt%) of PFO-EC is found to be most effective in lessening cell performance degradation during extended cycling. Linear sweep voltammetry (LSV), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy are used to further characterize the effects of PFO-EC on the positive and negative electrodes. LSV data from the electrolyte, and XPS analyses of electrodes harvested after cycling, suggest that PFO-EC is oxidized on the cathode forming surface films that slow electrode/cell impedance rise. Differential capacity (dQ/dV) plots from graphite//Li cells suggest that PFO-EC is involved in solid electrolyte interphase (SEI) formation. Raman data from anodes after cycling suggest that structural disordering of graphite is reduced by the addition of PFO-EC, which may explain the improved cell capacity retention.

Facile Fabrication of Ethoxy-Functional Polysiloxane Wrapped LiNi0.6Co0.2Mn0.2O2 Cathode with Improved Cycling Performance for Rechargeable Li-Ion Battery.

PubMed

Wang, Hao; Ge, Wujie; Li, Wen; Wang, Feng; Liu, Wenjing; Qu, Mei-Zhen; Peng, Gongchang

2016-07-20

Dealing with the water molecule on the surface of LiNi0.6Co0.2Mn0.2O2 (NCM) cathode and hydrogen fluoride in the electrolyte is one of the most difficult challenges in Li-ion battery research. In this paper, the surface polymerization of tetraethyl orthosilicate (TEOS) on NCM to generate ethoxy-functional polysiloxane (EPS) wrapped NCM (E-NCM) cathode under mild conditions and without any additions is utilized to solve this intractable problem. The differential scanning calorimetry, transmission electron microscopy, and X-ray photoelectron spectroscopy results show that the formed amorphous coating can provide a protective shell to improve the NCM thermal stability, suppress the thickening of the solid electrolyte interphase (SEI) layer, and scavenge HF in the electrolyte. The E-NCM composite with 2 mol % EPS delivers a high discharge capacity retention of 84.9% after 100 cycles at a 1 C discharge rate in the 2.8-4.3 V potential range at 55 °C. Moreover, electrochemical impedance spectroscopy measurements reveal that the EPS coating could alleviate the impedance rise during cycling especially at an elevated temperature. Therefore, the fabricated E-NCM cathode with long-term cycling and thermal stability is a promising candidate for use in a high-energy Li-ion battery.

Understanding of carbon-based supercapacitors ageing mechanisms by electrochemical and analytical methods

NASA Astrophysics Data System (ADS)

Liu, Yinghui; Soucaze-Guillous, Benoît; Taberna, Pierre-Louis; Simon, Patrice

2017-10-01

In order to shed light on ageing mechanisms of Electrochemical Double Layer Capacitor (EDLC), two kinds of activated carbons are studied in tetraethyl ammonium tetrafluoroborate (Et4NBF4) in acetonitrile. In floating mode, it turns out that two different ageing mechanisms are observed, depending on the activated carbon electrode materials used. On one hand, carbon A exhibits a continuous capacitance and series resistance fall-off; on the other hand, for carbon B, only the series resistance degrades after ageing while the capacitance keeps unchanged. Additional electrochemical characterizations (Electrochemical Impedance Spectroscopy - EIS - and diffusion coefficient calculations) were carried out showing that carbon A's ageing behavior is suspected to be primarily related to the carbon degradation while for carbon B a passivation occurs leading to the formation of a Solid Electrolyte Interphase-Like (SEI-L) film. These hypotheses are supported by TG-IR and Raman spectroscopy analysis. The outcome forms the latter is an increase of carbon defects on carbon A on positive electrode.

Hollow carbon nanospheres/silicon/alumina core-shell film as an anode for lithium-ion batteries

PubMed Central

Li, Bing; Yao, Fei; Bae, Jung Jun; Chang, Jian; Zamfir, Mihai Robert; Le, Duc Toan; Pham, Duy Tho; Yue, Hongyan; Lee, Young Hee

2015-01-01

Hollow carbon nanospheres/silicon/alumina (CNS/Si/Al2O3) core-shell films obtained by the deposition of Si and Al2O3 on hollow CNS interconnected films are used as the anode materials for lithium-ion batteries. The hollow CNS film acts as a three dimensional conductive substrate and provides void space for silicon volume expansion during electrochemical cycling. The Al2O3 thin layer is beneficial to the reduction of solid-electrolyte interphase (SEI) formation. Moreover, as-designed structure holds the robust surface-to-surface contact between Si and CNSs, which facilitates the fast electron transport. As a consequence, the electrode exhibits high specific capacity and remarkable capacity retention simultaneously: 1560 mA h g−1 after 100 cycles at a current density of 1 A g−1 with the capacity retention of 85% and an average decay rate of 0.16% per cycle. The superior battery properties are further confirmed by cyclic voltammetry (CV) and impedance measurement. PMID:25564245

Facile synthesis of tin dioxide-based high performance anodes for lithium ion batteries assisted by graphene gel

NASA Astrophysics Data System (ADS)

Wan, Yuanxin; Sha, Ye; Luo, Shaochuan; Deng, Weijia; Wang, Xiaoliang; Xue, Gi; Zhou, Dongshan

2015-11-01

Tin dioxide (SnO2) is an attractive material for anodes in energy storage devices, because it has four times the theoretical capacity of the prevalent anode material (graphite). The main obstacle hampers SnO2 from practical application is the pulverization problem caused by drastic volume change (∼300%) during lithium-ion insertion or extraction, which would lead to the loss of electrical conductivity, unstable solid-electrolyte interphase (SEI) formation and consequently severe capacity fading in the cycling. Here, we anchored the SnO2 nanocrystals into three dimensional graphene gel network to tackle this problem. As a result of the three dimensional (3-D) architecture, the huge volume change during cycling was tolerated by the large free space in this 3-D construction, resulting in a high capacity of 1090 mAh g-1 even after 200 cycles. What's more, at a higher current density 5 A g-1, a reversible capacity of about 491 mAh g-1 was achieved with this electrode.

Improved Battery Performance of Nanocrystalline Si Anodes Utilized by Radio Frequency (RF) Sputtered Multifunctional Amorphous Si Coating Layers.

PubMed

Ahn, In-Kyoung; Lee, Young-Joo; Na, Sekwon; Lee, So-Yeon; Nam, Dae-Hyun; Lee, Ji-Hoon; Joo, Young-Chang

2018-01-24

Despite the high theoretical specific capacity of Si, commercial Li-ion batteries (LIBs) based on Si are still not feasible because of unsatisfactory cycling stability. Herein, amorphous Si (a-Si)-coated nanocrystalline Si (nc-Si) formed by versatile radio frequency (RF) sputtering systems is proposed as a promising anode material for LIBs. Compared to uncoated nc-Si (retention of 0.6% and Coulombic efficiency (CE) of 79.7%), the a-Si-coated nc-Si (nc-Si@a-Si) anodes show greatly improved cycling retention (C 50th /C first ) of ∼50% and a first CE of 86.6%. From the ex situ investigation with electrochemical impedance spectroscopy (EIS) and cracked morphology during cycling, the a-Si layer was found to be highly effective at protecting the surface of the nc-Si from the formation of solid-state electrolyte interphases (SEI) and to dissipate the mechanical stress upon de/lithiation due to the high fracture toughness.

Gas swelling behaviour at different stages in Li4Ti5O12/LiNi1/3Co1/3Mn1/3O2 pouch cells

NASA Astrophysics Data System (ADS)

Liu, Wei; Liu, Haohan; Wang, Qian; Zhang, Jian; Xia, Baojia; Min, Guoquan

2017-11-01

Gas swelling behaviour is a major drawback of batteries that are based on Li4Ti5O12 anode materials and hinders their application. In this article, the morphology and electronic structure changes of Li4Ti5O12 electrodes at ageing and cycling stages are investigated using scanning electron microscopy, X-ray absorption near-edge structure and X-ray photoelectron spectroscopy. A simple method that uses an air bag to collect the generated gases was conducted and the gases were then characterised by gas chromatography/mass spectrometry. The results indicate that the charge transformation of Ti ions would aggravate the gas swelling behaviour. The solid electrolyte interphase (SEI) films form on the surface of the Li4Ti5O12 particles and become thicker with increasing charge state. The gas components change significantly during the ageing and cycling, indicating the complexity of the gas swelling mechanism.

A highly reversible room-temperature sodium metal anode

DOE PAGES

Seh, Zhi Wei; Sun, Jie; Sun, Yongming; ...

2015-11-02

Owing to its low cost and high natural abundance, sodium metal is among the most promising anode materials for energy storage technologies beyond lithium ion batteries. However, room-temperature sodium metal anodes suffer from poor reversibility during long-term plating and stripping, mainly due to formation of nonuniform solid electrolyte interphase as well as dendritic growth of sodium metal. Herein we report for the first time that a simple liquid electrolyte, sodium hexafluorophosphate in glymes (mono-, di-, and tetraglyme), can enable highly reversible and nondendritic plating–stripping of sodium metal anodes at room temperature. High average Coulombic efficiencies of 99.9% were achieved overmore » 300 plating–stripping cycles at 0.5 mA cm –2. In this study, the long-term reversibility was found to arise from the formation of a uniform, inorganic solid electrolyte interphase made of sodium oxide and sodium fluoride, which is highly impermeable to electrolyte solvent and conducive to nondendritic growth. As a proof of concept, we also demonstrate a room-temperature sodium–sulfur battery using this class of electrolytes, paving the way for the development of next-generation, sodium-based energy storage technologies.« less

Assessment of Simple Models for Molecular Simulation of Ethylene Carbonate and Propylene Carbonate as Solvents for Electrolyte Solutions.

PubMed

Chaudhari, Mangesh I; Muralidharan, Ajay; Pratt, Lawrence R; Rempe, Susan B

2018-02-12

Progress in understanding liquid ethylene carbonate (EC) and propylene carbonate (PC) on the basis of molecular simulation, emphasizing simple models of interatomic forces, is reviewed. Results on the bulk liquids are examined from the perspective of anticipated applications to materials for electrical energy storage devices. Preliminary results on electrochemical double-layer capacitors based on carbon nanotube forests and on model solid-electrolyte interphase (SEI) layers of lithium ion batteries are considered as examples. The basic results discussed suggest that an empirically parameterized, non-polarizable force field can reproduce experimental structural, thermodynamic, and dielectric properties of EC and PC liquids with acceptable accuracy. More sophisticated force fields might include molecular polarizability and Buckingham-model description of inter-atomic overlap repulsions as extensions to Lennard-Jones models of van der Waals interactions. Simple approaches should be similarly successful also for applications to organic molecular ions in EC/PC solutions, but the important case of Li[Formula: see text] deserves special attention because of the particularly strong interactions of that small ion with neighboring solvent molecules. To treat the Li[Formula: see text] ions in liquid EC/PC solutions, we identify interaction models defined by empirically scaled partial charges for ion-solvent interactions. The empirical adjustments use more basic inputs, electronic structure calculations and ab initio molecular dynamics simulations, and also experimental results on Li[Formula: see text] thermodynamics and transport in EC/PC solutions. Application of such models to the mechanism of Li[Formula: see text] transport in glassy SEI models emphasizes the advantage of long time-scale molecular dynamics studies of these non-equilibrium materials.

The limits of low-temperature performance of Li-ion cells

NASA Technical Reports Server (NTRS)

Huang, C.; Sakamoto, J.; Wolfenstine, J.; Surampudi, S.

2000-01-01

The results of electrode and electrolyte studies reveal that the poor low-temperature (<-30 degrees C) performance of Li-ion cells is mainly caused by the carbon electrodes and not the organic electrolytes and solid electrolyte interphase, as previously suggested. It is suggested that the main causes for the poor performance in the carbon electrodes are (i) the low value and concentration depedence of the Li diffusivity and (ii) limited Li capacity.

Electrolyte Chemistry for Simultaneous Stabilization of Potassium Metal and Superoxide in K-O₂ Batteries.

PubMed

Xiao, Neng; Gourdin, Gerald; Wu, Yiying

2018-05-22

In the superoxide batteries based on O2/O2- redox chemistry, identifying an electrolyte to stabilize both alkali metal and superoxide remains challenging due to their reactivity towards electrolyte components. Bis(fluorosulfonyl)imide (FSI-) has been recognized as a "magical anion" for passivating alkali metals. Herein, we illustrate the chemical reactions between FSI- and superoxide, and the resultant dilemma when considering an anode-compatible electrolyte vs. a cathode-compatible one in K-O2 batteries. On one side, the KFSI-dimethoxyethane (DME) electrolyte passivates the potassium metal anode via the cleavage of S-F bond and formation of a KF-rich solid electrolyte interface (SEI). Nevertheless, the KFSI salt is chemically unstable due to the nucleophilic attack by superoxide and/or hydroxide species. On the other hand, potassium bis(trifluorosulfonyl)imide (KTFSI) is stable for KO2, but results in mossy deposition and irreversible plating and stripping. In order to circumvent this dilemma, we develop an artificial SEI for K metal anode to achieve long cycle-life K-O2 batteries. This work contributes to the understanding of electrolyte chemistry and guides the development of stable electrolytes and artificial SEI in metal-O2 batteries. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mastering the interface for advanced all-solid-state lithium rechargeable batteries

PubMed Central

Li, Yutao; Zhou, Weidong; Chen, Xi; Lü, Xujie; Cui, Zhiming; Xin, Sen; Xue, Leigang; Jia, Quanxi; Goodenough, John B.

2016-01-01

A solid electrolyte with a high Li-ion conductivity and a small interfacial resistance against a Li metal anode is a key component in all-solid-state Li metal batteries, but there is no ceramic oxide electrolyte available for this application except the thin-film Li-P oxynitride electrolyte; ceramic electrolytes are either easily reduced by Li metal or penetrated by Li dendrites in a short time. Here, we introduce a solid electrolyte LiZr2(PO4)3 with rhombohedral structure at room temperature that has a bulk Li-ion conductivity σLi = 2 × 10−4 S⋅cm−1 at 25 °C, a high electrochemical stability up to 5.5 V versus Li+/Li, and a small interfacial resistance for Li+ transfer. It reacts with a metallic lithium anode to form a Li+-conducting passivation layer (solid-electrolyte interphase) containing Li3P and Li8ZrO6 that is wet by the lithium anode and also wets the LiZr2(PO4)3 electrolyte. An all-solid-state Li/LiFePO4 cell with a polymer catholyte shows good cyclability and a long cycle life. PMID:27821751

Liquid electrolytes for lithium and lithium-ion batteries

NASA Astrophysics Data System (ADS)

Blomgren, George E.

A number of advances in electrolytes have occurred in the past 4 years, which have contributed to increased safety, wider temperature range of operation, better cycling and other enhancements to lithium-ion batteries. The changes to basic electrolyte solutions that have occurred to accomplish these advances are discussed in detail. The solvent components that have led to better low-temperature operation are also considered. Also, additives that have resulted in better structure of the solid electrolyte interphase (SEI) are presented as well as proposed methods of operation of these additives. Other additives that have lessened the flammability of the electrolyte when exposed to air and also caused lowering of the heat of reaction with the oxidized positive electrode are discussed. Finally, additives that act to open current-interrupter devices by releasing a gas under overcharge conditions and those that act to cycle between electrodes to alleviate overcharging are presented. As a class, these new electrolytes are often called "functional electrolytes". Possibilities for further progress in this most important area are presented. Another area of active work in the recent past has been the reemergence of ambient-temperature molten salt electrolytes applied to alkali metal and lithium-ion batteries. This revival of an older field is due to the discovery of new salt types that have a higher voltage window (particularly to positive potentials) and also have greatly increased hydrolytic stability compared to previous ionic liquids. While practical batteries have not yet emerged from these studies, the increase in the number of active researchers and publications in the area demonstrates the interest and potentialities of the field. Progress in the field is briefly reviewed. Finally, recent results on the mechanisms for capacity loss on shelf and cycling in lithium-ion cells are reviewed. Progress towards further market penetration by lithium-ion cells hinges on improved understanding of the failure mechanisms of the cells, so that crucial problems can be addressed.

Electrocatalytic transformation of HF impurity to H 2 and LiF in lithium-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strmcnik, Dusan; Castelli, Ivano E.; Connell, Justin G.

The formation of solid electrolyte interphase on graphite anodes plays a key role in the efficiency of Li-ion batteries. However, to date, fundamental understanding of the formation of LiF as one of the main solid electrolyte interphase components in hexafluorophosphate-based electrolytes remains elusive. In this paper, we present experimental and theoretical evidence that LiF formation is an electrocatalytic process that is controlled by the electrochemical transformation of HF impurity to LiF and H 2. Although the kinetics of HF dissociation and the concomitant production of LiF and H 2 is dependent on the structure and nature of surface atoms, themore » underlying electrochemistry is the same. The morphology, and thus the role, of the LiF formed is strongly dependent on the nature of the substrate and HF inventory, leading to either complete or partial passivation of the interface. Finally, our finding is of general importance and may lead to new opportunities for the improvement of existing, and design of new, Li-ion technologies.« less

Electrocatalytic transformation of HF impurity to H 2 and LiF in lithium-ion batteries

DOE PAGES

Strmcnik, Dusan; Castelli, Ivano E.; Connell, Justin G.; ...

2018-04-09

The formation of solid electrolyte interphase on graphite anodes plays a key role in the efficiency of Li-ion batteries. However, to date, fundamental understanding of the formation of LiF as one of the main solid electrolyte interphase components in hexafluorophosphate-based electrolytes remains elusive. In this paper, we present experimental and theoretical evidence that LiF formation is an electrocatalytic process that is controlled by the electrochemical transformation of HF impurity to LiF and H 2. Although the kinetics of HF dissociation and the concomitant production of LiF and H 2 is dependent on the structure and nature of surface atoms, themore » underlying electrochemistry is the same. The morphology, and thus the role, of the LiF formed is strongly dependent on the nature of the substrate and HF inventory, leading to either complete or partial passivation of the interface. Finally, our finding is of general importance and may lead to new opportunities for the improvement of existing, and design of new, Li-ion technologies.« less

Interfacial Reactivity Benchmarking of the Sodium Ion Conductors Na3PS4 and Sodium β-Alumina for Protected Sodium Metal Anodes and Sodium All-Solid-State Batteries.

PubMed

Wenzel, Sebastian; Leichtweiss, Thomas; Weber, Dominik A; Sann, Joachim; Zeier, Wolfgang G; Janek, Jürgen

2016-10-05

The interfacial stability of solid electrolytes at the electrodes is crucial for an application of all-solid-state batteries and protected electrodes. For instance, undesired reactions between sodium metal electrodes and the solid electrolyte form charge transfer hindering interphases. Due to the resulting large interfacial resistance, the charge transfer kinetics are altered and the overvoltage increases, making the interfacial stability of electrolytes the limiting factor in these systems. Driven by the promising ionic conductivities of Na 3 PS 4 , here we explore the stability and viability of Na 3 PS 4 as a solid electrolyte against metallic Na and compare it to that of Na-β″-Al 2 O 3 (sodium β-alumina). As expected, Na-β″-Al 2 O 3 is stable against sodium, whereas Na 3 PS 4 decomposes with an increasing overall resistance, making Na-β″-Al 2 O 3 the electrolyte of choice for protected sodium anodes and all-solid-state batteries.

A study of perfluorocarboxylate ester solvents for lithium ion battery electrolytes

DOE PAGES

Fears, Tyler M.; Sacci, Robert L.; Winiarz, Jeffrey G.; ...

2015-09-18

We prepared several high-purity methyl perfluorocarboxylates (>99.5% purity by mole) and investigated as potential fluorine-rich electrolyte solvents in Li-ion batteries. The most conductive electrolyte, 0.1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in dimethyl perfluoroglutarate (PF5M 2) (ionic conductivity 1.87 10 -2 mS cm -1), is investigated in Si thin-film half-cells. The solid-electrolyteinterphase (SEI) formed by the PF5M2 electrolyte is composed of similar organic and inorganic moieties and at comparable concentrations as those formed by ethylene carbonate/dimethyl carbonate electrolytes containing LiPF 6 and LiTFSI salts. But, the SEI formed by the PF5M 2 electrolyte undergoes reversible electrochemical defluorination, contributing to the reversible capacitymore » of the cell and compensating in part for capacity fade in the Si electrode. These electrolytes, though far from ideal, provide an opportunity to further develop predictions of suitable fluorinated molecules for use in battery solvents.« less

First principles study on electrochemical and chemical stability of solid electrolyte–electrode interfaces in all-solid-state Li-ion batteries

DOE PAGES

Zhu, Yizhou; He, Xingfeng; Mo, Yifei

2015-12-11

All-solid-state Li-ion batteries based on ceramic solid electrolyte materials are a promising next-generation energy storage technology with high energy density and enhanced cycle life. The poor interfacial conductance is one of the key limitations in enabling all-solid-state Li-ion batteries. However, the origin of this poor conductance has not been understood, and there is limited knowledge about the solid electrolyte–electrode interfaces in all-solid-state Li-ion batteries. In this paper, we performed first principles calculations to evaluate the thermodynamics of the interfaces between solid electrolyte and electrode materials and to identify the chemical and electrochemical stabilities of these interfaces. Our computation results revealmore » that many solid electrolyte–electrode interfaces have limited chemical and electrochemical stability, and that the formation of interphase layers is thermodynamically favorable at these interfaces. These formed interphase layers with different properties significantly affect the electrochemical performance of all-solid-state Li-ion batteries. The mechanisms of applying interfacial coating layers to stabilize the interface and to reduce interfacial resistance are illustrated by our computation. This study demonstrates a computational scheme to evaluate the chemical and electrochemical stability of heterogeneous solid interfaces. Finally, the enhanced understanding of the interfacial phenomena provides the strategies of interface engineering to improve performances of all-solid-state Li-ion batteries.« less

Reduction mechanisms of additives on Si anodes of Li-ion batteries.

PubMed

Martínez de la Hoz, Julibeth M; Balbuena, Perla B

2014-08-28

Solid-electrolyte interphase (SEI) layers are films deposited on the surface of Li-ion battery electrodes during battery charge and discharge processes. They are due to electrochemical instability of the electrolyte which causes electron transfer from (to) the anode (cathode) surfaces. The films could have a protective passivating role and therefore understanding the detailed reduction (oxidation) processes is essential. Here density functional theory and ab initio molecular dynamics simulations are used to investigate the reduction mechanisms of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) on lithiated silicon surfaces. These species are frequently used as "additives" to improve the SEI properties. It is found that on lithiated Si anodes (with low to intermediate degrees of lithiation) VC may be reduced via a 2e(-) mechanism yielding an opened VC(2-) anion. At higher degrees of lithiation, such a species receives two extra electrons from the surface resulting in an adsorbed CO(2-)(ads) anion and a radical anion ˙OC2H2O(2-). Additionally, in agreement with experimental observations, it is shown that CO2 can be generated from reaction of VC with the CO3(2-)anion, a product of the reduction of the main solvent, ethylene carbonate (EC). On the other hand, FEC reduction on LixSiy surfaces is found to be independent of the degree of lithiation, and occurs through three mechanisms. One of them leads to an adsorbed VC(2-) anion upon release from the FEC molecule and adsorption on the surface of F(-) and one H atom. Thus in some cases, the reduction of FEC may lead to the exact same reduction products as that of VC, which explains similarities in SEI layers formed in the presence of these additives. However, FEC may be reduced via two other multi-electron transfer mechanisms that result in formation of either CO2(2-), F(-), and ˙CH2CHO(-) or CO(2-), F(-), and ˙OCH2CHO(-). These alternative reduction products may oligomerize and form SEI layers with different components than those formed in the presence of VC. In all cases, FEC reduction also leads to formation of LiF moieties on the anode surface, in agreement with reported experimental data. The crucial role of the surface in each of these mechanisms is thoroughly explained.

Exploiting Anti-T-shaped Graphene Architecture to Form Low Tortuosity, Sieve-like Interfaces for High-Performance Anodes for Li-Based Cells

PubMed Central

2017-01-01

Graphitic carbon anodes have long been used in Li ion batteries due to their combination of attractive properties, such as low cost, high gravimetric energy density, and good rate capability. However, one significant challenge is controlling, and optimizing, the nature and formation of the solid electrolyte interphase (SEI). Here it is demonstrated that carbon coating via chemical vapor deposition (CVD) facilitates high electrochemical performance of carbon anodes. We examine and characterize the substrate/vertical graphene interface (multilayer graphene nanowalls coated onto carbon paper via plasma enhanced CVD), revealing that these low-tortuosity and high-selection graphene nanowalls act as fast Li ion transport channels. Moreover, we determine that the hitherto neglected parallel layer acts as a protective surface at the interface, enhancing the anode performance. In summary, these findings not only clarify the synergistic role of the parallel functional interface when combined with vertical graphene nanowalls but also have facilitated the development of design principles for future high rate, high performance batteries. PMID:29392179

Bundled and densified carbon nanotubes (CNT) fabrics as flexible ultra-light weight Li-ion battery anode current collectors

NASA Astrophysics Data System (ADS)

Yehezkel, Shani; Auinat, Mahmud; Sezin, Nina; Starosvetsky, David; Ein-Eli, Yair

2016-04-01

Carbon nanotubes (CNT) fabrics were studied and evaluated as anode current collectors, replacing the traditional copper foil current collector in Li-ion batteries. Glavanostatic measurements reveal high values of irreversible capacities (as high as 28%), resulted mainly from the formation of the solid electrolyte interphase (SEI) layer at the CNT fabric surface. Various pre-treatments to the CNT fabric prior to active anode material loading have shown that the lowest irreversible capacity is achieved by immersing and washing the CNT fabric with iso-propanol (IPA), which dramatically modified the fabric surface. Additionally, the use of very thin CNT fabrics (5 μm) results in a substantial irreversible capacity minimization. A combination of IPA rinse action and utilization of the thinnest CNT fabric provides the lowest irreversible capacity of 13%. The paper describes innovative and rather simple techniques towards a complete implementation of CNT fabric as an anode current collector in Li-ion batteries, instead of the relatively heavy and expensive copper foil, enabling an improvement in the gravimetric and volumetric energy densities of such advanced batteries.

New promising lithium malonatoborate salts for high voltage lithium ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Xiao -Guang; Wan, Shun; Guang, Hong Yu

Here, three new lithium salts, lithium difluoro-2-methyl-2-fluoromalonaoborate (LiDFMFMB), lithium difluoro-2-ethyl-2-fluoromalonaoborate (LiDFEFMB), and lithium difluoro-2-propyl-2-fluoro malonaoborate (LiDFPFMB), have been synthesized and evaluated for application in lithium ion batteries. These new salts are soluble in a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (1:2 by wt.) and 1.0 M salt solutions can be easily prepared. The ionic conductivities of these new salts are close to those of LiBF 4 and LiPF 6. Cyclic voltammograms reveal that these new salt based electrolytes can passivate both natural graphite and high voltage spinel LiNi 0.5Mn 1.5O 4 (LNMO) to form effective solidmore » electrolyte interphases (SEIs). In addition, these new salts based electrolytes exhibit good cycling stability with high coulombic efficiencies in both LiNi 0.5Mn 1.5O 4 and graphite based half-cells and full cells.« less

New promising lithium malonatoborate salts for high voltage lithium ion batteries

DOE PAGES

Sun, Xiao -Guang; Wan, Shun; Guang, Hong Yu; ...

2016-12-01

Here, three new lithium salts, lithium difluoro-2-methyl-2-fluoromalonaoborate (LiDFMFMB), lithium difluoro-2-ethyl-2-fluoromalonaoborate (LiDFEFMB), and lithium difluoro-2-propyl-2-fluoro malonaoborate (LiDFPFMB), have been synthesized and evaluated for application in lithium ion batteries. These new salts are soluble in a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (1:2 by wt.) and 1.0 M salt solutions can be easily prepared. The ionic conductivities of these new salts are close to those of LiBF 4 and LiPF 6. Cyclic voltammograms reveal that these new salt based electrolytes can passivate both natural graphite and high voltage spinel LiNi 0.5Mn 1.5O 4 (LNMO) to form effective solidmore » electrolyte interphases (SEIs). In addition, these new salts based electrolytes exhibit good cycling stability with high coulombic efficiencies in both LiNi 0.5Mn 1.5O 4 and graphite based half-cells and full cells.« less

Equilibrium lithium-ion transport between nanocrystalline lithium-inserted anatase TiO2 and the electrolyte.

PubMed

Ganapathy, Swapna; van Eck, Ernst R H; Kentgens, Arno P M; Mulder, Fokko M; Wagemaker, Marnix

2011-12-23

The power density of lithium-ion batteries requires the fast transfer of ions between the electrode and electrolyte. The achievable power density is directly related to the spontaneous equilibrium exchange of charged lithium ions across the electrolyte/electrode interface. Direct and unique characterization of this charge-transfer process is very difficult if not impossible, and consequently little is known about the solid/liquid ion transfer in lithium-ion-battery materials. Herein we report the direct observation by solid-state NMR spectroscopy of continuous lithium-ion exchange between the promising nanosized anatase TiO(2) electrode material and the electrolyte. Our results reveal that the energy barrier to charge transfer across the electrode/electrolyte interface is equal to or greater than the barrier to lithium-ion diffusion through the solid anatase matrix. The composition of the electrolyte and in turn the solid/electrolyte interface (SEI) has a significant effect on the electrolyte/electrode lithium-ion exchange; this suggests potential improvements in the power of batteries by optimizing the electrolyte composition. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Depth profiling the solid electrolyte interphase on lithium titanate (Li4Ti5O12) using synchrotron-based photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Nordh, Tim; Younesi, Reza; Brandell, Daniel; Edström, Kristina

2015-10-01

The presence of a surface layer on lithium titanate (Li4Ti5O12, LTO) anodes, which has been a topic of debate in scientific literature, is here investigated with tunable high surface sensitive synchrotron-based photoelectron spectroscopy (PES) to obtain a reliable depth profile of the interphase. Li||LTO cells with electrolytes consisting of 1 M lithium hexafluorophosphate dissolved in ethylene carbonate:diethyl carbonate (LiPF6 in EC:DEC) were cycled in two different voltage windows of 1.0-2.0 V and 1.4-2.0 V. LTO electrodes were characterized after 5 and 100 cycles. Also the pristine electrode as such, and an electrode soaked in the electrolyte were analyzed by varying the photon energies enabling depth profiling of the outermost surface layer. The main components of the surface layer were found to be ethers, P-O containing compounds, and lithium fluoride.

An artificial interphase enables reversible magnesium chemistry in carbonate electrolytes.

PubMed

Son, Seoung-Bum; Gao, Tao; Harvey, Steve P; Steirer, K Xerxes; Stokes, Adam; Norman, Andrew; Wang, Chunsheng; Cresce, Arthur; Xu, Kang; Ban, Chunmei

2018-05-01

Magnesium-based batteries possess potential advantages over their lithium counterparts. However, reversible Mg chemistry requires a thermodynamically stable electrolyte at low potential, which is usually achieved with corrosive components and at the expense of stability against oxidation. In lithium-ion batteries the conflict between the cathodic and anodic stabilities of the electrolytes is resolved by forming an anode interphase that shields the electrolyte from being reduced. This strategy cannot be applied to Mg batteries because divalent Mg 2+ cannot penetrate such interphases. Here, we engineer an artificial Mg 2+ -conductive interphase on the Mg anode surface, which successfully decouples the anodic and cathodic requirements for electrolytes and demonstrate highly reversible Mg chemistry in oxidation-resistant electrolytes. The artificial interphase enables the reversible cycling of a Mg/V 2 O 5 full-cell in the water-containing, carbonate-based electrolyte. This approach provides a new avenue not only for Mg but also for other multivalent-cation batteries facing the same problems, taking a step towards their use in energy-storage applications.

An artificial interphase enables reversible magnesium chemistry in carbonate electrolytes

NASA Astrophysics Data System (ADS)

Son, Seoung-Bum; Gao, Tao; Harvey, Steve P.; Steirer, K. Xerxes; Stokes, Adam; Norman, Andrew; Wang, Chunsheng; Cresce, Arthur; Xu, Kang; Ban, Chunmei

2018-05-01

Magnesium-based batteries possess potential advantages over their lithium counterparts. However, reversible Mg chemistry requires a thermodynamically stable electrolyte at low potential, which is usually achieved with corrosive components and at the expense of stability against oxidation. In lithium-ion batteries the conflict between the cathodic and anodic stabilities of the electrolytes is resolved by forming an anode interphase that shields the electrolyte from being reduced. This strategy cannot be applied to Mg batteries because divalent Mg2+ cannot penetrate such interphases. Here, we engineer an artificial Mg2+-conductive interphase on the Mg anode surface, which successfully decouples the anodic and cathodic requirements for electrolytes and demonstrate highly reversible Mg chemistry in oxidation-resistant electrolytes. The artificial interphase enables the reversible cycling of a Mg/V2O5 full-cell in the water-containing, carbonate-based electrolyte. This approach provides a new avenue not only for Mg but also for other multivalent-cation batteries facing the same problems, taking a step towards their use in energy-storage applications.

A structural study of solid electrolyte interface on negative electrode of lithium-Ion battery by electron microscopy.

PubMed

Matsushita, Tadashi; Watanabe, Jiro; Nakao, Tatsuya; Yamashita, Seiichi

2014-11-01

For the last decades, the performance of the lithium-ion battery (LIB) has been significantly improved and its applications have been expanding rapidly. However, its performance has yet to be enhanced.In the lithium-ion battery development, it is important to elucidate the electrode structure change in detail during the charge and discharge cycling. In particular, solid electrolyte interface (SEI) formed by decomposition of the electrolytes on the graphite negative electrode surface should play an important role for battery properties. Therefore, it is essential to control the structure and composition of SEI to improve the battery performance. Here, we conducted a scanning electron microscope (SEM) and transmission electron microscope (TEM) study to elucidate the structures of the SEI during the charge and discharge process using LiNi1/3Co1/3Mn1/3O2 [1] cathode and graphite anode. [2] Since SEI is a lithium-containing compound with high activity, it was observed without being exposed to the atmosphere. The electrodes including SEI were sampled after dismantling batteries with cutoff voltages of 3V and 4.2V for the charge process and 3V for the discharge process. Fig.1 shows SEM images of the graphite electrode surface during the charge and discharge process. The change of the SEI structure during the process was clearly observed. Further, TEM images showed that the SEI grew thicker during the charge process and becomes thinner when discharged. These results with regard to the reversible SEI structure could give a new insight for the battery development.jmicro;63/suppl_1/i21/DFU056F1F1DFU056F1Fig. 1.SEM images of the graphite electrode surface:(a) before charge process;(b) with charge-cutoff voltage of 3.0V; (c) with charge-cutoff voltage of 4.2V; (d) with discharge-cutoff voltage of 3.0V. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Formation and Inhibition of Metallic Lithium Microstructures in Lithium Batteries Driven by Chemical Crossover

DOE PAGES

Li, Wangda; Kim, Un-Hyuck; Dolocan, Andrei; ...

2017-05-14

The formation of metallic lithium microstructures in the form of dendrites or mosses at the surface of anode electrodes (e.g., lithium metal, graphite, and silicon) leads to rapid capacity fade and poses grave safety risks in rechargeable lithium batteries. In this work, we present here a direct, relative quantitative analysis of lithium deposition on graphite anodes in pouch cells under normal operating conditions, paired with a model cathode material, the layered nickel-rich oxide LiNi 0.61Co 0.12Mn 0.27O 2, over the course of 3000 charge-discharge cycles. Secondary-ion mass spectrometry chemically dissects the solid-electrolyte interphase (SEI) on extensively cycled graphite with virtuallymore » atomic depth resolution and reveals substantial growth of Li-metal deposits. With the absence of apparent kinetic (e.g., fast charging) or stoichiometric restraints (e.g., overcharge) during cycling, we show lithium deposition on graphite is triggered by certain transition-metal ions (manganese in particular) dissolved from the cathode in a disrupted SEI. This insidious effect is found to initiate at a very early stage of cell operation (<200 cycles) and can be effectively inhibited by substituting a small amount of aluminum (~1 mol %) in the cathode, resulting in much reduced transition-metal dissolution and drastically improved cyclability. In conclusion, our results may also be applicable to studying the unstable electrodeposition of lithium on other substrates, including Li metal.« less

Formation and Inhibition of Metallic Lithium Microstructures in Lithium Batteries Driven by Chemical Crossover

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Wangda; Kim, Un-Hyuck; Dolocan, Andrei

The formation of metallic lithium microstructures in the form of dendrites or mosses at the surface of anode electrodes (e.g., lithium metal, graphite, and silicon) leads to rapid capacity fade and poses grave safety risks in rechargeable lithium batteries. In this work, we present here a direct, relative quantitative analysis of lithium deposition on graphite anodes in pouch cells under normal operating conditions, paired with a model cathode material, the layered nickel-rich oxide LiNi 0.61Co 0.12Mn 0.27O 2, over the course of 3000 charge-discharge cycles. Secondary-ion mass spectrometry chemically dissects the solid-electrolyte interphase (SEI) on extensively cycled graphite with virtuallymore » atomic depth resolution and reveals substantial growth of Li-metal deposits. With the absence of apparent kinetic (e.g., fast charging) or stoichiometric restraints (e.g., overcharge) during cycling, we show lithium deposition on graphite is triggered by certain transition-metal ions (manganese in particular) dissolved from the cathode in a disrupted SEI. This insidious effect is found to initiate at a very early stage of cell operation (<200 cycles) and can be effectively inhibited by substituting a small amount of aluminum (~1 mol %) in the cathode, resulting in much reduced transition-metal dissolution and drastically improved cyclability. In conclusion, our results may also be applicable to studying the unstable electrodeposition of lithium on other substrates, including Li metal.« less

Capacity Fading Mechanisms of Silicon Nanoparticle Negative Electrodes for Lithium Ion Batteries

DOE PAGES

Yoon, Taeho; Nguyen, Cao Cuong; Seo, Daniel M.; ...

2015-09-16

A thorough analysis of the evolution of the voltage profiles of silicon nanoparticle electrodes upon cycling has been conducted. The largest changes to the voltage profiles occur at the earlier stages (> 0.16 V vs Li/Li +) of lithiation of the silicon nanoparticles. The changes in the voltage profiles suggest that the predominant failure mechanism of the silicon electrode is related to incomplete delithiation of the silicon electrode during cycling. The incomplete delithiation is attributed to resistance increases during delithiation, which are predominantly contact and solid electrolyte interface (SEI) resistance. The capacity retention can be significantly improved by lowering delithiationmore » cutoff voltage or by introducing electrolyte additives, which generate a superior SEI. The improved capacity retention is attributed to the reduction of the contact and SEI resistance.« less

An artificial interphase enables reversible magnesium chemistry in carbonate electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Son, Seoung-Bum; Gao, Tao; Harvey, Steve P.

Magnesium-based batteries possess potential advantages over their lithium counterparts. However, reversible Mg chemistry requires a thermodynamically stable electrolyte at low potential, which is usually achieved with corrosive components and at the expense of stability against oxidation. In lithium-ion batteries the conflict between the cathodic and anodic stabilities of the electrolytes is resolved by forming an anode interphase that shields the electrolyte from being reduced. This strategy cannot be applied to Mg batteries because divalent Mg2+ cannot penetrate such interphases. Here, we engineer an artificial Mg2+-conductive interphase on the Mg anode surface, which successfully decouples the anodic and cathodic requirements formore » electrolytes and demonstrate highly reversible Mg chemistry in oxidation-resistant electrolytes. The artificial interphase enables the reversible cycling of a Mg/V2O5 full-cell in the water-containing, carbonate-based electrolyte. This approach provides a new avenue not only for Mg but also for other multivalent-cation batteries facing the same problems, taking a step towards their use in energy-storage applications.« less

Interfacial Stability of Li Metal-Solid Electrolyte Elucidated via in Situ Electron Microscopy.

PubMed

Ma, Cheng; Cheng, Yongqiang; Yin, Kuibo; Luo, Jian; Sharafi, Asma; Sakamoto, Jeff; Li, Juchuan; More, Karren L; Dudney, Nancy J; Chi, Miaofang

2016-11-09

Despite their different chemistries, novel energy-storage systems, e.g., Li-air, Li-S, all-solid-state Li batteries, etc., face one critical challenge of forming a conductive and stable interface between Li metal and a solid electrolyte. An accurate understanding of the formation mechanism and the exact structure and chemistry of the rarely existing benign interfaces, such as the Li-cubic-Li 7-3x Al x La 3 Zr 2 O 12 (c-LLZO) interface, is crucial for enabling the use of Li metal anodes. Due to spatial confinement and structural and chemical complications, current investigations are largely limited to theoretical calculations. Here, through an in situ formation of Li-c-LLZO interfaces inside an aberration-corrected scanning transmission electron microscope, we successfully reveal the interfacial chemical and structural progression. Upon contact with Li metal, the LLZO surface is reduced, which is accompanied by the simultaneous implantation of Li + , resulting in a tetragonal-like LLZO interphase that stabilizes at an extremely small thickness of around five unit cells. This interphase effectively prevented further interfacial reactions without compromising the ionic conductivity. Although the cubic-to-tetragonal transition is typically undesired during LLZO synthesis, the similar structural change was found to be the likely key to the observed benign interface. These insights provide a new perspective for designing Li-solid electrolyte interfaces that can enable the use of Li metal anodes in next-generation batteries.

Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

PubMed Central

Li, Wangda; Dolocan, Andrei; Oh, Pilgun; Celio, Hugo; Park, Suhyeon; Cho, Jaephil; Manthiram, Arumugam

2017-01-01

Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries. PMID:28443608

Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Li, Wangda; Dolocan, Andrei; Oh, Pilgun; Celio, Hugo; Park, Suhyeon; Cho, Jaephil; Manthiram, Arumugam

2017-04-01

Undesired electrode-electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.

Elucidating electrolyte decomposition under electron-rich environments at the lithium-metal anode

DOE PAGES

Camacho-Forero, Luis E.; Balbuena, Perla B.

2017-11-07

The lithium metal anode is one of the key components of the lithium–sulfur (Li–S) batteries, which are considered one of the most promising candidates for the next generation of battery systems. However, one of the main challenges that have prevented Li-metal anodes from becoming feasible to be used in commercial batteries is the continuous decomposition of the electrolyte due to its high reactivity, which leads to the formation of solid–electrolyte interphase (SEI) layers. The properties of the SEI can dramatically affect the performance of the batteries. Thus, a rigorous understanding of the electrolyte decomposition is crucial to elucidate improvements inmore » performance of the Li–S technology. Here, in this work, using density functional theory (DFT) and ab initio molecular dynamics simulations (AIMD), we investigate the effect of electron-rich environments on the decomposition mechanism of electrolyte species in pure 1,2-dimethoxyethane (DME) solvent and 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI) salt solutions. It is found that systems with pure DME require an average environment of at least ~0.9 |e| per molecule for a DME to decompose into CH 3O - and C 2H 4 2-via a 4-electron transfer. In the case of mixtures, the salts are very prone to react with any excess of electrons. In addition, DME dehydrogenation due to reactions with fragments coming from the salt decompositions was detected. Formation of oligomer anionic species from DME and salt fragments were also identified from the AIMD simulations. Finally, the thermodynamics and kinetics of the most relevant electrolyte decomposition reactions were characterized. DME decomposition reactions predicted from the AIMD simulations were found to be thermodynamically favorable under exposure to Li atoms and/or by reactions with salt fragments. Lastly, in most cases, these reactions were shown to have low to moderate activation barriers.« less

Elucidating electrolyte decomposition under electron-rich environments at the lithium-metal anode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Camacho-Forero, Luis E.; Balbuena, Perla B.

The lithium metal anode is one of the key components of the lithium–sulfur (Li–S) batteries, which are considered one of the most promising candidates for the next generation of battery systems. However, one of the main challenges that have prevented Li-metal anodes from becoming feasible to be used in commercial batteries is the continuous decomposition of the electrolyte due to its high reactivity, which leads to the formation of solid–electrolyte interphase (SEI) layers. The properties of the SEI can dramatically affect the performance of the batteries. Thus, a rigorous understanding of the electrolyte decomposition is crucial to elucidate improvements inmore » performance of the Li–S technology. Here, in this work, using density functional theory (DFT) and ab initio molecular dynamics simulations (AIMD), we investigate the effect of electron-rich environments on the decomposition mechanism of electrolyte species in pure 1,2-dimethoxyethane (DME) solvent and 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI) salt solutions. It is found that systems with pure DME require an average environment of at least ~0.9 |e| per molecule for a DME to decompose into CH 3O - and C 2H 4 2-via a 4-electron transfer. In the case of mixtures, the salts are very prone to react with any excess of electrons. In addition, DME dehydrogenation due to reactions with fragments coming from the salt decompositions was detected. Formation of oligomer anionic species from DME and salt fragments were also identified from the AIMD simulations. Finally, the thermodynamics and kinetics of the most relevant electrolyte decomposition reactions were characterized. DME decomposition reactions predicted from the AIMD simulations were found to be thermodynamically favorable under exposure to Li atoms and/or by reactions with salt fragments. Lastly, in most cases, these reactions were shown to have low to moderate activation barriers.« less

Unraveling the electrolyte properties of Na3SbS4 through computation and experiment

NASA Astrophysics Data System (ADS)

Rush, Larry E.; Hood, Zachary D.; Holzwarth, N. A. W.

2017-12-01

Solid-state sodium electrolytes are expected to improve next-generation batteries on the basis of favorable energy density and reduced cost. Na3SbS4 represents a new solid-state ion conductor with high ionic conductivities in the mS/cm range. Here, we explore the tetragonal phase of Na3SbS4 and its interface with metallic sodium anode using a combination of experiments and first-principles calculations. The computed Na-ion vacancy migration energies of 0.1 eV are smaller than the value inferred from experiment, suggesting that grain boundaries or other factors dominate the experimental systems. Analysis of symmetric cells of the electrolyte—Na/Na 3SbS4/Na —show that a conductive solid electrolyte interphase forms. Computer simulations infer that the interface is likely to be related to Na3SbS3 , involving the conversion of the tetrahedral SbS43 - ions of the bulk electrolyte into trigonal pyramidal SbS33 - ions at the interface.

Methods for solid electrolyte interphase formation and anode pre-lithiation of lithium ion capacitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raman, Santhanam; Xi, Xiaomei; Ye, Xiang-Rong

A method of pre-doping an anode of an energy storage device can include immersing the anode and a dopant source in an electrolyte, and coupling a substantially constant current between the anode and the dopant source. A method of pre-doping an anode of an energy storage device can include immersing the anode and a dopant source in an electrolyte, and coupling a substantially constant voltage across the anode and the dopant source. An energy storage device can include an anode having a lithium ion pre-doping level of about 60% to about 90%.

