Se-doped MoC/NC nanorods modified separator for synergistically accelerating trap and conversion of polysulfides toward advanced Li-S battery

• A novel N-doped carbon-coated porous Se-doped molybdenum carbide (Se-MoC/NC) nanorods is successfully constructed. • Se-MoC/NC nanorods as a multifunctional layer, is used to modify separator. • The Se-MoC/NC delivers efficiently capture, catalyze conversion for polysulfides , and transfer/diffuse electrons/Li + . • The Li-S battery with Se-MoC/NC@PP separator displays excellent rate performance and cycling stability. Lithium-sulfur (Li-S) batteries have emerged as a viable option for advanced energy storage solutions, driven by their exceptional energy density and low cost. Nevertheless, the sluggish sulfur redox kinetics and the intricate lithium polysulfides (LiPSs) shuttle have critically hampered their commercialization. Herein, a novel nitrogen-doped carbon-coated porous selenium-doped molybdenum carbide (Se-MoC/NC) nanorods-modified polypropylene (PP) separator (Se-MoC/NC@PP) with potent adsorption capacities, numerous catalytic active sites, and an efficient channel for electron/Li + transfer has been reported. The effectiveness of the modified separator in capturing and catalyzing the conversion of polysulfides has been identified through density function theory (DFT) calculations. Benefitting from these alluring properties, the Li-S cell with Se-MoC/NC@PP delivers a high reversible capacity (1044.9 mAh g −1 ) at 0.5C and remains 652.5mAh g −1 after 500 cycles with a decline rate of 0.075 % per cycle. Even at 1C, it can reach up to the discharge capacity of 941.9 mAh g −1 accompanied by a low capacity fading of 0.056 % per cycle. after long-term 700 cycles. Of particular note, at 0.1C, the Se-MoC/NC@PP-based cell exhibits an impressive areal capacity of 4.7 mAh cm −2 even when subjected to a high S loading of 5.0 mg cm −2 and a lean electrolyte-to-sulfur (E/S) ratio of 10 μL mg −1 . The Li//Li symmetric cell cycles steadily for 1000 h, confirming the interlayer simultaneously promotes sulfur evolution kinetics and sieves lithium ions. The strategy of heteroatom doping offers a viable pathway for advancing high-performance Li-S battery development and application.