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

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 Mn₃O₄ 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 Mn₃O₄ (designated as V_Mn-Mn₃O₄@C). The cationic vacancy endows Mn₃O₄ 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-Mn₃O₄@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-Mn₃O₄@C cathodes maintain superior cycling stability of 5000 cycles with nearly 100% capacity retention at 1 A g⁻¹.