Earth-Abundant Spinel LiMn₂O₄ Cathode for Lithium-Ion Batteries: Challenges, Strategies, and Perspectives

Recently, lithium-ion batteries (LIBs) have gained extensive applications in electric vehicles and energy storage systems due to their high energy density and long service life. In LIBs, the energy density and overall cost highly depend on the cathode material. Therefore, low-cost Mn-based spinel LiMn₂O₄ (LMO) has emerged as an outstanding candidate and attracted the attention of many scientific researchers. However, structural instability during cycling,  particularly capacity deterioration at high temperatures, severely hinders  its commercial applications. Various studies reveal that the Jahn-Teller(J-T) effect and Mn disproportionation constitute primary causes of the irreversible phase transition and Mn dissolution induced by capacity decline. This review first discusses the interrelationships among spinel, layered, and rock salt structures and the underlying principles of the LMO charging and discharging process. Subsequently, we systematically review the capacity decay mechanism and analyze recent advancements in performance enhancement strategies, with particular emphasis on how partially disordered spinel architectures exceeds theoretical capacity limitations while achieving ultrahigh rate capability. Furthermore, rapid synthesis of LMO through advanced manufacturing processes is introduced. This review summarizes the progress and challenges of pioneering research on the LMO and provides new ideas for the practical application of LMO.