The overcharge behaviors of 1000 mAh LiCoO₂/graphite pouch cells are systematically investigated through the analysis of morphology, structural and thermal stability of LiCoO₂ under different state of charge (SOC) of 120%, 150%, 174%, 190% and 220%. The LiCoO₂ experiences the phase transition from O3 to H1-3 and then O1 together with the grain breakage and boundary slip as evidenced by XRD and SEM analysis respectively, which results in the pronounced Co dissolution after the SOC of 174%. The impedance analysis of the pouch cells and coin cells demonstrates that the main contribution of impedance increase originates from the LiCoO₂ electrode. Under the combined effect of structural collapse, Co dissolution, and electrolyte oxidization, the thermal stability of LiCoO₂ cathode materials reduces with the progressing of overcharge as revealed by differential scanning calorimetry (DSC) results. We hope that this comprehensive understanding can provide meaningful guidance for advancing the overcharge performance of LiCoO₂/graphite pouch cells.

通过分析120％，150％，174％，190％和220％荷电状态下LiCoO ₂的形貌，结构和热稳定性，系统地研究了1000 mAh LiCoO ₂ /石墨袋式电池的过充电行为。％。LiCoO ₂经历了从O3到H1-3的相变，然后经历了O1的相变，分别由XRD和SEM分析证明，这导致SOC达到174％时，Co溶出明显。袋式电池和纽扣电池的阻抗分析表明，阻抗增加的主要贡献来自LiCoO ₂电极。差示扫描量热法（DSC）结果表明，在结构崩溃，Co溶解和电解质氧化的综合作用下，LiCoO ₂阴极材料的热稳定性会随着过充电的进行而降低。我们希望这种全面的了解可以为提高LiCoO ₂ /石墨袋式电池的过充电性能提供有意义的指导。