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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

A Flexible Solid Electrolyte Interphase Layer for Long-Life Lithium Metal Anodes.

PubMed

Li, Nian-Wu; Shi, Yang; Yin, Ya-Xia; Zeng, Xian-Xiang; Li, Jin-Yi; Li, Cong-Ju; Wan, Li-Jun; Wen, Rui; Guo, Yu-Guo

2018-02-05

Lithium (Li) metal is a promising anode material for high-energy density batteries. However, the unstable and static solid electrolyte interphase (SEI) can be destroyed by the dynamic Li plating/stripping behavior on the Li anode surface, leading to side reactions and Li dendrites growth. Herein, we design a smart Li polyacrylic acid (LiPAA) SEI layer high elasticity to address the dynamic Li plating/stripping processes by self-adapting interface regulation, which is demonstrated by in situ AFM. With the high binding ability and excellent stability of the LiPAA polymer, the smart SEI can significantly reduce the side reactions and improve battery safety markedly. Stable cycling of 700 h is achieved in the LiPAA-Li/LiPAA-Li symmetrical cell. The innovative strategy of self-adapting SEI design is broadly applicable, providing opportunities for use in Li metal anodes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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.

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

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.

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.

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.

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

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.

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

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.

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

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.

Tuning the Solid Electrolyte Interphase for Selective Li- and Na-Ion Storage in Hard Carbon

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

Soto, Fernando A.; Yan, Pengfei; Engelhard, Mark H.

Solid-electrolyte interphase (SEI) films with controllable properties are highly desirable for improving battery performance. In this paper, a combined experimental and theoretical approach is used to study SEI films formed on hard carbon in Li- and Na-ion batteries. It is shown that a stable SEI layer can be designed by precycling an electrode in a desired Li- or Na-based electrolyte, and that ionic transport can be kinetically controlled. Selective Li- and Na-based SEI membranes are produced using Li- or Na-based electrolytes, respectively. The Na-based SEI allows easy transport of Li ions, while the Li-based SEI shuts off Na-ion transport. Na-ionmore » storage can be manipulated by tuning the SEI layer with film-forming electrolyte additives, or by preforming an SEI layer on the electrode surface. The Na specific capacity can be controlled to < 25 mAh g(-1); approximate to 1/10 of the normal capacity (250 mAh g(-1)). Unusual selective/ preferential transport of Li ions is demonstrated by preforming an SEI layer on the electrode surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion-selective conductors using electrochemical approaches.« less

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.

Tuning the Solid Electrolyte Interphase for Selective Li- and Na-Ion Storage in Hard Carbon

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

Soto, Fernando A.; Yan, Pengfei; Engelhard, Mark H.

Solid-electrolyte interphase (SEI) with controllable properties are highly desirable to improve battery performance. In this paper, we use a combined experimental and simulation approach to study the SEI formation on hard carbon in Li and Na-ion batteries. We show that with proper additives, stable SEI can be formed on hard carbon by pre-cycling the electrode materials in Li or Na-ion electrolyte. Detailed mechanistic studies suggest that the ion transport in the SEI layer is kinetically controlled and can be tuned by the applied voltage. Selective Na and Li-ion SEI membranes are produced using the Na or Li-ion based electrolytes respectively.more » The large Na ion SEI allows easy transport of Li ions, while the small Li ion SEI shuts off the Na-ion transport. Na-ion storage can be manipulated by tuning the SEI with film-forming electrolyte additives or preforming a SEI on the electrodes’ surface. The Na specific capacity can be controlled to <25 mAh/g, ~1/10 of the normal capacity (250 mAh/g). Unusual selective/preferential transport of Li-ion is demonstrated by preforming a SEI on the electrode’s surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion selective conductors using electrochemical approaches in the future.« less

Modulation of solid electrolyte interphase of lithium-ion batteries by LiDFOB and LiBOB electrolyte additives

NASA Astrophysics Data System (ADS)

Huang, Shiqiang; Wang, Shuwei; Hu, Guohong; Cheong, Ling-Zhi; Shen, Cai

2018-05-01

Solid-electrolyte interphase (SEI) layer is an organic-inorganic composite layer that allows Li+ transport across but blocks electron flow across and prevents solvent diffusing to electrode surface. Morphology, thickness, mechanical and chemical properties of SEI are important for safety and cycling performance of lithium-ion batteries. Herein, we employ a combination of in-situ AFM and XPS to investigate the effects of two electrolyte additives namely lithium difluoro(oxalate)borate (LiDFOB) and lithium bis(oxalato)borate (LiBOB) on SEI layer. LiDFOB is found to result in a thin but hard SEI layer containing more inorganic species (LiF and LiCO3); meanwhile LiBOB promotes formation of a thick but soft SEI layer containing more organic species such as ROCO2Li. Findings from present study will help development of electrolyte additives that promote formation of good SEI layer.

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.

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

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.

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.

Artificial solid electrolyte interphase to address the electrochemical degradation of silicon electrodes.

PubMed

Li, Juchuan; Dudney, Nancy J; Nanda, Jagjit; Liang, Chengdu

2014-07-09

Electrochemical degradation on silicon (Si) anodes prevents them from being successfully used in lithium (Li)-ion battery full cells. Unlike the case of graphite anodes, the natural solid electrolyte interphase (SEI) films generated from carbonate electrolytes do not self-passivate on Si, causing continuous electrolyte decomposition and loss of Li ions. In this work, we aim at solving the issue of electrochemical degradation by fabricating artificial SEI films using a solid electrolyte material, lithium phosphorus oxynitride (Lipon), which conducts Li ions and blocks electrons. For Si anodes coated with Lipon of 50 nm or thicker, a significant effect is observed in suppressing electrolyte decomposition, while Lipon of thinner than 40 nm has a limited effect. Ionic and electronic conductivity measurements reveal that the artificial SEI is effective when it is a pure ionic conductor, but electrolyte decomposition is only partially suppressed when the artificial SEI is a mixed electronic-ionic conductor. The critical thickness for this transition in conducting behavior is found to be 40-50 nm. This work provides guidance for designing artificial SEI films for high-capacity Li-ion battery electrodes using solid electrolyte materials.

Artificial Solid Electrolyte Interphase to Address the Electrochemical Degradation of Silicon Electrodes

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

Dudney, Nancy J; Nanda, Jagjit; Liang, Chengdu

2014-01-01

Electrochemical degradation on Si anodes prevents them from being successfully used in lithium-ion full cells. Unlike the case of graphite anodes, natural solid electrolyte interphase (SEI) films generated from carbonate electrolyte do not self-passivate on Si and causes continuous electrolyte decomposition. In this work we aim at solving the issue of electrochemical degradation by fabricating artificial SEI films using a solid electrolyte material, lithium phosphor oxynitride (Lipon), that conducts Li ions and blocks electrons. For Si anodes coated with Lipon of 50 nm or thicker, significant effect is observed in suppressing the electrolyte decomposition, while Lipon of thinner than 40more » nm has little effect. Ionic and electronic conductivity measurement reveals that the artificial SEI is effective when it is a pure ionic conductor, and the electrolyte decomposition is not suppressed when the artificial SEI is a mixed electronic-ionic conductor. The critical thickness for this transition in conducting behavior is found to be 40~50 nm. This work provides guidance for designing artificial SEI for high capacity lithium-ion battery electrodes using solid electrolyte materials.« 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

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

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

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.

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.

The state of understanding of the lithium-ion-battery graphite solid electrolyte interphase (SEI) and its relationship to formation cycling

DOE PAGES

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

2016-04-09

An in-depth review is presented on the science of lithium-ion battery (LIB) solid electrolyte interphase (SEI) formation on the graphite anode, including structure, morphology, chemical composition, electrochemistry, formation mechanism, and LIB formation cycling. During initial operation of LIBs, the SEI layer forms on the graphite surfaces, the most commonly used anode material, due to side reactions with the electrolyte solvent/salt at low electro-reduction potentials. It is accepted that the SEI layer is essential to the long-term performance of LIBs, and it also has an impact on its initial capacity loss, self-discharge characteristics, cycle life, rate capability, and safety. While themore » presence of the anode SEI layer is vital, it is difficult to control its formation and growth, as the chemical composition, morphology, and stability depend on several factors. These factors include the type of graphite, electrolyte composition, electrochemical conditions, and cell temperature. Thus, SEI layer formation and electrochemical stability over long-term operation should be a primary topic of future investigation in the development of LIB technology. We review the progression of knowledge gained about the anode SEI, from its discovery in 1979 to the current state of understanding, and covers its formation process, differences in the chemical and structural makeup when cell materials and components are varied, methods of characterization, and associated reactions with the liquid electrolyte phase. It also discusses the relationship of the SEI layer to the LIB formation step, which involves both electrolyte wetting and subsequent slow charge-discharge cycles to grow the SEI.« less

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

Electronic Structure at Electrode/Electrolyte Interfaces in Magnesium based Batteries

NASA Astrophysics Data System (ADS)

Balachandran, Janakiraman; Siegel, Donald

2015-03-01

Magnesium is a promising multivalent element for use in next generation electrochemical energy storage systems. However, a wide range of challenges such as low coulombic efficiency, low/varying capacity and cyclability need to be resolved in order to realize Mg based batteries. Many of these issues can be related to interfacial phenomena between the Mg anode and common electrolytes. Ab-initio based computational models of these interfaces can provide insights on the interfacial interactions that can be difficult to probe experimentally. In this work we present ab-initio computations of common electrolyte solvents (THF, DME) in contact with two model electrode surfaces namely -- (i) an ``SEI-free'' electrode based on Mg metal and, (ii) a ``passivated'' electrode consisting of MgO. We perform GW calculations to predict the reorganization of the molecular orbitals (HOMO/LUMO) upon contact with the these surfaces and their alignment with respect to the Fermi energy of the electrodes. These computations are in turn compared with more efficient GGA (PBE) & Hybrid (HSE) functional calculations. The results obtained from these computations enable us to qualitatively describe the stability of these solvent molecules at electrode-electrolyte interfaces

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.

High-temperature solid electrolyte interphases (SEI) in graphite electrodes

NASA Astrophysics Data System (ADS)

Rodrigues, Marco-Tulio F.; Sayed, Farheen N.; Gullapalli, Hemtej; Ajayan, Pulickel M.

2018-03-01

Thermal fragility of the solid electrolyte interphase (SEI) is a major source of performance decay in graphite anodes, and efforts to overcome the issues offered by extreme environments to Li-ion batteries have had limited success. Here, we demonstrate that the SEI can be extensively reinforced by carrying the formation cycles at elevated temperatures. Under these conditions, decomposition of the ionic liquid present in the electrolyte favored the formation of a thicker and more protective layer. Cells in which the solid electrolyte interphase was cast at 90 °C were significantly less prone to self-discharge when exposed to high temperature, with no obvious damages to the formed SEI. This additional resilience was accomplished at the expense of rate capability, as charge transfer became growingly inefficient in these systems. At slower rates, however, cells that underwent SEI formation at 90 °C presented superior performances, as a result of improved Li+ transport through the SEI, and optimal wetting of graphite by the electrolyte. This work analyzes different graphite hosts and ionic liquids, showing that this effect is more pervasive than anticipated, and offering the unique perspective that, for certain systems, temperature can actually be an asset for passivation.

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.

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.

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.

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.

Operando Measurement of Solid Electrolyte Interphase Formation at Working Electrode of Li-Ion Battery by Time-Slicing Neutron Reflectometry.

PubMed

Kawaura, Hiroyuki; Harada, Masashi; Kondo, Yasuhito; Kondo, Hiroki; Suganuma, Yoshitake; Takahashi, Naoko; Sugiyama, Jun; Seno, Yoshiki; Yamada, Norifumi L

2016-04-20

We report the first operando measurement of solid electrolyte interphase (SEI) formation at an electrode using in situ neutron reflectometry. The results revealed the growth of the SEI and intercalation of ions during the charge reaction. Furthermore, we propose a way of evaluating the charge used for the SEI formation.

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

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

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

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

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

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

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

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

Parasitic reactions of electrolyte and polysulfide with the Li-anode in lithium sulfur (Li-S) batteries lead to the for-mation 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 oth-er electrolyte components are still unclear. 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 in-volving 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 (Li2S, LiF, Li2O etc); and formation of a secondary matrix type phase due to cross interaction between reaction products and elec-trolyte components, which is followed by a highly dynamic mono-anionic polysulfide (i.e. LiS5) fouling process. 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

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

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

Determination of the Solid Electrolyte Interphase Structure Grown on a Silicon Electrode Using a Fluoroethylene Carbonate Additive

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

Veith, Gabriel M.; Doucet, Mathieu; Sacci, Robert L.

2017-07-24

In this work we explore how an electrolyte additive (fluorinated ethylene carbonate – FEC) mediates the thickness and composition of the solid electrolyte interphase formed over a silicon anode in situ as a function of state-of-charge and cycle. We show the FEC condenses on the surface at open circuit voltage then is reduced to C-O containing polymeric species around 0.9 V (vs. Li/Li +). The resulting film is about 50 Å thick. Upon lithiation the SEI thickens to 70 Å and becomes more organic-like. With delithiation the SEI thins by 13 Å and becomes more inorganic in nature, consistent withmore » the formation of LiF. This thickening/thinning is reversible with cycling and shows the SEI is a dynamic structure. We compare the SEI chemistry and thickness to 280 Å thick SEI layers produced without FEC and provide a mechanism for SEI formation using FEC additives.« less

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.

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

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.

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

Microscale Alloy Type Lithium Ion Battery Anodes

DTIC Science & Technology

2015-09-01

hexamethyldisilazane Li lithium Ni nickel NMP n-methyl-2-pyrolidone RMS root mean square SEI solid electrolyte interphase SEM scanning electron microscopy...process also leads to an unstable solid electrolyte interphase (SEI) and further capacity loss. An extraordinary amount of work has been done in an...

Effect of water on solid electrolyte interphase formation in Li-ion batteries

NASA Astrophysics Data System (ADS)

Saito, M.; Fujita, M.; Aoki, Y.; Yoshikawa, M.; Yasuda, K.; Ishigami, R.; Nakata, Y.

2016-03-01

Time-of-flight-elastic recoil detection analysis (TOF-ERDA) with 20 MeV Cu ions has been applied to measure the depth profiles of solid electrolyte interphase (SEI) layers on the negative electrode of lithium ion batteries (LIB). In order to obtain quantitative depth profiles, the detector efficiency was first assessed, and the test highlighted a strong mass and energy dependence of the recoiled particles, especially H and He. Subsequently, we prepared LIB cells with different water contents in the electrolyte, and subjected them to different charge-discharge cycle tests. TOF-ERDA, X-ray photoelectron spectrometry (XPS), gas chromatography (GC), ion chromatography (IC), and 1H nuclear magnetic resonance (1H NMR) were applied to characterize the SEI region of the negative electrode. The results showed that the SEI layer is formed after 300 cycle tests, and a 500 ppm water concentration in the electrolyte does not appear to cause significant differences in the elemental and organic content of the SEI.

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

Direct determination of solid-electrolyte interphase thickness and composition as a function of state of charge on a silicon anode

DOE PAGES

Veith, Gabriel M.; Doucet, Mathieu; Baldwin, J. K.; ...

2015-08-17

Using neutron reflectometry we have determined the thickness and chemistry of the solid-electrolyte interphase (SEI) layer grown on a silicon anode as a function of state of charge and during cycling. We show the chemistry of this SEI layer becomes more LiF like with increasing lithiation and more Li-C-O-F like with delithiation. More importantly the SEI layer thickness appears to increase (about 250 ) as the electrode becomes less lithiated and thins to 180 with increasing Li content (Li 3.7Si). We attribute this breathing to the continual consumption of electrolyte with cycling.

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

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.

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.

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.

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.

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.

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

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.

Deliberate modification of the solid electrolyte interphase (SEI) during lithiation of magnetite, Fe 3O 4: impact on electrochemistry

DOE PAGES

Bock, David C.; Marschilok, Amy C.; Takeuchi, Kenneth J.; ...

2017-11-20

Here, magnetite is a conversion anode material displaying multi-electron transfer during lithiation and delithiation. The solid electrolyte interphase (SEI) on magnetite, Fe 3O 4, electrodes for lithium ion batteries was deliberately modified through the use of fluoroethylene carbonate (FEC) electrolyte additive, improving both capacity retention and rate capability. Analysis showed reduction of FEC at higher voltage compared to non-fluorinated solvents with formation of a modified lithium flouride containing electrode surface.

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.

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.

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.

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.

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

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

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

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.

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

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.

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

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.

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.

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

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

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.

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.

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.

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.

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.

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

Role of perfluoropolyether-based electrolytes in lithium metal batteries: Implication for suppressed Al current collector corrosion and the stability of Li metal/electrolytes interfaces

NASA Astrophysics Data System (ADS)

Cong, Lina; Liu, Jia; Armand, Michel; Mauger, Alain; Julien, Christian M.; Xie, Haiming; Sun, Liqun

2018-03-01

The development of safe and high performance lithium metal batteries represents a major technological challenge for this new century. Historically, intrinsic instabilities of conventional liquid organic electrolytes induced battery failures and safety issues that hinder the practical utilization of advanced rechargeable lithium metal batteries. Herein, we report a multifunctional perfluoropolyether-based liquid polymer electrolyte (PFPE-MC/LiTFSI), presenting a unique "anion-solvent" interaction. This interaction optimizes the interfacial chemistry of lithium metal batteries, which effectively inhibits the corrosion of aluminum current collectors, suppresses lithium dendrite growth, and also facilitates the formation of a thin and stable SEI layer on Li anode. Even at a high current density of 0.7 mA cm-2, the lithium dendrites do not form after 1360 h of continuous operation. The LiFePO4|PFPE-MC/LiTFSI|Li cell delivers a stable cycling performance with over 99.9% columbic efficiency either at ambient temperature or high temperature, which is significantly superior to those using traditional carbonate electrolytes. In addition, PFPE-MC/LiTFSI electrolyte also possesses eye-catching properties, such as being non-flammable, non-volatile, non-hygroscopic, and existing in the liquid state between -90 °C and 200 °C, which further ensures the high safety of the lithium metal batteries, making this electrolyte promising for the development of high energy lithium metal batteries.

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).

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.

Structure of spontaneously formed solid-electrolyte interphase on lithiated graphite determined using small-angle neutron scattering

DOE PAGES

Sacci, Robert L.; Banuelos, Jose Leobardo; Veith, Gabriel M.; ...

2015-03-25

We report the first small-angle neutron scattering of a chemically formed solid-electrolyte interphase from LixC6 reacting with ethylene carbonate/dimethyl carbon solvent. This provides a different and perhaps simpler view of SEI formation than the usual electrochemically-driven reaction. We show that an organic layer coats the graphite particles filling in micro-pores and is polymeric in nature being 1-3 nm thick. We used inelastic neutron scattering to probe the chemistry, and we found that the SEI showed similar inelastic scattering to polyethylene oxide.

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

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

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.

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.

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

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

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

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.

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

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

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

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.

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.

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.

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.

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.

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.

1H,1H,5H-Perfluoropentyl-1,1,2,2-tetrafluoroethylether as a co-solvent for high voltage LiNi1/3Co1/3Mn1/3O2/graphite cells

NASA Astrophysics Data System (ADS)

Wang, Chengyun; Zuo, Xiaoxi; Zhao, Minkai; Xiao, Xin; Yu, Le; Nan, Junmin

2016-03-01

1H,1H,5H-Perfluoropentyl-1,1,2,2-tetrafluoroethylether (F-EAE) mixed with ethylene carbonate (EC), diethyl carbonate (DEC), and lithium hexafluorophosphate (LiPF6) is evaluated as a co-solvent high-potential electrolyte of LiNi1/3Co1/3Mn1/3O2/graphite batteries. Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) indicate that the EC/DEC-based electrolyte with F-EAE possesses a high oxidation potential (>5.2 V vs. Li/Li+) and excellent film-forming characteristics. With 40 wt% F-EAE in the electrolyte, the capacity retention of the LiNi1/3Co1/3Mn1/3O2/graphite pouch cells that are cycled between 3.0 and 4.5 V is significantly improved from 28.8% to 86.8% after 100 cycles. In addition, electrochemical impedance spectroscopy (EIS) of three-electrode pouch cells, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) are used to characterize the effects of F-EAE on the enhanced capacity retention. It is demonstrated that F-EAE facilitates the formation of a stable surface electrolyte interface (SEI) layer with low impedance on the anode and effectively suppresses an increase in the charge-transfer resistance on the cathode. These results suggest that F-EAE can serve as an alternative electrolyte solvent for 4.5 V high voltage rechargeable lithium-ion batteries.

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.

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.

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.

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

75 FR 16731 - Young Dodge SEIS; Kootenai National Forest, Lincoln County, MT

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-02

... (SEIS) for the Young Dodge project. The Young Dodge project includes urban interface fuels treatments... management changes, including road decommissioning. The project is located in the Young Dodge planning... Wildland-Urban Interface, to decrease the likelihood that fires would become stand-replacing wildfires; (2...

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.

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.

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

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.

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

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

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

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

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

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

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

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).

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

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.

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.

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

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

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.

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.

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

Extensive ionic partitioning in interfaces that membranous and biomimetic surfaces form with electrolytes: Antitheses of the gold-electrolyte interface

NASA Astrophysics Data System (ADS)

Chilcott, Terry; Guo, Chuan; Coster, Hans

2013-04-01

Maxwell-Wagner modeling of electrical impedance measurements of tetradecane-electrolyte systems yielded three interfacial layers between the tetradecane layer and the bulk electrolytes of concentration ranging from 1-300 mM KCl whereas the gold-electrolyte system yielded only one layer. The conductivity and thickness for the surface layer were orders of magnitude different from that expected for the Gouy-Chapman layer and did not reflect dependencies of the Debye length on concentration. Conductivity values for the three layers were less than those of the bulk electrolyte but exhibited a dependency on concentration similar to that expected for the bulk. Thickness values for the layers indicate an interface extending ~106 Å into the bulk electrolyte, which contrasts with the gold-electrolyte interface that extended only 20-30 Å into the bulk. Maxwell-Wagner characterizations of both interfaces were consistent with spatial distributions of ionic partitioning arising from the Born energy as determined by the dielectric properties of the substrates and electrolyte. The distributions for the membranous and silicon interfaces were similar but the antitheses of that for the gold interface.

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.

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.

An induced current method for measuring zeta potential of electrolyte solution-air interface.

PubMed

Song, Yongxin; Zhao, Kai; Wang, Junsheng; Wu, Xudong; Pan, Xinxiang; Sun, Yeqing; Li, Dongqing

2014-02-15

This paper reports a novel and very simple method for measuring the zeta potential of electrolyte solution-air interface. When a measuring electrode contacts the electrolyte solution-air interface, an electrical current will be generated due to the potential difference between the electrode-air surface and the electrolyte solution-air interface. The amplitude of the measured electric signal is linearly proportional to this potential difference; and depends only on the zeta potential at the electrolyte solution-air interface, regardless of the types and concentrations of the electrolyte. A correlation between the zeta potential and the measured voltage signal is obtained based on the experimental data. Using this equation, the zeta potential of any electrolyte solution-air interface can be evaluated quickly and easily by inserting an electrode through the electrolyte solution-air interface and measuring the electrical signal amplitude. This method was verified by comparing the obtained results of NaCl, MgCl2 and CaCl2 solutions of different pH values and concentrations with the zeta potential data reported in the published journal papers. Copyright © 2013 Elsevier Inc. All rights reserved.

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

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

SeisFlows-Flexible waveform inversion software

NASA Astrophysics Data System (ADS)

Modrak, Ryan T.; Borisov, Dmitry; Lefebvre, Matthieu; Tromp, Jeroen

2018-06-01

SeisFlows is an open source Python package that provides a customizable waveform inversion workflow and framework for research in oil and gas exploration, earthquake tomography, medical imaging, and other areas. New methods can be rapidly prototyped in SeisFlows by inheriting from default inversion or migration classes, and code can be tested on 2D examples before application to more expensive 3D problems. Wave simulations must be performed using an external software package such as SPECFEM3D. The ability to interface with external solvers lends flexibility, and the choice of SPECFEM3D as a default option provides optional GPU acceleration and other useful capabilities. Through support for massively parallel solvers and interfaces for high-performance computing (HPC) systems, inversions with thousands of seismic traces and billions of model parameters can be performed. So far, SeisFlows has run on clusters managed by the Department of Defense, Chevron Corp., Total S.A., Princeton University, and the University of Alaska, Fairbanks.

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.

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.

SeisComP 3 - Where are we now?

NASA Astrophysics Data System (ADS)

Saul, Joachim; Becker, Jan; Hanka, Winfried; Heinloo, Andres; Weber, Bernd

2010-05-01

The seismological software SeisComP has evolved within the last approximately 10 years from a pure acquisition modules to a fully featured real-time earthquake monitoring software. The now very popular SeedLink protocol for seismic data transmission has been the core of SeisComP from the very beginning. Later additions included simple, purely automatic event detection, location and magnitude determination capabilities. Especially within the development of the 3rd-generation SeisComP, also known as "SeisComP 3", automatic processing capabilities have been augmented by graphical user interfaces for vizualization, rapid event review and quality control. Communication between the modules is achieved using a a TCP/IP infrastructure that allows distributed computing and remote review. For seismological metadata exchange export/import to/from QuakeML is avalable, which also provides a convenient interface with 3rd-party software. SeisComP is the primary seismological processing software at the GFZ Potsdam. It has also been in use for years in numerous seismic networks in Europe and, more recently, has been adopted as primary monitoring software by several tsunami warning centers around the Indian Ocean. In our presentation we describe the current status of development as well as future plans. We illustrate its possibilities by discussing different use cases for global and regional real-time earthquake monitoring and tsunami warning.

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.

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.

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.

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

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

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.

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.

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

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.

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.

Charge regulation at semiconductor-electrolyte interfaces.

PubMed

Fleharty, Mark E; van Swol, Frank; Petsev, Dimiter N

2015-07-01

The interface between a semiconductor material and an electrolyte solution has interesting and complex electrostatic properties. Its behavior will depend on the density of mobile charge carriers that are present in both phases as well as on the surface chemistry at the interface through local charge regulation. The latter is driven by chemical equilibria involving the immobile surface groups and the potential determining ions in the electrolyte solution. All these lead to an electrostatic potential distribution that propagate such that the electrolyte and the semiconductor are dependent on each other. Hence, any variation in the charge density in one phase will lead to a response in the other. This has significant implications on the physical properties of single semiconductor-electrolyte interfaces and on the electrostatic interactions between semiconductor particles suspended in electrolyte solutions. The present paper expands on our previous publication (Fleharty et al., 2014) and offers new results on the electrostatics of single semiconductor interfaces as well as on the interaction of charged semiconductor colloids suspended in electrolyte solution. Copyright © 2014 Elsevier Inc. All rights reserved.

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

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.

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

Water at silica/liquid water interfaces investigated by DFT-MD simulations

NASA Astrophysics Data System (ADS)

Gaigeot, Marie-Pierre

This talk is dedicated to probing the microscopic structural organization of water at silica/liquid water interfaces including electrolytes by first principles DFT-based molecular dynamics simulations (DFT-MD). We will present our very recent DFT-MD simulations of electrolytic (KCl, NaCl, NaI) silica/liquid water interfaces in order to unravel the intertwined structural properties of water and electrolytes at the crystalline quartz/liquid water and amorphous silica/liquid water interfaces. DFT-MD simulations provide direct knowledge of the structural organization of water and the H-Bond network formed between the water molecules within the different water layers above the silica surface. One can furthermore extract vibrational signatures of the water molecules within the interfacial layers from the DFT-MD simulations, especially non-linear SFG (Sum Frequency generation) signatures that are active at solid/liquid interfaces. The strength of the simulated spectra is that a detailed analysis of the signatures in terms of the water/water H-Bond networks formed within the interfacial water layers and in terms of the water/silica or water/electrolytes H-Bond networks can be given. Comparisons of SFG spectra between quartz/water/electrolytes and amorphous silica/water/electrolytes interfaces allow us to definitely conclude on how the structural arrangements of liquid water at these electrolytic interfaces modulate the final spectroscopic signatures. Invited speaker.

Surface and interface sciences of Li-ion batteries. -Research progress in electrode-electrolyte interface-

NASA Astrophysics Data System (ADS)

Minato, Taketoshi; Abe, Takeshi

2017-12-01

The application potential of Li-ion batteries is growing as demand increases in different fields at various stages in energy systems, in addition to their conventional role as power sources for portable devices. In particular, applications in electric vehicles and renewable energy storage are increasing for Li-ion batteries. For these applications, improvements in battery performance are necessary. The Li-ion battery produces and stores electric power from the electrochemical redox reactions between the electrode materials. The interface between the electrodes and electrolyte strongly affects the battery performance because the charge transfer causing the electrode redox reaction begins at this interface. Understanding of the surface structure, electronic structure, and chemical reactions at the electrode-electrolyte interface is necessary to improve battery performance. However, the interface is located between the electrode and electrolyte materials, hindering the experimental analysis of the interface; thus, the physical properties and chemical processes have remained poorly understood until recently. Investigations of the physical properties and chemical processes at the interface have been performed using advanced surface science techniques. In this review, current knowledge and future research prospects regarding the electrode-electrolyte interface are described for the further development of Li-ion batteries.

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.

Using Molecular Dynamics to quantify the electrical double layer and examine the potential for its direct observation in the in-situ TEM

DOE PAGES

Welch, David A.; Mehdi, Beata L.; Hatchell, Hanna J.; ...

2015-03-25

Understanding the fundamental processes taking place at the electrode-electrolyte interface in batteries will play a key role in the development of next generation energy storage technologies. One of the most fundamental aspects of the electrode-electrolyte interface is the electrical double layer (EDL). Given the recent development of high spatial resolution in-situ electrochemical cells for scanning transmission electron microscopy (STEM), there now exists the possibility that we can directly observe the formation and dynamics of the EDL. In this paper we predict electrolyte structure within the EDL using classical models and atomistic Molecular Dynamics (MD) simulations. The MD simulations show thatmore » the classical models fail to accurately reproduce concentration profiles that exist within the electrolyte. It is thus suggested that MD must be used in order to accurately predict STEM images of the electrode-electrolyte interface. Using MD and image simulations together for a high contrast electrolyte (the high atomic number CsCl electrolyte), it is determined that, for a smooth interface, concentration profiles within the EDL should be visible experimentally. When normal experimental parameters such as rough interfaces and low-Z electrolytes (like those used in Li-ion batteries) are considered, observation of the EDL appears to be more difficult.« less

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.

Electrode-electrolyte interface model of tripolar concentric ring electrode and electrode paste.

PubMed

Nasrollaholhosseini, Seyed Hadi; Steele, Preston; Besio, Walter G

2016-08-01

Electrodes are used to transform ionic currents to electrical currents in biological systems. Modeling the electrode-electrolyte interface could help to optimize the performance of the electrode interface to achieve higher signal to noise ratios. There are previous reports of accurate models for single-element biomedical electrodes. In this paper we develop a model for the electrode-electrolyte interface for tripolar concentric ring electrodes (TCRE) that are used to record brain signals.

Noncovalent Pi-Pi Stacking at the Carbon-Electrolyte Interface: Controlling the Voltage Window of Electrochemical Supercapacitors.

PubMed

Li, Mengya; Westover, Andrew S; Carter, Rachel; Oakes, Landon; Muralidharan, Nitin; Boire, Timothy C; Sung, Hak-Joon; Pint, Cary L

2016-08-03

A key parameter in the operation of an electrochemical double-layer capacitor is the voltage window, which dictates the device energy density and power density. Here we demonstrate experimental evidence that π-π stacking at a carbon-ionic liquid interface can modify the operation voltage of a supercapacitor device by up to 30%, and this can be recovered by steric hindrance at the electrode-electrolyte interface introduced by poly(ethylene oxide) polymer electrolyte additives. This observation is supported by Raman spectroscopy, electrochemical impedance spectroscopy, and differential scanning calorimetry that each independently elucidates the signature of π-π stacking between imidazole groups in the ionic liquid and the carbon surface and the role this plays to lower the energy barrier for charge transfer at the electrode-electrolyte interface. This effect is further observed universally across two separate ionic liquid electrolyte systems and is validated by control experiments showing an invariant electrochemical window in the absence of a carbon-ionic liquid electrode-electrolyte interface. As interfacial or noncovalent interactions are usually neglected in the mechanistic picture of double-layer capacitors, this work highlights the importance of understanding chemical properties at supercapacitor interfaces to engineer voltage and energy capability.

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

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

Energy Materials Center at Cornell: Final Report

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

Abruña, Héctor; Mutolo, Paul F

2015-01-02

The mission of the Energy Materials Center at Cornell (emc 2) was to achieve a detailed understanding, via a combination of synthesis of new materials, experimental and computational approaches, of how the nature, structure, and dynamics of nanostructured interfaces affect energy conversion and storage with emphasis on fuel cells, batteries and supercapacitors. Our research on these systems was organized around a full system strategy for; the development and improved performance of materials for both electrodes at which storage or conversion occurs; understanding their internal interfaces, such as SEI layers in batteries and electrocatalyst supports in fuel cells, and methods formore » structuring them to enable high mass transport as well as high ionic and electronic conductivity; development of ion-conducting electrolytes for batteries and fuel cells (separately) and other separator components, as needed; and development of methods for the characterization of these systems under operating conditions (operando methods) Generally, our work took industry and DOE report findings of current materials as a point of departure to focus on novel material sets for improved performance. In addition, some of our work focused on studying existing materials, for example observing battery solvent degradation, fuel cell catalyst coarsening or monitoring lithium dendrite growth, employing in operando methods developed within the center.« less

Investigating the air oxidation of V(II) ions in a vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Ngamsai, Kittima; Arpornwichanop, Amornchai

2015-11-01

The air oxidation of vanadium (V(II)) ions in a negative electrolyte reservoir is a major side reaction in a vanadium redox flow battery (VRB), which leads to electrolyte imbalance and self-discharge of the system during long-term operation. In this study, an 80% charged negative electrolyte solution is employed to investigate the mechanism and influential factors of the reaction in a negative-electrolyte reservoir. The results show that the air oxidation of V(II) ions occurs at the air-electrolyte solution interface area and leads to a concentration gradient of vanadium ions in the electrolyte solution and to the diffusion of V(II) and V(III) ions. The effect of the ratio of the electrolyte volume to the air-electrolyte solution interface area and the concentrations of vanadium and sulfuric acid in an electrolyte solution is investigated. A higher ratio of electrolyte volume to the air-electrolyte solution interface area results in a slower oxidation reaction rate. The high concentrations of vanadium and sulfuric acid solution also retard the air oxidation of V(II) ions. This information can be utilized to design an appropriate electrolyte reservoir for the VRB system and to prepare suitable ingredients for the electrolyte solution.

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

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

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

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.