High performance sulfur graphite full cell for next generation sulfur Li-ion battery

NASA Astrophysics Data System (ADS)

Wu, Yunwen; Momma, Toshiyuki; Yokoshima, Tokihiko; Nara, Hiroki; Osaka, Tetsuya

2018-06-01

Sulfur (S) Li-ion battery which use the metallic Li free anode is deemed as a promising solution to conquer the hazards originating from Li metal. However, stable cycling performance and low production price of the S Li-ion battery still remain challenging. Here, we propose a S-LixC full cell system by paring a S cathode and a pre-lithiated graphite anode which is cheap and commercially available. It shows stable cycling performance with a capacity around 1300 mAh (g-S)-1 at 0.2 C-rate and 1000 mAh (g-S)-1 at 0.5 C-rate. In addition, 0.1% per cycle capacity fading rate with a capacity retention of 880 mAh (g-S)-1 after 400 cycles at 0.2 C-rate has been achieved. The pre-formed solid electrolyte interphase (SEI) layer on the pre-lithaited graphite anode largely contributes to the high capacity performance. Notably, a 10-times-enlarged scale of S-LixC laminate type full cell has been assembled with high capacity performance (around 1000 mAh (g-S)-1) even after high rate cycling.

Nature of the Electrochemical Properties of Sulphur Substituted LiMn2O4 Spinel Cathode Material Studied by Electrochemical Impedance Spectroscopy

PubMed Central

Bakierska, Monika; Świętosławski, Michał; Dziembaj, Roman; Molenda, Marcin

2016-01-01

In this work, nanostructured LiMn2O4 (LMO) and LiMn2O3.99S0.01 (LMOS1) spinel cathode materials were comprehensively investigated in terms of electrochemical properties. For this purpose, electrochemical impedance spectroscopy (EIS) measurements as a function of state of charge (SOC) were conducted on a representative charge and discharge cycle. The changes in the electrochemical performance of the stoichiometric and sulphur-substituted lithium manganese oxide spinels were examined, and suggested explanations for the observed dependencies were given. A strong influence of sulphur introduction into the spinel structure on the chemical stability and electrochemical characteristic was observed. It was demonstrated that the significant improvement in coulombic efficiency and capacity retention of lithium cell with LMOS1 active material arises from a more stable solid electrolyte interphase (SEI) layer. Based on EIS studies, the Li ion diffusion coefficients in the cathodes were estimated, and the influence of sulphur on Li+ diffusivity in the spinel structure was established. The obtained results support the assumption that sulphur substitution is an effective way to promote chemical stability and the electrochemical performance of LiMn2O4 cathode material. PMID:28773819

Self-generated concentration and modulus gradient coating design to protect Si nano-wire electrodes during lithiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Sung-Yup; Ostadhossein, Alireza; van Duin, Adri C. T.

2016-01-01

Surface coatings as artificial solid electrolyte interphases have been actively pursued as an effective way to improve the cycle efficiency of nanostructured Si electrodes for high energy density lithium ion batteries, where the mechanical stability of the surface coatings on Si is as critical as Si itself.

Co9 S8 /Co as a High-Performance Anode for Sodium-Ion Batteries with an Ether-Based Electrolyte.

PubMed

Zhao, Yingying; Pang, Qiang; Wei, Yingjin; Wei, Luyao; Ju, Yanming; Zou, Bo; Gao, Yu; Chen, Gang

2017-12-08

Co 9 S 8 has been regarded as a desirable anode material for sodium-ion batteries because of its high theoretical capacity. In this study, a Co 9 S 8 anode material containing 5.5 wt % Co (Co 9 S 8 /Co) was prepared by a solid-state reaction. The electrochemical properties of the material were studied in carbonate and ether-based electrolytes (EBE). The results showed that the material had a longer cycle life and better rate capability in EBE. This excellent electrochemical performance was attributed to a low apparent activation energy and a low overpotential for Na deposition in EBE, which improved the electrode kinetic properties. Furthermore, EBE suppressed side reactions of the electrode and electrolyte, which avoided the formation of a solid electrolyte interphase film. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lithium-ion conducting electrolyte salts for lithium batteries.

PubMed

Aravindan, Vanchiappan; Gnanaraj, Joe; Madhavi, Srinivasan; Liu, Hua-Kun

2011-12-16

This paper presents an overview of the various types of lithium salts used to conduct Li(+) ions in electrolyte solutions for lithium rechargeable batteries. More emphasis is paid towards lithium salts and their ionic conductivity in conventional solutions, solid-electrolyte interface (SEI) formation towards carbonaceous anodes and the effect of anions on the aluminium current collector. The physicochemical and functional parameters relevant to electrochemical properties, that is, electrochemical stabilities, are also presented. The new types of lithium salts, such as the bis(oxalato)borate (LiBOB), oxalyldifluoroborate (LiODFB) and fluoroalkylphosphate (LiFAP), are described in detail with their appropriate synthesis procedures, possible decomposition mechanism for SEI formation and prospect of using them in future generation lithium-ion batteries. Finally, the state-of-the-art of the system is given and some interesting strategies for the future developments are illustrated. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Wangda; Dolocan, Andrei; Oh, Pilgun

Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species.more » By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Finally, our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.« less

Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

DOE PAGES

Li, Wangda; Dolocan, Andrei; Oh, Pilgun; ...

2017-04-26

Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species.more » By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Finally, our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.« less

A pomegranate-inspired nanoscale design for large-volume-change lithium battery anodes

NASA Astrophysics Data System (ADS)

Liu, Nian; Lu, Zhenda; Zhao, Jie; McDowell, Matthew T.; Lee, Hyun-Wook; Zhao, Wenting; Cui, Yi

2014-03-01

Silicon is an attractive material for anodes in energy storage devices, because it has ten times the theoretical capacity of its state-of-the-art carbonaceous counterpart. Silicon anodes can be used both in traditional lithium-ion batteries and in more recent Li-O2 and Li-S batteries as a replacement for the dendrite-forming lithium metal anodes. The main challenges associated with silicon anodes are structural degradation and instability of the solid-electrolyte interphase caused by the large volume change (~300%) during cycling, the occurrence of side reactions with the electrolyte, and the low volumetric capacity when the material size is reduced to a nanometre scale. Here, we propose a hierarchical structured silicon anode that tackles all three of these problems. Our design is inspired by the structure of a pomegranate, where single silicon nanoparticles are encapsulated by a conductive carbon layer that leaves enough room for expansion and contraction following lithiation and delithiation. An ensemble of these hybrid nanoparticles is then encapsulated by a thicker carbon layer in micrometre-size pouches to act as an electrolyte barrier. As a result of this hierarchical arrangement, the solid-electrolyte interphase remains stable and spatially confined, resulting in superior cyclability (97% capacity retention after 1,000 cycles). In addition, the microstructures lower the electrode-electrolyte contact area, resulting in high Coulombic efficiency (99.87%) and volumetric capacity (1,270 mAh cm-3), and the cycling remains stable even when the areal capacity is increased to the level of commercial lithium-ion batteries (3.7 mAh cm-2).

Lithium Self-Discharge and Its Prevention: Direct Visualization through In Situ Electrochemical Scanning Transmission Electron Microscopy

DOE PAGES

Harrison, Katharine L.; Zavadil, Kevin R.; Hahn, Nathan T.; ...

2017-11-07

To understand the mechanism that controls low-aspect-ratio lithium deposition morphologies for Li-metal anodes in batteries, we conducted direct visualization of Li-metal deposition and stripping behavior through nanoscale in situ electrochemical scanning transmission electron microscopy (EC-STEM) and macroscale-cell electrochemistry experiments in a recently developed and promising solvate electrolyte, 4 M lithium bis(fluorosulfonyl)imide in 1,2-dimethoxyethane. In contrast to published coin cell studies in the same electrolyte, our experiments revealed low Coulombic efficiencies and inhomogeneous Li morphology during in situ observation. In addition, we conclude that this discrepancy in Coulombic efficiency and morphology of the Li deposits was dependent on the presence ofmore » a compressed lithium separator interface, as we have confirmed through macroscale (not in the transmission electron microscope) electrochemical experiments. Our data suggests that cell compression changed how the solid-electrolyte interphase formed, which is likely responsible for improved morphology and Coulombic efficiency with compression. Furthermore, during the in situ EC-STEM experiments, we observed direct evidence of nanoscale self-discharge in the solvate electrolyte (in the state of electrical isolation). This self-discharge was duplicated in the macroscale, but it was less severe with electrode compression, likely due to a more passivating and corrosion-resistant solid-electrolyte interphase formed in the presence of compression. By combining the solvate electrolyte with a protective LiAl 0.3S coating, we show that the Li nucleation density increased during deposition, leading to improved morphological uniformity. In conclusion, self-discharge was suppressed during rest periods in the cycling profile with coatings present, as evidenced through EC-STEM and confirmed with coin cell data.« less

Lithium Self-Discharge and Its Prevention: Direct Visualization through In Situ Electrochemical Scanning Transmission Electron Microscopy.

PubMed

Harrison, Katharine L; Zavadil, Kevin R; Hahn, Nathan T; Meng, Xiangbo; Elam, Jeffrey W; Leenheer, Andrew; Zhang, Ji-Guang; Jungjohann, Katherine L

2017-11-28

To understand the mechanism that controls low-aspect-ratio lithium deposition morphologies for Li-metal anodes in batteries, we conducted direct visualization of Li-metal deposition and stripping behavior through nanoscale in situ electrochemical scanning transmission electron microscopy (EC-STEM) and macroscale-cell electrochemistry experiments in a recently developed and promising solvate electrolyte, 4 M lithium bis(fluorosulfonyl)imide in 1,2-dimethoxyethane. In contrast to published coin cell studies in the same electrolyte, our experiments revealed low Coulombic efficiencies and inhomogeneous Li morphology during in situ observation. We conclude that this discrepancy in Coulombic efficiency and morphology of the Li deposits was dependent on the presence of a compressed lithium separator interface, as we have confirmed through macroscale (not in the transmission electron microscope) electrochemical experiments. Our data suggests that cell compression changed how the solid-electrolyte interphase formed, which is likely responsible for improved morphology and Coulombic efficiency with compression. Furthermore, during the in situ EC-STEM experiments, we observed direct evidence of nanoscale self-discharge in the solvate electrolyte (in the state of electrical isolation). This self-discharge was duplicated in the macroscale, but it was less severe with electrode compression, likely due to a more passivating and corrosion-resistant solid-electrolyte interphase formed in the presence of compression. By combining the solvate electrolyte with a protective LiAl 0.3 S coating, we show that the Li nucleation density increased during deposition, leading to improved morphological uniformity. Furthermore, self-discharge was suppressed during rest periods in the cycling profile with coatings present, as evidenced through EC-STEM and confirmed with coin cell data.

Lithium Self-Discharge and Its Prevention: Direct Visualization through In Situ Electrochemical Scanning Transmission Electron Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrison, Katharine L.; Zavadil, Kevin R.; Hahn, Nathan T.

To understand the mechanism that controls low-aspect-ratio lithium deposition morphologies for Li-metal anodes in batteries, we conducted direct visualization of Li-metal deposition and stripping behavior through nanoscale in situ electrochemical scanning transmission electron microscopy (EC-STEM) and macroscale-cell electrochemistry experiments in a recently developed and promising solvate electrolyte, 4 M lithium bis(fluorosulfonyl)imide in 1,2-dimethoxyethane. In contrast to published coin cell studies in the same electrolyte, our experiments revealed low Coulombic efficiencies and inhomogeneous Li morphology during in situ observation. In addition, we conclude that this discrepancy in Coulombic efficiency and morphology of the Li deposits was dependent on the presence ofmore » a compressed lithium separator interface, as we have confirmed through macroscale (not in the transmission electron microscope) electrochemical experiments. Our data suggests that cell compression changed how the solid-electrolyte interphase formed, which is likely responsible for improved morphology and Coulombic efficiency with compression. Furthermore, during the in situ EC-STEM experiments, we observed direct evidence of nanoscale self-discharge in the solvate electrolyte (in the state of electrical isolation). This self-discharge was duplicated in the macroscale, but it was less severe with electrode compression, likely due to a more passivating and corrosion-resistant solid-electrolyte interphase formed in the presence of compression. By combining the solvate electrolyte with a protective LiAl 0.3S coating, we show that the Li nucleation density increased during deposition, leading to improved morphological uniformity. In conclusion, self-discharge was suppressed during rest periods in the cycling profile with coatings present, as evidenced through EC-STEM and confirmed with coin cell data.« less

N-Allyl- N, N-Bis(trimethylsilyl)amine as a Novel Electrolyte Additive To Enhance the Interfacial Stability of a Ni-Rich Electrode for Lithium-Ion Batteries.

PubMed

Zheng, Qinfeng; Xing, Lidan; Yang, Xuerui; Li, Xiangfeng; Ye, Changchun; Wang, Kang; Huang, Qiming; Li, Weishan

2018-05-16

Enhancing the electrode/electrolyte interface stability of high-capacity LiNi 0.8 Co 0.15 Al 0.05 O 2 (LNCA) cathode material is urgently required for its application in next-generation lithium-ion battery. Herein, we demonstrate that enhanced interfacial stability of LNCA can be achieved by simply introducing 2 wt % N-allyl- N, N-bis(trimethylsilyl)amine (NNB) electrolyte additive. Electrolyte oxidation reactions and electrode structural destruction are greatly suppressed in the electrolyte with NNB additive, leading to improved cyclic stability of LNCA from 72.8 to 86.2% after 300 cycles. The mechanism of NNB on improving the cyclic stability of LNCA has been verified to its excellent solid electrolyte interface (SEI) film-forming capability. Moreover, the X-ray diffraction and X-ray photoelectron spectroscopy results indicate that the NNB-derived Si-containing SEI film restrains the Li/Ni disorder of LNCA during cycling, which further improves the cyclic stability of Ni-rich LNCA. Importantly, the charging/discharging test reveals that the NNB additive effectively improves the cyclic stability of the LNCA/graphite full cell.

Quantitative MAS NMR characterization of the LiMn(1/2)Ni(1/2)O(2) electrode/electrolyte interphase.

PubMed

Cuisinier, M; Martin, J F; Moreau, P; Epicier, T; Kanno, R; Guyomard, D; Dupré, N

2012-04-01

The conditions in which degradation processes at the positive electrode/electrolyte interface occur are still incompletely understood and traditional surface analytical techniques struggle to characterize and depict accurately interfacial films. In the present work, information on the growth and evolution of the interphases upon storage and cycling as well as their electrochemical consequences are gathered in the case of LiNi(1/2)Mn(1/2)O(2) with commonly used LiPF(6) (1M in EC/DMC) electrolyte. The use of (7)Li, (19)F and (31)P MAS NMR, made quantitative through the implementation of empirical calibration, is combined with transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) to probe the elements involved in surface species and to unravel the inhomogenous architecture of the interphase. At room temperature, contact with the electrolyte leads to a covering of the oxide surface first by LiF and lithiated organic species are found on the outer part of the interphase. At 55°C, not only the interphase proceeds in further covering of the surface but also thickens resulting in an increase of 240% of lithiated species and the presence of -POF(2) fluorophosphates. The composition gradient within the interphase depth is also strongly affected by the temperature. In agreement with the electrochemical performance, quantitative NMR surface analyses show that the use of LiBOB-modified electrolyte results in a Li-enriched interphase, intrinsically less resistive than the standard LiPF(6)-based interphase, comprised of a mixture of resistive LiF with non lithiated species. Copyright © 2011 Elsevier Inc. All rights reserved.

Reduction of Electrolyte Components on a Coated Si Anode of Lithium-Ion Batteries.

PubMed

Gomez-Ballesteros, Jose L; Balbuena, Perla B

2017-07-20

Surface modification of Si anodes in Li-ion batteries by deposition of a thin alucone coating has demonstrated an effective way to help maintain a stable anode/electrolyte interface and good battery performance. In this work, we investigate the interactions and reactivity of the film with electrolyte components using ab initio molecular dynamics simulations. Adsorption of solvent molecules (ethylene carbonate, EC) and salt (LiPF 6 ) and reduction by two mechanisms depending on the Li content of the film (yielding open EC adsorbed on the film or C 2 H 4 + CO 3 2- ) take place near the film/electrolyte and film/anode interfaces. Reaction products incorporate into the structure of the film and create a new kind of solid-electrolyte interphase layer.

Reduction of Electrolyte Components on a Coated Si Anode of Lithium-Ion Batteries

DOE PAGES

Gomez-Ballesteros, Jose L.; Balbuena, Perla B.

2017-07-07

Surface modification of Si anodes in Li-ion batteries by deposition of a thin alucone coating has demonstrated an effective way to help maintain a stable anode/electrolyte interface and good battery performance. In this paper, we investigate the interactions and reactivity of the film with electrolyte components using ab initio molecular dynamics simulations. Adsorption of solvent molecules (ethylene carbonate, EC) and salt (LiPF 6), and reduction by two mechanisms depending on the Li content of the film (yielding open EC adsorbed on the film or C 2H 4 + CO 3 2-) take place near the film/electrolyte and film/anode interfaces. Finally,more » reactions products incorporate to the structure of the film and create a new kind of solid-electrolyte interphase layer.« less

Hybrid electrolytes for lithium metal batteries

NASA Astrophysics Data System (ADS)

Keller, Marlou; Varzi, Alberto; Passerini, Stefano

2018-07-01

This perspective article discusses the most recent developments in the field of hybrid electrolytes, here referred to electrolytes composed of two, well-defined ion-conducting phases, for high energy density lithium metal batteries. The two phases can be both solid, as e.g., two inorganic conductors or one inorganic and one polymer conductor, or, differently, one liquid and one inorganic conductor. In this latter case, they are referred as quasi-solid hybrid electrolytes. Techniques for the appropriate characterization of hybrid electrolytes are discussed emphasizing the importance of ionic conduction and interfacial properties. On this view, multilayer systems are also discussed in more detail. Investigations on Lewis acid-base interactions, activation energies for lithium-ion transfer between the phases, and the formation of an interphase between the components are reviewed and analyzed. The application of different hybrid electrolytes in lithium metal cells with various cathode compositions is also discussed. Fabrication methods for the feasibility of large-scale applications are briefly analyzed and different cell designs and configurations, which are most suitable for the integration of hybrid electrolytes, are determined. Finally, the specific energy of cells containing different hybrid electrolytes is estimated to predict possible enhancement in energy with respect to the current lithium-ion battery technology.

Dendrite Suppression by Synergistic Combination of Solid Polymer Electrolyte Crosslinked with Natural Terpenes and Lithium-Powder Anode for Lithium-Metal Batteries.

PubMed

Shim, Jimin; Lee, Jae Won; Bae, Ki Yoon; Kim, Hee Joong; Yoon, Woo Young; Lee, Jong-Chan

2017-05-22

Lithium-metal anode has fundamental problems concerning formation and growth of lithium dendrites, which prevents practical applications of next generation of high-capacity lithium-metal batteries. The synergistic combination of solid polymer electrolyte (SPE) crosslinked with naturally occurring terpenes and lithium-powder anode is promising solution to resolve the dendrite issues by substituting conventional liquid electrolyte/separator and lithium-foil anode system. A series of SPEs based on polysiloxane crosslinked with natural terpenes are prepared by facile thiol-ene click reaction under mild condition and the structural effect of terpene crosslinkers on electrochemical properties is studied. Lithium powder with large surface area is prepared by droplet emulsion technique (DET) and used as anode material. The effect of the physical state of electrolyte (solid/liquid) and morphology of lithium-metal anode (powder/foil) on dendrite growth behavior is systematically studied. The synergistic combination of SPE and lithium-powder anode suggests an effective solution to suppress the dendrite growth owing to the formation of a stable solid-electrolyte interface (SEI) layer and delocalized current density. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lithium-Ion Electrolytes Containing Flame Retardant Additives for Increased Safety Characteristics

NASA Technical Reports Server (NTRS)

Bugga, Ratnakumar V. (Inventor); Krause, Frederick Charles (Inventor); Smart, Marshall C. (Inventor); Prakash, Surya G. (Inventor); Smith, Kiah A. (Inventor)

2014-01-01

The invention discloses various embodiments of Li-ion electrolytes containing flame retardant additives that have delivered good performance over a wide temperature range, good cycle life characteristics, and improved safety characteristics, namely, reduced flammability. In one embodiment of the invention there is provided an electrolyte for use in a lithium-ion electrochemical cell, the electrolyte comprising a mixture of an ethylene carbonate (EC), an ethyl methyl carbonate (EMC), a fluorinated co-solvent, a flame retardant additive, and a lithium salt. In another embodiment of the invention there is provided an electrolyte for use in a lithium-ion electrochemical cell, the electrolyte comprising a mixture of an ethylene carbonate (EC), an ethyl methyl carbonate (EMC), a flame retardant additive, a solid electrolyte interface (SEI) film forming agent, and a lithium salt.

A contrastive study of three graphite anodes in the piperidinium based electrolytes for lithium ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Xiao-Tao; Wang, Chen-Yi; Gao, Kun, E-mail: gaokun0451@163.com

Graphical abstract: The fitting results of R{sub sei} and R{sub ct} of three graphite/Li cells. Besides three graphite/Li cells show the similar R{sub sei}, the NG198/Li cell demonstrates a higher R{sub ct} value in all test temperatures. Especially, the R{sub ct} at 333 K is even up to 355.8 Ω cm{sup 2}. Obviously, the narrow distribution of edge plane for NG198 caused this result, and then greatly restricts its cell capacity. By contrast, CMB with bigger specific surface area and more Li{sup +} insertion points shows lower resistance at room temperature, which should help to improve its capacity. - Highlights:more » • SEI film is closely related to graphite structures and formation temperature. • The graphite with bigger surface area and more Li{sup +} insertion points behaves better. • The graphite with narrow edge plane is uncompetitive for ionic liquid electrolyte. - Abstract: The electrochemical behaviors of natural graphite (NG198), artificial graphite (AG360) and carbon microbeads (CMB) in an ionic liquid based electrolyte are investigated by cyclic voltammetry (CV). The surface and structure of three graphite materials are characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) before and after cycling. It is found that solid electrolyte interface (SEI) is closely related to graphite structure. Benefiting from larger specific surface area and more dispersed Li{sup +} insertion points, CMB shows a better Li{sup +} insertion/de-insertion behavior than NG198 and AG360. Furthermore, electrochemical impedance spectra (EIS) prove that the SEI of different graphite electrodes has different intrinsic resistance and Li{sup +} penetrability. By comparison, CMB behaves better cell performances than AG360, while the narrow edge plane makes NG198 uncompetitive as a potential anode for the ionic liquids (ILs)-type Li-ion battery.« less

Advanced electrolyte/additive for lithium-ion batteries with silicon anode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Shuo; He, Meinan; Su, Chi-Cheung

State-of-the-art lithium-ion batteries (LIBs) are based on a lithium transition metal oxide cathode, a graphite anode and a nonaqueous carbonate electrolyte. To further increase the energy and power density of LIBs, silicon anodes have been intensively explored due to their high theoretical capacity, low operation potential, and low cost. However, the main challenges for Si anode are the large volume change during lithiation/delithiation process and the instability of the solid-electrolyte-interphase associated with this process. Recently, significant progress has been achieved via advanced material fabrication technologies and rational electrolyte design in terms of improving the Coulombic efficiency and capacity retention. Inmore » this paper, new developments in advanced electrolyte and additive for LIBs with Si anode were systematically reviewed, and perspectives over future research were suggested.« less

Post-mortem analysis on LiFePO4|Graphite cells describing the evolution & composition of covering layer on anode and their impact on cell performance

NASA Astrophysics Data System (ADS)

Lewerenz, Meinert; Warnecke, Alexander; Sauer, Dirk Uwe

2017-11-01

During cyclic aging of lithium-ion batteries the formation of a μm-thick covering layer on top of the anode facing the separator is found on top of the anode. In this work several post-mortem analyses of cyclic aged cylindrical LFP|Graphite cells are evaluated to give a detailed characterization of the covering layer and to find possible causes for the evolution of such a layer. The analyses of the layer with different methods return that it consists to high percentage of plated active lithium, deposited Fe and products of a solid electrolyte interphase (SEI). The deposition is located mainly in the center of the cell symmetrical to the coating direction. The origin of these depositions is assumed in locally overcharged particles, Fe deposition or inhomogeneous distribution of capacity density. As a secondary effect the deposition on one side increases the thickness locally; thereafter a pressure-induced overcharging due to charge agglomeration of the back side of the anode occurs. Finally a compact and dense covering layer in a late state of aging leads to deactivation of the covered parts of the anode and cathode due to suppressed lithium-ion conductivity. This leads to increasing slope of capacity fade and increase of internal resistance.

Structure-Property Relationships of Organic Electrolytes and Their Effects on Li/S Battery Performance.

PubMed

Kaiser, Mohammad Rejaul; Chou, Shulei; Liu, Hua-Kun; Dou, Shi-Xue; Wang, Chunsheng; Wang, Jiazhao

2017-12-01

Electrolytes, which are a key component in electrochemical devices, transport ions between the sulfur/carbon composite cathode and the lithium anode in lithium-sulfur batteries (LSBs). The performance of a LSB mostly depends on the electrolyte due to the dissolution of polysulfides into the electrolyte, along with the formation of a solid-electrolyte interphase. The selection of the electrolyte and its functionality during charging and discharging is intricate and involves multiple reactions and processes. The selection of the proper electrolyte, including solvents and salts, for LSBs strongly depends on its physical and chemical properties, which is heavily controlled by its molecular structure. In this review, the fundamental properties of organic electrolytes for LSBs are presented, and an attempt is made to determine the relationship between the molecular structure and the properties of common organic electrolytes, along with their effects on the LSB performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Density Functional Theory Research into the Reduction Mechanism for the Solvent/Additive in a Sodium-Ion Battery.

PubMed

Liu, Qi; Mu, Daobin; Wu, Borong; Wang, Lei; Gai, Liang; Wu, Feng

2017-02-22

The solid-electrolyte interface (SEI) film in a sodium-ion battery is closely related to capacity fading and cycling stability of the battery. However, there are few studies on the SEI film of sodium-ion batteries and the mechanism of SEI film formation is unclear. The mechanism for the reduction of ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), ethylene sulfite (ES), 1,3-propylene sulfite (PS), and fluorinated ethylene carbonate (FEC) is studied by DFT. The reaction activation energies, Gibbs free energies, enthalpies, and structures of the transition states are calculated. It is indicated that VC, ES, and PS additives in the electrolyte are all easier to form organic components in the anode SEI film by one-electron reduction. The priority of one-electron reduction to produce organic SEI components is in the order of VC>PC>EC; two-electron reduction to produce the inorganic Na 2 CO 3 component is different and follows the order of EC>PC>VC. Two-electron reduction for sulfites ES and PS to form inorganic Na 2 SO 3 is harder than that of carbonate ester reduction. It is also suggested that the one- and two-electron reductive decomposition pathway for FEC is more feasible to produce inorganic NaF components. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical performance and interfacial properties of Li-metal in lithium bis(fluorosulfonyl)imide based electrolytes.

PubMed

Younesi, Reza; Bardé, Fanny

2017-11-21

Successful usage of lithium metal as the negative electrode or anode in rechargeable batteries can be an important step to increase the energy density of lithium batteries. Performance of lithium metal in a relatively promising electrolyte solution composed of lithium bis(fluorosulfonyl)imide (LiN(SO 2 F) 2 ; LiFSI) salt dissolved in 1,2-dimethoxyethane (DME) is here studied. The influence of the concentration of the electrolyte salt -1 M or 4 M LiFSI- is investigated by varying important electrochemical parameters such as applied current density and plating capacity. X-ray photoelectron spectroscopy analysis as a surface sensitive technique is here used to analyze that how the composition of the solid electrolyte interphase varies with the salt concentration and with the number of cycles.

A High-Energy-Density Potassium Battery with a Polymer-Gel Electrolyte and a Polyaniline Cathode.

PubMed

Gao, Hongcai; Xue, Leigang; Xin, Sen; Goodenough, John B

2018-05-04

A safe, rechargeable potassium battery of high energy density and excellent cycling stability has been developed. The anion component of the electrolyte salt is inserted into a polyaniline cathode upon charging and extracted from it during discharging while the K + ion of the KPF 6 salt is plated/stripped on the potassium-metal anode. The use of a p-type polymer cathode increases the cell voltage. By replacing the organic-liquid electrolyte in a glass-fiber separator with a polymer-gel electrolyte of cross-linked poly(methyl methacrylate), a dendrite-free potassium anode can be plated/stripped, and the electrode/electrolyte interface is stabilized. The potassium anode wets the polymer, and the cross-linked architecture provides small pores of adjustable sizes to stabilize a solid-electrolyte interphase formed at the anode/electrolyte interface. This alternative electrolyte/cathode strategy offers a promising new approach to low-cost potassium batteries for the stationary storage of electric power. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Li-Ion Cells Employing Electrolytes With Methyl Propionate and Ethyl Butyrate Co-Solvents

NASA Technical Reports Server (NTRS)

Smart, Marshall C.; Bugga, Ratnakumar V.

2011-01-01

Future NASA missions aimed at exploring Mars and the outer planets require rechargeable batteries that can operate at low temperatures to satisfy the requirements of such applications as landers, rovers, and penetrators. A number of terrestrial applications, such as hybrid electric vehicles (HEVs) and electric vehicles (EVs) also require energy storage devices that can operate over a wide temperature range (i.e., -40 to +70 C), while still providing high power capability and long life. Currently, the state-of-the-art lithium-ion system has been demonstrated to operate over a wide range of temperatures (-30 to +40 C); however, the rate capability at the lower temperatures is very poor. These limitations at very low temperatures are due to poor electrolyte conductivity, poor lithium intercalation kinetics over the electrode surface layers, and poor ionic diffusion in the electrode bulk. Two wide-operating-temperature-range electrolytes have been developed based on advances involving lithium hexafluorophosphate-based solutions in carbonate and carbonate + ester solvent blends, which have been further optimized in the context of the technology and targeted applications. The approaches employed include further optimization of electrolytes containing methyl propionate (MP) and ethyl butyrate (EB), which are effective co-solvents, to widen the operating temperature range beyond the baseline systems. Attention was focused on further optimizing ester-based electrolyte formulations that have exhibited the best performance at temperatures ranging from -60 to +60 C, with an emphasis upon improving the rate capability at -20 to -40 C. This was accomplished by increasing electrolyte salt concentration to 1.20M and increasing the ester content to 60 percent by volume to increase the ionic conductivity at low temperatures. Two JPL-developed electrolytes 1.20M LiPF6 in EC+EMC+MP (20:20:60 v/v %) and 1.20M LiPF6 in EC+EMC+EB (20:20:60 v/v %) operate effectively over a wide temperature range in MCMB-LiNiCoAlO2 and Li4Ti5O12-LiNi-CoAlO2 prototype cells. These electrolytes have enabled high rate performance at low temperature (i.e., up to 2.0C rates at -50 C and 5.0C rates at -40 C), and good cycling performance over a wide temperature range (i.e., from -40 to +70 C). Current efforts are focused upon improving the high temperature resilience of the methyl propionatebased system through the use of electrolyte additives, which are envisioned to improve the nature of the solid electrolyte interphase (SEI) layers.

Towards High-Performance Aqueous Sodium-Ion Batteries: Stabilizing the Solid/Liquid Interface for NASICON-Type Na2 VTi(PO4 )3 using Concentrated Electrolytes.

PubMed

Zhang, Huang; Jeong, Sangsik; Qin, Bingsheng; Vieira Carvalho, Diogo; Buchholz, Daniel; Passerini, Stefano

2018-04-25

Aqueous Na-ion batteries may offer a solution to the cost and safety issues of high-energy batteries. However, substantial challenges remain in the development of electrode materials and electrolytes enabling high performance and long cycle life. Herein, we report the characterization of a symmetric Na-ion battery with a NASICON-type Na 2 VTi(PO 4 ) 3 electrode material in conventional aqueous and "water-in-salt" electrolytes. Extremely stable cycling performance for 1000 cycles at a high rate (20 C) is found with the highly concentrated aqueous electrolytes owing to the formation of a resistive but protective interphase between the electrode and electrolyte. These results provide important insight for the development of aqueous Na-ion batteries with stable long-term cycling performance for large-scale energy storage. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Role of Cations on the Performance of Lithium Ion Batteries: A Quantitative Analytical Approach.

PubMed

Nowak, Sascha; Winter, Martin

2018-02-20

Lithium ion batteries are nowadays the state-of-the-art power sources for portable electronic devices and the most promising candidate for energy storage in large-size batteries, e.g., pure and hybrid vehicles. However, the degradation of the cell components minimizes both storage and operation lifetime (calendar and cycle life), which is called aging. Due to the numerous different aging effects, in either the single constituents or their interactions with each other, many reports about methodologies and techniques, both electrochemical and analytical, can be found in the literature. However, quantitative data about the degradation effects were seldom stated. One important effect is the cation distribution and migration during operation. Metal dissolution and metal migration of the cathode and the corresponding deposition of these metals on the graphitic anode are known harmful degradation effects, especially for the formed solid electrolyte interphase on the surface of the anode. Depending on the applied cell chemistries and therefore the cathode material, different mechanisms were reported so far. For lithium manganese oxide based cells, the acidification of the electrolyte due to composition of the conduction salt is attributed as the main source of metal migration. Due to subsequent loss of manganese from the cathode, the overall performance of the cell is seriously impaired. Based on the obtained observations, this degradation mechanism was adapted to lithium nickel cobalt manganese based cells as main cause of the capacity fading. However, with the help a developed total X-ray fluorescence method and additional surface and electrolyte investigations, the proposed HF based mechanism was disproven. Instead, the migration was directly associated with material defects or mechanical spalling of the particles. Furthermore, with the obtained quantitative data of the migrated transition metals on the anode and separator, the contribution on the capacity fade was determined. It ranged only the ‰ region and could therefore be excluded as the main source of the capacity in these lithium ion batteries. Nevertheless, the oxidation state of the cations is hardly accessible; but would provide further information about the exact migrating mechanisms. In addition, lithium can be "lost" or immobilized during charge/discharge and is therefore no longer available as an electrochemically active cation. For example, the formation, reformation, and growth of the solid electrolyte interphase and cathode electrolyte interphase leads to an increased active lithium loss during cycling. The investigations on this topic are frequently reported in literature; however, quantitative data on the actual lithium distribution throughout the cell are relatively few. Furthermore, the exact amount of lost lithium in the in the respective interphases is so far not available. In order to determine quantitatively the lithium distribution within the cell, inductively coupled plasma-based method was applied. For laboratory test cells, the lithium that was lost to the housing of the cell was 32 times higher than that for pouch bag cells. Furthermore, the determined concentration of lithium in the interphases ranged only from 2 to 4%. However, the investigations need to be repeated with isotope labeled material ( 6 Li) in order to obtain statements that are more precise.

Bubble-Sheet-Like Interface Design with an Ultrastable Solid Electrolyte Layer for High-Performance Dual-Ion Batteries.

PubMed

Qin, Panpan; Wang, Meng; Li, Na; Zhu, Haili; Ding, Xuan; Tang, Yongbing

2017-05-01

In this work, a bubble-sheet-like hollow interface design on Al foil anode to improve the cycling stability and rate performance of aluminum anode based dual-ion battery is reported, in which, a carbon-coated hollow aluminum anode is used as both anode materials and current collector. This anode structure can guide the alloying position inside the hollow nanospheres, and also confine the alloy sizes within the hollow nanospheres, resulting in significantly restricted volumetric expansion and ultrastable solid electrolyte interface (SEI). As a result, the battery demonstrates an excellent long-term cycling stability within 1500 cycles with ≈99% capacity retention at 2 C. Moreover, this cell displays an energy density of 169 Wh kg -1 even at high power density of 2113 W kg -1 (10 C, charge and discharge within 6 min), which is much higher than most of conventional lithium ion batteries. The interfacial engineering strategy shown in this work to stabilize SEI layer and control the alloy forming position could be generalized to promote the research development of metal anodes based battery systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel Slurry Electrolyte Containing Lithium Metasilicate for High Electrochemical Performance of a 5 V Cathode.

PubMed

Ren, Yonghuan; Mu, Daobin; Wu, Feng; Wu, Borong

2015-10-21

We report a novel slurry electrolyte with ultrahigh concentration of insoluble inorganic lithium metasilicate (Li2SiO3) that is exploited for lithium ion batteries to combine the merits of solid and liquid electrolytes. The safety, conductivity, and anodic and storage stabilities of the eletrolyte are examined, which are all enhanced compared to a base carbonate electrolyte. The compatibility of the elecrolyte with a LiNi0.5Mn1.5O4 cathode is evaluated under high voltage. A discharge capacity of 173.8 mAh g(-1) is still maintained after 120 cycles, whereas it is only 74.9 mAh g(-1) in the base electrolyte. Additionally, the rate capability of the LiNi0.5Mn1.5O4 cathode is also improved with reduced electrode polarization. TEM measurements indicate that the electrode interface is modified by Li2SiO3 with a thinner solid electrolyte interphase film. Density functional theory computations demonstrate that LiPF6 is stabilized against its decomposition by Li2SiO3. A possible path for the reaction between PF5 and Li2SiO3 is also proposed by deducing the transition states involved in the process using the DFT method.

Demonstration of an electrochemical liquid cell for operando transmission electron microscopy observation of the lithiation/delithiation behavior of Si nanowire battery anodes.

PubMed

Gu, Meng; Parent, Lucas R; Mehdi, B Layla; Unocic, Raymond R; McDowell, Matthew T; Sacci, Robert L; Xu, Wu; Connell, Justin Grant; Xu, Pinghong; Abellan, Patricia; Chen, Xilin; Zhang, Yaohui; Perea, Daniel E; Evans, James E; Lauhon, Lincoln J; Zhang, Ji-Guang; Liu, Jun; Browning, Nigel D; Cui, Yi; Arslan, Ilke; Wang, Chong-Min

2013-01-01

Over the past few years, in situ transmission electron microscopy (TEM) studies of lithium ion batteries using an open-cell configuration have helped us to gain fundamental insights into the structural and chemical evolution of the electrode materials in real time. In the standard open-cell configuration, the electrolyte is either solid lithium oxide or an ionic liquid, which is point-contacted with the electrode. This cell design is inherently different from a real battery, where liquid electrolyte forms conformal contact with electrode materials. The knowledge learnt from open cells can deviate significantly from the real battery, calling for operando TEM technique with conformal liquid electrolyte contact. In this paper, we developed an operando TEM electrochemical liquid cell to meet this need, providing the configuration of a real battery and in a relevant liquid electrolyte. To demonstrate this novel technique, we studied the lithiation/delithiation behavior of single Si nanowires. Some of lithiation/delithation behaviors of Si obtained using the liquid cell are consistent with the results from the open-cell studies. However, we also discovered new insights different from the open cell configuration-the dynamics of the electrolyte and, potentially, a future quantitative characterization of the solid electrolyte interphase layer formation and structural and chemical evolution.

Copper Antimonide Nanowire Array Lithium Ion Anodes Stabilized by Electrolyte Additives.

PubMed

Jackson, Everett D; Prieto, Amy L

2016-11-09

Nanowires of electrochemically active electrode materials for lithium ion batteries represent a unique system that allows for intensive investigations of surface phenomena. In particular, highly ordered nanowire arrays produced by electrodeposition into anodic aluminum oxide templates can lead to new insights into a material's electrochemical performance by providing a high-surface-area electrode with negligible volume expansion induced pulverization. Here we show that for the Li-Cu x Sb ternary system, stabilizing the surface chemistry is the most critical factor for promoting long electrode life. The resulting solid electrolyte interphase is analyzed using a mix of electron microscopy, X-ray photoelectron spectroscopy, and lithium ion battery half-cell testing to provide a better understanding of the importance of electrolyte composition on this multicomponent alloy anode material.

Interaction of CuS and sulfur in Li-S battery system

DOE PAGES

Sun, Ke; Su, Dong; Zhang, Qing; ...

2015-10-27

Lithium-Sulfur (Li-S) battery has been a subject of intensive research in recent years due to its potential to provide much higher energy density and lower cost than the current state of the art lithiumion battery technology. In this work, we have investigated Cupric Sulfide (CuS) as a capacitycontributing conductive additive to the sulfur electrode in a Li-S battery. Galvanostatic charge/discharge cycling has been used to compare the performance of both sulfur electrodes and S:CuS hybrid electrodes with various ratios. We found that the conductive CuS additive enhanced the utilization of the sulfur cathode under a 1C rate discharge. However, undermore » a C/10 discharge rate, S:CuS hybrid electrodes exhibited lower sulfur utilization in the first discharge and faster capacity decay in later cycles than a pure sulfur electrode due to the dissolution of CuS. The CuS dissolution is found to be the result of strong interaction between the soluble low order polysulfide Li 2S 3 and CuS. As a result, we identified the presence of conductive copper-containing sulfides at the cycled lithium anode surface, which may degrade the effectiveness of the passivation function of the solid-electrolyte-interphase (SEI) layer, accounting for the poor cycling performance of the S:CuS hybrid cells at low rate.« less

Graphene Oxides Used as a New "Dual Role" Binder for Stabilizing Silicon Nanoparticles in Lithium-Ion Battery.

PubMed

Shan, Changsheng; Wu, Kaifeng; Yen, Hung-Ju; Narvaez Villarrubia, Claudia; Nakotte, Tom; Bo, Xiangjie; Zhou, Ming; Wu, Gang; Wang, Hsing-Lin

2018-05-09

For the first time, we report that graphene oxide (GO) can be used as a new "dual-role" binder for Si nanoparticles (SiNPs)-based lithium-ion batteries (LIBs). GO not only provides a graphene-like porous 3D framework for accommodating the volume changes of SiNPs during charging/discharging cycles, but also acts as a polymer-like binder that forms strong chemical bonds with SiNPs through its Si-OH functional groups to trap and stabilize SiNPs inside the electrode. Leveraging this unique dual-role of GO binder, we fabricated GO/SiNPs electrodes with remarkably improved performances as compared to using the conventional polyvinylidene fluoride (PVDF) binder. Specifically, the GO/SiNPs electrode showed a specific capacity of 2400 mA h g -1 at the 50th cycle and 2000 mA h g -1 at the 100th cycle, whereas the SiNPs/PVDF electrode only showed 456 mAh g -1 at the 50th cycle and 100 mAh g -1 at 100th cycle. Moreover, the GO/SiNPs film maintained its structural integrity and formed a stable solid-electrolyte interphase (SEI) film after 100 cycles. These results, combined with the well-established facile synthesis of GO, indicate that GO can be an excellent binder for developing high performance Si-based LIBs.

Simultaneous Purification and Perforation of Low-Grade Si Sources for Lithium-Ion Battery Anode.

PubMed

Jin, Yan; Zhang, Su; Zhu, Bin; Tan, Yingling; Hu, Xiaozhen; Zong, Linqi; Zhu, Jia

2015-11-11

Silicon is regarded as one of the most promising candidates for lithium-ion battery anodes because of its abundance and high theoretical capacity. Various silicon nanostructures have been heavily investigated to improve electrochemical performance by addressing issues related to structure fracture and unstable solid-electrolyte interphase (SEI). However, to further enable widespread applications, scalable and cost-effective processes need to be developed to produce these nanostructures at large quantity with finely controlled structures and morphologies. In this study, we develop a scalable and low cost process to produce porous silicon directly from low grade silicon through ball-milling and modified metal-assisted chemical etching. The morphology of porous silicon can be drastically changed from porous-network to nanowire-array by adjusting the component in reaction solutions. Meanwhile, this perforation process can also effectively remove the impurities and, therefore, increase Si purity (up to 99.4%) significantly from low-grade and low-cost ferrosilicon (purity of 83.4%) sources. The electrochemical examinations indicate that these porous silicon structures with carbon treatment can deliver a stable capacity of 1287 mAh g(-1) over 100 cycles at a current density of 2 A g(-1). This type of purified porous silicon with finely controlled morphology, produced by a scalable and cost-effective fabrication process, can also serve as promising candidates for many other energy applications, such as thermoelectrics and solar energy conversion devices.

Scalable Production of the Silicon-Tin Yin-Yang Hybrid Structure with Graphene Coating for High Performance Lithium-Ion Battery Anodes.

PubMed

Jin, Yan; Tan, Yingling; Hu, Xiaozhen; Zhu, Bin; Zheng, Qinghui; Zhang, Zijiao; Zhu, Guoying; Yu, Qian; Jin, Zhong; Zhu, Jia

2017-05-10

Alloy anodes possessed of high theoretical capacity show great potential for next-generation advanced lithium-ion battery. Even though huge volume change during lithium insertion and extraction leads to severe problems, such as pulverization and an unstable solid-electrolyte interphase (SEI), various nanostructures including nanoparticles, nanowires, and porous networks can address related challenges to improve electrochemical performance. However, the complex and expensive fabrication process hinders the widespread application of nanostructured alloy anodes, which generate an urgent demand of low-cost and scalable processes to fabricate building blocks with fine controls of size, morphology, and porosity. Here, we demonstrate a scalable and low-cost process to produce a porous yin-yang hybrid composite anode with graphene coating through high energy ball-milling and selective chemical etching. With void space to buffer the expansion, the produced functional electrodes demonstrate stable cycling performance of 910 mAh g -1 over 600 cycles at a rate of 0.5C for Si-graphene "yin" particles and 750 mAh g -1 over 300 cycles at 0.2C for Sn-graphene "yang" particles. Therefore, we open up a new approach to fabricate alloy anode materials at low-cost, low-energy consumption, and large scale. This type of porous silicon or tin composite with graphene coating can also potentially play a significant role in thermoelectrics and optoelectronics applications.

