Suppressing vanadium dissolution and vacancy degradation by anion healing for highly stable vanadium oxide cathodes in aqueous zinc-ion batteries

Aqueous zinc ion batteries (ZIBs) are attractive for safe, cost-effective, and sustainable energy storage, but the practical application of layered vanadium-based cathodes remains challenged by sluggish Zn²⁺ transport, poor conductivity, and vanadium dissolution. Here, we develop a fluorine-healing strategy to stabilize oxygen vacancies in Zn²⁺ pre-intercalated hydrated vanadium oxides (F-ZnVOH), thereby regulating ion transport, electronic structure, and structural stability. Zn²⁺ pre-intercalation expands the interplanar spacing and induces oxygen vacancies, providing accessible pathways for Zn²⁺ storage, while fluorine healing enhances ionic/electronic conductivity and reduces activation energy, promoting the Zn²⁺ diffusion kinetics. Moreover, fluorine healing stabilizes the vacancy-rich framework through strong VF interactions, suppressing vacancy reconstruction, vanadium dissolution, and irreversible lattice degradation during cycling. As a result, F-ZnVOH exhibits a reversible capacity of 534 mAh g^-1 at 0.1 A g^-1, with (94.0 ± 0.9)% (n = 3) of its initial capacity retained after 200 cycles at 0.5 A g^-1. Even under the high current density of 8 A g^-1, it maintains (94.2 ± 2)% (n = 3) of its capacity over 7500 cycles. In addition, electrochemical and spectroscopic analyses reveal a reversible Zn²⁺/H⁺ co-insertion/extraction mechanism.