Electrochemomechanical degradation is one of the most common causes of capacity deterioration in high-energy-density cathodes, particularly intercalation-based layered oxides. Here we reveal the presence of rotational stacking faults (RSFs) in layered lithium transition-metal oxides, arising from specific stacking sequences at different angles, and demonstrate their critical role in determining structural/electrochemical stability. Our combined experiments and calculations show that RSFs facilitate oxygen dimerization and transition-metal migration in layered oxides, fostering microcrack nucleation/propagation concurrently with cumulative electrochemomechanical degradation on cycling. We further show that thermal defect annihilation as a potential solution can suppress RSFs, reducing microcracks and enhancing cyclability in lithium-rich layered cathodes. The common but previously overlooked occurrence of RSFs suggests a new synthesis guideline of high-energy-density layered oxide cathodes.

电化学机械降解是高能量密度正极（尤其是基于插层的层状氧化物）容量恶化的最常见原因之一。在这里，我们揭示了层状锂过渡金属氧化物中存在的旋转堆垛层错（RSF），这些层错是由不同角度的特定堆垛序列引起的，并证明了它们在确定结构/电化学稳定性中的关键作用。我们的综合实验和计算表明，RSF 促进层状氧化物中的氧二聚和过渡金属迁移，促进微裂纹成核/扩展，同时促进循环中累积的电化学机械降解。我们进一步表明，热缺陷消灭作为一种潜在的解决方案可以抑制RSF，减少微裂纹并增强富锂层状正极的循环性能。常见但之前被忽视的 RSF 的出现提出了高能量密度层状氧化物阴极的新合成指南。