4-Vinyl-1,3-Dioxolane-2-One as an Additive for Li-Ion Cells

NASA Technical Reports Server (NTRS)

Smart, Marshall; Bugga, Ratnakumar

2006-01-01

Electrolyte additive 4-vinyl-1,3-dioxolane-2-one has been found to be promising for rechargeable lithium-ion electrochemical cells. This and other additives, along with advanced electrolytes comprising solutions of LiPF6 in various mixtures of carbonate solvents, have been investigated in a continuing effort to improve the performances of rechargeable lithium-ion electrochemical cells, especially at low temperatures. In contrast to work by other researchers who have investigated the use of this additive to improve the high-temperature resilience of Li-ion cells, the current work involves the incorporation of 4-vinyl-1,3-dioxolane-2-one into quaternary carbonate electrolyte mixtures, previously optimized for low-temperature applications, resulting in improved low-temperature performance. The benefit afforded by 4-vinyl-1,3- dioxolane-2-one can be better understood in the light of relevant information from a number of prior NASA Tech Briefs articles about electrolytes and additives for such cells. To recapitulate: The loss of performance with decreasing temperature is attributable largely to a decrease of ionic conductivity and the increase in viscosity of the electrolyte. What is needed to extend the lower limit of operating temperature is a stable electrolyte solution with relatively small lowtemperature viscosity, a large electric permittivity, adequate coordination behavior, and appropriate ranges of solubilities of liquid and salt constituents. Whether the anode is made of graphitic or non-graphitic carbon, a film on the surface of the anode acts as a solid/electrolyte interface (SEI), the nature of which is critical to low-temperature performance. Desirably, the surface film should exert a chemically protective (passivating) effect on both the anode and the electrolyte, yet should remain conductive to lithium ions to facilitate intercalation and de-intercalation of the ions into and out of the carbon during discharging and charging, respectively. The additives investigated previously include alkyl pyrocarbonates. Those additives help to improve low-temperature performances by giving rise to the formation of SEIs having desired properties. The formation of the SEIs is believed to be facilitated by products (e.g., CO2) of the decomposition of these additives. These decomposition products are believed to react to form Li2CO3-based films on the carbon electrodes. The present additive, 4-vinyl-1,3-dioxolane-2-one, also helps to improve lowtemperature performance by contributing to the formation of SEIs having desired properties, but probably in a different manner: It is believed that, as part of the decomposition process, the compound polymerizes on the surfaces of carbon electrodes.

The Electrochemistry of Fe 3 O 4 /Polypyrrole Composite Electrodes in Lithium-Ion Cells: The Role of Polypyrrole in Capacity Retention

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruck, Andrea M.; Gannett, Cara N.; Bock, David C.

In two series of magnetite (Fe 3O4) composite electrodes, one group with and one group without added carbon, containing varying quantities of polypyrrole (PPy), and a non-conductive polyvinylidene difluoride (PVDF) binder were constructed and then analyzed using electrochemical and spectroscopic techniques. Galvanostatic cycling and alternating current (AC) impedance measurements were used in tandem to measure delivered capacity, capacity retention, and the related impedance at various stages of discharge and charge. Further, the reversibility of Fe 3O 4 to iron metal (Fe0) conversion observed during discharge was quantitatively assessed ex-situ using X-ray Absorption Spectroscopy (XAS). The Fe 3O 4 composite containingmore » the largest weight fraction of PPy (20 wt%) with added carbon demonstrated reduced irreversible capacity on initial cycles and improved cycling stability over 50 cycles, attributed to decreased reaction with the electrolyte in the presence of PPy. Our study illustrated the beneficial role of PPy addition to Fe 3O 4 based electrodes was not strongly related to improved electrical conductivity, but rather to improved ion transport related to the formation of a more favorable surface electrolyte interphase (SEI).« less

The Electrochemistry of Fe 3 O 4 /Polypyrrole Composite Electrodes in Lithium-Ion Cells: The Role of Polypyrrole in Capacity Retention

DOE PAGES

Bruck, Andrea M.; Gannett, Cara N.; Bock, David C.; ...

2016-12-15

In two series of magnetite (Fe 3O4) composite electrodes, one group with and one group without added carbon, containing varying quantities of polypyrrole (PPy), and a non-conductive polyvinylidene difluoride (PVDF) binder were constructed and then analyzed using electrochemical and spectroscopic techniques. Galvanostatic cycling and alternating current (AC) impedance measurements were used in tandem to measure delivered capacity, capacity retention, and the related impedance at various stages of discharge and charge. Further, the reversibility of Fe 3O 4 to iron metal (Fe0) conversion observed during discharge was quantitatively assessed ex-situ using X-ray Absorption Spectroscopy (XAS). The Fe 3O 4 composite containingmore » the largest weight fraction of PPy (20 wt%) with added carbon demonstrated reduced irreversible capacity on initial cycles and improved cycling stability over 50 cycles, attributed to decreased reaction with the electrolyte in the presence of PPy. Our study illustrated the beneficial role of PPy addition to Fe 3O 4 based electrodes was not strongly related to improved electrical conductivity, but rather to improved ion transport related to the formation of a more favorable surface electrolyte interphase (SEI).« less

Modeling the degradation mechanisms of C6/LiFePO4 batteries

NASA Astrophysics Data System (ADS)

Li, Dongjiang; Danilov, Dmitri L.; Zwikirsch, Barbara; Fichtner, Maximilian; Yang, Yong; Eichel, Rüdiger-A.; Notten, Peter H. L.

2018-01-01

A fundamental electrochemical model is developed, describing the capacity fade of C6/LiFePO4 batteries as a function of calendar time and cycling conditions. At moderate temperatures the capacity losses are mainly attributed to Li immobilization in Solid-Electrolyte-Interface (SEI) layers at the anode surface. The SEI formation model presumes the availability of an outer and inner SEI layers. Electron tunneling through the inner SEI layer is regarded as the rate-determining step. The model also includes high temperature degradation. At elevated temperatures, iron dissolution from the positive electrode and the subsequent metal sedimentation on the negative electrode influence the capacity loss. The SEI formation on the metal-covered graphite surface is faster than the conventional SEI formation. The model predicts that capacity fade during storage is lower than during cycling due to the generation of SEI cracks induced by the volumetric changes during (dis)charging. The model has been validated by cycling and calendar aging experiments and shows that the capacity loss during storage depends on the storage time, the State-of-Charge (SoC), and temperature. The capacity losses during cycling depend on the cycling current, cycling time, temperature and cycle number. All these dependencies can be explained by the single model presented in this paper.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strelcov, Evgheni; Cothren, Joshua E.; Leonard, Donovan N.

Progress in rational engineering of Li-ion batteries requires better understanding of the electrochemical processes and accompanying transformations in the electrode materials on multiple length scales. In spite of recent progress in utilizing transmission electron microscopy (TEM) to analyze these materials, in situ scanning electron microscopy (SEM) was mostly overlooked as a powerful tool that allows probing these phenomena on the nano and mesoscale. In this paper, we report on in situ SEM study of lithiation in a V 2O 5-based single-nanobelt battery with ionic liquid electrolyte. Coupled with cyclic voltammetry measurements, in situ SEM revealed the peculiarities of subsurface intercalation,more » formation of solid-electrolyte interface (SEI) and electromigration of liquid. We observed that single-crystalline vanadia nanobelts do not undergo large-scale amorphization or fracture during electrochemical cycling, but rather transform topochemically with only a slight shape distortion. Lastly, the SEI layer seems to have significant influence on the lithium ion diffusion and overall capacity of the single-nanobelt battery.« less

Identification and formation mechanism of individual degradation products in lithium-ion batteries studied by liquid chromatography/electrospray ionization mass spectrometry and atmospheric solid analysis probe mass spectrometry.

PubMed

Takeda, Sahori; Morimura, Wataru; Liu, Yi-Hung; Sakai, Tetsuo; Saito, Yuria

2016-08-15

Improvement of lithium ion batteries (LIBs) in terms of performance and robustness requires good understanding of the reaction processes. The analysis of the individual degradation products in LIB electrolytes and on the surface of the electrodes provides vital information in this regard. In this study, mass spectrometric analytical methods were utilized for the identification of the individual degradation products. The degradation products in the electrolytes recovered from cycle-tested cells were separated by liquid chromatography (LC) and their mass spectrometric analysis was conducted by electrospray ionization mass spectrometry (ESI-MS). For identification of degradation products on the surface of electrodes, atmospheric solid analysis probe (ASAP)-MS analysis was conducted by time-of-flight mass spectrometry with an ASAP probe and an atmospheric pressure chemical ionization source. The degradation products in the electrolytes, namely carbonate oligomers and organophosphates, were identified simultaneously by LC/ESI-MS. Their formation mechanisms were estimated, which explain their different compositions at different temperatures. One degradation product was found on the anode surface by ASAP-MS, and its formation mechanism was explained similarly to those in the electrolyte. The results suggest that the electrolyte degradation is correlated with the formation of a solid electrolyte interphase, which is an important factor in the performance of LIBs. We expect that further investigation of the degradation products by LC/ESI-MS and ASAP-MS will be helpful for studying their degradation processes in LIBs. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Materials Research Society (MRS) 2014 Fall Meeting, Boston, MA on November 30 December 5, 2014

DTIC Science & Technology

2015-12-18

10.1557/opl.2015.216, Published online by Cambridge University Press 03 Mar 2015 Lithium - ion Diffusion in Solid Electrolyte Interface (SEI) Predicted by...challenges; Innovation and Inclusion: What It Takes to Move Diversity Forward, Vern Myers, Esq., principal of Vern Myers Consulting Group, LLC, engaged...bacteriophage to synthesize radically novel electronic and battery devices at protein and semiconductor interfaces. Ashutosh Chilkoti (Duke Univ

An Ultrahigh Capacity Graphite/Li 2S Battery with Holey-Li 2S Nanoarchitectures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Fangmin; Noh, Hyungjun; Lee, Hongkyung

The pairing of high-capacity Li 2S cathode (1166 mAh g -1) and lithium-free anode (LFA) provides an unparalleled potential in developing safe and energy-dense next-generation secondary batteries. However, the low utilization of the Li 2S cathode and the lack of electrolytes compatible to both electrodes are impeding the development. Here, a novel graphite/Li 2S battery system, which features a self-assembled, holey-Li 2S nanoarchitecture and a stable solid electrolyte interface (SEI) on the graphite electrode, is reported. The holey structure on Li 2S is beneficial in decomposing Li 2S at the first charging process due to the enhanced Li ion extractionmore » and transfer from the Li 2S to the electrolyte. In addition, the concentrated dioxolane (DOL)-rich electrolyte designed lowers the irreversible capacity loss for SEI formation. By using the combined strategies, the graphite/holey-Li 2S battery delivers an ultrahigh discharge capacity of 810 mAh g -1 at 0.1 C (based on the mass of Li 2S) and of 714 mAh g -1 at 0.2 C. Moreover, it exhibits a reversible capacity of 300 mAh g -1 after a record lifecycle of 600 cycles at 1 C. These results suggest the great potential of the designed LFA/holey-Li 2S batteries for practical use.« less

An Ultrahigh Capacity Graphite/Li 2S Battery with Holey-Li 2S Nanoarchitectures

DOE PAGES

Ye, Fangmin; Noh, Hyungjun; Lee, Hongkyung; ...

2018-05-07

The pairing of high-capacity Li 2S cathode (1166 mAh g -1) and lithium-free anode (LFA) provides an unparalleled potential in developing safe and energy-dense next-generation secondary batteries. However, the low utilization of the Li 2S cathode and the lack of electrolytes compatible to both electrodes are impeding the development. Here, a novel graphite/Li 2S battery system, which features a self-assembled, holey-Li 2S nanoarchitecture and a stable solid electrolyte interface (SEI) on the graphite electrode, is reported. The holey structure on Li 2S is beneficial in decomposing Li 2S at the first charging process due to the enhanced Li ion extractionmore » and transfer from the Li 2S to the electrolyte. In addition, the concentrated dioxolane (DOL)-rich electrolyte designed lowers the irreversible capacity loss for SEI formation. By using the combined strategies, the graphite/holey-Li 2S battery delivers an ultrahigh discharge capacity of 810 mAh g -1 at 0.1 C (based on the mass of Li 2S) and of 714 mAh g -1 at 0.2 C. Moreover, it exhibits a reversible capacity of 300 mAh g -1 after a record lifecycle of 600 cycles at 1 C. These results suggest the great potential of the designed LFA/holey-Li 2S batteries for practical use.« less

Transforming from planar to three-dimensional lithium with flowable interphase for solid lithium metal batteries

PubMed Central

Liu, Yayuan; Lin, Dingchang; Jin, Yang; Liu, Kai; Tao, Xinyong; Zhang, Qiuhong; Zhang, Xiaokun; Cui, Yi

2017-01-01

Solid-state lithium (Li) metal batteries are prominent among next-generation energy storage technologies due to their significantly high energy density and reduced safety risks. Previously, solid electrolytes have been intensively studied and several materials with high ionic conductivity have been identified. However, there are still at least three obstacles before making the Li metal foil-based solid-state systems viable, namely, high interfacial resistance at the Li/electrolyte interface, low areal capacity, and poor power output. The problems are addressed by incorporating a flowable interfacial layer and three-dimensional Li into the system. The flowable interfacial layer can accommodate the interfacial fluctuation and guarantee excellent adhesion at all time, whereas the three-dimensional Li significantly reduces the interfacial fluctuation from the whole electrode level (tens of micrometers) to local scale (submicrometer) and also decreases the effective current density for high-capacity and high-power operations. As a consequence, both symmetric and full-cell configurations can achieve greatly improved electrochemical performances in comparison to the conventional Li foil, which are among the best reported values in the literature. Noticeably, solid-state full cells paired with high–mass loading LiFePO4 exhibited, at 80°C, a satisfactory specific capacity even at a rate of 5 C (110 mA·hour g−1) and a capacity retention of 93.6% after 300 cycles at a current density of 3 mA cm−2 using a composite solid electrolyte middle layer. In addition, when a ceramic electrolyte middle layer was adopted, stable cycling with greatly improved capacity could even be realized at room temperature. PMID:29062894

Transforming from planar to three-dimensional lithium with flowable interphase for solid lithium metal batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yayuan; Lin, Dingchang; Jin, Yang

Solid-state lithium (Li) metal batteries are prominent among next-generation energy storage technologies due to their significantly high energy density and reduced safety risks. Previously, solid electrolytes have been intensively studied and several materials with high ionic conductivity have been identified. However, there are still at least three obstacles before making the Li metal foil-based solid-state systems viable, namely, high interfacial resistance at the Li/electrolyte interface, low areal capacity, and poor power output. The problems are addressed by incorporating a flowable interfacial layer and three-dimensional Li into the system. The flowable interfacial layer can accommodate the interfacial fluctuation and guarantee excellentmore » adhesion at all time, whereas the three-dimensional Li significantly reduces the interfacial fluctuation from the whole electrode level (tens of micrometers) to local scale (submicrometer) and also decreases the effective current density for high-capacity and high-power operations. As a consequence, both symmetric and full-cell configurations can achieve greatly improved electrochemical performances in comparison to the conventional Li foil, which are among the best reported values in the literature. Noticeably, solid-state full cells paired with high–mass loading LiFePO4 exhibited, at 80°C, a satisfactory specific capacity even at a rate of 5 C (110 mA·hour g -1) and a capacity retention of 93.6% after 300 cycles at a current density of 3 mA cm -2 using a composite solid electrolyte middle layer. In addition, when a ceramic electrolyte middle layer was adopted, stable cycling with greatly improved capacity could even be realized at room temperature.« less

Transforming from planar to three-dimensional lithium with flowable interphase for solid lithium metal batteries

DOE PAGES

Liu, Yayuan; Lin, Dingchang; Jin, Yang; ...

2017-10-01

Solid-state lithium (Li) metal batteries are prominent among next-generation energy storage technologies due to their significantly high energy density and reduced safety risks. Previously, solid electrolytes have been intensively studied and several materials with high ionic conductivity have been identified. However, there are still at least three obstacles before making the Li metal foil-based solid-state systems viable, namely, high interfacial resistance at the Li/electrolyte interface, low areal capacity, and poor power output. The problems are addressed by incorporating a flowable interfacial layer and three-dimensional Li into the system. The flowable interfacial layer can accommodate the interfacial fluctuation and guarantee excellentmore » adhesion at all time, whereas the three-dimensional Li significantly reduces the interfacial fluctuation from the whole electrode level (tens of micrometers) to local scale (submicrometer) and also decreases the effective current density for high-capacity and high-power operations. As a consequence, both symmetric and full-cell configurations can achieve greatly improved electrochemical performances in comparison to the conventional Li foil, which are among the best reported values in the literature. Noticeably, solid-state full cells paired with high–mass loading LiFePO4 exhibited, at 80°C, a satisfactory specific capacity even at a rate of 5 C (110 mA·hour g -1) and a capacity retention of 93.6% after 300 cycles at a current density of 3 mA cm -2 using a composite solid electrolyte middle layer. In addition, when a ceramic electrolyte middle layer was adopted, stable cycling with greatly improved capacity could even be realized at room temperature.« less

Enhanced cycling performance of a Li metal anode in a dimethylsulfoxide-based electrolyte using highly concentrated lithium salt for a lithium-oxygen battery

NASA Astrophysics Data System (ADS)

Togasaki, Norihiro; Momma, Toshiyuki; Osaka, Tetsuya

2016-03-01

Stable charge-discharge cycling behavior for a lithium metal anode in a dimethylsulfoxide (DMSO)-based electrolyte is strongly desired of lithium-oxygen batteries, because the Li anode is rapidly exhausted as a result of side reactions during cycling in the DMSO solution. Herein, we report a novel electrolyte design for enhancing the cycling performance of Li anodes by using a highly concentrated DMSO-based electrolyte with a specific Li salt. Lithium nitrate (LiNO3), which forms an inorganic compound (Li2O) instead of a soluble product (Li2S) on a lithium surface, exhibits a >20% higher coulombic efficiency than lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium perchlorate, regardless of the loading current density. Moreover, the stable cycling of Li anodes in DMSO-based electrolytes depends critically on the salt concentration. The highly concentrated electrolyte 4.0 M LiNO3/DMSO displays enhanced and stable cycling performance comparable to that of carbonate-based electrolytes, which had not previously been achieved. We suppose this enhancement is due to the absence of free DMSO solvent in the electrolyte and the promotion of the desolvation of Li ions on the solid electrolyte interphase surface, both being consequences of the unique structure of the electrolyte.

A novel electrolyte salt additive for lithium-ion batteries with voltages greater than 4.7 V

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yunchao; Wan, Shun; Veith, Gabriel M.

2016-11-07

Here, lithium bis(2-methyl-2-fluoromalonato)borate (LiBMFMB), as an additive in conventional electrolyte for LiNi 0.5Mn 1.5O 4, exhibits improved coulombic efficiencies and cycling stability. Cyclic voltammograms indicate the cells with additive form good SEIs during the first cycle whereas no additive cell needs more cycles to form a functional SEI. XPS reveals LiBMFMB could reduce the decomposition of LiPF 6 salt and solvents, resulting in thinner SEI.

Magnesium Hydride Nanoparticles Self-Assembled on Graphene as Anode Material for High-Performance Lithium-Ion Batteries.

PubMed

Zhang, Baoping; Xia, Guanglin; Sun, Dalin; Fang, Fang; Yu, Xuebin

2018-04-24

MgH 2 nanoparticles (NPs) uniformly anchored on graphene (GR) are fabricated based on a bottom-up self-assembly strategy as anode materials for lithium-ion batteries (LIBs). Monodisperse MgH 2 NPs with an average particle size of ∼13.8 nm are self-assembled on the flexible GR, forming interleaved MgH 2 /GR (GMH) composite architectures. Such nanoarchitecture could effectively constrain the aggregation of active materials, buffer the strain of volume changes, and facilitate the electron/lithium ion transfer of the whole electrode, leading to a significant enhancement of the lithium storage capacity of the GMH composite. Furthermore, the performances of GMH composite as anode materials for LIBs are enabled largely through robust interfacial interactions with poly(methyl methacrylate) (PMMA) binder, which plays multifunctional roles in forming a favorable solid-electrolyte interphase (SEI) film, alleviating the volume expansion and detachment of active materials, and maintaining the structural integrity of the whole electrode. As a result, these synergistic effects endow the obtained GMH composite with a significantly enhanced reversible capacity and cyclability as well as a good rate capability. The GMH composite with 50 wt % MgH 2 delivers a high reversible capacity of 946 mA h g -1 at 100 mA g -1 after 100 cycles and a capacity of 395 mAh g -1 at a high current density of 2000 mA g -1 after 1000 cycles.

Evolution of LiFePO4 thin films interphase with electrolyte

NASA Astrophysics Data System (ADS)

Dupré, N.; Cuisinier, M.; Zheng, Y.; Fernandez, V.; Hamon, J.; Hirayama, M.; Kanno, R.; Guyomard, D.

2018-04-01

Many parameters may control the growth and the characteristics of the interphase, such as surface structure and morphology, structural defects, grain boundaries, surface reactions, etc. However, polycrystalline surfaces contain these parameters simultaneously, resulting in a quite complicated system to study. Working with model electrode surfaces using crystallographically oriented crystalline thin films appears as a novel and unique approach to understand contributions of preferential orientation and rugosity of the surface. In order to rebuild the interphase architecture along electrochemical cycling, LiFePO4 epitaxial films offering ideal 2D (100) interfaces are here investigated through the use of non-destructive depth profiling by Angular Resolved X-ray Photoelectron Spectroscopy (ARXPS). The composition and structure of the interphase is then monitored upon cycling for samples stopped at the end of charge and discharge for various numbers of cycles, and discussed in the light of combined XPS and X-ray reflectivity (XRR) measurements. Such an approach allows describing the interphase evolution on a specific model LiFePO4 crystallographic orientation and helps understanding the nature and evolution of the LiFePO4/electrolyte interphase forming on the surface of LiFePO4 poly-crystalline powder.

Enabling electrolyte compositions for columnar silicon anodes in high energy secondary batteries

NASA Astrophysics Data System (ADS)

Piwko, Markus; Thieme, Sören; Weller, Christine; Althues, Holger; Kaskel, Stefan

2017-09-01

Columnar silicon structures are proven as high performance anodes for high energy batteries paired with low (sulfur) or high (nickel-cobalt-aluminum oxide, NCA) voltage cathodes. The introduction of a fluorinated ether/sulfolane solvent mixture drastically improves the capacity retention for both battery types due to an improved solid electrolyte interface (SEI) on the surface of the silicon electrode which reduces irreversible reactions normally causing lithium loss and rapid capacity fading. For the lithium silicide/sulfur battery cycling stability is significantly improved as compared to a frequently used reference electrolyte (DME/DOL) reaching a constant coulombic efficiency (CE) as high as 98%. For the silicon/NCA battery with higher voltage, the addition of only small amounts of fluoroethylene carbonate (FEC) to the novel electrolyte leads to a stable capacity over at least 50 cycles and a CE as high as 99.9%. A high volumetric energy density close to 1000 Wh l-1 was achieved with the new electrolyte taking all inactive components of the stack into account for the estimation.

Fluorinated reduced graphene oxide as a protective layer on the metallic lithium for application in the high energy batteries.

PubMed

Bobnar, Jernej; Lozinšek, Matic; Kapun, Gregor; Njel, Christian; Dedryvère, Rémi; Genorio, Boštjan; Dominko, Robert

2018-04-11

Metallic lithium is considered to be one of the most promising anode materials since it offers high volumetric and gravimetric energy densities when combined with high-voltage or high-capacity cathodes. However, the main impediment to the practical applications of metallic lithium is its unstable solid electrolyte interface (SEI), which results in constant lithium consumption for the formation of fresh SEI, together with lithium dendritic growth during electrochemical cycling. Here we present the electrochemical performance of a fluorinated reduced graphene oxide interlayer (FGI) on the metallic lithium surface, tested in lithium symmetrical cells and in combination with two different cathode materials. The FGI on the metallic lithium exhibit two roles, firstly it acts as a Li-ion conductive layer and electronic insulator and secondly, it effectively suppresses the formation of high surface area lithium (HSAL). An enhanced electrochemical performance of the full cell battery system with two different types of cathodes was shown in the carbonate or in the ether based electrolytes. The presented results indicate a potential application in future secondary Li-metal batteries.

In situ SEM Study of Lithium Intercalation in individual V 2O 5 Nanowires

DOE PAGES

Strelcov, Evgheni; Cothren, Joshua E.; Leonard, Donovan N.; ...

2015-01-08

Progress in rational engineering of Li-ion batteries requires better understanding of the electrochemical processes and accompanying transformations in the electrode materials on multiple length scales. In spite of recent progress in utilizing transmission electron microscopy (TEM) to analyze these materials, in situ scanning electron microscopy (SEM) was mostly overlooked as a powerful tool that allows probing these phenomena on the nano and mesoscale. In this paper, we report on in situ SEM study of lithiation in a V 2O 5-based single-nanobelt battery with ionic liquid electrolyte. Coupled with cyclic voltammetry measurements, in situ SEM revealed the peculiarities of subsurface intercalation,more » formation of solid-electrolyte interface (SEI) and electromigration of liquid. We observed that single-crystalline vanadia nanobelts do not undergo large-scale amorphization or fracture during electrochemical cycling, but rather transform topochemically with only a slight shape distortion. Lastly, the SEI layer seems to have significant influence on the lithium ion diffusion and overall capacity of the single-nanobelt battery.« less

Immobilization of Anions on Polymer Matrices for Gel Electrolytes with High Conductivity and Stability in Lithium Ion Batteries.

PubMed

Wang, Shih-Hong; Lin, Yong-Yi; Teng, Chiao-Yi; Chen, Yen-Ming; Kuo, Ping-Lin; Lee, Yuh-Lang; Hsieh, Chien-Te; Teng, Hsisheng

2016-06-15

This study reports on a high ionic-conductivity gel polymer electrolyte (GPE), which is supported by a TiO2 nanoparticle-decorated polymer framework comprising poly(acrylonitrile-co-vinyl acetate) blended with poly(methyl methacrylate), i.e. , PAVM: TiO2. High conductivity TiO2 is achieved by causing the PAVM:TiO2 polymer framework to swell in 1 M LiPF6 in carbonate solvent. Raman analysis results demonstrate that the poly(acrylonitrile) (PAN) segments and TiO2 nanoparticles strongly adsorb PF6(-) anions, thereby generating 3D percolative space-charge pathways surrounding the polymer framework for Li(+)-ion transport. The ionic conductivity of TiO2 is nearly 1 order of magnitude higher than that of commercial separator-supported liquid electrolyte (SLE). TiO2 has a high Li(+) transference number (0.7), indicating that most of the PF6(-) anions are stationary, which suppresses PF6(-) decomposition and substantially enlarges the voltage that can be applied to TiO2 (to 6.5 V vs Li/Li(+)). Immobilization of PF6(-) anions also leads to the formation of stable solid-electrolyte interface (SEI) layers in a full-cell graphite|electrolyte|LiFePO4 battery, which exhibits low SEI and overall resistances. The graphite|electrolyte|LiFePO4 battery delivers high capacity of 84 mAh g(-1) even at 20 C and presents 90% and 71% capacity retention after 100 and 1000 charge-discharge cycles, respectively. This study demonstrates a GPE architecture comprising 3D space charge pathways for Li(+) ions and suppresses anion decomposition to improve the stability and lifespan of the resulting LIBs.

Micro-sized organometallic compound of ferrocene as high-performance anode material for advanced lithium-ion batteries

NASA Astrophysics Data System (ADS)

Liu, Zhen; Feng, Li; Su, Xiaoru; Qin, Chenyang; Zhao, Kun; Hu, Fang; Zhou, Mingjiong; Xia, Yongyao

2018-01-01

An organometallic compound of ferrocene is first investigated as a promising anode for lithium-ion batteries. The electrochemical properties of ferrocene are conducted by galvanostatic charge and discharge. The ferrocene anode exhibits a high reversible capacity and great cycling stability, as well as superior rate capability. The electrochemical reaction of ferrocene is semi-reversible and some metallic Fe remains in the electrode even after delithiation. The metallic Fe formed in electrode and the stable solid electrolyte interphase should be responsible for its excellent electrochemical performance.

Glassy Metal Alloy Nanofiber Anodes Employing Graphene Wrapping Layer: Toward Ultralong-Cycle-Life Lithium-Ion Batteries.

PubMed

Jung, Ji-Won; Ryu, Won-Hee; Shin, Jungwoo; Park, Kyusung; Kim, Il-Doo

2015-07-28

Amorphous silicon (a-Si) has been intensively explored as one of the most attractive candidates for high-capacity and long-cycle-life anode in Li-ion batteries (LIBs) primarily because of its reduced volume expansion characteristic (∼280%) compared to crystalline Si anodes (∼400%) after full Li(+) insertion. Here, we report one-dimensional (1-D) electrospun Si-based metallic glass alloy nanofibers (NFs) with an optimized composition of Si60Sn12Ce18Fe5Al3Ti2. On the basis of careful compositional tailoring of Si alloy NFs, we found that Ce plays the most important role as a glass former in the formation of the metallic glass alloy. Moreover, Si-based metallic glass alloy NFs were wrapped by reduced graphene oxide sheets (specifically Si60Sn12Ce18Fe5Al3Ti2 NFs@rGO), which can prevent the direct exposure of a-Si alloy NFs to the liquid electrolyte and stabilize the solid-electrolyte interphase (SEI) layers on the surfaces of rGO sheets while facilitating electron transport. The metallic glass nanofibers exhibited superior electrochemical cell performance as an anode: (i) Si60Sn12Ce18Fe5Al3Ti2 NFs show a high specific capacity of 1017 mAh g(-1) up to 400 cycles at 0.05C with negligible capacity loss as well as superior cycling performance (nearly 99.9% capacity retention even after 2000 cycles at 0.5C); (ii) Si60Sn12Ce18Fe5Al3Ti2 NFs@rGO reveals outstanding rate behavior (569.77 mAh g(-1) after 2000 cycles at 0.5C and a reversible capacity of around 370 mAh g(-1) at 4C). We demonstrate the potential suitability of multicomponent a-Si alloy NFs as a long-cycling anode material.

Stabilizing lithium metal using ionic liquids for long-lived batteries

PubMed Central

Basile, A.; Bhatt, A. I.; O'Mullane, A. P.

2016-01-01

Suppressing dendrite formation at lithium metal anodes during cycling is critical for the implementation of future lithium metal-based battery technology. Here we report that it can be achieved via the facile process of immersing the electrodes in ionic liquid electrolytes for a period of time before battery assembly. This creates a durable and lithium ion-permeable solid–electrolyte interphase that allows safe charge–discharge cycling of commercially applicable Li|electrolyte|LiFePO4 batteries for 1,000 cycles with Coulombic efficiencies >99.5%. The tailored solid–electrolyte interphase is prepared using a variety of electrolytes based on the N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide room temperature ionic liquid containing lithium salts. The formation is both time- and lithium salt-dependant, showing dynamic morphology changes, which when optimized prevent dendrite formation and consumption of electrolyte during cycling. This work illustrates that a simple, effective and industrially applicable lithium metal pretreatment process results in a commercially viable cycle life for a lithium metal battery. PMID:27292652

Solvent decompositions and physical properties of decomposition compounds in Li-ion battery electrolytes studied by DFT calculations and molecular dynamics simulations.

PubMed

Tasaki, Ken

2005-02-24

The density functional theory (DFT) calculations have been performed for the reduction decompositions of solvents widely used in Li-ion secondary battery electrolytes, ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonates (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), including a typical electrolyte additive, vinylene carbonate (VC), at the level of B3LYP/6-311+G(2d,p), both in the gas phase and solution using the polarizable conductor calculation model. In the gas phase, the first electron reduction for the cyclic carbonates and for the linear carbonates is found to be exothermic and endothermic, respectively, while the second electron reduction is endothermic for all the compounds examined. On the contrary, in solution both first and second electron reductions are exothermic for all the compounds. Among the solvents and the additive examined, the likelihood of undergoing the first electron reduction in solution was found in the order of EC > PC > VC > DMC > EMC > DEC with EC being the most likely reduced. VC, on the other hand, is most likely to undergo the second electron reduction among the compounds, in the order of VC > EC > PC. Based on the results, the experimentally demonstrated effectiveness of VC as an excellent electrolyte additive was discussed. The bulk thermodynamic properties of two dilithium alkylene glycol dicarbonates, dilithium ethylene glycol dicarbonate (Li-EDC) and dilithium 1,2-propylene glycol dicarbonate (Li-PDC), as the major component of solid-electrolyte interface (SEI) films were also examined through molecular dynamics (MD) simulations in order to understand the stability of the SEI film. It was found that film produced from a decomposition of EC, modeled by Li-EDC, has a higher density, more cohesive energy, and less solubility to the solvent than the film produced from decomposition of PC, Li-PDC. Further, MD simulations of the interface between the decomposition compound and graphite suggested that Li-EDC has more favorable interactions with the graphite surface than Li-PDC. The difference in the SEI film stability and the behavior of Li-ion battery cycling among the solvents were discussed in terms of the molecular structures.

Chemical Shuttle Additives in Lithium Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patterson, Mary

2013-03-31

The goals of this program were to discover and implement a redox shuttle that is compatible with large format lithium ion cells utilizing LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} (NMC) cathode material and to understand the mechanism of redox shuttle action. Many redox shuttles, both commercially available and experimental, were tested and much fundamental information regarding the mechanism of redox shuttle action was discovered. In particular, studies surrounding the mechanism of the reduction of the oxidized redox shuttle at the carbon anode surface were particularly revealing. The initial redox shuttle candidate, namely 2-(pentafluorophenyl)-tetrafluoro-1,3,2-benzodioxaborole (BDB) supplied by Argonne National Laboratory (ANL, Lemont,more » Illinois), did not effectively protect cells containing NMC cathodes from overcharge. The ANL-RS2 redox shuttle molecule, namely 1,4-bis(2-methoxyethoxy)-2,5-di-tert-butyl-benzene, which is a derivative of the commercially successful redox shuttle 2,5-di-tert-butyl-1,4-dimethoxybenzene (DDB, 3M, St. Paul, Minnesota), is an effective redox shuttle for cells employing LiFePO{sub 4} (LFP) cathode material. The main advantage of ANL-RS2 over DDB is its larger solubility in electrolyte; however, ANL-RS2 is not as stable as DDB. This shuttle also may be effectively used to rebalance cells in strings that utilize LFP cathodes. The shuttle is compatible with both LTO and graphite anode materials although the cell with graphite degrades faster than the cell with LTO, possibly because of a reaction with the SEI layer. The degradation products of redox shuttle ANL-RS2 were positively identified. Commercially available redox shuttles Li{sub 2}B{sub 12}F{sub 12} (Air Products, Allentown, Pennsylvania and Showa Denko, Japan) and DDB were evaluated and were found to be stable and effective redox shuttles at low C-rates. The Li{sub 2}B{sub 12}F{sub 12} is suitable for lithium ion cells utilizing a high voltage cathode (potential that is higher than NMC) and the DDB is useful for lithium ion cells with LFP cathodes (potential that is lower than NMC). A 4.5 V class redox shuttle provided by Argonne National Laboratory was evaluated which provides a few cycles of overcharge protection for lithium ion cells containing NMC cathodes but it is not stable enough for consideration. Thus, a redox shuttle with an appropriate redox potential and sufficient chemical and electrochemical stability for commercial use in larger format lithium ion cells with NMC cathodes was not found. Molecular imprinting of the redox shuttle molecule during solid electrolyte interphase (SEI) layer formation likely contributes to the successful reduction of oxidized redox shuttle species at carbon anodes. This helps to understand how a carbon anode covered with an SEI layer, that is supposed to be electrically insulating, can reduce the oxidized form of a redox shuttle.« less

Optimization of Pore Structure of Cathodic Carbon Supports for Solvate Ionic Liquid Electrolytes Based Lithium-Sulfur Batteries.

PubMed

Zhang, Shiguo; Ikoma, Ai; Li, Zhe; Ueno, Kazuhide; Ma, Xiaofeng; Dokko, Kaoru; Watanabe, Masayoshi

2016-10-04

Lithium-sulfur (Li-S) batteries are a promising energy-storage technology owing to their high theoretical capacity and energy density. However, their practical application remains a challenge because of the serve shuttle effect caused by the dissolution of polysulfides in common organic electrolytes. Polysulfide-insoluble electrolytes, such as solvate ionic liquids (ILs), have recently emerged as alternative candidates and shown great potential in suppressing the shuttle effect and improving the cycle stability of Li-S batteries. Redox electrochemical reactions in polysulfide-insoluble electrolytes occur via a solid-state process at the interphase between the electrolyte and the composite cathode; therefore, creating an appropriate interface between sulfur and a carbon support is of great importance. Nevertheless, the porous carbon supports established for conventional organic electrolytes may not be suitable for polysulfide-insoluble electrolytes. In this work, we investigated the effect of the porous structure of carbon materials on the Li-S battery performance in polysulfide-insoluble electrolytes using solvate ILs as a model electrolyte. We determined that the pore volume (rather than the surface area) exerts a major influence on the discharge capacity of S composite cathodes. In particular, inverse opal carbons with three-dimensionally ordered interconnected macropores and a large pore volume deliver the highest discharge capacity. The battery performance in both polysulfide-soluble electrolytes and solvate ILs was used to study the effect of electrolytes. We propose a plausible mechanism to explain the different porous structure requirements in polysulfide-soluble and polysulfide-insoluble electrolytes.

High-Performance Sodium Metal Anodes Enabled by a Bifunctional Potassium Salt.

PubMed

Shi, Qiuwei; Zhong, Yiren; Wu, Min; Wang, Hongzhi; Wang, Hailiang

2018-04-12

Developing Na metal anodes that can be deeply cycled with high efficiency for a long time is a prerequisite for rechargeable Na metal batteries to be practically useful despite their notable advantages in theoretical energy density and potential low cost. Their high chemical reactivity with the electrolyte and tendency for dendrite formation are two major issues limiting the reversibility of Na metal electrodes. In this work, we introduce for the first time potassium bis(trifluoromethylsulfonyl)imide (KTFSI) as a bifunctional electrolyte additive to stabilize Na metal electrodes, in which the TFSI - anions decompose into lithium nitride and oxynitrides to render a desirable solid electrolyte interphase layer while the K + cations preferentially adsorb onto Na protrusions and provide electrostatic shielding to suppress dendritic deposition. Through the cooperation of the cations and anions, we have realized Na metal electrodes that can be deeply cycled at a capacity of 10 mAh cm -2 for hundreds of hours. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

One-dimensional nanostructured materials for lithium-ion battery and supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Chan, Candace Kay

The need for improved electrochemical storage devices has necessitated research on new and advanced electrode materials. One-dimensional nanomaterials such as nanowires, nanotubes, and nanoribbons, can provide a unique opportunity to engineer electrochemical devices to have improved electronic and ionic conductivity as well as electrochemical and structural transformations. Silicon and germanium nanowires (NWs) were studied as negative electrode materials for lithiumion batteries because of their ability to alloy with large amounts of lithium, leading to 4-10 times higher specific capacities than the graphite standard. These nanowires could be grown vertically off of metallic current collector substrates using the gold-catalyzed vapor-liquid-solid synthesis. Electrochemical measurements of the SiNWs showed that capacities greater than 3,500 mAh/g could be obtained for tens of cycles, while hundreds of cycles could be obtained at lower capacities. As opposed to bulk Si, the SiNWs were observed to maintain their morphology during cycling and did not pulverize due to the large volume changes. Detailed TEM and XRD characterization showed that the SiNWs became amorphous during the first lithiation (charge) and formed a two-phase region between crystalline Si and amorphous Li xSi. Afterwards, the SiNWs remained amorphous and subsequent reaction was through a single-phase cycling of amorphous Si. The good cycling behavior compared to bulk and micron-sized Si particles was attributed to the nanowire morphology and electrode design. The surface chemistry and solid-electrolyte interphase (SEI) were studied using XPS as a function of charge and discharge potential. The common reduction productions expected in the electrolyte (1 M LiPF6 in 1:1 EC/DEC) were observed, with the main component being Li2CO3. The morphology of the SEI was found to change at different potentials, indicating a dynamic process involving deposition, dissolution, and re-deposition on the SiNWs. Longterm cycling performance of the SiNWs in different electrolytes, with various surface modifications and coatings, and other experimental parameters were evaluated. The electrochemical reaction of GeNWs with lithium resulted in capacities of ˜1000 mAh/g for tens of cycles. The GeNWs were also observed to become amorphous after the first charge. Interestingly, very large irreversible capacities were observed in the GeNWs, indicating surface instabilities or reactivity with the electrolyte. To passivate the surface, a thin layer of amorphous Si was used to coat the GeNWs and make Ge-Si coreshell nanowires. This passivation helped to reduce the irreversibly capacity loss and gave reversible capacities typical for the GeNWs. Two positive electrode materials for Li-ion batteries were synthesized in nano-morphologies and characterized. Transformation of layered structured V2O5 nanoribbons into the fully lithiated o-Li 3V2O5 phase was found to depend not only on the width but also the thickness of the nanoribbons. For the first time, complete delithiation of o-Li3V2O5 back to the single-crystalline, pristine V2O5 nanoribbon was observed, indicating a 30% higher energy density. Nanostructured BiOCl, a conversion material, was also synthesized and characterized for its Li insertion properties. Networks of silver nanowires (AgNWs) and single-walled carbon nanotubes (SWNTs) were explored as highly conducting, high surface area, and printable materials for flexible, light-weight supercapacitors. Use of the solution-processible AgNWs and SWNTs, as well as a polymer electrolyte, facilitated the fabrication of an entirely printable device on plastic substrates. The devices showed promising results for high energy and power density supercapacitors, with energy and power densities reaching 24 Wh/kg and 42 kW/kg for the AgNW/SWNT composite.

Mechanically and chemically robust sandwich-structured C@Si@C nanotube array Li-ion battery anodes.

PubMed

Liu, Jinyun; Li, Nan; Goodman, Matthew D; Zhang, Hui Gang; Epstein, Eric S; Huang, Bo; Pan, Zeng; Kim, Jinwoo; Choi, Jun Hee; Huang, Xingjiu; Liu, Jinhuai; Hsia, K Jimmy; Dillon, Shen J; Braun, Paul V

2015-02-24

Stability and high energy densities are essential qualities for emerging battery electrodes. Because of its high specific capacity, silicon has been considered a promising anode candidate. However, the several-fold volume changes during lithiation and delithiation leads to fractures and continuous formation of an unstable solid-electrolyte interphase (SEI) layer, resulting in rapid capacity decay. Here, we present a carbon-silicon-carbon (C@Si@C) nanotube sandwich structure that addresses the mechanical and chemical stability issues commonly associated with Si anodes. The C@Si@C nanotube array exhibits a capacity of ∼2200 mAh g(-1) (∼750 mAh cm(-3)), which significantly exceeds that of a commercial graphite anode, and a nearly constant Coulombic efficiency of ∼98% over 60 cycles. In addition, the C@Si@C nanotube array gives much better capacity and structure stability compared to the Si nanotubes without carbon coatings, the ZnO@C@Si@C nanorods, a Si thin film on Ni foam, and C@Si and Si@C nanotubes. In situ SEM during cycling shows that the tubes expand both inward and outward upon lithiation, as well as elongate, and then revert back to their initial size and shape after delithiation, suggesting stability during volume changes. The mechanical modeling indicates the overall plastic strain in a nanotube is much less than in a nanorod, which may significantly reduce low-cycle fatigue. The sandwich-structured nanotube design is quite general, and may serve as a guide for many emerging anode and cathode systems.

A model problem concerning ionic transport in microstructured solid electrolytes

NASA Astrophysics Data System (ADS)

Curto Sillamoni, Ignacio J.; Idiart, Martín I.

2015-11-01

We consider ionic transport by diffusion and migration through microstructured solid electrolytes. The assumed constitutive relations for the constituent phases follow from convex energy and dissipation potentials which guarantee thermodynamic consistency. The effective response is determined by homogenizing the relevant field equations via the notion ofmulti-scale convergence. The resulting homogenized response involves several effective tensors, but they all require the solution of just one standard conductivity problem over the representative volume element. A multi-scale model for semicrystalline polymer electrolytes with spherulitic morphologies is derived by applying the theory to a specific class of two-dimensional microgeometries for which the effective response can be computed exactly. An enriched model accounting for a random dispersion of filler particles with interphases is also derived. In both cases, explicit expressions for the effective material parameters are provided. The models are used to explore the effect of crystallinity and filler content on the overall response. Predictions support recent experimental observations on doped poly-ethylene-oxide systems which suggest that the anisotropic crystalline phase can actually support faster ion transport than the amorphous phase along certain directions dictated by the morphology of the polymeric chains. Predictions also support the viewpoint that ceramic fillers improve ionic conductivity and cation transport number via interphasial effects.

Insertion compounds and composites made by ball milling for advanced sodium-ion batteries

PubMed Central

Zhang, Biao; Dugas, Romain; Rousse, Gwenaelle; Rozier, Patrick; Abakumov, Artem M.; Tarascon, Jean-Marie

2016-01-01

Sodium-ion batteries have been considered as potential candidates for stationary energy storage because of the low cost and wide availability of Na sources. However, their future commercialization depends critically on control over the solid electrolyte interface formation, as well as the degree of sodiation at the positive electrode. Here we report an easily scalable ball milling approach, which relies on the use of metallic sodium, to prepare a variety of sodium-based alloys, insertion layered oxides and polyanionic compounds having sodium in excess such as the Na4V2(PO4)2F3 phase. The practical benefits of preparing sodium-enriched positive electrodes as reservoirs to compensate for sodium loss during solid electrolyte interphase formation are demonstrated by assembling full C/P′2-Na1[Fe0.5Mn0.5]O2 and C/‘Na3+xV2(PO4)2F3' sodium-ion cells that show substantial increases (>10%) in energy storage density. Our findings may offer electrode design principles for accelerating the development of the sodium-ion technology. PMID:26777573

Lithium Difluorophosphate as a Dendrite-Suppressing Additive for Lithium Metal Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Pengcheng; Zhang, Linchao; Xiang, Hongfa

Here, the notorious lithium (Li) dendrites and the low Coulombic efficiency (CE) of Li anode are two major obstacles to the practical utilization of Li metal batteries (LMBs). Introducing a dendrite-suppressing additive into nonaqueous electrolytes is one of the facile and effective solutions to promote the commercialization of LMBs. Herein, Li difluorophosphate (LiPO 2F 2, LiDFP) is used as an electrolyte additive to inhibit Li dendrite growth by forming a vigorous and stable solid electrolyte interphase film on metallic Li anode. Moreover, the Li CE can be largely improved from 84.6% of the conventional LiPF 6-based electrolyte to 95.2% bymore » the addition of an optimal concentration of LiDFP at 0.15 M. The optimal LiDFP-containing electrolyte can allow the Li||Li symmetric cells to cycle stably for more than 500 and 200 h at 0.5 and 1.0 mA cm –2, respectively, much longer than the control electrolyte without LiDFP additive. Meanwhile, this LiDFP-containing electrolyte also plays an important role in enhancing the cycling stability of the Li||LiN i1/3Co 1/3Mn 1/3O 2 cells with a moderately high mass loading of 9.7 mg cm –2. These results demonstrate that LiDFP has extensive application prospects as a dendrite-suppressing additive in advanced LMBs.« less

Lithium Difluorophosphate as a Dendrite-Suppressing Additive for Lithium Metal Batteries.

