Aluminum-ion intercalation and reduced graphene oxide wrapping enable the electrochemical properties of hydrated V2O5 for Zn-ion storage

Abstract

Aqueous zinc-ion batteries (AZIBs) have the characteristics of high theoretical specific capacity, wide source and high safety, and become a very promising energy storage equipment. Due to the larger solvation radius and stronger electrostatic interaction of divalent zinc ions, the cathode materials need to have larger space and more stable structure. The ions or molecules are pre-inserted between the vanadium oxide layers as pillars, which can provide large layer spacing and facilitate the insertion/extraction process and diffusion of zinc ions, but their performance is limited due to their low conductivity and solubility. By combining it with carbon materials with high conductivity and strong chemical stability, it can make up for these shortcomings and greatly improve the electrochemical performance. Herein, aluminum-ion intercalated hydrated V2O5 (AlxV2O5·nH2O, abbreviated as AlVOH)/reduced graphene oxide (AlVOH/rGO) composite was synthesized by a one-step hydrothermal method to improve the Zn ion storage properties of hydrated V2O5 (VOH). The composite material has a large layer spacing of 13.3 Å, and the composite of rGO not only enhances its electrical conductivity, but also protects the electrode active material to a certain extent. As expected, AlVOH/rGO has good cycle stability and rate performance, which shows a specific capacity of 405 mA h·g−1 at 0.1 A·g−1 and has no significant energy attenuation after 100 cycles.