Great focus has recently been placed on anionic redox, to which high capacities of Li-rich layered oxides are attributed. With almost doubled capacity compared with state-of-the-art cathode materials, Li-rich layered oxides still fall short in other performance metrics. Among these, voltage decay upon cycling remains the most hindering obstacle, in which defect electrochemistry plays a critical role. Here, we reveal that the metastable state of cycled Li-rich layered oxide, which stems from structural defects in different dimensions, is responsible for the voltage decay. More importantly, through mild thermal energy, the metastable state can be driven to a stable state, bringing about structural and voltage recovery. However, for the classic layered oxide without reversible anionic redox, thermal energy can only introduce cation disordering, leading to performance deterioration. These insights elucidate that understanding the structure metastability and reversibility is essential for implementing design strategies to improve cycling stability for high-capacity layered oxides.

近来，人们集中在阴离子氧化还原上，这归因于高容量的富含锂的层状氧化物。与最先进的阴极材料相比，其容量几乎翻了一番，但富锂的层状氧化物在其他性能指标上仍然不足。其中，循环时的电压衰减仍然是最大的障碍，其中缺陷电化学起着至关重要的作用。在这里，我们揭示了循环的富锂层状氧化物的亚稳态，这是由不同尺寸的结构缺陷引起的，是造成电压衰减的原因。更重要的是，通过温和的热能，亚稳态可以被驱动到稳定状态，从而实现结构和电压的恢复。但是，对于没有可逆阴离子氧化还原作用的经典层状氧化物，热能只能引入阳离子紊乱，导致性能下降。这些见解表明，了解结构的亚稳定性和可逆性对于实施设计策略以提高高容量层状氧化物的循环稳定性至关重要。