Phosphate synergism activation strategy for amorphous vanadium oxide cathode materials of high-performance aqueous zinc ion batteries

Abstract

Durability of V-based cathode materials at low current density is a key factor for application of aqueous zinc ion batteries (AZIBs). An isotropy high entropy amorphous vanadium oxide material (VO-PO@C) is obtained by in-situ electrochemical oxidation activation strategy. Larger phosphate cluster radius not only offers abundant defect active sites but also improves the solid-state solubility and transfer kinetics of Zn2+. For the in-situ electrochemical oxidation activation strategy, phosphate can prevent the structural reorganization which is caused by excessive oxidation. In addition, Zn|Zn(CF3SO3)2|VO-PO@C exhibits a specific capacity of 247.8 m h g−1 at 0.5 A g−1, and an excellent cyclic performance up to 300 cycles at 1.0 A g−1 with a capacity retention of 94.2% and coulombic efficiency of 100% without any phase transformation. Phosphate is beneficial to activate amorphous vanadium oxide and increase ions diffusion contribution of reversible capacity for high-performance AZIBs cathode materials. This work provides a universality design strategy for efficient V-based cathode electrodes of AZIBs.