Molybdenum Substitution for Improving the Charge Compensation and Activity of Li2MnO3 |
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Authors: | Dr Jun Ma Dr Yong‐Ning Zhou Dr Yurui Gao Prof Qingyu Kong Prof Zhaoxiang Wang Prof Xiao‐Qing Yang Prof Liquan Chen |
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Institution: | 1. Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P. O. Box 603, Beijing 100190 (China), Fax: (+86)?10‐82649046;2. Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973 (United States);3. X‐ray Science Division, Argonne National Laboratory, 9700 South Cass Ave, Argonne, IL 60439 (United States) |
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Abstract: | Lithium‐rich layer‐structured oxides xLi2MnO3? (1?x)LiMO2 (0<x<1, M=Mn, Ni, Co, etc.) are interesting and potential cathode materials for high energy‐density lithium ion batteries. However, the characteristic charge compensation contributed by O2? in Li2MnO3 leads to the evolution of oxygen during the initial Li+ ion extraction at high voltage and voltage fading in subsequent cycling, resulting in a safety hazard and poor cycling performance of the battery. Molybdenum substitution was performed in this work to provide another electron donor and to enhance the electrochemical activity of Li2MnO3‐based cathode materials. X‐ray diffraction and adsorption studies indicated that Mo5+ substitution expands the unit cell in the crystal lattice and weakens the Li?O and Mn?O bonds, as well as enhancing the activity of Li2MnO3 by lowering its delithiation potential and suppressing the release of oxygen. In addition, the chemical environment of O2? ions in molybdenum‐substituted Li2MnO3 is more reversible than in the unsubstituted sample during cycling. Therefore molybdenum substitution is expected to improve the performances of the Li2MnO3‐based lithium‐rich cathode materials. |
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Keywords: | charge transfer doping layered compounds lithium molybdenum |
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