Potential-specific structure at the hematite-electrolyte interface

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

McBriarty, Martin E.; Stubbs, Joanne; Eng, Peter

The atomic-scale structure of interfaces between metal oxides and aqueous electrolytes controls their catalytic, geochemical, and corrosion behavior. Measurements that probe these interfaces in situ provide important details of ion and solvent arrangements, but atomically precise structural models do not exist for common oxide-electrolyte interfaces far from equilibrium. Using a novel cell, we measured the structure of the hematite (a-Fe 2O 3) (110more » $$\\bar{2}$$)-electrolyte interface under controlled electrochemical bias using synchrotron crystal truncation rod X ray scattering. At increasingly cathodic potentials, charge-compensating protonation of surface oxygen groups increases the coverage of specifically bound water while adjacent water layers displace outwardly and became disordered. Returning to open circuit potential leaves the surface in a persistent metastable protonation state. The flux of current and ions at applied potential is thus regulated by a unique interfacial electrolyte environment, suggesting that electrical double layer models should be adapted to the dynamically changing interfacial structure far from equilibrium.« less

In Situ Mass Spectrometric Monitoring of the Dynamic Electrochemical Process at the Electrode–Electrolyte Interface: a SIMS Approach

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

Wang, Zhaoying; Zhang, Yanyan; Liu, Bingwen

The in situ molecular characterization of reaction intermediates and products at electrode-electrolyte interfaces is central to mechanistic studies of complex electrochemical processes, yet a great challenge. The coupling of electrochemistry (EC) and mass spectrometry (MS) has seen rapid development and found broad applicability in tackling challenges in analytical and bioanalytical chemistry. However, few truly in situ and real-time EC-MS studies have been reported at electrode-electrolyte interfaces. An innovative EC-MS coupling method named in situ liquid secondary ion mass spectrometry (SIMS) was recently developed by combining SIMS with a vacuum compatible microfluidic electrochemical device. Using this novel capability we report themore » first in situ elucidation of the electro-oxidation mechanism of a biologically significant organic compound, ascorbic acid (AA), at the electrode-electrolyte interface. The short-lived radical intermediate was successfully captured, which had not been detected directly before. Moreover, we demonstrated the power of this new technique in real-time monitoring of the formation and dynamic evolution of electrical double layers at the electrode-electrolyte interface. This work suggests further promising applications of in situ liquid SIMS in studying more complex chemical and biological events at the electrode-electrolyte interface.« less

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.

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

Experimental Evaluation of the Synthetic Solid Electrolyte Interface (SSEI) Concept for the Primary Ca-SOCl2 Battery System

DTIC Science & Technology

1988-12-01

coatings based on the Ca(Sr,Y)- Ge-S system can serve as an effective SSEI for Ca anodes in Ca-SOC12 primary cells using 1 M Ca(AlCl4 )2 as the electrolyte...I iy - LFI. CDY 4 EXPERIMENTAL EVALUATION OF THE SYNTHETIC SOLID ELECTROLYTE INTERFACE ( SSEI ) CONCEPT FOR THE PRIMARY Ca-SOC1 2 BA LERY SYSTEM...apply the concept of a synthetic solid electrolyte interface ( SSEI ) to overcome the problem of Ca corro- sion in Ca-SOC 2 primary cells. / To this end

Second harmonic generation study of malachite green adsorption at the interface between air and an electrolyte solution: observing the effect of excess electrical charge density at the interface.

PubMed

Song, Jinsuk; Kim, Mahn Won

2010-03-11

Understanding the differential adsorption of ions at the interface of an electrolyte solution is very important because it is closely related, not only to the fundamental aspects of biological systems, but also to many industrial applications. We have measured the excess interfacial negative charge density at air-electrolyte solution interfaces by using resonant second harmonic generation of oppositely charged probe molecules. The excess charge density increased with the square root of the bulk electrolyte concentration. A new adsorption model that includes the electrostatic interaction between adsorbed molecules is proposed to explain the measured adsorption isotherm, and it is in good agreement with the experimental results.

Germanium Nanowires-in-Graphite Tubes via Self-Catalyzed Synergetic Confined Growth and Shell-Splitting Enhanced Li-Storage Performance.

PubMed

Sun, Yong; Jin, Shuaixing; Yang, Guowei; Wang, Jing; Wang, Chengxin

2015-04-28

Despite the high theoretical capacity, pure Ge has various difficulties such as significant volume expansion and electron and Li(+) transfer problems, when applied as anode materials in lithium ion battery (LIB), for which the solution would finally rely on rational design like advanced structures and available hybrid. Here in this work, we report a one-step synthesis of Ge nanowires-in-graphite tubes (GNIGTs) with the liquid Ge/C synergetic confined growth method. The structure exhibits impressing LIB behavior in terms of both cyclic stability and rate performance. We found the semiclosed graphite shell with thickness of ∼50 layers experience an interesting splitting process that was driven by electrolyte diffusion, which occurs before the Ge-Li alloying plateau begins. Two types of different splitting mechanism addressed as "inside-out"/zipper effect and "outside-in" dominate this process, which are resulted from the SEI layer growing longitudinally along the Ge-graphite interface and the lateral diffusion of Li(+) across the shell, respectively. The former mechanism is the predominant way driving the initial shell to split, which behaves like a zipper with SEI layer as invisible puller. After repeated Li(+) insertion/exaction, the GNIGTs configuration is finally reconstructed by forming Ge nanowires-thin graphite strip hybrid, both of which are in close contact, resulting in enormous enchantment to the electrons/Li(+) transport. These features make the structures perform well as anode material in LIB. We believe both the progress in 1D assembly and the structure evolution of this Ge-C composite would contribute to the design of advanced LIB anode materials.

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.

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.

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.

Combined soft and hard X-ray ambient pressure photoelectron spectroscopy studies of semiconductor/electrolyte interfaces

DOE PAGES

Starr, David E.; Favaro, Marco; Abdi, Fatwa F.; ...

2017-05-18

The development of solar fuel generating materials would greatly benefit from a molecular level understanding of the semiconductor/electrolyte interface and changes in the interface induced by an applied potential and illumination by solar light. Ambient pressure photoelectron spectroscopy techniques with both soft and hard X-rays, AP-XPS and AP-HAXPES respectively, have the potential to markedly contribute to this understanding. In this paper we initially provide two examples of current challenges in solar fuels material development that AP-XPS and AP-HAXPES can directly a ddress. This will be followed by a brief description of the distinguishing and complementary characteristics of soft and hardmore » X-ray AP-XPS and AP-HAXPES and best approaches to achieving monolayer sensitivity in solid/aqueous electrolyte studies. In particular we focus on the detection of surface adsorbed hydroxyl groups in the presence of aqueous hydroxide anions in the electrolyte, a common situation when investigating photoanodes for solar fuel generating applications. Finally, the article concludes by providing an example of a combined AP-XPS and AP-HAXPES study of a semiconductor/aqueous electrolyte interface currently used in water splitting devices specifically the BiVO 4/aqueous potassium phosphate electrolyte interface.« less

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.

Poly (acrylic acid sodium) grafted carboxymethyl cellulose as a high performance polymer binder for silicon anode in lithium ion batteries

PubMed Central

Wei, Liangming; Chen, Changxin; Hou, Zhongyu; Wei, Hao

2016-01-01

The design of novel binder systems is required for the high capacity silicon (Si) anodes which usually undergo huge volume change during the charge/discharge cycling. Here, we introduce a poly (acrylic acid sodium)-grafted-carboxymethyl cellulose (NaPAA-g-CMC) copolymer as an excellent binder for Si anode in lithium ion batteries (LIBs). The NaPAA-g-CMC copolymer was prepared via a free radical graft polymerization method by using CMC and acrylic acid as precursors. Unlike the linear, one-dimensional binders, the NaPAA-g-CMC copolymer binder is expected to present multi-point interaction with Si surface, resulting in enhanced binding ability with Si particles as well as with the copper (Cu) current collectors, and building a stable solid electrolyte interface (SEI) layer on the Si surface. The NaPAA-g-CMC based Si anode shows much better cycle stability and higher coulombic efficiency than those made with the well-known linear polymeric binders such as CMC and NaPPA. PMID:26786315

Cu2+1O coated polycrystalline Si nanoparticles as anode for lithium-ion battery.

PubMed

Zhang, Junying; Zhang, Chunqian; Wu, Shouming; Liu, Zhi; Zheng, Jun; Zuo, Yuhua; Xue, Chunlai; Li, Chuanbo; Cheng, Buwen

2016-12-01

Cu2+1O coated Si nanoparticles were prepared by simple hydrolysis and were investigated as an anode material for lithium-ion battery. The coating of Cu2+1O on the surface of Si particles remarkably improves the cycle performance of the battery than that made by the pristine Si. The battery exhibits an initial reversible capacity of 3063 mAh/g and an initial coulombic efficiency (CE) of 82.9 %. With a current density of 300 mA/g, its reversible capacity can remains 1060 mAh/g after 350 cycles, corresponding to a CE ≥ 99.8 %. It is believed that the Cu2+1O coating enhances the electrical conductivity, and the elasticity of Cu2+1O further helps buffer the volume changes during lithiation/delithiation processes. Experiment results indicate that the electrode maintained a highly integrated structure after 100 cycles and it is in favour of the formation of stable solid electrolyte interface (SEI) on the Si surface to keep the extremely high CE during long charge and discharge cycles.

Degradation Mechanisms at the Li10GeP2S12/LiCoO2 Cathode Interface in an All-Solid-State Lithium-Ion Battery.

PubMed

Zhang, Wenbo; Richter, Felix H; Culver, Sean P; Leichtweiss, Thomas; Lozano, Juan G; Dietrich, Christian; Bruce, Peter G; Zeier, Wolfgang G; Janek, Jürgen

2018-06-20

All-solid-state batteries (ASSBs) show great potential for providing high power and energy densities with enhanced battery safety. While new solid electrolytes (SEs) have been developed with high enough ionic conductivities, SSBs with long operational life are still rarely reported. Therefore, on the way to high-performance and long-life ASSBs, a better understanding of the complex degradation mechanisms, occurring at the electrode/electrolyte interfaces is pivotal. While the lithium metal/solid electrolyte interface is receiving considerable attention due to the quest for high energy density, the interface between the active material and solid electrolyte particles within the composite cathode is arguably the most difficult to solve and study. In this work, multiple characterization methods are combined to better understand the processes that occur at the LiCoO 2 cathode and the Li 10 GeP 2 S 12 solid electrolyte interface. Indium and Li 4 Ti 5 O 12 are used as anode materials to avoid the instability problems associated with Li-metal anodes. Capacity fading and increased impedances are observed during long-term cycling. Postmortem analysis with scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy show that electrochemically driven mechanical failure and degradation at the cathode/solid electrolyte interface contribute to the increase in internal resistance and the resulting capacity fading. These results suggest that the development of electrochemically more stable SEs and the engineering of cathode/SE interfaces are crucial for achieving reliable SSB 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.

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.

Method of doping a semiconductor

DOEpatents

Yang, Chiang Y.; Rapp, Robert A.

1983-01-01

A method for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient.

In situ engineering of the electrode-electrolyte interface for stabilized overlithiated cathodes

DOE PAGES

Evans, Tyler; Piper, Daniela Molina; Sun, Huaxing; ...

2017-01-05

Here, the first-ever demonstration of stabilized Si/lithium-manganese-rich full cells, capable of retaining >90% energy over early cycling and >90% capacity over more than 750 cycles at the 1C rate (100% depth-of-discharge), is made through the utilization of a modified ionic liquid electrolyte capable of forming a favorable cathode-electrolyte interface.

Novel structure formation at the bottom surface of porous anodic alumina fabricated by single step anodization process.

PubMed

Ali, Ghafar; Ahmad, Maqsood; Akhter, Javed Iqbal; Maqbool, Muhammad; Cho, Sung Oh

2010-08-01

A simple approach for the growth of long-range highly ordered nanoporous anodic alumina film in H(2)SO(4) electrolyte through a single step anodization without any additional pre-anodizing procedure is reported. Free-standing porous anodic alumina film of 180 microm thickness with through hole morphology was obtained. A simple and single step process was used for the detachment of alumina from aluminum substrate. The effect of anodizing conditions, such as anodizing voltage and time on the pore diameter and pore ordering is discussed. The metal/oxide and oxide/electrolyte interfaces were examined by high resolution scanning transmission electron microscope. The arrangement of pores on metal/oxide interface was well ordered with smaller diameters than that of the oxide/electrolyte interface. The inter-pore distance was larger in metal/oxide interface as compared to the oxide/electrolyte interface. The size of the ordered domain was found to depend strongly upon anodizing voltage and time. (c) 2010 Elsevier Ltd. All rights reserved.

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.

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.

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).

Bridging Redox Species-Coated Graphene Oxide Sheets to Electrode for Extending Battery Life Using Nanocomposite Electrolyte.

PubMed

Huang, Yi Fu; Ruan, Wen Hong; Lin, Dong Ling; Zhang, Ming Qiu

2017-01-11

Substituting conventional electrolyte for redox electrolyte has provided a new intriguing method for extending battery life. The efficiency of utilizing the contained redox species (RS) in the redox electrolyte can benefit from increasing the specific surface area of battery electrodes from the electrode side of the electrode-electrolyte interface, but is not limited to that. Herein, a new strategy using nanocomposite electrolyte is proposed to enlarge the interface with the aid of nanoinclusions from the electrolyte side. To do this, graphene oxide (GO) sheets are first dispersed in the electrolyte solution of tungstosilicic salt/lithium sulfate/poly(vinyl alcohol) (SiWLi/Li 2 SO 4 /PVA), and then the sheets are bridged to electrode, after casting and evaporating the solution on the electrode surface. By applying in situ conductive atomic force microscopy and Raman spectra, it is confirmed that the GO sheets doped with RS of SiWLi/Li 2 SO 4 can be bridged and electrically reduced as an extended electrode-electrolyte interface. As a result, the RS-coated GO sheets bridged to LiTi 2 (PO 4 ) 3 //LiMn 2 O 4 battery electrodes are found to deliver extra energy capacity (∼30 mAh/g) with excellent electrochemical cycling stability, which successfully extends the battery life by over 50%.

Charge Saturation and Intrinsic Doping in Electrolyte-Gated Organic Semiconductors.

PubMed

Atallah, Timothy L; Gustafsson, Martin V; Schmidt, Elliot; Frisbie, C Daniel; Zhu, X-Y

2015-12-03

Electrolyte gating enables low voltage operation of organic thin film transistors, but little is known about the nature of the electrolyte/organic interface. Here we apply charge-modulation Fourier transform infrared spectroscopy, in conjunction with electrical measurements, on a model electrolyte gated organic semiconductor interface: single crystal rubrene/ion-gel. We provide spectroscopic signature for free-hole like carriers in the organic semiconductor and unambiguously show the presence of a high density of intrinsic doping of the free holes upon formation of the rubrene/ion-gel interface, without gate bias (Vg = 0 V). We explain this intrinsic doping as resulting from a thermodynamic driving force for the stabilization of free holes in the organic semiconductor by anions in the ion-gel. Spectroscopy also reveals the saturation of free-hole like carrier density at the rubrene/ion-gel interface at Vg < -0.5 V, which is commensurate with the negative transconductance seen in transistor measurements.

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.

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.

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.

Operando X-ray Investigation of Electrode/Electrolyte Interfaces in Model Solid Oxide Fuel Cells

PubMed Central

2016-01-01

We employed operando anomalous surface X-ray diffraction to investigate the buried interface between the cathode and the electrolyte of a model solid oxide fuel cell with atomic resolution. The cell was studied under different oxygen pressures at elevated temperatures and polarizations by external potential control. Making use of anomalous X-ray diffraction effects at the Y and Zr K-edges allowed us to resolve the interfacial structure and chemical composition of a (100)-oriented, 9.5 mol % yttria-stabilized zirconia (YSZ) single crystal electrolyte below a La0.6Sr0.4CoO3−δ (LSC) electrode. We observe yttrium segregation toward the YSZ/LSC electrolyte/electrode interface under reducing conditions. Under oxidizing conditions, the interface becomes Y depleted. The yttrium segregation is corroborated by an enhanced outward relaxation of the YSZ interfacial metal ion layer. At the same time, an increase in point defect concentration in the electrolyte at the interface was observed, as evidenced by reduced YSZ crystallographic site occupancies for the cations as well as the oxygen ions. Such changes in composition are expected to strongly influence the oxygen ion transport through this interface which plays an important role for the performance of solid oxide fuel cells. The structure of the interface is compared to the bare YSZ(100) surface structure near the microelectrode under identical conditions and to the structure of the YSZ(100) surface prepared under ultrahigh vacuum conditions. PMID:27346923

Telecommunications, navigation and information management concept overview for the Space Exploration Initiative program

NASA Technical Reports Server (NTRS)

Bell, Jerome A.; Stephens, Elaine; Barton, Gregg

1991-01-01

An overview is provided of the Space Exploration Initiative (SEI) concepts for telecommunications, information systems, and navigation (TISN), and engineering and architecture issues are discussed. The SEI program data system is reviewed to identify mission TISN interfaces, and reference TISN concepts are described for nominal, degraded, and mission-critical data services. The infrastructures reviewed include telecommunications for robotics support, autonomous navigation without earth-based support, and information networks for tracking and data acquisition. Four options for TISN support architectures are examined which relate to unique SEI exploration strategies. Detailed support estimates are given for: (1) a manned stay on Mars; (2) permanent lunar and Martian settlements; short-duration missions; and (4) systematic exploration of the moon and Mars.

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

Electrochemical cell utilizing molten alkali metal electrode-reactant

DOEpatents

Virkar, Anil V.; Miller, Gerald R.

1983-11-04

An improved electrochemical cell comprising an additive-modified molten alkali metal electrode-reactant and/or electrolyte is disclosed. Various electrochemical cells employing a molten alkali metal, e.g., sodium, electrode in contact with a cationically conductive ceramic membrane experience a lower resistance and a lower temperature coefficient of resistance whenever small amounts of selenium are present at the interface of the electrolyte and the molten alkali metal. Further, cells having small amounts of selenium present at the electrolyte-molten metal interface exhibit less degradation of the electrolyte under long term cycling conditions.

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.

Investigation of a novel ternary electrolyte based on dimethyl sulfite and lithium difluoromono(oxalato)borate for lithium ion batteries

NASA Astrophysics Data System (ADS)

Chen, Renjie; Zhu, Lu; Wu, Feng; Li, Li; Zhang, Rong; Chen, Shi

2014-01-01

Lithium difluoromono(oxalato)borate (LiODFB) has been used as a novel lithium salt for battery in recent studies. In this study, a series of novel electrolytes has been prepared by adding 30 vol% dimethyl sulfite (DMS) or dimethyl carbonate (DMC) as co-solvent into an ethylene carbonate (EC)/ethyl methyl carbonate (EMC) + LiX mixture, in which the LiX could be LiClO4, LiODFB, LiBOB, LiTFSI, or LiCF3SO3. These ternary electrolytes have been investigated for use in lithium ion batteries. FT-IR spectroscopy analysis shows that characteristic functional groups (-CO3, -SO3) undergo red-shift or blue-shift with the addition of different lithium salts. The LiODFB-EC/EMC/DMS electrolyte exhibits high ionic conductivity, which is mainly because of the low melting point of DMS, and LiODFB possessing high solubility. The Li/MCMB cells containing this novel electrolyte exhibit high capacities, good cycling performance, and excellent rate performance. These performances are probably because both LiODFB and DMS can assist in the formation of SEI films by reductive decomposition. Additionally, the discharge capacity of Li/LiCoO2 half cell containing LiODFB-EC/EMC/DMS electrolyte is 130.9 mAh g-1 after 50 cycles, and it is very comparable with the standard-commercial electrolyte. The results show that this study produces a promising electrolyte candidate for lithium ion batteries.

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.

Molecular adsorption at electrolyte/α-Al2O3 interface of aluminum electrolytic capacitor revealed by sum frequency vibrational spectroscopy.

PubMed

Jia, Ming; Hu, Xiaoyu; Liu, Jin; Liu, Yexiang; Ai, Liang

2017-05-21

The operating voltage of an aluminum electrolytic capacitor is determined by the breakdown voltage (U b ) of the Al 2 O 3 anode. U b is related to the molecular adsorption at the Al 2 O 3 /electrolyte interface. Therefore, we have employed sum-frequency vibrational spectroscopy (SFVS) to study the adsorption states of a simple electrolyte, ethylene glycol (EG) solution with ammonium adipate, on an α-Al 2 O 3 surface. In an acidic electrolyte (pH < 6), the Al 2 O 3 surface is positively charged. The observed SFVS spectra show that long chain molecules poly ethylene glycol and ethylene glycol adipate adopt a "lying" orientation at the interface. In an alkaline electrolyte (pH > 8), the Al 2 O 3 surface is negatively charged and the short chain EG molecules adopt a "tilting" orientation. The U b results exhibit a much higher value at pH < 6 compared with that at pH > 8. Since the "lying" long chain molecules cover and protect the Al 2 O 3 surface, U b increases with a decrease of pH. These findings provide new insights to study the breakdown mechanisms and to develop new electrolytes for high operating voltage capacitors.

Effect of cycling on the lithium/electrolyte interface in organic electrolytes

NASA Technical Reports Server (NTRS)

Surampudi, S.; Shen, D. H.; Huang, C.-K.; Narayanan, S. R.; Attia, A.; Halpert, G.; Peled, E.

1993-01-01

Nondestructive methods such as ac impedance spectroscopy and microcalorimetry are used to study the effect of cell cycling on the lithium/electrolyte interface. The reactivity of both uncycled and cycled lithium towards various electrolytes is examined by measuring the heat evolved from the cells under open-circuit conditions at 25 C by microcalorimetry. Cycled cells at the end of charge/discharge exhibited considerably higher heat output compared with the uncycled cells. After 30 d of storage, the heat output of the cycled cells is similar to that of the uncycled cells. The cell internal resistance increases with cycling, and this is attributed to the degradation of the electrolyte with cycling.

Photoelectrical Stimulation of Neuronal Cells by an Organic Semiconductor-Electrolyte Interface.

PubMed

Abdullaeva, Oliya S; Schulz, Matthias; Balzer, Frank; Parisi, Jürgen; Lützen, Arne; Dedek, Karin; Schiek, Manuela

2016-08-23

As a step toward the realization of neuroprosthetics for vision restoration, we follow an electrophysiological patch-clamp approach to study the fundamental photoelectrical stimulation mechanism of neuronal model cells by an organic semiconductor-electrolyte interface. Our photoactive layer consisting of an anilino-squaraine donor blended with a fullerene acceptor is supporting the growth of the neuronal model cell line (N2A cells) without an adhesion layer on it and is not impairing cell viability. The transient photocurrent signal upon illumination from the semiconductor-electrolyte layer is able to trigger a passive response of the neuronal cells under physiological conditions via a capacitive coupling mechanism. We study the dynamics of the capacitive transmembrane currents by patch-clamp recordings and compare them to the dynamics of the photocurrent signal and its spectral responsivity. Furthermore, we characterize the morphology of the semiconductor-electrolyte interface by atomic force microscopy and study the stability of the interface in dark and under illuminated conditions.

Potential of Zero Charge and Its Temperature Derivative for Au(111) Electrode|Alkanethiol SAM|1.0 M Aqueous Electrolyte Solution Interfaces: Impact of Electrolyte Solution Ionic Strength and Its Effect on the Structure of the Modified Electrode|Electrolyte Solution Interface

DOE PAGES

Smalley, John F.

2017-04-06

In this study, we demonstrate how small and rapid temperature perturbations (produced by the indirect laser-induced temperature jump (ILIT) technique) of solid metal electrode|electrolyte solution interfaces may be used to determine the potential of zero (total) charge (E pzc) and its temperature derivativemore » $$\\left(\\frac{dEpzc}{dT}\\right)$$ of Au(111) electrode surfaces modified by alkanethiol self-assembled monolayers in contact with high ionic strength (i.e., 1.0 M) aqueous electrolyte solutions. The E pzc’s measured for two different types of SAMs (made from either HS(CH 2) n-1CH 3 (5 ≤ n ≤ 12, E pzc = -(0.99 ± 0.12) V vs SSCE) or HS(CH 2) nOH (3 ≤ n ≤ 16, E pzc = (0.46 ± 0.22) V vs SSCE)) are considerably different than those measured previously at much lower electrolyte solution ionic strengths. For mixed monolayers made from both HS(CH 2) n-1CH 3 and HS(CH 2) nFc (where Fc refers to ferrocene), the difference in Epzc decreases as a function of the surface concentration of the Fc moiety (i.e., [Fc]), and it completely disappears at a surprisingly small [Fc] (~4.0 × 10 –11 mol cm –2). These observations for the Au(111)|hydrophobic (neat and mixed) SAM|aqueous electrolyte solution interfaces, along with the surface potentials (g Sml(dip)) evaluated for the contacting electrolyte solution surfaces of these interfaces, are consistent with a structure for the water molecule components of these surfaces where there is a net orientation of the dipoles of these molecules. Accordingly, the negative (oxygen) ends of these molecules point toward the SAM surface. The positive values of g Sml(dip) evaluated for hydrophilic SAM (e.g., made from HS(CH 2) nOH)|aqueous electrolyte solution interfaces) also indicate that the structure of these interfaces is similar to that of the hydrophobic interfaces. However, g Sml(dip) decreases with increasing ionic strength for the hydrophilic interfaces, while it increases with increasing ionic strength for the hydrophobic interfaces. The data (and calculations) reported in the present work and other studies of hydrophobic (and hydrophilic)|aqueous solution interfaces are as yet insufficient to support a complete explanation for the effects of ionic strength observed in the present study. Nevertheless, an analysis based upon the value of $$\\left(\\frac{dEpzc}{dT}\\right)$$ (= (0.51 ± 0.12) mV/K, essentially the same for SAMs made from both HS(CH 2) n-1CH 3 and HS(CH 2) nOH), determined in the present study provides a further indication that upon formation of the SAM there is a partial charge transfer of electrons from the relevant gold atoms on the Au(111) surface to the sulfur atoms of the alkanethiols.« less

Li Distribution Heterogeneity in Solid Electrolyte Li10GeP2S12 upon Electrochemical Cycling Probed by 7Li MRI.

PubMed

Chien, Po-Hsiu; Feng, Xuyong; Tang, Mingxue; Rosenberg, Jens T; O'Neill, Sean; Zheng, Jin; Grant, Samuel C; Hu, Yan-Yan

2018-04-19

All-solid-state rechargeable batteries embody the promise for high energy density, increased stability, and improved safety. However, their success is impeded by high resistance for mass and charge transfer at electrode-electrolyte interfaces. Li deficiency has been proposed as a major culprit for interfacial resistance, yet experimental evidence is elusive due to the challenges associated with noninvasively probing the Li distribution in solid electrolytes. In this Letter, three-dimensional 7 Li magnetic resonance imaging (MRI) is employed to examine Li distribution homogeneity in solid electrolyte Li 10 GeP 2 S 12 within symmetric Li/Li 10 GeP 2 S 12 /Li batteries. 7 Li MRI and the derived histograms reveal Li depletion from the electrode-electrolyte interfaces and increased heterogeneity of Li distribution upon electrochemical cycling. Significant Li loss at interfaces is mitigated via facile modification with a poly(ethylene oxide)/bis(trifluoromethane)sulfonimide Li salt thin film. This study demonstrates a powerful tool for noninvasively monitoring the Li distribution at the interfaces and in the bulk of all-solid-state batteries as well as a convenient strategy for improving interfacial stability.

Molecular dynamics simulations of lithium silicate/vanadium pentoxide interfacial lithium ion diffusion in thin film lithium ion-conducting devices

NASA Astrophysics Data System (ADS)

Li, Weiqun

The lithium ion diffusion behavior and mechanism in the glassy electrolyte and the electrolyte/cathode interface during the initial stage of lithium ion diffusing from electrolyte into cathode were investigated using Molecular Dynamics simulation technique. Lithium aluminosilicate glass electrolytes with different R (ratio of the concentration of Al to Li) were simulated. The structural features of the simulated glasses are analyzed using Radial Distribution Function (RDF) and Pair Distribution Function (PDF). The diffusion coefficient and activation energy of lithium ion diffusion in simulated lithium aluminosilicate glasses were calculated and the values are consistent with those in experimental glasses. The behavior of lithium ion diffusion from the glassy electrolyte into a polycrystalline layered intercalation cathode has been studied. The solid electrolyte was a model lithium silicate glass while the cathode was a nanocrystalline vanadia with amorphous V2O5 intergranular films (IGF) between the V2O5 crystals. Two different orientations between the V2O5 crystal planes are presented for lithium ion intercalation via the amorphous vanadia IGF. A series of polycrystalline vanadia cathodes with 1.3, 1.9, 2.9 and 4.4 nm thickness IGFs were simulated to examine the effects of the IGF thickness on lithium ion transport in the polycrystalline vanadia cathodes. The simulated results showed that the lithium ions diffused from the glassy electrolyte into the IGF of the polycrystalline vanadia cathode and then part of those lithium ions diffused into the crystalline V2O5 from the IGF. The simulated results also showed an ordering of the vanadium ion structure in the IGF near the IGF/V2 O5 interface. The ordering structure still existed with glass former silica additive in IGF. Additionally, 2.9 run is suggested to be the optimal thickness of the IGF, which is neither too thick to decrease the capacity of the cathode nor too thin to impede the transport of lithium from glassy electrolyte into the cathode. Parallel molecular dynamic simulation technique was also used for a larger electrolyte/cathode interface system, which include more atoms and more complicated microstructures. Simulation results from larger electrolyte/cathode interface system prove that there is no size effect on simulation of smaller electrolyte/cathode interface system from statistical point of view.

Lithium-ion battery electrolyte mobility at nano-confined graphene interfaces

PubMed Central

Moeremans, Boaz; Cheng, Hsiu-Wei; Hu, Qingyun; Garces, Hector F.; Padture, Nitin P.; Renner, Frank Uwe; Valtiner, Markus

2016-01-01

Interfaces are essential in electrochemical processes, providing a critical nanoscopic design feature for composite electrodes used in Li-ion batteries. Understanding the structure, wetting and mobility at nano-confined interfaces is important for improving the efficiency and lifetime of electrochemical devices. Here we use a Surface Forces Apparatus to quantify the initial wetting of nanometre-confined graphene, gold and mica surfaces by Li-ion battery electrolytes. Our results indicate preferential wetting of confined graphene in comparison with gold or mica surfaces because of specific interactions of the electrolyte with the graphene surface. In addition, wetting of a confined pore proceeds via a profoundly different mechanism compared with wetting of a macroscopic surface. We further reveal the existence of molecularly layered structures of the confined electrolyte. Nanoscopic confinement of less than 4–5 nm and the presence of water decrease the mobility of the electrolyte. These results suggest a lower limit for the pore diameter in nanostructured electrodes. PMID:27562148

Software engineering activities at SEI (Software Engineering Institute)

NASA Technical Reports Server (NTRS)

Chittister, Clyde

1990-01-01

Prototyping was shown to ease system specification and implementation, especially in the area of user interfaces. Other prototyping approaches do not allow for the evolution of the prototype into a production system or support maintenance after the system is fielded. A set of goals is presented for a modern user interface environment and Serpent, a prototype implementation that achieves these goals, is described.

Gas evolution from cathode materials: A pathway to solvent decomposition concomitant to SEI formation.

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

Browning, Katie L; Baggetto, Loic; Unocic, Raymond R

This work reports a method to explore the catalytic reactivity of electrode surfaces towards the decomposition of carbonate solvents [ethylene carbonate (EC), dimethyl carbonate (DMC), and EC/DMC]. We show that the decomposition of a 1:1 wt% EC/DMC mixture is accelerated over certain commercially available LiCoO2 materials resulting in the formation of CO2 while over pure EC or DMC the reaction is much slower or negligible. The solubility of the produced CO2 in carbonate solvents is high (0.025 grams/mL) which masks the effect of electrolyte decomposition during storage or use. The origin of this decomposition is not clear but it ismore » expected to be present on other cathode materials and may affect the analysis of SEI products as well as the safety of Li-ion batteries.« less

Investigation on the interface between Li10GeP2S12 electrolyte and carbon conductive agents in all-solid-state lithium battery.

PubMed

Yoon, Kyungho; Kim, Jung-Joon; Seong, Won Mo; Lee, Myeong Hwan; Kang, Kisuk

2018-05-23

All-solid-state batteries are considered as one of the attractive alternatives to conventional lithium-ion batteries, due to their intrinsic safe properties benefiting from the use of non-flammable solid electrolytes in ASSBs. However, one of the issues in employing the solid-state electrolyte is the sluggish ion transport kinetics arising from the chemical and physical instability of the interfaces among solid components including electrode material, electrolyte and additive agents. In this work, we investigate the stability of the interface between carbon conductive agents and Li 10 GeP 2 S 12 in a composite cathode and its effect on the electrochemical performance of ASSBs. It is found that the inclusion of various carbon conductive agents in composite cathode leads to inferior kinetic performance of the cathode despite expectedly enhanced electrical conductivity of the composite. We observe that the poor kinetic performance is attributed to a large interfacial impedance which is gradually developed upon the inclusions of the various carbon conductive agents regardless of their physical differences. The analysis through X-ray Photoelectron Spectroscopy suggests that the carbon additives in the composite cathode stimulate the electrochemical decomposition of LGPS electrolyte degrading its surface during cycling, indicating the large interfacial resistance stems from the undesirable decomposition of the electrolyte at the interface.

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.

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

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

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.

Investigation of electrolytes utilized for high-voltage LiNi0.5Mn1.5O4 batteries

NASA Astrophysics Data System (ADS)

Qin, Yinping; Lin, Huan; Liu, Yang; Wang, Deyu

2017-10-01

The main challenge of high-voltage LiNi0.5Mn1.5O4 (LNMO), which is one of the most promising cathodes with the redox plateau of ˜4.75V vs Li+/Li, is the decomposition of electrolyte. In fact, our studies show that LNMO presents the good capacity retention ratio, higher than 80% after 300 cycles, in the electrolyte with the mixture of pure carbonate solvents. Even 92% of the initial capacity in the 300th cycle is remained in the optimal composition. Obviously, high-voltage LiNi0.5Mn1.5O4 can get excellent cycle performance without any special additives. In addition, we studied the electrochemical behavior of viny lene carbonate (VC) and ethylene sulfite (ES) in high potential. The results indicate that VC and ES can be electrochemically oxidized at 4.6 V and 4.05 V vs Li+/Li, respectively. In the cells with the electrolytes containing VC and ES respectively, the discharge capacities are significantly diminished. Also, the thick and high-resistance sediment layers are formed on the surface of LNMO. We concluded that the SEI-forming additives widely used in commercial batteries may firstly decompose on cathode side. Therefore, the electrolyte systems should be redesigned for graphite-LNMO batteries.

