MoS2/MoP@Ti3C2Tx ternary heterostructure with dual heterointerfaces for accelerating polysulfide conversion kinetics in lithium–sulfur batteries

Abstract

Lithium–sulfur batteries are considered a highly promising next-generation energy storage system due to their exceptionally high theoretical specific capacity and energy density. However, their practical application is severely hindered by the shuttle effect of soluble lithium polysulfides and the sluggish kinetics of sulfur redox reactions. To address these challenges, this study designs and constructs a ternary heterostructured material with dual heterointerfaces, MoS₂/MoP@Ti₃C₂T_x, for the functional modification of polypropylene separators. In this architecture, MoS₂/MoP is coupled with Ti₃C₂T_x via Ti–S bonds, establishing a stable dual-heterointerface system. This design significantly promotes interfacial charge transfer, enhances the adsorption capability and catalytic conversion efficiency for polysulfides, and thereby effectively suppresses the shuttle effect. Density functional theory calculations reveal that the introduction of Ti₃C₂T_x optimizes the electronic structure of Mo sites, inducing an upshift of the d-band center, which increases the adsorption energy for polysulfides and accelerates the reaction kinetics. The battery employing the MoS₂/MoP@Ti₃C₂T_x modified separator exhibits outstanding electrochemical performance, delivering a specific capacity of 831.7 mAh g⁻¹ at 3C, maintaining a reversible capacity of 681.8 mAh g⁻¹ after 500 cycles at 1C, and achieving a high initial areal capacity of 5.1 mAh cm⁻² under a high sulfur loading of 5.5 mg cm⁻². This study provides an effective strategy for developing high-performance separator materials for lithium–sulfur batteries through heterointerface engineering.