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Sample records for spinel cathode materials

  1. New inverse spinel cathode materials for rechargeable lithium batteries

    NASA Astrophysics Data System (ADS)

    Fey, G. T. K.; Wang, K. S.; Yang, S. M.

    The synthesis, characterization, and electrochemical properties of LiNi yCo 1 - yVO 4 (0 ≤ y ≤ 1) as the new cathode materials for rechargeable lithium batteries were investigated. A series of LiNi yCo 1 - yVO 4 ( y = 0.1 - 0.9) compounds were synthesized by either a solid-state reaction of LiNi yCo 1 - yO 2 and V 2O 5 at 800 °C for 12 h or a solution coprecipitation of LiOH · H 2O, Ni(NO 3) 2 · 6H 2O, Co(NO 3) 2 · 6H 2O and NH 4VO 3, followed by heating the precipitate at 500 °C for 48 h. The products from both preparation methods were analyzed by scanning electron microcopy and inductively-coupled plasma-atomic emission spectroscopy. These compounds are inverse spinels based on the results from Rietveld analysis and the fact that the cubic lattice constant a is a linear function of stoichiometry y in LiNi yCo 1 - yVO 4. Either a 1 M LiC1O 4-EC + PC (1:1) or 1 M LiBF 4-EC + PC + DMC (1:1:4) electrolyte can be used as the electrolyte for Li/LiNi yCo 1 - yVO 4 cells up to y = 0.7. The charge and discharge capacity of a Li/1 M LiBF 4-EC + PC + DMC (1:1:4) /LiNi 0.5Co 0.5VO 4 cell were 43.8 and 34.8 mAh/g, respectively, when the cathode material was prepared by the low temperature coprecipitation method.

  2. Ultrathin spinel membrane-encapsulated layered lithium-rich cathode material for advanced Li-ion batteries.

    PubMed

    Wu, Feng; Li, Ning; Su, Yuefeng; Zhang, Linjing; Bao, Liying; Wang, Jing; Chen, Lai; Zheng, Yu; Dai, Liqin; Peng, Jingyuan; Chen, Shi

    2014-06-11

    Lack of high-performance cathode materials has become a technological bottleneck for the commercial development of advanced Li-ion batteries. We have proposed a biomimetic design and versatile synthesis of ultrathin spinel membrane-encapsulated layered lithium-rich cathode, a modification by nanocoating. The ultrathin spinel membrane is attributed to the superior high reversible capacity (over 290 mAh g(-1)), outstanding rate capability, and excellent cycling ability of this cathode, and even the stubborn illnesses of the layered lithium-rich cathode, such as voltage decay and thermal instability, are found to be relieved as well. This cathode is feasible to construct high-energy and high-power Li-ion batteries. PMID:24844948

  3. High power 4.7 V nanostructured spinel lithium manganese nickel oxide lithium-ion battery cathode materials

    NASA Astrophysics Data System (ADS)

    Kunduraci, Muharrem

    Nanostructured LiMn1.5+deltaNi0.5-deltaO 4 spinel powders were synthesized by a solution based chemistry method called modified Pechini. The impacts of processing parameters such as synthesis temperature, oxygen-partial-pressure and mole ratio of ethylene glycol to citric acid on the morphology, structure and properties of spinel materials have been studied thoroughly via various in-situ and ex-situ characterization techniques. Later, these parameters were tied with the electrochemical properties of spinel electrodes. After optimization of processing steps and glycol/acid ratio, a unique mesoporous morphology with interconnected nanoparticles were successfully obtained. Such morphology was found to be very conducive to achieve high power density lithium-ion battery spinel cathodes. This was attributed to (i) large number of mesoporosities that favor electrolyte penetration, thereby enabling better wetting of spinel cathodes and faster lithium ion transfer at electrolyte/cathode interface and (ii) particle interconnectivity that allows continuous electron transport, which becomes highly critical especially at high current rates. The synthesis temperature and oxygen-partial-pressure were found to affect the structure significantly. Depending on the ordering/disordering of transition metal ions on octahedral sites, spinels were assigned to either ordered P4 332 or disordered Fd3m space groups. The spinel of the two symmetry groups differed significantly in fast discharge rate capability. In an effort to identify the origin of this electrochemical disparity, intensive characterizations of both structures were undertaken (in-situ: XRD, Impedance spectroscopy, Raman; ex-situ: XRD, FTIR, TGA, electronic conductivity and lithium diffusivity and more). The poor performance of the ordered phase was attributed to its intrinsic properties, namely lower electronic conductivity and lithium diffusion coefficient (DLi). Regarding the former, the mechanism of electron conduction in

  4. Polyaniline modification and performance enhancement of lithium-rich cathode material based on layered-spinel hybrid structure

    NASA Astrophysics Data System (ADS)

    Wang, Di; Wang, Xianyou; Yang, Xiukang; Yu, Ruizhi; Ge, Long; Shu, Hongbo

    2015-10-01

    The spherical lithium-rich cathode material with a layered-spinel hybrid structure is successfully synthesized and coated by polyaniline (PANI). The spherical material with layered-spinel hybrid structure is firstly prepared via the hydrothermal method, and then the conducting PANI is coated on the surface of the as-prepared spherical particle through an in-situ polymerization. Based on the analysis of scanning electron microscope (SEM), transmission electron microscope (TEM), high rate transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED), it can be found that the size distribution of the spherical particles modified by PANI are about ∼1 μm, meanwhile the average thickness of the PANI layer on the surface of each particle is about 6.3 nm. The electrochemical performance of the spherical lithium-rich cathode material modified by PANI is apparently improved, the capacity retention is still 92.4% after 200 cycles at a rate of 0.5 C. The discharge capacities at 0.1 C and 10 C are as high as 302.9 mAh g-1 and 146.2 mAh g-1, respectively. Therefore, the modification of PANI for the spherical lithium-rich cathode material with a layered-spinel hybrid structure will be a promising technical route for the application with high capacity, long cycle life and good safety.

  5. Dependence of structure and temperature for lithium-rich layered-spinel microspheres cathode material of lithium ion batteries

    PubMed Central

    Wang, Di; Yu, Ruizhi; Wang, Xianyou; Ge, Long; Yang, Xiukang

    2015-01-01

    Homogeneous lithium-rich layered-spinel 0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2 microspheres (~1 μm) are successfully prepared by a solvothermal method and subsequent high-temperature calcinations process. The effects of temperature on the structure and performance of the as-prepared cathode material are systemically studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), galvanostatical charge/discharge and electrochemical impedance spectra. The results show that a spinel Li4Mn5O12 component can be controllably introduced into the lithium-rich layered material at 750°C. Besides, it has been found that the obtained layered-spinel cathode material represents excellent electrochemical characteristics. For example, it can deliver a high initial discharge capacity of 289.6 mAh g−1 between 2.0 V and 4.6 V at a rate of 0.1 C at room temperature, and a discharge capacity of 144.9 mAh g−1 at 5 C and 122.8 mAh g−1 even at 10 C. In addition, the retention of the capacity is still as high as 88% after 200 cycles, while only 79.9% for the single-phase layered material. The excellent electrochemical performance of the as-prepared cathode material can probably be attributed to the hybrid structures combining a fast Li-ion diffusion rate of 3D spinel Li4Mn5O12 phase and a high capacity of the layered Li-Mn-Ni-Co-O component. PMID:25672573

  6. Structure of electrolyte decomposition products on high voltage spinel cathode materials determined by in situ neutron reflectometry

    NASA Astrophysics Data System (ADS)

    Browning, Jim; Veith, Gabriel; Baggetto, Loic; Dudney, Nancy; Tenhaeff, Wyatt

    2012-02-01

    Interfacial reactions on electrical energy storage (EES) materials mediate their stability, durability, and cycleablity. Understanding these reactions in situ is difficult since they occur at the liquid-solid interface of an optically absorbing material that hinders the use of techniques such as infra-red spectroscopy. Furthermore, since the interfaces involve liquids classic vacuum-based analytical methods can only probe reaction products, which are stable under vacuum. Here, we present the results of an in situ neutron reflectometry study detailing the formation of a thick solid-electrolyte interphase (SEI) on a high voltage spinel cathode material. The cathode/electrolyte system used in this study is a LiMn1.5Ni0.5O4 thin film subjected to a 1.2 molar LiPF6 in 1:1 ethylene carbonate - dimethyl carbonate electrolyte solution.

  7. Preliminary studies of biominerals-coated spinel LiMn2 O4 as a cathode material on electrochemical performances for Li-ion rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Vediappan, Kumaran; Lee, Chang Woo

    2010-05-01

    Lithium manganese oxide (LiMn2O4) is an inexpensive and pollution-free cathode material for Li-ion rechargeable batteries. In this study, spinel LiMn2O4 cathode material was coated with biomineral powders by the mechano-chemical method. In the course of the material synthesis, citric acid and acryl amide were added to serve as a complexing agent and a gelling agent, respectively, followed by a calcination process at 700 °C for 6 h in a high-purity argon atmosphere. The spinel LiMn2O4 and biominerals-coated spinel LiMn2O4 cathode materials were, from diverse viewpoints, characterized by x-ray diffraction, field emission-scanning electron microscopy, Fourier transform infrared spectroscopy and the electrochemical cycling method to understand the mechanism of improvements in electrochemical performances. We suggest that the biominerals-coated spinel LiMn2O4 is a good candidate as a low cost and environmentally friendly cathode material showing the enlarged capacity characteristic of Li-ion rechargeable batteries.

  8. Solution-combustion synthesized aluminium-doped spinel (LiAl x Mn2- x O4) as a high-performance lithium-ion battery cathode material

    NASA Astrophysics Data System (ADS)

    Kebede, Mesfin A.; Phasha, Maje J.; Kunjuzwa, Niki; Mathe, Mkhulu K.; Ozoemena, Kenneth I.

    2015-10-01

    High-performing LiAl x Mn2- x O4 ( x = 0, 0.125, 0.25, 0.375, and 0.5) spinel cathode materials for lithium-ion battery were developed using a solution combustion method. The as-synthesized cathode materials have spinel cubic structure of LiMn2O4 without any impurity peak and accompanied with peak shift as doping with aluminium. LiAl0.375Mn1.625O4 (first cycle capacity = 113.1 mAh g-1) retains 85 % (96.2 mAh g-1), while pristine LiMn2O4 electrode (first cycle capacity = 135.8 mAh g-1) fades quickly and retains only 54 % (73.9 mAh g-1) after 50 cycles. The electrochemical performance of all the cathode samples prepared using the SCM is comparable to those reported for Al-doped LiMn2O4 spinel cathode materials. The experimental lattice parameter of LiAl x Mn2- x O4 was validated by ab initio calculations and correlated with the first cycle capacity of materials. The variation in lattice parameter as a result of Al doping greatly enhanced the cyclability of discharge capacity of the LiMn2O4 spinel.

  9. A facile approach to derive binder protective film on high voltage spinel cathode materials against high temperature degradation

    NASA Astrophysics Data System (ADS)

    Chou, Wei-Yu; Jin, Yi-Chun; Duh, Jenq-Gong; Lu, Cheng-Zhang; Liao, Shih-Chieh

    2015-11-01

    The electrochemical performance of spinel LiNi0.5Mn1.5O4 cathode combined with different binders at elevated temperature is firstly investigated. The water soluble binder, such as sodium carboxymethyl cellulose (CMC) and sodium alginate (SA), is compared with the polyvinylidene difluoride (PVdF) binder used in non-aqueous process. The aqueous process can meet the need of Li-ion battery industry due to environmental-friendly and cost effectiveness by replacing toxic organic solvent, such as N-methyl-pyrrolidone (NMP). In this study, a significantly improved high temperature cycling performance is successfully obtained as compared to the traditional PVdF binder. The aqueous binder can serve as a protective film which inhibits the serious Ni and Mn dissolution especially at elevated temperature. Our result demonstrates a facile approach to solve the problem of capacity fading for high voltage spinel cathodes.

  10. A series of spinel phase cathode materials prepared by a simple hydrothermal process for rechargeable lithium batteries

    SciTech Connect

    Liang Yanyu; Bao Shujuan; Li Hulin . E-mail: lihl@lzu.edu.cn

    2006-07-15

    A series of spinel-structured materials have been prepared by a simple hydrothermal procedure in an aqueous medium. The new synthetic method is time and energy saving i.e., no further thermal treatment and extended grinding. The main experimental process involved the insertion of lithium into electrolytic manganese dioxide with glucose as a mild reductant in an autoclave. Both the hydrothermal temperature and the presence of glucose play the critical roles in determining the final spinel integrity. Particular electrochemical performance has also been systematically explored, and the results show that Al{sup 3+}, F{sup -} co-substituted spinels have the best combination of initial capacity and capacity retention among all these samples, exhibited the initial capacity of 115 mAh/g and maintained more than 90% of the initial value at the 50th cycle. - Graphical abstract: It is a SEM image of the spinel LiMn{sub 2}O{sub 4}, which was prepared by this novel hydrothermal procedure. It illustrates that reasonable-crystallized spinel oxide has occurred through the special hydrothermal process and the average particle size declined to about 1 {mu}m. This homogeneous grain size distribution provides an important morphological basis for the reversibility and accessibility of lithium ion insertion/extraction reactions.

  11. Interplay between two-phase and solid solution reactions in high voltage spinel cathode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Xiao, Jie; Yu, Xiqian; Zheng, Jianming; Zhou, Yungang; Gao, Fei; Chen, Xilin; Bai, Jianming; Yang, Xiao-Qing; Zhang, Ji-Guang

    2013-11-01

    Lithium ion batteries (LIBs) are attracting intensive interests worldwide because of their potential applications in transportation electrification and utility grid. The intercalation compounds used in LIBs electrochemically react with Li+ ions via single or multiple phase transitions depending on the nature of the material structure as well as the synthesis and operating conditions. For LiNi0.5Mn1.5O4 high voltage spinel, a promising candidate positive electrode material for LIBs, there are three spinel-structured phases sequentially appeared through two successive two-phase reactions during the delithiation/lithiation processes. Here we demonstrate, experimentally and theoretically, that through elemental substitution, the solid solution ranges for both the first and second phases are significantly extended during the electrochemical charge-discharge process. This type of structural changes with more solid solution regions facilitate fast Li+ diffusion by reducing the number of phase boundaries that Li+ ions have to overcome and resulted in less shrinkage of the unit cells at the end of charge process. This work unravels the fundamental interactions between structural and electrochemical properties by using spinel as the platform, which may be widely adopted to explain or tailor the properties of materials for energy storage and conversion.

  12. Layered-Layered-Spinel Cathode Materials Prepared by a High-Energy Ball-Milling Process for Lithium-ion Batteries.

    PubMed

    Kim, Soo; Noh, Jae-Kyo; Aykol, Muratahan; Lu, Zhi; Kim, Haesik; Choi, Wonchang; Kim, Chunjoong; Chung, Kyung Yoon; Wolverton, Chris; Cho, Byung-Won

    2016-01-13

    In this work, we report the electrochemical properties of 0.5Li2MnO3·0.25LiNi0.5Co0.2Mn0.3O2·0.25LiNi0.5Mn1.5O4 and 0.333Li2MnO3·0.333LiNi0.5Co0.2Mn0.3O2·0.333LiNi0.5Mn1.5O4 layered-layered-spinel (L*LS) cathode materials prepared by a high-energy ball-milling process. Our L*LS cathode materials can deliver a large and stable capacity of ∼200 mAh g(-1) at high voltages up to 4.9 V, and do not show the anomalous capacity increase upon cycling observed in previously reported three-component cathode materials synthesized with different routes. Furthermore, we have performed synchrotron-based in situ X-ray diffraction measurements and found that there are no significant structural distortions during charge/discharge runs. Lastly, we carry out (opt-type) van der Waals-corrected density functional theory (DFT) calculations to explain the enhanced cycle characteristics and reduced phase transformations in our ball-milled L*LS cathode materials. Our simple synthesis method brings a new perspective on the use of the high-power L*LS cathodes in practical devices. PMID:26645115

  13. Controllable synthesis of spinel lithium nickel manganese oxide cathode material with enhanced electrochemical performances through a modified oxalate co-precipitation method

    NASA Astrophysics Data System (ADS)

    Liu, Hongmei; Zhu, Guobin; Zhang, Li; Qu, Qunting; Shen, Ming; Zheng, Honghe

    2015-01-01

    A spinel lithium nickel manganese oxide (LiNi0.5Mn1.5O4) cathode material is synthesized with a modified oxalate co-precipitation method by controlling pH value of the precursor solution and introducing excessive Li source in the precursor. All the samples synthesized through this method are of Fd3m phase with a small amount of P4332 phase. It is found that pH value of the precursor solution considerably affects the morphology, stoichiometry and crystallographic structure of the target material, thereby resulting in different amounts of Mn3+ (i.e., different degree of disorder). 5% excessive Li source in the precursor may compensate for the lithium loss during the high-temperature sintering process and eliminate the LixNi1-xO impurity phase. Under the optimized synthesis conditions, the obtained high-purity LiNi0.5Mn1.5O4 spinel exhibits enhanced electrochemical performances. A reversible capacity of ca. 140 mAh g-1 can be delivered at 0.1C and the electrode retains 106 mAh g-1 at 10C rate. When cycled at 0.2C, a capacity retention of more than 98% is obtained in the initial 50 electrochemical cycles.

  14. Microwave-enhanced electrochemical cycling performance of the LiNi0.2Mn1.8O4 spinel cathode material at elevated temperature.

    PubMed

    Raju, Kumar; Nkosi, Funeka P; Viswanathan, Elumalai; Mathe, Mkhulu K; Damodaran, Krishnan; Ozoemena, Kenneth I

    2016-05-14

    The well-established poor electrochemical cycling performance of the LiMn2O4 (LMO) spinel cathode material for lithium-ion batteries at elevated temperature stems from the instability of the Mn(3+) concentration. In this work, a microwave-assisted solid-state reaction has been used to dope LMO with a very low amount of nickel (i.e., LiNi0.2Mn1.8O4, herein abbreviated as LMNO) for lithium-ion batteries from Mn3O4 which is prepared from electrolytic manganese oxide (EMD, γ-MnO2). To establish the impact of microwave irradiation on the electrochemical cycling performance at an elevated temperature (60 °C), the Mn(3+) concentration in the pristine and microwave-treated LMNO samples was independently confirmed by XRD, XPS, (6)LiMAS-NMR and electrochemical studies including electrochemical impedance spectroscopy (EIS). The microwave-treated sample (LMNOmic) allowed for the clear exposure of the {111} facets of the spinel, optimized the Mn(3+) content, promoting structural and cycle stability at elevated temperature. At room temperature, both the pristine (LMNO) and microwave-treated (LMNOmic) samples gave comparable cycling performance (>96% capacity retention and ca. 100% coulombic efficiency after 100 consecutive cycling). However, at an elevated temperature (60 °C), the LMNOmic gave an improved cycling stability (>80% capacity retention and ca. 90% coulombic efficiency after 100 consecutive cycling) compared to the LMNO. For the first time, the impact of microwave irradiation on tuning the average manganese redox state of the spinel material to enhance the cycling performance of the LiNi0.2Mn1.8O4 at elevated temperature and lithium-ion diffusion kinetics has been clearly demonstrated. PMID:27113855

  15. Insight into the Atomic Structure of High-Voltage Spinel LiNi0.5Mn1.5O4 Cathode Material in the First Cycle

    DOE PAGESBeta

    Huang, Xuejie; Yu, Xiqian; Lin, Mingxiang; Ben, Liubin; Sun, Yang; Wang, Hao; Yang, Zhenzhong; Gu, Lin; Yang, Xiao -Qing; Zhao, Haofei; et al

    2014-12-22

    Application of high-voltage spinel LiNi0.5Mn1.5O4 cathode material is the closest and the most realistic approach to meeting the midterm goal of lithium-ion batteries for electric vehicles (EVs) and plug-in hybrid electric vehicles (HEVs). However, this application has been hampered by long-standing issues, such as capacity degradation and poor first-cycle Coulombic efficiency of LiNi0.5Mn1.5O4 cathode material. Although it is well-known that the structure of LiNi0.5Mn1.5O4 into which Li ions are reversibly intercalated plays a critical role in the above issues, performance degradation related to structural changes, particularly in the first cycle, are not fully understood. Here, we report detailed investigations ofmore » local atomic-level and average structure of LiNi0.5Mn1.5O4 during first cycle (3.5–4.9 V) at room temperature. We observed two types of local atomic-level migration of transition metals (TM) ions in the cathode of a well-prepared LiNi0.5Mn1.5O4//Li half-cell during first charge via an aberration-corrected scanning transmission electron microscopy (STEM). Surface regions (~2 nm) of the cycled LiNi0.5Mn1.5O4 particles show migration of TM ions into tetrahedral Li sites to form a Mn3O4-like structure. However, subsurface regions of the cycled particles exhibit migration of TM ions into empty octahedral sites to form a rocksalt-like structure. The migration of these TM ions are closely related to dissolution of Ni/Mn ions and building-up of charge transfer impedance, which contribute significantly to the capacity degradation and the poor first-cycle Coulombic efficiency of spinel LiNi0.5Mn1.5O4 cathode material. Accordingly, we provide suggestions of effective stabilization of LiNi0.5Mn1.5O4 structure to obtain better electrochemical performance.« less

  16. Interplay between two-phase and solid solution reactions in high voltage spinel cathode material for lithium ion batteries

    SciTech Connect

    Xiao, Jie; Yu, Xiqian; Zheng, Jianming; Zhou, Yungang; Gao, Fei; Chen, Xilin; Bai, Jianming; Yang, Xiao-Qing; Zhang, Jiguang

    2013-06-06

    Lithium ion batteries (LIBs) are attracting intensive interests worldwide because of their potential applications in transportation electrification and utility grid. The intercalation compounds used in LIBs electrochemically react with Li+ ions via single or multiple phase transitions depending on the nature of the material structure as well as the synthesis and testing conditions. It is generally accepted that for high voltage spinel LiNi0.5Mn1.5O4, a promising candidate for LIBs, there are two successive two-phase reactions occurring during the delithiation/lithiation processes, as reflected by the two flat plateaus with a small step in between. Here we demonstrate, experimentally and theoretically, that through elemental substitution, each of the two-phase transitions has been largely converted into a solid solution reaction during the electrochemical process. The latter favors fast Li+ diffusion due to the reduced number of phase boundaries that Li+ ions have to overcome, as well as the reduced shrinkage of unit cells after charge. This work clearly elaborates one of the critical functions for element doping/substitution that has been widely adopted in the materials synthesis for LIBs, whose fundamental mechanisms are still obscured.

  17. Quaternary phase diagrams of spinel Liy□1-yMnxNi2 -xO4 and composite cathode voltages for concentration gradient materials

    NASA Astrophysics Data System (ADS)

    Hao, Shiqiang; Lu, Zhi; Wolverton, Christopher

    2016-07-01

    Core-shell coating structures and concentration gradient materials may enhance Li-ion battery performance by integrating advantages of core and shell components without introducing unfavorable problems associated with general coatings. The fundamental thermodynamic properties of concentration gradient composite materials are complex due to the multicomponent nature of the problem. We systematically study the thermodynamics of ordering and phase separation in the quaternary spinel Liy□1-yMnxNi2 -xO4 (□ means vacancy) system by density functional theory calculations, together with the coupled cluster expansion method with interactions within and between (Li/□) and (Mn/Ni) sublattices. On the basis of coupled cluster expansion interactions and Monte Carlo simulations, we calculate quaternary phase diagrams as a function of temperature as well as voltage profiles of single ordered phases and multiphase composite structures. The phase diagram and voltage results are in good agreement with available experimental observations. We also predict a stable high-voltage ordered compound LiMnNiO4, with a very high delithiation voltage of 4.76 V. For the composite (Mn-rich+Ni -rich) cathode materials, the voltage profiles show combinations of plateaus from each component compound. The computational strategy of combining quaternary phase diagrams with voltage calculations provides a pathway to understand and design concentration gradient materials.

  18. Sub-2 nm Thick Fluoroalkylsilane Self-Assembled Monolayer-Coated High Voltage Spinel Crystals as Promising Cathode Materials for Lithium Ion Batteries.

    PubMed

    Zettsu, Nobuyuki; Kida, Satoru; Uchida, Shuhei; Teshima, Katsuya

    2016-01-01

    We demonstrate herein that an ultra-thin fluoroalkylsilane self-assembled monolayer coating can be used as a modifying agent at LiNi0.5Mn1.5O4-δcathode/electrolyte interfaces in 5V-class lithium-ion batteries. Bare LiNi0.5Mn1.5O4-δ cathode showed substantial capacity fading, with capacity dropping to 79% of the original capacity after 100 cycles at a rate of 1C, which was entirely due to dissolution of Mn(3+) from the spinel lattice via oxidative decomposition of the organic electrolyte. Capacity retention was improved to 97% on coating ultra-thin FAS17-SAM onto the LiNi0.5Mn1.5O4 cathode surface. Such surface protection with highly ordered fluoroalkyl chains insulated the cathode from direct contact with the organic electrolyte and led to increased tolerance to HF. PMID:27553901

  19. Synthesis of spinel LiNi0.5Mn1.5O4 with secondary plate morphology as cathode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Risthaus, Tim; Wang, Jun; Friesen, Alex; Wilken, Andrea; Berghus, Debbie; Winter, Martin; Li, Jie

    2015-10-01

    Spinel LiNi0.5Mn1.5O4 material has been synthesized by a spray drying process and subsequent solid state reaction. Polyvinylpyrrolidone (PVP) is given as additive to the spray drying precursor solution and its effects on structural and electrochemical properties are evaluated. By using PVP in the synthesis process, the obtained sample displays a secondary plate morphology which is consisting of densely arranged primary octahedrally shaped particles. The new cathode material has a lesser degree of impurity phases, a higher discharge capacity, a superior rate capability, and a slightly better cycling performance than the sample synthesized without PVP. In more detail, by the use of PVP the ratio of Mn3+ to Mn4+ in the final product decreases from 20.8 to 9.2%. The initial discharge capacity at 0.1 C exhibits an increase of about 14%. The normalized capacity at 20 C is 84.1% instead of 67.0%. A slightly improved cycling performance with the capacity retention increase from 93.8 to 97.9% could be observed as well.

  20. Spinel compounds as multivalent battery cathodes: A systematic evaluation based on ab initio calculations

    DOE PAGESBeta

    Liu, Miao; Rong, Ziqin; Malik, Rahul; Canepa, Pieremanuele; Jain, Anubhav; Ceder, Gerbrand; Persson, Kristin A.

    2014-12-16

    In this study, batteries that shuttle multivalent ions such as Mg2+ and Ca2+ ions are promising candidates for achieving higher energy density than available with current Li-ion technology. Finding electrode materials that reversibly store and release these multivalent cations is considered a major challenge for enabling such multivalent battery technology. In this paper, we use recent advances in high-throughput first-principles calculations to systematically evaluate the performance of compounds with the spinel structure as multivalent intercalation cathode materials, spanning a matrix of five different intercalating ions and seven transition metal redox active cations. We estimate the insertion voltage, capacity, thermodynamic stabilitymore » of charged and discharged states, as well as the intercalating ion mobility and use these properties to evaluate promising directions. Our calculations indicate that the Mn2O4 spinel phase based on Mg and Ca are feasible cathode materials. In general, we find that multivalent cathodes exhibit lower voltages compared to Li cathodes; the voltages of Ca spinels are ~0.2 V higher than those of Mg compounds (versus their corresponding metals), and the voltages of Mg compounds are ~1.4 V higher than Zn compounds; consequently, Ca and Mg spinels exhibit the highest energy densities amongst all the multivalent cation species. The activation barrier for the Al³⁺ ion migration in the Mn₂O₄ spinel is very high (~1400 meV for Al3+ in the dilute limit); thus, the use of an Al based Mn spinel intercalation cathode is unlikely. Amongst the choice of transition metals, Mn-based spinel structures rank highest when balancing all the considered properties.« less

  1. Synthesis of spinel LiMn2O4 cathode material by a modified solid state reaction

    NASA Astrophysics Data System (ADS)

    Zhang, Jiawei; Lin, Shudong; Li, Keyan; Shua, Fenfen; Chen, Kunfeng; Wang, Liqiu; Xue, Dongfeng

    2015-12-01

    Spinel LiMn2O4 was synthesized by a modified solid state reaction. We pretreated the reactants using tartaric acid as complexing agent through a grinding process to obtain uniform distribution of metal ions at atomic level. The structures, morphologies and electrochemical properties of the products were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and galvanostatic charge-discharge test. The results show that adding tartaric acid during the chemical pretreatment plays an important role in the formation of regular and uniform particles, which is beneficial to the electrochemical performance of LiMn2O4. At the current density of 100 mA g-1, the discharge capacity is 118 mAh g-1 after 50 cycles with the capacity retention of 97%.

  2. Ternary Spinel MCo2O4 (M = Mn, Fe, Ni, and Zn) Porous Nanorods as Bifunctional Cathode Materials for Lithium-O2 Batteries.

    PubMed

    Mohamed, Saad Gomaa; Tsai, Yuan-Quei; Chen, Chih-Jung; Tsai, Yi-Ting; Hung, Tai-Feng; Chang, Wen-Sheng; Liu, Ru-Shi

    2015-06-10

    The development of Li-O2 battery electrocatalysts has been extensively explored recently. The Co3O4 oxide has attracted much attention because of its bifunctional activity and high abundance. In the present study, toxic Co(2+) has been replaced through the substitution on the tetrahedral spinel A site ions with environmental friendly metals (Mn(2+), Fe(2+), Ni(2+), and Zn(2+)), and porous nanorod structure are formed. Among these spinel MCo2O4 cathodes, the FeCo2O4 surface has the highest Co(3+) ratio. Thus, oxygen can be easily adsorbed onto the active sites. In addition, Fe(2+) in the tetrahedral site can easily release electrons to reduce oxygen and oxidize to half electron filled Fe(3+). The FeCo2O4 cathode exhibits the highest discharging plateau and lowest charging plateau as shown by the charge-discharge profile. Moreover, the porous FeCo2O4 nanorods can also facilitate achieving high capacity and good cycling performance, which are beneficial for O2 diffusion channels and Li2O2 formation/decomposition pathways. PMID:25984925

  3. Sub-2 nm Thick Fluoroalkylsilane Self-Assembled Monolayer-Coated High Voltage Spinel Crystals as Promising Cathode Materials for Lithium Ion Batteries

    PubMed Central

    Zettsu, Nobuyuki; Kida, Satoru; Uchida, Shuhei; Teshima, Katsuya

    2016-01-01

    We demonstrate herein that an ultra-thin fluoroalkylsilane self-assembled monolayer coating can be used as a modifying agent at LiNi0.5Mn1.5O4−δcathode/electrolyte interfaces in 5V-class lithium-ion batteries. Bare LiNi0.5Mn1.5O4−δ cathode showed substantial capacity fading, with capacity dropping to 79% of the original capacity after 100 cycles at a rate of 1C, which was entirely due to dissolution of Mn3+ from the spinel lattice via oxidative decomposition of the organic electrolyte. Capacity retention was improved to 97% on coating ultra-thin FAS17-SAM onto the LiNi0.5Mn1.5O4 cathode surface. Such surface protection with highly ordered fluoroalkyl chains insulated the cathode from direct contact with the organic electrolyte and led to increased tolerance to HF. PMID:27553901

  4. Truncated octahedral LiNi0.5Mn1.5O4 cathode material for ultralong-life lithium-ion battery: Positive (100) surfaces in high-voltage spinel system

    NASA Astrophysics Data System (ADS)

    Liu, Haidong; Kloepsch, Richard; Wang, Jun; Winter, Martin; Li, Jie

    2015-12-01

    So far, it has not yet reached an agreement that (111) surfaces or (100) surfaces are more positive to electrochemical performance in the spinel system. Herein, we present the synthesis of regular truncated octahedral high-voltage spinel LiNi0.5Mn1.5O4 single crystals with preferred growth of (100) surfaces, which incredibly exhibit the best long-term cycling stability compared with the state-of-art spinel material. The capacity retention is about 90% after 2000 cycles at 1 C. The extraordinary performance is mostly attributed to the highly regular truncated octahedral microstructure with large portions of stable (100) facets, which can stabilize the spinel structure to effectively suppress the side reactions with the electrolyte at high operating voltage and are also orientated to support Li+ transport kinetics. Therefore, our work further promotes the practical application of LiNi0.5Mn1.5O4 cathode material in next generation Lithium-ion batteries with high energy density and power performance.

  5. Long-term evaluation of solid oxide fuel cell candidate materials in a 3-cell generic stack test fixture, part III: Stability and microstructure of Ce-(Mn,Co)-spinel coating, AISI441 interconnect, alumina coating, cathode and anode

    NASA Astrophysics Data System (ADS)

    Chou, Yeong-Shyung; Stevenson, Jeffry W.; Choi, Jung-Pyung

    2014-07-01

    A generic solid oxide fuel cell stack test fixture was developed to evaluate candidate materials and processing under realistic conditions. Part III of the work investigated the stability of Ce-(Mn,Co) spinel coating, AISI441 metallic interconnect, alumina coating, and cell's degradation. After 6000 h test, the spinel coating showed densification with some diffusion of Cr. At the metal interface, segregation of Si and Ti was observed, however, no continuous layer formed. The alumina coating for perimeter sealing areas appeared more dense and thick at the air side than the fuel side. Both the spinel and alumina coatings remained bonded. EDS analysis of Cr within the metal showed small decrease in concentration near the coating interface and would expect to cause no issue of Cr depletion. Inter-diffusion of Ni, Fe, and Cr between spot-welded Ni wire and AISI441 interconnect was observed and Cr-oxide scale formed along the circumference of the weld. The microstructure of the anode and cathode was discussed relating to degradation of the top and middle cells. Overall, the Ce-(Mn,Co) spinel coating, alumina coating, and AISI441 steel showed the desired long-term stability and the developed generic stack fixture proved to be a useful tool to validate candidate materials for SOFC.

  6. Morphological Evolution of High-Voltage Spinel LiNi(0.5)Mn(1.5)O4 Cathode Materials for Lithium-Ion Batteries: The Critical Effects of Surface Orientations and Particle Size.

    PubMed

    Liu, Haidong; Wang, Jun; Zhang, Xiaofei; Zhou, Dong; Qi, Xin; Qiu, Bao; Fang, Jianhui; Kloepsch, Richard; Schumacher, Gerhard; Liu, Zhaoping; Li, Jie

    2016-02-01

    An evolution panorama of morphology and surface orientation of high-voltage spinel LiNi(0.5)Mn(1.5)O4 cathode materials synthesized by the combination of the microwave-assisted hydrothermal technique and a postcalcination process is presented. Nanoparticles, octahedral and truncated octahedral particles with different preferential growth of surface orientations are obtained. The structures of different materials are studied by X-ray diffraction (XRD), Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), and transmission electron microscopy (TEM). The influence of various morphologies (including surface orientations and particle size) on kinetic parameters, such as electronic conductivity and Li(+) diffusion coefficients, are investigated as well. Moreover, electrochemical measurements indicate that the morphological differences result in divergent rate capabilities and cycling performances. They reveal that appropriate surface-tailoring can satisfy simultaneously the compatibility of power capability and long cycle life. The morphology design for optimizing Li(+) transport and interfacial stability is very important for high-voltage spinel material. Overall, the crystal chemistry, kinetics and electrochemical performance of the present study on various morphologies of LiNi(0.5)Mn(1.5)O4 spinel materials have implications for understanding the complex impacts of electrode interface and electrolyte and rational design of rechargeable electrode materials for lithium-ion batteries. The outstanding performance of our truncated octahedral LiNi(0.5)Mn(1.5)O4 materials makes them promising as cathode materials to develop long-life, high energy and high power lithium-ion batteries. PMID:26824793

  7. In operando study of the high voltage spinel cathode material LiNi(0.5)Mn(1.5)O4 using two dimensional full-field spectroscopic imaging of Ni and Mn.

    PubMed

    Bauer, Sondes; de Biasi, Lea; Glatthaar, Sven; Toukam, Leonel; Gesswein, Holger; Baumbach, Tilo

    2015-07-01

    LiNi0.5Mn1.5O4 spinel cathode was studied during the first discharge cycle using combined full field Transmission X-ray Microscopy (TXM) and X-ray Absorption Near Edge Structure Spectroscopy (XANES) techniques to follow the chemical phase transformation as well as the microstructural evolution of cathode materials upon operation within an electrochemical cell. The spatial distribution and electrochemical process of the spinel material with spherical granules of 30 μm and 3 μm crystallite size was investigated. The spectroscopic imaging of the cathode within field of view of 40 × 32 μm(2) and spatial resolution of 40 nm has revealed an increase of the LiNi0.5Mn1.5O4 granule size during lithiation providing an insight into the effect of the particle size and morphology on the electrochemical process. The chemical elemental distribution and the content of the different oxidation states of the two absorbing elements (Ni and Mn) have been determined in operando from the XANES imaging. A gradual increase in the content of the oxidation state Mn(3+) from 8% up to 64% has been recorded during the discharge from 5 V to 2.7 V. The study of the local oxidation reduction behavior of Mn(3+) reveals a reversibility aspect in the local electrochemical reaction of Mn(4+) toward Mn(3+) in areas located in the center of the aggregate as well as in areas closed to the electrolyte. During the discharge process, a mixture of Mn(3+) and Mn(4+) has been detected while only single electron valence states have been found in the case of Ni. Probing the chemical changes during the discharge using two-dimensional XANES reveals spatial differences in the electrochemical activities of the two absorbing elements Ni and Mn. PMID:26051380

  8. Copper cobalt spinel as a high performance cathode for intermediate temperature solid oxide fuel cells.

    PubMed

    Shao, Lin; Wang, Qi; Fan, Lishuang; Wang, Pengxiang; Zhang, Naiqing; Sun, Kening

    2016-06-30

    CuCo2O4 spinel prepared via an EDTA-citric acid process was studied as a candidate solid oxide fuel cell (SOFC) cathode material at intermediate temperatures (IT). CuCo2O4 cathodes were measured using thermal gravimetric analysis, X-ray diffraction and scanning electron microscopy. AC impedance spectroscopy and DC polarization measurements were used to study the electrode performance. The obtained value of the polarization resistances at 800 °C was 0.12 Ω cm(2) with a maximum power density of 972 mW cm(-2). PMID:27326915

  9. Spinel compounds as multivalent battery cathodes: A systematic evaluation based on ab initio calculations

    SciTech Connect

    Liu, Miao; Rong, Ziqin; Malik, Rahul; Canepa, Pieremanuele; Jain, Anubhav; Ceder, Gerbrand; Persson, Kristin A.

    2014-12-16

    In this study, batteries that shuttle multivalent ions such as Mg2+ and Ca2+ ions are promising candidates for achieving higher energy density than available with current Li-ion technology. Finding electrode materials that reversibly store and release these multivalent cations is considered a major challenge for enabling such multivalent battery technology. In this paper, we use recent advances in high-throughput first-principles calculations to systematically evaluate the performance of compounds with the spinel structure as multivalent intercalation cathode materials, spanning a matrix of five different intercalating ions and seven transition metal redox active cations. We estimate the insertion voltage, capacity, thermodynamic stability of charged and discharged states, as well as the intercalating ion mobility and use these properties to evaluate promising directions. Our calculations indicate that the Mn2O4 spinel phase based on Mg and Ca are feasible cathode materials. In general, we find that multivalent cathodes exhibit lower voltages compared to Li cathodes; the voltages of Ca spinels are ~0.2 V higher than those of Mg compounds (versus their corresponding metals), and the voltages of Mg compounds are ~1.4 V higher than Zn compounds; consequently, Ca and Mg spinels exhibit the highest energy densities amongst all the multivalent cation species. The activation barrier for the Al³⁺ ion migration in the Mn₂O₄ spinel is very high (~1400 meV for Al3+ in the dilute limit); thus, the use of an Al based Mn spinel intercalation cathode is unlikely. Amongst the choice of transition metals, Mn-based spinel structures rank highest when balancing all the considered properties.

  10. Formation Of The Spinel Phase In The Layered Composite Cathode Used In Li-Ion Batteries

    SciTech Connect

    Gu, Meng; Belharouak, Ilias; Zheng, Jianming; Wu, Huiming; Xiao, Jie; Genc, Arda; Amine, Khalil; Thevuthasan, Suntharampillai; Baer, Donald R.; Zhang, Jiguang; Browning, Nigel D.; Liu, Jun; Wang, Chong M.

    2013-01-22

    Pristine Li-rich layered cathodes, such as Li1.2Ni0.2Mn0.6O2 and Li1.2Ni0.1Mn0.525Co0.175O2, were identified to exist in two different structures: LiMO2 R-3m and Li2MO3 C2/m phases. Upon charge/discharge cycling, both phases gradually transform to the spinel structure. The transition from LiMO2 R-3m to spinel is accomplished through the migration of transition metal ions to the Li site without breaking down the lattice, leading to the formation of mosaic structured spinel grains within the parent particle. In contrast, transition from Li2MO3 C2/m to spinel involves removal of Li+ and O2-, which produces a large lattice strain and leads to the breakdown of the parent lattice and therefore the newly formed spinel grains show random orientation within the same particle. Cracks and pores were also noticed within some particles, which is believed to be the consequence of the breakdown of the lattice and vacancy condensation upon removal of lithium ions. The presently observed structure transition characteristics provide direct reasons for the observed gradual capacity loss and poor rate performance of the layered composite. Ultimately it also provides clues about how to improve the materials structure with potential improved performance.

  11. Insight into the Atomic Structure of High-Voltage Spinel LiNi0.5Mn1.5O4 Cathode Material in the First Cycle

    SciTech Connect

    Huang, Xuejie; Yu, Xiqian; Lin, Mingxiang; Ben, Liubin; Sun, Yang; Wang, Hao; Yang, Zhenzhong; Gu, Lin; Yang, Xiao -Qing; Zhao, Haofei; Yu, Richeng; Armand, Michel

    2014-12-22

    Application of high-voltage spinel LiNi0.5Mn1.5O4 cathode material is the closest and the most realistic approach to meeting the midterm goal of lithium-ion batteries for electric vehicles (EVs) and plug-in hybrid electric vehicles (HEVs). However, this application has been hampered by long-standing issues, such as capacity degradation and poor first-cycle Coulombic efficiency of LiNi0.5Mn1.5O4 cathode material. Although it is well-known that the structure of LiNi0.5Mn1.5O4 into which Li ions are reversibly intercalated plays a critical role in the above issues, performance degradation related to structural changes, particularly in the first cycle, are not fully understood. Here, we report detailed investigations of local atomic-level and average structure of LiNi0.5Mn1.5O4 during first cycle (3.5–4.9 V) at room temperature. We observed two types of local atomic-level migration of transition metals (TM) ions in the cathode of a well-prepared LiNi0.5Mn1.5O4//Li half-cell during first charge via an aberration-corrected scanning transmission electron microscopy (STEM). Surface regions (~2 nm) of the cycled LiNi0.5Mn1.5O4 particles show migration of TM ions into tetrahedral Li sites to form a Mn3O4-like structure. However, subsurface regions of the cycled particles exhibit migration of TM ions into empty octahedral sites to form a rocksalt-like structure. The migration of these TM ions are closely related to dissolution of Ni/Mn ions and building-up of charge transfer impedance, which contribute significantly to the capacity degradation and the poor first-cycle Coulombic efficiency of spinel LiNi0.5Mn1.5O4 cathode material. Accordingly, we provide suggestions of effective stabilization of LiNi0.5

  12. Formation of the spinel phase in the layered composite cathode used in Li-ion batteries.

    PubMed

    Gu, Meng; Belharouak, Ilias; Zheng, Jianming; Wu, Huiming; Xiao, Jie; Genc, Arda; Amine, Khalil; Thevuthasan, Suntharampillai; Baer, Donald R; Zhang, Ji-Guang; Browning, Nigel D; Liu, Jun; Wang, Chongmin

    2013-01-22

    Pristine Li-rich layered cathodes, such as Li(1.2)Ni(0.2)Mn(0.6)O(2) and Li(1.2)Ni(0.1)Mn(0.525)Co(0.175)O(2), were identified to exist in two different structures: LiMO(2)R3[overline]m and Li(2)MO(3)C2/m phases. Upon 300 cycles of charge/discharge, both phases gradually transform to the spinel structure. The transition from LiMO(2)R3[overline]m to spinel is accomplished through the migration of transition metal ions to the Li site without breaking down the lattice, leading to the formation of mosaic structured spinel grains within the parent particle. In contrast, transition from Li(2)MO(3)C2/m to spinel involves removal of Li(+) and O(2-), which produces large lattice strain and leads to the breakdown of the parent lattice. The newly formed spinel grains show random orientation within the same particle. Cracks and pores were also noticed within some layered nanoparticles after cycling, which is believed to be the consequence of the lattice breakdown and vacancy condensation upon removal of lithium ions. The AlF(3)-coating can partially relieve the spinel formation in the layered structure during cycling, resulting in a slower capacity decay. However, the AlF(3)-coating on the layered structure cannot ultimately stop the spinel formation. The observation of structure transition characteristics discussed in this paper provides direct explanation for the observed gradual capacity loss and poor rate performance of the layered composite. It also provides clues about how to improve the materials structure in order to improve electrochemical performance. PMID:23237664

  13. High-Capacity Layered-Spinel Cathodes for Li-Ion Batteries.

    PubMed

    Nayak, Prasant Kumar; Levi, Elena; Grinblat, Judith; Levi, Mikhael; Markovsky, Boris; Munichandraiah, N; Sun, Yang Kook; Aurbach, Doron

    2016-09-01

    Li and Mn-rich layered oxides with the general structure x Li2 MnO3 ⋅(1-x) LiMO2 (M=Ni, Mn, Co) are promising cathode materials for Li-ion batteries because of their high specific capacity, which may be greater than 250 mA h g(-1) . However, these materials suffer from high first-cycle irreversible capacity, gradual capacity fading, limited rate capability and discharge voltage decay upon cycling, which prevent their commercialization. The decrease in average discharge voltage is a major issue, which is ascribed to a structural layered-to-spinel transformation upon cycling of these oxide cathodes in wide potential ranges with an upper limit higher than 4.5 V and a lower limit below 3 V versus Li. By using four elements systems (Li, Mn, Ni, O) with appropriate stoichiometry, it is possible to prepare high capacity composite cathode materials that contain LiMn1.5 Ni0.5 O4 and Lix Mny Niz O2 components. The Li and Mn-rich layered-spinel cathode materials studied herein exhibit a high specific capacity (≥200 mA h g(-1) ) with good capacity retention upon cycling in a wide potential domain (2.4-4.9 V). The effect of constituent phases on their electrochemical performance, such as specific capacity, cycling stability, average discharge voltage, and rate capability, are explored here. This family of materials can provide high specific capacity, high rate capability, and promising cycle life. Using Co-free cathode materials is also an obvious advantage of these systems. PMID:27530465

  14. An Integrated, Layered-Spinel Composite Cathode for Energy Storage Applications

    NASA Technical Reports Server (NTRS)

    Hagh, Nader; Skandan, Ganesh

    2012-01-01

    At low operating temperatures, commercially available electrode materials for lithium-ion batteries do not fully meet the energy and power requirements for NASA fs exploration activities. The composite cathode under development is projected to provide the required energy and power densities at low temperatures and its usage will considerably reduce the overall volume and weight of the battery pack. The newly developed composite electrode material can provide superior electrochemical performance relative to a commercially available lithium cobalt system. One advantage of using a composite cathode is its higher energy density, which can lead to smaller and lighter battery packs. In the current program, different series of layered-spinel composite materials with at least two different systems in an integrated structure were synthesized, and the volumetric and gravimetric energy densities were evaluated. In an integrated network of a composite electrode, the effect of the combined structures is to enhance the capacity and power capabilities of the material to levels greater than what is possible in current state-of-the-art cathode systems. The main objective of the current program is to implement a novel cathode material that meets NASA fs low temperature energy density requirements. An important feature of the composite cathode is that it has at least two components (e.g., layered and spinel) that are structurally integrated. The layered material by itself is electrochemically inactive; however, upon structural integration with a spinel material, the layered material can be electrochemically activated, thereby delivering a large amount of energy with stable cycling. A key aspect of the innovation has been the development of a scalable process to produce submicronand micron-scale particles of these composite materials. An additional advantage of using such a composite electrode material is its low irreversible loss (.5%), which is primarily due to the unique activation

  15. Cathode materials review

    SciTech Connect

    Daniel, Claus Mohanty, Debasish Li, Jianlin Wood, David L.

    2014-06-16

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO{sub 2} cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  16. Cathode materials review

    NASA Astrophysics Data System (ADS)

    Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood, David L.

    2014-06-01

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  17. Utilizing environmental friendly iron as a substitution element in spinel structured cathode materials for safer high energy lithium-ion batteries

    DOE PAGESBeta

    Hu, Enyuan; Bak, Seong -Min; Liu, Yijin; Liu, Jue; Yu, Xiqian; Zhou, Yong -Ning; Zhou, Jigang; Khalifah, Peter; Ariyoshi, Kingo; Nam, Kyung -Wan; et al

    2015-12-03

    Suppressing oxygen release from lithium ion battery cathodes during heating is a critical issue for the improvement of the battery safety characteristics because oxygen can exothermically react with the flammable electrolyte and cause thermal runaway. Previous studies have shown that oxygen release can be reduced by the migration of transition metal cations from octahedral sites to tetrahedral sites during heating. Such site-preferred migration is determined by the electronic structure of cations. In addition, taking advantage of the unique electronic structure of the environmental friendly Fe, this is selected as substitution element in a high energy density material LiNi0.5Mn1.5O4 to improvemore » the thermal stability. The optimized LiNi0.33Mn1.33Fe0.33O4 material shows significantly improved thermal stability compared with the unsubstituted one, demonstrated by no observed oxygen release at temperatures as high as 500°C. Due to the electrochemical contribution of Fe, the high energy density feature of LiNi0.5Mn1.5O4 is well preserved.« less

  18. Utilizing environmental friendly iron as a substitution element in spinel structured cathode materials for safer high energy lithium-ion batteries

    SciTech Connect

    Hu, Enyuan; Bak, Seong -Min; Liu, Yijin; Liu, Jue; Yu, Xiqian; Zhou, Yong -Ning; Zhou, Jigang; Khalifah, Peter; Ariyoshi, Kingo; Nam, Kyung -Wan; Yang, Xiao -Qing

    2015-12-03

    Suppressing oxygen release from lithium ion battery cathodes during heating is a critical issue for the improvement of the battery safety characteristics because oxygen can exothermically react with the flammable electrolyte and cause thermal runaway. Previous studies have shown that oxygen release can be reduced by the migration of transition metal cations from octahedral sites to tetrahedral sites during heating. Such site-preferred migration is determined by the electronic structure of cations. In addition, taking advantage of the unique electronic structure of the environmental friendly Fe, this is selected as substitution element in a high energy density material LiNi0.5Mn1.5O4 to improve the thermal stability. The optimized LiNi0.33Mn1.33Fe0.33O4 material shows significantly improved thermal stability compared with the unsubstituted one, demonstrated by no observed oxygen release at temperatures as high as 500°C. Due to the electrochemical contribution of Fe, the high energy density feature of LiNi0.5Mn1.5O4 is well preserved.

  19. Cathode material for lithium batteries

    DOEpatents

    Park, Sang-Ho; Amine, Khalil

    2015-01-13

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  20. Cathode material for lithium batteries

    DOEpatents

    Park, Sang-Ho; Amine, Khalil

    2013-07-23

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  1. Cation-substituted spinel oxide and oxyfluoride cathodes for lithium ion batteries

    DOEpatents

    Manthiram, Arumugam; Choi, Wongchang

    2014-05-13

    The present invention includes compositions and methods of making cation-substituted and fluorine-substituted spinel cathode compositions by firing a LiMn.sub.2-y-zLi.sub.yM.sub.zO.sub.4 oxide with NH.sub.4HF.sub.2 at low temperatures of between about 300 and 700.degree. C. for 2 to 8 hours and a .eta. of more than 0 and less than about 0.50, mixed two-phase compositions consisting of a spinel cathode and a layered oxide cathode, and coupling them with unmodified or surface modified graphite anodes in lithium ion cells.

  2. Relative stability of normal vs. inverse spinel for 3d transition metal oxides as lithium intercalation cathodes.

    PubMed

    Bhattacharya, Jishnu; Wolverton, C

    2013-05-01

    Spinel oxides represent an important class of cathode materials for Li-ion batteries. Two major variants of the spinel crystal structure are normal and inverse. The relative stability of normal and inverse ordering at different stages of lithiation has important consequences in lithium diffusivity, voltage, capacity retention and battery life. In this paper, we investigate the relative structural stability of normal and inverse structures of the 3d transition metal oxide spinels with first-principles DFT calculations. We have considered ternary spinel oxides LixM2O4 with M = Ti, V, Cr, Mn, Fe, Co and Ni in both lithiated (x = 1) and delithiated (x = 0) conditions. We find that for all lithiated spinels, the normal structure is preferred regardless of the metal. We observe that the normal structure for all these oxides has a lower size mismatch between octahedral cations compared to the inverse structure. With delithiation, many of the oxides undergo a change in stability with vanadium in particular, showing a tendency to occupy tetrahedral sites. We find that in the delithiated oxide, only vanadium ions can access a +5 oxidation state which prefers tetrahedral coordination. We have also calculated the average voltage of lithiation for these spinels. The calculated voltages agree well with the previously measured and calculated values, wherever available. For the yet to be characterized spinels, our calculation provides voltage values which can motivate further experimental attention. Lastly, we observe that all the normal spinel oxides of the 3d transition metal series have a driving force for a transformation to the non-spinel structure upon delithiation. PMID:23529669

  3. Suppressing Manganese Dissolution from Lithium Manganese Oxide Spinel Cathodes with Single-Layer Graphene

    SciTech Connect

    Jaber-Ansari, Laila; Puntambekar, Kanan P.; Kim, Soo; Aykol, Muratahan; Luo, Langli; Wu, Jinsong; Myers, Benjamin D.; Iddir, Hakim; Russell, John T.; Saldana, Spencer J.; Kumar, Rajan; Thackeray, Michael M.; Curtiss, Larry A.; Dravid, Vinayak P.; Wolverton, Christopher M.; Hersam, Mark C.

    2015-06-24

    Spinel-structured LiMn 2 O 4 (LMO) is a desirable cathode material for Li-ion batteries due to its low cost, abundance, and high power capability. However, LMO suffers from limited cycle life that is triggered by manganese dissolution into the electrolyte during electrochemical cycling. Here, it is shown that single-layer graphene coatings suppress manganese dissolution, thus enhancing the performance and lifetime of LMO cathodes. Relative to lithium cells with uncoated LMO cathodes, cells with graphene-coated LMO cathodes provide improved capacity retention with enhanced cycling stability. X-ray photoelectron spectroscopy reveals that graphene coatings inhibit manganese depletion from the LMO surface. Additionally, transmission electron microscopy demonstrates that a stable solid electrolyte interphase is formed on graphene, which screens the LMO from direct contact with the electrolyte. Density functional theory calculations provide two mechanisms for the role of graphene in the suppression of manganese dissolution. First, common defects in single-layer graphene are found to allow the transport of lithium while concurrently acting as barriers for manganese diffusion. Second, graphene can chemically interact with Mn 3+ at the LMO electrode surface, promoting an oxidation state change to Mn 4+ , which suppresses dissolution.

  4. Fluorination Induced the Surface Segregation of High Voltage Spinel on Lithium-Rich Layered Cathodes for Enhanced Rate Capability in Lithium Ion Batteries.

    PubMed

    Jin, Yi-Chun; Duh, Jenq-Gong

    2016-02-17

    This study is aimed to explore the effect of fluoride doping and the associated structural transformation on lithium-rich layered cathode materials. The polymeric fluoride source is first adopted for synthesizing lithium intercalated oxide through a newly developed organic precipitation process. A heterostructured spinel/layered composite cathode material is obtained after appreciable fluorination and a superior rate capability is successfully achieved. The fluoride dopant amount and the surface spinel phase are evidenced and systematically examined by various structural spectroscopy and electrochemical analysis. It appears the reversible Ni(2+/4+) redox couple at high voltage regime around 4.8 V because of the formation of spinel LiNi1/2Mn3/2O4 phase. The mechanism of "layer to spinel" phase transformation is discussed in detail. PMID:26807506

  5. Olivine Composite Cathode Materials for Improved Lithium Ion Battery Performance

    SciTech Connect

    Ward, R.M.; Vaughey, J.T.

    2006-01-01

    Composite cathode materials in lithium ion batteries have become the subject of a great amount of research recently as cost and safety issues related to LiCoO2 and other layered structures have been discovered. Alternatives to these layered materials include materials with the spinel and olivine structures, but these present different problems, e.g. spinels have low capacities and cycle poorly at elevated temperatures, and olivines exhibit extremely low intrinsic conductivity. Previous work has shown that composite structures containing spinel and layered materials have shown improved electrochemical properties. These types of composite structures have been studied in order to evaluate their performance and safety characteristics necessary for use in lithium ion batteries in portable electronic devices, particularly hybrid-electric vehicles. In this study, we extended that work to layered-olivine and spinel-olivine composites. These materials were synthesized from precursor salts using three methods: direct reaction, ball-milling, and a coreshell synthesis method. X-ray diffraction spectra and electrochemical cycling data show that the core-shell method was the most successful in forming the desired products. The electrochemical performance of the cells containing the composite cathodes varied dramatically, but the low overpotential and reasonable capacities of the spinel-olivine composites make them a promising class for the next generation of lithium ion battery cathodes.

  6. Cation-substituted spinel oxide and oxyfluoride cathodes for lithium ion batteries

    DOEpatents

    Manthiram, Arumugam; Choi, Wonchang

    2010-05-18

    The present invention includes compositions and methods of making cation-substituted and fluorine-substituted spinel cathode compositions by firing a LiMn2-y-zLiyMzO4 oxide with NH4HF2 at low temperatures of between about 300 and 700.degree. C. for 2 to 8 hours and a .eta. of more than 0 and less than about 0.50, mixed two-phase compositions consisting of a spinel cathode and a layered oxide cathode, and coupling them with unmodified or surface modified graphite anodes in lithium ion cells.

  7. Insertion of lattice strains into ordered LiNi0.5Mn1.5O4 spinel by mechanical stress: A comparison of perfect versus imperfect structures as a cathode for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Kozawa, Takahiro; Murakami, Takeshi; Naito, Makio

    2016-07-01

    The Ni-doped lithium manganese oxide, LiNi0.5Mn1.5O4, has received much attention as a cathode active material in high-energy lithium-ion batteries (LIBs). This active material has two different spinel structures depending on the ordering state of the Ni and Mn ions. The ordered LiNi0.5Mn1.5O4 spinel has an inferior cathode performance than the disordered phase because of its poor electronic conductivity. However, the ordered LiNi0.5Mn1.5O4 spinel possesses the potential advantage of avoiding dissolution of the Mn ion, which is an issue for the disordered spinel. The improvement of cathode performance is important for future applications. Here, we report a unique approach to improve the cathode performance of the ordered LiNi0.5Mn1.5O4 spinel. The mechanical treatment using an attrition-type mill successfully inserted lattice strains into the ordered LiNi0.5Mn1.5O4 spinel structure without a phase transformation to the disordered phase. The insertion of lattice strains by mechanical stresses provided an increased discharge capacity and a decreased charge transfer resistance. This limited crystal structure modification improved the cathode performance. The present work has the potential for application of the mechanically treated ordered LiNi0.5Mn1.5O4 spinel as a cathode for high-energy LIBs.

  8. Critical parameters governing energy density of Li-storage cathode materials unraveled by confirmatory factor analysis

    NASA Astrophysics Data System (ADS)

    Sohn, Kee-Sun; Han, Su Cheol; Park, Woon Bae; Pyo, Myoungho

    2016-03-01

    Despite extensive effort during the past few decades, a comprehensive understanding of the key variables governing the electrochemical properties of cathode materials in Li-ion batteries is still far from complete. To elucidate the critical parameters affecting energy density (ED) and capacity (Q) retention in layer and spinel cathodes, we data-mine the existing experimental data via confirmatory factor analysis (CFA) based on a structural equation model (SEM), which is a proven, versatile tool in understanding complex problems in the social science. The data sets are composed of 18 and 15 parameters extracted from 38 layer and 33 spinel compounds, respectively. CFA reveals the irrelevance of Q retention to all the parameters we adopt, but it also reveals the sensitive variations of ED with specific parameters. We validate the usefulness of CFA in material science and pinpointed critical parameters for high-ED cathodes, hoping to suggest a new insight in materials design.

  9. High-Capacity, High-Voltage Composite Oxide Cathode Materials

    NASA Technical Reports Server (NTRS)

    Hagh, Nader M.

    2015-01-01

    This SBIR project integrates theoretical and experimental work to enable a new generation of high-capacity, high-voltage cathode materials that will lead to high-performance, robust energy storage systems. At low operating temperatures, commercially available electrode materials for lithium-ion (Li-ion) batteries do not meet energy and power requirements for NASA's planned exploration activities. NEI Corporation, in partnership with the University of California, San Diego, has developed layered composite cathode materials that increase power and energy densities at temperatures as low as 0 degC and considerably reduce the overall volume and weight of battery packs. In Phase I of the project, through innovations in the structure and morphology of composite electrode particles, the partners successfully demonstrated an energy density exceeding 1,000 Wh/kg at 4 V at room temperature. In Phase II, the team enhanced the kinetics of Li-ion transport and electronic conductivity at 0 degC. An important feature of the composite cathode is that it has at least two components that are structurally integrated. The layered material is electrochemically inactive; however, upon structural integration with a spinel material, the layered material can be electrochemically activated and deliver a large amount of energy with stable cycling.

  10. Power generation using spinel manganese-cobalt oxide as a cathode catalyst for microbial fuel cell applications.

    PubMed

    Mahmoud, Mohamed; Gad-Allah, Tarek A; El-Khatib, K M; El-Gohary, Fatma

    2011-11-01

    This study focused on the use of spinel manganese-cobalt (Mn-Co) oxide, prepared by a solid state reaction, as a cathode catalyst to replace platinum in microbial fuel cells (MFCs) applications. Spinel Mn-Co oxides, with an Mn/Co atomic ratios of 0.5, 1, and 2, were prepared and examined in an air cathode MFCs which was fed with a molasses-laden synthetic wastewater and operated in batch mode. Among the three Mn-Co oxide cathodes and after 300 h of operation, the Mn-Co oxide catalyst with Mn/Co atomic ratio of 2 (MnCo-2) exhibited the highest power generation 113 mW/m2 at cell potential of 279 mV, which were lower than those for the Pt catalyst (148 mW/m2 and 325 mV, respectively). This study indicated that using spinel Mn-Co oxide to replace platinum as a cathodic catalyst enhances power generation, increases contaminant removal, and substantially reduces the cost of MFCs. PMID:21944282

  11. Phthalocyanine cathode materials for secondary lithium cells

    SciTech Connect

    Tamaki, J.; Yamaji, A.

    1982-01-01

    Discharge and charge characteristics of various phthalocyanine cathodes coupled with lithium metal are studied. The best capacity based only on cathode active material weight is 1440 A-hr/kg in the lithium/iron phthalocyanine system, and the cycle life of the lithium/Cu phthalocyanine system is more than 100 times at the discharge depth of 157 A-hr/kg. The cathode reaction mechanism is supposed to be lithium intercalation between phthalocyanine molecules. The results indicate that these phthalocyanines are promising cathode active materials for lithium secondary batteries.

  12. M{sup 3+}-modified LiMn{sub 2}O{sub 4} spinel intercalation cathodes. 1: Admetal effects on morphology and electrochemical performance

    SciTech Connect

    Robertson, A.D.; Lu, S.H.; Averill, W.F.; Howard, W.F. Jr.

    1997-10-01

    Low levels of trivalent cations were utilized to stabilize LiMn{sub 2}O{sub 4} spinel cathode materials against capacity decline during electrochemical cycling. Of the several single-phase products obtained, only those with Cr{sup 3+} and Ga{sup 3+} prevented capacity fade, and only LiCr{sub 0.02}Mn{sub 1.98}O{sub 4} exhibited acceptable initial reversible capacity. The external particle morphology was unchanged by the preparation or the admetal, and the internal structures were all converted to cong tou (onion) configurations during product synthesis. Grain size played a surprising role in cathode performance <25 {micro}m material had at least 10% lower capacity than larger or as-prepared Cr-doped LiMn{sub 2}O{sub 4}.

  13. Cells having cathodes containing polycarbon disulfide materials

    DOEpatents

    Okamoto, Yoshi; Skotheim, Terje A.; Lee, Hung S.

    1995-08-15

    The present invention relates to an electric current producing cell which contains an anode, a cathode having as a cathode-active material one or more carbon-sulfur compounds of the formula (CS.sub.x).sub.n, in which x takes values from 1.2 to 2.3 and n is greater or equal to 2, and where the redox process does not involve polymerization and de-polymerization by forming and breaking S--S bonds in the polymer backbone. The cell also contains an electrolyte which is chemically inert with respect to the anode and the cathode.

  14. Cells having cathodes containing polycarbon disulfide materials

    DOEpatents

    Okamoto, Y.; Skotheim, T.A.; Lee, H.S.

    1995-08-15

    The present invention relates to an electric current producing cell which contains an anode, a cathode having as a cathode-active material one or more carbon-sulfur compounds of the formula (CS{sub x}){sub n}, in which x takes values from 1.2 to 2.3 and n is greater or equal to 2, and where the redox process does not involve polymerization and de-polymerization by forming and breaking S--S bonds in the polymer backbone. The cell also contains an electrolyte which is chemically inert with respect to the anode and the cathode. 5 figs.

  15. Interfacial phenomena on selected cathode materials

    SciTech Connect

    Kostecki, Robert; Matsuo, Yoshiaki; McLarnon, Frank

    2001-06-22

    We have carried out a series of surface studies of selected cathode materials. Instrumental techniques such as Raman microscopy, surface enhanced Raman spectroscopy (SERS), and atomic force microscopy were used to investigate the cathode surfaces. The goal of this study was to identify detrimental processes which occur at the electrode/electrolyte interface and can lead to electrode degradation and failure during cycling and/or storage at elevated temperatures.

  16. Composite and diamond cold cathode materials

    SciTech Connect

    Worthington, M.S.; Wheeland, C.L.; Ramacher, K.; Doyle, E.

    1996-12-31

    Cold-cathode technology for Crossed-Field Amplifiers (CFAs) has not changed significantly over the last thirty years. The material typically used for cold cathode CFAs is either platinum (Pt) or beryllium (Be), although numerous other materials with higher secondary electron emission ratios have been tested. Beryllium cathodes display higher secondary emission ratios, {approximately} 3.4, than Pt, but require a partial pressure of oxygen to maintain a beryllium oxide (BeO) surface layer. These dispensers limit the life of the CFA, both directly, due to oxygen-source filament burnout, and indirectly, by the production of undesirable gases which adversely affect the performance of the CFA. In an attempt to reduce or eliminate the required oxygen dispenser output level, cathodes were constructed from three varieties of Be/BeO composite material and tested in L-4808s, standard forward-wave AEGIS CFAs. Diamond and diamond-like carbons are desirable as cathode materials because of their extremely high secondary electron emission ratio, greater than 20, but their use has previously been prohibitive because of cost, available, and physical characteristics. Because of recent advances in diamond growth technology it is now possible to deposit thin layers of diamond on a variety of geometric objects. In coordination with Penn State University four annular diamond emitters have been fabricated. The diamond emitters will be tested in a standard AEGIS CFA, both under vacuum and with a partial pressure of hydrogen.

  17. 2013 Estorm - Invited Paper - Cathode Materials Review

    SciTech Connect

    Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood III, David L

    2014-01-01

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403 431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783 789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  18. NANOWIRE CATHODE MATERIAL FOR LITHIUM-ION BATTERIES

    SciTech Connect

    John Olson, PhD

    2004-07-21

    This project involved the synthesis of nanowire ã-MnO2 and characterization as cathode material for high-power lithium-ion batteries for EV and HEV applications. The nanowire synthesis involved the edge site decoration nanowire synthesis developed by Dr. Reginald Penner at UC Irvine (a key collaborator in this project). Figure 1 is an SEM image showing ã-MnO2 nanowires electrodeposited on highly oriented pyrolytic graphite (HOPG) electrodes. This technique is unique to other nanowire template synthesis techniques in that it produces long (>500 um) nanowires which could reduce or eliminate the need for conductive additives due to intertwining of fibers. Nanowire cathode for lithium-ion batteries with surface areas 100 times greater than conventional materials can enable higher power batteries for electric vehicles (EVs) and hybrid electric vehicles (HEVs). The synthesis of the ã-MnO2 nanowires was successfully achieved. However, it was not found possible to co-intercalate lithium directly in the nanowire synthesis. Based on input from proposal reviewers, the scope of the project was altered to attempt the conversion into spinel LiMn2O4 nanowire cathode material by solid state reaction of the ã-MnO2 nanowires with LiNO3 at elevated temperatures. Attempts to perform the conversion on the graphite template were unsuccessful due to degradation of the graphite apparently caused by oxidative attack by LiNO3. Emphasis then shifted to quantitative removal of the nanowires from the graphite, followed by the solid state reaction. Attempts to quantitatively remove the nanowires by several techniques were unsatisfactory due to co-removal of excess graphite or poor harvesting of nanowires. Intercalation of lithium into ã-MnO2 electrodeposited onto graphite was demonstrated, showing a partial demonstration of the ã-MnO2 material as a lithium-ion battery cathode material. Assuming the issues of nanowires removal can be solved, the technique does offer potential for creating

  19. Improved cathode materials for microbial electrosynthesis

    SciTech Connect

    Zhang, T; Nie, HR; Bain, TS; Lu, HY; Cui, MM; Snoeyenbos-West, OL; Franks, AE; Nevin, KP; Russell, TP; Lovley, DR

    2013-01-01

    Microbial electrosynthesis is a promising strategy for the microbial conversion of carbon dioxide to transportation fuels and other organic commodities, but optimization of this process is required for commercialization. Cathodes which enhance electrode-microbe electron transfer might improve rates of product formation. To evaluate this possibility, biofilms of Sporomusa ovata, which are effective in acetate electrosynthesis, were grown on a range of cathode materials and acetate production was monitored over time. Modifications of carbon cloth that resulted in a positive-charge enhanced microbial electrosynthesis. Functionalization with chitosan or cyanuric chloride increased acetate production rates 6-7 fold and modification with 3-aminopropyltriethoxysilane gave rates 3-fold higher than untreated controls. A 3-fold increase in electrosynthesis over untreated carbon cloth cathodes was also achieved with polyaniline cathodes. However, not all strategies to provide positively charged surfaces were successful, as treatment of carbon cloth with melamine or ammonia gas did not stimulate acetate electrosynthesis. Treating carbon cloth with metal, in particular gold, palladium, or nickel nanoparticles, also promoted electrosynthesis, yielding electrosynthesis rates that were 6-,4.7- or 4.5-fold faster than the untreated control, respectively. Cathodes comprised of cotton or polyester fabric treated with carbon nanotubes yielded cathodes that supported acetate electrosynthesis rates that were similar to 3-fold higher than carbon cloth controls. Recovery of electrons consumed in acetate was similar to 80% for all materials. The results demonstrate that one approach to increase rates of carbon dioxide reduction in microbial electrosynthesis is to modify cathode surfaces to improve microbe-electrode interactions.

  20. Capacity improvement by deficit of transition metals in inverse spinel LiNi1/3Co1/3Mn1/3VO4 cathodes

    NASA Astrophysics Data System (ADS)

    Kitajou, Ayuko; Yoshida, Jun; Nakanishi, Shinji; Matsuda, Yasuaki; Kanno, Ryoji; Okajima, Toshihiro; Okada, Shigeto

    2016-01-01

    Although inverse spinel materials have attracted attention because of their unusually high voltage characteristics, their rechargeable capacities are generally less than 50 mAh g-1, as a result of the coexistence of Li and transition metal ions at 16d octahedral sites. This work attempted to improve cathode functioning by optimizing the quantities of Li and transition metal ions residing at the 16d sites of LiNi1/3Co1/3Mn1/3VO4. The rechargeable capacity of the LiNi0.28Co0.28Mn0.26V0.80O4 synthesized in the present study was found to be above 120 mAh g-1, representing the largest capacity reported to date for an inverse spinel material. The results of in-situ XANES analysis demonstrated that the charge-discharge reactions of LiNi1/3Co1/3Mn1/3VO4 corresponds to the Mn2+/Mn4+ and Co2+/Co3+ redox couples, mainly.

  1. Deciphering the thermal behavior of lithium rich cathode material by in situ X-ray diffraction technique

    NASA Astrophysics Data System (ADS)

    Muhammad, Shoaib; Lee, Sangwoo; Kim, Hyunchul; Yoon, Jeongbae; Jang, Donghyuk; Yoon, Jaegu; Park, Jin-Hwan; Yoon, Won-Sub

    2015-07-01

    Thermal stability is one of the critical requirements for commercial operation of high energy lithium-ion batteries. In this study, we use in situ X-ray diffraction technique to elucidate the thermal degradation mechanism of 0.5Li2MnO3-0.5LiNi0.33Co0.33Mn0.33O2 lithium rich cathode material in the absence and presence of electrolyte to simulate the real life battery conditions and compare its thermal behavior with the commercial LiNi0.33Co0.33Mn0.33O2 cathode material. We show that the thermal induced phase transformations in delithiated lithium rich cathode material are much more intense compared to similar single phase layered cathode material in the presence of electrolyte. The structural changes in both cathode materials with the temperature rise follow different trends in the absence and presence of electrolyte between 25 and 600 °C. Phase transitions are comparatively simple in the absence of electrolyte, the fully charged lithium rich cathode material demonstrates better thermal stability by maintaining its phase till 379 °C, and afterwards spinel structure is formed. In the presence of electrolyte, however, the spinel structure appears at 207 °C, subsequently it transforms to rock salt type cubic phase at 425 °C with additional metallic, metal fluoride, and metal carbonate phases.

  2. LiMn{sub 2-x}Cu{sub x}O{sub 4} spinels (0.1 {le} x {le} 0.5) - a new class of 5 V cathode materials for Li batteries : I. electrochemical, structural and spectroscopic studies.

    SciTech Connect

    Ein-Eli, Y.