Carbon Materials Embedded with Metal Nanoparticles as Anode in Lithium-Ion Batteries

NASA Technical Reports Server (NTRS)

Hung, Ching-cheh

2002-01-01

Carbon materials containing metal nanoparticles that can form an alloy with lithium were tested for their capacity and cycle life to store and release lithium electrochemically. Metal nanoparticles may provide the additional lithium storage capacity as well as additional channels to conduct lithium in carbon. The cycle life of this carbon-metal composite can be long because the solid-electrolyte interface (SEI) on the carbon surface may protect both lithium and the metal particles in the carbon interior. In addition, the voids in the carbon interior may accommodate the nanoparticle's volume change, and such volume change may not cause much internal stress due to small sizes of the nanoparticles. This concept of improving carbon's performance to store and release lithium was demonstrated using experimental cells of C(Pd)/0.5M Lil-50/50 (vol.%) EC and DMC/Li, where C(Pd) was graphitized carbon fibers containing palladium nanoparticles, EC was ethylene carbonate, and DMC was dimethyl carbonate. However, such improvement was not observed if the Pd nanoparticles are replaced by aluminum, possibly because the aluminum nanoparticles were oxidized in air during storage, resulting in an inert oxide of aluminum. Further studies are needed to use this concept for practical applications.

First principles modeling of the metal-electrolyte interface: A novel approach to the study of the electrochemical interface

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

Fernandez-Serra, Maria Victoria

2016-09-12

The research objective of this proposal is the computational modeling of the metal-electrolyte interface purely from first principles. The accurate calculation of the electrostatic potential at electrically biased metal-electrolyte interfaces is a current challenge for periodic “ab-initio” simulations. It is also an essential requisite for predicting the correspondence between the macroscopic voltage and the microscopic interfacial charge distribution in electrochemical fuel cells. This interfacial charge distribution is the result of the chemical bonding between solute and metal atoms, and therefore cannot be accurately calculated with the use of semi-empirical classical force fields. The project aims to study in detail themore » structure and dynamics of aqueous electrolytes at metallic interfaces taking into account the effect of the electrode potential. Another side of the project is to produce an accurate method to simulate the water/metal interface. While both experimental and theoretical surface scientists have made a lot of progress on the understanding and characterization of both atomistic structures and reactions at the solid/vacuum interface, the theoretical description of electrochemical interfaces is still lacking behind. A reason for this is that a complete and accurate first principles description of both the liquid and the metal interfaces is still computationally too expensive and complex, since their characteristics are governed by the explicit atomic and electronic structure built at the interface as a response to environmental conditions. This project will characterize in detail how different theoretical levels of modeling describer the metal/water interface. In particular the role of van der Waals interactions will be carefully analyzed and prescriptions to perform accurate simulations will be produced.« less

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.

Study of Surface States at the Semiconductor/electrolyte Interface of Liquid-Junction Solar Cells.

NASA Astrophysics Data System (ADS)

Siripala, Withana P.

The existence of surface states at the semiconductor electrolyte interface of photoelectrochemical (PEC) cells plays a major role in determining the performance of the device in regard to the potential distribution and transport mechanisms of photogenerated carriers at the interface. We have investigated the n-TiO(,2)/electrolyte interface using three experimental techniques: relaxation spectrum analysis, photocurrent spectroscopy, and electrolyte electroreflectance (EER) spectroscopy. The effect of Fermi level pinning at the CdIn(,2)SE(,4)/aqueous-polysulfide interface was also studied using EER. Three distinct surface states were observed at the n-TiO(,2)/aqueous-electrolyte interface. The dominant state, which tails from the conduction band edge, is primarily responsible for the surface recombination of photocarriers at the interface. The second surface state, observed at 0.8 eV below the conduction band of TiO(,2), originates in the dark charge transfer intermediates (TiO(,2)-H). It is proposed that the sub-bandgap (SBG) photocurrent-potential behavior is a result of the mechanism of dynamic formation and annihilation of these surface states. The third surface state was at 1.3 eV below the conduction band of TiO(,2), and the SBG EER measurements show this state is "intrinsic" to the surface. These states were detected with SBG EER and impedance measurements in the presence of electrolytes that can adsorb on the surface of TiO(,2). Surface concentration of these states was evaluated with impedance measurements. EER measurements on a CdIn(,2)Se(,4)/polysulfide system have shown that the EER spectrum is sensitive to the surface preparation of the sample. The EER signal was quenched as the surface was driven to strong depletion, owing to Fermi level pinning at the interface in the presence of a high density of surface states. The full analysis of this effect enables us to measure the change in the flatband potential, as a function of the electrode potential, and also the energy distribution of these states.

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.

Novel Solid Electrolytes for Li-Ion Batteries: A Perspective from Electron Microscopy Studies

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

Ma, Cheng; Chi, Miaofang

2016-06-08

Solid electrolytes can simultaneously overcome two of the most formidable challenges of Li-ion batteries: the severe safety issues and insufficient energy densities. However, before they can be implemented in actual batteries, the ionic conductivity needs to be improved and the interface with electrodes must be optimized. The prerequisite for addressing these issues is a thorough understanding of the material’s behavior at the microscopic and/or the atomic level. (Scanning) transmission electron microscopy is a powerful tool for this purpose, as it can reach an ultrahigh spatial resolution. Here, we review recent electron microscopy investigations on the ion transport behavior in solidmore » electrolytes and their interfaces. Specifically, three aspects will be highlighted: the influence of grain interior atomic configuration on ionic conductivity, the contribution of grain boundaries, and the behavior of solid electrolyte/electrode interfaces. In conclusion, based on this, the perspectives for future research will be discussed.« less

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

Ion distributions in electrolyte confined by multiple dielectric interfaces

NASA Astrophysics Data System (ADS)

Jing, Yufei; Zwanikken, Jos W.; Jadhao, Vikram; de La Cruz, Monica

2014-03-01

The distribution of ions at dielectric interfaces between liquids characterized by different dielectric permittivities is crucial to nanoscale assembly processes in many biological and synthetic materials such as cell membranes, colloids and oil-water emulsions. The knowledge of ionic structure of these systems is also exploited in energy storage devices such as double-layer super-capacitors. The presence of multiple dielectric interfaces often complicates computing the desired ionic distributions via simulations or theory. Here, we use coarse-grained models to compute the ionic distributions in a system of electrolyte confined by two planar dielectric interfaces using Car-Parrinello molecular dynamics simulations and liquid state theory. We compute the density profiles for various electrolyte concentrations, stoichiometric ratios and dielectric contrasts. The explanations for the trends in these profiles and discuss their effects on the behavior of the confined charged fluid are also presented.

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.

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

Stabilizing the Electrode/Electrolyte Interface of LiNi0.8Co0.15Al0.05O2 through Tailoring Aluminum Distribution in Microspheres as Long-Life, High-Rate, and Safe Cathode for Lithium-Ion Batteries.

PubMed

Hou, Peiyu; Zhang, Hongzhou; Deng, Xiaolong; Xu, Xijin; Zhang, Lianqi

2017-09-06

The unstable electrode/electrolyte interface of high-capacity LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) cathodes, especially at a highly delithiated state, usually leads to the transformation of layered to spinel and/or rock-salt phases, resulting in drastic capacity fade and poor thermal stability. Herein, the Al-increased and Ni-,Co-decreased electrode surface is fabricated through tailoring element distribution in micrometer-sized spherical NCA secondary particles via coprecipitation and solid-state reactions, aimed at stabilizing the electrode/electrolyte interface during continuous cycles. As expected, it shows much extended cycle life, 93.6% capacity retention within 100 cycles, compared with that of 78.5% for the normal NCA. It also delivers large reversible capacity of about 140 mAh g -1 even at 20 C, corresponding to energy density of around 480 Wh kg -1 , which is enhanced by 45% compared to that of the normal NCA (about 330 Wh kg -1 ). Besides, the delayed heat emission temperature and reduced heat generation mean remarkably improved thermal stability. These foregoing improvements are ascribed to the Al-increased spherical secondary particle surface that stabilizes the electrode/electrolyte interface by protecting inner components from directly contacting with electrolyte and suppressing the side reaction on electrode surface between high oxidizing Ni 4+ and electrolyte.

Stabilizing electrochemical interfaces in viscoelastic liquid electrolytes

PubMed Central

2018-01-01

Electrodeposition is a widely practiced method for creating metal, colloidal, and polymer coatings on conductive substrates. In the Newtonian liquid electrolytes typically used, the process is fundamentally unstable. The underlying instabilities have been linked to failure of microcircuits, dendrite formation on battery electrodes, and overlimiting conductance in ion-selective membranes. We report that viscoelastic electrolytes composed of semidilute solutions of very high–molecular weight neutral polymers suppress these instabilities by multiple mechanisms. The voltage window ΔV in which a liquid electrolyte can operate free of electroconvective instabilities is shown to be markedly extended in viscoelastic electrolytes and is a power-law function, ΔV : η1/4, of electrolyte viscosity, η. This power-law relation is replicated in the resistance to ion transport at liquid/solid interfaces. We discuss consequences of our observations and show that viscoelastic electrolytes enable stable electrodeposition of many metals, with the most profound effects observed for reactive metals, such as sodium and lithium. This finding is of contemporary interest for high-energy electrochemical energy storage. PMID:29582017

Semiconductor-Electrocatalyst Interfaces: Theory, Experiment, and Applications in Photoelectrochemical Water Splitting.

PubMed

Nellist, Michael R; Laskowski, Forrest A L; Lin, Fuding; Mills, Thomas J; Boettcher, Shannon W

2016-04-19

Light-absorbing semiconductor electrodes coated with electrocatalysts are key components of photoelectrochemical energy conversion and storage systems. Efforts to optimize these systems have been slowed by an inadequate understanding of the semiconductor-electrocatalyst (sem|cat) interface. The sem|cat interface is important because it separates and collects photoexcited charge carriers from the semiconductor. The photovoltage generated by the interface drives "uphill" photochemical reactions, such as water splitting to form hydrogen fuel. Here we describe efforts to understand the microscopic processes and materials parameters governing interfacial electron transfer between light-absorbing semiconductors, electrocatalysts, and solution. We highlight the properties of transition-metal oxyhydroxide electrocatalysts, such as Ni(Fe)OOH, because they are the fastest oxygen-evolution catalysts known in alkaline media and are (typically) permeable to electrolyte. We describe the physics that govern the charge-transfer kinetics for different interface types, and show how numerical simulations can explain the response of composite systems. Emphasis is placed on "limiting" behavior. Electrocatalysts that are permeable to electrolyte form "adaptive" junctions where the interface energetics change during operation as charge accumulates in the catalyst, but is screened locally by electrolyte ions. Electrocatalysts that are dense, and thus impermeable to electrolyte, form buried junctions where the interface physics are unchanged during operation. Experiments to directly measure the interface behavior and test the theory/simulations are challenging because conventional photoelectrochemical techniques do not measure the electrocatalyst potential during operation. We developed dual-working-electrode (DWE) photoelectrochemistry to address this limitation. A second electrode is attached to the catalyst layer to sense or control current/voltage independent from that of the semiconductor back ohmic contact. Consistent with simulations, electrolyte-permeable, redox-active catalysts such as Ni(Fe)OOH form "adaptive" junctions where the effective barrier height for electron exchange depends on the potential of the catalyst. This is in contrast to sem|cat interfaces with dense electrolyte-impermeable catalysts, such as nanocrystalline IrOx, that behave like solid-state buried (Schottky-like) junctions. These results elucidate a design principle for catalyzed photoelectrodes. The buried heterojunctions formed by dense catalysts are often limited by Fermi-level pinning and low photovoltages. Catalysts deposited by "soft" methods, such as electrodeposition, form adaptive junctions that tend to provide larger photovoltages and efficiencies. We also preview efforts to improve theory/simulations to account for the presence of surface states and discuss the prospect of carrier-selective catalyst contacts.

Design principles for electrolytes and interfaces for stable lithium-metal batteries

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

Tikekar, Mukul D.; Choudhury, Snehashis; Tu, Zhengyuan

2016-09-08

The future of electrochemical energy storage hinges on the advancement of science and technology that enables rechargeable batteries that utilize reactive metals as anodes. With specific capacity more than ten times that of the LiC6 anode used in present-day lithium-ion batteries, cells based on Li-metal anodes are of particular interest. Effective strategies for stabilizing the anode in such cells are now understood to be a requirement for progress on exceptional storage technologies, including Li–S and Li–O2 batteries. Multiple challenges—parasitic reactions of Li-metal with liquid electrolytes, unstable and dendritic electrodeposition, and dendrite-induced short circuits—derailed early efforts to commercialize such lithium-metal batteries.more » Here we consider approaches for rationally designing electrolytes and Li-metal/electrolyte interfaces for stable, dendrite-free operation of lithium-metal batteries. On the basis of fundamental understanding of the failure modes of reactive metal anodes, we discuss the key variables that govern the stability of electrodeposition at the Li anode and propose a universal framework for designing stable electrolytes and interfaces for lithium-metal batteries.« less

Design principles for electrolytes and interfaces for stable lithium-metal batteries

NASA Astrophysics Data System (ADS)

Tikekar, Mukul D.; Choudhury, Snehashis; Tu, Zhengyuan; Archer, Lynden A.

2016-09-01

The future of electrochemical energy storage hinges on the advancement of science and technology that enables rechargeable batteries that utilize reactive metals as anodes. With specific capacity more than ten times that of the LiC6 anode used in present-day lithium-ion batteries, cells based on Li-metal anodes are of particular interest. Effective strategies for stabilizing the anode in such cells are now understood to be a requirement for progress on exceptional storage technologies, including Li-S and Li-O2 batteries. Multiple challenges—parasitic reactions of Li-metal with liquid electrolytes, unstable and dendritic electrodeposition, and dendrite-induced short circuits—derailed early efforts to commercialize such lithium-metal batteries. Here we consider approaches for rationally designing electrolytes and Li-metal/electrolyte interfaces for stable, dendrite-free operation of lithium-metal batteries. On the basis of fundamental understanding of the failure modes of reactive metal anodes, we discuss the key variables that govern the stability of electrodeposition at the Li anode and propose a universal framework for designing stable electrolytes and interfaces for lithium-metal batteries.

Study of the H2O/Al2O3 Interface and the Acting Mechanism of Water in the Working Electrolyte

NASA Astrophysics Data System (ADS)

Jia, Ming; Li, Qiang; Li, Lixiang; Cao, Liang; Yang, Juan; Zhou, Xiangyang; Ai, Liang

2018-04-01

Using a working electrolyte containing mixed solvents of ethylene glycol and N,N-dimethylformamide, this paper presents a study of the reactions on the H2O/Al2O3 interface with sum frequency vibrational spectroscopy and the effects of different water content on the performance of the working electrolyte and an aluminum electrolytic capacitor and summarizes the rules of the variations in the performance parameters of the working electrolyte and aluminum electrolytic capacitor with respect to the water content. The results demonstrate that, when the water content is increased from 2.5 to 15%, the conductivity of the working electrolyte increased by 930 μS/cm, and the sparking voltage decreased by 27 V. Also, the increased water content causes lower oxidation efficiency and lower thermal stability. The leakage current of the aluminum electrolytic capacitor after high-temperature storage increases with an increase in the water content, and the attenuation rate of capacitor's the low-temperature capacitance decreases with an increase in the water content.

Self-consistent modeling of electrochemical strain microscopy of solid electrolytes

DOE PAGES

Tselev, Alexander; Morozovska, Anna N.; Udod, Alexei; ...

2014-10-10

Electrochemical strain microscopy (ESM) employs a strong electromechanical coupling in solid ionic conductors to map ionic transport and electrochemical processes with nanometer-scale spatial resolution. To elucidate the mechanisms of the ESM image formation, we performed self-consistent numerical modeling of the electromechanical response in solid electrolytes under the probe tip in a linear, small-signal regime using the Boltzmann–Planck–Nernst–Einstein theory and Vegard's law while taking account of the electromigration and diffusion. We identified the characteristic time scales involved in the formation of the ESM response and found that the dynamics of the charge carriers in the tip-electrolyte system with blocking interfaces canmore » be described as charging of the diffuse layer at the tip-electrolyte interface through the tip contact spreading resistance. At the high frequencies used in the detection regime, the distribution of the charge carriers under the tip is governed by evanescent concentration waves generated at the tip-electrolyte interface. The ion drift length in the electric field produced by the tip determines the ESM response at high frequencies, which follows a 1/f asymptotic law. The electronic conductivity, as well as the electron transport through the electrode-electrolyte interface, do not have a significant effect on the ESM signal in the detection regime. The results indicate, however, that for typical solid electrolytes at room temperature, the ESM response originates at and contains information about the very surface layer of a sample, and the properties of the one-unit-cell-thick surface layer may significantly contribute to the ESM response, implying a high surface sensitivity and a high lateral resolution of the technique. On the other hand, it follows that a rigorous analysis of the ESM signals requires techniques that account for the discrete nature of a solid.« less

A key discovery at the TiO2/dye/electrolyte interface: slow local charge compensation and a reversible electric field.

PubMed

Yang, Wenxing; Pazoki, Meysam; Eriksson, Anna I K; Hao, Yan; Boschloo, Gerrit

2015-07-14

Dye-sensitized mesoporous TiO2 films have been widely applied in energy and environmental science related research fields. The interaction between accumulated electrons inside TiO2 and cations in the surrounding electrolyte at the TiO2/dye/electrolyte interface is, however, still poorly understood. This interaction is undoubtedly important for both device performance and fundamental understanding. In the present study, Stark effects of an organic dye, LEG4, adsorbed on TiO2 were well characterized and used as a probe to monitor the local electric field at the TiO2/dye/electrolyte interface. By using time-resolved photo- and potential-induced absorption techniques, we found evidence for a slow (t > 0.1 s) local charge compensation mechanism, which follows electron accumulation inside the mesoporous TiO2. This slow local compensation was attributed to the penetration of cations from the electrolyte into the adsorbed dye layer, leading to a more localized charge compensation of the electrons inside TiO2. Importantly, when the electrons inside TiO2 were extracted, a remarkable reversal of the surface electric field was observed for the first time, which is attributed to the penetrated and/or adsorbed cations now being charge compensated by anions in the bulk electrolyte. A cation electrosorption model is developed to account for the overall process. These findings give new insights into the mesoporous TiO2/dye/electrolyte interface and the electron-cation interaction mechanism. Electrosorbed cations are proposed to act as electrostatic trap states for electrons in the mesoporous TiO2 electrode.

What Can We Learn from Solid State NMR on the Electrode-Electrolyte Interface?

PubMed

Haber, Shira; Leskes, Michal

2018-06-11

Rechargeable battery cells are composed of two electrodes separated by an ion-conducting electrolyte. While the energy density of the cell is mostly determined by the redox potential of the electrodes and amount of charge they can store, the processes at the electrode-electrolyte interface govern the battery's lifetime and performance. Viable battery cells rely on unimpeded ion transport across this interface, which depends on its composition and structure. These properties are challenging to determine as interfacial phases are thin, disordered, heterogeneous, and can be very reactive. The recent developments and applications of solid state NMR spectroscopy in the study of interfacial phenomena in rechargeable batteries based on lithium and sodium chemistries are reviewed. The different NMR interactions are surveyed and how these are used to shed light on the chemical composition and architecture of interfacial phases as well as directly probe ion transport across them is described. By combining new methods in solid state NMR spectroscopy with other analytical tools, a holistic description of the electrode-electrolyte interface can be obtained. This will enable the design of improved interfaces for developing battery cells with high energy, high power, and longer lifetime. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrodeposition of Polymer Nanostructures using Three Diffuse Double Layers: Polymerization beyond the Liquid/Liquid Interfaces

NASA Astrophysics Data System (ADS)

Divya, Velpula; Sangaranarayanan, M. V.

2018-04-01

Nanostructured conducting polymers have received immense attention during the past few decades on account of their phenomenal usefulness in diverse contexts, while the interface between two immiscible liquids is of great interest in chemical and biological applications. Here we propose a novel Electrode(solid)/Electrolyte(aqueous)/Electrolyte(organic) Interfacial assembly for the synthesis of polymeric nanostructures using a novel concept of three diffuse double layers. There exist remarkable differences between the morphologies of the polymers synthesized using the conventional electrode/electrolyte method and that of the new approach. In contrast to the commonly employed electrodeposition at liquid/liquid interfaces, these polymer modified electrodes can be directly employed in diverse applications such as sensors, supercapacitors etc.

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.

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

Investigation of Charge Transfer Kinetics at Carbon/Hydroquinone Interfaces for Redox-Active-Electrolyte Supercapacitors.

PubMed

Park, Jinwoo; Kumar, Vipin; Wang, Xu; Lee, Pooi See; Kim, Woong

2017-10-04

The redox-active electrolyte supercapacitor (RAES) is a relatively new type of energy storage device. Simple addition of selected redox species in the electrolyte can greatly enhance the energy density of supercapacitors relative to traditional electric double layer capacitors (EDLCs) owing to redox reactions. Studies on the kinetics at the interface of the electrode and redox mediator are important when developing RAESs. In this work, we employ highly accurate scanning electrochemical microscopy (SECM) to extract the kinetic constants at carbon/hydroquinone interfaces. The charge transfer rate constants are 1.2 × 10 -2 and 1.3 × 10 -2 cm s -1 for the carbon nanotube/hydroquinone and reduced graphene oxide/hydroquinone interfaces, respectively. These values are higher than those obtained by the conventional cyclic voltammetry method, approximately by an order of magnitude. The evaluation of heterogeneous rate constants with SECM would be the cornerstone for understanding and developing high performance RAESs.

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

FAST TRACK COMMUNICATION Spectral signatures of the surface reconstructions of Au(110)/electrolyte interfaces

NASA Astrophysics Data System (ADS)

Smith, C. I.; Bowfield, A.; Almond, N. J.; Mansley, C. P.; Convery, J. H.; Weightman, P.

2010-10-01

It is demonstrated that the (1 × 1) structure and the (1 × 2) and (1 × 3) surface reconstructions that occur at Au(110)/electrolyte interfaces have unique optical fingerprints. The optical fingerprints are potential, pH and anion dependent and have potential for use in monitoring dynamic changes at this interface. We also observe a specific reflection anisotropy spectroscopy signature that may arise from anions adsorbed on the (1 × 1) structure of Au(110).

Post mortem analysis of fatigue mechanisms in LiNi0.8Co0.15Al0.05O2 - LiNi0.5Co0.2Mn0.3O2 - LiMn2O4/graphite lithium ion batteries

NASA Astrophysics Data System (ADS)

Lang, Michael; Darma, Mariyam Susana Dewi; Kleiner, Karin; Riekehr, Lars; Mereacre, Liuda; Ávila Pérez, Marta; Liebau, Verena; Ehrenberg, Helmut

2016-09-01

The fatigue of commercial lithium ion batteries after long-term cycling at two different temperatures and cycling rates is investigated. The cells are opened after cycling and post-mortem analysis are conducted. Two main contributions to the capacity loss of the batteries are revealed. The loss of active lithium leads to a relative shift between anodes and cathodes potentials. A growth of the solid electrolyte interface (SEI) on the anode is determined as well as the formation of lithium fluoride species as an electrolyte decomposition product. Those effects are reinforced by increasing cycling rates from 1C/2C (charge/discharge) to 2C/3C as well as by increasing cycling temperatures from 25 °C to 40 °C. The other contribution to the capacity loss originates from a fatigue of the blended cathodes consisting of LiNi0.5Co0.2Mn0.3O2 (NCM), LiNi0.8Co0.15Al0.05O2 (NCA) and LiMn2O4 (LMO). Phase-specific capacity losses and fatigue mechanisms are identified. The layered oxides tend to form microcracks and reveal changes of the surface structure leading to a worsening of the lithium kinetics. The cathode exhibits a loss of manganese at 40 °C cycling temperature. Cycling at 40 °C instead of 25 °C has the major impact on cathodes capacity loss, while cycling at 2C/3C rates barely influences it.

High-Performance Flexible Solid-State Supercapacitor with an Extended Nanoregime Interface through in Situ Polymer Electrolyte Generation.

PubMed

Anothumakkool, Bihag; Torris A T, Arun; Veeliyath, Sajna; Vijayakumar, Vidyanand; Badiger, Manohar V; Kurungot, Sreekumar

2016-01-20

Here, we report an efficient strategy by which a significantly enhanced electrode-electrolyte interface in an electrode for supercapacitor application could be accomplished by allowing in situ polymer gel electrolyte generation inside the nanopores of the electrodes. This unique and highly efficient strategy could be conceived by judiciously maintaining ultraviolet-triggered polymerization of a monomer mixture in the presence of a high-surface-area porous carbon. The method is very simple and scalable, and a prototype, flexible solid-state supercapacitor could even be demonstrated in an encapsulation-free condition by using the commercial-grade electrodes (thickness = 150 μm, area = 12 cm(2), and mass loading = 7.3 mg/cm(2)). This prototype device shows a capacitance of 130 F/g at a substantially reduced internal resistance of 0.5 Ω and a high capacitance retention of 84% after 32000 cycles. The present system is found to be clearly outperforming a similar system derived by using the conventional polymer electrolyte (PVA-H3PO4 as the electrolyte), which could display a capacitance of only 95 F/g, and this value falls to nearly 50% in just 5000 cycles. The superior performance in the present case is credited primarily to the excellent interface formation of the in situ generated polymer electrolyte inside the nanopores of the electrode. Further, the interpenetrated nature of the polymer also helps the device to show a low electron spin resonance and power rate and, most importantly, excellent shelf-life in the unsealed flexible conditions. Because the nature of the electrode-electrolyte interface is the major performance-determining factor in the case of many electrochemical energy storage/conversion systems, along with the supercapacitors, the developed process can also find applications in preparing electrodes for the devices such as lithium-ion batteries, metal-air batteries, polymer electrolyte membrane fuel cells, etc.

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.

Charge-induced equilibrium dynamics and structure at the Ag(001)–electrolyte interface

DOE PAGES

Karl Jr., Robert M.; Barbour, Andi; Komanicky, Vladimir; ...

2015-06-08

We have measured the applied potential dependent rate of atomic step motion of the Ag (001) surface in weak NaF electrolyte using a new extension of the technique of X-ray Photon Correlation Spectroscopy (XPCS). Furthermore, concurrent specular x-ray scattering measurements reveal how the ordering of the water layers at the interface correlates with the dynamics.

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.

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.

Polymers for new battery technologies.

NASA Astrophysics Data System (ADS)

Singh, Mohit

2009-03-01

The chemical and electrochemical reactivity of the components comprising today's lithium batteries has severely limited their lifetime and stability, and attempts to push the limits on energy density have exacerbated these stability issues. The weakest link in terms of safety and stability of Li ion systems is the organic liquid electrolyte that facilitates the Li^+ ion transport between the electrodes. The electrolyte is flammable and electrochemically unstable against the graphitic anode. It is the continuous electrochemical degradation of the electrolyte at the electrodes that leads to poor cycle life of the batteries, and in some cases runaway reactions that lead to explosions. Dry polymer electrolytes alleviate the electrochemical stability problem by offering a stable electrode-electrolyte interface. The absence of flammable liquids prevents runaway reactions. The main hurdle that has prevented dry polymer electrolytes from being commercialized is low ionic conductivity, and challenges in interfacing with the electrode materials. We demonstrate a novel approach towards addressing these challenges that renders batteries with excellent cycle lives, and thermal stability.

Effects of different electrolytes for micro-arc oxidation on the bond strength between titanium and porcelain.

PubMed

Yuan, Xiaohui; Tan, Fei; Xu, Haitao; Zhang, Shaojun; Qu, Fuzhen; Liu, Jie

2017-07-01

The aim of this study is to investigate the effects of different electrolytes on the titanium-porcelain bond strength after micro-arc oxidation (MAO) treatment. Three electrolytes at the same concentration were used as MAO reaction solutions: Na 2 SiO 3 , KF, and MgSiF 6 . Blasting treatment was chosen as a control. After MAO treatment in each electrolyte, the titanium-porcelain bond strengths were measured by the three-point bending test, as described in ISO 9693. The morphologies and elemental compositions of the MAO coating on the titanium substrate were evaluated by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The interface between the titanium and porcelain was also observed by SEM and EDS. The MAO coatings created in different electrolytes exhibited completely different morphologies and compositions. The bond strengths of the Na 2 SiO 3 and MgSiF 6 groups were significantly higher than those of the other groups (p<0.05). Additionally, the titanium-porcelain interfaces were compact in the former two groups, whereas pores and cracks were visible at the interfaces in the other groups. These results indicate that MAO treatment with an appropriate electrolyte could be an effective method to increase the titanium-porcelain bonding strength. According to ISO 9693, titanium-porcelain restorations subjected to MAO treatment with an appropriate electrolyte could be appropriate for clinical use. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Hybrid deposition of thin film solid oxide fuel cells and electrolyzers

DOEpatents

Jankowski, A.F.; Makowiecki, D.M.; Rambach, G.D.; Randich, E.

1998-05-19

The use of vapor deposition techniques enables synthesis of the basic components of a solid oxide fuel cell (SOFC); namely, the electrolyte layer, the two electrodes, and the electrolyte-electrode interfaces. Such vapor deposition techniques provide solutions to each of the three critical steps of material synthesis to produce a thin film solid oxide fuel cell (TFSOFC). The electrolyte is formed by reactive deposition of essentially any ion conducting oxide, such as defect free, yttria stabilized zirconia (YSZ) by planar magnetron sputtering. The electrodes are formed from ceramic powders sputter coated with an appropriate metal and sintered to a porous compact. The electrolyte-electrode interface is formed by chemical vapor deposition of zirconia compounds onto the porous electrodes to provide a dense, smooth surface on which to continue the growth of the defect-free electrolyte, whereby a single fuel cell or multiple cells may be fabricated. 8 figs.

Hybrid deposition of thin film solid oxide fuel cells and electrolyzers

DOEpatents

Jankowski, Alan F.; Makowiecki, Daniel M.; Rambach, Glenn D.; Randich, Erik

1999-01-01

The use of vapor deposition techniques enables synthesis of the basic components of a solid oxide fuel cell (SOFC); namely, the electrolyte layer, the two electrodes, and the electrolyte-electrode interfaces. Such vapor deposition techniques provide solutions to each of the three critical steps of material synthesis to produce a thin film solid oxide fuel cell (TFSOFC). The electrolyte is formed by reactive deposition of essentially any ion conducting oxide, such as defect free, yttria stabilized zirconia (YSZ) by planar magnetron sputtering. The electrodes are formed from ceramic powders sputter coated with an appropriate metal and sintered to a porous compact. The electrolyte-electrode interface is formed by chemical vapor deposition of zirconia compounds onto the porous electrodes to provide a dense, smooth surface on which to continue the growth of the defect-free electrolyte, whereby a single fuel cell or multiple cells may be fabricated.

Hybrid deposition of thin film solid oxide fuel cells and electrolyzers

DOEpatents

Jankowski, Alan F.; Makowiecki, Daniel M.; Rambach, Glenn D.; Randich, Erik

1998-01-01

The use of vapor deposition techniques enables synthesis of the basic components of a solid oxide fuel cell (SOFC); namely, the electrolyte layer, the two electrodes, and the electrolyte-electrode interfaces. Such vapor deposition techniques provide solutions to each of the three critical steps of material synthesis to produce a thin film solid oxide fuel cell (TFSOFC). The electrolyte is formed by reactive deposition of essentially any ion conducting oxide, such as defect free, yttria stabilized zirconia (YSZ) by planar magnetron sputtering. The electrodes are formed from ceramic powders sputter coated with an appropriate metal and sintered to a porous compact. The electrolyte-electrode interface is formed by chemical vapor deposition of zirconia compounds onto the porous electrodes to provide a dense, smooth surface on which to continue the growth of the defect-free electrolyte, whereby a single fuel cell or multiple cells may be fabricated.

An Artificial Lithium Protective Layer that Enables the Use of Acetonitrile-Based Electrolytes in Lithium Metal Batteries.

PubMed

Trinh, Ngoc Duc; Lepage, David; Aymé-Perrot, David; Badia, Antonella; Dollé, Mickael; Rochefort, Dominic

2018-04-23

The resurgence of the lithium metal battery requires innovations in technology, including the use of non-conventional liquid electrolytes. The inherent electrochemical potential of lithium metal (-3.04 V vs. SHE) inevitably limits its use in many solvents, such as acetonitrile, which could provide electrolytes with increased conductivity. The aim of this work is to produce an artificial passivation layer at the lithium metal/electrolyte interface that is electrochemically stable in acetonitrile-based electrolytes. To produce such a stable interface, the lithium metal was immersed in fluoroethylene carbonate (FEC) to generate a passivation layer via the spontaneous decomposition of the solvent. With this passivation layer, the chemical stability of lithium metal is shown for the first time in 1 m LiPF 6 in acetonitrile. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thin films as a platform for understanding the conversion mechanism of FeF2 cathodes in lithium-ion microbatteries

NASA Astrophysics Data System (ADS)

Santos-Ortiz, Reinaldo

Conversion material electrodes such as FeF2 possess the potential to deliver transformative improvements in lithium ion battery performance because they permit a reversible change of more than one Li-ion per 3d metal cation. They outperform current state of the art intercalation cathodes such as LiCoO2, which have volumetric and gravimetric energy densities that are intrinsically limited by single electron transfer. Current studies focus on composite electrodes that are formed by mixing with carbon (FeF 2-C), wherein the carbon is expected to act as a binder to support the matrix and facilitate electronic conduction. These binders complicate the understanding of the electrode-electrolyte interface (SEI) passivation layer growth, of Li agglomeration, of ion and electron transport, and of the basic phase transformation processes under electrochemical cycling. This research uses thin-films as a model platform for obtaining basic understanding to the structural and chemical foundations of the phase conversion processes. Thin film cathodes are free of the binders used in nanocomposite structures and may potentially provide direct basic insight to the evolution of the SEI passivation layer, electron and ion transport, and the electrochemical behavior of true complex phases. The present work consisted of three main tasks (1) Development of optimized processes to deposit FeF2 and LiPON thin-films with the required phase purity and microstructure; (2) Understanding their electron and ion transport properties and; (3) Obtaining insight to the correlation between structure and capacity in thin-film microbatteries with FeF2 thin-film cathode and LiPON thin-film solid electrolyte. Optimized pulsed laser deposition (PLD) growth produced polycrystalline FeF2 films with excellent phase purity and P42/mnm crystallographic symmetry. A schematic band diagram was deduced using a combination of UPS, XPS and UV-Vis spectroscopies. Room temperature Hall measurements reveal that as-deposited FeF2 is n-type with an electron mobility of 0.33 cm 2/V.s and a resistivity was 0.255 O.cm. The LiPON films were deposited by reactive sputtering in nitrogen, and the results indicate that the ionic conductivity is dependent on the amount of nitrogen incorporated into the film during processing. The highest ionic conductivity obtained was 1.431.9E-6 Scm-1 and corresponded to a chemical composition of Li1.9PO3.3N.21.

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.

From Two-Phase to Three-Phase: The New Electrochemical Interface by Oxide Electrocatalysts

NASA Astrophysics Data System (ADS)

Xu, Zhichuan J.

