In this work, capacity degradation in fast‐charging process is studied by using a power‐optimized graphite‐LiNi0.80Co0.15Al0.05O2 (NCA) electrode couple and a three‐electrode coin cell as the testing vehicle. It is shown that capacity degradation consists of two distinct stages, (1) rapid degradation in early period and (2) progressive degradation over lifetime, which are associated with the electrochemical reduction of electrolyte solvents on the graphite anode and the structural deterioration of the NCA cathode, and are well correlated to a decrease in Coulomb efficiency. Analyses on the change in differential capacity profile and the recoverability of the lost capacity reveal that capacity degradation mainly originates from structural deterioration of the NCA cathode over lifetime, and it aggravates with the state‐of‐charge and temperature. Based on this guideline, we show that capacity degradation of the Li‐ion batteries in the fast‐charging applications can be greatly mitigated by limiting the cell’s operation to a relatively low state‐of‐charge (i.e., a relatively low charging cutoff voltage).

中文翻译：

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锂电池快速充电过程中的揭露容量降低机制

在这项工作中，通过使用功率优化的石墨-LiNi0.80Co0.15Al0.05O2（NCA）电极对和三电极纽扣电池作为测试工具，研究了快速充电过程中的容量降低。结果表明，容量下降包括两个不同的阶段，（1）早期迅速下降，（2）整个寿命期间逐渐下降，这与石墨阳极上电解质溶剂的电化学还原和NCA的结构恶化有关。阴极，并且与库仑效率的降低密切相关。对差分容量曲线的变化和容量损失的可恢复性进行的分析表明，容量下降主要源于NCA阴极在整个使用寿命期间的结构劣化，并且随着荷电状态和温度而加剧。