期刊
ENERGY STORAGE MATERIALS
卷 22, 期 -, 页码 113-119出版社
ELSEVIER
DOI: 10.1016/j.ensm.2019.01.004
关键词
Li-ion battery; Voltage decay; Surface thermodynamic stability; Defective graphene
资金
- National Key R&D Program of China [2016YFB0100200]
- National Natural Science Foundation of China [51671004, U1764255]
- Beijing Municipal Natural Science Foundation [2181001]
Li-rich Mn-based cathode materials used in Li-ion batteries show ultra-high capacity due to the favorable oxygen redox behavior induced by activation of Li2MnO3. However, structural degradation associated with oxygen loss and transition metal migration occurs due to excessive oxygen redox on the surface, which is the main origin of the low coulombic efficiency, capacity fade, and voltage decay, which limit the widespread application of this high-capacity material. In this study, the underlying mechanism of tuning the surface thermodynamic stability of the Li2MnO3 model material was systematically investigated. The results showed that a defective graphene coating can effectively stabilize surface oxygen by modification of the potential energy surface, while reducing Mn migration and increasing the diffusivity of Li ions. Theoretical calculations predicted an improvement in the electrochemical performance, which was confirmed by experimental results. These findings may provide a novel strategy for increasing the surface thermodynamic stability of electrode materials.
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