Intergrated morphology engineering and alloying strategy for FeNi@NC Catalysts: Tackling the polysulfide shuttle in Li-S batteries

Lithium-sulfur batteries (LSBs) are constrained by the shuttle effect and slow kinetics of lithium polysulfides (LPSs). Herein, we introduces a novel FeNi bimetallic catalyst, encapsulated within a structure of highly graphitized and nitrogen-doped carbon tubules, denoted as FeNi@NC. The synthesis employs a straightforward high-temperature calcination and freeze-drying technique, tailored to modify the functional separator layer in LSBs. FeNi@NC includes a diverse range of carbon tube morphologies, facilitating quick electron and lithium-ion transfer. Notably, it displays remarkable catalytic activity towards LPSs. Specifically engineered, the FeNi@NC catalyst prompts the generation of S•3− radicals, providing an alternative pathway for polysulfide transformation, ultimately enhancing the redox kinetics of the polysulfides. As a result, a battery incorporating the FeNi@NC catalyst-modified separator layer attains a notable initial specific capacity of 1378.8 mAh/g at 0.1C, and a negligible capacity decay rate of only 0.11% per cycle after 500 cycles at 1C. The robust performance extends to areal capacity, which reaches a high value of 6.25 mAh cm−2 with a high sulfur loading of 4.99 mg cm−2. Even after 100 cycles, the areal capacity remains significant at 4.28 mAh cm−2. These findings showcase the promising potential for the application of bimetallic alloy catalysts in LSBs.