2018-03-01

Electrochemical reactions typically occur at the interface between a solid electrode and a liquid electrolyte. The charge exchange behaviour between these two phases determines the kinetics of electrochemical reactions. In the past few years, significant advances have been made in the development of metal oxide electrocatalysts for fuel cell and electrolyser reactions. However, considerable gaps remain in the fundamental understanding of the charge transfer pathways and the interaction between the metal oxides and the conducting substrate on which they are located. In particular, the electrochemical interfaces of metal oxides are significantly different from the traditional (metal) ones, where only a conductive solid electrode and a liquid electrolyte are considered. Oxides are insulating and have to be combined with carbon as a conductive mediator. This electrode configuration results in a three-phase electrochemical interface, consisting of the insulating oxide, the conductive carbon, and the liquid electrolyte. To date, the mechanistic insights into this kind of non-traditional electrochemical interface remain unclear. Consequently conventional electrochemistry concepts, established on classical electrode materials and their two-phase interfaces, are facing challenges when employed for explaining these new electrode materials. [Figure not available: see fulltext.

Method of measuring interface area of activated carbons in condensed phase

NASA Astrophysics Data System (ADS)

Dmitriyev, D. S.; Agafonov, D. V.; Kiseleva, E. A.; Mikryukova, M. A.

2018-01-01

In this work, we investigated the correlation between the heat of wetting of super-capacitor electrode material (activated carbon) with condensed phases (electrolytes based on homologous series of phosphoric acid esters) and the capacity of the supercapacitor. The surface area of the electrode-electrolyte interface was calculated according to the obtained correlations using the conventional formula for calculating the capacitance of a capacitor.

Suppressed Sr segregation and performance of directly assembled La0.6Sr0.4Co0.2Fe0.8O3-δ oxygen electrode on Y2O3-ZrO2 electrolyte of solid oxide electrolysis cells

NASA Astrophysics Data System (ADS)

Ai, Na; He, Shuai; Li, Na; Zhang, Qi; Rickard, William D. A.; Chen, Kongfa; Zhang, Teng; Jiang, San Ping

2018-04-01

Active and stable oxygen electrode is probably the most important in the development of solid oxide electrolysis cells (SOECs) technologies. Herein, we report the successful development of mixed ionic and electronic conducting (MIEC) La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) perovskite oxides directly assembled on barrier-layer-free yttria-stabilized zirconia (YSZ) electrolyte as highly active and stable oxygen electrodes of SOECs. Electrolysis polarization effectively induces the formation of electrode/electrolyte interface, similar to that observed under solid oxide fuel cell (SOFC) operation conditions. However, in contrast to the significant performance decay under SOFC operation conditions, the cell with directly assembled LSCF oxygen electrodes shows excellent stability, tested for 300 h at 0.5 A cm-2 and 750 °C under SOEC operation conditions. Detailed microstructure and phase analysis reveal that Sr segregation is inevitable for LSCF electrode, but anodic polarization substantially suppresses Sr segregation and migration to the electrode/electrolyte interface, leading to the formation of stable and efficient electrode/electrolyte interface for water and CO2 electrolysis under SOECs operation conditions. The present study demonstrates the feasibility of using directly assembled MIEC cobaltite based oxygen electrodes on barrier-layer-free YSZ electrolyte of SOECs.

Two types of diffusions at the cathode/electrolyte interface in IT-SOFCs

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

Li Zhipeng, E-mail: LI.Zhipeng@nims.go.jp; Mori, Toshiyuki; Auchterlonie, Graeme John

2011-09-15

Analytical transmission electron microscopy, in particular with the combination of energy dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS), has been performed to investigate the microstructure and microchemistry of the interfacial region between the cathode (La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3}, LSCF) and the electrolyte (Gd-doped ceria, GDC). Two types of diffusions, mutual diffusion between cathode and electrolyte as well as the diffusion along grain boundaries, have been clarified. These diffusions suggest that the chemical stability of LSCF and GDC are not as good as previously reported. The results are more noteworthy if we take into consideration the factmore » that such interdiffusions occur even during the sintering process of cell preparation. - Graphical Abstract: Two types of diffusions, the mutual diffusion and the diffusion along grain boundaries, occurred at the cathode/electrolyte interface of intermediate temperature solid state fuel cells, during cell preparation. The mutual diffusion is denoted by black arrows and the diffusion along grain boundaries assigned by pink arrows. Highlights: > All the cations in cathode (LSCF) and electrolyte (GDC) can mutually diffuse into each other. > Diffusing elements will segregate at grain boundaries or triple junctions around the cathode/electrolyte interface. > Two types of diffusions, the mutual diffusion and diffusion along grain boundaries, have been clarified thereafter.« less

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.

Thermal abuse performance of high-power 18650 Li-ion cells

NASA Astrophysics Data System (ADS)

Roth, E. P.; Doughty, D. H.

High-power 18650 Li-ion cells have been developed for hybrid electric vehicle applications as part of the DOE Advanced Technology Development (ATD) program. The thermal abuse response of two advanced chemistries (Gen1 and Gen2) were measured and compared with commercial Sony 18650 cells. Gen1 cells consisted of an MCMB graphite based anode and a LiNi 0.85Co 0.15O 2 cathode material while the Gen2 cells consisted of a MAG10 anode graphite and a LiNi 0.80Co 0.15 Al 0.05O 2 cathode. Accelerating rate calorimetry (ARC) and differential scanning calorimetry (DSC) were used to measure the thermal response and properties of the cells and cell materials up to 400 °C. The MCMB graphite was found to result in increased thermal stability of the cells due to more effective solid electrolyte interface (SEI) formation. The Al stabilized cathodes were seen to have higher peak reaction temperatures that also gave improved cell thermal response. The effects of accelerated aging on cell properties were also determined. Aging resulted in improved cell thermal stability with the anodes showing a rapid reduction in exothermic reactions while the cathodes only showed reduced reactions after more extended aging.

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.

Effects of Surface Oxygen on the Performance of Carbon as an Anode in Lithium-Ion Batteries

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh; Clark, Gregory W.

2001-01-01

Carbon materials with similar bulk structure but different surface oxygen were compared for their performance as anodes in lithium-ion battery. The bulk structure was such that the graphene planes were perpendicular to the surface. Three types of surfaces were examined: surface containing C=O type oxygen. surface containing -O-C type oxygen, and surface containing high concentration of active sites. The test involved cycles of lithium insertion into and release from the carbon materials, which was in the half cells of carbon/saturated LiI-50/50 (vol %) EC and DMC/lithium. During the first cycle of lithium insertion, the presence of adsorbed oxygen, -O-C type oxygen, active carbon sites, and C=O type oxygen resulted in the formation of solid-electrolyte interface (SEI) when the carbon's voltage relative to lithium metal was >1.35, 1 to 1.35, 0.5 to 1, and 0.67 to 0.7 V, respectively. An optimum -O-C type oxygen and a minimum C=O type oxygen was found to increase the reversible and decrease the irreversible capacity of carbon. Active sites on the carbon surface result in a large irreversible capacity and a second lithium insertion-release mechanism. However, this new mechanism has a short cycle life.

Atomic and Molecular Layer Deposition for Enhanced Lithium Ion Battery Electrodes and Development of Conductive Metal Oxide/Carbon Composites

NASA Astrophysics Data System (ADS)

Travis, Jonathan

The performance and safety of lithium-ion batteries (LIBs) are dependent on interfacial processes at the positive and negative electrodes. For example, the surface layers that form on cathodes and anodes are known to affect the kinetics and capacity of LIBs. Interfacial reactions between the electrolyte and the electrodes are also known to initiate electrolyte combustion during thermal runaway events that compromise battery safety. Atomic layer deposition (ALD) and molecular layer deposition (MLD) are thin film deposition techniques based on sequential, self-limiting surface reactions. ALD and MLD can deposit ultrathin and conformal films on high aspect ratio and porous substrates such as composite particulate electrodes in lithium-ion batteries. The effects of electrode surface modification via ALD and MLD are studied using a variety of techniques. It was found that sub-nm thick coatings of Al2O 3 deposited via ALD have beneficial effects on the stability of LIB anodes and cathodes. These same Al2O3 ALD films were found to improve the safety of graphite based anodes through prevention of exothermic solid electrolyte interface (SEI) degradation at elevated temperatures. Ultrathin and conformal metal alkoxide polymer films known as "metalcones" were grown utilizing MLD techniques with trimethylaluminum (TMA) or titanium tetrachloride (TiCl4) and organic diols or triols, such as ethylene glycol (EG), glycerol (GL) or hydroquinone (HQ), as the reactants. Pyrolysis of these metalcone films under inert gas conditions led to the development of conductive metal oxide/carbon composites. The composites were found to contain sp2 carbon using micro-Raman spectroscopy in the pyrolyzed films with pyrolysis temperatures ≥ 600°C. Four point probe measurements demonstrated that the graphitic sp2 carbon domains in the metalcone films grown using GL and HQ led to significant conductivity. The pyrolysis of conformal MLD films to obtain conductive metal oxide/carbon composite films is presented as a method for enabling non-conductive, but possibly electrochemically active materials, to be used for electrochemical applications.

On the Suitability of Tcl/Tk for SYS

DTIC Science & Technology

2003-02-01

database design, or user interface. CMU/SEI-2003-TN-001 7 4.4 Legacy Systems SYS is not now complete. The system it replaced interfaced with a dozen...a database maintained by a parent organization. Before SYS was released, many of its current users interacted directly with JSYS, so that system...rating. Rather than shades of blue, the full rainbow is exploited. Rather than window proliferation, the usual result of an action is to replace the

Interfacial strain effects on lithium diffusion pathways in the spinel solid electrolyte Li-doped MgAl2O4

NASA Astrophysics Data System (ADS)

O'Rourke, Conn; Morgan, Benjamin J.

2018-04-01

The (Li,Al)-codoped magnesium spinel (LixMg1 -2 xAl2 +xO4 ) is a solid lithium-ion electrolyte with potential use in all-solid-state lithium-ion batteries. The spinel structure means that interfaces with spinel electrodes, such as LiyMn2O4 and Li4 +3 zTi5O12 , may be lattice matched, with potentially low interfacial resistances. Small lattice parameter differences across a lattice-matched interface are unavoidable, causing residual epitaxial strain. This strain potentially modifies lithium diffusion near the electrolyte-electrode interface, contributing to interfacial resistance. Here, we report a density functional theory study of strain effects on lithium diffusion pathways for (Li,Al)-codoped magnesium spinel, for xLi=0.25 and xLi=0.5 . We have calculated diffusion profiles for the unstrained materials, and for isotropic and biaxial tensile strains of up to 6 % , corresponding to {100 } epitaxial interfaces with LiyMn2O4 and Li4 +3 zTi5O12 . We find that isotropic tensile strain reduces lithium diffusion barriers by as much as 0.32 eV , with typical barriers reduced by ˜0.1 eV. This effect is associated with increased volumes of transitional octahedral sites, and broadly follows qualitative changes in local electrostatic potentials. For biaxial (epitaxial) strain, which more closely approximates strain at a lattice-matched electrolyte-electrode interface, changes in octahedral site volumes and in lithium diffusion barriers are much smaller than under isotropic strain. Typical barriers are reduced by only ˜0.05 eV. Individual effects, however, depend on the pathway considered and the relative strain orientation. These results predict that isotropic strain strongly affects ionic conductivities in (Li,Al)-codoped magnesium spinel electrolytes, and that tensile strain is a potential route to enhanced lithium transport. For a lattice-matched interface with candidate spinel-structured electrodes, however, epitaxial strain has a small, but complex, effect on lithium diffusion barriers.

The impact of alkyl sulfate surfactant geometry and electrolyte on the co-adsorption of anionic surfactants with model perfumes at the air-solution interface.

PubMed

Bradbury, Robert; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Jones, Craig

2013-08-01

The impact of surfactant geometry and electrolyte on the co-adsorption of anionic surfactants and model perfumes at the air-solution interface has been studied by neutron reflectivity. The more hydrophobic perfume linalool, competes more favourably for the surface with sodium dodecylsulfate than was previously reported for the anionic surfactant, sodium dodecyl 6-benzenesulfonate. Due to an increase in surface activity of the sodium dodecylsulfate, the addition of electrolyte results in a reduction in the linalool adsorption. Changing the alkyl chain length affects the relative adsorption of linalool and surfactant at the interface. Similar measurements for the different alkyl sulfates and with electrolyte with the more hydrophilic perfume phenyl ethanol, reveal broadly similar trends. Although the relative adsorption of phenyl ethanol with sodium dodecylsulfate is substantially enhanced compared to sodium dodecyl-6-benzenesulfonate the effects are not as significant as was observed with linalool. The variations with alkyl chain geometry show the importance of the hydrophobic interaction between the perfume and surfactant and changes in the packing constraints on the relative adsorption. The results highlight the importance of the specific interaction between the surfactant and perfume, and the surfactant and perfume geometries on the relative adsorption at the interface. Copyright © 2013 Elsevier Inc. All rights reserved.

A long life 4 V class lithium-ion polymer battery with liquid-free polymer electrolyte

NASA Astrophysics Data System (ADS)

Kobayashi, Yo; Shono, Kumi; Kobayashi, Takeshi; Ohno, Yasutaka; Tabuchi, Masato; Oka, Yoshihiro; Nakamura, Tatsuya; Miyashiro, Hajime

2017-02-01

Ether-based solid polymer electrolyte (SPE) is one of the most well-known lithium ion conductors. Unlike the other inorganic electrolytes, SPE exhibits advantages of flexibility and large-area production, enabling low cost production of large size batteries. However, because the ether group is oxidized at 4 V versus Li/Li+ cathode, and due to its high irreversibility with the carbon anode, ether-based SPE was believed to be inapplicable to 4 V class lithium-ion batteries with carbon anode. Here we report a remarkably stable SPE in combination with a 4 V class cathode and carbon anode achieved by the proper design at the interface. The introduced boron-based lithium salt prohibits further oxidation of SPE at the cathode interface. The surface modification of graphite by the annealing of polyvinyl chloride mostly prohibits the continuous consumption of lithium at the graphite anode. Using above interface design, we achieved 60% capacity retention after 5400 cycles. The proposed battery provides a possible approach for realizing flammable electrolyte-free lithium-ion batteries, which achieve innovative safety improvements of large format battery systems for stationary use.

Prelude: The renaissance of electrocatalysis

DOE PAGES

Shao, Yuyan; Markovic, Nenad M.

2016-09-16

Recent improvements in the fundamental understanding of the behavior of electrochemical interfaces in aqueous electrolytes have begun a revolution in the field of electrocatalysis, enabling the design of interfaces tailored to the efficient breaking and making of specific chemical bonds, as well as providing insight into the redistribution of the electrons that are associated with these transformations. We intentionally emphasize the importance of electrochemical interfaces, rather than electrode materials, because contemporary electrocatalysis goes well beyond the design and synthesis of materials. Rather, it has become the science of electrode processes, where the reaction rates have a strong dependence on themore » nature of both the electrode material as well as the electrolyte, i.e., solvated ions in the vicinity (~0.3 nm) of the electrode. Lastly, although understanding the role of electrolyte components introduces an additional level of complexity, this very same complexity has led to a new wave of discovery and will provide the knowledge required to move beyond the current generation of materials and electrolytes and shape the future of alternative energy sources that are key to delivering energy security and protecting the environment.« less

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

InGaN/GaN quantum dots as optical probes for the electric field at the GaN/electrolyte interface

NASA Astrophysics Data System (ADS)

Teubert, J.; Koslowski, S.; Lippert, S.; Schäfer, M.; Wallys, J.; Dimitrakopulos, G.; Kehagias, Th.; Komninou, Ph.; Das, A.; Monroy, E.; Eickhoff, M.

2013-08-01

We investigated the electric-field dependence of the photoluminescence-emission properties of InGaN/GaN quantum dot multilayers in contact with an electrolyte. Controlled variations of the surface potential were achieved by the application of external electric fields using the electrolytic Schottky contact and by variation of the solution's pH value. Prior to characterization, a selective electrochemical passivation process was required to suppress leakage currents. The quantum dot luminescence is strongly affected by surface potential variations, i.e., it increases exponentially with cathodic bias and acidic pH values. The results cannot be explained by a modification of intra-dot polarization induced electric fields via the quantum confined Stark effect but are attributed to the suppression/enhancement of non-radiative recombination processes, i.e., mainly hole transfer into the electrolyte. The results establish a link between the photoluminescence intensity and the magnitude of electric fields at the semiconductor/electrolyte interface.

Nanoclay gelation approach toward improved dye-sensitized solar cell efficiencies: an investigation of charge transport and shift in the TiO2 conduction band.

PubMed

Wang, Xiu; Kulkarni, Sneha A; Ito, Bruno Ieiri; Batabyal, Sudip K; Nonomura, Kazuteru; Wong, Chee Cheong; Grätzel, Michael; Mhaisalkar, Subodh G; Uchida, Satoshi

2013-01-23

Nanoclay minerals play a promising role as additives in the liquid electrolyte to form a gel electrolyte for quasi-solid-state dye-sensitized solar cells, because of the high chemical stability, unique swelling capability, ion exchange capacity, and rheological properties of nanoclays. Here, we report the improved performance of a quasi-solid-state gel electrolyte that is made from a liquid electrolyte and synthetic nitrate-hydrotalcite nanoclay. Charge transport mechanisms in the gel electrolyte and nanoclay interactions with TiO(2)/electrolyte interface are discussed in detail. The electrochemical analysis reveals that the charge transport is solely based on physical diffusion at the ratio of [PMII]:[I(2)] = 10:1 (where PMII is 1-propyl-3-methylimidazolium iodide). The calculated physical diffusion coefficient shows that the diffusion of redox ions is not affected much by the viscosity of nanoclay gel. The addition of nitrate-hydrotalcite clay in the electrolyte has the effect of buffering the protonation process at the TiO(2)/electrolyte interface, resulting in an upward shift in the conduction band and a boost in open-circuit voltage (V(OC)). Higher V(OC) values with undiminished photocurrent is achieved with nitrate-hydrotalcite nanoclay gel electrolyte for organic as well as for inorganic dye (D35 and N719) systems. The efficiency for hydrotalcite clay gel electrolyte solar cells is increased by 10%, compared to that of the liquid electrolyte. The power conversion efficiency can reach 10.1% under 0.25 sun and 9.6% under full sun. This study demonstrates that nitrate-hydrotalcite nanoclay in the electrolyte not only solidifies the liquid electrolyte to prevent solvent leakage, but also facilitates the improvement in cell efficiency.

Ionic Liquid Hybrid Electrolytes for Lithium-Ion Batteries: A Key Role of the Separator-Electrolyte Interface in Battery Electrochemistry.

PubMed

Huie, Matthew M; DiLeo, Roberta A; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

2015-06-10

Batteries are multicomponent systems where the theoretical voltage and stoichiometric electron transfer are defined by the electrochemically active anode and cathode materials. While the electrolyte may not be considered in stoichiometric electron-transfer calculations, it can be a critical factor determining the deliverable energy content of a battery, depending also on the use conditions. The development of ionic liquid (IL)-based electrolytes has been a research area of recent reports by other researchers, due, in part, to opportunities for an expanded high-voltage operating window and improved safety through the reduction of flammable solvent content. The study reported here encompasses a systematic investigation of the physical properties of IL-based hybrid electrolytes including quantitative characterization of the electrolyte-separator interface via contact-angle measurements. An inverse trend in the conductivity and wetting properties was observed for a series of IL-based electrolyte candidates. Test-cell measurements were undertaken to evaluate the electrolyte performance in the presence of functioning anode and cathode materials, where several promising IL-based hybrid electrolytes with performance comparable to that of conventional carbonate electrolytes were identified. The study revealed that the contact angle influenced the performance more significantly than the conductivity because the cells containing IL-tetrafluoroborate-based electrolytes with higher conductivity but poorer wetting showed significantly decreased performance relative to the cells containing IL-bis(trifluoromethanesulfonyl)imide electrolytes with lower conductivity but improved wetting properties. This work contributes to the development of new IL battery-based electrolyte systems with the potential to improve the deliverable energy content as well as safety of lithium-ion battery systems.

Tunable Molecular-Scale Materials for Catalyzing the Low-Overpotential Electrochemical Conversion of CO2.

PubMed

Rosen, Brian A; Hod, Idan

2018-04-25

Electrochemical CO 2 reduction provides a clean and viable alternative for mitigating the environmental aspects of global greenhouse gas emissions. To date, the simultaneous goals of CO 2 reduction at high selectivity and activity have yet to be achieved. Here, the importance of engineering both sides of the electrode-electrolyte interface as a rational strategy for achieving this milestone is highlighted. An emphasis is placed on researchers contributing to the design of solid electrodes based on metal-organic frameworks (MOFs) and electrolytes based on room-temperature ionic liquids (RTILs). Future research geared toward optimizing the electrode-electrolyte interface for efficient and selective CO 2 reduction can be achieved by understanding the structure of newly designed RTILs at the electrified interface, as well as structure-activity relationships in highly tunable MOF platforms. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gas-liquid interface of room-temperature ionic liquids.

PubMed

Santos, Cherry S; Baldelli, Steven

2010-06-01

The organization of ions at the interface of ionic liquids and the vacuum is an ideal system to test new ideas and concepts on the interfacial chemistry of electrolyte systems in the limit of no solvent medium. Whilst electrolyte systems have numerous theoretical and experimental methods used to investigate their properties, the ionic liquids are relatively new and our understanding of the interfacial properties is just beginning to be explored. In this critical review, the gas-liquid interface is reviewed, as this interface does not depend on the preparation of another medium and thus produces a natural interface. The interface has been investigated by sum frequency generation vibrational spectroscopy and ultra-high vacuum techniques. The results provide a detailed molecular-level view of the surface composition and structure. These have been complemented by theoretical studies. The combinations of treatments on this interface are starting to provide a somewhat convergent description of how the ions are organized at this neat interface (108 references).

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.

Non-Faradaic Li + Migration and Chemical Coordination across Solid-State Battery Interfaces

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

Gittleson, Forrest S.; El Gabaly, Farid

Efficient and reversible charge transfer is essential to realizing high-performance solid-state batteries. Efforts to enhance charge transfer at critical electrode–electrolyte interfaces have proven successful, yet interfacial chemistry and its impact on cell function remains poorly understood. Using X-ray photoelectron spectroscopy combined with electrochemical techniques, we elucidate chemical coordination near the LiCoO 2–LIPON interface, providing experimental validation of space-charge separation. Space-charge layers, defined by local enrichment and depletion of charges, have previously been theorized and modeled, but the unique chemistry of solid-state battery interfaces is now revealed. Here we highlight the non-Faradaic migration of Li+ ions from the electrode to themore » electrolyte, which reduces reversible cathodic capacity by ~15%. Inserting a thin, ion-conducting LiNbO 3 interlayer between the electrode and electrolyte, however, can reduce space-charge separation, mitigate the loss of Li+ from LiCoO 2, and return cathodic capacity to its theoretical value. This work illustrates the importance of interfacial chemistry in understanding and improving solid-state batteries.« 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.

Self-Assembled Polymeric Ionic Liquid-Functionalized Cellulose Nano-crystals: Constructing 3D Ion-conducting Channels Within Ionic Liquid-based Composite Polymer Electrolytes.

PubMed

Shi, Qing Xuan; Xia, Qing; Xiang, Xiao; Ye, Yun Sheng; Peng, Hai Yan; Xue, Zhi Gang; Xie, Xiao Lin; Mai, Yiu-Wing

2017-09-04

Composite polymeric and ionic liquid (IL) electrolytes are some of the most promising electrolyte systems for safer battery technology. Although much effort has been directed towards enhancing the transport properties of polymer electrolytes (PEs) through nanoscopic modification by incorporating nano-fillers, it is still difficult to construct ideal ion conducting networks. Here, a novel class of three-dimensional self-assembled polymeric ionic liquid (PIL)-functionalized cellulose nano-crystals (CNC) confining ILs in surface-grafted PIL polymer chains, able to form colloidal crystal polymer electrolytes (CCPE), is reported. The high-strength CNC nano-fibers, decorated with PIL polymer chains, can spontaneously form three-dimensional interpenetrating nano-network scaffolds capable of supporting electrolytes with continuously connected ion conducting networks with IL being concentrated in conducting domains. These new CCPE have exceptional ionic conductivities, low activation energies (close to bulk IL electrolyte with dissolved Li salt), high Li + transport numbers, low interface resistances and improved interface compatibilities. Furthermore, the CCPE displays good electrochemical properties and a good battery performance. This approach offers a route to leak-free, non-flammable and high ionic conductivity solid-state PE in energy conversion devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Energetics of the Semiconductor-Electrolyte Interface.

ERIC Educational Resources Information Center

Turner, John A.

1983-01-01

The use of semiconductors as electrodes for electrochemistry requires an understanding of both solid-state physics and electrochemistry, since phenomena associated with both disciplines are seen in semiconductor/electrolyte systems. The interfacial energetics of these systems are discussed. (JN)

Effect of the Anion Activity on the Stability of Li Metal Anodes in Lithium-Sulfur Batteries

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

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

2016-03-29

With the significant progress made in the development of cathodes in lithium-sulfur (Li-S) batteries, the stability of Li metal anodes becomes a more urgent challenge in these batteries. Here we report the systematic investigation of the stability of the anode/electrolyte interface in Li-S batteries with concentrated electrolytes containing various lithium salts. It is found that Li-S batteries using LiTFSI-based electrolytes are more stable than those using LiFSI-based electrolytes. The decreased stability is because the N-S bond in the FSI- anion is fairly weak and the scission of this bond leads to the formation of lithium sulfate (LiSOx) in the presencemore » of polysulfide species. In contrast, even the weakest bond (C-S) in the TFSI- anion is stronger than the N-S bond in the FSI- anion. In the LiTFSI-based electrolyte, the lithium metal anode tends to react with polysulfide to form lithium sulfide (LiSx) which is more reversible than LiSOx formed in the LiTFSI-based electrolyte. This fundamental difference in the bond strength of the salt anions in the presence of polysulfide species leads to a large difference in the stability of the anode-electrolyte interface and performance of the Li-S batteries with electrolytes composed of these salts. Therefore, anion selection is one of the key parameters in the search for new electrolytes for stable operation of Li-S batteries.« 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.

Effect of La0.6 Sr0.4 Co0.2 Fe0.8O3 - δ air electrode-electrolyte interface on the short-term stability under high-current electrolysis in solid oxide electrolyzer cells

NASA Astrophysics Data System (ADS)

Pan, Zehua; Liu, Qinglin; Lyu, Renzhi; Li, Ping; Chan, Siew Hwa

2018-02-01

In this work, the effects of the La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) electrode-yttria stabilized zirconia (YSZ) electrolyte interface on the stability of LSCF electrodes under high-current electrolysis are studied. Six different half-cells with different configurations are tested at 800 °C for 264 h under an electrolysis current of 1 A cm-2. A few concluding remarks can be drawn by comparing the behaviors of different cells. Firstly, it is confirmed that the formation of SrZrO3 at the interface will lead to the delamination of air electrode. Thus, the formation of SrZrO3 should be strictly prevented. Secondly, increasing sintering temperature can decrease the degradation rate of polarization resistance, RP, for LSCF electrodes. Thirdly, the increase of ohmic resistance, RS, comes from structural changes as the degradation rate in percentage is similar for cells with different electrolytes and electrodes. Fourthly, the LSCF electrode after the electrolysis test shows recrystallization and lattice shrink which could be the reason for the degradation of LSCF electrodes on Gd0.1Ce0.9O2-δ (GDC) electrolytes. Lastly, comparing all the samples, the cell composed of YSZ electrolyte, dense GDC interlayer and LSCF electrode sintered at 1000 °C can be used for future study on the degradation mechanisms of the LSCF air electrode and the electrolyte.

Argonne Chemical Sciences & Engineering - Center for Electrical Energy

Science.gov Websites

electrodes at the SEI interface, Li-ion batteries show limited calendar and cycle life--less than 2 years energy storage requirements. The CEES will focus on lithium batteries, as they offer the best opportunity of Argonne's Applied Battery Research and Development Program. EFRCs at Argonne The Center for

Direct liquid-feed fuel cell with membrane electrolyte and manufacturing thereof

NASA Technical Reports Server (NTRS)

Narayanan, Sekharipuram (Inventor); Surampudi, Subbarao (Inventor); Halpert, Gerald (Inventor)

1999-01-01

An improved direct liquid-feed fuel cell having a solid membrane electrolyte for electrochemical reactions of an organic fuel. Improvements in interfacing of the catalyst layer and the membrane and activating catalyst materials are disclosed.

Yttria-stabilized zirconia solid oxide electrolyte fuel cells: Monolithic solid oxide fuel cells

NASA Astrophysics Data System (ADS)

1990-10-01

The monolithic solid oxide fuel cell (MSOFC) is currently under development for a variety of applications including coal-based power generation. The MSOFC is a design concept that places the thin components of a solid oxide fuel cell in lightweight, compact, corrugated structure, and so achieves high efficiency and excellent performance simultaneously with high power density. The MSOFC can be integrated with coal gasification plants and is expected to have high overall efficiency in the conversion of the chemical energy of coal to electrical energy. This report describes work aimed at: (1) assessing manufacturing costs for the MSOFC and system costs for a coal-based plant; (2) modifying electrodes and electrode/electrolyte interfaces to improve the electrochemical performance of the MSOFC; and (3) testing the performance of the MSOFC on hydrogen and simulated coal gas. Manufacturing costs for both the coflow and crossflow MSOFC's were assessed based on the fabrication flow charts developed by direct scaleup of tape calendering and other laboratory processes. Integrated coal-based MSOFC systems were investigated to determine capital costs and costs of electricity. Design criteria were established for a coal-fueled 200-Mw power plant. Four plant arrangements were evaluated, and plant performance was analyzed. Interfacial modification involved modification of electrodes and electrode/electrolyte interfaces to improve the MSOFC electrochemical performance. Work in the cathode and cathode/electrolyte interface was concentrated on modification of electrode porosity, electrode morphology, electrode material, and interfacial bonding. Modifications of the anode and anode/electrolyte interface included the use of additives and improvement of nickel distribution. Single cells have been tested for their electrochemical performance. Performance data were typically obtained with humidified H2 or simulated coal gas and air or oxygen.

Monolithic All-Phosphate Solid-State Lithium-Ion Battery with Improved Interfacial Compatibility.

PubMed

Yu, Shicheng; Mertens, Andreas; Tempel, Hermann; Schierholz, Roland; Kungl, Hans; Eichel, Rüdiger-A

2018-06-22

High interfacial resistance between solid electrolyte and electrode of ceramic all-solid-state batteries is a major reason for the reduced performance of these batteries. A solid-state battery using a monolithic all-phosphate concept based on screen printed thick LiTi 2 (PO 4 ) 3 anode and Li 3 V 2 (PO 4 ) 3 cathode composite layers on a densely sintered Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 solid electrolyte has been realized with competitive cycling performance. The choice of materials was primarily based on the (electro-)chemical and mechanical matching of the components instead of solely focusing on high-performance of individual components. Thus, the battery utilized a phosphate backbone in combination with tailored morphology of the electrode materials to ensure good interfacial matching for a durable mechanical stability. Moreover, the operating voltage range of the active materials matches with the intrinsic electrochemical window of the electrolyte which resulted in high electrochemical stability. A highly competitive discharge capacity of 63.5 mAh g -1 at 0.39 C after 500 cycles, corresponding to 84% of the initial discharge capacity, was achieved. The analysis of interfacial charge transfer kinetics confirmed the structural and electrical properties of the electrodes and their interfaces with the electrolyte, as evidenced by the excellent cycling performance of the all-phosphate solid-state battery. These interfaces have been studied via impedance analysis with subsequent distribution of relaxation times analysis. Moreover, the prepared solid-state battery could be processed and operated in air atmosphere owing to the low oxygen sensitivity of the phosphate materials. The analysis of electrolyte/electrode interfaces after cycling demonstrates that the interfaces remained stable during cycling.

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

Smalley, John F.

In this study, we demonstrate how small and rapid temperature perturbations (produced by the indirect laser-induced temperature jump (ILIT) technique) of solid metal electrode|electrolyte solution interfaces may be used to determine the potential of zero (total) charge (E pzc) and its temperature derivativemore » $$\\left(\\frac{dEpzc}{dT}\\right)$$ of Au(111) electrode surfaces modified by alkanethiol self-assembled monolayers in contact with high ionic strength (i.e., 1.0 M) aqueous electrolyte solutions. The E pzc’s measured for two different types of SAMs (made from either HS(CH 2) n-1CH 3 (5 ≤ n ≤ 12, E pzc = -(0.99 ± 0.12) V vs SSCE) or HS(CH 2) nOH (3 ≤ n ≤ 16, E pzc = (0.46 ± 0.22) V vs SSCE)) are considerably different than those measured previously at much lower electrolyte solution ionic strengths. For mixed monolayers made from both HS(CH 2) n-1CH 3 and HS(CH 2) nFc (where Fc refers to ferrocene), the difference in Epzc decreases as a function of the surface concentration of the Fc moiety (i.e., [Fc]), and it completely disappears at a surprisingly small [Fc] (~4.0 × 10 –11 mol cm –2). These observations for the Au(111)|hydrophobic (neat and mixed) SAM|aqueous electrolyte solution interfaces, along with the surface potentials (g Sml(dip)) evaluated for the contacting electrolyte solution surfaces of these interfaces, are consistent with a structure for the water molecule components of these surfaces where there is a net orientation of the dipoles of these molecules. Accordingly, the negative (oxygen) ends of these molecules point toward the SAM surface. The positive values of g Sml(dip) evaluated for hydrophilic SAM (e.g., made from HS(CH 2) nOH)|aqueous electrolyte solution interfaces) also indicate that the structure of these interfaces is similar to that of the hydrophobic interfaces. However, g Sml(dip) decreases with increasing ionic strength for the hydrophilic interfaces, while it increases with increasing ionic strength for the hydrophobic interfaces. The data (and calculations) reported in the present work and other studies of hydrophobic (and hydrophilic)|aqueous solution interfaces are as yet insufficient to support a complete explanation for the effects of ionic strength observed in the present study. Nevertheless, an analysis based upon the value of $$\\left(\\frac{dEpzc}{dT}\\right)$$ (= (0.51 ± 0.12) mV/K, essentially the same for SAMs made from both HS(CH 2) n-1CH 3 and HS(CH 2) nOH), determined in the present study provides a further indication that upon formation of the SAM there is a partial charge transfer of electrons from the relevant gold atoms on the Au(111) surface to the sulfur atoms of the alkanethiols.« less

Mitigation of the irreversible capacity and electrolyte decomposition in a LiNi 0.5Mn 1.5O 4/nano-TiO 2 Li-ion battery

NASA Astrophysics Data System (ADS)

Brutti, Sergio; Gentili, Valentina; Reale, Priscilla; Carbone, Lorenzo; Panero, Stefania

Nanosized titanium oxides can achieve large reversible specific capacity (above 200 mAh g -1) and good rate capabilities, but suffer irreversible capacity losses in the first cycle. Moreover, due to the intrinsic safe operating potential (1.5 V), the use of titanium oxide requires to couple it with high-potential cathodes, such as lithium nickel manganese spinel (LNMO) in order to increase the energy density of the final cell. However the use of the 4.7 V vs. Li +/Li 0 LNMO cathode material requires to tackle the continuous electrolyte decomposition upon cycling. Coupling these two electrodes to make a lithium ion battery is thus highly appealing but also highly difficult because the cell balancing must account not only for the charge reversibly exchanged by each electrode but also for the irreversible charge losses. In this paper a LNMO-nano TiO 2 Li-ion cell with liquid electrolyte is presented: two innovative approaches on both the cathode and the anode sides were developed in order to mitigate the electrolyte decomposition upon cycling. In particular the LNMO surface was coated with ZnO in order to minimize the surface reactivity, and the TiO 2 nanoparticles where activated by incorporating nano-lithium in the electrode formulation to compensate for the irreversible capacity loss in the first cycle. With these strategies we were able to assemble balanced Li-ion coin cells thus avoiding the use of electrolyte additives and more hazardous and expensive ex-situ SEI preforming chemical or electrochemical procedures.