    1998-10-05

    A series of electroactive spinel compounds, LiMn{sub 2{minus}x}Cu{sub x}O{sub 4} (0.1 {le} x {le} 0.5) has been studied by crystallographic, spectroscopic and electrochemical methods and by electron-microscopy. These LiMn{sub 2{minus}x}Cu{sub x}O{sub 4} spinels are nearly identical in structure to cubic LiMn{sub 2}O{sub 4} and successfully undergo reversible Li intercalation. The electrochemical data show a remarkable reversible electrochemical process at 4.9 V which is attributed to the oxidation of Cu{sup 2+} to Cu{sub 3+}. The inclusion of Cu in the spinel structure enhances the electrochemical stability of these materials upon cycling. The initial capacity of LiMn{sub 2{minus}x}Cu{sub x}O{sub 4} spinels decreases with increasing x from 130mAh/g in LiMn{sub 2}O{sub 4} (x=0) to 70 mAh/g in ''LiMn{sub 1.5}Cu{sub 0.5}O{sub 4}'' (x=0.5). The data also show slight shifts to higher voltage for the delithiation reaction that normally occurs at 4.1 V in standard Li{sub 1{minus}x}Mn{sub 2}O{sub 4} electrodes (1 {ge} x {ge} 0) corresponding to the oxidation of Mn{sup 3+} to Mn{sup 4+}. Although the powder X-ray diffraction pattern of ''LiMn{sub 1.5}Cu{sub 0.5}O{sub 4}'' shows a single-phase spinel product, neutron diffraction data show a small, but significant quantity of an impurity phase, the composition and structure of which could not be identified. X-ray absorption spectroscopy was used to gather information about the oxidation states of the manganese and copper ions. The composition of the spinel component in the LiMn{sub 1.5}Cu{sub 0.5}O{sub 4} was determined from X-ray diffraction and XANES data to be Li{sub 1.01}Mn{sub 1.67}Cu{sub 0.32}O{sub 4} suggesting, to a best approximation, that the impurity in the sample was a lithium-copper-oxide phase. The substitution of manganese by copper enhances the reactivity of the spinel structure towards hydrogen; the compounds are more easily reduced at moderate temperature ({approximately} 200 C) than LiMn{sub 2}O{sub 4}.

  3. High rate capability caused by surface cubic spinels in Li-rich layer-structured cathodes for Li-ion batteries

    PubMed Central

    Song, Bohang; Liu, Hongwei; Liu, Zongwen; Xiao, Pengfei; Lai, Man On; Lu, Li

    2013-01-01

    Modified Li-rich layered cathode Li(Li0.2Mn0.54Ni0.13Co0.13)O2 has been synthesized by a simple strategy of using surface treatment with various amounts (0–30 wt.%) of Super P (carbon black). Based on detailed characterizations from X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS), it is suggested that the phase transformation from Li2MnO3-type of structure to spinel-like phase take place at the surface regions of particles during post annealing process at 350°C, leading to increase in both first coulombic efficiency and rate capability, from 78% and 100 mAh·g−1 (charge capacity at 2500 mA·g−1) of the pristine material to 93.4% and 200 mAh·g−1. The evidences of spinel formation and the reasons for electrochemical enhancement are systematically investigated. PMID:24172795

  4. High performance cobalt-free Cu1.4Mn1.6O4 spinel oxide as an intermediate temperature solid oxide fuel cell cathode

    NASA Astrophysics Data System (ADS)

    Zhen, Shuying; Sun, Wang; Li, Peiqian; Tang, Guangze; Rooney, David; Sun, Kening; Ma, Xinxin

    2016-05-01

    In this work Cu1.4Mn1.6O4 (CMO) spinel oxide is prepared and evaluated as a novel cobalt-free cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). Single phase CMO powder with cubic structure is identified using XRD. XPS results confirm that mixed Cu+/Cu2+ and Mn3+/Mn4+ couples exist in the CMO sample, and a maximum conductivity of 78 S cm-1 is achieved at 800 °C. Meanwhile, CMO oxide shows good thermal and chemical compatibility with a 10 mol% Sc2O3 stabilized ZrO2 (ScSZ) electrolyte material. Impedance spectroscopy measurements reveals that CMO exhibits a low polarization resistance of 0.143 Ω cm2 at 800 °C. Furthermore, a Ni-ScSZ/ScSZ/CMO single cell demonstrates a maximum power density of 1076 mW cm-2 at 800 °C under H2 (3% H2O) as the fuel and ambient air as the oxidant. These results indicate that Cu1.4Mn1.6O4 is a superior and promising cathode material for IT-SOFCs.

  5. High performance cobalt-free Cu1.4Mn1.6O4 spinel oxide as an intermediate temperature solid oxide fuel cell cathode

    NASA Astrophysics Data System (ADS)

    Zhen, Shuying; Sun, Wang; Li, Peiqian; Tang, Guangze; Rooney, David; Sun, Kening; Ma, Xinxin

    2016-05-01

    In this work Cu1.4Mn1.6O4 (CMO) spinel oxide is prepared and evaluated as a novel cobalt-free cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). Single phase CMO powder with cubic structure is identified using XRD. XPS results confirm that mixed Cu+/Cu2+ and Mn3+/Mn4+ couples exist in the CMO sample, and a maximum conductivity of 78 S cm-1 is achieved at 800 °C. Meanwhile, CMO oxide shows good thermal and chemical compatibility with a 10 mol% Sc2O3 stabilized ZrO2 (ScSZ) electrolyte material. Impedance spectroscopy measurements reveals that CMO exhibits a low polarization resistance of 0.143 Ω cm2 at 800 °C. Furthermore, a Ni-ScSZ/ScSZ/CMO single cell demonstrates a maximum power density of 1076 mW cm-2 at 800 °C under H2 (3% H2O) as the fuel and ambient air as the oxidant. These results indicate that Cu1.4Mn1.6O4 is a superior and promising cathode material for IT-SOFCs.

  6. Role of morphology in the performance of LiFe0.5Mn1.5O4 spinel cathodes for lithium-ion batteries.

    PubMed

    Pico, M P; Álvarez-Serrano, I; López, M L; Veiga, M L

    2014-10-21

    Spinel oxides with composition LiMn2-xMxO4 (M, a transition metal) are intensively studied due to their remarkable electrochemical properties. This study deals with cathode materials based on the lithium iron manganese oxide LiFe0.5Mn1.5O4 synthesized by different methods (sol-gel, in solution and hydrothermal) in order to obtain samples with various morphologies. SEM results show microspheres, composed of nanosized/submicrometer-sized subunits, microrods with a less porous surface, and finally nanoparticles that form micro-sized aggregates. The samples obtained by both solution and hydrothermal methods provided the best electrochemical behavior. In all cases, the coulombic efficiency is around 90%, and it remains constant during the tested cycles. Specific capacities remain stable between 95% and 98% of capacity retention after series of cycles in samples formed by microspheres or micro-size aggregates. These values are notably higher than those obtained for the samples with particles of heterogeneous size (49%). A LiMn1.5Fe0.5O4/Li2MnO3 composite has been prepared by the solvothermal technique in order to increase its capacity and energy density. These cells show a good cyclability at different current densities. All cells based on these LiFe0.5Mn1.5O4 cathodes recover their discharge capacity when the current density returns to C/10. PMID:25160729

  7. The loss of material from the cathode of metal arcs

    NASA Technical Reports Server (NTRS)

    Seeliger, R.; Wulfhekel, H.

    1985-01-01

    A study was made of the effect of arc length, cathode thickness, current strength, gas pressure and the chemical nature of the cathode material and filling gases upon the material loss from Cu, Fe, and Ag cathodes in arcs. The results show that the analysis of the phenomenon is complex and the energy balance is difficult to formulate.

  8. Organic Cathode Materials for Rechargeable Batteries

    SciTech Connect

    Cao, Ruiguo; Qian, Jiangfeng; Zhang, Jiguang; Xu, Wu

    2015-06-28

    This chapter will primarily focus on the advances made in recent years and specify the development of organic electrode materials for their applications in rechargeable lithium batteries, sodium batteries and redox flow batteries. Four various organic cathode materials, including conjugated carbonyl compounds, conducting polymers, organosulfides and free radical polymers, are introduced in terms of their electrochemical performances in these three battery systems. Fundamental issues related to the synthesis-structure-activity correlations, involved work principles in energy storage systems, and capacity fading mechanisms are also discussed.

  9. Structural and Chemical Evolution of Li- and Mn-rich Layered Cathode Material

    SciTech Connect

    Zheng, Jianming; Xu, Pinghong; Gu, Meng; Xiao, Jie; Browning, Nigel D.; Yan, Pengfei; Wang, Chong M.; Zhang, Jiguang

    2015-02-24

    Lithium (Li)- and manganese-rich (LMR) layered-structure materials are very promising cathodes for high energy density lithium-ion batteries. However, their voltage fading mechanism and its relationships with fundamental structural changes are far from being sufficiently understood. Here we report the detailed phase transformation pathway in the LMR cathode (Li[Li0.2Ni0.2Mn0.6]O2) during cycling for the samples prepared by hydro-thermal assistant method. It is found the transformation pathway of LMR cathode is closely correlated to its initial structure and preparation conditions. The results reveal that LMR cathode prepared by HA approach experiences a phase transformation from the layered structure to a LT-LiCoO2 type defect spinel-like structure (Fd-3m space group) and then to a disordered rock-salt structure (Fm-3m space group). The voltage fade can be well correlated with the Li ion insertion into octahedral sites, rather than tetrahedral sites, in both defect spinel-like structure and disordered rock-salt structure. The reversible Li insertion/removal into/from the disordered rock-salt structure is ascribed to the Li excess environment that can satisfy the Li percolating in the disordered rock-salt structure despite the increased kinetic barrier. Meanwhile, because of the presence of a great amount of oxygen vacancies, a significant decrease of Mn valence is detected in the cycled particle, which is below that anticipated for a potentially damaging Jahn-Teller distortion (+3.5). Clarification of the phase transformation pathway, cation redistribution, oxygen vacancy and Mn valence change undoubtedly provides insights into a profound understanding on the voltage fade, and capacity degradation of LMR cathode. The results also inspire us to further enhance the reversibility of LMR cathode via improving its surface structural stability.

  10. Oxide diffusion in innovative SOFC cathode materials.

    PubMed

    Hu, Y; Thoréton, V; Pirovano, C; Capoen, E; Bogicevic, C; Nuns, N; Mamede, A-S; Dezanneau, G; Vannier, R N

    2014-01-01

    Oxide diffusion was studied in two innovative SOFC cathode materials, Ba(2)Co(9)O(14) and Ca(3)Co(4)O(9)+δ derivatives. Although oxygen diffusion was confirmed in the promising material Ba(2)Co(9)O(14), it was not possible to derive accurate transport parameters because of an oxidation process at the sample surface which has still to be clarified. In contrast, oxygen diffusion in the well-known Ca(3)Co(4)O(9)+δ thermoelectric material was improved when calcium was partly substituted with strontium, likely due to an increase of the volume of the rock salt layers in which the conduction process takes place. Although the diffusion coefficient remains low, interestingly, fast kinetics towards the oxygen molecule dissociation reaction were shown with surface exchange coefficients higher than those reported for the best cathode materials in the field. They increased with the strontium content; the Sr atoms potentially play a key role in the mechanism of oxygen molecule dissociation at the solid surface. PMID:25407246

  11. Chemical, structural, and electrochemical characterization of 5 V spinel and complex layered oxide cathodes of lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Tiruvannamalai Annamalai, Arun Kumar

    2007-12-01

    Lithium ion batteries have revolutionized the portable electronics market since their commercialization first by Sony Corporation in 1990. They are also being intensively pursued for electric and hybrid electric vehicle applications. Commercial lithium ion cells are currently made largely with the layered LiCoO 2 cathode. However, only 50% of the theoretical capacity of LiCoO 2 can be utilized in practical cells due to the chemical and structural instabilities at deep charge as well as safety concerns. These drawbacks together with the high cost and toxicity of Co have created enormous interest in alternative cathodes. In this regard, spinel LiMn2O4 has been investigated widely as Mn is inexpensive and environmentally benign. However, LiMn 2O4 exhibits severe capacity fade on cycling, particularly at elevated temperatures. With an aim to overcome the capacity fading problems, several cationic substitutions to give LiMn2-yMyO 4 (M = Cr, Fe, Co, Ni, and Cu) have been pursued in the literature. Among the cation-substituted systems, LiMn1.5Ni0.5O 4 has become attractive as it shows a high capacity of ˜ 130 mAh/g (theoretical capacity: 147 mAh/g) at around 4.7 V. With an aim to improve the electrochemical performance of the 5 V LiMn 1.5Ni0.5O4 spinel oxide, various cation-substituted LiMn1.5-yNi0.5-zMy+zO4 (M = Li, Mg, Fe, Co, and Zn) spinel oxides have been investigated by chemical lithium extraction. The cation-substituted LiMn1.5-yNi0.5-zM y+zO4 spinel oxides exhibit better cyclability and rate capability in the 5 V region compared to the unsubstituted LiMn1.5Ni 0.5O4 cathodes although the degree of manganese dissolution does not vary significantly. The better electrochemical properties of LiMn 1.5-yNi0.5-zMy+zO4 are found to be due to a smaller lattice parameter difference among the three cubic phases formed during the charge-discharge process. In addition, while the spinel Li1-xMn1.58Ni0.42O4 was chemically stable, the spinel Li1-xCo2O4 was found to exhibit both

  12. Nanostructured cathode materials for rechargeable lithium batteries

    NASA Astrophysics Data System (ADS)

    Myung, Seung-Taek; Amine, Khalil; Sun, Yang-Kook

    2015-06-01

    The prospect of drastic climate change and the ceaseless fluctuation of fossil fuel prices provide motivation to reduce the use of fossil fuels and to find new energy conversion and storage systems that are able to limit carbon dioxide generation. Among known systems, lithium-ion batteries are recognized as the most appropriate energy storage system because of their high energy density and thus space saving in applications. Introduction of nanotechnology to electrode material is beneficial to improve the resulting electrode performances such as capacity, its retention, and rate capability. The nanostructure is highly available not only when used alone but also is more highlighted when harmonized in forms of core-shell structure and composites with carbon nanotubes, graphene or reduced graphene oxides. This review covers syntheses and electrochemical properties of nanoscale, nanosized, and nanostructured cathode materials for rechargeable lithium batteries.

  13. Properties of cathode materials in alkaline cells

    NASA Astrophysics Data System (ADS)

    Salkind, A. J.; McBreen, J.; Freeman, R.; Parkhurst, W. A.

    1984-04-01

    Conventional and new cathode materials in primary and secondary alkaline cells were investigated for stability, structure, electrochemical reversibility and efficiency. Included were various forms of AgO for reserve type silver zinc batteries, a new material - AgNiO2 and several nickel electrodes for nickel cadmium and nickel hydrogen cells for aerospace applications. A comparative study was made of the stability of electroformed and chemically prepared AgO. Stability was correlated with impurities. After the first discharge AgNiO2 can be recharged to the monovalent level. The discharge product is predominantly silver. Plastic bonded nickel electrodes display a second plateau on discharge. Additions of Co(OH)2 largely eliminate this.

  14. Lithium and sodium battery cathode materials: computational insights into voltage, diffusion and nanostructural properties.

    PubMed

    Islam, M Saiful; Fisher, Craig A J

    2014-01-01

    Energy storage technologies are critical in addressing the global challenge of clean sustainable energy. Major advances in rechargeable batteries for portable electronics, electric vehicles and large-scale grid storage will depend on the discovery and exploitation of new high performance materials, which requires a greater fundamental understanding of their properties on the atomic and nanoscopic scales. This review describes some of the exciting progress being made in this area through use of computer simulation techniques, focusing primarily on positive electrode (cathode) materials for lithium-ion batteries, but also including a timely overview of the growing area of new cathode materials for sodium-ion batteries. In general, two main types of technique have been employed, namely electronic structure methods based on density functional theory, and atomistic potentials-based methods. A major theme of much computational work has been the significant synergy with experimental studies. The scope of contemporary work is highlighted by studies of a broad range of topical materials encompassing layered, spinel and polyanionic framework compounds such as LiCoO2, LiMn2O4 and LiFePO4 respectively. Fundamental features important to cathode performance are examined, including voltage trends, ion diffusion paths and dimensionalities, intrinsic defect chemistry, and surface properties of nanostructures. PMID:24202440

  15. The positive roles of integrated layered-spinel structures combined with nanocoating in low-cost Li-rich cathode Li[Li₀.₂Fe₀.₁Ni₀.₁₅Mn₀.₅₅]O₂ for lithium-ion batteries.

    PubMed

    Zhao, Taolin; Chen, Shi; Chen, Renjie; Li, Li; Zhang, Xiaoxiao; Xie, Man; Wu, Feng

    2014-12-10

    As the most promising cathodes of lithium-ion batteries, lithium-rich manganese-based layered oxides with high capacity suffer from poor cycle stability, poor rate capability, and fast voltage fading. Here we introduced AlF3 into the surface of layered lithium-rich cathode (Li[Li0.2Fe0.1Ni0.15Mn0.55]O2) as an artificial protective layer as well as an inducer of integrated layered-spinel structures to achieve both low cost and high capacity. The reduced irreversible capacity loss, improved cycling stability, and superior high-rate capability were ascribed to the combination of AlF3 nanocoating and the unique structures as well as the low charge transfer resistance. Besides, the intractable issue, fast voltage fading of the layered lithium-rich cathode was also alleviated. Such materials with both low cost and high capacity are considered to be promising candidate cathodes to achieve lithium-ion batteries with high energy and high power. PMID:25402183

  16. The dependence of vircator oscillation mode on cathode material

    NASA Astrophysics Data System (ADS)

    Li, Limin; Liu, Lie; Cheng, Guoxin; Xu, Qifu; Wan, Hong; Chang, Lei; Wen, Jianchun

    2009-06-01

    This paper presents the effects of cathode materials on the oscillation mode of a virtual cathode oscillator (vircator). In the case of the stainless steel cathode, an oscillation mode hopping appeared with two separate frequencies. Interestingly, the vircator using the carbon fiber cathode exhibited an almost unchanged microwave frequency throughout the microwave pulse. To understand this phenomenon, several parameters are compared, including the diode voltage, accelerating gap, emitting area, and beam uniformity. It was found that a flat-top voltage and a relatively stable gap will provide a possibility of generating a constant microwave frequency. Further, the cathode operated in a regime where the beam current was between the space-charge limited current determined by Child-Langmuir law and the bipolar flow. On the cathode surface, the electron emission is initiated from discrete plasma spots and next from a continuing area, while there is a liberation process of multilayer gases on the anode surface. The changes in the emitting area of carbon fiber cathode showed a self-quenching process, which is not observed in the case of stainless steel cathode. The two-dimensional effect of microwave frequency is introduced, and the obtained results supported the experimental observations on the oscillation mode. By examining the cross section of electron beam, the electron beam for carbon fiber cathode was significantly centralized, while the discrete beam spots appeared for stainless steel cathode. These results show that the slowed diode closure, high emission uniformity, and stable microwave frequency tend to be closely tied.

  17. A Novel Cathode Material for Cathodic Dehalogenation of 1,1-Dibromo Cyclopropane Derivatives.

    PubMed

    Gütz, Christoph; Selt, Maximilian; Bänziger, Markus; Bucher, Christoph; Römelt, Christina; Hecken, Nadine; Gallou, Fabrice; Galvão, Tomás R; Waldvogel, Siegfried R

    2015-09-28

    Leaded bronze turned out to be an excellent cathode material for the dehalogenation reaction of cyclopropanes without affecting the strained molecular entity. With this particular alloy, beneficial properties of lead cathodes are conserved, whereas the corrosion of cathode is efficiently suppressed. The solvent in the electrolyte determines whether a complete debromination reaction is achieved or if the process can be selectively stopped at the monobromo cyclopropane intermediate. The electroorganic conversion tolerates a variety of functional groups and can be conducted at rather complex substrates like cyclosporine A. This approach allows the sustainable preparation of cyclopropane derivatives. PMID:26250701

  18. Chromium (V) compounds as cathode material in electrochemical power sources

    DOEpatents

    Delnick, Frank M.; Guidotti, Ronald A.; McCarthy, David K.

    1985-01-01

    A cathode for use in a thermal battery, comprising a chromium (V) compound. The preferred materials for this use are Ca.sub.5 (CrO.sub.4).sub.3 Cl, Ca.sub.5 (CrO.sub.4).sub.3 OH, and Cr.sub.2 O.sub.5. The chromium (V) compound can be employed as a cathode material in ambient temperature batteries when blended with a suitably conductive filler, preferably carbon black.

  19. Chromium (V) compounds as cathode material in electrochemical power sources

    DOEpatents

    Delnick, F.M.; Guidotti, R.A.; McCarthy, D.K.

    A cathode for use in a thermal battery, comprising a chromium (V) compound. The preferred materials for this use are Ca/sub 5/(CrO/sub 4/)/sub 3/Cl, Ca/sub 5/(CrO/sub 4/)OH, and Cr/sub 2/O/sub 5/. The chromium (V) compound can be employed as a cathode material in ambient temperature batteries when blended with a suitably conductive filler, preferably carbon black.

  20. Two-step oxalate approach for the preparation of high performance LiNi0.5Mn1.5O4 cathode material with high voltage

    NASA Astrophysics Data System (ADS)

    Liu, Zushan; Jiang, Yangmei; Zeng, Xiaoyuan; Xiao, Guan; Song, Huiyu; Liao, Shijun

    2014-02-01

    A high voltage cathode material, LiNi0.5Mn1.5O4, is synthesized with a two-step approach, in which the nickel-manganese oxalate precipitate is firstly obtained by adding oxalic acid to the solution of nickel and manganese ions precursors, followed by calcining the oxalates to obtain spinel nickel-manganese oxide, incorporating lithium ions with ball milling and calcining at 900 °C for 15 h. The materials are characterized with TG, XRD, SEM, BET and FTIR; it is revealed that both nickel-manganese oxide and final LiNi0.5Mn1.5O4 have well defined spinel structure. The LiNi0.5Mn1.5O4 spinel materials exhibit high capacities and good cyclic stability, the capacity of the materials is in the range from 126 to 136 mAh -1, depending on the calcining temperatures. The sample calcined at an optimal temperature of 900 °C exhibits best performance, the capacity is high up to 136 mAh g-1 at tenth cycle and the capacity retention after 50 cycles is 93%. For the sample prepared by mixing and milling oxalate with lithium salt, the discharge capacity is only 115 mAh g-1. We suggest that the spinel oxide derived from oxalate may play an important role for the high performance and high stability of the final cathode materials.

  1. Layered Lithium-Rich Oxide Nanoparticles Doped with Spinel Phase: Acidic Sucrose-Assistant Synthesis and Excellent Performance as Cathode of Lithium Ion Battery.

    PubMed

    Chen, Min; Chen, Dongrui; Liao, Youhao; Zhong, Xiaoxin; Li, Weishan; Zhang, Yuegang

    2016-02-01

    Nanolayered lithium-rich oxide doped with spinel phase is synthesized by acidic sucrose-assistant sol-gel combustion and evaluated as the cathode of a high-energy-density lithium ion battery. Physical characterizations indicate that the as-synthesized oxide (LR-SN) is composed of uniform and separated nanoparticles of about 200 nm, which are doped with about 7% spinel phase, compared to the large aggregated ones of the product (LR) synthesized under the same condition but without any assistance. Charge/discharge demonstrates that LR-SN exhibits excellent rate capability and cyclic stability: delivering an average discharge capacity of 246 mAh g(-1) at 0.2 C (1C = 250 mA g(-1)) and earning a capacity retention of 92% after 100 cycles at 4 C in the lithium anode-based half cell, compared to the 227 mA g(-1) and the 63% of LR, respectively. Even in the graphite anode-based full cell, LR-SN still delivers a capacity of as high as 253 mAh g(-1) at 0.1 C, corresponding to a specific energy density of 801 Wh kg(-1), which are the best among those that have been reported in the literature. The separated nanoparticles of the LR-SN provide large sites for charge transfer, while the spinel phase doped in the nanoparticles facilitates lithium ion diffusion and maintains the stability of the layered structure during cycling. PMID:26799282

  2. Perspectives on Li and transition metal fluoride phosphates as cathode materials for a new generation of Li-ion batteries.

    PubMed

    Antipov, Evgeny V; Khasanova, Nellie R; Fedotov, Stanislav S

    2015-01-01

    To satisfy the needs of rapidly growing applications, Li-ion batteries require further significant improvements of their key properties: specific energy and power, cyclability, safety and costs. The first generation of cathode materials for Li-ion batteries based on mixed oxides with either spinel or rock-salt derivatives has already been widely commercialized, but the potential to improve the performance of these materials further is almost exhausted. Li and transition metal inorganic compounds containing different polyanions are now considered as the most promising cathode materials for the next generation of Li-ion batteries. Further advances in cathode materials are considered to lie in combining different anions [such as (XO4) (n-) and F(-)] in the anion sublattice, which is expected to enhance the specific energy and power of these materials. This review focuses on recent advances related to the new class of cathode materials for Li-ion batteries containing phosphate and fluoride anions. Special attention is given to their crystal structures and the relationships between structure and properties, which are important for their possible practical applications. PMID:25610630

  3. Perspectives on Li and transition metal fluoride phosphates as cathode materials for a new generation of Li-ion batteries

    PubMed Central

    Antipov, Evgeny V.; Khasanova, Nellie R.; Fedotov, Stanislav S.

    2015-01-01

    To satisfy the needs of rapidly growing applications, Li-ion batteries require further significant improvements of their key properties: specific energy and power, cyclability, safety and costs. The first generation of cathode materials for Li-ion batteries based on mixed oxides with either spinel or rock-salt derivatives has already been widely commercialized, but the potential to improve the performance of these materials further is almost exhausted. Li and transition metal inorganic compounds containing different polyanions are now considered as the most promising cathode materials for the next generation of Li-ion batteries. Further advances in cathode materials are considered to lie in combining different anions [such as (XO4)n− and F−] in the anion sublattice, which is expected to enhance the specific energy and power of these materials. This review focuses on recent advances related to the new class of cathode materials for Li-ion batteries containing phosphate and fluoride anions. Special attention is given to their crystal structures and the relationships between structure and properties, which are important for their possible practical applications. PMID:25610630

  4. The addition of ortho-hexagon nano spinel Co3O4 to improve the performance of activated carbon air cathode microbial fuel cell.

    PubMed

    Ge, Baochao; Li, Kexun; Fu, Zhou; Pu, Liangtao; Zhang, Xi

    2015-11-01

    Commercial Co3O4 and ortho-hexagon spinel nano-Co3O4 (OHSNC) were doped in the AC at a different percentage (5%, 10% and 15%) to enhance the performance of microbial fuel cell (MFC). The maximum power density of MFC with 10% OHSNC doped cathode was 1500±14 mW m(-2), which was 97.36% and 41.24% higher than that with the bare AC air cathode and commercial Co3O4 respectively. The electrocatalytic behavior for their better performance was discussed in detail with the help of various structural and electrochemical techniques. The OHSNC was characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM). The results showed that the improved performance owed to the enhancement of both kinetics activity and the number of electron transfer in the ORR, and the internal resistance was largely reduced. Therefore, OHSNC was proved to be an excellent cathodic catalyst in AC air cathode MFC. PMID:26112347

  5. Oxygen vacancies and ordering of d-levels control voltage suppression in oxide cathodes: the case of spinel LiNi0.5Mn1.5O4-δ

    SciTech Connect

    Sushko, Petr V.; Rosso, Kevin M.; Zhang, Jiguang; Liu, Jun; Sushko, Maria L.

    2013-06-19

    Spinel Li-Mn rich oxides form one of the most promising classes of high voltage cathode materials for next generation Li-ion batteries for electric vehicle applications. Our simulations for spinel LiNi0.5Mn1.5O4 (LNMO) show that neutral oxygen vacancies promote formation of Ni-rich regions, which are negatively charged with respect to the lattice. This makes the electrons associated with these vacancies to localize on Mn3+ eg states of two types: shallow states in the Ni-rich regions and deep states in the Ni-poor regions. The positive electrostatic potential produced by the oxygen vacancies and the existence of the shallow and deep Mn3+ states result in appearance of the low-voltage region at high Li content and high-voltage region at low Li content. This is consistent with characteristic changes in the voltage capacity curves observed experimentally during electrochemical cycling. We propose that doping LNMO with judiciously selected cations can help to remedy voltage suppression effects. This approach may also be used to enhance the electrochemical stability of Li-Mn rich oxides, which tend to experience continuous voltage fade.

  6. A SYSTEMATIC STUDY OF INTERCALATION COMPOUNDS AS CATHODE MATERIALS FOR LITHIUM BATTERIES.

    SciTech Connect

    YANG,X.Q.; MCBREEN,J.

    2001-06-08

    Three types of intercalation Compounds, LiMn{sub 2}O{sub 4} with spinel structure, LiNiO{sub 2} and LiCoO{sub 2} with layered structure are widely studied as cathode materials for lithium-ion batteries. Among them, LiCoO{sub 2} is the most widely used cathode material in commercial lithium battery cells. LiNiO{sub 2} has same theoretical capacity as LiCoO{sub 2}, but is less expensive. However its application in lithium batteries has not been realized due to serious safety concerns. Substituting a portion of Ni in LiNiO{sub 2} with other cations has been pursued as a way to improve its safety characteristics. It was reported that Co doped LiNi{sub 0.8}Co{sub 0.2}O{sub 2} showed better thermal stability than pure LiNiO{sub 2}. Many new materials have been developed aimed in increasing the capacity and improving the thermal stability and cyclability. Most of these new materials are based on these three types of materials and modified their compositions and structures by doping. However, most of the efforts on developing new cathode materials have been done on the empirical base without guidelines from the systematic studies on the relationship between the performance and the structural changes of the cathode materials. Exploring this relationship is very important not only in guiding the development of new materials, but also in improving the performance and safety aspect for the existing cathode materials for lithium ion batteries. Using conventional x-ray source and a specially designed battery cell with beryllium windows, Dahn and co-workers have published several papers on the structural changes of LiNiO{sub 2} cathodes 1 and LiCoO{sub 2} cathodes 2 during charge. Unfortunately, the charging voltage was limited to below 4.3 V due to the problem of beryllium window corrosion at higher voltage. However, the voltage range between 4.3 V and 5.2 V is the most important region for studying the relationship between the thermal stability and structural changes during

  7. Durability and performance optimization of cathode materials for fuel cells

    NASA Astrophysics Data System (ADS)

    Colon-Mercado, Hector Rafael

    The primary objective of this dissertation is to develop an accelerated durability test (ADT) for the evaluation of cathode materials for fuel cells. The work has been divided in two main categories, namely high temperature fuel cells with emphasis on the Molten Carbonate Fuel Cell (MCFC) cathode current collector corrosion problems and low temperature fuel cells in particular Polymer Electrolyte Fuel Cell (PEMFC) cathode catalyst corrosion. The high operating temperature of MCFC has given it benefits over other fuel cells. These include higher efficiencies (>50%), faster electrode kinetics, etc. At 650°C, the theoretical open circuit voltage is established, providing low electrode overpotentials without requiring any noble metal catalysts and permitting high electrochemical efficiency. The waste heat is generated at sufficiently high temperatures to make it useful as a co-product. However, in order to commercialize the MCFC, a lifetime of 40,000 hours of operation must be achieved. The major limiting factor in the MCFC is the corrosion of cathode materials, which include cathode electrode and cathode current collector. In the first part of this dissertation the corrosion characteristics of bare, heat-treated and cobalt coated titanium alloys were studied using an ADT and compared with that of state of the art current collector material, SS 316. PEMFCs are the best choice for a wide range of portable, stationary and automotive applications because of their high power density and relatively low-temperature operation. However, a major impediment in the commercialization of the fuel cell technology is the cost involved due to the large amount of platinum electrocatalyst used in the cathode catalyst. In an effort to increase the power and decrease the cathode cost in polymer electrolyte fuel cell (PEMFC) systems, Pt-alloy catalysts were developed to increase its activity and stability. Extensive research has been conducted in the area of new alloy development and

  8. Understanding the Origin of Enhanced Performances in Core-Shell and Concentration-Gradient Layered Oxide Cathode Materials.

    PubMed

    Song, Dawei; Hou, Peiyu; Wang, Xiaoqing; Shi, Xixi; Zhang, Lianqi

    2015-06-17

    Core-shell and concentration-gradient layered oxide cathode materials deliver superior electrochemical properties such as long cycle life and outstanding thermal stability. However, the origin of enhanced performance is not clear and seldom investigated until now. Here, a specific structured layered oxide (LiNi0.5Co0.2Mn0.3O2) consisting of concentration-gradient core, transition layer, and stable outer shell, is designed and achieved from double-shelled precursors to overcome the great challenge by comparison with the normal layered LiNi0.5Co0.2Mn0.3O2. As expected, the specific structured layered oxide displays excellent cycle life and thermal stability. After numerous cycles, the valence state of Ni and Co at normal layered oxide surface tends to a higher oxidation state than that of the specific structured oxide, and the spinel phase is observed on particle surface of normal layered oxide. Also, the deficient spinel/layered mixed phases lead to high surface film and charge-transfer resistance for normal layered oxide, whereas the specific structured one still remains a layered structure. Those results first illustrate the origin of improved electrochemical performance of layered core-shell and concentration-gradient cathode materials for lithium-ion batteries. PMID:26017733

  9. Cells having cathodes with thiocyanogen-containing cathode-active materials

    SciTech Connect

    Rao, B.M.

    1980-03-11

    An electric current-producing cell which contains: (A) an anode metal higher than hydrogen in the electromotive series and having an atomic number no greater than 30; (B) a cathode material containing thiocyanogen, said material being selected from the group consisting of: (I) thiocyanogen of the formula: (ScN)/sub 2/ (II) parathiocyanogen of the formula: (ScN)/sub x/ wherein X is greater than 2; (III) halothiocyanogen of the formula: YScN wherein Y is a halogen selected from the group consisting of F, Cl, Br and I; (IV) parahalothiocyanogen of the formula: (YScN)/sub y/ wherein Y is as described above and wherein Y is equal to or greater than 2; (V) perthiocyanogen complex of an amine; (VI) perthiocyanogen complex of an ammonium ion; (VII) thiocyanogen complex of a metal cation which is the same as the metal cation in the anode; (VIII) thiocyanogen complex of a metal cation which is higher in the electromotive series than the metal cation in the anode; (IX) cathode intercalated material having halothiocyanogen of paragraph (III) above intercalated therein; (X) cathode intercalated material having parahalothiocyanogen of paragraph (IV) above intercalated therein; (XI) polymeric thiocyanogen-containing material obtained from oxidation of a polyvinyl thiocyanate; (XII) ammonium thiocyanate salt complex of thiocyanogen of paragraph (I) above; (XIII) ammonium thiocyanate salt complex of parathiocyanogen of paragraph (II) above; (XIV) ammonium thiocyanate salt complex of halothiocyanogen of paragraph (III) above; and (XV) ammonium thiocyanate salt complex of parahalothiocyanogen of paragraph (IV) above; and (C) an electrolyte which is chemically inert with respect to said anode and said cathode.

  10. Refractory Materials based on Magnesia-Alumina Spinel for Improved Performance in Coal Gasification Environments

    SciTech Connect

    Hemrick, James Gordon; Armstrong, Beth L; Rodrigues-Schroer, Angela; Colavito,; Smith, Jeffrey D; O'Hara, Kelley

    2013-01-01

    As part of a larger project to develop novel refractory systems and techniques to reduce energy consumption of refractory lined vessels, a team composed of Oak Ridge National Laboratory, refractory manufacturer Minteq International, Inc., and academic partner Missouri University of Science and Technology have developed new refractory materials and coating systems specifically for application in coal gasification environments. Materials were developed under this U.S. DOE funded project to address the need for innovative refractory compositions by developing MgO-Al2O3 spinel gunnable refractory compositions utilizing new aggregate materials, bond systems, protective coatings, and phase formation techniques. Work was conducted to develop and deploy these new materials and to develop and apply low cost coatings using a colloidal approach for protection against attack of the refractory brick by the serviced environment. Additionally, a light-weight back-up refractory system was developed to help offset the high thermal conductivity inherent in spinel materials. This paper discusses the efforts involved in the development of these materials, along with the laboratory testing and evaluation of these materials leading to relevant results achieved toward the reduction of chemical reactions and mechanical degradation by the service environment though compositional and processing modifications.

  11. First-principles material modeling of solid-state electrolytes with the spinel structure.

    PubMed

    Mees, Maarten J; Pourtois, Geoffrey; Rosciano, Fabio; Put, Brecht; Vereecken, Philippe M; Stesmans, André

    2014-03-21

    Ionic diffusion through the novel (AlxMg1-2xLix)Al2O4 spinel electrolyte is investigated using first-principles calculations, combined with the Kinetic Monte Carlo algorithm. We observe that the ionic diffusion increases with the lithium content x. Furthermore, the structural parameters, formation enthalpies and electronic structures of (AlxMg1-2xLix)Al2O4 are calculated for various stoichiometries. The overall results indicate the (AlxMg1-2xLix)Al2O4 stoichiometries x = 0.2…0.3 as most promising. The (AlxMg1-2xLix)Al2O4 electrolyte is a potential candidate for the all-spinel solid-state battery stack, with the material epitaxially grown between well-known spinel electrodes, such as LiyMn2O4 and Li4+3yTi5O12 (y = 0…1). Due to their identical crystal structure, a good electrolyte-electrode interface is expected. PMID:24503944

  12. Why is magnesia spinel a radiation-resistant material?

    NASA Astrophysics Data System (ADS)

    Kinoshita, C.; Fukumoto, K.; Fukuda, K.; Garner, F. A.; Hollenberg, G. W.

    1995-03-01

    Side-by-side irradiation of stoichiometric MgAl 2O 4 and α-Al 2O 3 in JOYO shows that the radiation-induced microstructural evolution to exposure of ≤ 6 dpa proceeds by very different paths in these two materials. The large difference in dislocation loop evolution appears to account for the ease of void swelling in α-Al 2O 3 and the strong resistance to void formation in MgAl 2O 4. Irradiation of MgAl 2O 4 to much higher exposure (22-230 dpa) in FFTF confirms the details of the dislocation evolution, which involves a progressive change in Burgers vector and habit plane as interstitial loops increase in size. Constraints unique to the MgAl 2O 4 crystal structure do not allow the formation of dislocation network structures that favor swelling.

  13. Process for Low Cost Domestic Production of LIB Cathode Materials

    SciTech Connect

    Thurston, Anthony

    2012-10-31

    The objective of the research was to determine the best low cost method for the large scale production of the Nickel-Cobalt-Manganese (NCM) layered cathode materials. The research and development focused on scaling up the licensed technology from Argonne National Laboratory in BASF’s battery material pilot plant in Beachwood Ohio. Since BASF did not have experience with the large scale production of the NCM cathode materials there was a significant amount of development that was needed to support BASF’s already existing research program. During the three year period BASF was able to develop and validate production processes for the NCM 111, 523 and 424 materials as well as begin development of the High Energy NCM. BASF also used this time period to provide free cathode material samples to numerous manufactures, OEM’s and research companies in order to validate the ma-terials. The success of the project can be demonstrated by the construction of the production plant in Elyria Ohio and the successful operation of that facility. The benefit of the project to the public will begin to be apparent as soon as material from the production plant is being used in electric vehicles.

  14. In Situ X-ray Diffraction Studies of Li(sub x)Mn(sub 2)O(sub 4) Cathode Materials by Synchrotron X-ray Radiation

    SciTech Connect

    Yang, X. Q.; Sun, X.; Lee, S. J.; McBreen, J.; Mukerjee, S.; Daroux, M. L.; Xing, X. K.

    1998-11-01

    In Situ x-ray diffraction studies on Li{sub x}Mn{sub 2}O{sub 4} spinel cathode materials during charge-discharge cycles were carried out by using a synchrotron as x-ray source. Lithium rich (x = 1.03-1.06) spinel materials obtained from two different sources were studied. Three cubic phases with different lattice constants were observed during charge-discharge cycles in all the samples when a Sufficiently low charge-discharge rate (C/10) was used. There are two regions of two-phase coexistence between these three phases, indicating that both phase transitions are first order. The separation of the Bragg peaks representing these three phases varies from sample to sample and also depends on the charge-discharge rate. These results show that the de-intercalation of lithium in lithium-rich spinel cathode materials proceeds through a series of phase transitions from a lithium-rich phase to a lithium-poor phase and finally to a {lambda}-MnO{sub 2} like cubic phase, rather than through a continuous lattice constant contraction in a single phase.

  15. Functioning mechanism of AlF3 coating on the Li- and Mn-rich cathode materials

    SciTech Connect

    Zheng, Jianming; Gu, Meng; Xiao, Jie; Polzin, Bryant; Yan, Pengfei; Chen, Xilin; Wang, Chong M.; Zhang, Jiguang

    2014-11-25

    Li- and Mn-rich (LMR) material is a very promising cathode for lithium ion batteries because of their high theoretical energy density (~900 Wh kg-1) and low cost. However, their poor long-term cycling stability, voltage fade, and low rate capability are significant barriers hindered their practical applications. Surface coating, e.g. AlF3 coating, can significantly improve the capacity retention and enhance the rate capability. However, the fundamental mechanism of this improvement and the microstructural evolution related to the surface coating is still not well understood. Here, we report systematic studies of the microstructural changes of uncoated and AlF3-coated materials before and after cycling using aberration-corrected scanning/transmission electron microscopy and electron energy loss spectroscopy. The results reveal that surface coating can reduce the oxidation of electrolyte at high voltage, thus suppressing the accumulation of SEI layer on electrode particle surface. Surface coating also enhances structural stability of the surface region (especially the electrochemically transformed spinel-like phase), and protects the electrode from severe etching/corrosion by the acidic species in the electrolyte, therefore limiting the degradation of the material. Moreover, surface coating can alleviate the undesirable voltage fade by minimize layered-spinel phase transformation in the bulk region of the materials. These fundamental findings may also be widely applied to explain the functioning mechanism of other surface coatings used in a broad range of electrode materials.

  16. Novel Composite Materials for SOFC Cathode-Interconnect Contact

    SciTech Connect

    J. H. Zhu

    2009-07-31

    This report summarized the research efforts and major conclusions of our University Coal Research Project, which focused on developing a new class of electrically-conductive, Cr-blocking, damage-tolerant Ag-perovksite composite materials for the cathode-interconnect contact of intermediate-temperature solid oxide fuel cell (SOFC) stacks. The Ag evaporation rate increased linearly with air flow rate initially and became constant for the air flow rate {ge} {approx} 1.0 cm {center_dot} s{sup -1}. An activation energy of 280 KJ.mol{sup -1} was obtained for Ag evaporation in both air and Ar+5%H{sub 2}+3%H{sub 2}O. The exposure environment had no measurable influence on the Ag evaporation rate as well as its dependence on the gas flow rate, while different surface morphological features were developed after thermal exposure in the oxidizing and reducing environments. Pure Ag is too volatile at the SOFC operating temperature and its evaporation rate needs to be reduced to facilitate its application as the cathode-interconnect contact. Based on extensive evaporation testing, it was found that none of the alloying additions reduced the evaporation rate of Ag over the long-term exposure, except the noble metals Au, Pt, and Pd; however, these noble elements are too expensive to justify their practical use in contact materials. Furthermore, the addition of La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSM) into Ag to form a composite material also did not significantly modify the Ag evaporation rate. The Ag-perovskite composites with the perovskite being either (La{sub 0.6}Sr{sub 0.4})(Co{sub 0.8}Fe{sub 0.2})O{sub 3} (LSCF) or LSM were systematically evaluated as the contact material between the ferritic interconnect alloy Crofer 22 APU and the LSM cathode. The area specific resistances (ASRs) of the test specimens were shown to be highly dependent on the volume percentage and the type of the perovskite present in the composite contact material as well as the amount of thermal cycling

  17. New Cathode Materials for Intermediate Temperature Solid Oxide Fuel Cells

    SciTech Connect

    Allan J. Jacobson

    2005-11-17

    Operation of SOFCs at intermediate temperatures (500-800 C) requires new combinations of electrolyte and electrode materials that will provide both rapid ion transport across the electrolyte and electrode--electrolyte interfaces and efficient electrocatalysis of the oxygen reduction and fuel oxidation reactions. This project concentrates on materials and issues associated with cathode performance that are known to become limiting factors as the operating temperature is reduced. The specific objectives of the proposed research are to develop cathode materials that meet the electrode performance targets of 1.0 W/cm{sup 2} at 0.7 V in combination with YSZ at 700 C and with GDC, LSGM or bismuth oxide based electrolytes at 600 C. The performance targets imply an area specific resistance of {approx}0.5 {Omega}cm{sup 2} for the total cell. The research strategy is to investigate both established classes of materials and new candidates as cathodes, to determine fundamental performance parameters such as bulk diffusion, surface reactivity and interfacial transfer, and to couple these parameters to performance in single cell tests. In this report, the oxygen exchange kinetics of a P2 composition are described in detail. The oxygen exchange kinetics of the oxygen deficient double perovskite LnBaCo{sub 2}O{sub 5.5+{delta}} (Ln=Pr and Nd) have been determined by electrical conductivity relaxation. The high electronic conductivity and rapid diffusion and surface exchange kinetics of PBCO suggest its application as cathode material in intermediate temperature solid oxide fuel cells.

  18. Structural changes and thermal stability of charged LiNi 1/3Co 1/3Mn 1/3O 2 cathode material for Li-ion batteries studied by time-resolved XRD

    NASA Astrophysics Data System (ADS)

    Nam, Kyung-Wan; Yoon, Won-Sub; Yang, Xiao-Qing

    Structural changes and their relationship with thermal stability of charged Li 0.33Ni 1/3Co 1/3Mn 1/3O 2 cathode samples have been studied using time-resolved X-ray diffraction (TR-XRD) in a wide temperature from 25 to 600 °C with and without the presence of electrolyte in comparison with Li 0.27Ni 0.8Co 0.15Al 0.05O 2 cathodes. Unique phase transition behavior during heating is found for the Li 0.33Ni 1/3Co 1/3Mn 1/3O 2 cathode samples: when no electrolyte is present, the initial layered structure changes first to a LiM 2O 4-type spinel, and then to a M 3O 4-type spinel and remains in this structure up to 600 °C. For the Li 0.33Ni 1/3Co 1/3Mn 1/3O 2 cathode sample with electrolyte, additional phase transition from the M 3O 4-type spinel to the MO-type rock salt phase takes place from about 400 to 441 °C together with the formation of metallic phase at about 460 °C. The major difference between this type of phase transitions and that for Li 0.27Ni 0.8Co 0.15Al 0.05O 2 in the presence of electrolyte is the delayed phase transition from the spinel-type to the rock salt-type phase by stretching the temperature range of spinel phases from about 20 to 140 °C. This unique behavior is considered as the key factor of the better thermal stability of the Li 1-xNi 1/3Co 1/3Mn 1/3O 2 cathode materials.

  19. Cathode materials for the molten carbonate fuel cell

    SciTech Connect

    Kucera, G.H.; Brown, A.P.; Roche, M.F.; Indacochea, E.J.; Krumpelt, M.; Myles, K.M.

    1993-08-01

    Both LiFeO{sub 2} and Li{sub 2},MnO{sub 3} were stable in the cathode environment, had low solubility, and were nonprecipitating in the anode environment. Dopants were employed to enhance the electronic conductivity of both materials. Cobalt-doped LiFeO{sub 2} was a factor of 30 more conductive than the undoped LiFeO{sub 2}; Nb-doped Li{sub 2}MnO{sub 3} was a factor of 60 more conductive than its undoped form. However, only the Co-doped LiFeO{sub 2} Li{sub 2} exhibited the desired p-type conduction. Half- and full-cell tests with Co-doped LiFeO{sub 2} as the cathode material showed that its performance strongly depended on the oxygen partial pressure. Under simulated high-pressure conditions, where the O{sub 2} partial pressure was 70 kPa, the performance was good. LiCoO{sub 2} had low solubility and was a good electronic conductor undoped. In addition, it exhibited p-type conduction, and, when used as a cathode material, gave good cell performance. It precipitated as cobalt metal under reducing conditions in anode. However, neither rate of deposition nor conditions influencing deposition and location are known.

  20. Material and Energy Flows in the Production of Cathode and Anode Materials for Lithium Ion Batteries

    SciTech Connect

    Dunn, Jennifer B.; James, Christine; Gaines, Linda; Gallagher, Kevin; Dai, Qiang; Kelly, Jarod C.

    2015-09-01

    The Greenhouse gases, Regulated Emissions and Energy use in Transportation (GREET) model has been expanded to include four new cathode materials that can be used in the analysis of battery-powered vehicles: lithium nickel cobalt manganese oxide (LiNi0.4Co0.2Mn0.4O2 [NMC]), lithium iron phosphate (LiFePO4 [LFP]), lithium cobalt oxide (LiCoO2 [LCO]), and an advanced lithium cathode (0.5Li2MnO3∙0.5LiNi0.44Co0.25Mn0.31O2 [LMR-NMC]). In GREET, these cathode materials are incorporated into batteries with graphite anodes. In the case of the LMR-NMC cathode, the anode is either graphite or a graphite-silicon blend. Lithium metal is also an emerging anode material. This report documents the material and energy flows of producing each of these cathode and anode materials from raw material extraction through the preparation stage. For some cathode materials, we considered solid state and hydrothermal preparation methods. Further, we used Argonne National Laboratory’s Battery Performance and Cost (BatPaC) model to determine battery composition (e.g., masses of cathode, anode, electrolyte, housing materials) when different cathode materials were used in the battery. Our analysis concluded that cobalt- and nickel-containing compounds are the most energy intensive to produce.

  1. 1-Nitronapthalene as a cathode material for magnesium reserve batteries

    NASA Astrophysics Data System (ADS)

    Thirunakaran, R.; Vasudevan, S.; Sivashanmugam, A.; Kumar, Gopu; Muniyandi, N.

    1-Nitronaphthalene has been investigated for use as a battery depolarizer in conjunction with a high-energt magnesium anode. Acetylene black is added to improve the conductivity of the non-conducting organic compound and its concentration in the mix is optimized for better performance of the cathode. To assess its suitability and its characteristics as a cathode active material, magnesium/1-nitronaphthalene cells are fabricated and discharged in different electrolytes (magnesium chloride, magnesium bromide and magnesium perchlorate) at various current densities. The capacity delivered by the cell system shows better reduction efficiency of the 1-nitronaphthalene depolarizer. Cyclic voltammetric studies are carried out on a glassy-carbon electrode to understand the reduction behaviour of 1-nitronaphthalene.

  2. First principle computational and experimental studies of cathode materials for lithium ion rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Saavedra Arias, Jose Javier

    We have studied the properties of spinel and layered cathode materials for Li ion rechargeable batteries. The analysis was done by first principle calculations, and experimental techniques to elucidate materials that can substitute the presently commercialized material, namely LiCoO 2. We have studied the influence of Ni substitution for Mn in spinel Li 2MnO4. To understand the effects of this substitution on the crystal structure and electronic properties, first principle DFT calculations were performed using VASP. The substitution was done systematically for up to 25% of Mn replacement by Ni in a super cell configuration. Furthermore, the influence of Ni substitution on lithium hoping pathways between the two stable Li positions was also studied by first principle calculations in LiMn 2-xNixO4. These calculations revealed that Ni substitution for Mn in LiMn2O4 indeed improved Li ion mobility. Thereafter, systematic experimental studies were performed on LiMn 2-xNixO4 (0materials were synthesized by solution route and their structural characterization was done using X-ray diffraction (XRD) and Raman spectroscopy. The electrochemical performance of LiMn2-xNi xO4 materials was evaluated in two electrode CR2032 type coin cell configuration with Li metal as anode and liquid electrolyte (1 M LiPF6 in EC:DMC=1:1 v/v). Our results showed significant enhancement in the electrochemical properties with 25% of Ni substitution in LiMn 2O4, which is in good agreement with the theoretical calculations. We also studied layered cathode materials both theoretically and experimentally. The First principle calculations in conjunction with alloy metal method were used to evaluate the average voltage and phase stability of LiMO2 (M=Co, Ni, Mn, W) systems. By formation energy analysis we established that LiNi0.8Co0.1Mn0.1O2 is a promising candidate cathode material. Single

  3. Probing the initiation of voltage decay in Li-rich layered cathode materials at the atomic scale

    SciTech Connect

    Wu, Yan; Ma, Cheng; Yang, Jihui; Li, Zicheng; Allard, Jr., Lawrence Frederick; Liang, Chengdu; Chi, Miaofang

    2015-01-01

    Li-rich layered oxides hold great promise for improving the energy density of present-day Li-ion batteries. However, their application is limited by the voltage decay upon cycling, and the origin of such a phenomenon is poorly understood. A major issue is determining the voltage range over which detrimental reactions originate. In the present study, a unique yet effective approach was employed to probe this issue. Instead of studying the materials during the first cycle, electrochemical behavior and evolution of the atomic structures were compared in extensively cycled specimens under varied charge/discharge voltages. With the upper cutoff voltage lowered from 4.8 to 4.4 V, the voltage decay ceased to occur even after 60 cycles. In the meantime, the material maintained its layered structure without any spinel phase emerging at the surface, which is unambiguously shown by the atomic-resolution Z-contrast imaging and electron energy loss spectroscopy. These results have conclusively demonstrated that structural/chemical changes responsible for the voltage decay began between 4.4 and 4.8 V, where the layered-to-spinel transition was the most dramatic structural change observed. Thus, this discovery lays important groundwork for the mechanistic understanding of the voltage decay in Li-rich layered cathode materials.

  4. Probing the initiation of voltage decay in Li-rich layered cathode materials at the atomic scale

    DOE PAGESBeta

    Wu, Yan; Ma, Cheng; Yang, Jihui; Li, Zicheng; Allard, Jr., Lawrence Frederick; Liang, Chengdu; Chi, Miaofang

    2015-01-01

    Li-rich layered oxides hold great promise for improving the energy density of present-day Li-ion batteries. However, their application is limited by the voltage decay upon cycling, and the origin of such a phenomenon is poorly understood. A major issue is determining the voltage range over which detrimental reactions originate. In the present study, a unique yet effective approach was employed to probe this issue. Instead of studying the materials during the first cycle, electrochemical behavior and evolution of the atomic structures were compared in extensively cycled specimens under varied charge/discharge voltages. With the upper cutoff voltage lowered from 4.8 tomore » 4.4 V, the voltage decay ceased to occur even after 60 cycles. In the meantime, the material maintained its layered structure without any spinel phase emerging at the surface, which is unambiguously shown by the atomic-resolution Z-contrast imaging and electron energy loss spectroscopy. These results have conclusively demonstrated that structural/chemical changes responsible for the voltage decay began between 4.4 and 4.8 V, where the layered-to-spinel transition was the most dramatic structural change observed. Thus, this discovery lays important groundwork for the mechanistic understanding of the voltage decay in Li-rich layered cathode materials.« less

  5. High voltage spinel oxides for Li-ion batteries: From the material research to the application

    NASA Astrophysics Data System (ADS)

    Patoux, Sébastien; Daniel, Lise; Bourbon, Carole; Lignier, Hélène; Pagano, Carole; Le Cras, Frédéric; Jouanneau, Séverine; Martinet, Sébastien

    Li-ion batteries are already used in many nomad applications, but improvement of this technology is still necessary to be durably introduced on new markets such as electric vehicles (EVs), hybrid electric vehicles (HEVs) or eventually photovoltaic solar cells. Modification of the nature of the active materials of electrodes is the most challenging and innovative aspect. High voltage spinel oxides for Li-ion batteries, with general composition LiMn 2- xM xO 4 (M a transition metal element), may be used to face increasing power source demand. It should be possible to obtain up to 240 Wh kg -1 at cell level when combining a nickel manganese spinel oxide with graphite (even more with silicon/carbon nanocomposites at the anode). Specific composition and material processing have to be selected with care, as discussed in this paper. It is demonstrated that 'LiNi 0.5Mn 1.5O 4' and LiNi 0.4Mn 1.6O 4 have remarkable properties such as high potential, high energy density, good cycle life and high rate capability. Choice of the electrolyte is also of primary importance in order to prevent its degradation at high voltage in contact with active surfaces. We showed that a few percents of additive in the electrolyte were suitable for protecting the positive electrode/electrolyte interface, and reducing the self-discharge. High voltage materials are also possibly interesting to be used in safe and high power Li-ion cells. In this case, the negative electrode may be made of Li 4Ti 5O 12 or TiO 2 to give a '3 V' system.

  6. Apparatus and method for treating a cathode material provided on a thin-film substrate

    DOEpatents

    Hanson, Eric J.; Kooyer, Richard L.

    2001-01-01

    An apparatus and method for treating a cathode material provided on a surface of a continuous thin-film substrate and a treated thin-film cathode having increased smoothness are disclosed. A web of untreated cathode material is moved between a feed mechanism and a take-up mechanism, and passed through a treatment station. The web of cathode material typically includes areas having surface defects, such as prominences extending from the surface of the cathode material. The surface of the cathode material is treated with an abrasive material to reduce the height of the prominences so as to increase an 85 degree gloss value of the cathode material surface by at least approximately 10. The web of cathode material may be subjected to a subsequent abrasive treatment at the same or other treatment station. Burnishing or lapping film is employed at a treatment station to process the cathode material. An abrasive roller may alternatively be used to process the web of cathode material. The apparatus and method of the present invention may also be employed to treat the surface of a lithium anode foil so as to cleanse and reduce the roughness of the anode foil surface.

  7. Apparatus and method for treating a cathode material provided on a thin-film substrate

    DOEpatents

    Hanson, Eric J.; Kooyer, Richard L.

    2003-01-01

    An apparatus and method for treating a cathode material provided on a surface of a continuous thin-film substrate and a treated thin-film cathode having increased smoothness are disclosed. A web of untreated cathode material is moved between a feed mechanism and a take-up mechanism, and passed through a treatment station. The web of cathode material typically includes areas having surface defects, such as prominences extending from the surface of the cathode material. The surface of the cathode material is treated with an abrasive material to reduce the height of the prominences so as to increase an 85 degree gloss value of the cathode material surface by at least approximately 10. The web of cathode material may be subjected to a subsequent abrasive treatment at the same or other treatment station. Burnishing or lapping film is employed at a treatment station to process the cathode material. An abrasive roller may alternatively be used to process the web of cathode material. The apparatus and method of the present invention may also be employed to treat the surface of a lithium anode foil so as to cleanse and reduce the roughness of the anode foil surface.

  8. Understanding Voltage Decay in Lithium-Rich Manganese-Based Layered Cathode Materials by Limiting Cutoff Voltage.

    PubMed

    Yang, Jingsong; Xiao, Lifen; He, Wei; Fan, Jiangwei; Chen, Zhongxue; Ai, Xinping; Yang, Hanxi; Cao, Yuliang

    2016-07-27

    The effect of the cutoff voltages on the working voltage decay and cyclability of the lithium-rich manganese-based layered cathode (LRMO) was investigated by electrochemical measurements, electrochemical impedance spectroscopy, ex situ X-ray diffraction, transmission electron microscopy, and energy dispersive spectroscopy line scan technologies. It was found that both lower (2.0 V) and upper (4.8 V) cutoff voltages cause severe voltage decay with cycling due to formation of the spinel phase and migration of the transition metals inside the particles. Appropriate cutoff voltage between 2.8 and 4.4 V can effectively inhibit structural variation as the electrode demonstrates 92% capacity retention and indiscernible working voltage decay over 430 cycles. The results also show that phase transformation not only on high charge voltage but also on low discharge voltage should be addressed to obtain highly stable LRMO materials. PMID:27383918

  9. Renewable Cathode Materials from Biopolymer/Conjugated Polymer Interpenetrating Networks

    NASA Astrophysics Data System (ADS)

    Milczarek, Grzegorz; Inganäs, Olle

    2012-03-01

    Renewable and cheap materials in electrodes could meet the need for low-cost, intermittent electrical energy storage in a renewable energy system if sufficient charge density is obtained. Brown liquor, the waste product from paper processing, contains lignin derivatives. Polymer cathodes can be prepared by electrochemical oxidation of pyrrole to polypyrrole in solutions of lignin derivatives. The quinone group in lignin is used for electron and proton storage and exchange during redox cycling, thus combining charge storage in lignin and polypyrrole in an interpenetrating polypyrrole/lignin composite.

  10. Copper oxide as a high temperature battery cathode material

    NASA Astrophysics Data System (ADS)

    Ritchie, A. G.; Mullins, A. P.

    1994-10-01

    Copper oxide has been tested as a cathode material for high temperature primary reserve thermal batteries in single cells at 530 to 600 C and at current densities of 0.1 to 0.25 A cm(exp -2) using lithium-aluminium alloy anodes and lithium fluoride-lithium chloride-lithium bromide molten salt electrolytes. Initial on-load voltages were around 2.3 V, falling to 1.5 V after about 0.5 F mol(exp -1) had been withdrawn. Lithium copper oxide, LiCu2O2, and cuprous oxide, Cu2O, were identified as discharge products.

  11. Advanced hybrid battery with a magnesium metal anode and a spinel LiMn2O4 cathode.

    PubMed

    Pan, Baofei; Feng, Zhenxing; Sa, Niya; Han, Sang-Don; Ma, Qing; Fenter, Paul; Vaughey, John T; Zhang, Zhengcheng; Liao, Chen

    2016-08-01

    Two Mg-Li dual salt hybrid electrolytes are developed, which exhibit excellent oxidative stability up to around 3.8 V (vs. Mg/Mg(2+)) on an aluminum current collector, enabling the successful coupling of several state-of-the-art lithium-ion intercalation cathodes (LiMn2O4, LiCoO2 and LiNi1/3Mn1/3Co1/3O2) with magnesium metal anodes. The Mg-LiMn2O4 battery delivers an initial discharge capacity of about 106 mA h g(-1) with a working voltage of around 2.8 V (vs. Mg/Mg(2+)), highlighting the highest working voltage of rechargeable batteries with magnesium metal anodes to date. PMID:27439946

  12. Discharge characteristics of lithium/molten nitrate thermal battery cells using silver salts as solid cathode materials

    NASA Astrophysics Data System (ADS)

    McManis, G. E.; Miles, M. H.; Fletcher, A. N.

    1985-12-01

    Thermal battery cells using molten nitrate electrolytes and liquid lithium anodes have been evaluated using several silver salts with low solubility in molten nitrates as solid cathode materials. These cathode materials do not readily diffuse into the anolyte and, thus, do not have parasitic reactions with the lithium anode. Furthermore, the solid cathode materials have voltammetric characteristics as favorable as many soluble silver salt cathodes. This paper presents the effects of temperature, current density, and cathode material on cell discharge characteristics.

  13. Reaction mechanism and thermal stability study on cathode materials for rechargeable lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Fang, Jin

    Olivine-type lithium iron phosphate has been a very promising cathode material since it was proposed by Padhi in 1997, low-cost, environmental friendly and stable structure ensure the commercialization of LiFePO 4. In LiFePO4, during charge and discharge process, Li ions are transferred between two phases, Li-poor LialphaFePO 4 and Li-rich Li1-betaFePO4, which implies a significant energy barrier for the new phase nucleation and interface growth, contrary to the fast reaction kinetics experimentally observed. The understanding of the lithiation and delithiation mechanism of this material has spurred a lot of research interests. Many theory models have been proposed to explain the reaction mechanism of LiFePO4, among them, the single phase model claims that the reaction goes through a metastable single phase, and the over potential required to form this single phase is about 30mV, so we studied the driving force to transport lithium ions between Lialpha FePO4 and Li1-betaFePO4 phases and compared the particle sizes effect. Experiment results shows that, the nano-sized (30nm) LiFePO4 has wider solid solution range, lower solid solution formation temperature and faster kinetics than normal LiFePO4 (150nm). Also a 20mV over potential was observed in both samples, either after relaxing the FePO4/LiFePO4 system to equilibrium or transport lithium from one side to the other side, the experiment result is corresponding to theoretical calculation; indicates the reaction might go through single-phase reaction mechanism. The energy and power density of lithium ion battery largely depend on cathode materials. Mn substituted LiFePO4 has a higher voltage than LiFePO4, which results a higher theoretical energy density. Safety issue is one of the most important criterions for batteries, since cathode materials need to maintain stable structure during hundreds of charge and discharge cycles and ranges of application conditions. We have reported that iron-rich compound o-Fe1-yMnyPO4

  14. Alternate anode materials for cathodic protection of steel reinforced concrete

    SciTech Connect

    Russell, James H.; Bullard, Sophie J.; Covino, Bernard S., Jr.; Cramer, Stephen D.; Holcomb, Gordon R.; Cryer, Curtis B.

    2001-01-01

    Consumable and non-consumable anodes were evaluated in the laboratory for use in cathodic protection (CP) systems for steel reinforced concrete bridges in coastal environments and in areas where deicing salts are employed. The anode materials included Zn-hydrogel and thermal-sprayed Zn, Zn-15Al, Al-12Zn-0.2In, and cobalt-sprayed Ti. These anodes were evaluated for service in both galvanic (GCP) and impressed current (ICCP) cathodic protection systems. Impressed current CP anodes were electrochemically aged at a current density 15 times as great as that used by the Oregon Department of Transportation in typical coastal ICCP systems (2.2 mA/m2 based on anode area). Increasing moisture at the anode-concrete interface reduced the operating voltage of all the anodes. Bond strength between the anodes and concrete decreased with electrochemical aging. The Zn-15Al and Al-12Zn-0.2In anodes provided adequate protection in GCP but their life was too short in the accelerated ICCP tests. Zinc had an adequate life in ICCP tests but was inadequate as a galvanic anode. Zinc-hydrogel performed well in both tests when the hydrogel was kept moist. Titanium was an excellent anode for ICCP, but is not suitable for GCP.

  15. New Cathode Materials for Intermediate Temperature Solid Oxide Fuel Cells

    SciTech Connect

    Allan J. Jacobson

    2006-09-30

    Operation of SOFCs at intermediate temperatures (500-800 C) requires new combinations of electrolyte and electrode materials that will provide both rapid ion transport across the electrolyte and electrode-electrolyte interfaces and efficient electrocatalysis of the oxygen reduction and fuel oxidation reactions. This project concentrates on materials and issues associated with cathode performance that are known to become limiting factors as the operating temperature is reduced. The specific objectives of the proposed research are to develop cathode materials that meet the electrode performance targets of 1.0 W/cm{sup 2} at 0.7 V in combination with YSZ at 700 C and with GDC, LSGM or bismuth oxide based electrolytes at 600 C. The performance targets imply an area specific resistance of {approx}0.5 {Omega}cm{sup 2} for the total cell. The research strategy is to investigate both established classes of materials and new candidates as cathodes, to determine fundamental performance parameters such as bulk diffusion, surface reactivity and interfacial transfer, and to couple these parameters to performance in single cell tests. The initial choices for study were perovskite oxides based on substituted LaFeO{sub 3} (P1 compositions), where significant data in single cell tests exist at PNNL for example, for La{sub 0.8}Sr{sub 0.2}FeO{sub 3} cathodes on both YSZ and CSO/YSZ. The materials selection was then extended to La{sub 2}NiO{sub 4} compositions (K1 compositions), and then in a longer range task we evaluated the possibility of completely unexplored group of materials that are also perovskite related, the ABM{sub 2}O{sub 5+{delta}}. A key component of the research strategy was to evaluate for each cathode material composition, the key performance parameters, including ionic and electronic conductivity, surface exchange rates, stability with respect to the specific electrolyte choice, and thermal expansion coefficients. In the initial phase, we did this in parallel with

  16. Performance and stability of different cathode base materials for use in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Janicek, Anthony; Fan, Yanzhen; Liu, Hong

    2015-04-01

    Metal supporting materials are increasingly being used as base materials for microbial fuel cell (MFC) cathodes. However, the potential for corrosion may limit their use as base materials of MFCs during scale-up and long-term operation. In this study, the electrochemical performance, power generation in MFCs, hydrostatic pressure tolerance, and stability of activated carbon (catalyst) cathodes with carbon cloth or different size metal mesh as base materials are investigated. Electrochemical testing results show that the finest stainless steel mesh (250 × 250 openings per inch) outperforms carbon cloth cathodes by 10-40% at current densities ranging from 6 to 11.2 A m-2 over the typical cathode operating range of 0.1 V-0 V. When tested in MFCs, however, carbon cloth based cathodes out perform all stainless steel mesh cathodes by as much as 34%, reaching 1.72 W m-2; probably due to the corrosion and salt build-up on the surface of the stainless steel mesh cathodes. Carbon cloth cathodes also maintained high static pressure heads of 1.9 m. The high electrochemical performance, hydrostatic pressure tolerance, and corrosion resistance of carbon cloth suggest that carbon fiber based materials may be more suitable than metal based materials for use as MFC cathodes base material for some applications.

  17. Nickel hydroxide and other nanophase cathode materials for rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Reisner, David E.; Salkind, Alvin J.; Strutt, Peter R.; Xiao, T. Danny

    The staff of US Nanocorp, Inc. are developing unique nanostructured materials for a wide range of applications in the areas of energy storage (batteries and ultracapacitors) and energy conversion (fuel cells and thermoelectric) devices. Many of the preparations of these materials exploit a wet synthesis process (patent pending) that is scaleable to large volume manufacturing and anticipated to be low in cost. Specifically, both the β-form of nickel hydroxide and the hollandite form of manganese dioxide have been synthesized. The hexagonal Ni(OH) 2 is anticipated to significantly boost energy densities in nickel-alkaline batteries, including nickel/cadmium, nickel/metal hydride and nickel/zinc. The nanophase MnO 2 microstructure exhibits an unusual tunnelled tubular geometry within a 'bird's nest' superstructure, and is expected to be of interest as an intercalation cathode material in lithium-ion systems as well as a catalyst for fuel cells. Characterization of these materials has been by the techniques of high resolution SEM and TEM, as well as XRD. Both Hg porosimetry and BET surface measurements for conventional and spherical nickel hydroxides are summarized. Pore distribution and electrochemical activity for the nanophase materials will be examined in the future.

  18. Nanostructured material for advanced energy storage : magnesium battery cathode development.

    SciTech Connect

    Sigmund, Wolfgang M.; Woan, Karran V.; Bell, Nelson Simmons

    2010-11-01

    Magnesium batteries are alternatives to the use of lithium ion and nickel metal hydride secondary batteries due to magnesium's abundance, safety of operation, and lower toxicity of disposal. The divalency of the magnesium ion and its chemistry poses some difficulties for its general and industrial use. This work developed a continuous and fibrous nanoscale network of the cathode material through the use of electrospinning with the goal of enhancing performance and reactivity of the battery. The system was characterized and preliminary tests were performed on the constructed battery cells. We were successful in building and testing a series of electrochemical systems that demonstrated good cyclability maintaining 60-70% of discharge capacity after more than 50 charge-discharge cycles.

  19. Cobalt Hexacyanoferrate as Cathode Material for Na+ Secondary Battery

    NASA Astrophysics Data System (ADS)

    Takachi, Masamitsu; Matsuda, Tomoyuki; Moritomo, Yutaka

    2013-02-01

    We investigated structural and electrochemical properties of thin film electrodes of cobalt hexacyanoferrate, NaxCo[Fe(CN)6]0.902.9H2O, against x. The compound exhibits a high capacity of 135 mAh/g and an average operating voltage of 3.6 V against Na, with a good cyclability. The discharge curve exhibits two plateaus at ≈3.8 and ≈3.4 V, which are ascribed to the reduction processes of Fe3+ and Co3+, respectively. The ex situ X-ray diffraction (XRD) profiles reveal the robust nature of the host framework against Na+ intercalation/deintercalation. Thus, cobalt hexacyanoferrate is a promising candidate for the cathode material of sodium-ion secondary battery (SIB).

  20. Mercury vapor hollow cathode component studies. [emissive materials for ion thruster requirements

    NASA Technical Reports Server (NTRS)

    Zuccaro, D. E.

    1973-01-01

    An experimental study of starting and operating characteristics of conventional hollow cathodes and of hollow cathodes without alkaline earth emissive materials demonstrated that the emissive mix is essential to obtain the desired cathode operation. Loss of the emissive mix by evaporation and chemical reaction was measured. New insert designs consisting of emissive mix supported on nickel and of barium impregnated porous tungsten were studied. Cathodes with a modified orifice geometry operated in a low voltage, 'spot' mode over a broad range of discharge current. Thermal degradation tests on cathode heaters showed the flame sprayed SERT II type to be the most durable at high temperatures. Thermal shock was observed to be a significant factor in limiting cathode heater life. A cathode having a barium impregnated porous tungsten tip and a heater which is potted in sintered alumina was found to have favorable operating characteristics.

  1. Hydrogen Induced Stress Cracking of Materials Under Cathodic Protection

    NASA Astrophysics Data System (ADS)

    LaCoursiere, Marissa P.

    Hydrogen embrittlement of AISI 4340, InconelRTM 718, Alloy 686 and Alloy 59 was studied using slow strain rate tests of both smooth and notched cylindrical specimens. Two heat treatments of the AISI 4340 material were used as a standard for two levels of yield strength: 1479 MPa, and 1140 MPa. A subset of the 1140 MPa AISI 4340 material also underwent plasma nitriding. The InconelRTM 718 material was hardened following AMS 5663M to obtain a yield strength of 1091 MPa. The Alloy 686 material was obtained in the Grade 3 condition with a minimum yield strength of 1034 MPa. The Alloy 59 material was obtained with a cold worked condition similar to the Alloy 686 and with a minimum yield strength of 1034 MPa. Ninety-nine specimens were tested, including smooth cylindrical tensile test specimens and smooth and notched cylindrical slow strain rate tensile tests specimens. Testing included specimens that had been precharged with hydrogen in 3.5% NaCl at 50°C for 2 weeks (AISI 4340), 4 weeks (InconelRTM 718, Alloy 686, Alloy 59) and 16 weeks (InconelRTM 718, Alloy 686, Alloy 59) using a potentiostat to deliver a cathodic potential of -1100 mV vs. SCE. The strain rate over the gauge section for the smooth specimens and in the notch root for the notched specimens was 1 x 10-6 /s. It was found that the AISI 4340 was highly embrittled in simulated ocean water when compared to the nickel based superalloys. The higher strength AISI 4340 showed much more embrittlement, as expected. Testing of the AISI 4340 at both 20°C and 4°C showed that the temperature had no effect on the hydrogen embrittlement response. The InconelRTM 718 was highly embrittled when precharged, although it only showed low levels of embrittlement when unprecharged. Both the Alloy 686 and Alloy 59 showed minimal embrittlement in all conditions. Therefore, for the materials examined, the use of Alloy 686 and Alloy 59 for components in salt water environments when under a cathodic potential of -1100 mV vs. SCE is

  2. Rapid synthesis of monodispersed highly porous spinel nickel cobaltite (NiCo2O4) electrode material for supercapacitors

    NASA Astrophysics Data System (ADS)

    Naveen, A. Nirmalesh; Selladurai, S.

    2015-06-01

    Monodispersed highly porous spinel nickel cobaltite electrode material was successfully synthesized in a short time using combustion technique. Single phase cubic nature of the spinel nickel cobaltite with average crystallite size of 24 nm was determined from X-ray diffraction study. Functional groups present in the compound were determined from FTIR study and it further confirms the spinel formation. FESEM images reveal the porous nature of the prepared material and uniform size distribution of the particles. Electrochemical evaluation was performed using Cyclic Voltammetry (CV) technique, Chronopotentiometry (CP) and Electrochemical Impedance Spectroscopy (EIS). Results reveal the typical pseudocapacitive behaviour of the material. Maximum capacitance of 754 F/g was calculated at the scan rate of 5 mV/s, high capacitance was due to the unique porous morphology of the electrode. Nyquist plot depicts the low resistance and good electrical conductivity of nickel cobaltite. It has been found that nickel cobaltite prepared by this typical method will be a potential electrode material for supercapcitor application.

  3. Modified nickel oxides as cathode materials for MCFC

    NASA Astrophysics Data System (ADS)

    Daza, L.; Rangel, C. M.; Baranda, J.; Casais, M. T.; Martínez, M. J.; Alonso, J. A.

