Boosted Zn2+ storage performance of hydrated vanadium oxide by defect and heterostructure

Abstract

The inherent sluggish Zn²⁺ diffusion and poor electronic conductivity limit the ion intercalation/deintercalation process in aqueous Zn-ion batteries (ZIBs) using an oxide-based cathode. Here, we demonstrated that a heterostructure in the form of defective hydrated vanadium oxide embedded in the porous carbon textile (d-VOH@CT) could tackle these issues. The additional edges created by crystal defects significantly promoted facile Zn-ion adsorption and intercalation. Expanded interlayer spacing and reduced crystalline domain size kinetically facilitated fast Zn-ion diffusion in d-VOH flakes with shortened diffusion paths. Moreover, the heterostructure of d-VOH on the conductive carbon textile triggered rapid charge transfer, leading to high rate capability and structural stability. The ZIBs fabricated using the d-VOH@CT cathode delivered a preferable reversible capacity of 416 mA h g⁻¹ at 0.1 A g⁻¹, an impressive energy density of 293 W h kg⁻¹ and long cycle life. In addition, the d-VOH@CT heterostructure was able to be used as a freestanding cathode for a flexible ZIB with outstanding mechanical robustness and electrochemical stability.