Zinc ion modulation of hydrated vanadium pentoxide for high-performance aqueous zinc ion batteries

Abstract

The structure of V2O5 as a cathode material is prone to collapse during repeated embedding/de-embedding of Zn2+, and the instability of the material limits its application. Introducing metal ions into the V2O5 layer provides larger ion channels, improves cycling kinetics, and acts as a pillar to enhance the structure stability during the charge/discharge process. In this study, Zn0·2V2O5·0.51H2O (ZVOH) is prepared by the hydrothermal method by embedding both Zn2+ and structural water molecules in the V2O5 interlayer. ZVOH is used as the cathode in zinc-ion batteries (ZIBs) with high power and energy densities (∼6779.3 W kg−1 and 289.6 Wh kg−1) and outstanding cycling stability. Furthermore, the valence changes of vanadium in ZVOH during charging and discharging as well as the morphological changes on the surface of the electrode material are investigated by ex-situ methods. The binding energy of Zn2+ at the sites within ZVOH and the migration energy barrier for Zn2+ migration on the ZVOH surface are also investigated by density functional theory.