Suppressing Jahn–Teller distortion in Mn2O3 via Ca2+ doping for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have gained significant attention owing to their high energy densities, low costs, and good safety. However, developing cathodes with high capacity and structural stability remains challenging. Herein, we propose a Ca 2+ doping strategy to design a high-performance Mn 2 O 3 cathode via a facile hydrothermal-calcination method. The Ca 2+ substitution has a dual functional effect: 1) it triggers charge compensation that converts partial Mn 3+ to Mn 4+ , decreasing the Mn 3+ / Mn 4+ ratio and reducing Jahn–Teller active centers; 2) it shortens the Mn O bonds, thereby reinforcing the Mn O framework and stabilizing the crystal structure. Consequently, in pure ZnSO 4 electrolyte, the optimized Ca 2+ doped cathode (CMO7) delivers a high specific capacity of 214.7 mAh g −1 at 100 mA g −1 , far surpassing pristine Mn 2 O 3 (102.3 mAh g −1 ). In a hybrid ZnSO 4 /MnSO 4 electrolyte, CMO7 achieves a higher capacity of 227.8 mAh g −1 at 100 mA g −1 and retains 88% of its capacity after 500 cycles at 1000 mA g −1 . This study provides a new perspective on the development of advanced Mn-based cathodes for durable aqueous zinc-ion batteries.