Microstructure Strain of ZnMn₂O₄ Spinel by Regulation of Tetrahedral Sites for High‐Performance Aqueous Zinc‐Ion Battery

Abstract Manganese oxides are widely used as cathode materials in aqueous zinc‐ion batteries (AZIBs) due to their low cost, multiple oxidation states, and high theoretical specific capacity. However, the further development of Mn‐based oxides is severely hindered by poor structural reversibility and sluggish reaction kinetics. Herein, a microstructure strain strategy is proposed to regulate the microstructure of MnO₆ in ZnMn₂O₄ (ZMO) through partial atomic substitution on tetrahedral sites. The Ni substitution of ZMO (ZN_xMO) with enlarged crystal plane spacing, increased Mn─O bond binding energy, and enhanced oxygen vacancy defects exhibits superior structural stability and faster ion transport kinetics. Correspondingly, the ZN_0.5MO/NCNTs cathode delivers a favorable high specific capacity of 239.2 mAh g⁻¹ at 0.1 A g⁻¹ with excellent rate performance as well as longer‐term cycle life (over 3000 cycles at 1.0 A g⁻¹). The outstanding performance of ZN_xMO is deeply rooted in its Zn²⁺‐transport friendly in asymmetric MnO₆ channel and the structure reversibility during the Zn²⁺‐intercalation/deintercalation process. This study provides an excellent example of using a microstructure strain strategy to design stable and high‐specific capacity manganese‐based cathode materials for Zn storage.