Mn-Doped MoP-Modified Separator to Enhance the Adsorption and Catalytic Conversion of Polysulfides in Li–S Battery

Lithium–sulfur (Li–S) battery, which boasts a high theoretical specific capacity, is regarded as a highly promising candidate for next-generation energy storage devices. However, the industrial application of Li–S batteries has been significantly impeded by the shuttle effect of lithium polysulfides (LiPSs) and the slow conversion kinetics of sulfur species. Doping engineering strategy can be used to adjust and optimize the electronic properties of metal compounds to enhance the chemisorption and redox reactions of LiPSs. Herein, carbon nanotube-supported Mn-doped MoP (CNT/Mn-MoP) is designed and synthesized to improve the ability to capture LiPSs and accelerate the reaction kinetics for Li–S batteries. Experimental and theoretical results indicate that Mn doping adjusts the electronic structure of MoP, significantly reduces the band gap between the 3d band center of Mo and the 2p band center of P, and increases the binding energy with LiPSs, thereby enhancing the chemisorption capacity of LiPSs and accelerating the diffusion and conversion kinetics of LiPSs. Therefore, the cell utilizing an optimized separator modified with CNT/Mn-MoP demonstrates a high initial specific capacity of 963 mAh g–1 at 1 C, accompanied by remarkable cycling stability (with a capacity attenuation rate of just 0.075% after 200 cycles) and satisfactory rate performance. In addition, the cell maintains a commendable initial areal capacity of 880 mAh g–1 at 0.2 C, despite the high sulfur loading of 5.2 mg cm–2. This research offers feasible insights into the design of advanced separators for Li–S batteries with excellent performance.