MXene nanosheets modified with different intercalators as the separator for lithium–sulfur batteries

Abstract

The shuttle effect and sluggish reaction kinetics induced by soluble lithium polysulfides (LiPSs) in the electrolyte significantly hinder the commercial viability of lithium–sulfur batteries. Two-dimensional MXene materials have demonstrated significant potential in enhancing the performance of separators in lithium–sulfur batteries. In this study, MAX-phase MXene was etched using an HF-HCl acid mixture and subsequently intercalated with various agents, including lithium chloride (LiCl, L-MXene) and tetra-methylammonium hydroxide (TMAH, T-MXene), with the unmodified M-MXene serving as a comparison. These three types of MXene materials were used as separators in lithium–sulfur batteries, and their impacts on battery performance were evaluated through a series of electrochemical tests. The results demonstrated that the intercalated MXene significantly enhanced both the catalytic activity and the trapping efficiency of lithium polysulfides (LiPSs), leading to improved rate performance and cycling stability in the lithium–sulfur (Li–S) battery. The battery fabricated with L-MXene intercalated with LiCl exhibited an impressive initial capacity of 1076.9 mA h g⁻¹ at a charge/discharge rate of 0.2C. Even when the rate was increased to 1C, the initial capacity remained at 760 mA h g⁻¹. After 500 charge/discharge cycles, the capacity remained 559 mA h g⁻¹, corresponding to a capacity retention of 73%.