Iron-Doped Nickel Disulfide as an Efficient Polysulfide Barrier for High-Performance Lithium-Sulfur Batteries

Severe polysulfide shuttle effect and sluggish redox kinetics remain primary impediments to the practical application of high-energy-density lithium-sulfur (Li-S) batteries. Herein, a metal-organic framework (MOF)-assisted strategy was employed to fabricate a bimetallic Fe-doped NiS ₂ catalyst. The incorporation of Fe via in situ synthesis effectively modulates the electronic structure of NiS ₂ , constructing synergistic bimetallic active sites. Comprehensive experimental analyses and density functional theory (DFT) calculations verify that these sites not only significantly enhance the chemisorption of lithium polysulfides (LiPSs) but also lower the energy barrier for their catalytic conversion, achieving a balance between adsorption and kinetics. Furthermore, the catalyst inherits the porous and layered architecture from its MOF precursor, which prevents structural collapse and provides ample space for physical LiPSs confinement. Benefiting from this dual-confinement and accelerated redox kinetics, the Li-S battery equipped with the Fe-NiS ₂ /PP separator delivers superior electrochemical performance: a high initial discharge capacity of 1395 mAh g⁻¹ at 0.1 C and remarkable long-term cycling stability with a capacity decay rate as low as 0.07% per cycle over 500 cycles at 1 C. This work demonstrates the effectiveness of bimetallic modulation, offering a feasible strategy for designing functional interlayers to advance the practical application of Li-S batteries.