Tunnel-Preinserted Guest Zinc Tailoring VO2(B) Enhances Zn2+/H+ Reversible De/intercalation Capability

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.