PubMed

Shi, Pengcheng; Zhang, Linchao; Xiang, Hongfa; Liang, Xin; Sun, Yi; Xu, Wu

2018-06-13

The notorious lithium (Li) dendrites and the low Coulombic efficiency (CE) of Li anode are two major obstacles to the practical utilization of Li metal batteries (LMBs). Introducing a dendrite-suppressing additive into nonaqueous electrolytes is one of the facile and effective solutions to promote the commercialization of LMBs. Herein, Li difluorophosphate (LiPO2F2, LiDFP) is used as an electrolyte additive to inhibit Li dendrite growth by forming a vigorous and stable solid electrolyte interphase film on metallic Li anode. Moreover, the Li CE can be largely improved from 84.6% of the conventional LiPF6-based electrolyte to 95.2% by the addition of an optimal concentration of LiDFP at 0.15 M. The optimal LiDFP-containing electrolyte can allow the Li||Li symmetric cells to cycle stably for more than 500 and 200 h at 0.5 and 1.0 mA cm-2, respectively, much longer than the control electrolyte without LiDFP additive. Meanwhile, this LiDFP-containing electrolyte also plays an important role in enhancing the cycling stability of the Li||LiNi1/3Co1/3Mn1/3O2 cells with a moderately high mass loading of 9.7 mg cm-2. These results demonstrate that LiDFP has extensive application prospects as a dendrite-suppressing additive in advanced LMBs.

Lithium Difluorophosphate as a Dendrite-Suppressing Additive for Lithium Metal Batteries

DOE PAGES

Shi, Pengcheng; Zhang, Linchao; Xiang, Hongfa; ...

2018-06-13

Here, the notorious lithium (Li) dendrites and the low Coulombic efficiency (CE) of Li anode are two major obstacles to the practical utilization of Li metal batteries (LMBs). Introducing a dendrite-suppressing additive into nonaqueous electrolytes is one of the facile and effective solutions to promote the commercialization of LMBs. Herein, Li difluorophosphate (LiPO 2F 2, LiDFP) is used as an electrolyte additive to inhibit Li dendrite growth by forming a vigorous and stable solid electrolyte interphase film on metallic Li anode. Moreover, the Li CE can be largely improved from 84.6% of the conventional LiPF 6-based electrolyte to 95.2% bymore » the addition of an optimal concentration of LiDFP at 0.15 M. The optimal LiDFP-containing electrolyte can allow the Li||Li symmetric cells to cycle stably for more than 500 and 200 h at 0.5 and 1.0 mA cm –2, respectively, much longer than the control electrolyte without LiDFP additive. Meanwhile, this LiDFP-containing electrolyte also plays an important role in enhancing the cycling stability of the Li||LiN i1/3Co 1/3Mn 1/3O 2 cells with a moderately high mass loading of 9.7 mg cm –2. These results demonstrate that LiDFP has extensive application prospects as a dendrite-suppressing additive in advanced LMBs.« less

A Lithium-Ion Battery with Enhanced Safety Prepared using an Environmentally Friendly Process.

PubMed

Mueller, Franziska; Loeffler, Nicholas; Kim, Guk-Tae; Diemant, Thomas; Behm, R Jürgen; Passerini, Stefano

2016-06-08

A new lithium-ion battery chemistry is presented based on a conversion-alloying anode material, a carbon-coated Fe-doped ZnO (TMO-C), and a LiNi1/3 Mn1/3 Co1/3 O2 (NMC) cathode. Both electrodes were fabricated using an environmentally friendly cellulose-based binding agent. The performance of the new lithium-ion battery was evaluated with a conventional, carbonate-based electrolyte (ethylene carbonate:diethyl carbonate-1 m lithium hexafluorophosphate, EC:DEC 1 m LiPF6 ) and an ionic liquid (IL)-based electrolyte (N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide-0.2 m lithium bis(trifluoromethanesulfonyl)imide, Pyr14 TFSI 0.2 m LiTFSI), respectively. Galvanostatic charge/discharge tests revealed a reduced rate capability of the TMO-C/Pyr14 TFSI 0.2 m LiTFSI/NMC full-cell compared to the organic electrolyte, but the coulombic efficiency was significantly enhanced. Moreover, the IL-based electrolyte substantially improves the safety of the system due to a higher thermal stability of the formed anodic solid electrolyte interphase and the IL electrolyte itself. While the carbonate-based electrolyte shows sudden degradation reactions, the IL exhibits a slowly increasing heat flow, which does not constitute a serious safety risk. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An insight into intrinsic interfacial properties between Li metals and Li10GeP2S12 solid electrolytes.

PubMed

Chen, Bingbing; Ju, Jiangwei; Ma, Jun; Zhang, Jianjun; Xiao, Ruijuan; Cui, Guanglei; Chen, Liquan

2017-11-29

Density functional theory simulations and experimental studies were performed to investigate the interfacial properties, including lithium ion migration kinetics, between lithium metal anode and solid electrolyte Li 10 GeP 2 S 12 (LGPS). The LGPS[001] plane was chosen as the studied surface because the easiest Li + migration pathway is along this direction. The electronic structure of the surface states indicated that the electrochemical stability was reduced at both the PS 4 - and GeS 4 -teminated surfaces. For the interface cases, the equilibrium interfacial structures of lithium metal against the PS 4 -terminated LGPS[001] surface (Li/PS 4 -LGPS) and the GeS 4 -terminated LGPS[001] surface (Li/GeS 4 -LGPS) were revealed based on the structural relaxation and adhesion energy analysis. Solid electrolyte interphases were expected to be formed at both Li/PS 4 -LGPS and Li/GeS 4 -LGPS interfaces, resulting in an unstable state of interface and large interfacial resistance, which was verified by the EIS results of the Li/LGPS/Li cell. In addition, the simulations of the migration kinetics show that the energy barriers for Li + crossing the Li/GeS 4 -LGPS interface were relatively low compared with the Li/PS 4 -LGPS interface. This may contribute to the formation of Ge-rich phases at the Li/LGPS interface, which can tune the interfacial structures to improve the ionic conductivity for future all-solid-state batteries. This work will offer a thorough understanding of the Li/LGPS interface, including local structures, electronic states and Li + diffusion behaviors in all-solid-state batteries.

Effect of cation on diffusion coefficient of ionic liquids at onion-like carbon electrodes.

PubMed

Van Aken, Katherine L; McDonough, John K; Li, Song; Feng, Guang; Chathoth, Suresh M; Mamontov, Eugene; Fulvio, Pasquale F; Cummings, Peter T; Dai, Sheng; Gogotsi, Yury

2014-07-16

While most supercapacitors are limited in their performance by the stability of the electrolyte, using neat ionic liquids (ILs) as the electrolyte can expand the voltage window and temperature range of operation. In this study, ILs with bis(trifluoromethylsulfonyl)imide (Tf2N) as the anion were investigated as the electrolyte in onion-like carbon-based electrochemical capacitors. To probe the influence of cations on the electrochemical performance of supercapacitors, three different cations were used: 1-ethyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium and 1,6-bis(3-methylimidazolium-1-yl). A series of electrochemical characterization tests was performed using cyclic voltammetry (CV), galvanostatic cycling and electrochemical impedance spectroscopy (EIS). Diffusion coefficients were measured using EIS and correlated with quasielastic neutron scattering and molecular dynamics simulation. These three techniques were used in parallel to confirm a consistent trend between the three ILs. It was found that the IL with the smaller sized cation had a larger diffusion coefficient, leading to a higher capacitance at faster charge-discharge rates. Furthermore, the IL electrolyte performance was correlated with increasing temperature, which limited the voltage stability window and led to the formation of a solid electrolyte interphase on the carbon electrode surface, evident in both the CV and EIS experiments.

Simultaneous Stabilization of LiNi0.76Mn0.14Co0.10O2 Cathode and Lithium Metal Anode by LiBOB Additive.

PubMed

Zhao, Wengao; Zou, Lianfeng; Zheng, Jianming; Jia, Haiping; Song, Junhua; Engelhard, Mark H; Wang, Chongmin; Xu, Wu; Yang, Yong; Zhang, Ji-Guang

2018-05-01

The long-term cycling performance, rate capability, and voltage stability of lithium (Li) metal batteries with LiNi0.76Mn0.14Co0.10O2 (NMC76) cathodes is greatly enhanced by lithium bis(oxalato)borate (LiBOB) additive in the LiPF6-based electrolyte. With 2% LiBOB in the electrolyte, a Li||NMC76 cell is able to achieve a high capacity retention of 96.8% after 200 cycles at C/3 rate (1C = 200 mA g-1), which is the best result reported for a Ni-rich NMC cathode coupled with Li metal anode. The significantly enhanced electrochemical performance can be ascribed to the stabilization of both the NMC76-cathode/electrolyte and Li-metal-anode/electrolyte interfaces. LiBOB-containing electrolyte not only facilitates the formation of a more compact solid electrolyte interphase on the Li metal surface, it also forms a enhanced cathode electrolyte interface layer, which efficiently prevents the corrosion of the cathode interface and mitigates the formation of disordered rock-salt phase after cycling. The fundamental findings of this work highlight the importance of recognizing the dual effects of electrolyte additives in simultaneously stabilizing both cathode and anode interfaces, so as to enhance the long-term cycle life of high-energy-density battery systems. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lithium electrodeposition dynamics in aprotic electrolyte observed in situ via transmission electron microscopy

DOE PAGES

Leenheer, Andrew Jay; Jungjohann, Katherine Leigh; Zavadil, Kevin Robert; ...

2015-03-18

Electrodeposited metallic lithium is an ideal negative battery electrode, but nonuniform microstructure evolution during cycling leads to degradation and safety issues. A better understanding of the Li plating and stripping processes is needed to enable practical Li-metal batteries. Here we use a custom microfabricated, sealed liquid cell for in situ scanning transmission electron microscopy (STEM) to image the first few cycles of lithium electrodeposition/dissolution in liquid aprotic electrolyte at submicron resolution. Cycling at current densities from 1 to 25 mA/cm 2 leads to variations in grain structure, with higher current densities giving a more needle-like, higher surface area deposit. Themore » effect of the electron beam was explored, and it was found that, even with minimal beam exposure, beam-induced surface film formation could alter the Li microstructure. The electrochemical dissolution was seen to initiate from isolated points on grains rather than uniformly across the Li surface, due to the stabilizing solid electrolyte interphase surface film. As a result, we discuss the implications for operando STEM liquid-cell imaging and Li-battery applications.« less

Electrolyte additive enabled fast charging and stable cycling lithium metal batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jianming; Engelhard, Mark H.; Mei, Donghai

2017-03-01

Batteries using lithium (Li) metal as anodes are considered promising energy storage systems because of their high energy densities. However, safety concerns associated with dendrite growth along with limited cycle life, especially at high charge current densities, hinder their practical uses. Here we report that an optimal amount (0.05 M) of LiPF6 as an additive in LiTFSI-LiBOB dual-salt/carbonate-solvent-based electrolytes significantly enhances the charging capability and cycling stability of Li metal batteries. In a Li metal battery using a 4-V Li-ion cathode at a moderately high loading of 1.75mAh cm(-2), a cyclability of 97.1% capacity retention after 500 cycles along withmore » very limited increase in electrode overpotential is accomplished at a charge/discharge current density up to 1.75 mA cm(-2). The fast charging and stable cycling performances are ascribed to the generation of a robust and conductive solid electrolyte interphase at the Li metal surface and stabilization of the Al cathode current collector.« less

Dual overcharge protection and solid electrolyte interphase-improving action in Li-ion cells containing a bis-annulated dialkoxyarene electrolyte additive

NASA Astrophysics Data System (ADS)

Zhang, Jingjing; Shkrob, Ilya A.; Assary, Rajeev S.; Zhang, Shuo; Hu, Bin; Liao, Chen; Zhang, Zhengcheng; Zhang, Lu

2018-02-01

1,4-Dialkoxybenzene additives are commonly used as redox active shuttles in lithium-ion batteries in order to prevent runaway oxidation of electrolyte when overcharge conditions set in. During this action the shuttle molecule goes through a futile cycle, becoming oxidized at the cathode and reduced at the anode. Minimizing parasitic reactions in all states of charge is paramount for sustained protective action. Here we demonstrate that recently developed bis-annulated 9,10-bis(2-methoxyethoxy)-1,2,3,4,5,6,7,8-octahydro-1,4:5,8-dimethano-anthracene shuttle molecule (that yields exceptionally stable radical cations) survives over 120 cycles of overcharge abuse with 100% overcharge ratio at C/5 rate. Equally remarkably, in the presence of this additive the cell impedance becomes significantly lower compared to the control cells without the additive; this decrease is observed during the formation, normal cycling, and even under overcharge conditions. This unusual dual action has not been observed in other redox shuttle systems, and it presents considerable practical interest.

Ionic Liquid-Enhanced Solid State Electrolyte Interface (SEI) for Lithium Sulfur Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jianming; Gu, Meng; Chen, Honghao

2013-05-16

Li-S battery is a complicated system with many challenges existing before its final market penetration. While most of the reported work for Li-S batteries is focused on the cathode design, we demonstrate in this work that the anode consumption accelerated by corrosive polysulfide solution also critically determines the Li-S cell performance. To validate this hypothesis, ionic liquid (IL) N-methyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Py14TFSI) has been employed to modify the properties of SEI layer formed on Li metal surface in Li-S batteries. It is found that the IL-enhanced passivation film on the lithium anode surface exhibits much different morphology and chemical compositions, effectivelymore » protecting lithium metal from continuous attack by soluble polysulfides. Therefore, both cell impedance and the irreversible consumption of polysulfides on lithium metal are reduced. As a result, the Coulombic efficiency and the cycling stability of Li-S batteries have been greatly improved. After 120 cycles, Li-S battery cycled in the electrolyte containing IL demonstrates a high capacity retention of 94.3% at 0.1 C rate. These results unveil another important failure mechanism for Li-S batteries and shin the light on the new approaches to improve Li-S battery performances.« less

Precise Perforation and Scalable Production of Si Particles from Low-Grade Sources for High-Performance Lithium Ion Battery Anodes.

PubMed

Zong, Linqi; Jin, Yan; Liu, Chang; Zhu, Bin; Hu, Xiaozhen; Lu, Zhenda; Zhu, Jia

2016-11-09

Alloy anodes, particularly silicon, have been intensively pursued as one of the most promising anode materials for the next generation lithium-ion battery primarily because of high specific capacity (>4000 mAh/g) and elemental abundance. In the past decade, various nanostructures with porosity or void space designs have been demonstrated to be effective to accommodate large volume expansion (∼300%) and to provide stable solid electrolyte interphase (SEI) during electrochemical cycling. However, how to produce these building blocks with precise morphology control at large scale and low cost remains a challenge. In addition, most of nanostructured silicon suffers from poor Coulombic efficiency due to a large surface area and Li ion trapping at the surface coating. Here we demonstrate a unique nanoperforation process, combining modified ball milling, annealing, and acid treating, to produce porous Si with precise and continuous porosity control (from 17% to 70%), directly from low cost metallurgical silicon source (99% purity, ∼ $1/kg). The produced porous Si coated with graphene by simple ball milling can deliver a reversible specific capacity of 1250 mAh/g over 1000 cycles at the rate of 1C, with Coulombic efficiency of first cycle over 89.5%. The porous networks also provide efficient ion and electron pathways and therefore enable excellent rate performance of 880 mAh/g at the rate of 5C. Being able to produce particles with precise porosity control through scalable processes from low-grade materials, it is expected that this nanoperforation may play a role in the next generation lithium ion battery anodes, as well as many other potential applications such as optoelectronics and thermoelectrics.

The Weinstein conjecture with multiplicities on spherizations

NASA Astrophysics Data System (ADS)

Hertzberg, Benjamin J.

2011-07-01

Si-based anodes have recently received considerable attention for use in Li-ion batteries, due to their extremely high specific capacity---an order of magnitude beyond that offered by conventional graphite anode materials. However, during the lithiation process, Si-based anodes undergo extreme increases in volume, potentially by more than 300 %. The stresses produced within the electrode by these volume changes can damage the electrode binder, the active Si particles and the solid electrolyte interphase (SEI), causing the electrode to rapidly fail and lose capacity. These problems can be overcome by producing new anode materials incorporating both Si and C, which may offer a favorable combination of the best properties of both materials, and which can be designed with internal porosity, thereby buffering the high strains produced during battery charge and discharge with minimal overall volume changes. However, in order to develop useful anode materials, we must gain a thorough understanding of the structural, microstructural and chemical changes occurring within the electrode during the lithiation and delithiation process, and we must develop new processes for synthesizing composite anode particles which can survive the extreme strains produced during lithium intercalation of Si and exhibit no volume changes in spite of the volume changes in Si. In this work we have developed several novel synthesis processes for producing internally porous Si-C nanocomposite anode materials for Li-ion batteries. These nanocomposites possess excellent specific capacity, Coulombic efficiency, cycle lifetime, and rate capability. We have also investigated the influence of a range of different parameters on the electrochemical performance of these materials, including pore size and shape, carbon and silicon film thickness and microstructure, and binder chemistry.

Ionic liquids and derived materials for lithium and sodium batteries.

PubMed

Yang, Qiwei; Zhang, Zhaoqiang; Sun, Xiao-Guang; Hu, Yong-Sheng; Xing, Huabin; Dai, Sheng

2018-03-21

The ever-growing demand for advanced energy storage devices in portable electronics, electric vehicles and large scale power grids has triggered intensive research efforts over the past decade on lithium and sodium batteries. The key to improve their electrochemical performance and enhance the service safety lies in the development of advanced electrode, electrolyte, and auxiliary materials. Ionic liquids (ILs) are liquids consisting entirely of ions near room temperature, and are characterized by many unique properties such as ultralow volatility, high ionic conductivity, good thermal stability, low flammability, a wide electrochemical window, and tunable polarity and basicity/acidity. These properties create the possibilities of designing batteries with excellent safety, high energy/power density and long-term stability, and also provide better ways to synthesize known materials. IL-derived materials, such as poly(ionic liquids), ionogels and IL-tethered nanoparticles, retain most of the characteristics of ILs while being endowed with other favourable features, and thus they have received a great deal of attention as well. This review provides a comprehensive review of the various applications of ILs and derived materials in lithium and sodium batteries including Li/Na-ion, dual-ion, Li/Na-S and Li/Na-air (O 2 ) batteries, with a particular emphasis on recent advances in the literature. Their unique characteristics enable them to serve as advanced resources, medium, or ingredient for almost all the components of batteries, including electrodes, liquid electrolytes, solid electrolytes, artificial solid-electrolyte interphases, and current collectors. Some thoughts on the emerging challenges and opportunities are also presented in this review for further development.

Advanced Micro/Nanostructures for Lithium Metal Anodes

PubMed Central

Zhang, Rui; Li, Nian‐Wu; Cheng, Xin‐Bing; Yin, Ya‐Xia

2017-01-01

Owning to their very high theoretical capacity, lithium metal anodes are expected to fuel the extensive practical applications in portable electronics and electric vehicles. However, unstable solid electrolyte interphase and lithium dendrite growth during lithium plating/stripping induce poor safety, low Coulombic efficiency, and short span life of lithium metal batteries. Lately, varies of micro/nanostructured lithium metal anodes are proposed to address these issues in lithium metal batteries. With the unique surface, pore, and connecting structures of different nanomaterials, lithium plating/stripping processes have been regulated. Thus the electrochemical properties and lithium morphologies have been significantly improved. These micro/nanostructured lithium metal anodes shed new light on the future applications for lithium metal batteries. PMID:28331792

Doped Si nanoparticles with conformal carbon coating and cyclized-polyacrylonitrile network as high-capacity and high-rate lithium-ion battery anodes.

PubMed

Xie, Ming; Piper, Daniela Molina; Tian, Miao; Clancey, Joel; George, Steven M; Lee, Se-Hee; Zhou, Yun

2015-09-11

Doped Si nanoparticles (SiNPs) with conformal carbon coating and cyclized-polyacrylonitrile (PAN) network displayed capacities of 3500 and 3000 mAh g(-1) at C/20 and C/10, respectively. At 1 C, the electrode preserves a specific discharge capacity of ∼1500 mAh g(-1) for at least 60 cycles without decay. Al2O3 atomic layer deposition (ALD) helps improve the initial Coulombic efficiency (CE) to 85%. The dual coating of conformal carbon and cyclized-PAN help alleviate volume change and facilitate charge transfer. Ultra-thin Al2O3 ALD layers help form a stable solid electrolyte interphase interface.

Fluorine-donating electrolytes enable highly reversible 5-V-class Li metal batteries.

PubMed

Suo, Liumin; Xue, Weijiang; Gobet, Mallory; Greenbaum, Steve G; Wang, Chao; Chen, Yuming; Yang, Wanlu; Li, Yangxing; Li, Ju

2018-02-06

Lithium metal has gravimetric capacity ∼10× that of graphite which incentivizes rechargeable Li metal batteries (RLMB) development. A key factor that limits practical use of RLMB is morphological instability of Li metal anode upon electrodeposition, reflected by the uncontrolled area growth of solid-electrolyte interphase that traps cyclable Li, quantified by the Coulombic inefficiency (CI). Here we show that CI decreases approximately exponentially with increasing donatable fluorine concentration of the electrolyte. By using up to 7 m of Li bis(fluorosulfonyl)imide in fluoroethylene carbonate, where both the solvent and the salt donate F, we can significantly suppress anode porosity and improve the Coulombic efficiency to 99.64%. The electrolyte demonstrates excellent compatibility with 5-V LiNi 0.5 Mn 1.5 O 4 cathode and Al current collector beyond 5 V. As a result, an RLMB full cell with only 1.4× excess lithium as the anode was demonstrated to cycle above 130 times, at industrially significant loading of 1.83 mAh/cm 2 and 0.36 C. This is attributed to the formation of a protective LiF nanolayer, which has a wide bandgap, high surface energy, and small Burgers vector, making it ductile at room temperature and less likely to rupture in electrodeposition.

The Role of Electrolyte Upon the SEI Formation Characteristics and Low Temperature Performance of Lithium-Ion Cells With Graphite Anodes

NASA Technical Reports Server (NTRS)

Smart, M.; Ratnakumar, B.; Greenbaum, S.; Surampudi, S.

1998-01-01

Quarternary lithium-ion battery electrolyte solutions containing ester co-solvents in mixtures of carbonates have been demonstrated to have high conductivity at low temperatures (<-20 degrees Celcius).

Mechanical measurements on lithium phosphorous oxynitride coated silicon thin film electrodes for lithium-ion batteries during lithiation and delithiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Obeidi, Ahmed, E-mail: alobeidi@mit.edu; Thompson, Carl V., E-mail: reiner.moenig@kit.edu, E-mail: cthomp@mit.edu; Kramer, Dominik, E-mail: dominik.kramer@kit.edu

2016-08-15

The development of large stresses during lithiation and delithiation drives mechanical and chemical degradation processes (cracking and electrolyte decomposition) in thin film silicon anodes that complicate the study of normal electrochemical and mechanical processes. To reduce these effects, lithium phosphorous oxynitride (LiPON) coatings were applied to silicon thin film electrodes. Applying a LiPON coating has two purposes. First, the coating acts as a stable artificial solid electrolyte interphase. Second, it limits mechanical degradation by retaining the electrode's planar morphology during cycling. The development of stress in LiPON-coated electrodes was monitored using substrate curvature measurements. LiPON-coated electrodes displayed highly reproducible cycle-to-cyclemore » behavior, unlike uncoated electrodes which had poorer coulombic efficiency and exhibited a continual loss in stress magnitude with continued cycling due to film fracture. The improved mechanical stability of the coated silicon electrodes allowed for a better investigation of rate effects and variations of mechanical properties during electrochemical cycling.« less

Inorganic-Organic Coating via Molecular Layer Deposition Enables Long Life Sodium Metal Anode.

PubMed

Zhao, Yang; Goncharova, Lyudmila V; Zhang, Qian; Kaghazchi, Payam; Sun, Qian; Lushington, Andrew; Wang, Biqiong; Li, Ruying; Sun, Xueliang

2017-09-13

Metallic Na anode is considered as a promising alternative candidate for Na ion batteries (NIBs) and Na metal batteries (NMBs) due to its high specific capacity, and low potential. However, the unstable solid electrolyte interphase layer caused by serious corrosion and reaction in electrolyte will lead to big challenges, including dendrite growth, low Coulombic efficiency and even safety issues. In this paper, we first demonstrate the inorganic-organic coating via advanced molecular layer deposition (alucone) as a protective layer for metallic Na anode. By protecting Na anode with controllable alucone layer, the dendrites and mossy Na formation have been effectively suppressed and the lifetime has been significantly improved. Moreover, the molecular layer deposition alucone coating shows better performances than the atomic layer deposition Al 2 O 3 coating. The novel design of molecular layer deposition protected Na metal anode may bring in new opportunities to the realization of the next-generation high energy-density NIBs and NMBs.

Highly Porous Silicon Embedded in a Ceramic Matrix: A Stable High-Capacity Electrode for Li-Ion Batteries.

PubMed

Vrankovic, Dragoljub; Graczyk-Zajac, Magdalena; Kalcher, Constanze; Rohrer, Jochen; Becker, Malin; Stabler, Christina; Trykowski, Grzegorz; Albe, Karsten; Riedel, Ralf

2017-11-28

We demonstrate a cost-effective synthesis route that provides Si-based anode materials with capacities between 2000 and 3000 mAh·g Si -1 (400 and 600 mAh·g composite -1 ), Coulombic efficiencies above 99.5%, and almost 100% capacity retention over more than 100 cycles. The Si-based composite is prepared from highly porous silicon (obtained by reduction of silica) by encapsulation in an organic carbon and polymer-derived silicon oxycarbide (C/SiOC) matrix. Molecular dynamics simulations show that the highly porous silicon morphology delivers free volume for the accommodation of strain leading to no macroscopic changes during initial Li-Si alloying. In addition, a carbon layer provides an electrical contact, whereas the SiOC matrix significantly diminishes the interface between the electrolyte and the electrode material and thus suppresses the formation of a solid-electrolyte interphase on Si. Electrochemical tests of the micrometer-sized, glass-fiber-derived silicon demonstrate the up-scaling potential of the presented approach.

Ethoxy (pentafluoro) cyclotriphosphazene (PFPN) as a multi-functional flame retardant electrolyte additive for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Li, Xi; Li, Weikang; Chen, Lai; Lu, Yun; Su, Yuefeng; Bao, Liying; Wang, Jing; Chen, Renjie; Chen, Shi; Wu, Feng

2018-02-01

With the wide application of lithium-ion batteries (LiBs), safety performance is an important constraint on the commercialization of large-scale, high-capacity LIBs. The main reason for the safety problem is that the electrolyte of LiBs is highly flammable, especially under high temperature and high voltage. It is an effective method to improve the safety of cells by mixing flame retardant with conventional electrolyte comprising of LiPF6 and carbonates. Herein, ethoxy (pentafluoro) cyclotriphosphazene (PFPN) is studied as a high efficiency flame retardant. Adding 5 vol% of PFPN results in a non-flammable electrolyte with self-extinguishing time (SET) of 12.38 s g-1 and critical oxygen index (COI) of 22.9, without compromising the capacity of cathode material. The initial discharge capacity of the LiCoO2 electrode with 5% PFPN is 150.7 mAh g-1, with a capacity retention of 99.14% after 30 cycles at 0.1 C. The results show that 5 vol% is the best adding amount of PFPN for electrolyte, which can modify the solid electrolyte interface (SEI). Moreover, PFPN reduces charge transfer resistance of the cells, resulting decreased electrode polarization and enhanced electrochemistry performances at low temperature. These results have confirmed that PFPN has the potential to be a multi-function additive for commercial LIBs production.

Suppressing Manganese Dissolution from Lithium Manganese Oxide Spinel Cathodes with Single-Layer Graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaber-Ansari, Laila; Puntambekar, Kanan P.; Kim, Soo

2015-06-24

Spinel-structured LiMn 2 O 4 (LMO) is a desirable cathode material for Li-ion batteries due to its low cost, abundance, and high power capability. However, LMO suffers from limited cycle life that is triggered by manganese dissolution into the electrolyte during electrochemical cycling. Here, it is shown that single-layer graphene coatings suppress manganese dissolution, thus enhancing the performance and lifetime of LMO cathodes. Relative to lithium cells with uncoated LMO cathodes, cells with graphene-coated LMO cathodes provide improved capacity retention with enhanced cycling stability. X-ray photoelectron spectroscopy reveals that graphene coatings inhibit manganese depletion from the LMO surface. Additionally, transmissionmore » electron microscopy demonstrates that a stable solid electrolyte interphase is formed on graphene, which screens the LMO from direct contact with the electrolyte. Density functional theory calculations provide two mechanisms for the role of graphene in the suppression of manganese dissolution. First, common defects in single-layer graphene are found to allow the transport of lithium while concurrently acting as barriers for manganese diffusion. Second, graphene can chemically interact with Mn 3+ at the LMO electrode surface, promoting an oxidation state change to Mn 4+ , which suppresses dissolution.« less

Carbon Nanotube-CoF2 Multifunctional Cathode for Lithium Ion Batteries: Effect of Electrolyte on Cycle Stability.

PubMed

Wang, Xinran; Gu, Wentian; Lee, Jung Tae; Nitta, Naoki; Benson, Jim; Magasinski, Alexandre; Schauer, Mark W; Yushin, Gleb

2015-10-01

Transition metal fluorides (MFx ) offer remarkably high theoretical energy density. However, the low cycling stability, low electrical and ionic conductivity of metal fluorides have severely limited their applications as conversion-type cathode materials for lithium ion batteries. Here, a scalable and low-cost strategy is reported on the fabrication of multifunctional cobalt fluoride/carbon nanotube nonwoven fabric nanocomposite, which demonstrates a combination of high capacity (near-theoretical, 550mAhgCoF2-1) and excellent mechanical properties. Its strength and modulus of toughness exceed that of many aluminum alloys, cast iron, and other structural materials, fulfilling the use of MFx -based materials in batteries with load-bearing capabilities. In the course of this study, cathode dissolution in conventional electrolytes has been discovered as the main reason that leads to the rapid growth of the solid electrolyte interphase layer and attributes to rapid cell degradation. And such largely overlooked degradation mechanism is overcome by utilizing electrolyte comprising a fluorinated solvent, which forms a protective ionically conductive layer on the cathode and anode surfaces. With this approach, 93% capacity retention is achieved after 200 cycles at the current density of 100 mA g(-1) and over 50% after 10 000 cycles at the current density of 1000 mA g(-1) . © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fast ion transport at solid-solid interfaces in hybrid battery anodes

NASA Astrophysics Data System (ADS)

Tu, Zhengyuan; Choudhury, Snehashis; Zachman, Michael J.; Wei, Shuya; Zhang, Kaihang; Kourkoutis, Lena F.; Archer, Lynden A.

2018-04-01

Carefully designed solid-electrolyte interphases are required for stable, reversible and efficient electrochemical energy storage in batteries. We report that hybrid battery anodes created by depositing an electrochemically active metal (for example, Sn, In or Si) on a reactive alkali metal electrode by a facile ion-exchange chemistry lead to very high exchange currents and stable long-term performance of electrochemical cells based on Li and Na electrodes. By means of direct visualization and ex situ electrodeposition studies, Sn-Li anodes are shown to be stable at 3 mA cm-2 and 3 mAh cm-2. Prototype full cells in which the hybrid anodes are paired with high-loading LiNi0.8Co0.15Al0.05O2(NCA) cathodes are also reported. As a second demonstration, we create and study Sn-Na hybrid anodes and show that they can be cycled stably for more than 1,700 hours with minimal voltage divergence. Charge storage at the hybrid anodes is reported to involve a combination of alloying and electrodeposition reactions.

Interphase evolution at two promising electrode materials for Li-ion batteries: LiFePO4 and LiNi1/2 Mn1/2O2.

PubMed

Dupré, Nicolas; Cuisinier, Marine; Martin, Jean-Frederic; Guyomard, Dominique

2014-07-21

The present review reports the characterization and control of interfacial processes occurring on olivine LiFePO(4) and layered LiNi(1/2) Mn(1/2)O(2), standing here as model compounds, during storage and electrochemical cycling. The formation and evolution of the interphase created by decomposition of the electrolyte is investigated by using spectroscopic tools such as magic-angle-spinning nuclear magnetic resonance ((7)Li,(19)F and (31)P) and electron energy loss spectroscopy, in parallel to X-ray photoelectron spectroscopy, to quantitatively describe the interphase and unravel its architecture. The influence of the pristine surface chemistry of the active material is carefully examined. The importance of the chemical history of the surface of the electrode material before any electrochemical cycling and the strong correlation between interface phenomena, the formation/evolution of an interphase, and the electrochemical behavior appear clearly from the use of these combined characterization probes. This approach allows identifying interface aging and failure mechanisms. Different types of surface modifications are then investigated, such as intrinsic modifications upon aging in air or methods based on the use of additives in the electrolyte or carbon coatings on the surface of the active materials. In each case, the species detected on the surface of the materials during storage and cycling are correlated with the electrochemical performance of the modified positive electrodes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stabilization of Lithium-Metal Batteries Based on the in Situ Formation of a Stable Solid Electrolyte Interphase Layer.

PubMed

Park, Seong-Jin; Hwang, Jang-Yeon; Yoon, Chong S; Jung, Hun-Gi; Sun, Yang-Kook

2018-05-30

Lithium (Li) metals have been considered most promising candidates as an anode to increase the energy density of Li-ion batteries because of their ultrahigh specific capacity (3860 mA h g -1 ) and lowest redox potential (-3.040 V vs standard hydrogen electrode). However, unstable dendritic electrodeposition, low Coulombic efficiency, and infinite volume changes severely hinder their practical uses. Herein, we report that ethyl methyl carbonate (EMC)- and fluoroethylene carbonate (FEC)-based electrolytes significantly enhance the energy density and cycling stability of Li-metal batteries (LMBs). In LMBs, using commercialized Ni-rich Li[Ni 0.6 Co 0.2 Mn 0.2 ]O 2 (NCM622) and 1 M LiPF 6 in EMC/FEC = 3:1 electrolyte exhibits a high initial capacity of 1.8 mA h cm -2 with superior cycling stability and high Coulombic efficiency above 99.8% for 500 cycles while delivering a unprecedented energy density. The present work also highlights a significant improvement in scaled-up pouch-type Li/NCM622 cells. Moreover, the postmortem characterization of the cycled cathodes, separators, and Li-metal anodes collected from the pouch-type Li/NCM622 cells helped identifying the improvement or degradation mechanisms behind the observed electrochemical cycling.

Mechanistic elucidation of thermal runaway in potassium-ion batteries

NASA Astrophysics Data System (ADS)

Adams, Ryan A.; Varma, Arvind; Pol, Vilas G.

2018-01-01

For the first time, thermal runaway of charged graphite anodes for K-ion batteries is investigated, using differential scanning calorimetry (DSC) to probe the exothermic degradation reactions. Investigated parameters such as state of charge, cycle number, surface area, and binder demonstrate strong influences on the DSC profiles. Thermal runaway initiates at 100 °C owing to KxC8 - electrolyte reactions, but the K-ion graphite anode evolves significantly less heat as compared to the analogous Li-ion system (395 J g-1 vs. 1048 J g-1). The large volumetric expansion of graphite during potassiation cracks the SEI layer, enabling contact and reaction of KC8 - electrolyte, which diminishes with cycle number due to continuous SEI growth. High surface area graphite decreases the total heat generation, owing to thermal stability of the K-ion SEI layer. These findings illustrate the dynamic nature of K-ion thermal runaway and its many contrasts with the Li-ion graphite system, permitting possible engineering solutions for safer batteries.

Evidence of covalent synergy in silicon–sulfur–graphene yielding highly efficient and long-life lithium-ion batteries

DOE PAGES

Hassan, Fathy M.; Batmaz, Rasim; Li, Jingde; ...

2015-10-26

Silicon has the potential to revolutionize the energy storage capacities of lithium-ion batteries to meet the ever increasing power demands of next generation technologies. To avoid the operational stability problems of silicon-based anodes, we propose synergistic physicochemical alteration of electrode structures during their design. This capitalizes on covalent interaction of Si nanoparticles with sulfur-doped graphene and with cyclized polyacrylonitrile to provide a robust nanoarchitecture. This hierarchical structure stabilized the solid electrolyte interphase leading to superior reversible capacity of over 1,000 mAh g -1 for 2,275 cycles at 2 A g -1. Furthermore, the nanoarchitectured design lowered the contact of themore » electrolyte to the electrode leading to not only high coulombic efficiency of 99.9% but also maintaining high stability even with high electrode loading associated with 3.4 mAh cm -2. As a result, the excellent performance combined with the simplistic, scalable and non-hazardous approach render the process as a very promising candidate for Li-ion battery technology.« less

Degradation diagnosis of lithium-ion batteries with a LiNi0.5Co0.2Mn0.3O2 and LiMn2O4 blended cathode using dV/dQ curve analysis

NASA Astrophysics Data System (ADS)

Ando, Keisuke; Matsuda, Tomoyuki; Imamura, Daichi

2018-06-01

Understanding the degradation factors (cathode and anode degradation and solid electrolyte interface (SEI) formation) of lithium-ion batteries (LIBs) with a blended cathode is necessary to improve their durability because battery drive vehicles often use LIBs with a blended cathode due to advantages of power and cost. We developed a dV/dQ curve analysis adapted for through a dQ/dV curve analysis to elucidate the relations between cycle test conditions and degradation factors. To compare said factors, cycle tests were conducted under different conditions: one charge/discharge rate (C/3), two state-of-charge (SoC) ranges (100%-0% and 100%-70%), and three temperatures (0 °C, 25 °C, and 45 °C). We confirmed that there are clear differences in the degree of contribution of each degradation factor depending on conditions. For instance, at 0 °C, although the capacity reduction rate was almost the same regardless of the SoC range, the degradation mechanisms were different, i.e., the cathode degradation and the SEI formation occurred at the same time, resulting in the reduced capacity for the 100%-0% SoC range, while capacity reduction was mainly due to SEI formation for the 100%-70% SoC range.

Cr{sub 2}O{sub 5} as new cathode for rechargeable sodium ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Xu-Yong; Chien, Po-Hsiu; Rose, Alyssa M.

2016-10-15

Chromium oxide, Cr{sub 2}O{sub 5}, was synthesized by pyrolyzing CrO{sub 3} at 350 °C and employed as a new cathode in rechargeable sodium ion batteries. Cr{sub 2}O{sub 5}/Na rechargeable batteries delivered high specific capacities up to 310 mAh/g at a current density of C/16 (or 20 mA/g). High-resolution solid-state {sup 23}Na NMR both qualitatively and quantitatively revealed the reversible intercalation of Na ions into the bulk electrode and participation of Na ions in the formation of the solid-electrolyte interphase largely at low potentials. Amorphization of the electrode structure occurred during the first discharge revealed by both NMR and X-ray diffractionmore » data. CrO{sub 3}-catalyzed electrolyte degradation and loss in electronic conductivity led to gradual capacity fading. The specific capacity stabilized at >120 mAh/g after 50 charge-discharge cycles. Further improvement in electrochemical performance is possible via electrode surface modification, polymer binder incorporation, or designs of new morphologies. - Graphical abstract: Electrochemical profile of a Cr{sub 2}O{sub 5}/Na battery cell and high-resolution solid-state {sup 23}Na MAS NMR spectrum of a Cr{sub 2}O{sub 5} electrode discharged to 2 V. - Highlights: • Cr{sub 2}O{sub 5} was synthesized and used as a new cathode in rechargeable Na ion batteries. • A high capacity of 310 mAh/g and an energy density of 564 Wh/kg were achieved. • High-resolution solid-state {sup 23}Na NMR was employed to follow the reaction mechanisms.« less

Impedance based time-domain modeling of lithium-ion batteries: Part I

NASA Astrophysics Data System (ADS)

Gantenbein, Sophia; Weiss, Michael; Ivers-Tiffée, Ellen

2018-03-01

This paper presents a novel lithium-ion cell model, which simulates the current voltage characteristic as a function of state of charge (0%-100%) and temperature (0-30 °C). It predicts the cell voltage at each operating point by calculating the total overvoltage from the individual contributions of (i) the ohmic loss η0, (ii) the charge transfer loss of the cathode ηCT,C, (iii) the charge transfer loss and the solid electrolyte interface loss of the anode ηSEI/CT,A, and (iv) the solid state and electrolyte diffusion loss ηDiff,A/C/E. This approach is based on a physically meaningful equivalent circuit model, which is parametrized by electrochemical impedance spectroscopy and time domain measurements, covering a wide frequency range from MHz to μHz. The model is exemplarily parametrized to a commercial, high-power 350 mAh graphite/LiNiCoAlO2-LiCoO2 pouch cell and validated by continuous discharge and charge curves at varying temperature. For the first time, the physical background of the model allows the operator to draw conclusions about the performance-limiting factor at various operating conditions. Not only can the model help to choose application-optimized cell characteristics, but it can also support the battery management system when taking corrective actions during operation.

Influence of the Stefan Flow on Heat Transfer in the System "Gas-Solid Particle" in Thermochemical Conversion of a Solid Fuel

NASA Astrophysics Data System (ADS)

Pechenegov, Yu. Ya.; Mrakin, A. N.

2017-09-01

Recommendations are presented on calculating interphase heat transfer in gas-disperse systems of plants for thermochemical conversion of ground solid fuel. An analysis is made of the influence of the gas release of fuel particles on the heat transfer during their heating. It is shown that in the processes of thermal treatment of oil shales, the presence of gas release reduces substantially the intensity of interphase heat transfer compared to the heat transfer in the absence of thermochemical decomposition of the solid phase.

Materials Development for All-Solid-State Battery Electrolytes

NASA Astrophysics Data System (ADS)

Wang, Weimin

Solid electrolytes in all solid-state batteries, provide higher attainable energy density and improved safety. Ideal solid electrolytes require high ionic conductivity, a high elastic modulus to prevent dendrite growth, chemical compatibility with electrodes, and ease of fabrication into thin films. Although various materials types, including polymers, ceramics, and composites, are under intense investigation, unifying design principles have not been identified. In this thesis, we study the key ion transport mechanisms in relation to the structural characteristics of polymers and glassy solids, and apply derived material design strategies to develop polymer-silica hybrid materials with improved electrolyte performance characteristics. Poly(ethylene) oxide-based solid electrolytes containing ceramic nanoparticles are attractive alternatives to liquid electrolytes for high-energy density Li batteries. We compare the effect of Li1.3Al0.3Ti 1.7(PO4)3 active nanoparticles, passive TiO 2 nanoparticles and fumed silica. Up to two orders of magnitude enhancement in ionic conductivity is observed for composites with active nanoparticles, attributed to cation migration through a percolating interphase region that develops around the active nanoparticles, even at low nanoparticle loading. We investigate the structural origin of elastic properties and ionic migration mechanisms in sodium borosilicate and sodium borogermanate glass electrolyte system. A new statistical thermodynamic reaction equilibrium model is used in combination with data from nuclear magnetic resonance and Brillouin light scattering measurements to determine network structural unit fractions. The highly coordinated structural units are found to be predominantly responsible for effective mechanical load transmission, by establishing three-dimensional covalent connectivity. A strong correlation exists between bulk modulus and the activation energy for ion conduction. We describe the activated process in glasses as involving a jump by the migrating cation and transient reversible isotropic displacement of atoms in the immediate vicinity, and express the activation energy as a sum of Coulomb and elastic terms. By fitting our experimental data to this model, we find that the number of affected atoms in the vicinity ranges between 20 and 30. Furthermore, elastic deformations in ion jumping are almost purely hydrostatic and hardly shear. Considering that the energy required for the cation jump is made available by concentrating thermal phonons at the jump site, we establish a relationship between structural stiffness and activation energy. Moreover, the more atoms that partake in the cation jump, the more degrees of freedom for atomic motion can be relied upon to achieve the required net outward expansion to facilitate the passage of the jumping cation, lowering the activation energy. To combine the flexibility of polymers and the good mechanical and electrochemical properties of silica, we use sol-gel methods for fabricating silica-based hybrid organic-inorganic electrolytes. Polyethylene glycol is covalently grafted onto the silica backbone as the organic filler that provides the environment for ion conduction. We developed synthesis methods in which grafting and polycondensation occur concurrently, or the grafting occurs after the silica backbone has formed. Small angle x-ray scattering measurements reveal that different structures are achieved depending on the method used. The two-step procedure allows for a larger amount of conducting polymer to be embedded into network pores than in the one-pot method. This greatly enhances the ionic conductivity without sacrificing mechanical stability afforded by the continuous silica backbone. Here we provide a cumulative account of a systematic materials design efforts, in which we sequentially implement several important design aspects to identify their respective importance and influence on the materials performance characteristics.

Comparative study of imide-based Li salts as electrolyte additives for Li-ion batteries

NASA Astrophysics Data System (ADS)

Sharova, Varvara; Moretti, Arianna; Diemant, Thomas; Varzi, Alberto; Behm, R. Jürgen; Passerini, Stefano

2018-01-01

Herein, we report the results of a detailed study on the use of different Li imide salts (LiTFSI, LiFSI, and LiFTFSI) as electrolyte additives for lithium-ion batteries. The introduction of lithium imide salts in the electrolyte is shown to considerably improve the first cycle coulombic efficiency and the long-term cycling stability of graphite/LiFePO4 cells. Using LiTFSI, a capacity fading of only ∼2% occurred over 600 cycles while the control cell with the state-of-the-art additive (VC) lost ∼20% of the initial capacity at 20 °C. The results of the XPS and impedance spectroscopy measurements of graphite electrodes show that, after the formation cycle, the SEI obtained in the presence of imide salts is thinner, contains more LiF and is less resistive than that obtained using VC. Despite the beneficial effect of the imide salts on the lithium-ion cell performance, a slightly reduced thermal stability of the SEI is observed.

Design of Complex Nanomaterials for Energy Storage: Past Success and Future Opportunity.