    The preparation and subsequent oxidation of nickel cathodes modified by impregnation with cerium were evaluated by surface and bulk analysis. The cerium impregnated cathodes showed the same pore size distribution curve types and the same morphology as the reference nickel cathode. The measured nickel oxide dissolution rate in the molten carbonate mixture indicated that a minimum corrosion was evident for cathodes with 0.3-1 wt.% cerium oxide content. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed in the cathode characterization. As can be seen by SEM, the corrosion treatments produce marked modifications on the sample surfaces that appear more prominent for the cerium-free sample. The results also show that the lithiation process is a very significant factor that can improve the efficiency of the cell, but needs to be controlled because it can also produce very damaging effects such as the modification of the cathode volume by the formation on new compounds.

  4. Synthesis and electrochemical characterizations of nano-La{sub 2}O{sub 3}-coated nanostructure LiMn{sub 2}O{sub 4} cathode materials for rechargeable lithium batteries

    SciTech Connect

    Arumugam, D.; Paruthimal Kalaignan, G.

    2010-12-15

    LiMn{sub 2}O{sub 4} spinel cathode materials were coated with 1.0, 2.0 and 3.0 wt.% of La{sub 2}O{sub 3} by polymeric process, followed by calcinations at 850 {sup o}C for 6 h in air. The surface coated LiMn{sub 2}O{sub 4} cathode materials were physically characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and XPS. XRD patterns of La{sub 2}O{sub 3}-coated LiMn{sub 2}O{sub 4} revealed that the coating did not affect the crystal structure and space group Fd3m of the cathode materials, compared to the uncoated LiMn{sub 2}O{sub 4}. The surface morphology and particle agglomeration were investigated using scanning electron microscopy and the TEM image showed a compact coating layer on the surface of the core materials that had average thickness of about 100 nm. XPS data illustrated that the La{sub 2}O{sub 3} was completely coated over the surface of the LiMn{sub 2}O{sub 4} core cathode materials. The galvanostatic charge and discharge of the uncoated and La{sub 2}O{sub 3}-coated LiMn{sub 2}O{sub 4} cathode materials were carried out in the potential range of 3.0 and 4.5 V at 30 {sup o}C and 60 {sup o}C. Among them, 2.0 wt.% of La{sub 2}O{sub 3}-coated spinel LiMn{sub 2}O{sub 4} cathode has improved the structural stability, high reversible capacity and excellent electrochemical performances of the rechargeable lithium batteries.

  5. The influence of cathode material on electrochemical degradation of trichloroethylene in aqueous solution.

    PubMed

    Rajic, Ljiljana; Fallahpour, Noushin; Podlaha, Elizabeth; Alshawabkeh, Akram

    2016-03-01

    In this study, different cathode materials were evaluated for electrochemical degradation of aqueous phase trichloroethylene (TCE). A cathode followed by an anode electrode sequence was used to support reduction of TCE at the cathode via hydrodechlorination (HDC). The performance of iron (Fe), copper (Cu), nickel (Ni), aluminum (Al) and carbon (C) foam cathodes was evaluated. We tested commercially available foam materials, which provide large electrode surface area and important properties for field application of the technology. Ni foam cathode produced the highest TCE removal (68.4%) due to its high electrocatalytic activity for hydrogen generation and promotion of HDC. Different performances of the cathode materials originate from differences in the bond strength between atomic hydrogen and the material. With a higher electrocatalytic activity than Ni, Pd catalyst (used as cathode coating) increased TCE removal from 43.5% to 99.8% for Fe, from 56.2% to 79.6% for Cu, from 68.4% to 78.4% for Ni, from 42.0% to 63.6% for Al and from 64.9% to 86.2% for C cathode. The performance of the palladized Fe foam cathode was tested for degradation of TCE in the presence of nitrates, as another commonly found groundwater species. TCE removal decreased from 99% to 41.2% in presence of 100 mg L(-1) of nitrates due to the competition with TCE for HDC at the cathode. The results indicate that the cathode material affects TCE removal rate while the Pd catalyst significantly enhances cathode activity to degrade TCE via HDC. PMID:26761603

  6. Synthesis, Characterization and Electrochemical Analysis of Composite Cathode Material 0.5Li2MnO3-0.25LiMn2O4-0.25LiNi0.5Mn0.5O2 for LIB applications

    NASA Astrophysics Data System (ADS)

    Lopez de Victoria, Monica; Shojan, Jifi; Torres, Loraine; Katiyar, Rajesh; Dorvilien, Valerio; Katiyar, Ram

    Structural stability, environment friendliness, low cost as well as good electrochemical performances are the major requirements for cathode materials. Li2MnO3 based composite cathode materials are one of the widely investigated positive cathode materials due to their ability to provide high discharge capacity and good rate capability. We have synthesized layered- spinel composite cathode material 0.5Li2MnO3-0.25LiMn2O4 -0.25LiNi0.5Mn0.5O2 by sol-gel synthesis technique and surface characterized using XRD, Raman, SEM and EDX. Peaks corresponding to layered and spinel structures are identified by XRD and Raman studies. SEM images depict the nano-sized particles and EDX data confirms the presence of constituent transition metals and oxygen. Electrochemical studies were performed on coin cells, which were assembled in the Ar- filled glove box using Li as anode and spread material as cathode. LiPF6 with EC:DMC::1:2 ratio was used as the electrolyte. CV, EIS and charge discharge studies shows that the developed cathode material is a promising electrode for next generation Li ion batteries. Nasa Epscore Grant.

  7. Mitigating Voltage Decay of Li-Rich Cathode Material via Increasing Ni Content for Lithium-Ion Batteries.

    PubMed

    Shi, Ji-Lei; Zhang, Jie-Nan; He, Min; Zhang, Xu-Dong; Yin, Ya-Xia; Li, Hong; Guo, Yu-Guo; Gu, Lin; Wan, Li-Jun

    2016-08-10

    Li-rich layered materials have been considered as the most promising cathode materials for future high-energy-density lithium-ion batteries. However, they suffer from severe voltage decay upon cycling, which hinders their further commercialization. Here, we report a Li-rich layered material 0.5Li2MnO3·0.5LiNi0.8Co0.1Mn0.1O2 with high nickel content, which exhibits much slower voltage decay during long-term cycling compared to conventional Li-rich materials. The voltage decay after 200 cycles is 201 mV. Combining in situ X-ray diffraction (XRD), ex situ XRD, ex situ X-ray photoelectron spectroscopy, and scanning transmission electron microscopy, we demonstrate that nickel ions act as stabilizing ions to inhibit the Jahn-Teller effect of active Mn(3+) ions, improving d-p hybridization and supporting the layered structure as a pillar. In addition, nickel ions can migrate between the transition-metal layer and the interlayer, thus avoiding the formation of spinel-like structures and consequently mitigating the voltage decay. Our results provide a simple and effective avenue for developing Li-rich layered materials with mitigated voltage decay and a long lifespan, thereby promoting their further application in lithium-ion batteries with high energy density. PMID:27437556

  8. Impact of active material surface area on thermal stability of LiCoO2 cathode

    NASA Astrophysics Data System (ADS)

    Geder, Jan; Hoster, Harry E.; Jossen, Andreas; Garche, Jürgen; Yu, Denis Y. W.

    2014-07-01

    Thermal stability of charged LiCoO2 cathodes with various surface areas of active material is investigated in order to quantify the effect of LiCoO2 surface area on thermal stability of cathode. Thermogravimetric analyses and calorimetry have been conducted on charged cathodes with different active material surface areas. Besides reduced thermal stability, high surface area also changes the active material decomposition reaction and induces side reactions with additives. Thermal analyses of LiCoO2 delithiated chemically without any additives or with a single additive have been conducted to elaborate the effect of particle size on side reactions. Stability of cathode-electrolyte system has been investigated by accelerating rate calorimetry (ARC). Arrhenius activation energy of cathode decomposition has been calculated as function of conversion at different surface area of active material.

  9. Organotrisulfide: A High Capacity Cathode Material for Rechargeable Lithium Batteries.

    PubMed

    Wu, Min; Cui, Yi; Bhargav, Amruth; Losovyj, Yaroslav; Siegel, Amanda; Agarwal, Mangilal; Ma, Ying; Fu, Yongzhu

    2016-08-16

    An organotrisulfide (RSSSR, R is an organic group) has three sulfur atoms which could be involved in multi-electron reduction reactions; therefore it is a promising electrode material for batteries. Herein, we use dimethyl trisulfide (DMTS) as a model compound to study its redox reactions in rechargeable lithium batteries. With the aid of XRD, XPS, and GC-MS analysis, we confirm DMTS could undergo almost a 4 e(-) reduction process in a complete discharge to 1.0 V. The discharge products are primarily LiSCH3 and Li2 S. The lithium cell with DMTS catholyte delivers an initial specific capacity of 720 mAh g(-1) DMTS and retains 82 % of the capacity over 50 cycles at C/10 rate. When the electrolyte/DMTS ratio is 3:1 mL g(-1) , the reversible specific energy for the cell including electrolyte can be 229 Wh kg(-1) . This study shows organotrisulfide is a promising high-capacity cathode material for high-energy rechargeable lithium batteries. PMID:27411083

  10. Structural predictions based on the compositions of cathodic materials by first-principles calculations

    NASA Astrophysics Data System (ADS)

    Li, Yang; Lian, Fang; Chen, Ning; Hao, Zhen-jia; Chou, Kuo-chih

    2015-05-01

    A first-principles method is applied to comparatively study the stability of lithium metal oxides with layered or spinel structures to predict the most energetically favorable structure for different compositions. The binding and reaction energies of the real or virtual layered LiMO2 and spinel LiM2O4 (M = Sc-Cu, Y-Ag, Mg-Sr, and Al-In) are calculated. The effect of element M on the structural stability, especially in the case of multiple-cation compounds, is discussed herein. The calculation results indicate that the phase stability depends on both the binding and reaction energies. The oxidation state of element M also plays a role in determining the dominant structure, i.e., layered or spinel phase. Moreover, calculation-based theoretical predictions of the phase stability of the doped materials agree with the previously reported experimental data.

  11. Oxide Fiber Cathode Materials for Rechargeable Lithium Cells

    NASA Technical Reports Server (NTRS)

    Rice, Catherine E.; Welker, Mark F.

    2008-01-01

    LiCoO2 and LiNiO2 fibers have been investigated as alternatives to LiCoO2 and LiNiO2 powders used as lithium-intercalation compounds in cathodes of rechargeable lithium-ion electrochemical cells. In making such a cathode, LiCoO2 or LiNiO2 powder is mixed with a binder [e.g., poly(vinylidene fluoride)] and an electrically conductive additive (usually carbon) and the mixture is pressed to form a disk. The binder and conductive additive contribute weight and volume, reducing the specific energy and energy density, respectively. In contrast, LiCoO2 or LiNiO2 fibers can be pressed and sintered to form a cathode, without need for a binder or a conductive additive. The inter-grain contacts of the fibers are stronger and have fewer defects than do those of powder particles. These characteristics translate to increased flexibility and greater resilience on cycling and, consequently, to reduced loss of capacity from cycle to cycle. Moreover, in comparison with a powder-based cathode, a fiber-based cathode is expected to exhibit significantly greater ionic and electronic conduction along the axes of the fibers. Results of preliminary charge/discharge-cycling tests suggest that energy densities of LiCoO2- and LiNiO2-fiber cathodes are approximately double those of the corresponding powder-based cathodes.

  12. Study Of Erosion Rates And Surface Effects of Different Hollow Cathode Materials During Vacuum Microarc Discharge

    SciTech Connect

    Atta Khedr, M.; Abdel Moneim, H.M.

    2005-03-17

    Studies of the properties of the emitted plasma from graphite, titanium, titanium Carbide, Stainless Steel, Cupper and Molybdenum Hollow Cathode materials during vacuum microarc were carried out. Using high voltage of 30 KV, short arc duration (0.5 - 4 {mu}s) and arc currents (100 - 450 A), each cathode material was subjected to 1000-3000 arc discharges under high vacuum (10-8 mbar) conditions. The angular distributions for the evaporants in each case were measured and show an exponential isotropic distribution in agreement with the theoretical predictions. The total erosion rates of evaporants and molten droplets were estimated and showed clearly their, dependence on the cathode material and on the hollow cathode geometry. The damages on the cathode surfaces and the inside of the hollow cathodes were investigated by the scanning electron microscope. Crater formation were formed spreading inside the hole of the hollow cathodes as well as on the rim surfaces and were found to differ according to both geometry and material of the hollow cathodes. The crater evacuation velocity and plasma pressure were determined. The damage on the anode tip showed erosion on the pen anode tip to the extent of drilling hole. The mechanism responsible for such phenomena is discussed.

  13. Nanoporous selenium as a cathode material for rechargeable lithium-selenium batteries.

    PubMed

    Liu, Lili; Hou, Yuyang; Wu, Xiongwei; Xiao, Shiying; Chang, Zheng; Yang, Yaqiong; Wu, Yuping

    2013-12-21

    Nanoporous selenium was prepared by a simple mechanical method adopting nano-CaCO3 as a template. When used as a cathode, it can exhibit relatively high capacity and good cycling behaviour. These results present great promise for this new cathode material for rechargeable lithium batteries of high energy density. PMID:24175320

  14. Particle size effect of Ni-rich cathode materials on lithium ion battery performance

    SciTech Connect

    Hwang, Ilkyu; Department of Chemical Engineering, Kyungppok National University, Daegu 702-701 ; Lee, Chul Wee; Kim, Jae Chang; Yoon, Songhun

    2012-01-15

    Graphical abstract: The preparation condition of Ni-rich cathode materials was investigated. When the retention time was short, a poor cathode performance was observed. For long retention time condition, cathode performance displayed a best result at pH 12. Highlights: Black-Right-Pointing-Pointer Ni-rich cathode materials (LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2}) were prepared by co-precipitation method using separate addition of Al salt. Black-Right-Pointing-Pointer Particle size of Ni-rich cathode materials became larger with increase of retention time and solution pH. Black-Right-Pointing-Pointer Cathode performance was poor for low retention time. Black-Right-Pointing-Pointer Optimal pH for co-precipitation was 12. -- Abstract: Herein, Ni-rich cathode materials (LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2}) in lithium ion batteries are prepared by a separate addition of Ni/Co salt and Al sol solution using a continuously stirred tank reactor. Retention time and solution pH were controlled in order to obtain high performance cathode material. Particle size increase was observed with a higher retention time of the reactants. Also, primary and secondary particles became smaller according to an increase of solution pH, which was probably due to a decrease of growth rate. From the cathode application, a high discharge capacity (175 mAh g{sup -1}), a high initial efficiency (90%) and a good cycleability were observed in the cathode material prepared under pH 12 condition, which was attributed to its well-developed layered property and the optimal particle size. However, rate capability was inversely proportional to the particle size, which was clarified by a decrease of charge-transfer resistance measured in the electrochemical impedance spectroscopy.

  15. Graphene wrapped ordered LiNi0.5Mn1.5O4 nanorods as promising cathode material for lithium-ion batteries

    PubMed Central

    Tang, Xiao; Jan, S. Savut; Qian, Yanyan; Xia, Hui; Ni, Jiangfeng; Savilov, Serguei V.; Aldoshin, Serguei M.

    2015-01-01

    LiNi0.5Mn1.5O4 nanorods wrapped with graphene nanosheets have been prepared and investigated as high energy and high power cathode material for lithium-ion batteries. The structural characterization by X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy indicates the LiNi0.5Mn1.5O4 nanorods prepared from β-MnO2 nanowires have ordered spinel structure with P4332 space group. The morphological characterization by scanning electron microscopy and transmission electron microscopy reveals that the LiNi0.5Mn1.5O4 nanorods of 100–200 nm in diameter are well dispersed and wrapped in the graphene nanosheets for the composite. Benefiting from the highly conductive matrix provided by graphene nanosheets and one-dimensional nanostructure of the ordered spinel, the composite electrode exhibits superior rate capability and cycling stability. As a result, the LiNi0.5Mn1.5O4-graphene composite electrode delivers reversible capacities of 127.6 and 80.8 mAh g−1 at 0.1 and 10 C, respectively, and shows 94% capacity retention after 200 cycles at 1 C, greatly outperforming the bare LiNi0.5Mn1.5O4 nanorod cathode. The outstanding performance of the LiNi0.5Mn1.5O4-graphene composite makes it promising as cathode material for developing high energy and high power lithium-ion batteries. PMID:26148558

  16. Graphene wrapped ordered LiNi0.5Mn1.5O4 nanorods as promising cathode material for lithium-ion batteries.

    PubMed

    Tang, Xiao; Jan, S Savut; Qian, Yanyan; Xia, Hui; Ni, Jiangfeng; Savilov, Serguei V; Aldoshin, Serguei M

    2015-01-01

    LiNi0.5Mn1.5O4 nanorods wrapped with graphene nanosheets have been prepared and investigated as high energy and high power cathode material for lithium-ion batteries. The structural characterization by X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy indicates the LiNi0.5Mn1.5O4 nanorods prepared from β-MnO2 nanowires have ordered spinel structure with P4332 space group. The morphological characterization by scanning electron microscopy and transmission electron microscopy reveals that the LiNi0.5Mn1.5O4 nanorods of 100-200 nm in diameter are well dispersed and wrapped in the graphene nanosheets for the composite. Benefiting from the highly conductive matrix provided by graphene nanosheets and one-dimensional nanostructure of the ordered spinel, the composite electrode exhibits superior rate capability and cycling stability. As a result, the LiNi0.5Mn1.5O4-graphene composite electrode delivers reversible capacities of 127.6 and 80.8 mAh g(-1) at 0.1 and 10 C, respectively, and shows 94% capacity retention after 200 cycles at 1 C, greatly outperforming the bare LiNi0.5Mn1.5O4 nanorod cathode. The outstanding performance of the LiNi0.5Mn1.5O4-graphene composite makes it promising as cathode material for developing high energy and high power lithium-ion batteries. PMID:26148558

  17. High-Current Cold Cathode Employing Diamond and Related Materials

    SciTech Connect

    Hirshfield, Jay L.

    2014-10-22

    The essence of this project was for diamond films to be deposited on cold cathodes to improve their emission properties. Films with varying morphology, composition, and size of the crystals were deposited and the emission properties of the cathodes that utilize such films were studied. The prototype cathodes fabricated by the methods developed during Phase I were tested and evaluated in an actual high-power RF device during Phase II. These high-power tests used the novel active RF pulse compression system and the X-band magnicon test facility at US Naval Research Laboratory. In earlier tests, plasma switches were employed, while tests under this project utilized electron-beam switching. The intense electron beams required in the switches were supplied from cold cathodes embodying diamond films with varying morphology, including uncoated molybdenum cathodes in the preliminary tests. Tests with uncoated molybdenum cathodes produced compressed X-band RF pulses with a peak power of 91 MW, and a maximum power gain of 16.5:1. Tests were also carried out with switches employing diamond coated cathodes. The pulse compressor was based on use of switches employing electron beam triggering to effect mode conversion. In experimental tests, the compressor produced 165 MW in a ~ 20 ns pulse at ~18× power gain and ~ 140 MW at ~ 16× power gain in a 16 ns pulse with a ~ 7 ns flat-top. In these tests, molybdenum blade cathodes with thin diamond coatings demonstrated good reproducible emission uniformity with a 100 kV, 100 ns high voltage pulse. The new compressor does not have the limitations of earlier types of active pulse compressors and can operate at significantly higher electric fields without breakdown.

  18. The Impact of Cathode Material and Shape on Current Density in an Aluminum Electrolysis Cell

    NASA Astrophysics Data System (ADS)

    Song, Yang; Peng, Jianping; Di, Yuezhong; Wang, Yaowu; Li, Baokuan; Feng, Naixiang

    2016-02-01

    A finite element model was developed to determine the impact of cathode material and shape on current density in an aluminum electrolysis cell. For the cathode material, results show that increased electrical resistivity leads to a higher cathode voltage drop; however, the horizontal current is reduced in the metal. The horizontal current magnitude for six different cathode materials in decreasing order is graphitized, semi-graphitized, full graphitic, 50% anthracite (50% artificial graphite), 70% anthracite (30% artificial graphite), 100% anthracite. The modified cathode shapes with an inclined cathode surface, higher collector bar and cylindrical protrusions are intended to improve horizontal current and flow resistance. Compared to a traditional cathode, modified collector bar sizes of 70 mm × 230 mm and 80 mm × 270 mm can reduce horizontal current density component Jx by 10% and 19%, respectively, due to better conductivity of the steel. The horizontal current in the metal decreases with increase of cathode inclination. The peak value of Jx can be approximately reduced by 20% for a 2° change in inclination. Cylindrical protrusions lead to local horizontal current increase on their tops, but the average current is less affected and the molten metal is effectively slowed down.

  19. A review of blended cathode materials for use in Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Chikkannanavar, Satishkumar B.; Bernardi, Dawn M.; Liu, Lingyun

    2014-02-01

    Several commercial automotive battery suppliers have developed lithium ion cells which use cathodes that consist of a mixture of two different active materials. This approach is intended to take advantage of the unique properties of each material and optimize the performance of the battery with respect to the automotive operating requirements. Certain cathode materials have high coulombic capacity and good cycling characteristics, but are costly and exhibit poor thermal stability (e.g., LiNixCo1-x-yAlyO2). Alternately, other cathode materials exhibit good thermal stability, high voltage and high rate capability, but have low capacity (e.g., LiMn2O4). By blending two cathode materials the shortcomings of the parent materials could be minimized and the resultant blend can be tailored to have a higher energy or power density coupled with enhanced stability and lower cost. In this review, we survey the developing field of blended cathode materials from a new perspective. Targeting a range of cathode materials, we survey the advances in the field in the current review. Limitations, such as capacity decay due to metal dissolution are also discussed, as well as how the appropriate balance of characteristics of the blended materials can be optimized for hybrid- and electric-vehicle applications.

  20. Cobalt-manganese-based spinels as multifunctional materials that unify catalytic water oxidation and oxygen reduction reactions.

    PubMed

    Menezes, Prashanth W; Indra, Arindam; Sahraie, Nastaran Ranjbar; Bergmann, Arno; Strasser, Peter; Driess, Matthias

    2015-01-01

    Recently, there has been much interest in the design and development of affordable and highly efficient oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts that can resolve the pivotal issues that concern solar fuels, fuel cells, and rechargeable metal-air batteries. Here we present the synthesis and application of porous CoMn2 O4 and MnCo2 O4 spinel microspheres as highly efficient multifunctional catalysts that unify the electrochemical OER with oxidant-driven and photocatalytic water oxidation as well as the ORR. The porous materials were prepared by the thermal degradation of the respective carbonate precursors at 400 °C. The as-prepared spinels display excellent performances in electrochemical OER for the cubic MnCo2 O4 phase in comparison to the tetragonal CoMn2 O4 material in an alkaline medium. Moreover, the oxidant-driven and photocatalytic water oxidations were performed and they exhibited a similar trend in activity to that of the electrochemical OER. Remarkably, the situation is reversed in ORR catalysis, that is, the oxygen reduction activity and stability of the tetragonal CoMn2 O4 catalyst outperformed that of cubic MnCo2 O4 and rivals that of benchmark Pt catalysts. The superior catalytic performance and the remarkable stability of the unifying materials are attributed to their unique porous and robust microspherical morphology and the intrinsic structural features of the spinels. Moreover, the facile access to these high-performance materials enables a reliable and cost-effective production on a large scale for industrial applications. PMID:25394186

  1. Factors Affecting the Battery Performance of Anthraquinone-based Organic Cathode Materials

    SciTech Connect

    Xu, Wu; Read, Adam L.; Koech, Phillip K.; Hu, Dehong; Wang, Chong M.; Xiao, Jie; Padmaperuma, Asanga B.; Graff, Gordon L.; Liu, Jun; Zhang, Jiguang

    2012-02-01

    Two organic cathode materials based on poly(anthraquinonyl sulfide) structure with different substitution positions were synthesized and their electrochemical behavior and battery performances were investigated. The substitution positions on the anthraquinone structure, binders for electrode preparation and electrolyte formulations have been found to have significant effects on the battery performances of such organic cathode materials. The substitution position with less steric stress has higher capacity, longer cycle life and better high-rate capability. Polyvinylidene fluoride binder and ether-based electrolytes are favorable for the high capacity and long cycle life of the quinonyl organic cathodes.

  2. Hexagonal NiS nanobelts as advanced cathode materials for rechargeable Al-ion batteries.

    PubMed

    Yu, Zhijing; Kang, Zepeng; Hu, Zongqian; Lu, Jianhong; Zhou, Zhigang; Jiao, Shuqiang

    2016-08-16

    Hexagonal NiS nanobelts served as novel cathode materials for rechargeable Al-ion batteries based on an AlCl3/[EMIm]Cl ionic liquid electrolyte system. The nano-banded structure of the materials can facilitate the electrolyte immersion and enhance Al(3+) diffusion. The hexagonal NiS nanobelt based cathodes exhibit high storage capacity, good cyclability and low overpotential. PMID:27487940

  3. Recovery of cathode materials and Al from spent lithium-ion batteries by ultrasonic cleaning.

    PubMed

    He, Li-Po; Sun, Shu-Ying; Song, Xing-Fu; Yu, Jian-Guo

    2015-12-01

    Cathode materials are difficult to separate from Al-foil substrates during the recycling of spent lithium-ion batteries (LIBs), because of the strong bonding force present. In this study, ultrasonic cleaning was used to separate and recycle these cathode materials. The mechanism of separation was ascribed to the dissolution of polyvinylidene fluoride (PVDF) and the cavitation caused by ultrasound. Based on this mechanism, the key parameters affecting the peel-off efficiency of cathode materials from Al foil was identified as solvent nature, temperature, ultrasonic power, and ultrasonic time. The peel-off efficiency of cathode materials achieved ∼ 99% under the optimized conditions of N-methyl-2-pyrrolidone (NMP) cleaning fluid, 70°C process temperature, 240 W ultrasonic power, and 90 min of ultrasonication. The cathode materials separated from Al foil displayed a low agglomeration degree, which is beneficial to the subsequent leaching process. Finally, a new, environmentally-sound process was proposed to efficiently recycle cathode materials and Al from spent LIBs, consisting of manual dismantling, ultrasonic cleaning, and picking. PMID:26323202

  4. Lithium-ion transport through a tailored disordered phase on the LiNi0.5 Mn1.5 O4 surface for high-power cathode materials.

    PubMed

    Jo, Mi Ru; Kim, Yong-Il; Kim, Yunok; Chae, Ji Su; Roh, Kwang Chul; Yoon, Won-Sub; Kang, Yong-Mook

    2014-08-01

    The phase control of spinel LiNi0.5 Mn1.5 O4 was achieved through surface treatment that led to an enhancement of its electrochemical properties. Li(+) diffusion inside spinel LiNi0.5 Mn1.5 O4 could be promoted by modifying the surface structure of LiNi0.5 Mn1.5 O4 through phosphidation into a disordered phase (Fd3m) that allows facile Li(+) transport. Phosphidated LiNi0.5 Mn1.5 O4 showed a significantly enhanced electrochemical performance, even at high rates exceeding 10 C, demonstrating that the improved kinetics (related to the amount of Mn(3+) ) can render LiNi0.5 Mn1.5 O4 competitive as a high-power cathode material for electric vehicles and hybrid electric vehicles. PMID:24924807

  5. Selenium and selenium-sulfur cathode materials for high-energy rechargeable magnesium batteries

    NASA Astrophysics Data System (ADS)

    Zhao-Karger, Zhirong; Lin, Xiu-Mei; Bonatto Minella, Christian; Wang, Di; Diemant, Thomas; Behm, R. Jürgen; Fichtner, Maximilian

    2016-08-01

    Magnesium (Mg) is an attractive metallic anode material for next-generation batteries owing to its inherent dendrite-free electrodeposition, high capacity and low cost. Here we report a new class of Mg batteries based on both elemental selenium (Se) and selenium-sulfur solid solution (SeS2) cathode materials. Elemental Se confined into a mesoporous carbon was used as a cathode material. Coupling the Se cathode with a metallic Mg anode in a non-nucleophilic electrolyte, the Se cathode delivered a high initial volumetric discharge capacity of 1689 mA h cm-3 and a reversible capacity of 480 mA h cm-3 was retained after 50 cycles at a high current density of 2 C. The mechanistic insights into the electrochemical conversion in Mg-Se batteries were investigated by microscopic and spectroscopic methods. The structural transformation of cyclic Se8 into chainlike Sen upon battery cycling was revealed by ex-situ Raman spectroscopy. In addition, the promising battery performance with a SeS2 cathode envisages the perspective of a series of SeSn cathode materials combining the benefits of both selenium and sulfur for high energy Mg batteries.

  6. Improved electrochemical performance of the Cr doped cathode materials for energy storage/conversion devices

    NASA Astrophysics Data System (ADS)

    Sangeeta, Agnihotri, Shruti; Arya, Anil; Sharma, A. L.

    2016-05-01

    Successful synthesis of a nanostructured Cr-doped LiFePO4 cathode material has been prepared by a sol-gel technique followed by a single step thermal treatment at 750° C for 12 hours. As olivine type LiFePO4 has already gained much attention due to its advantages over other cathode materials, doping of metal ion is done in the paper to improve its drawback of lower conductivity. FESEM couples with EDX were done to characterize the morphology and particle size of the materials. LiFe(1-x)CrxPO4 (x=0.1, 0.2, 0.3) materials have average particle size of 30 to 50 nm. EDX analysis confirmed the precursor used and also confirmed the presence of carbon which is in good agreement with chemical analysis result. Electrical conductivity of the prepared cathode materials is estimated of the order of 10-5 Scm-1 by AC impedance analysis. The energy density and power density of the cathode materials is improved drastically after addition of Cr as dopant. The estimated parameters appear at desirable value for use of materials as cathode in energy storage/conversion devices.

  7. Spinel electrodes for rechargeable lithium batteries.

    SciTech Connect

    Thackeray, M. M.

    1999-11-10

    This paper gives a historical account of the development of spinel electrodes for rechargeable lithium batteries. Research in the late 1970's and early 1980's on high-temperature . Li/Fe{sub 3}O{sub 4} cells led to the evaluation of lithium spinels Li[B{sub 2}]X{sub 4} at room temperature (B = metal cation). This work highlighted the importance of the [B{sub 2}]X{sub 4}spinel framework as a host electrode structure and the ability to tailor the cell voltage by selection of different B cations. Examples of lithium-ion cells that operate with spinel anode/spinel cathode couples are provided. Particular attention is paid to spinels within the solid solution system Li{sub 1+x}Mn{sub 2-x}O{sub 4} (0 {le} x {le} 0.33).

  8. Characterization of Cathode Materials for Rechargeable Lithium Batteries using Synchrotron Based In Situ X-ray Techniques

    SciTech Connect

    Yang, Xiao-Qing

    2007-05-23

    The emergence of portable telecommunication, computer equipment and ultimately hybrid electric vehicles has created a substantial interest in manufacturing rechargeable batteries that are less expensive, non-toxic, operate for longer time, small in size and weigh less. Li-ion batteries are taking an increasing share of the rechargeable battery market. The present commercial battery is based on a layered LiCoO{sub 2} cathode and a graphitized carbon anode. LiCoO{sub 2} is expensive but it has the advantage being easily manufactured in a reproducible manner. Other low cost layered compounds such as LiNiO{sub 2}, LiNi{sub 0.85}Co{sub 0.15}O{sub 2} or cubic spinels such as LiMn{sub 2}O{sub 4} have been considered. However, these suffer from cycle life and thermal stability problems. Recently, some battery companies have demonstrated a new concept of mixing two different types of insertion compounds to make a composite cathode, aimed at reducing cost and improving self-discharge. Reports clearly showed that this blending technique can prevent the decline in ·capacity caused by cycling or storage at elevated temperatures. However, not much work has been reported on the charge-discharge characteristics and phase transitions for these composite cathodes. Understanding the structure and structural changes of electrode materials during the electrochemical cycling is the key to develop better .lithium ion batteries. The successful commercialization of the· lithium-ion battery is mainly built on the advances in solid state chemistry of the intercalation compounds. Most of the progress in understanding the lithium ion battery materials has been obtained from x-ray diffraction studies. Up to now, most XRD studies on lithium-ion battery materials have been done ex situ. Although these ex situ XRD studies have provided important information· about the structures of battery materials, they do face three major problems. First of all, the pre-selected charge (discharge) states may

  9. Role of surface coating on cathode materials for lithium-ion batteries.

    SciTech Connect

    Chen, Z.; Qin, Y.; Amine, K.; Sun, Y.-K.

    2010-01-01

    Surface coating of cathode materials has been widely investigated to enhance the life and rate capability of lithium-ion batteries. The surface coating discussed here was divided into three different configurations which are rough coating, core shell structure coating and ultra thin film coating. The mechanism of surface coating in achieving improved cathode performance and strategies to carry out this surface modification is discussed. An outlook on atomic layer deposition for lithium ion battery is also presented.

  10. Final Report on Materials Characterization for the Wetted Cathodes for Low-Temperature Aluminum Smelting Program

    SciTech Connect

    Windisch, Charles F.

    2002-10-30

    This report is a summary of materials characterization results on twenty cathode samples that were used in a novel aluminum reduction cell at the Northwest Aluminum Technologies laboratory. Most of these cathodes were based on the TiB2 composition and showed very little corrosion as a result of testing. Most of the samples also showed good wetting by Al metal that formed during cell operation.

  11. Strain-induced tuning of surface energetics, electron conductivity and reduction drive in spinel LiMn2O4 cathodes

    NASA Astrophysics Data System (ADS)

    Scivetti, Ivan; Teobaldi, Gilberto

    LiMn2O4 (LMO) implementation in cathodes of rechargeable Li-ion batteries (LIBs) is hampered by the limited lifetime of the material and the stability of its interfaces, starting from the Solid Electrolyte Interphase. Recent experiments and Density Functional Theory (DFT) simulations indicate that the formation and effectiveness of the SEI on LMO are related to the surface orientation. In this context, we analyse the role of geometrical strain for the relative energy, magnetic ordering and the reduction drive of several LMO surfaces. DFT simulations reveal LMO surfaces to be markedly sensitive to geometrical strain. Strain lower than 10% can lead to insulator-metal and ferromagnetic-antiferromagnetic transitions, alter the relative energy of LMO surfaces, and induce changes as large as 1.0 eV in the surface chemical potential, thence the reduction drive. Prompted by advances in the synthesis of metal-oxide core-shell nanostructures, the use of strained LMO coating to enhance SEI-formation is put forward as a potential nano-engineered strategy for longer lived SEI on LMO substrates. Eu FP7 project SIRBATT (Ref. 608502, end date: August 2016).

  12. Key strategies for enhancing the cycling stability and rate capacity of LiNi0.5Mn1.5O4 as high-voltage cathode materials for high power lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Yi, Ting-Feng; Mei, Jie; Zhu, Yan-Rong

    2016-06-01

    Spinel LiNi0.5Mn1.5O4 (LNMO) is one of the most promising high voltage cathode materials for future application due to its advantages of large reversible capacity, high thermal stability, low cost, environmental friendliness, and high energy density. LNMO can provide 20% and 30% higher energy density than traditional cathode materials LiCoO2 and LiFePO4, respectively. Unfortunately, LNMO-based batteries with LiPF6-based carbonate electrolytes always suffer from severe capacity deterioration and poor thermostability because of the oxidization of organic carbonate solvents and decomposition of LiPF6, especially at elevated temperatures and water-containing environment. Hence, it is necessary to systematically and comprehensively summarize the progress in understanding and modifying LNMO cathode from various aspects. In this review, the structure, transport properties and different reported possible fading mechanisms of LNMO cathode are first discussed detailedly. And then, the major goal of this review is to highlight new progress in using proposed strategies to improve the cycling stability and rate capacity of LNMO-based batteries, including synthesis, control of special morphologies, element doping and surface coating etc., especially at elevated temperatures. Finally, an insight into the future research and further development of LNMO cathode is discussed.

  13. Carbon incorporation effects and reaction mechanism of FeOCl cathode materials for chloride ion batteries

    NASA Astrophysics Data System (ADS)

    Zhao, Xiangyu; Li, Qiang; Yu, Tingting; Yang, Meng; Fink, Karin; Shen, Xiaodong

    2016-01-01

    Metal oxychlorides are proved to be new cathode materials for chloride ion batteries. However, this kind of cathode materials is still in a very early stage of research and development. The obtained reversible capacity is low and the electrochemical reaction mechanism concerning chloride ion transfer is not clear. Herein, we report FeOCl/carbon composites prepared by mechanical milling of the as-prepared FeOCl with carbon nanotube, carbon black or graphene nanoplatelets as cathode materials for chloride ion batteries. The electrochemical performance of the FeOCl electrode is evidently improved by the incorporation of graphene into the cathode. FeOCl/graphene cathode shows a high reversible capacity of 184 mAh g-1 based on the phase transformation between FeOCl and FeO. Two stages of this phase transformation are observed for the FeOCl cathode. New insight into the reaction mechanism of chloride ion dissociation of FeOCl is investigated by DFT + U + D2 calculations.

  14. Carbon incorporation effects and reaction mechanism of FeOCl cathode materials for chloride ion batteries

    PubMed Central

    Zhao, Xiangyu; Li, Qiang; Yu, Tingting; Yang, Meng; Fink, Karin; Shen, Xiaodong

    2016-01-01

    Metal oxychlorides are proved to be new cathode materials for chloride ion batteries. However, this kind of cathode materials is still in a very early stage of research and development. The obtained reversible capacity is low and the electrochemical reaction mechanism concerning chloride ion transfer is not clear. Herein, we report FeOCl/carbon composites prepared by mechanical milling of the as-prepared FeOCl with carbon nanotube, carbon black or graphene nanoplatelets as cathode materials for chloride ion batteries. The electrochemical performance of the FeOCl electrode is evidently improved by the incorporation of graphene into the cathode. FeOCl/graphene cathode shows a high reversible capacity of 184 mAh g−1 based on the phase transformation between FeOCl and FeO. Two stages of this phase transformation are observed for the FeOCl cathode. New insight into the reaction mechanism of chloride ion dissociation of FeOCl is investigated by DFT + U + D2 calculations. PMID:26777572

  15. Phase control of Mn-based spinel films via pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Feng, Zhenxing; Chen, Xiao; Fister, Timothy T.; Bedzyk, Michael J.; Fenter, Paul

    2016-07-01

    Phase transformations in battery cathode materials during electrochemical-insertion reactions lead to capacity fading and low cycle life. One solution is to keep the same phase of cathode materials during cation insertion-extraction processes. Here, we demonstrate a novel strategy to control the phase and composition of Mn-based spinel oxides for magnesium-ion battery applications through the growth of thin films on lattice-matched substrates using pulsed laser deposition. Materials at two extreme conditions are considered: fully discharged cathode MgMn2O4 and fully charged cathode Mn2O4. The tetragonal MgMn2O4 (MMO) phase is obtained on MgAl2O4 substrates, while the cubic MMO phase is obtained on MgO substrates. Similarly, growth of the empty Mn2O4 spinel in the cubic phase is obtained on an MgO substrate. These results demonstrate the ability to control separately the phase of spinel thin films (e.g., tetragonal vs. cubic MMO) at nominally fixed composition, and to maintain a fixed (cubic) phase while varying its composition (MgxMn2O4, for x = 0, 1). This capability provides a novel route to gain insights into the operation of battery electrodes for energy storage applications.

  16. On the dispersion of lithium-sulfur battery cathode materials effected by electrostatic and stereo-chemical factors of binders

    NASA Astrophysics Data System (ADS)

    Hong, Xiaoheng; Jin, Jun; Wen, Zhaoyin; Zhang, Sanpei; Wang, Qingsong; Shen, Chen; Rui, Kun

    2016-08-01

    Sodium carboxymethyl cellulose-styrene butadiene rubber (CMC-SBR), sodium alginate (SA) and LA132 are utilized as the polymer binders for the cathodes of Li-S batteries to study their dispersion mechanism on the cathode materials and the consequent influence on the performance of Li-S batteries. Zeta potential tests, differential scanning calorimetry analysis and calculations of the rotational barriers of the links of the polymer chains by General Atomic and Molecular Electronic Structure System (GAMESS) reveal that higher charge densities and better chain flexibility of the binders promise the dispersion of the downsized cathode materials. LA132 is found to have optimal characteristic for dispersing and stabilizing the cathode materials in aqueous environment. The cycling performance and SEM images of the cathodes demonstrate that cathodes with higher dispersion degree achieve higher discharge capacities. The electrochemical impedance spectroscopy (EIS) results further support that better dispersed cathodes have lower impedance resulting from their well established conducting frameworks.

  17. Phase stability of Li-Mn-O oxides as cathode materials for Li-ion batteries: insights from ab initio calculations.

    PubMed

    Longo, R C; Kong, F T; KC, Santosh; Park, M S; Yoon, J; Yeon, D-H; Park, J-H; Doo, S-G; Cho, K

    2014-06-21

    In this work, we present a density-functional theory (DFT) investigation of the phase stability, electrochemical stability and phase transformation mechanisms of the layered and over-lithiated Mn oxides. This study includes the thermodynamic stability of Li and oxygen vacancies, to examine the electrochemical activation mechanisms of these cathode materials. The DFT calculations provide phase diagrams of the Li-Mn-O system in both physical and chemical potential spaces, including the crystals containing vacancies as independent phases. The results show the ranges of electrochemical activity for both layered LiMnO2 and over-lithiated Li2MnO3. By using a thermodynamic model analysis, we found that the required temperature for oxygen evolution and Li vacancy formation is too high to be compatible with any practical synthesis temperature. Using solid-state transition calculations, we have identified the key steps in the phase transition mechanism of the layered LiMnO2 into the spinel phase. The calculated effects of pH on the Li-Mn-O phase stability elucidated the mechanism of Mn(2+) formation from the spinel phase under acidic conditions. PMID:24776820

  18. One-Pot Hydrothermal Synthesis of LiMn2O4 Cathode Material with Excellent High-Rate and Cycling Properties

    NASA Astrophysics Data System (ADS)

    Jiang, Qianqian; Wang, Xingyao; Zhang, Han

    2016-08-01

    The spinel LiMn2O4 was prepared by a one-step hydrothermal method using acetone as the reductant under different hydrothermal temperatures. X-ray diffraction and scanning electron microscopy analysis indicated that optimal LiMn2O4 particles (LMO-120) were synthesized at the temperature of 120°C and the particles were well distributed and about 410 nm in size. Electrochemical performance showed that the as-prepared LiMn2O4 particles exhibited a higher initial discharge capacity than commercial LiMn2O4 (131.5 mAh g-1 versus 115.6 mAh g-1 at 0.2 C). An excellent discharge capacity retention rate of 94.07% was observed after 60 charge-discharge cycles. On the other hand, when cycled at the high rate of 1 C, the optimal LiMn2O4 in this work showed a high discharge capacity of 107.5 mAh g-1 in contrast to only 92.3 mAh g-1 of the commercial LiMn2O4. These results indicate that LMO-120 showed excellent electrochemical performance, especially the prolonged cycling life and high-rate performance, which suggested that this spinel LiMn2O4 has promise for practical application as a high-rate cathode material for lithium ion batteries.

  19. One-Pot Hydrothermal Synthesis of LiMn2O4 Cathode Material with Excellent High-Rate and Cycling Properties

    NASA Astrophysics Data System (ADS)

    Jiang, Qianqian; Wang, Xingyao; Zhang, Han

    2016-05-01

    The spinel LiMn2O4 was prepared by a one-step hydrothermal method using acetone as the reductant under different hydrothermal temperatures. X-ray diffraction and scanning electron microscopy analysis indicated that optimal LiMn2O4 particles (LMO-120) were synthesized at the temperature of 120°C and the particles were well distributed and about 410 nm in size. Electrochemical performance showed that the as-prepared LiMn2O4 particles exhibited a higher initial discharge capacity than commercial LiMn2O4 (131.5 mAh g-1 versus 115.6 mAh g-1 at 0.2 C). An excellent discharge capacity retention rate of 94.07% was observed after 60 charge-discharge cycles. On the other hand, when cycled at the high rate of 1 C, the optimal LiMn2O4 in this work showed a high discharge capacity of 107.5 mAh g-1 in contrast to only 92.3 mAh g-1 of the commercial LiMn2O4. These results indicate that LMO-120 showed excellent electrochemical performance, especially the prolonged cycling life and high-rate performance, which suggested that this spinel LiMn2O4 has promise for practical application as a high-rate cathode material for lithium ion batteries.

  20. Studies on niobium triselenide cathode material for lithium rechargeable cells

    NASA Technical Reports Server (NTRS)

    Ratnakumar, B. V.; Ni, C. L.; Distefano, S.; Somoano, R. B.; Bankston, C. P.

    1988-01-01

    NbSe3 exhibits superior characteristics such as high capacity, high volumetric and gravimetric energy densities, and high discharge rate capability, as compared to other intercalating cathodes. This paper reports the preparation, characterization, and performance of NbSe3. Several electrochemical techniques, such as cyclic voltammetry, constant-current/constant-potential discharges, dc potentiodynamic scans, ac impedance, and ac voltammetry, have been used to give insight to the mechanisms of intercalation of three lithiums with NbSe3 and also into the rate determining process in the reduction of NbSe3.

  1. Cathode and electrolyte materials for solid oxide fuel cells and ion transport membranes

    DOEpatents

    Jacobson, Allan J; Wang, Shuangyan; Kim, Gun Tae

    2014-01-28

    Novel cathode, electrolyte and oxygen separation materials are disclosed that operate at intermediate temperatures for use in solid oxide fuel cells and ion transport membranes based on oxides with perovskite related structures and an ordered arrangement of A site cations. The materials have significantly faster oxygen kinetics than in corresponding disordered perovskites.

  2. Chemical compatibility study of melilite-type gallate solid electrolyte with different cathode materials

    NASA Astrophysics Data System (ADS)

    Mancini, Alessandro; Felice, Valeria; Natali Sora, Isabella; Malavasi, Lorenzo; Tealdi, Cristina

    2014-05-01

    Chemical reactivity between cathodes and electrolytes is a crucial issue for long term SOFCs stability and performances. In this study, chemical reactivity between selected cathodic materials and the ionic conducting melilite La1.50Sr0.50Ga3O7.25 has been extensively investigated by X-ray powder diffraction in a wide temperature range (up to 1573 K). Perovskite-type La0.8Sr0.2MnO3-d and La0.8Sr0.2Fe0.8Cu0.2O3-d and K2NiF4-type La2NiO4+d were selected as cathode materials. The results of this study allow identifying the most suitable electrode material to be used in combination with the melilite-type gallate electrolyte and set the basis for future work on this novel system.

  3. Gas evolution behaviors for several cathode materials in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Kong, Weihe; Li, Hong; Huang, Xuejie; Chen, Liquan

    Several 18650 lithium-ion batteries using LiCoO 2, LiMn 2O 4, and LiFePO 4 as cathode materials were assembled separately. Gas species of these batteries under normal cycling and overcharging to 4.5 and 5.0 V conditions were examined by means of GC-MS method. Under the normal charge and discharge voltage range, it is found that gas components are independent to the cathode materials. C 2H 5F gas was detected in all cases. A formation mechanism is proposed. Under overcharging condition, it is found that the gas components are different and there is a correlation between the C 2H 2 product and the oxidation ability of various delithiated cathode materials.

  4. Cathode material for lithium ion accumulators prepared by screen printing for Smart Textile applications

    NASA Astrophysics Data System (ADS)

    Syrový, T.; Kazda, T.; Syrová, L.; Vondrák, J.; Kubáč, L.; Sedlaříková, M.

    2016-03-01

    The presented study is focused on the development of LiFePO4 based cathode for thin and flexible screen printed secondary lithium based accumulators. An ink formulation was developed for the screen printing technique, which enabled mass production of accumulator's cathode for Smart Label and Smart Textile applications. The screen printed cathode was compared with an electrode prepared by the bar coating technique using an ink formulation based on the standard approach of ink composition. Obtained LiFePO4 cathode layers were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and galvanostatic charge/discharge measurements at different loads. The discharge capacity, capacity retention and stability at a high C rate of the LiFePO4 cathode were improved when Super P and PVDF were replaced by conductive polymers PEDOT:PSS. The achieved capacity during cycling at various C rates was approximately the same at the beginning and at the end, and it was about 151 mAh/g for cycling under 1C. The obtained results of this novelty electrode layer exceed the parameters of several electrode layers based on LiFePO4 published in literature in terms of capacity, cycling stability and overcomes them in terms of simplicity/industrial process ability of cathode layer fabrication and electrode material preparation.

  5. Electrochemical behaviour of mono-chloronitrobenzene as cathode material for magnesium reserve batteries

    NASA Astrophysics Data System (ADS)

    Thirunakaran, R.; Vasudevan, S.; Sivashanmugam, A.; Gopukumar, S.

    Mono-chloronitrobenzene (MCNB) is investigated as a cathode material for magnesium reserve batteries that use a magnesium anode and a 2 M magnesium perchlorate aqueous electrolyte. The composition of the conducting material (acetylene black) in the cathode mix is optimized to obtain better electrochemical performance. The reduction mechanism of mono-chloronitrobenzene is examined by means of cyclic voltammetry using a glassy carbon electrode. Discharge studies at different current drains indicate that Mg-MCNB cells exhibit the highest Coulombic efficiency (86%) at a current drain of 100 mA. The reduction of MCNB to mono-chloroaniline is irreversible and diffusion-controlled.

  6. Hollow nanoparticle cathode materials for sodium electrochemical cells and batteries

    DOEpatents

    Shevchenko, Elena; Rajh, Tijana; Johnson, Christopher S.; Koo, Bonil

    2016-07-12

    A cathode comprises, in its discharged state, a layer of hollow .gamma.-Fe.sub.2O.sub.3 nanoparticles disposed between two layers of carbon nanotubes, and preferably including a metallic current collector in contact with one of the layers of carbon nanotubes. Individual particles of the hollow .gamma.-Fe.sub.2O.sub.3 nanoparticles comprise a crystalline shell of .gamma.-Fe.sub.2O.sub.3 including cation vacancies within the crystal structure of the shell (i.e., iron vacancies of anywhere between 3% to 90%, and preferably 44 to 77% of available octahedral iron sites). Sodium ions are intercalated within at least some of the cation vacancies within the crystalline shell of the hollow .gamma.-Fe.sub.2O.sub.3 nanoparticles.

  7. High-energy cathode material for long-life and safe lithium batteries.

    PubMed

    Sun, Yang-Kook; Myung, Seung-Taek; Park, Byung-Chun; Prakash, Jai; Belharouak, Ilias; Amine, Khalil

    2009-04-01

    Layered lithium nickel-rich oxides, Li[Ni(1-x)M(x)]O(2) (M=metal), have attracted significant interest as the cathode material for rechargeable lithium batteries owing to their high capacity, excellent rate capability and low cost. However, their low thermal-abuse tolerance and poor cycle life, especially at elevated temperature, prohibit their use in practical batteries. Here, we report on a concentration-gradient cathode material for rechargeable lithium batteries based on a layered lithium nickel cobalt manganese oxide. In this material, each particle has a central bulk that is rich in Ni and a Mn-rich outer layer with decreasing Ni concentration and increasing Mn and Co concentrations as the surface is approached. The former provides high capacity, whereas the latter improves the thermal stability. A half cell using our concentration-gradient cathode material achieved a high capacity of 209 mA h g(-1) and retained 96% of this capacity after 50 charge-discharge cycles under an aggressive test profile (55 degrees C between 3.0 and 4.4 V). Our concentration-gradient material also showed superior performance in thermal-abuse tests compared with the bulk composition Li[Ni(0.8)Co(0.1)Mn(0.1)]O(2) used as reference. These results suggest that our cathode material could enable production of batteries that meet the demanding performance and safety requirements of plug-in hybrid electric vehicles. PMID:19305398

  8. Beyond Conventional Cathode Materials for Lithium-ion Batteries and Sodium-ion Batteries Nickel fluoride conversion materials and P2 type Sodium-ion intercalation cathodes

    NASA Astrophysics Data System (ADS)

    Lee, Dae Hoe

    The Li-ion battery is one of the most important rechargeable energy storage devices due to its high energy density, long cycle life, and reliable safety. Although the performances of Li-ion batteries have been improved dramatically, the limit in terms of the energy density still needs to be resolved to meet the growing demands for large-scale mobile devices. Choosing the cathode material is the most pivotal issue in achieving higher energy, since the energy density is directly correlated to the specific capacity of the cathode. Intercalation-based cathode materials have been widely utilized in commercial products; however they yield a limited capacity due to restricted crystallographic sites for Li-ions. In this thesis, the NiF2 and NiO doped NiF2/C conversion materials, which display substantially greater capacities, are intensively studied using various synchrotron X-ray techniques and magnetic measurements. The enhanced electronic conductivity of NiO doped NiF2/C is associated with a significant improvement in the reversible conversion reaction. While bimodal Ni nanoparticles are maintained for NiO doped NiF2/C upon the discharge, for pure NiF2 only smaller nanoparticles remain following the 2nd discharge. Based on the electronic conductivity, it is demonstrated that the size of Ni nanoparticles is associated with the conversion kinetics and consequently the reversibility. Although Li-ion batteries offer the highest energy density among all the secondary batteries, the amount of the reserves and the cost associated with the Li sources are still a concern. In the second part of the thesis, P2 type Na2/3[Ni1/3Mn2/3]O2 is investigated to understand the structural stability in the Na-ion batteries. Significantly improved battery performances are obtained by excluding the phase transformation region. In addition, the structural evolution of the P2-Na0.8[Li0.12Ni0.22Mn0.66]O 2 is tracked by in situ technique and revealed no phase transformation during the cycling. It

  9. Synthesis, Characterization and Testing of Novel Anode and Cathode Materials for Li-Ion Batteries

    SciTech Connect

    White, Ralph E.; Popov, Branko N.

    2002-10-31

    During this program we have synthesized and characterized several novel cathode and anode materials for application in Li-ion batteries. Novel synthesis routes like chemical doping, electroless deposition and sol-gel method have been used and techniques like impedance, cyclic voltammetry and charge-discharge cycling have been used to characterize these materials. Mathematical models have also been developed to fit the experimental result, thus helping in understanding the mechanisms of these materials.

  10. Solution synthesis and characterization of lithium manganese oxide cathode materials

    SciTech Connect

    Voigt, J.A.; Boyle, T.J.; Doughty, D.H.

    1995-07-01

    A nonaqueous coprecipitation process has been developed to prepare controlled stoichiometry lithium manganese oxalate precipitates. The process involved mixing a methanolic Li-Mn nitrate solution with a methanolic solution containing tetramethylammonium oxalate as the precipitating agent. The resulting oxalates were readily converted to a variety of phase pure lithium manganese oxides at moderate temperatures ({le}600{degrees}C), where the phase formed was determined by the initial Li/Mn ratio in the starting solution. Metal cation dopants have been incorporated into the oxalate precipitate by dissolving the appropriate metal nitrate in the Li-Mn precursor solution The various starting solutions, oxalate precipitates, and calcined oxides have been extensively characterized using a variety of techniques, including {sup 7}Li NMR, TGA/DTA, SEM, and XRD. Results indicate that a strong interaction occurs between Li and Mn in the nitrate solution which carries over into the oxalate phase during precipitation. The morphology and the crystallite size of the oxide powders were shown to be controlled by the morphology of the oxalate precursor and the oxalate calcination temperature, respectively. The results of initial cathode performance tests with respect to dopant type (Al, Ni, Co) and concentration for LiMn{sub 2}O{sub 4} are also reported.

  11. Aerospace applications of sodium batteries using novel cathode materials

    NASA Technical Reports Server (NTRS)

    Ratnakumar, B. V.; Di Stefano, S.; Bankston, C. P.

    1989-01-01

    Preliminary fundamental investigations aimed at evaluating sodium metal chloride systems for future aerospace applications are described. Since the sodium metal chloride systems are relatively new, the approach has been to characterize their fundamental properties in order to understand their limitations. To this end, a series of fundamental electrochemical investigations have been carried out, the results of which are reported here. The metal chloride cathodes show high exchange current densities which corroborate their good reversibility in a battery application. The reduction mechanisms appear to be complex and involve multielectron transfer steps and intermediates. Such intermediates in the reaction mechanism have already been identified in the case of FeCl2. Similar mechanisms may be operative in the case of NiCl2. CuCl2, however, exhibits a second relaxation loop in the impedance plot at low frequencies and also a sloping discharge curve, unlike FeCl2 and NiCl2, which may indicate the existence of monovalent copper in the reduction mechanism.

  12. Endurance test on a single cell of a novel cathode material for MCFC

    NASA Astrophysics Data System (ADS)

    Soler, J.; González, T.; Escudero, M. J.; Rodrigo, T.; Daza, L.

    The molten carbonate fuel cell (MCFC) is expected to be an efficient device for the conversion of chemical energy in the near future. However, one of the major limits to the lifetime is the dissolution of the nickel oxide cathode in the electrolyte. This problem can be overcome by the addition of new compounds to the nickel oxide. In this way, the performance and the endurance of a new Ni-Ce cathode for MCFC has been tested and the results compared to a commercial nickel cathode. The polarisation curves were measured in order to check the degradation of the cell performance with time. The results showed a better performance with the novel cathode material (136 mW/cm 2 at 200 mA/cm 2 during 2100 h) than the commercial one (the voltage decreased from 120 to 108 mW/cm 2 at 150 mA/cm 2 in 1000 h). The better performance of Ni-Ce cathode with respect to the Ni one can be attributed to the good effect of cerium in the cathode. The change in the nickel crystalline structure reduces the dissolution of nickel in the electrolyte and implies a greater endurance of the cell. The current-voltage curves were measured and showed the same trend for both cells. Postmortem analyses were done in order to characterise the cells. As a conclusion, the addition of cerium can be beneficial to overcome the dissolution of the nickel cathode in the electrolyte, which is considered one of the major limits to the lifetime of a MCFC.

  13. Catalyzed electrochemical gasification of carbonaceous materials at anode and electrowinning of metals at cathode

    SciTech Connect

    Vaughan, R.J.

    1983-09-20

    The electrochemical gasification reaction of carbonaceous materials by anodic oxidation in an aqueous acidic electrolyte to produce oxides of carbon at the anode and metallic elements at the cathode of an electrolysis cell is catalyzed by the use of an iron catalyst.

  14. Fabrication and characterization of lithium manganese nickel oxide sputtered thin film cathodes for lithium-ion batteries

    SciTech Connect

    Baggetto, Loic; Unocic, Raymond R; Dudney, Nancy J; Veith, Gabriel M

    2012-01-01

    Li-rich and stoichiometric Li1Mn1.5Ni0.5O4 (LMNO) cathode films have been prepared by magnetron sputtering. Sputtering from a Li stoichiometric target yields Li-rich films composed of spinel, layered and monoclinic phases. Films obtained from a Li deficient target are mostly made of a spinel phase and little layered material. The resulting cathode thin films have good capacity retention and very high rate capability. The reaction mechanism has been investigated by XRD and HRTEM and evidences the reversible formation of a spinel phase, as is also found for the powder samples. The film geometry enables to understand the effect of coatings (ZnO or LiPON). Coating high voltage cathodes reduces the coulombic losses but at the price of rate performance. Nonetheless, these coated sputtered electrode thin films offer a higher rate capability than other LMNO thin films obtained by other physical vapor deposition techniques.

  15. Different materials as a cathode modification layer on the impact of organic solar cells

    NASA Astrophysics Data System (ADS)

    Zhong, Jian; Huang, Qiuyan; Yu, Junsheng; Jiang, Yadong

    2010-10-01

    Organic thin film solar cells based on conjugated polymer or small molecules have showed an interesting approach to energy conversion since Tang reported a single donor-accepter hetero-junction solar cell. The power conversion efficiency of organic solar cells has increased steadily over last decade. Small-molecular weight organic double heterojunction donor-acceptor layer organic solar cells (OSC) with a structure of indium-tin-oxide (ITO)/CuPc(200Å)/C60(400Å)/x/Ag(1000Å), using CuPc(copper Phthalocyanine)as donor layer, and Alq3(8-Hydroxyquinoline aluminum salt), BCP(Bromocresol purple sodium salt) and Bphen(4'7-diphyenyl-1,10-phenanthroline) as cathode modification layer, respectively were fabricated. The performance of OSC was studied as a function of the different materials as an cathode modification layer to optimize the structure. The current-voltage characteristic of the solar cell under AM1.5 solar illumination at an intensity of 100 mw/cm2 showed that the power conversion efficiency (PCE) was dependent of the different materials of the cathode modification layer. the efficiency along with the different materials as an cathode modification layer will diminish under that standard solar illumination(AM1.5)was obtained. Using a double heterostructure of ITO/CuPc(200Å)/C60(400Å)/Alq3(60Å)/Ag(1000Å) with high-vacuum evaporation technology, the efficiency was 0.587%.the efficiency was 0.967% when the material of the cathode modification layer was BCP, with the structure of ITO/CuPc(200Å)/C60(400Å)/BCP(35Å)/Ag(1000Å), and the efficiency was 0.742% when the material of the cathode modification layer was Bphen, with the structure of ITO/CuPc(200Å)/C60(400Å)/ Bphen(50Å)/Ag(1000Å).Using different materials as a cathode modification layer, it can be seen that the material which matches the energy level could even eventually be able to improve the energy conversion efficiency more.

  16. Structural changes and thermal stability of charged LiNixMnyCozO2 cathode materials studied by combined in situ time-resolved XRD and mass spectroscopy

    DOE PAGESBeta

    Bak, Seong -Min; Hu, Enyuan; Zhou, Yongning; Yu, Xiqian; Senanayake, Sanjaya D.; Cho, Sung -Jin; Kim, Kwang -Bum; Chung, Kyung Yoon; Yang, Xiao -Qing; Nam, Kyung -Wan

    2014-11-24

    Thermal stability of charged LiNixMnyCozO2 (NMC, with x + y + z = 1, x:y:z = 4:3:3 (NMC433), 5:3:2 (NMC532), 6:2:2 (NMC622), and 8:1:1 (NMC811)) cathode materials is systematically studied using combined in situ time- resolved X-ray diffraction and mass spectroscopy (TR-XRD/MS) techniques upon heating up to 600 °C. The TR-XRD/MS results indicate that the content of Ni, Co, and Mn significantly affects both the structural changes and the oxygen release features during heating: the more Ni and less Co and Mn, the lower the onset temperature of the phase transition (i.e., thermal decomposition) and the larger amount of oxygenmore » release. Interestingly, the NMC532 seems to be the optimized composition to maintain a reasonably good thermal stability, comparable to the low-nickel-content materials (e.g., NMC333 and NMC433), while having a high capacity close to the high-nickel-content materials (e.g., NMC811 and NMC622). The origin of the thermal decomposition of NMC cathode materials was elucidated by the changes in the oxidation states of each transition metal (TM) cations (i.e., Ni, Co, and Mn) and their site preferences during thermal decomposition. It is revealed that Mn ions mainly occupy the 3a octahedral sites of a layered structure (R3¯m) but Co ions prefer to migrate to the 8a tetrahedral sites of a spinel structure (Fd3¯m) during the thermal decomposition. Such element-dependent cation migration plays a very important role in the thermal stability of NMC cathode materials. The reasonably good thermal stability and high capacity characteristics of the NMC532 composition is originated from the well-balanced ratio of nickel content to manganese and cobalt contents. As a result, this systematic study provides insight into the rational design of NMC-based cathode materials with a desired balance between thermal stability and high energy density.« less

  17. Influence of cathode material on generation of energetic hydrogen atoms in a glow discharge

    SciTech Connect

    Cvetanovic, N.; Obradovic, B. M.; Kuraica, M. M.

    2011-01-01

    In this paper influence of cathode material on formation of fast hydrogen atoms in an abnormal glow discharge is investigated using Balmer alpha emission spectroscopy. Energetic H atoms are generated in charge exchange reactions of hydrogen ions that are accelerated in the electric field, and also formed in the backscattering process at the cathode surface. Copper and graphite cathodes were used. Investigation was performed in two orthogonal directions of observation in pure hydrogen and argon-hydrogen mixture. The shapes of the profiles are examined together with the space intensity distribution of Balmer alpha line. Reduced atom reflection from graphite was manifested in the spectroscopic result, in accordance to the field acceleration model. The effect was evident only at high ion energies. This is explained by energy dependence of reflection coefficient for H atoms.

  18. Mobility of cations in magnesium aluminate spinel

    NASA Astrophysics Data System (ADS)

    Martinelli, J. R.; Sonder, E.; Weeks, R. A.; Zuhr, R. A.

    1986-04-01

    Transport of cations in magnesium aluminate spinel due to an applied electric field at approximately 1000 °C has been measured by observing changes in elemental concentrations near the cathode and anode surfaces using ion backscattering techniques. The results indicate that magnesium ions are the mobile species at 1000 °C and that these ions combine with ambient oxygen at the cathode surface to form a MgO layer. Quantitative interpretation of the data leads to the conclusion that the ionic transference number of spinel becomes approximately 0.5 after treatment in an electric field.

  19. Materials characterization of impregnated W and W-Ir cathodes after oxygen poisoning

    NASA Astrophysics Data System (ADS)

    Polk, James E.; Capece, Angela M.

    2015-05-01

    Electric thrusters use hollow cathodes as the electron source for generating the plasma discharge and for beam neutralization. These cathodes contain porous tungsten emitters impregnated with BaO material to achieve a lower surface work function and are operated with xenon propellant. Oxygen contaminants in the xenon plasma can poison the emitter surface, resulting in a higher work function and increased operating temperature. This could lead directly to cathode failure by preventing discharge ignition or could accelerate evaporation of the BaO material. Exposures over hundreds of hours to very high levels of oxygen can result in increased temperatures, oxidation of the tungsten substrate, and the formation of surface layers of barium tungstates. In this work, we present results of a cathode test in which impregnated tungsten and tungsten-iridium emitters were operated with 100 ppm of oxygen in the xenon plasma for several hundred hours. The chemical and morphological changes were studied using scanning electron microscopy, energy dispersive spectroscopy, and laser profilometry. The results provide strong evidence that high concentrations of oxygen accelerate the formation of tungstate layers in both types of emitters, a phenomenon not inherent to normal cathode operation. Deposits of pure tungsten were observed on the W-Ir emitter, indicating that tungsten is preferentially removed from the surface and transported in the insert plasma. A W-Ir cathode surface will therefore evolve to a pure W composition, eliminating the work function benefit of W-Ir. However, the W-Ir emitter exhibited less erosion and redeposition at the upstream end than the pure W emitter.

  20. An investigation of anode and cathode materials in photomicrobial fuel cells.

    PubMed

    Schneider, Kenneth; Thorne, Rebecca J; Cameron, Petra J

    2016-02-28

    Photomicrobial fuel cells (p-MFCs) are devices that use photosynthetic organisms (such as cyanobacteria or algae) to turn light energy into electrical energy. In a p-MFC, the anode accepts electrons from microorganisms that are either growing directly on the anode surface (biofilm) or are free floating in solution (planktonic). The nature of both the anode and cathode material is critical for device efficiency. An ideal anode is biocompatible and facilitates direct electron transfer from the microorganisms, with no need for an electron mediator. For a p-MFC, there is the additional requirement that the anode should not prevent light from perfusing through the photosynthetic cells. The cathode should facilitate the rapid reaction of protons and oxygen to form water so as not to rate limit the device. In this paper, we first review the range of anode and cathode materials currently used in p-MFCs. We then present our own data comparing cathode materials in a p-MFC and our first results using porous ceramic anodes in a mediator-free p-MFC. PMID:26755764

  1. Progress in High-Capacity Core-Shell Cathode Materials for Rechargeable Lithium Batteries.

    PubMed

    Myung, Seung-Taek; Noh, Hyung-Joo; Yoon, Sung-June; Lee, Eung-Ju; Sun, Yang-Kook

    2014-02-20

    High-energy-density rechargeable batteries are needed to fulfill various demands such as self-monitoring analysis and reporting technology (SMART) devices, energy storage systems, and (hybrid) electric vehicles. As a result, high-energy electrode materials enabling a long cycle life and reliable safety need to be developed. To ensure these requirements, new material chemistries can be derived from combinations of at least two compounds in a secondary particle with varying chemical composition and primary particle morphologies having a core-shell structure and spherical cathode-active materials, specifically a nanoparticle core and shell, nanoparticle core and nanorod shell, and nanorod core and shell. To this end, several layer core-shell cathode materials were developed to ensure high capacity, reliability, and safety. PMID:26270835

  2. Electron microscopy characterization of Li-based cathode materials for battery applications

    NASA Astrophysics Data System (ADS)

    Phillips, Patrick; Klie, Robert

    2014-03-01

    The role of aberration-corrected scanning transmission electron microscopy (STEM) in materials characterization is examined with respect to Li-based cathode materials for battery applications. STEM-based methods are quickly becoming the most promising characterization tools for these materials, owed largely to the wide-range of techniques available on advanced STEM instruments, including the direct imaging of both heavy and light elements, and both energy-dispersive X-ray (EDX) and electron energy loss (EEL) spectroscopies. The current talk with focus on structural and chemical characterization of a Li-based cathode material, both in a pristine and irradiated state. Focus will remain on the nucleation of structural transitions, while also characterizing relevant parameters such as the manganese valence and oxygen presence. Various imaging modes, including high/low angle annular dark field (H/LAADF) and annular bright field (ABF), in conjunction with EELS, will be used extensively for this analysis.

  3. Correlation of cathode parameters of high power grid tubes with material characteristics of cathode-grid units

    NASA Astrophysics Data System (ADS)

    Melnikova, Irina P.; Polyakov, Igor V.; Usanov, Dmitry A.

    2005-09-01

    One way to increase the longevity of dispenser cathodes is based on reducing the Barium evaporation. This can be achieved by the decrease of the reaction "activity" of the emitter impregnant with the porous tungsten (W) body, which supplies free Barium from the interior of the porous cathode to its surface.

  4. Exceptional performance of a high voltage spinel LiNi0.5Mn1.5O4 cathode in all one dimensional architectures with an anatase TiO2 anode by electrospinning

    NASA Astrophysics Data System (ADS)

    Arun, Nagasubramanian; Aravindan, Vanchiappan; Jayaraman, Sundaramurthy; Shubha, Nageswaran; Ling, Wong Chui; Ramakrishna, Seeram; Madhavi, Srinivasan

    2014-07-01

    We report for the first time the synthesis and extraordinary performance of a high voltage spinel LiNi0.5Mn1.5O4 fiber cathode in all one dimensional (1D) architecture. Structural and morphological features are analyzed by various characterization techniques. Li-insertion/extraction properties are evaluated in a half-cell assembly (Li/LiNi0.5Mn1.5O4) and subsequently in full-cell configuration with an anatase TiO2 fiber anode. In both half- and full-cell assemblies, gelled polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP) is used as the separator-cum-electrolyte. All the one dimensional components used for fabricating Li-ion cells are prepared by a simple and scalable electrospinning technique. The full-cell, LiNi0.5Mn1.5O4/gelled PVdF-HFP/TiO2 delivered the reversible capacity of ~102 mA h g-1 at 0.1 C rate with an operating potential of ~2.8 V. Excellent rate capability and stable cycling profiles are noted for such a full-cell assembly with a capacity retention of ~86% after 400 cycles.

  5. Exploiting chemically and electrochemically reactive phosphite derivatives for high-voltage spinel LiNi0.5Mn1.5O4 cathodes

    NASA Astrophysics Data System (ADS)

    Song, Young-Min; Kim, Choon-Ki; Kim, Ko-Eun; Hong, Sung You; Choi, Nam-Soon

    2016-01-01

    A family of organophosphorus compounds including triphenyl phosphite (TPP), trimethyl phosphite (TMP), tris(2,2,2-trifluoroethyl) phosphite (TFEP), and tris(trimethylsilyl) phosphite (TMSP) is investigated as additives for the stabilization of high-voltage LiNi0.5Mn1.5O4 (LNMO) cathode-electrolyte interface. Our investigation reveals that the cycling performance of Li/LNMO half cells with the TMP, TFEP or TMSP additive is drastically improved at 60 °C compared to the baseline electrolyte. Among the various phosphite-based additives tested, TMSP additive enables facile Li ion transport at high C rates and significantly enhances the storage performance of the Li/LNMO cells at 60 °C. To understand the effects of the phosphite-based additives on electrolyte oxidative decomposition at high voltages, the surface chemistry of the cathode after precycling is investigated via ex-situ X-ray photoelectron spectroscopy (XPS). Additionally, the roles of phosphite-based additives to suppress LiPF6 hydrolysis and to remove HF are examined via 19F and 31P NMR spectroscopies.

  6. Composite cathode materials development for intermediate temperature solid oxide fuel cell systems

    NASA Astrophysics Data System (ADS)

    Qin, Ya

    Solid oxide fuel cell (SOFC) systems are of particular interest as electrochemical power systems that can operate on various hydrocarbon fuels with high fuel-to-electrical energy conversion efficiency. Within the SOFC stack, La0.8Sr 0.2Ga0.8Mg0.115Co0.085O3-delta (LSGMC) has been reported as an optimized composition of lanthanum gallate based electrolytes to achieve higher oxygen ionic conductivity at intermediate temperatures, i.e., 500-700°C. The electrocatalytic properties of interfaces between LSGMC electrolytes and various candidate intermediate-temperature SOFC cathodes have been investigated. Sm0.5Sr0.5CoO 3-delta (SSC), and La0.6Sr0.4Co0.2Fe 0.8O3-delta (LSCF), in both pure and composite forms with LSGMC, were investigated with regards to both oxygen reduction and evolution, A range of composite cathode compositions, having ratios of SSC (in wt.%) with LSGMC (wt.%) spanning the compositions 9:1, 8:2, 7:3, 6:4 and 5:5, were investigated to determine the optimal cathode-electrolyte interface performance at intermediate temperatures. All LSGMC electrolyte and cathode powders were synthesized using the glycine-nitrate process (GNP). Symmetrical electrochemical cells were investigated with three-electrode linear dc polarization and ac impedance spectroscopy to characterize the kinetics of the interfacial reactions in detail. Composite cathodes were found to perform better than the single phase cathodes due to significantly reduced polarization resistances. Among those composite SSC-LSGMC cathodes, the 7:3 composition has demonstrated the highest current density at the equivalent overpotential values, indicating that 7:3 is an optimal mixing ratio of the composite cathode materials to achieve the best performance. For the composite SC-LSGMC cathode/LSGMC interface, the cathodic overpotential under 1 A/cm2 current density was as low as 0.085 V at 700°C, 0.062V at 750°C and 0.051V at 800°C in air. Composite LSCF-LSGMC cathode/LSGMC interfaces were found to have

  7. Local structure modification in lithium rich layered Li-Mn-O cathode material

    NASA Astrophysics Data System (ADS)

    Giorgetti, Marco; Wang, Diandian; Aquilanti, Giuliana; Buchholz, Daniel; Passerini, Stefano

    2016-05-01

    X-ray absorption spectroscopy (XAS) is applied to study the local geometry of Co, Ni, and Mn sites in a new high voltage cathode for lithium batteries. The material is a solid solution between Li2MnO3 and Li(x)Mn0.4Ni0.4Co0.2O2. The XAS technique has permitted to check the local atomic structure and charge associated with the metals in a series of electrodes with different lithium concentration x, obtained during the first charge operation, and compared to the first discharge and a successive charge. The ex-situ XAS investigation on the initial activation of the cathode material (first charge) can be described by two separated reaction of LiMO2 (M = Ni and Co) and Li2MnO3. The strength and limitations of the ExAFS approach in these materials is underlined.

