Thermally coupled defective 1 T/2H MoSe2 as a multifunctional electrocatalyst for polysulfide regulation in practical lithium–sulfur batteries

Abstract

Despite their attractive high energy density, lithium–sulfur (Li-S) batteries face critical barriers to practical application, including polysulfide shuttling, sluggish redox kinetics, and poor cell stability, which necessitate the development of effective catalytic strategies to overcome these challenges. Here, we report the thermal coupling of defective mixed-phase MoSe2 (1 T/2H) with sulfur to suppress the shuttle effect and boost the redox kinetics in practical Li-S batteries. The MoSe2 with dislocation defects exhibits strong interfacial interactions with sulfur species and also coexists with 1 T/2H phases, which synergistically enhance polysulfide adsorption and catalytic conversion. As a result, the charge-transfer resistance and activation energy of the MoSe2-applied cell are significantly reduced, with the activation energy decreasing by 54% under high sulfur loading and a lean electrolyte. Furthermore, sulfur utilization reaches 63% at an E/S ratio of 12 μL mg−1, and after 100 cycles at 0.2C, the specific capacity is 810 mAh g−1, and the Coulombic efficiency is 96.5%, ensuring stable redox reversibility. Our study demonstrates the potential of defective 1 T/2H MoSe2 as a multifunctional electrocatalyst, paving the way for the development of practical and scalable Li-S batteries.