Comparison of chitosan and chitosan nanoparticles on the performance and charge recombination of water-based gel electrolyte in dye sensitized solar cells.

PubMed

Khalili, Malihe; Abedi, Mohammad; Amoli, Hossein Salar; Mozaffari, Seyed Ahmad

2017-11-01

In commercialization of liquid dye-sensitized solar cells (DSSCs), whose leakage, evaporation and toxicity of organic solvents are limiting factors, replacement of organic solvents with water-based gel electrolyte is recommended. This work reports on utilizing and comparison of chitosan and chitosan nanoparticle as different gelling agents in preparation of water-based gel electrolyte in fabrication of dye sensitized solar cells. All photovoltaic parameters such as open circuit voltage (V oc ), fill factor (FF), short circuit current density (J sc ) and conversion efficiency (η) were measured. For further characterization, electrochemical impedance spectroscopy (EIS) was used to study the charge transfer at Pt/electrolyte interface and charge recombination and electron transport at TiO 2 /dye/electrolyte interface. Significant improvements in conversion efficiency and short circuit current density of DSSCs fabricated by chitosan nanoparticle were observed that can be attributed to the higher mobility of I 3 - due to the lower viscosity and smaller size of chitosan nanoparticles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Formation of anodic layers on InAs (111)III. Study of the chemical composition

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

Valisheva, N. A., E-mail: valisheva@thermo.isp.nsc.ru; Tereshchenko, O. E.; Prosvirin, I. P.

2012-04-15

The chemical composition of {approx}20-nm-thick anodic layers grown on InAs (111)III in alkaline and acid electrolytes containing or not containing NH{sub 4}F is studied by X-ray photoelectron spectroscopy. It is shown that the composition of fluorinated layers is controlled by the relation between the concentrations of fluorine and hydroxide ions in the electrolyte and by diffusion processes in the growing layer. Fluorine accumulates at the (anodic layer)/InAs interface. Oxidation of InAs in an acid electrolyte with a low oxygen content and a high NH{sub 4}F content brings about the formation of anodic layers with a high content of fluorine andmore » elemental arsenic and the formation of an oxygen-free InF{sub x}/InAs interface. Fluorinated layers grown in an alkaline electrolyte with a high content of O{sup 2-} and/or OH{sup -} groups contain approximately three times less fluorine and consist of indium and arsenic oxyfluorides. No distinction between the compositions of the layers grown in both types of fluorine-free electrolytes is established.« 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.

Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity

DOEpatents

Skotheim, Terje

1986-01-01

There is disclosed a polymer blend of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity

DOEpatents

Skotheim, T.

1984-09-28

There is disclosed a polymer blend of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

Film bonded fuel cell interface configuration

DOEpatents

Kaufman, Arthur; Terry, Peter L.

1985-01-01

An improved interface configuration for use between adjacent elements of a fuel cell stack. The interface is impervious to gas and liquid and provides resistance to corrosion by the electrolyte of the fuel cell. A multi-layer arrangement for the interface provides bridging electrical contact with a hot-pressed resin filling the void space.

Process for making film-bonded fuel cell interfaces

DOEpatents

Kaufman, Arthur; Terry, Peter L.

1990-07-03

An improved interface configuration for use between adjacent elements of a fuel cell stack. The interface is impervious to gas and liquid and provides resistance to corrosion by the electrolyte of the fuel cell. A multi-layer arrangement for the interface provides bridging electrical contact with a hot-pressed resin filling the void space.

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.

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.

Optimized Li-Ion Electrolytes Containing Triphenyl Phosphate as a Flame-Retardant Additive

NASA Technical Reports Server (NTRS)

Smart, Marshall C.; Bugga, Ratnakumar V.; Prakash, G. K. Surya; Krause, Frederick C.

2011-01-01

A number of future NASA missions involving the exploration of the Moon and Mars will be human-rated and thus require high-specific-energy rechargeable batteries that possess enhanced safety characteristics. Given that Li-ion technology is the most viable rechargeable energy storage device for near-term applications, effort has been devoted to improving the safety characteristics of this system. There is also a strong desire to develop Li-ion batteries with improved safety characteristics for terrestrial applications, most notably for hybrid electric vehicle (HEV) and plug-in hybrid electric vehicle (PHEV) automotive applications. Therefore, extensive effort has been devoted recently to developing non-flammable electrolytes to reduce the flammability of the cells/battery. A number of electrolyte formulations have been developed, including systems that (1) incorporate greater concentrations of the flame-retardant additive (FRA); (2) use di-2,2,2-trifluoroethyl carbonate (DTFEC) as a co-solvent; (3) use 2,2,2- trifluoroethyl methyl carbonate (TFEMC); (4) use mono-fluoroethylene carbonate (FEC) as a co-solvent and/or a replacement for ethylene carbonate in the electrolyte mixture; and (5) utilize vinylene carbonate as a "SEI promoting" electrolyte additive, to build on the favorable results previously obtained. To extend the family of electrolytes developed under previous work, a number of additional electrolyte formulations containing FRAs, most notably triphenyl phosphate (TPP), were investigated and demonstrated in experimental MCMB (mesocarbon micro beads) carbon- LiNi(0.8)Co(0.2)O2 cells. The use of higher concentrations of the FRA is known to reduce the flammability of the electrolyte solution, thus, a concentration range was investigated (i.e., 5 to 20 percent by volume). The desired concentration of the FRA is the highest amount tolerable without adversely affecting the performance in terms of reversibility, ability to operate over a wide temperature range, and the discharge rate capability. The use of fluorinated carbonates, much in the same manner as the incorporation of fluorinated ester-based solvents, was employed to reduce the inherent flammability of mixtures. Thus, electrolyte formulations that embody both approaches are anticipated to have much lower flammability, resulting in enhanced safety.

Impedance spectroscopy of tripolar concentric ring electrodes with Ten20 and TD246 pastes.

PubMed

Nasrollaholhosseini, Seyed Hadi; Herrera, Daniel Salazar; Besio, Walter G

2017-07-01

Electrodes are used to transform ionic currents to electrical currents in biological systems. Modeling the electrode-electrolyte interface could help to optimize the performance of the electrode interface to achieve higher signal to noise ratios. There are previous reports of accurate models for single-element biomedical electrodes. In this paper, we measured the impedance on both tripolar concentric ring electrodes and standard cup electrodes by electrochemical impedance spectroscopy (EIS) using both Ten20 and TD246 electrode paste. Furthermore, we applied the model to prove that the model can predict the performance of the electrode-electrolyte interface for tripolar concentric ring electrodes (TCRE) that are used to record brain signals.

Frequency-dependent learning achieved using semiconducting polymer/electrolyte composite cells

NASA Astrophysics Data System (ADS)

Dong, W. S.; Zeng, F.; Lu, S. H.; Liu, A.; Li, X. J.; Pan, F.

2015-10-01

Frequency-dependent learning has been achieved using semiconducting polymer/electrolyte composite cells. The cells composed of polymer/electrolyte double layers realized the conventional spike-rate-dependent plasticity (SRDP) learning model. These cells responded to depression upon low-frequency stimulation and to potentiation upon high-frequency stimulation and presented long-term memory. The transition threshold θm from depression to potentiation varied depending on the previous stimulations. A nanostructure resembling a bio-synapse in its transport passages was demonstrated and a random channel model was proposed to describe the ionic kinetics at the polymer/electrolyte interface during and after stimulations with various frequencies, accounting for the observed SRDP.Frequency-dependent learning has been achieved using semiconducting polymer/electrolyte composite cells. The cells composed of polymer/electrolyte double layers realized the conventional spike-rate-dependent plasticity (SRDP) learning model. These cells responded to depression upon low-frequency stimulation and to potentiation upon high-frequency stimulation and presented long-term memory. The transition threshold θm from depression to potentiation varied depending on the previous stimulations. A nanostructure resembling a bio-synapse in its transport passages was demonstrated and a random channel model was proposed to describe the ionic kinetics at the polymer/electrolyte interface during and after stimulations with various frequencies, accounting for the observed SRDP. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02891d

Flexible interfaces between Si anodes and composite electrolytes consisting of poly(propylene carbonates) and garnets for solid-state batteries

NASA Astrophysics Data System (ADS)

Huo, Hanyu; Sun, Jiyang; chen, Cheng; Meng, Xianglu; He, Minghui; Zhao, Ning; Guo, Xiangxin

2018-04-01

Flexible interfaces between Si anodes and composite electrolytes consisting of poly(propylene carbonates) (PPCs) and garnets have been fabricated. The solid polymer electrolytes (SPEs) of PPC/garnet/LiTFSI show the conductivity of 4.2 × 10-4 S cm-1 at room temperature. Their combination with the Si layer anodes allows great alleviation of internal stress resulting from the large volume variation during lithiation and delithiation process of Si anodes. As a result, the Si/SPE/Li cells exhibit 2520 mAh g-1, 2260 mAh g-1, 1902 mAh g-1, 1342 mAh g-1 at 0.1 C, 0.2 C, 0.5 C, and 1 C, respectively. Furthermore, with such compatible and stable interfaces of Si/SPE and the LiFePO4 cathodes in solid-state batteries, the specific capacity of 2296 mAh g-1 in terms of Si is obtained, which remains 82.6% after 100 cycles at room temperature and 0.1 C. The results here indicate that constructing of flexible interfaces between Si anodes and SPEs is a promising strategy to develop high performance solid-state batteries.

Direct deposit of catalyst on the membrane of direct feed fuel cells

NASA Technical Reports Server (NTRS)

Chun, William (Inventor); Narayanan, Sekharipuram R. (Inventor); Jeffries-Nakamura, Barbara (Inventor); Valdez, Thomas I. (Inventor); Linke, Juergen (Inventor)

2001-01-01

An improved direct liquid-feed fuel cell having a solid membrane electrolyte for electrochemical reactions of an organic fuel. Catalyst utilization and catalyst/membrane interface improvements are disclosed. Specifically, the catalyst layer is applied directly onto the membrane electrolyte.

Improved electrochemical performance of spinel LiMn(1.5)Ni(0.5)O4 through MgF2 nano-coating.

PubMed

Wu, Qing; Zhang, Xiaoping; Sun, Shuwei; Wan, Ning; Pan, Du; Bai, Ying; Zhu, Huiyuan; Hu, Yong-Sheng; Dai, Sheng

2015-10-14

A spinel LiMn1.5Ni0.5O4 (LMNO) cathode material synthesized by a sol-gel method is modified by MgF2 nano-coating via a wet coating strategy. The results of X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) showed that the MgF2 nano-coating layers do not physically change the bulk structure of the pristine material. Compared with the pristine compound, the MgF2-coated LMNO electrodes display enhanced cycling stabilities. Particularly, the 5 wt% MgF2-coated LMNO demonstrates the best reversibility, with a capacity retention of 89.9% after 100 cycles, much higher than that of the pristine material, 69.3%. The dQ/dV analysis and apparent Li(+) diffusion coefficient calculation prove that the kinetic properties are enhanced after MgF2 surface modification, which partly explains the improved electrochemical performances. Electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) data confirm that the MgF2 coating layer helps in suppressing the fast growth of the solid electrolyte interface (SEI) film in repeated cycling, which effectively stabilizes the spinel structure. Additionally, differential scanning calorimetry (DSC) tests show that the MgF2 nano-coating layer also helps in enhancing the thermal stability of the LMNO cathode.

Interface Engineering of Garnet Solid Electrolytes

NASA Astrophysics Data System (ADS)

Cheng, Lei

Solid lithium ion conductors represent a promising class of materials for next generation high energy density batteries, with the potential for enabling use of high capacity Li metal anodes and providing opportunities for novel lithium-free cathode materials. However, highly resistive interfaces stymie their practical use. This urgent scientific challenge requires mechanistic understanding of ion transport at interfaces, as well as development of novel processes to achieve low interfacial resistances. The goal of this PhD dissertation was to generate fundamental understandings of garnet-structured Al substituted Li7La3Zr2O 12 (LLZO) electrolyte surfaces and interfaces with lithium metal electrodes. Specifically in this research, the topmost surface microstructure, local chemical environment, and surface chemistry were carefully studied. The ceramic processing of garnet is discussed and ways to control the sintering behavior and microstructures were explored and successfully demonstrated. Factors contributing to high interfacial resistance were systematically studied. The source of the high interfacial impedance has been traced to the presence of Li2CO 3 on pellet surfaces resulting from air exposure after processing. In addition, it was discovered that surface grain boundaries are surprisingly fast ion transport pathways and surface microstructure is critically important to lithium ion transport at interfaces. Complex homo- and heterostructured LLZO solid electrolytes with controllable surface and bulk microstructures were successfully fabricated, which allowed the comparison and separation of the contribution from the surface and the bulk. Engineered pellet surfaces allowed us to achieve the lowest interfacial resistance ever reported for this composition, resulting in significantly improved cycling behavior. Lastly, it was found that LLZO surfaces can be effectively stabilized under air exposure conditions, preventing Li2CO3 formation and maintaining low interfacial resistances. This opens new opportunities for garnet solid electrolyte in practical applications.

Microscopic dynamics research on the "mature" process of dye-sensitized solar cells after injection of highly concentrated electrolyte.

PubMed

Liang, Zhongguan; Liu, Weiqing; Chen, Jun; Hu, Linhua; Dai, Songyuan

2015-01-21

After injection of electrolyte, the internal three-dimensional solid-liquid penetration system of dye-sensitized solar cells (DSCs) can take a period of time to reach "mature" state. This paper studies the changes of microscopic processes of DSCs including TiO2 energy-level movement, localized state distribution, charge accumulation, electron transport, and recombination dynamics, from the beginning of electrolyte injection to the time of reached mature state. The results show that the microscopic dynamics process of DSCs exhibited a time-dependent behavior and achieved maturity ∼12 h after injecting the electrolyte into DSCs. Within 0-12 h, several results were observed: (1) the conduction band edge of TiO2 moved slightly toward negative potential direction; (2) the localized states in the band gap of TiO2 was reduced according to the same distribution law; (3) the transport resistance in TiO2 film increased, and electron transport time was prolonged as the time of maturity went on, which indicated that the electron transport process is impeded gradually; (4) the recombination resistance at the TiO2/electrolyte (EL) interface increases, and electron lifetime gradually extends, therefore, the recombination process is continuously suppressed. Furthermore, results suggest that the parameters of EL/Pt-transparent conductive oxide (TCO) interface including the interfacial capacitance, electron-transfer resistance, and transfer time constant would change with time of maturity, indicating that the EL/Pt-TCO interface is a potential factor affecting the mature process of DSCs.

Correlative tomography at the cathode/electrolyte interfaces of solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Wankmüller, Florian; Szász, Julian; Joos, Jochen; Wilde, Virginia; Störmer, Heike; Gerthsen, Dagmar; Ivers-Tiffée, Ellen

2017-08-01

This paper introduces a correlative tomography technique. It visualizes the spatial organization of primary and secondary phases at the interface of La0.58Sr0.4Co0.2Fe0.8O3-δ cathode/10 mol% Gadolinia doped Ceria/8 mol% Yttria stabilized Zirconia electrolyte. It uses focused ion beam/scanning electron microscope tomography (FIB/SEM), and combines data sets from Everhart-Thornley and Inlens detector differentiating four primary and two secondary material phases. In addition, grayscale information is correlated to elemental distribution gained by energy dispersive X-ray spectroscopy in a scanning transmission electron microscope. Interdiffusion of GDC into YSZ and SrZrO3 as secondary phases depend (in both amount and spatial organization) on the varied co-sintering temperature of the GDC/YSZ electrolyte. The ion-blocking SrZrO3 forms a continuous layer on top of the temperature-dependent GDC/YSZ interdiffusion zone (ID) at and below a co-sintering temperature of 1200 °C; above it becomes intermittent. 2D FIB/SEM images of primary and secondary phases at 1100, 1200, 1300 and 1400 °C were combined with a 3D FIB/SEM reconstruction (1300 °C). This reveals that ;preferred; oxygen ion transport pathways from the LSCF cathode through GDC and the ID into the YSZ electrolyte only exist in samples sintered above 1200 °C. The applied correlative technique expands our understanding of this multiphase cathode/electrolyte interface region.

Development of a Visual System Interface to Support a Domain-Oriented Application Composition System

DTIC Science & Technology

1993-03-23

Austin Texas, 1990. 25. Kang, Kyo C. and others. Feature-Oriented Domain Analysis ( FODA ) Feasibility Study. Tech- nical Report CMU/SEI-90-TR-21, Software...Validation and Analysis of the Architect Visual System. .. .. .. .. .... ....... 5-1 5.1 Validation Domain...5-2 5.3 Analysis .. .. .. .. .. .. .... .. .... .... .. .... .... .. ....... 5-2 5.3.1 The REFINE Environment

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.

Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity and methods for manufacturing such blends

DOEpatents

Skotheim, T.

A polymer blend is disclosed of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

Contact electrification induced interfacial reactions and direct electrochemical nanoimprint lithography in n-type gallium arsenate wafer.

PubMed

Zhang, Jie; Zhang, Lin; Wang, Wei; Han, Lianhuan; Jia, Jing-Chun; Tian, Zhao-Wu; Tian, Zhong-Qun; Zhan, Dongping

2017-03-01

Although metal assisted chemical etching (MacEtch) has emerged as a versatile micro-nanofabrication method for semiconductors, the chemical mechanism remains ambiguous in terms of both thermodynamics and kinetics. Here we demonstrate an innovative phenomenon, i.e. , the contact electrification between platinum (Pt) and an n-type gallium arsenide (100) wafer (n-GaAs) can induce interfacial redox reactions. Because of their different work functions, when the Pt electrode comes into contact with n-GaAs, electrons will move from n-GaAs to Pt and form a contact electric field at the Pt/n-GaAs junction until their electron Fermi levels ( E F ) become equal. In the presence of an electrolyte, the potential of the Pt/electrolyte interface will shift due to the contact electricity and induce the spontaneous reduction of MnO 4 - anions on the Pt surface. Because the equilibrium of contact electrification is disturbed, electrons will transfer from n-GaAs to Pt through the tunneling effect. Thus, the accumulated positive holes at the n-GaAs/electrolyte interface make n-GaAs dissolve anodically along the Pt/n-GaAs/electrolyte 3-phase interface. Based on this principle, we developed a direct electrochemical nanoimprint lithography method applicable to crystalline semiconductors.

Functional interface of polymer modified graphite anode

NASA Astrophysics Data System (ADS)

Komaba, S.; Ozeki, T.; Okushi, K.

Graphite electrodes were modified by polyacrylic acid (PAA), polymethacrylic acid (PMA), and polyvinyl alcohol (PVA). Their electrochemical properties were examined in 1 mol dm -3 LiClO 4 ethylene carbonate:dimethyl carbonate (EC:DMC) and propylene carbonate (PC) solutions as an anode of lithium ion batteries. Generally, lithium ions hardly intercalate into graphite in the PC electrolyte due to a decomposition of the PC electrolyte at ca. 0.8 V vs. Li/Li +, and it results in the exfoliation of the graphene layers. However, the modified graphite electrodes with PAA, PMA, and PVA demonstrated the stable charge-discharge performance due to the reversible lithium intercalation not only in the EC:DMC but also in the PC electrolytes since the electrolyte decomposition and co-intercalation of solvent were successfully suppressed by the polymer modification. It is thought that these improvements were attributed to the interfacial function of the polymer layer on the graphite which interacted with the solvated lithium ions at the electrode interface.

New insight into the discharge mechanism of silicon-air batteries using electrochemical impedance spectroscopy.

PubMed

Cohn, Gil; Eichel, Rüdiger A; Ein-Eli, Yair

2013-03-07

The mechanism of discharge termination in silicon-air batteries, employing a silicon wafer anode, a room-temperature fluorohydrogenate ionic liquid electrolyte and an air cathode membrane, is investigated using a wide range of tools. EIS studies indicate that the interfacial impedance between the electrolyte and the silicon wafer increases upon continuous discharge. In addition, it is shown that the impedance of the air cathode-electrolyte interface is several orders of magnitude lower than that of the anode. Equivalent circuit fitting parameters indicate the difference in the anode-electrolyte interface characteristics for different types of silicon wafers. Evolution of porous silicon surfaces at the anode and their properties, by means of estimated circuit parameters, is also presented. Moreover, it is found that the silicon anode potential has the highest negative impact on the battery discharge voltage, while the air cathode potential is actually stable and invariable along the whole discharge period. The discharge capacity of the battery can be increased significantly by mechanically replacing the silicon anode.

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.

The Fabrication of All-Solid-State Lithium-Ion Batteries via Spark Plasma Sintering

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

Wei, Xialu; Rechtin, Jack; Olevsky, Eugene

Spark plasma sintering (SPS) has been successfully used to produce all-solid-state lithium-ion batteries (ASSLibs). Both regular and functionally graded electrodes are implemented into novel three-layer and five-layer battery designs together with solid-state composite electrolyte. The electrical capacities and the conductivities of the SPS-processed ASSLibs are evaluated using the galvanostatic charge-discharge test. Experimental results have shown that, compared to the three-layer battery, the five-layer battery is able to improve energy and power densities. Scanning electron microscopy (SEM) is employed to examine the microstructures of the batteries especially at the electrode–electrolyte interfaces. It reveals that the functionally graded structure can eliminate themore » delamination effect at the electrode–electrolyte interface and, therefore, retains better performance.« less

The Fabrication of All-Solid-State Lithium-Ion Batteries via Spark Plasma Sintering

DOE PAGES

Wei, Xialu; Rechtin, Jack; Olevsky, Eugene

2017-09-14

Spark plasma sintering (SPS) has been successfully used to produce all-solid-state lithium-ion batteries (ASSLibs). Both regular and functionally graded electrodes are implemented into novel three-layer and five-layer battery designs together with solid-state composite electrolyte. The electrical capacities and the conductivities of the SPS-processed ASSLibs are evaluated using the galvanostatic charge-discharge test. Experimental results have shown that, compared to the three-layer battery, the five-layer battery is able to improve energy and power densities. Scanning electron microscopy (SEM) is employed to examine the microstructures of the batteries especially at the electrode–electrolyte interfaces. It reveals that the functionally graded structure can eliminate themore » delamination effect at the electrode–electrolyte interface and, therefore, retains better performance.« less

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

Surface Charge at the Oxide/Electrolyte Interface: Toward Optimization of Electrolyte Composition for Treatment of Aluminum and Magnesium by Plasma Electrolytic Oxidation.

PubMed

Nominé, Alexandre; Martin, Julien; Noël, Cédric; Henrion, Gérard; Belmonte, Thierry; Bardin, Ilya V; Lukeš, Petr

2016-02-09

Controlling microdischarges in plasma electrolytic oxidation is of great importance in order to optimize coating quality. The present study highlights the relationship between the polarity at which breakdown occurs and the electrolyte pH as compared with the isoelectric point (IEP). It is found that working at a pH higher than the IEP of the grown oxide prevents the buildup of detrimental cathodic discharges. The addition of phosphates results in a shift in the IEP to a lower value and therefore promotes anodic discharges at the expense of cathodic ones.

Cycle stability of the electrochemical capacitors patterned with vertically aligned carbon nanotubes in an LiPF6-based electrolyte.

PubMed

Chiou, Yi-Deng; Tsai, Dah-Shyang; Lam, Hoa Hung; Chang, Chuan-hua; Lee, Kuei-Yi; Huang, Ying-Sheng

2013-09-07

The miniature ultracapacitors, with interdigitated electrodes of vertically aligned carbon nanotubes (VACNTs) and an inter-electrode gap of 20 μm, have been prepared in the LiPF6 organic electrolyte with and without PVdF-HFP gel. PVdF-HFP between two opposing electrodes enhances the device reliability, but lessens its power performance because of the extra diffusion resistance. Also noteworthy are the gel influences on the cycle stability. When the applied voltage is 2.0 or 2.5 V, both the LiPF6 and the gel capacitors exhibit excellent stability, typified by a retention ratio of ≥95% after 10,000 cycles. Their coulombic efficiencies quickly rise up, and hold steady at 100%. Nonetheless, when the applied voltage is 3.5 or 4.0 V, the cycle stability deteriorates, since the negative electrode potential descends below 0.9 V (vs. Li), leading to electrolyte decomposition and SEI formation. For the LiPF6 capacitor, its retention ratio could be around 60% after 10,000 cycles and the coulombic efficiency of 100% is difficult to reach throughout its cycle life. On the other hand, the gel capacitor cycles energy with a much higher retention ratio, >80% after 10,000 cycles, and a better coulombic efficiency, even though electrolyte decomposition still occurs. We attribute the superior stability of the gel capacitor to its extra diffusion resistance which slows down the performance deterioration.

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.

Relevant Features of a Triethylene Glycol Dimethyl Ether-Based Electrolyte for Application in Lithium Battery.

PubMed

Carbone, Lorenzo; Di Lecce, Daniele; Gobet, Mallory; Munoz, Stephen; Devany, Matthew; Greenbaum, Steve; Hassoun, Jusef

2017-05-24

Triethylene glycol dimethyl ether (TREGDME) dissolving lithium trifluoromethanesulfonate (LiCF 3 SO 3 ) is studied as a suitable electrolyte medium for lithium battery. Thermal and rheological characteristics, transport properties of the dissolved species, and the electrochemical behavior in lithium cell represent the most relevant investigated properties of the new electrolyte. The self-diffusion coefficients, the lithium transference numbers, the ionic conductivity, and the ion association degree of the solution are determined by pulse field gradient nuclear magnetic resonance and electrochemical impedance spectroscopy. The study sheds light on the determinant role of the lithium nitrate (LiNO 3 ) addition for allowing cell operation by improving the electrode/electrolyte interfaces and widening the voltage stability window. Accordingly, an electrochemical activation procedure of the Li/LiFePO 4 cell using the upgraded electrolyte leads to the formation of stable interfaces at the electrodes surface as clearly evidenced by cyclic voltammetry, impedance spectroscopy, and ex situ scanning electron microscopy. Therefore, the lithium battery employing the TREGDME-LiCF 3 SO 3 -LiNO 3 solution shows a stable galvanostatic cycling, a high efficiency, and a notable rate capability upon the electrochemical conditions adopted herein.

Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity and methods for manufacturing such blends

DOEpatents

Skotheim, Terje

1984-01-01

There is disclosed a polymer blend of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

The Electrolyte Factor in O2 Reduction Electrocatalysis

DTIC Science & Technology

1993-04-23

molecule thick and does not seem to interfere with 02 and water/proton transport at this interface. This layer resembles a self-ordered Langmuir - Blodgett ... liquid electrolyte from within the polymer is in contact with the catalyst and completes the ionic circuit between the ionic conducting polymer and the...the free energy of adsorption of H2 0 and ionic components because of the lower effective dielectric constant in the electrolyte phase immediately

Promoting Effect of Layered Titanium Phosphate on the Electrochemical and Photovoltaic Performance of Dye-Sensitized Solar Cells

PubMed Central

2010-01-01

We reported a composite electrolyte prepared by incorporating layered α-titanium phosphate (α-TiP) into an iodide-based electrolyte using 1-ethyl-3-methylimidazolium tetrafluoroborate(EmimBF4) ionic liquid as solvent. The obtained composite electrolyte exhibited excellent electrochemical and photovoltaic properties compared to pure ionic liquid electrolyte. Both the diffusion coefficient of triiodide (I3−) in the electrolyte and the charge-transfer reaction at the electrode/electrolyte interface were improved markedly. The mechanism for the enhanced electrochemical properties of the composite electrolyte was discussed. The highest conversion efficiency of dye-sensitized solar cell (DSSC) was obtained for the composite electrolyte containing 1wt% α-TiP, with an improvement of 58% in the conversion efficiency than the blank one, which offered a broad prospect for the fabrication of stable DSSCs with a high conversion efficiency. PMID:20676195

Effect of electrolyte composition on initial cycling and impedance characteristics of lithium-ion cells

NASA Astrophysics Data System (ADS)

Abraham, D. P.; Furczon, M. M.; Kang, S.-H.; Dees, D. W.; Jansen, A. N.

Hybrid-electric vehicles require lithium-battery electrolytes that form stable, low impedance passivation layers to protect the electrodes, while allowing rapid lithium-ion transport under high current charge/discharge pulses. In this article, we describe data acquired on cells containing LiNi 0.8Co 0.15Al 0.05O 2-based positive electrodes, graphite-based negative electrodes, and electrolytes with lithium hexafluorophosphate (LiPF 6), lithium tetrafluoroborate (LiBF 4), lithium bis(oxalato)borate (LiBOB) and lithium difluoro(oxalato) borate (LiF 2OB) salts. The impedance data were collected in cells containing a Li-Sn reference electrode to determine effect of electrolyte composition and testing temperature on individual electrode impedance. The full cell impedance data showed the following trend: LiBOB > LiBF 4 > LiF 2OB > LiPF 6. The negative electrode impedance showed a trend similar to that of the full cell; this electrode was the main contributor to impedance in the LiBOB and LiBF 4 cells. The positive electrode impedance values for the LiBF 4, LiF 2OB, and LiPF 6 cells were comparable; the values were somewhat higher for the LiBOB cell. Cycling and impedance data were also obtained for cells containing additions of LiBF 4, LiBOB, LiF 2OB, and vinylene carbonate (VC) to the EC:EMC (3:7 by wt.) + 1.2 M LiPF 6 electrolyte. Our data indicate that the composition and morphology of the graphite SEI formed during the first lithiation cycle is an important determinant of the negative electrode impedance, and hence full cell impedance.

Contact electrification induced interfacial reactions and direct electrochemical nanoimprint lithography in n-type gallium arsenate wafer† †Electronic supplementary information (ESI) available: Electrochemical measurements of the interfaces, optimization of the contact force and temperature of ECNL, XPS analysis, and more examples of ECNL on n-GaAs. See DOI: 10.1039/c6sc04091h Click here for additional data file.

PubMed Central

Zhang, Jie; Zhang, Lin; Wang, Wei; Han, Lianhuan; Jia, Jing-Chun; Tian, Zhao-Wu; Tian, Zhong-Qun

2017-01-01

Although metal assisted chemical etching (MacEtch) has emerged as a versatile micro-nanofabrication method for semiconductors, the chemical mechanism remains ambiguous in terms of both thermodynamics and kinetics. Here we demonstrate an innovative phenomenon, i.e., the contact electrification between platinum (Pt) and an n-type gallium arsenide (100) wafer (n-GaAs) can induce interfacial redox reactions. Because of their different work functions, when the Pt electrode comes into contact with n-GaAs, electrons will move from n-GaAs to Pt and form a contact electric field at the Pt/n-GaAs junction until their electron Fermi levels (E F) become equal. In the presence of an electrolyte, the potential of the Pt/electrolyte interface will shift due to the contact electricity and induce the spontaneous reduction of MnO4 – anions on the Pt surface. Because the equilibrium of contact electrification is disturbed, electrons will transfer from n-GaAs to Pt through the tunneling effect. Thus, the accumulated positive holes at the n-GaAs/electrolyte interface make n-GaAs dissolve anodically along the Pt/n-GaAs/electrolyte 3-phase interface. Based on this principle, we developed a direct electrochemical nanoimprint lithography method applicable to crystalline semiconductors. PMID:28451347

Unravelling Li-Ion Transport from Picoseconds to Seconds: Bulk versus Interfaces in an Argyrodite Li6PS5Cl-Li2S All-Solid-State Li-Ion Battery.

PubMed

Yu, Chuang; Ganapathy, Swapna; de Klerk, Niek J J; Roslon, Irek; van Eck, Ernst R H; Kentgens, Arno P M; Wagemaker, Marnix

2016-09-07

One of the main challenges of all-solid-state Li-ion batteries is the restricted power density due to the poor Li-ion transport between the electrodes via the electrolyte. However, to establish what diffusional process is the bottleneck for Li-ion transport requires the ability to distinguish the various processes. The present work investigates the Li-ion diffusion in argyrodite Li6PS5Cl, a promising electrolyte based on its high Li-ion conductivity, using a combination of (7)Li NMR experiments and DFT based molecular dynamics simulations. This allows us to distinguish the local Li-ion mobility from the long-range Li-ion motional process, quantifying both and giving a coherent and consistent picture of the bulk diffusion in Li6PS5Cl. NMR exchange experiments are used to unambiguously characterize Li-ion transport over the solid electrolyte-electrode interface for the electrolyte-electrode combination Li6PS5Cl-Li2S, giving unprecedented and direct quantitative insight into the impact of the interface on Li-ion charge transport in all-solid-state batteries. The limited Li-ion transport over the Li6PS5Cl-Li2S interface, orders of magnitude smaller compared with that in the bulk Li6PS5Cl, appears to be the bottleneck for the performance of the Li6PS5Cl-Li2S battery, quantifying one of the major challenges toward improved performance of all-solid-state batteries.

Enhancing Capacity Performance by Utilizing the Redox Chemistry of the Electrolyte in a Dual-Electrolyte Sodium-Ion Battery.

