Rod-like anhydrous V 2 O 5 assembled by tiny nanosheets as a high-performance cathode material for aqueous zinc-ion batteries.

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 V 2 O 5 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 m 2 g -1 and high pore volume of 0.96 cm 3 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 Zn 2+ ion diffusion coefficient, large contribution of intercalation pseudocapacitance, and fast electrochemical kinetics. The ex situ measurements unveil that the intercalation of Zn 2+ ion is accompanied by the reversible V 5+ reduction and H 2 O incorporation. This work discloses a direction for designing and fabricating high-performance cathode materials for zinc-ion batteries and other advanced energy storage systems.