Driving intercalation kinetic through hydrated Na+ insertion in V2O5 for high rate performance aqueous zinc ion batteries

Abstract

V2O5, as a positive electrode material in aqueous zinc ion batteries, is easy to collapse in the process of repeated charging and discharging of Zn2+, thus leading to an inferior electrochemical performance. In this paper, hydrated Na+ has been inserted into the V2O5 layer by a simple hydrothermal method to synthesize NaxV2O5·nH2O (NaVO). Electrochemical characterization of NaVO is as follows, which has a capacity of 452 mA h g−1 at 100 mA g−1 and a capacity holding of 79% after 1000 cycles at 4 A g−1, indicating that the insertion of hydrated Na+ can efficiently enhance high-rate performance of V2O5 cathode. In-situ XRD tests have been employed to reveal the underlying mechanism of the superior electrochemical performance. It is certified that hydrated Na+ incorporation not only provides support pillars for V2O5 thereby improving the stability of V2O5 structure, but also significantly reduces the material’s desolvation penalty and enhances intercalation kinetics, which leads to a superior rate capability. These demonstrate the method that insertion of hydrated alkali metal ion into interlayer of nanomaterials is ideally suited for V-based material and other layered cathode materials for AZIBs.