Excellent Rate Capability and Cycling Stability of Novel H₂V₃O₈ Doped with Graphene Materials Used in New Aqueous Zinc-Ion Batteries

Nanorods of H₂V₃O₈ wrapped in graphene sheets were prepared by hydrothermal synthesis and tested as the cathode in an aqueous rechargeable zinc-ion battery. Cyclic voltammetry indicates that H₂V₃O₈ nanorods/graphene-523 K allows a rapid and reversible Zn²⁺ intercalation/extraction without the evolution of H₂ and O₂. The structure and composition of the composite graphene H₂V₃O₈ nanorods [determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SEAD), and X-ray photoelectron spectroscopy (XPS)] offered excellent electrochemical performance including a high specific discharge capacity of 401 mAh g^–1 at 200 mA g^–1, a high rate capacity of 170 mAh g^–1 at 2 A g^–1, and prolonged cycling stability after 200 cycles. The addition of the graphene sheets increases the diffusion coefficient of the zinc ions by an order of magnitude. Five light-emitting diodes (LEDs) are successfully powered by the aqueous rechargeable zinc-ion batteries (ARZBs) for more than 2 min to demonstrate the practical application. This work provides a creative choice for energy storage applications with low prices, green and environmental protection, and excellent safety.