Cationic Vacancy Modulation of Mn₃O₄ as a Superior Cathode for Durable Aqueous Zinc‐Ion Batteries

Abstract Aqueous zinc‐ion batteries (AZIBs) have attracted more and more attention owing to their high safety, low cost, and environmental friendliness. Mn‐based materials are considered as one of the most promising cathode materials for AZIBs because of their high output voltage, eco‐friendliness, and abundance. However, the low electrochemical activity and the manganese dissolution of Mn 3 O 4 lead to the low specific capacity and inferior cycling stability, hindering its practical applications. Herein, a facile and low‐cost strategy is designed that combines cationic vacancy modulation with Mn ion‐confinement effect in a synergistic action to boost zinc ion energy storage capability of inert Mn 3 O 4 (designated as V Mn ‐Mn 3 O 4 @C). The cationic vacancy endows Mn 3 O 4 with more active sites, resulting in an increased specific capacity. Meanwhile, the manganese dissolution is inhibited via the Mn ion‐confinement effect of the carbon framework, thereby improving the cycling stability of the cathode. Consequently, the developed Zn/V Mn ‐Mn 3 O 4 @C batteries deliver a high specific capacity of 280.9 mAh g −1 and 98.4% capacity retention after 100 cycles at 0.1 A g −1 . More importantly, V Mn ‐Mn 3 O 4 @C cathodes maintain superior cycling stability of 5000 cycles with nearly 100% capacity retention at 1 A g −1 .