  8. Spinel: where did it go?

    NASA Astrophysics Data System (ADS)

    Roy, Donald W.

    1997-11-01

    Polycrystalline magnesium aluminum oxide, transparent from 200 nanometers to 6 microns, offers a unique combination of optical and physical properties. A superior dome and window material in respect to rain and particle erosion, solar radiation, high temperatures and humidity; it is resistant to attack by strong acids, sea water, and jet fuels. Although it had been qualified for, and designed into several advanced UV/visible/IR optical systems, production of hot-pressed Spinel was stopped at Alpha Optical Systems in 1993 by the parent company Coors Ceramics. Development efforts on cold-pressed/sinter/HIP Spinel at RCS Technologies are reportedly stalemated at the present time. Therefore, there is no known significant effort directed toward the development of polycrystalline Spinel. however, the author is in contact with both domestic and foreign laboratories which have expressed a desire to develop the technology for transparent Spinel. Renewed development may begin during calendar year 1997. Because of the apparent continuing significant interest in Spinel this paper will review the properties of Spinel and will compare the most significant properties of Spinel with sapphire and aluminum oxynitride. The limitations of competing manufacturing processes, will be mentioned. Grinding and polishing considerations will be reviewed in respect to maximizing optical and structural properties.

  9. Rapid synthesis of monodispersed highly porous spinel nickel cobaltite (NiCo{sub 2}O{sub 4}) electrode material for supercapacitors

    SciTech Connect

    Naveen, A. Nirmalesh Selladurai, S.

    2015-06-24

    Monodispersed highly porous spinel nickel cobaltite electrode material was successfully synthesized in a short time using combustion technique. Single phase cubic nature of the spinel nickel cobaltite with average crystallite size of 24 nm was determined from X-ray diffraction study. Functional groups present in the compound were determined from FTIR study and it further confirms the spinel formation. FESEM images reveal the porous nature of the prepared material and uniform size distribution of the particles. Electrochemical evaluation was performed using Cyclic Voltammetry (CV) technique, Chronopotentiometry (CP) and Electrochemical Impedance Spectroscopy (EIS). Results reveal the typical pseudocapacitive behaviour of the material. Maximum capacitance of 754 F/g was calculated at the scan rate of 5 mV/s, high capacitance was due to the unique porous morphology of the electrode. Nyquist plot depicts the low resistance and good electrical conductivity of nickel cobaltite. It has been found that nickel cobaltite prepared by this typical method will be a potential electrode material for supercapcitor application.

  10. Innovative application of ionic liquid to separate Al and cathode materials from spent high-power lithium-ion batteries.

    PubMed

    Zeng, Xianlai; Li, Jinhui

    2014-04-30

    Because of the increasing number of electric vehicles, there is an urgent need for effective recycling technologies to recapture the significant amount of valuable metals contained in spent lithium-ion batteries (LiBs). Previous studies have indicated, however, that Al and cathode materials were quite difficult to separate due to the strong binding force supplied by the polyvinylidene fluoride (PVDF), which was employed to bind cathode materials and Al foil. This research devoted to seek a new method of melting the PVDF binder with heated ionic liquid (IL) to separate Al foil and cathode materials from the spent high-power LiBs. Theoretical analysis based on Fourier's law was adopted to determine the heat transfer mechanism of cathode material and to examine the relationship between heating temperature and retention time. All the experimental and theoretic results show that peel-off rate of cathode materials from Al foil could reach 99% when major process parameters were controlled at 180°C heating temperature, 300 rpm agitator rotation, and 25 min retention time. The results further imply that the application of IL for recycling Al foil and cathode materials from spent high-power LiBs is highly efficient, regardless of the application source of the LiBs or the types of cathode material. This study endeavors to make a contribution to an environmentally sound and economically viable solution to the challenge of spent LiB recycling. PMID:24607415

  11. Synthesis and investigation of novel cathode materials for sodium ion batteries

    NASA Astrophysics Data System (ADS)

    Sawicki, Monica

    Environmental pollution and eventual depletion of fossil fuels and lithium has increased the need for research towards alternative electrical energy storage systems. In this context, research in sodium ion batteries (NIBs) has become more prevalent since the price in lithium has increased due to its demand and reserve location. Sodium is an abundant resource that is low cost, and safe; plus its chemical properties are similar to that of Li which makes the transition into using Na chemistry for ion battery systems feasible. In this study, we report the effects of processing conditions on the electrochemical properties of Na-ion batteries made of the NaCrO2 cathode. NaCrO2 is synthesized via solid state reactions. The as-synthesized powder is then subjected to high-energy ball milling under different conditions which reduces particle size drastically and causes significant degradation of the specific capacity for NaCrO2. X-ray diffraction reveals that lattice distortion has taken place during high-energy ball milling and in turn affects the electrochemical performance of the cathode material. This study shows that a balance between reducing particle size and maintaining the layered structure is essential to obtain high specific capacity for the NaCrO2 cathode. In light of the requirements for grid scale energy storage: ultra-long cycle life (> 20,000 cycles and calendar life of 15 to 20 years), high round trip efficiency (> 90%), low cost, sufficient power capability, and safety; the need for a suitable cathode materials with excellent capacity retention such as Na2MnFe(CN)6 and K2MnFe(CN)6 will be investigated. Prussian blue (A[FeIIIFeII (CN)6]•xH2O, A=Na+ or K+ ) and its analogues have been investigated as an alkali ion host for use as a cathode material. Their structure (FCC) provides large ionic channels along the direction enabling facile insertion and extraction of alkali ions. This material is also capable of more than one Na ion insertion per unit formula

  12. Secondary cell with orthorhombic alkali metal/manganese oxide phase active cathode material

    DOEpatents

    Doeff, M.M.; Peng, M.Y.; Ma, Y.; Visco, S.J.; DeJonghe, L.C.

    1996-09-24

    An alkali metal manganese oxide secondary cell is disclosed which can provide a high rate of discharge, good cycling capabilities, good stability of the cathode material, high specific energy (energy per unit of weight) and high energy density (energy per unit volume). The active material in the anode is an alkali metal and the active material in the cathode comprises an orthorhombic alkali metal manganese oxide which undergoes intercalation and deintercalation without a change in phase, resulting in a substantially linear change in voltage with change in the state of charge of the cell. The active material in the cathode is an orthorhombic structure having the formula M{sub x}Z{sub y}Mn{sub (1{minus}y)}O{sub 2}, where M is an alkali metal; Z is a metal capable of substituting for manganese in the orthorhombic structure such as iron, cobalt or titanium; x ranges from about 0.2 in the fully charged state to about 0.75 in the fully discharged state, and y ranges from 0 to 60 atomic %. Preferably, the cell is constructed with a solid electrolyte, but a liquid or gelatinous electrolyte may also be used in the cell. 11 figs.

  13. Theoretical investigation of Chevrel phase materials for cathodes accommodating Ca2+ ions

    NASA Astrophysics Data System (ADS)

    Smeu, Manuel; Hossain, Md Sazzad; Wang, Zi; Timoshevskii, Vladimir; Bevan, Kirk H.; Zaghib, Karim

    2016-02-01

    The Chevrel phase compounds Mo6X8 (X = S, Se, Te) are theoretically studied by ab initio methods as potential candidates for battery cathode materials. The voltage profiles are calculated for the cases of various alkaline earth metals (Mg, Ca, Sr, Ba) serving as guest intercalation ions. The Ca ions are shown to offer the practically significant voltage of ∼1.0-1.25 V, with S substitution giving the highest voltage over Se and Te. We further demonstrate that doubling the capacity of such a battery would also be possible by incorporating a second Ca ion near the Mo6X8 cluster. The electronic properties of this material are investigated, revealing that the entire Mo6 cluster behaves as a redox center. Finally, the ion diffusion barriers are calculated, showing comparable values to existing battery materials. This work demonstrates that the Chevrel phase may be useful as a cathode material for intercalating divalent ions, and also offers insights into possible tuning of cathode properties by judicious selection of the constituents.

  14. Glass-containing composite cathode contact materials for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Tucker, Michael C.; Cheng, Lei; DeJonghe, Lutgard C.

    2011-10-01

    The feasibility of adding glass to conventional SOFC cathode contact materials in order to improve bonding to adjacent materials in the cell stack is assessed. A variety of candidate glass compositions are added to LSM and SSC. The important properties of the resulting composites, including conductivity, sintering behavior, coefficient of thermal expansion, and adhesion to LSCF and Mn1.5Co1.5O4-coated 441 stainless steel are used as screening parameters. Adhesion of LSM to LSCF improved from 3.9 to 5.3 MPa upon addition of SCZ-8 glass. Adhesion of LSM to coated stainless steel improved from 1.8 to 3.9 MPa upon addition of Schott GM31107 glass. The most promising cathode contact material/glass composites are coated onto Mn1.5Co1.5O4-coated 441 stainless steel substrates and subjected to area-specific resistance testing at 800 °C. In all cases, area-specific resistance is found to be in the range 2.5-7.5 mOhm cm2 and therefore acceptable. Indeed, addition of glass is found to improve bonding of the cathode contact material layer without sacrificing acceptable conductivity.

  15. Secondary cell with orthorhombic alkali metal/manganese oxide phase active cathode material

    DOEpatents

    Doeff, Marca M.; Peng, Marcus Y.; Ma, Yanping; Visco, Steven J.; DeJonghe, Lutgard C.

    1996-01-01

    An alkali metal manganese oxide secondary cell is disclosed which can provide a high rate of discharge, good cycling capabilities, good stability of the cathode material, high specific energy (energy per unit of weight) and high energy density (energy per unit volume). The active material in the anode is an alkali metal and the active material in the cathode comprises an orthorhombic alkali metal manganese oxide which undergoes intercalation and deintercalation without a change in phase, resulting in a substantially linear change in voltage with change in the state of charge of the cell. The active material in the cathode is an orthorhombic structure having the formula M.sub.x Z.sub.y Mn.sub.(1-y) O.sub.2, where M is an alkali metal; Z is a metal capable of substituting for manganese in the orthorhombic structure such as iron, cobalt or titanium; x ranges from about 0.2 in the fully charged state to about 0.75 in the fully discharged state, and y ranges from 0 to 60 atomic %. Preferably, the cell is constructed with a solid electrolyte, but a liquid or gelatinous electrolyte may also be used in the cell.

  16. Designing and Thermal Analysis of Safe Lithium Ion Cathode Materials for High Energy Applications

    NASA Astrophysics Data System (ADS)

    Hu, Enyuan

    Safety is one of the most critical issues facing lithium-ion battery application in vehicles. Addressing this issue requires the integration of several aspects, especially the material chemistry and the battery thermal management. First, thermal stability investigation was carried out on an attractive high energy density material LiNi0.5Mn1.5O4. New findings on the thermal-stability and thermal-decomposition-pathways related to the oxygen-release are discovered for the high-voltage spinel Li xNi0.5Mn1.5O4 (LNMO) with ordered (o-) and disordered (d-) structures at fully delithiated (charged) state using a combination of in situ time-resolved x-ray diffraction (TR-XRD) coupled with mass spectroscopy (MS) and x-ray absorption spectroscopy (XAS). Both fully charged o--LixNi0.5Mn1.5O 4 and d-LixNi0.5Mn1.5O 4 start oxygen-releasing structural changes at temperatures below 300 °C, which is in sharp contrast to the good thermal stability of the 4V-spinel LixMn2O4 with no oxygen being released up to 375 °C. This is mainly caused by the presence of Ni4+ in LNMO, which undergoes dramatic reduction during the thermal decomposition. In addition, charged o-LNMO shows better thermal stability than the d-LNMO counterpart, due to the Ni/Mn ordering and smaller amount of the rock-salt impurity phase in o-LNMO. Newly identified two thermal-decomposition-pathways from the initial LixNi0.5Mn1.5O 4 spinel to the final NiMn2O4-type spinel structure with and without the intermediate phases (NiMnO3 and alpha-Mn 2O3) are found to play key roles in thermal stability and oxygen release of LNMO during thermal decomposition. In addressing the safety issue associated with LNMO, Fe is selected to partially substitute Ni and Mn simultaneously utilizing the electrochemical activity and structure-stabilizing high spin Fe3+. The synthesized LiNi1/3Mn4/3Fe1/3O4 showed superior thermal stability and satisfactory electrochemical performance. At charged state, it is able to withstand the temperature as

  17. Bare-tether cathodic contact through thermionic emission by low-work-function materials

    SciTech Connect

    Chen Xin; Sanmartin, J. R.

    2012-07-15

    A new material, C12A7:e{sup -} electride, which might present a work function as low as 0.6 eV and moderately high temperature stability, was recently proposed as coating for floating bare tethers. Arising from heating under space operation, current is emitted by thermionic emission along a thus coated cathodic segment. A preliminary study on the space-charge-limited (SCL) double layer in front of the cathodic segment is presented using Langmuir's SCL electron current between cylindrical electrodes and orbital-motion-limited ion-collection sheath. A detailed calculation of current and bias profiles along the entire tether length is carried out with ohmic effects and the transition from SCL to full Richardson-Dushman emission included. Analysis shows that in the simplest drag mode, under typical orbital and tether conditions, thermionic emission leads to a short cathodic section and may eliminate the need for an active cathodic device and its corresponding gas feed requirements and power subsystem, which results in a truly 'propellant-less' tether system for such basic applications as de-orbiting low earth orbit satellites.

  18. Bare-tether cathodic contact through thermionic emission by low-work-function materials

    NASA Astrophysics Data System (ADS)

    Chen, Xin; Sanmartín, J. R.

    2012-07-01

    A new material, C12A7:e- electride, which might present a work function as low as 0.6 eV and moderately high temperature stability, was recently proposed as coating for floating bare tethers. Arising from heating under space operation, current is emitted by thermionic emission along a thus coated cathodic segment. A preliminary study on the space-charge-limited (SCL) double layer in front of the cathodic segment is presented using Langmuir's SCL electron current between cylindrical electrodes and orbital-motion-limited ion-collection sheath. A detailed calculation of current and bias profiles along the entire tether length is carried out with ohmic effects and the transition from SCL to full Richardson-Dushman emission included. Analysis shows that in the simplest drag mode, under typical orbital and tether conditions, thermionic emission leads to a short cathodic section and may eliminate the need for an active cathodic device and its corresponding gas feed requirements and power subsystem, which results in a truly "propellant-less" tether system for such basic applications as de-orbiting low earth orbit satellites.

  19. Magnetostructural coupling in spinel oxides

    NASA Astrophysics Data System (ADS)

    Kemei, Moureen

    2015-03-01

    Spinels oxides are of great interest functionally as multiferroic, battery, and magnetic materials as well as fundamentally because they exhibit novel spin, structural, and orbital ground states. Competing interactions are at the heart of novel functional behavior in spinels. Here, we explore the intricate landscape of spin, lattice, and orbital interactions in magnetic spinels by employing variable-temperature high-resolution synchrotron x-ray powder diffraction, total neutron scattering, magnetic susceptibility, dielectric, and heat capacity measurements. We show that the onset of long-range magnetic interactions often gives rise to lattice distortions. Our work illustrates that the spinels NiCr2O4, CuCr2O4,andMn3O4, which are tetragonal at room temperature due to Jahn-Teller ordering, undergo further spin-driven structural distortions at the onset of long-range ferrimagnetic order. We have also studied the complete structural description of the ground states of several spinels including the geometrically frustrated spinels ZnCr2O4andMgCr2O4. The detailed spin-lattice studies of spinel oxides presented here illustrate the prevalence of structural phase coexistence when magnetostructural changes occur below 50 K. The new understanding of structural ground states in spinel oxides will guide the design of structure-property relationships in these materials. Broadly, this work highlights the importance of variable-temperature high-resolution synchrotron x-ray diffraction in understanding phase transitions in functional materials. Schlumberger Foundation Faculty for the Future fellowship, MRL Facilities funded by the NSF under Award No. DMR 1121053, and the Advanced Photon Source supported by the DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

  20. Introduction of two lithiooxycarbonyl groups enhances cyclability of lithium batteries with organic cathode materials

    NASA Astrophysics Data System (ADS)

    Shimizu, Akihiro; Kuramoto, Hiroki; Tsujii, Yutaka; Nokami, Toshiki; Inatomi, Yuu; Hojo, Nobuhiko; Suzuki, Hirotetsu; Yoshida, Jun-ichi

    2014-08-01

    To increase the cyclability of lithium batteries using organic cathode materials of low molecular weights, two lithiooxycarbonyl (-CO2Li) groups was introduced to p- and o-quinones. The introduction of two -CO2Li groups does not strongly affect the redox potentials of quinones. Lithium batteries using p- and o-quinones with two -CO2Li groups as cathode materials exhibit excellent cyclability compared to their parent quinones. In particular, pyrene-4,5,9,10-tetraone having two lithiooxycarbonyl groups (LCPYT) exhibited high energy density, high cyclability, and fast charge ability. These results indicate that introduction of two lithiooxycarbonyl groups to quinones serves as a simple and effective way to decrease the solubility of various quinones in electrolyte solutions without significant decrease in the voltage.

  1. Graphene Modified LiFePO4 Cathode Materials for High Power Lithium ion Batteries

    SciTech Connect

    Zhou, X.; Wang, F.; Zhu, Y.; Liu, Z.

    2011-01-24

    Graphene-modified LiFePO{sub 4} composite has been developed as a Li-ion battery cathode material with excellent high-rate capability and cycling stability. The composite was prepared with LiFePO{sub 4} nanoparticles and graphene oxide nanosheets by spray-drying and annealing processes. The LiFePO{sub 4} primary nanoparticles embedded in micro-sized spherical secondary particles were wrapped homogeneously and loosely with a graphene 3D network. Such a special nanostructure facilitated electron migration throughout the secondary particles, while the presence of abundant voids between the LiFePO{sub 4} nanoparticles and graphene sheets was beneficial for Li{sup +} diffusion. The composite cathode material could deliver a capacity of 70 mAh g{sup -1} at 60C discharge rate and showed a capacity decay rate of <15% when cycled under 10C charging and 20C discharging for 1000 times.

  2. Layered cathode materials for lithium ion rechargeable batteries

    DOEpatents

    Kang, Sun-Ho; Amine, Khalil

    2007-04-17

    A number of materials with the composition Li.sub.1+xNi.sub..alpha.Mn.sub..beta.Co.sub..gamma.M'.sub..delta.O.sub.2-- zF.sub.z (M'=Mg,Zn,Al,Ga,B,Zr,Ti) for use with rechargeable batteries, wherein x is between about 0 and 0.3, .alpha. is between about 0.2 and 0.6, .beta. is between about 0.2 and 0.6, .gamma. is between about 0 and 0.3, .delta. is between about 0 and 0.15, and z is between about 0 and 0.2. Adding the above metal and fluorine dopants affects capacity, impedance, and stability of the layered oxide structure during electrochemical cycling.

  3. Sulfur-carbon nanocomposites and their application as cathode materials in lithium-sulfur batteries

    SciTech Connect

    Liang, Chengdu; Dudney, Nancy J; Howe, Jane Y

    2015-05-05

    The invention is directed in a first aspect to a sulfur-carbon composite material comprising: (i) a bimodal porous carbon component containing therein a first mode of pores which are mesopores, and a second mode of pores which are micropores; and (ii) elemental sulfur contained in at least a portion of said micropores. The invention is also directed to the aforesaid sulfur-carbon composite as a layer on a current collector material; a lithium ion battery containing the sulfur-carbon composite in a cathode therein; as well as a method for preparing the sulfur-composite material.

  4. Sulfur-based composite cathode materials for high-energy rechargeable lithium batteries.

    PubMed

    Wang, Jiulin; He, Yu-Shi; Yang, Jun

    2015-01-21

    There is currently an urgent demand for highly efficient energy storage and conversion systems. Due to its high theoretical energy density, low cost, and environmental compatibility, the lithium sulfur (Li-S) battery has become a typical representative of the next generation of electrochemical power sources. Various approaches have been explored to design and prepare sulfur cathode materials to enhance their electrochemical performance. This Research News article summarizes and compares different sulfur materials for Li-S batteries and particularly focuses on the fine structures, electrochemical performance, and electrode reaction mechanisms of pyrolyzed polyacrylo-nitrile sulfur (pPAN@S) and microporous-carbon/small-sulfur composite materials. PMID:25256595

  5. Selective Recovery of Lithium from Cathode Materials of Spent Lithium Ion Battery

    NASA Astrophysics Data System (ADS)

    Higuchi, Akitoshi; Ankei, Naoki; Nishihama, Syouhei; Yoshizuka, Kazuharu

    2016-07-01

    Selective recovery of lithium from four kinds of cathode materials, manganese-type, cobalt-type, nickel-type, and ternary-type, of spent lithium ion battery was investigated. In all cathode materials, leaching of lithium was improved by adding sodium persulfate (Na2S2O8) as an oxidant in the leaching solution, while the leaching of other metal ions (manganese, cobalt, and nickel) was significantly suppressed. Optimum leaching conditions, such as pH, temperature, amount of Na2S2O8, and solid/liquid ratio, for the selective leaching of lithium were determined for all cathode materials. Recovery of lithium from the leachate as lithium carbonate (Li2CO3) was then successfully achieved by adding sodium carbonate (Na2CO3) to the leachate. Optimum recovery conditions, such as pH, temperature, and amount of Na2CO3, for the recovery of lithium as Li2CO3 were determined for all cases. Purification of Li2CO3 was achieved by lixiviation in all systems, with purities of the Li2CO3 higher than 99.4%, which is almost satisfactory for the battery-grade purity of lithium.

  6. New High Capacity Cathode Materials for Rechargeable Li-ion Batteries: Vanadate-Borate Glasses

    NASA Astrophysics Data System (ADS)

    Afyon, Semih; Krumeich, Frank; Mensing, Christian; Borgschulte, Andreas; Nesper, Reinhard

    2014-11-01

    V2O5 based materials are attractive cathode alternatives due to the many oxidation state switches of vanadium bringing about a high theoretical specific capacity. However, significant capacity losses are eminent for crystalline V2O5 phases related to the irreversible phase transformations and/or vanadium dissolution starting from the first discharge cycle. These problems can be circumvented if amorphous or glassy vanadium oxide phases are employed. Here, we demonstrate vanadate-borate glasses as high capacity cathode materials for rechargeable Li-ion batteries for the first time. The composite electrodes of V2O5 - LiBO2 glass with reduced graphite oxide (RGO) deliver specific energies around 1000 Wh/kg and retain high specific capacities in the range of ~ 300 mAh/g for the first 100 cycles. V2O5 - LiBO2 glasses are considered as promising cathode materials for rechargeable Li-ion batteries fabricated through rather simple and cost-efficient methods.

  7. New high capacity cathode materials for rechargeable Li-ion batteries: vanadate-borate glasses.

    PubMed

    Afyon, Semih; Krumeich, Frank; Mensing, Christian; Borgschulte, Andreas; Nesper, Reinhard

    2014-01-01

    V2O5 based materials are attractive cathode alternatives due to the many oxidation state switches of vanadium bringing about a high theoretical specific capacity. However, significant capacity losses are eminent for crystalline V2O5 phases related to the irreversible phase transformations and/or vanadium dissolution starting from the first discharge cycle. These problems can be circumvented if amorphous or glassy vanadium oxide phases are employed. Here, we demonstrate vanadate-borate glasses as high capacity cathode materials for rechargeable Li-ion batteries for the first time. The composite electrodes of V2O5 - LiBO(2) glass with reduced graphite oxide (RGO) deliver specific energies around 1000 Wh/kg and retain high specific capacities in the range of ~ 300 mAh/g for the first 100 cycles. V2O5 - LiBO(2) glasses are considered as promising cathode materials for rechargeable Li-ion batteries fabricated through rather simple and cost-efficient methods. PMID:25408200

  8. Preparation and electrochemical performance of sulfur-alumina cathode material for lithium-sulfur batteries

    SciTech Connect

    Dong, Kang; Wang, Shengping; Zhang, Hanyu; Wu, Jinping

    2013-06-01

    Highlights: ► Micron-sized alumina was synthesized as adsorbent for lithium-sulfur batteries. ► Sulfur-alumina material was synthesized via crystallizing nucleation. ► The Al{sub 2}O{sub 3} can provide surface area for the deposition of Li{sub 2}S and Li{sub 2}S{sub 2}. ► The discharge capacity of the battery is improved during the first several cycles. - Abstract: Nano-sized sulfur particles exhibiting good adhesion with conducting acetylene black and alumina composite materials were synthesized by means of an evaporated solvent and a concentrated crystallization method for use as the cathodes of lithium-sulfur batteries. The composites were characterized and examined by X-ray diffraction, environmental scanning electron microscopy and electrochemical methods, such as cyclic voltammetry, electrical impedance spectroscopy and charge–discharge tests. Micron-sized flaky alumina was employed as an adsorbent for the cathode material. The initial discharge capacity of the cathode with the added alumina was 1171 mAh g{sup −1}, and the remaining capacity was 585 mAh g{sup −1} after 50 cycles at 0.25 mA cm{sup −2}. Compared with bare sulfur electrodes, the electrodes containing alumina showed an obviously superior cycle performance, confirming that alumina can contribute to reducing the dissolution of polysulfides into electrolytes during the sulfur charge–discharge process.

  9. Comparison of Nonprecious Metal Cathode Materials for Methane Production by Electromethanogenesis.

    PubMed

    Siegert, Michael; Yates, Matthew D; Call, Douglas F; Zhu, Xiuping; Spormann, Alfred; Logan, Bruce E

    2014-04-01

    In methanogenic microbial electrolysis cells (MMCs), CO2 is reduced to methane using a methanogenic biofilm on the cathode by either direct electron transfer or evolved hydrogen. To optimize methane generation, we examined several cathode materials: plain graphite blocks, graphite blocks coated with carbon black or carbon black containing metals (platinum, stainless steel or nickel) or insoluble minerals (ferrihydrite, magnetite, iron sulfide, or molybdenum disulfide), and carbon fiber brushes. Assuming a stoichiometric ratio of hydrogen (abiotic):methane (biotic) of 4:1, methane production with platinum could be explained solely by hydrogen production. For most other materials, however, abiotic hydrogen production rates were insufficient to explain methane production. At -600 mV, platinum on carbon black had the highest abiotic hydrogen gas formation rate (1600 ± 200 nmol cm(-3) d(-1)) and the highest biotic methane production rate (250 ± 90 nmol cm(-3) d(-1)). At -550 mV, plain graphite (76 nmol cm(-3) d(-1)) performed similarly to platinum (73 nmol cm(-3) d(-1)). Coulombic recoveries, based on the measured current and evolved gas, were initially greater than 100% for all materials except platinum, suggesting that cathodic corrosion also contributed to electromethanogenic gas production. PMID:24741468

  10. Comparison of Nonprecious Metal Cathode Materials for Methane Production by Electromethanogenesis

    PubMed Central

    2014-01-01

    In methanogenic microbial electrolysis cells (MMCs), CO2 is reduced to methane using a methanogenic biofilm on the cathode by either direct electron transfer or evolved hydrogen. To optimize methane generation, we examined several cathode materials: plain graphite blocks, graphite blocks coated with carbon black or carbon black containing metals (platinum, stainless steel or nickel) or insoluble minerals (ferrihydrite, magnetite, iron sulfide, or molybdenum disulfide), and carbon fiber brushes. Assuming a stoichiometric ratio of hydrogen (abiotic):methane (biotic) of 4:1, methane production with platinum could be explained solely by hydrogen production. For most other materials, however, abiotic hydrogen production rates were insufficient to explain methane production. At −600 mV, platinum on carbon black had the highest abiotic hydrogen gas formation rate (1600 ± 200 nmol cm–3 d–1) and the highest biotic methane production rate (250 ± 90 nmol cm–3 d–1). At −550 mV, plain graphite (76 nmol cm–3 d–1) performed similarly to platinum (73 nmol cm–3 d–1). Coulombic recoveries, based on the measured current and evolved gas, were initially greater than 100% for all materials except platinum, suggesting that cathodic corrosion also contributed to electromethanogenic gas production. PMID:24741468

  11. Spinel materials for Li-ion batteries: new insights obtained by operando neutron and synchrotron X-ray diffraction.

    PubMed

    Bianchini, Matteo; Fauth, François; Suard, Emmanuelle; Leriche, Jean Bernard; Masquelier, Christian; Croguennec, Laurence

    2015-12-01

    In the last few decades Li-ion batteries changed the way we store energy, becoming a key element of our everyday life. Their continuous improvement is tightly bound to the understanding of lithium (de)intercalation phenomena in electrode materials. Here we address the use of operando diffraction techniques to understand these mechanisms. We focus on powerful probes such as neutrons and synchrotron X-ray radiation, which have become increasingly familiar to the electrochemical community. After discussing the general benefits (and drawbacks) of these characterization techniques and the work of customization required to adapt standard electrochemical cells to an operando diffraction experiment, we highlight several very recent results. We concentrate on important electrode materials such as the spinels Li1 + xMn2 - xO4 (0 ≤ x ≤ 0.10) and LiNi0.4Mn1.6O4. Thorough investigations led by operando neutron powder diffraction demonstrated that neutrons are highly sensitive to structural parameters that cannot be captured by other means (for example, atomic Debye-Waller factors and lithium site occupancy). Synchrotron radiation X-ray powder diffraction reveals how LiMn2O4 is subject to irreversibility upon the first electrochemical cycle, resulting in severe Bragg peak broadening. Even more interestingly, we show for the first time an ordering scheme of the elusive composition Li0.5Mn2O4, through the coexistence of Mn(3+):Mn(4+) 1:3 cation ordering and lithium/vacancy ordering. More accurately written as Li0.5Mn(3+)0.5Mn(4+)1.5O4, this intermediate phase loses the Fd\\overline 3m symmetry, to be correctly described in the P213 space group. PMID:26634725

  12. Zero-Strain Na2FeSiO4 as Novel Cathode Material for Sodium-Ion Batteries.

    PubMed

    Li, Shouding; Guo, Jianghuai; Ye, Zhuo; Zhao, Xin; Wu, Shunqing; Mi, Jin-Xiao; Wang, Cai-Zhuang; Gong, Zhengliang; McDonald, Matthew J; Zhu, Zizhong; Ho, Kai-Ming; Yang, Yong

    2016-07-13

    A new cubic polymorph of sodium iron silicate, Na2FeSiO4, is reported for the first time as a cathode material for Na-ion batteries. It adopts an unprecedented cubic rigid tetrahedral open framework structure, i.e., F4̅3m, leading to a polyanion cathode material without apparent cell volume change during the charge/discharge processes. This cathode shows a reversible capacity of 106 mAh g(-1) and a capacity retention of 96% at 5 mA g(-1) after 20 cycles. PMID:27305627

  13. XAFS Study on Deterioration of Cathode Materials for Lithium-Ion Batteries

    SciTech Connect

    Nonaka, Takamasa; Okuda, Chikaaki; Kondo, Yasuhito; Seno, Yoshiki; Ukyo, Yoshio

    2007-02-02

    LiNi0.8CO0.15Al0.05O2, being one of the promising cathode materials for lithium-ion batteries, shows a distinct capacity fading after charge/discharge cycling and/or storage at high temperatures. The origin of these deteriorations has been explored by investigating the electronic and structural changes of the cathode material using X-ray absorption spectroscopy. Ni K-edge XAFS measurements were performed in two different modes: surface-sensitive conversion electron yield (CEY) mode and bulk-sensitive transmission mode. The Ni K-edge XANES showed that, after the cycle and aging tests, the Ni valences at the near-surface of the cathode particles became much lower than those in bulk. Whereas, the EXAFS showed that the bulk and surface-averaged Ni-O bond distances remained unchanged after the tests. These electronic and structural changes which occur prominently at near-surface are probably the main cause of the battery deterioration phenomenon.

  14. Electricity generation and bivalent copper reduction as a function of operation time and cathode electrode material in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Wu, Dan; Huang, Liping; Quan, Xie; Li Puma, Gianluca

    2016-03-01

    The performance of carbon rod (CR), titanium sheet (TS), stainless steel woven mesh (SSM) and copper sheet (CS) cathode materials are investigated in microbial fuel cells (MFCs) for simultaneous electricity generation and Cu(II) reduction, in multiple batch cycle operations. After 12 cycles, the MFC with CR exhibits 55% reduction in the maximum power density and 76% increase in Cu(II) removal. In contrast, the TS and SSM cathodes at cycle 12 show maximum power densities of 1.7 (TS) and 3.4 (SSM) times, and Cu(II) removal of 1.2 (TS) and 1.3 (SSM) times higher than those observed during the first cycle. Diffusional resistance in the TS and SSM cathodes is found to appreciably decrease over time due to the copper deposition. In contrast to CR, TS and SSM, the cathode made with CS is heavily corroded in the first cycle, exhibiting significant reduction in both the maximum power density and Cu(II) removal at cycle 2, after which the performance stabilizes. These results demonstrate that the initial deposition of copper on the cathodes of MFCs is crucial for efficient and continuous Cu(II) reduction and electricity generation over prolonged time. This effect is closely associated with the nature of the cathode material. Among the materials examined, the SSM is the most effective and inexpensive cathode for practical use in MFCs.

  15. Is alpha-V2O5 a cathode material for Mg insertion batteries?

    NASA Astrophysics Data System (ADS)

    Sa, Niya; Wang, Hao; Proffit, Danielle L.; Lipson, Albert L.; Key, Baris; Liu, Miao; Feng, Zhenxing; Fister, Timothy T.; Ren, Yang; Sun, Cheng-Jun; Vaughey, John T.; Fenter, Paul A.; Persson, Kristin A.; Burrell, Anthony K.

    2016-08-01

    When designing a high energy density battery, one of the critical features is a high voltage, high capacity cathode material. In the development of Mg batteries, oxide cathodes that can reversibly intercalate Mg, while at the same time being compatible with an electrolyte that can deposit Mg reversibly are rare. Herein, we report the compatibility of Mg anodes with α-V2O5 by employing magnesium bis(trifluoromethane sulfonyl)imide in diglyme electrolytes at very low water levels. Electrolytes that contain a high water level do not reversibly deposit Mg, but interestingly these electrolytes appear to enable much higher capacities for an α-V2O5 cathode. Solid state NMR indicates that the major source of the higher capacity in high water content electrolytes originates from reversible proton insertion. In contrast, we found that lowering the water level of the magnesium bis(trifluoromethane sulfonyl)imide in diglyme electrolyte is critical to achieve reversible Mg deposition and direct evidence for reversible Mg intercalation is shown. Findings we report here elucidate the role of proton intercalation in water-containing electrolytes and clarify numerous conflicting reports of Mg insertion into α-V2O5.

  16. Synthesis, strctural and electrochemical characterizations of lithium- manganese- rich composite cathode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Dapeng

    The electrification trend for transportation systems requires alternative cathode materials to LiCoO2 with improved safety, lowered cost and extended cycle life. Lithium- manganese- rich composite cathode materials, which can be presented in a two component notation as xLi2MnO3·(1-x)LiMO 2, (M= Ni, Co or Mn) have superior cost and energy density advantages. These cathode materials have shown success in laboratory scale experiments, but are still facing challenges such as voltage fade, moderate rate capacity and tap density for commercialization. The synthesis of precursors with high packing density and suitable physical properties is critical to achieve high energy density as well as the other acceptable electrochemical performance for the next generation lithium ion batteries. The aim of this study is to correlate the electrochemical properties of materials to their structural, morphological, and physical properties by coordinating the science of synthesis with the science of function, in order to enable the use of these compounds in vehicle technologies. Three different precursors including carbonate, hydroxide and oxalate were synthesized by co-precipitation reactions using continuous stirred tank reactor (CSTR) under various conditions. Research focused on areas such as nucleation and growth mechanisms, synthesis optimizations, and intrinsic limitations of each co-precipitation method. A combination of techniques such as PSA, BET, SEM, EDX FIB, TEM, Raman, FTIR, TGA-DSC, XRD, and ICP-MS, as well as electrochemical test methods such as cycling, CV, EIS and HPPC tests were used in correlation with each other in order to deepen our understanding to these materials. Related topics such as the composite structure formation process during the solid state reaction, lithium and nickel content effects on the cathode properties were also discussed. Additionally, the side reactions between the active materials and electrolyte as a result of the high charge potential were

  17. Rational design of novel cathode materials in solid oxide fuel cells using first-principles simulations

    NASA Astrophysics Data System (ADS)

    Choi, YongMan; Lin, M. C.; Liu, Meilin

    The search for clean and renewable sources of energy represents one of the most vital challenges facing us today. Solid oxide fuel cells (SOFCs) are among the most promising technologies for a clean and secure energy future due to their high energy efficiency and excellent fuel flexibility (e.g., direct utilization of hydrocarbons or renewable fuels). To make SOFCs economically competitive, however, development of new materials for low-temperature operation is essential. Here we report our results on a computational study to achieve rational design of SOFC cathodes with fast oxygen reduction kinetics and rapid ionic transport. Results suggest that surface catalytic properties are strongly correlated with the bulk transport properties in several material systems with the formula of La 0.5Sr 0.5BO 2.75 (where B = Cr, Mn, Fe, or Co). The predictions seem to agree qualitatively with available experimental results on these materials. This computational screening technique may guide us to search for high-efficiency cathode materials for a new generation of SOFCs.

  18. Metal segregation in hierarchically structured cathode materials for high-energy lithium batteries

    DOE PAGESBeta

    Lin, Feng; Xin, Huolin L.; Nordlund, Dennis; Li, Yuyi; Quan, Matthew K.; Cheng, Lei; Weng, Tsu -Chien; Liu, Yijin; Doeff, Marca M.

    2016-01-11

    Controlling surface and interfacial properties of battery materials is key to improving performance in rechargeable Li-ion devices. Surface reconstruction from a layered to a rock salt structure in metal oxide cathode materials is commonly observed and results in poor high-voltage cycling performance, impeding attempts to improve energy density. Hierarchically structured LiNi0.4Mn0.4Co0.2O2 (NMC-442) spherical powders, made by spray pyrolysis, exhibit local elemental distribution gradients that deviate from the global NMC-442 composition; specifically, they are Ni-rich and Mn-poor at particle surfaces. These materials demonstrate improved Coulombic efficiencies, discharge capacities, and high-voltage capacity retention in lithium half-cell configurations. The subject powders show superiormore » resistance against surface reconstruction due to the tailored surface chemistry, compared to conventional NMC-442 materials. This paves the way towards the development of a new generation of robust and stable high-energy NMC cathodes for Li-ion batteries.« less

  19. Highly stable TiO2 coated Li2MnO3 cathode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Kim, Si-Jin; Kim, Min-Cheol; Kwak, Da-Hee; Kim, Da-Mi; Lee, Gyu-Ho; Choe, Hui-Seon; Park, Kyung-Won

    2016-02-01

    Many efforts have been made to improve the electrochemical performance of Li-rich cathode materials such as metal ion doping, surface modification, and fabricating nanostructured materials. Here, we demonstrate Li2MnO3 (denoted as OLO) cathode materials coated with TiO2 (OLO@ TiO2) for high-performance LIBs. The ratio of layered Li2MnO3 to anatase TiO2 as well as the shell thickness in the OLO@TiO2 cathodes were controlled by increasing the addition of titanium butoxide. The structure and chemical states for TiO2 coated OLO electrodes were confirmed using field-emission scanning electron microscopy, field-emission transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. To evaluate the performance of the electrodes for LIBs, charge/discharge curves, cycling performance, cyclic voltammograms, and Nyquist plots of the as-prepare cathode materials were obtained using lithium coin cells. In particular, since the TiO2 coating layer in OLO@TiO2 could stabilize the interface between the cathode and electrolyte, OLO@TiO2 exhibited high specific capacity, improved high rate cycling performance, and excellent cycle life due to the low interface resistance and high diffusion coefficient of lithium ion, compared with the uncoated OLO cathode.

  20. Effect of the cathode material on the removal of nitrates by electrolysis in non-chloride media.

    PubMed

    Lacasa, Engracia; Cañizares, Pablo; Llanos, Javier; Rodrigo, Manuel A

    2012-04-30

    In this work, the effect of the cathode material (conductive diamond, stainless steel, silicon carbide, graphite or lead) and the current density (150-1400 A m(-2)) on the removal of nitrates from aqueous solutions is studied by electrolysis in non-divided electrochemical cells equipped with conductive diamond anodes, using sodium sulphate as the electrolyte. The results show that the cathode material very strongly influences both the process performance and the product distribution. The main products obtained are gaseous nitrogen (NO, N(2)O and NO(2)) and ammonium ions. Nitrate removal follows first order kinetics, which indicates that the electrolysis process is controlled by mass transfer. Furthermore, the stainless steel and graphite cathodes show a great selectivity towards the production of ammonium ions, whereas the silicon carbide cathode leads to the highest formation of gaseous nitrogen, which production is promoted at low current densities. PMID:22387000

  1. Load displacement and high speed nanoindentation data set at different state of charge (SoC) for spinel Li x Mn2O4 cathodes.

    PubMed

    Mughal, Muhammad Zeeshan; Moscatelli, Riccardo; Sebastiani, Marco

    2016-09-01

    Novel high speed nanoindentation data is reported for 0% and 100% state of charge (SoC) for the spinal Li x Mn2O4 material. The article also includes the load/displacement data for different SoC highlighting the displacement bursts corresponding to the pillar splitting for fracture toughness evaluation. For more details, please see the article; Mughal et al. (2016) [1]. PMID:27331088

  2. Surface structure evolution of cathode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Yingchun, Lyu; Yali, Liu; Lin, Gu

    2016-01-01

    Lithium ion batteries are important electrochemical energy storage devices for consumer electronics and the most promising candidates for electrical/hybrid vehicles. The surface chemistry influences the performance of the batteries significantly. In this short review, the evolution of the surface structure of the cathode materials at different states of the pristine, storage and electrochemical reactions are summarized. The main methods for the surface modification are also introduced. Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB07030200) and the National Basic Research Program of China (Grant Nos. 2014CB921002 and 2012CB921702).

  3. Li2C2, a High-Capacity Cathode Material for Lithium Ion Batteries.

    PubMed

    Tian, Na; Gao, Yurui; Li, Yurong; Wang, Zhaoxiang; Song, Xiaoyan; Chen, Liquan

    2016-01-11

    As a typical alkaline earth metal carbide, lithium carbide (Li2C2) has the highest theoretical specific capacity (1400 mA h g(-1)) among all the reported lithium-containing cathode materials for lithium ion batteries. Herein, the feasibility of using Li2C2 as a cathode material was studied. The results show that at least half of the lithium can be extracted from Li2C2 and the reversible specific capacity reaches 700 mA h g(-1). The C≡C bond tends to rotate to form C4 (C≡C⋅⋅⋅C≡C) chains during lithium extraction, as indicated with the first-principles molecular dynamics (FPMD) simulation. The low electronic and ionic conductivity are believed to be responsible for the potential gap between charge and discharge, as is supported with density functional theory (DFT) calculations and Arrhenius fitting results. These findings illustrate the feasibility to use the alkali and alkaline earth metal carbides as high-capacity electrode materials for secondary batteries. PMID:26609636

  4. Covalently Functionalized Graphene by Radical Polymers for Graphene-Based High-Performance Cathode Materials.

    PubMed

    Li, Yongjun; Jian, Zukai; Lang, Meidong; Zhang, Chunming; Huang, Xiaoyu

    2016-07-13

    Polymer-functionalized graphene sheets play an important role in graphene-containing composite materials. Herein, functionalized graphene sheets covalently linked with radical polymer, graphene-graft-poly(2,2,6,6-tetramethylpiperidin-1-oxyl-4-yl methacrylate) (G-g-PTMA), were prepared via surface-initiated atom transfer radical polymerization (SI-ATRP). A composite cathode with G-g-PTMA as major active material and reduced graphene oxide (RGO) as conductive additive was fabricated via a simple dispersing-depositing process, and this composite cathode exhibited a relatively high specific capacity up to 466 mAh g(-1) based on the mass of PTMA, which is much higher than the theoretical capacity of PTMA. This extraordinary electrochemical performance is attributed to the fast one-electron redox reaction of G-g-PTMA and surface Faradaic reaction of RGO boosted by G-g-PTMA, which suggested that G-g-PTMA sheets play a dual role in the composite materials, that is, on the one hand provided the fast one-electron redox reaction of PTMA and on the other hand worked as nanofiller for facilitating the surface Faradaic reaction-based lithium storage of RGO. PMID:27328986

  5. Investigation of the removing process of cathode material in micro-EDM using an atomistic-continuum model

    NASA Astrophysics Data System (ADS)

    Guo, Jianwen; Zhang, Guojun; Huang, Yu; Ming, Wuyi; Liu, Min; Huang, Hao

    2014-10-01

    In micro-electrical discharge machining (micro-EDM), the discharge duration is ultra-short, and both the electric action and the thermal action by the discharge channel play important roles in the removing process of cathode material. However, in most researches on the machining mechanism of micro-EDM, only the thermal action is concerned. In this article, a combined atomistic-continuum modeling method in which the two-temperature model and the molecular dynamics simulation model are integrated is used to construct the simulation model for cathode in single-discharge micro-EDM process. With this simulation model, removing processes of Cu cathode material in micro-EDM under pure thermal action, pure electric action and the combination of them are investigated in a simulative way. By analyzing evolutions of temperature, stress and micro-structure of material as well as the dynamical behaviors of material in the removing process, mechanisms of the cathode material removal and crater formation are revealed. In addition, the removing process of cathode material under the combination of pure thermal action and pure electric action is compared with those under the two pure actions respectively to analyze the interactive effect between the thermal action and the electric action.

  6. In Situ X-ray Diffraction Studies of Cathode Materials in Lithium Batteries

    SciTech Connect

    Yang, X. Q.; Sun, X.; McBreen, J.; Mukerjee, S.; Gao, Yuan; Yakovleva, M. V.; Xing, X. K.; Daroux, M. L.

    1998-11-01

    There is an increasing interest in lithiated transition metal oxides because of their use as cathodes in lithium batteries. LiCoO{sub 2}, LiNiO{sub 2} and LiMn{sub 2}O{sub 4} are the three most widely used and studied materials, At present, although it is relative expensive and toxic, LiCoO{sub 2} is the material of choice in commercial lithium ion batteries because of its ease of manufacture, better thermal stability and cycle life. However, the potential use of lithium ion batteries with larger capacity for power tools and electric vehicles in the future will demand new cathode materials with higher energy density, lower cost and better thermal stability. LiNiO{sub 2} is isostructural with LiCoO{sub 2}. It offers lower cost and high energy density than LiCoO{sub 2}. However, it has much poorer thermal stability than LiCoO{sub 2}, in the charged (delithiated) state. Co, Al, and other elements have been used to partially replace Ni in LiNiO{sub 2} system in order to increase the thermal stability. LiMn{sub 2}O{sub 4} has the highest thermal stability and lowest cost and toxicity. However, the low energy density and poor cycle life at elevated temperature are the major obstacles for this material. In order to develop safer, cheaper, and better performance cathode materials, the in-depth understanding of the relationships between the thermal stability and structure, performance and structure are very important. The performance here includes energy density and cycle life of the cathode materials. X-ray diffraction (XRD) is one of the most powerful tools to study these relationships. The pioneer ex situ XRD work on cathode materials for lithium batteries was done by Ohzuku. His XRD studies on LiMn{sub 2}O{sub 4}, LiCoO{sub 2}, LiNiO{sub 2}, LiNi{sub 0.5}Co{sub 0.5}O{sub 2}, and LiAl{sub x}Ni{sub 1-x}O{sub 2} cathodes at different states of charge have provided important guidelines for the development of these new materials. However, the kinetic nature of the battery

  7. Development and characterization of novel cathode materials for molten carbonate fuel cell

    NASA Astrophysics Data System (ADS)

    Giorgi, L.; Carewska, M.; Patriarca, M.; Scaccia, S.; Simonetti, E.; Dibartolomeo, A.

    1994-04-01

    In the development of molten carbonate fuel cell (MCFC) technology, the corrosion of materials is a serious problem for long-term operation. Indeed, slow dissolution of lithiated-NiO cathode in molten carbonates is the main obstacle for the commercialization of MCFCs. In the search of new, more stable, cathode materials, alternative compounds such as LiFeO2, Li2MnO3, and La(1-x)Sr(x)CoO3 are presently under investigation to replace the currently used lithiated-NiO. The aim of the present work was to investigate the possibility to produce electrode based on LiCoO2, a promising cathode material. At first, Li(x)CoO2 powder samples (0.8 less than x less than 1.1) were made by thermal decomposition of carbonate precursors in air. The synthesis processes were monitored by thermal analysis (TGA, DTA). The calcined and sintered powder samples were characterized by x ray diffraction (XRD) andatomic absorption spectrophotometry (F-AAS). A single phase was detected in all the samples, without any change in crystal structure as a function of lithium content. Porous sintered electrodes were prepared starting from lithium cobaltite powders mixed with different pore-formers by cold pressing and sintering. A bimodal pore-size distribution with a mean pore diameter in the range of 0.15 to 8 micron, a surface area of 2 to 12 sq m/g and a porosity of 10 to 65%, determined by the Hg-intrusion technique, were observed in all the materials. Conductivity measurements were carried out in the temperature range of 500-700 C, in air. The influence of the deviations from stoichiometry on the electronic properties was determined, the conductivity value of the stoichiometric compound being the lowest. A linear relationship between the electronic conductivity and the sample porosity was found. Solubility testing of the materials was carried out to evaluate their chemical stability in the electrolyte. The sampling method (F-AAS) and square wave voltammetry (SWV) were used to determine the

  8. Strain-induced tuning of surface energy, electron conductivity, and reduction drive in spinel LiMn2O4 cathodes

    NASA Astrophysics Data System (ADS)

    Scivett, Ivan; Teobaldi, Gilberto

    LiMn2O4 (LMO) implementation in rechargeable Li-ion batteries (LIBs) for stationary storage is hampered by the limited lifetime of the material and its interfaces, starting from the Solid Electrolyte Interphase. Recent experiments and Density Functional Theory (DFT) simulations indicate that the formation and effectiveness of the SEI on LMO are related to the surface orientation and reduction drive. In this context, we analyse the role of geometrical strain for the relative energy, magnetic ordering and the reduction drive of several LMO surfaces. DFT simulations reveal LMO surfaces to be markedly sensitive to geometrical strain. Strain lower than 10% can induce insulator-metal and ferromagnetic-antiferromagnetic transitions, alter the relative energy of LMO surfaces, and induce changes as large as 1.0 eV in the surface chemical potential, thence reduction drive. Prompted by advances in the synthesis of metal-oxide core-shell nanostructures, use of strained LMO coating as SEI-formation agent is put forward towards engineering of longer lived SEI on LMO substrates. EU FP7 project SIRBATT (Ref. 608502, end date: August 2016)

  9. Heteroaromatic organic compound with conjugated multi-carbonyl as cathode material for rechargeable lithium batteries

    PubMed Central

    Lv, Meixiang; Zhang, Fen; Wu, Yiwen; Chen, Mujuan; Yao, Chunfeng; Nan, Junmin; Shu, Dong; Zeng, Ronghua; Zeng, Heping; Chou, Shu-Lei

    2016-01-01

    The heteroaromatic organic compound, N,N’-diphenyl-1,4,5,8-naphthalenetetra- carboxylic diimide (DP-NTCDI-250) as the cathode material of lithium batteries is prepared through a simple one-pot N-acylation reaction of 1,4,5,8-naphthalenetetra-carboxylic dianhydride (NTCDA) with phenylamine (PA) in DMF solution followed by heat treatment in 250 °C. The as prepared sample is characterized by the combination of elemental analysis, NMR, FT-IR, TGA, XRD, SEM and TEM. The electrochemical measurements show that DP-NTCDI-250 can deliver an initial discharge capacity of 170 mAh g−1 at the current density of 25 mA g−1. The capacity of 119 mAh g−1 can be retained after 100 cycles. Even at the high current density of 500 mA g−1, its capacity still reaches 105 mAh g−1, indicating its high rate capability. Therefore, the as-prepared DP-NTCDI-250 could be a promising candidate as low cost cathode materials for lithium batteries. PMID:27064938

  10. Recycling of spent lithium-ion battery cathode materials by ammoniacal leaching.

    PubMed

    Ku, Heesuk; Jung, Yeojin; Jo, Minsang; Park, Sanghyuk; Kim, Sookyung; Yang, Donghyo; Rhee, Kangin; An, Eung-Mo; Sohn, Jeongsoo; Kwon, Kyungjung

    2016-08-01

    As the production and consumption of lithium ion batteries (LIBs) increase, the recycling of spent LIBs appears inevitable from an environmental, economic and health viewpoint. The leaching behavior of Ni, Mn, Co, Al and Cu from treated cathode active materials, which are separated from a commercial LIB pack in hybrid electric vehicles, is investigated with ammoniacal leaching agents based on ammonia, ammonium carbonate and ammonium sulfite. Ammonium sulfite as a reductant is necessary to enhance leaching kinetics particularly in the ammoniacal leaching of Ni and Co. Ammonium carbonate can act as a pH buffer so that the pH of leaching solution changes little during leaching. Co and Cu can be fully leached out whereas Mn and Al are hardly leached and Ni shows a moderate leaching efficiency. It is confirmed that the cathode active materials are a composite of LiMn2O4, LiCoxMnyNizO2, Al2O3 and C while the leach residue is composed of LiNixMnyCozO2, LiMn2O4, Al2O3, MnCO3 and Mn oxides. Co recovery via the ammoniacal leaching is believed to gain a competitive edge on convenitonal acid leaching both by reducing the sodium hydroxide expense for increasing the pH of leaching solution and by removing the separation steps of Mn and Al. PMID:27060219

  11. Accelerated discovery of cathode materials with prolonged cycle life for lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Nishijima, Motoaki; Ootani, Takuya; Kamimura, Yuichi; Sueki, Toshitsugu; Esaki, Shogo; Murai, Shunsuke; Fujita, Koji; Tanaka, Katsuhisa; Ohira, Koji; Koyama, Yukinori; Tanaka, Isao

    2014-08-01

    Large-scale battery systems are essential for efficiently utilizing renewable energy power sources from solar and wind, which can generate electricity only intermittently. The use of lithium-ion batteries to store the generated energy is one solution. A long cycle life is critical for lithium-ion battery when used in these applications; this is different from portable devices which require 1,000 cycles at most. Here we demonstrate a novel co-substituted lithium iron phosphate cathode with estimated 70%-capacity retention of 25,000 cycles. This is found by exploring a wide chemical compositional space using density functional theory calculations. Relative volume change of a compound between fully lithiated and delithiated conditions is used as the descriptor for the cycle life. On the basis of the results of the screening, synthesis of selected materials is targeted. Single-phase samples with the required chemical composition are successfully made by an epoxide-mediated sol-gel method. The optimized materials show excellent cycle-life performance as lithium-ion battery cathodes.

  12. Heteroaromatic organic compound with conjugated multi-carbonyl as cathode material for rechargeable lithium batteries

    NASA Astrophysics Data System (ADS)

    Lv, Meixiang; Zhang, Fen; Wu, Yiwen; Chen, Mujuan; Yao, Chunfeng; Nan, Junmin; Shu, Dong; Zeng, Ronghua; Zeng, Heping; Chou, Shu-Lei

    2016-04-01

    The heteroaromatic organic compound, N,N’-diphenyl-1,4,5,8-naphthalenetetra- carboxylic diimide (DP-NTCDI-250) as the cathode material of lithium batteries is prepared through a simple one-pot N-acylation reaction of 1,4,5,8-naphthalenetetra-carboxylic dianhydride (NTCDA) with phenylamine (PA) in DMF solution followed by heat treatment in 250 °C. The as prepared sample is characterized by the combination of elemental analysis, NMR, FT-IR, TGA, XRD, SEM and TEM. The electrochemical measurements show that DP-NTCDI-250 can deliver an initial discharge capacity of 170 mAh g‑1 at the current density of 25 mA g‑1. The capacity of 119 mAh g‑1 can be retained after 100 cycles. Even at the high current density of 500 mA g‑1, its capacity still reaches 105 mAh g‑1, indicating its high rate capability. Therefore, the as-prepared DP-NTCDI-250 could be a promising candidate as low cost cathode materials for lithium batteries.

  13. Accelerated discovery of cathode materials with prolonged cycle life for lithium-ion battery.

    PubMed

    Nishijima, Motoaki; Ootani, Takuya; Kamimura, Yuichi; Sueki, Toshitsugu; Esaki, Shogo; Murai, Shunsuke; Fujita, Koji; Tanaka, Katsuhisa; Ohira, Koji; Koyama, Yukinori; Tanaka, Isao

    2014-01-01

    Large-scale battery systems are essential for efficiently utilizing renewable energy power sources from solar and wind, which can generate electricity only intermittently. The use of lithium-ion batteries to store the generated energy is one solution. A long cycle life is critical for lithium-ion battery when used in these applications; this is different from portable devices which require 1,000 cycles at most. Here we demonstrate a novel co-substituted lithium iron phosphate cathode with estimated 70%-capacity retention of 25,000 cycles. This is found by exploring a wide chemical compositional space using density functional theory calculations. Relative volume change of a compound between fully lithiated and delithiated conditions is used as the descriptor for the cycle life. On the basis of the results of the screening, synthesis of selected materials is targeted. Single-phase samples with the required chemical composition are successfully made by an epoxide-mediated sol-gel method. The optimized materials show excellent cycle-life performance as lithium-ion battery cathodes. PMID:25080933

  14. A mesoporous carbon–sulfur composite as cathode material for high rate lithium sulfur batteries

    SciTech Connect

    Choi, Hyunji; Zhao, Xiaohui; Kim, Dul-Sun; Ahn, Hyo-Jun; Kim, Ki-Won; Cho, Kwon-Koo; Ahn, Jou-Hyeon

    2014-10-15

    Highlights: • CMK-3 mesoporous carbon was synthesized as conducting reservoir for housing sulfur. • Sulfur/CMK-3 composites were prepared by two-stage thermal treatment. • The composite at 300 °C for 20 h shows improved electrochemical properties. - Abstract: Sulfur composite was prepared by encapsulating sulfur into CMK-3 mesoporous carbon with different heating times and then used as the cathode material for lithium sulfur batteries. Thermal treatment at 300 °C plays an important role in the sulfur encapsulation process. With 20 h of heating time, a portion of sulfur remained on the surface of carbon, whereas with 60 h of heating time, sulfur is confined deeply in the small pores of carbon that cannot be fully exploited in the redox reaction, thus causing low capacity. The S/CMK-3 composite with thermal treatment for 40 h at 300 °C contained 51.3 wt.% sulfur and delivered a high initial capacity of 1375 mA h g{sup −1} at 0.1 C. Moreover, it showed good capacity retention of 704 mA h g{sup −1} at 0.1 C and 578 mA h g{sup −1} at 2 C even after 100 cycles, which proves its potential as a cathode material for high capability lithium sulfur batteries.

  15. Heteroaromatic organic compound with conjugated multi-carbonyl as cathode material for rechargeable lithium batteries.

    PubMed

    Lv, Meixiang; Zhang, Fen; Wu, Yiwen; Chen, Mujuan; Yao, Chunfeng; Nan, Junmin; Shu, Dong; Zeng, Ronghua; Zeng, Heping; Chou, Shu-Lei

    2016-01-01

    The heteroaromatic organic compound, N,N'-diphenyl-1,4,5,8-naphthalenetetra- carboxylic diimide (DP-NTCDI-250) as the cathode material of lithium batteries is prepared through a simple one-pot N-acylation reaction of 1,4,5,8-naphthalenetetra-carboxylic dianhydride (NTCDA) with phenylamine (PA) in DMF solution followed by heat treatment in 250 °C. The as prepared sample is characterized by the combination of elemental analysis, NMR, FT-IR, TGA, XRD, SEM and TEM. The electrochemical measurements show that DP-NTCDI-250 can deliver an initial discharge capacity of 170 mAh g(-1) at the current density of 25 mA g(-1). The capacity of 119 mAh g(-1) can be retained after 100 cycles. Even at the high current density of 500 mA g(-1), its capacity still reaches 105 mAh g(-1), indicating its high rate capability. Therefore, the as-prepared DP-NTCDI-250 could be a promising candidate as low cost cathode materials for lithium batteries. PMID:27064938

  16. Performance study of commercial LiCoO 2 and spinel-based Li-ion cells

    NASA Astrophysics Data System (ADS)

    Ramadass, P.; Haran, Bala; White, Ralph; Popov, Branko N.

    The performance of Cell-Batt ® Li-ion cells and Sony 18650 cells using non-stoichiometric spinel and LiCoO 2, respectively, as positive electrode material has been studied under several modes of charging. During cycling, the cells were opened at intermittent cycles and extensive material and electrochemical characterization was done on the active material at both electrodes. Capacity fade of spinel-based Li-ion cells was attributed to structural degradation at the cathode and loss of active material at both electrodes due to electrolyte oxidation. For the Sony cells both primary (Li +) and secondary active material (LiCoO 2)/C) are lost during cycling.

  17. Surface natures of conductive carbon materials and their contributions to charge/discharge performance of cathodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Lin, H. B.; Huang, W. Z.; Rong, H. B.; Hu, J. N.; Mai, S. W.; Xing, L. D.; Xu, M. Q.; Li, X. P.; Li, W. S.

    2015-08-01

    The surface natures of five carbon materials, acetylene black, Super P, ECP600JD, KS-6 and CNTs, are compared in terms of morphology, specific surface area and activity towards electrolyte decomposition and anion insertion, and their contributions as conductive additives to cathode performance of lithium ion batteries are understood. With the characterizations from scanning electron microscopy, Brunauer-Emmett-Teller analysis and cyclic voltammetry, it's demonstrated that: (1) the morphology is granular for acetylene black, Super P and ECP600JD, flake-like for KS-6 and wire-like for CNTs; (2) ECP600JD exhibits the largest specific surface area but KS-6 has the smallest one; (3) the activity is the same for all the samples towards the electrolyte decomposition but different from each other towards anion insertion. Charge/discharge tests of LiMn2O4 and LiNi0.5Mn1.5O4 cathodes indicate that the surface natures of carbon materials play an important role in charge/discharge performance of cathodes for lithium ion batteries. ECP600JD with smallest particle size provides the largest site for electrolyte decomposition leading to the lowest coulombic efficiency, while KS-6 with a layered structure exhibits the highest activity towards anion insertion leading to the lowest charge and discharge capacity of cathode materials. These negative effects become more significant when high voltage cathode materials are used.

  18. Methods for using novel cathode and electrolyte materials for solid oxide fuel cells and ion transport membranes

    DOEpatents

    Jacobson, Allan J.; Wang, Shuangyan; Kim, Gun Tae

    2016-01-12

    Methods using novel cathode, electrolyte and oxygen separation materials operating at intermediate temperatures for use in solid oxide fuel cells and ion transport membranes include oxides with perovskite related structures and an ordered arrangement of A site cations. The materials have significantly faster oxygen kinetics than in corresponding disordered perovskites.

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

    SciTech Connect

    Browning, Katie L; Baggetto, Loic; Unocic, Raymond R; Dudney, Nancy J; Veith, Gabriel M

    2013-01-01

    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 is 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.

  20. Strategies to curb structural changes of lithium/transition metal oxide cathode materials & the changes' effects on thermal & cycling stability

    DOE PAGESBeta

    Yu, Xiqian; Hu, Enyuan; Bak, Seongmin; Zhou, Yong -Ning; Yang, Xiao -Qing

    2015-12-07

    Structural transformation behaviors of several typical oxide cathode materials during a heating process are reviewed in detail to provide in-depth understanding of the key factors governing the thermal stability of these materials. Furthermore, we also discuss applying the information about heat induced structural evolution in the study of electrochemically induced structural changes. All these discussions are expected to provide valuable insights for designing oxide cathode materials with significantly improved structural stability for safe, long-life lithium ion batteries, as the safety of lithium-ion batteries is a critical issue. As a result, it is widely accepted that the thermal instability of themore » cathodes is one of the most critical factors in thermal runaway and related safety problems.« less

  1. Strategies to curb structural changes of lithium/transition metal oxide cathode materials & the changes’ effects on thermal & cycling stability

    NASA Astrophysics Data System (ADS)

    Xiqian, Yu; Enyuan, Hu; Seongmin, Bak; Yong-Ning, Zhou; Xiao-Qing, Yang

    2016-01-01

    Structural transformation behaviors of several typical oxide cathode materials during a heating process are reviewed in detail to provide in-depth understanding of the key factors governing the thermal stability of these materials. We also discuss applying the information about heat induced structural evolution in the study of electrochemically induced structural changes. All these discussions are expected to provide valuable insights for designing oxide cathode materials with significantly improved structural stability for safe, long-life lithium ion batteries, as the safety of lithium-ion batteries is a critical issue; it is widely accepted that the thermal instability of the cathodes is one of the most critical factors in thermal runaway and related safety problems. Project supported by the U.S. Department of Energy, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies (Grant No. DE-SC0012704).

  2. Strategies to curb structural changes of lithium/transition metal oxide cathode materials & the changes' effects on thermal & cycling stability

    SciTech Connect

    Yu, Xiqian; Hu, Enyuan; Bak, Seongmin; Zhou, Yong -Ning; Yang, Xiao -Qing

    2015-12-07

    Structural transformation behaviors of several typical oxide cathode materials during a heating process are reviewed in detail to provide in-depth understanding of the key factors governing the thermal stability of these materials. Furthermore, we also discuss applying the information about heat induced structural evolution in the study of electrochemically induced structural changes. All these discussions are expected to provide valuable insights for designing oxide cathode materials with significantly improved structural stability for safe, long-life lithium ion batteries, as the safety of lithium-ion batteries is a critical issue. As a result, it is widely accepted that the thermal instability of the cathodes is one of the most critical factors in thermal runaway and related safety problems.

  3. Excellent cycling stability and superior rate capability of a graphene-amorphous FePO4 porous nanowire hybrid as a cathode material for sodium ion batteries.

    PubMed

    Yang, Gaoliang; Ding, Bing; Wang, Jie; Nie, Ping; Dou, Hui; Zhang, Xiaogang

    2016-04-28

    A porous nanowire material consisting of graphene-amorphous FePO4 was investigated as an advanced cathode material for sodium ion batteries for large-scale applications. This hybrid cathode material showed excellent cycling performance and superior rate capability, which were attributed to the porous nanowire structure and the existence of graphene. PMID:27064740

  4. Metal segregation in hierarchically structured cathode materials for high-energy lithium batteries

    NASA Astrophysics Data System (ADS)

    Lin, Feng; Nordlund, Dennis; Li, Yuyi; Quan, Matthew K.; Cheng, Lei; Weng, Tsu-Chien; Liu, Yijin; Xin, Huolin L.; Doeff, Marca M.

    2016-01-01

    In technologically important LiNi1-x-yMnxCoyO2 cathode materials, surface reconstruction from a layered to a rock-salt structure is commonly observed under a variety of operating conditions, particularly in Ni-rich compositions. This phenomenon contributes to poor high-voltage cycling performance, impeding attempts to improve the energy density by widening the potential window at which these electrodes operate. Here, using advanced nano-tomography and transmission electron microscopy techniques, we show that hierarchically structured LiNi0.4Mn0.4Co0.2O2 spherical particles, made by a simple spray pyrolysis method, exhibit local elemental segregation such that surfaces are Ni-poor and Mn-rich. The tailored surfaces result in superior resistance to surface reconstruction compared with those of conventional LiNi0.4Mn0.4Co0.2O2, as shown by soft X-ray absorption spectroscopy experiments. The improved high-voltage cycling behaviour exhibited by cells containing these cathodes demonstrates the importance of controlling LiNi1-x-yMnxCoyO2 surface chemistry for successful development of high-energy lithium ion batteries.

  5. Effect of carbon black materials on the electrochemical properties of sulfur-based composite cathode for lithium-sulfur cells.

    PubMed

    Jeong, Bo Ock; Kwon, Sang Woon; Kim, Tae Jeong; Lee, Eun Hee; Jeong, Seong Hun; Jung, Yongju

    2013-12-01

    To investigate the effect of the electrode materials on the electrochemical performance of Li-S cells, sulfur cathodes were constructed using four types of carbon blacks: Ketjenblack EC-600JD (KB-600), Printex XE-2, Cabot BP-2000, and Super-P. It was found that the electrochemical performance of sulfur cathode was strongly dependent on the type of carbon black used. In the first discharge, the sulfur cathodes containing carbon blacks with a high surface area, KB-600 (SBET = 1270 m2/g), Printex XE-2 (SBET = 950 m2/g), or Cabot BP-2000 (SBET = 1487 m2/g), showed much higher discharge capacities (>1200 mA h/g) than the sulfur cathode (710 mA h/g) with Super-P (SBET = 62 m2/g). It was observed that the sulfur cathodes with KB-600, Printex XE-2, or Cabot BP-2000, which showed very similar discharge capacities one another at a low rate of 0.2 C, exhibited significantly different electrochemical behavior (the discharge capacity and midvoltage) at a high rate of 1.0 C. In particular, the sulfur cathode with KB-600 showed an extremely high capacity (831 mA h/g) with a midvoltage of 2.07 V at a 1.0 C rate, and excellent capacity retention (79%) after 50 cycles. PMID:24266155

  6. Recent advances in first principles computational research of cathode materials for lithium-ion batteries.

    PubMed

    Meng, Ying Shirley; Arroyo-de Dompablo, M Elena

    2013-05-21

    To meet the increasing demands of energy storage, particularly for transportation applications such as plug-in hybrid electric vehicles, researchers will need to develop improved lithium-ion battery electrode materials that exhibit high energy density, high power, better safety, and longer cycle life. The acceleration of materials discovery, synthesis, and optimization will benefit from the combination of both experimental and computational methods. First principles (ab Initio) computational methods have been widely used in materials science and can play an important role in accelerating the development and optimization of new energy storage materials. These methods can prescreen previously unknown compounds and can explain complex phenomena observed with these compounds. Intercalation compounds, where Li(+) ions insert into the host structure without causing significant rearrangement of the original structure, have served as the workhorse for lithium ion rechargeable battery electrodes. Intercalation compounds will also facilitate the development of new battery chemistries such as sodium-ion batteries. During the electrochemical discharge reaction process, the intercalating species travel from the negative to the positive electrode, driving the transition metal ion in the positive electrode to a lower oxidation state, which delivers useful current. Many materials properties change as a function of the intercalating species concentrations (at different state of charge). Therefore, researchers will need to understand and control these dynamic changes to optimize the electrochemical performance of the cell. In this Account, we focus on first-principles computational investigations toward understanding, controlling, and improving the intrinsic properties of five well known high energy density Li intercalation electrode materials: layered oxides (LiMO2), spinel oxides (LiM2O4), olivine phosphates (LiMPO4), silicates-Li2MSiO4, and the tavorite-LiM(XO4)F (M = 3d

  7. Lithium iron phosphate spheres as cathode materials for high power lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Vu, Anh; Stein, Andreas

    2014-01-01

    Electrode materials composed of micrometer- and sub-micrometer-sized spherical particles are of interest for lithium ion batteries (LIBs) because spheres can be packed with higher efficiency than randomly shaped particles and achieve higher volumetric energy densities. Here we describe the synthesis of lithium iron phosphate (LFP) phases as cathode materials with spherical morphologies. Spherical Li3Fe2(PO4)3 particles and LiFePO4 spheres embedded in a carbon matrix are prepared through phase separation of precursor components in confinement. Precursors containing Li, Fe, and P sources, pre-polymerized phenol-formaldehyde (carbon source), and amphiphilic surfactant (F127) are confined in 3-dimensional (colloidal crystal template) or 2-dimensional (thin film) spaces, and form spherical LFP particles upon heat treatment. Spherical Li3Fe2(PO4)3 particles are fabricated by calcining LiFePO4/C composites in air at different temperatures. LiFePO4 spheres embedded in a carbon matrix are prepared by spin-coating the LFP/carbon precursor onto quartz substrates and then applying a series of heat treatments. The spherical Li3Fe2(PO4)3 cathode materials exhibit a capacity of 100 mA h g-1 (83% of theoretical) at 2.5 C rate. LiFePO4 spheres embedded in a carbon matrix have specific capacities of 130, 100, 83, and 50 mA h g-1 at C/2, 2 C, 4 C, and 16 C rates, respectively (PF_600_2), revealing excellent high-rate performance.

  8. Lithium titanate epitaxial coating on spinel lithium manganese oxide surface for improving the performance of lithium storage capability.

    PubMed

    Li, Jili; Zhu, Youqi; Wang, Lin; Cao, Chuanbao

    2014-11-12

    Spinel lithium titanate (Li4Ti5O12, LTO) is applied as an epitaxial coating layer on LiMn2O4 hollow microspheres (LMO) through solvothermal-assisted processing. The epitaxial interface between LTO and LMO can be clearly observed by high resolution transmission electron microscopy (HR-TEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) with atomic resolution images. The epitaxial coating cathode (EC-LMO@LTO) exhibits an excellent cyclability, thermal and rate capability for LIBs cathode due to the complete, thin LTO coating layer with strong adhesion to the host material. In addition, the small structure mismatch and high Li(+)-ion mobility of LTO can be beneficial to forming an efficient tunnel for Li(+)-ion transfer at the interface. It is suggested that EC-LMO@LTO can be recognized as a promising cathode material in electric vehicles (EVs) and plug-in hybrid electric vehicles (HEVs). PMID:25322171

  9. Specially designed carbon black nanoparticle-sulfur composite cathode materials with a novel structure for lithium-sulfur battery application

    NASA Astrophysics Data System (ADS)

    Sun, Zhenjie; Xiao, Min; Wang, Shuanjin; Han, Dongmei; Song, Shuqin; Chen, Guohua; Meng, Yuezhong

    2015-07-01

    Sulfur is a promising cathode material with a high theoretical capacity of 1672 mAh g-1, but the challenges of the low electrical conductivity of sulfur and the high solubility of polysulfide intermediates still hinder its practical application. In this work, we design and synthesize a special carbon black nanoparticle-sulfur composite cathode material (NCB-S@NCB) with a novel structure and a high sulfur content of 84 wt% for lithium-sulfur battery application. The NCB-S@NCB composite cathode delivers a high initial discharge capacity of 1258 mAh g-1 and still maintains a reversible capacity of 865 mAh g-1 after 100 cycles with a relatively constant Coulombic efficiency around 98.0%.

