Engineering sulphur vacancy in VS₂as high performing zinc-ion batteries with high cyclic stability

Metal dichalcogenides have been widely investigated in various energy storage devices in the past decades due to their large interlayer spacing formed by the weak van der Waals force between the layers. Among the various metal dichalcogenides, vanadium disulphide (VS₂) has recently been demonstrated as a potential cathode in zinc-ion batteries (ZIBs) exhibiting encouraging electrochemical performance and excellent reversible Zn²⁺storage. However, the main challenge for VS₂is its less-than-satisfactory capacity ofca.150-160 mA h g⁻¹. As such, this work proposes the use of the sulphur vacancy defect engineering strategy to further enhance the electrochemical performance of VS₂. The as-assembled Zn//sulphur deficient VS₂cell (denoted as D-VS₂) is able to deliver a high specific capacity of 262 mA h g⁻¹at a current density of 0.1 A g⁻¹, which isca.1.75 times higher as compared to pristine VS₂,i.e., 150 mA h g⁻¹at 1 A g⁻¹. Furthermore, the cyclic stability of Zn//D-VS₂is also superior as compared to its counterpart with pristine VS₂as the cathode (Zn//P-VS₂). Zn//D-VS₂can achieve a capacity retention of 94% after 524 hours of continuous deep cycling, while Zn//P-VS₂can achieve only 81% retention after about 270 hours of deep cycling. Hence, based on this work, it is expected that sulphur vacancy defect engineering could be a viable strategy to enhance the electrochemical performance of not only VS₂, but also of various metal dichalcogenides.