Enhanced electrochemical performance of molten salt synthesized V2CTx MXene@VOx composite in Zn ion aqueous electrolytes

Abstract

The development of MXenes using Lewis acidic salts for etching (MS-MXenes) in molten salts presents a novel, fluorine-free method attracting considerable interest. However, the behavior of various MS-MXenes and their derivatives in aqueous environments remains largely unexplored. Particularly, vanadium-based MXenes demonstrate intriguing properties in Zn ion aqueous electrolytes. Herein, a fluorine-free V₂CT_x MXene@VO_x is synthesized by molten salt etching under an argon atmosphere. The electrochemical properties of V₂CT_x@VO_x are tested in various aqueous electrolytes, including Zn(TFSI)₂, ZnSO₄, ZnBr₂, ZnAc₂, and ZnCl₂ solutions. The V₂CT_x@VO_x shows high redox capacities in all these Zn ion electrolytes, with the peak performance observed in 1 M ZnBr₂, achieving a maximum capacity of 172 mAh g⁻¹ at 1 mV s⁻¹. This performance rivals that of V₂CT_x MXene prepared through wet-chemical methods. These results underscore the potential of MS-MXenes materials in aqueous energy storage applications.