  10. Effect of Defects on Decay of Voltage and Capacity for Li[Li0.15Ni0.2Mn0.6]O2 Cathode Material.

    PubMed

    Yan, Wuwei; Liu, Yongning; Guo, Shengwu; Jiang, Tao

    2016-05-18

    Lithium-rich manganese metal layered oxides are very promising cathode materials for high-energy-density lithium-ion batteries, but improvement in voltage decay and capacity fade is a great challenge, which is mainly related to the structural instability or reconstruction of material's surface. Defects, such as part lattice distortions, local cation disordering and atomic ununiformity, often aggravate the further structural changes upon cycling. In this paper, we found that PEG contributed to form better layered structure, well crystallinity, uniform composition and polyhedral nanoparticles for Li[Li0.15Ni0.2Mn0.6]O2 (LNMO). On the basis of the comparative trial, a mechanism of electronegativity difference is proposed to elucidate cation nonuniform distribution. Higher electronegativity of Ni (1.91) than Mn (1.55) show a stronger ability of attraction between Ni and O atoms, and then led to Ni atoms show stronger diffusion driving force toward particle surface to contact the rich O atoms during sintering in air. However, PEG polymer can form a better barrier for more O atoms to attract Ni and Mn atoms on particle surface so that facilitated a uniform distribution. The electrochemical test indicated that the decay of discharge capacity and working voltage was mitigated, which was identified by the result of HRTEM analysis that the initial less defect structure obviously retarded the phase transformation from the layered to spinel after 50 cycles. Therefore, defects are crucial for understanding the voltage fade and capacity decay, and the improvement of performance also demonstrates that designing optimum compositions and ordering atomic arrangements will contribute to stabilize the surface structure and restrain inherent phase transitions. PMID:27116571

  11. Impact of ALD Coating on Mn-rich Cathode Materials (Presentation)

    SciTech Connect

    Santhanagopalan, S.

    2013-06-01

    LG Chem Power Inc. (LGCPI) and NREL have collaborated to demonstrate the scalability of the atomic layer deposition (ALD) coating process over the last 6 months, and the benefits of ALD coatings for long-term cycling and calendar life are being quantified. The objectives of this work are two-fold: 1) to evaluate the scalability of the process to coat LGCPI cathodes with alumina using the ALD technique, and 2) to demonstrate improvements in rate capability and life of ALD-coated LGCPI electrodes. NREL received samples of baseline material to be coated from LGCPI. NREL carried out ALD coating of the samples with help from a subcontractor, ALD Nanosolutions. NREL fabricated cells from those samples for quick screening and feedback to ALD Nanosolutions. LGCPI is currently fabricating larger-format cells for further evaluation.

  12. Enhancing the stability of microplasma device utilizing diamond coated carbon nanotubes as cathode materials

    SciTech Connect

    Chang, Tinghsun; Sankaran, Kamatchi Jothiramalingam; Tai, Nyanhwa E-mail: inanlin@mail.tku.edu.tw; Kunuku, Srinivasu; Leou, Keh-Chyang; Lin, I-Nan E-mail: inanlin@mail.tku.edu.tw

    2014-06-02

    This paper reports the enhanced stability of a microplasma device by using hybrid-granular-structured diamond (HiD) film coated carbon nanotubes (CNTs) as cathode, which overcomes the drawback of short life time in the CNTs-based one. The microplasma device can be operated more than 210 min without showing any sign of degradation, whereas the CNTs-based one can last only 50 min. Besides the high robustness against the Ar-ion bombardment, the HiD/CNTs material also possesses superior electron field emission properties with low turn-on field of 3.2 V/μm, which is considered as the prime factor for the improved plasma illumination performance of the devices.

  13. Hydrothermal synthesis of sodium vanadate nanobelts as high-performance cathode materials for lithium batteries

    NASA Astrophysics Data System (ADS)

    Yang, Kaiwen; Fang, Guozhao; Zhou, Jiang; Qin, Mulan; Tang, Yan; Pan, Anqiang; Liang, Shuquan

    2016-09-01

    The sodium vanadate (Na0.76V6O15) nanobelts have been successfully synthesized via a facile hydrothermal reaction followed by annealing. The ultra-long nanobelts have a length ranging from several micrometers to several dozens of micrometers. As cathode materials for lithium-ion batteries, the Na0.76V6O15 nanobelts exhibit high discharge capacity, excellent cyclic stability and good rate capability. High discharge capacity of 248 and 214 mA h g-1 can be obtained at the current density of 300 and 500 mA g-1, respectively. Meanwhile, it maintains a stable capacity of 113 mA h g-1 after 200 cycles at a high current density of 2000 mA g-1 with no capacity decay. The superior electrochemical performances may be attributed to the novel nanobelts structure and excellent structural stability of Na0.76V6O15.

  14. Potassium barium hexacyanoferrate - A potential cathode material for rechargeable calcium ion batteries

    NASA Astrophysics Data System (ADS)

    Padigi, Prasanna; Goncher, Gary; Evans, David; Solanki, Raj

    2015-01-01

    Potassium barium hexacyanoferrate (K2BaFe(CN)6) was investigated as a cathode material for reversible Ca2+ ion insertion/extraction type rechargeable battery using non-aqueous electrolytes. The electrochemical performance of K2BaFe(CN)6was evaluated using cyclic voltammetry and galvanic cycling at ambient temperature. It is shown that addition of water led to significant enhancement in intercalation and de-intercalation of Ca2+ ions, leading to improved charge/discharge capacity. The enhancement in performance is attributed to formation of solvation spheres around the intercalating Ca2+ ions which provide screening from the electrostatic charges of the BaFe(CN)6 lattice. A reversible capacity of 55.8 mA hr g-1 and a coulombic efficiency of 93.8% was demonstrated at the end of 30 charge/discharge cycles.

  15. CO₂ and O₂ evolution at high voltage cathode materials of Li-ion batteries: a differential electrochemical mass spectrometry study.

    PubMed

    Wang, Hongsen; Rus, Eric; Sakuraba, Takahito; Kikuchi, Jun; Kiya, Yasuyuki; Abruña, Héctor D

    2014-07-01

    A three-electrode differential electrochemical mass spectrometry (DEMS) cell has been developed to study the oxidative decomposition of electrolytes at high voltage cathode materials of Li-ion batteries. In this DEMS cell, the working electrode used was the same as the cathode electrode in real Li-ion batteries, i.e., a lithium metal oxide deposited on a porous aluminum foil current collector. A charged LiCoO2 or LiMn2O4 was used as the reference electrode, because of their insensitivity to air, when compared to lithium. A lithium sheet was used as the counter electrode. This DEMS cell closely approaches real Li-ion battery conditions, and thus the results obtained can be readily correlated with reactions occurring in real Li-ion batteries. Using DEMS, the oxidative stability of three electrolytes (1 M LiPF6 in EC/DEC, EC/DMC, and PC) at three cathode materials including LiCoO2, LiMn2O4, and LiNi(0.5)Mn(1.5)O4 were studied. We found that 1 M LiPF6 + EC/DMC electrolyte is quite stable up to 5.0 V, when LiNi(0.5)Mn(1.5)O4 is used as the cathode material. The EC/DMC solvent mixture was found to be the most stable for the three cathode materials, while EC/DEC was the least stable. The oxidative decomposition of the EC/DEC mixture solvent could be readily observed under operating conditions in our cell even at potentials as low as 4.4 V in 1 M LiPF6 + EC/DEC electrolyte on a LiCoO2 cathode, as indicated by CO2 and O2 evolution. The features of this DEMS cell to unveil solvent and electrolyte decomposition pathways are also described. PMID:24845246

  16. Structural and Electrical Properties of Lithium-Ion Rechargeable Battery Using the LiFePO4/Carbon Cathode Material.

    PubMed

    Kim, Young-Sung; Jeoung, Tae-Hoon; Nam, Sung-Pill; Lee, Seung-Hwan; Kim, Jea-Chul; Lee, Sung-Gap

    2015-03-01

    LiFePO4/C composite powder as cathode material and graphite powder as anode material for Li-ion batteries were synthesized by using the sol-gel method. An electrochemical improvement of LiFePO4 materials has been achieved by adding polyvinyl alcohol as a carbon source into as-prepared materials. The samples were characterized by elemental analysis (EA), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-EM). The chemical composition of LiFePO4/C powders was in a good agreement with that of the starting solution. The capacity loss after 500 cycles of LiFePO4/C cell is 11.1% in room temperature. These superior electrochemical properties show that LiFePO4/C composite materials are promising candidates as cathode materials. PMID:26413683

  17. Hydroxyl-decorated Graphene Systems: Organic metal-free Ferroelectrics, Multiferroics, and Proton battery Cathode Materials

    NASA Astrophysics Data System (ADS)

    Wu, Menghao; Burton, J. D.; Tsymbal, Evgeny; Zeng, Xiao; Jena, Puru; Jena's Group Team, Prof.; Burton's Group Team, Prof.; Tsymbal's Group Team, Prof.; Zeng's Group Team, Prof.

    2013-03-01

    Through density-functional-theory calculations we show that hydroxylized graphene systems are ideal candidates for light-weight organic ferroelectric materials with giant polarizations. For example, the polarization of semi-hydroxylized graphane and graphone as well as fully hydroxylized graphane are, respectively, 41.1, 43.7, 67.7 μC/cm2, much higher than any organic ferroelectric materials known to date. In addition, hydroxylized graphone is multiferroic due to the coexistence of ferroeletricity and ferromagnetism. Zigzag graphene nanoribbons decorated by hydroxyl groups also exhibit ferroelectric properties with a large polarization of 27.0 μC/cm2. Moreover, proton vacancies at the end of ribbons can induce large dipole moments that can be reversed by both hopping of protons and rotation of O-H bonds under an electric field. These materials have the potential as high-capacity cathode materials with specific capacity six times larger than lead-acid batteries and five times that of lithium-ion batteries.

  18. Advanced carbon materials/olivine LiFePO4 composites cathode for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Gong, Chunli; Xue, Zhigang; Wen, Sheng; Ye, Yunsheng; Xie, Xiaolin

    2016-06-01

    In the past two decades, LiFePO4 has undoubtly become a competitive candidate for the cathode material of the next-generation LIBs due to its abundant resources, low toxicity and excellent thermal stability, etc. However, the poor electronic conductivity as well as low lithium ion diffusion rate are the two major drawbacks for the commercial applications of LiFePO4 especially in the power energy field. The introduction of highly graphitized advanced carbon materials, which also possess high electronic conductivity, superior specific surface area and excellent structural stability, into LiFePO4 offers a better way to resolve the issue of limited rate performance caused by the two obstacles when compared with traditional carbon materials. In this review, we focus on advanced carbon materials such as one-dimensional (1D) carbon (carbon nanotubes and carbon fibers), two-dimensional (2D) carbon (graphene, graphene oxide and reduced graphene oxide) and three-dimensional (3D) carbon (carbon nanotubes array and 3D graphene skeleton), modified LiFePO4 for high power lithium ion batteries. The preparation strategies, structure, and electrochemical performance of advanced carbon/LiFePO4 composite are summarized and discussed in detail. The problems encountered in its application and the future development of this composite are also discussed.

  19. X-ray Absorption Studies in Spinel-Type LiMn 2O 4

    NASA Astrophysics Data System (ADS)

    Liu, R. S.; Jang, L. Y.; Chen, J. M.; Tsai, Y. C.; Hwang, Y. D.; Liu, R. G.

    1997-02-01

    The electronic structure of the spinel-type LiMn2O4as the cathode material for the application in secondary batteries was probed using both MnK- andL23-edge X-ray absorption near edge structure (XANES) spectra. Based on the energy shifts of the absorption peaks in the XANES spectrum correlated to the effective charge, the valence of Mn in LiMn2O4was determined to be ∼4+. This suggests that the chemical substitution of low valent Li+ions into the Mn sites is possible to result in high valence of Mn.

  20. Suppressing the voltage-fading of layered lithium-rich cathode materials via an aqueous binder for Li-ion batteries.

    PubMed

    Zhang, Tao; Li, Jun-tao; Liu, Jie; Deng, Ya-ping; Wu, Zhen-guo; Yin, Zu-wei; Guo, Dong; Huang, Ling; Sun, Shi-gang

    2016-03-28

    Guar gum (GG) has been applied as a binder for layered lithium-rich cathode materials of Li-ion batteries for the first time. Compared with the conventional PVDF binder, electrodes with GG as the binder exhibit significantly suppressed voltage and capacity fading. This study has introduced a multi-functional binder for layered lithium-rich cathode materials. PMID:26954264

  1. Structural factors affecting lithium transport in lithium-excess layered cathode materials

    NASA Astrophysics Data System (ADS)

    Fell, Christopher R.

    Lithium ion batteries have drawn significant attention as the principle energy storage device powering today's mobile electronic equipment. Despite the increased usage, the performance of current lithium ion battery technology falls short of the requirements needed for large format applications such as electric vehicles. The layered lithium-excess oxide compounds Li[NixLi1/3-2x/3Mn2/3-x/3]O2 are of interest as a new generation of cathode materials for high energy density lithium ion batteries. Efforts to achieve a better understanding of the electrochemistry of lithium-excess materials require the connection of crystal structure to electrochemical properties. In this dissertation, a combination of advanced characterization techniques was used as a tool to understand the intercalation mechanism of the layered lithium-excess transition metal oxide Li[NixLi1/3-2x/3Mn 2/3-x/3]O2. The research identified that synthesis influences the structure of the material specifically the surface of the particles. The formation of a hydroxide rich surface film decreases the electrochemical performance. Post synthesis modifications including high pressure and high temperature leads to the formation of a second layered phase in the bulk; however, the treated samples display good electrochemical properties. This result underlines the flexibility of the structure of Li[NixLi1/3-2x/3Mn 2/3-x/3]O2, a feature uncommon to other layered transition metal oxides. Surface characterization of the layered lithium-excess cathodes following electrochemical cycling revealed the formation of a new surface phase 1 to 5 nm thick as well as insight to the complex cation rearrangement process and phase transformation. This part of the research identified that significant changes occurred during electrochemical cycling; however did not identify when the transformations occurred. Investigation using in situ techniques during the first electrochemical cycle shows that the structure undergoes irreversible

  2. Evolution Of Lattice Structure And Chemical Composition Of The Surface Reconstruction Layer In Li1.2Ni0.2Mn0.6O2 Cathode Material For Lithium Ion Batteries

    SciTech Connect

    Yan, Pengfei; Nie, Anmin; Zheng, Jianming; Zhou, Yungang; Lu, Dongping; Zhang, Xiaofeng; Xu, Rui; Belharouak, Ilias; Zu, Xiaotao; Xiao, Jie; Amine, Khalil; Liu, Jun; Gao, Fei; Shahbazian-Yassar, Reza; Zhang, Jiguang; Wang, Chong M.

    2015-01-14

    Voltage and capacity fading of layer structured lithium and manganese rich (LMR) transition metal oxide is directly related to the structural and composition evolution of the material during the cycling of the battery. However, understanding such evolution at atomic level remains elusive. Based on atomic level structural imaging, elemental mapping of the pristine and cycled samples and density functional theory calculations, it is found that accompanying the hoping of Li ions is the simultaneous migration of Ni ions towards the surface from the bulk lattice, leading to the gradual depletion of Ni in the bulk lattice and thickening of a Ni enriched surface reconstruction layer (SRL). Furthermore, Ni and Mn also exhibit concentration partitions within the thin layer of SRL in the cycled samples where Ni is almost depleted at the very surface of the SRL, indicating the preferential dissolution of Ni ions in the electrolyte. Accompanying the elemental composition evolution, significant structural evolution is also observed and identified as a sequential phase transition of C2/m →I41→Spinel. For the first time, it is found that the surface facet terminated with pure cation is more stable than that with a mixture of cation and anion. These findings firmly established how the elemental species in the lattice of LMR cathode transfer from the bulk lattice to surface layer and further into the electrolyte, clarifying the long standing confusion and debate on the structure and chemistry of the surface layer and their correlation with the voltage fading and capacity decaying of LMR cathode. Therefore, this work provides critical insights for designing of cathode materials with both high capacity and voltage stability during cycling.

  3. Thianthrene-functionalized polynorbornenes as high-voltage materials for organic cathode-based dual-ion batteries.

    PubMed

    Speer, Martin E; Kolek, Martin; Jassoy, Jean Jacques; Heine, Jennifer; Winter, Martin; Bieker, Peter M; Esser, Birgit

    2015-10-25

    Thianthrene-functionalized polynorbornenes were investigated as high-voltage organic cathode materials for dual-ion cells. The polymers show reversible oxidation reactions in solution and as a solid in composite electrodes. Constant current investigations displayed a capacity of up to 66 mA h g(-1) at a high potential of 4.1 V vs. Li/Li(+). PMID:26235336

  4. Sodium iron hexacyanoferrate with high Na content as a Na-rich cathode material for Na-ion batteries

    DOE PAGESBeta

    You, Ya; Yu, Xi -Qian; Yin, Ya -Xia; Nam, Kyung -Wan; Guo, Yu -Guo

    2014-10-27

    Owing to the worldwide abundance and low-cost of Na, room-temperature Na-ion batteries are emerging as attractive energy storage systems for large-scale grids. Increasing the Na content in cathode material is one of the effective ways to achieve high energy density. Prussian blue and its analogues (PBAs) are promising Na-rich cathode materials since they can theoretically store two Na ions per formula. However, increasing the Na content in PBAs cathode materials is a big challenge in the current. Here we show that sodium iron hexacyanoferrate with high Na content could be obtained by simply controlling the reducing agent and reaction atmospheremore » during synthesis. The Na content can reach as high as 1.63 per formula, which is the highest value for sodium iron hexacyanoferrate. This Na-rich sodium iron hexacyanoferrate demonstrates a high specific capacity of 150 mA h g-1 and remarkable cycling performance with 90% capacity retention after 200 cycles. Furthermore, the Na intercalation/de-intercalation mechanism is systematically studied by in situ Raman, X-ray diffraction and X-ray absorption spectroscopy analysis for the first time. As a result, the Na-rich sodium iron hexacyanoferrate could function as a plenteous Na reservoir and has great potential as a cathode material toward practical Na-ion batteries.« less

  5. Sodium iron hexacyanoferrate with high Na content as a Na-rich cathode material for Na-ion batteries

    SciTech Connect

    You, Ya; Yu, Xi -Qian; Yin, Ya -Xia; Nam, Kyung -Wan; Guo, Yu -Guo

    2014-10-27

    Owing to the worldwide abundance and low-cost of Na, room-temperature Na-ion batteries are emerging as attractive energy storage systems for large-scale grids. Increasing the Na content in cathode material is one of the effective ways to achieve high energy density. Prussian blue and its analogues (PBAs) are promising Na-rich cathode materials since they can theoretically store two Na ions per formula. However, increasing the Na content in PBAs cathode materials is a big challenge in the current. Here we show that sodium iron hexacyanoferrate with high Na content could be obtained by simply controlling the reducing agent and reaction atmosphere during synthesis. The Na content can reach as high as 1.63 per formula, which is the highest value for sodium iron hexacyanoferrate. This Na-rich sodium iron hexacyanoferrate demonstrates a high specific capacity of 150 mA h g-1 and remarkable cycling performance with 90% capacity retention after 200 cycles. Furthermore, the Na intercalation/de-intercalation mechanism is systematically studied by in situ Raman, X-ray diffraction and X-ray absorption spectroscopy analysis for the first time. As a result, the Na-rich sodium iron hexacyanoferrate could function as a plenteous Na reservoir and has great potential as a cathode material toward practical Na-ion batteries.

  6. Template-assisted formation of porous vanadium oxide as high performance cathode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Su, Yanhui; Pan, Anqiang; Wang, Yaping; Huang, Jiwu; Nie, Zhiwei; An, Xinxin; Liang, Shuquan

    2015-11-01

    Similar to carbonaceous materials, porous metal oxides have attracted wide attention in energy storage and conversion systems because of their structural advantages, including high activity and electrolyte accessibility. In this work, we report the novel preparation of porous vanadium pentoxide (V2O5) as high performance cathode material for lithium ion batteries. Ketjen black (KB), a porous carbon material, has been employed as hard templates to host precursor species in their porous structures. The porous V2O5 electrode material is prepared after removing the KB carbon framework by calcinating the composites in air. As cathode materials for lithium ion batteries, the porous V2O5 electrodes exhibit high capacity, good cycling stability and rate capability. An initial discharge capacity of 141.1 mA h g-1 is delivered at a current density of 100 mAg-1, very close to the theoretical capacity of 147 mA h g-1.

  7. Investigation on preparation and performance of spinel LiNi0.5Mn1.5O4 with different microstructures for lithium-ion batteries.

    PubMed

    Xue, Yuan; Wang, Zhenbo; Zheng, Lili; Yu, Fuda; Liu, Baosheng; Zhang, Yin; Ke, Ke

    2015-01-01

    The high voltage spinel LiNi0.5Mn1.5O4 is a promising cathode material in next generation of lithium ion batteries. In this study, LiNi0.5Mn1.5O4 with various particle microstructures are prepared by controlling the microstructures of precursors. LiNi0.5Mn1.5O4 spinel samples with solid, hollow and hierarchical microstructures are prepared with solid MnCO3, hollow MnO2 and hierarchical Mn2O3 as precursor, respectively. The homemade spinel materials are investigated and the results show that the content of Mn(3+) and impurity phase differ much in these three spinel samples obtained under the same calcining and annealing conditions. It is revealed for the first time that an inhomogeneous migration of atoms may introduce Mn(3+) and impurity phase in the spinel. The hierarchical microstructure with the primary particles interconnected is optimal for electrode materials because this microstructure has a higher conductivity between the interconnected primary particles and appropriate specific surface area. LiNi0.5Mn1.5O4 in this microstructure has the best rate capability and also the best long-term cycling stability. PMID:26299774

  8. Investigation on preparation and performance of spinel LiNi0.5Mn1.5O4 with different microstructures for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Xue, Yuan; Wang, Zhenbo; Zheng, Lili; Yu, Fuda; Liu, Baosheng; Zhang, Yin; Ke, Ke

    2015-08-01

    The high voltage spinel LiNi0.5Mn1.5O4 is a promising cathode material in next generation of lithium ion batteries. In this study, LiNi0.5Mn1.5O4 with various particle microstructures are prepared by controlling the microstructures of precursors. LiNi0.5Mn1.5O4 spinel samples with solid, hollow and hierarchical microstructures are prepared with solid MnCO3, hollow MnO2 and hierarchical Mn2O3 as precursor, respectively. The homemade spinel materials are investigated and the results show that the content of Mn3+ and impurity phase differ much in these three spinel samples obtained under the same calcining and annealing conditions. It is revealed for the first time that an inhomogeneous migration of atoms may introduce Mn3+ and impurity phase in the spinel. The hierarchical microstructure with the primary particles interconnected is optimal for electrode materials because this microstructure has a higher conductivity between the interconnected primary particles and appropriate specific surface area. LiNi0.5Mn1.5O4 in this microstructure has the best rate capability and also the best long-term cycling stability.

  9. Investigation on preparation and performance of spinel LiNi0.5Mn1.5O4 with different microstructures for lithium-ion batteries

    PubMed Central

    Xue, Yuan; Wang, Zhenbo; Zheng, Lili; Yu, Fuda; Liu, Baosheng; Zhang, Yin; Ke, Ke

    2015-01-01

    The high voltage spinel LiNi0.5Mn1.5O4 is a promising cathode material in next generation of lithium ion batteries. In this study, LiNi0.5Mn1.5O4 with various particle microstructures are prepared by controlling the microstructures of precursors. LiNi0.5Mn1.5O4 spinel samples with solid, hollow and hierarchical microstructures are prepared with solid MnCO3, hollow MnO2 and hierarchical Mn2O3 as precursor, respectively. The homemade spinel materials are investigated and the results show that the content of Mn3+ and impurity phase differ much in these three spinel samples obtained under the same calcining and annealing conditions. It is revealed for the first time that an inhomogeneous migration of atoms may introduce Mn3+ and impurity phase in the spinel. The hierarchical microstructure with the primary particles interconnected is optimal for electrode materials because this microstructure has a higher conductivity between the interconnected primary particles and appropriate specific surface area. LiNi0.5Mn1.5O4 in this microstructure has the best rate capability and also the best long-term cycling stability. PMID:26299774

  10. Investigating the stability of cathode materials for rechargeable lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Huang, Yiqing

    Lithium ion batteries are widely used in portable electronic devices and electric vehicles. However, safety is one of the most important issues for the Li-ion batteries' use. Some cathode materials, such as LiCoO 2, are thermally unstable in the charged state. Upon decomposition these cathode materials release O2, which could react with organic electrolyte, leading to a thermal runaway. Thus understanding the stability of the cathode materials is critical to the safety of lithium ion batteries. Olivine-type LiMnPO4 is a promising cathode material for lithium ion batteries because of its high energy density. We have revealed the critical role of carbon in the stability and thermal behaviour of olivine MnPO 4 obtained by chemical delithiation of LiMnPO4. (Li)MnPO 4 samples with various particle sizes and carbon contents were studied. Carbon-free LiMnPO4 obtained by solid state synthesis in O 2 becomes amorphous upon delithiation. Small amounts of carbon (0.3 wt.%) help to stabilize the olivine structure, so that completely delithiated crystalline olivine MnPO4 can be obtained. Larger amount of carbon (2 wt.%) prevents full delithiation. Heating in air, O2, or N 2 results in structural disorder (< 300 °C), formation of an intermediate sarcopside Mn3(PO4)2 phase (350 -- 450 °C), and complete decomposition to Mn2P2O 7 on extended heating at 400 °C. Carbon protects MnPO4 from reacting with environmental water, which is detrimental to its structural stability. We not only studied the crystalline olivine MnPO4, but also investigated the amorphous products obtained from carbon-free LiMnPO 4. We have revealed the Mn dissolution phenomenon during chemical delithiation of LiMnPO4, which causes the amorphization of olivine MnPO 4. Properties of crystalline-MnPO4 obtained from carbon-coated LiMnPO4 and of amorphous product resulting from the delithiation of pure LiMnPO4 were studied and compared. The P-rich amorphous phases in the latter are considered to be MnHP2O7 and MnH2P

  11. Corrosion behavior and interfacial resistivity of bipolar plate materials under molten carbonate fuel cell cathode conditions

    SciTech Connect

    Schoeler, A.C.; Kaun, T.D.; Bloom, I.; Lanagan, M.; Krumpelt, M.

    2000-03-01

    A material is needed for bipolar plate materials in molten carbonate fuel cells (MCFCs) that combines the low oxide resistivity of 316L stainless steel (SS) with the low corrosion rate of the type 310 SS. The authors tested a group of materials that included Nitronic 50 SS and a newly developed high-temperature nickel-rich alloy, having chromium contents ranging from 16 to 31 wt %. Their results indicate that chromium content is the primary determinant of oxide scale composition and resistivity. In the MCFC cathode compartment, all tested alloys formed a duplex structure with an inner Cr-rich layer and an outer Fe-rich one. The composition of the inner Cr-rich layer was determined by the chromium content of the base alloy and has a controlling effect on scale resistivity. Oxide scale resistivity was measured for three electrolyte compositions: Li/K, Li/Na, and newly developed (Li, Na, Ca, Ba) carbonates. Changes in the physical/mechanical properties (spallation/cracking) in the oxide scale of 316L SS provided an understanding of its resistivity fluctuations over time.

  12. Strontium-doped samarium manganite as cathode materials for oxygen reduction reaction in solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Li, W.; Xiong, C. Y.; Jia, L. C.; Pu, J.; Chi, B.; Chen, X.; Schwank, J. W.; Li, J.

    2015-06-01

    SmxSr1-xMnO3 with x = 0.3, 0.5 and 0.8, denoted as SSM37, SSM55 and SSM82, respectively, have been prepared via a sol-gel route as materials for cathodes in solid oxide fuel cells. Their activities in the oxygen reduction reaction (ORR) have been evaluated in comparison with the state-of-the-art cathode material La0.8Sr0.2MnO3 (LSM82) by electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and thermogravimetry (TG). Among all the prepared cathodes, the SSM55 exhibits the lowest values, while the LSM82 exhibits the highest polarization resistance, at open circuit voltage (OCV) and temperatures from 650 to 800 °C. This result indicates that the prepared SmxSr1-xMnO3 is a promising replacement for LSM82 as cathode material for SOFCs, and the SSM55 represents the optimal concentration in SmxSr1-xMnO3 series. The remarkably high ORR activity of the SSM55 is ascribed to its high surface Mn4+/Mn3+ and Oad/Olattice ratios and fast surface oxygen exchange kinetics.

  13. Sintered wire cathode

    DOEpatents

    Falce, Louis R.; Ives, R. Lawrence

    2009-06-09

    A porous cathode structure is fabricated from a plurality of wires which are placed in proximity to each other in elevated temperature and pressure for a sintering time. The sintering process produces the porous cathode structure which may be divided into a plurality of individual porous cathodes, one of which may be placed into a dispenser cathode support which includes a cavity for containing a work function reduction material such as BaO, CaO, and Al.sub.2O.sub.3. The work function reduction material migrates through the pores of the porous cathode from a work replenishment surface adjacent to the cavity of the dispenser cathode support to an emitting cathode surface, thereby providing a dispenser cathode which has a uniform work function and therefore a uniform electron emission.

  14. Facet-dependent disorder in pristine high-voltage lithium-manganese-rich cathode material.

    PubMed

    Dixit, Hemant; Zhou, Wu; Idrobo, Juan-Carlos; Nanda, Jagjit; Cooper, Valentino R

    2014-12-23

    Defects and surface reconstructions are thought to be crucial for the long-term stability of high-voltage lithium-manganese-rich cathodes. Unfortunately, many of these defects arise only after electrochemical cycling which occurs under harsh conditions, making it difficult to fully comprehend the role they play in degrading material performance. Recently, it has been observed that defects are present even in the pristine material. This study, therefore, focuses on examining the nature of the disorder observed in pristine Li1.2Ni0.175Mn0.525Co0.1O2 (LNMCO) particles. Using atomic-resolution Z-contrast imaging and electron energy loss spectroscopy measurements, we show that there is indeed a significant amount of antisite defects present in this material, with transition metals substituting on Li metal sites. Furthermore, we find a strong segregation tendency of these types of defects toward open facets (surfaces perpendicular to the layered arrangement of atoms) rather than closed facets (surfaces parallel to the layered arrangement of atoms). First-principles calculations identify antisite defect pairs of Ni swapping with Li ions as the predominant defect in the material. Furthermore, energetically favorable swapping of Ni on the Mn sites was observed to lead to Mn depletion at open facets. Relatively, low Ni migration barriers also support the notion that Ni is the predominant cause of disorder. These insights suggest that certain facets of the LNMCO particles may be more useful for inhibiting surface reconstruction and improving the stability of these materials through careful consideration of the exposed surface. PMID:25415876

  15. Laser annealing of textured thin film cathode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Kohler, R.; Bruns, M.; Smyrek, P.; Ulrich, S.; Przybylski, M.; Pfleging, W.

    2010-02-01

    The material development for advanced lithium ion batteries plays an important role in future mobile applications and energy storage systems. It is assumed that electrode materials made of nano-composited materials will improve battery lifetime and will lead to an enhancement of lithium diffusion and thus improve battery capacity and cyclability. Lithium cobalt oxide (LiCoO2) is commonly used as a cathode material. Thin films of this electrode material were synthesized by non-reactive r.f. magnetron sputtering of LiCoO2 targets on silicon or stainless steel substrates. For the formation of the high temperature phase of LiCoO2 (HT-LiCoO2), which exhibits good electrochemical performance with a specific capacity of 140 mAh/g and high capacity retention, a subsequent annealing treatment is necessary. For this purpose laser annealing of thin film LiCoO2 was investigated in detail and compared to conventional furnace annealing. A high power diode laser system operating at a wavelength of 940 nm with an integrated pyrometer for temperature control was used. Different temperatures (between 200°C and 700°C) for the laser structured and unstructured thin films were applied. The effects of laser treatment on the LiCoO2 thin films studied with Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction to determine their stoichiometry and crystallinity. The development of HT-LiCoO2 and also the formation of a Co3O4 phase were discussed. The electrochemical properties of the manufactured films were investigated via electrochemical cycling against a lithium anode.

  16. Facet Dependent Disorder in the Pristine High Voltage Lithium-Manganese-Rich Cathode Material

    DOE PAGESBeta

    Dixit, Hemant M.; Zhou, Wu; Idrobo Tapia, Juan Carlos; Nanda, Jagjit; Cooper, Valentino R.

    2014-11-21

    Defects and surface reconstructions are thought to be crucial for the long term stability of high-voltage lithium-manganese-rich cathodes. Unfortunately, many of these defects arise only after electrochemical cycling which occur under harsh conditions making it difficult to fully comprehend the role they play in degrading material performance. Recently, it has been observed that defects are present even in the pristine material. This study, therefore, focuses on examining the nature of the disorder observed in pristine Limore » $$_{1.2}$$Ni$$_{0.175}$$Mn$$_{0.525}$$Co$$_{0.1}$$O$_2$ (LNMCO) particles. Using atomic resolution Z-contrast imaging and electron energy-loss spectroscopy measurements we show that there are indeed a significant amount of anti-site defects present in this material; with transition metals substituting on Li metal sites. Furthermore, we find a strong tendency of segregation of these types of defects towards open facets (surfaces perpendicular to the layered arrangement of atoms), rather than closed facets (surfaces parallel to the layered arrangement of atoms). First principles calculations identify anti-site defect pairs of Ni swapping with Li ions as the predominant defect in the material. Furthermore, energetically favorable swapping of Ni on the Mn sites were observed to lead to Mn depletion at open facets. Relatively, low Ni migration barriers also support the notion that Ni are the predominant cause of disorder. These insights suggests that certain facets of the LNMCO particles may be more useful for inhibiting surface reconstruction and improving the stability of these materials through careful consideration of the exposed surface.« less

  17. Facet Dependent Disorder in the Pristine High Voltage Lithium-Manganese-Rich Cathode Material

    SciTech Connect

    Dixit, Hemant M.; Zhou, Wu; Idrobo Tapia, Juan Carlos; Nanda, Jagjit; Cooper, Valentino R.

    2014-11-21

    Defects and surface reconstructions are thought to be crucial for the long term stability of high-voltage lithium-manganese-rich cathodes. Unfortunately, many of these defects arise only after electrochemical cycling which occur under harsh conditions making it difficult to fully comprehend the role they play in degrading material performance. Recently, it has been observed that defects are present even in the pristine material. This study, therefore, focuses on examining the nature of the disorder observed in pristine Li$_{1.2}$Ni$_{0.175}$Mn$_{0.525}$Co$_{0.1}$O$_2$ (LNMCO) particles. Using atomic resolution Z-contrast imaging and electron energy-loss spectroscopy measurements we show that there are indeed a significant amount of anti-site defects present in this material; with transition metals substituting on Li metal sites. Furthermore, we find a strong tendency of segregation of these types of defects towards open facets (surfaces perpendicular to the layered arrangement of atoms), rather than closed facets (surfaces parallel to the layered arrangement of atoms). First principles calculations identify anti-site defect pairs of Ni swapping with Li ions as the predominant defect in the material. Furthermore, energetically favorable swapping of Ni on the Mn sites were observed to lead to Mn depletion at open facets. Relatively, low Ni migration barriers also support the notion that Ni are the predominant cause of disorder. These insights suggests that certain facets of the LNMCO particles may be more useful for inhibiting surface reconstruction and improving the stability of these materials through careful consideration of the exposed surface.

  18. Resistivity of bipolar plate materials at the cathode interface in molten carbonate fuel cells.

    SciTech Connect

    Kaun, T. D.

    1998-11-18

    Measurements of oxide scale resistivity for prospective bipolar plate materials in the molten carbonate fuel cell (MCFC) are coupled with observations of microstructural/compositional change over time. This work searches for a compromise to the high corrosion rate of Type 316L and the high oxide scale resistance of Type 310S. We tested a group of materials having chromium content ranging from 16 to 31 wt%, including Nitronic 50 and NKK, a Ni-Cr-Fe alloy. Chromium content was found to be the primary determinant of oxide scale composition. In the MCFC cathode compartment, stainless steels generally formed a duplex structure with an inner Cr-rich layer and an outer, Fe-rich layer. The composition of the inner Cr-rich layer was related to the base alloy and had a controlling effect on scale resistivity. Oxide scale resistivity was measured for two electrolyte compositions: Li/K and Li/Na carbonates. Changes in the physical/mechanical properties (spallation/cracking) in the oxide scale of Type 316L provided an understanding of its resistivity fluctuations over time.

  19. Surface reconstruction and chemical evolution of stoichiometric layered cathode materials for lithium-ion batteries.

    PubMed

    Lin, Feng; Markus, Isaac M; Nordlund, Dennis; Weng, Tsu-Chien; Asta, Mark D; Xin, Huolin L; Doeff, Marca M

    2014-01-01

    The present study sheds light on the long-standing challenges associated with high-voltage operation of LiNi(x)Mn(x)Co(1-2x)O2 cathode materials for lithium-ion batteries. Using correlated ensemble-averaged high-throughput X-ray absorption spectroscopy and spatially resolved electron microscopy and spectroscopy, here we report structural reconstruction (formation of a surface reduced layer, to transition) and chemical evolution (formation of a surface reaction layer) at the surface of LiNi(x)Mn(x)Co(1-2x)O2 particles. These are primarily responsible for the prevailing capacity fading and impedance buildup under high-voltage cycling conditions, as well as the first-cycle coulombic inefficiency. It was found that the surface reconstruction exhibits a strong anisotropic characteristic, which predominantly occurs along lithium diffusion channels. Furthermore, the surface reaction layer is composed of lithium fluoride embedded in a complex organic matrix. This work sets a refined example for the study of surface reconstruction and chemical evolution in battery materials using combined diagnostic tools at complementary length scales. PMID:24670975

  20. Mechanical and electrochemical performance of composite cathode contact materials for solid oxide fuel cells

    SciTech Connect

    Tucker, Michael C.; Dejonghe, Lutgard C.; Garcia-Negron, Valerie; Trejo, Rosa M; Lara-Curzio, Edgar

    2013-01-01

    The feasibility of adding glass or inorganic binder to conventional SOFC cathode contact materials (CCM) in order to improve bonding to adjacent materials in the cell stack is assessed. Two glasses (SEM-COM SCZ-8 and Schott GM31107) and one inorganic binder (Aremco 644A) are mixed with LSM particles to produce composite CCM pastes. These are used to bond Mn1.5Co1.5O4-coated stainless steel mesh current collectors to anode-supported button cells. The cells are operated at 800 C for about 1000 h. The cell with SCZ-8 addition to the CCM displays quite stable operation (3.9%/1000 h degradation), whereas the other additives lead to somewhat higher degradation rate. Bonding of the CCM to coated stainless steel coupons is also assessed. Interfacial fracture toughness is determined using a four-point bend test. The fracture toughness for LSM Schott glass (12.3 N mm 1), LSM SCZ-8 glass (6.8 N mm 1) and LSM 644A binder (5.4 N mm 1) are significantly improved relative to pure LSM (1.7 N mm 1). Indeed, addition of binder or glass is found to improve bonding of the CCM layer without sacrificing cell performance.

  1. Variations in structure and electrochemistry of iron- and titanium-doped lithium nickel manganese oxyfluoride spinels

    NASA Astrophysics Data System (ADS)

    Höweling, Andres; Stenzel, David; Gesswein, Holger; Kaus, Maximilian; Indris, Sylvio; Bergfeldt, Thomas; Binder, Joachim R.

    2016-05-01

    Doping of cathode materials can considerably improve electrochemical performance and stability. Here, the high-voltage LiNi0.5Mn1.5O4 spinel is used as a candidate material. It is high-voltage cycling at a potential of approximately 4.7 V and the ability to host 2 eq. Li, thus leading to a theoretical capacity of 294 mAh g-1, that makes this material interesting. In order to improve stability and electronic conductivity, the spinel is doped with titanium and iron. Cycling in a voltage range of 2.0-5.0 V leads to a cooperative Jahn-Teller distortion accompanied by a phase transformation from cubic to tetragonal symmetry. This causes a severe capacity fade. To improve capacity retention, the as-prepared spinel is post-doped with fluorine. Influence of different fluorine amounts in LiNi0.5Mn1.4Fe0.1Ti0.027O4-xFx (x = 0-0.3) on the capacity and stability is analyzed. The initial capacities decrease with increasing fluorine content but the low voltage capacity is stabilized. Best electrochemical results are obtained with a fluorine content of x = 0.15. Furthermore, an additional redox couple is found. The intensity of this depends on the fluorine content. It is assumed that manganese, either in the tetrahedral sites or in octahedral sites, bound to fluorine lead to a higher voltage.

  2. Electrochemical Effects of Atomic Layer Deposition on Cathode Materials for Lithium Batteries

    NASA Astrophysics Data System (ADS)

    Scott, Isaac David

    One of the greatest challenges of modern society is to stabilize a consistent energy supply that will meet our growing energy demand while decreasing the use of fossil fuels and the harmful green house gases which they produce. Developing reliable and safe solutions has driven research into exploring alternative energy sources for transportation including fuel cells, hydrogen storage, and lithium-ion batteries (LIBs). For the foreseeable future, though, rechargeable batteries appear to be the most practically viable power source. To deploy LIBs in next-generation vehicles, it is essential to develop electrodes with durability, high energy density, and high power. Unfortunately, the power capability of LIBs is generally hindered by Li+-ion diffusion in micrometer-sized materials and the formation of an insulating solid electrolyte interface (SEI) layer on the surface of the active material. In addition, degradation of the battery material due to chemical and electrochemical reactions with the electrolyte lead to both capacity fade and safety concerns both at room and higher temperatures. The current study focuses on mitigating these issues for high voltage cathode materials by both using nanoscale particles to improve Li+-ion diffusion and using ultrathin nanoscale coatings to protect the battery materials from undesirable side reactions. The electrode material is coated with Al2O3 using atomic layer deposition (ALD), which is a method to grow conformal thin films with atomic thickness (angstrom level control) using sequential, self-limiting surface reactions. First, nano-LiCoO 2 is employed to demonstrate the effectiveness of ALD coatings and demonstrates a profound increase in rate performance (>250% improvement) over generally employed micrometer-sized particles. Second, the cathode materials LiNi 0.8Co0.15Al0.05O2, LiNi0.33Mn 0.33Co0.33O2, LiMn2O4, and LiNi0.5Mn1.5O4 were used to demonstrate the benefits ALD coatings have on thermal runaway. The results show a

  3. Evolution of Phase Transformation Behavior in Li(Mn1.5Ni0.5)O4 Cathodes Studies By In Situ XRD

    SciTech Connect

    Rhodes, Kevin J; Meisner, Roberta Ann; Kim, Yoongu; Dudney, Nancy J; Daniel, Claus

    2011-01-01

    Li(Mn1.5Ni0.5)O4 (MNO) is promising spinel cathode material for lithium ion batteries (LIB) due to its increased intercalation potential and improved capacity retention compared to LiMn2O4. Still, improvements to this materials performance must be achieved before MNO is a viable option for commercial LIB cells. In situ X-ray diffraction of Li(Mn1.5Ni0.5)O4 was performed using a novel electrochemical cell based on coin cell hardware. A diffractogram of the pristine material showed a spinel structure with a Ni2+ oxidation state. As the cell was charged through its 4.75V plateau, a transition between spinels with Ni2+, Ni3+, and Ni4+ oxidation was observed. As the oxidation stage on the nickel increased the lattice parameter of the corresponding spinel was reduced. As discharged ensued the spinel reversed its phases change until only the Ni2+ spinel was present. When discharge reached the 2.75V plateau a tetragonal spinel phase was formed, which upon subsequent cell charging was completely converted back to a cubic spinel phase. Lattice parameter changes of each phase were calculated and showed a characteristic strain release during phase changes. After 15 full cycles the transition between these phases was no longer complete and the formation of the tetragonal spinel phase was no longer detected. A discussion of how these cycle-induced changes to phase transition behavior relate to capacity fade and overall cell performance is presented.

  4. Flower-like CoS with nanostructures as a new cathode-active material for rechargeable magnesium batteries

    NASA Astrophysics Data System (ADS)

    He, Dong; Wu, Danni; Gao, Jing; Wu, Xiaomei; Zeng, Xiaoqin; Ding, Wenjiang

    2015-10-01

    Cobalt sulfides have become promising electrode materials for lithium ion batteries while their applications in rechargeable magnesium batteries are rarely reported. In this paper, we have done some research on the electrochemical properties of cobalt sulfide (CoS) as the cathode-active material for rechargeable magnesium batteries. Flower-like CoS with nanostructures is synthesized by a facile solvothermal route. The obvious redox peaks on the cyclic voltammetric curves confirm the possibility of applications. The galvanostatic charge-discharge tests display excellent cycle stability and high coulomb efficiency. Meanwhile, the possible mechanism of charge-discharge reactions is proposed and discussed. These results show that flower-like CoS is a promising candidate as cathode-active material for rechargeable magnesium batteries.

  5. Re-heating effect of Ni-rich cathode material on structure and electrochemical properties

    NASA Astrophysics Data System (ADS)

    Jo, Jae Hyeon; Jo, Chang-Heum; Yashiro, Hitoshi; Kim, Sun-Jae; Myung, Seung-Taek

    2016-05-01

    The re-heating effect for Ni-rich Li[Ni0.7Mn0.3]O2 is investigated because the process is required in surface modification and removal of adhered water molecules. A representative binary Ni-rich Li[Ni0.7Mn0.3]O2 (in which cationic distribution in Li layers is not affected by heteroelements) is selected and synthesized via co-precipitation. The as-synthesized Ni-rich Li[Ni0.7Mn0.3]O2 is re-heated at 200 °C, 400 °C, and 600 °C, so that the resulting structural and electrochemical properties are compared by means of X-ray diffraction, transmission electron microscopy, time of flight-secondary ion spectroscopy, thermogravimetric analysis, high temperature X-ray diffraction, and electrochemical tests. Raising the re-heating temperature increases the occupancy of Ni2+ in Li layers and accelerates the aggregation of lithium-related compounds such as Li2CO3 and LiOH towards the particle surface. Among the several conditions tested, re-heating at 200 °C results in a negligible change in the crystal structure; specifically, Ni2+ occupation in Li layers, higher capacity with good reversibility upon cycling tests, better rate capability, and thermal properties. Therefore, re-heating of cathode active materials, in particular Ni-rich compositions, should be considered to stabilize both electrode performances and thermal properties.

  6. Defect physics vis-à-vis electrochemical performance in layered mixed-metal oxide cathode materials

    NASA Astrophysics Data System (ADS)

    Hoang, Khang; Johannes, Michelle

    Layered mixed-metal oxides with different compositions of (Ni,Co,Mn) [NCM] or (Ni,Co,Al) [NCA] have been used in commercial lithium-ion batteries. Yet their defect physics and chemistry is still not well understood, despite having important implications for the electrochemical performance. In this presentation, we report a hybrid density functional study of intrinsic point defects in the compositions LiNi1/3Co1/3Mn1/3O2 (NCM1/3) and LiNi1/3Co1/3Al1/3O2 (NCA1/3) which can also be regarded as model compounds for NCM and NCA. We will discuss defect landscapes in NCM1/3 and NCA1/3 under relevant synthesis conditions with a focus on the formation of metal antisite defects and its implications on the electrochemical properties and ultimately the design of NCM and NCA cathode materials.

  7. Surface modified CFx cathode material for ultrafast discharge and high energy density

    DOE PAGESBeta

    Dai, Yang; Zhu, Yimei; Cai, Sendan; Wu, Lijun; Yang, Weijing; Xie, Jingying; Wen, Wen; Zheng, Jin-Cheng; Zheng, Yi

    2014-11-10

    Li/CFx primary possesses the highest energy density of 2180 W h kg⁻¹ among all primary lithium batteries. However, a key limitation for the utility of this type of battery is in its poor rate capability because the cathode material, CFx, is an intrinsically poor electronic conductor. Here, we report on our development of a controlled process of surface de-fluorination under mild hydrothermal conditions to modify the highly fluorinated CFx. The modified CFx, consisting of an in situ generated shell component of F-graphene layers, possesses good electronic conductivity and removes the transporting barrier for lithium ions, yielding a high-capacity performance andmore » an excellent rate-capability. Indeed, a capacity of 500 mA h g⁻¹ and a maximum power density of 44 800 W kg⁻¹ can be realized at the ultrafast rate of 30 C (24 A g⁻¹), which is over one order of magnitude higher than that of the state-of-the-art primary lithium-ion batteries.« less

  8. Surface modified CFx cathode material for ultrafast discharge and high energy density

    SciTech Connect

    Dai, Yang; Zhu, Yimei; Cai, Sendan; Wu, Lijun; Yang, Weijing; Xie, Jingying; Wen, Wen; Zheng, Jin-Cheng; Zheng, Yi

    2014-11-10

    Li/CFx primary possesses the highest energy density of 2180 W h kg⁻¹ among all primary lithium batteries. However, a key limitation for the utility of this type of battery is in its poor rate capability because the cathode material, CFx, is an intrinsically poor electronic conductor. Here, we report on our development of a controlled process of surface de-fluorination under mild hydrothermal conditions to modify the highly fluorinated CFx. The modified CFx, consisting of an in situ generated shell component of F-graphene layers, possesses good electronic conductivity and removes the transporting barrier for lithium ions, yielding a high-capacity performance and an excellent rate-capability. Indeed, a capacity of 500 mA h g⁻¹ and a maximum power density of 44 800 W kg⁻¹ can be realized at the ultrafast rate of 30 C (24 A g⁻¹), which is over one order of magnitude higher than that of the state-of-the-art primary lithium-ion batteries.

  9. Improvement of Electrochemical Properties of Ni-Rich Cathode Material by Polypyrrole Coating.

    PubMed

    Yoo, Gi-Won; Jang, Byung-Chan; Min, Song-Gi; Son, Jong-Tae

    2016-03-01

    In this study, we attempted a nanosized coating layer of commercial polypyrrole (PPy) on LiNi0.6Co0.1Mn0.3O2 (HNCM) cathode material to overcome the side reactions with electrolyte and a decrease in the capacity of the inert coating layer. The coating method using commercial PPy is very simple. The energy dispersive X-ray spectroscopy (EDS) analysis and transmission electron microscopy (TEM) images confirmed that PPy coating layer was well dispersed and nanosized. The alternating current (AC) impedance studies revealed that the coating of PPy significantly decreased the charge-transfer resistance of HNCM electrodes. Moreover, the 1 wt% PPy-HNCM electrode exhibited good electrochemical performance with a specific discharge capacity of 177.52 mA h g(-1) at a rate of 0.1 C in the voltage range 3.0-4.3 V, whereas the capacity of the HNCM electrode was only 167.13 mA h g(-1). PMID:27455681

  10. Crystal and electronic structures of nitridophosphate compounds as cathode materials for Na-ion batteries

    NASA Astrophysics Data System (ADS)

    Debbichi, M.; Lebègue, S.

    2015-08-01

    Using density-functional theory, we have studied the electronic and magnetic properties of two promising compounds that can be used as cathode materials, namely, Na2Fe2P3O9N and Na3TiP3O9N . When Na is extracted, we found the volume change to be quite small, with values of ˜-0.6 % for Na3TiP3O9N and -5 % for Na2Fe2P3O9N . Our calculated voltages with the Hubbard-type correction (GGA+U) approximation are 2.93 V for Na3TiP3O9N /Na2TiP3O9N and 2.68 V for Na2Fe2P3O9N /NaFe2P3O9N , in good agreement with the experimental data. Our results confirm that these compounds are very promising for rechargeable Na-ion batteries.

  11. Binary and ternary nano-catalysts as cathode materials in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Trimm, Bryan Dunning

    The need for alternative energy, in order to reduce dependence on petroleum based fuels, has increased in recent years. Public demand is at an all-time high for low emitting or none polluting energy sources, driving the research for cleaner technology. Lithium batteries and fuel cells have the ability to produce this alternative energy with much cleaner standards, while allowing for portability and high energy densities. This work focuses on the performance of nanocatalysts in Proton Exchange Membrane Fuel Cell or PEMFC. A key technical challenge is the sluggish rate for oxygen reduction reaction at the cathode of PEMFC, which requires highly-active and stable catalysts. Our investigation is directed at increasing stability and durability as well as reducing high loading of noble metals in these catalyst materials. Binary and ternary structured nanomaterials, e.g., Pt51V1Co48/C and Pd xCu1-x/C, have been synthesized and tested in a PEMFC, in order to gain a better understanding of their durability and efficiency. In addition to electrochemical characterization, synchrotron x-ray techniques at the Advance Photon Source in Argonne National Lab have also been used for the structural characterization.

  12. Li2S-reduced graphene oxide nanocomposites as cathode material for lithium sulfur batteries

    NASA Astrophysics Data System (ADS)

    Han, Kai; Shen, Jingmei; Hayner, Cary M.; Ye, Hongqi; Kung, Mayfair C.; Kung, Harold H.

    2014-04-01

    A lithium sulfide-reduced graphene oxide nanocomposite (Li2S-rGO) was synthesized and evaluated as the cathode material and Li source for the assembly of Li-S batteries. The composite, with a unique 3-D pocket structure, was synthesized by a combination of facile solution chemistry and thermal treatment. The as-prepared Li2S-rGO nanocomposites were characterized by X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy, which showed 20-40 nm Li2S particles homogeneously dispersed between reduced graphene oxide sheets. Li2S contents as high as ∼66% could be obtained. When used with an electrolyte containing LiNO3 and polysulfide, the Li2S-rGO nanocomposites exhibited a high initial capacity of 982 mAh g-1 Li2S. However, there was noticeable capacity fade in subsequent cycles, probably due to polysulfide dissolution and the shuttle mechanism, but a capacity of 315 mAh g-1 could still be obtained after 100 cycles, with 90-95% coulomb efficiency. The effect of polysulfide additive in the electrolyte on the activation of Li2S in the first delithiation step was discussed.

  13. Electrochemical studies on niobium triselenide cathode material for lithium rechargeable cells

    SciTech Connect

    Ratnakumar, B.V.; Ni, C.L.; DiStefano, S.; Nagasubramanian, G.; Bankston, C.P.

    1989-01-01

    Niobium triselenide offers promise as a high energy density cathode material for ambient temperature lithium rechargeable cells. The electrochemical behavior of NbSe/sub 3/ in the battery electrolyte, i.e., 1.5m LiAsF/sub 6//2 Me-THF is reported here. A detailed study has been carried out using various ac and dc electrochemical techniques to establish the mechanism of intercalation of three equivalents of Li with NbSe/sub 3/ as well as the rate governing processes in the reduction of NbSe/sub 3/. Based on the experimental data, an equivalent circuit has been formulated to represent the NbSe/sub 3/-solution interface. The kinetic parameters for the reduction of NbSe/sub 3/ were evaluated from the ac and dc measurements. Finally, the structural change in NbSe/sub 3/ on lithiation during initial discharge which results in higher cell voltages and different electrochemical response as compared to virgin NbSe/sub 3/ was identified to be a loss of crystallographic order, i.e., amorphous by x-ray diffraction.

  14. Excellent cycling stability and superior rate capability of a graphene-amorphous FePO4 porous nanowire hybrid as a cathode material for sodium ion batteries

    NASA Astrophysics Data System (ADS)

    Yang, Gaoliang; Ding, Bing; Wang, Jie; Nie, Ping; Dou, Hui; Zhang, Xiaogang

    2016-04-01

    A porous nanowire material consisting of graphene-amorphous FePO4 was investigated as an advanced cathode material for sodium ion batteries for large-scale applications. This hybrid cathode material showed excellent cycling performance and superior rate capability, which were attributed to the porous nanowire structure and the existence of graphene.A porous nanowire material consisting of graphene-amorphous FePO4 was investigated as an advanced cathode material for sodium ion batteries for large-scale applications. This hybrid cathode material showed excellent cycling performance and superior rate capability, which were attributed to the porous nanowire structure and the existence of graphene. Electronic supplementary information (ESI) available: Experimental section; SEM images, BET, XPS spectrum, TG curve and EIS spectra of the samples; the comparison of electrochemical performance with the reported results. See DOI: 10.1039/c6nr00409a

  15. Electronic and Electrochemical Properties of Li 1–x Mn 1.5 Ni 0.5 O 4 Spinel Cathodes As a Function of Lithium Content and Cation Ordering

    DOE PAGESBeta

    Moorhead-Rosenberg, Zach; Huq, Ashfia; Goodenough, John B.; Manthiram, Arumugam

    2015-10-05

    The electronic and electrochemical properties of the high-voltage spinel LiMn1.5Ni0.5O4 as a function of cation ordering and lithium content have been investigated. Conductivity and activation energy measurements confirm that charge transfer occurs by small polaron hopping and the charge carrier conduction is easier in the Ni:3d band than in the in Mn:3d band. Seebeck coefficient data reveal that the Ni2+/3+. and Ni3+/4+ redox couples are combined in a single,3d band, and that maximum charge carrier concentration occurs where the average Ni oxidation state is close to 3+, corresponding to x = 0.5 in Li Li1-xMn1.5Ni0.5O4. Furthermore, maximum electronic conductivity ismore » found at x = 0.5, regardless of cation ordering. The thermodynamically stable phases formed during cycling were investigated by recording the X-ray diffraction (XRD) of chemically delithiated powders. The more ordered spinels maintained two separate two-phase regions upon lithium extraction, while the more disordered samples exhibited a solid-solubility region from LiMn1.5Ni0.5O4 to Li0.5Mn1.5Ni0.5O4. The conductivity and phase-transformation data of four samples with varying degrees of cation ordering were compared to the electrochemical data collected with lithium cells. Only the most ordered spinel showed inferior rate performance, while the sample annealed for a shorter time performed comparable to the unannealed or disordered samples. Our results challenge the most common beliefs about high-voltage spinel: (i) low Mn3+ content is responsible for poor rate performance and (ii) thermodynamically stable solid-solubility is critical for fast kinetics.« less

  16. Mixed ion/electron-conductive protective soft nanomatter-based conformal surface modification of lithium-ion battery cathode materials

    NASA Astrophysics Data System (ADS)

    Park, Jang-Hoon; Kim, Ju-Myung; Lee, Chang Kee; Lee, Sang-Young

    2014-10-01

    Understanding and control of interfacial phenomena between electrode material and liquid electrolytes are of major scientific importance for boosting development of high-performance lithium ion batteries with reliable electrochemical/safety attributes. Here, as an innovative surface engineering approach to address the interfacial issues, a new concept of mixed ion/electron-conductive soft nanomatter-based conformal surface modification of the cathode material is presented. The soft nanomatter is comprised of an electron conductive carbonaceous (C) substance embedded in an ion conductive polyimide (PI) nanothin compliant film. In addition to its structural uniqueness, the newly proposed surface modification benefits from a simple fabrication process. The PI/carbon soft nanomatter is directly synthesized on LiCoO2 surface via one-pot thermal treatment of polyamic acid (=PI precursor) and sucrose (=carbon source) mixture, where the LiCoO2 powders are chosen as a model system to explore the feasibility of this surface engineering strategy. The resulting PI/carbon coating layer facilitates electronic conduction and also suppresses unwanted side reactions arising from the cathode material-liquid electrolyte interface. These synergistic coating effects of the multifunctional PI/carbon soft nanomatter significantly improve high-voltage cell performance and also mitigate interfacial exothermic reaction between cathode material and liquid electrolyte.

  17. A Ternary Polyaniline/Active Carbon/Lithium Iron Phosphate Composite as Cathode Material for Lithium Ion Battery.

    PubMed

    Wang, Xiaohong; Zhang, Wuxing; Huang, Yunhui; Xia, Tian; Lian, Yongfu

    2016-06-01

    Lithium iron phosphate (LiFePO4) has been evaluated as the most promising cathode material for the next generation lithium-ion batteries because of its high operating voltage, good cycle performance, low cost, and environmentally friendly safety. However, pure LiFePO4 shows poor reversible capacity and charge/discharge performance at high current density. Many methods including optimization of particle size, introduction of coating carbon and conductive polymer, and the doping of metal and halogen ions have been developed to improve its electrochemical performance. In this study, conductive polymer polyaniline (PANI), active carbon and LiFePO4 (C-LFP/PANI) composite cathodes were successfully prepared by chemical oxidation method. Electrochemical performance shows that a remarkable improvement in capacity and rate performance can be achieved in the C-LFP/PANI composite cathodes with an addition of HCI. In comparison with C-LFP cathode, the C-LFP/PANI doped with HCl composite exhibits ca. 15% and 26% capacity enhancement at 0.2 C and 10 C, respectively. PMID:27427742

  18. Lightweight Cathodes For Nickel Batteries

    NASA Technical Reports Server (NTRS)

    Britton, Doris L.

    1996-01-01

    Lightweight cathodes for rechargeable nickel-based electrochemical cells undergoing development. In cathodes, mats of nickel fibers are substrates providing structural support of, and electrical contact with, active cathode material. Offers specific energies greater than sintered nickel plaque cathodes. Electrodes used in rechargeable batteries for applications in which weight major concern, including laptop computers, cellular phones, flashlights, soldiers' backpacks, and electric vehicles.

  19. Yolk-shelled cathode materials with extremely high electrochemical performances prepared by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Choi, Seung Ho; Hong, Young Jun; Kang, Yun Chan

    2013-08-01

    A facile, continuous preparation process of yolk-shell-structured lithium-metal oxide powders without a template for use as cathode materials in lithium ion batteries is introduced for the first time. Single and double-shelled LiNi0.5Mn1.5O4 yolk-shell powders as the first target materials are prepared directly by spray pyrolysis from a spray solution with sucrose, at a short residence time of 4 s. Fast combustion and contraction of a carbon-mixed oxide composite intermediate, formed from a micro-sized droplet inside a hot wall reactor maintained at 700 °C, produces the yolk-shell powders. The yolk-shell structure of the precursor powders directly prepared by spray pyrolysis is well maintained even at a high post-treatment temperature of 750 °C. The yolk-shell LiNi0.5Mn1.5O4 powders delivered a 1000th high discharge capacity of 108 mA h g-1 at 10 C. The discharge capacities are as high as 103, 95, and 91 mA h g-1 at extremely high discharge rates of 100, 200, and 300 C and the corresponding specific energy densities are 420, 370, and 328 W h kg-1. The capacity retention at a constant discharge rate of 200 C is 90% after 500 cycles.A facile, continuous preparation process of yolk-shell-structured lithium-metal oxide powders without a template for use as cathode materials in lithium ion batteries is introduced for the first time. Single and double-shelled LiNi0.5Mn1.5O4 yolk-shell powders as the first target materials are prepared directly by spray pyrolysis from a spray solution with sucrose, at a short residence time of 4 s. Fast combustion and contraction of a carbon-mixed oxide composite intermediate, formed from a micro-sized droplet inside a hot wall reactor maintained at 700 °C, produces the yolk-shell powders. The yolk-shell structure of the precursor powders directly prepared by spray pyrolysis is well maintained even at a high post-treatment temperature of 750 °C. The yolk-shell LiNi0.5Mn1.5O4 powders delivered a 1000th high discharge capacity of 108 m

  20. Defect Physics, Delithiation Mechanism, and Electronic and Ionic Conduction in Layered Lithium Manganese Oxide Cathode Materials

    NASA Astrophysics Data System (ADS)

    Hoang, Khang

    2015-02-01

    Layered Li Mn O2 and Li2Mn O3 are of great interest for lithium-ion battery cathodes because of their high theoretical capacities. The practical application of these materials is, however, limited due to poor electrochemical performance. We herein report a comprehensive first-principles study of defect physics in Li Mn O2 and Li2Mn O3 using hybrid density-functional calculations. We find that manganese antisites have low formation energies in Li Mn O2 and may act as nucleation sites for the formation of impurity phases. The antisites can also occur with high concentrations in Li2Mn O3 ; however, unlike in Li Mn O2 , they can be eliminated by tuning the experimental conditions during preparation. Other intrinsic point defects may also occur and have an impact on the materials' properties and functioning. An analysis of the formation of lithium vacancies indicates that lithium extraction from Li Mn O2 is associated with oxidation at the manganese site, resulting in the formation of manganese small hole polarons; whereas in Li2Mn O3 the intrinsic delithiation mechanism involves oxidation at the oxygen site, leading to the formation of bound oxygen hole polarons ηO+ . The layered oxides are found to have no or negligible bandlike carriers, and they cannot be doped n or p type. The electronic conduction proceeds through hopping of hole and/or electron polarons; the ionic conduction occurs through lithium monovacancy and/or divacancy migration mechanisms. Since ηO+ is not stable in the absence of negatively charged lithium vacancies in bulk Li2Mn O3 , the electronic conduction near the start of delithiation is likely to be poor. We suggest that the electronic conduction associated with ηO+ and, hence, the electrochemical performance of Li2Mn O3 can be improved through nanostructuring and/or ion substitution.

  1. Hard X-ray Fluorescence Measurements of Heteroepitaxial Solid Oxide Fuel Cell Cathode Materials

    SciTech Connect

    Davis, Jacob N.; Miara, Lincoln J.; Saraf, Laxmikant V.; Kaspar, Tiffany C.; Gopalan, Srikanth; Pal, Uday B.; Woicik, Joseph C.; Basu, Soumendra N.; Ludwig, Karl F.

    2012-12-01

    Commonly, SOFCs are operated at high temperatures (above 800°C). At these temperatures expensive housing is needed to contain an operating stack as well as coatings to contain the oxidation of the metallic interconnects. Lowering the temperature of an operating device would allow for more conventional materials to be used, thus lowering overall cost. Understanding the surface chemical states of cations in the surface of the SOFC cathode is vital to designing a system that will perform well at lower temperatures. The samples studied were grown by pulsed laser deposition (PLD) at the Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). 20% strontium doped lanthanum manganite (LSM-20) was grown on YSZ and NGO (neodymium gallate). The films on YSZ have a fiber texture. LSM-20 on NGO is heteroepitaxial. Lanthanum strontium cobalt ferrite (LSCF-6428) films were grown on LAO and YSZ with a GDC barrier layer. Total X-ray Reflection Fluorescence (TXRF) was used to depth profile the samples. In a typical experiment, the angle of the incident beam is varied though the critical angle. Below the critical angle, the x-ray decays as an evanescent wave and will only penetrate the top few nanometers. TXRF experiments done on LSM films have suggested strontium segregates to the surface and form strontium enriched nanoparticles (1). It should be pointed out that past studies have focused on 30% strontium A-site doping, but this project uses 20% strontium doped lanthanum manganite. XANES and EXAFS data were taken as a function of incoming angle to probe composition as a function of depth. XANES spectra can be difficult to analyze fully. For other materials density functional theory calculations compared to near edge measurements have been a good way to understand the 3d valence electrons (2).

  2. Thermal Stability and Reactivity of Cathode Materials for Li-Ion Batteries.

    PubMed

    Huang, Yiqing; Lin, Yuh-Chieh; Jenkins, David M; Chernova, Natasha A; Chung, Youngmin; Radhakrishnan, Balachandran; Chu, Iek-Heng; Fang, Jin; Wang, Qi; Omenya, Fredrick; Ong, Shyue Ping; Whittingham, M Stanley

    2016-03-23

    The thermal stability of electrochemically delithiated Li0.1Ni0.8Co0.15Al0.05O2 (NCA), FePO4 (FP), Mn0.8Fe0.2PO4 (MFP), hydrothermally synthesized VOPO4, LiVOPO4, and electrochemically lithiated Li2VOPO4 is investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis, coupled with mass spectrometry (TGA-MS). The thermal stability of the delithiated materials is found to be in the order of NCA < VOPO4 < MFP < FP. Unlike the layered oxides and MFP, VOPO4 does not evolve O2 on heating. Thus, VOPO4 is less likely to cause a thermal run-away phenomenon in batteries at elevated temperature and so is inherently safer. The lithiated materials LiVOPO4, Li2VOPO4, and LiNi0.8Co0.15Al0.05O2 are found to be stable in the presence of electrolyte, but sealed-capsule high-pressure experiments show a phase transformation of VOPO4 → HVOPO4 → H2VOPO4 when VOPO4 reacts with electrolyte (1 M LiPF6 in EC/DMC = 1:1) between 200 and 300 °C. Using first-principles calculations, we confirm that the charged VOPO4 cathode is indeed predicted to be marginally less stable than FP but significantly more stable than NCA in the absence of electrolyte. An analysis of the reaction equilibria between VOPO4 and EC using a multicomponent phase diagram approach yields products and reaction enthalpies that are highly consistent with the experiment results. PMID:26915096

  3. The usefulness of a LiMn 2O 4 composite as an active cathode material in lithium batteries

    NASA Astrophysics Data System (ADS)

    Fonseca, C. Polo; Neves, S.

    The synthesis and electrochemical properties of a lithium manganese spinel, a LiMn 2O 4 film and a LiMn 2O 4/polyaniline (PAni)/PVDF composite film were investigated. The materials were characterized using X-ray diffraction, differential thermal analysis, scanning electron microscopy and BET surface area analysis. The intercalation/deintercalation lithium was investigated using electrochemical impedance spectroscopy, cyclic voltammetry and charge/discharge cycles. The use of PAni as an electronic conductor and electroactive material optimized the process of lithium intercalation/deintercalation in this film. The stabilized lithium extraction capacity of the LiMn 2O 4/PAni/PVDF composite was significantly higher than for the LiMn 2O 4 film (138 and 52 mA h g -1, respectively).

  4. Evaluation of Ca3Co2O6 as cathode material for high-performance solid-oxide fuel cell

    PubMed Central

    Wei, Tao; Huang, Yun-Hui; Zeng, Rui; Yuan, Li-Xia; Hu, Xian-Luo; Zhang, Wu-Xing; Jiang, Long; Yang, Jun-You; Zhang, Zhao-Liang

    2013-01-01

    A cobalt-based thermoelectric compound Ca3Co2O6 (CCO) has been developed as new cathode material with superior performance for intermediate-temperature (IT) solid-oxide fuel cell (SOFC). Systematic evaluation has been carried out. Measurement of thermal expansion coefficient (TEC), thermal-stress (σ) and interfacial shearing stress (τ) with the electrolyte show that CCO matches well with several commonly-used IT electrolytes. Maximum power density as high as 1.47 W cm−2 is attained at 800°C, and an additional thermoelectric voltage of 11.7 mV is detected. The superior electrochemical performance, thermoelectric effect, and comparable thermal and mechanical behaviors with the electrolytes make CCO to be a promising cathode material for SOFC. PMID:23350032

  5. Evaluation of Ca3Co2O6 as cathode material for high-performance solid-oxide fuel cell.

    PubMed

    Wei, Tao; Huang, Yun-Hui; Zeng, Rui; Yuan, Li-Xia; Hu, Xian-Luo; Zhang, Wu-Xing; Jiang, Long; Yang, Jun-You; Zhang, Zhao-Liang

    2013-01-01

    A cobalt-based thermoelectric compound Ca(3)Co(2)O(6) (CCO) has been developed as new cathode material with superior performance for intermediate-temperature (IT) solid-oxide fuel cell (SOFC). Systematic evaluation has been carried out. Measurement of thermal expansion coefficient (TEC), thermal-stress (σ) and interfacial shearing stress (τ) with the electrolyte show that CCO matches well with several commonly-used IT electrolytes. Maximum power density as high as 1.47 W cm(-2) is attained at 800°C, and an additional thermoelectric voltage of 11.7 mV is detected. The superior electrochemical performance, thermoelectric effect, and comparable thermal and mechanical behaviors with the electrolytes make CCO to be a promising cathode material for SOFC. PMID:23350032

  6. One-step microwave synthesized core-shell structured selenium@carbon spheres as cathode materials for rechargeable lithium batteries.

    PubMed

    Guo, Jing; Wang, Qingsong; Qi, Chao; Jin, Jun; Zhu, Yingjie; Wen, Zhaoyin

    2016-04-12

    A core-shell structured selenium@carbon composite material was obtained by a facile one-step microwave synthesis method. The uniform carbon shells coated on selenium spheres greatly minimized the shuttle effect of Li-Se cells. The morphology analysis of the cathodes after different cycles revealed that the Se cores were perfectly confined inside the unbroken C shells all through the 100 cycles. PMID:27030554

  7. Functionally Graded Cathodes for Solid Oxide Fuel Cells

    SciTech Connect

    Harry Abernathy; Meilin Liu

    2006-12-31

    One primary suspected cause of long-term performance degradation of solid oxide fuels (SOFCs) is the accumulation of chromium (Cr) species at or near the cathode/electrolyte interface due to reactive Cr molecules originating from Cr-containing components (such as the interconnect) in fuel cell stacks. To date, considerable efforts have been devoted to the characterization of cathodes exposed to Cr sources; however, little progress has been made because a detailed understanding of the chemistry and electrochemistry relevant to the Cr-poisoning processes is still lacking. This project applied multiple characterization methods - including various Raman spectroscopic techniques and various electrochemical performance measurement techniques - to elucidate and quantify the effect of Cr-related electrochemical degradation at the cathode/electrolyte interface. Using Raman microspectroscopy the identity and location of Cr contaminants (SrCrO{sub 4}, (Mn/Cr){sub 3}O{sub 4} spinel) have been observed in situ on an LSM cathode. These Cr contaminants were shown to form chemically (in the absence of current flowing through the cell) at temperatures as low as 625 C. While SrCrO{sub 4} and (Mn/Cr){sub 3}O{sub 4} spinel must preferentially form on LSM, since the LSM supplies the Sr and Mn cations necessary for these compounds, LSM was also shown to be an active site for the deposition of Ag{sub 2}CrO{sub 4} for samples that also contained silver. In contrast, Pt and YSZ do not appear to be active for formation of Cr-containing phases. The work presented here supports the theory that Cr contamination is predominantly chemically-driven and that in order to minimize the effect, cathode materials should be chosen that are free of cations/elements that could preferentially react with chromium, including silver, strontium, and manganese.

  8. Surfactants assisted synthesis and electrochemical properties of nano-LiFePO4/C cathode materials for low temperature applications

    NASA Astrophysics Data System (ADS)

    Zheng, Fenghua; Yang, Chenghao; Ji, Xu; Hu, Dongli; Chen, Yu; Liu, Meilin

    2015-08-01

    Nano-LiFePO4/C cathode materials have been synthesized by a solid-state reaction method using Tween60-Span60 composite as surfactant and carbon source. The Tween60-Span60 composite surfactants together lead a strong space steric effect, which ensures a high surface energy and reaction kinetic of the precursors. Consequently, it contributes to the formation of uniformly distributed LiFePO4 particles coated with a thin layer of carbon. The unique structured LiFePO4/C cathode materials can deliver high electrochemical capacities of 166, 150.5 and 130.1 mAh g-1 under 0.1 C at 25, 0 and -20 °C, respectively. Moreover, the LiFePO4/C cathode materials demonstrate an excellent rate capability and cycle performance, no discernible specific discharge capacity fading has been observed after over 400 cycles under the rate of 0.1-5 C at 25 °C, or after over 100 cycles under the rate of 0.1-0.5 C at -20 °C.

  9. Structure of spinel

    SciTech Connect

    Sickafus, K.E.; Wills, J.M.; Grimes, N.W.

    1999-12-01

    This paper reviews the crystal structure of compounds with the general formula AB{sub 2}X{sub 4}, which crystallize with the same atomic structure as the mineral spinel, MgAl{sub 2}O{sub 4}. Three degrees of freedom associated with the detailed atomic arrangements of spinels are considered here: (i) the lattice parameter, a; (ii) the anion parameter, u; and (iii) the cation inversion parameter, i. Oxide spinels are used as examples to explore the interrelationships between these parameters.

