Vacancy‐Engineered Vanadium Cathode for Fast‐Charging Aqueous Zinc Batteries of Ultra‐Long Cycle Life

Abstract Aqueous zinc‐ion batteries have emerged as strong contenders for sustainable energy storage; however, their widespread adoption is constrained by sluggish Zn ²⁺ transport and suboptimal cathode performance. A rapid, energy‐efficient solvothermal synthesis of Na ₂ V ₆ O ₁₆ is reported, and introduces cation vacancies via initial electrochemical engineering. This electrochemical pre‐treatment generates Na⁺ vacancies, significantly enhances Zn ²⁺ diffusion, and enables synergistic Zn ²⁺ /H ⁺ co‐storage. Ex situ and operando analyses, supported by theoretical and computational studies, confirm the pivotal role of Na⁺ vacancies in facilitating ion transport and improving capacity. The vacancy‐engineered cathode exhibits a high discharge capacity of 692.8 mAh g ⁻¹ at 100 mA g ⁻¹ , delivering an energy density of 467.6 Wh kg ⁻¹ and outstanding cycling stability over 10 000 cycles at 10 A g ⁻¹ . It also sustains a capacity of 366.6 mAh g ⁻¹ at 1000 mA g ⁻¹ and retains 395.2 mAh g ⁻¹ at 100 mA g ⁻¹ under high mass loading, highlighting its rate capability and practical applicability. The battery shows fast‐charging capability, delivering a specific capacity of 138.2 mAh g ⁻¹ within 12.4 s, and has an ultra‐long cycle life of over 75 000 cycles with capacity loss of only 0.0003% per cycle at a current density of 40 A g ⁻¹ .