Multifunctional Carbon Modification Enhancement for Vanadium-Based Phosphates as an Advanced Cathode of Zinc-Ion Batteries

In recent years, rechargeable aqueous zinc-ion batteries (ZIBs) have shown extraordinary potential due to their safety, nontoxicity, sustainable zinc resources, and low price. However, the lack of suitable cathode materials hinders the development of ZIBs. Recently, layered phosphates have been widely used as cathode materials. As one typical phosphate cathode, vanadium oxyphosphate (VOPO4) has inherently low electronic conductivity and structural dissolution in electrochemical reactions, limiting its development. To solve these problems, VOPO4/C is prepared by combining multifunctional carbon material with a VOPO4 interlayer and an external surface, which not only improves the electronic conductivity of the composite material but also effectively inhibits the dissolution of VOPO4 in the electrolyte. As a result, the prepared VOPO4/C could deliver a reversible capacity of 140 mA h g-1 at a current density of 100 mA g-1. Furthermore, the rate performance of the VOPO4/C composite has also been improved significantly. In the process of charging and discharging, zinc ions in the composite show perfect intercalate and deintercalate performance.