  10. Operando Lithium Dynamics in the Li-Rich Layered Oxide Cathode Material via Neutron Diffraction

    DOE PAGESBeta

    Liu, Haodong; An, Ke; Venkatachalam, Subramanian; Qian, Danna; Zhang, Minghao; Meng, Ying Shirley

    2016-04-06

    Neutron diffraction under operando battery cycling is used to study the lithium and oxygen dynamics of high Li-rich Li(Lix/3Ni(3/8-3x/8)Co(1/4-x/4)Mn(3/8+7x/24)O2 (x = 0.6, HLR) and low Li-rich Li(Lix/3Ni(1/3-x/3)Co(1/3-x/3)Mn(1/3+x/3)O2 (x = 0.24, LLR) compounds that exhibit different degrees of oxygen activation at high voltage. The measured lattice parameter changes and oxygen position show largely contrasting changes for the two cathodes where the LLR exhibits larger movement of oxygen and lattice contractions in comparison to the HLR that maintains relatively constant lattice parameters and oxygen position during the high voltage plateau until the end of charge. Density functional theory calculations show the presencemore » of oxygen vacancy during the high voltage plateau; changes in the lattice parameters and oxygen position are consistent with experimental observations. Lithium migration kinetics for the Li-rich material is observed under operando conditions for the first time to reveal the rate of lithium extraction from the lithium layer, and transition metal layer is related to the different charge and discharge characteristics. At the beginning of charging, the lithium extraction predominately occurs within the lithium layer. The lithium extraction from the lithium layer slows down and extraction from the transition metal layer evolves at a faster rate once the high voltage plateau is reached.« less

  11. Facile electrochemical polymerization of polypyrrole film applied as cathode material in dual rotating disk photo fuel cell

    NASA Astrophysics Data System (ADS)

    Li, Kan; Zhang, Hongbo; Tang, Tiantian; Tang, Yanping; Wang, Yalin; Jia, Jinping

    2016-08-01

    Polypyrrole (PPy) film is synthesized on Ti substrate through electrochemical polymerization method and is applied as cathode material in a TiO2 NTs-PPy dual rotating disk photo fuel cell (PFC). The optimized PPy electrochemical polymerization is carried out using linear sweep voltammetry from 0 V to 1.2 V (vs. SCE) with scan rate of 0.1 V s-1, 100 circles. Sixty milliliter real textile wastewater with the initial COD and conductivity of 408 ± 6 mgO2 L-1 and 20180 μS cm-1 is treated in this PFC under UV irradiation. About 0.46 V open-circuit voltage (VOC) and 1.8-2.2 mA short-circuit current (JSC) are obtained. Due to the effective electron-hole separation effect, the COD removal rate is as high as 0.0055 min-1. Stable current and COD removal can be obtained at different output voltage. Two influence factors including rotating speed and pH are investigated. Better electricity generation performance and COD removal activity are achieved at high rotating speed and in acidic condition. In comparison with platinized cathode, though VOC is lower, similar JSC is measured. Considering the high cost of Pt, PPy is a promising alternative cathode material in PFC that can also generate electricity efficiently and stably.

  12. Ruthenium-oxide-coated sodium vanadium fluorophosphate nanowires as high-power cathode materials for sodium-ion batteries.

    PubMed

    Peng, Manhua; Li, Biao; Yan, Huijun; Zhang, Dongtang; Wang, Xiayan; Xia, Dingguo; Guo, Guangsheng

    2015-05-26

    Sodium-ion batteries are a very promising alternative to lithium-ion batteries because of their reliance on an abundant supply of sodium salts, environmental benignity, and low cost. However, the low rate capability and poor long-term stability still hinder their practical application. A cathode material, formed of RuO2 -coated Na3 V2 O2 (PO4 )2 F nanowires, has a 50 nm diameter with the space group of I4/mmm. When used as a cathode material for Na-ion batteries, a reversible capacity of 120 mAh g(-1) at 1 C and 95 mAh g(-1) at 20 C can be achieved after 1000 charge-discharge cycles. The ultrahigh rate capability and enhanced cycling stability are comparable with high performance lithium cathodes. Combining first principles computational investigation with experimental observations, the excellent performance can be attributed to the uniform and highly conductive RuO2 coating and the preferred growth of the (002) plane in the Na3 V2 O2 (PO4 )2 F nanowires. PMID:25864686

  13. Facile electrochemical polymerization of polypyrrole film applied as cathode material in dual rotating disk photo fuel cell

    NASA Astrophysics Data System (ADS)

    Li, Kan; Zhang, Hongbo; Tang, Tiantian; Tang, Yanping; Wang, Yalin; Jia, Jinping

    2016-08-01

    Polypyrrole (PPy) film is synthesized on Ti substrate through electrochemical polymerization method and is applied as cathode material in a TiO2 NTs-PPy dual rotating disk photo fuel cell (PFC). The optimized PPy electrochemical polymerization is carried out using linear sweep voltammetry from 0 V to 1.2 V (vs. SCE) with scan rate of 0.1 V s-1, 100 circles. Sixty milliliter real textile wastewater with the initial COD and conductivity of 408 ± 6 mgO2 L-1 and 20180 μS cm-1 is treated in this PFC under UV irradiation. About 0.46 V open-circuit voltage (VOC) and 1.8-2.2 mA short-circuit current (JSC) are obtained. Due to the effective electron-hole separation effect, the COD removal rate is as high as 0.0055 min-1. Stable current and COD removal can be obtained at different output voltage. Two influence factors including rotating speed and pH are investigated. Better electricity generation performance and COD removal activity are achieved at high rotating speed and in acidic condition. In comparison with platinized cathode, though VOC is lower, similar JSC is measured. Considering the high cost of Pt, PPy is a promising alternative cathode material in PFC that can also generate electricity efficiently and stably.

  14. One-step synthesis of graphene/polypyrrole nanofiber composites as cathode material for a biocompatible zinc/polymer battery.

    PubMed

    Li, Sha; Shu, Kewei; Zhao, Chen; Wang, Caiyun; Guo, Zaiping; Wallace, Gordon; Liu, Hua Kun

    2014-10-01

    The significance of developing implantable, biocompatible, miniature power sources operated in a low current range has become manifest in recent years to meet the demands of the fast-growing market for biomedical microdevices. In this work, we focus on developing high-performance cathode material for biocompatible zinc/polymer batteries utilizing biofluids as electrolyte. Conductive polymers and graphene are generally considered to be biocompatible and suitable for bioengineering applications. To harness the high electrical conductivity of graphene and the redox capability of polypyrrole (PPy), a polypyrrole fiber/graphene composite has been synthesized via a simple one-step route. This composite is highly conductive (141 S cm(-1)) and has a large specific surface area (561 m(2) g(-1)). It performs more effectively as the cathode material than pure polypyrrole fibers. The battery constructed with PPy fiber/reduced graphene oxide cathode and Zn anode delivered an energy density of 264 mWh g(-1) in 0.1 M phosphate-buffer saline. PMID:25198621

  15. Considering Critical Factors of Li-rich Cathode and Si Anode Materials for Practical Li-ion Cell Applications.

    PubMed

    Ko, Minseong; Oh, Pilgun; Chae, Sujong; Cho, Woongrae; Cho, Jaephil

    2015-09-01

    In order to keep pace with increasing energy demands for advanced electronic devices and to achieve commercialization of electric vehicles and energy-storage systems, improvements in high-energy battery technologies are required. Among the various types of batteries, lithium ion batteries (LIBs) are among the most well-developed and commercialized of energy-storage systems. LIBs with Si anodes and Li-rich cathodes are one of the most promising alternative electrode materials for next-generation, high-energy batteries. Si and Li-rich materials exhibit high reversible capacities of <2000 mAh g(-1) and >240 mAh g(-1) , respectively. However, both materials have intrinsic drawbacks and practical limitations that prevent them from being utilized directly as active materials in high-energy LIBs. Examples for Li-rich materials include phase distortion during cycling and side reactions caused by the electrolyte at the surface, and for Si, large volume changes during cycling and low conductivity are observed. Recent progress and important approaches adopted for overcoming and alleviating these drawbacks are described in this article. A perspective on these matters is suggested and the requirements for each material are delineated, in addition to introducing a full-cell prototype utilizing a Li-rich cathode and Si anode. PMID:26108922

  16. Nanosized high voltage cathode material LiMg 0.05Ni 0.45Mn 1.5O 4: Structural, electrochemical and in situ investigation

    NASA Astrophysics Data System (ADS)

    Lafont, U.; Locati, C.; Borghols, W. J. H.; Łasińska, A.; Dygas, J.; Chadwick, A. V.; Kelder, E. M.

    In this study a modified solid state synthesis (auto-ignition method) is used to form nanosized spinel type material LiMg 0.05Ni 0.45Mn 1.5O 4. This material presents a high voltage plateau at 4.75 V vs. Li/Li +. Structural and electrochemical characterisations have been performed using a wide range of techniques (TEM, neutron diffraction, galvanostatic measurements, and impedance spectroscopy). Besides, in situ XAS has been performed to monitor the evolution of Ni and Mn oxidation state during Li intercalation. The material presents an ordered cubic spinel structure, good capacity retention upon cycling (131 mAh g -1 at C/10 and 117 mAh g -1 at 1C) and good electronic conductivity (10 -6 S cm -1 at RT). The simultaneous presence of Mn 3+/Mn 4+ in the structure has been investigated and explained by inclusion of disordered nanodomains in the structure.

  17. Mechanism of high luminous efficacy in plasma display panel with high secondary electron emission coefficient cathode material analyzed through three-dimensional fluid model simulation

    SciTech Connect

    Kwon, Ohyung; Lee, Tae-Ho; Cheong, Hee-Woon; Whang, Ki-Woong; Bae, Hyun Sook; Jung, Hae-Yoon

    2011-08-15

    The mechanism to realize high luminous efficacy in a plasma display panel fabricated with a cathode material possessing a high secondary electron emission coefficient ({gamma}) for Ne and Xe ions was studied via three-dimensional numerical simulation. When a high {gamma} cathode material is used, the increased electron heating efficacy is responsible for increasing vacuum ultraviolet (VUV) efficacy with 10% Xe content gas. However, the continued availability of sufficient secondary electrons during the dynamic moving phase of the cathode sheath in which the electric field remains weakened causes increasing VUV efficacy with 30% Xe content gas. It was found that the improvement of the luminous efficacy of the plasma display panel with a high {gamma} cathode material is maximized under the condition of high Xe content gas because of the simultaneous increase of the electron heating efficacy and Xe excitation efficacy.

  18. CO 2 adsorption on porous NiO as a cathode material for molten carbonate fuel cells

    NASA Astrophysics Data System (ADS)

    Özkan, Göksel; Özçelik, Emre

    Molten carbonate fuel cells (MCFC) are the systems suitable for large-scale energy production. The cathode material used in these cells is NiO. In this study the NiO cathode was synthesized by tape-casting method and the adsorption of CO 2, one of the cathode feeding gases, was investigated on it. The adsorption studies were carried out by the use of packed column and the adsorption analysis were performed using pulse response technique. There were two 1/4 in. diameter and 5 and 10 cm length columns prepared for the experiments and they were packed with 3 mm average particle sized NiO. The experiments were carried out with gas chromatography using He as a carrier gas. The response curves were taken after pulsing the columns with CO 2. The equilibrium constants and heat of adsorption of CO 2 on NiO were determined by the use of the first absolute moment equations corresponding to retention times. It was observed that the adsorption was physical in nature. From the adsorption constants determined at different temperatures and the heat of adsorption, Δ H0, was found as -1299 cal mol -1.

  19. Nickel Hydroxide-Modified Sulfur/Carbon Composite as a High-Performance Cathode Material for Lithium Sulfur Battery.

    PubMed

    Niu, Xiao-Qing; Wang, Xiu-Li; Xie, Dong; Wang, Dong-Huang; Zhang, Yi-Di; Li, Yi; Yu, Ting; Tu, Jiang-Ping

    2015-08-01

    Tailored sulfur cathode is vital for the development of a high performance lithium-sulfur (Li-S) battery. A surface modification on the sulfur/carbon composite would be an efficient strategy to enhance the cycling stability. Herein, we report a nickel hydroxide-modified sulfur/conductive carbon black composite (Ni(OH)2@S/CCB) as the cathode material for the Li-S battery through the thermal treatment and chemical precipitation method. In this composite, the sublimed sulfur is stored in the CCB, followed by a surface modification of Ni(OH)2 nanoparticles with size of 1-2 nm. As a cathode for the Li-S battery, the as-prepared Ni(OH)2@S/CCB electrode exhibits better cycle stability and higher rate discharge capacity, compared with the bare S/CCB electrode. The improved performance is largely due to the introduction of Ni(OH)2 surface modification, which can effectively suppress the "shuttle effect" of polysulfides, resulting in enhanced cycling life and higher capacity. PMID:26158375

  20. Influence of Parameters of the Glow Discharge on Change of Structure and the Isotope Composition of the Cathode Materials

    NASA Astrophysics Data System (ADS)

    Savvatimova, I. B.; Gavritenkov, D. V.

    Results of examinations of changes in structure, element, and isotope composition of cathodes after the glow discharge exposure in hydrogen, deuterium, argon, and xenon are submitted. The voltage of the discharge was less than 1000 V and the current was 5-150 mA. Samples before and after ions bombardment in the glow discharge were explored by the methods of mass spectrometry: the secondary ions (SIMS), the secondary ions with additional ionization of neutral sprayed particles (SNMS), spark (SMS), and thermo-ionization (TIMS), and also methods of energy dispersion X-ray spectral analysis (EDX). The alpha-, beta-, gamma- emission, and gamma- spectrometry for radioactive uranium specimens were also carried out before and after experiments in the glow discharge. Changes in structure, isotope, and element composition of the cathode samples depend on current density, integrated ions flow (fluence of ions), kind of irradiating ions and other experimental conditions. Attempts are made to estimate qualitatively and quantitatively the role of each of the parameters on intensity of the observed changes in cathode composition. It is shown that the maximum changes in structure, chemical and isotope composition of the cathode material occur in "hot points," such as craters from microexplosions, phase segregations, blisters and other new formations. Various methods of the analysis revealed that the basic elements Mg, O, Si, Al, and Ca with quantities up to per cents and more were prevailing in these zones and not found out before experiment. The greatest changes of the isotope relations were observed for iron, calcium, silicon, chromium after experiments with pulsing current. EDX method finds out the elements missing in the samples before experiment such as cadmium, strontium, tin. The isotopes with mass number 59 (Co 100%), 55 (Mn 100%), 45 (Sc 100%) are also not found in initial samples and background measurement by TIMS method. Results of changes in the element and isotope

  1. Graphene–Selenium Hybrid Microballs as Cathode Materials for High-performance Lithium–Selenium Secondary Battery Applications

    PubMed Central

    Youn, Hee-Chang; Jeong, Jun Hui; Roh, Kwang Chul; Kim, Kwang-Bum

    2016-01-01

    In this study, graphene–selenium hybrid microballs (G–SeHMs) are prepared in one step by aerosol microdroplet drying using a commercial spray dryer, which represents a simple, scalable continuous process, and the potential of the G–SeHMs thus prepared is investigated for use as cathode material in applications of lithium–selenium secondary batteries. These morphologically unique graphene microballs filled with Se particles exhibited good electrochemical properties, such as high initial specific capacity (642 mA h g−1 at 0.1 C, corresponding to Se electrochemical utilisation as high as 95.1%), good cycling stability (544 mA h g−1 after 100 cycles at 0.1 C; 84.5% retention) and high rate capability (specific capacity of 301 mA h g−1 at 5 C). These electrochemical properties are attributed to the fact that the G–SeHM structure acts as a confinement matrix for suppressing the dissolution of polyselenides in the organic electrolyte, as well as an electron conduction path for increasing the transport rate of electrons for electrochemical reactions. Notably, based on the weight of hybrid materials, electrochemical performance is considerably better than that of previously reported Se-based cathode materials, attributed to the high Se loading content (80 wt%) in hybrid materials. PMID:27480798

  2. Graphene-Selenium Hybrid Microballs as Cathode Materials for High-performance Lithium-Selenium Secondary Battery Applications.

    PubMed

    Youn, Hee-Chang; Jeong, Jun Hui; Roh, Kwang Chul; Kim, Kwang-Bum

    2016-01-01

    In this study, graphene-selenium hybrid microballs (G-SeHMs) are prepared in one step by aerosol microdroplet drying using a commercial spray dryer, which represents a simple, scalable continuous process, and the potential of the G-SeHMs thus prepared is investigated for use as cathode material in applications of lithium-selenium secondary batteries. These morphologically unique graphene microballs filled with Se particles exhibited good electrochemical properties, such as high initial specific capacity (642 mA h g(-1) at 0.1 C, corresponding to Se electrochemical utilisation as high as 95.1%), good cycling stability (544 mA h g(-1) after 100 cycles at 0.1 C; 84.5% retention) and high rate capability (specific capacity of 301 mA h g(-1) at 5 C). These electrochemical properties are attributed to the fact that the G-SeHM structure acts as a confinement matrix for suppressing the dissolution of polyselenides in the organic electrolyte, as well as an electron conduction path for increasing the transport rate of electrons for electrochemical reactions. Notably, based on the weight of hybrid materials, electrochemical performance is considerably better than that of previously reported Se-based cathode materials, attributed to the high Se loading content (80 wt%) in hybrid materials. PMID:27480798

  3. Graphene–Selenium Hybrid Microballs as Cathode Materials for High-performance Lithium–Selenium Secondary Battery Applications

    NASA Astrophysics Data System (ADS)

    Youn, Hee-Chang; Jeong, Jun Hui; Roh, Kwang Chul; Kim, Kwang-Bum

    2016-08-01

    In this study, graphene–selenium hybrid microballs (G–SeHMs) are prepared in one step by aerosol microdroplet drying using a commercial spray dryer, which represents a simple, scalable continuous process, and the potential of the G–SeHMs thus prepared is investigated for use as cathode material in applications of lithium–selenium secondary batteries. These morphologically unique graphene microballs filled with Se particles exhibited good electrochemical properties, such as high initial specific capacity (642 mA h g‑1 at 0.1 C, corresponding to Se electrochemical utilisation as high as 95.1%), good cycling stability (544 mA h g‑1 after 100 cycles at 0.1 C 84.5% retention) and high rate capability (specific capacity of 301 mA h g‑1 at 5 C). These electrochemical properties are attributed to the fact that the G–SeHM structure acts as a confinement matrix for suppressing the dissolution of polyselenides in the organic electrolyte, as well as an electron conduction path for increasing the transport rate of electrons for electrochemical reactions. Notably, based on the weight of hybrid materials, electrochemical performance is considerably better than that of previously reported Se-based cathode materials, attributed to the high Se loading content (80 wt%) in hybrid materials.

  4. Prediction of O2 Dissociation Kinetics on LaMnO3-Based Cathode Materials for Solid Oxide Fuel Cells

    SciTech Connect

    Choi, Yongman; Lynch, Matthew E.; Lin, M. C.; Liu, Meilin

    2009-04-30

    First-principles and statistical-theory calculations were applied to examine the interactions between oxygen molecules and the (100) surfaces of LaMnO3 and La0.5Sr0.5MnO2.75, one of the most-used cathode materials in solid oxide fuel cells (SOFCs). To predict the rate constants for the interactions between O2 and LaMnO3 or La0.5Sr0.5MnO2.75, potential energy profiles were constructed using the nudged elastic band (NEB) method. Predicted rate constants for the dissociation of adsorbed oxygen species on LaMnO3 (lm) and La0.5Sr0.5MnO2.75 (lsm) can be expressed as kdiss,lm ) 2.35 × 1012 exp(-0.50 eV/RT) s-1 and kdiss,lsm ) 2.15 × 1012 exp(-0.23 eV/RT) s-1, respectively, in the temperature range of 873-1273 K at 1 atm. Because the activation energy for oxygen dissociation on La0.5Sr0.5MnO2.75 (0.23 eV) is much smaller than that on LaMnO3 (0.50 eV), oxygen vacancies greatly enhance O2 dissociation kinetics. The kinetic and mechanistic studies for the interactions at the molecular level are imperative to gaining a fundamental understanding of oxygen reduction kinetics on cathode materials and to providing important insight into the rational design of more catalytically active cathode materials for SOFCs.

  5. Template-Assisted Hydrothermal Synthesis of Li₂MnSiO₄ as a Cathode Material for Lithium Ion Batteries.

    PubMed

    Xie, Man; Luo, Rui; Chen, Renjie; Wu, Feng; Zhao, Taolin; Wang, Qiuyan; Li, Li

    2015-05-27

    Lithium manganese silicate (Li2MnSiO4) is an attractive cathode material with a potential capacity above 300 mA h g(-1) if both lithium ions can be extracted reversibly. Two drawbacks of low electronic conductivity and structural collapse could be overcome by a conductive surface coating and a porous structure. Porous morphology with inner mesopores offers larger surface area and shorter ions diffusion pathways and also buffers the volume changes during lithium insertion and extraction. In this paper, mesoporous Li2MnSiO4 (M-Li2MnSiO4) prepared using MCM-41 as template through a hydrothermal route is compared to a sample of bulk Li2MnSiO4 (B-Li2MnSiO4) using silica as template under the same conditions. Also, in situ carbon coating technique was used to improve the electronic conductivity of M-Li2MnSiO4. The physical properties of these cathode materials were further characterized by SEM, XRD, FTIR, and N2 adsorption-desorption. It is shown that M-Li2MnSiO4 exhibits porous structure with pore sizes distributed in the range 9-12 nm, and when used as cathode electrode material, M-Li2MnSiO4 exhibits enhanced specific discharge capacity of 193 mA h g(-1) at a constant current of 20 mA g(-1) compared with 120.1 mA h g(-1) of B-Li2MnSiO4. This is attributed to the porous structure which allows the electrolyte to penetrate into the particles easily. And carbon-coated M-Li2MnSiO4 shows smaller charge transfer resistance and higher capacity of 217 mA h g(-1) because carbon coating retains the porous structure and enhances the electrical conductivity. PMID:25932749

  6. Effect of Transition Metal Ordering on the Electronic Properties of LiNi1 - y - xCoyMnxO2 Cathode Materials for Li-ion Batteries

    NASA Astrophysics Data System (ADS)

    Longo, Roberto; Kong, Fantai; Kc, Santosh; Yeon, Dong-Hee; Yoon, Jaegu; Park, Jin-Hwan; Doo, Seok-Kwang; Cho, Kyeongjae; MSL Team; SAIT Team

    2015-03-01

    Current Li-ion batteries use layered oxides as cathode materials, specially LiCoO2 or LiNi1 - y - xCoyMnxO2(NCM), and graphite as anode. Co layered oxides suffer from the high cost and toxicity of cobalt, together with certain instability at high operational temperatures. To overcome these difficulties, the synthesis of novel materials composed of layered oxides with different sets of Transition Metals (TM) has become the most successful way to solve the particular drawbacks of every single-oxide family. Although layered materials can deliver larger capacity than other families of cathode materials, the energy density has yet to be increased in order to match the expectations deposited on the NCM oxides. To acquire a high capacity, they need to be cycled at high operational voltages, resulting in voltage and capacity fading over a large number of cycles. In this work, we examine the phase diagram of the Li-Ni-Co-Mn-O system and the effect of TM ordering on the electronic properties of NCM cathode materials, using density-functional theory. Our findings will provide conceptual guidance in the experimental search for the mechanisms driving the voltage and capacity fading of the NCM family of cathode materials, in an attempt to solve such structural instability problems and, thus, improving the performance of the NCM cathode materials. This work was supported by Samsung GRO project.

  7. Preliminary study of structural changes in Li2MnSiO4 cathode material during electrochemical reaction

    NASA Astrophysics Data System (ADS)

    Świętosławski, Michał; Molenda, Marcin; Gajewska, Marta

    2016-06-01

    In this paper, we present exsitu observations of a structure of particular Li2MnSiO4 grains at different states of charge (SOC). The goal of these studies is structural analysis of Li2MnSiO4 cathode material for Li-ion batteries at different stages of electrochemical reaction using transmission electron microscopy. Performed analysis suggests that amorphization process of Li2MnSiO4 is not directly connected with lithium ions deintercalation but with additional electrochemical reactions running in the working cell.

  8. Electrical contacts between cathodes and metallic interconnects in solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Yang, Zhenguo; Xia, Guanguang; Singh, Prabhakar; Stevenson, Jeffry W.

    In this work, simulated cathode/interconnect structures were used to investigate the effects of different contact materials on the contact resistance between a strontium doped lanthanum ferrite cathode and a Crofer22 APU interconnect. Among the materials studied, Pt, which has a prohibitive cost for the application, demonstrated the best performance as a contact paste. For the relatively cost-effective perovskites, the contact ASR was found to depend on their electrical conductivity, scale growth on the metallic interconnect, and interactions between the contact material and the metallic interconnect or particularly the scale grown on the interconnect. Manganites appeared to promote manganese-containing spinel interlayer formation that helped minimize the increase of contact ASR. Chromium from the interconnects reacted with strontium in the perovskites to form SrCrO 4. An improved performance was achieved by application of a thermally grown (Mn,Co) 3O 4 spinel protection layer on Crofer22 APU that dramatically minimized the contact resistance between the cathodes and interconnects.

  9. Barium Doped Li2FeSiO4 Cathode Material for Li-Ion Secondary Batteries.

    PubMed

    Kim, Cheong; Yoo, Gi Won; Son, Jong Tae

    2015-11-01

    Barium-doped Li2Fe(1-x)Ba(x)SiO4 (x = 0, 0.01) cathode materials were synthesized by the sol-gel and electrospinning processes. The structures of the samples were confirmed by X-ray diffraction and Fourier transform infrared spectroscopy. The sizes and the morphologies of the particles and nanofibers were observed by field emission scanning electron microscopy and atomic force microscopy. The initial discharge capacity of Li2FeSiO4 particles was 28 mAh/g, Li2FeSiO4 nanofibers and barium (Ba)-doped Li2FeSiO4 nanofibers showed the discharge capacities of 78 and 85 mAh/g, respectively. The lithium-ion diffusion coefficients of Li2FeSiO4 particles, Li2FeSiO4 nanofibers and Ba-doped Li2FeSiO4 nanofibers were calculated 5.15 x 10-(16), 3.52 x 10(-16), and 2.27 x 10(-15) cm2/s, respectively. The Ba-doped Li2FeSiO4 cathode material showed the highest lithium-ion diffusion coefficient, and its electrochemical properties were better than that of the pristine material. PMID:26726598

  10. Tuning charge-discharge induced unit cell breathing in layer-structured cathode materials for lithium-ion batteries

    SciTech Connect

    Zhou, Yong-Ning; Ma, Jun; Hu, Enyuan; Yu, Xiqian; Gu, Lin; Nam, Kyung-Wan; Chen, Liquan; Wang, Zhaoxiang; Yang, Xiao-Qing

    2014-12-18

    For LiMO2 (M=Co, Ni, Mn) cathode materials, lattice parameters, a(b), contract during charge. Here we report such changes in opposite directions for lithium molybdenum trioxide (Li2MoO3). A ‘unit cell breathing’ mechanism is proposed based on crystal and electronic structural changes of transition metal oxides during charge-discharge. Metal–metal bonding is used to explain such ‘abnormal’ behaviour and a generalized hypothesis is developed. The expansion of the metal-metal bond becomes the controlling factor for a(b) evolution during charge, in contrast to the shrinking metal-oxygen bond as controlling factor in ‘normal’ materials. The cation mixing caused by migration of molybdenum ions at higher oxidation state provides the benefits of reducing the c expansion range in the early stage of charging and suppressing the structure collapse at high voltage charge. These results may open a new strategy for designing layered cathode materials for high energy density lithium-ion batteries.

  11. Electrospun V2O5 nanostructures with controllable morphology as high-performance cathode materials for lithium-ion batteries.

    PubMed

    Wang, Heng-guo; Ma, De-long; Huang, Yun; Zhang, Xin-bo

    2012-07-16

    Porous V(2)O(5) nanotubes, hierarchical V(2)O(5) nanofibers, and single-crystalline V(2)O(5) nanobelts were controllably synthesized by using a simple electrospinning technique and subsequent annealing. The mechanism for the formation of these controllable structures was investigated. When tested as the cathode materials in lithium-ion batteries (LIBs), the as-formed V(2)O(5) nanostructures exhibited a highly reversible capacity, excellent cycling performance, and good rate capacity. In particular, the porous V(2)O(5) nanotubes provided short distances for Li(+)-ion diffusion and large electrode-electrolyte contact areas for high Li(+)-ion flux across the interface; Moreover, these nanotubes delivered a high power density of 40.2 kW kg(-1) whilst the energy density remained as high as 201 W h kg(-1), which, as one of the highest values measured on V(2)O(5)-based cathode materials, could bridge the performance gap between batteries and supercapacitors. Moreover, to the best of our knowledge, this is the first preparation of single-crystalline V(2)O(5) nanobelts by using electrospinning techniques. Interestingly, the beneficial crystal orientation provided improved cycling stability for lithium intercalation. These results demonstrate that further improvement or optimization of electrochemical performance in transition-metal-oxide-based electrode materials could be realized by the design of 1D nanostructures with unique morphologies. PMID:22689094

  12. Tuning charge–discharge induced unit cell breathing in layer-structured cathode materials for lithium-ion batteries

    DOE PAGESBeta

    Zhou, Yong-Ning; Ma, Jun; Hu, Enyuan; Yu, Xiqian; Gu, Lin; Nam, Kyung -Wan; Chen, Liquan; Wang, Zhaoxiang; Yang, Xiao -Qing

    2014-11-18

    Through a systematic study of lithium molybdenum trioxide (Li2MoO3), a new ‘unit cell breathing’ mechanism is introduced based on both crystal and electronic structural changes of transition metal oxide cathode materials during charge–discharge: For widely used LiMO2 (M = Co, Ni, Mn), lattice parameters, a and b, contracts during charge. However, for Li2MoO3, such changes are in opposite directions. Metal–metal bonding is used to explain such ‘abnormal’ behaviour and a generalized hypothesis is developed. The expansion of M–M bond becomes the controlling factor for a(b) evolution during charge, in contrast to the shrinking M–O as controlling factor in ‘normal’ materials.more » The cation mixing caused by migration of Mo ions at higher oxidation state provides the benefits of reducing the c expansion range in early stage of charging and suppressing the structure collapse at high voltage charge. These results open a new strategy for designing and engineering layered cathode materials for high energy density lithium-ion batteries.« less

  13. Tuning charge–discharge induced unit cell breathing in layer-structured cathode materials for lithium-ion batteries

    SciTech Connect

    Zhou, Yong-Ning; Ma, Jun; Hu, Enyuan; Yu, Xiqian; Gu, Lin; Nam, Kyung -Wan; Chen, Liquan; Wang, Zhaoxiang; Yang, Xiao -Qing

    2014-11-18

    Through a systematic study of lithium molybdenum trioxide (Li2MoO3), a new ‘unit cell breathing’ mechanism is introduced based on both crystal and electronic structural changes of transition metal oxide cathode materials during charge–discharge: For widely used LiMO2 (M = Co, Ni, Mn), lattice parameters, a and b, contracts during charge. However, for Li2MoO3, such changes are in opposite directions. Metal–metal bonding is used to explain such ‘abnormal’ behaviour and a generalized hypothesis is developed. The expansion of M–M bond becomes the controlling factor for a(b) evolution during charge, in contrast to the shrinking M–O as controlling factor in ‘normal’ materials. The cation mixing caused by migration of Mo ions at higher oxidation state provides the benefits of reducing the c expansion range in early stage of charging and suppressing the structure collapse at high voltage charge. These results open a new strategy for designing and engineering layered cathode materials for high energy density lithium-ion batteries.

  14. Cathode material comparison of thermal runaway behavior of Li-ion cells at different state of charges including over charge

    NASA Astrophysics Data System (ADS)

    Mendoza-Hernandez, Omar Samuel; Ishikawa, Hiroaki; Nishikawa, Yuuki; Maruyama, Yuki; Umeda, Minoru

    2015-04-01

    The analysis of Li-ion secondary cells under outstanding conditions, as overcharge and high temperatures, is important to determine thermal abuse characteristics of electroactive materials and precise risk assessments on Li-ion cells. In this work, the thermal runaway behavior of LiCoO2 and LiMn2O4 cathode materials were compared at different state of charges (SOCs), including overcharge, by carrying out accelerating rate calorimetry (ARC) measurements using 18650 Li-ion cells. Onset temperatures of self-heating reactions and thermal runaway behavior were identified, and by using these onset points thermal mapping plots were made. We were able to identify non-self-heating, self-heating and thermal runaway regions as a function of state of charge and temperature. The cell using LiMn2O4 cathode material was found to be more thermally stable than the cell using LiCoO2. In parallel with the ARC measurements, the electrochemical behavior of the cells was monitored by measuring the OCV and internal resistance of the cells. The electrochemical behavior of the cells showed a slightly dependency on SOC.

  15. Synthesis of FePO{sub 4} cathode material for lithium ion batteries by a sonochemical method

    SciTech Connect

    Okawa, Hirokazu Yabuki, Junpei; Kawamura, Youhei; Arise, Ichiro; Sato, Mineo

    2008-05-06

    Hydrated amorphous FePO{sub 4} was synthesized by a sonochemical reaction method, in which a solution of (NH{sub 4}){sub 2}HPO{sub 4} and FeSO{sub 4}.7H{sub 2}O was irradiated by an ultrasonic wave. From this material, two kinds of cathode materials were easily prepared: (1) an amorphous sample prepared by heating at 350 deg. C and (2) a crystalline sample prepared by heating at 700 deg. C. Both samples consisted of homogeneous sub-micron particles. The amorphous sample of FePO{sub 4} exhibited high discharge capacities with more than 100 mAh g{sup -1} in the range of 3.9-2.0 V versus Li/Li{sup +} at a current rate of 0.2 C. The sonochemical synthesis proposed herein has the following advantages: no use of oxidation agents for production of trivalent iron ions, reduction in reaction time, control of particle size, and enlargement in surface area for the preparation of the cathode material.

  16. Effect of surfactants on the electrochemical behavior of LiFePO4 cathode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Bazzi, K.; Mandal, B. P.; Nazri, M.; Naik, V. M.; Garg, V. K.; Oliveira, A. C.; Vaishnava, P. P.; Nazri, G. A.; Naik, R.

    2014-11-01

    The application of lithium iron phosphate as positive electrode material for lithium ion batteries has been challenged by its poor electronic conductivity. To improve its conductivity and electrochemical performance, we have synthesized LiFePO4/C composite cathode materials by sol gel technique using long chain fatty acids, such as, lauric, myristic, and oleic acids, as surfactants for carbon coating. The phase purity of the three LiFePO4/C composites was confirmed by X-ray diffraction. The Raman spectroscopy, scanning electron microscopy and transmission electron microscopy measurements show that the surfactants coat the LiFePO4 particles with carbon with varying degree of uniformity depending on the surfactant used. The sample prepared in presence of lauric acid shows smaller particle size and the lowest charge transfer resistance, higher Li-ion diffusion coefficient, higher discharge capacity (∼155 mAh g-1 at C/3 rate), better rate capability and cyclic stability compared to the other two samples. We found the smaller particle size, uniformity of carbon coating, reduced agglomeration, and a lower amount of Fe3+ impurity phase in the samples to be major contributing factors for better electrochemical properties in the LiFePO4/C cathode material.

  17. Thermoelectric Properties of Selenides Spinels

    NASA Technical Reports Server (NTRS)

    Snyder, G.; Caillat, T.; Fleurial, J-P.

    2000-01-01

    Many compounds with the spinel structure type have been analyzed for their thermoelectric properties. Published data was used to augment experimental results presented here to select promising thermoelectric spinels.

  18. Rugged spinel optics for space based imaging systems

    NASA Astrophysics Data System (ADS)

    Bayya, Shyam; Villalobos, Guillermo; Hunt, Michael; Kim, Woohong; Plunkett, Simon; Sanghera, Jasbinder

    2016-05-01

    Space environment is very harsh for optical systems. Currently available optical materials for space applications are susceptible to surface and bulk damage due to high-speed impacts from dust and debris found in the space environment. Impacts lead to surface pitting and fracturing that may compromise structural integrity and degrade the optical performance of imaging systems. We are developing polycrystalline spinel as a rugged optics material. With its 3x hardness and 5x strength, as compared to BK7 glass, spinel is a very promising optical material for space imaging applications. Spinel's broad transmission from 160 nm to 5000 nm will also enable multispectral imaging from ultraviolet to midwave infrared.

  19. Effect of temperature of Li2O-Al2O3-TiO2-P2O5 solid-state electrolyte coating process on the performance of LiNi0.5Mn1.5O4 cathode materials

    NASA Astrophysics Data System (ADS)

    Deng, Yu-Feng; Zhao, Shi-Xi; Xu, Ya-Hui; Nan, Ce-Wen

    2015-11-01

    Electrochemical performance of spinel LiNi0.5Mn1.5O4 (LNMO) at elevated temperature is improved by solid-state electrolyte Li2O-Al2O3-TiO2-P2O5 (LATP) coating. Crystallinity and thickness of coatings are controlled by adjusting the coating process at two different temperatures (550 and 650 °C). 2.0 wt.% LATP-modified LNMO cathode materials obtained at 650 °C exhibits remarkably promoted electrochemical performance compared to that of the pristine one in terms of cycling and rate ability at 55 °C. The enhanced performance of the surface-modified samples can be accounted for the suppressed side reactions between the cathode materials and electrolyte solution. What is more important is that LATP cannot only protect the active materials from electrolyte solution but also improve Li+ mobility. The higher crystallinity of glass-ceramic LATP coating layer with thinner thickness implies more unobstructed, stable and shorter diffusion path of Li+ transport. It is found that the coating process is in favor of the disordered to ordered phase transition, implying that the heating process of coating plays a role of anneal as well.

  20. Electrochemical properties of large-sized pouch-type lithium ion batteries with bio-inspired organic cathode materials

    NASA Astrophysics Data System (ADS)

    Yeo, Jae-Seong; Yoo, Eun-Ji; Ha, Sang-Hyeon; Cheong, Dong-Ik; Cho, Sung-Baek

    2016-05-01

    To investigate the feasibility of scaling up bio-inspired organic materials as cathode materials in lithium ion batteries, large-sized pouch cells are successfully prepared via tape casting using lumichrome with an alloxazine structure and aqueous styrene butadiene rubber-carboxymethyl cellulose (SBR-CMC) binders. A battery module with a two-in-series, six-in-parallel (2S6P) configuration is also successfully fabricated and is able to power blue LEDs (850 mW). Lumichrome shows no structural changes during the fabrication processes used to produce the positive electrode. The large-sized pouch cells show two sets of cathodic and anodic peaks with average potentials of 2.58 V and 2.26 V vs. Li/Li+, respectively. The initial discharge capacities are 142 mAh g-1 and 148 mAh g-1 for ethylene carbonate-dimethyl carbonate (EC-DMC) and tetraethylene glycol dimethyl ether (TEGDME) electrolytes, respectively, similar to that of a coin cell (149 mAh g-1). The EC-DMC-injected pouch cells exhibit higher rate performance and cyclability than the TEGDME-injected ones. The TEGDME electrolyte is not suitable for lithium metal anodes because of electrolyte decomposition and subsequent cell swelling.

  1. Iron-rich nanoparticle encapsulated, nitrogen doped porous carbon materials as efficient cathode electrocatalyst for microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Lu, Guolong; Zhu, Youlong; Lu, Lu; Xu, Kongliang; Wang, Heming; Jin, Yinghua; Jason Ren, Zhiyong; Liu, Zhenning; Zhang, Wei

    2016-05-01

    Developing efficient, readily available, and sustainable electrocatalysts for oxygen reduction reaction (ORR) in neutral medium is of great importance to practical applications of microbial fuel cells (MFCs). Herein, a porous nitrogen-doped carbon material with encapsulated Fe-based nanoparticles (Fe-Nx/C) has been developed and utilized as an efficient ORR catalyst in MFCs. The material was obtained through pyrolysis of a highly porous organic polymer containing iron(II) porphyrins. The characterizations of morphology, crystalline structure and elemental composition reveal that Fe-Nx/C consists of well-dispersed Fe-based nanoparticles coated by N-doped graphitic carbon layer. ORR catalytic performance of Fe-Nx/C has been evaluated through cyclic voltammetry and rotating ring-disk electrode measurements, and its application as a cathode electrocatalyst in an air-cathode single-chamber MFC has been investigated. Fe-Nx/C exhibits comparable or better performance in MFCs than 20% Pt/C, displaying higher cell voltage (601 mV vs. 591 mV), maximum power density (1227 mW m-2 vs. 1031 mW m-2) and Coulombic efficiency (50% vs. 31%). These findings indicate that Fe-Nx/C is more tolerant and durable than Pt/C in a system with bacteria metabolism and thus holds great potential for practical MFC applications.

  2. Recovery of valuable metals from cathodic active material of spent lithium ion batteries: Leaching and kinetic aspects.

    PubMed

    Meshram, Pratima; Pandey, B D; Mankhand, T R

    2015-11-01

    This work is focussed on the processing of cathodic active material of spent lithium ion batteries (LIBs) to ensure resource recovery and minimize environmental degradation. The sulfuric acid leaching of metals was carried out for the recovery of all the valuable metals including nickel and manganese along with the frequently targeted metals like lithium and cobalt. The process parameters such as acid concentration, pulp density, time and temperature for the leaching of metals from the cathode powder containing 35.8% Co, 6.5% Li, 11.6% Mn and 10.06% Ni, were optimized. Results show the optimized leach recovery of 93.4% Li, 66.2% Co, 96.3% Ni and 50.2% Mn when the material was leached in 1M H2SO4 at 368 K and 50 g/L pulp density for 240 min. The need of a reductant for improved recovery of cobalt and manganese has been explained by the thermodynamic analysis (Eh-pH diagram) for these metals. Leaching of the valuable metals was found to follow the logarithmic rate law controlled by surface layer diffusion of the lixiviant reacting with the particles. The mode of leaching of the metals from the spent LIBs was further examined by chemical analysis of the samples at various stage of processing which was further corroborated by characterizing the untreated sample and the leach residues by XRD phase identification and the SEM-EDS studies. PMID:26087645

  3. Optimization of a microbial fuel cell for wastewater treatment using recycled scrap metals as a cost-effective cathode material.

    PubMed

    Lefebvre, Olivier; Tan, Zi; Shen, Yujia; Ng, How Y

    2013-01-01

    Microbial fuel cell (MFC) for wastewater treatment is still hindered by the prohibitive cost of cathode material, especially when platinum is used to catalyze oxygen reduction. In this study, recycled scrap metals could be used efficiently as cathode material in a specially-designed MFC. In terms of raw power, the scrap metals ranked as follows: W/Co > Cu/Ni > Inconel 718 > carpenter alloy; however, in terms of cost and long term stability, Inconel 718 was the preferred choice. Treatment performance--assessed on real and synthetic wastewater--was considerably improved either by filling the anode compartment with carbon granules or by operating the MFC in full-loop mode. The latter option allowed reaching 99.7% acetate removal while generating a maximum power of 36 W m(-3) at an acetate concentration of 2535 mg L(-1). Under these conditions, the energy produced by the system averaged 0.1 kWh m(-3) of wastewater treated. PMID:23138054

  4. Understanding local degradation of cycled Ni-rich cathode materials at high operating temperature for Li-ion batteries

    SciTech Connect

    Hwang, Sooyeon; Kim, Dong Hyun; Chung, Kyung Yoon; Chang, Wonyoung

    2014-09-08

    We utilize transmission electron microscopy in conjunction with electron energy loss spectroscopy to investigate local degradation that occurs in Li{sub x}Ni{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} cathode materials (NCA) after 30 cycles with cutoff voltages of 4.3 V and 4.8 V at 55 °C. NCA has a homogeneous crystallographic structure before electrochemical reactions; however, we observed that 30 cycles of charge/discharge reactions induced inhomogeneity in the crystallographic and electronic structures and also introduced porosity particularly at surface area. These changes were more noticeable in samples cycled with higher cutoff voltage of 4.8 V. Effect of operating temperature was further examined by comparing electronic structures of oxygen of the NCA particles cycled at both room temperature and 55 °C. The working temperature has a greater impact on the NCA cathode materials at a cutoff voltage of 4.3 V that is the practical the upper limit voltage in most applications, while a cutoff voltage of 4.8 V is high enough to cause surface degradation even at room temperature.

  5. Hollow spherical carbonized polypyrrole/sulfur composite cathode materials for lithium/sulfur cells with long cycle life

    NASA Astrophysics Data System (ADS)

    Wang, Zhongbao; Zhang, Shichao; Zhang, Lan; Lin, Ruoxu; Wu, Xiaomeng; Fang, Hua; Ren, Yanbiao

    2014-02-01

    Hollow carbonized polypyrrole (PPy) spheres are synthesized using poly(methyl methacrylate-ethyl acrylate-acrylic acid) latex spheres as sacrificial templates. The hollow spherical carbonized PPy/sulfur composite cathode materials are prepared by heating the mixture of hollow carbonized PPy spheres and element sulfur at 155 °C for 24 h. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations show the hollow structures of the carbonized PPy spheres and the homogeneous distribution of sulfur on the carbonized PPy shells. The hollow spherical carbonized PPy/sulfur composite with 60.9 wt.% S shows high specific capacity and excellent cycling stability when used as the cathode materials in lithium/sulfur cells, whose initial specific discharge capacity reaches as high as 1320 mA h g-1 and the reversible discharge capacity retains 758 mA h g-1 after 400 cycles at 0.2C. The excellent electrochemical properties benefit from the hollow structures and the flexible shells of the carbonized PPy spheres.

  6. First-principles investigation of the structural characteristics of LiMO2 cathode materials for lithium secondary batteries

    NASA Astrophysics Data System (ADS)

    Kim, Yongseon

    2015-11-01

    The structural features related to the defects of LiMO2 (M = Ni, Co, Mn) cathode materials for lithium secondary batteries were investigated by a simulation of phase diagrams based on first-principle calculations. Crystal models with various types of point defects were designed and dealt with as independent phases, which enabled an examination of the thermodynamic stability of the defects. A perfect phase without defects appeared to be the most stable for LiCoO2, whereas the formation of Li vacancies, O vacancies, and antisites between Li and Ni was thermodynamically unavoidable for LiNiO2. The introduction of both Co and Mn in LiNiO2 was effective in reducing the formation of point defects, but increasing the relative amount of Mn was undesirable because the antisite defect remained stable with Mn doping. The simulation showed good agreement with the experimental data and previous reports. Therefore, the method and the results of this study are expected to be useful for examining the synthesis, structure and related properties of layer-structured cathode materials.

  7. The influence of reduced graphene oxide on electrical conductivity of LiFePO4-based composite as cathode material

    NASA Astrophysics Data System (ADS)

    Arifin, Muhammad; Aimon, Akfiny Hasdi; Winata, Toto; Abdullah, Mikrajuddin; Iskandar, Ferry

    2016-02-01

    LiFePO4 is fascinating cathode active materials for Li-ion batteries application because of their high electrochemical performance such as a stable voltage at 3.45 V and high specific capacity at 170 mAh.g-1. However, their low intrinsic electronic conductivity and low ionic diffusion are still the hindrance for their further application on Li-ion batteries. Therefore, the efforts to improve their conductivity are very important to elevate their prospecting application as cathode materials. Herein, we reported preparation of additional of reduced Graphene Oxide (rGO) into LiFePO4-based composite via hydrothermal method and the influence of rGO on electrical conductivity of LiFePO4-based composite by varying mass of rGO in composition. Vibration of LiFePO4-based composite was detected on Fourier Transform Infrared Spectroscopy (FTIR) spectra, while single phase of LiFePO4 nanocrystal was observed on X-Ray Diffraction (XRD) pattern, it furthermore, Scanning Electron Microscopy (SEM) images showed that rGO was distributed around LiFePO4-based composite. Finally, the 4-point probe measurement result confirmed that the optimum electrical conductivity is in additional 2 wt% rGO for range 1 to 2 wt% rGO.

  8. Enhancement of electrochemical behavior of nanostructured LiFePO4/Carbon cathode material with excess Li

    NASA Astrophysics Data System (ADS)

    Bazzi, K.; Nazri, M.; Naik, V. M.; Garg, V. K.; Oliveira, A. C.; Vaishnava, P. P.; Nazri, G. A.; Naik, R.

    2016-02-01

    We have synthesized carbon coated LiFePO4 (C-LiFePO4) and C-Li1.05FePO4 with 5 mol% excess Li via sol-gel method using oleic acid as a source of carbon for enhancing electronic conductivity and reducing the average particle size. Although the phase purity of the crystalline samples was confirmed by x-ray diffraction (XRD), the 57Fe Mössbauer spectroscopy analyses show the presence of ferric impurity phases in both stoichiometric and non-stoichiometric C-LiFePO4 samples. Transmission electron microscopy measurements show nanosized C-LiFePO4 particles uniformly covered with carbon, with average particle size reduced from ∼100 nm to ∼50 nm when excess lithium is used. Electrochemical measurements indicate a lower charge transfer resistance and better electrochemical performance for C-Li1.05FePO4 compared to that of C-LiFePO4. The aim of this work is to systematically analyze the nature of impurities formed during synthesis of LiFePO4 cathode material, and their impact on electrochemical performance. The correlation between the morphology, charge transfer resistance, diffusion coefficient and electrochemical performance of C-LiFePO4 and C- Li1.05FePO4 cathode materials are discussed.

  9. Transmission electron microscopy (TEM) investigations of Mn-oxide rich cathodic material from spent disposable alkaline batteries

    SciTech Connect

    Krekeler, Mark P.S.

    2008-11-15

    Transmission electron microscopy (TEM) techniques were used to investigate the spent cathodic material of a single common brand of disposable alkaline batteries. Mn-oxide particles are anhedral and irregular in shape and compose an estimated 99-95% of the <10 {mu}m size fraction of sample material. Diameters of particles vary widely and typically are between 50 nm and 3 {mu}m; however, most particles are approximately 200-400 nm in diameter. Chemical composition varies for Mn-oxide particles with concentrations being SiO{sub 2} (0.00-1.52 wt%), TiO{sub 2} (0.49-4.58 wt%), MnO (65.85-92.06 wt%), ZnO (1.00-7.53 wt%), K{sub 2}O (4.97-20.48 wt%) and SO{sub 3} (0.43-2.21 wt%). Discrete prismatic zinc crystals occur and vary from a maximum of approximately 0.8 {mu}m long x 0.15 {mu}m wide, to 100 nm long x 20 nm wide. Titanium metal was also observed in samples and composes approximately 0.25-1.0% of the <10 {mu}m size fraction of sample material. Results of this study suggest that battery components may be recycled in some special applications. Examples are low energy-low material requirement products such as paint pigments and Zn nanoparticles. This investigation provides detailed constraints on the nature of spent cathodic materials to improve existing recycling methods and develop new technologies.

  10. Electron beam treatment of non-conducting materials by a fore-pump-pressure plasma-cathode electron beam source

    NASA Astrophysics Data System (ADS)

    Burdovitsin, V. A.; Klimov, A. S.; Medovnik, A. V.; Oks, E. M.

    2010-10-01

    In the irradiation of an insulated target by an electron beam produced by a plasma-cathode electron beam source operating in the fore-vacuum pressure range (5-15 Pa), the target potential is much lower than the electron beam energy, offering the possibility of direct electron treatment of insulating materials. It is found that in the electron beam irradiation of a non-conducting target in a moderately high pressure range, the electron charge on the target surface is neutralized mainly by ions from a volume discharge established between the negatively charged target surface and the grounded walls of the vacuum chamber. This allows the possibility of direct electron beam treatment (heating, melting, welding) of ceramics and other non-conducting and semiconductor materials.

  11. The structural and chemical origin of the oxygen redox activity in layered and cation-disordered Li-excess cathode materials.

    PubMed

    Seo, Dong-Hwa; Lee, Jinhyuk; Urban, Alexander; Malik, Rahul; Kang, ShinYoung; Ceder, Gerbrand

    2016-07-01

    Lithium-ion batteries are now reaching the energy density limits set by their electrode materials, requiring new paradigms for Li(+) and electron hosting in solid-state electrodes. Reversible oxygen redox in the solid state in particular has the potential to enable high energy density as it can deliver excess capacity beyond the theoretical transition-metal redox-capacity at a high voltage. Nevertheless, the structural and chemical origin of the process is not understood, preventing the rational design of better cathode materials. Here, we demonstrate how very specific local Li-excess environments around oxygen atoms necessarily lead to labile oxygen electrons that can be more easily extracted and participate in the practical capacity of cathodes. The identification of the local structural components that create oxygen redox sets a new direction for the design of high-energy-density cathode materials. PMID:27325096

  12. Synthesis of a LiFePO4/C cathode material by using a high-energy nano mill

    NASA Astrophysics Data System (ADS)

    Islam, Mobinul; Yoon, Man-Soon; Ur, Soon-Chul

    2015-07-01

    Olivine lithium iron phosphate (LiFePO4) is a promising cathode material for Li-ion battery. A temperature around 700 - 800 ℃ is generally required to prepare LiFePO4 powder with good crystallinity. The LiFePO4 materials are synthesized via a solid-state method by using a highenergy nano mill (HENM). The conventional ball-milling process is also conducted for the same material for a comparative study. The effect of the precursor's mixing processes on the synthesis temperature of LiFePO4 is investigated in this study. The required reaction temperature of LiFePO4 is 432 ℃ for the HENM process and 480 ℃ for the ball-mill process as found from the differential scanning calorimetry (DSC) results. The HENM process improves the reaction activity and the homogeneity of the materials used throughout process and lowers the reaction temperature as compared with the conventional ball-mill process. The milled powders are characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The sample synthesized by using the HENM process exhibits a discharge capacity of 136 mAhg -1 at 0.1 C rate. The results in this study indicate that the HENM process is a substantial and promising process for LiFePO4 cathode preparation owing to its short fabrication time and ability to improve the reaction condition. A HENM can be used to promote formation of LiFePO4 at lower temperatures.

  13. Electroconductive properties in doped spinel oxides

    NASA Astrophysics Data System (ADS)

    Dwivedi, Shalini; Sharma, Ramesh; Sharma, Yamini

    2014-11-01

    The application of spinel oxides as transparent conducting oxides (TCOs) in optoelectronic devices as a substitute for ZnO is attracting attention in the recent years. Despite attractive photo-luminescence properties of zinc aluminate and zinc gallate, relatively little work has been done to interpret the optical response of spinel oxides on the basis of energy band structures. We present the electronic properties of ZnX2O4 (X = Al, Ga, In) calculated by the full potential linearized augmented plane wave method. Optical properties such as absorption coefficient and reflectivity are calculated and interpreted in terms of energy bands and density of states. Enhancement in optical properties was studied for Li and Mn ions doped in the ZnGa2O4 matrix. The main features in the experimentally observed photoluminescence spectra for doped and undoped ZnGa2O4 have been verified through the optical parameters. The transparence of spinel oxides to UV radiations is also clearly illustrated in the reflectivity vs. energy curves. At very small wavelengths the oxides may be used as reflective coating materials. Transport properties of the zinc spinel oxides have been investigated for the first time, and are found to have high Seebeck coefficients, high electrical conductivity and low thermal conductivity, with high value of figure of merit ZT ∼ 0.8. The study of vibrational and thermodynamic properties by the projector augmented wave method confirms the dynamic stability of the doped and undoped spinel oxides. Zinc spinel oxides are found to be p-type semiconductors with an optimum value of band gap ∼2-3 eV and appear to meet the conditions of low resistivity and high transparency (>80%) for state-of-art TCOs.

  14. Investigating the reversibility of structural modifications of LixNiyMnzCo1-y-zO₂ cathode materials during initial charge/discharge, at multiple length scales

    DOE PAGESBeta

    Hwang, Sooyeon; Bak, Seong -Min; Kim, Seung Min; Chung, Kyung Yoon; Chang, Wonyoung

    2015-08-11

    In this work, we investigate the structural modifications occurring at the bulk, subsurface, and surface scales of LixNiyMnzCo1-y-zO₂ (NMC; y, z = 0.8, 0.1 and 0.4, 0.3, respectively) cathode materials during the initial charge/discharge. Various analytical tools, such as X-ray diffraction, selected-area electron diffraction, electron energy-loss spectroscopy, and high-resolution electron microscopy, are used to examine the structural properties of the NMC cathode materials at the three different scales. Cut-off voltages of 4.3 and 4.8 V are applied during the electrochemical tests as the normal and extreme conditions, respectively. The high-Ni-content NMC cathode materials exhibit unusual behaviors, which is deviate frommore » the general redox reactions during the charge or discharge. The transition metal (TM) ions in the high-Ni-content NMC cathode materials, which are mostly Ni ions, are reduced at 4.8 V, even though TMs are usually oxidized to maintain charge neutrality upon the removal of Li. It was found that any changes in the crystallographic and electronic structures are mostly reversible down to the sub-surface scale, despite the unexpected reduction of Ni ions. However, after the discharge, traces of the phase transitions remain at the edges of the NMC cathode materials at the scale of a few nanometers (i.e., surface scale). This study demonstrates that the structural modifications in NMC cathode materials are induced by charge as well as discharge at multiple length scales. These changes are nearly reversible after the first cycle, except at the edges of the samples, which should be avoided because these highly localized changes can initiate battery degradation.« less

  15. Cobalt based layered perovskites as cathode material for intermediate temperature Solid Oxide Fuel Cells: A brief review

    NASA Astrophysics Data System (ADS)

    Pelosato, Renato; Cordaro, Giulio; Stucchi, Davide; Cristiani, Cinzia; Dotelli, Giovanni

    2015-12-01

    Nowadays, the cathode is the most studied component in Intermediate Temperature-Solid Oxide Fuel Cells (IT-SOFCs). Decreasing SOFCs operating temperature implies slow oxygen reduction kinetics and large polarization losses. Double perovskites with general formula REBaCo2O5+δ are promising mixed ionic-electronic conductors, offering a remarkable enhancement of the oxygen diffusivity and surface exchange respect to disordered perovskites. In this review, more than 250 compositions investigated in the literature were analyzed. The evaluation was performed in terms of electrical conductivity, Area Specific Resistance (ASR), chemical compatibility with electrolytes and Thermal Expansion Coefficient (TEC). The most promising materials have been identified as those bearing the mid-sized rare earths (Pr, Nd, Sm, Gd). Doping strategies have been analyzed: Sr doping on A site promotes higher electrical conductivity, but worsen ASR and TECs; B-site doping (Fe, Ni, Mn) helps lowering TECs, but is detrimental for the electrochemical properties. A promising boost of the electrochemical activity is obtained by simply introducing a slight Ba under-stoichiometry. Still, the high sensitivity of the electrochemical properties against slight changes in the stoichiometry hamper a conclusive comparison of all the investigated compounds. Opportunities for an improvement of double perovskite cathodes performance is tentatively foreseen in combining together the diverse effective doping strategies.

  16. A preliminary investigation into the new class of lithium intercalating LiNiSiO4 cathode material

    NASA Astrophysics Data System (ADS)

    Jayaprakash, N.; Kalaiselvi, N.; Periasamy, P.

    2008-01-01

    A unique attempt to exploit silicate chemistry for a possible enhancement of the electrochemical properties of a lithium ion system via exploration of the novel category lithium intercalating LiNiSiO4 cathode has been made through the present study. A novel citric acid assisted modified sol-gel method (CAM sol-gel) has been adopted to synthesize the title compound with a formation temperature positioned well below 500 °C, as derived from thermal studies. A powder x-ray diffraction (PXRD) pattern evidenced the absence of undesirable peaks and confirmed the formation of a hexagonal lattice structure with enhanced crystallinity and phase purity, and the presence of uniformly distributed particles of ~200 nm size with well defined grain boundaries is obvious from the scanning electron microscopy (SEM) image of LiNiSiO4 material. Further, magic angle spinning (MAS) 7Li nuclear magnetic resonance (NMR) results from LiNiSiO4 confirmed the presence of a layered type of crystal arrangement. A cyclic voltammetry (CV) study performed on a LiNiSiO4 cathode revealed an excellent reversibility without any change in the peak position upon extended cycling, thus substantiating the structural stability upon progressive cycling.

  17. A preliminary investigation into the new class of lithium intercalating LiNiSiO(4) cathode material.

    PubMed

    Jayaprakash, N; Kalaiselvi, N; Periasamy, P

    2008-01-16

    A unique attempt to exploit silicate chemistry for a possible enhancement of the electrochemical properties of a lithium ion system via exploration of the novel category lithium intercalating LiNiSiO(4) cathode has been made through the present study. A novel citric acid assisted modified sol-gel method (CAM sol-gel) has been adopted to synthesize the title compound with a formation temperature positioned well below 500 °C, as derived from thermal studies. A powder x-ray diffraction (PXRD) pattern evidenced the absence of undesirable peaks and confirmed the formation of a hexagonal lattice structure with enhanced crystallinity and phase purity, and the presence of uniformly distributed particles of ∼200 nm size with well defined grain boundaries is obvious from the scanning electron microscopy (SEM) image of LiNiSiO(4) material. Further, magic angle spinning (MAS) (7)Li nuclear magnetic resonance (NMR) results from LiNiSiO(4) confirmed the presence of a layered type of crystal arrangement. A cyclic voltammetry (CV) study performed on a LiNiSiO(4) cathode revealed an excellent reversibility without any change in the peak position upon extended cycling, thus substantiating the structural stability upon progressive cycling. PMID:21817545

  18. The synergistic effect of inert oxide and metal fluoride dual coatings on advanced cathode materials for lithium ion battery applications.

    PubMed

    Park, Kwangjin; Lee, Byoung-Sun; Park, Jun-Ho; Hong, Suk-Gi

    2016-06-21

    The effect of Al2O3/LiF dual coatings on the electrochemical performance of over-lithiated layered oxide (OLO) has been investigated. A uniform coating of Al2O3 and LiF is obtained on the surface of the layered pristine material. The OLO with a dual Al2O3/LiF coating with a ratio of 1 : 1.5 exhibits excellent electrochemical performance. An initial discharge capacity of 265.66 mA h g(-1) is obtained at a C-rate of 0.1C. This capacity is approximately 15 mA h g(-1) higher than that of pristine OLO. The capacity retention (92.8% at the 50th cycle) is also comparable to that of pristine OLO (91.4% at the 50th cycle). Coating the cathode with a dual layer comprising Al2O3 and LiF leads to improved charging and discharging kinetics, and prevents direct contact between the cathode and the electrolyte. PMID:27233109

  19. Non-crystalline oligopyrene as a cathode material with a high-voltage plateau for sodium ion batteries

    NASA Astrophysics Data System (ADS)

    Han, Su Cheol; Bae, Eun Gyoung; Lim, Heatsal; Pyo, Myoungho

    2014-05-01

    Oligopyrene (OPr, 3-4 pyrene units) is chemically synthesized and used as a high-voltage organic cathode for sodium ion batteries (SIBs). OPr shows anion-dominant transport behaviors during redox-switching in NaClO4 electrolytes, indicating that, when implemented in SIBs, OPr can reversibly incorporate/release perchlorate anions for charge-balance. A composite film, in which OPr maintains a crystalline phase with a layered structure, shows a sloping charge-discharge (C-D) curve (discharge capacity = 42.5 mAh g-1 and average voltage = 2.9 V vs. Na/Na+ at 20 mA g-1), implying a large overpotential due to slow ClO4- diffusion through the crystalline phase. In contrast, a composite film containing amorphous OPr exhibits substantially reduced overpotential with a plateau potential at 3.5 V during discharge. An initial reversible capacity of 121.0 mAh g-1, which is close to one-electron transfer per pyrene unit, is decreased to 95.8 mAh g-1 during the first 10 C-D cycles, but is subsequently stabilized with a decreasing rate of 0.30 mAh g-1 per C-D cycle. The energy density of amorphous OPr (423 Wh kg-1 for the 1st discharge) is so large that it exceeds those of most inorganic-based cathode materials that have been reported thus far.

  20. FePO 4 nanoparticles supported on mesoporous SBA-15: Interesting cathode materials for Li-ion cells

    NASA Astrophysics Data System (ADS)

    Gerbaldi, C.; Meligrana, G.; Bodoardo, S.; Tuel, A.; Penazzi, N.

    Exploiting the properties of stability, low cost and low toxicity of iron phosphates, we have tried to enhance the performance of FePO 4 as cathode material for Li-ion cells. We adopted the strategy of obtaining FePO 4, via a typical preparation, onto the channels of an ordered mesoporous SBA-15 silica, a low cost mesoporous material commonly used in industry, which possesses larger pores, thicker walls and higher thermal stability as compared with other mesoporous silicas like MCM-41. Characterizations with ICP-AES, XRPD, BET and HRTEM suggest that the supported iron phosphate species, with loading amounts as high as 30 wt%, are located and dispersed in the mesopores of SBA-15. Iron phosphate can be reduced/oxidized more readily than the unsupported iron phosphate at room temperature, and in fact, cycling at C/10, the supported phosphate shows a utilization of 70% with respect to a value of 30% for the unsupported solid. The result is interesting from the scientific viewpoint but not suitable for application at the moment. Indeed, the amount of active material does not exceed 30% of the electrode mass and the total electrode capacity, though the active material is very efficient, is largely insufficient. Researches are being developed trying to increase the performances of the materials and also to eliminate the support after the dispersion of the active material.

  1. Dual-phase spinel MnCo2O4 and spinel MnCo2O4/nanocarbon hybrids for electrocatalytic oxygen reduction and evolution.

    PubMed

    Ge, Xiaoming; Liu, Yayuan; Goh, F W Thomas; Hor, T S Andy; Zong, Yun; Xiao, Peng; Zhang, Zheng; Lim, Suo Hon; Li, Bing; Wang, Xin; Liu, Zhaolin

    2014-08-13

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are essential reactions for energy-storage and -conversion devices relying on oxygen electrochemistry. High-performance, nonprecious metal-based hybrid catalysts are developed from postsynthesis integration of dual-phase spinel MnCo2O4 (dp-MnCo2O4) nanocrystals with nanocarbon materials, e.g., carbon nanotube (CNT) and nitrogen-doped reduced graphene oxide (N-rGO). The synergic covalent coupling between dp-MnCo2O4 and nanocarbons effectively enhances both the bifunctional ORR and OER activities of the spinel/nanocarbon hybrid catalysts. The dp-MnCo2O4/N-rGO hybrid catalysts exhibited comparable ORR activity and superior OER activity compared to commercial 30 wt % platinum supported on carbon black (Pt/C). An electrically rechargeable zinc-air battery using dp-MnCo2O4/CNT hybrid catalysts on the cathode was successfully operated for 64 discharge-charge cycles (or 768 h equivalent), significantly outperforming the Pt/C counterpart, which could only survive up to 108 h under similar conditions. PMID:25058393

  2. Synthesis and Electrochemical Studies of LiNi0.2Co0.8VO4 Cathode Material by Sol-Gel Method

    NASA Astrophysics Data System (ADS)

    Prakash, D.; Sanjeeviraja, C.

    2013-07-01

    Lithium nickel cobalt vanadate (LiNi0.2Co0.8VO4) cathode material was prepared by using sol-gel method. Rietveld refinement analysis of powder x-ray diffraction (PXRD) pattern confirmed the prepared compound having cubic structure and showed no evidence of secondary phase peaks. The field emission scanning microscopy (FESEM) image of the compound showed that the particles have submicron size. The x-ray photoelectron spectroscopy (XPS) results showed that the oxidation states of cobalt and vanadium was +3 and +5, respectively. The electrochemical performance of the cathode material was also performed.

  3. A new cathode material for super-valent battery based on aluminium ion intercalation and deintercalation.

    PubMed

    Wang, Wei; Jiang, Bo; Xiong, Weiyi; Sun, He; Lin, Zheshuai; Hu, Liwen; Tu, Jiguo; Hou, Jungang; Zhu, Hongmin; Jiao, Shuqiang

    2013-01-01

    Due to their small footprint and flexible siting, rechargeable batteries are attractive for energy storage systems. A super-valent battery based on aluminium ion intercalation and deintercalation is proposed in this work with VO2 as cathode and high-purity Al foil as anode. First-principles calculations are also employed to theoretically investigate the crystal structure change and the insertion-extraction mechanism of Al ions in the super-valent battery. Long cycle life, low cost and good capacity are achieved in this battery system. At the current density of 50 mAg(-1), the discharge capacity remains 116 mAhg(-1) after 100 cycles. Comparing to monovalent Li-ion battery, the super-valent battery has the potential to deliver more charges and gain higher specific capacity. PMID:24287676

  4. A fundamental study of chromium deposition on solid oxide fuel cell cathode materials

    NASA Astrophysics Data System (ADS)

    Tucker, Michael C.; Kurokawa, Hideto; Jacobson, Craig P.; De Jonghe, Lutgard C.; Visco, Steven J.

    Chromium contamination of metal oxides and SOFC cathode catalysts is studied in the range 700-1000 °C. Samples are exposed to a moist air atmosphere saturated with volatile Cr species in the presence and absence of direct contact between the sample and ferritic stainless steel powder. Chromium contamination of the samples is observed to occur via two separate pathways: surface diffusion from the stainless steel surface and vapor deposition from the atmosphere. Surface diffusion dominates in all cases. Surface diffusion is found to be a significant source of Cr contamination for LSM and LSCF at 700, 800, and 1000 °C. Vapor deposition of Cr onto LSCF was observed at each of these temperatures, but was not observed for LSM at 700 or 800 °C. Comparison of the behavior for LSM, LSCF, and single metal oxides suggests that Mn and Co, respectively, are responsible for the Cr contamination of these catalysts.

  5. New lithium iron pyrophosphate as 3.5 V class cathode material for lithium ion battery.

    PubMed

    Nishimura, Shin-ichi; Nakamura, Megumi; Natsui, Ryuichi; Yamada, Atsuo

    2010-10-01

    A new pyrophosphate compound Li(2)FeP(2)O(7) was synthesized by a conventional solid-state reaction, and its crystal structure was determined. Its reversible electrode operation at ca. 3.5 V vs Li was identified with the capacity of a one-electron theoretical value of 110 mAh g(-1) even for ca. 1 μm particles without any special efforts such as nanosizing or carbon coating. Li(2)FeP(2)O(7) and its derivatives should provide a new platform for related lithium battery electrode research and could be potential competitors to commercial olivine LiFePO(4), which has been recognized as the most promising positive cathode for a lithium-ion battery system for large-scale applications, such as plug-in hybrid electric vehicles. PMID:20831186

  6. Toward a stabilized lattice framework and surface structure of layered lithium-rich cathode materials with Ti modification.

    PubMed

    Wang, Sihui; Li, Yixiao; Wu, Jue; Zheng, Bizhu; McDonald, Matthew J; Yang, Yong

    2015-04-21

    Layered lithium-rich oxides have several serious shortcomings such as fast voltage fading and poor cyclic stability of energy density which greatly hinder their practical applications. Fabrication of a stable framework of layered lithium-rich oxides during charging-discharging is crucial for addressing the above problems. In this work, we show that Ti modification is a promising way to realize this target with bifunctional roles. For example, it is able to substitute Mn in the lattice framework and form a stable surface layer. It therefore leads to an improved retention of energy density of the Ti-modified Li1.2Mn0.54-xTixNi0.13Co0.13O2 (x = 0.04, 0.08, and 0.15) materials during cycling. The evolution of dQ/dV curves show that the layered/spinel phase transformation is suppressed owing to the introduction of strong Ti-O bonds in the framework. In addition, SEM, TEM, and EIS results confirm that a more uniform and stable interface layer is formed on Ti-modified Li1.2Mn0.54-xTixNi0.13Co0.13O2 (x = 0.04, 0.08, and 0.15) materials compared with the Ti-free counterpart. The stable interface layer on the lithium-rich oxides is also beneficial for further reducing side reactions, resulting in stable interface layer resistance. Therefore, the improved cycling performance of the material is due to both contribution of the more stable framework and enhanced electrode/electrolyte interface by Ti modification. PMID:25790778

  7. Cathodes - Technological review

    NASA Astrophysics Data System (ADS)

    Cherkouk, Charaf; Nestler, Tina

    2014-06-01

    Lithium cobalt oxide (LiCoO2) was already used in the first commercialized Li-ion battery by SONY in 1990. Still, it is the most frequently used cathode material nowadays. However, LiCoO2 is intrinsically unstable in the charged state, especially at elevated temperatures and in the overcharged state causing volume changes and transport limitation for high power batteries. In this paper, some technological aspects with large impact on cell performance from the cathode material point of view will be reviewed. At first it will be focused on the degradation processes and life-time mechanisms of the cathode material LiCoO2. Electrochemical and structural results on commercial Li-ion batteries recorded during the cycling will be discussed. Thereafter, advanced nanomaterials for new cathode materials will be presented.

  8. Facile molten salt synthesis of Li2NiTiO4 cathode material for Li-ion batteries.

    PubMed

    Wang, Yanming; Wang, Yajing; Wang, Fei

    2014-01-01

    Well-crystallized Li2NiTiO4 nanoparticles are rapidly synthesized by a molten salt method using a mixture of NaCl and KCl salts. X-ray diffraction pattern and scanning electron microscopic image show that Li2NiTiO4 has a cubic rock salt structure with an average particle size of ca. 50 nm. Conductive carbon-coated Li2NiTiO4 is obtained by a facile ball milling method. As a novel 4 V positive cathode material for Li-ion batteries, the Li2NiTiO4/C delivers high discharge capacities of 115 mAh g(-1) at room temperature and 138 mAh g(-1) and 50°C, along with a superior cyclability. PMID:24855459

  9. Study of the Durability of Doped Lanthanum Manganite and Cobaltite Cathode Materials under ''Real World'' Air Exposure Atmospheres

    SciTech Connect

    Singh, Prabhakar; Mahapatra, Manoj; Ramprasad, Rampi; Minh, Nguyen; Misture, Scott

    2014-11-30

    The overall objective of the program is to develop and validate mechanisms responsible for the overall structural and chemical degradation of lanthanum manganite as well as lanthanum ferrite cobaltite based cathode when exposed to “real world” air atmosphere exposure conditions during SOFC systems operation. Of particular interest are the evaluation and analysis of degradation phenomena related to and responsible for (a) products formation and interactions with air contaminants, (b) dopant segregation and oxide exolution at free surfaces, (c) cation interdiffusion and reaction products formation at the buried interfaces, (d) interface morphology changes, lattice transformation and the development of interfacial porosity and (e) micro-cracking and delamination from the stack repeat units. Reaction processes have been studied using electrochemical and high temperature materials compatibility tests followed by structural and chemical characterization. Degradation hypothesis has been proposed and validated through further experimentation and computational simulation.

  10. Atomic-Resolution Visualization of Distinctive Chemical Mixing Behavior of Ni, Co and Mn with Li in Layered Lithium Transition-Metal Oxide Cathode Materials

    SciTech Connect

    Yan, Pengfei; Zheng, Jianming; Lv, Dongping; Wei, Yi; Zheng, Jiaxin; Wang, Zhiguo; Kuppan, Saravanan; Yu, Jianguo; Luo, Langli; Edwards, Danny J.; Olszta, Matthew J.; Amine, Khalil; Liu, Jun; Xiao, Jie; Pan, Feng; Chen, Guoying; Zhang, Jiguang; Wang, Chong M.

