Tunnel‐Preinserted Guest Zinc Tailoring VO ₂ (B) Enhances Zn ²⁺ /H ⁺ Reversible De/intercalation Capability

Abstract VO ₂ (B) has attracted tremendous attention as a cathode for aqueous zinc‐ion batteries (AZIBs), but its low intrinsic electronic conductivity and uncontrolled vanadium dissolution hinder further practical applications. Herein, Zn _0.03 VO ₂ , with guest zinc ions preinserted into the tunnel sites, is demonstrated to enhance the conductivity and cyclability of VO ₂ (B). The tailored structure, featuring a modulated electronic configuration, offers enlarged ion diffusion tunnels, improved electronic conductivity, and enhanced electrochemical activity, thereby facilitating the reversible de‐intercalation of Zn ²⁺ /H ⁺ ions, as confirmed by both experimental results and theoretical calculations. Notably, vanadium dissolution is significantly suppressed due to the chemical pre‐insertion of guest zinc, which weakens the interaction between Zn ²⁺ and host lattice, as well as the homologous ion effect. As a result, Zn _0.03 VO ₂ cathode delivers a high capacity of 358 mAh g ⁻¹ , particularly at low current density of 0.1 A g ⁻¹ , with 85% capacity retention after 300 cycles, excellent rate capability of 175 mAh g ⁻¹ at 5 A g ⁻¹ , and long cycling stability over 2000 cycles at 20 A g ⁻¹ . Moreover, a pseudocapacitive‐dominated Zn ²⁺ /H ⁺ co‐insertion mechanism is conclusively identified through electrochemical and spectroscopic analyses. This work provides valuable insights into ion‐preinserted structural modulation of vanadium oxides for the development of high‐performance AZIBs.