Tetragonal VO2 hollow nanospheres as robust cathode material for aqueous zinc ion batteries

The emerging aqueous zinc ion batteries (ZIBs) are one of the alternatives to lithium ion batteries (LIBs) because zinc electrode possesses low equilibrium potential, high exchange current density and high hydrogen evolution overpotential. Nevertheless, they are still challenging on improving the cycle stability and compatibility with electrolytes. Herein, we report VO2-5@PPy hollow nanospheres consisting of many nanosheets as cathode materials for ZIBs. The spaces between nanospheres facilitate transmission of Zn ions and make electrode tolerate high volume change. The as-obtained material delivers a specific capacity of 440 mAh g(-1) at 0.1 A g(-1). Also, they remain a reversible capacity of 143 mAh g(-1) after 860 cycles at 1 A g(-1). (C) 2020 Elsevier Ltd. All rights reserved.