    2015-07-06

    Capacity and voltage fading of layer structured cathode based on lithium transition metal oxide is closely related to the lattice position and migration behavior of the transition metal ions. However, it is scarcely clear about the behavior of each of these transition metal ions. We report direct atomic resolution visualization of interatomic layer mixing of transition metal (Ni, Co, Mn) and lithium ions in layer structured oxide cathodes for lithium ion batteries. Using chemical imaging with aberration corrected scanning transmission electron microscope (STEM) and DFT calculations, we discovered that in the layered cathodes, Mn and Co tend to reside almost exclusively at the lattice site of transition metal (TM) layer in the structure or little interlayer mixing with Li. In contrast, Ni shows high degree of interlayer mixing with Li. The fraction of Ni ions reside in the Li layer followed a near linear dependence on total Ni concentration before reaching saturation. The observed distinctively different behavior of Ni with respect to Co and Mn provides new insights on both capacity and voltage fade in this class of cathode materials based on lithium and TM oxides, therefore providing scientific basis for selective tailoring of oxide cathode materials for enhanced performance.

  11. First principle study of LiXS2 (X = Ga, In) as cathode materials for Li ion batteries

    NASA Astrophysics Data System (ADS)

    Feng-Ya, Rao; Fang-Hua, Ning; Li-Wei, Jiang; Xiang-Ming, Zeng; Mu-Sheng, Wu; Bo, Xu; Chu-Ying, Ouyang

    2016-02-01

    From first principle calculations, we demonstrate that LiXS2 (X = Ga, In) compounds have potential applications as cathode materials for Li ion batteries. It is shown that Li can be extracted from the LiXS2 lattice with relatively small volume change and the XS4 tetrahedron structure framework remains stable upon delithiation. The theoretical capacity and average intercalation potential of the LiGaS2 (LiInS2) cathode are 190.4 (144.2) mAh/g and 3.50 V (3.53 V). The electronic structures of the LiXS2 are insulating with band gaps of 2.88 eV and 1.99 eV for X = Ga and In, respectively. However, Li vacancies, which are formed through delithiation, change the electronic structure substantially from insulating to metallic structure, indicating that the electrical conductivities of the LiXS2 compounds should be good during cycling. Li ion migration energy barriers are also calculated, and the results show that Li ion diffusions in the LiXS2 compounds can be as good as those in the currently widely used electrode materials. Project supported by the National High Technology and Development Key Program, China (Grant No. 2015AA034201), the National Natural Science Foundation of China (Grant Nos. 11234013 and 11264014), the Natural Science Foundation of Jiangxi Province, China (Grant Nos. 20133ACB21010, 20142BAB212002, and 20132BAB212005), and the Foundation of Jiangxi Provincial Education Committee, China (Grant Nos. GJJ14254 and KJLD14024).

  12. Electrolytic Reduction of Spent Nuclear Oxide Fuel -- Effects of Fuel Form and Cathode Containment Materials on Bench-Scale Operations

    SciTech Connect

    S. D. Herrmann

    2007-09-01

    A collaborative effort between the Idaho National Laboratory (INL) and Korea Atomic Energy Research Institute (KAERI) is underway per an International Nuclear Energy Research Initiative to advance the development of a pyrochemical process for the treatment of spent nuclear oxide fuel. To assess the effects of specific process parameters that differ between oxide reduction operations at INL and KAERI, a series of 4 electrolytic reduction runs will be performed with a single salt loading of LiCl-Li2O at 650 °C using a test apparatus located inside of a hot cell at INL. The spent oxide fuel for the tests will be irradiated UO2 that has been subjected to a voloxidation process to form U3O8. The primary variables in the 4 electrolytic reduction runs will be fuel basket containment material and Li2O concentration in the LiCl salt. All 4 runs will be performed with comparable fuel loadings (approximately 50 g) and fuel compositions and will utilize a platinum anode and a Ni/NiO reference electrode. The first 2 runs will elucidate the effect of fuel form on the electrolytic reduction process by comparison of the above test results with U3O8 versus results from previous tests with UO2. The first 3 runs will investigate the impact that the cathode containment material has on the electrolytic reduction of spent oxide fuel. The 3rd and 4th runs will investigate the effect of Li2O concentration on the reduction process with a porous MgO cathode containment.

  13. Vanadium Oxyfluoride/Few-Layer Graphene Composite as a High-Performance Cathode Material for Lithium Batteries.

    PubMed

    Cambaz, Musa Ali; Vinayan, B P; Clemens, Oliver; Munnangi, Anji Reddy; Chakravadhanula, Venkata Sai Kiran; Kübel, Christian; Fichtner, Maximilian

    2016-04-18

    Metal oxyfluoride compounds are gathering significant interest as cathode materials for lithium ion batteries at the moment because of their high theoretical capacity and resulting high energy density. In this regard, a new and direct approach is presented to synthesize phase-pure vanadium oxyfluoride (VO2F). The structure of VO2F was identified by Rietveld refinement of the powder X-ray diffraction (XRD) pattern. It crystallizes in a perovskite-type structure with disorder of the oxide and fluoride ions. The as-synthesized VO2F was tested as a cathode material for lithium ion batteries after being surface-coated with few-layer graphene. The VO2F delivered a first discharge capacity of 254 mA h g(-1) and a reversible capacity of 208 mA h g(-1) at a rate of C/20 for the first 20 cycles with an average discharge voltage of 2.84 V, yielding an energy density of 591 W h kg(-1). Improved rate capability that outperforms the previous report has been achieved, showing a discharge capacity of 150 mA h g(-1) for 1 C. The structural changes during lithium insertion and extraction were monitored by ex-situ XRD analysis of the electrodes discharged and charged to various stages. Lithium insertion results in an irreversible structural change of the anion lattice from (3)/4 cubic close packing to hexagonal close packing to accommodate the inserted lithium ions while keeping the overall space-group symmetry. For the first time we have revealed a structural change for the ReO3-type structure of as-prepared VO2F to the RhF3 structure after lithiation/delithiation, with structural changes that have not been observed in previous reports. Furthermore, the new synthetic approach described here would be a platform for the synthesis of new oxyfluoride compounds. PMID:27018603

  14. Exceptionally Active and Stable Spinel Nickel Manganese Oxide Electrocatalysts for Urea Oxidation Reaction.

    PubMed

    Periyasamy, Sivakumar; Subramanian, Palaniappan; Levi, Elena; Aurbach, Doron; Gedanken, Aharon; Schechter, Alex

    2016-05-18

    Spinel nickel manganese oxides, widely used materials in the lithium ion battery high voltage cathode, were studied in urea oxidation catalysis. NiMn2O4, Ni1.5Mn1.5O4, and MnNi2O4 were synthesized by a simple template-free hydrothermal route followed by a thermal treatment in air at 800 °C. Rietveld analysis performed on nonstoichiometric nickel manganese oxide-Ni1.5Mn1.5O4 revealed the presence of three mixed phases: two spinel phases with different lattice parameters and NiO unlike the other two spinels NiMn2O4 and MnNi2O4. The electroactivity of nickel manganese oxide materials toward the oxidation of urea in alkaline solution is evaluated using cyclic voltammetric measurements. Ni1.5Mn1.5O4 exhibits excellent redox characteristics and lower charge transfer resistances in comparison with other compositions of nickel manganese oxides and nickel oxide prepared under similar conditions.The Ni1.5Mn1.5O4modified electrode oxidizes urea at 0.29 V versus Ag/AgCl with a corresponding current density of 6.9 mA cm(-2). At a low catalyst loading of 50 μg cm(-2), the urea oxidation current density of Ni1.5Mn1.5O4 in alkaline solution is 7 times higher than that of nickel oxide and 4 times higher than that of NiMn2O4 and MnNi2O4, respectively. PMID:27123873

  15. Preparation of Nanocomposite GDC/LSCF Cathode Material for IT-SOFC by Induction Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Shen, Yan; Almeida, Veronica Alexandra B.; Gitzhofer, François

    2011-01-01

    Homogeneous mixtures of Ce0.8Gd0.2O1.9 (GDC) and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) nanopowders were successfully synthesized using induction plasma by axial injection of a solution. The resulting nanocomposite powders consisted of two kinds of nanopowders with different mass ratio of GDC/LSCF, such as 3/7 and 6/4. The morphological features, crystallinity, and the phases of the synthesized powders were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), local energy-dispersive x-ray spectroscopy (EDS) analysis, and x-ray diffraction (XRD). The nanopowders are almost globular in shape with a diameter smaller than 100 nm and their BET specific areas are around 20 m2 g-1. The GDC and LSCF phases are well distributed in the nanopowders. In addition, suspensions, made with the as-synthesized composite nanopowders and ethanol, were used to deposit cathode coatings using suspension plasma spray (SPS). Micro-nanostructures of the coatings are discussed. The coatings are homogeneous and porous (51% porosity) with cauliflower structures.

  16. Fe-Si networks in Na2FeSiO4 cathode materials.

    PubMed

    Wu, P; Wu, S Q; Lv, X; Zhao, X; Ye, Z; Lin, Z; Wang, C Z; Ho, K M

    2016-08-24

    Using a combination of adaptive genetic algorithm search, motif-network search scheme and first-principles calculations, we have systematically studied the low-energy crystal structures of Na2FeSiO4. We show that the low-energy crystal structures with different space group symmetries can be classified into several families based on the topologies of their Fe-Si networks. In addition to the diamond-like network which is shared by most of the low-energy structures, another three robust Fe-Si networks are also found to be stable during the charge/discharge process. The electrochemical properties of representative structures from these four different Fe-Si networks in Na2FeSiO4 and Li2FeSiO4 are investigated and found to be strongly correlated with the Fe-Si network topologies. Our studies provide a new route to characterize the crystal structures of Na2FeSiO4 and Li2FeSiO4 and offer useful guidance for the design of promising cathodes for Na/Li ion batteries. PMID:27523264

  17. Compositional variations in lunar spinels.

    NASA Technical Reports Server (NTRS)

    Haggerty, S. E.

    1971-01-01

    Electron probe data for spinels from Apollo 11, 12, and 14 are presented and analyzed. A modified Johnstone spinel prism showing the data distribution is given. Three projections of this prism are then presented which illustrate the variations of simple ratios that are present in the prism and permit three different perspectives of the data. The results are summarized as fO2 isobars on the spinel prism.

  18. Thermionic emission investigation of materials for directly heated cathodes of electron tubes

    NASA Astrophysics Data System (ADS)

    Gellert, Bernd; Rohrbach, W.

    1994-05-01

    Thermionic emission of new material compositions are studied. Combinations of rare earth materials and tungsten offer great potential as thermal electron emitter into vacuum. The thermal emission properties of these materials are studied and compared to thoriated tungsten as a well-known thermal emitter. The corresponding work functions and Richardson Dushman constants are evaluated. The chemistry involved and the emission mechanism are discussed.

  19. Hydrogen hollow cathode ion source

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J., Jr.; Sovey, J. S.; Roman, R. F. (Inventor)

    1980-01-01

    A source of hydrogen ions is disclosed and includes a chamber having at one end a cathode which provides electrons and through which hydrogen gas flows into the chamber. Screen and accelerator grids are provided at the other end of the chamber. A baffle plate is disposed between the cathode and the grids and a cylindrical baffle is disposed coaxially with the cathode at the one end of the chamber. The cylindrical baffle is of greater diameter than the baffle plate to provide discharge impedance and also to protect the cathode from ion flux. An anode electrode draws the electrons away from the cathode. The hollow cathode includes a tubular insert of tungsten impregnated with a low work function material to provide ample electrons. A heater is provided around the hollow cathode to initiate electron emission from the low work function material.

  20. Multi-Functional Surface Engineering for Li-Excess Layered Cathode Material Targeting Excellent Electrochemical and Thermal Safety Properties.

    PubMed

    Bian, Xiaofei; Fu, Qiang; Pang, Qiang; Gao, Yu; Wei, Yingjin; Zou, Bo; Du, Fei; Chen, Gang

    2016-02-10

    The Li(Li(0.18)Ni(0.15)Co(0.15)Mn(0.52))O2 cathode material is modified by a Li4M5O12-like heterostructure and a BiOF surface layer. The interfacial heterostructure triggers the layered-to-Li4M5O12 transformation of the material which is different from the layered-to-LiMn2O4 transformation of the pristine Li(Li(0.18)Ni(0.15)Co(0.15)Mn(0.52))O2. This Li4M5O12-like transformation helps the material to keep high working voltage, long cycle life and excellent rate capability. Mass spectrometry, in situ X-ray diffraction and transmission electron microscope show that the Li4M5O12-like phase prohibits oxygen release from the material bulk at elevated temperatures. In addition, the BiOF coating layer protects the material from harmful side reactions with the electrolyte. These advantages significantly improve the electrochemical performance of Li(Li(0.18)Ni(0.15)Co(0.15)Mn(0.52))O2. The material shows a discharge capacity of 292 mAh g(-1) at 0.2 C with capacity retention of 92% after 100 cycles. Moreover, a high discharge capacity of 78 mAh g(-1) could be obtained at 25 C. The exothermic temperature of the fully charged electrode is elevated from 203 to 261 °C with 50% reduction of the total thermal release, highlighting excellent thermal safety of the material. PMID:26799857

  1. Ionic liquid-assisted solvothermal synthesis of hollow Mn2O3 anode and LiMn2O4 cathode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    He, Xin; Wang, Jun; Jia, Haiping; Kloepsch, Richard; Liu, Haidong; Beltrop, Kolja; Li, Jie

    2015-10-01

    Mn-based Mn2O3 anode and LiMn2O4 cathode materials are prepared by a solvothermal method combined with post annealing process. Environmentally friendly ionic liquid 1-Butyl-3-methylimidazolium tetrafluoroborate as both structure-directing agent and fluorine source is used to prepare hollow polyhedron MnF2 precursor. Both target materials Mn2O3 anode and LiMn2O4 cathode have the morphology of the MnF2 precursor. The Mn2O3 anode using carboxymethyl cellulose as binder could deliver slight better electrochemical performance than the one using poly (vinyldifluoride) as binder. The former has an initial charge capacity of 800 mAh g-1 at a current density of 101.8 mA g-1, and exhibits no obvious capacity decay for 150 cycles at 101.8 mA g-1. The LiMn2O4 cathode material prepared with molten salt assistant could display much better electrochemical performance than the one prepared without molten salt assistance. In particular, it has an initial discharge capacity of 117.5 mAh g-1 at a current density of 0.5C and good rate capability. In the field of lithium ion batteries, both the Mn2O3 anode and LiMn2O4 cathode materials could exhibit enhanced electrochemical performance due to the well formed morphology based on the ionic liquid-assisted solvothermal method.

  2. Evaluation of wear rates and mechanisms of titanium diboride-graphite composite materials proposed for use as cathodes in Hall-Heroult cells

    SciTech Connect

    Pool, K.H.; Brimhall, J.L.; Raney, P.J.; Hart, P.E.

    1987-01-01

    Purpose of this study was to measure the initial wear rates of TiB/sub 2/ carbon-containing cathode materials (TiB/sub 2/-G) under electrolytic conditions. Parameters evaluated included bath ratio, current density, and aluminum pad thickness. In order to measure initial wear rates, the tests were limited to 8 h.

  3. Hydroxyl-decorated graphene systems as candidates for organic metal-free ferroelectrics, multiferroics, and high-performance proton battery cathode materials

    NASA Astrophysics Data System (ADS)

    Wu, Menghao; Burton, J. D.; Tsymbal, Evgeny Y.; Zeng, Xiao Cheng; Jena, Puru

    2013-02-01

    Using a first-principles method we show that graphene based materials, functionalized with hydroxyl groups, constitute a class of multifunctional, lightweight, and nontoxic organic materials with functional properties such as ferroelectricity, multiferroicity, and can be used as proton battery cathode materials. For example, the polarizations of semihydroxylized graphane and graphone, as well as fully hydroxylized graphane, are much higher than any organic ferroelectric materials known to date. Further, hydroxylized graphene nanoribbons with proton vacancies at the end can have much larger dipole moments. They may also be applied as high-capacity cathode materials with a specific capacity that is six times larger than lead-acid batteries and five times that of lithium-ion batteries.

  4. A new lithium-rich anti-spinel in Li-O-Br system.

    PubMed

    Zhang, J; Zhu, J; Wang, L; Zhao, Y

    2015-06-14

    In spinel-type materials currently known, the divalent anions are arranged in a closed-pack lattice and cations of various valences occupy some or all of the tetrahedral and octahedral sites. We report here the first discovery of an "electronically inverted" anti-spinel. The new material, crystallized in a defect spinel structure, was obtained from the dehydration of Li5Br(OH)4 under moderate pressure and temperature conditions. PMID:25977945

  5. A Hollow Cathode Magnetron (HCM)

    SciTech Connect

    S.A. Cohen; Z. Wang

    1998-04-01

    A new type of plasma sputtering device, named the hollow cathode magnetron (HCM), has been developed by surrounding a planar magnetron cathode with a hollow cathode structure (HCS). Operating characteristics of HCMs, current-voltage ( I-V ) curves for fixed discharge pressure and voltage-pressure ( V-p ) curves for fixed cathode current, are measured. Such characteristics are compared with their planar magnetron counterparts. New operation regimes, such as substantially lower pressures (0.3 mTorr), were discovered for HCMs. Cathode erosion profiles show marked improvement over planar magnetron in terms of material utilization. The use of HCMs for thin film deposition are discussed.

  6. Structural changes and thermal stability of charged LiNixMnyCozO2 cathode materials studied by combined in situ time-resolved XRD and mass spectroscopy

    SciTech Connect

    Bak, Seong -Min; Hu, Enyuan; Zhou, Yongning; Yu, Xiqian; Senanayake, Sanjaya D.; Cho, Sung -Jin; Kim, Kwang -Bum; Chung, Kyung Yoon; Yang, Xiao -Qing; Nam, Kyung -Wan

    2014-11-24

    Thermal stability of charged LiNixMnyCozO2 (NMC, with x + y + z = 1, x:y:z = 4:3:3 (NMC433), 5:3:2 (NMC532), 6:2:2 (NMC622), and 8:1:1 (NMC811)) cathode materials is systematically studied using combined in situ time- resolved X-ray diffraction and mass spectroscopy (TR-XRD/MS) techniques upon heating up to 600 °C. The TR-XRD/MS results indicate that the content of Ni, Co, and Mn significantly affects both the structural changes and the oxygen release features during heating: the more Ni and less Co and Mn, the lower the onset temperature of the phase transition (i.e., thermal decomposition) and the larger amount of oxygen release. Interestingly, the NMC532 seems to be the optimized composition to maintain a reasonably good thermal stability, comparable to the low-nickel-content materials (e.g., NMC333 and NMC433), while having a high capacity close to the high-nickel-content materials (e.g., NMC811 and NMC622). The origin of the thermal decomposition of NMC cathode materials was elucidated by the changes in the oxidation states of each transition metal (TM) cations (i.e., Ni, Co, and Mn) and their site preferences during thermal decomposition. It is revealed that Mn ions mainly occupy the 3a octahedral sites of a layered structure (R3¯m) but Co ions prefer to migrate to the 8a tetrahedral sites of a spinel structure (Fd3¯m) during the thermal decomposition. Such element-dependent cation migration plays a very important role in the thermal stability of NMC cathode materials. The reasonably good thermal stability and high capacity characteristics of the NMC532 composition is originated from the well-balanced ratio of nickel content to manganese and cobalt contents. As a result, this systematic study provides insight into the rational design of NMC-based cathode materials with a desired balance between thermal stability and high energy density.

  7. Flakelike LiCoO2 with Exposed {010} Facets As a Stable Cathode Material for Highly Reversible Lithium Storage.

    PubMed

    Wu, Naiteng; Zhang, Yun; Guo, Yi; Liu, Shengjie; Liu, Heng; Wu, Hao

    2016-02-01

    A thick and dense flakelike LiCoO2 with exposed {010} active facets is synthesized using Co(OH)2 nanoflake as a self-sacrificial template obtained from a simple coprecipitation method, and served as a cathode material for lithium ion batteries. When operated at a high cutoff voltage up to 4.5 V, the resultant LiCoO2 exhibits an outstanding rate capability, delivering a reversible discharge capacity as high as 179, 176, 168, 116, and 96 mA h g(-1) at 25 °C under the current rate of 0.1, 0.5, 1, 5, and 10 C, respectively. When charge/discharge cycling at 55 °C, a high specific capacity of 148 mA h g(-1) (∼88% retention) can be retained after 100 cycles under 1 C, demonstrating excellent cycling and thermal stability. Besides, the flakelike LiCoO2 also shows an impressive low-temperature electrochemical activity with specific capacities of 175 (0.1 C) and 154 mA h g(-1) (1 C) at -10 °C, being the highest ever reported for a subzero-temperature lithium storage capability, as well as 52% capacity retention even after 80 cycles under 1 C. Such superior high-voltage electrochemical performances of the flakelike LiCoO2 operated at a wide temperature range are mainly attributed to its unique hierarchical structure with specifically exposed facets. The exposed {010} active facets provide a preferential crystallographic orientation for Li-ion migration, while the micrometer-sized secondary particles agglomerated by submicron primary LiCoO2 flakes endow the electrode with better structural integrity, both of which ensure the LiCoO2 cathode to manifest remarkably enhanced reversible lithium storage properties. PMID:26760433

  8. Carbon Quantum Dot Surface-Engineered VO2 Interwoven Nanowires: A Flexible Cathode Material for Lithium and Sodium Ion Batteries.

    PubMed

    Balogun, Muhammad-Sadeeq; Luo, Yang; Lyu, Feiyi; Wang, Fuxin; Yang, Hao; Li, Haibo; Liang, Chaolun; Huang, Miao; Huang, Yongchao; Tong, Yexiang

    2016-04-20

    The use of electrode materials in their powdery form requires binders and conductive additives for the fabrication of the cells, which leads to unsatisfactory energy storage performance. Recently, a new strategy to design flexible, binder-, and additive-free three-dimensional electrodes with nanoscale surface engineering has been exploited in boosting the storage performance of electrode materials. In this paper, we design a new type of free-standing carbon quantum dot coated VO2 interwoven nanowires through a simple fabrication process and demonstrate its potential to be used as cathode material for lithium and sodium ion batteries. The versatile carbon quantum dots that are vastly flexible for surface engineering serve the function of protecting the nanowire surface and play an important role in the diffusion of electrons. Also, the three-dimensional carbon cloth coated with VO2 interwoven nanowires assisted in the diffusion of ions through the inner and the outer surface. With this unique architecture, the carbon quantum dot nanosurface engineered VO2 electrode exhibited capacities of 420 and 328 mAh g(-1) at current density rate of 0.3 C for lithium and sodium storage, respectively. This work serves as a milestone for the potential replacement of lithium ion batteries and next generation postbatteries. PMID:27028048

  9. Electrochemical properties of magnesium doped LiFePO{sub 4} cathode material prepared by sol–gel method

    SciTech Connect

    Zhao, Xiaohui; Baek, Dong-Ho; Manuel, James; Heo, Min-Yeong; Yang, Rong; Ha, Jong Keun; Ryu, Ho-Suk; Ahn, Hyo-Jun; Kim, Ki-Won; Cho, Kwon-Koo; Ahn, Jou-Hyeon

    2012-10-15

    Magnesium doped Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C (x = 0.00, 0.01, 0.03, 0.05) cathode materials were synthesized by sol–gel method, and the effect of magnesium doping as well as its content on the electrochemical properties for lithium batteries was also investigated{sub .} Their morphology was studied with field emission scanning electron microscope and Li{sub 1−2x}Mg{sub x}FePO{sub 4} materials showed the olivine phase without impurities. The thin carbon layer of Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C was confirmed by high resolution transmission electron microscopy. The magnesium doped Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C particles were smaller than those undoped. The Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C materials showed better cycling behavior than undoped LiFePO{sub 4}, especially at high C-rate in which Li{sub 0.94}Mg{sub 0.03}FePO{sub 4}/C composition exhibited the best electrochemical properties.

  10. Mechanistic insights for the development of Li-O2 battery materials: addressing Li2O2 conductivity limitations and electrolyte and cathode instabilities.

    PubMed

    McCloskey, Bryan D; Burke, Colin M; Nichols, Jessica E; Renfrew, Sara E

    2015-08-18

    The Li-air battery has received significant attention over the past decade given its high theoretical specific energy compared to competing energy storage technologies. Yet, numerous scientific challenges remain unsolved in the pursuit of attaining a battery with modest Coulombic efficiency and high capacity. In this Feature Article, we provide our current perspective on challenges facing the development of nonaqueous Li-O2 battery cathodes. We initially present a review on our understanding of electrochemical processes occurring at the nonaqueous Li-O2 cathode. Electrolyte and cathode instabilities and Li2O2 conductivity limitations are then discussed, and suggestions for future materials research development to alleviate these issues are provided. PMID:26179598

  11. Miniaturized cathodic arc plasma source

    DOEpatents

    Anders, Andre; MacGill, Robert A.

    2003-04-15

    A cathodic arc plasma source has an anode formed of a plurality of spaced baffles which extend beyond the active cathode surface of the cathode. With the open baffle structure of the anode, most macroparticles pass through the gaps between the baffles and reflect off the baffles out of the plasma stream that enters a filter. Thus the anode not only has an electrical function but serves as a prefilter. The cathode has a small diameter, e.g. a rod of about 1/4 inch (6.25 mm) diameter. Thus the plasma source output is well localized, even with cathode spot movement which is limited in area, so that it effectively couples into a miniaturized filter. With a small area cathode, the material eroded from the cathode needs to be replaced to maintain plasma production. Therefore, the source includes a cathode advancement or feed mechanism coupled to cathode rod. The cathode also requires a cooling mechanism. The movable cathode rod is housed in a cooled metal shield or tube which serves as both a current conductor, thus reducing ohmic heat produced in the cathode, and as the heat sink for heat generated at or near the cathode. Cooling of the cathode housing tube is done by contact with coolant at a place remote from the active cathode surface. The source is operated in pulsed mode at relatively high currents, about 1 kA. The high arc current can also be used to operate the magnetic filter. A cathodic arc plasma deposition system using this source can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  12. Planar-focusing cathodes.

    SciTech Connect

    Lewellen, J. W.; Noonan, J.; Accelerator Systems Division

    2005-01-01

    Conventional {pi}-mode rf photoinjectors typically use magnetic solenoids for emittance compensation. This provides independent focusing strength but can complicate rf power feed placement, introduce asymmetries (due to coil crossovers), and greatly increase the cost of the photoinjector. Cathode-region focusing can also provide for a form of emittance compensation. Typically this method strongly couples focusing strength to the field gradient on the cathode, however, and usually requires altering the longitudinal position of the cathode to change the focusing. We propose a new method for achieving cathode-region variable-strength focusing for emittance compensation. The new method reduces the coupling to the gradient on the cathode and does not require a change in the longitudinal position of the cathode. Expected performance for an S-band system is similar to conventional solenoid-based designs. This paper presents the results of rf cavity and beam dynamics simulations of the new design. We have proposed a method for performing emittance compensation using a cathode-region focusing scheme. This technique allows the focusing strength to be adjusted somewhat independently of the on-axis field strength. Beam dynamics calculations indicate performance should be comparable to presently in-use emittance compensation schemes, with a simpler configuration and fewer possibilities for emittance degradation due to the focusing optics. There are several potential difficulties with this approach, including cathode material selection, cathode heating, and peak fields in the gun. We hope to begin experimenting with a cathode of this type in the near future, and several possibilities exist for reducing the peak gradients to more acceptable levels.

  13. A novel surface-sensitive X-ray absorption spectroscopic detector to study the thermal decomposition of cathode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Nonaka, Takamasa; Okuda, Chikaaki; Oka, Hideaki; Nishimura, Yusaku F.; Makimura, Yoshinari; Kondo, Yasuhito; Dohmae, Kazuhiko; Takeuchi, Yoji

    2016-09-01

    A surface-sensitive conversion-electron-yield X-ray absorption fine structure (CEY-XAFS) detector that operates at elevated temperatures is developed to investigate the thermal decomposition of cathode materials for Li-ion batteries. The detector enables measurements with the sample temperature controlled from room temperature up to 450 °C. The detector is applied to the LiNi0.75Co0.15Al0.05Mg0.05O2 cathode material at 0% state of charge (SOC) and 50% SOC to examine the chemical changes that occur during heating in the absence of an electrolyte. The combination of surface-sensitive CEY-XAFS and bulk-sensitive transmission-mode XAFS shows that the reduction of Ni and Co ions begins at the surface of the cathode particles at around 150 °C, and propagates inside the particle upon further heating. These changes with heating are irreversible and are more obvious at 50% SOC than at 0% SOC. The fraction of reduced Ni ions is larger than that of reduced Co ions. These results demonstrate the capability of the developed detector to obtain important information for the safe employment of this cathode material in Li-ion batteries.

  14. Plasma sprayed manganese-cobalt spinel coatings: Process sensitivity on phase, electrical and protective performance

    NASA Astrophysics Data System (ADS)

    Han, Su Jung; Pala, Zdenek; Sampath, Sanjay

    2016-02-01

    Manganese cobalt spinel (Mn1.5Co1.5O4, MCO) coatings are prepared by the air plasma spray (APS) process to examine their efficacy in serving as protective coatings from Cr-poisoning of the cathode side in intermediate temperature-solid oxide fuel cells (IT-SOFCs). These complex oxides are susceptible to process induced stoichiometric and phase changes which affect their functional performance. To critically examine these effects, MCO coatings are produced with deliberate modifications to the spray process parameters to explore relationship among process conditions, microstructure and functional properties. The resultant interplay among particle thermal and kinetic energies are captured through process maps, which serve to characterize the parametric effects on properties. The results show significant changes to the chemistry and phase composition of the deposited material resulting from preferential evaporation of oxygen. Post deposition annealing recovers oxygen in the coatings and allows partial recovery of the spinel phase, which is confirmed through thermo-gravimetric analysis (TGA)/differential scanning calorimetry (DSC), X-ray Diffraction (XRD), and magnetic hysteresis measurements. In addition, coatings with high density after sintering show excellent electrical conductivity of 40 S cm-1 at 800 °C while simultaneously providing requisite protection characteristics against Cr-poisoning. This study provides a framework for optimal evaluation of MCO coatings in intermediate temperature SOFCs.

  15. On the Utility of Spinel Oxide Hosts for Magnesium-Ion Batteries.

    PubMed

    Knight, James C; Therese, Soosairaj; Manthiram, Arumugam

    2015-10-21

    There is immense interest to develop Mg-ion batteries, but finding suitable cathode materials has been a challenge. The spinel structure has many advantages for ion insertion and has been successfully used in Li-ion batteries. We present here findings on the attempts to extract Mg from MgMn2O4-based spinels with acid (H2SO4) and with NO2BF4. The acid treatment was able to fully remove all Mg from MgMn2O4 by following a mechanism involving the disproportionation of Mn(3+), and the extraction rate decreased with increasing cation disorder. Samples with additional Mg(2+) ions in the octahedral sites (e.g., Mg1.1Mn1.9O4 and Mg1.5Mn1.5O4) also exhibit complete or near complete demagnesiation due to an additional mechanism involving ion exchange of Mg(2+) by H(+), but no Mg could be extracted from MgMnAlO4 due to the disruption of Mn-Mn interaction/contact across shared octahedral edges. In contrast, no Mg could be extracted with the oxidizing agent NO2BF4 from MgMn2O4 or Mg1.5Mn1.5O4 as the electrostatic repulsion between the divalent Mg(2+) ions prevents Mg(2+) diffusion through the 16c octahedral sites, unlike Li(+) diffusion, suggesting that spinels may not serve as potential hosts for Mg-ion batteries. The ability to extract Mg with acid in contrast to that with NO2BF4 is attributed to Mn dissolution from the lattice and the consequent reduction in electrostatic repulsion. The findings could provide insights toward the design of Mg hosts for Mg-ion batteries. PMID:26436429

  16. 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. PMID:26204097

  17. Improved electrochemical performance of spinel LiMn1.5Ni0.5O4 through MgF2 nano-coating

    DOE PAGESBeta

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

    2015-07-08

    In this paper, 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 themore » 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. Finally and additionally, differential scanning calorimetry (DSC) tests show that the MgF2 nano-coating layer also helps in enhancing the thermal stability of the LMNO cathode.« less

  18. Improvement of the cycling performance of LiNi(0.6)Co(0.2)Mn(0.2)O(2) cathode active materials by a dual-conductive polymer coating.

    PubMed

    Ju, Seo Hee; Kang, Ik-Su; Lee, Yoon-Sung; Shin, Won-Kyung; Kim, Saheum; Shin, Kyomin; Kim, Dong-Won

    2014-02-26

    LiNi0.6Co0.2Mn0.2O2 cathode materials were surface-modified by coating with a dual conductive poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol) (PEDOT-co-PEG) copolymer, and their resulting electrochemical properties were investigated. The surface-modified LiNi0.6Co0.2Mn0.2O2 cathode material exhibited a high discharge capacity and good high rate performance due to enhanced transport of Li(+) ions as well as electrons. The presence of a protective conducting polymer layer formed on the cathode also suppressed the growth of a resistive layer and inhibited the dissolution of transition metals from the active cathode materials, which resulted in more stable cycling characteristics than the pristine LiNi0.6Co0.2Mn0.2O2 cathode material at 55 (o)C. PMID:24460052

  19. Hollow Cathode With Multiple Radial Orifices

    NASA Technical Reports Server (NTRS)

    Brophy, John R.

    1992-01-01

    Improved hollow cathode serving as source of electrons has multiple radial orifices instead of single axial orifice. Distributes ion current more smoothly, over larger area. Prototype of high-current cathodes for ion engines in spacecraft. On Earth, cathodes used in large-diameter ion sources for industrial processing of materials. Radial orientation of orifices in new design causes current to be dispersed radially in vicinity of cathode. Advantageous where desireable to produce plasma more nearly uniform over wider region around cathode.

  20. MxMn8O16 (M = Ag or K) as promising cathode materials for secondary Mg based batteries: The role of the cation M

    DOE PAGESBeta

    Huang, Jianping; Takeuchi, Esther S.; Altug S. Poyraz; Takeuchi, Kenneth J.; Marschilok, Amy C.

    2016-02-15

    Here, AgxMn8O16 (Ag-OMS-2) and KxMn8O16 (K-OMS-2) were investigated as high voltage cathode materials for Mg based batteries. Both MxMn8O16 materials delivered high initial capacities (>180 mA h g–1), and KxMn8O16 showed high cycle stability with a reversible capacity of >170 mA h g–1 after 20 cycles.

  1. Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries.

    PubMed

    Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

    2014-01-01

    As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries. PMID:24710575

  2. Aspergillus flavus Conidia-derived Carbon/Sulfur Composite as a Cathode Material for High Performance Lithium–Sulfur Battery

    PubMed Central

    Xu, Maowen; Jia, Min; Mao, Cuiping; Liu, Sangui; Bao, Shujuan; Jiang, Jian; Liu, Yang; Lu, Zhisong

    2016-01-01

    A novel approach was developed to prepare porous carbon materials with an extremely high surface area of 2459.6 m2g−1 by using Aspergillus flavus conidia as precursors. The porous carbon serves as a superior cathode material to anchor sulfur due to its uniform and tortuous morphology, enabling high capacity and good cycle lifetime in lithium sulfur-batteries. Under a current rate of 0.2 C, the carbon-sulfur composites with 56.7 wt% sulfur loading deliver an initial capacity of 1625 mAh g−1, which is almost equal to the theoretical capacity of sulfur. The good performance may be ascribed to excellent electronic networks constructed by the high-surface-area carbon species. Moreover, the semi-closed architecture of derived carbons can effectively retard the polysulfides dissolution during charge/discharge, resulting in a capacity of 940 mAh g−1 after 120 charge/discharge cycles. PMID:26732547

  3. Nb doped TiO2 as a Cathode Catalyst Support Material for Polymer Electrolyte Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    O'Toole, Alexander W.

    In order to reduce the emissions of greenhouse gases and reduce dependence on the use of fossil fuels, it is necessary to pursue alternative sources of energy. Transportation is a major contributor to the emission of greenhouse gases due to the use of fossil fuels in the internal combustion engine. To reduce emission of these pollutants into the atmosphere, research is needed to produce alternative solutions for vehicle transportation. Low temperature polymer electrolyte membrane fuel cells are energy conversion devices that provide an alternative to the internal combustion engine, however, they still have obstacles to overcome to achieve large scale implementation. T he following work presents original research with regards to the development of Nb doped TiO2 as a cathode catalyst support material for low temperature polymer electrolyte membrane fuel cells. The development of a new process to synthesize nanoparticles of Nb doped TiO2 with controlled compositions is presented as well as methods to scale up the process and optimize the synthesis for the aforementioned application. In addition to this, comparison of both electrochemical activity and durability with current state of the art Pt on high surface area carbon black (Vulcan XC-72) is investigated. Effects of the strong metal-support interaction on the electrochemical behavior of these materials is also observed and discussed.

  4. Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries

    PubMed Central

    Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

    2014-01-01

    As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries. PMID:24710575

  5. Aspergillus flavus Conidia-derived Carbon/Sulfur Composite as a Cathode Material for High Performance Lithium-Sulfur Battery

    NASA Astrophysics Data System (ADS)

    Xu, Maowen; Jia, Min; Mao, Cuiping; Liu, Sangui; Bao, Shujuan; Jiang, Jian; Liu, Yang; Lu, Zhisong

    2016-01-01

    A novel approach was developed to prepare porous carbon materials with an extremely high surface area of 2459.6 m2g-1 by using Aspergillus flavus conidia as precursors. The porous carbon serves as a superior cathode material to anchor sulfur due to its uniform and tortuous morphology, enabling high capacity and good cycle lifetime in lithium sulfur-batteries. Under a current rate of 0.2 C, the carbon-sulfur composites with 56.7 wt% sulfur loading deliver an initial capacity of 1625 mAh g-1, which is almost equal to the theoretical capacity of sulfur. The good performance may be ascribed to excellent electronic networks constructed by the high-surface-area carbon species. Moreover, the semi-closed architecture of derived carbons can effectively retard the polysulfides dissolution during charge/discharge, resulting in a capacity of 940 mAh g-1 after 120 charge/discharge cycles.

  6. Coaxial-cable structure composite cathode material with high sulfur loading for high performance lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Zhang, Zhian; Guo, Zaiping; Zhang, Kai; Lai, Yanqing; Li, Jie

    2015-01-01

    Hollow carbon nanofiber@nitrogen-doped porous carbon (HCNF@NPC) coaxial-cable structure composite, which is carbonized from HCNF@polydopamine, is prepared as an improved high conductive carbon matrix for encapsulating sulfur as a composite cathode material for lithium-sulfur batteries. The prepared HCNF@NPC-S composite with high sulfur content of approximately 80 wt% shows an obvious coaxial-cable structure with an NPC layer coating on the surface of the linear HCNFs along the length and sulfur homogeneously distributes in the coating layer. This material exhibits much better electrochemical performance than the HCNF-S composite, delivers initial discharge capacity of 982 mAh g-1 and maintains a high capacity retention rate of 63% after 200 cycles at a high current density of 837.5 mA g-1. The significantly enhanced electrochemical performance of the HCNF@NPC-S composite is attributed to the unique coaxial-cable structure, in which the linear HCNF core provides electronic conduction pathways and works as mechanical support, and the NPC shell with nitrogen-doped and porous structure can trap sulfur/polysulfides and provide Li+ conductive pathways.

  7. Aspergillus flavus Conidia-derived Carbon/Sulfur Composite as a Cathode Material for High Performance Lithium-Sulfur Battery.

    PubMed

    Xu, Maowen; Jia, Min; Mao, Cuiping; Liu, Sangui; Bao, Shujuan; Jiang, Jian; Liu, Yang; Lu, Zhisong

    2016-01-01

    A novel approach was developed to prepare porous carbon materials with an extremely high surface area of 2459.6 m(2)g(-1) by using Aspergillus flavus conidia as precursors. The porous carbon serves as a superior cathode material to anchor sulfur due to its uniform and tortuous morphology, enabling high capacity and good cycle lifetime in lithium sulfur-batteries. Under a current rate of 0.2 C, the carbon-sulfur composites with 56.7 wt% sulfur loading deliver an initial capacity of 1625 mAh g(-1), which is almost equal to the theoretical capacity of sulfur. The good performance may be ascribed to excellent electronic networks constructed by the high-surface-area carbon species. Moreover, the semi-closed architecture of derived carbons can effectively retard the polysulfides dissolution during charge/discharge, resulting in a capacity of 940 mAh g(-1) after 120 charge/discharge cycles. PMID:26732547

  8. Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

    2014-04-01

    As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries.

  9. Hierarchical LiNixCoyO2 mesostructures as high-performance cathode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Shang, Longmei; Li, He; Lai, Hongwei; Li, Danqin; Wu, Qiang; Yang, Lijun; Wang, Xizhang; Hu, Zheng

    2016-09-01

    Lithium ion batteries (LIBs) with enhanced performance to commercial ones are urgently demanded in portable electric devices. Herein, we demonstrate an efficient strategy to improve the electrochemical performance of a dominant commercial cathode material (LiCoO2) by constructing 3D hierarchical LiNixCoyO2 (h-LNCO). The h-LNCO presents porous spherical-shaped morphology at mesoscale while comprises interconnected primary nanoparticles at nanoscale. Such a unique morphology endows the h-LNCO with porous structure for easy penetration of electrolyte, relatively small size of primary particles with short Li+ ions diffusion length and abundant exposed surface in favor of Li+ intercalation/deintercalation. The synergism of these merits makes the h-LNCO exhibit superior electrochemical properties with high capacity, superior cyclability and rate capability, much better than the solid granular LNCO counterparts and commercial LiCoO2. This strategy of constructing porous hierarchical mesostructures could be extended to other electrode materials for electrochemical energy storage.

  10. Enhanced electrochemical performance in LiFePO4/graphene nanocomposite cathode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Dhindsa, Kulwinder; Mandal, B.; Lin, M. W.; Nazri, M.; Vaishnava, P.; Naik, V.; Nazri, G. A.; Naik, R.; Zhou, Z. X.

    2012-02-01

    We synthesized LiFePO4/graphene nano-composite employing a sol-gel method, where graphene oxide solution was added to the LiFePO4 precursors during the synthesis. Electrical measurement reveals that the addition of 10% graphene (by weight) to LiFePO4 increases its conductivity by 5 orders of magnitude. SEM images of the composite show that the material consists of LiFePO4 nanoparticles (with a mean particle size ˜ 50 nm) homogeneously mixed with graphene sheets; the latter provides a three-dimensional conducting network for Li+ ion and electron transport. A large specific capacity of 170 mAh/g was observed at a discharge rate of C/2. To further increase the conductivity and inhibit particle size growth of LiFePO4 (thus to increase the rate capacity), we coated the nanoparticles with a thin carbon layer by adding 0.25M lauric acid as precursor in addition to graphene oxide during the synthesis. The respective roles of graphene and lauric-acid-induced carbon coating in the specific capacity and charge-discharge rate of the LiFePO4 cathode material will be discussed.

  11. Triphenylamine-Based Metal-Organic Frameworks as Cathode Materials in Lithium-Ion Batteries with Coexistence of Redox Active Sites, High Working Voltage, and High Rate Stability.

    PubMed

    Peng, Zhe; Yi, Xiaohui; Liu, Zixuan; Shang, Jie; Wang, Deyu

    2016-06-15

    Through rational organization of two redox active building block, a triphenylamine-based metal-organic framework (MOF) material, Cu-TCA (H3TCA = tricarboxytriphenyl amine), was synthesized and applied as a cathode active material for the first time in lithium batteries. Cu-TCA exhibited redox activity both in the metal clusters (Cu(+)/Cu(2+)) and organic ligand radicals (N/N(+)) with separated voltage plateaus and a high working potential vs Li/Li(+) up to 4.3 V, comparing with the current commercial LiCoO2 cathode materials. The electrochemical behaviors of this MOF electrode material at different states of charge were carefully studied by cyclic voltammetry, X-ray photoelectron spectroscopy, and photoluminescence techniques. Long cycling stability of this MOF was achieved with an average Coulombic efficiency of 96.5% for 200 cycles at a 2 C rate. Discussing the electrochemical performances on the basis of capacity contributions from the metal clusters (Cu(+)/Cu(2+)) and organic ligands (N/N(+)) proposes an alternative mechanism of capacity loss for the MOF materials used in lithium batteries. This improved understanding will shed light on the designing principle of MOF-based cathode materials for their practical application in battery sciences. PMID:27225327

  12. Rugged spinel windows and optics for harsh environments

    NASA Astrophysics Data System (ADS)

    Bayya, Shyam; Villalobos, Guillermo; Kim, Woohong; Busse, Lynda; Sanghera, Jasbinder; Aggarwal, Ishwar

    2013-05-01

    Spinel is a rugged ceramic transparent from ultraviolet to midwave infrared (0.18 - 5.5 μm) wavelengths. It has the best transmission from 4-5 μm among the competing materials ALON and sapphire with comparable mechanical properties. We have developed low absorption loss spinel as an exit window aperture for High Energy Laser systems. We demonstrated that spinel possesses excellent thermo-optical characteristics required for the High Energy Laser systems and at the same time it can provide the necessary ruggedness desired for the realistic and harsh battlefield environment. We have demonstrated through testing that spinel can withstand very adverse conditions of rain, sand storms and salt fog conditions without any change in its optical performance. We have also developed rugged anti-reflective coatings and anti-reflective surface structures to maintain high optical transmission in adverse environment.

  13. Facile synthesis of LiMn2O4 octahedral nanoparticles as cathode materials for high capacity lithium ion batteries with long cycle life

    NASA Astrophysics Data System (ADS)

    Cai, Yanjun; Huang, Yudai; Wang, Xingchao; Jia, Dianzeng; Pang, Weikong; Guo, Zaiping; Du, Yaping; Tang, Xincun

    2015-03-01

    Spinel lithium manganate octahedral nanoparticles have been prepared by high temperature solid-state combustion reaction using cellulose as fuel. The crystal structure, morphology, and electrochemical performance of the as-prepared materials are analyzed by X-ray diffraction (XRD), electron microscopy, and electrochemical testing. The XRD results show that the materials are single-phase and perfectly crystalline with a spinel structure. Microscopic observations reveal that the nanoparticles possess octahedral morphology, with an average particle size of about 165.4 nm and a uniform particle size distribution. The lithium manganate octahedral nanoparticles exhibit excellent initial discharge capacity of 118.5 and 78.3 mAh g-1, and about 72.49% and 94.6% of its initial discharge capacity can be retained even after 1600 cycles at 10 C and 3000 cycles at 20 C, respectively. The excellent electrochemical performance of the lithium manganate can be mainly attributed to the strong MnO6 framework mitigates the occurrence of Mn dissolution, maintains structural stability, and allows higher Li+ diffusion during electrochemical cycling. Furthermore, the nano-sized octahedral structure not only facilitates fast ion diffusion, but also mitigates the manganese dissolution due to the exposed (111) crystal planes, where the solid electrolyte interphase (SEI) forms.

  14. Structure and performance of LiFePO4 cathode materials: A review

    NASA Astrophysics Data System (ADS)

    Zhang, Wei-Jun

    2011-03-01

    LiFePO4 has been considered a promising battery material in electric vehicles. However, there are still a number of technical challenges to overcome before its wide-spread applications. In this article, the structure and electrochemical performance of LiFePO4 are reviewed in light of the major technical requirements for EV batteries. The rate capability, capacity density, cyclic life and low-temperature performance of various LiFePO4 materials are described. The major factors affecting these properties are discussed, which include particle size, doping, carbon coating, conductive carbon loading and synthesis techniques. Important future research for science and engineering is suggested.

  15. Cheaper Hydride-Forming Cathodes

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.; Blue, Gary

    1990-01-01

    Hydride-forming cathodes for electrochemical experiments made of materials or combinations of materials cheaper and more abundant than pure palladium, according to proposal. Concept prompted by needs of experimenters in now-discredited concept of electrochemical nuclear fusion, cathodes useful in other electrochemical applications involving generation or storage of hydrogen, deuterium, or tritium.

  16. MoO3 as a Cathode Buffer Layer Material for the Improvement of Planar pn-Heterojunction Organic Solar Cell Performance

    NASA Astrophysics Data System (ADS)

    Kageyama, Hiroshi; Kajii, Hirotake; Ohmori, Yutaka; Shirota, Yasuhiko

    2011-03-01

    The use of MoO3 as a cathode buffer layer inserted between LiF and Al improved the power conversion efficiency (PCE) of planar pn-heterojunction organic solar cells (OSCs) by reducing exciton quenching at the interface between the n-type organic active layer and the electrode. The cell using an amorphous molecular material, tris[4-(5-phenylthiophen-2-yl)phenyl]amine, as a p-type organic semiconductor, C70 as an n-type organic semiconductor and MoO3 as a cathode buffer layer exhibited a PCE of 3.3% under AM1.5G illumination (100 mW cm-2), which is of the highest level among those for planar pn-heterojunction OSCs using amorphous molecular materials as donor materials.

  17. Development program on a cold cathode electron gun

    NASA Technical Reports Server (NTRS)

    Spindt, C. A.; Holland, C. E.

    1985-01-01

    During this phase of the cathode development program, SRI improved the multiple electron beam exposure system used to print hole patterns for the cathode arrays, studied anisotropic etch processes, conducted cathode investigations using an emission microscope, reviewed possible alternate materials for cathode fabrication, studied cathode storage techniques, conducted high power operation experiments, and demonstrated high-current-density operation with small arrays of tips.

  18. Silver-coated LiVPO4F composite with improved electrochemical performance as cathode material for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Yang, Bo; Yang, Lin

    2015-12-01

    Nano-structured LiVPO4F/Ag composite cathode material has been successfully synthesized via a sol-gel route. The structural and physical properties, as well as the electrochemical performance of the material are compared with those of the pristine LiVPO4F. X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveal that Ag particles are uniformly dispersed on the surface of LiVPO4F without destroying the crystal structure of the bulk material. An analysis of the electrochemical measurements show that the Ag-modified LiVPO4F material exhibits high discharge capacity, good cycle performance (108.5 mAh g-1 after 50th cycles at 0.1 C, 93% of initial discharge capacity) and excellent rate behavior (81.8 mAh g-1 for initial discharge capacity at 5 C). The electrochemical impedance spectroscopy (EIS) results reveal that the adding of Ag decreases the charge-transfer resistance (Rct) of LiVPO4F cathode. This study demonstrates that Ag-coating is a promising way to improve the electrochemical performance of the pristine LiVPO4F for lithium-ion batteries cathode material.

  19. A Search for the Optimum Lithium Rich Layered Metal Oxide Cathode Material for Li-Ion Batteries

    PubMed Central

    Ates, Mehmet Nurullah; Mukerjee, Sanjeev; Abraham, K. M.

    2015-01-01

    We report the results of a comprehensive study of the relationship between electrochemical performance in Li cells and chemical composition of a series of Li rich layered metal oxides of the general formula xLi2MnO3 · (1-x)LiMn0.33Ni0.33Co0.33O2 in which x = 0,1, 0.2, 0,3, 0.5 or 0.7, synthesized using the same method. In order to identify the cathode material having the optimum Li cell performance we first varied the ratio between Li2MnO3 and LiMO2 segments of the composite oxides while maintaining the same metal ratio residing within their LiMO2 portions. The materials with the overall composition 0.5Li2MnO3 · 0.5LiMO2 containing 0.5 mole of Li2MnO3 per mole of the composite metal oxide were found to be the optimum in terms of electrochemical performance. The electrochemical properties of these materials were further tuned by changing the relative amounts of Mn, Ni and Co in the LiMO2 segment to produce xLi2MnO3 · (1-x)LiMn0.50Ni0.35Co0.15O2 with enhanced capacities and rate capabilities. The rate capability of the lithium rich compound in which x = 0.3 was further increased by preparing electrodes with about 2 weight-percent multiwall carbon nanotube in the electrode. Lithium cells prepared with such electrodes were cycled at the 4C rate with little fade in capacity for over one hundred cycles. PMID:26478598

  20. Synthesis of LiFePO4/Pani/C composite as a cathode material for lithium ion battery

    NASA Astrophysics Data System (ADS)

    Rahayu, Iman; Hidayat, Sahrul; Aryadi, Lutfi

    2016-02-01

    In recent years, LiFePO4 studied intensively as a cathode material for Li-ion batteries because of high theoretical capacity, stability, and environmental friendly. However, its low intrinsic electronic conductivity. One way to improve its conductivity is addition of conductive material. Polyaniline (PANI) is one of the conductive polymer materials that widely studied because its unique physical and chemical properties which can be an insulator and conductor by doping-dedoping processes and has large potential application. The purpose of this research is to improve the conductivity of LiFePO4 with conductive polymer PANI. The method is performed by the addition of LiFePO4 during the polymerization process to form LiFePO4 polyaniline then added to the C-PANI with the addition of mass percent variation of 5%, 10%, 15%, 20% form-LiFePO4 composite PANI-C. In LiFePO4 added during polymerization PANI provide a smooth surface profile after composited with the carbon to LiFePO4-PANI-C compared to LiFePO4-C. LiFePO4-PANI-C composite provided higher conductivity is 18.45×10-4 S/cm compared to LiFePO4-C is 10.48×10-4 S/cm at 20% addition of carbon. This is due to PANI in LiFePO4 is added to the polyaniline polymerization process can act as a conductive adhesive to glue between carbon and LiFePO4.

  1. Nonaqueous battery with organic compound cathode

    SciTech Connect

    Yamaji, A.; Yamaki, J.

    1981-02-17

    A battery embodying this invention comprises: an anode including an anode-active material formed of one metal selected from the Group IA metals or preferably lithium metal; a cathode including a cathode-active material formed of metal or metal-free organic compounds having a phthalocyanine function or organic compounds having a porphin function; and an electrolyte prepared from a material which is chemically stable to the cathode and anode materials and permits the migration of the ion of the anode metal to the cathode for electrochemical reaction with the cathode-active material.

  2. Layer cathode methods of manufacturing and materials for Li-ion rechargeable batteries

    DOEpatents

    Kang, Sun-Ho; Amine, Khalil

    2008-01-01

    A positive electrode active material for lithium-ion rechargeable batteries of general formula Li.sub.1+xNi.sub..alpha.Mn.sub..beta.A.sub..gamma.O.sub.2 and further wherein A is Mg, Zn, Al, Co, Ga, B, Zr, or Ti and 0material is manufactured by employing either a solid state reaction method or an aqueous solution method or a sol-gel method which is followed by a rapid quenching from high temperatures into liquid nitrogen or liquid helium.

  3. Magnetostructural and magnetodielectric coupling in spinel oxides

    NASA Astrophysics Data System (ADS)

    Kemei, Moureen Chemurgor

    Spinels oxides are of great interest functionally as multiferroic, battery, and magnetic materials as well as fundamentally because they exhibit novel spin, structural, and orbital ground states. Competing interactions are at the heart of novel functional behavior in spinels. Here, we explore the intricate landscape of spin, lattice, and orbital interactions in magnetic spinels by employing variable-temperature high-resolution synchrotron x-ray powder diffraction, total neutron scattering, magnetic susceptibility, dielectric, and heat capacity measurements. We show that the onset of long-range magnetic interactions often gives rise to lattice distortions. We present the complete crystallographic descriptions of the ground state structures of several spinels, thereby paving the way for accurate modeling and design of structure-property relationships in these materials. We also report the emergence of magnetodielectric coupling in the magnetostructural phases of some of the studied spinels. We begin by examining spin-lattice coupling in the Jahn-Teller active systems NiCr2O4 and CuCr2O4. Orbital ordering yields a cubic to tetragonal lattice distortion in these materials above their magnetic ordering temperatures, however, we find that magnetic ordering also drives structural distortions in these spinels through exchange striction. We provide the first orthorhombic structural descriptions of NiCr 2O4 and CuCr2O4. Our observation of strong spin-lattice coupling in NiCr2O4 and CuCr 2O4 inspired the study of magnetodielectric coupling in these spinels. Magnetocapacitance measurements of NiCr2O4 reveal multiferroic behavior and new magnetostructural distortions below the Neel temperature. This observation illustrates the sensitivity of dielectric measurements to magnetostructural transitions in spinel materials. Finally, in the examination of NiCr2O4 we show that magnetodielectric coupling is well described by Ginzburg-Landau theory. In addition to exchange striction

  4. Metal-organic frameworks as cathode materials for Li-O2 batteries.

    PubMed

    Wu, Doufeng; Guo, Ziyang; Yin, Xinbo; Pang, Qingqing; Tu, Binbin; Zhang, Lijuan; Wang, Yong-Gang; Li, Qiaowei

    2014-05-28

    Metal-organic frameworks (MOFs) with open metal sites enrich the population of O2 in the pores significantly and assist the Li-O2 reaction when employed as a cell electrode material. A primary capacity of 9420 mA h g(-1) is achieved in a cell with Mn-MOF-74; more than four times higher than the value obtained in a cell without an MOF. PMID:24616022

  5. Mixed Electronic and Ionic Conductor-Coated Cathode Material for High-Voltage Lithium Ion Battery.

    PubMed

    Shim, Jae-Hyun; Han, Jung-Min; Lee, Joon-Hyung; Lee, Sanghun

    2016-05-18

    A lithium ionic conductor, Li1.3Al0.3Ti1.7(PO4)3 (LATP), is introduced as a coating material on the surface of Mg-doped LiCoO2 to improve electrochemical performances for high-voltage (4.5 V) lithium ion batteries. Structure, morphology, elemental distribution, and electrical properties of the materials are thoroughly characterized by SEM, TEM, EELS, EDS, and C-AFM. The coating layer is electrically conductive with the aid of Mg ions which are used as a dopant for the active materials; therefore, this mixed electronic ionic conductor strongly enhances the electrochemical performances of initial capacity, cycling property, and rate capability. The LATP coating layer also demonstrates very promising applicability for 4.4 V prismatic full cells with graphite anode, which correspond to the 4.5 V half-cells with lithium anode. The 2900 mA h full cells show 85% of capacity retention after 500 cycles and more than 60% after 700 cycles. PMID:27127906

  6. Arcjet Cathode Phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  7. Arcjet cathode phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  8. Li3V2(PO4)3 cathode materials for lithium-ion batteries: A review

    NASA Astrophysics Data System (ADS)

    Rui, Xianhong; Yan, Qingyu; Skyllas-Kazacos, Maria; Lim, Tuti Mariana

    2014-07-01

    The principal challenges facing the development of lithium ion batteries (LIBs) for hybrid electric/plug-in-hybrid (HEV/PHEV) vehicles and for off-peak energy storage are cost, safety, cell energy density (voltage × capacity), rate of charge/discharge, and service life. There are exciting developments in new positive electrode (cathode) materials to replace the LiCoO2 for use in the LIBs over the past decade. Monoclinic Li3V2(PO4)3 (LVP) with promising electrochemical properties including excellent cycling stability, high theoretical capacity (197 mAh g-1), low synthetic cost, improved safety characteristic, and low environmental impact emerges as highly suitable candidate. In this review, we focus on research work related to the LVP and discuss its host structure, mechanism of lithium insertion/extraction, transport properties (i.e., electronic conductivity, and lithium diffusion), synthesis and electrochemical properties. We highlight some recent development of LVP, which shows superior cycling stability and high rate capability and give some vision for the future research of LVP based electrodes.

  9. LiFePO4 - 3D carbon nanofiber composites as cathode materials for Li-ions batteries

    NASA Astrophysics Data System (ADS)

    Dimesso, L.; Spanheimer, C.; Jaegermann, W.; Zhang, Y.; Yarin, A. L.

    2012-03-01

    The characterization of carbon nanofiber 3D nonwovens, prepared by electrospinning process, coated with olivine structured lithium iron phosphate is reported. The LiFePO4 as cathode material for lithium ion batteries was prepared by a Pechini-assisted reversed polyol process. The coating has been successfully performed on carbon nanofiber 3D nonwovens by soaking in aqueous solution containing lithium, iron salts and phosphates at 70 °C for 2-4 h. After drying-out, the composites were annealed at 600 °C for 5 h under nitrogen. The surface investigation of the prepared composites showed a uniform coating of the carbon nonwoven nanofibers as well as the formation of cauliflower-like crystalline structures which are uniformly distributed all over the surface area of the carbon nanofibers. The electrochemical measurements on the composites showed good performances delivering a discharge specific capacity of 156 mAhg- 1 at a discharging rate of C/25 and 152 mAhg- 1 at a discharging rate of C/10 at room temperature.

  10. Three-dimensional graphene/LiFePO{sub 4} nanostructures as cathode materials for flexible lithium-ion batteries

    SciTech Connect

    Ding, Y.H.; Ren, H.M.; Huang, Y.Y.; Chang, F.H.; Zhang, P.

    2013-10-15

    Graphical abstract: Graphene/LiFePO{sub 4} composites as a high-performance cathode material for flexible lithium-ion batteries have been prepared by using a co-precipitation method to synthesize graphene/LiFePO4 powders as precursors and then followed by a solvent evaporation process. - Highlights: • Flexible LiFePO{sub 4}/graphene films were prepared first time by a solvent evaporation process. • The flexible electrode exhibited a high discharge capacity without conductive additives. • Graphene network offers the electrode adequate strength to withstand repeated flexing. - Abstract: Three-dimensional graphene/LiFePO{sub 4} nanostructures for flexible lithium-ion batteries were successfully prepared by solvent evaporation method. Structural characteristics of flexible electrodes were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Electrochemical performance of graphene/LiFePO{sub 4} was examined by a variety of electrochemical testing techniques. The graphene/LiFePO{sub 4} nanostructures showed high electrochemical properties and significant flexibility. The composites with low graphene content exhibited a high capacity of 163.7 mAh g{sup −1} at 0.1 C and 114 mAh g{sup −1} at 5 C without further incorporation of conductive agents.

  11. Facile synthesis of porous Li2S@C composites as cathode materials for lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Liang, Sheng; Liang, Chu; Xia, Yang; Xu, Haohui; Huang, Hui; Tao, Xinyong; Gan, Yongping; Zhang, Wenkui

    2016-02-01

    Lithium sulfide (Li2S) is regarded as a promising cathode material for lithium-sulfur (Li-S) batteries in terms of its high theoretical specific capacity of 1166 mAh g-1 and good compatibility with lithium metal-free anodes. However, Li2S suffers from poor cycling stability and rate capability resulted from the serious shuttle effect of lithium polysulfides and its low electronic and ionic conductivity. Here, we present a facile ball milling combined with carbon coating method to synthesize porous carbon-coated Li2S (Li2S@C) composites with a high Li2S content by using polystyrene (PS) as a carbon precursor. The Li2S@C composites show a high reversible specific capacity of 676 mAh g-1 (equal to 971 mAh g-1 sulfur) after 3 cycles at the current density of 0.1 A g-1, superior cycling stability with an average decay rate of 0.18% per cycle over 200 cycles, and improved rate capability of 416 mAh g-1 at the current density of 1.0 A g-1. The enhanced electrochemical properties of Li2S can be attributed to the porosity and core-shell structure of the Li2S@C composites, which increased the electronic and ionic conductivity of Li2S and alleviated the shuttle effect of intermediate lithium polysulfides in the discharge/charge process.

  12. Facile Synthesis of Boron-Doped rGO as Cathode Material for High Energy Li-O2 Batteries.

    PubMed

    Wu, Feng; Xing, Yi; Li, Li; Qian, Ji; Qu, Wenjie; Wen, Jianguo; Miller, Dean; Ye, Yusheng; Chen, Renjie; Amine, Khalil; Lu, Jun

    2016-09-14

    To improve the electrochemical performance of the high energy Li-O2 batteries, it is important to design and construct a suitable and effective oxygen-breathing cathode. Herein, a three-dimensional (3D) porous boron-doped reduction graphite oxide (B-rGO) material with a hierarchical structure has been prepared by a facile freeze-drying method. In this design, boric acid as the boron source helps to form the 3D porous structure, owing to its cross-linking and pore-forming function. This architecture facilitates the rapid oxygen diffusion and electrolyte penetration in the electrode. Meanwhile, the boron-oxygen functional groups linking to the carbon surface or edge serve as additional reaction sites to activate the ORR process. It is vital that boron atoms have been doped into the carbon lattices to greatly activate the electrons in the carbon π system, which is beneficial for fast charge under large current densities. Density functional theory calculation demonstrates that B-rGO exhibits much stronger interactions with Li5O6 clusters, so that B-rGO more effectively activates Li-O bonds to decompose Li2O2 during charge than rGO does. With B-rGO as a catalytic substrate, the Li-O2 battery achieves a high discharge capacity and excellent rate capability. Moreover, catalysts could be added into the B-rGO substrate to further lower the overpotential and enhance the cycling performance in future. PMID:27549204

  13. Observation of Electron-Beam-Induced Phase Evolution Mimicking the Effect of the Charge–Discharge Cycle in Li-Rich Layered Cathode Materials Used for Li Ion Batteries

    DOE PAGESBeta

    Lu, Ping; Yan, Pengfei; Romero, Eric; Spoerke, Erik David; Zhang, Ji-Guang; Wang, Chong-Min

    2015-01-27

    Capacity loss, and voltage decrease upon electrochemical charge-discharge cycling observed in lithium-rich layered cathode oxides (Li[LixMnyTM1-x-y]O2, TM = Ni, Co or Fe) have recently been attributed to the formation of a surface reconstructed layer (SRL) that evolves from a thin (<2 nm), defect spinel layer upon the first charge, to a relatively thick (~5nm), spinel or rock-salt layer upon continuous charge-discharge cycling. Here we report observations of a SRL and structural evolution of the SRL on the Li[Li0.2Ni0.2Mn0.6]O2 (LNMO) particles, which are identical to those reported due to the charge-discharge cycle but are a result of electron-beam irradiation during scanningmore » transmission electron microscopy (STEM) imaging. Sensitivity of the lithium-rich layered oxides to high-energy electrons leads to the formation of thin, defect spinel layer on surfaces of the particles when exposed to a 200kV electron beam for as little as 30 seconds under normal high-resolution STEM imaging conditions. Further electron irradiation produces a thicker layer of the spinel phase, ultimately producing a rock-salt layer at a higher electron exposure. Atomic-scale chemical mapping by electron dispersive X-ray spectroscopy in STEM indicates the electron-beam-induced SRL formation on LNMO is accomplished by migration of the transition metal ions to the Li sites without breaking down the lattice. The observation through this study provides an insight for understanding the mechanism of forming the SRL and also possibly a mean to study structural evolution in the Li-rich layered oxides without involving the electrochemistry.« less

  14. Observation of Electron-Beam-Induced Phase Evolution Mimicking the Effect of the Charge–Discharge Cycle in Li-Rich Layered Cathode Materials Used for Li Ion Batteries

    SciTech Connect

    Lu, Ping; Yan, Pengfei; Romero, Eric; Spoerke, Erik David; Zhang, Ji-Guang; Wang, Chong-Min

    2015-01-27

    Capacity loss, and voltage decrease upon electrochemical charge-discharge cycling observed in lithium-rich layered cathode oxides (Li[LixMnyTM1-x-y]O2, TM = Ni, Co or Fe) have recently been attributed to the formation of a surface reconstructed layer (SRL) that evolves from a thin (<2 nm), defect spinel layer upon the first charge, to a relatively thick (~5nm), spinel or rock-salt layer upon continuous charge-discharge cycling. Here we report observations of a SRL and structural evolution of the SRL on the Li[Li0.2Ni0.2Mn0.6]O2 (LNMO) particles, which are identical to those reported due to the charge-discharge cycle but are a result of electron-beam irradiation during scanning transmission electron microscopy (STEM) imaging. Sensitivity of the lithium-rich layered oxides to high-energy electrons leads to the formation of thin, defect spinel layer on surfaces of the particles when exposed to a 200kV electron beam for as little as 30 seconds under normal high-resolution STEM imaging conditions. Further electron irradiation produces a thicker layer of the spinel phase, ultimately producing a rock-salt layer at a higher electron exposure. Atomic-scale chemical mapping by electron dispersive X-ray spectroscopy in STEM indicates the electron-beam-induced SRL formation on LNMO is accomplished by migration of the transition metal ions to the Li sites without breaking down the lattice. The observation through this study provides an insight for understanding the mechanism of forming the SRL and also possibly a mean to study structural evolution in the Li-rich layered oxides without involving the electrochemistry.

  15. Observation Of Electron-beam-induced Phase Evolution Mimicking The Effect Of Charge-discharge Cycle In Li-rich Layered Cathode Materials Used For Li-ion Batteries

    SciTech Connect

    Lu, Ping; Yan, Pengfei; Romero, Eric; Spoerke, Erik D.; Zhang, Jiguang; Wang, Chong M.

    2015-02-24

    Capacity loss, and voltage fade upon electrochemical charge-discharge cycling observed in lithium-rich layered cathode oxides (Li[LixMnyTM1-x-y]O2 , TM = Ni, Co or Fe) have recently been identified to be correlated to the gradual phase transformation, featuring the formation of a surface reconstructed layer (SRL) that evolves from a thin (<2 nm), defect spinel layer upon the first charge, to a relatively thick (~5 nm), spinel or rock-salt layer upon continuous charge-discharge cycling. Here we report observations of a SRL and structural evolution of the SRL on the Li[Li0.2Ni0.2Mn0.6]O2 (LMR) particles, which are identical to those reported due to the charge-discharge cycle but are a result of electron-beam irradiation during scanning transmission electron microscopy (STEM) imaging. Sensitivity of the lithium-rich layered oxides to high-energy electrons leads to the formation of thin, defect spinel layer on surfaces of the particles when exposed to a 200 kV electron beam for as little as 30 seconds under normal high-resolution STEM imaging conditions. Further electron irradiation produces a thicker layer of the spinel phase, ultimately producing a rock-salt layer at a higher electron exposure. Atomic-scale chemical mapping by energy dispersive X-ray spectroscopy in STEM indicates the electron-beam-induced SRL formation on LMR is accomplished by migration of the transition metal ions to the Li sites without breaking down the lattice. This study provides an insight for understanding the mechanism of forming the SRL and also possibly a mean to study structural evolution in the Li-rich layered oxides without involving the electrochemistry.

  16. Ab initio study of vacancy formation in cubic LaMnO3 and SmCoO3 as cathode materials in solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Olsson, Emilia; Aparicio-Anglès, Xavier; de Leeuw, Nora H.

    2016-07-01

    Doped LaMnO3 and SmCoO3 are important solid oxide fuel cell cathode materials. The main difference between these two perovskites is that SmCoO3 has proven to be a more efficient cathode material than LaMnO3 at lower temperatures. In order to explain the difference in efficiency, we need to gain insight into the materials' properties at the atomic level. However, while LaMnO3 has been widely studied, ab initio studies on SmCoO3 are rare. Hence, in this paper, we perform a comparative DFT + U study of the structural, electronic, and magnetic properties of these two perovskites. To that end, we first determined a suitable Hubbard parameter for the Co d-electrons to obtain a proper description of SmCoO3 that fully agrees with the available experimental data. We next evaluated the impact of oxygen and cation vacancies on the geometry, electronic, and magnetic properties. Oxygen vacancies strongly alter the electronic and magnetic structures of SmCoO3, but barely affect LaMnO3. However, due to their high formation energy, their concentrations in the material are very low and need to be induced by doping. Studying the cation vacancy concentration showed that the formation of cation vacancies is less energetically favorable than oxygen vacancies and would thus not markedly influence the performance of the cathode.

  17. Ab initio study of vacancy formation in cubic LaMnO3 and SmCoO3 as cathode materials in solid oxide fuel cells.

    PubMed

    Olsson, Emilia; Aparicio-Anglès, Xavier; de Leeuw, Nora H

    2016-07-01

    Doped LaMnO3 and SmCoO3 are important solid oxide fuel cell cathode materials. The main difference between these two perovskites is that SmCoO3 has proven to be a more efficient cathode material than LaMnO3 at lower temperatures. In order to explain the difference in efficiency, we need to gain insight into the materials' properties at the atomic level. However, while LaMnO3 has been widely studied, ab initio studies on SmCoO3 are rare. Hence, in this paper, we perform a comparative DFT + U study of the structural, electronic, and magnetic properties of these two perovskites. To that end, we first determined a suitable Hubbard parameter for the Co d-electrons to obtain a proper description of SmCoO3 that fully agrees with the available experimental data. We next evaluated the impact of oxygen and cation vacancies on the geometry, electronic, and magnetic properties. Oxygen vacancies strongly alter the electronic and magnetic structures of SmCoO3, but barely affect LaMnO3. However, due to their high formation energy, their concentrations in the material are very low and need to be induced by doping. Studying the cation vacancy concentration showed that the formation of cation vacancies is less energetically favorable than oxygen vacancies and would thus not markedly influence the performance of the cathode. PMID:27394117

  18. Visualizing nanoscale 3D compositional fluctuation of lithium in advanced lithium-ion battery cathodes

    SciTech Connect

    Devaraj, Arun; Gu, Meng; Colby, Robert J.; Yan, Pengfei; Wang, Chong M.; Zheng, Jianming; Xiao, Jie; Genc, Arda; Zhang, Jiguang; Belharouak, Ilias; Wang, Dapeng; Amine, Khalil; Thevuthasan, Suntharampillai

    2015-08-14

    The distribution and concentration of lithium in Li-ion battery cathodes at different stages of cycling is a pivotal factor in determining battery performance. Non-uniform distribution of the transition metal cations has been shown to affect cathode performance; however, the Li is notoriously challenging to characterize with typical high-spatial-resolution imaging techniques. Here, for the first time, laser–assisted atom probe tomography is applied to two advanced Li-ion battery oxide cathode materials—layered Li1.2Ni0.2Mn0.6O2 and spinel LiNi0.5Mn1.5O4—to unambiguously map the three dimensional (3D) distribution of Li at sub-nanometer spatial resolution and correlate it with the distribution of the transition metal cations (M) and the oxygen. The as-fabricated layered Li1.2Ni0.2Mn0.6O2 is shown to have Li-rich Li2MO3 phase regions and Li-depleted Li(Ni0.5Mn0.5)O2 regions while in the cycled layered Li1.2Ni0.2Mn0.6O2 an overall loss of Li and presence of Ni rich regions, Mn rich regions and Li rich regions are shown in addition to providing the first direct evidence for Li loss on cycling of layered LNMO cathodes. The spinel LiNi0.5Mn1.5O4 cathode is shown to have a uniform distribution of all cations. These results were additionally validated by correlating with energy dispersive spectroscopy mapping of these nanoparticles in a scanning transmission electron microscope. Thus, we have opened the door for probing the nanoscale compositional fluctuations in crucial Li-ion battery cathode materials at an unprecedented spatial resolution of sub-nanometer scale in 3D which can provide critical information for understanding capacity decay mechanisms in these advanced cathode materials.

