A multifunctional layered Ti3C2Tx/VS2 composite sulfur host for promoting the conversion of lithium polysulfides in lithium–sulfur batteries

Abstract

Lithium–sulfur (Li–S) batteries show promise in meeting the requirements of high energy density and cost-effective energy storage systems. However, they are hindered by slow reaction kinetics and lithium polysulfide (LiPS) shuttling. In this research, a multifunctional sulfur host, Ti₃C₂T_x/VS₂, is developed by incorporating VS₂ onto the surface of few-layer Ti₃C₂T_x using a self-assembly method. The presence of VS₂ sheets can prevent the re-stacking of Ti₃C₂T_x sheets. The Ti₃C₂T_x/VS₂ composite exhibits high electronic conductivity, strong adsorption and anchoring of LiPSs by Ti₃C₂T_x, and excellent electrocatalytic activity due to VS₂. Additionally, carbon nanotubes (CNTs) are used as both conductive agents and binders in the cathode to promote electron/ion transport and improve structural stability. These characteristics can accelerate redox kinetics and mitigate LiPS shuttling. The Ti₃C₂T_x/VS₂/S composite cathode demonstrates a high initial capacity of 1382.7 mA h g⁻¹ and excellent cycling stability, maintaining a reversible capacity of 806.6 mA h g⁻¹ after 150 cycles at 0.1C. Moreover, 3D printing technology is utilized to manufacture 3D grid electrodes with a high sulfur loading of 10.05 mg cm⁻². The 3D-printed composite cathode maintains an areal capacity of 7.13 mA h cm⁻² after 100 cycles at 0.05C.