Water-Lubricated Intercalation in V 2 O 5 ·nH 2 O for High-Capacity and High-Rate Aqueous Rechargeable Zinc Batteries.

Low-cost, environment-friendly aqueous Zn batteries have great potential for large-scale energy storage, but the intercalation of zinc ions in the cathode materials is challenging and complex. Herein, the critical role of structural H2 O on Zn2+ intercalation into bilayer V2 O5 ·nH2 O is demonstrated. The results suggest that the H2 O-solvated Zn2+ possesses largely reduced effective charge and thus reduced electrostatic interactions with the V2 O5 framework, effectively promoting its diffusion. Benefited from the "lubricating" effect, the aqueous Zn battery shows a specific energy of ≈144 Wh kg-1 at 0.3 A g-1 . Meanwhile, it can maintain an energy density of 90 Wh kg-1 at a high power density of 6.4 kW kg-1 (based on the cathode and 200% Zn anode), making it a promising candidate for high-performance, low-cost, safe, and environment-friendly energy-storage devices.