  19. Visualizing nanoscale 3D compositional fluctuation of lithium in advanced lithium-ion battery cathodes

    DOE PAGESBeta

    Devaraj, Arun; Gu, Meng; Colby, Robert J.; Yan, Pengfei; Wang, Chong M.; Zheng, Jianming; Xiao, Jie; Genc, Arda; Zhang, Jiguang; Belharouak, Ilias; et al

    2015-08-14

    The distribution and concentration of lithium in Li-ion battery cathodes at different stages of cycling is a pivotal factor in determining battery performance. Non-uniform distribution of the transition metal cations has been shown to affect cathode performance; however, the Li is notoriously challenging to characterize with typical high-spatial-resolution imaging techniques. Here, for the first time, laser–assisted atom probe tomography is applied to two advanced Li-ion battery oxide cathode materials—layered Li1.2Ni0.2Mn0.6O2 and spinel LiNi0.5Mn1.5O4—to unambiguously map the three dimensional (3D) distribution of Li at sub-nanometer spatial resolution and correlate it with the distribution of the transition metal cations (M) and themore » oxygen. The as-fabricated layered Li1.2Ni0.2Mn0.6O2 is shown to have Li-rich Li2MO3 phase regions and Li-depleted Li(Ni0.5Mn0.5)O2 regions while in the cycled layered Li1.2Ni0.2Mn0.6O2 an overall loss of Li and presence of Ni rich regions, Mn rich regions and Li rich regions are shown in addition to providing the first direct evidence for Li loss on cycling of layered LNMO cathodes. The spinel LiNi0.5Mn1.5O4 cathode is shown to have a uniform distribution of all cations. These results were additionally validated by correlating with energy dispersive spectroscopy mapping of these nanoparticles in a scanning transmission electron microscope. Thus, we have opened the door for probing the nanoscale compositional fluctuations in crucial Li-ion battery cathode materials at an unprecedented spatial resolution of sub-nanometer scale in 3D which can provide critical information for understanding capacity decay mechanisms in these advanced cathode materials.« less

  20. A multi-core-shell structured composite cathode material with a conductive polymer network for Li-S batteries.

    PubMed

    Wang, Mengjia; Wang, Weikun; Wang, Anbang; Yuan, Keguo; Miao, Lixiao; Zhang, Xiaolin; Huang, Yaqin; Yu, Zhongbao; Qiu, Jingyi

    2013-11-11

    A multi-core-shell with a conductive network structured C-PANI-S@PANI composite with high sulfur content up to 87% was synthesized. The composite cathode delivers higher specific capacity and excellent cycle stability, retaining a reversible discharge capacity of 835 mA h g(-1) after 100 cycles when the sulfur loading of the cathode was above 6 mg cm(-2). PMID:23999983

  1. Understanding the effects of a multi-functionalized additive on the cathode-electrolyte interfacial stability of Ni-rich materials

    NASA Astrophysics Data System (ADS)

    Yim, Taeeun; Kang, Kyoung Seok; Mun, Junyoung; Lim, Sang Hoo; Woo, Sang-Gil; Kim, Ki Jae; Park, Min-Sik; Cho, Woosuk; Song, Jun Ho; Han, Young-Kyu; Yu, Ji-Sang; Kim, Young-Jun

    2016-01-01

    Nickel-rich lithium nickel cobalt manganese oxides have received considerable attention as a promising cathode material, however, they have suffered from poor interfacial stability, especially at high temperature. Here, we suggest a bi-functionalized divinyl sulfone that enhances the applicability of a nickel-rich cathode via stabilization of the electrolyte-electrode interface. The divinyl sulfone forms a protective layer on the cathode surface by electrochemical oxidation reactions and this greatly decreases the internal pressure of the cell via stabilization of the Ni-rich cathode-electrolyte interface. The cell controlled with divinyl sulfone shows remarkable cycling performance with 91.9% capacity retention at elevated temperature even after 100 cycles. Additional electrode analyses and first-principles calculations provide critical spectroscopic evidences to demonstrate the combined effects of the sulfone and vinyl functional groups. Once the divinyl sulfone is electrochemically oxidized, the vinyl functional groups readily participate in further stabilizing sulfone-based solid electrolyte interphase intermediates and afford a durable protective layer on the nickel-rich electrode surface.

  2. Analysis of optimization processses for solid state fabrication of olivine cathode materials

    NASA Astrophysics Data System (ADS)

    Oladimeji, Charles

    Lithium ion battery discovered since the 1980s has become pivotal to our energy needs. With the need for a shift to renewable energy and increased use of portable devices, energy storage has become a very important aspect of modern day life and technology. In the thesis, optimization techniques for solid state calcination of lithium olivine batteries are characterized and analyzed. A brief introduction into lithium ion battery is discussed, the chemistry and physics of the materials is studied in details. Emphasis is placed on the olivine structure, industrially utilized synthesis method and the performance of olivine lithium ion batteries are also discussed in details. Olivine structure LiFePO4 (LFP) was synthesized via solid state processes, using Li2CO3, NH4H 2PO4 and FeC2O4˙H2O and C12H22O11 as precursor materials. The effects of calendaring in terms of charge/discharge capacity, cycle life performance, surface morphology, and ac impedance was analyzed. The resulting LFP electrode was divided in part, Part A was left as is and Part B was calendared. The calendared electrode exhibited lower impedance under electrochemical impedance test. The calendared electrode also exhibited a higher discharge capacity of about 130 mAh/g at 0.1C compared to the as-is electrode with discharge capacity of about 120mAh/g. Olivine structure LiMnPO4 (LMP) was also synthesized via solid state processes, using Li2CO3, NH4H 2PO4, MnCO3 and C12H22O 11 as precursor materials. Comparison of the carbon addition process was done by adding sucrose to the initial precursor mix and carbon black at the later stages of fabrication. The 3 step carbon addition exhibited the highest specific capacity of about 72mAh/g, 1 step carbon addition possessed the least capacity of about 45mAh/g, while the 2 step process had a capacity of about 65mA/g.

  3. Freeze-dryed LixMoO3 nanobelts used as cathode materials for lithium-ion batteries: A bulk and interface study

    NASA Astrophysics Data System (ADS)

    Villevieille, Claire; Gorzkowska-Sobas, Agnieszka; Fjellvåg, Helmer; Novák, Petr

    2015-11-01

    Through a chemical lithiation method, we were able to modify the well-known anode material MoO3 to develop a new kind of a high specific energy cathode. Thus, nanobelts of MoO3 were synthetized and chemically lithiated to obtain nominally LiMoO3 (composition discovered via DFT calculations). This electrode material showed enhanced electrochemical performance (>150 mAh/g for a loading of 4 mg/cm2 at 3C rate) and can be considered as a novel cathode with high specific charge. Its reaction mechanism was explored via high resolution in situ XRD and post mortem SEM analysis, which revealed almost no damage to the nanobelts after 50 cycles.

  4. Corrosion testing of candidates for the alkaline fuel cell cathode

    NASA Technical Reports Server (NTRS)

    Singer, Joseph; Fielder, William L.

    1989-01-01

    Current/voltage data was obtained for specially made corrosion electrodes of some oxides and of gold materials for the purpose of developing a screening test of catalysts and supports for use at the cathode of the alkaline fuel cell. The data consists of measurements of current at fixed potentials and cyclic voltammograms. These data will have to be correlated with longtime performance data in order to fully evaluate this approach to corrosion screening. Corrosion test screening of candidates for the oxygen reduction electrode of the alkaline fuel cell was applied to two substances, the pyrochlore Pb2Ru2O6.5 and the spinel NiCo2O4. The substrate gold screen and a sample of the IFC Orbiter Pt-Au performance electrode were included as blanks. The pyrochlore data indicate relative stability, although nothing yet can be said about long term stability. The spinel was plainly unstable. For this type of testing to be validated, comparisons will have to be made with long term performance tests.

  5. Layered Li-Mn-M-oxides as cathodes for Li-ion batteries:. Recent trends

    NASA Astrophysics Data System (ADS)

    Shaju, K. M.; Subba Rao, G. V.; Chowdari, B. V. R.

    2002-12-01

    There is an increasing demand for manganese (Mn) based mixed oxides which can effectively replace the presently used LiCoO2 as cathode in Li-ion batteries (LIB). The well-studied spinel, LiMn2O4 and its doped derivatives give a capacity of 100-120 mAh/g, but show capacity-fading on cycling especially above 55°C. The layered LiMnO2, isostructural to LiCoO2 (so called O3-structure) can be a viable cathode. However, studies have shown that it undergoes conversion to spinel structure on cycling and thus gives capacity-fading. Other alternative systems recently studied are: O2-structured layered Li-M-Mn-oxides with the general formula Li(2/3)+x(MyMn1-y)O2, M = Li, Ni, Co; x ≤ 0.33 and y = 0.1-0.67, O3-Li(Ni1/2Mn1/2)O2, Li(NixCo1-2xMnx)O2, and M'-substituted Li2MnO3 (M' = Ni, Co, Cr). Some of them are shown to have stable cycling performance, good rate-capability and structural stability over charge-discharge cycling in the 2.5-4.6 V region. Further, the electrochemical processes in the above mixed oxides have been shown to involve Ni2+/4+ or Cr3+/6+ redox couple, thus invoking novel ideas to develop new cathode materials. A brief review of the work done on the above O2- and O3-layered Li-Mn-M-oxides (M = metal) as cathodes for LIB is presented.

  6. One-step hydrothermal method synthesis of core-shell LiNi0.5Mn1.5O4 spinel cathodes for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Liu, Yuanzhuang; Zhang, Minghao; Xia, Yonggao; Qiu, Bao; Liu, Zhaoping; Li, Xing

    2014-06-01

    Spherical LiNi0.5Mn1.5O4 material with a core-shell structure is synthesized by a urea-assisted hydrothermal method followed by heat treatment with LiOH at high temperature. After the process of hydrothermal treatment, the carbonate precursor with a concentration gradient is produced, in a single spherical particle, the content of Ni in the surface is higher than that in the center while Mn has a reversal trend. LiNi0.5Mn1.5O4 synthesized through the hydrothermal route has a great improvement in cycling stability at elevated temperature and rate capability. The capacity retention can maintain at 95% after 30 cycles at 55 °C. Furthermore, it can deliver a discharge capacity of 118 mAh g-1 at a high rate of 10 C at room temperature. Such excellent electrochemical properties of LiNi0.5Mn1.5O4 can be ascribed to its unique core-shell structure and nano-size particle.

  7. Hierarchical sulfur-based cathode materials with long cycle life for rechargeable lithium batteries.

    PubMed

    Wang, Jiulin; Yin, Lichao; Jia, Hao; Yu, Haitao; He, Yushi; Yang, Jun; Monroe, Charles W

    2014-02-01

    Composite materials of porous pyrolyzed polyacrylonitrile-sulfur@graphene nanosheet (pPAN-S@GNS) are fabricated through a bottom-up strategy. Microspherical particles are formed by spray drying of a mixed aqueous colloid of PAN nanoparticles and graphene nanosheets, followed by a simple heat treatment with elemental sulfur. The pPAN-S primary nanoparticles are wrapped homogeneously and loosely within a three-dimensional network of graphene nanosheets (GNS). The hierarchical pPAN-S@GNS composite shows a high reversible capacity of 1449.3 mAh g(-1) sulfur or 681.2 mAh g(-1) composite in the second cycle; after 300 cycles at a 0.2 C charge/discharge rate the capacity retention is 88.8 % of its initial reversible value. Additionally, the coulombic efficiency (CE) during cycling is near 100 %, apart from in the first cycle, in which CE is 81.1 %. A remarkable capacity of near 700 mAh g(-1) sulfur is obtained, even at a high discharge rate of 10 C. The superior performance of pPAN-S@GNS is ascribed to the spherical secondary GNS structure that creates an electronically conductive 3D framework and also reinforces structural stability. PMID:24155121

  8. Enhanced rate performance of multiwalled carbon nanotube encrusted olivine type composite cathode material using polyol technique

    NASA Astrophysics Data System (ADS)

    Muruganantham, R.; Sivakumar, M.; Subadevi, R.

    2015-12-01

    Olivine type multi-walled carbon nanotube encrusted LiFePO4/C composites have been prepared using economic and energy efficient simple polyol technique without any subsequent heat treatment. The prepared material has an olivine type orthorhombic phase. Also, the iron oxidation state is 2+, which is identified by X-ray diffraction and X-ray photoelectron spectroscopy. It is possible to attain the discharge capacity almost close to theoretical capacity of LiFePO4 as in high temperature methods with ∼100% coulombic efficiency. The specific surface area has been increased upon encrusting multi walled carbon nano tube on LiFePO4/C, which results in enhanced reversible capacity upto 166 mAh g-1 at C/10. Also, it exhibits 89 mAh g-1 even at 30 C rate. This is due to the formation of conductive networks by carbon nanotube, and excellent attachment of LiFePO4/C composite particles on multi-walled carbon nanotube, which induced the kinetics during intercalation/deintercalation process. Multi-walled carbon nanotube acts as the electro-conductive filler on the LiFePO4 surface. The direct addition of MWCNT would result better performances than blending the MWCNT with LiFePO4/C.

  9. Infiltrating sulfur into a highly porous carbon sphere as cathode material for lithium–sulfur batteries

    SciTech Connect

    Zhao, Xiaohui; Kim, Dul-Sun; Ahn, Hyo-Jun; Kim, Ki-Won; Cho, Kwon-Koo; Ahn, Jou-Hyeon

    2014-10-15

    Highlights: • A highly porous carbon (HPC) with regular spherical morphology was synthesized. • Sulfur/HPC composites were prepared by melt–diffusion method. • Sulfur/HPC composites showed improved cyclablity and long-term cycle life. - Abstract: Sulfur composite material with a highly porous carbon sphere as the conducting container was prepared. The highly porous carbon sphere was easily synthesized with resorcinol–formaldehyde precursor as the carbon source. The morphology of the carbon was observed with field emission scanning electron microscope and transmission electron microscope, which showed a well-defined spherical shape. Brunauer–Emmett–Teller analysis indicated that it possesses a high specific surface area of 1563 m{sup 2} g{sup −1} and a total pore volume of 2.66 cm{sup 3} g{sup −1} with a bimodal pore size distribution, which allow high sulfur loading and easy transportation of lithium ions. Sulfur carbon composites with varied sulfur contents were prepared by melt–diffusion method and lithium sulfur cells with the sulfur composites showed improved cyclablity and long-term cycle life.

  10. Discharge/charge reaction mechanisms of FeS2 cathode material for aluminum rechargeable batteries at 55°C

    NASA Astrophysics Data System (ADS)

    Mori, Takuya; Orikasa, Yuki; Nakanishi, Koji; Kezheng, Chen; Hattori, Masashi; Ohta, Toshiaki; Uchimoto, Yoshiharu

    2016-05-01

    The aluminum rechargeable battery is a desirable device for large-scale energy storage owing to the high capacity derived from the properties of the aluminum metal anode. The development of cathode materials is needed to compose battery systems. However, the design principles of the cathode materials have not been determined. We focus on the high capacity FeS2 cathode materials and investigate the discharge/charge reaction mechanisms in chloroaluminate ionic liquids as the electrolyte at 55°C. X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) measurements are performed for the discharged and charged samples. S 3p-orbitals are shown to play an important role in the redox reactions from the results of the S and Fe K-edge XANES spectra. As a result of the redox reaction, FeS2 is transformed into low crystalline FeS and amorphous Al2S3, as shown by the XRD and S, Al, and Fe K-edge XANES spectra. This reaction mechanism is different from the reaction observed with lithium ion.

  11. Nitrogen-doped graphene-decorated LiVPO4F nanocomposite as high-voltage cathode material for rechargeable lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Cui, Kai; Hu, Shuchun; Li, Yongkui

    2016-09-01

    In this study, nitrogen-doped graphene decorated LiVPO4F cathode material is firstly synthesized via a facile method. Well-dispersed LiVPO4F nanoparticles are embedded in nitrogen-doped graphene nanosheets, forming an effective conducting network. The added nitrogen-doped graphene nanosheets greatly enhance the electronic conductivity and Li-ion diffusion of LiVPO4F sample. When tested as cathode material for rechargeable lithium-ion batteries, the hybrid electrode exhibits superior high-rate performance and long-term cycling stability between 3.0 and 4.5 V. It delivers a large discharge capacity of 152.7 mAhg-1 at 0.1 C and shows a capacity retention of 97.8% after 60 cycles. Moreover, a reversible capacity of 90.1 mAhg-1 is maintained even after 500 cycles at a high rate of 20 C. The charge-transfer resistance of LiVPO4F electrode is also reduced in the nitrogen-doped graphene, revealing that its electrode-electrolyte complex reactions take place easily and thus improve the electrochemical performance. The above results provide a facile and effective strategy for the synthesis of LiVPO4F cathode material for high-performance lithium-ion batteries.

  12. An efficient electrocatalyst as cathode material for solid oxide fuel cells: BaFe0·95Sn0·05O3-δ

    NASA Astrophysics Data System (ADS)

    Dong, Feifei; Ni, Meng; He, Wei; Chen, Yubo; Yang, Guangming; Chen, Dengjie; Shao, Zongping

    2016-09-01

    The B-site substitution with the minor amount of tin in BaFeO3-δ parent oxide is expected to stabilize a single perovskite lattice structure. In this study, a composition of BaFe0·95Sn0·05O3-δ (BFS) as a new cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs) is synthesized and characterized. Special attention is paid to the exploration of some basic properties including phase structure, oxygen non-stoichiometry, electrical conductivity, oxygen bulk diffusion coefficient, and surface exchange coefficient, which are of significant importance to the electrochemical activity of cathode materials. BFS holds a single cubic perovskite structure over temperature range of cell operation, determined by in-situ X-ray diffraction and scanning transmission electron microscope. A high oxygen vacancy concentration at cell operating temperatures is observed by combining thermo-gravimetric data and iodometric titration result. Furthermore, electrical conductivity relaxation measurement illustrates the fast oxygen bulk diffusion and surface exchange kinetics. Accordingly, testing cells based on BFS cathode material demonstrate the low polarization resistance of 0.033 Ω cm2 and high peak power density of 1033 mW cm-2 at 700 °C, as well as a relatively stable long-term operation for ∼300 h. The results obtained suggest that BFS perovskite oxide holds a great promise as an oxygen reduction electrocatalyst for IT-SOFCs.

  13. Isothermal calorimetry investigation of Li{sub 1+x}Mn{sub 2-y}Al{sub z}O{sub 4} spinel.

    SciTech Connect

    Lu, W.; Belharouak, I.; Park, S. H.; Sun, Y. K; Amine, K.; Chemical Engineering; Hanyang Univ.

    2007-05-25

    The heat generation of LiMn{sub 2}O{sub 4}, Li{sub 1.156}Mn{sub 1.844}O{sub 4}, and Li{sub 1.06}Mn{sub 1.89}Al{sub 0.05}O{sub 4} spinel cathode materials in a half-cell system was investigated by isothermal micro-calorimetry (IMC). The heat variations of the Li/LiMn{sub 2}O{sub 4} cell during charging were attributed to the LiMn{sub 2}O{sub 4} phase transition and order/disorder changes. This heat variation was largely suppressed when the stoichiometric spinel was doped with excess lithium or lithium and aluminum. The calculated entropy change (dE/dT) from the IMC confirmed that the order/disorder change of LiMn{sub 2}O{sub 4}, which occurs in the middle of the charge, was largely suppressed with lithium or lithium and aluminum doping. The dE/dT values obtained did not agree between the charge and the discharge at room temperature (25 C), which was attributed to cell self-discharge. This discrepancy was not observed at low temperature (10 C). Differential scanning calorimeter (DSC) results showed that the fully charged spinel with lithium doping has better thermal stability.

  14. Thermodynamic Stability of Transition-Metal-Substituted LiMn2-x Mx O4 (M=Cr, Fe, Co, and Ni) Spinels.

    PubMed

    Lai, Chenying; Chen, Jiewei; Knight, James C; Manthiram, Arumugam; Navrotsky, Alexandra

    2016-07-01

    The formation enthalpies from binary oxides of LiMn2 O4 , LiMn2-x Crx O4 (x=0.25, 0.5, 0.75 and 1), LiMn2-x Fex O4 (x=0.25 and 0.5), LiMn2-x Cox O4 (x=0.25, 0.5, and 0.75) and LiMn1.75 Ni0.25 O4 at 25 °C were measured by high temperature oxide melt solution calorimetry and were found to be strongly exothermic. Increasing the Cr, Co, and Ni content leads to more thermodynamically stable spinels, but increasing the Fe content does not significantly affect the stability. The formation enthalpies from oxides of the fully substituted spinels, LiMnMO4 (M=Cr, Fe and Co), become more exothermic (implying increasing stability) with decreasing ionic radius of the metal and lattice parameters of the spinel. The trend in enthalpy versus metal content is roughly linear, suggesting a close-to-zero heat of mixing in LiMn2 O4 -LiMnMO4 solid solutions. These data confirm that transition-metal doping is beneficial for stabilizing these potential cathode materials for lithium-ion batteries. PMID:27017448

  15. New materials for Li-ion batteries: synthesis and spectroscopic characterization of Li2(FeMnCo)SiO4 cathode materials.

    PubMed

    Ferrari, Stefania; Mozzati, Maria Cristina; Lantieri, Marco; Spina, Gabriele; Capsoni, Doretta; Bini, Marcella

    2016-01-01

    Improving cathode materials is mandatory for next-generation Li-ion batteries. Exploring polyanion compounds with high theoretical capacity such as the lithium metal orthosilicates, Li2MSiO4 is of great importance. In particular, mixed silicates represent an advancement with practical applications. Here we present results on a rapid solid state synthesis of mixed Li2(FeMnCo)SiO4 samples in a wide compositional range. The solid solution in the P21/n space group was found to be stable for high iron concentration or for a cobalt content up to about 0.3 atom per formula unit. Other compositions led to a mixture of polymorphs, namely Pmn21 and Pbn21. All the samples contained a variable amount of Fe(3+) ions that was quantified by Mössbauer spectroscopy and confirmed by the TN values of the paramagnetic to antiferromagnetic transition. Preliminary characterization by cyclic voltammetry revealed the effect of Fe(3+) on the electrochemical response. Further work is required to determine the impact of these electrode materials on lithium batteries. PMID:27293181

  16. New materials for Li-ion batteries: synthesis and spectroscopic characterization of Li2(FeMnCo)SiO4 cathode materials

    NASA Astrophysics Data System (ADS)

    Ferrari, Stefania; Mozzati, Maria Cristina; Lantieri, Marco; Spina, Gabriele; Capsoni, Doretta; Bini, Marcella

    2016-06-01

    Improving cathode materials is mandatory for next-generation Li-ion batteries. Exploring polyanion compounds with high theoretical capacity such as the lithium metal orthosilicates, Li2MSiO4 is of great importance. In particular, mixed silicates represent an advancement with practical applications. Here we present results on a rapid solid state synthesis of mixed Li2(FeMnCo)SiO4 samples in a wide compositional range. The solid solution in the P21/n space group was found to be stable for high iron concentration or for a cobalt content up to about 0.3 atom per formula unit. Other compositions led to a mixture of polymorphs, namely Pmn21 and Pbn21. All the samples contained a variable amount of Fe3+ ions that was quantified by Mössbauer spectroscopy and confirmed by the TN values of the paramagnetic to antiferromagnetic transition. Preliminary characterization by cyclic voltammetry revealed the effect of Fe3+ on the electrochemical response. Further work is required to determine the impact of these electrode materials on lithium batteries.

  17. New materials for Li-ion batteries: synthesis and spectroscopic characterization of Li2(FeMnCo)SiO4 cathode materials

    PubMed Central

    Ferrari, Stefania; Mozzati, Maria Cristina; Lantieri, Marco; Spina, Gabriele; Capsoni, Doretta; Bini, Marcella

    2016-01-01

    Improving cathode materials is mandatory for next-generation Li-ion batteries. Exploring polyanion compounds with high theoretical capacity such as the lithium metal orthosilicates, Li2MSiO4 is of great importance. In particular, mixed silicates represent an advancement with practical applications. Here we present results on a rapid solid state synthesis of mixed Li2(FeMnCo)SiO4 samples in a wide compositional range. The solid solution in the P21/n space group was found to be stable for high iron concentration or for a cobalt content up to about 0.3 atom per formula unit. Other compositions led to a mixture of polymorphs, namely Pmn21 and Pbn21. All the samples contained a variable amount of Fe3+ ions that was quantified by Mössbauer spectroscopy and confirmed by the TN values of the paramagnetic to antiferromagnetic transition. Preliminary characterization by cyclic voltammetry revealed the effect of Fe3+ on the electrochemical response. Further work is required to determine the impact of these electrode materials on lithium batteries. PMID:27293181

  18. History of development of polycrystalline optical spinel in the U.S.

    NASA Astrophysics Data System (ADS)

    Harris, Daniel C.

    2005-05-01

    Optical quality polycrystalline spinel (MgAl2O4) has been sought as a visible- and infrared-transmitting material since the 1960s because of its potential for transparent armor and durable sensor windows. Its physical properties were known from synthetic crystals available since ~1950 from Linde Air Products. In the late 1960s, methods to process powder into transparent, polycrystalline spinel were investigated at North Carolina State University, General Electric Co., AVCO, and Westinghouse, mainly with Government support. The leading figure in the development of polycrystalline spinel was Don Roy, who began work on spinel at Coors Ceramics around 1970, initially for transparent armor. In the late 1970s, both Coors Ceramics and Raytheon Research Division were funded to make spinel for the infrared dome of the Advanced Short-Range Air-to-Air Missile, an application that disappeared by 1980. In the late 1980s, there was another burst of activity when spinel was a candidate for the Stinger Missile. By 1990, Raytheon had dropped spinel and the material was spun off by Coors Ceramics to Alpha Optical Systems, whose technical effort was led by Don Roy. With low commercial sales potential for spinel, Alpha was dissolved in 1993. RCS Technologies took over a Government contract seeking 200-mm spinel domes for the Harrier aircraft, but this effort ended in 1996 and RCS was dissolved. In 1998, the Army enlisted TA&T to make spinel for transparent armor. Other potential applications appeared and TA&T received numerous Government development contracts. Demand for the still-unavailable spinel drew Surmet to begin development in 2002. In early 2005, spinel is under active development at TA&T and Surmet.

  19. Elastic stability of high dose neutron irradiated spinel

    SciTech Connect

    Li, Z.; Chan, S.K.; Garner, F.A.

    1995-04-01

    The objective of this effort is to identify ceramic materials that are suitable for fusion reactor applications. Elastic constants (C{sub 11}, C{sub 12}, and C{sub 44}) of spinel (MgAl{sub 2}O{sub 4}) single crystals irradiated to very high neutron fluences have geen measured by an ultrasonic technique. Although results of a neutron diffraction study show that cation occupation sites are significantly changed in the irradiated samples, no measurable differences occurred in their elastic properties. In order to understand such behavior, the elastic properties of a variety of materials with either normal or inverse spinel structures were studied. The cation valence and cation distribution appear to have little influence on the elastic properties of spinel materials.

  20. On the Compressive and Tensile Strength of Magnesium Aluminate Spinel

    NASA Astrophysics Data System (ADS)

    Paris, V.; Hayun, S.; Dariel, M. P.; Frage, N.; Zaretsky, E.

    2009-12-01

    Magnesium aluminate spinel is a strong polycrystalline transparent ceramic. Spinel is an attractive material for armor applications and its behavior under shock wave loading is of obvious interest. The purpose of the present study was to determine the Hugoniot elastic limit (HEL) of this material, its Hugoniot response above the HEL, and its spall strength. Planar impact experiments were performed over the 2 to 40 GPa stress range using the Velocity Interferometer System for Any Reflector (VISAR) as a principal diagnostics tool. According to these tests, spinel has a HEL of about 11.3 GPa. The spall strength of the material was found to be close to zero at low, about 2 GPa, impact stress.

  1. Cathodic arcs

    SciTech Connect

    Anders, Andre

    2003-10-29

    Cathodic arc plasma deposition has become the technology of choice for hard, wear and corrosion resistant coatings for a variety of applications. The history, basic physics of cathodic arc operation, the infamous macroparticle problem and common filter solutions, and emerging high-tech applications are briefly reviewed. Cathodic arc plasmas standout due to their high degree of ionization, with important consequences for film nucleation, growth, and efficient utilization of substrate bias. Industrial processes often use cathodic arc plasma in reactive mode. In contrast, the science of arcs has focused on the case of vacuum arcs. Future research directions include closing the knowledge gap for reactive mode, large area coating, linear sources and filters, metal plasma immersion process, with application in high-tech and biomedical fields.

  2. Soft-combustion synthesis of a new cathode-active material, LiVWO 6, for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Prabaharan, S. R. S.; Yong, Tou T.; Fauzi, Ahmad; Michael, M. S.

    Brannerite-LiVWO 6, has been synthesized by employing a wet-chemical soft-combustion (low temperature) technique and its battery-active character as candidate cathode material in lithium-containing batteries is reported in the light of electrochemical means. Structural and thermal properties have also been studied by means of classical techniques such as XRD and thermal analysis. The structural features are found to be similar to its analogous counterpart, brannerite-LiVMoO 6 previously reported. Quasi-layered type LiVWO 6 crystallizes in brannerite structure of AB 2O 6 type, having a general formula LiM 2'O 6 (M'=transition metal) with lattice parameters a=9.347 Å, b=3.670 Å, c=6.593 Å and β=111°50'. The thermochemical reactions that occur during the soft-combustion of the precursor mass facilitate the formation of the above compound at 434°C as deduced from TG-DTA scan. The product (LiVWO 6) thus prepared (calcined at 700°C) exhibits the submicrometer grains (<1 μm) whose specific surface area is found to be 4.97 m 2/g as deduced from BET analysis. The redox behavior of the above compound has been examined for LiVWO 6/Li +/Li under the wet electrolyte (1 M LiPF 6: EC+DMC) environment in the voltage regime 4.0 and 1.5 V using constant current technique at a current density of 0.8 mA/cm 2. It has been found that the test cell containing LiVWO 6/Li couple demonstrates excellent charge-discharge behavior in the voltage regime 3.0-1.5 V and the specific capacity of ˜240 mAh/g has been deduced from the first charge-discharge cycle in the voltage regime ˜4.0-1.5 V.

  3. Spinel NiCo2O4 for use as a high-performance supercapacitor electrode material: Understanding of its electrochemical properties

    NASA Astrophysics Data System (ADS)

    Zhu, Yirong; Ji, Xiaobo; Wu, Zhengping; Song, Weixin; Hou, Hongshuai; Wu, Zhibin; He, Xiao; Chen, Qiyuan; Banks, Craig E.

    2014-12-01

    In this work, spinel NiCo2O4 is prepared by a facile sol-gel method with the effect of three different chelating agents including citric acid (CA), oxalic acid (OA) and ethylenediamine tetraacetic acid (EDTA) explored upon the fabrication methodology and resulting electrochemical and supercapacitor properties. The electrochemical measurements reveal that NiCo2O4 prepared using OA exhibits ultrahigh specific capacitance of 1254 F g-1 at 2 A g-1 due to the resultant high specific surface area, while NiCo2O4 prepared by EDTA exhibits the best rate capability and cycling stability owing to the subsequent large pore size. The obvious differences can be primarily ascribed to the use of the differing chelating agents which are shown, for the first time, to greatly affect the particle size, pore structure and specific surface area of the fabricated NiCo2O4. Such work is of fundamental importance and demonstrates that the tailoring of these different properties can be readily obtained through the use of differing chelating and is responsible for the observed differing electrochemical properties. Additionally, first-principles calculations were employed to investigate the electronic structure of NiCo2O4, which can help to further understand its excellent electrochemical behaviors. These results above provide a facile, cost-effective and high-performance strategy for supercapacitor electrode applications.

  4. REACTIVE FORCE FIELDS FOR Y-DOPED BaZrO3 ELECTROLYTE AND NI-ANODE. POTENTIAL CATHODE MATERIALS FOR APPLICATION IN PROTON CERAMIC FUEL CELLS

    SciTech Connect

    Boris Merinov; Adri van Duin; Sossina Haile; William A. Goddard III

    2004-10-30

    Based on quantum mechanical data obtained for the Y-doped BaZrO{sub 3} electrolyte and Ni-anode Reactive Force Field parameters have been developed for further molecular dynamics simulations of the proton diffusion and electrode/electrolyte interfaces. Electronic and atomic structures of different terminations of the (001) BaZrO{sub 3} surface have been studied using first-principles calculations. Several potential cathode materials for the Y-doped BaZrO{sub 3} system were synthesized via glycine nitrate combustion method. Of the five potential cathode materials examined BaZr{sub 0.40}Pr{sub 0.40}Gd{sub 0.20}O{sub 3} and BaZr{sub 0.60}Y{sub 0.20}Co{sub 0.20}O{sub 3} appear to be the most promising for further applications in proton ceramic fuel cells. Fuel cell test of a Y-doped BaZrO{sub 3} thin film using platinum ink for both electrodes have been performed. The obtained results shows that a robust method for fabricating crack-free thin membranes, as well as methods for sealing anode and cathode chambers, have successfully been developed.

  5. Cathode for aluminum producing electrolytic cell

    DOEpatents

    Brown, Craig W.

    2004-04-13

    A method of producing aluminum in an electrolytic cell comprising the steps of providing an anode in a cell, preferably a non-reactive anode, and also providing a cathode in the cell, the cathode comprised of a base material having low electrical conductivity reactive with molten aluminum to provide a highly electrically conductive layer on the base material. Electric current is passed from the anode to the cathode and alumina is reduced and aluminum is deposited at the cathode. The cathode base material is selected from boron carbide, and zirconium oxide.

  6. Lithiated Vanadium Oxide (LVO), gamma-lithium vanadium bronze (Gamma-LIV2O5) and vanadium dioxide (VO2) as thermal battery cathode materials

    NASA Astrophysics Data System (ADS)

    Richie, A. G.; Warner, K.

    1991-05-01

    Thermal batteries are high temperature reserve batteries, predominantly used in missiles. Modern designs use a lithium (or lithium alloy) anode, an immobilized molten salt electrolyte, and an iron-disulphide cathode. These batteries have many advantages: high reliability, long storage life without maintenance, wide temperature range of operation, and, sometimes, high power. However, the energy density is rather low and this could be improved if the individual cell voltage could be raised above the present 2.2 V/cell open circuit-voltage for the lithium iron-disulphide couple. A new cathode material, lithiated vanadium oxide (LVO), was invented at RAE and has the advantage of a much higher open-circuit voltage of 2.6 V/cell versus lithium. The properties of LVO have been investigated and it has been shown that LVO consists of vanadium dioxide as the major component. Some lithium bromide is also present.

  7. Core-shell nano-FeS2@N-doped graphene as an advanced cathode material for rechargeable Li-ion batteries.

    PubMed

    Tan, Rui; Yang, Jinlong; Hu, Jiangtao; Wang, Kai; Zhao, Yan; Pan, Feng

    2016-01-18

    We report the formation of core-shell nano-FeS2@N-doped graphene as a novel cathode material and its mechanism for use in rechargeable Li-ion batteries. A benefit of the amount of FeS2 nano-crystals as the core for Li-ion storage with high capacity and using coated N-doped graphene as the shell is that FeS2@N-graphene exhibits a remarkable specific energy (950 W h kg(-1) at 0.15 kW g(-1)) and higher specific power (543 W h kg(-1) at 2.79 kW g(-1)) than commercial rechargeable LIB cathodes, as well as stable cycling performance (∼600 W h kg(-1) at 0.75 kW g(-1) after 400 cycles). PMID:26592428

  8. The Role of Spinel Minerals in Lunar Magma Evolution

    NASA Astrophysics Data System (ADS)

    Taylor, L. A.; Head, J. W.; Pieters, C. M.; Sunshine, J. M.; Staid, M.; Isaacson, P.; Petro, N. E.

    2009-12-01

    crystal settling in an anorthositic magma chamber, much like in anorthositic layered intrusives on Earth. On the Moon, this would be a cumulate spinel anorthosite, never before seen in remote sensing or in the lunar sample collection. Virtually all types of mare basalt melts have chromite at or near the liquidus, closely associated with olivine or low-Ca pyroxene. During crystallization, the chromite becomes more Ti-rich, typically with nearly continuous solid-solution zonation outward to ulvöspinel. Pyroclastic orange/black glass on the Moon typically contains dendritic crystallites of ilmenite and olivine, a product of the rich-TiO2 content of the fire-fountain melt. However, other pyroclastic melt compositions, with high-Cr and low-Ti contents, have chromite on the liquidus, which could result in dendrites of chromite and olivine in the volcanic glass. Here again, M3 is seeing spinel-dominated materials, this time in close association with pyroclastic deposits.

  9. Nanotube cathodes.

    SciTech Connect

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-11-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  10. Pyrite (FeS2) nanocrystals as inexpensive high-performance lithium-ion cathode and sodium-ion anode materials.

    PubMed

    Walter, Marc; Zünd, Tanja; Kovalenko, Maksym V

    2015-05-28

    In light of the impeding depletion of fossil fuels and necessity to lower carbon dioxide emissions, economically viable high-performance batteries are urgently needed for numerous applications ranging from electric cars to stationary large-scale electricity storage. Due to its low raw material cost, non-toxicity and potentially high charge-storage capacity pyrite (FeS2) is a highly promising material for such next-generation batteries. In this work we present the electrochemical performance of FeS2 nanocrystals (NCs) as lithium-ion and sodium-ion storage materials. First, we show that nanoscopic FeS2 is a promising lithium-ion cathode material, delivering a capacity of 715 mA h g(-1) and average energy density of 1237 Wh kg(-1) for 100 cycles, twice higher than for commonly used LiCoO2 cathodes. Then we demonstrate, for the first time, that FeS2 NCs can serve as highly reversible sodium-ion anode material with long cycling life. As sodium-ion anode material, FeS2 NCs provide capacities above 500 mA h g(-1) for 400 cycles at a current rate of 1000 mA g(-1). In all our tests and control experiments, the performance of chemically synthesized nanoscale FeS2 clearly surpasses bulk FeS2 as well as large number of other nanostructured metal sulfides. PMID:25941034

  11. Development of a Fundamental Understanding of Chemical Bonding and Electronic Structure in Spinel Compounds

    SciTech Connect

    Sickafus, K.E.; Wills, J.M.; Chen, S.-P.; Terry, J.H., Jr.; Hartmann, T.; Sheldon, R.I.

    1999-05-14

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos national Laboratory (LANL). Hundreds of ceramic compounds possess the spinel crystal structure and exhibit a remarkable variety of properties, ranging from compounds that are electrical insulators to compounds that are superconducting, or from compounds with ferri- and antiferromagnetic behavior to materials with colossal magnetoresistive characteristics. The unique crystal structure of spinel compounds is in many ways responsible for the widely varying physical properties of spinels. The objective of this project is to investigate the nature of chemical bonding, point defects, and electronic structure in compounds with the spinel crystal structure. Our goal is to understand and predict the stability of the spinel structure as a function of chemical composition, stoichiometry, and cation disorder. The consequences of cation disorder in spinel materials can be profound . The ferromagnetic characteristics of magnesioferrite, for instance, are entirely attributable to disorder on the cation sublattices. Our studies provide insight into the mechanisms of point defect formation and cation disorder and their effects on the electronic band structure and crystal structure of spinel-structure materials. our ultimate objective is to develop a more substantive knowledge of the spinel crystal structure and to promote new and novel uses for spinel compounds. The technical approach to achieve our goals is to combine first-principles calculations with experimental measurements. The structural and electronic properties of spinel samples were experimentally determined primarily with X-ray and neutron scattering, optical and X-ray absorption, and electron energy-loss spectroscopy. Total energy electronic structure calculations were performed to determine structural stability, band structure, density of states, and electron distribution. We also used shell

  12. Development of a Fundamental Understanding of Chemical Bonding and Electronic Structure in Spinel Compounds

    SciTech Connect

    Sickafus, K.E.; Wills, J.M.; Chen, S.-P.; Terry, J.H., Jr.; Hartmann, T.; Sheldon, R.I.

    1999-06-03

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Hundreds of ceramic compounds possess the spinel crystal structure and exhibit a remarkable variety of properties, ranging from compounds that are electrical insulators to compounds that are superconducting, or from compounds with ferri- and antiferromagnetic behavior to materials with colossal magnetoresistive characteristics. The unique crystal structure of spinel compounds is in many ways responsible for the widely varying physical properties of spinels. The objective of this project is to investigate the nature of chemical bonding, point defects, and electronic structure in compounds with the spinel crystal structure. Our goal is to understand and predict the stability of the spinel structure as a function of chemical composition, stoichiometry, and cation disorder. The consequences of cation disorder in spinel materials can be profound . The ferromagnetic characteristics of magnesioferrite, for instance, are entirely attributable to disorder on the cation sublattices. Our studies provide insight into the mechanisms of point defect formation and cation disorder and their effects on the electronic band structure and crystal structure of spinel-structure materials. Our ultimate objective is to develop a more substantive knowledge of the spinel crystal structure and to promote new and novel uses for spinel compounds. The technical approach to achieve our goals is to combine first-principles calculations with experimental measurements. The structural and electronic properties of spinel samples were experimentally determined primarily with X-ray and neutron scattering, optical and X-ray absorption, and electron energy-loss spectroscopy. Total energy electronic structure calculations were performed to determine structural stability, band structure, density of states, and electron distribution. We also used shell

  13. High energy cathode material

    SciTech Connect

    Li, Bin; Caldwell, Marissa; Tong, Wei; Kaye, Steven; Bhat, Vinay

    2015-09-01

    A composition for use in a battery electrode comprising a compound including lithium, manganese, nickel, and oxygen. The composition is characterized by a powder X-ray diffraction pattern having peaks including 18.6.+-.0.2, 35.0.+-.0.2, 36.4.+-.0.2, 37.7.+-.0.2, 42.1.+-.0.2, and 44.5.+-.0.2 degrees 2.theta. as measured using Cu K.sub..alpha. radiation.

  14. LaCoO3: Promising cathode material for protonic ceramic fuel cells based on a BaCe0.2Zr0.7Y0.1O3-δ electrolyte

    NASA Astrophysics Data System (ADS)

    Ricote, Sandrine; Bonanos, Nikolaos; Lenrick, Filip; Wallenberg, Reine

    2012-11-01

    Symmetric cells (cathode/electrolyte/cathode) were prepared using BaCe0.2Zr0.7Y0.1O3-δ (BCZY27) as proton conducting electrolyte and LaCoO3 (LC) infiltrated into a porous BCZY27 backbone as cathode. Single phased LC was formed after annealing in air at 600 °C for 2 h. Scanning electron micrographs showed the presence of the infiltrated LC in the full cathode depth. Transmission electron micrographs revealed LC grains (60-80 nm) covering partly the BCZY27 grains (200 nm-1 μm). Impedance spectra were recorded at 500 °C and 600 °C, varying the oxygen partial pressure and the water vapour pressure. Two arcs correspond to the cathode contribution: a middle range frequency one (charge transfer) and a low frequency one (oxygen dissociation/adsorption). The area specific resistances (ASRs) of both contributions increase when decreasing the oxygen partial pressure. The low frequency arc is independent on the water vapour pressure while the charge transfer ASR values increase with higher pH2O. The cathode ASRs of 0.39 and 0.11 Ω cm2 at 500 and 600 °C respectively, in air (pH2O = 0.01 atm) are the lowest reported to the authors' knowledge for PCFC cathodes. Furthermore, this work shows that the presence of oxide ion conduction in the cathode material is not necessary for good performance.

  15. A Study of the Thermodynamics and Kinetics of Lithium Iron Phosphate as a Cathode Material for Lithium Batteries

    NASA Astrophysics Data System (ADS)

    Tan, Hongjin

    Olivine-type LiFePO4 has been recognized as one of the most promising cathode materials for rechargeable Li batteries. Its advantages include high capacity, high stability, nontoxicity, and low cost. Our methods for synthesizing nanocrystalline LixFePO 4 with the olivine structure are described. Solid-state reactions and precipitation reactions were both successful, and ball milling was especially effective at reducing crystallite sizes. Diffractometry and microscopy were used to characterize these materials, and results of impurity phases, excess Fe3+, and internal stresses are reported for the different types of synthesis. Applications of lithium-ion batteries, including automotive applications, require fast kinetics and high conductivity of ions and electrons. Unfortunately, LixFePO4 has the electronic structure of an insulator, an entirely unsatisfactory situation if it is to be used as a battery electrode. Electrical conductivity in LixFePO 4 occurs by the motion of small polarons, which are valence electrons at Fe atoms plus their distorted local environments. Electrical conductivity of LixFePO4 is interpreted in terms of small polaron hopping. There are other factors of importance in these measurements, such as impurities or defects that block the one-dimensional conduction channels of the olivine structure of LixFePO4. We studied the polaron hopping directly, which allows us to understand the intrinsic electrical conductivity, and how it depends on microstructure and composition of LixFePO4. The experimental technique was Mossbauer spectrometry, which has been used for many years as a means for determining the fractions of Fe2+ and Fe 3+ in a material. Usually the spectral signatures of Fe2+ and Fe3+ are distinct. When valence electrons hop between Fe 2+ and Fe3+ at a frequency of 108 Hz or higher, however, the valence changes during the timescale of the Mossbauer measurement and the spectrum is blurred. By measuring Mossbauer spectra at elevated

  16. In Situ XAS and XRD Studies of Substituted Spinel Lithium Manganese Oxides in the 4-5 V Region

    SciTech Connect

    McBreen, J.; Mukerjee, S.; Yang, X. Q.; Sun, X.; Ein-Eli, Y.

    1998-11-01

    Partial substitution of Mn in lithium manganese oxide spinel materials by Cu and Ni greatly affects the electrochemistry and the phase behavior of the cathode. Substitution with either metal or with a combination of both shortens the 4.2 V plateau and results in higher voltage plateaus. In situ x-ray absorption (XAS) studies indicate that the higher voltage plateaus are related to redox processes on the substituents. In situ x-ray diffraction (XRD) on LiCu{sub 0.5}Mn{sub 1.5}O{sub 4} shows single phase behavior during the charge and discharge process. Three phases are observed for LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} and two phases are observed in the case of LiNi{sub 0.25}Cu{sub 0.25}Mn{sub 1.5}O{sub 4}. The electrolyte stability is dependent on both the operating voltage and the cathode composition. Even though Ni substituted materials have lower voltages, the electrolyte is more stable in cells with the Cu substituted materials.

  17. Effect of MWCNT on prepared cathode material (Li2Mn(x)Fe(1-x)SiO4) for energy storage applications

    NASA Astrophysics Data System (ADS)

    Agnihotri, Shruti; Rattan, Sangeeta; Sharma, A. L.

    2016-05-01

    The electrode material Li2MnFeSiO4 was successfully synthesized by standard sol-gel method and further modified with multiwalled carbon nano tube (MWCNT) to achieve better electrochemical properties. Our strategy helps us to improve the performance and storage capacity as compared with the bared material. This novel composite structure constructs an efficient cation (Li+) and electron channel which significantly enhance the Li+ ion diffusion coefficient and reduced charge transfer resistance. Hence leads to high conductivity and specific capacity. Characterization technique like Field emission scanning electron microscopy (FESEM) has been used to confirm its morphology, structure and particle size which comes out to be of the order of ˜20 to 30 nm. Lesser particle size reveals better electrochemical properties. Electrical conductivity (˜10-5 Scm-1) of MWCNT doped oxide cathode materials was recorded using ac impedance spectroscopy technique which reflects tenfold increment when compared with pure oxide cathode materials. Cyclic voltametery analysis has been done to calculate specific capacity and potential window of materials with and without CNTs. The results obtained from different techniques are well correlated and suitable for energy storage applications.

  18. The Na2FeP2O7-carbon nanotubes composite as high rate cathode material for sodium ion batteries

    NASA Astrophysics Data System (ADS)

    Longoni, Gianluca; Wang, Ji Eun; Jung, Young Hwa; Kim, Do Kyung; Mari, Claudio M.; Ruffo, Riccardo

    2016-01-01

    Among the viable positive electrode materials recently proposed for Na-ion secondary batteries, Na2FeP2O7 was investigated thanks to its facile preparation, the use of highly abundant and low cost raw materials, and the highest thermal stability among all others cathode materials. In the present work the electrochemical features of the Na2FeP2O7 are improved by synthesizing a Na2FeP2O7-carbon nanotubes composite with prominent high-rate performances. The material shows a reversible specific capacity of 86 mAh g-1 for 140 cycles at 1C and 68 mAh g-1 at 10C. An in depth investigation about the Na+ diffusion rates inside the material was conducted by electrochemical impedance spectroscopy.

  19. Electrochemical properties of graphene flakes as an air cathode material for Li-O2 batteries in an ether-based electrolyte.

    PubMed

    Kim, Se Young; Lee, Ho-Taek; Kim, Kwang-Bum

    2013-12-14

    We employed graphene flakes as an air-cathode material for Li-O2 batteries and investigated their electrochemical properties in the dimethyl ether electrolyte. Graphene flakes were prepared by microwave-assisted reduction of graphene oxide, and their electrochemical properties were compared with those of Ketjen Black and carbon nanotubes. The catalytic effect of the prepared graphene flake-air cathode was demonstrated using cyclic voltammetry and discharge-charge testing performed under a limited discharge capacity. The catalytic effect of graphene flakes was also supported by morphological and spectroscopic analysis of the discharge-charge products formed on the graphene surface. Scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy revealed that Li2O2, Li2O, and Li2CO3 were the main discharge products on all carbon-air cathode surfaces. Raman spectroscopy revealed that LiRCO3 was additionally formed on Ketjen Black and carbon nanotubes during the first discharge; however, its formation was not observed on the graphene flakes. The catalytic effect of the graphene flakes and the absence of LiRCO3 in the discharge product could explain the higher Coulombic efficiency in the discharge-charge tests. PMID:24166701

  20. Optical properties of laser spinel

    NASA Astrophysics Data System (ADS)

    Mironova-Ulmane, Nina; Skvortsova, Vera; Smirnovs, Andrejs; Riekstinya, Daina; Litvinov, L.; Sildos, Ilmo; Osvet, Andris

    1997-02-01

    The present work summarizes the results of absorption and luminescence spectra investigation of natural and synthetic magnesium aluminum spinels (MgO*nAl2O3) containing chromium and manganese ions. The spectra have been analyzed with an aim to determine the effect of stoichiometry 'n' on distribution of emitting ions. The Mn2+ is observed in both tetrahedral and octahedral coordinations providing green or orange emission. Absorption bands have been explained in terms of the Mn2+ configuration model. Laser excitation of chromium-comprising magnesium aluminum spinel crystals has been carried out at 7 K with the purpose to detect the nearest neighbors of Cr3+ ions. Luminescence emission spectra have been obtained for natural sample and three synthetic samples (MgO*nAl2O3, n equals 1, 2, 2.8). Decay time has been measured at different wavelengths and compared for crystals of different stoichiometry. In case n equals 2 or 2.8, computer simulation has been used to decompose smeared luminescence spectra in the 680 - 700 nm region. Gaussian curves corresponding to R- and N-lines of natural spinel spectrum have been applied as components in the calculations of nonstoichiometric spinel spectra. This suggests that there aren't normally arranged Cr-occupied octahedral positions in nonstoichiometric spinel (n equals 2.8, e.g.).

  1. Preparation and electrochemical performance of Pr2Ni0.6Cu0.4O4 cathode materials for intermediate-temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Yifang; Cheng, Jigui; Jiang, Qiumei; Yang, Junfang; Gao, Jianfeng

    2011-03-01

    Cathode material Pr2Ni0.6Cu0.4O4 (PNCO) for intermediate-temperature solid oxide fuel cells (IT-SOFCs) is synthesized by a glycine-nitrate process using Pr6O11, NiO, and CuO powders as raw materials. X-ray diffraction analysis reveals that nanosized Pr2Ni0.6Cu0.4O4 powders with K2NiF4-type structure can be obtained from calcining the precursors at 1000 °C for 3 h. Scanning electron microscopy shows that the sintered PNCO samples have porous microstructure with a porosity of more than 30% and grain size smaller than 2 μm. A maximum conductivity of 130 S cm-1 is obtained from the PNCO samples sintered at 1050 °C. A single fuel cell based on the PNCO cathode with 30 μm Sm0.2Ce0.8O1.9 (SCO) electrolyte film and a 1 mm NiO-SCO anode support is constructed. The ohmic resistance of the single Ni-SCO/SCO/PNCO cell is 0.08 Ω cm2 and the area specific resistance (ASR) value is 0.19 Ω cm2 at 800 °C. Cell performance was also tested using humidified hydrogen (3% H2O) as fuel and air as oxidant. The single cell shows an open circuit voltage of 0.82 V and 0.75 V at 700 °C and 800 °C, respectively. Maximum power density is 238 mW cm-2 and 308 mW cm-2 at 700 °C and 800 °C, respectively. The preliminary tests have shown that Pr2Ni1-xCuxO4materials can be a good candidate for cathode materials of IT-SOFCs.

  2. Filtered cathodic arc source

    DOEpatents

    Falabella, Steven; Sanders, David M.

    1994-01-01

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45.degree. to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles.

  3. Filtered cathodic arc source

    DOEpatents

    Falabella, S.; Sanders, D.M.

    1994-01-18

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge is described. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45[degree] to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles. 3 figures.

  4. Filtered cathodic arc source

    SciTech Connect

    Falabella, S.; Sanders, D.M.

    1992-12-31

    Disclosed is a continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45{degrees} to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles.

  5. Orbital Superstructures in Spinels

    NASA Astrophysics Data System (ADS)

    Khomskii, Daniel

    2006-03-01

    Orbital degrees of freedom often lead to specific types of orbital and spin ordering. Complicated and interesting superstructures are observed in B-sublattice of spinels. This is connected with the geometric frustration of this lattice and with the interconnection of edge-sharing MO6 octahedra, which is especially important for transition metals with partially-filled t2g levels. In some such systems (MgTi2O4, CuIr2S4, AlV2O4) there appears strange superstructures with the formation of spin gap states. In other cases (ZnV2O4) structural transitions, apparently connected with orbital ordering, are followed by long-range magnetic ordering. Last but not least, the famous Verwey transition in magnetite Fe3O4 leads to a very complicated structural pattern, accompanied by the appearance of ferroelectricity. In this talk I will discuss all these examples, paying main attention to an interplay of charge, spin and orbital degrees of freedom. In particular, for MgTi2O4, and CuIr2S4 we proposed the picture of orbitally-driven Peierls state [1]. Similar phenomenon can also explain situation in ZnV2O4 [2], although the corresponding superstructure has not yet been observed experimentally. Finally, I propose the model of charge and orbital ordering in magnetite [3], which uses the idea of an interplay of site- and bond-centered ordering [4] and which seems to explain both the structural data and the presence of ferroelectricity in Fe3O4 below Verwey transition. [1] D.I.Khomskii and T.Mizokawa, Phys.Rev.Lett. 94, 156402 (2005); [2] Hua Wu, T.Mizokawa and D.I.Khomskii, unpublished; [3] D.I.Khomskii, unpublished; [4] D.V.Efremov, J.van den Brink and D.I.Khomskii, Nature Mater. 3, 853 (2004)

  6. Nanoscale Morphological and Chemical Changes of High Voltage Lithium–Manganese Rich NMC Composite Cathodes with Cycling

    PubMed Central

    2015-01-01

    Understanding the evolution of chemical composition and morphology of battery materials during electrochemical cycling is fundamental to extending battery cycle life and ensuring safety. This is particularly true for the much debated high energy density (high voltage) lithium–manganese rich cathode material of composition Li1 + xM1 – xO2 (M = Mn, Co, Ni). In this study we combine full-field transmission X-ray microscopy (TXM) with X-ray absorption near edge structure (XANES) to spatially resolve changes in chemical phase, oxidation state, and morphology within a high voltage cathode having nominal composition Li1.2Mn0.525Ni0.175Co0.1O2. Nanoscale microscopy with chemical/elemental sensitivity provides direct quantitative visualization of the cathode, and insights into failure. Single-pixel (∼30 nm) TXM XANES revealed changes in Mn chemistry with cycling, possibly to a spinel conformation and likely including some Mn(II), starting at the particle surface and proceeding inward. Morphological analysis of the particles revealed, with high resolution and statistical sampling, that the majority of particles adopted nonspherical shapes after 200 cycles. Multiple-energy tomography showed a more homogeneous association of transition metals in the pristine particle, which segregate significantly with cycling. Depletion of transition metals at the cathode surface occurs after just one cycle, likely driven by electrochemical reactions at the surface. PMID:25054780

  7. Nanoscale morphological and chemical changes of high voltage lithium-manganese rich NMC composite cathodes with cycling.

    PubMed

    Yang, Feifei; Liu, Yijin; Martha, Surendra K; Wu, Ziyu; Andrews, Joy C; Ice, Gene E; Pianetta, Piero; Nanda, Jagjit

    2014-08-13

    Understanding the evolution of chemical composition and morphology of battery materials during electrochemical cycling is fundamental to extending battery cycle life and ensuring safety. This is particularly true for the much debated high energy density (high voltage) lithium-manganese rich cathode material of composition Li(1 + x)M(1 - x)O2 (M = Mn, Co, Ni). In this study we combine full-field transmission X-ray microscopy (TXM) with X-ray absorption near edge structure (XANES) to spatially resolve changes in chemical phase, oxidation state, and morphology within a high voltage cathode having nominal composition Li1.2Mn0.525Ni0.175Co0.1O2. Nanoscale microscopy with chemical/elemental sensitivity provides direct quantitative visualization of the cathode, and insights into failure. Single-pixel (∼ 30 nm) TXM XANES revealed changes in Mn chemistry with cycling, possibly to a spinel conformation and likely including some Mn(II), starting at the particle surface and proceeding inward. Morphological analysis of the particles revealed, with high resolution and statistical sampling, that the majority of particles adopted nonspherical shapes after 200 cycles. Multiple-energy tomography showed a more homogeneous association of transition metals in the pristine particle, which segregate significantly with cycling. Depletion of transition metals at the cathode surface occurs after just one cycle, likely driven by electrochemical reactions at the surface. PMID:25054780

  8. Nanowire Na0.35MnO2 from a hydrothermal method as a cathode material for aqueous asymmetric supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhang, B. H.; Liu, Y.; Chang, Z.; Yang, Y. Q.; Wen, Z. B.; Wu, Y. P.; Holze, R.

    2014-05-01

    Nanowire Na0.35MnO2 was prepared by a simple and low energy consumption hydrothermal method; its electrochemical performance as a cathode material for aqueous asymmetric supercapacitors in Na2SO4 solution was investigated. Due to the nanowire structure its capacitance (157 F g-1) is much higher than that of the rod-like Na0.95MnO2 (92 F g-1) from solid phase reaction although its sodium content is lower. When it is assembled into an asymmetric aqueous supercapacitor using activated carbon as the counter electrode and aqueous 0.5 mol L-1 Na2SO4 electrolyte solution, the nanowire Na0.35MnO2 shows an energy density of 42.6 Wh kg-1 at a power density of 129.8 W kg-1 based on the total weight of the two electrode material, higher than those for the rod-like Na0.95MnO2, with an energy density of 27.3 Wh kg-1 at a power density of 74.8 W kg-1, and that of LiMn2O4. The new material presents excellent cycling behavior even when dissolved oxygen is not removed from the electrolyte solution. The results hold great promise for practical applications of this cathode material since sodium is much cheaper than lithium and its natural resources are rich.

  9. Sepiolite-sulfur as a high-capacity, high-rate performance, and low-cost cathode material for lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Pan, Junan; Wu, Cheng; Cheng, Juanjuan; Pan, Yong; Ma, Zengsheng; Xie, Shuhong; Li, Jiangyu

    2015-10-01

    Lithium-sulfur batteries have the theoretical energy density of up to 2600 Wh/kg, though its commercialization is limited by high material cost and poor cyclic performance. In this work, we show that sepiolite-sulfur is a high-capacity, high-rate performance, and low-cost cathode material for lithium-sulfur batteries. Sepiolite is a porous mineral with specific structure, outstanding physical and chemical adsorption characteristics, and excellent ion exchange capability, making it an ideal matrix material for lithium-sulfur batteries. It is shown that the first specific discharge capacity of sepiolite-sulfur cathode is about 1436 mAh g-1 at 0.2 C current rate, and it remains as high as 901 mAh g-1 after 300 cycles. Under 1 C current density, the first discharge capacity is 1206 mAh g-1, and maintains a high value of 601 mAh g-1 after 500 cycles. The raw materials are abundant and low cost, and the manufacturing process is simple and scalable, making it promising for the commercialization of lithium-sulfur batteries.

  10. Improved electrochemical properties of surface-coated Li(Ni,Co,Mn)0{sub 2} cathode material for Li secondary batteries.

    SciTech Connect

    Kang, S.-H.; Amine, K.; Chemical Engineering

    2006-01-01

    The surface of Li(Ni{sub 0.4}Co{sub 0.2}Mn{sub 0.4})O{sub 2} was coated with amorphous aluminum oxide using Al-isopropoxide. The effect of the surface coating on the cycling performance and high-temperature storage characteristics was investigated using coin-type cells. The surface-coated materials showed superior capacity retention at 55C as well as at room temperature and limited impedance rise during high-temperature storage compared with the uncoated material. From the a.c. impedance measurement, it was found that the uncoated material exhibited very large increase in the cathode/electrolyte interfacial impedance during cycling whereas the surface-coated materials showed a limited increase in the interfacial impedance.

  11. Bismuth and niobium co-doped barium cobalt oxide as a promising cathode material for intermediate temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    He, Shaofei; Le, Shiru; Guan, Lili; Liu, Tao; Sun, Kening

    2015-11-01

    Perovskite oxides BaBi0.05Co0.95-yNbyO3-δ (BBCNy, 0 ≤ y ≤ 0.2) are synthesized and evaluated as potential cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). Highly charged Nb5+ successfully stabilizes the cubic perovskite structure to room temperature with Nb substituting content y ≥ 0.1. The phase structure, thermal expansion behavior, electrical conductivity and electrochemical performance of BBCNy with cubic phase are systematically studied. The samples exhibit excellent chemical compatibility with GDC and have sufficiently high electrical conductivities. However, the thermal expansion coefficients of BBCNy samples are nearly twice those of the most commonly used electrolyte materials YSZ and GDC, which is a major drawback for application in IT-SOFCs. The polarization resistances of BBCNy with y = 0.10, 0.15 and 0.20 on GDC electrolyte are 0.086, 0.079 and 0.107 Ω cm2 at 700 °C, respectively. Even though the YSZ electrolyte membrane and GDC barrier layer are approximately 50 μm and 10 μm in thickness, the highest maximum power density (1.23 W cm-2) of the single cell Ni-YSZ|YSZ|GDC|BBCN0.15 is obtained at 750 °C. Good long-term stability of the single cell with BBCN0.15 cathode is also demonstrated. These results demonstrate that BBCNy perovskite oxides with cubic structure are very promising cathode materials for IT-SOFCs.

  12. Sulfur/Co3O4 nanotube composite with high performances as cathode materials for lithium sulfur batteries

    NASA Astrophysics Data System (ADS)

    Cheng, Hong; Wang, Shengping; Tao, Du; Wang, Man

    2014-02-01

    To improve the overall electrochemical performance of the sulfur cathode in Li/S batteries, a hollow Co3O4 nanotube with a channel measuring approximately 12.5 nm in diameter is synthesized and then impregnated with sulfur via a melt-diffusion strategy. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis and thermogravimetric analysis indicate that sulfur impregnated the channels of the hollow Co3O4 nanotube. Because the sulfur is mostly restricted to the Co3O4 nanotubes, a sulfur/Co3O4 cathode with 10 wt.% sulfur loading delivers an initial discharge capacity of 963.4 mAh g-1, with much of the capacity contributed by Co3O4, and exhibits excellent reversibility with a capacity reservation of 80.8% after 100 cycles.

  13. Water based processing of LiFePO4/C cathode material for Li-ion batteries utilizing freeze granulation

    NASA Astrophysics Data System (ADS)

    Orlenius, J.; Lyckfeldt, O.; Kasvayee, K. A.; Johander, P.

    2012-09-01

    A water based solid state synthesis of LiFePO4 has been conducted by utilizing freeze granulation. Various processing conditions were tested and achieved powder properties were characterized by density, XRD, specific surface area, carbon content, conductivity and SEM. Freeze granulation, a novel method for precursor preparation was shown to be an effective method to provide high degree of homogeneity prior to calcination and high ultimate yield of pure LiFePO4. Cathodes were manufactured by water based as well as NMP system based tape casting. A commercial LiFePO4/C powder was also characterized and used to manufacture cathodes as comparison in this study. Charge cycling tests showed promising results with high capacity and long term stability, well in the range of what the commercial powder provided. Post-milling of calcined powder prior to paste preparation for tape casting tended, however, to retard the capacity owing to disturbed carbon distribution and loss of conductivity of the LiFePO4/C. In comparison with the solvent system for cathode manufacturing, the water based system gave similar cell performance, illustrating the possibility to apply a more environmentally sustainable processing of Li-battery cells.

  14. Room temperature large-scale synthesis of layered frameworks as low-cost 4 V cathode materials for lithium ion batteries

    PubMed Central

    Hameed, A. Shahul; Reddy, M. V.; Nagarathinam, M.; Runčevski, Tomče; Dinnebier, Robert E; Adams, Stefan; Chowdari, B. V. R.; Vittal, Jagadese J.

    2015-01-01

    Li-ion batteries (LIBs) are considered as the best available technology to push forward the production of eco-friendly electric vehicles (EVs) and for the efficient utilization of renewable energy sources. Transformation from conventional vehicles to EVs are hindered by the high upfront price of the EVs and are mainly due to the high cost of LIBs. Hence, cost reduction of LIBs is one of the major strategies to bring forth the EVs to compete in the market with their gasoline counterparts. In our attempt to produce cheaper high-performance cathode materials for LIBs, an rGO/MOPOF (reduced graphene oxide/Metal-Organic Phosphate Open Framework) nanocomposite with ~4 V of operation has been developed by a cost effective room temperature synthesis that eliminates any expensive post-synthetic treatments at high temperature under Ar/Ar-H2. Firstly, an hydrated nanocomposite, rGO/K2[(VO)2(HPO4)2(C2O4)]·4.5H2O has been prepared by simple magnetic stirring at room temperature which releases water to form the anhydrous cathode material while drying at 90 °C during routine electrode fabrication procedure. The pristine MOPOF material undergoes highly reversible lithium storage, however with capacity fading. Enhanced lithium cycling has been witnessed with rGO/MOPOF nanocomposite which exhibits minimal capacity fading thanks to increased electronic conductivity and enhanced Li diffusivity. PMID:26593096

  15. Synthesis and electrochemical characterization of mesoporous Li2FeSiO4/C composite cathode material for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Kumar, Ajay; Jayakumar, O. D.; Bazzi, Khadije; Nazri, Gholam-Abbas; Naik, Vaman M.; Naik, Ratna

    2015-03-01

    Lithium iron silicate (Li2FeSiO4) has the potential as cathode for Li ion batteries due to its high theoretical capacity (~ 330 mAh/g) and improved safety. The application of Li2FeSiO4 as cathode material has been challenged by its poor electronic conductivity and slow lithium ion diffusion in the solid phase. In order to solve these problems, we have synthesized mesoporous Li2FeSiO4/C composites by sol-gel method using the tri-block copolymer (P123) as carbon source. The phase purity and morphology of the composite materials were characterized by x-ray diffraction, SEM and TEM. The XRD pattern confirmed the formation of ~ 12 nm size Li2FeSiO4 crystallites in composites annealed at 600 °C for 6 h under argon atmosphere. The electrochemical properties are measured using the composite material as positive electrode in a standard coin cell configuration with lithium as the active anode and the cells were tested using AC impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge cycling. The Li2FeSiO4/C composites showed a discharge capacity of ~ 240 mAh/g at a rate of C/30 at room temperature. The effect of different annealing temperature and synthesis time on the electrochemical performance of Li2FeSiO4/C will be presented.

  16. Room temperature large-scale synthesis of layered frameworks as low-cost 4 V cathode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Hameed, A. Shahul; Reddy, M. V.; Nagarathinam, M.; Runčevski, Tomče; Dinnebier, Robert E.; Adams, Stefan; Chowdari, B. V. R.; Vittal, Jagadese J.

    2015-11-01

    Li-ion batteries (LIBs) are considered as the best available technology to push forward the production of eco-friendly electric vehicles (EVs) and for the efficient utilization of renewable energy sources. Transformation from conventional vehicles to EVs are hindered by the high upfront price of the EVs and are mainly due to the high cost of LIBs. Hence, cost reduction of LIBs is one of the major strategies to bring forth the EVs to compete in the market with their gasoline counterparts. In our attempt to produce cheaper high-performance cathode materials for LIBs, an rGO/MOPOF (reduced graphene oxide/Metal-Organic Phosphate Open Framework) nanocomposite with ~4 V of operation has been developed by a cost effective room temperature synthesis that eliminates any expensive post-synthetic treatments at high temperature under Ar/Ar-H2. Firstly, an hydrated nanocomposite, rGO/K2[(VO)2(HPO4)2(C2O4)]·4.5H2O has been prepared by simple magnetic stirring at room temperature which releases water to form the anhydrous cathode material while drying at 90 °C during routine electrode fabrication procedure. The pristine MOPOF material undergoes highly reversible lithium storage, however with capacity fading. Enhanced lithium cycling has been witnessed with rGO/MOPOF nanocomposite which exhibits minimal capacity fading thanks to increased electronic conductivity and enhanced Li diffusivity.

  17. Room temperature large-scale synthesis of layered frameworks as low-cost 4 V cathode materials for lithium ion batteries.

    PubMed

    Hameed, A Shahul; Reddy, M V; Nagarathinam, M; Runčevski, Tomče; Dinnebier, Robert E; Adams, Stefan; Chowdari, B V R; Vittal, Jagadese J

    2015-01-01

    Li-ion batteries (LIBs) are considered as the best available technology to push forward the production of eco-friendly electric vehicles (EVs) and for the efficient utilization of renewable energy sources. Transformation from conventional vehicles to EVs are hindered by the high upfront price of the EVs and are mainly due to the high cost of LIBs. Hence, cost reduction of LIBs is one of the major strategies to bring forth the EVs to compete in the market with their gasoline counterparts. In our attempt to produce cheaper high-performance cathode materials for LIBs, an rGO/MOPOF (reduced graphene oxide/Metal-Organic Phosphate Open Framework) nanocomposite with ~4 V of operation has been developed by a cost effective room temperature synthesis that eliminates any expensive post-synthetic treatments at high temperature under Ar/Ar-H2. Firstly, an hydrated nanocomposite, rGO/K2[(VO)2(HPO4)2(C2O4)]·4.5H2O has been prepared by simple magnetic stirring at room temperature which releases water to form the anhydrous cathode material while drying at 90 °C during routine electrode fabrication procedure. The pristine MOPOF material undergoes highly reversible lithium storage, however with capacity fading. Enhanced lithium cycling has been witnessed with rGO/MOPOF nanocomposite which exhibits minimal capacity fading thanks to increased electronic conductivity and enhanced Li diffusivity. PMID:26593096

  18. Surface micro-structuring of intercalation cathode materials for lithium-ion batteries: a study of laser-assisted cone formation

    NASA Astrophysics Data System (ADS)

    Pfleging, W.; Smyrek, P.; Hund, J.; Bergfeldt, T.; Pröll, J.

    2015-03-01

    Strong efforts are currently undertaken in order to further improve the electrochemical performance of high energy lithium-ion batteries containing thick composite electrode materials. The properties of these electrode materials such as active surface area, film thickness, and film porosity strongly impact the cell life-time and cycling stability. A rather new approach is to generate hierarchical architectures into cathode materials by laser direct ablation as well as by laserassisted formation of self-organized structures. It could be shown that appropriate surface structures can lead to a significant improvement of lithium-ion diffusion kinetics leading to higher specific capacities at high charging and discharging currents. In this paper, the formation of self-organized conical structures in intercalation materials such as LiCoO2 and LiNi1/3Mn1/3Co1/3O2 is investigated in detail. For this purpose, the cathode materials are exposed to excimer laser radiation with wavelengths of 248 nm and 193 nm leading to cone structures with outer dimensions in the micrometer range. The process of cone formation is investigated using laser ablation inductively coupled plasma mass spectrometry and laser-induced breakdown spectroscopy (LIBS). Cone formation can be initiated for laser fluences up to 3 J/cm2 while selective removal of lithium was observed to be one of the key issues for starting the cone formation process. It could be shown that material re-deposition supports the cone-growth process leading to a low loss of active material. Besides the cone formation process, laser-induced chemical surface modification will be analysed by LIBS.

  19. Pyrite (FeS2) nanocrystals as inexpensive high-performance lithium-ion cathode and sodium-ion anode materials

    NASA Astrophysics Data System (ADS)

    Walter, Marc; Zünd, Tanja; Kovalenko, Maksym V.

    2015-05-01

    In light of the impeding depletion of fossil fuels and necessity to lower carbon dioxide emissions, economically viable high-performance batteries are urgently needed for numerous applications ranging from electric cars to stationary large-scale electricity storage. Due to its low raw material cost, non-toxicity and potentially high charge-storage capacity pyrite (FeS2) is a highly promising material for such next-generation batteries. In this work we present the electrochemical performance of FeS2 nanocrystals (NCs) as lithium-ion and sodium-ion storage materials. First, we show that nanoscopic FeS2 is a promising lithium-ion cathode material, delivering a capacity of 715 mA h g-1 and average energy density of 1237 Wh kg-1 for 100 cycles, twice higher than for commonly used LiCoO2 cathodes. Then we demonstrate, for the first time, that FeS2 NCs can serve as highly reversible sodium-ion anode material with long cycling life. As sodium-ion anode material, FeS2 NCs provide capacities above 500 mA h g-1 for 400 cycles at a current rate of 1000 mA g-1. In all our tests and control experiments, the performance of chemically synthesized nanoscale FeS2 clearly surpasses bulk FeS2 as well as large number of other nanostructured metal sulfides.In light of the impeding depletion of fossil fuels and necessity to lower carbon dioxide emissions, economically viable high-performance batteries are urgently needed for numerous applications ranging from electric cars to stationary large-scale electricity storage. Due to its low raw material cost, non-toxicity and potentially high charge-storage capacity pyrite (FeS2) is a highly promising material for such next-generation batteries. In this work we present the electrochemical performance of FeS2 nanocrystals (NCs) as lithium-ion and sodium-ion storage materials. First, we show that nanoscopic FeS2 is a promising lithium-ion cathode material, delivering a capacity of 715 mA h g-1 and average energy density of 1237 Wh kg-1 for 100

  20. Ultrasound Nondestructive Characterization of Transparent Spinel

    NASA Astrophysics Data System (ADS)

    Bottiglieri, S.; Portune, A. R.; Haber, R. A.

    2011-06-01

    Ceramic materials have attractive attributes for applications that experience high stresses or strain rates. Compared to metal-based systems, ceramics offer a lower areal density which reduces weight, but do not depreciate the integrity of other properties. The ability to tailor the microstructure of ceramics used in armor systems is a common way to increase specific mechanical properties or obtain certain material characteristics. Properties such as elastic modulus, hardness, and density are those that are typically desired to be enhanced. By modifying the microstructure one can obtain a ceramic with these enhanced properties as well as high optical transmission across a wide range of the electromagnetic spectrum. The testing of these properties and ballistic performance is usually destructive, expensive, and time consuming. Common assessments using ultrasonic NDE usually include spatially locating large flaws, sonic velocity measurements, and elastic property measurements. The use of acoustic spectroscopy to go beyond typical ultrasonic NDE in structural ceramics and allow for the use of a microstructural characterization tool is investigated in this paper. Ultrasound absorption by lithium fluoride precipitates in aluminate spinel (MgAl2O4) present as defined spectral peaks. Average heterogeneity size determination in magnesium aluminate spinel MgAl2O4 by method of acoustic spectroscopy is shown.