Traditional O3-type Li-rich layered materials are attractive with ultra-high specific capacities, but suffering from inherent problems of voltage hysteresis and poor cycle performance. As an alternative, O2-type materials show the potential to improve the oxygen redox reversibility and structural stability. However, their structure-performance relationship is still unclear. Here, we investigate the correlation between the Li component and dynamic chemical reversibility of O2-type Li-rich materials. By exploring the formation mechanism of a series of materials prepared by Na/Li exchange, we reveal that insufficient Li leads to an incomplete replacement, and the residual Na in the Li-layer would hinder the fast diffusion of Li⁺. Moreover, excessive Li induces the extraction of interlayer Li during the melting chemical reaction stage, resulting in a reduction in the valence of Mn, which leads to a severe Jahn-Teller effect. Structural detection confirms that the regulation of Li can improve the cycle stability of Li-rich materials and suppress the trend of voltage fading. The reversible phase evolution observed in in-situ X-ray diffraction confirms the excellent structural stability of the optimized material, which is conducive to capacity retention. This work highlights the significance of modulating dynamic electrochemical performance through the intrinsic structure.

传统的 O3 型富锂层状材料具有超高的比容量，但存在电压滞后和循环性能差的固有问题。作为替代方案，O2 型材料显示出改善氧氧化还原可逆性和结构稳定性的潜力。然而，它们的结构-性能关系仍不清楚。在这里，我们研究了锂组分与 O2 型富锂材料的动态化学可逆性之间的相关性。通过探索Na/Li交换制备的一系列材料的形成机制，我们发现Li不足导致置换不完全，Li层中残留的Na会阻碍Li ⁺的快速扩散. 此外，过量的Li会在熔融化学反应阶段引起夹层Li的析出，导致Mn的化合价降低，从而导致严重的Jahn-Teller效应。结构检测证实，锂的调节可以提高富锂材料的循环稳定性并抑制电压衰减趋势。在原位 X 射线衍射中观察到的可逆相演变证实了优化材料的优异结构稳定性，有利于容量保持。这项工作突出了通过内在结构调节动态电化学性能的重要性。