Bimetallic chalcogenides enable highly efficient polysulfide capture and conversion in lean-electrolyte Li–S batteries

The commercialization of Li–S batteries is obstructed by the sluggish redox kinetics and serious shuttling behaviors of polysulfides. Herein, a rationally structured sulfur host material was designed to tackle these issues, nickel-doped cobalt sulfide nanoparticles uniformly decorated on electrospun carbon nanofibers. The sulfide nanoparticles were demonstrated to effectively capture polysulfides and catalytically promote their redox conversions due to the Ni atoms modulated the band structure of cobalt sulfide. Moreover, the interlinked porous architecture of decorated carbon nanofibers also contributes to alleviating volume expansion of sulfur cathode and provides rapid electron transfer paths and Li-ion diffusion channels. Benefiting from these attributes, the prepared cathodes delivered an excellent rate capability and long cycling stability (capacity decay of 0.142% per cycle over 300 cycles). Additionally, under high sulfur content (83.3%) and lean electrolyte (5 μL mg⁻¹) showed a high capacity of 556 mAh g⁻¹ at 0.5 C and 590 mAh g⁻¹ after 180 cycles at 0.2 C, demonstrating highly efficient utilization of sulfur and extraordinary potential for practical application of Li–S batteries.