Li‐excess 3d‐transition metal layered oxides are promising candidates in high‐energy‐density cathode materials for improving the mileage of electric vehicles. However, their low rate capability has hindered their practical application. The lack of understanding about the redox reactions and migration behavior at high C‐rates make it difficult to design Li‐excess materials with high rate capability. In this study, the characteristics of the atomic behavior that is predominant at fast charge/discharge are investigated by comparing cation‐ordered and cation‐disordered materials using X‐ray absorption spectroscopy (XAS). The difference in the atomic arrangement determines the dominance of the transition metal/oxygen redox reaction and the variations in transition metal–oxygen hybridization. In‐depth electrochemical analysis is combined with operando XAS analysis to reveal electronically and structurally preferred atomic behavior when a redox reaction occurs between oxygen and each transition metal under fast charge/discharge conditions. This provides a fundamental insight into the improvement of rate capability. Furthermore, this work provides guidance for identifying high‐energy‐density materials with complex structural properties.

中文翻译：

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揭示锂过量的3d过渡金属氧化物的快速氧化还原行为，以实现高倍率能力

过量的3d过渡金属层状氧化物是高能量密度阴极材料中有望改善电动汽车行驶里程的候选材料。但是，它们的低速率能力阻碍了它们的实际应用。对高C速率下的氧化还原反应和迁移行为缺乏了解，使得设计具有高速率能力的Li过量材料变得困难。在本研究中，通过使用X射线吸收光谱法（XAS）比较阳离子有序和阳离子无序的材料，研究了快速充放电中主要的原子行为特征。原子排列的不同决定了过渡金属/氧还原反应的优势以及过渡金属-氧杂化的变化。深度电化学分析与操作XAS分析相结合，可以揭示在快速充电/放电条件下氧气与每种过渡金属之间发生氧化还原反应时，电子和结构上优选的原子行为。这为提高费率能力提供了基本的见识。此外，这项工作为确定具有复杂结构特性的高能量密度材料提供了指导。