From Liquid to Solid‐State Batteries: Li‐Rich Mn‐Based Layered Oxides as Emerging Cathodes with High Energy Density

Abstract Li‐rich Mn‐based (LRMO) cathode materials have attracted widespread attention due to their high specific capacity, energy density, and cost‐effectiveness. However, challenges such as poor cycling stability, voltage deca,y and oxygen escape limit their commercial application in liquid Li‐ion batteries. Consequently, there is a growing interest in the development of safe and resilient all‐solid‐state batteries (ASSBs), driven by their remarkable safety features and superior energy density. ASSBs based on LRMO cathodes offer distinct advantages over conventional liquid Li‐ion batteries, including long‐term cycle stability, thermal and wider electrochemical windows stability, as well as the prevention of transition metal dissolution. This review aims to recapitulate the challenges and fundamental understanding associated with the application of LRMO cathodes in ASSBs. Additionally, it proposes the mechanisms of interfacial mechanical and chemical instability, introduces noteworthy strategies to enhance oxygen redox reversibility, enhances high‐voltage interfacial stability, and optimizes Li⁺ transfer kinetics. Furthermore, it suggests potential research approaches to facilitate the large‐scale implementation of LRMO cathodes in ASSBs.