PubMed

Liu, Yayuan; Zhou, Guangmin; Liu, Kai; Cui, Yi

2017-12-19

The development of next-generation lithium-based rechargeable batteries with high energy density, low cost, and improved safety is a great challenge with profound technological significance for portable electronics, electric vehicles, and grid-scale energy storage. Specifically, advanced lithium battery chemistries call for a paradigm shift to electrodes with high Li to host ratio based on a conversion or alloying mechanism, where the increased capacity is often accompanied by drastic volumetric changes, significant bond breaking, limited electronic/ionic conductivity, and unstable electrode/electrolyte interphase. Fortunately, the rapid progress of nanotechnology over the past decade has been offering battery researchers effective means to tackle some of the most pressing issues for next-generation battery chemistries. The major applications of nanotechnology in batteries can be summarized as follows: First, by reduction of the dimensions of the electrode materials, the cracking threshold of the material upon lithiation can be overcome, at the same time facilitating electron/ion transport within the electrode. Second, nanotechnology also provides powerful methods to generate various surface-coating and functionalization layers on electrode materials, protecting them from side reactions in the battery environment. Finally, nanotechnology gives people the flexibility to engineer each and every single component within a battery (separator, current collector, etc.), bringing novel functions to batteries that are unachievable by conventional methods. Thus, this Account aims to highlight the crucial role of nanotechnology in advanced battery systems. Because of the limited space, we will mainly assess representative examples of rational nanomaterials design with complexity for silicon and lithium metal anodes, which have shown great promise in constraining their large volume changes and the repeated solid-electrolyte interphase formation during cycling. Noticeably, the roadmap delineating the gradual improvement of silicon anodes with a span of 11 generations of materials designs developed in our group is discussed in order to reflect how nanotechnology could guide battery research step by step toward practical applications. Subsequently, we summarize efforts to construct nanostructured composite sulfur cathodes with improved electronic conductivity and effective soluble species encapsulation for maximizing the utilization of active material, cycle life, and system efficiency. We emphasize carbon-based materials and, importantly, materials with polar surfaces for sulfur entrapment. We then briefly discuss nanomaterials strategies to improve the ionic conductivity of solid polymer electrolytes by means of incorporating high-surface-area and, importantly, high-aspect-ratio secondary-phase fillers for continuous, low-tortuosity ionic transport pathways. Finally, critical innovations that have been brought to the area of grid-scale energy storage and battery safety by nanotechnology are also succinctly reviewed.

Grid Scale Energy Storage (Symposium EE8)

DTIC Science & Technology

2016-06-01

27709-2211 Grid-Scale Energy Storage, electrolytes, systems ntegration, Lithium - ion chemistry, Redox flow batteries REPORT DOCUMENTATION PAGE 11... Lithium - Ion Chemistry (4) Redox Flow Batteries Christopher J. Orendorff from Sandia National Laboratories kicked off the symposium on Tuesday...for redox flow batteries . SEI formation is a well-known process in standard lithium - ion battery operation; however, using aqueous electrolytes does

Modeling Insight into Battery Electrolyte Electrochemical Stability and Interfacial Structure.

PubMed

Borodin, Oleg; Ren, Xiaoming; Vatamanu, Jenel; von Wald Cresce, Arthur; Knap, Jaroslaw; Xu, Kang

2017-12-19

Electroactive interfaces distinguish electrochemistry from chemistry and enable electrochemical energy devices like batteries, fuel cells, and electric double layer capacitors. In batteries, electrolytes should be either thermodynamically stable at the electrode interfaces or kinetically stable by forming an electronically insulating but ionically conducting interphase. In addition to a traditional optimization of electrolytes by adding cosolvents and sacrificial additives to preferentially reduce or oxidize at the electrode surfaces, knowledge of the local electrolyte composition and structure within the double layer as a function of voltage constitutes the basis of manipulating an interphase and expanding the operating windows of electrochemical devices. In this work, we focus on how the molecular-scale insight into the solvent and ion partitioning in the electrolyte double layer as a function of applied potential could predict changes in electrolyte stability and its initial oxidation and reduction reactions. In molecular dynamics (MD) simulations, highly concentrated lithium aqueous and nonaqueous electrolytes were found to exclude the solvent molecules from directly interacting with the positive electrode surface, which provides an additional mechanism for extending the electrolyte oxidation stability in addition to the well-established simple elimination of "free" solvent at high salt concentrations. We demonstrate that depending on their chemical structures, the anions could be designed to preferentially adsorb or desorb from the positive electrode with increasing electrode potential. This provides additional leverage to dictate the order of anion oxidation and to effectively select a sacrificial anion for decomposition. The opposite electrosorption behaviors of bis(trifluoromethane)sulfonimide (TFSI) and trifluoromethanesulfonate (OTF) as predicted by MD simulation in highly concentrated aqueous electrolytes were confirmed by surface enhanced infrared spectroscopy. The proton transfer (H-transfer) reactions between solvent molecules on the cathode surface coupled with solvent oxidation were found to be ubiquitous for common Li-ion electrolyte components and dependent on the local molecular environment. Quantum chemistry (QC) calculations on the representative clusters showed that the majority of solvents such as carbonates, phosphates, sulfones, and ethers have significantly lower oxidation potential when oxidation is coupled with H-transfer, while without H-transfer their oxidation potentials reside well beyond battery operating potentials. Thus, screening of the solvent oxidation limits without considering H-transfer reactions is unlikely to be relevant, except for solvents containing unsaturated functionalities (such as C═C) that oxidize without H-transfer. On the anode, the F-transfer reaction and LiF formation during anion and fluorinated solvent reduction could be enhanced or diminished depending on salt and solvent partitioning in the double layer, again giving an additional tool to manipulate the order of reductive decompositions and interphase chemistry. Combined with experimental efforts, modeling results highlight the promise of interphasial compositional control by either bringing the desired components closer to the electrode surface to facilitate redox reaction or expelling them so that they are kinetically shielded from the potential of the electrode.

Structural, electrical conductivity and dielectric behavior of Na2SO4-LDT composite solid electrolyte.

PubMed

Iqbal, Mohd Z; Rafiuddin

2016-01-01

A series of composite materials of general molecular formula (1 - x) Na2SO4 - (x) LDT was prepared by solid state reaction method. The phase structure and functionalization of these materials were defined by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) respectively. Differential thermal analysis (DTA) revealed that the hump of phase transition at 250 °C has decreased while its thermal stability was enhanced. Scanning electron microscopy signifies the presence of improved rigid surfaces and interphases that are accountable for the high ionic conduction due to dispersion of LDT particles in the composite systems. Arrhenius plots of the conductance show the maximum conductivity, σ = 4.56 × 10(-4) S cm(-1) at 500 °C for the x = 0.4 composition with the lowest activation energy 0.34 eV in the temperature range of 573-773 K. The value of dielectric constant was decreased with increasing frequency and follows the usual trend.

Chemically Bonded Phosphorus/Graphene Hybrid as a High Performance Anode for Sodium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Jiangxuan; Yu, Zhaoxin; Gordin, Mikhail

2014-11-12

Room temperature sodium-ion batteries are of great interest for high-energy-density energy storage systems because of low-cost, natural abundance of sodium. Here, we report a novel graphene nanosheets-wrapped phosphorus composite as an anode for high performance sodium-ion batteries though a facile ball-milling of red phosphorus and graphene nanosheets. Not only can the graphene nanosheets significantly improve the electrical conductivity, but they also serve as a buffer layer to accommodate the large volume change of phosphorus in the charge-discharge process. As a result, the graphene wrapped phosphorus composite anode delivers a high reversible capacity of 2077 mAh/g with excellent cycling stability (1700more » mAh/g after 60 cycles) and high Coulombic efficiency (>98%). This simple synthesis approach and unique nanostructure can potentially extend to other electrode materials with unstable solid electrolyte interphases in sodium-ion batteries.« less

A reversible dendrite-free high-areal-capacity lithium metal electrode

PubMed Central

Wang, Hui; Matsui, Masaki; Kuwata, Hiroko; Sonoki, Hidetoshi; Matsuda, Yasuaki; Shang, Xuefu; Takeda, Yasuo; Yamamoto, Osamu; Imanishi, Nobuyuki

2017-01-01

Reversible dendrite-free low-areal-capacity lithium metal electrodes have recently been revived, because of their pivotal role in developing beyond lithium ion batteries. However, there have been no reports of reversible dendrite-free high-areal-capacity lithium metal electrodes. Here we report on a strategy to realize unprecedented stable cycling of lithium electrodeposition/stripping with a highly desirable areal-capacity (12 mAh cm−2) and exceptional Coulombic efficiency (>99.98%) at high current densities (>5 mA cm−2) and ambient temperature using a diluted solvate ionic liquid. The essence of this strategy, that can drastically improve lithium electrodeposition kinetics by cyclic voltammetry premodulation, lies in the tailoring of the top solid-electrolyte interphase layer in a diluted solvate ionic liquid to facilitate a two-dimensional growth mode. We anticipate that this discovery could pave the way for developing reversible dendrite-free metal anodes for sustainable battery chemistries. PMID:28440299

Confined silicon nanospheres by biomass lignin for stable lithium ion battery.

PubMed

Niu, Xiaoying; Zhou, Jinqiu; Qian, Tao; Wang, Mengfan; Yan, Chenglin

2017-10-06

Biomass lignin, as a significant renewable resource, is one of the most abundant natural polymers in the world. Here, we report a novel silicon-based material, in which lignin-derived functional conformal network crosslinks the silicon nanoparticles via self-assembly. This newly-developed material could greatly solve the problems of large volume change during lithiation/delithiation process and the formation of unstable solid electrolyte interphase layers on the silicon surface. With this anode, the battery demonstrates a high capacity of ∼3000 mA h g -1 , a highly stable cycling retention (∼89% after 100 cycles at 300 mA g -1 ) and an excellent rate capability (∼800 mA h g -1 at 9 A g -1 ). Moreover, the feasibility of full lithium-ion batteries with the novel silicon-based material would provide wide range of applications in the field of flexible energy storage systems for wearable electronic devices.

Confined silicon nanospheres by biomass lignin for stable lithium ion battery

NASA Astrophysics Data System (ADS)

Niu, Xiaoying; Zhou, Jinqiu; Qian, Tao; Wang, Mengfan; Yan, Chenglin

2017-10-01

Biomass lignin, as a significant renewable resource, is one of the most abundant natural polymers in the world. Here, we report a novel silicon-based material, in which lignin-derived functional conformal network crosslinks the silicon nanoparticles via self-assembly. This newly-developed material could greatly solve the problems of large volume change during lithiation/delithiation process and the formation of unstable solid electrolyte interphase layers on the silicon surface. With this anode, the battery demonstrates a high capacity of ˜3000 mA h g-1, a highly stable cycling retention (˜89% after 100 cycles at 300 mA g-1) and an excellent rate capability (˜800 mA h g-1 at 9 A g-1). Moreover, the feasibility of full lithium-ion batteries with the novel silicon-based material would provide wide range of applications in the field of flexible energy storage systems for wearable electronic devices.

Materials Challenges and Opportunities of Lithium-ion Batteries for Electrical Energy Storage

NASA Astrophysics Data System (ADS)

Manthiram, Arumugam

2011-03-01

Electrical energy storage has emerged as a topic of national and global importance with respect to establishing a cleaner environment and reducing the dependence on foreign oil. Batteries are the prime candidates for electrical energy storage. They are the most viable near-term option for vehicle applications and the efficient utilization of intermittent energy sources like solar and wind. Lithium-ion batteries are attractive for these applications as they offer much higher energy density than other rechargeable battery systems. However, the adoption of lithium-ion battery technology for vehicle and stationary storage applications is hampered by high cost, safety concerns, and limitations in energy, power, and cycle life, which are in turn linked to severe materials challenges. This presentation, after providing an overview of the current status, will focus on the physics and chemistry of new materials that can address these challenges. Specifically, it will focus on the design and development of (i) high-capacity, high-voltage layered oxide cathodes, (ii) high-voltage, high-power spinel oxide cathodes, (iii) high-capacity silicate cathodes, and (iv) nano-engineered, high-capacity alloy anodes. With high-voltage cathodes, a critical issue is the instability of the electrolyte in contact with the highly oxidized cathode surface and the formation of solid-electrolyte interfacial (SEI) layers that degrade the performance. Accordingly, surface modification of cathodes with nanostructured materials and self-surface segregation during the synthesis process to suppress SEI layer formation and enhance the energy, power, and cycle life will be emphasized. With the high-capacity alloy anodes, a critical issue is the huge volume change occurring during the charge-discharge process and the consequent poor cycle life. Dispersion of the active alloy nanoparticles in an inactive metal oxide-carbon matrix to mitigate this problem and realize long cycle life will be presented.

Composite Solid Electrolyte For Lithium Cells

NASA Technical Reports Server (NTRS)

Peled, Emmanuel; Nagasubramanian, Ganesan; Halpert, Gerald; Attia, Alan I.

1994-01-01

Composite solid electrolyte material consists of very small particles, each coated with thin layer of Lil, bonded together with polymer electrolyte or other organic binder. Material offers significant advantages over other solid electrolytes in lithium cells and batteries. Features include high ionic conductivity and strength. Composite solid electrolyte expected to exhibit flexibility of polymeric electrolytes. Polymer in composite solid electrolyte serves two purposes: used as binder alone, conduction taking place only in AI2O3 particles coated with solid Lil; or used as both binder and polymeric electrolyte, providing ionic conductivity between solid particles that it binds together.

Improved performance and safety of lithium ion cells with the use of fluorinated carbonate-based electrolytes

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Ryan, V. S.; Surampudi, S.; Prakashi, G. K. S.; Hu, J.; Cheung, I.

2002-01-01

There has been increasing interest in developing lithium-ion electrolytes that possess enhanced safety characteristics, while still able to provide the desired stability and performance. Toward this end, our efforts have been focused on the development of lithium-ion electrolytes which contain partially and fully fluorinated carbonate solvents. The advantage of using such solvents is that they possess the requisite stability demonstrated by the hydrocarbon-based carbonates, while also possessing more desirable physical properties imparted by the presence of the fluorine substituents, such as lower melting points, increased stability toward oxidation, and favorable SEI film forming Characteristics on carbon. Specifically, we have demonstrated the beneficial effect of electrolytes which contain the following fluorinated carbonate-based solvents: methyl 2,2,2-trifluoroethyl carbonate (MTFEC), ethyl-2,2,2 trifluoroethyl carbonate (ETFEC), propyl 2,2,2-trifluoroethyl carbonate (PTFEC), methyl-2,2,2,2',2',2' -hexafluoro-i-propyl carbonate (MHFPC), ethyl- 2,2,2,2',2',2' -hexafluoro-i-propyl carbonate (EHFPC), and di-2,2,2-trifluoroethyl carbonate (DTFEC). These solvents have been incorporated into multi-component ternary and quaternary carbonate-based electrolytes and evaluated in lithium-carbon and carbon-LiNio.8Coo.202 cells (equipped with lithium reference electrodes). In addition to determining the charge/discharge behavior of these cells, a number of electrochemical techniques were employed (i.e., Tafel polarization measurements, linear polarization measurements, and electrochemical impedance spectroscopy (EIS)) to further characterize the performance of these electrolytes, including the SEI formation characteristics and lithium intercalatiodde-intercalation kinetics. In addition to their evaluation in experimental cells, cyclic voltammetry (CV) and conductivity measurements were performed on select electrolyte formulations to further our understanding of the trends in stability and ionic mobility imparted by different alkyl substituents in linear carbonates.

Non-crosslinked, amorphous, block copolymer electrolyte for batteries

DOEpatents

Mayes, Anne M.; Ceder, Gerbrand; Chiang, Yet-Ming; Sadoway, Donald R.; Aydinol, Mehmet K.; Soo, Philip P.; Jang, Young-Il; Huang, Biying

2006-04-11

Solid battery components are provided. A block copolymeric electrolyte is non-crosslinked and non-glassy through the entire range of typical battery service temperatures, that is, through the entire range of at least from about 0.degree. C. to about 70.degree. C. The chains of which the copolymer is made each include at least one ionically-conductive block and at least one second block immiscible with the ionically-conductive block. The chains form an amorphous association and are arranged in an ordered nanostructure including a continuous matrix of amorphous ionically-conductive domains and amorphous second domains that are immiscible with the ionically-conductive domains. A compound is provided that has a formula of Li.sub.xM.sub.yN.sub.zO.sub.2. M and N are each metal atoms or a main group elements, and x, y and z are each numbers from about 0 to about 1. y and z are chosen such that a formal charge on the M.sub.yN.sub.z portion of the compound is (4-x). In certain embodiments, these compounds are used in the cathodes of rechargeable batteries. The present invention also includes methods of predicting the potential utility of metal dichalgogenide compounds for use in lithium intercalation compounds. It also provides methods for processing lithium intercalation oxides with the structure and compositional homogeneity necessary to realize the increased formation energies of said compounds. An article is made of a dimensionally-stable, interpenetrating microstructure of a first phase including a first component and a second phase, immiscible with the first phase, including a second component. The first and second phases define interphase boundaries between them, and at least one particle is positioned between a first phase and a second phase at an interphase boundary. When the first and second phases are electronically-conductive and ionically-conductive polymers, respectively, and the particles are ion host particles, the arrangement is an electrode of a battery.

Optimized Li-Ion Electrolytes Containing Fluorinated Ester Co-Solvents

NASA Technical Reports Server (NTRS)

Prakash, G. K. Surya; Smart, Marshall; Smith, Kiah; Bugga, Ratnakumar

2010-01-01

A number of experimental lithium-ion cells, consisting of MCMB (meso-carbon microbeads) carbon anodes and LiNi(0.8)Co(0.2)O2 cathodes, have been fabricated with increased safety and expanded capability. These cells serve to verify and demonstrate the reversibility, low-temperature performance, and electrochemical aspects of each electrode as determined from a number of electrochemical characterization techniques. A number of Li-ion electrolytes possessing fluorinated ester co-solvents, namely trifluoroethyl butyrate (TFEB) and trifluoroethyl propionate (TFEP), were demonstrated to deliver good performance over a wide temperature range in experimental lithium-ion cells. The general approach taken in the development of these electrolyte formulations is to optimize the type and composition of the co-solvents in ternary and quaternary solutions, focusing upon adequate stability [i.e., EC (ethylene carbonate) content needed for anode passivation, and EMC (ethyl methyl carbonate) content needed for lowering the viscosity and widening the temperature range, while still providing good stability], enhancing the inherent safety characteristics (incorporation of fluorinated esters), and widening the temperature range of operation (the use of both fluorinated and non-fluorinated esters). Further - more, the use of electrolyte additives, such as VC (vinylene carbonate) [solid electrolyte interface (SEI) promoter] and DMAc (thermal stabilizing additive), provide enhanced high-temperature life characteristics. Multi-component electrolyte formulations enhance performance over a temperature range of -60 to +60 C. With the need for more safety with the use of these batteries, flammability was a consideration. One of the solvents investigated, TFEB, had the best performance with improved low-temperature capability and high-temperature resilience. This work optimized the use of TFEB as a co-solvent by developing the multi-component electrolytes, which also contain non-halogenated esters, film forming additives, thermal stabilizing additives, and flame retardant additives. Further optimization of these electrolyte formulations is anticipated to yield improved performance. It is also anticipated that much improved performance will be demonstrated once these electrolyte solutions are incorporated into hermetically sealed, large capacity prototype cells, especially if effort is devoted to ensure that all electrolyte components are highly pure.

Passivation dynamics in the anisotropic deposition and stripping of bulk magnesium electrodes during electrochemical cycling

DOE PAGES

Wetzel, David J.; Malone, Marvin A.; Haasch, Richard T.; ...

2015-08-10

Rechargeable magnesium (Mg) batteries show promise for use as a next generation technology for high-density energy storage, though little is known about the Mg anode solid electrolyte interphase and its implications for the performance and durability of a Mg-based battery. We explore in this report passivation effects engendered during the electrochemical cycling of a bulk Mg anode, characterizing their influences during metal deposition and dissolution in a simple, nonaqueous, Grignard electrolyte solution (ethylmagnesium bromide, EtMgBr, in tetrahydrofuran). Scanning electron microscopy images of Mg foil working electrodes after electrochemical polarization to dissolution potentials show the formation of corrosion pits. The pitmore » densities so evidenced are markedly potential-dependent. When the Mg working electrode is cycled both potentiostatically and galvanostatically in EtMgBr these pits, formed due to passive layer breakdown, act as the foci for subsequent electrochemical activity. Detailed microscopy, diffraction, and spectroscopic data show that further passivation and corrosion results in the anisotropic stripping of the Mg {0001} plane, leaving thin oxide-comprising passivated side wall structures that demark the {0001} fiber texture of the etched Mg grains. Upon long-term cycling, oxide side walls formed due to the pronounced crystallographic anisotropy of the anodic stripping processes, leading to complex overlay anisotropic, columnar structures, exceeding 50 μm in height. Finally, the passive responses mediating the growth of these structures appear to be an intrinsic feature of the electrochemical growth and dissolution of Mg using this electrolyte.« less

Passivation dynamics in the anisotropic deposition and stripping of bulk magnesium electrodes during electrochemical cycling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetzel, David J.; Malone, Marvin A.; Haasch, Richard T.

Rechargeable magnesium (Mg) batteries show promise for use as a next generation technology for high-density energy storage, though little is known about the Mg anode solid electrolyte interphase and its implications for the performance and durability of a Mg-based battery. We explore in this report passivation effects engendered during the electrochemical cycling of a bulk Mg anode, characterizing their influences during metal deposition and dissolution in a simple, nonaqueous, Grignard electrolyte solution (ethylmagnesium bromide, EtMgBr, in tetrahydrofuran). Scanning electron microscopy images of Mg foil working electrodes after electrochemical polarization to dissolution potentials show the formation of corrosion pits. The pitmore » densities so evidenced are markedly potential-dependent. When the Mg working electrode is cycled both potentiostatically and galvanostatically in EtMgBr these pits, formed due to passive layer breakdown, act as the foci for subsequent electrochemical activity. Detailed microscopy, diffraction, and spectroscopic data show that further passivation and corrosion results in the anisotropic stripping of the Mg {0001} plane, leaving thin oxide-comprising passivated side wall structures that demark the {0001} fiber texture of the etched Mg grains. Upon long-term cycling, oxide side walls formed due to the pronounced crystallographic anisotropy of the anodic stripping processes, leading to complex overlay anisotropic, columnar structures, exceeding 50 μm in height. Finally, the passive responses mediating the growth of these structures appear to be an intrinsic feature of the electrochemical growth and dissolution of Mg using this electrolyte.« less

Passivation Dynamics in the Anisotropic Deposition and Stripping of Bulk Magnesium Electrodes During Electrochemical Cycling.

PubMed

Wetzel, David J; Malone, Marvin A; Haasch, Richard T; Meng, Yifei; Vieker, Henning; Hahn, Nathan T; Gölzhäuser, Armin; Zuo, Jian-Min; Zavadil, Kevin R; Gewirth, Andrew A; Nuzzo, Ralph G

2015-08-26

Although rechargeable magnesium (Mg) batteries show promise for use as a next generation technology for high-density energy storage, little is known about the Mg anode solid electrolyte interphase and its implications for the performance and durability of a Mg-based battery. We explore in this report passivation effects engendered during the electrochemical cycling of a bulk Mg anode, characterizing their influences during metal deposition and dissolution in a simple, nonaqueous, Grignard electrolyte solution (ethylmagnesium bromide, EtMgBr, in tetrahydrofuran). Scanning electron microscopy images of Mg foil working electrodes after electrochemical polarization to dissolution potentials show the formation of corrosion pits. The pit densities so evidenced are markedly potential-dependent. When the Mg working electrode is cycled both potentiostatically and galvanostatically in EtMgBr these pits, formed due to passive layer breakdown, act as the foci for subsequent electrochemical activity. Detailed microscopy, diffraction, and spectroscopic data show that further passivation and corrosion results in the anisotropic stripping of the Mg {0001} plane, leaving thin oxide-comprising passivated side wall structures that demark the {0001} fiber texture of the etched Mg grains. Upon long-term cycling, oxide side walls formed due to the pronounced crystallographic anisotropy of the anodic stripping processes, leading to complex overlay anisotropic, columnar structures, exceeding 50 μm in height. The passive responses mediating the growth of these structures appear to be an intrinsic feature of the electrochemical growth and dissolution of Mg using this electrolyte.

Electrochemical Stability of Li 10GeP 2S 12 and Li 7La 3Zr 2O 12 Solid Electrolytes

DOE PAGES

Han, Fudong; Zhu, Yizhou; He, Xingfeng; ...

2016-01-21

The electrochemical stability window of solid electrolyte is overestimated by the conventional experimental method using a Li/electrolyte/inert metal semiblocking electrode because of the limited contact area between solid electrolyte and inert metal. Since the battery is cycled in the overestimated stability window, the decomposition of the solid electrolyte at the interfaces occurs but has been ignored as a cause for high interfacial resistances in previous studies, limiting the performance improvement of the bulk-type solid-state battery despite the decades of research efforts. Thus, there is an urgent need to identify the intrinsic stability window of the solid electrolyte. The thermodynamic electrochemicalmore » stability window of solid electrolytes is calculated using first principles computation methods, and an experimental method is developed to measure the intrinsic electrochemical stability window of solid electrolytes using a Li/electrolyte/electrolyte-carbon cell. The most promising solid electrolytes, Li10GeP2S12 and cubic Li-garnet Li7La3Zr2O12, are chosen as the model materials for sulfide and oxide solid electrolytes, respectively. The results provide valuable insights to address the most challenging problems of the interfacial stability and resistance in high-performance solid-state batteries.« less

Effects of Cesium Cations in Lithium Deposition via Self-Healing Electrostatic Shield Mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Fei; Xu, Wu; Chen, Xilin

Lithium (Li) dendrite formation is one of the critical challenges for rechargeable Li metal batteries. The traditional method to suppress Li dendrites by using high-quality solid electrolyte interface (SEI) films cannot effectively solve this problem. Recently, we proposed a novel self-healing electrostatic shield (SHES) mechanism to change the Li deposition behavior. The SHES mechanism forces Li to be deposited in the region away from protuberant tips by using non-Li cations as additives that preferentially accumulate but not deposit on the active sites of Li electrode. In this paper, the electrochemical behavior of cesium cation (Cs+) as the typical non-Li cationmore » suitable for the SHES mechanism was further investigated in detail to reveal its effects on preventing Li dendrites and interactions with Li electrode. It is found that typical adsorption behavior instead of chemical reaction is observed. The existence of Cs+ cation in the electrolyte does not change the components and structure of the Li surface film and this is consistent with the projection of the SHES mechanism. Various factors affecting the effectiveness of SHES mechanism are also discussed. The morphologies of Li films deposited is smooth and uniform during the repeated deposition-stripping cycles and at various current densities (from 0.1 to 1.0 mA cm-2) by adding just a small amount (0.05 M) of Cs+-additive in the electrolyte.« less

Process to produce lithium-polymer batteries

DOEpatents

MacFadden, Kenneth Orville

1998-01-01

A polymer bonded sheet product suitable for use as an electrode in a non-aqueous battery system. A porous electrode sheet is impregnated with a solid polymer electrolyte, so as to diffuse into the pores of the electrode. The composite is allowed to cool, and the electrolyte is entrapped in the porous electrode. The sheet products composed have the solid polymer electrolyte composition diffused into the active electrode material by melt-application of the solid polymer electrolyte composition into the porous electrode material sheet. The solid polymer electrolyte is maintained at a temperature that allows for rapid diffusion into the pores of the electrode. The composite electrolyte-electrode sheets are formed on current collectors and can be coated with solid polymer electrolyte prior to battery assembly. The interface between the solid polymer electrolyte composite electrodes and the solid polymer electrolyte coating has low resistance.

Bacteria Absorption-Based Mn2P2O7-Carbon@Reduced Graphene Oxides for High-Performance Lithium-Ion Battery Anodes.

PubMed

Yang, Yuhua; Wang, Bin; Zhu, Jingyi; Zhou, Jun; Xu, Zhi; Fan, Ling; Zhu, Jian; Podila, Ramakrishna; Rao, Apparao M; Lu, Bingan

2016-05-24

The development of freestanding flexible electrodes with high capacity and long cycle-life is a central issue for lithium-ion batteries (LIBs). Here, we use bacteria absorption of metallic Mn(2+) ions to in situ synthesize natural micro-yolk-shell-structure Mn2P2O7-carbon, followed by the use of vacuum filtration to obtain Mn2P2O7-carbon@reduced graphene oxides (RGO) papers for LIBs anodes. The Mn2P2O7 particles are completely encapsulated within the carbon film, which was obtained by carbonizing the bacterial wall. The resulting carbon microstructure reduces the electrode-electrolyte contact area, yielding high Coulombic efficiency. In addition, the yolk-shell structure with its internal void spaces is ideal for sustaining volume expansion of Mn2P2O7 during charge/discharge processes, and the carbon shells act as an ideal barrier, limiting most solid-electrolyte interphase formation on the surface of the carbon films (instead of forming on individual particles). Notably, the RGO films have high conductivity and robust mechanical flexibility. As a result of our combined strategies delineated in this article, our binder-free flexible anodes exhibit high capacities, long cycle-life, and excellent rate performance.

Interphase Transformations at Metal (Copper, Iron)-Polymer Gel-Electrolyte Interfaces

NASA Astrophysics Data System (ADS)

Lyamina, G. V.; Dubinina, O. V.; Vaitulevich, E. A.; Mokrousov, G. M.

2018-07-01

The results from studies of the interface boundaries between metals (copper and iron) and gel electrolyte based on methacrylic copolymers are organized systematically. In contrast to processes in liquid electrolytes, a number of key features of the reactions that occur at such interfaces are revealed: a diffusion limiting stage; a lack of reverse reactions; and the formation of coordination compounds of metal ions with the functional groups of polymers, the stabilities of which are several orders of magnitude greater than that of coordination with their low-molecular weight counterparts. It is shown that processes which employ polymeric organogels can be used for the careful cleaning of the metal surfaces, and for the formation of a desired phase composition on the latter.

Bivalence Mn5O8 with hydroxylated interphase for high-voltage aqueous sodium-ion storage

PubMed Central

Shan, Xiaoqiang; Charles, Daniel S.; Lei, Yinkai; Qiao, Ruimin; Wang, Guofeng; Yang, Wanli; Feygenson, Mikhail; Su, Dong; Teng, Xiaowei

2016-01-01

Aqueous electrochemical energy storage devices have attracted significant attention owing to their high safety, low cost and environmental friendliness. However, their applications have been limited by a narrow potential window (∼1.23 V), beyond which the hydrogen and oxygen evolution reactions occur. Here we report the formation of layered Mn5O8 pseudocapacitor electrode material with a well-ordered hydroxylated interphase. A symmetric full cell using such electrodes demonstrates a stable potential window of 3.0 V in an aqueous electrolyte, as well as high energy and power performance, nearly 100% coulombic efficiency and 85% energy efficiency after 25,000 charge–discharge cycles. The interplay between hydroxylated interphase on the surface and the unique bivalence structure of Mn5O8 suppresses the gas evolution reactions, offers a two-electron charge transfer via Mn2+/Mn4+ redox couple, and provides facile pathway for Na-ion transport via intra-/inter-layer defects of Mn5O8. PMID:27845345

Bivalence Mn5O8 with hydroxylated interphase for high-voltage aqueous sodium-ion storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shan, Xiaoqiang; Charles, Daniel S.; Lei, Yinkai

Aqueous electrochemical energy storage devices have attracted significant attention owing to their high safety, low cost, and environmental friendliness. However, their applications have been limited by a narrow potential window (~1.23 V), beyond which the hydrogen and oxygen evolution reactions occur. Here, we report the formation of layered Mn 5O 8 pseudocapacitor electrode material with a well ordered hydroxylated interphase. A symmetric full cell using such electrodes demonstrates a stable potential window of 3.0 V in an aqueous electrolyte, as well as high energy and power performance, nearly 100% coulombic efficiency and 85% energy efficiency after 25,000 charge-discharge cycles. Furthermore,more » the interplay between hydroxylated interphase on the surface and the unique bivalence structure of Mn 5O 8 suppresses the gas evolution reactions, offers a two-electron charge transfer via Mn 2+/Mn 4+ redox couple, and provides facile pathway for Na-ion transport via intra-/inter-layer defects of Mn 5O 8.« less

Bivalence Mn5O8 with hydroxylated interphase for high-voltage aqueous sodium-ion storage

DOE PAGES

Shan, Xiaoqiang; Charles, Daniel S.; Lei, Yinkai; ...

2016-11-15

Aqueous electrochemical energy storage devices have attracted significant attention owing to their high safety, low cost, and environmental friendliness. However, their applications have been limited by a narrow potential window (~1.23 V), beyond which the hydrogen and oxygen evolution reactions occur. Here, we report the formation of layered Mn 5O 8 pseudocapacitor electrode material with a well ordered hydroxylated interphase. A symmetric full cell using such electrodes demonstrates a stable potential window of 3.0 V in an aqueous electrolyte, as well as high energy and power performance, nearly 100% coulombic efficiency and 85% energy efficiency after 25,000 charge-discharge cycles. Furthermore,more » the interplay between hydroxylated interphase on the surface and the unique bivalence structure of Mn 5O 8 suppresses the gas evolution reactions, offers a two-electron charge transfer via Mn 2+/Mn 4+ redox couple, and provides facile pathway for Na-ion transport via intra-/inter-layer defects of Mn 5O 8.« less

Scalable Synthesis of Defect Abundant Si Nanorods for High-Performance Li-Ion Battery Anodes.

PubMed

Wang, Jing; Meng, Xiangcai; Fan, Xiulin; Zhang, Wenbo; Zhang, Hongyong; Wang, Chunsheng

2015-06-23

Microsized nanostructured silicon-carbon composite is a promising anode material for high energy Li-ion batteries. However, large-scale synthesis of high-performance nano-Si materials at a low cost still remains a significant challenge. We report a scalable low cost method to synthesize Al/Na-doped and defect-abundant Si nanorods that have excellent electrochemical performance with high first-cycle Coulombic efficiency (90%). The unique Si nanorods are synthesized by acid etching the refined and rapidly solidified eutectic Al-Si ingot. To maintain the high electronic conductivity, a thin layer of carbon is then coated on the Si nanorods by carbonization of self-polymerized polydopamine (PDA) at 800 °C. The carbon coated Si nanorods (Si@C) electrode at 0.9 mg cm(-2) loading (corresponding to area-specific-capacity of ∼2.0 mAh cm(-2)) exhibits a reversible capacity of ∼2200 mAh g(-1) at 100 mA g(-1) current, and maintains ∼700 mAh g(-1) over 1000 cycles at 1000 mA g(-1) with a capacity decay rate of 0.02% per cycle. High Coulombic efficiencies of 87% in the first cycle and ∼99.7% after 5 cycles are achieved due to the formation of an artificial Al2O3 solid electrolyte interphase (SEI) on the Si surface, and the low surface area (31 m(2) g(-1)), which has never been reported before for nano-Si anodes. The excellent electrochemical performance results from the massive defects (twins, stacking faults, dislocations) and Al/Na doping in Si nanorods induced by rapid solidification and Na salt modifications; this greatly enhances the robustness of Si from the volume changes and alleviates the mechanical stress/strain of the Si nanorods during the lithium insertion/extraction process. Introducing massive defects and Al/Na doping in eutectic Si nanorods for Li-ion battery anodes is unexplored territory. We venture this uncharted territory to commercialize this nanostructured Si anode for the next generation of Li-ion batteries.

Process to produce lithium-polymer batteries

DOEpatents

MacFadden, K.O.

1998-06-30

A polymer bonded sheet product is described suitable for use as an electrode in a non-aqueous battery system. A porous electrode sheet is impregnated with a solid polymer electrolyte, so as to diffuse into the pores of the electrode. The composite is allowed to cool, and the electrolyte is entrapped in the porous electrode. The sheet products composed have the solid polymer electrolyte composition diffused into the active electrode material by melt-application of the solid polymer electrolyte composition into the porous electrode material sheet. The solid polymer electrolyte is maintained at a temperature that allows for rapid diffusion into the pores of the electrode. The composite electrolyte-electrode sheets are formed on current collectors and can be coated with solid polymer electrolyte prior to battery assembly. The interface between the solid polymer electrolyte composite electrodes and the solid polymer electrolyte coating has low resistance. 1 fig.

A self-forming composite electrolyte for solid-state sodium battery with ultra-long cycle life

DOE PAGES

Zhang, Zhizhen; Yang, Xiao -Qing; Zhang, Qinghua; ...

2016-10-31

Replacing organic liquid electrolyte with inorganic solid electrolytes (SE) can potentially address the inherent safety problems in conventional rechargeable batteries. Furthermore, all-solid-state batteries have been plagues by the relatively low ionic conductivity of solid electrolytes and large charge-transfer resistance resulted from solid-solid interfaces between electrode materials and solid electrolytes. Here we report a new design strategy for improving the ionic conductivity of solid electrolyte by self-forming a composite material. An optimized Na + ion conducting composite electrolyte derived from the NASICON structure was successfully synthesized, yielding ultra-high ionic conductivity of 3.4 mS cm –1 at 25°C and 14 ms cmmore » –1 at 80°C.« less

Beneficial effect of added water on sodium metal cycling in super concentrated ionic liquid sodium electrolytes

NASA Astrophysics Data System (ADS)

Basile, Andrew; Ferdousi, Shammi A.; Makhlooghiazad, Faezeh; Yunis, Ruhamah; Hilder, Matthias; Forsyth, Maria; Howlett, Patrick C.

2018-03-01

The plating and stripping performance of sodium metal in an ionic liquid electrolyte is improved when including water as an additive. Herein we report for the first time the trend of improved cycling behavior of Na0/+ in N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide with 500 ppm H2O. The addition of water to this ionic liquid electrolyte promotes the breakdown of the [FSI]- anion towards beneficial SEI formation. The benefits during plating and stripping of sodium is observed as lower total polarization during symmetrical cell cycling and decreased electrode/electrolyte interface impedance. Sodium metal surfaces after cycling with 500 ppm H2O are shown to be smooth in morphology in comparison to lower additive concentrations. The outcome of adventitious moisture benefiting Na0/+ cycling in an ionic liquid, contrary to conventional electrolytes, allows flexibility in ionic liquid electrolyte design to the benefit of battery manufacturers.

3D-Printing Electrolytes for Solid-State Batteries.

PubMed

McOwen, Dennis W; Xu, Shaomao; Gong, Yunhui; Wen, Yang; Godbey, Griffin L; Gritton, Jack E; Hamann, Tanner R; Dai, Jiaqi; Hitz, Gregory T; Hu, Liangbing; Wachsman, Eric D

2018-05-01

Solid-state batteries have many enticing advantages in terms of safety and stability, but the solid electrolytes upon which these batteries are based typically lead to high cell resistance. Both components of the resistance (interfacial, due to poor contact with electrolytes, and bulk, due to a thick electrolyte) are a result of the rudimentary manufacturing capabilities that exist for solid-state electrolytes. In general, solid electrolytes are studied as flat pellets with planar interfaces, which minimizes interfacial contact area. Here, multiple ink formulations are developed that enable 3D printing of unique solid electrolyte microstructures with varying properties. These inks are used to 3D-print a variety of patterns, which are then sintered to reveal thin, nonplanar, intricate architectures composed only of Li 7 La 3 Zr 2 O 12 solid electrolyte. Using these 3D-printing ink formulations to further study and optimize electrolyte structure could lead to solid-state batteries with dramatically lower full cell resistance and higher energy and power density. In addition, the reported ink compositions could be used as a model recipe for other solid electrolyte or ceramic inks, perhaps enabling 3D printing in related fields. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polyethylene oxide film coating enhances lithium cycling efficiency of an anode-free lithium-metal battery.

PubMed

Assegie, Addisu Alemayehu; Cheng, Ju-Hsiang; Kuo, Li-Ming; Su, Wei-Nien; Hwang, Bing-Joe

2018-03-29

The practical implementation of an anode-free lithium-metal battery with promising high capacity is hampered by dendrite formation and low coulombic efficiency. Most notably, these challenges stem from non-uniform lithium plating and unstable SEI layer formation on the bare copper electrode. Herein, we revealed the homogeneous deposition of lithium and effective suppression of dendrite formation using a copper electrode coated with a polyethylene oxide (PEO) film in an electrolyte comprising 1 M LiTFSI, DME/DOL (1/1, v/v) and 2 wt% LiNO3. More importantly, the PEO film coating promoted the formation of a thin and robust SEI layer film by hosting lithium and regulating the inevitable reaction of lithium with the electrolyte. The modified electrode exhibited stable cycling of lithium with an average coulombic efficiency of ∼100% over 200 cycles and low voltage hysteresis (∼30 mV) at a current density of 0.5 mA cm-2. Moreover, we tested the anode-free battery experimentally by integrating it with an LiFePO4 cathode into a full-cell configuration (Cu@PEO/LiFePO4). The new cell demonstrated stable cycling with an average coulombic efficiency of 98.6% and capacity retention of 30% in the 200th cycle at a rate of 0.2C. These impressive enhancements in cycle life and capacity retention result from the synergy of the PEO film coating, high electrode-electrolyte interface compatibility, stable polar oligomer formation from the reduction of 1,3-dioxolane and the generation of SEI-stabilizing nitrite and nitride upon lithium nitrate reduction. Our result opens up a new route to realize anode-free batteries by modifying the copper anode with PEO to achieve ever more demanding yet safe interfacial chemistry and control of dendrite formation.

Superior Blends Solid Polymer Electrolyte with Integrated Hierarchical Architectures for All-Solid-State Lithium-Ion Batteries.

PubMed

Zhang, Dechao; Zhang, Long; Yang, Kun; Wang, Hongqiang; Yu, Chuang; Xu, Di; Xu, Bo; Wang, Li-Min

2017-10-25

Exploration of advanced solid electrolytes with good interfacial stability toward electrodes is a highly relevant research topic for all-solid-state batteries. Here, we report PCL/SN blends integrating with PAN-skeleton as solid polymer electrolyte prepared by a facile method. This polymer electrolyte with hierarchical architectures exhibits high ionic conductivity, large electrochemical windows, high degree flexibility, good flame-retardance ability, and thermal stability (workable at 80 °C). Additionally, it demonstrates superior compatibility and electrochemical stability toward metallic Li as well as LiFePO 4 cathode. The electrolyte/electrode interfaces are very stable even subjected to 4.5 V at charging state for long time. The LiFePO 4 /Li all-solid-state cells based on this electrolyte deliver high capacity, outstanding cycling stability, and superior rate capability better than those based on liquid electrolyte. This solid polymer electrolyte is eligible for next generation high energy density all-solid-state batteries.

Chemical Passivation of Li(exp +)-Conducting Solid Electrolytes

NASA Technical Reports Server (NTRS)

West, William; Whitacre, Jay; Lim, James

2008-01-01

Plates of a solid electrolyte that exhibits high conductivity for positive lithium ions can now be passivated to prevent them from reacting with metallic lithium. Such passivation could enable the construction and operation of high-performance, long-life lithium-based rechargeable electrochemical cells containing metallic lithium anodes. The advantage of this approach, in comparison with a possible alternative approach utilizing lithium-ion graphitic anodes, is that metallic lithium anodes could afford significantly greater energy-storage densities. A major impediment to the development of such cells has been the fact that the available solid electrolytes having the requisite high Li(exp +)-ion conductivity are too highly chemically reactive with metallic lithium to be useful, while those solid electrolytes that do not react excessively with metallic lithium have conductivities too low to be useful. The present passivation method exploits the best features of both extremes of the solid-electrolyte spectrum. The basic idea is to coat a higher-conductivity, higher-reactivity solid electrolyte with a lower-conductivity, lower-reactivity solid electrolyte. One can then safely deposit metallic lithium in contact with the lower-reactivity solid electrolyte without incurring the undesired chemical reactions. The thickness of the lower-reactivity electrolyte must be great enough to afford the desired passivation but not so great as to contribute excessively to the electrical resistance of the cell. The feasibility of this method was demonstrated in experiments on plates of a commercial high-performance solid Li(exp +)- conducting electrolyte. Lithium phosphorous oxynitride (LiPON) was the solid electrolyte used for passivation. LiPON-coated solid-electrolyte plates were found to support electrochemical plating and stripping of Li metal. The electrical resistance contributed by the LiPON layers were found to be small relative to overall cell impedances.

Polymer-Derived Ceramic Functionalized MoS2 Composite Paper as a Stable Lithium-Ion Battery Electrode

NASA Astrophysics Data System (ADS)

David, L.; Bhandavat, R.; Barrera, U.; Singh, G.

2015-04-01

A facile process is demonstrated for the synthesis of layered SiCN-MoS2 structure via pyrolysis of polysilazane functionalized MoS2 flakes. The layered morphology and polymer to ceramic transformation on MoS2 surfaces was confirmed by use of electron microscopy and spectroscopic techniques. Tested as thick film electrode in a Li-ion battery half-cell, SiCN-MoS2 showed the classical three-stage reaction with improved cycling stability and capacity retention than neat MoS2. Contribution of conversion reaction of Li/MoS2 system on overall capacity was marginally affected by the presence of SiCN while Li-irreversibility arising from electrolyte decomposition was greatly suppressed. This is understood as one of the reasons for decreased first cycle loss and increased capacity retention. SiCN-MoS2 in the form of self-supporting paper electrode (at 6 mg.cm-2) exhibited even better performance, regaining initial charge capacity of approximately 530 mAh.g-1 when the current density returned to 100 mA.g-1 after continuous cycling at 2400 mA.g-1 (192 mAh.g-1). MoS2 cycled electrode showed mud-cracks and film delamination whereas SiCN-MoS2 electrodes were intact and covered with a uniform solid electrolyte interphase coating. Taken together, our results suggest that molecular level interfacing with precursor-derived SiCN is an effective strategy for suppressing the metal-sulfide/electrolyte degradation reaction at low discharge potentials.

Rechargeable solid polymer electrolyte battery cell

DOEpatents

Skotheim, Terji

1985-01-01

A rechargeable battery cell comprising first and second electrodes sandwiching a solid polymer electrolyte comprising a layer of a polymer blend of a highly conductive polymer and a solid polymer electrolyte adjacent said polymer blend and a layer of dry solid polymer electrolyte adjacent said layer of polymer blend and said second electrode.

Electro-Analytical Study of Material Interfaces Relevant for Chemical Mechanical Planarization and Lithium Ion Batteries

NASA Astrophysics Data System (ADS)

Turk, Michael C.