PubMed

Senthilkumar, Sirugaloor Thangavel; Bae, Hyuntae; Han, Jinhyup; Kim, Youngsik

2018-05-04

A strategy is described to increase charge storage in a dual electrolyte Na-ion battery (DESIB) by combining the redox chemistry of the electrolyte with a Na + ion de-insertion/insertion cathode. Conventional electrolytes do not contribute to charge storage in battery systems, but redox-active electrolytes augment this property via charge transfer reactions at the electrode-electrolyte interface. The capacity of the cathode combined with that provided by the electrolyte redox reaction thus increases overall charge storage. An aqueous sodium hexacyanoferrate (Na 4 Fe(CN) 6 ) solution is employed as the redox-active electrolyte (Na-FC) and sodium nickel Prussian blue (Na x -NiBP) as the Na + ion insertion/de-insertion cathode. The capacity of DESIB with Na-FC electrolyte is twice that of a battery using a conventional (Na 2 SO 4 ) electrolyte. The use of redox-active electrolytes in batteries of any kind is an efficient and scalable approach to develop advanced high-energy-density storage systems. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phase-field based Multiscale Modeling of Heterogeneous Solid Electrolytes: Applications to Nanoporous Li 3 PS 4

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

Hu, Jia-Mian; Wang, Bo; Ji, Yanzhou

Modeling the effective ion conductivities of heterogeneous solid electrolytes typically involves the use of a computer-generated microstructure consisting of randomly or uniformly oriented fillers in a matrix. But, the structural features of the filler/matrix interface, which critically determine the interface ion conductivity and the microstructure morphology, have not been considered during the microstructure generation. In using nanoporous β-Li 3PS 4 electrolyte as an example, we develop a phase-field model that enables generating nanoporous microstructures of different porosities and connectivity patterns based on the depth and the energy of the surface (pore/electrolyte interface), both of which are predicted through density functionalmore » theory (DFT) calculations. Room-temperature effective ion conductivities of the generated microstructures are then calculated numerically, using DFT-estimated surface Li-ion conductivity (3.14×10 -3 S/cm) and experimentally measured bulk Li-ion conductivity (8.93×10 -7 S/cm) of β-Li 3PS 4 as the inputs. We also use the generated microstructures to inform effective medium theories to rapidly predict the effective ion conductivity via analytical calculations. Furthemore, when porosity approaches the percolation threshold, both the numerical and analytical methods predict a significantly enhanced Li-ion conductivity (1.74×10 -4 S/cm) that is in good agreement with experimental data (1.64×10 -4 S/cm). The present phase-field based multiscale model is generally applicable to predict both the microstructure patterns and the effective properties of heterogeneous solid electrolytes.« less

Phase-field based Multiscale Modeling of Heterogeneous Solid Electrolytes: Applications to Nanoporous Li 3 PS 4

DOE PAGES

Hu, Jia-Mian; Wang, Bo; Ji, Yanzhou; ...

2017-09-07

Modeling the effective ion conductivities of heterogeneous solid electrolytes typically involves the use of a computer-generated microstructure consisting of randomly or uniformly oriented fillers in a matrix. But, the structural features of the filler/matrix interface, which critically determine the interface ion conductivity and the microstructure morphology, have not been considered during the microstructure generation. In using nanoporous β-Li 3PS 4 electrolyte as an example, we develop a phase-field model that enables generating nanoporous microstructures of different porosities and connectivity patterns based on the depth and the energy of the surface (pore/electrolyte interface), both of which are predicted through density functionalmore » theory (DFT) calculations. Room-temperature effective ion conductivities of the generated microstructures are then calculated numerically, using DFT-estimated surface Li-ion conductivity (3.14×10 -3 S/cm) and experimentally measured bulk Li-ion conductivity (8.93×10 -7 S/cm) of β-Li 3PS 4 as the inputs. We also use the generated microstructures to inform effective medium theories to rapidly predict the effective ion conductivity via analytical calculations. Furthemore, when porosity approaches the percolation threshold, both the numerical and analytical methods predict a significantly enhanced Li-ion conductivity (1.74×10 -4 S/cm) that is in good agreement with experimental data (1.64×10 -4 S/cm). The present phase-field based multiscale model is generally applicable to predict both the microstructure patterns and the effective properties of heterogeneous solid electrolytes.« less

Advanced Characterization Techniques for Sodium-Ion Battery Studies

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

Shadike, Zulipiya; Zhao, Enyue; Zhou, Yong-Ning

Sodium (Na)-ion batteries (NIBs) are considered promising alternative candidates to the well-commercialized lithium-ion batteries, especially for applications in large-scale energy storage systems. The electrochemical performance of NIBs such as the cyclability, rate capability, and voltage profiles are strongly dependent on the structural and morphological evolution, phase transformation, sodium-ion diffusion, and electrode/electrolyte interface reconstruction during charge–discharge cycling. Therefore, in-depth understanding of the structure and kinetics of electrode materials and the electrode/electrolyte interfaces is essential for optimizing current NIB systems and exploring new materials for NIBs. Recently, rapid progress and development in spectroscopic, microscopic, and scattering techniques have provided extensive insight intomore » the nature of structural evolution, morphological changes of electrode materials, and electrode/electrolyte interface in NIBs. Here in this review, a comprehensive overview of both static (ex situ) and real-time (in situ or in operando) techniques for studying the NIBs is provided. Lastly, special focus is placed on how these techniques are applied to the fundamental investigation of NIB systems and what important results are obtained.« less

Adsorption of surfactant ions and binding of their counterions at an air/water interface.

PubMed

Tagashira, Hiroaki; Takata, Youichi; Hyono, Atsushi; Ohshima, Hiroyuki

2009-01-01

An expression for the surface tension of an aqueous mixed solution of surfactants and electrolyte ions in the presence of the common ions was derived from the Helmholtz free energy of an air/water surface. By applying the equation to experimental data for the surface tension, the adsorption constant of surfactant ions onto the air/water interface, the binding constant of counterions on the surfactants, and the surface potential and surface charge density of the interface were estimated. The adsorption constant and binding constant were dependent on the species of surfactant ion and counterion, respectively. Taking account of the dependence of surface potential and surface charge density on the concentration of electrolyte, it was suggested that the addition of electrolyte to the aqueous surfactant solution brings about the decrease in the surface potential, the increase in the surface density of surfactant ions, and consequently, the decrease in the surface tension. Furthermore, it was found that the configurational entropy plays a predominant role for the surface tension, compared to the electrical work.

The influence of the carbonate species on LiNi0.8Co0.15Al0.05O2 surfaces for all-solid-state lithium ion battery performance

NASA Astrophysics Data System (ADS)

Visbal, Heidy; Fujiki, Satoshi; Aihara, Yuichi; Watanabe, Taku; Park, Youngsin; Doo, Seokgwang

2014-12-01

The influence of selected carbonate species on LiNi0.8Co0.15Al0.05O2 (NCA) surface for all-solid-state lithium-ion battery (ASSB) with a sulfide based solid electrolyte was studied for its electrochemical properties, structural stabilities, and surface characteristics. The rated discharge performance improved with the reduction of the carbonate concentration on the NCA surface due to the decrease of the interface resistance. The species and coordination of the adsorbed carbonates on the NCA surface were analyzed by diffuse reflectance Fourier transformed infrared (DRIFT) spectroscopy. The coordination of the adsorbed carbonate anion was determined based on the degree of splitting of the ν3(CO) stretching vibrations. It is found that the surface carbonate species exists in an unidentate coordination on the surface. They react with the sulfide electrolyte to form an irreversible passivation layer. This layer obstructs the charge transfer process at the cathode/electrolyte interface, and results in the rise of the interface resistance and drop of the rated discharge capability.

Advanced Characterization Techniques for Sodium-Ion Battery Studies

DOE PAGES

Shadike, Zulipiya; Zhao, Enyue; Zhou, Yong-Ning; ...

2018-02-19

Sodium (Na)-ion batteries (NIBs) are considered promising alternative candidates to the well-commercialized lithium-ion batteries, especially for applications in large-scale energy storage systems. The electrochemical performance of NIBs such as the cyclability, rate capability, and voltage profiles are strongly dependent on the structural and morphological evolution, phase transformation, sodium-ion diffusion, and electrode/electrolyte interface reconstruction during charge–discharge cycling. Therefore, in-depth understanding of the structure and kinetics of electrode materials and the electrode/electrolyte interfaces is essential for optimizing current NIB systems and exploring new materials for NIBs. Recently, rapid progress and development in spectroscopic, microscopic, and scattering techniques have provided extensive insight intomore » the nature of structural evolution, morphological changes of electrode materials, and electrode/electrolyte interface in NIBs. Here in this review, a comprehensive overview of both static (ex situ) and real-time (in situ or in operando) techniques for studying the NIBs is provided. Lastly, special focus is placed on how these techniques are applied to the fundamental investigation of NIB systems and what important results are obtained.« less

Rough Gold Electrodes for Decreasing Impedance at the Electrolyte/Electrode Interface

PubMed Central

Koklu, Anil; Sabuncu, Ahmet C.; Beskok, Ali

2016-01-01

Electrode polarization at the electrolyte/electrode interface is often undesirable for bio-sensing applications, where charge accumulated over an electrode at constant potential causes large potential drop at the interface and low measurement sensitivity. In this study, novel rough electrodes were developed for decreasing electrical impedance at the interface. The electrodes were fabricated using electrochemical deposition of gold and sintering of gold nanoparticles. The performances of the gold electrodes were compared with platinum black electrodes. A constant phase element model was used to describe the interfacial impedance. Hundred folds of decrease in interfacial impedance were observed for fractal gold electrodes and platinum black. Biotoxicity, contact angle, and surface morphology of the electrodes were investigated. Relatively low toxicity and hydrophilic nature of the fractal and granulated gold electrodes make them suitable for bioimpedance and cell electromanipulation studies compared to platinum black electrodes which are both hydrophobic and toxic. PMID:27695132

Protein Monolayer Formation at Air-Electrolyte Interface:. a Langmuir-Blodgett Study

NASA Astrophysics Data System (ADS)

Pal, Prabir; Kamilya, Tapanendu; Mahato, Mrityunjoy; Talapatra, G. B.

The interfacial surface activity of a protein, ovalbumin (OVA) at bare air/water interface in presence and also in absence of electrolyte (KCl) in subphase has been investigated. The surface activity was measured as a function of time. It has been found that, the presence of KCl in aqueous subphase enhances the adsorption rate of the protein. The changes of area/molecule, compressibility, rigidity and unfolding of OVA are trivial up to 10 mM KCl concentration. These properties of OVA, above 10 mM KCl concentration are significant and have been explained in the perspective of DLVO theory and many-body ion-protein dispersion potentials. The presence of high concentration of electrolyte increases the β-structure of OVA, resulting into larger unfolding as well as larger intermolecular aggregates. The overall study indicates that KCl perturbs the OVA monolayer.

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

Spectroscopic Studies of the Electronic Structure of Metal-Semiconductor and Vacuum-Semiconductor Interfaces.

DTIC Science & Technology

1982-12-31

interfaces which are of importance in such semi- conductor devices as MOSFETS, CCD devices, photovoltaic devices, DD I jAN 73 1473 EDITION OF INOV 66 if...interfaces is interesting for the study of electrolytic cells . Our photoemission study reveals for the first time how the electronic structure of water

Enhanced stability of solid oxide fuel cells by employing a modified cathode-interlayer interface with a dense La0.6Sr0.4Co0.2Fe0.8O3-δ thin film

NASA Astrophysics Data System (ADS)

De Vero, Jeffrey C.; Develos-Bagarinao, Katherine; Kishimoto, Haruo; Ishiyama, Tomohiro; Yamaji, Katsuhiko; Horita, Teruhisa; Yokokawa, Harumi

2018-02-01

In La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode/Gd-doped ceria (GDC)/yttria-stabilized zirconia (YSZ)-electrolyte based solid oxide fuel cells (SOFCs), one of the key issues affecting performance and long-term stability is the apparent deactivation of LSCF cathode by the presence of secondary phases such as SrZrO3 at the interfaces. Herein, we report that by modifying the cathode-interlayer interface with a dense LSCF thin film, the severe cation interdiffusion is suppressed especially the fast gas or surface diffusion of Sr into adjacent GDC-interlayer/YSZ-electrolyte resulting in the significant reduction of SrZrO3 formation at the interfaces improving cell stability. In order to understand the present results, the interface chemistry is carefully considered and discussed. The results show that modification of cathode-interlayer interfaces is an important strategy for improving the lifetime of SOFCs.

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.

Elastic Properties of the Solid Electrolyte Li7La3Zr2O12 (LLZO)

DOE PAGES

Yu, Seungho; Schmidt, Robert D.; Garcia-mendez, Regina; ...

2015-12-16

The oxide known as LLZO, with nominal composition Li 7La 3Zr 2O 12, is a promising solid electrolyte for Li-based batteries due to its high Li-ion conductivity and chemical stability with respect to lithium. Solid electrolytes may also enable the use of metallic Li anodes by serving as a physical barrier that suppresses dendrite initiation and propagation during cycling. Prior linear elasticity models of the Li electrode/solid electrolyte interface suggest that the stability of this interface is highly dependent on the elastic properties of the solid separator. For example, dendritic suppression is predicted to be enhanced as the electrolyte smore » shear modulus increases. In the present study a combination of first-principles calculations, acoustic impulse excitation measurements, and nanoindentation experiments are used to determine the elastic constants and moduli for highconductivity LLZO compositions based on Al and Ta doping. The calculated and measured isotropic shear moduli are in good agreement and fall within the range of 56-61 GPa. These values are an order of magnitude larger than that for Li metal and far exceed the minimum value ( 8.5 GPa) believed to be necessary to suppress dendrite initiation. These data suggest that LLZO exhibits sufficient stiffness to warrant additional development as a solid electrolyte for Li batteries.« less

Emerging applications of spark plasma sintering in all solid-state lithium-ion batteries and beyond

NASA Astrophysics Data System (ADS)

Zhu, Hongzheng; Liu, Jian

2018-07-01

Solid-state batteries have received increasing attention due to their high safety aspect and high energy and power densities. However, the development of solid-state batteries is hindered by inferior solid-solid interfaces between the solid-state electrolyte and electrode, which cause high interfacial resistance, reduced Li-ion and electron transfer rate, and limited battery performance. Recently, spark plasma sintering (SPS) is emerging as a promising technique for fabricating solid-state electrolyte and electrode pellets with clean and intimate solid-solid interfaces. During the SPS process, the unique reaction mechanism through the combination of current, pressure and high heating rate allow the formation of desirable solid-solid interfaces between active material particles. Herein, this work focuses on the overview of the application of SPS for fabricating solid-state electrolyte and electrode in all solid-state Li-ion batteries, and beyond, such as solid-state Li-S and Na-ion batteries. The correlations among SPS parameters, interfacial resistance, and electrochemical properties of solid-state electrolytes and electrodes are discussed for different material systems. In the end, we point out future opportunities and challenges associated with SPS application in the hot area of solid-state batteries. It is expected that this timely review will stimulate more fundamental and applied research in the development of solid-state batteries by SPS.

Earthquake Intensity and Strong Motion Analysis Within SEISCOMP3

NASA Astrophysics Data System (ADS)

Becker, J.; Weber, B.; Ghasemi, H.; Cummins, P. R.; Murjaya, J.; Rudyanto, A.; Rößler, D.

2017-12-01

Measuring and predicting ground motion parameters including seismic intensities for earthquakes is crucial and subject to recent research in engineering seismology.gempa has developed the new SIGMA module for Seismic Intensity and Ground Motion Analysis. The module is based on the SeisComP3 framework extending it in the field of seismic hazard assessment and engineering seismology. SIGMA may work with or independently of SeisComP3 by supporting FDSN Web services for importing earthquake or station information and waveforms. It provides a user-friendly and modern graphical interface for semi-automatic and interactive strong motion data processing. SIGMA provides intensity and (P)SA maps based on GMPE's or recorded data. It calculates the most common strong motion parameters, e.g. PGA/PGV/PGD, Arias intensity and duration, Tp, Tm, CAV, SED and Fourier-, power- and response spectra. GMPE's are configurable. Supporting C++ and Python plug-ins, standard and customized GMPE's including the OpenQuake Hazard Library can be easily integrated and compared. Originally tailored to specifications by Geoscience Australia and BMKG (Indonesia) SIGMA has become a popular tool among SeisComP3 users concerned with seismic hazard and strong motion seismology.

Project Interface Requirements Process Including Shuttle Lessons Learned

NASA Technical Reports Server (NTRS)

Bauch, Garland T.

2010-01-01

Most failures occur at interfaces between organizations and hardware. Processing interface requirements at the start of a project life cycle will reduce the likelihood of costly interface changes/failures later. This can be done by adding Interface Control Documents (ICDs) to the Project top level drawing tree, providing technical direction to the Projects for interface requirements, and by funding the interface requirements function directly from the Project Manager's office. The interface requirements function within the Project Systems Engineering and Integration (SE&I) Office would work in-line with the project element design engineers early in the life cycle to enhance communications and negotiate technical issues between the elements. This function would work as the technical arm of the Project Manager to help ensure that the Project cost, schedule, and risk objectives can be met during the Life Cycle. Some ICD Lessons Learned during the Space Shuttle Program (SSP) Life Cycle will include the use of hardware interface photos in the ICD, progressive life cycle design certification by analysis, test, & operations experience, assigning interface design engineers to Element Interface (EI) and Project technical panels, and linking interface design drawings with project build drawings

Capillary electrophoresis electrospray ionization mass spectrometry interface

DOEpatents

Smith, Richard D.; Severs, Joanne C.

1999-01-01

The present invention is an interface between a capillary electrophoresis separation capillary end and an electrospray ionization mass spectrometry emitter capillary end, for transporting an anolyte sample from a capillary electrophoresis separation capillary to a electrospray ionization mass spectrometry emitter capillary. The interface of the present invention has: (a) a charge transfer fitting enclosing both of the capillary electrophoresis capillary end and the electrospray ionization mass spectrometry emitter capillary end; (b) a reservoir containing an electrolyte surrounding the charge transfer fitting; and (c) an electrode immersed into the electrolyte, the electrode closing a capillary electrophoresis circuit and providing charge transfer across the charge transfer fitting while avoiding substantial bulk fluid transfer across the charge transfer fitting. Advantages of the present invention have been demonstrated as effective in providing high sensitivity and efficient analyses.

Electrolyte Solutions and Specific Ion Effects on Interfaces

ERIC Educational Resources Information Center

Friedman, Ran

2013-01-01

Introductory general and physical chemistry courses often deal with colligative properties of solutions and do not discuss nonideal solutions in detail. Yet, a growing body of evidence reveals that even at physiological concentrations electrolyte solutions cannot be treated as ideal when a charged or partially charged solute (such as a protein) is…

High-Performance Protonic Ceramic Fuel Cells with Thin-Film Yttrium-Doped Barium Cerate-Zirconate Electrolytes on Compositionally Gradient Anodes.

PubMed

Bae, Kiho; Lee, Sewook; Jang, Dong Young; Kim, Hyun Joong; Lee, Hunhyeong; Shin, Dongwook; Son, Ji-Won; Shim, Joon Hyung

2016-04-13

In this study, we used a compositionally gradient anode functional layer (AFL) consisting of Ni-BaCe(0.5)Zr(0.35)Y(0.15)O(3-δ) (BCZY) with increasing BCZY contents toward the electrolyte-anode interface for high-performance protonic ceramic fuel cells. It is identified that conventional homogeneous AFLs fail to stably accommodate a thin film of BCZY electrolyte. In contrast, a dense 2 μm thick BCZY electrolyte was successfully deposited onto the proposed gradient AFL with improved adhesion. A fuel cell containing this thin electrolyte showed a promising maximum peak power density of 635 mW cm(-2) at 600 °C, with an open-circuit voltage of over 1 V. Impedance analysis confirmed that minimizing the electrolyte thickness is essential for achieving a high power output, suggesting that the anode structure is important in stably accommodating thin electrolytes.

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

Kazyak, Eric; Chen, Kuan-Hung; Wood, Kevin N.

Lithium solid electrolytes are a promising platform for achieving high energy density, long-lasting, and safe rechargeable batteries, which could have widespread societal impact. In particular, the ceramic oxide garnet Li7La3Zr2O12 (LLZO) has been shown to be a promising electrolyte due to its stability and high ionic conductivity. Two major challenges for commercialization are manufacturing of thin layers and creating stable, low-impedance, interfaces with both anode and cathode materials. Atomic Layer Deposition (ALD) has recently been shown as a potential method for depositing both solid electrolytes and interfacial layers to improve the stability and performance at electrode-electrolyte interfaces in battery systems.more » Herein we present the first reported ALD process for LLZO, demonstrating the ability to tune composition within the amorphous film and anneal to achieve the desired cubic garnet phase. Formation of the cubic phase was observed at temperatures as low as 555°C, significantly lower than is required for bulk processing. Additionally, challenges associated with achieving a dense garnet phase due to substrate reactivity, morphology changes and Li loss under the necessary high temperature annealing are quantified via in situ synchrotron diffraction.« less

The role of electrolyte and polyelectrolyte on the adsorption of the anionic surfactant, sodium dodecylbenzenesulfonate, at the air-water interface.

PubMed

Zhang, X L; Taylor, D J F; Thomas, R K; Penfold, J

2011-04-15

The role of the polyelectrolyte, poly(ethyleneimine), PEI, and the electrolytes NaCl and CaCl(2), on the adsorption of the anionic surfactant, sodium dodecylbenzenesulfonate, LAS, at the air-water interface have been investigated by neutron reflectivity and surface tension. The surface tension data for the PEI/LAS mixtures are substantially affected by pH and the addition of electrolyte, and are consistent with a strong adsorption of surface polymer/surfactant complexes down to relatively low surfactant concentrations. The effects are most pronounced at high pH, and this is confirmed by the adsorption data obtained directly from neutron reflectivity. However, the effects of the addition of PEI and electrolyte on the LAS adsorption are not as pronounced as previously reported for PEI/SDS mixtures. This is attributed primarily to the steric hindrance of the LAS phenyl group resulting in a reduction in the ion-dipole attraction between the LAS sulfonate and amine groups that dominates the interaction at high pH. Copyright © 2011 Elsevier Inc. All rights reserved.

Selenium and Selenium–Sulfur Chemistry for Rechargeable Lithium Batteries: Interplay of Cathode Structures, Electrolytes, and Interfaces

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

Xu, Gui-Liang; Liu, Jianzhao; Amine, Rachid

2017-02-09

In the search for a transformative new energy storage system, the rechargeable Li/sulfur battery is considered as one of the promising candidates due to its much higher energy density and lower cost than state-of-the-art lithium-ion batteries. However, the insulating nature of sulfur and the dissolution of intermediary polysulfides into the electrolyte significantly hinder its practical application. Very recently, selenium and selenium-sulfur systems have received considerable attention as cathode materials for rechargeable batteries owing to the high electronic conductivity (20 orders of magnitude higher than sulfur) and high volumetric capacity (3254 mAh/cm3 ) of selenium. In this perspective, we present anmore » overview of the implications of employing selenium and selenium-sulfur systems with different structures and compositions as electroactive materials for rechargeable lithium batteries. We also show how the cathode structures, electrolytes, and electrode-electrolyte interfaces affect the electrochemistry of Se and Se-S based cathodes. Furthermore, suggestions are provided on paths for future development of these cathodes.« less

Tailoring the electrode-electrolyte interface of Solid Oxide Fuel Cells (SOFC) by laser micro-patterning to improve their electrochemical performance

NASA Astrophysics Data System (ADS)

Cebollero, J. A.; Lahoz, R.; Laguna-Bercero, M. A.; Larrea, A.

2017-08-01

Cathode activation polarisation is one of the main contributions to the losses of a Solid Oxide Fuel Cell. To reduce this loss we use a pulsed laser to modify the surface of yttria stabilized zirconia (YSZ) electrolytes to make a corrugated micro-patterning in the mesoscale. The beam of the laser source, 5 ns pulse width and emitting at λ = 532 nm (green region), is computer-controlled to engrave the selected micro-pattern on the electrolyte surface. Several laser scanning procedures and geometries have been tested. Finally, we engrave a square array with 28 μm of lattice parameter and 7 μm in depth on YSZ plates. With these plates we prepare LSM-YSZ/YSZ/LSM-YSZ symmetrical cells (LSM: La1-xSrxMnO3) and determine their activation polarisation by Electrochemical Impedance Spectroscopy (EIS). To get good electrode-electrolyte contact after sintering it is necessary to use pressure-assisted sintering with low loads (about 5 kPa), which do not modify the electrode microstructure. The decrease in polarisation with respect to an unprocessed cell is about 30%. EIS analysis confirms that the reason for this decrease is an improvement in the activation processes at the electrode-electrolyte interface.

Ionic Effects on Supercritical CO2-Brine Interfacial Tensions: Molecular Dynamics Simulations and a Universal Correlation with Ionic Strength, Temperature, and Pressure.

PubMed

Zhao, Lingling; Ji, Jiayuan; Tao, Lu; Lin, Shangchao

2016-09-13

For geological CO2 storage in deep saline aquifers, the interfacial tension (IFT) between supercritical CO2 and brine is critical for the storage security and design of the storage capacitance. However, currently, no predictive model exists to determine the IFT of supercritical CO2 against complex electrolyte solutions involving various mixed salt species at different concentrations and compositions. In this paper, we use molecular dynamics (MD) simulations to investigate the effect of salt ions on the incremental IFT at the supercritical CO2-brine interface with respect to that at the reference supercritical CO2-water interface. Supercritical CO2-NaCl solution, CO2-CaCl2 solution and CO2-(NaCl+CaCl2) mixed solution systems are simulated at 343 K and 20 MPa under different salinities and salt compositions. We find that the valence of the cations is the primary contributor to the variation in IFT, while the Lennard-Jones potentials for the cations pose a smaller impact on the IFT. Interestingly, the incremental IFT exhibits a general linear correlation with the ionic strength in the above three electrolyte systems, and the slopes are almost identical and independent of the solution types. Based on this finding, a universal predictive formula for IFTs of CO2-complex electrolyte solution systems is established, as a function of ionic strength, temperature, and pressure. The predicted IFTs using the established formula agree perfectly (with a high statistical confidence level of ∼96%) with a wide range of experimental data for CO2 interfacing with different electrolyte solutions, such as those involving MgCl2 and Na2SO4. This work provides an efficient and accurate route to directly predict IFTs in supercritical CO2-complex electrolyte solution systems for practical engineering applications, such as geological CO2 sequestration in deep saline aquifers and other interfacial systems involving complex electrolyte solutions.

Composite electrolytes of polyethylene oxides/garnets interfacially wetted by ionic liquid for room-temperature solid-state lithium battery

NASA Astrophysics Data System (ADS)

Huo, Hanyu; Zhao, Ning; Sun, Jiyang; Du, Fuming; Li, Yiqiu; Guo, Xiangxin

2017-12-01

Paramount attention has been paid on solid polymer electrolytes due to their potential in enhancement of energy density as well as improvement of safety. Herein, the composite electrolytes consisting of Li-salt-free polyethylene oxides and 200 nm-sized Li6.4La3Zr1.4Ta0.6O12 particles interfacially wetted by [BMIM]TF2N of 1.8 μL cm-2 have been prepared. Such wetted ionic liquid remains the solid state of membrane electrolytes and decreases the interface impedance between the electrodes and the electrolytes. There is no release of the liquid phase from the PEO matrix when the pressure of 5.0 × 104 Pa being applied for 24 h. The interfacially wetted membrane electrolytes show the conductivity of 2.2 × 10-4 S cm-1 at 20 °C, which is one order of magnitude greater than that of the membranes without the wetted ionic liquids. The conduction mechanism is related to a large number of lithium ions releasing from Li6.4La3Zr1.4Ta0.6O12 particles and the improved conductive paths along the ion-liquid-wetted interfaces between the polymer matrix and ceramic grains. When the membranes being used in the solid-state LiFePO4/Li and LiFe0.15Mn0.85PO4/Li cells at 25 °C, the excellent rate capability and superior cycle stability has been shown. The results provide a new prospect for solid polymer electrolytes used for room-temperature solid-state lithium batteries.

Recent Progresses and Development of Advanced Atomic Layer Deposition towards High-Performance Li-Ion Batteries

PubMed Central

Lu, Wei; Liang, Longwei; Sun, Xuan; Sun, Xiaofei; Wu, Chen; Hou, Linrui; Sun, Jinfeng

2017-01-01

Electrode materials and electrolytes play a vital role in device-level performance of rechargeable Li-ion batteries (LIBs). However, electrode structure/component degeneration and electrode-electrolyte sur-/interface evolution are identified as the most crucial obstacles in practical applications. Thanks to its congenital advantages, atomic layer deposition (ALD) methodology has attracted enormous attention in advanced LIBs. This review mainly focuses upon the up-to-date progress and development of the ALD in high-performance LIBs. The significant roles of the ALD in rational design and fabrication of multi-dimensional nanostructured electrode materials, and finely tailoring electrode-electrolyte sur-/interfaces are comprehensively highlighted. Furthermore, we clearly envision that this contribution will motivate more extensive and insightful studies in the ALD to considerably improve Li-storage behaviors. Future trends and prospects to further develop advanced ALD nanotechnology in next-generation LIBs were also presented. PMID:29036916

The Influence of Electrolytes on the Mixed Micellization of Equimolar (Monomeric and Dimeric) Surfactants

NASA Astrophysics Data System (ADS)

Alam, Md. Sayem; Siddiq, A. Mohammed; Mandal, Asit Baran

2018-01-01

The influence of halide ions of (sodium salt) electrolytes on the mixed micellization of a cationic gemini (dimeric) surfactant, hexanediyl-1,6-bis(dimethylcetylammonium) bromide (16-6-16) and a cationic conventional (monomeric) surfactant, cetyltrimethylammonium bromide (CTAB) have been investigated. The critical micelle concentration (CMC) of the mixed (16-6-16+CTAB) surfactants was measured by the surface tension measurements. The surface properties: viz., the surfactant concentration required to reduce the surface tension by 20 mN/m ( C 20), the surface pressure at the CMC (ΠCMC), the maximum surface excess concentration at the air/water interface (Γmax), the minimum area per surfactant molecule at the air/water interface ( A min), etc. of the mixed micellar surfactant systems were evaluated. In the absence and presence of electrolytes, the thermodynamic parameters of the mixed micellar surfactant systems were also evaluated.

Interfacial behavior of polymer electrolytes

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

Kerr, John; Kerr, John B.; Han, Yong Bong

2003-06-03

Evidence is presented concerning the effect of surfaces on the segmental motion of PEO-based polymer electrolytes in lithium batteries. For dry systems with no moisture the effect of surfaces of nano-particle fillers is to inhibit the segmental motion and to reduce the lithium ion transport. These effects also occur at the surfaces in composite electrodes that contain considerable quantities of carbon black nano-particles for electronic connection. The problem of reduced polymer mobility is compounded by the generation of salt concentration gradients within the composite electrode. Highly concentrated polymer electrolytes have reduced transport properties due to the increased ionic cross-linking. Combinedmore » with the interfacial interactions this leads to the generation of low mobility electrolyte layers within the electrode and to loss of capacity and power capability. It is shown that even with planar lithium metal electrodes the concentration gradients can significantly impact the interfacial impedance. The interfacial impedance of lithium/PEO-LiTFSI cells varies depending upon the time elapsed since current was turned off after polarization. The behavior is consistent with relaxation of the salt concentration gradients and indicates that a portion of the interfacial impedance usually attributed to the SEI layer is due to concentrated salt solutions next to the electrode surfaces that are very resistive. These resistive layers may undergo actual phase changes in a non-uniform manner and the possible role of the reduced mobility polymer layers in dendrite initiation and growth is also explored. It is concluded that PEO and ethylene oxide-based polymers are less than ideal with respect to this interfacial behavior.« less

High-Performance All-Solid-State Na-S Battery Enabled by Casting-Annealing Technology.

PubMed

Fan, Xiulin; Yue, Jie; Han, Fudong; Chen, Ji; Deng, Tao; Zhou, Xiuquan; Hou, Singyuk; Wang, Chunsheng

2018-04-24

Room-temperature all-solid-state Na-S batteries (ASNSBs) using sulfide solid electrolytes are a promising next-generation battery technology due to the high energy, enhanced safety, and earth abundant resources of both sodium and sulfur. Currently, the sulfide electrolyte ASNSBs are fabricated by a simple cold-pressing process leaving with high residential stress. Even worse, the large volume change of S/Na 2 S during charge/discharge cycles induces additional stress, seriously weakening the less-contacted interfaces among the solid electrolyte, active materials, and the electron conductive agent that are formed in the cold-pressing process. The high and continuous increase of the interface resistance hindered its practical application. Herein, we significantly reduce the interface resistance and eliminate the residential stress in Na 2 S cathodes by fabricating Na 2 S-Na 3 PS 4 -CMK-3 nanocomposites using melting-casting followed by stress-release annealing-precipitation process. The casting-annealing process guarantees the close contact between the Na 3 PS 4 solid electrolyte and the CMK-3 mesoporous carbon in mixed ionic/electronic conductive matrix, while the in situ precipitated Na 2 S active species from the solid electrolyte during the annealing process guarantees the interfacial contact among these three subcomponents without residential stress, which greatly reduces the interfacial resistance and enhances the electrochemical performance. The in situ synthesized Na 2 S-Na 3 PS 4 -CMK-3 composite cathode delivers a stable and highly reversible capacity of 810 mAh/g at 50 mA/g for 50 cycles at 60 °C. The present casting-annealing strategy should provide opportunities for the advancement of mechanically robust and high-performance next-generation ASNSBs.

Corrosion protected, multi-layer fuel cell interface

DOEpatents

Feigenbaum, Haim; Pudick, Sheldon; Wang, Chiu L.

1986-01-01

An improved interface configuration for use between adjacent elements of a fuel cell stack. The interface is impervious to gas and liquid and provides resistance to corrosion by the electrolyte of the fuel cell. The multi-layer configuration for the interface comprises a non-cupreous metal-coated metallic element to which is film-bonded a conductive layer by hot pressing a resin therebetween. The multi-layer arrangement provides bridging electrical contact.

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.

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.

Functionally Graded Bismuth Oxide/Zirconia Bilayer Electrolytes for High-Performance Intermediate-Temperature Solid Oxide Fuel Cells (IT-SOFCs).

PubMed

Joh, Dong Woo; Park, Jeong Hwa; Kim, Doyeub; Wachsman, Eric D; Lee, Kang Taek

2017-03-15

A functionally graded Bi 1.6 Er 0.4 O 3 (ESB)/Y 0.16 Zr 0.84 O 1.92 (YSZ) bilayer electrolyte is successfully developed via a cost-effective screen printing process using nanoscale ESB powders on the tape-cast NiO-YSZ anode support. Because of the highly enhanced oxygen incorporation process at the cathode/electrolyte interface, a novel bilayer solid oxide fuel cell (SOFC) yields extremely high power density of ∼2.1 W cm -2 at 700 °C, which is a 2.4 times increase compared to that of the YSZ single electrolyte SOFC.

Electrodeposition of polymer electrolyte in nanostructured electrodes for enhanced electrochemical performance of thin-film Li-ion microbatteries

NASA Astrophysics Data System (ADS)

Salian, Girish D.; Lebouin, Chrystelle; Demoulin, A.; Lepihin, M. S.; Maria, S.; Galeyeva, A. K.; Kurbatov, A. P.; Djenizian, Thierry

2017-02-01

We report that electrodeposition of polymer electrolyte in nanostructured electrodes has a strong influence on the electrochemical properties of thin-film Li-ion microbatteries. Electropolymerization of PMMA-PEG (polymethyl methacrylate-polyethylene glycol) was carried out on both the anode (self-supported titania nanotubes) and the cathode (porous LiNi0.5Mn1.5O4) by cyclic voltammetry and the resulting electrode-electrolyte interface was examined by scanning electron microscopy. The electrochemical characterizations performed by galvanostatic experiments reveal that the capacity values obtained at different C-rates are doubled when the electrodes are completely filled by the polymer electrolyte.

