Design Principles for High‐Capacity, Long‐Life Cation‐Disordered Rocksalt Cathodes

Abstract Lithium‐excess cation disordered rocksalt (DRX) cathodes have gained wide attention because of their capability of delivering high energy densities solely relying on inexpensive and earth‐abundant transition metal (TM) species. To date, various strategies have been proposed for their intrinsic performance optimization, including designing high‐entropy compositions to suppress cation short‐range order (SRO), incorporating high Mn content to promote the in situ phase transformation to a partially‐disordered spinel phase (δ phase) or Cr doping to enhance the Li‐ion mobility; however, the compatibility of these strategies remains unexplored. In this study, the interplay among the three strategies is systematically investigated when applied concurrently via the design of a series of DRX cathode compounds. The findings demonstrate that compared to the other two strategies, DRX‐to‐δ phase transformation induced by high Mn content plays a more significant role in improving the electrochemical performance of DRX cathodes, which simultaneously elevates the capacity and cycle life. Cr or multi‐elemental doping will inevitably dilute the Mn concentration, limiting the performance enhancement. These insights ultimately contribute to the design of an optimal composition that combines high capacity and long cycle life.