Rod-like anhydrous V₂O₅ assembled by tiny nanosheets as a high-performance cathode material for aqueous zinc-ion...

Aqueous zinc-ion batteries offer a low-cost and high-safety alternative for next-generation electrochemical energy storage, whereas suitable cathode materials remain to be explored. Herein, rod-like anhydrous V₂O₅ derived from a vanadium-based metal-organic framework is investigated. Interestingly, this material is assembled by tiny nanosheets with a large surface area of 218 m² g^-1 and high pore volume of 0.96 cm³ g^-1. Benefiting from morphological and structural merits, this material exhibits excellent performances, such as high reversible capacity (449.8 mA h g^-1 at 0.1 A g^-1), good rate capability (314.3 mA h g^-1 at 2 A g^-1), and great long-term cyclability (86.8% capacity retention after 2000 cycles at 2 A g^-1), which are significantly superior to the control sample. Such great performances are found to derive from high Zn²⁺ ion diffusion coefficient, large contribution of intercalation pseudocapacitance, and fast electrochemical kinetics. The ex situ measurements unveil that the intercalation of Zn²⁺ ion is accompanied by the reversible V⁵⁺ reduction and H₂O incorporation. This work discloses a direction for designing and fabricating high-performance cathode materials for zinc-ion batteries and other advanced energy storage systems.