Improved electrochemical performance of spinel LiMn 1.5Ni 0.5O 4 through MgF 2 nano-coating

DOE PAGES

Wu, Qing; Zhang, Xiaoping; Sun, Shuwei; ...

2015-07-08

In this paper, a spinel LiMn 1.5Ni 0.5O 4 (LMNO) cathode material synthesized by a sol–gel method is modified by MgF 2 nano-coating via a wet coating strategy. The results of X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) showed that the MgF 2 nano-coating layers do not physically change the bulk structure of the pristine material. Compared with the pristine compound, the MgF 2-coated LMNO electrodes display enhanced cycling stabilities. Particularly, the 5 wt% MgF 2-coated LMNO demonstrates the best reversibility, with a capacity retention of 89.9% after 100more » cycles, much higher than that of the pristine material, 69.3%. The dQ/dV analysis and apparent Li + diffusion coefficient calculation prove that the kinetic properties are enhanced after MgF 2 surface modification, which partly explains the improved electrochemical performances. Electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) data confirm that the MgF 2 coating layer helps in suppressing the fast growth of the solid electrolyte interface (SEI) film in repeated cycling, which effectively stabilizes the spinel structure. Finally and additionally, differential scanning calorimetry (DSC) tests show that the MgF 2 nano-coating layer also helps in enhancing the thermal stability of the LMNO cathode.« less

Liquid junction schottky barrier solar cell

DOEpatents

Williams, Richard

1980-01-01

A mixture of ceric ions (Ce.sup.+4) and cerous ions (Ce.sup.+3) in an aqueous electrolyte solution forms a Schottky barrier at the interface between an active region of silicon and the electrolyte solution. The barrier height obtained for hydrogenated amorphous silicon using the Ce.sup.+4 /Ce.sup.+3 redox couple is about 1.7 eV.

Electrolyte and Electrode Passivation for Thin Film Batteries

NASA Technical Reports Server (NTRS)

West, W.; Whitacre, J.; Ratnakumar, B.; Brandon, E.; Blosiu, J.; Surampudi, S.

2000-01-01

Passivation films for thin film batteries have been prepared and the conductivity and voltage stability window have been measured. Thin films of Li2CO3 have a large voltage stability window of 4.8V, which facilitates the use of this film as a passivation at both the lithium anode-electrolyte interface at high cathodic potentials.

Hydrophobic interaction and charge accumulation at the diamond-electrolyte interface.

PubMed

Dankerl, M; Lippert, A; Birner, S; Stützel, E U; Stutzmann, M; Garrido, J A

2011-05-13

The hydrophobic interaction of surfaces with water is a well-known phenomenon, but experimental evidence of its influence on biosensor devices has been lacking. In this work we investigate diamond field-effect devices, reporting on Hall effect experiments and complementary simulations of the interfacial potential at the hydrogen-terminated diamond/aqueous electrolyte interface. The interfacial capacitance, derived from the gate-dependent Hall carrier concentration, can be modeled only when considering the hydrophobic nature of this surface and its influence on the structure of interfacial water. Our work demonstrates how profoundly the performance of potentiometric biosensor devices can be affected by their surfaces' hydrophobicity.

Engineering the Interfaces of Superadsorbing Graphene-Based Electrodes with Gas and Electrolyte to Boost Gas Evolution and Activation Reactions.

PubMed

Zhang, Jun-Jun; Lv, Li-Bing; Zhao, Tian-Jian; Lin, Yun-Xiao; Yu, Qiu-Ying; Su, Juan; Hirano, Shin-Ichi; Li, Xin-Hao; Chen, Jie-Sheng

2018-05-30

Electrochemical gas evolution and activation reactions are complicated processes, involving not only active electrocatalysts but also the interaction among solid electrodes, electrolyte, and gas-phase products and reactants. In this study, multiphase interfaces of superadsorbing graphene-based electrodes were controlled without changing the active centers to significantly facilitate mass diffusion kinetics for superior performance. The achieved in-depth understanding of how to regulate the interfacial properties to promote the electrochemical performance could provide valuable clues for electrode manufacture and for the design of more active electrocatalysts. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Calculation of the acid-base equilibrium constants at the alumina/electrolyte interface from the ph dependence of the adsorption of singly charged ions (Na+, Cl-)

NASA Astrophysics Data System (ADS)

Gololobova, E. G.; Gorichev, I. G.; Lainer, Yu. A.; Skvortsova, I. V.

2011-05-01

A procedure was proposed for the calculation of the acid-base equilibrium constants at an alumina/electrolyte interface from experimental data on the adsorption of singly charged ions (Na+, Cl-) at various pH values. The calculated constants (p K {1/0}= 4.1, p K {2/0}= 11.9, p K {3/0}= 8.3, and p K {4/0}= 7.7) are shown to agree with the values obtained from an experimental pH dependence of the electrokinetic potential and the results of potentiometric titration of Al2O3 suspensions.

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.

Impact of isoelectric points of nanopowders in electrolytes on electrochemical characteristics of dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Mohanty, Shyama Prasad; Bhargava, Parag

2012-11-01

Nanoparticle loaded quasi solid electrolytes are important from the view point of developing electrolytes for dye sensitized solar cells (DSSCs) having long term stability. The present work shows the influence of isoelectric point of nanopowders in electrolyte on the photoelectrochemical characteristics of DSSCs. Electrolytes with nanopowders of silica, alumina and magnesia which have widely differing isoelectric points are used in the study. Adsorption of ions from the electrolyte on the nanopowder surface, characterized by zeta potential measurement, show that cations get adsorbed on silica, alumina surface while anions get adsorbed on magnesia surface. The electrochemical characteristics of nanoparticulate loaded electrolytes are examined through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). DSSCs fabricated using liquid, silica or alumina loaded electrolytes exhibit almost similar performance. But interestingly, the magnesia loaded electrolyte-based cell show lower short circuit current density (JSC) and much higher open circuit voltage (VOC), which is attributed to adsorption of anions. Such anionic adsorption prevents the dark reaction in magnesia loaded electrolyte-based cell and thus, enhances the VOC by almost 100 mV as compared to liquid electrolyte based cell. Also, higher electron life time at the titania/electrolyte interface is observed in magnesia loaded electrolyte-based cell as compared to others.

Light-Induced Surface Reactions at the Bismuth Vanadate/Potassium Phosphate Interface.

PubMed

Favaro, Marco; Abdi, Fatwa F; Lamers, Marlene; Crumlin, Ethan J; Liu, Zhi; van de Krol, Roel; Starr, David E

2018-01-18

Bismuth vanadate has recently drawn significant research attention as a light-absorbing photoanode due to its performance for photoelectrochemical water splitting. In this study, we use in situ ambient pressure X-ray photoelectron spectroscopy with "tender" X-rays (4.0 keV) to investigate a polycrystalline bismuth vanadate (BiVO 4 ) electrode in contact with an aqueous potassium phosphate (KPi) solution at open circuit potential under both dark and light conditions. This is facilitated by the creation of a 25 to 30 nm thick electrolyte layer using the "dip-and-pull" method. We observe that under illumination bismuth phosphate forms on the BiVO 4 surface leading to an increase of the surface negative charge. The bismuth phosphate layer may act to passivate surface states observed in photoelectrochemical measurements. The repulsive interaction between the negatively charged surface under illumination and the phosphate ions in solution causes a shift in the distribution of ions in the thin aqueous electrolyte film, which is observed as an increase in their photoelectron signals. Interestingly, we find that such changes at the BiVO 4 /KPi electrolyte interface are reversible upon returning to dark conditions. By measuring the oxygen 1s photoelectron peak intensities from the phosphate ions and liquid water as a function of time under dark and light conditions, we determine the time scales for the forward and reverse reactions. Our results provide direct evidence for light-induced chemical modification of the BiVO 4 /KPi electrolyte interface.

The impact of electrolyte on the adsorption of the anionic surfactant methyl ester sulfonate at the air-solution interface: Surface multilayer formation.

PubMed

Xu, H; Thomas, R K; Penfold, J; Li, P X; Ma, K; Welbourne, R J L; Roberts, D W; Petkov, J T

2018-02-15

The methyl ester sulfonates represent a promising group of anionic surfactants which have the potential for improved performance and biocompatibility in a range of applications. Their solution properties, in particular their tolerance to hard water, suggests that surface ordering may occur in the presence of multi-valent counterion. Understanding their adsorption properties in a range of different circumstances is key to the exploitation of their potential. Neutron reflectivity and surface tension have been used to characterise the adsorption at the air-aqueous solution interface of the anionic surfactant sodium tetradecanoic 2-sulfo 1-methyl ester, C 14 MES, in the absence of electrolyte and in the presence of mono, di, and tri-valent counterions, Na + , Ca 2+ , and Al 3+ . In particular the emphasis has been on exploring the tendency to form layered structures at the interface. In the absence of electrolyte and in the presence of NaCl and CaCl 2 and AlCl 3 at low concentrations monolayer adsorption is observed, and the addition of electrolyte results in enhanced adsorption. In the presence of NaCl and CaCl 2 only monolayer adsorption is observed. However at higher AlCl 3 concentrations surface multilayer formation is observed, in which the number of bilayers at the surface depends upon the surfactant and AlCl 3 concentrations. Copyright © 2017 Elsevier Inc. All rights reserved.

First-principles estimates of free energy barriers for Mg desolvation and intercalation at electrolyte/electrode interfaces

NASA Astrophysics Data System (ADS)

Wan, Liwen; Prendergast, David

2014-03-01

There is a growing interest in developing multivalent ion batteries that could, in principle, double or triple the energy density compared to the monovalent Li-ion batteries. However, the strong electrostatic interaction caused by the extra charge also makes it very challenging to find appropriate intercalation compounds that allow for relatively fast and reversible ion transport. An established working multivalent battery is comprised of Mg(AlCl2BuEt)2 salts in THF solution as the electrolyte, and Mg metal and Mo6S8 Chevrel phase as the anode and cathode, respectively. Currently, we lack a clear understanding of the mechanism for Mg desolvation and intercalation at the interface between the electrolyte and Chevrel phase surfaces, which is critical in designing new advanced battery systems with improved ion diffusion rate. Here, we present a theoretical investigation of the dynamics and kinetics of the Mg desolvation/intercalation process. The surface properties of Mo6S8 are studied for the first time using density functional theory (DFT) and its interaction with the electrolyte is simulated via an ab initio molecular dynamics (AIMD) approach. The free energy barrier for Mg diffusing through the interface is then calculated by performing a set of biased AIMD simulations. This work is supported as part of the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences.

Ni-SDC cermet anode for medium-temperature solid oxide fuel cell with lanthanum gallate electrolyte

NASA Astrophysics Data System (ADS)

Zhang, Xinge; Ohara, Satoshi; Maric, Radenka; Mukai, Kazuo; Fukui, Takehisa; Yoshida, Hiroyuki; Nishimura, Masayoshi; Inagaki, Toru; Miura, Kazuhiro

The polarization properties and microstructure of Ni-SDC (samaria-doped ceria) cermet anodes prepared from spray pyrolysis (SP) composite powder, and element interface diffusion between the anode and a La 0.9Sr 0.1Ga 0.8Mg 0.2O 3- δ (LSGM) electrolyte are investigated as a function of anode sintering temperature. The anode sintered at 1250°C displays minimum anode polarization (with anode ohmic loss), while the anode prepared at 1300°C has the best electrochemical overpotential, viz., 27 mV at 300 mA cm -2 operating at 800°C. The anode ohmic loss gradually increases with increase in the sintering temperature at levels below 1300°C, and sharply increases at 1350°C. Electron micrographs show a clear grain growth at sintering temperatures higher than 1300°C. The anode microstructure appears to be optimized at 1300°C, in which nickel particles form a network with well-connected SDC particles finely distributed over the surfaces of the nickel particles. The anode sintered at 1350°C has severe grain growth and an apparent interface diffusion of nickel from the anode to the electrolyte. The nickel interface diffusion is assumed to be the main reason for the increment in ohmic loss, and the resulting loss in anode performance. The findings suggest that sintering Ni-SDC composite powder near 1250°C is the best method to prepare the anode on a LSGM electrolyte.

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

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.

Distributed Object Technology with CORBA and Java: Key Concepts and Implications.

DTIC Science & Technology

1997-06-01

commercial use should be addressed to the SEI Licensing Agent. NO WARRANTY THIS CARNEGIE MELLON UNIVERSITY AND SOFTWARE ENGINEERING INSTITUTE MATERIAL...retrieval. This power is not derived from the language per se, but from the architecture-neutral approach used by Java. The Java Virtual Machine...pattern that is focused on performance considerations, the PCo archi- tecture also uses CORBA interface definition language (IDL) to model the

Improving Quality Using Architecture Fault Analysis with Confidence Arguments

DTIC Science & Technology

2015-03-01

CMU/SEI-2015-TR-006 | SOFTWARE ENGINEERING INSTITUTE | CARNEGIE MELLON UNIVERSITY iii List of Figures Figure 1: Architecture-Centric...Requirements Decomposition 5 Figure 2: A System and Its Interface with Its Environment 6 Figure 3: AADL Graphical Symbols 8 Figure 4: Textual AADL Example...8 Figure 5: Textual AADL Error Model Example 9 Figure 6: Potential Hazard Sources in the Feedback Control Loop [Leveson 2012] 11 Figure 7

Electrokinetics of diffuse soft interfaces. 1. Limit of low Donnan potentials.

PubMed

Duval, Jérôme F L; van Leeuwen, Herman P

2004-11-09

The current theoretical approaches to electrokinetics of gels or polyelectrolyte layers are based on the assumption that the position of the very interface between the aqueous medium and the gel phase is well defined. Within this assumption, spatial profiles for the volume fraction of polymer segments (phi), the density of fixed charges in the porous layer (rho fix), and the coefficient modeling the friction to hydrodynamic flow (k) follow a step-function. In reality, the "fuzzy" nature of the charged soft layer is intrinsically incompatible with the concept of a sharp interface and therefore necessarily calls for more detailed spatial representations for phi, rho fix, and k. In this paper, the notion of diffuse interface is introduced. For the sake of illustration, linear spatial distributions for phi and rho fix are considered in the interfacial zone between the bulk of the porous charged layer and the bulk electrolyte solution. The corresponding distribution for k is inferred from the Brinkman equation, which for low phi reduces to Stokes' equation. Linear electrostatics, hydrodynamics, and electroosmosis issues are analytically solved within the context of streaming current and streaming potential of charged surface layers in a thin-layer cell. The hydrodynamic analysis clearly demonstrates the physical incorrectness of the concept of a discrete slip plane for diffuse interfaces. For moderate to low electrolyte concentrations and nanoscale spatial transition of phi from zero (bulk electrolyte) to phi o (bulk gel), the electrokinetic properties of the soft layer as predicted by the theory considerably deviate from those calculated on the basis of the discontinuous approximation by Ohshima.

Anomalously enhanced hydration of aqueous electrolyte solution in hydrophobic carbon nanotubes to maintain stability.

PubMed

Ohba, Tomonori

2014-02-24

An understanding of the structure and behavior of electrolyte solutions in nanoenvironements is crucial not only for a wide variety of applications, but also for the development of physical, chemical, and biological processes. We demonstrate the structure and stability of electrolyte in carbon nanotubes using hybrid reverse Monte Carlo simulations of X-ray diffraction patterns. Hydrogen bonds between water are adequately formed in carbon nanotubes, although some hydrogen bonds are restricted by the interfaces of carbon nanotubes. The hydrogen bonding network of water in electrolyte in the carbon nanotubes is further weakened. On the other hand, formation of the ion hydration shell is significantly enhanced in the electrolyte in the carbon nanotubes in comparison to ion hydration in bulk electrolyte. The significant hydrogen bond and hydration shell formation are a result of gaining stability in the hydrophobic nanoenvironment. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical performance of a solvent-free hybrid ceramic-polymer electrolyte based on Li7La3Zr2O12 in P(EO)15LiTFSI

NASA Astrophysics Data System (ADS)

Keller, Marlou; Appetecchi, Giovanni Battista; Kim, Guk-Tae; Sharova, Varvara; Schneider, Meike; Schuhmacher, Jörg; Roters, Andreas; Passerini, Stefano

2017-06-01

The preparation of hybrid ceramic-polymer electrolytes, consisting of 70 wt% of Li+ cation conducting Li7La3Zr2O12 (LLZO) and 30 wt% of P(EO)15LiTFSI polymer electrolyte, through a solvent-free procedure is reported. The LLZO-P(EO)15LiTFSI hybrid electrolytes exhibit remarkable improvement in terms of flexibility and processability with respect to pure LLZO ceramic electrolytes. The physicochemical and electrochemical investigation shows the effect of LLZO annealing, resulting in ion conduction gain. However, slow charge transfer at the ceramic-polymer interface is also observed especially at higher temperatures. Nevertheless, improved compatibility with lithium metal anodes and good Li stripping/plating behavior are exhibited by the LLZO-P(EO)15LiTFSI hybrid electrolytes with respect to P(EO)15LiTFSI.

Design and synthesis of guest-host nanostructures to enhance ionic conductivity across nanocomposite membranes

DOEpatents

Hu, Michael Z [Knoxville, TN; Kosacki, Igor [Oak Ridge, TN

2010-01-05

An ion conducting membrane has a matrix including an ordered array of hollow channels and a nanocrystalline electrolyte contained within at least some or all of the channels. The channels have opposed open ends, and a channel width of 1000 nanometers or less, preferably 60 nanometers or less, and most preferably 10 nanometers or less. The channels may be aligned perpendicular to the matrix surface, and the length of the channels may be 10 nanometers to 1000 micrometers. The electrolyte has grain sizes of 100 nanometers or less, and preferably grain sizes of 1 to 50 nanometers. The electrolyte may include grains with a part of the grain boundaries aligned with inner walls of the channels to form a straight oriented grain-wall interface or the electrolyte may be a single crystal. In one form, the electrolyte conducts oxygen ions, the matrix is silica, and the electrolyte is yttrium doped zirconia.

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

Controls of ionic strength and macromolecule chemistry on calcite nucleation: Salinity and ion hydration as levers for regulating biomineralization

NASA Astrophysics Data System (ADS)

Dove, P. M.; Giuffre, A. J.; Mergelsberg, S. T.; Han, N.; De Yoreo, J. J.

2016-12-01

Organisms form shells and skeletons with remarkable fidelity by controlling the timing and placement of the minerals that nucleate and subsequently grow. An extensive effort has identified features of the organic matrix that regulate this process. Recent measurements from our group show the energy barrier to nucleation onto polysaccharide (PS) substrates is dependent upon hydrophilicity through functional group chemistry and suggest that free energy of the macromolecule-liquid interface influences where and when mineral nucleation occurs (Giuffre et al., 2013, PNAS). The importance of interfacial free energy in regulating nucleation raises the question of whether local changes in salinity or electrolyte composition can be tuned to further modulate the onset of calcite nucleation. Using alginate (negatively charged by carboxyl groups) and chitosan (small positive charge by amine groups), the rate of calcite nucleation was measured at controlled supersaturations and pH as a function of NaCl concentration (65-600 mM). Analyses of the data show the thermodynamic barrier to calcite nucleation onto both types of PS increases with ionic strength. The evidence suggests this effect arises from an increasing concentration of solvated ions at the PS-water interface while also increasing the hydrophilic character of that interface; thus decreasing the substrate-liquid interfacial free energy. To test this explanation, a second group of nucleation experiments used a suite of electrolytes (alkali chlorides for alginate and sodium halides for chitosan) while holding ionic strength constant. Indeed, the nucleation barriers for calcite formation are electrolyte-specific and correlated with the hydration free energy of the ion. This suggests solvated electrolyte ions indirectly regulate calcite nucleation onto substrates through their competition with the substrate for water thereby influencing net interfacial free energy. These effects are consistent with the long-established salting-in phenomena of the Hofmeister series. The new insights from this experimental study reiterate the importance of electrolytes in reactions involving mineral-water interfaces and suggest a role for seemingly inert `spectator' ions in regulating the local timing and placement of minerals during biomineralization.

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.

Micellar Electrolytes in Organic Electrochemical Transistors

NASA Astrophysics Data System (ADS)

Cicoira, Fabio; Giuseppe, Tarabella; Nanda, Gaurav; Iannotta, Salvatore; Santato, Clara

2012-02-01

Organic electrochemical transistors (OECTs) are promising for applications in sensing and bioelectronics. OECTs consist of a conducting polymer film (transistor channel) in contact with an electrolyte. A gate electrode immersed in the electrolyte controls the doping/dedoping level of the conducting polymer. OECTs can be operated in aqueous electrolytes, making possible the implementation of organic electronic materials at the interface with biology. The inherent signal amplification of OECTs has the potential to yield sensors with low detection limits and high sensitivity. In this talk we will present recent studies on OECTs using ionic surfactants (such as hexadecyl-trimethyl-ammonium bromide) as electrolytes. As the conducting polymer we used PEDOT:PSS, i.e. (Poly,3-4 ethylenedioxythiopene) doped with Poly(styrene sulphonate). Interestingly, ionic surfactant electrolytes result in large transistor current modulation, especially beyond the critical micellar concentration (CMC). Since micelles play a primary role in biological processes and drug-delivery systems, the use for micellar electrolytes opens new exciting opportunities for the use of OECTs in bioelectronics.

Current limit diagrams for dendrite formation in solid-state electrolytes for Li-ion batteries

NASA Astrophysics Data System (ADS)

Raj, R.; Wolfenstine, J.

2017-03-01

We build upon the concept that nucleation of lithium dendrites at the lithium anode-solid state electrolyte interface is instigated by the higher resistance of grain boundaries that raises the local electro-chemical potential of lithium, near the lithium-electrode. This excess electro-chemo-mechanical potential, however, is reduced by the mechanical back stress generated when the dendrite is formed within the electrolyte. These parameters are coalesced into an analytical model that prescribes a specific criterion for dendrite formation. The results are presented in the form of current limit diagrams that show the "safe" and "fail" regimes for battery function. A higher conductivity of the electrolyte can reduce dendrite formation.

Exactly solvable model of the two-dimensional electrical double layer.

PubMed

Samaj, L; Bajnok, Z

2005-12-01

We consider equilibrium statistical mechanics of a simplified model for the ideal conductor electrode in an interface contact with a classical semi-infinite electrolyte, modeled by the two-dimensional Coulomb gas of pointlike unit charges in the stability-against-collapse regime of reduced inverse temperatures 0< or = beta < 2. If there is a potential difference between the bulk interior of the electrolyte and the grounded electrode, the electrolyte region close to the electrode (known as the electrical double layer) carries some nonzero surface charge density. The model is mappable onto an integrable semi-infinite sine-Gordon theory with Dirichlet boundary conditions. The exact form-factor and boundary state information gained from the mapping provide asymptotic forms of the charge and number density profiles of electrolyte particles at large distances from the interface. The result for the asymptotic behavior of the induced electric potential, related to the charge density via the Poisson equation, confirms the validity of the concept of renormalized charge and the corresponding saturation hypothesis. It is documented on the nonperturbative result for the asymptotic density profile at a strictly nonzero beta that the Debye-Hückel beta-->0 limit is a delicate issue.

An Electrochemical, Microtopographical and Ambient Pressure X-Ray Photoelectron Spectroscopic Investigation of Si/TiO 2/Ni/Electrolyte Interfaces

DOE PAGES

Lichterman, Michael F.; Richter, Matthias H.; Hu, Shu; ...

2015-12-05

The electrical and spectroscopic properties of the TiO 2/Ni protection layer system, which enables stabilization of otherwise corroding photoanodes, have been investigated in contact with electrolyte solutions by scanning-probe microscopy, electrochemistry and in-situ ambient pressure X-ray photoelectron spectroscopy (AP-XPS). Specifically, the energy-band relations of the p +-Si/ALD-TiO 2/Ni interface have been determined for a selected range of Ni thicknesses. AP-XPS measurements using tender X-rays were performed in a three-electrode electrochemical arrangement under potentiostatic control to obtain information from the semiconductor near-surface region, the electrochemical double layer (ECDL) and the electrolyte beyond the ECDL. The degree of conductivity depended on themore » chemical state of the Ni on the TiO 2 surface. At low loadings of Ni, the Ni was present primarily as an oxide layer and the samples were not conductive, although the TiO 2 XPS core levels nonetheless displayed behavior indicative of a metal-electrolyte junction. In contrast, as the Ni thickness increased, the Ni phase was primarily metallic and the electrochemical behavior became highly conductive, with the AP-XPS data indicative of a metal-electrolyte junction. Electrochemical and microtopographical methods have been employed to better define the nature of the TiO 2/Ni electrodes and to contextualize the AP-XPS results.« 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.

Prospects for reducing the processing cost of lithium ion batteries

DOE PAGES

Wood III, David L.; Li, Jianlin; Daniel, Claus

2014-11-06

A detailed processing cost breakdown is given for lithium-ion battery (LIB) electrodes, which focuses on: elimination of toxic, costly N-methylpyrrolidone (NMP) dispersion chemistry; doubling the thicknesses of the anode and cathode to raise energy density; and, reduction of the anode electrolyte wetting and SEI-layer formation time. These processing cost reduction technologies generically adaptable to any anode or cathode cell chemistry and are being implemented at ORNL. This paper shows step by step how these cost savings can be realized in existing or new LIB manufacturing plants using a baseline case of thin (power) electrodes produced with NMP processing and amore » standard 10-14-day wetting and formation process. In particular, it is shown that aqueous electrode processing can cut the electrode processing cost and energy consumption by an order of magnitude. Doubling the thickness of the electrodes allows for using half of the inactive current collectors and separators, contributing even further to the processing cost savings. Finally wetting and SEI-layer formation cost savings are discussed in the context of a protocol with significantly reduced time. These three benefits collectively offer the possibility of reducing LIB pack cost from $502.8 kWh-1-usable to $370.3 kWh-1-usable, a savings of $132.5/kWh (or 26.4%).« less

Direct Mapping of Band Positions in Doped and Undoped Hematite during Photoelectrochemical Water Splitting

DOE PAGES

Shavorskiy, Andrey; Ye, Xiaofei; Karslgolu, Osman; ...

2017-10-30

Photoelectrochemical water splitting is a promising pathway for the direct conversion of renewable solar energy to easy to store and use chemical energy. The performance of a photoelectrochemical device is determined in large part by the heterogeneous interface between the photoanode and the electrolyte, which we here characterize directly under operating conditions using interface-specific probes. Utilizing X-ray photoelectron spectroscopy as a noncontact probe of local electrical potentials, we demonstrate direct measurements of the band alignment at the semiconductor/electrolyte interface of an operating hematite/KOH photoelectrochemical cell as a function of solar illumination, applied potential, and doping. Here, we provide evidence formore » the absence of in-gap states in this system, which is contrary to previous measurements using indirect methods, and give a comprehensive description of shifts in the band positions and limiting processes during the photoelectrochemical reaction.« less

Effective Infiltration of Gel Polymer Electrolyte into Silicon-Coated Vertically Aligned Carbon Nanofibers as Anodes for Solid-State Lithium-Ion Batteries.

PubMed

Pandey, Gaind P; Klankowski, Steven A; Li, Yonghui; Sun, Xiuzhi Susan; Wu, Judy; Rojeski, Ronald A; Li, Jun

2015-09-23

This study demonstrates the full infiltration of gel polymer electrolyte into silicon-coated vertically aligned carbon nanofibers (Si-VACNFs), a high-capacity 3D nanostructured anode, and the electrochemical characterization of its properties as an effective electrolyte/separator for future all-solid-state lithium-ion batteries. Two fabrication methods have been employed to form a stable interface between the gel polymer electrolyte and the Si-VACNF anode. In the first method, the drop-casted gel polymer electrolyte is able to fully infiltrate into the open space between the vertically aligned core-shell nanofibers and encapsulate/stabilize each individual nanofiber in the polymer matrix. The 3D nanostructured Si-VACNF anode shows a very high capacity of 3450 mAh g(-1) at C/10.5 (or 0.36 A g(-1)) rate and 1732 mAh g(-1) at 1C (or 3.8 A g(-1)) rate. In the second method, a preformed gel electrolyte film is sandwiched between an Si-VACNF electrode and a Li foil to form a half-cell. Most of the vertical core-shell nanofibers of the Si-VACNF anode are able to penetrate into the gel polymer film while retaining their structural integrity. The slightly lower capacity of 2800 mAh g(-1) at C/11 rate and ∼1070 mAh g(-1) at C/1.5 (or 2.6 A g(-1)) rate have been obtained, with almost no capacity fade for up to 100 cycles. Electrochemical impedance spectroscopy does not show noticeable changes after 110 cycles, further revealing the stable interface between the gel polymer electrolyte and the Si-VACNFs anode. These results show that the infiltrated flexible gel polymer electrolyte can effectively accommodate the stress/strain of the Si shell due to the large volume expansion/contraction during the charge-discharge processes, which is particularly useful for developing future flexible solid-state lithium-ion batteries incorporating Si-anodes.

Sub-0.5 V Highly Stable Aqueous Salt Gated Metal Oxide Electronics

PubMed Central

Park, Sungjun; Lee, SeYeong; Kim, Chang-Hyun; Lee, Ilseop; Lee, Won-June; Kim, Sohee; Lee, Byung-Geun; Jang, Jae-Hyung; Yoon, Myung-Han

2015-01-01

Recently, growing interest in implantable bionics and biochemical sensors spurred the research for developing non-conventional electronics with excellent device characteristics at low operation voltages and prolonged device stability under physiological conditions. Herein, we report high-performance aqueous electrolyte-gated thin-film transistors using a sol-gel amorphous metal oxide semiconductor and aqueous electrolyte dielectrics based on small ionic salts. The proper selection of channel material (i.e., indium-gallium-zinc-oxide) and precautious passivation of non-channel areas enabled the development of simple but highly stable metal oxide transistors manifested by low operation voltages within 0.5 V, high transconductance of ~1.0 mS, large current on-off ratios over 107, and fast inverter responses up to several hundred hertz without device degradation even in physiologically-relevant ionic solutions. In conjunction with excellent transistor characteristics, investigation of the electrochemical nature of the metal oxide-electrolyte interface may contribute to the development of a viable bio-electronic platform directly interfacing with biological entities in vivo. PMID:26271456

Electrochemical impedance spectroscopy of lithium-titanium disulfide rechargeable cells

NASA Technical Reports Server (NTRS)

Narayanan, S. R.; Shen, D. H.; Surampudi, S.; Attia, A. I.; Halpert, G.

1993-01-01

The two-terminal alternating current impedance of Li/TiS2 rechargeable cells was studied as a function of frequency, state-of-charge, and extended cycling. Analysis based on a plausible equivalent circuit model for the Li/TiS2 cell leads to evaluation of kinetic parameters for the various physicochemical processes occurring at the electrode/electrolyte interfaces. To investigate the causes of cell degradation during extended cycling, the parameters evaluated for cells cycled 5 times were compared with the parameters of cells cycled over 600 times. The findings are that the combined ohmic resistance of the electrolyte and electrodes suffers a tenfold increase after extended cycling, while the charge-transfer resistance and diffusional impedance at the TiS2/electrolyte interface are not significantIy affected. The results reflect the morphological change and increase in area of the anode due to cycling. The study also shows that overdischarge of a cathode-limited cell causes a decrease in the diffusion coefficient of the lithium ion in the cathode.

Pulsed Electrochemical Mass Spectrometry for Operando Tracking of Interfacial Processes in Small-Time-Constant Electrochemical Devices such as Supercapacitors.

PubMed

Batisse, Nicolas; Raymundo-Piñero, Encarnación

2017-11-29

A more detailed understanding of the electrode/electrolyte interface degradation during the charging cycle in supercapacitors is of great interest for exploring the voltage stability range and therefore the extractable energy. The evaluation of the gas evolution during the charging, discharging, and aging processes is a powerful tool toward determining the stability and energy capacity of supercapacitors. Here, we attempt to fit the gas analysis resolution to the time response of a low-gas-generation power device by adopting a modified pulsed electrochemical mass spectrometry (PEMS) method. The pertinence of the method is shown using a symmetric carbon/carbon supercapacitor operating in different aqueous electrolytes. The differences observed in the gas levels and compositions as a function of the cell voltage correlate to the evolution of the physicochemical characteristics of the carbon electrodes and to the electrochemical performance, giving a complete picture of the processes taking place at the electrode/electrolyte interface.

Nanoscaled Na3PS4 Solid Electrolyte for All-Solid-State FeS2/Na Batteries with Ultrahigh Initial Coulombic Efficiency of 95% and Excellent Cyclic Performances.

PubMed

Wan, Hongli; Mwizerwa, Jean Pierre; Qi, Xingguo; Xu, Xiaoxiong; Li, Hong; Zhang, Qiang; Cai, Liangting; Hu, Yong-Sheng; Yao, Xiayin

2018-04-18

Nanosized Na 3 PS 4 solid electrolyte with an ionic conductivity of 8.44 × 10 -5 S cm -1 at room temperature is synthesized by a liquid-phase reaction. The resultant all-solid-state FeS 2 /Na 3 PS 4 /Na batteries show an extraordinary high initial Coulombic efficiency of 95% and demonstrate high energy density of 611 Wh kg -1 at current density of 20 mA g -1 at room temperature. The outstanding performances of the battery can be ascribed to good interface compatibility and intimate solid-solid contact at FeS 2 electrode/nanosized Na 3 PS 4 solid electrolytes interface. Meanwhile, excellent cycling stability is achieved for the battery after cycling at 60 mA g -1 for 100 cycles, showing a high capacity of 287 mAh g -1 with the capacity retention of 80%.

In Situ STEM-EELS observation of nanoscale interfacial phenomena in all-solid-state batteries

DOE PAGES

Wang, Ziying; Santhanagopalan, Dhamodaran; Zhang, Wei; ...

2016-05-03

Behaviors of functional interfaces are crucial factors in the performance and safety of energy storage and conversion devices. Indeed, solid electrode–solid electrolyte interfacial impedance is now considered the main limiting factor in all-solid-state batteries rather than low ionic conductivity of the solid electrolyte. In this paper, we present a new approach to conducting in situ scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) in order to uncover the unique interfacial phenomena related to lithium ion transport and its corresponding charge transfer. Our approach allowed quantitative spectroscopic characterization of a galvanostatically biased electrochemical system under in situmore » conditions. Using a LiCoO 2/LiPON/Si thin film battery, an unexpected structurally disordered interfacial layer between LiCoO 2 cathode and LiPON electrolyte was discovered to be inherent to this interface without cycling. During in situ charging, spectroscopic characterization revealed that this interfacial layer evolved to form highly oxidized Co ions species along with lithium oxide and lithium peroxide species. These findings suggest that the mechanism of interfacial impedance at the LiCoO 2/LiPON interface is caused by chemical changes rather than space charge effects. Finally, insights gained from this technique will shed light on important challenges of interfaces in all-solid-state energy storage and conversion systems and facilitate improved engineering of devices operated far from equilibrium.« 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.