This dissertation work involves two areas of experimental research, focusing specifically on the applications of electro-analytical techniques for interfacial material characterization. The first area of the work is centered on the evaluation and characterization of material components used for chemical mechanical planarization (CMP) in the fabrication of semiconductor devices. This part also represents the bulk of the projects undertaken for the present dissertation. The other area of research included here involves exploratory electrochemical studies of certain electrolyte and electrode materials for applications in the development of advanced lithium ion secondary batteries. The common element between the two areas of investigation is the technical approach that combines a broad variety of electro-analytical characterization techniques to examine application specific functions of the associated materials and devices. The CMP related projects concentrate on designing and evaluating materials for CMP slurries that would be useful in the processing of copper interconnects for the sub-22 nm technology node. Specifically, ruthenium and cobalt are nontraditional barrier materials currently considered for the new interconnects. The CMP schemes used to process the structures based on these metals involve complex surface chemistries of Ru, Co and Cu (used for wiring lines). The strict requirement of defect-control while maintaining material removal by precisely regulated tribo-corrosion complicates the designs of the CMP slurries needed to process these systems. Since Ru is electrochemically more noble than Cu, the surface regions of Cu assembled in contact with Ru tend to generate defects due to galvanic corrosion in the CMP environment. At the same time, Co is strongly reactive in the typical slurry environment and is prone to developing galvanic corrosion induced by Cu. The present work explores a selected class of alkaline slurry formulations aimed at reducing these galvanic corrosions in chemically controlled low-pressure CMP. The CMP specific functions of the slurry components are characterized in the tribo-electro-analytical approach by using voltammetry, open circuit potential (OCP) measurements and electrochemical impedance spectroscopy (EIS) in the presence as well as in the absence of surface abrasion, both with and without the inclusion of colloidal silica (SiO2) abrasives. The results are used to understand the reaction mechanisms responsible for supporting material removal and corrosion suppression. The project carried out in the area of Li ion batteries (LIBs) uses electro-analytical techniques to probe electrolyte characteristics as well as electrode material performance. The investigation concentrates on optimizing a tactically chosen set of electrolyte compositions for low-to-moderate temperature applications of lithium titanium oxide (LTO), a relatively new anode material for such batteries. For this application, mixtures of non-aqueous carbonate based solvents are studied in combination with lithium perchlorate. The temperature dependent conductivities of the electrolytes are rigorously measured and analyzed using EIS. The experimental considerations and the working principle of this EIS based approach are carefully examined and standardized in the course of this study. These experiments also investigate the effects of temperature variations (below room temperature) on the solid electrolyte interphase (SEI) formation characteristics of LTO in the given electrolytes. This dissertation is organized as follows: Each experimental system and its relevance for practical applications are briefly introduced in each chapter. The experimental approach and the motivation for carrying out the investigation are also noted in that context. The experimental details specific to the particular study are described. This is followed by the results and their discussion, and subsequently, by the specific conclusions drawn from the given set of experiments. A general summary of the obtained results is presented at the end of the dissertation. Possible extensions of the present studies have also been briefly noted there.

Continuous process to produce lithium-polymer batteries

DOEpatents

Chern, Terry Song-Hsing; Keller, David Gerard; MacFadden, Kenneth Orville

1998-01-01

Solid polymer electrolytes are extruded with active electrode material in a continuous, one-step process to form composite electrolyte-electrodes ready for assembly into battery cells. The composite electrolyte-electrode sheets are extruded onto current collectors to form electrodes. The composite electrodes, as extruded, are electronically and ionically conductive. The composite electrodes can be overcoated with a solid polymer electrolyte, which acts as a separator upon battery assembly. The interface between the solid polymer electrolyte composite electrodes and the solid polymer electrolyte separator has low resistance.

Quantification and modeling of mechanical degradation in lithium-ion batteries based on nanoscale imaging.

PubMed

Müller, Simon; Pietsch, Patrick; Brandt, Ben-Elias; Baade, Paul; De Andrade, Vincent; De Carlo, Francesco; Wood, Vanessa

2018-06-14

Capacity fade in lithium-ion battery electrodes can result from a degradation mechanism in which the carbon black-binder network detaches from the active material. Here we present two approaches to visualize and quantify this detachment and use the experimental results to develop and validate a model that considers how the active particle size, the viscoelastic parameters of the composite electrode, the adhesion between the active particle and the carbon black-binder domain, and the solid electrolyte interphase growth rate impact detachment and capacity fade. Using carbon-silicon composite electrodes as a model system, we demonstrate X-ray nano-tomography and backscatter scanning electron microscopy with sufficient resolution and contrast to segment the pore space, active particles, and carbon black-binder domain and quantify delamination as a function of cycle number. The validated model is further used to discuss how detachment and capacity fade in high-capacity materials can be minimized through materials engineering.

Electrochemical properties of chemically processed SiO x as coating material in lithium-ion batteries with Si anode.

PubMed

Jeong, Hee-June; Yang, Hyeon-Woo; Yun, Kang-Seop; Noh, Eul; Jung, Sang-Chul; Kang, Wooseung; Kim, Sun-Jae

2014-01-01

A SiO x coating material for Si anode in lithium-ion battery was processed by using SiCl4 and ethylene glycol. The produced SiO x particles after heat treatment at 725°C for 1 h were porous and irregularly shaped with amorphous structure. Pitch carbon added to SiO x was found to strongly affect solid electrolyte interphase stabilization and cyclic stability. When mixed with an optimal amount of 30 wt% pitch carbon, the SiO x showed a high charge/discharge cyclic stability of about 97% for the 2nd to the 50th cycle. The initial specific capacity of the SiO x was measured to be 1401 mAh/g. On the basis of the evaluation of the SiO x coating material, the process utilized in this study is considered an efficient method to produce SiO x with high performance in an economical way.

Electrochemical Properties of Chemically Processed SiOx as Coating Material in Lithium-Ion Batteries with Si Anode

PubMed Central

Jeong, Hee-June; Yang, Hyeon-Woo; Yun, Kang-Seop; Noh, Eul; Kang, Wooseung

2014-01-01

A SiOx coating material for Si anode in lithium-ion battery was processed by using SiCl4 and ethylene glycol. The produced SiOx particles after heat treatment at 725°C for 1 h were porous and irregularly shaped with amorphous structure. Pitch carbon added to SiOx was found to strongly affect solid electrolyte interphase stabilization and cyclic stability. When mixed with an optimal amount of 30 wt% pitch carbon, the SiOx showed a high charge/discharge cyclic stability of about 97% for the 2nd to the 50th cycle. The initial specific capacity of the SiOx was measured to be 1401 mAh/g. On the basis of the evaluation of the SiOx coating material, the process utilized in this study is considered an efficient method to produce SiOx with high performance in an economical way. PMID:25050401

Systematic Effect for an Ultralong Cycle Lithium-Sulfur Battery.

PubMed

Wu, Feng; Ye, Yusheng; Chen, Renjie; Qian, Ji; Zhao, Teng; Li, Li; Li, Wenhui

2015-11-11

Rechargeable lithium-sulfur (Li-S) batteries are attractive candidates for energy storage devices because they have five times the theoretical energy storage of state-of-the-art Li-ion batteries. The main problems plaguing Li-S batteries are poor cycle life and limited rate capability, caused by the insulating nature of S and the shuttle effect associated with the dissolution of intermediate lithium polysulfides. Here, we report the use of biocell-inspired polydopamine (PD) as a coating agent on both the cathode and separator to address these problems (the "systematic effects"). The PD-modified cathode and separator play key roles in facilitating ion diffusion and keeping the cathode structure stable, leading to uniform lithium deposition and a solid electrolyte interphase. As a result, an ultralong cycle performance of more than 3000 cycles, with a capacity fade of only 0.018% per cycle, was achieved at 2 C. It is believed that the systematic modification of the cathode and separator for Li-S batteries is a new strategy for practical applications.

Mechanistic Study of Electrolyte Additives to Stabilize High-Voltage Cathode-Electrolyte Interface in Lithium-Ion Batteries.

PubMed

Gao, Han; Maglia, Filippo; Lamp, Peter; Amine, Khalil; Chen, Zonghai

2017-12-27

Current developments of electrolyte additives to stabilize electrode-electrolyte interface in lithium-ion batteries highly rely on a trial-and-error search, which involves repetitive testing and intensive amount of resources. The lack of understandings on the fundamental protection mechanisms of the additives significantly increases the difficulty for the transformational development of new additives. In this study, we investigated two types of individual protection routes to build a robust cathode-electrolyte interphase at high potentials: (i) a direct reduction in the catalytic decomposition of the electrolyte solvent; and (ii) formation of a "corrosion inhibitor film" that prevents severely attack and passivation from protons that generated from the solvent oxidation, even the decomposition of solvent cannot be mitigated. Effect of two exemplary electrolyte additives, lithium difluoro(oxalato)borate (LiDFOB) and 3-hexylthiophene (3HT), on LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC 622) cathode were investigated to validate our hypothesis. It is demonstrated that understandings of both electrolyte additives and solvent are essential and careful balance between the cathode protection mechanism of additives and their side effects is critical to obtain optimum results. More importantly, this study opens up new directions of rational design of functional electrolyte additives for the next-generation high-energy-density lithium-ion chemistries.

In Situ Real-Time Mechanical and Morphological Characterization of Electrodes for Electrochemical Energy Storage and Conversion by Electrochemical Quartz Crystal Microbalance with Dissipation Monitoring.

PubMed

Shpigel, Netanel; Levi, Mikhael D; Sigalov, Sergey; Daikhin, Leonid; Aurbach, Doron

2018-01-16

Quartz crystal microbalance with dissipation monitoring (QCM-D) generates surface-acoustic waves in quartz crystal plates that can effectively probe the structure of films, particulate composite electrodes of complex geometry rigidly attached to quartz crystal surface on one side and contacting a gas or liquid phase on the other side. The output QCM-D characteristics consist of the resonance frequency (MHz frequency range) and resonance bandwidth measured with extra-ordinary precision of a few tenths of Hz. Depending on the electrodes stiffness/softness, QCM-D operates either as a gravimetric or complex mechanical probe of their intrinsic structure. For at least 20 years, QCM-D has been successfully used in biochemical and environmental science and technology for its ability to probe the structure of soft solvated interfaces. Practical battery and supercapacitor electrodes appear frequently as porous solids with their stiffness changing due to interactions with electrolyte solutions or as a result of ion intercalation/adsorption and long-term electrode cycling. Unfortunately, most QCM measurements with electrochemical systems are carried out based on a single (fundamental) frequency and, as such, provided that the resonance bandwidth remains constant, are suitable for only gravimetric sensing. The multiharmonic measurements have been carried out mainly on conducting/redox polymer films rather than on typical composite battery/supercapacitor electrodes. Here, we summarize the most recent publications devoted to the development of electrochemical QCM-D (EQCM-D)-based methodology for systematic characterization of mechanical properties of operating battery/supercapacitor electrodes. By varying the electrodes' composition and structure (thin/thick layers, small/large particles, binders with different mechanical properties, etc.), nature of the electrolyte solutions and charging/cycling conditions, the method is shown to be operated in different application modes. A variety of useful electrode-material properties are assessed noninvasively, in situ, and in real time frames of ion intercalation into the electrodes of interest. A detailed algorithm for the mechanical characterization of battery electrodes kept in the gas phase and immersed into the electrolyte solutions has been developed for fast recognition of stiff and viscoelastic materials in terms of EQCM-D signatures treated by the hydrodynamic and viscoelastic models. Working examples of the use of in situ hydrodynamic spectroscopy to characterize stiff rough/porous solids of complex geometry and viscoelastic characterization of soft electrodes are presented. The most demonstrative example relates to the formation of solid electrolyte interphase on Li 4 Ti 5 O 12 electrodes in the presence of different electrolyte solutions and additives: only a few cycles (an experiment during ∼30 min) were required for screening the electrolyte systems for their ability to form high-quality surface films in experimental EQCM-D cells as compared to 100 cycles (200 h cycling) in conventional coin cells. Thin/small-mass electrodes required for the EQCM-D analysis enable accelerated cycling tests for ultrafast mechanical characterization of these electrodes in different electrolyte solutions. Hence, this methodology can be easily implemented as a highly effective in situ analytical tool in the field of energy storage and conversion.

Continuous process to produce lithium-polymer batteries

DOEpatents

Chern, T.S.H.; Keller, D.G.; MacFadden, K.O.

1998-05-12

Solid polymer electrolytes are extruded with active electrode material in a continuous, one-step process to form composite electrolyte-electrodes ready for assembly into battery cells. The composite electrolyte electrode sheets are extruded onto current collectors to form electrodes. The composite electrodes, as extruded, are electronically and ionically conductive. The composite electrodes can be over coated with a solid polymer electrolyte, which acts as a separator upon battery assembly. The interface between the solid polymer electrolyte composite electrodes and the solid polymer electrolyte separator has low resistance. 1 fig.

Electrode property of single-walled carbon nanotubes in all-solid-state lithium ion battery using polymer electrolyte

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakamoto, Y.; Ishii, Y.; Kawasaki, S., E-mail: kawasaki.shinji@nitech.ac.jp

2016-07-06

Electrode properties of single-walled carbon nanotubes (SWCNTs) in an all-solid-state lithium ion battery were investigated using poly-ethylene oxide (PEO) solid electrolyte. Charge-discharge curves of SWCNTs in the solid electrolyte cell were successfully observed. It was found that PEO electrolyte decomposes on the surface of SWCNTs.

Solid polymer electrolyte composite membrane comprising a porous support and a solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide

DOEpatents

Liu, Han; Mittelsteadt, Cortney K; Norman, Timothy J; Griffith, Arthur E; LaConti, Anthony B

2015-02-24

A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a thin, rigid, dimensionally-stable, non-electrically-conducting support, the support having a plurality of cylindrical, straight-through pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores are unevenly distributed, with some or no pores located along the periphery and more pores located centrally. The pores are completely filled with a solid polymer electrolyte, the solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide. The solid polymer electrolyte may also be deposited over the top and/or bottom surfaces of the support.

MultiLayer solid electrolyte for lithium thin film batteries

DOEpatents

Lee, Se -Hee; Tracy, C. Edwin; Pitts, John Roland; Liu, Ping

2015-07-28

A lithium metal thin-film battery composite structure is provided that includes a combination of a thin, stable, solid electrolyte layer [18] such as Lipon, designed in use to be in contact with a lithium metal anode layer; and a rapid-deposit solid electrolyte layer [16] such as LiAlF.sub.4 in contact with the thin, stable, solid electrolyte layer [18]. Batteries made up of or containing these structures are more efficient to produce than other lithium metal batteries that use only a single solid electrolyte. They are also more resistant to stress and strain than batteries made using layers of only the stable, solid electrolyte materials. Furthermore, lithium anode batteries as disclosed herein are useful as rechargeable batteries.

Protective interlayer for high temperature solid electrolyte electrochemical cells

DOEpatents

Isenberg, Arnold O.; Ruka, Roswell J.

1986-01-01

A high temperature, solid electrolyte electrochemical cell is made, having a first and second electrode with solid electrolyte between them, where the electrolyte is formed by hot chemical vapor deposition, where a solid, interlayer material, which is electrically conductive, oxygen permeable, and protective of electrode material from hot metal halide vapor attack, is placed between the first electrode and the electrolyte, to protect the first electrode from the hot metal halide vapors during vapor deposition.

Protective interlayer for high temperature solid electrolyte electrochemical cells

DOEpatents

Isenberg, Arnold O.; Ruka, Roswell J.; Zymboly, Gregory E.

1985-01-01

A high temperature, solid electrolyte electrochemical cell is made, having a first and second electrode with solid electrolyte between them, where the electrolyte is formed by hot chemical vapor deposition, where a solid, interlayer material, which is electrically conductive, oxygen permeable, and protective of electrode material from hot metal halide vapor attack, is placed between the first electrode and the electrolyte, to protect the first electrode from the hot metal halide vapors during vapor deposition.

Protective interlayer for high temperature solid electrolyte electrochemical cells

DOEpatents

Isenberg, Arnold O.; Ruka, Roswell J.

1987-01-01

A high temperature, solid electrolyte electrochemical cell is made, having a first and second electrode with solid electrolyte between them, where the electrolyte is formed by hot chemical vapor deposition, where a solid, interlayer material, which is electrically conductive, oxygen permeable, and protective of electrode material from hot metal halide vapor attack, is placed between the first electrode and the electrolyte, to protect the first electrode from the hot metal halide vapors during vapor deposition.

Lithium-ion batteries having conformal solid electrolyte layers

DOEpatents

Kim, Gi-Heon; Jung, Yoon Seok

2014-05-27

Hybrid solid-liquid electrolyte lithium-ion battery devices are disclosed. Certain devices comprise anodes and cathodes conformally coated with an electron insulating and lithium ion conductive solid electrolyte layer.

Self-Passivating Lithium/Solid Electrolyte/Iodine Cells

NASA Technical Reports Server (NTRS)

Bugga, Ratnakumar; Whitcare, Jay; Narayanan, Sekharipuram; West, William

2006-01-01

Robust lithium/solid electrolyte/iodine electrochemical cells that offer significant advantages over commercial lithium/ iodine cells have been developed. At room temperature, these cells can be discharged at current densities 10 to 30 times those of commercial lithium/iodine cells. Moreover, from room temperature up to 80 C, the maximum discharge-current densities of these cells exceed those of all other solid-electrolyte-based cells. A cell of this type includes a metallic lithium anode in contact with a commercial flexible solid electrolyte film that, in turn, is in contact with an iodine/ graphite cathode. The solid electrolyte (the chemical composition of which has not been reported) offers the high ionic conductivity needed for high cell performance. However, the solid electrolyte exhibits an undesirable chemical reactivity to lithium that, if not mitigated, would render the solid electrolyte unsuitable for use in a lithium cell. In this cell, such mitigation is affected by the formation of a thin passivating layer of lithium iodide at the anode/electrolyte interface. Test cells of this type were fabricated from iodine/graphite cathode pellets, free-standing solid-electrolyte films, and lithium-foil anodes. The cathode mixtures were made by grinding together blends of nominally 10 weight percent graphite and 90 weight percent iodine. The cathode mixtures were then pressed into pellets at 36 kpsi (248 MPa) and inserted into coin-shaped stainless-steel cell cases that were coated with graphite paste to minimize corrosion. The solid-electrolyte film material was stamped to form circular pieces to fit in the coin cell cases, inserted in the cases, and pressed against the cathode pellets with polyethylene gaskets. Lithium-foil anodes were placed directly onto the electrolyte films. The layers described thus far were pressed and held together by stainless- steel shims, wave springs, and coin cell caps. The assembled cells were then crimped to form hermetic seals. It was found that the solid electrolyte films became discolored within seconds after they were placed in contact with the cathodes - a result of facile diffusion of iodine through the solid electrolyte material (see figure).

Solid electrolyte-electrode system for an electrochemical cell

DOEpatents

Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.

1995-01-01

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided.

Surface and interface engineering of anatase TiO2 anode for sodium-ion batteries through Al2O3 surface modification and wise electrolyte selection

NASA Astrophysics Data System (ADS)

Li, Tao; Gulzar, Umair; Bai, Xue; Monaco, Simone; Longoni, Gianluca; Prato, Mirko; Marras, Sergio; Dang, Zhiya; Capiglia, Claudio; Proietti Zaccaria, Remo

2018-04-01

In the present study, Al2O3 is utilized for the first time as coating agent on nanostructured anatase TiO2 in order to investigate its effect on sodium-ion batteries performance. Our results show that the Al2O3 coating, introduced by a facile two-step approach, provides beneficial effects to the TiO2-based anodes. However, the coated TiO2 still suffers of capacity fading upon cycling when using 1.0 M of NaClO4 in propylene carbonate (PC) as electrolyte. To address this issue, the influence of different electrolytes (NaClO4 salt in various solvents) is further studied. It is found that the modified TiO2 exhibits significant improvements in cycling performance using binary ethylene carbonate (EC) and PC solvent mixture without the need of the commonly used fluoroethylene carbonate (FEC) additive. Under the best configuration, our battery could deliver a high reversible capacity of 188.1 mAh g-1 at 0.1C after 50 cycles, good rate capability up to 5C, and remarkable long-term cycling stability at 1C rate for 650 cycles. This excellent performance can be ascribed to the synergistic effects of surface and interface engineering enabling the formation of a stable and highly ionic conductive interface layer in EC:PC based electrolyte which combines the native SEI film and an 'artificial' SEI layer of irreversibly formed Na-Al-O.

Mechanistic Study of Electrolyte Additives to Stabilize High-Voltage Cathode–Electrolyte Interface in Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Han; Maglia, Filippo; Lamp, Peter

Current developments of electrolyte additives to stabilize electrode-electrolyte interface in Li-ion batteries highly rely on a trial-and-error search, which involves repetitive testing and intensive amount of resources. The lack of understandings on the fundamental protection mechanisms of the additives significantly increases the difficulty for the transformational development of new additives. In this study, we investigated two types of individual protection routes to build a robust cathode-electrolyte interphase at high potentials: (i) a direct reduction in the catalytic decomposition of the electrolyte solvent; and (ii) formation of a “corrosion inhibitor film” that prevents severely attack and passivation from protons that generatedmore » from the solvent oxidation, even the decomposition of solvent cannot not mitigated. Effect of three exemplary electrolyte additives: (i) lithium difluoro(oxalato)borate (LiDFOB); (ii) 3-hexylthiophene (3HT); and (iii) tris(hexafluoro-iso-propyl)phosphate (HFiP), on LiNi0.6Mn0.2Co0.2O2 (NMC 622) cathode were investigated to validate our hypothesis. It is demonstrated that understandings of both electrolyte additives and solvent are essential and careful balance between the cathode protection mechanism of additives and their side effects is critical to obtain optimum results. More importantly, this study opens up new directions of rational design of functional electrolyte additives for the next generation high-energy density lithium-ion chemistries.« less

Ceramic and polymeric solid electrolytes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Fergus, Jeffrey W.

Lithium-ion batteries are important for energy storage in a wide variety of applications including consumer electronics, transportation and large-scale energy production. The performance of lithium-ion batteries depends on the materials used. One critical component is the electrolyte, which is the focus of this paper. In particular, inorganic ceramic and organic polymer solid-electrolyte materials are reviewed. Solid electrolytes provide advantages in terms of simplicity of design and operational safety, but typically have conductivities that are lower than those of organic liquid electrolytes. This paper provides a comparison of the conductivities of solid-electrolyte materials being used or developed for use in lithium-ion batteries.

Method of synthesizing polymers from a solid electrolyte

DOEpatents

Skotheim, Terje A.

1985-01-01

A method of synthesizing electrically conductive polymers from a solvent-free solid polymer electrolyte wherein an assembly of a substrate having an electrode thereon, a thin coating of solid electrolyte including a solution of PEO complexed with an alkali salt, and a thin transparent noble metal electrode are disposed in an evacuated chamber into which a selected monomer vapor is introduced while an electric potential is applied across the solid electrolyte to hold the thin transparent electrode at a positive potential relative to the electrode on the substrate, whereby a highly conductive polymer film is grown on the transparent electrode between it and the solid electrolyte.

Method of synthesizing polymers from a solid electrolyte

DOEpatents

Skotheim, T.A.

1984-10-19

A method of synthesizing electrically conductive polymers from a solvent-free solid polymer electrolyte is disclosed. An assembly of a substrate having an electrode thereon, a thin coating of solid electrolyte including a solution of PEO complexed with an alkali salt, and a thin transparent noble metal electrode are disposed in an evacuated chamber into which a selected monomer vapor is introduced while an electric potential is applied across the solid electrolyte to hold the thin transparent electrode at a positive potential relative to the electrode on the substrate, whereby a highly conductive polymer film is grown on the transparent electrode between it and the solid electrolyte.

A siloxane-incorporated copolymer as an in situ cross-linkable binder for high performance silicon anodes in Li-ion batteries

NASA Astrophysics Data System (ADS)

Jeena, M. T.; Bok, Taesoo; Kim, Si Hoon; Park, Sooham; Kim, Ju-Young; Park, Soojin; Ryu, Ja-Hyoung

2016-04-01

The electrochemical performance of Li-ion batteries (LIBs) can be highly tuned by various factors including the morphology of the anode material, the nature of the electrolyte, the binding material, and the percentage of conducting materials. Binding materials have been of particular interest to researchers over the decades as a means to further improve the cycle durability and columbic efficiency of LIBs. Such approaches include the introduction of different polymeric binders such as poly(acrylic acid) (PAA), carboxymethyl cellulose (CMC), and alginic acid (Alg) into the Si anode of LIBs. To achieve a better efficiency of LIBs, herein, we introduce a novel copolymer, poly(tert-butyl acrylate-co-triethoxyvinylsilane) (TBA-TEVS), as an efficient binder with stable cycle retention and excellent specific capacity. The binder forms a highly interconnected three-dimensional network upon thermal treatment as a result of de-protection of the tert-butyl group and the consequent inter-intra condensation reaction, which minimizes pulverization of the Si nanoparticles. Moreover, the siloxane group is expected to promote the formation of stable solid-electrolyte-interface (SEI) layers. A series of random copolymers were synthesized by varying the molar ratio of tert-butyl acrylate and triethoxyvinylsilane. Twenty-one percent of TEVS in the TBS-TEVS copolymer gave rise to a superior performance as a binder for Si anodes, where the anodes showed a stable specific capacity of 2551 mA h g-1 over hundreds of cycles and an initial columbic efficiency (ICE) of 81.8%.The electrochemical performance of Li-ion batteries (LIBs) can be highly tuned by various factors including the morphology of the anode material, the nature of the electrolyte, the binding material, and the percentage of conducting materials. Binding materials have been of particular interest to researchers over the decades as a means to further improve the cycle durability and columbic efficiency of LIBs. Such approaches include the introduction of different polymeric binders such as poly(acrylic acid) (PAA), carboxymethyl cellulose (CMC), and alginic acid (Alg) into the Si anode of LIBs. To achieve a better efficiency of LIBs, herein, we introduce a novel copolymer, poly(tert-butyl acrylate-co-triethoxyvinylsilane) (TBA-TEVS), as an efficient binder with stable cycle retention and excellent specific capacity. The binder forms a highly interconnected three-dimensional network upon thermal treatment as a result of de-protection of the tert-butyl group and the consequent inter-intra condensation reaction, which minimizes pulverization of the Si nanoparticles. Moreover, the siloxane group is expected to promote the formation of stable solid-electrolyte-interface (SEI) layers. A series of random copolymers were synthesized by varying the molar ratio of tert-butyl acrylate and triethoxyvinylsilane. Twenty-one percent of TEVS in the TBS-TEVS copolymer gave rise to a superior performance as a binder for Si anodes, where the anodes showed a stable specific capacity of 2551 mA h g-1 over hundreds of cycles and an initial columbic efficiency (ICE) of 81.8%. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01559j

Performance comparison: Aluminum electrolytic and solid tantalum capacitor

NASA Technical Reports Server (NTRS)

Hawthornthwaite, B. G.; Piper, J.; Holland, H. W.

1981-01-01

Several key electrical and environmental parameters of latest technology aluminum electrolytic and solid tantalum capacitors were evaluated in terms of price fluctuations of tantalum metal. Performance differences between solid tantalums and aluminum electrolytics are examined.

A zwitterionic gel electrolyte for efficient solid-state supercapacitors

PubMed Central

Peng, Xu; Liu, Huili; Yin, Qin; Wu, Junchi; Chen, Pengzuo; Zhang, Guangzhao; Liu, Guangming; Wu, Changzheng; Xie, Yi

2016-01-01

Gel electrolytes have attracted increasing attention for solid-state supercapacitors. An ideal gel electrolyte usually requires a combination of advantages of high ion migration rate, reasonable mechanical strength and robust water retention ability at the solid state for ensuring excellent work durability. Here we report a zwitterionic gel electrolyte that successfully brings the synergic advantages of robust water retention ability and ion migration channels, manifesting in superior electrochemical performance. When applying the zwitterionic gel electrolyte, our graphene-based solid-state supercapacitor reaches a volume capacitance of 300.8 F cm−3 at 0.8 A cm−3 with a rate capacity of only 14.9% capacitance loss as the current density increases from 0.8 to 20 A cm−3, representing the best value among the previously reported graphene-based solid-state supercapacitors, to the best of our knowledge. We anticipate that zwitterionic gel electrolyte may be developed as a gel electrolyte in solid-state supercapacitors. PMID:27225484

Oxygen partial pressure sensor

DOEpatents

Dees, D.W.

1994-09-06

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

Oxygen partial pressure sensor

DOEpatents

Dees, Dennis W.

1994-01-01

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

Solid electrolyte-electrode system for an electrochemical cell

DOEpatents

Tuller, H.L.; Kramer, S.A.; Spears, M.A.

1995-04-04

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided. 17 figures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galvez-Aranda, Diego E.; Ponce, Victor; Seminario, Jorge M.

Rechargeable lithium-ion batteries are the most popular devices for energy storage but still a lot of research needs to be done to improve their cycling and storage capacity. Silicon has been proposed as an anode material because of its large theoretical capacity of ~3600 mAh/g. Therefore, focus is needed on the lithiation process of silicon anodes where it is known that the anode increases its volume more than 300%, producing cracking and other damages. In this study, we performed molecular dynamics atomistic simulations to study the swelling, alloying, and amorphization of a silicon nanocrystal anode in a full nanobattery modelmore » during the first charging cycle. A dissolved salt of lithium hexafluorophosphate in ethylene carbonate was chosen as the electrolyte solution and lithium cobalt oxide as cathode. External electric fields are applied to emulate the charging, causing the migration of the Li-ions from the cathode to the anode, by drifting through the electrolyte solution, thus converting pristine Si gradually into Li 14Si 5 when fully lithiated. When the electric field is applied to the nanobattery, the temperature never exceeds 360 K due to a temperature control imposed resembling a cooling mechanism. The volume of the anode increases with the amorphization of the silicon as the external field is applied by creating a layer of LiSi alloy between the electrolyte and the silicon nanocrystal and then, at the arrival of more Li-ions changing to an alloy, where the drift velocity of Li-ions is greater than the velocity in the initial nanocrystal structure. Charge neutrality is maintained by concerted complementary reduction-oxidation reactions at the anode and cathode, respectively. Also, the nanobattery model developed here can be used to study charge mobility, current density, conductance and resistivity, among several other properties of several candidate materials for rechargeable batteries and constitutes the initial point for further studies on the formation of the solid electrolyte interphase in the anode.« less

Poly(ethylene oxide)-co-poly(propylene oxide)-based gel electrolyte with high ionic conductivity and mechanical integrity for lithium-ion batteries.

PubMed

Wang, Shih-Hong; Hou, Sheng-Shu; Kuo, Ping-Lin; Teng, Hsisheng

2013-09-11

Using gel polymer electrolytes (GPEs) for lithium-ion batteries usually encounters the drawback of poor mechanical integrity of the GPEs. This study demonstrates the outstanding performance of a GPE consisting of a commercial membrane (Celgard) incorporated with a poly(ethylene oxide)-co-poly(propylene oxide) copolymer (P(EO-co-PO)) swelled by a liquid electrolyte (LE) of 1 M LiPF6 in carbonate solvents. The proposed GPE stably holds LE with an amount that is three times that of the Celgard-P(EO-co-PO) composite. This GPE has a higher ionic conductivity (2.8×10(-3) and 5.1×10(-4) S cm(-1) at 30 and -20 °C, respectively) and a wider electrochemical voltage range (5.1 V) than the LE-swelled Celgard because of the strong ion-solvation power of P(EO-co-PO). The active ion-solvation role of P(EO-co-PO) also suppresses the formation of the solid-electrolyte interphase layer. When assembling the GPE in a Li/LiFePO4 battery, the P(EO-co-PO) network hinders anionic transport, producing a high Li+ transference number of 0.5 and decreased the polarization overpotential. The Li/GPE/LiFePO4 battery delivers a discharge capacity of 156-135 mAh g(-1) between 0.1 and 1 C-rates, which is approximately 5% higher than that of the Li/LE/LiFePO4 battery. The IR drop of the Li/GPE/LiFePO4 battery was 44% smaller than that of the Li/LE/LiFePO4. The Li/GPE/LiFePO4 battery is more stable, with only a 1.2% capacity decay for 150 galvanostatic charge-discharge cycles. The advantages of the proposed GPE are its high stability, conductivity, Li+ transference number, and mechanical integrity, which allow for the assembly of GPE-based batteries readily scalable to industrial levels.

Molecular dynamics simulations of the first charge of a Li-ion—Si-anode nanobattery

DOE PAGES

Galvez-Aranda, Diego E.; Ponce, Victor; Seminario, Jorge M.

2017-03-16

Rechargeable lithium-ion batteries are the most popular devices for energy storage but still a lot of research needs to be done to improve their cycling and storage capacity. Silicon has been proposed as an anode material because of its large theoretical capacity of ~3600 mAh/g. Therefore, focus is needed on the lithiation process of silicon anodes where it is known that the anode increases its volume more than 300%, producing cracking and other damages. In this study, we performed molecular dynamics atomistic simulations to study the swelling, alloying, and amorphization of a silicon nanocrystal anode in a full nanobattery modelmore » during the first charging cycle. A dissolved salt of lithium hexafluorophosphate in ethylene carbonate was chosen as the electrolyte solution and lithium cobalt oxide as cathode. External electric fields are applied to emulate the charging, causing the migration of the Li-ions from the cathode to the anode, by drifting through the electrolyte solution, thus converting pristine Si gradually into Li 14Si 5 when fully lithiated. When the electric field is applied to the nanobattery, the temperature never exceeds 360 K due to a temperature control imposed resembling a cooling mechanism. The volume of the anode increases with the amorphization of the silicon as the external field is applied by creating a layer of LiSi alloy between the electrolyte and the silicon nanocrystal and then, at the arrival of more Li-ions changing to an alloy, where the drift velocity of Li-ions is greater than the velocity in the initial nanocrystal structure. Charge neutrality is maintained by concerted complementary reduction-oxidation reactions at the anode and cathode, respectively. Also, the nanobattery model developed here can be used to study charge mobility, current density, conductance and resistivity, among several other properties of several candidate materials for rechargeable batteries and constitutes the initial point for further studies on the formation of the solid electrolyte interphase in the anode.« less

3D Fiber-Network-Reinforced Bicontinuous Composite Solid Electrolyte for Dendrite-free Lithium Metal Batteries.

PubMed

Li, Dan; Chen, Long; Wang, Tianshi; Fan, Li-Zhen

2018-02-28

Replacement of flammable organic liquid electrolytes with solid Li + conductors is a promising approach to realize excellent performance of Li metal batteries. However, ceramic electrolytes are either easily reduced by Li metal or penetrated by Li dendrites through their grain boundaries, and polymer electrolytes are also faced with instability on the electrode/electrolyte interface and weak mechanical property. Here, we report a three-dimensional fiber-network-reinforced bicontinuous solid composite electrolyte with flexible Li + -conductive network (lithium aluminum titanium phosphate (LATP)/polyacrylonitrile), which helps to enhance electrochemical stability on the electrode/electrolyte interface by isolating Li and LATP and suppress Li dendrites growth by mechanical reinforcement of fiber network for the composite solid electrolyte. The composite electrolyte shows an excellent electrochemical stability after 15 days of contact with Li metal and has an enlarged tensile strength (10.72 MPa) compared to the pure poly(ethylene oxide)-bistrifluoromethanesulfonimide lithium salt electrolyte, leading to a long-term stability and safety of the Li symmetric battery with a current density of 0.3 mA cm -2 for 400 h. In addition, the composite electrolyte also shows good electrochemical and thermal stability. These results provide such fiber-reinforced membranes that present stable electrode/electrolyte interface and suppress lithium dendrite growth for high-safety all-solid-state Li metal batteries.

A new anion receptor for improving the interface between lithium- and manganese-rich layered oxide cathode and the electrolyte

DOE PAGES

Ma, Yulin; Zhou, Yan; Du, Chunyu; ...

2017-02-15

Surface degradation on cycled lithium-ion battery cathode particles is governed not only by intrinsic thermodynamic properties of the material but also, oftentimes more predominantly, by the side reactions with the electrolytic solution. A superior electrolyte inhibits these undesired side reactions on the cathode and at the electrolyte interface, which consequently minimizes the deterioration of the cathode surface. The present study investigates a new boron-based anion receptor, tris(2,2,2-trifluoroethyl)borate (TTFEB), as an electrolyte additive in cells containing a lithium- and manganese-rich layered oxide cathode, Li 1.16Ni 0.2Co 0.1Mn 0.54O 2. Our electrochemical studies demonstrate that the cycling performance and Coulombic efficiency aremore » significantly improved because of the additive, in particular, under elevated temperature conditions. Spectroscopic analyses revealed that the addition of 0.5 wt % TTFEB is capable of reducing the content of lithium-containing inorganic species within the cathode-electrolyte interphase layer and minimizing the reduction of tetravalent Mn4+ at the cathode surface. Furthermore, our work introduces a novel additive highly effective in improving lithium-ion battery performance, highlights the importance in preserving the surface properties of cathode materials, and provides new insights on the working mechanism of electrolyte additives.« less

Numerical investigation of influence on heat transfer characteristics to pneumatically conveyed dense phase flow by selecting models and boundary conditions

NASA Astrophysics Data System (ADS)

Zheng, Y.; Liu, Q.; Li, Y.

2012-03-01

Solids moving with a gas stream in a pipeline can be found in many industrial processes, such as power generation, chemical, pharmaceutical, food and commodity transfer processes. A mass flow rate of the solids is important characteristic that is often required to be measured (and controlled) to achieve efficient utilization of energy and raw materials in pneumatic conveying systems. The methods of measuring the mass flow rate of solids in a pneumatic pipeline can be divided into direct and indirect (inferential) measurements. A thermal solids' mass flow-meter, in principle, should ideally provide a direct measurement of solids flow rate, regardless of inhomogeneities in solids' distribution and environmental impacts. One key issue in developing a thermal solids' mass flow-meter is to characterize the heat transfer between the hot pipe wall and the gas-solids dense phase flow. The Eulerian continuum modeling with gas-solid two phases is the most common method for pneumatic transport. To model a gas-solid dense phase flow passing through a heated region, the gas phase is described as a continuous phase and the particles as the second phase. This study aims to describe the heat transfer characteristics between the hot wall and the gas-solids dense phase flow in pneumatic pipelines by modeling a turbulence gas-solid plug passing through the heated region which involves several actual and crucial issues: selections of interphase exchange coefficient, near-wall region functions and different wall surface temperatures. A sensitivity analysis was discussed to identify the influence on the heat transfer characteristics by selecting different interphase exchange coefficient models and different boundary conditions. Simulation results suggest that sensitivity analysis in the choice of models is very significant. The simulation results appear to show that a combination of choosing the Syamlal-O'Brien interphase exchange coefficient model and the standard k-ɛ model along with the standard wall function model might be the best approach, by which, the simulation data seems to be closest to the experimental results.

Solid-State Electrolyte Anchored with a Carboxylated Azo Compound for All-Solid-State Lithium Batteries.

PubMed

Luo, Chao; Ji, Xiao; Chen, Ji; Gaskell, Karen J; He, Xinzi; Liang, Yujia; Jiang, Jianjun; Wang, Chunsheng

2018-05-23

Organic electrode materials are promising for green and sustainable lithium-ion batteries. However, the high solubility of organic materials in the liquid electrolyte results in the shuttle reaction and fast capacity decay. Herein, azo compounds are firstly applied in all-solid-state lithium batteries (ASSLB) to suppress the dissolution challenge. Due to the high compatibility of azobenzene (AB) based compounds to Li 3 PS 4 (LPS) solid electrolyte, the LPS solid electrolyte is used to prevent the dissolution and shuttle reaction of AB. To maintain the low interface resistance during the large volume change upon cycling, a carboxylate group is added into AB to provide 4-(phenylazo) benzoic acid lithium salt (PBALS), which could bond with LPS solid electrolyte via the ionic bonding between oxygen in PBALS and lithium ion in LPS. The ionic bonding between the active material and solid electrolyte stabilizes the contact interface and enables the stable cycle life of PBALS in ASSLB. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interphase Evolution of a Lithium-Ion/Oxygen Battery.

PubMed

Elia, Giuseppe Antonio; Bresser, Dominic; Reiter, Jakub; Oberhumer, Philipp; Sun, Yang-Kook; Scrosati, Bruno; Passerini, Stefano; Hassoun, Jusef

2015-10-14

A novel lithium-ion/oxygen battery employing Pyr14TFSI-LiTFSI as the electrolyte and nanostructured LixSn-C as the anode is reported. The remarkable energy content of the oxygen cathode, the replacement of the lithium metal anode by a nanostructured stable lithium-alloying composite, and the concomitant use of nonflammable ionic liquid-based electrolyte result in a new and intrinsically safer energy storage system. The lithium-ion/oxygen battery delivers a stable capacity of 500 mAh g(-1) at a working voltage of 2.4 V with a low charge-discharge polarization. However, further characterization of this new system by electrochemical impedance spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy reveals the progressive decrease of the battery working voltage, because of the crossover of oxygen through the electrolyte and its direct reaction with the LixSn-C anode.

The Role of Electrolyte Upon the SEI Formation Characteristics and Low Temperature Performance of Lithium-Ion Cells With Graphite Anodes

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Greenbaum, S.; Surampudi, S.

2000-01-01

Quarternary lithium-ion battery electrolyte solutions containing ester co-solvents in mixtures of carbonates have been demonstrated to have high conductivity at low temperatures (< -20C). However, in some cases the presence of such co-solvents does not directly translate into improved low temperature cell performance, presumably due to the formation of ionically resistive surface films on carbonaceous anodes. In order to understand this behavior, a number of lithium-graphite cells have been studied containing electrolytes with various ester co-solvents, including methyl acetate (MA), ethyl acetate (EA), ethyl propionate (EP), and ethyl butyrate (EB). The charge/discharge characterization of these cells indicates that the higher molecular weight esters result in electrolytes which possess superior low temperature performance in contrast to the lower molecular weight ester-containing solutions, even though these solutions display lower conductivity values.

Autogenous electrolyte, non-pyrolytically produced solid capacitor structure

DOEpatents

Sharp, Donald J.; Armstrong, Pamela S.; Panitz, Janda Kirk G.

1998-01-01

A solid electrolytic capacitor having a solid electrolyte comprising manganese dioxide dispersed in an aromatic polyamide capable of further cure to form polyimide linkages, the solid electrolyte being disposed between a first electrode made of valve metal covered by an anodic oxide film and a second electrode opposite the first electrode. The electrolyte autogenously produces water, oxygen, and hydroxyl groups which act as healing substances and is not itself produced pyrolytically. Reduction of the manganese dioxide and the water molecules released by formation of imide linkages result in substantially improved self-healing of anodic dielectric layer defects.

Autogenous electrolyte, non-pyrolytically produced solid capacitor structure

DOEpatents

Sharp, D.J.; Armstrong, P.S.; Panitz, J.K.G.

1998-03-17

A solid electrolytic capacitor is described having a solid electrolyte comprising manganese dioxide dispersed in an aromatic polyamide capable of further cure to form polyimide linkages, the solid electrolyte being disposed between a first electrode made of valve metal covered by an anodic oxide film and a second electrode opposite the first electrode. The electrolyte autogenously produces water, oxygen, and hydroxyl groups which act as healing substances and is not itself produced pyrolytically. Reduction of the manganese dioxide and the water molecules released by formation of imide linkages result in substantially improved self-healing of anodic dielectric layer defects. 2 figs.

Molecular dynamics simulations of the first charge of a Li-ion-Si-anode nanobattery.

PubMed

Galvez-Aranda, Diego E; Ponce, Victor; Seminario, Jorge M

2017-04-01

Rechargeable lithium-ion batteries are the most popular devices for energy storage but still a lot of research needs to be done to improve their cycling and storage capacity. Silicon has been proposed as an anode material because of its large theoretical capacity of ∼3600 mAh/g. Therefore, focus is needed on the lithiation process of silicon anodes where it is known that the anode increases its volume more than 300%, producing cracking and other damages. We performed molecular dynamics atomistic simulations to study the swelling, alloying, and amorphization of a silicon nanocrystal anode in a full nanobattery model during the first charging cycle. A dissolved salt of lithium hexafluorophosphate in ethylene carbonate was chosen as the electrolyte solution and lithium cobalt oxide as cathode. External electric fields are applied to emulate the charging, causing the migration of the Li-ions from the cathode to the anode, by drifting through the electrolyte solution, thus converting pristine Si gradually into Li 14 Si 5 when fully lithiated. When the electric field is applied to the nanobattery, the temperature never exceeds 360 K due to a temperature control imposed resembling a cooling mechanism. The volume of the anode increases with the amorphization of the silicon as the external field is applied by creating a layer of LiSi alloy between the electrolyte and the silicon nanocrystal and then, at the arrival of more Li-ions changing to an alloy, where the drift velocity of Li-ions is greater than the velocity in the initial nanocrystal structure. Charge neutrality is maintained by concerted complementary reduction-oxidation reactions at the anode and cathode, respectively. In addition, the nanobattery model developed here can be used to study charge mobility, current density, conductance and resistivity, among several other properties of several candidate materials for rechargeable batteries and constitutes the initial point for further studies on the formation of the solid electrolyte interphase in the anode. Graphical Abstract Nanobattery: LiCoO 2 cathode, electrolyte solution of 1M Li + PF 6 - in ethylene carbonate, and Si crystal anode, which changes its volume due to lithiation during the first charge.

Fuel cells with solid polymer electrolyte and their application on vehicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fateev, V.

1996-04-01

In Russia, solid polymer electrolyte MF-4-SK has been developed for fuel cells. This electrolyte is based on perfluorinated polymer with functional sulfogroups. Investigations on electrolyte properties and electrocatalysts have been carried out.

Solid oxide fuel cell operable over wide temperature range

DOEpatents

Baozhen, Li; Ruka, Roswell J.; Singhal, Subhash C.

2001-01-01

Solid oxide fuel cells having improved low-temperature operation are disclosed. In one embodiment, an interfacial layer of terbia-stabilized zirconia is located between the air electrode and electrolyte of the solid oxide fuel cell. The interfacial layer provides a barrier which controls interaction between the air electrode and electrolyte. The interfacial layer also reduces polarization loss through the reduction of the air electrode/electrolyte interfacial electrical resistance. In another embodiment, the solid oxide fuel cell comprises a scandia-stabilized zirconia electrolyte having high electrical conductivity. The scandia-stabilized zirconia electrolyte may be provided as a very thin layer in order to reduce resistance. The scandia-stabilized electrolyte is preferably used in combination with the terbia-stabilized interfacial layer. The solid oxide fuel cells are operable over wider temperature ranges and wider temperature gradients in comparison with conventional fuel cells.

Interfacial material for solid oxide fuel cell

DOEpatents

Baozhen, Li; Ruka, Roswell J.; Singhal, Subhash C.

1999-01-01

Solid oxide fuel cells having improved low-temperature operation are disclosed. In one embodiment, an interfacial layer of terbia-stabilized zirconia is located between the air electrode and electrolyte of the solid oxide fuel cell. The interfacial layer provides a barrier which controls interaction between the air electrode and electrolyte. The interfacial layer also reduces polarization loss through the reduction of the air electrode/electrolyte interfacial electrical resistance. In another embodiment, the solid oxide fuel cell comprises a scandia-stabilized zirconia electrolyte having high electrical conductivity. The scandia-stabilized zirconia electrolyte may be provided as a very thin layer in order to reduce resistance. The scandia-stabilized electrolyte is preferably used in combination with the terbia-stabilized interfacial layer. The solid oxide fuel cells are operable over wider temperature ranges and wider temperature gradients in comparison with conventional fuel cells.

