Regulating the Intralayer Cation Disorder in Layered Lithium‐Rich Cathodes to Improve Cycle Performance

The Li/Mn ordered structure of lithium‐rich (LR) cathodes leads to the heterogeneous Li2MnO3 and LiTMO2 components, readily triggering structural degeneration and performance degradation in long‐term cycling. However, the lack of guiding principles for promoting cation disorder within the transition metal (TM) layers has posed a persistent challenge in designing homogeneous layered LR cathodes. Herein, the (Li + Mn)TM content in the TM layer as a criterion for the design of cation‐disordered layered LR cathodes is proposed. The intralayer cation disorder can be achieved by tuning the (Li + Mn)TM content less than 0.5 combined with incorporating the solute ions with suitable ionic radii. For a multicomponent LR nickel cobalt manganese (LRNCM) oxides system, multiscale structural analyses reveal that cation‐disordered layered Li1.1(Ni0.6Co0.1Mn0.3)0.9O2 (LR613) exhibits enhanced compositional homogeneity and higher R3¯$\bar{3}$m symmetry. The developed LR613 cathode undergoes a solid‐solution reaction during Li+ deintercalation and mitigates voltage decay during cycling. It is elucidated that intralayer cation disorder effectively alleviates microstrain within the cathode structure and enhances overall structural stability. This comprehensive understanding of the composition‐structure‐electrochemical behavior relationship inspires the development of durable cation‐disordered layered LR cathodes through composition tuning. The interlayer and intralayer cationic ordering can be regulated by the incorporation of ions with different ionic radii. A design principle for cation‐disordered layered structure is proposed to guide the synthesis of homogeneous lithium‐rich cathodes. The intralayer cation disorder helps alleviate structural microstrain during Li+‐(de)intercalation process, thus improving the electrochemical cycle performance of lithium‐rich cathodes.