阴极
电解质
溶解
电化学
氧化物
化学工程
容量损失
氧化还原
化学
氧气
电池(电)
过渡金属
材料科学
无机化学
电极
冶金
热力学
物理化学
工程类
功率(物理)
物理
生物化学
有机化学
催化作用
作者
Ke Zhou,Chunyang Zhang,Yining Li,Xiangsi Liu,Jianjun Liu,Zhengyan Lun,Yong Yang
标识
DOI:10.1016/j.cej.2023.142709
摘要
Li-rich cation-disordered rock-salt oxides (DRXs) are promising candidates for next-generation Li-ion cathode materials due to the demonstrated high capacity (> 300 mAh g−1) by utilizing both transition metal (TM) cations and oxygen anions with a much-widened material design space as compared to conventional layered cathodes, which heavily rely on Co and Ni. However, the serious performance deterioration during long-term cycling impedes their practical applications. Although oxygen loss and associated densified surface layer are responsible for the performance deterioration, these issues are part of the scope of cathode electrolyte interface (CEI) which need further study, including its chemical composition, chemical and electrochemical stability, formation mechanism as well as the effects on battery performance. Through careful monitoring of the CEI evolution of Li1.2Mn0.4Ti0.4O2 (LMTO) in conventional carbonated-based electrolyte upon charging and discharging, we identify that the continuously growing CEI layer exhibits gradually increasing LiF as the main composition. The significant change of the CEI layer is closely related to loss of lattice oxygen (O2−), the continuous over-reduction of redox-active TMs (e.g. Mn3+, Mn 4+) from the cathode surface, severe TMs dissolution, and the release of CO2/O2, and irreversible phase transition in surface structures, which eventually cause a fast capacity degradation and voltage decay. This research provides a fundamental interpretation for understanding interfacial stability in this young class of DRX cathode materials.
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