Layered Ni0.22V2O5·nH2O as high-performance cathode material for aqueous zinc-ion batteries

Vanadium-based material has great potential for the cathode of aqueous Zn-ion batteries (ZIBs). Herein, the Ni0.22V2O5·nH2O cathode materials were fabricated by a hydrothermal method. The morphologies and structures of materials were characterized by XRD, SEM, and TEM. The results indicated that the Ni0.22V2O5·nH2O nanobelts appear a typical layered structure, and Ni2+ was embedded in the layer. The electrochemical performance was measured by the galvanostatic charge–discharge test and cyclic voltammetry. The Zn-Ni0.22V2O5 battery represents a capacity of 320.2 mAh g−1 at 0.2 A g−1. The cycle reversible capacity retention rate was 93.9% of the initial capacitance after 2000 cycles at 5 A g−1. Meanwhile, the transmutation of the structure was characterized by in situ and ex situ XRD. The main peak corresponding to the Ni0.22V2O5 electrode at 34.7° slightly shifts to higher 2θ values and then shifts to the initial state during the charge and discharge process. The reversibility of structure improves the electrochemical stability of the Ni0.22V2O5 electrode.