Tunable Conversion to Spinel–Layered LiMnO2 via Protonated Mn3O4 for Ultrastable Lithium-Ion Batteries

Lithium manganese-rich oxides are promising low-cost cathode materials for non-aqueous lithium-ion batteries. However, their cycle performances are limited by the cooperative Jahn–Teller effect associated with Mn3+, leading to severe structural degradation and Mn dissolution. Herein, spinel–layered Li0.98MnO1.992 with alleviated Jahn–Teller distortion and less oxygen loss is developed by tunable conversion via using protonated Mn3O4 as the original material, significantly suppressing Mn dissolution and enhancing structural stability, which enables an enhanced specific capacity of 250.5 mAh g–1 as well as an ultralong cycle life. This work provides important insights into developing highly stable Jahn–Teller active electrode materials for sustainable lithium-ion batteries.