Thermo‐Electrochemical Tuning of V ₂ O ₅ to ZnV ₃ O ₈ Enables Ultra‐Stable Zinc‐Ion Battery

Abstract Zinc‐ion batteries (ZIBs) are emerging as viable alternatives due to their safety, cost‐effectiveness, and abundant zinc resources. However, the lack of stable and high‐performance cathode materials limits their practical application. Vanadium‐based materials, with their versatile crystal structures and variable valence states, are promising candidates but face challenges such as sluggish ion kinetics and poor electronic conductivity. This study introduces a novel thermo‐electrochemical activation strategy for V 2 O 5 cathodes, creating defect‐rich Zn‐V 2 O 5 (ZnV 3 O 8 ), which enhances performance significantly. The activated cathode achieves a remarkable increase in specific capacity from 73 to 302 mAh g −1 at 0.1 A g −1 and exhibits ultralong cycling stability over 4500 cycles at 2 A g −1 . Comprehensive electrochemical characterization reveals improved Zn 2+ diffusion rates, supported by first‐principles calculations that highlight the stabilizing role of hydrogen intercalation. The activation process induces a thermodynamically driven phase transition to ZnV 3 O 8 , enabling superior ion accommodation, reduced activation energy, and enhanced structural robustness. Ex‐situ analyses further elucidate the structural and morphological evolution during cycling. This study underscores the potential of thermo‐electrochemical activation as a straightforward and effective approach for engineering vanadium oxide cathodes, advancing the development of high‐performance ZIBs with enhanced energy density and cycling stability.