Graphene Oxide Wrapped CuV₂O₆ Nanobelts as High-Capacity and Long-Life Cathode Materials of Aqueous Zinc-Ion Batteries

Rechargeable aqueous zinc-ion batteries are considered as a promising alternative of lithium-ion batteries for stationary energy storage because of their economical and high safety quality. However, their widespread application is still impeded by the development of cathode materials with poor energy density and limited long-term stability. Herein, we report a high-performance CuV₂O₆ cathode material for aqueous zinc-ion batteries and elucidate the zinc-storage mechanism. The reversible phase transformation between CuV₂O₆ and ZnV₂O₆, accompanied by zinc ion insertion/extraction and the reduction/oxidation of metallic Cu nanoparticles, all contribute to excellent battery performance: an impressively high specific capacity of 427 mA h g^-1 at current density of 0.1 A g^-1, long-term cycling stability with minor capacity loss (0.7%) after 3000 cycles at a high current density of 5 A g^-1, and a high energy density of 317 Wh kg^-1 at a power density of 210 W kg^-1. Furthermore, graphene oxide wrapped CuV₂O₆ nanocomposites are successfully fabricated, which demonstrates the significantly enhanced specific capacity (at least 30% improvement). This work provides an intriguing cathode material and expands available options of transition metal vanadate materials for zinc-ion batteries.