Dynamic transport of Zn2+ in ionic liquid intercalated V2O5 cathode for high-performance aqueous Zn-ion batteries

Due to high safety and low-cost, aqueous Zn-ion batteries (ZIBs) are expected to be a promising next-generation energy storage technology. Exploiting high capacity and stable cathode materials are extremely important for the development of aqueous ZIBs. However, commercial V₂O₅ despite its high theoretical specific capacity, suffers from structural instability during charging and discharging, and strong electrostatic forces seriously limit the diffusion of zinc ions. Herein, a novel dynamic transport mechanism of Zn²⁺ is designed by intercalating organic cations (C₈H₁₅N₂⁺) from ionic liquids into the interlayers of V₂O₅. The electrostatic interaction between the C₈H₁₅N₂⁺ and the V-O layers enhance the structure stability of the layers and increase the interlayer spacing. Meanwhile, the C₈H₁₅N₂⁺ between the V-O layers reduce the diffusion energy barrier of Zn²⁺ and enable the rapid dynamically transport of Zn²⁺. The diffusion coefficient is enhanced by an order of magnitude. The optimized V₂O₅ cathode exhibits a high capacity of 268 mA h/g at 100 mA/g and excellent cycling stability (over 500 cycles at 200 mA/g with nearly 100 % coulombic efficiency). The home-made pouch cells deliver a high energy density of 310 W h kg⁻¹. This interesting idea opens up a new research direction for high-energy secondary batteries.