Abuse Tolerance Improvements

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

Orendorff, Christopher J.; Nagasubramanian, Ganesan; Fenton, Kyle R.

As lithium-ion battery technologies mature, the size and energy of these systems continues to increase (> 50 kWh for EVs); making safety and reliability of these high energy systems increasingly important. While most material advances for lithium-ion chemistries are directed toward improving cell performance (capacity, energy, cycle life, etc.), there are a variety of materials advancements that can be made to improve lithium-ion battery safety. Issues including energetic thermal runaway, electrolyte decomposition and flammability, anode SEI stability, and cell-level abuse tolerance continue to be critical safety concerns. This report highlights work with our collaborators to develop advanced materials to improvemore » lithium-ion battery safety and abuse tolerance and to perform cell-level characterization of new materials.« less

Sustainable Interfaces between Si Anodes and Garnet Electrolytes for Room-Temperature Solid-State Batteries.

PubMed

Chen, Cheng; Li, Quan; Li, Yiqiu; Cui, Zhonghui; Guo, Xiangxin; Li, Hong

2018-01-17

Solid-state batteries (SSBs) have seen a resurgence of research interests in recent years for their potential to offer high energy density and excellent safety far beyond current commercialized lithium-ion batteries. The compatibility of Si anodes and Ta-doped Li 7 La 3 Zr 2 O 12 (Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 , LLZTO) solid electrolytes and the stability of the Si anode have been investigated. It is found that Si layer anodes thinner than 180 nm can maintain good contact with the LLZTO plate electrolytes, leading the Li/LLZTO/Si cells to exhibit excellent cycling performance with a capacity retention over 85% after 100 cycles. As the Si layer thickness is increased to larger than 300 nm, the capacity retention of Li/LLZTO/Si cells becomes 77% after 100 cycles. When the thickness is close to 900 nm, the cells can cycle only for a limited number of times because of the destructive volume change at the interfaces. Because of the sustainable Si/LLZTO interfaces with the Si layer anodes with a thickness of 180 nm, full cells with the LiFePO 4 cathodes show discharge capacities of 120 mA h g -1 for LiFePO 4 and 2200 mA h g -1 for the Si anodes at room temperature. They cycle 100 times with a capacity retention of 72%. These results indicate that the combination between the Si anodes and the garnet electrolytes is a promising strategy for constructing high-performance SSBs.

In situ monitoring magnetism and resistance of nanophase platinum upon electrochemical oxidation.

PubMed

Steyskal, Eva-Maria; Topolovec, Stefan; Landgraf, Stephan; Krenn, Heinz; Würschum, Roland

2013-01-01

Controlled tuning of material properties by external stimuli represents one of the major topics of current research in the field of functional materials. Electrochemically induced property tuning has recently emerged as a promising pathway in this direction making use of nanophase materials with a high fraction of electrode-electrolyte interfaces. The present letter reports on electrochemical property tuning of porous nanocrystalline Pt. Deeper insight into the underlying processes could be gained by means of a direct comparison of the charge-induced response of two different properties, namely electrical resistance and magnetic moment. For this purpose, four-point resistance measurements and SQUID magnetometry were performed under identical in situ electrochemical control focussing on the regime of electrooxidation. Fully reversible variations of the electrical resistance and the magnetic moment of 6% and 1% were observed upon the formation or dissolution of a subatomic chemisorbed oxygen surface layer, respectively. The increase of the resistance, which is directly correlated to the amount of deposited oxygen, is considered to be primarily caused by charge-carrier scattering processes at the metal-electrolyte interfaces. In comparison, the decrease of the magnetic moment upon positive charging appears to be governed by the electric field at the nanocrystallite-electrolyte interfaces due to spin-orbit coupling.

Use of Tween Polymer To Enhance the Compatibility of the Li/Electrolyte Interface for the High-Performance and High-Safety Quasi-Solid-State Lithium-Sulfur Battery.

PubMed

Liu, Jie; Qian, Tao; Wang, Mengfan; Zhou, Jinqiu; Xu, Na; Yan, Chenglin

2018-06-07

Lithium metal batteries have attracted increasing attention recently due to their particular advantages in energy density. However, as for their practical application, the development of solid-state lithium metal batteries is restricted because of the poor Li/electrolyte interface, low Li-ion conductivity, and irregular growth of Li dendrites. To address the above issues, we herein report a high Li-ion conductivity and compatible polymeric interfacial layer by grafting tween-20 on active lithium metal. Sequential oxyethylene groups in tween-grafted Li (TG-Li) improve the ion conductivity and the compatibility of the Li/electrolyte interface, which enables low overpotentials and stable performance over 1000 cycles. Consequently, the poly(ethylene oxide)-based solid-state lithium-sulfur battery with TG-Li exhibits a high reversible capacity of 1051.2 mA h g -1 at 0.2 C (1 C = 1675 mA h g -1 ) and excellent stability for 500 cycles at 2 C. The decreasing concentration of the sulfur atom with increasing Ar + sputtering depth indicates that the polymer interfacial layer works well in suppressing polysulfide reduction to Li 2 S/Li 2 S 2 on the metallic Li surface even after long-term cycling.

Molecular Engineering toward Stabilized Interface: An Electrolyte Additive for High-Performance Li-Ion Battery

DOE PAGES

Zhang, Lu; Huang, Jinhua; Youssef, Kyrrilos; ...

2014-10-31

A novel electrolyte additive, 3-oxabicyclo[3.1.0]hexane-2,4-dione (OHD), has been discovered and evaluated in Li- 1.1(Mn 1/3Ni 1/3Co 1/3) 0.9O 2/graphite cells under elevated temperature. When an appropriate amount of OHD is used, the cell capacity retention is improved from 60% (Gen 2 electrolyte alone) to 82% (Gen 2 electrolyte plus OHD) after 200 cycles with no obvious impedance increase. The amount of OHD added is the key to achieving the superior cell performance. In conclusion, the effect of OHD additive was investigated by means of electrochemical analysis, fourier transform infrared spectroscopy, scanning electron microscopy, and density functional theory computation.

A sealed optical cell for the study of lithium-electrode|electrolyte interfaces

NASA Astrophysics Data System (ADS)

Howlett, P. C.; MacFarlane, D. R.; Hollenkamp, A. F.

A sealed, symmetrical, lithium optical cell, which enables optical images of lithium surface deposits and in situ Raman spectra to be obtained simply and conveniently during charge-discharge cycling of lithium metal electrodes, has been designed and tested. A conventional aprotic liquid, 1 M lithium hexafluorophosphate in propylene carbonate, and an experimental ionic liquid, 20 mol% lithium bis(trifluoromethanesulfonyl)amide in 1-ethyl 3-methyl imidazolium bis(trifluoromethanesulfonyl)amide, are investigated as electrolyte solutions. Images obtained from the cell with the former electrolyte solution demonstrate the problems associated with cycling lithium metal electrodes. Images obtained with the latter electrolyte solution provide clear evidence that continued investigation of ionic liquids for use with lithium metal electrodes is warranted. Operation of the cell with the conventional electrolyte yields Raman spectra of good quality. The spectra display vibrational modes which arise from the electrolyte, as well as several additional modes which are associated with the deposits formed during cycling.

Ionic Structure at Dielectric Interfaces

NASA Astrophysics Data System (ADS)

Jing, Yufei

The behavior of ions in liquids confined between macromolecules determines the outcome of many nanoscale assembly processes in synthetic and biological materials such as colloidal dispersions, emulsions, hydrogels, DNA, cell membranes, and proteins. Theoretically, the macromolecule-liquid boundary is often modeled as a dielectric interface and an important quantity of interest is the ionic structure in a liquid confined between two such interfaces. The knowledge gleaned from the study of ionic structure in such models can be useful in several industrial applications, such as biosensors, lithium-ion batteries double-layer supercapacitors for energy storage and seawater desalination. Electrostatics plays a critical role in the development of such functional materials. Many of the functions of these materials, result from charge and composition heterogeneities. There are great challenges in solving electrostatics problems in heterogeneous media with arbitrary shapes because electrostatic interactions remains unknown but depend on the particular density of charge distributions. Charged molecules in heterogeneous media affect the media's dielectric response and hence the interaction between the charges is unknown since it depends on the media and on the geometrical properties of the interfaces. To determine the properties of heterogeneous systems including crucial effects neglected in classical mean field models such as the hard core of the ions, the dielectric mismatch and interfaces with arbitrary shapes. The effect of hard core interactions accounts properly for short range interactions and the effect of local dielectric heterogeneities in the presence of ions and/or charged molecules for long-range interactions are both analyzed via an energy variational principle that enables to update charges and the medium's response in the same simulation time step. In particular, we compute the ionic structure in a model system of electrolyte confined by two planar dielectric interfaces using molecular dynamics(MD) simulations and compared it with liquid state theory result. We explore the effects of high electrolyte concentrations, multivalent ions, and dielectric contrasts on the ionic distributions. We observe the presence of non-monotonous ionic density profiles leading to structure deformation in the fluid which is attributed to the competition between electrostatic and steric (entropic) interactions. We find that thermal forces that arise from symmetry breaking at the interfaces can have a profound effect on the ionic structure and can oftentimes overwhelm the influence of dielectric discontinuity. The combined effect of ionic correlations and inhomogeneous dielectric permittivity significantly changes the character of effective interaction between two interfaces. We show that, in concentrated electrolytes with confinement, it is imperative to take into account the finite-size of the ions as well as proper description of electrostatic interactions in heterogeneous media, which is not fully fulfilled by Poisson-Boltzmann based approaches. The effect of electric field at interface between two immiscible electrolyte solutions is studied as well. The classical Poisson-Boltzmann theory has been widely used to describe the corresponding ionic distribution, even though it neglects the polarization and ion correlations typical of these charged systems. Using Monte Carlo simulations, we provide an enhanced description of an oil-water interface in the presence of an electric field without needing any adjustable parameter, including realistic ionic sizes, ion correlations, and image charges. Our data agree with experimental measurements of excess surface tension for a wide range of electrolyte concentrations of LiCl and TBATPB (tetrabutylammonium-tetraphenylborate), contrasting with the result of the classical non-linear Poisson-Boltzmann theory. More importantly, we show that the size-asymmetry between small Li+ and large Cl- ions can significantly increase the electric field near the liquid interface, or can even reverse it locally, at high salt concentrations in the aqueous phase. These observations suggest a novel trapping/release mechanism of charged nanoparticles at oil-water interfaces in the vicinity of the point of zero charge. In addition, we study the effects of size asymmetry and charge asymmetry on ion distribution at a dielectric interface using coarse-grained MD based on an energy variational principle. The goal is to explore charge amplification with exact consideration of surface polarization. We find that both size asymmetry and charge asymmetry lead to charge separation at the interfaces. In addition, charge separation is enhanced by interface polarization. We are currently extending the research to charged interfaces that has broad applications such as batteries and supercapacitors for energy storage.

Interfaces and Materials in Lithium Ion Batteries: Challenges for Theoretical Electrochemistry.

PubMed

Kasnatscheew, Johannes; Wagner, Ralf; Winter, Martin; Cekic-Laskovic, Isidora

2018-04-18

Energy storage is considered a key technology for successful realization of renewable energies and electrification of the powertrain. This review discusses the lithium ion battery as the leading electrochemical storage technology, focusing on its main components, namely electrode(s) as active and electrolyte as inactive materials. State-of-the-art (SOTA) cathode and anode materials are reviewed, emphasizing viable approaches towards advancement of the overall performance and reliability of lithium ion batteries; however, existing challenges are not neglected. Liquid aprotic electrolytes for lithium ion batteries comprise a lithium ion conducting salt, a mixture of solvents and various additives. Due to its complexity and its role in a given cell chemistry, electrolyte, besides the cathode materials, is identified as most susceptible, as well as the most promising, component for further improvement of lithium ion batteries. The working principle of the most important commercial electrolyte additives is also discussed. With regard to new applications and new cell chemistries, e.g., operation at high temperature and high voltage, further improvements of both active and inactive materials are inevitable. In this regard, theoretical support by means of modeling, calculation and simulation approaches can be very helpful to ex ante pre-select and identify the aforementioned components suitable for a given cell chemistry as well as to understand degradation phenomena at the electrolyte/electrode interface. This overview highlights the advantages and limitations of SOTA lithium battery systems, aiming to encourage researchers to carry forward and strengthen the research towards advanced lithium ion batteries, tailored for specific applications.

Designing a Novel Polymer Electrolyte for Improving the Electrode/Electrolyte Interface in Flexible All-Solid-State Electrical Double-Layer Capacitors.

PubMed

Wang, Jeng-An; Lu, Yi-Ting; Lin, Sheng-Chi; Wang, Yu-Sheng; Ma, Chen-Chi M; Hu, Chi-Chang

2018-05-30

A novel copolymer, polyurethane-poly(acrylic acid) (PAA), is successfully synthesized from poly(acrylic acid) (PAA) backbone cross-linked with waterborne polyurethane (WPU). This sticky polymer, which is neutralized with 1 M KOH and then soaked in 1 M KOH (denoted as WPU-PAAK-K), provides an ionic conductivity greater than 10 -2 S cm -1 and acts as a gel electrolyte perfectly improving the electrode/electrolyte interfaces in a flexible all-solid-state electrical double-layer capacitor (EDLC). The PAA backbone chains in the copolymer increase the amount of carboxyl groups and promote the segmental motion. The carboxyl groups enhance the water-uptake capacity, which facilitates the ion transport and promotes the ionic conductivity. The cross-linked agent, WPU chains, effectively maintains the rich water content and provides mechanical stickiness to bind two electrodes together. An acid-treated carbon paper (denoted as ACP) combining with such a gel polymer electrolyte demonstrates excellent capacitive behavior with a high areal capacitance of 211.6 mF cm -2 at 10 mV s -1 . A full cell consisting of ACP/WPU-PAAK-K/ACP displays a low equivalent series resistance of 0.44 Ω from the electrochemical impedance spectroscopic results. An all-solid-state ACP/WPU-PAAK-K/ACP EDLC provides an areal specific capacitance of 94.6 mF cm -2 at 1 mA cm -2 . This device under 180° bending shows a capacitance retention over 90%, revealing its remarkable flexibility.

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.

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

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

Lithium (Li) metal battery is an attractive energy storage system owing to the ultrahigh specific capacity and the lowest redox potential of Li metal anode. However, safety concern associated with dendrite growth and limited cycle life especially at a high charge current density are two critical challenges hindering the practical applications of rechargeable Li metal batteries. Here, we report for the first time that an optimal amount (0.05 M) of LiPF6 as additive in the LiTFSI-LiBOB dual-salt/carbonate-based electrolyte can significantly enhance the charging capability and the long-term cycle life of Li metal batteries with a moderately high cathode loading ofmore » 1.75 mAh cm-2. Unprecedented stable-cycling (97.1% capacity retention after 500 cycles) along with very limited increase in electrode over-potential has been achieved at a high current density of 1.75 mA cm-2. This unparalleled fast charging and stable cycling performance is contributed from both the stabilized Al cathode current collector, and, more importantly, the robust and conductive SEI layer formed on Li metal anode in the presence of the LiPF6 additive.« less

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 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

Influence of temperature on the aging behavior of 18650-type lithium ion cells: A comprehensive approach combining electrochemical characterization and post-mortem analysis

NASA Astrophysics Data System (ADS)

Friesen, Alex; Mönnighoff, Xaver; Börner, Markus; Haetge, Jan; Schappacher, Falko M.; Winter, Martin

2017-02-01

The understanding of the aging behavior of lithium ion batteries in automotive and energy storage applications is essential for the acceptance of the technology. Therefore, aging experiments were conducted on commercial 18650-type state-of-the-art cells to determine the influence of the temperature during electrochemical cycling on the aging behavior of the different cell components. The cells, based on Li(Ni0.5Co0.2Mn0.3)O2 (NCM532)/graphite, were aged at 20 °C and 45 °C to different states of health. The electrochemical performance of the investigated cells shows remarkable differences depending on the cycling temperature. At contrast to the expected behavior, the cells cycled at 45 °C show a better electrochemical performance over lifetime than the cells cycled at 20 °C. Comprehensive post-mortem analyses revealed the main aging mechanisms, showing a complex interaction between electrodes and electrolyte. The main aging mechanisms of the cells cycled at 45 °C differ strongly at contrast to cells cycled at 20 °C. A strong correlation between the formed SEI, the electrolyte composition and the electrochemical performance over lifetime was observed.

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

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.

Study of Stable Cathodes and Electrolytes for High Specific Density Lithium-Air Battery

NASA Technical Reports Server (NTRS)

Hernandez-Lugo, Dionne M.; Wu, James; Bennett, William; Ming, Yu; Zhu, Yu

2015-01-01

Future NASA missions require high specific energy battery technologies, greater than 400 Wh/kg. Current NASA missions are using "state-of-the-art" (SOA) Li-ion batteries (LIB), which consist of a metal oxide cathode, a graphite anode and an organic electrolyte. NASA Glenn Research Center is currently studying the physical and electrochemical properties of the anode-electrolyte interface for ionic liquid based Li-air batteries. The voltage-time profiles for Pyr13FSI and Pyr14TFSI ionic liquids electrolytes studies on symmetric cells show low over-potentials and no dendritic lithium morphology. Cyclic voltammetry measurements indicate that these ionic liquids have a wide electrochemical window. As a continuation of this work, sp2 carbon cathode and these low flammability electrolytes were paired and the physical and electrochemical properties were studied in a Li-air battery system under an oxygen environment.

Comparative Study of Ether-Based Electrolytes for Application in Lithium-Sulfur Battery.

PubMed

Carbone, Lorenzo; Gobet, Mallory; Peng, Jing; Devany, Matthew; Scrosati, Bruno; Greenbaum, Steve; Hassoun, Jusef

2015-07-01

Herein, we report the characteristics of electrolytes using various ether-solvents with molecular composition CH3O[CH2CH2O]nCH3, differing by chain length, and LiCF3SO3 as the lithium salt. The electrolytes, considered as suitable media for lithium-sulfur batteries, are characterized in terms of thermal properties (TGA, DSC), lithium ion conductivity, lithium interface stability, cyclic voltammetry, self-diffusion properties of the various components, and lithium transference number measured by NMR. Furthermore, the electrolytes are characterized in lithium cells using a sulfur-carbon composite cathode by galvanostatic charge-discharge tests. The results clearly evidence the influence of the solvent chain length on the species mobility within the electrolytes that directly affects the behavior in lithium sulfur cell. The results may effectively contribute to the progress of an efficient, high-energy lithium-sulfur battery.

Electrolytic oxidation of anthracite

USGS Publications Warehouse

Senftle, F.E.; Patton, K.M.; Heard, I.

1981-01-01

An anthracite slurry can be oxidized only with difficulty by electrolytic methods in which aqueous electrolytes are used if the slurry is confined to the region of the anode by a porous pot or diaphragm. However, it can be easily oxidized if the anthracite itself is used as the anode. No porous pot or diaphragm is needed. Oxidative consumption of the coal to alkali-soluble compounds is found to proceed preferentially at the edges of the aromatic planes. An oxidation model is proposed in which the chief oxidants are molecular and radical species formed by the electrolytic decomposition of water at the coal surface-electrolyte interface. The oxidation reactions proposed account for the opening of the aromatic rings and the subsequent formation of carboxylic acids. The model also explains the observed anisotropic oxidation and the need for the porous pot or diaphragm used in previous studies of the oxidation of coal slurries. ?? 1981.

Water-gel for gating graphene transistors.

PubMed

Kim, Beom Joon; Um, Soong Ho; Song, Woo Chul; Kim, Yong Ho; Kang, Moon Sung; Cho, Jeong Ho

2014-05-14

Water, the primary electrolyte in biology, attracts significant interest as an electrolyte-type dielectric material for transistors compatible with biological systems. Unfortunately, the fluidic nature and low ionic conductivity of water prevents its practical usage in such applications. Here, we describe the development of a solid state, megahertz-operating, water-based gate dielectric system for operating graphene transistors. The new electrolyte systems were prepared by dissolving metal-substituted DNA polyelectrolytes into water. The addition of these biocompatible polyelectrolytes induced hydrogelation to provide solid-state integrity to the system. They also enhanced the ionic conductivities of the electrolytes, which in turn led to the quick formation of an electric double layer at the graphene/electrolyte interface that is beneficial for modulating currents in graphene transistors at high frequencies. At the optimized conditions, the Na-DNA water-gel-gated flexible transistors and inverters were operated at frequencies above 1 MHz and 100 kHz, respectively.

Fundamental Investigations of Durability at a Polymer Electrolyte-Electrode Interface

DTIC Science & Technology

2008-04-01

before before σ -σ σ after before before σ -σ σ Cleavage of the side chain ether linkage (Fig. 3), which intrudes into the hydrophilic ionic cluster...directly correlated to peroxide yields measured Figure 3: ATR-FTIR Spectrum of Nafion ®112 (H-form) indicating absorption bands obtained using...electrocatalyst-based fuel cell electrode (referred as sacrificial electrode) directly into the liquid electrolyte, in which oxygen reduction was

Cyanoethylated compounds as additives in lithium/lithium batteries

DOEpatents

Nagasubramanian, Ganesan

1999-01-01

The power loss of lithium/lithium ion battery cells is significantly reduced, especially at low temperatures, when about 1% by weight of an additive is incorporated in the electrolyte layer of the cells. The usable additives are organic solvent soluble cyanoethylated polysaccharides and poly(vinyl alcohol). The power loss decrease results primarily from the decrease in the charge transfer resistance at the interface between the electrolyte and the cathode.

Gas Evolution in Operating Lithium-Ion Batteries Studied In Situ by Neutron Imaging

PubMed Central

Michalak, Barbara; Sommer, Heino; Mannes, David; Kaestner, Anders; Brezesinski, Torsten; Janek, Jürgen

2015-01-01

Gas generation as a result of electrolyte decomposition is one of the major issues of high-performance rechargeable batteries. Here, we report the direct observation of gassing in operating lithium-ion batteries using neutron imaging. This technique can be used to obtain qualitative as well as quantitative information by applying a new analysis approach. Special emphasis is placed on high voltage LiNi0.5Mn1.5O4/graphite pouch cells. Continuous gassing due to oxidation and reduction of electrolyte solvents is observed. To separate gas evolution reactions occurring on the anode from those associated with the cathode interface and to gain more insight into the gassing behavior of LiNi0.5Mn1.5O4/graphite cells, neutron experiments were also conducted systematically on other cathode/anode combinations, including LiFePO4/graphite, LiNi0.5Mn1.5O4/Li4Ti5O12 and LiFePO4/Li4Ti5O12. In addition, the data were supported by gas pressure measurements. The results suggest that metal dissolution in the electrolyte and decomposition products resulting from the high potentials adversely affect the gas generation, particularly in the first charge cycle (i.e., during graphite solid-electrolyte interface layer formation). PMID:26496823

High-performance electrodes for reduced temperature solid oxide fuel cells with doped lanthanum gallate electrolyte. II. La(Sr)CoO 3 cathode

NASA Astrophysics Data System (ADS)

Inagaki, Toru; Miura, Kazuhiro; Yoshida, Hiroyuki; Maric, Radenka; Ohara, Satoshi; Zhang, Xinge; Mukai, Kazuo; Fukui, Takehisa

The reduced temperature solid oxide fuel cell (SOFC) with 0.5 mm thick La 0.9Sr 0.1Ga 0.8Mg 0.2O 3- α (LSGM) electrolyte, La 0.6Sr 0.4CoO 3- δ (LSCo) cathode, and Ni-(CeO 2) 0.8(SmO 1.5) 0.2 (SDC) cermet anode showed an excellent initial performance, and high maximum power density, 0.47 W/cm 2, at 800°C. The results were comparable to those for the conventional SOFC with yttria-stabilized zirconia (YSZ) electrolyte, La(Sr)MnO 3-YSZ cathode and Ni-YSZ cermet anode at 1000°C. Using an LSCo powder prepared by spray pyrolysis, and selecting appropriate sintering temperatures, the lowest cathodic polarization of about 25 mV at 300 mA/cm 2 was measured for a cathode prepared by sintering at 1000°C. Life time cell test results, however, showed that the polarization of the LSCo cathode increased with operating time. From EPMA results, this behavior was considered to be related to the interdiffusion of the elements at the cathode/electrolyte interface. Calcination of LSCo powder could be a possible way to suppress this interdiffusion at the interface.

Investigating the time-dependent zeta potential of wood surfaces.

PubMed

Muff, Livius F; Luxbacher, Thomas; Burgert, Ingo; Michen, Benjamin

2018-05-15

This work reports on streaming potential measurements through natural capillaries in wood and investigates the cause of a time-dependent zeta potential measured during the equilibration of wood cell-walls with an electrolyte solution. For the biomaterial, this equilibration phase takes several hours, which is much longer than for many other materials that have been characterized by electrokinetic measurements. During this equilibration phase the zeta potential magnitude is decaying due to two parallel mechanisms: (i) the swelling of the cell-wall which causes a dimensional change reducing the charge density at the capillary interface; (ii) the transport of ions from the electrolyte solution into the permeable cell-wall which alters the electrical potential at the interface by internal charge compensation. The obtained results demonstrate the importance of equilibration kinetics for an accurate determination of the zeta potential, especially for materials that interact strongly with the measurement electrolyte. Moreover, the change in zeta potential with time can be correlated with the bulk swelling of wood if the effect of electrolyte ion diffusion is excluded. This study shows the potential of streaming potential measurements of wood, and possibly of other hygroscopic and nanoporous materials, to reveal kinetic information about their interaction with liquids, such as swelling and ion uptake. Copyright © 2018 Elsevier Inc. All rights reserved.

Proceedings of the Systems Reengineering Technology Workshop (4th) held in Monterey, California on February 8 - 10, 1994

DTIC Science & Technology

1994-09-01

report for the Properties of User Interface Software Architetures ", draft DISCUS Working Group, Programmers Tutorial, MITRE paper, SEI. Carnegie...execution that we have defined called asynchronous remote procedure call (ARPC) [15], which allows concurrency in amounts proportional to the amount of...demonstration project to use STARS DoD software budget and the proportion concepts. IBM is one of the prime is expected to be increased during the contractors

Polymer membrane based electrolytic cell and process for the direct generation of hydrogen peroxide in liquid streams

NASA Technical Reports Server (NTRS)

White, James H. (Inventor); Schwartz, Michael (Inventor); Sammells, Anthony F. (Inventor)

1997-01-01

An electrolytic cell for generating hydrogen peroxide is provided including a cathode containing a catalyst for the reduction of oxygen, and an anode containing a catalyst for the oxidation of water. A polymer membrane, semipermeable to either protons or hydroxide ions is also included and has a first face interfacing to the cathode and a second face interfacing to the anode so that when a stream of water containing dissolved oxygen or oxygen bubbles is passed over the cathode and a stream of water is passed over the anode, and an electric current is passed between the anode and the cathode, hydrogen peroxide is generated at the cathode and oxygen is generated at the anode.

Graphene Oxide Sponge as Nanofillers in Printable Electrolytes in High-Performance Quasi-Solid-State Dye-Sensitized Solar Cells.

PubMed

Venkatesan, Shanmuganathan; Surya Darlim, Elmer; Tsai, Ming-Hsiang; Teng, Hsisheng; Lee, Yuh-Lang

2018-04-04

A graphene oxide sponge (GOS) is utilized for the first time as a nanofiller (NF) in printable electrolytes (PEs) based on poly(ethylene oxide) and poly(vinylidene fluoride) for quasi-solid-state dye-sensitized solar cells (QS-DSSCs). The effects of the various concentrations of GOS NFs on the ion diffusivity and conductivity of electrolytes and the performance of the QS-DSSCs are studied. The results show that the presence of GOS NFs significantly increases the diffusivity and conductivity of the PEs. The introduction of 1.5 wt % of GOS NFs decreases the charge-transfer resistance at the Pt-counter electrode/electrolyte interface ( R pt ) and increases the recombination resistance at the photoelectrode/electrolyte interface ( R ct ). QS-DSSC utilizing 1.5 wt % GOS NFs can achieve an energy conversion efficiency (8.78%) higher than that found for their liquid counterpart and other reported polymer gel electrolytes/GO NFs based DSSCs. The high energy conversion efficiency is a consequence of the increase in both the open-circuit potential ( V oc ) and fill factor with a slight decrease in current density ( J sc ). The cell efficiency can retain 86% of its initial value after a 500 h stability test at 60 °C under dark conditions. The long-term stability of the QS-DSSC with GOS NFs is higher than that without NFs. This result indicates that the GOS NFs do not cause dye-desorption from the photoanode in a long-term stability test, which infers a superior performance of GOS NFs as compared to TiO 2 NFs in terms of increasing the efficiency and long-term stability of QS-DSSCs.

High-Crystallinity Urchin-like VS4 Anode for High-Performance Lithium-Ion Storage.

PubMed

Yang, Guang; Zhang, Bowei; Feng, Jianyong; Wang, Huanhuan; Ma, Mingbo; Huang, Kang; Liu, Jilei; Madhavi, Srinivasan; Shen, Zexiang; Huang, Yizhong

2018-05-02

VS 4 anode materials with controllable morphologies from hierarchical microflower, octopus-like structure, seagrass-like structure to urchin-like structure have been successfully synthesized by a facile solvothermal synthesis approach using different alcohols as solvents. Their structures and electrochemical properties with various morphologies are systematically investigated, and the structure-property relationship is established. Experimental results reveal that Li + ion storage behavior in VS 4 significantly depends on physical features such as the morphology, crystallite size, and specific surface area. According to this study, electrochemical performance degrades on the order of urchin-like VS 4 > octopus-like VS 4 > seagrass-like VS 4 > flower-like VS 4 . Among them, urchin-like VS 4 demonstrates the best electrochemical performance benefiting from its peculiar structure which possesses large surface area that accommodates the volume change to a certain extent, and single-crystal thorns that provide fast electron transportation. Kinetic parameters derived from EIS spectra and sweep-rate-dependent CV curves, such as charge-transfer resistances, Li + ion apparent diffusion coefficients and stored charge ratio of capacitive and intercalation contributions, both support this claim well. In addition, the EIS measurement was conducted during the first discharge/charge process to study the solid electrolyte interface (SEI) formation on urchin-like VS 4 and kinetics behavior of Li + ion diffusion. A better fundamental understanding on Li + storage behavior in VS 4 is promoted, which is applicable to other vanadium-based materials as well. This study also provides invaluable guidance for morphology-controlled synthesis tailored for optimal electrochemical performance.

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.

Raising the Corrosion Resistance of Low-Carbon Steels by Electrolytic-Plasma Saturation with Nitrogen and Carbon

NASA Astrophysics Data System (ADS)

Kusmanov, S. A.; Grishina, E. P.; Belkin, P. N.; Kusmanova, Yu. V.; Kudryakova, N. O.

2017-05-01

Structural features of the external oxide layer and internal nitrided, carbonitrided and carburized layers in steels 10, 20 and St3 produced by the method of electrolytic plasma treatment are studied. Specimens of the steels are tested for corrosion in a naturally aerated 1-N solution of sodium chloride. The condition of the metal/sodium chloride solution interface is studied by the method of electrochemical impedance spectroscopy. It is shown that the corrosion resistance of low-carbon steels can be raised by anode electrolytic-plasma saturation with nitrogen and carbon. Recommendations are given on the choice of carbonitriding modes for structural steels.

Nitrogen-doped carbon nanofibers derived from polypyrrole coated bacterial cellulose as high-performance electrode materials for supercapacitors and Li-ion batteries

DOE PAGES

Lei, Wen; Han, Lili; Xuan, Cuijuan; ...

2016-05-24

Here, nitrogen-doped carbon nanofiber (NDCN) was synthesized via carbonization of polypyrrole (PPy) coated bacterial cellulose (BC) composites, where BC serves as templates as well as precursor, and PPy serves as the nitrogen source. The synthesized NDCN was employed as electrode for both supercapacitors and Li-ion batteries. The large surface area exposed to electrolyte resulting from the 3D carbon networks leads to sufficient electrode/electrolyte interface and creates shorter transport paths of electrolyte ions and Li + ion. Besides, the three types of N dopants in NDCN improve the electronic conductivity, as well as superior electrochemical performance.

Thin film buried anode battery

DOEpatents

Lee, Se-Hee [Lakewood, CO; Tracy, C Edwin [Golden, CO; Liu, Ping [Denver, CO

2009-12-15

A reverse configuration, lithium thin film battery (300) having a buried lithium anode layer (305) and process for making the same. The present invention is formed from a precursor composite structure (200) made by depositing electrolyte layer (204) onto substrate (201), followed by sequential depositions of cathode layer (203) and current collector (202) on the electrolyte layer. The precursor is subjected to an activation step, wherein a buried lithium anode layer (305) is formed via electroplating a lithium anode layer at the interface of substrate (201) and electrolyte film (204). The electroplating is accomplished by applying a current between anode current collector (201) and cathode current collector (202).

High Voltage LiNi0.5Mn1.5O4/Li4Ti5O12 Lithium Ion Cells at Elevated Temperatures: Carbonate- versus Ionic Liquid-Based Electrolytes.

PubMed

Cao, Xia; He, Xin; Wang, Jun; Liu, Haidong; Röser, Stephan; Rad, Babak Rezaei; Evertz, Marco; Streipert, Benjamin; Li, Jie; Wagner, Ralf; Winter, Martin; Cekic-Laskovic, Isidora

2016-10-05

Thanks to its high operating voltage, the LiNi 0.5 Mn 1.5 O 4 (LNMO) spinel represents a promising next-generation cathode material candidate for Lithium ion batteries. However, LNMO-based full-cells with organic carbonate solvent electrolytes suffer from severe capacity fading issues, associated with electrolyte decomposition and concurrent degradative reactions at the electrode/electrolyte interface, especially at elevated temperatures. As promising alternatives, two selected LiTFSI/pyrrolidinium bis(trifluoromethane-sulfonyl)imide room temperature ionic liquid (RTIL) based electrolytes with inherent thermal stability were investigated in this work. Linear sweep voltammetry (LSV) profiles of the investigated LiTFSI/RTIL electrolytes display much higher oxidative stability compared to the state-of-the-art LiPF 6 /organic carbonate based electrolyte at elevated temperatures. Cycling performance of the LNMO/Li 4 Ti 5 O 12 (LTO) full-cells with LiTFSI/RTIL electrolytes reveals remarkable improvements with respect to capacity retention and Coulombic efficiency. Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns indicate maintained pristine morphology and structure of LNMO particles after 50 cycles at 0.5C. The investigated LiTFSI/RTIL based electrolytes outperform the LiPF 6 /organic carbonate-based electrolyte in terms of cycling performance in LNMO/LTO full-cells at elevated temperatures.