Li- and Mn-rich (LMR) cathode materials that utilize both cation and anion redox can yield substantial increases in battery energy density^1,2,3. However, although voltage decay issues cause continuous energy loss and impede commercialization, the prerequisite driving force for this phenomenon remains a mystery^3,4,5,6 Here, with in situ nanoscale sensitive coherent X-ray diffraction imaging techniques, we reveal that nanostrain and lattice displacement accumulate continuously during operation of the cell. Evidence shows that this effect is the driving force for both structure degradation and oxygen loss, which trigger the well-known rapid voltage decay in LMR cathodes. By carrying out micro- to macro-length characterizations that span atomic structure, the primary particle, multiparticle and electrode levels, we demonstrate that the heterogeneous nature of LMR cathodes inevitably causes pernicious phase displacement/strain, which cannot be eliminated by conventional doping or coating methods. We therefore propose mesostructural design as a strategy to mitigate lattice displacement and inhomogeneous electrochemical/structural evolutions, thereby achieving stable voltage and capacity profiles. These findings highlight the significance of lattice strain/displacement in causing voltage decay and will inspire a wave of efforts to unlock the potential of the broad-scale commercialization of LMR cathode materials.

同时利用阳离子和阴离子氧化还原的富锂和富锰 (LMR) 正极材料可以显着提高电池能量密度^1,2,3。然而，尽管电压衰减问题会导致持续的能量损失并阻碍商业化，但这种现象的先决驱动力仍然是一个谜^3,4,5,6在这里，利用原位纳米级敏感的相干 X 射线衍射成像技术，我们揭示了在电池运行期间纳米应变和晶格位移不断累积。有证据表明，这种效应是结构退化和氧损失的驱动力，这引发了众所周知的 LMR 阴极中的快速电压衰减。通过进行跨越原子结构、初级粒子、多粒子和电极水平的微观到宏观长度表征，我们证明了 LMR 阴极的异质性不可避免地会导致有害的相位移/应变，这是常规掺杂或涂层无法消除的方法。因此，我们提出介观结构设计作为减轻晶格位移和不均匀电化学/结构演变的策略，从而实现稳定的电压和容量曲线。这些发现突出了晶格应变/位移在引起电压衰减方面的重要性，并将激发一波努力来释放 LMR 正极材料大规模商业化的潜力。