Rose-like vanadium disulfide coated by hydrophilic hydroxyvanadium oxide with improved electrochemical performance as cathode material for aqueous zinc-ion batteries

摘要

VS2, as a typical transition-metal diahalcogenide with hexagonal structure, has attracted considerable attention as an electrode material for aqueous zinc-ion batteries (ZIBs) owing to its large layer spacing, which is beneficial for Zn2+ intercalation/deintercalation. However, due to the solubility of the vanadium element, the stability of VS2 is poor in aqueous electrolytes, which results in severe capacity degradation and limits its practical applications. In this work, a hydrophilic VOOH coating on rose-like VS2 composed of nanosheets (VS2@VOOH) is synthesized by a simple one-pot hydrothermal method. The O-H in VOOH do not only improve the infiltration of the electrode and the electrolyte, but also reduce the dissolution of vanadium and increased electrochemical performance, especially in terms of rate capability and long cycle life. For instance, this composite material, as an aqueous ZIB cathode, delivers a superior capacity of 107.5 mA h g(-1) after 350 cycles at 1.5 A g(-1). In particularly, it can maintain a reversible capacity of 91.4 mA h g(-1) even after 400 cycles at a high current density of 2.5 A g(-1). Therefore, we believe that VS2@VOOH may be regarded as a very promising cathode material for ZIBs.