Review on solid electrolytes for all-solid-state lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zheng, Feng; Kotobuki, Masashi; Song, Shufeng; Lai, Man On; Lu, Li

2018-06-01

All-solid-state (ASS) lithium-ion battery has attracted great attention due to its high safety and increased energy density. One of key components in the ASS battery (ASSB) is solid electrolyte that determines performance of the ASSB. Many types of solid electrolytes have been investigated in great detail in the past years, including NASICON-type, garnet-type, perovskite-type, LISICON-type, LiPON-type, Li3N-type, sulfide-type, argyrodite-type, anti-perovskite-type and many more. This paper aims to provide comprehensive reviews on some typical types of key solid electrolytes and some ASSBs, and on gaps that should be resolved.

Room-Temperature Performance of Poly(Ethylene Ether Carbonate)-Based Solid Polymer Electrolytes for All-Solid-State Lithium Batteries.

PubMed

Jung, Yun-Chae; Park, Myung-Soo; Kim, Duck-Hyun; Ue, Makoto; Eftekhari, Ali; Kim, Dong-Won

2017-12-13

Amorphous poly(ethylene ether carbonate) (PEEC), which is a copolymer of ethylene oxide and ethylene carbonate, was synthesized by ring-opening polymerization of ethylene carbonate. This route overcame the common issue of low conductivity of poly(ethylene oxide)(PEO)-based solid polymer electrolytes at low temperatures, and thus the solid polymer electrolyte could be successfully employed at the room temperature. Introducing the ethylene carbonate units into PEEC improved the ionic conductivity, electrochemical stability and lithium transference number compared with PEO. A cross-linked solid polymer electrolyte was synthesized by photo cross-linking reaction using PEEC and tetraethyleneglycol diacrylate as a cross-linking agent, in the form of a flexible thin film. The solid-state Li/LiNi 0.6 Co 0.2 Mn 0.2 O 2 cell assembled with solid polymer electrolyte based on cross-linked PEEC delivered a high initial discharge capacity of 141.4 mAh g -1 and exhibited good capacity retention at room temperature. These results demonstrate the feasibility of using this solid polymer electrolyte in all-solid-state lithium batteries that can operate at ambient temperatures.

High temperature solid state storage cell

DOEpatents

Rea, Jesse R.; Kallianidis, Milton; Kelsey, G. Stephen

1983-01-01

A completely solid state high temperature storage cell comprised of a solid rechargeable cathode such as TiS.sub.2, a solid electrolyte which remains solid at the high temperature operating conditions of the cell and which exhibits high ionic conductivity at such elevated temperatures such as an electrolyte comprised of lithium iodide, and a solid lithium or other alkali metal alloy anode (such as a lithium-silicon alloy) with 5-50% by weight of said anode being comprised of said solid electrolyte.

Optimized performance of quasi-solid-state DSSC with PEO-bismaleimide polymer blend electrolytes filled with a novel procedure.

PubMed

Lee, Dong Ha; Sun, Kyung Chul; Qadir, Muhammad Bilal; Jeong, Sung Hoon

2014-12-01

Dye-sensitized solar cell (DSSC) is an attractive renewable energy technology currently under intense investigation. Electrolyte plays an important role in the photovoltaic performance of the DSSCs and many efforts have been contributed to study different kinds of electrolytes with various characteristics such as liquid electrolytes, polymer electrolytes and so on. In this study, DSSC is developed by using quasi-solid electrolyte and a novel procedure is adopted for filling this electrolyte. The quasi-solid-state electrolyte was prepared by mixing Poly ethylene oxide (PEO) and bismaleimide together and constitution was taken as PEO (15 wt%) at various bismaleimide concentrations (1, 3, 5 wt%). The novel procedure of filling electrolyte consists of three major steps (first step: filling liquid electrolyte, second step: vaporization of liquid electrolyte, third step: refilling quasi-solid-state electrolyte). The electrochemical and photovoltaic performances of DSSCs with these electrolytes were also investigated. The electrochemical impedance spectroscopy (EIS) indicated that TiO2/Dye/electrolyte impedance is reduced and electron lifetime is increased, and consequently efficiency of cell has been improved after using this novel procedure. The photovoltaic power conversion efficiency of 6.39% has been achieved under AM 1.5 simulated sunlight (100 W/cm2) through this novel procedure and by using specified blend of polymers.

Electrolyte for batteries with regenerative solid electrolyte interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Jie; Lu, Dongping; Shao, Yuyan

2017-08-01

An energy storage device comprising: an anode; and a solute-containing electrolyte composition wherein the solute concentration in the electrolyte composition is sufficiently high to form a regenerative solid electrolyte interface layer on a surface of the anode only during charging of the energy storage device, wherein the regenerative layer comprises at least one solute or solvated solute from the electrolyte composition.

Soft X-ray emission spectroscopy of liquids and lithium batterymaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Augustsson, Andreas

2004-01-01

Lithium ion insertion into electrode materials is commonly used in rechargeable battery technology. The insertion implies changes in both the crystal structure and the electronic structure of the electrode material. Side-reactions may occur on the surface of the electrode which is exposed to the electrolyte and form a solid electrolyte interface (SEI). The understanding of these processes is of great importance for improving battery performance. The chemical and physical properties of water and alcohols are complicated by the presence of strong hydrogen bonding. Various experimental techniques have been used to study geometrical structures and different models have been proposed tomore » view the details of how these liquids are geometrically organized by hydrogen bonding. However, very little is known about the electronic structure of these liquids, mainly due to the lack of suitable experimental tools. In this thesis examples of studies of lithium battery electrodes and liquid systems using soft x-ray emission spectroscopy will be presented. Monochromatized synchrotron radiation has been used to accomplish selective excitation, in terms of energy and polarization. The electronic structure of graphite electrodes has been studied, before and after lithium intercalation. Changes in the electronic structure upon lithiation due to transfer of electrons into the graphite π-bands have been observed. Transfer of electrons in to the 3d states of transition metal oxides upon lithiation have been studied, through low energy excitations as dd- and charge transfer-excitations. A SEI was detected on cycled graphite electrodes. By the use of selective excitation different carbon sites were probed in the SEI. The local electronic structure of water, methanol and mixtures of the two have been examined using a special liquid cell, to separate the liquid from the vacuum in the experimental chamber. Results from the study of liquid water showed a strong influence on the 3a1 molecular orbital and orbital mixing between water molecules upon hydrogen bonding. Apart from the four-hydrogen-bonding structure in water, a structure where one hydrogen bond is broken could be separated and identified. The soft x-ray emission study of methanol showed the existence of ring and chain formations in the liquid phase and the dominating structures are formed of 6 and 8 molecules. Upon mixing of the two liquids, a segregation at the molecular level was found and the formation of new structures, which could explain the unexpected low increase of the entropy.« less

New Solid Polymer Electrolytes for Improved Lithium Batteries

NASA Technical Reports Server (NTRS)

Hehemann, David G.

2002-01-01

The objective of this work was to identify, synthesize and incorporate into a working prototype, next-generation solid polymer electrolytes, that allow our pre-existing solid-state lithium battery to function better under extreme conditions. We have synthesized polymer electrolytes in which emphasis was placed on the temperature-dependent performance of these candidate electrolytes. This project was designed to produce and integrate novel polymer electrolytes into a lightweight thin-film battery that could easily be scaled up for mass production and adapted to different applications.

Vertically Aligned and Continuous Nanoscale Ceramic-Polymer Interfaces in Composite Solid Polymer Electrolytes for Enhanced Ionic Conductivity.

PubMed

Zhang, Xiaokun; Xie, Jin; Shi, Feifei; Lin, Dingchang; Liu, Yayuan; Liu, Wei; Pei, Allen; Gong, Yongji; Wang, Hongxia; Liu, Kai; Xiang, Yong; Cui, Yi

2018-06-13

Among all solid electrolytes, composite solid polymer electrolytes, comprised of polymer matrix and ceramic fillers, garner great interest due to the enhancement of ionic conductivity and mechanical properties derived from ceramic-polymer interactions. Here, we report a composite electrolyte with densely packed, vertically aligned, and continuous nanoscale ceramic-polymer interfaces, using surface-modified anodized aluminum oxide as the ceramic scaffold and poly(ethylene oxide) as the polymer matrix. The fast Li + transport along the ceramic-polymer interfaces was proven experimentally for the first time, and an interfacial ionic conductivity higher than 10 -3 S/cm at 0 °C was predicted. The presented composite solid electrolyte achieved an ionic conductivity as high as 5.82 × 10 -4 S/cm at the electrode level. The vertically aligned interfacial structure in the composite electrolytes enables the viable application of the composite solid electrolyte with superior ionic conductivity and high hardness, allowing Li-Li cells to be cycled at a small polarization without Li dendrite penetration.

Utilization of the Recycle Reactor in Determining Kinetics of Gas-Solid Catalytic Reactions.

ERIC Educational Resources Information Center

Paspek, Stephen C.; And Others

1980-01-01

Describes a laboratory scale reactor that determines the kinetics of a gas-solid catalytic reaction. The external recycle reactor construction is detailed with accompanying diagrams. Experimental details, application of the reactor to CO oxidation kinetics, interphase gradients, and intraphase gradients are discussed. (CS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allcorn, Eric

Lithium-ion battery safety is a critical issue in the adoption of the chemistry to larger scale applications such as transportation and stationary storage. One of the critical components impacting the safety of lithium-ion batteries is their use of highly flammable organic electrolytes. In this work, brominated flame retardants (BFR’s) – an existing class of flame retardant materials – are incorporated as additives to lithium-ion battery electrolytes with the intention to reduce the electrolyte flammability and thereby improve safety. There are a few critical needs for a successful electrolyte additive: solubility in the electrolyte, electrochemical stability over the range of batterymore » operation, and minimal detrimental effects on battery performance. Those detrimental effects can take the form of electrolyte specific impacts, such as a reduction in conductivity, or electrode impacts, such as SEI-layer modification or chemical instability to the active material. In addition to these needs, the electrolyte additive also needs to achieve its intended purpose, which in this case is to reduce the flammability of the electrolyte. For the work conducted as part of this SPP agreement three separate BFR materials were provided by Albemarle to be tested by Sandia as additives in a traditional lithium-ion battery electrolyte. The provided BFR materials were tribromo-neopentyl alcohol, tetrabromo bisphenol A, and tribromoethylene. These materials were incorporated as separate 4 wt.% additives into a traditional lithium-ion battery electrolyte and compared to said traditional electrolyte, designated Gen2.« less

Stability of the Solid Electrolyte Interface on the Li Electrode in Li–S Batteries

DOE PAGES

Zheng, Dong; Yang, Xiao-Qing; Qu, Deyang

2016-04-05

In this study, by means of high performance liquid chromatography–mass spectroscopy, the concentration of sulfur and polysulfides was determined in nonaqueous electrolytes. The stability of sulfur and Li in eight electrolytes was studied quantitatively. It was found that sulfur reacted with Li in most of the commonly used electrolytes for lithium–sulfur batteries. The reaction products between sulfur and Li were qualitatively identified. In some cases, the solid electrolyte interface on the Li can successfully prevent the interaction between S and Li; however, it was found that the solid electrolyte interface was damaged by polysulfide ions.

Solid polymer electrolyte composite membrane comprising laser micromachined porous support

DOEpatents

Liu, Han [Waltham, MA; LaConti, Anthony B [Lynnfield, MA; Mittelsteadt, Cortney K [Natick, MA; McCallum, Thomas J [Ashland, MA

2011-01-11

A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 5 microns, are made by laser micromachining and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

Solid polymer electrolyte composite membrane comprising plasma etched porous support

DOEpatents

Liu, Han; LaConti, Anthony B.

2010-10-05

A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 0.1 to 5 microns, are made by plasma etching and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

An advanced model framework for solid electrolyte intercalation batteries.

PubMed

Landstorfer, Manuel; Funken, Stefan; Jacob, Timo

2011-07-28

Recent developments of solid electrolytes, especially lithium ion conductors, led to all solid state batteries for various applications. In addition, mathematical models sprout for different electrode materials and battery types, but are missing for solid electrolyte cells. We present a mathematical model for ion flux in solid electrolytes, based on non-equilibrium thermodynamics and functional derivatives. Intercalated ion diffusion within the electrodes is further considered, allowing the computation of the ion concentration at the electrode/electrolyte interface. A generalized Frumkin-Butler-Volmer equation describes the kinetics of (de-)intercalation reactions and is here extended to non-blocking electrodes. Using this approach, numerical simulations were carried out to investigate the space charge region at the interface. Finally, discharge simulations were performed to study different limitations of an all solid state battery cell. This journal is © the Owner Societies 2011

Fabrication of ultrathin solid electrolyte membranes of β-Li 3PS 4 nanoflakes by evaporation-induced self-assembly for all-solid-state batteries

DOE PAGES

Wang, Hui; Hood, Zachary D.; Xia, Younan; ...

2016-04-25

All-solid-state lithium batteries are attractive candidates for next-generation energy storage devices because of their anticipated high energy density and intrinsic safety. Owing to their excellent ionic conductivity and stability with metallic lithium anodes, nanostructured lithium thiophosphate solid electrolytes such as β-Li 3PS 4 have found use in the fabrication of all-solid lithium batteries for large-scale energy storage systems. However, current methods for preparing air-sensitive solid electrolyte membranes of lithium thiophosphates can only generate thick membranes that compromise the battery's gravimetric/volumetric energy density and thus its rate performance. To overcome this limitation, the solid electrolyte's thickness needs to be effectively decreasedmore » to achieve ideal energy density and enhanced rate performance. In this paper, we show that the evaporation-induced self-assembly (EISA) technique produces ultrathin membranes of a lithium thiophosphate solid electrolyte with controllable thicknesses between 8 and 50 μm while maintaining the high ionic conductivity of β-Li 3PS 4 and stability with metallic lithium anodes up to 5 V. Finally, it is clearly demonstrated that this facile EISA approach allows for the preparation of ultrathin lithium thiophosphate solid electrolyte membranes for all-solid-state batteries.« less

Integrated Interface Strategy toward Room Temperature Solid-State Lithium Batteries.

PubMed

Ju, Jiangwei; Wang, Yantao; Chen, Bingbing; Ma, Jun; Dong, Shanmu; Chai, Jingchao; Qu, Hongtao; Cui, Longfei; Wu, Xiuxiu; Cui, Guanglei

2018-04-25

Solid-state lithium batteries have drawn wide attention to address the safety issues of power batteries. However, the development of solid-state lithium batteries is substantially limited by the poor electrochemical performances originating from the rigid interface between solid electrodes and solid-state electrolytes. In this work, a composite of poly(vinyl carbonate) and Li 10 SnP 2 S 12 solid-state electrolyte is fabricated successfully via in situ polymerization to improve the rigid interface issues. The composite electrolyte presents a considerable room temperature conductivity of 0.2 mS cm -1 , an electrochemical window exceeding 4.5 V, and a Li + transport number of 0.6. It is demonstrated that solid-state lithium metal battery of LiFe 0.2 Mn 0.8 PO 4 (LFMP)/composite electrolyte/Li can deliver a high capacity of 130 mA h g -1 with considerable capacity retention of 88% and Coulombic efficiency of exceeding 99% after 140 cycles at the rate of 0.5 C at room temperature. The superior electrochemical performance can be ascribed to the good compatibility of the composite electrolyte with Li metal and the integrated compatible interface between solid electrodes and the composite electrolyte engineered by in situ polymerization, which leads to a significant interfacial impedance decrease from 1292 to 213 Ω cm 2 in solid-state Li-Li symmetrical cells. This work provides vital reference for improving the interface compatibility for room temperature solid-state lithium batteries.

Gassing in Li4Ti5O12-based batteries and its remedy

PubMed Central

He, Yan-Bing; Li, Baohua; Liu, Ming; Zhang, Chen; Lv, Wei; Yang, Cheng; Li, Jia; Du, Hongda; Zhang, Biao; Yang, Quan-Hong; Kim, Jang-Kyo; Kang, Feiyu

2012-01-01

Destructive gas generation with associated swelling has been a major challenge to the large-scale application of lithium ion batteries (LIBs) made from Li4Ti5O12 (LTO) anodes. Here we report root causes of the gassing behavior, and suggest remedy to suppress it. The generated gases mainly contain H2, CO2 and CO, which originate from interfacial reactions between LTO and surrounding alkyl carbonate solvents. The reactions occur at the very thin outermost surface of LTO (111) plane, which result in transformation from (111) to (222) plane and formation of (101) plane of anatase TiO2. A nanoscale carbon coating along with a stable solid electrolyte interface (SEI) film around LTO is seen most effective as a barrier layer in suppressing the interfacial reaction and resulting gassing from the LTO surface. Such an ability to tune the interface nanostructure of electrodes has practical implications in the design of next-generation high power LIBs. PMID:23209873

High strength porous support tubes for high temperature solid electrolyte electrochemical cells

DOEpatents

Rossing, Barry R.; Zymboly, Gregory E.

1986-01-01

A high temperature, solid electrolyte electrochemical cell is made, having an electrode and a solid electrolyte disposed on a porous, sintered support material containing thermally stabilized zirconia powder particles and from about 3 wt. % to about 45 wt. % of thermally stable oxide fibers.

Challenges in Accommodating Volume Change of Si Anodes for Li-Ion Batteries

PubMed Central

Ko, Minseong; Chae, Sujong; Cho, Jaephil

2015-01-01

Si has been considered as a promising alternative anode for next-generation Li-ion batteries (LIBs) because of its high theoretical energy density, relatively low working potential, and abundance in nature. However, Si anodes exhibit rapid capacity decay and an increase in the internal resistance, which are caused by the large volume changes upon Li insertion and extraction. This unfortunately limits their practical applications. Therefore, managing the total volume change remains a critical challenge for effectively alleviating the mechanical fractures and instability of solid-electrolyte-interphase products. In this regard, we review the recent progress in volume-change-accommodating Si electrodes and investigate their ingenious structures with significant improvements in the battery performance, including size-controlled materials, patterned thin films, porous structures, shape-preserving shell designs, and graphene composites. These representative approaches potentially overcome the large morphologic changes in the volume of Si anodes by securing the strain relaxation and structural integrity in the entire electrode. Finally, we propose perspectives and future challenges to realize the practical application of Si anodes in LIB systems. PMID:27525208

Post oxygen treatment characteristics of coke as an anode material for Li-ion batteries.

PubMed

Kim, Jae-Hun; Park, Min-Sik; Jo, Yong Nam; Yu, Ji-Sang; Jeong, Goojin; Kim, Young-Jun

2013-05-01

The effect of a oxygen treatment on the electrochemical characteristics of a soft carbon anode material for Li-ion batteries was investigated. After a coke carbonization process at 1000 degrees C in an argon atmosphere, the samples were treated under a flow of oxygen gas to obtain a mild oxidation effect. After this oxygen treatment, the coke samples exhibited an improved initial coulombic efficiency and cycle performance as compared to the carbonized sample. High-resolution transmission electron microscopy revealed that the carbonized cokes consisted of disordered and nanosized graphene layers and the surface of the modified carbon was significantly changed after the treatment. The chemical state of the cokes was analyzed using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The enhanced electrochemical properties of the surface modified cokes could be attributed to the mild oxidation effect induced by the oxygen treatment. The mild oxidation process could have led to the elimination of surface imperfections and the reinforcement of a solid electrolyte interphase film, which resulted in the improved electrochemical characteristics.

Self-Volatilization Approach to Mesoporous Carbon Nanotube/Silver Nanoparticle Hybrids: The Role of Silver in Boosting Li Ion Storage.

PubMed

Jiang, Hao; Zhang, Haoxuan; Fu, Yao; Guo, Shaojun; Hu, Yanjie; Zhang, Ling; Liu, Yu; Liu, Honglai; Li, Chunzhong

2016-01-26

One of the biggest challenging issues of carbon nanomaterials for Li ion batteries (LIBs) is that they show low initial Coulombic efficiency (CE), leading to a limited specific capacity. Herein, we demonstrate a simple template self-volatilization strategy for in situ synthesis of mesoporous carbon nanotube/Ag nanoparticle (NP) hybrids (Ag-MCNTs) to boost the LIBs' performance. The key concept of Ag-MCNTs for enhancing LIBs is that a small trace of Ag NPs on MCNTS can greatly restrict the formation of a thicker solid electrolyte interphase film, which has been well verified by both transmission electron microscopy results and quantum density functional theory calculations, leading to the highest initial CE in all the reported carbon nanomaterials. This uncovered property of Ag NPs from Ag-MCNTs makes them exhibit a very high reversible capacity of 1637 mAh g(-1) after 400 discharge/charge cycles at 100 mA g(-1), approximately 5 times higher than the theoretical value of a graphite anode (372 mAh g(-1)), excellent rate capability, and long cycle life.

Dry-air-stable lithium silicide-lithium oxide core-shell nanoparticles as high-capacity prelithiation reagents.

PubMed

Zhao, Jie; Lu, Zhenda; Liu, Nian; Lee, Hyun-Wook; McDowell, Matthew T; Cui, Yi

2014-10-03

Rapid progress has been made in realizing battery electrode materials with high capacity and long-term cyclability in the past decade. However, low first-cycle Coulombic efficiency as a result of the formation of a solid electrolyte interphase and Li trapping at the anodes, remains unresolved. Here we report LixSi-Li2O core-shell nanoparticles as an excellent prelithiation reagent with high specific capacity to compensate the first-cycle capacity loss. These nanoparticles are produced via a one-step thermal alloying process. LixSi-Li2O core-shell nanoparticles are processible in a slurry and exhibit high capacity under dry-air conditions with the protection of a Li2O passivation shell, indicating that these nanoparticles are potentially compatible with industrial battery fabrication processes. Both Si and graphite anodes are successfully prelithiated with these nanoparticles to achieve high first-cycle Coulombic efficiencies of 94% to >100%. The LixSi-Li2O core-shell nanoparticles enable the practical implementation of high-performance electrode materials in lithium-ion batteries.

Solid polymer electrolyte lithium batteries

DOEpatents

Alamgir, M.; Abraham, K.M.

1993-10-12

This invention pertains to Lithium batteries using Li ion (Li[sup +]) conductive solid polymer electrolytes composed of solvates of Li salts immobilized in a solid organic polymer matrix. In particular, this invention relates to Li batteries using solid polymer electrolytes derived by immobilizing solvates formed between a Li salt and an aprotic organic solvent (or mixture of such solvents) in poly(vinyl chloride). 3 figures.

Solid polymer electrolyte lithium batteries

DOEpatents

Alamgir, Mohamed; Abraham, Kuzhikalail M.

1993-01-01

This invention pertains to Lithium batteries using Li ion (Li.sup.+) conductive solid polymer electrolytes composed of solvates of Li salts immobilized in a solid organic polymer matrix. In particular, this invention relates to Li batteries using solid polymer electrolytes derived by immobilizing solvates formed between a Li salt and an aprotic organic solvent (or mixture of such solvents) in poly(vinyl chloride).

Flexible poly(ethylene carbonate)/garnet composite solid electrolyte reinforced by poly(vinylidene fluoride-hexafluoropropylene) for lithium metal batteries

NASA Astrophysics Data System (ADS)

He, Zijian; Chen, Long; Zhang, Bochen; Liu, Yongchang; Fan, Li-Zhen

2018-07-01

Solid-state electrolytes with high ionic conductivities, great flexibility, and easy processability are needed for high-performance solid-state rechargeable lithium batteries. In this work, we synthesize nanosized cubic Li6.25Al0.25La3Zr2O12 (LLZO) by solution combustion method and develop a flexible garnet-based composite solid electrolyte composed of LLZO, poly(ethylene carbonate) (PEC), poly(vinylidene fluoride-hexafluoropropylene) (P(VdF-HFP) and lithium bis(fluorosulfonyl)imide (LiFSI)). In the flexible composite solid electrolytes, LLZO nanoparticles, as ceramic matrix, have a positive effect on ionic conductivities and lithium ion transference number (tLi+). PEC, as a fast ion-conducting polymer, possesses high tLi+ inherently. P(VdF-HFP), as a binder, can strengthen mechanical properties. Consequently, the as-prepared composite solid electrolyte demonstrates high tLi+ (0.82) and superb thermal stability (remaining LLZO matrix after burning). All-solid-state LiFePO4|Li cells assembled with the flexible composite solid electrolyte deliver a high initial discharge specific capacity of 121.4 mAh g-1 and good cycling stability at 55 °C.

A stable perovskite electrolyte in moist air for Li-ion batteries.

PubMed

Li, Yutao; Xu, Henghui; Chien, Po-Hsiu; Wu, Nan; Xin, Sen; Xue, Leigang; Park, Kyusung; Hu, Yan-Yan; Goodenough, John B

2018-05-07

Solid-oxide Li+ electrolytes of a rechargeable cell are generally sensitive to moisture in the air, H+ exchanges for the mobile Li+ of the electrolyte and forms insulating surface phases at the electrolyte interfaces and in the grain boundaries of a polycrystalline membrane. These surface phases dominate the total interfacial resistance of a conventional rechargeable cell having a solid-electrolyte separator. We report a new perovskite Li+ solid electrolyte, Li0.38Sr0.44Ta0.7Hf0.3O2.95F0.05, having a Li-ion conductivity σLi = 4.8×10-4 S cm-1 at 25 oC that does not react with water having 3≤pH≤14. The solid electrolyte with a thin Li+-conducting polymer on its surface to prevent reduction of Ta5+ is wet by metallic lithium and provides low-impedance dendrite-free plating/stripping of a lithium anode. It is also stable on contact with a composite polymer cathode. With this solid electrolyte, we demonstrate excellent cycling performance of an all-solid-state Li/LiFePO4 cell, a Li-S cell with a polymer-gel cathode, and a supercapacitor. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solvation-controlled lithium-ion complexes in a nonflammable solvent containing ethylene carbonate: structural and electrochemical aspects.

PubMed

Sogawa, Michiru; Kawanoue, Hikaru; Todorov, Yanko Marinov; Hirayama, Daisuke; Mimura, Hideyuki; Yoshimoto, Nobuko; Morita, Masayuki; Fujii, Kenta

2018-02-28

The structural and electrochemical properties of lithium-ion solvation complexes in a nonflammable organic solvent, tris(2,2,2-trifluoroethyl)phosphate (TFEP) containing ethylene carbonate (EC), were investigated using vibrational spectroscopic and electrochemical measurements. Based on quantitative Raman and infrared (IR) spectral analysis of the Li bis(trifluoromethanesulfonyl)amide (TFSA) salt in TFEP + EC electrolytes, we successfully evaluated the individual solvation numbers of EC (n EC ), TFEP (n TFEP ), and TFSA - (n TFSA ) in the first solvation sphere of the Li-ion. We found that the n EC value linearly increased with increasing EC mole fraction (x EC ), whereas the n TFEP and n TFSA values gradually decreased with increasing n EC . The ionic conductivity and viscosity (Walden plots) indicated that mainly Li + TFSA - ion pairs formed in neat TFEP (x EC = 0). This ion pair gradually dissociated into positively charged Li-ion complexes as x EC increased, which was consistent with the Raman/IR spectroscopy results. The redox reaction corresponding to an insertion/desertion of Li-ion into/from the graphite electrode occurred in the LiTFSA/TFEP + EC system at x EC ≥ 0.25. The same was not observed in the lower x EC cases. We discussed the relation between Li-ion solvation and electrode reaction behaviors at the molecular level and proposed that n EC plays a crucial role in the electrode reaction, particularly in terms of solid electrolyte interphase formation on the graphite electrode.

Surface Chemistry and Precursor Material Effects on the Performance of Pyrolyzed Nanofibers as Anodes for Lithium-ion Batteries

NASA Astrophysics Data System (ADS)

Loebl, Andrew James

Next-generation lithium-ion batteries to meet consumer demands and new applications require the development of new electrode materials. Electrospinning of polymers is a simple and effective method to create one-dimensional, self-supporting materials, with no inactive components after pyrolysis. Composites of these nanofibers and high-capacity lithium materials have been demonstrated to possess superior reversible capacity than state-of-the-art commercial anodes. Despite impressive reversible discharge capacities polyacrylonitrile-based composites are not ready for adoption in commercial applications. These materials suffer from irreversible losses of Li to formation on the electrode of the solid electrolyte interphase during the first charge of the cell. This thesis work has taken two approaches to engineer high-performing nanofiber-based electrodes. First, the chemistry at the interface of the electrode and the electrolyte has been changed by depositing new surfaces. Attempts to create a graphitic fiber surface via plasma enhanced chemical vapor deposition did not result in an improvement of the irreversible losses. However, the experiments did demonstrate the growth of large surface area carbon nanowalls on the pyrolyzed electrospun fibers, creating a material which could serve as a substrate in catalysis or as an electrode for composite ultra-capacitors. Additionally, passivation surfaces were deposited by atomic layer deposition and molecular layer deposition. These new surfaces were employed to reduce the irreversible consumption of lithium by moving the charge transfer reaction to the interface of the carbon and the new material. The removal the lithium from the solvent prior to charge transfer limits the irreversible reduction of solvent by metallic lithium. Alumina films grown by atomic layer deposition reduced lithium losses to the solid electrolyte interphase by up to 42% for twenty deposition cycles. This large improvement in irreversible capacity resulted in a nearly 50% reduction in reversible lithium storage. Thinner coatings of alumina had a less dramatic effect on both the irreversible capacity losses and the reversible discharge capacity. A coating of ten cycles of alumina at a temperature of 150 °C resulted in a 17% reduction in irreversible capacity with negligible impact on the reversible capacity. Hybrid aluminum-organic films grown by molecular layer deposition also reduced irreversible lithium losses. The largest reduction was 23% for electrodes coated with 40 cycles of the alucone material. For all thicknesses studied these hybrid films delivered less improvement than the alumina grown by atomic layer deposition, with poor reversible lithium storage capacity available at high charging and discharging currents. Second, polyacrylonitrile has served as the precursor for electrospun composite electrodes because of its ease of processing and well-known carbonization process. Polyimides represent a family of polymers for which the material properties can be tailored by careful monomer selection. These polymers were used as the non-woven matrix to create materials capable of delivering a larger percentage of their maximum reversible capacities at high currents when compared to polyacrylonitrile-based electrodes. These materials had a more graphitic structure based on Raman spectroscopy, and resulted in lower irreversible capacity losses than polyacrylonitrile-based fibers for fibers based on pyromellitic dianhydride and p-phenylene diamine.

Solid polymer electrolyte compositions

DOEpatents

Garbe, James E.; Atanasoski, Radoslav; Hamrock, Steven J.; Le, Dinh Ba

2001-01-01

An electrolyte composition is featured that includes a solid, ionically conductive polymer, organically modified oxide particles that include organic groups covalently bonded to the oxide particles, and an alkali metal salt. The electrolyte composition is free of lithiated zeolite. The invention also features cells that incorporate the electrolyte composition.

A Unique Hybrid Quasi-Solid-State Electrolyte for Li-O2 Batteries with Improved Cycle Life and Safety.

PubMed

Yi, Jin; Zhou, Haoshen

2016-09-08

In the context of the development of electric vehicle to solve the contemporary energy and environmental issues, the possibility of pushing future application of Li-O2 batteries as a power source for electric vehicles is particularly attractive. However, safety concerns, mainly derived from the use of flammable organic liquid electrolytes, become a major bottleneck for the strategically crucial applications of Li-O2 batteries. To overcome this issue, rechargeable solid-state Li-O2 batteries with enhanced safety is regarded as an appealing candidate. In this study, a hybrid quasi-solid-state electrolyte combing a polymer electrolyte with a ceramic electrolyte is first designed and explored for Li-O2 batteries. The proposed rechargeable solid-state Li-O2 battery delivers improved cycle life (>100 cycles) and safety. The feasibility study demonstrates that the hybrid quasi-solid-state electrolytes could be employed as a promising alternative strategy for the development of rechargeable Li-O2 batteries, hence encouraging more efforts devoted to explore other hybrid solid-state electrolytes for Li-O2 batteries upon future application. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon dioxide as a green carbon source for the synthesis of carbon cages encapsulating porous silicon as high performance lithium-ion battery anodes.

PubMed

Zhang, Yaguang; Du, Ning; Chen, Yifan; Lin, Yangfan; Jiang, Jinwei; He, Yuanhong; Lei, Yu; Yang, Deren

2018-03-28

Si/C composite is one of the most promising candidate materials for next-generation lithium-ion battery anodes. Herein, we demonstrate the novel structure of carbon cages encapsulating porous Si synthesized by the reaction between magnesium silicide (Mg 2 Si) and carbon dioxide (CO 2 ) and subsequent acid washing. Benefitting from the in situ deposition through magnesiothermic reduction of CO 2 , the carbon cage seals the inner Si completely and shows higher graphitization than that obtained from the decomposition of acetylene. After removing MgO, pores are created, which can accommodate the volume change of the Si anode during the charge/discharge process. As the anode material for lithium-ion batteries, the porous Si/C electrode shows a charge capacity of ∼1124 mA h g -1 after 100 cycles with 86.4% capacity retention at the current density of 0.4 A g -1 . When the current density increases to 1.6 and 3.2 A g -1 , the capacity can still be maintained at ∼860 and ∼460 mA h g -1 , respectively. The prominent cycling and rate performance is contributed by the built-in space for Si expansion, static carbon cages that prevent penetration of electrolyte and stabilize the solid electrolyte interface (SEI) outside, and fast charge transport by the novel structure.

Solid-state rechargeable magnesium battery

DOEpatents

Shao, Yuyan; Liu, Jun; Liu, Tianbiao; Li, Guosheng

2016-09-06

Embodiments of a solid-state electrolyte comprising magnesium borohydride, polyethylene oxide, and optionally a Group IIA or transition metal oxide are disclosed. The solid-state electrolyte may be a thin film comprising a dispersion of magnesium borohydride and magnesium oxide nanoparticles in polyethylene oxide. Rechargeable magnesium batteries including the disclosed solid-state electrolyte may have a coulombic efficiency .gtoreq.95% and exhibit cycling stability for at least 50 cycles.

Highly Stable Operation of Lithium Metal Batteries Enabled by the Formation of a Transient High Concentration Electrolyte Layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jianming; Yan, Pengfei; Mei, Donghai

2016-02-08

Lithium (Li) metal has been extensively investigated as an anode for rechargeable battery applications due to its ultrahigh specific capacity and the lowest redox potential. However, significant challenges including dendrite growth and low Coulombic efficiency are still hindering the practical applications of rechargeable Li metal batteries. Here, we demonstrate that long-term cycling of Li metal batteries can be realized by the formation of a transient high concentration electrolyte layer near the surface of Li metal anode during high rate discharge process. The highly concentrated Li+ ions in this transient layer will immediately solvate with the available solvent molecules and facilitatemore » the formation of a stable and flexible SEI layer composed of a poly(ethylene carbonate) framework integrated with other organic/inorganic lithium salts. This SEI layer largely suppresses the corrosion of Li metal anode by free organic solvents and enables the long-term operation of Li metal batteries. The fundamental findings in this work provide a new direction for the development and operation of Li metal batteries that could be operated at high current densities for a wide range of applications.« less

A high-conduction Ge substituted Li3AsS4 solid electrolyte with exceptional low activation energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahu, Gayatri; Rangasamy, Ezhiylmurugan; Li, Juchuan

2014-04-16

In lithium-ion conducting solid electrolytes the potential to enable high-energy-density secondary batteries and offer distinctive safety features as an advantage over traditional liquid electrolytes is shown. Achieving the combination of high ionic conductivity, low activation energy, and outstanding electrochemical stability in crystalline solid electrolytes is a challenge for the synthesis of novel solid electrolytes. We report an exceptionally low activation energy (Ea) and high room temperature superionic conductivity via facile aliovalent substitution of Li 3AsS 4 by Ge, which increased the conductivity by two orders of magnitude as compared to the parent compound. The composition Li 3.334Ge 0.334As 0.666S 4more » has a high ionic conductivity of 1.12 mScm -1 at 27°C. Local Li + hopping in this material is accompanied by distinctive low activation energy Ea of 0.17 eV being the lowest of Li + solid conductors. Finally, our study demonstrates the efficacy of surface passivation of solid electrolyte to achieve compatibility with metallic lithium electrodes.« less

High-surface-area mesoporous TiO2 microspheres via one-step nanoparticle self-assembly for enhanced lithium-ion storage

NASA Astrophysics Data System (ADS)

Wang, Hsin-Yi; Chen, Jiazang; Hy, Sunny; Yu, Linghui; Xu, Zhichuan; Liu, Bin

2014-11-01

Mesoporous TiO2 microspheres assembled from TiO2 nanoparticles with specific surface areas as high as 150 m2 g-1 were synthesized via a facile one-step solvothermal reaction of titanium isopropoxide and anhydrous acetone. Aldol condensation of acetone gradually releases structural H2O, which hydrolyzes and condenses titanium isopropoxide, forming TiO2 nanocrystals. Simultaneous growth and aggregation of TiO2 nanocrystals leads to the formation of high-surface-area TiO2 microspheres under solvothermal conditions. After a low-temperature post-synthesis calcination, carbonate could be incorporated into TiO2 as a dopant with the carbon source coming from the organic byproducts during the synthesis. Carbonate doping modifies the electronic structure of TiO2 (e.g., Fermi level, Ef), and thus influences its electrochemical properties. Solid electrolyte interface (SEI) formation, which is not common for titania, could be initiated in carbonate-doped TiO2 due to elevated Ef. After removing carbonate dopants by high-temperature calcination, the mesoporous TiO2 microspheres showed much improved performance in lithium insertion and stability at various current rates, attributed to a synergistic effect of high surface area, large pore size and good anatase crystallinity.Mesoporous TiO2 microspheres assembled from TiO2 nanoparticles with specific surface areas as high as 150 m2 g-1 were synthesized via a facile one-step solvothermal reaction of titanium isopropoxide and anhydrous acetone. Aldol condensation of acetone gradually releases structural H2O, which hydrolyzes and condenses titanium isopropoxide, forming TiO2 nanocrystals. Simultaneous growth and aggregation of TiO2 nanocrystals leads to the formation of high-surface-area TiO2 microspheres under solvothermal conditions. After a low-temperature post-synthesis calcination, carbonate could be incorporated into TiO2 as a dopant with the carbon source coming from the organic byproducts during the synthesis. Carbonate doping modifies the electronic structure of TiO2 (e.g., Fermi level, Ef), and thus influences its electrochemical properties. Solid electrolyte interface (SEI) formation, which is not common for titania, could be initiated in carbonate-doped TiO2 due to elevated Ef. After removing carbonate dopants by high-temperature calcination, the mesoporous TiO2 microspheres showed much improved performance in lithium insertion and stability at various current rates, attributed to a synergistic effect of high surface area, large pore size and good anatase crystallinity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04729j

Recent Developments of All-Solid-State Lithium Secondary Batteries with Sulfide Inorganic Electrolytes.

PubMed

Xu, Ruochen; Zhang, Shengzhao; Wang, Xiuli; Xia, Yan; Xia, Xinhui; Wu, Jianbo; Gu, Changdong; Tu, Jiangping

2018-04-20

Due to the increasing demand of security and energy density, all-solid-state lithium ion batteries have become the promising next-generation energy storage devices to replace the traditional liquid batteries with flammable organic electrolytes. In this Minireview, we focus on the recent developments of sulfide inorganic electrolytes for all-solid-state batteries. The challenges of assembling bulk-type all-solid-state batteries for industrialization are discussed, including low ionic conductivity of the present sulfide electrolytes, high interfacial resistance and poor compatibility between electrolytes and electrodes. Many efforts have been focused on the solutions for these issues. Although some progresses have been achieved, it is still far away from practical application. The perspectives for future research on all-solid-state lithium ion batteries are presented. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-performance graphene/sulphur electrodes for flexible Li-ion batteries using the low-temperature spraying method

NASA Astrophysics Data System (ADS)

Kumar, Pushpendra; Wu, Feng-Yu; Hu, Lung-Hao; Ali Abbas, Syed; Ming, Jun; Lin, Chia-Nan; Fang, Jason; Chu, Chih-Wei; Li, Lain-Jong

2015-04-01

Elementary sulphur (S) has been shown to be an excellent cathode material in energy storage devices such as Li-S batteries owing to its very high capacity. The major challenges associated with the sulphur cathodes are structural degradation, poor cycling performance and instability of the solid-electrolyte interphase caused by the dissolution of polysulfides during cycling. Tremendous efforts made by others have demonstrated that encapsulation of S materials improves their cycling performance. To make this approach practical for large scale applications, the use of low-cost technology and materials has become a crucial and new focus of S-based Li-ion batteries. Herein, we propose to use a low temperature spraying process to fabricate graphene/S electrode material, where the ink is composed of graphene flakes and the micron-sized S particles prepared by grinding of low-cost S powders. The S particles are found to be well hosted by highly conductive graphene flakes and consequently superior cyclability (~70% capacity retention after 250 cycles), good coulombic efficiency (~98%) and high capacity (~1500 mA h g-1) are obtained. The proposed approach does not require high temperature annealing or baking; hence, another great advantage is to make flexible Li-ion batteries. We have also demonstrated two types of flexible batteries using sprayed graphene/S electrodes.Elementary sulphur (S) has been shown to be an excellent cathode material in energy storage devices such as Li-S batteries owing to its very high capacity. The major challenges associated with the sulphur cathodes are structural degradation, poor cycling performance and instability of the solid-electrolyte interphase caused by the dissolution of polysulfides during cycling. Tremendous efforts made by others have demonstrated that encapsulation of S materials improves their cycling performance. To make this approach practical for large scale applications, the use of low-cost technology and materials has become a crucial and new focus of S-based Li-ion batteries. Herein, we propose to use a low temperature spraying process to fabricate graphene/S electrode material, where the ink is composed of graphene flakes and the micron-sized S particles prepared by grinding of low-cost S powders. The S particles are found to be well hosted by highly conductive graphene flakes and consequently superior cyclability (~70% capacity retention after 250 cycles), good coulombic efficiency (~98%) and high capacity (~1500 mA h g-1) are obtained. The proposed approach does not require high temperature annealing or baking; hence, another great advantage is to make flexible Li-ion batteries. We have also demonstrated two types of flexible batteries using sprayed graphene/S electrodes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00885a

Complex hydrides as room-temperature solid electrolytes for rechargeable batteries

NASA Astrophysics Data System (ADS)

de Jongh, P. E.; Blanchard, D.; Matsuo, M.; Udovic, T. J.; Orimo, S.

2016-03-01

A central goal in current battery research is to increase the safety and energy density of Li-ion batteries. Electrolytes nowadays typically consist of lithium salts dissolved in organic solvents. Solid electrolytes could facilitate safer batteries with higher capacities, as they are compatible with Li-metal anodes, prevent Li dendrite formation, and eliminate risks associated with flammable organic solvents. Less than 10 years ago, LiBH4 was proposed as a solid-state electrolyte. It showed a high ionic conductivity, but only at elevated temperatures. Since then a range of other complex metal hydrides has been reported to show similar characteristics. Strategies have been developed to extend the high ionic conductivity of LiBH4 down to room temperature by partial anion substitution or nanoconfinement. The present paper reviews the recent developments in complex metal hydrides as solid electrolytes, discussing in detail LiBH4, strategies towards for fast room-temperature ionic conductors, alternative compounds, and first explorations of implementation of these electrolytes in all-solid-state batteries.

Nano-sponge ionic liquid-polymer composite electrolytes for solid-state lithium power sources

NASA Astrophysics Data System (ADS)

Liao, Kang-Shyang; Sutto, Thomas E.; Andreoli, Enrico; Ajayan, Pulickel; McGrady, Karen A.; Curran, Seamus A.

Solid polymer gel electrolytes composed of 75 wt.% of the ionic liquid, 1- n-butyl-2,3-dimethylimidazolium bis-trifluoromethanesulfonylimide with 1.0 M lithium bis-trifluoromethanesulfonylimide and 25 wt.% poly(vinylidenedifluoro-hexafluoropropene) are characterized as the electrolyte/separator in solid-state lithium batteries. The ionic conductivity of these gels ranges from 1.5 to 2.0 mS cm -1, which is several orders of magnitude more conductive than any of the more commonly used solid polymers, and comparable to the best solid gel electrolytes currently used in industry. TGA indicates that these polymer gel electrolytes are thermally stable to over 280 °C, and do not begin to thermally decompose until over 300 °C; exhibiting a significant advancement in the safety of lithium batteries. Atomic force microscopy images of these solid thin films indicate that these polymer gel electrolytes have the structure of nano-sponges, with a sub-micron pore size. For these thin film batteries, 150 charge-discharge cycles are run for Li xCoO 2 where x is cycled between 0.95 down to 0.55. Minimal internal resistance effects are observed over the charging cycles, indicating the high ionic conductivity of the ionic liquid solid polymer gel electrolyte. The overall cell efficiency is approximately 98%, and no significant loss in battery efficiency is observed over the 150 cycles.

Application of Organic Solid Electrolytes

NASA Technical Reports Server (NTRS)

Sekido, S.

1982-01-01

If ions are considered to be solid material which transport electric charges, polymer materials can then be considered as organic solid electrolytes. The role of these electrolytes is discussed for (1) ion concentration sensors; (2) batteries using lithium as the cathode and a charge complex of organic material and iodine in the anode; and (3) elements applying electrical double layer capability.

A Newly Designed Composite Gel Polymer Electrolyte Based on Poly(Vinylidene Fluoride-Hexafluoropropylene) (PVDF-HFP) for Enhanced Solid-State Lithium-Sulfur Batteries.

PubMed

Xia, Yan; Wang, Xiuli; Xia, Xinhui; Xu, Ruochen; Zhang, Shengzhao; Wu, Jianbo; Liang, Yanfei; Gu, Changdong; Tu, Jiangping

2017-10-26

Developing high-performance solid-state electrolytes is crucial for the innovation of next-generation lithium-sulfur batteries. Herein, a facile method for preparation of a novel gel polymer electrolyte (GPE) based on poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) is reported. Furthermore, Li 1.5 Al 0.5 Ti 1.5 (PO 4 ) 3 (LATP) nanoparticles as the active fillers are uniformly embedded into the GPE to form the final PVDF-HFP/LATP composite gel polymer electrolyte (CPE). Impressively, the obtained CPE demonstrates a high lithium ion transference number of 0.51 and improved electrochemical stability as compared to commercial liquid electrolyte. In addition, the assembled solid-sate Li-S battery with the composite gel polymer electrolyte membrane presents a high initial capacity of 918 mAh g -1 at 0.05 C, and better cycle performance than the counterparts with liquid electrolyte. Our designed PVDF-HFP/LATP composite can be a promising electrolyte for next-generation solid-state batteries with high cycling stability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ilmenite Nanotubes for High Stability and High Rate Sodium-Ion Battery Anodes.

