Lithium-rich oxide cathodes lose energy density during cycling due to atomic disordering and nanoscale structural rearrangements, which are both challenging to characterize. Here we resolve the kinetics and thermodynamics of these processes in an exemplar layered Li-rich (Li_1.2–xMn_0.8O₂) cathode using a combined approach of ab initio molecular dynamics and cluster expansion-based Monte Carlo simulations. We identify a kinetically accessible and thermodynamically favourable mechanism to form O₂ molecules in the bulk, involving Mn migration and driven by interlayer oxygen dimerization. At the top of charge, the bulk structure locally phase segregates into MnO₂-rich regions and Mn-deficient nanovoids, which contain O₂ molecules as a nanoconfined fluid. These nanovoids are connected in a percolating network, potentially allowing long-range oxygen transport and linking bulk O₂ formation to surface O₂ loss. These insights highlight the importance of developing strategies to kinetically stabilize the bulk structure of Li-rich O-redox cathodes to maintain their high energy densities.

由于原子无序和纳米级结构重排，富锂氧化物阴极在循环过程中会损失能量密度，这两者都很难表征。在这里，我们使用从头算分子动力学和基于簇扩展的蒙特卡罗模拟相结合的方法，解决了示例性层状富锂 (Li _{1.2– x} Mn _0.8 O ₂ ) 阴极中这些过程的动力学和热力学问题。我们确定了一种动力学上可行且热力学上有利的机制来大量形成 O ₂分子，涉及 Mn 迁移并由层间氧二聚驱动。在电荷顶部，体结构局部相分离成富MnO ₂区域和缺乏Mn的纳米空隙，其中含有O ₂分子作为纳米限制流体。这些纳米空隙以渗透网络连接，可能允许长距离氧气传输并将大量 O ₂形成与表面 O ₂损失联系起来。这些见解凸显了开发动态稳定富锂O-氧化还原阴极的体结构以保持其高能量密度的策略的重要性。