The structural stability of LiCoO₂ at high voltages is especially important when enhancing the cutoff voltage used as an effective method to boost the energy density. we trace the origin of different crack formation mechanisms during fast and slow charging rates using a combination of qualitative atomic-scale differential phase-contrast scanning transmission electron microscope (STEM) images and electron energy loss spectroscopy (EELS) analysis of LiCoO₂ (LCO). We demonstrate that fast charging induces large heterogenous Li flux insertion into the cathode, resulting in large strain and big crack formation; in contrast, low cycling rates trigger phase transformations that only induce micro-cracks. To clarify the mechanisms, we mapped out local strain analysis for the LCO particles and detailed phase transition routes. The comprehensive characterization results are meaningful for researchers to understand the failure mechanisms under high voltage and inspire innovative solutions to capture higher capacity out of LCO.

当提高用作提高能量密度的有效方法的截止电压时， LiCoO ₂在高压下的结构稳定性尤为重要。我们结合定性原子尺度微分相衬扫描透射电子显微镜 (STEM) 图像和 LiCoO 2 的电子能量损失光谱 (EELS) 分析，追踪了快速和慢速充电过程中不同裂纹形成机制的_起源(LCO)。我们证明快速充电会导致大量异质 Li 通量插入正极，导致大应变和大裂纹形成；相比之下，低循环率会触发相变，只会导致微裂纹。为了阐明机制，我们绘制了 LCO 颗粒的局部应变分析和详细的相变路径。全面的表征结果对于研究人员了解高压下的失效机制并激发创新解决方案以从 LCO 中获取更高容量具有重要意义。