PubMed

Yu, Litao; Liu, Jun; Xu, Xijun; Zhang, Liguo; Hu, Renzong; Liu, Jiangwen; Ouyang, Liuzhang; Yang, Lichun; Zhu, Min

2017-05-23

To solve the problem of large volume change and low electronic conductivity of earth-abundant ilmenite used in rechargeable Na-ion batteries (SIBs), an anode of tiny ilmenite FeTiO 3 nanoparticle embedded carbon nanotubes (FTO⊂CNTs) has been successfully proposed. By introducing a TiO 2 shell on metal-organic framework (Fe-MOF) nanorods by sol-gel deposition and subsequent solid-state annealing treatment of these core-shell Fe-MOF@TiO 2 , such well-defined FTO⊂CNTs are obtained. The achieved FTO⊂CNT electrode has several distinct advantages including a hollow interior in the hybrid nanostructure, fully encapsulated ultrasmall electroactive units, flexible conductive carbon matrix, and stable solid electrolyte interface (SEI) of FTO in cycles. FTO⊂CNT electrodes present an excellent cycle stability (358.8 mA h g -1 after 200 cycles at 100 mA g -1 ) and remarkable rate capability (201.8 mA h g -1 at 5000 mA g -1 ) with a high Coulombic efficiency of approximately 99%. In addition, combined with the typical Na 3 V 2 (PO 4 ) 3 cathode to constitute full SIBs, the assembled FTO⊂CNT//Na 3 V 2 (PO 4 ) 3 batteries are also demonstrated with superior rate capability and a long cycle life.

Nanostructure enhanced ionic transport in fullerene reinforced solid polymer electrolytes.

PubMed

Sun, Che-Nan; Zawodzinski, Thomas A; Tenhaeff, Wyatt E; Ren, Fei; Keum, Jong Kahk; Bi, Sheng; Li, Dawen; Ahn, Suk-Kyun; Hong, Kunlun; Rondinone, Adam J; Carrillo, Jan-Michael Y; Do, Changwoo; Sumpter, Bobby G; Chen, Jihua

2015-03-28

Solid polymer electrolytes, such as polyethylene oxide (PEO) based systems, have the potential to replace liquid electrolytes in secondary lithium batteries with flexible, safe, and mechanically robust designs. Previously reported PEO nanocomposite electrolytes routinely use metal oxide nanoparticles that are often 5-10 nm in diameter or larger. The mechanism of those oxide particle-based polymer nanocomposite electrolytes is under debate and the ion transport performance of these systems is still to be improved. Herein we report a 6-fold ion conductivity enhancement in PEO/lithium bis(trifluoromethanesulfonyl) imide (LiTFSI)-based solid electrolytes upon the addition of fullerene derivatives. The observed conductivity improvement correlates with nanometer-scale fullerene crystallite formation, reduced crystallinities of both the (PEO)6:LiTFSI phase and pure PEO, as well as a significantly larger PEO free volume. This improved performance is further interpreted by enhanced decoupling between ion transport and polymer segmental motion, as well as optimized permittivity and conductivity in bulk and grain boundaries. This study suggests that nanoparticle induced morphological changes, in a system with fullerene nanoparticles and no Lewis acidic sites, play critical roles in their ion conductivity enhancement. The marriage of fullerene derivatives and solid polymer electrolytes opens up significant opportunities in designing next-generation solid polymer electrolytes with improved performance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hui; Chen, Yan; Hood, Zachary D.

All-solid-state sodium batteries, using abundant sodium resources and solid electrolyte, hold much promise for safe, low cost, large-scale energy storage. To realize the practical applications of all solid Na-ion batteries at ambient temperature, the solid electrolytes are required to have high ionic conductivity, chemical stability, and ideally, easy preparation. Ceramic electrolytes show higher ionic conductivity than polymers, but they often require extremely stringent synthesis conditions, either high sintering temperature above 1000 C or long-time, low-energy ball milling. Herein, we report a new synthesis route for Na 3SbS 4, a novel Na superionic conductor that needs much lower processing temperature belowmore » 200 C and easy operation. This new solid electrolyte exhibits a remarkable ionic conductivity of 1.05 mS cm -1 at 25 °C and is chemically stable under ambient atmosphere. In conclusion, this synthesis process provides unique insight into the current state-of-the-art solid electrolyte preparation and opens new possibilities for the design of similar materials.« less

Accessing the bottleneck in all-solid state batteries, lithium-ion transport over the solid-electrolyte-electrode interface.

PubMed

Yu, Chuang; Ganapathy, Swapna; Eck, Ernst R H van; Wang, Heng; Basak, Shibabrata; Li, Zhaolong; Wagemaker, Marnix

2017-10-20

Solid-state batteries potentially offer increased lithium-ion battery energy density and safety as required for large-scale production of electrical vehicles. One of the key challenges toward high-performance solid-state batteries is the large impedance posed by the electrode-electrolyte interface. However, direct assessment of the lithium-ion transport across realistic electrode-electrolyte interfaces is tedious. Here we report two-dimensional lithium-ion exchange NMR accessing the spontaneous lithium-ion transport, providing insight on the influence of electrode preparation and battery cycling on the lithium-ion transport over the interface between an argyrodite solid-electrolyte and a sulfide electrode. Interfacial conductivity is shown to depend strongly on the preparation method and demonstrated to drop dramatically after a few electrochemical (dis)charge cycles due to both losses in interfacial contact and increased diffusional barriers. The reported exchange NMR facilitates non-invasive and selective measurement of lithium-ion interfacial transport, providing insight that can guide the electrolyte-electrode interface design for future all-solid-state batteries.

High Performance Solid Polymer Electrolytes for Rechargeable Batteries: A Self-Catalyzed Strategy toward Facile Synthesis.

PubMed

Cui, Yanyan; Liang, Xinmiao; Chai, Jingchao; Cui, Zili; Wang, Qinglei; He, Weisheng; Liu, Xiaochen; Liu, Zhihong; Cui, Guanglei; Feng, Jiwen

2017-11-01

It is urgent to seek high performance solid polymer electrolytes (SPEs) via a facile chemistry and simple process. The lithium salts are composed of complex anions that are stabilized by a Lewis acid agent. This Lewis acid can initiate the ring opening polymerization. Herein, a self-catalyzed strategy toward facile synthesis of crosslinked poly(ethylene glycol) diglycidyl ether-based solid polymer electrolyte (C-PEGDE) is presented. It is manifested that the poly(ethylene glycol) diglycidyl ether-based solid polymer electrolyte possesses a superior electrochemical stability window up to 4.5 V versus Li/Li + and considerable ionic conductivity of 8.9 × 10 -5 S cm -1 at ambient temperature. Moreover, the LiFePO 4 /C-PEGDE/Li batteries deliver stable charge/discharge profiles and considerable rate capability. It is demonstrated that this self-catalyzed strategy can be a very effective approach for high performance solid polymer electrolytes.

Basic investigation into the electrical performance of solid electrolyte membranes

NASA Technical Reports Server (NTRS)

Richter, R.

1982-01-01

The electrical performance of solid electrolyte membranes was investigated analytically and the results were compared with experimental data. It is concluded that in devices that are used for pumping oxygen the major power losses have to be attributed to the thin film electrodes. Relations were developed by which the effectiveness of tubular solid electrolyte membranes can be determined and the optimum length evaluated. The observed failure of solid electrolyte tube membranes in very localized areas is explained by the highly non-uniform current distribution in the membranes. The analysis points to a possible contact resistance between the electrodes and the solid electrolyte material. This possible contact resistance remains to be investigated experimentally. It is concluded that film electrodes are not appropriate for devices which operate with current flow, i.e., pumps though they can be employed without reservation in devices that measure oxygen pressures if a limited increase in the response time can be tolerated.

Growth Kinetics of Magnesio-Aluminate Spinel in Al/Mg Lamellar Composite Interface

NASA Astrophysics Data System (ADS)

Fouad, Yasser; Rabeeh, Bakr Mohamed

The synthesis of Mg-Al2O3 double layered interface is introduced via the application of hot isostatic pressing, HIPing, in Al-Mg foils. Polycrystalline spinel layers are grown experimentally at the interfacial contacts between Al-Mg foils. The growth behavior of the spinel layers along with the kinetic parameters characterizing interface motion and long-range diffusion is established. Low melting depressant (LMD), Zn, and alloying element segregation tends to form micro laminated and/or Nano structure interphase in a lamellar composite solid state processing. Nano composite ceramic interphase materials offer interesting mechanical properties not achievable in other materials, such as superplastic flow and metal-like machinability. Microstructural characterization, mechanical characterization is also established via optical microscopy scanning electron microscopy, energy dispersive X-ray spectroscopy and tensile testing. Chemical and mechanical bonding via inter diffusion processing with alloy segregation are dominant for interphase kinetics. Mechanical characterization with interfacial shear strength is also introduced. HIPing processing is successfully applied on 6082 Al-alloy and AZ31 magnesium alloy for either particulate or micro-laminated interfacial composite processing. The interphase kinetic established through localized micro plasticity, metal flow, alloy segregation and delocalized Al oxide and Mg oxide. The kinetic of interface/interphase induce new nontraditional crack mitigation a long with new bridging and toughening mechanisms.

Chromatin Folding, Fragile Sites, and Chromosome Aberrations Induced by Low- and High- LET Radiation

NASA Technical Reports Server (NTRS)

Zhang, Ye; Cox, Bradley; Asaithamby, Aroumougame; Chen, David J.; Wu, Honglu

2013-01-01

We previously demonstrated non-random distributions of breaks involved in chromosome aberrations induced by low- and high-LET radiation. To investigate the factors contributing to the break point distribution in radiation-induced chromosome aberrations, human epithelial cells were fixed in G1 phase. Interphase chromosomes were hybridized with a multicolor banding in situ hybridization (mBAND) probe for chromosome 3 which distinguishes six regions of the chromosome in separate colors. After the images were captured with a laser scanning confocal microscope, the 3-dimensional structure of interphase chromosome 3 was reconstructed at multimega base pair scale. Specific locations of the chromosome, in interphase, were also analyzed with bacterial artificial chromosome (BAC) probes. Both mBAND and BAC studies revealed non-random folding of chromatin in interphase, and suggested association of interphase chromatin folding to the radiation-induced chromosome aberration hotspots. We further investigated the distribution of genes, as well as the distribution of breaks found in tumor cells. Comparisons of these distributions to the radiation hotspots showed that some of the radiation hotspots coincide with the frequent breaks found in solid tumors and with the fragile sites for other environmental toxins. Our results suggest that multiple factors, including the chromatin structure and the gene distribution, can contribute to radiation-induced chromosome aberrations.

Practical high temperature (80 °C) storage study of industrially manufactured Li-ion batteries with varying electrolytes

NASA Astrophysics Data System (ADS)

Genieser, R.; Loveridge, M.; Bhagat, R.

2018-05-01

A previous study is focused on high temperature cycling of industrially manufactured Li-ion pouch cells (NMC-111/Graphite) with different electrolytes at 80 °C [JPS 373 (2018) 172-183]. Within this article the same test set-up is used, with cells stored for 30 days at different open circuit potentials and various electrolytes instead of electrochemical cycling. The most pronounced cell degradation (capacity fade and resistance increase) happens at high potentials. However appropriate electrolyte formulations are able to suppress ageing conditions by forming passivating surface films on both electrodes. Compared with electrochemical cycling at 80 °C, cells with enhanced electrolytes only show a slight resistance increase during storage and the capacity fade is much lower. Additionally it is shown for the first time, that the resistance is decreasing and capacity is regained once these cells are cycled again at room temperature. This is not the case for electrolytes without additives or just vinylene carbonate (VC) as an additive. It is further shown that the resistance increase of cells with the other electrolytes is accompanied by a reduction of the cell volume during further cycling. This behaviour is likely related to the reduction of CO2 at the anode to form additional SEI layer components.

A review of lithium and non-lithium based solid state batteries

NASA Astrophysics Data System (ADS)

Kim, Joo Gon; Son, Byungrak; Mukherjee, Santanu; Schuppert, Nicholas; Bates, Alex; Kwon, Osung; Choi, Moon Jong; Chung, Hyun Yeol; Park, Sam

2015-05-01

Conventional lithium-ion liquid-electrolyte batteries are widely used in portable electronic equipment such as laptop computers, cell phones, and electric vehicles; however, they have several drawbacks, including expensive sealing agents and inherent hazards of fire and leakages. All solid state batteries utilize solid state electrolytes to overcome the safety issues of liquid electrolytes. Drawbacks for all-solid state lithium-ion batteries include high resistance at ambient temperatures and design intricacies. This paper is a comprehensive review of all aspects of solid state batteries: their design, the materials used, and a detailed literature review of various important advances made in research. The paper exhaustively studies lithium based solid state batteries, as they are the most prevalent, but also considers non-lithium based systems. Non-lithium based solid state batteries are attaining widespread commercial applications, as are also lithium based polymeric solid state electrolytes. Tabular representations and schematic diagrams are provided to underscore the unique characteristics of solid state batteries and their capacity to occupy a niche in the alternative energy sector.

Toward garnet electrolyte–based Li metal batteries: An ultrathin, highly effective, artificial solid-state electrolyte/metallic Li interface

PubMed Central

Fu, Kun (Kelvin); Gong, Yunhui; Liu, Boyang; Zhu, Yizhou; Xu, Shaomao; Yao, Yonggang; Luo, Wei; Wang, Chengwei; Lacey, Steven D.; Dai, Jiaqi; Chen, Yanan; Mo, Yifei; Wachsman, Eric; Hu, Liangbing

2017-01-01

Solid-state batteries are a promising option toward high energy and power densities due to the use of lithium (Li) metal as an anode. Among all solid electrolyte materials ranging from sulfides to oxides and oxynitrides, cubic garnet–type Li7La3Zr2O12 (LLZO) ceramic electrolytes are superior candidates because of their high ionic conductivity (10−3 to 10−4 S/cm) and good stability against Li metal. However, garnet solid electrolytes generally have poor contact with Li metal, which causes high resistance and uneven current distribution at the interface. To address this challenge, we demonstrate a strategy to engineer the garnet solid electrolyte and the Li metal interface by forming an intermediary Li-metal alloy, which changes the wettability of the garnet surface (lithiophobic to lithiophilic) and reduces the interface resistance by more than an order of magnitude: 950 ohm·cm2 for the pristine garnet/Li and 75 ohm·cm2 for the surface-engineered garnet/Li. Li7La2.75Ca0.25Zr1.75Nb0.25O12 (LLCZN) was selected as the solid-state electrolyte (SSE) in this work because of its low sintering temperature, stabilized cubic garnet phase, and high ionic conductivity. This low area-specific resistance enables a solid-state garnet SSE/Li metal configuration and promotes the development of a hybrid electrolyte system. The hybrid system uses the improved solid-state garnet SSE Li metal anode and a thin liquid electrolyte cathode interfacial layer. This work provides new ways to address the garnet SSE wetting issue against Li and get more stable cell performances based on the hybrid electrolyte system for Li-ion, Li-sulfur, and Li-oxygen batteries toward the next generation of Li metal batteries. PMID:28435874

Toward garnet electrolyte–based Li metal batteries: An ultrathin, highly effective, artificial solid-state electrolyte/metallic Li interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Kun; Gong, Yunhui; Liu, Boyang

Solid-state batteries are a promising option toward high energy and power densities due to the use of lithium (Li) metal as an anode. Among all solid electrolyte materials ranging from sulfides to oxides and oxynitrides, cubic garnet–type Li 7La 3Zr 2O 12 (LLZO) ceramic electrolytes are superior candidates because of their high ionic conductivity (10 -3 to 10 -4 S/cm) and good stability against Li metal. However, garnet solid electrolytes generally have poor contact with Li metal, which causes high resistance and uneven current distribution at the interface. To address this challenge, we demonstrate a strategy to engineer the garnetmore » solid electrolyte and the Li metal interface by forming an intermediary Li-metal alloy, which changes the wettability of the garnet surface (lithiophobic to lithiophilic) and reduces the interface resistance by more than an order of magnitude: 950 ohm·cm2 for the pristine garnet/Li and 75 ohm·cm 2 for the surface-engineered garnet/Li. Li 7La 2.75Ca 0.25Zr 1.75Nb 0.25O 12 (LLCZN) was selected as the solid-state electrolyte (SSE) in this work because of its low sintering temperature, stabilized cubic garnet phase, and high ionic conductivity. This low area-specific resistance enables a solid-state garnet SSE/Li metal configuration and promotes the development of a hybrid electrolyte system. The hybrid system uses the improved solid-state garnet SSE Li metal anode and a thin liquid electrolyte cathode interfacial layer. This work provides new ways to address the garnet SSE wetting issue against Li and get more stable cell performances based on the hybrid electrolyte system for Li-ion, Li-sulfur, and Li-oxygen batteries toward the next generation of Li metal batteries.« less

Toward garnet electrolyte–based Li metal batteries: An ultrathin, highly effective, artificial solid-state electrolyte/metallic Li interface

DOE PAGES

Fu, Kun; Gong, Yunhui; Liu, Boyang; ...

2017-04-07

Solid-state batteries are a promising option toward high energy and power densities due to the use of lithium (Li) metal as an anode. Among all solid electrolyte materials ranging from sulfides to oxides and oxynitrides, cubic garnet–type Li 7La 3Zr 2O 12 (LLZO) ceramic electrolytes are superior candidates because of their high ionic conductivity (10 -3 to 10 -4 S/cm) and good stability against Li metal. However, garnet solid electrolytes generally have poor contact with Li metal, which causes high resistance and uneven current distribution at the interface. To address this challenge, we demonstrate a strategy to engineer the garnetmore » solid electrolyte and the Li metal interface by forming an intermediary Li-metal alloy, which changes the wettability of the garnet surface (lithiophobic to lithiophilic) and reduces the interface resistance by more than an order of magnitude: 950 ohm·cm2 for the pristine garnet/Li and 75 ohm·cm 2 for the surface-engineered garnet/Li. Li 7La 2.75Ca 0.25Zr 1.75Nb 0.25O 12 (LLCZN) was selected as the solid-state electrolyte (SSE) in this work because of its low sintering temperature, stabilized cubic garnet phase, and high ionic conductivity. This low area-specific resistance enables a solid-state garnet SSE/Li metal configuration and promotes the development of a hybrid electrolyte system. The hybrid system uses the improved solid-state garnet SSE Li metal anode and a thin liquid electrolyte cathode interfacial layer. This work provides new ways to address the garnet SSE wetting issue against Li and get more stable cell performances based on the hybrid electrolyte system for Li-ion, Li-sulfur, and Li-oxygen batteries toward the next generation of Li metal batteries.« less

A solid state actuator based on polypyrrole (PPy) and a solid electrolyte NBR working in air

NASA Astrophysics Data System (ADS)

Cho, Misuk; Nam, Jaedo; Choi, Hyouk Ryeol; Koo, Jachoon; Lee, Youngkwan

2005-05-01

The solid polymer electrolyte based conducting polymer actuator was presented. In the preparation of acutuator module, an ionic liquid impregnated a synthetic rubber (NBR) and PPy were used as a solid polymer electrolyte and conducting polymer, respectively. An ionic liquid, 1-butyl-3-methylimidazolium bis (trifluoromethyl sulfonyl)imide (BMITFSI) is gradually dispersed into the NBR film and the conducting polymer, PPy was synthesized on the surface of NBR. The ionic conductivity of new type solid polymer electrolyte as a function of the immersion time was investigated. The cyclic voltammetry responsed and the redox switching dynamics of PEDOT in NBR matrix were studied. The displacement of the actuator was measured by laser beam.

Taichi-inspired rigid-flexible coupling cellulose-supported solid polymer electrolyte for high-performance lithium batteries

PubMed Central

Zhang, Jianjun; Yue, Liping; Hu, Pu; Liu, Zhihong; Qin, Bingsheng; Zhang, Bo; Wang, Qingfu; Ding, Guoliang; Zhang, Chuanjian; Zhou, Xinhong; Yao, Jianhua; Cui, Guanglei; Chen, Liquan

2014-01-01

Inspired by Taichi, we proposed rigid-flexible coupling concept and herein developed a highly promising solid polymer electrolyte comprised of poly (ethylene oxide), poly (cyano acrylate), lithium bis(oxalate)borate and robust cellulose nonwoven. Our investigation revealed that this new class solid polymer electrolyte possessed comprehensive properties in high mechanical integrity strength, sufficient ionic conductivity (3 × 10−4 S cm−1) at 60°C and improved dimensional thermostability (up to 160°C). In addition, the lithium iron phosphate (LiFePO4)/lithium (Li) cell using such solid polymer electrolyte displayed superior rate capacity (up to 6 C) and stable cycle performance at 80°C. Furthermore, the LiFePO4/Li battery could also operate very well even at an elevated temperature of 160°C, thus improving enhanced safety performance of lithium batteries. The use of this solid polymer electrolyte mitigates the safety risk and widens the operation temperature range of lithium batteries. Thus, this fascinating study demonstrates a proof of concept of the use of rigid-flexible coupling solid polymer electrolyte toward practical lithium battery applications with improved reliability and safety. PMID:25183416

Oxygen concentration sensor for an internal combustion engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakajima, T.; Okada, Y.; Mieno, T.

1988-09-29

This patent describes an oxygen concentration sensor, comprising: an oxygen ion conductive solid electrolyte member forming a gas diffusion restricted region into which a measuring gas is introduced; a pair of electrodes sandwiching the solid electrolyte member; pump current supply means applying a pump voltage to the pair of electrodes through a current detection element to generate a pump current; and a heater element connected to the solid electrolyte member for heating the solid electrolyte member for heating the solid electrolyte member when a heater current is supplied from a heater current source; wherein the oxygen concentration sensor detects anmore » oxygen concentration in the measuring gas in terms of a current value of the pump current supplied through the current detection element and controls oxygen concentration in the gas diffusion restricted region by conducting oxygen ions through the solid electrolyte member in accordance to the flow of the pump current; and wherein the current detection element is connected to the electrode of the pair of electrodes facing the gas diffusion restricted region for insuring that the current value is representative of the pump current and possible leakage current from the heater current.« less

A simple model for constant storage modulus of poly (lactic acid)/poly (ethylene oxide)/carbon nanotubes nanocomposites at low frequencies assuming the properties of interphase regions and networks.

PubMed

Zare, Yasser; Rhim, Sungsoo; Garmabi, Hamid; Rhee, Kyong Yop

2018-04-01

The networks of nanoparticles in nanocomposites cause solid-like behavior demonstrating a constant storage modulus at low frequencies. This study examines the storage modulus of poly (lactic acid)/poly (ethylene oxide)/carbon nanotubes (CNT) nanocomposites. The experimental data of the storage modulus in the plateau regions are obtained by a frequency sweep test. In addition, a simple model is developed to predict the constant storage modulus assuming the properties of the interphase regions and the CNT networks. The model calculations are compared with the experimental results, and the parametric analyses are applied to validate the predictability of the developed model. The calculations properly agree with the experimental data at all polymer and CNT concentrations. Moreover, all parameters acceptably modulate the constant storage modulus. The percentage of the networked CNT, the modulus of networks, and the thickness and modulus of the interphase regions directly govern the storage modulus of nanocomposites. The outputs reveal the important roles of the interphase properties in the storage modulus. Copyright © 2018 Elsevier Ltd. All rights reserved.

Creating Lithium-Ion Electrolytes with Biomimetic Ionic Channels in Metal-Organic Frameworks.

PubMed

Shen, Li; Wu, Hao Bin; Liu, Fang; Brosmer, Jonathan L; Shen, Gurong; Wang, Xiaofeng; Zink, Jeffrey I; Xiao, Qiangfeng; Cai, Mei; Wang, Ge; Lu, Yunfeng; Dunn, Bruce

2018-06-01

Solid-state electrolytes are the key to the development of lithium-based batteries with dramatically improved energy density and safety. Inspired by ionic channels in biological systems, a novel class of pseudo solid-state electrolytes with biomimetic ionic channels is reported herein. This is achieved by complexing the anions of an electrolyte to the open metal sites of metal-organic frameworks (MOFs), which transforms the MOF scaffolds into ionic-channel analogs with lithium-ion conduction and low activation energy. This work suggests the emergence of a new class of pseudo solid-state lithium-ion conducting electrolytes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solid-Liquid Lithium Electrolyte Nanocomposites Derived from Porous Molecular Cages.

PubMed

Petronico, Aaron; Moneypenny, Timothy P; Nicolau, Bruno G; Moore, Jeffrey S; Nuzzo, Ralph G; Gewirth, Andrew A

2018-06-20

We demonstrate that solid-liquid nanocomposites derived from porous organic cages are effective lithium ion electrolytes at room temperature. A solid-liquid electrolyte nanocomposite (SLEN) fabricated from a LiTFSI/DME electrolyte system and a porous organic cage exhibits ionic conductivity on the order of 1 × 10 -3 S cm -1 . With an experimentally measured activation barrier of 0.16 eV, this composite is characterized as a superionic conductor. Furthermore, the SLEN displays excellent oxidative stability up to 4.7 V vs Li/Li + . This simple three-component system enables the rational design of electrolytes from tunable discrete molecular architectures.

Influence of crystallography and bonding on the structure and migration of irrational interphase boundaries

NASA Astrophysics Data System (ADS)

Aaronson, H. I.

2006-03-01

Interphase boundary structure developed during precipitation from solid solution and during massive transformations is considered in diverse alloy systems in the presence of differences in stacking sequence across interphase boundaries. Linear misfit compensating defects, including misfit dislocations, structural disconnections, and misfit disconnections, are present over a wide range of crystallographie when both phases have metallic bonding. Misfit dislocations have also been observed when both phases have covalent bonding ( e.g., US: β US2 by Sole and van der Walt). These defects are also found when one phase is ionic and the other is metallic (Nb∶Al2O3 by Rühle et al.), albeit when the latter is formed by vapor deposition. However, when bonding is metallic in one phase but significantly covalent in the other, the structure of the interphase boundary appears to depend upon the strength of the covalent bonding relative to that in the metallically bonded phase. When this difference is large, growth can take place as if it were occurring at a free surface, resulting in orientation relationships that are irrational and conjugate habit planes that are ill matched ( e.g., ZrN: α Zr-N by Li et al. and Xe(solid):Al-Xe by Kishida and Yamaguchi). At lower levels of bonding directionality and strength, crystallography is again irrational, but now edge-to-edge-based low-energy structures can replace linear misfit compensating defects (γm:TiAl:αTi-Al by Reynolds et al.). In the perhaps still smaller difference case of Widmanstätten cementite precipitated from austenite, one orientation relationship yields plates with linear misfit compensating defects at their broad faces whereas another (presumably nucleated at different types of site) produces laths with poorly defined shapes and interfacial structures. Hence, Hume-Rothery-type bonding considerations can markedly affect interphase boundary structure and thus the mechanisms, kinetics, and morphology of growth.

Investigation of lithium ion battery electrolytes containing flame retardants in combination with the film forming electrolyte additives vinylene carbonate, vinyl ethylene carbonate and fluoroethylene carbonate

NASA Astrophysics Data System (ADS)

Dagger, Tim; Grützke, Martin; Reichert, Matthias; Haetge, Jan; Nowak, Sascha; Winter, Martin; Schappacher, Falko M.

2017-12-01

In order to address the trade-off between the safety lithium ion battery (LIB) electrolytes and their electrochemical performance, synergetic effects of flame retardant additives (FRs) in combination with film forming additives (FFAs) are investigated. Triphenyl phosphate (TPP) and a silicon-containing additive (WA) are applied as FRs to improve the onset temperature of the thermal runaway of a LIB standard electrolyte (LP57: 1 M LiPF6 in EC:EMC 3:7) about 15 K and 28 K, respectively. The application of the FRs in MCMB graphite/lithium metal and NMC111/lithium metal three-electrode cells induces insufficiencies in terms of charge/discharge cycling stability and rate capability. It is investigated if the addition of FFAs can degrade the insufficiencies that are induced by the FRs. Vinylene carbonate, vinyl ethylene carbonate and fluoroethylene carbonate are added to a mixture of LP57 with 10% FR to enhance the cycling performance via improved interphase formation. Results reveal, that the rate capability of cells containing TPP or WA is especially improved by addition of 2% or 5% FEC, respectively. Postmortem analyses of the electrodes by SEM and of the electrolyte by GC-MS are performed. Direct correlations between the cycling behavior during the C-rate study and the electrolyte decomposition products are drawn.

Rapid Thermal Annealing of Cathode-Garnet Interface toward High-Temperature Solid State Batteries.

PubMed

Liu, Boyang; Fu, Kun; Gong, Yunhui; Yang, Chunpeng; Yao, Yonggang; Wang, Yanbin; Wang, Chengwei; Kuang, Yudi; Pastel, Glenn; Xie, Hua; Wachsman, Eric D; Hu, Liangbing

2017-08-09

High-temperature batteries require the battery components to be thermally stable and function properly at high temperatures. Conventional batteries have high-temperature safety issues such as thermal runaway, which are mainly attributed to the properties of liquid organic electrolytes such as low boiling points and high flammability. In this work, we demonstrate a truly all-solid-state high-temperature battery using a thermally stable garnet solid-state electrolyte, a lithium metal anode, and a V 2 O 5 cathode, which can operate well at 100 °C. To address the high interfacial resistance between the solid electrolyte and cathode, a rapid thermal annealing method was developed to melt the cathode and form a continuous contact. The resulting interfacial resistance of the solid electrolyte and V 2 O 5 cathode was significantly decreased from 2.5 × 10 4 to 71 Ω·cm 2 at room temperature and from 170 to 31 Ω·cm 2 at 100 °C. Additionally, the diffusion resistance in the V 2 O 5 cathode significantly decreased as well. The demonstrated high-temperature solid-state full cell has an interfacial resistance of 45 Ω·cm 2 and 97% Coulombic efficiency cycling at 100 °C. This work provides a strategy to develop high-temperature all-solid-state batteries using garnet solid electrolytes and successfully addresses the high contact resistance between the V 2 O 5 cathode and garnet solid electrolyte without compromising battery safety or performance.

The design of a Li-ion full cell battery using a nano silicon and nano multi-layer graphene composite anode

NASA Astrophysics Data System (ADS)

Eom, KwangSup; Joshi, Tapesh; Bordes, Arnaud; Do, Inhwan; Fuller, Thomas F.

2014-03-01

In this study, a Si-graphene composite, which is composed of nano Si particles and nano-sized multi-layer graphene particles, and micro-sized multi-layer graphene plate conductor, was used as the anode for Li-ion battery. The Si-graphene electrode showed the high capacity and stable cyclability at charge/discharge rate of C/2 in half cell tests. Nickel cobalt aluminum material (NCA) was used as a cathode in the full cell to evaluate the practicality of the new Si-graphene material. Although the Si-graphene anode has more capacity than the NCA cathode in this designed full cell, the Si-graphene anode had a greater effect on the full-cell performance due to its large initial irreversible capacity loss and continuous SEI formation during cycling. When fluoro-ethylene carbonate was added to the electrolyte, the cyclability of the full cell was much improved due to less SEI formation, which was confirmed by the decreases in the 1st irreversible capacity loss, overpotential for the 1st lithiation, and the resistance of the SEI.

Plutonium recovery from spent reactor fuel by uranium displacement

DOEpatents

Ackerman, John P.

1992-01-01

A process for separating uranium values and transuranic values from fission products containing rare earth values when the values are contained together in a molten chloride salt electrolyte. A molten chloride salt electrolyte with a first ratio of plutonium chloride to uranium chloride is contacted with both a solid cathode and an anode having values of uranium and fission products including plutonium. A voltage is applied across the anode and cathode electrolytically to transfer uranium and plutonium from the anode to the electrolyte while uranium values in the electrolyte electrolytically deposit as uranium metal on the solid cathode in an amount equal to the uranium and plutonium transferred from the anode causing the electrolyte to have a second ratio of plutonium chloride to uranium chloride. Then the solid cathode with the uranium metal deposited thereon is removed and molten cadmium having uranium dissolved therein is brought into contact with the electrolyte resulting in chemical transfer of plutonium values from the electrolyte to the molten cadmium and transfer of uranium values from the molten cadmium to the electrolyte until the first ratio of plutonium chloride to uranium chloride is reestablished.

Self‐Regulative Nanogelator Solid Electrolyte: A New Option to Improve the Safety of Lithium Battery

PubMed Central

Wu, Feng; Chen, Nan; Zhu, Qizhen; Tan, Guoqiang; Li, Li

2016-01-01

The lack of suitable nonflammable electrolytes has delayed battery application in electric vehicles. A new approach to improve the safety performance for lithium battery is proposed here. This technology is based on a nanogelator‐based solid electrolyte made of porous oxides and an ionic liquid. The electrolyte is fabricated using an in situ method and the porous oxides serve as a nonflammable “nanogelator” that spontaneously immobilizes the ionic liquid. The electrolyte exhibits a high liquid‐like apparent ionic conductivity of 2.93 × 10−3 S cm−1 at room temperature. The results show that the nanogelator, which possess self‐regulating ability, is able to immobilize imidazolium‐, pyrrolidinium‐, or piperidinium‐based ionic liquids, simply by adjusting the ion transport channels. Our prototype batteries made of Ti‐nanogeltor solid electrolyte outperform conventional lithium batteries made using ionic liquid and commercial organic liquid electrolytes. PMID:27774385

Self-Regulative Nanogelator Solid Electrolyte: A New Option to Improve the Safety of Lithium Battery.

PubMed

Wu, Feng; Chen, Nan; Chen, Renjie; Zhu, Qizhen; Tan, Guoqiang; Li, Li

2016-01-01

The lack of suitable nonflammable electrolytes has delayed battery application in electric vehicles. A new approach to improve the safety performance for lithium battery is proposed here. This technology is based on a nanogelator-based solid electrolyte made of porous oxides and an ionic liquid. The electrolyte is fabricated using an in situ method and the porous oxides serve as a nonflammable "nanogelator" that spontaneously immobilizes the ionic liquid. The electrolyte exhibits a high liquid-like apparent ionic conductivity of 2.93 × 10 -3 S cm -1 at room temperature. The results show that the nanogelator, which possess self-regulating ability, is able to immobilize imidazolium-, pyrrolidinium-, or piperidinium-based ionic liquids, simply by adjusting the ion transport channels. Our prototype batteries made of Ti-nanogeltor solid electrolyte outperform conventional lithium batteries made using ionic liquid and commercial organic liquid electrolytes.

An air-stable Na 3SbS 4 superionic conductor prepared by a rapid and economic synthetic procedure

DOE PAGES

Wang, Hui; Chen, Yan; Hood, Zachary D.; ...

2016-01-01

All-solid-state sodium batteries, using abundant sodium resources and solid electrolyte, hold much promise for safe, low cost, large-scale energy storage. To realize the practical applications of all solid Na-ion batteries at ambient temperature, the solid electrolytes are required to have high ionic conductivity, chemical stability, and ideally, easy preparation. Ceramic electrolytes show higher ionic conductivity than polymers, but they often require extremely stringent synthesis conditions, either high sintering temperature above 1000 C or long-time, low-energy ball milling. Herein, we report a new synthesis route for Na 3SbS 4, a novel Na superionic conductor that needs much lower processing temperature belowmore » 200 C and easy operation. This new solid electrolyte exhibits a remarkable ionic conductivity of 1.05 mS cm -1 at 25 °C and is chemically stable under ambient atmosphere. In conclusion, this synthesis process provides unique insight into the current state-of-the-art solid electrolyte preparation and opens new possibilities for the design of similar materials.« less

Study of ceria-carbonate nanocomposite electrolytes for low-temperature solid oxide fuel cells.

PubMed

Fan, L; Wang, C; Di, J; Chen, M; Zheng, J; Zhu, B

2012-06-01

Composite and nanocomposite samarium doped ceria-carbonates powders were prepared by solid-state reaction, citric acid-nitrate combustion and modified nanocomposite approaches and used as electrolytes for low temperature solid oxide fuel cells. X-ray Diffraction, Scanning Electron Microscope, low-temperature Nitrogen Adsorption/desorption Experiments, Electrochemical Impedance Spectroscopy and fuel cell performance test were employed in characterization of these materials. All powders are nano-size particles with slight aggregation and carbonates are amorphous in composites. Nanocomposite electrolyte exhibits much lower impedance resistance and higher ionic conductivity than those of the other electrolytes at lower temperature. Fuel cell using the electrolyte prepared by modified nanocomposite approach exhibits the best performance in the whole operation temperature range and achieves a maximum power density of 839 mW cm(-2) at 600 degrees C with H2 as fuel. The excellent physical and electrochemical performances of nanocomposite electrolyte make it a promising candidate for low-temperature solid oxide fuel cells.

Electrolytes for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Fergus, Jeffrey W.

The high operating temperature of solid oxide fuel cells (SOFCs), as compared to polymer electrolyte membrane fuel cells (PEMFCs), improves tolerance to impurities in the fuel, but also creates challenges in the development of suitable materials for the various fuel cell components. In response to these challenges, intermediate temperature solid oxide fuel cells (IT-SOFCs) are being developed to reduce high-temperature material requirements, which will extend useful lifetime, improve durability and reduce cost, while maintaining good fuel flexibility. A major challenge in reducing the operating temperature of SOFCs is the development of solid electrolyte materials with sufficient conductivity to maintain acceptably low ohmic losses during operation. In this paper, solid electrolytes being developed for solid oxide fuel cells, including zirconia-, ceria- and lanthanum gallate-based materials, are reviewed and compared. The focus is on the conductivity, but other issues, such as compatibility with electrode materials, are also discussed.

Fabrication, testing and simulation of all solid state three dimensional Li-ion batteries

DOE PAGES

Talin, Albert Alec; Ruzmetov, Dmitry; Kolmakov, Andrei; ...

2016-11-10

Realization of safe, long cycle life and simple to package solid-state rechargeable batteries with high energy and power density has been a long-standing goal of the energy storage community. [1,2] Much of the research activity has been focused on developing new solid electrolytes with high Li ionic conductivity. In addition, LiPON, the only solid electrolyte currently used in commercial thin film solid state Li-ion batteris (SSLIBs), has a conductivity of ~10 -6 S/cm, compared to ~0.01 S/cm typically observed for liquid organic electrolytes [3].

Superionic glass-ceramic electrolytes for room-temperature rechargeable sodium batteries.

PubMed

Hayashi, Akitoshi; Noi, Kousuke; Sakuda, Atsushi; Tatsumisago, Masahiro

2012-05-22

Innovative rechargeable batteries that can effectively store renewable energy, such as solar and wind power, urgently need to be developed to reduce greenhouse gas emissions. All-solid-state batteries with inorganic solid electrolytes and electrodes are promising power sources for a wide range of applications because of their safety, long-cycle lives and versatile geometries. Rechargeable sodium batteries are more suitable than lithium-ion batteries, because they use abundant and ubiquitous sodium sources. Solid electrolytes are critical for realizing all-solid-state sodium batteries. Here we show that stabilization of a high-temperature phase by crystallization from the glassy state dramatically enhances the Na(+) ion conductivity. An ambient temperature conductivity of over 10(-4) S cm(-1) was obtained in a glass-ceramic electrolyte, in which a cubic Na(3)PS(4) crystal with superionic conductivity was first realized. All-solid-state sodium batteries, with a powder-compressed Na(3)PS(4) electrolyte, functioned as a rechargeable battery at room temperature.

High Performance Solid Polymer Electrolytes for Rechargeable Batteries: A Self‐Catalyzed Strategy toward Facile Synthesis

PubMed Central

Cui, Yanyan; Liang, Xinmiao; Chai, Jingchao; Cui, Zili; Wang, Qinglei; He, Weisheng; Liu, Xiaochen; Feng, Jiwen

2017-01-01

Abstract It is urgent to seek high performance solid polymer electrolytes (SPEs) via a facile chemistry and simple process. The lithium salts are composed of complex anions that are stabilized by a Lewis acid agent. This Lewis acid can initiate the ring opening polymerization. Herein, a self‐catalyzed strategy toward facile synthesis of crosslinked poly(ethylene glycol) diglycidyl ether‐based solid polymer electrolyte (C‐PEGDE) is presented. It is manifested that the poly(ethylene glycol) diglycidyl ether‐based solid polymer electrolyte possesses a superior electrochemical stability window up to 4.5 V versus Li/Li+ and considerable ionic conductivity of 8.9 × 10−5 S cm−1 at ambient temperature. Moreover, the LiFePO4/C‐PEGDE/Li batteries deliver stable charge/discharge profiles and considerable rate capability. It is demonstrated that this self‐catalyzed strategy can be a very effective approach for high performance solid polymer electrolytes. PMID:29201612

Crosslinked Polymer Ionic Liquid/Ionic Liquid Blends Prepared by Photopolymerization as Solid-State Electrolytes in Supercapacitors.

PubMed

Wang, Po-Hsin; Wang, Tzong-Liu; Lin, Wen-Churng; Lin, Hung-Yin; Lee, Mei-Hwa; Yang, Chien-Hsin

2018-04-07

A photopolymerization method is used to prepare a mixture of polymer ionic liquid (PIL) and ionic liquid (IL). This mixture is used as a solid-state electrolyte in carbon nanoparticle (CNP)-based symmetric supercapacitors. The solid electrolyte is a binary mixture of a PIL and its corresponding IL. The PIL matrix is a cross-linked polyelectrolyte with an imidazole salt cation coupled with two anions of Br - in PIL-M-(Br) and TFSI - in PIL-M-(TFSI), respectively. The corresponding ionic liquids have imidazolium salt cation coupled with two anions of Br - and TFSI - , respectively. This study investigates the electrochemical characteristics of PILs and their corresponding IL mixtures used as a solid electrolyte in supercapacitors. Results show that a specific capacitance, maximum power density and energy density of 87 and 58 F·g - ¹, 40 and 48 kW·kg - ¹, and 107 and 59.9 Wh·kg - ¹ were achieved in supercapacitors based on (PIL-M-(Br)) and (PIL-M-(TFSI)) solid electrolytes, respectively.

Reciprocated suppression of polymer crystallization toward improved solid polymer electrolytes: Higher ion conductivity and tunable mechanical properties

DOE PAGES

Bi, Sheng; Sun, Che-Nan; Zawodzinski, Thomas A.; ...

2015-08-06

Solid polymer electrolytes based on lithium bis(trifluoromethanesulfonyl) imide and polymer matrix were extensively studied in the past due to their excellent potential in a broad range of energy related applications. Poly(vinylidene fluoride) (PVDF) and polyethylene oxide (PEO) are among the most examined polymer candidates as solid polymer electrolyte matrix. In this paper, we study the effect of reciprocated suppression of polymer crystallization in PVDF/PEO binary matrix on ion transport and mechanical properties of the resultant solid polymer electrolytes. With electron and X-ray diffractions as well as energy filtered transmission electron microscopy, we identify and examine the appropriate blending composition thatmore » is responsible for the diminishment of both PVDF and PEO crystallites. Laslty, a three-fold conductivity enhancement is achieved along with a highly tunable elastic modulus ranging from 20 to 200 MPa, which is expected to contribute toward future designs of solid polymer electrolytes with high room-temperature ion conductivities and mechanical flexibility.« less

Method for making an electrochemical cell

DOEpatents

Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.; Pal, Uday B.

1996-01-01

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is provided.

Electrolyte materials containing highly dissociated metal ion salts

DOEpatents

Lee, H.S.; Geng, L.; Skotheim, T.A.

1996-07-23

The present invention relates to metal ion salts which can be used in electrolytes for producing electrochemical devices, including both primary and secondary batteries, photoelectrochemical cells and electrochromic displays. The salts have a low energy of dissociation and may be dissolved in a suitable polymer to produce a polymer solid electrolyte or in a polar aprotic liquid solvent to produce a liquid electrolyte. The anion of the salts may be covalently attached to polymer backbones to produce polymer solid electrolytes with exclusive cation conductivity. 2 figs.

Current status of solid-state lithium batteries employing solid redox polymerization cathodes

NASA Astrophysics Data System (ADS)

Visco, S. J.; Doeff, M. M.; Dejonghe, L. C.

1991-03-01

The rapidly growing demand for secondary batteries having high specific energy and power has naturally led to increased efforts in lithium battery technology. Still, the increased safety risks associated with high energy density systems has tempered the enthusiasm of proponents of such systems for use in the consumer marketplace. The inherent advantages of all-solid-state batteries in regards to safety and reliability are strong factors in advocating their introduction to the marketplace. However, the low ionic conductivity of solid electrolytes relative to nonaqueous liquid electrolytes implies low power densities for solid state systems operating at ambient temperatures. Recent advances in polymer electrolytes have led to the introduction of solid electrolytes having conductivities in the range of 10(exp -4)/ohm cm at room temperature; this is still two orders of magnitude lower than liquid electrolytes. Although these improved ambient conductivities put solid state batteries in the realm of practical devices, it is clear that solid state batteries using such polymeric separators will be thin film devices. Fortunately, thin film fabrication techniques are well established in the plastics and paper industry, and present the possibility of continuous web-form manufacturing. This style of battery manufacture should make solid polymer batteries very cost-competitive with conventional secondary cells. In addition, the greater geometric flexibility of thin film solid state cells should provide benefits in terms of the end-use form factor in device design. This work discusses the status of solid redox polymerization cathodes.

Nano-carbon coating layer prepared by the thermal evaporation of fullerene C60 for lithium metal anodes in rechargeable lithium batteries.

PubMed

Arie, Arenst Andreas; Lee, Joong Kee

2011-07-01

A nano carbon coating layer was prepared by the thermal evaporation of fullerene C60 on the surface of lithium metal anodes for rechargeable lithium batteries. The morphology and structure of the carbon layer was firstly investigated by Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of the nano-carbon coating layer on the electrochemical performance of the lithium electrode were then examined by charge-discharge tests and impedance spectroscopy. Raman spectra of carbon coating layer showed two main peaks (D and G peaks), indicating the amorphous structure of the film. A honey comb-like structure of carbon film was observed by TEM photographs, providing a transport path for the transport of lithium ions at the electrode/electrolyte interface. The carbon coated lithium electrodes exhibited a higher initial coulombic efficiency (91%) and higher specific capacity retention (88%) after the 30th cycle at 0.2 C-rate between 3.4 and 4.5 V. Impedance measurements showed that the charge transfer resistance was significantly reduced after cycle tests for the carbon coated electrodes, revealing that the more stable solid electrolyte (SEI) layer was established on their surface. Based on the experimental results, it suggested that the presence of the nano-carbon coating layer might suppress the dendritic growth on the surface of lithium metal electrodes, as confirmed by the observation of SEM images after cycle tests.