Thermo-Electrochemical Tuning of V2O5 to ZnV3O8 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 V2O5 cathodes, creating defect-rich Zn-V2O5 (ZnV3O8), 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 Zn2+ 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 ZnV3O8, 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.