Surface evolution mechanisms and stabilization approaches for lithium manganese oxide in rechargeable Li-ion batteries

Lithium manganese oxide (LiMn2O4) is an appealing cathode material for rechargeable lithium-ion batteries (LIBs) by virtue of its low cost, abundance, and fast Li-ion diffusion. Nevertheless, its practical application is curbed by severe surface degradation during electrochemical cycling, essentially regulated by oxygen loss/evolution and manganese dissolution. Compounding these bulk-driven instabilities, electrolyte-induced interfacial reactions and the formation of non-uniform cathode-electrolyte interphases further accelerate surface reconstruction and exacerbate Mn redox imbalance, ultimately culminating in capacity fade and truncated battery lifetime. This review systematically addresses the fundamental mechanisms of surface evolution in LiMn2O4, highlighting the coupling between oxygen redox reactions, lattice instability, and Mn dissolution pathways. Additionally, a comprehensive survey of stabilization strategies is provided, including intrinsic defect engineering and substitutional doping, surface coating techniques, controlled deposition strategies, and electrolyte optimization through additives and ionic liquids. By assimilating mechanistic insights with interfacial engineering advances, this review highlights approaches to mitigate surface degradation and accentuates the need for combined structural, chemical, and interfacial modifications to realize the full potential of LiMn2O4 in next-generation LIBs.