A V10O24·nH2O Layered Material with Low Crystal Water Content as a High-Performance Cathode for Aqueous Zinc-Ion Batteries

Abstract

Vanadium oxides are considered as promising cathode materials for aqueous Zn-ion batteries due to their open-layered frameworks, large interlayer spacing and the abundant valence states of vanadium. However, the instable frameworks and the strong electrostatic effect between the layers and Zn²⁺ collectively hamper the further development of these materials. Herein, a layered hydrated vanadium oxide V₁₀O₂₄·0.93H₂O is synthesized via a one-pot hydrothermal method, and is evaluated as a cathode material for aqueous rechargeable zinc-ion batteries (ZIBs). The incorporation of low content of 0.93 unit of structural water not only stabilizes the structure over long-term cycling, but also reduces the electrostatic effect. The pillar effect of low water content still favors the fast Zn²⁺ storage of the electrode in the cycling process. Namely, the corresponding cathode displays impressive rate performance and long-term stability with a stable capacity of 139.5 mAh g⁻¹ over 800 cycles at 5 A g⁻¹ (with the capacity retention of 94%). The strategy of water molecule insertion (even fewer unit of water molecule) is regarded as a promising strategy to regulate vanadium-based cathode materials for Zn-ion batteries.