Bifunctional Mo-doped SnS2 nanosheets enabling synergistic polysulfide confinement and catalytic conversion in Li–S batteries

Abstract

Metal sulfides, such as SnS₂, have been extensively studied as separator modifiers in lithium–sulfur batteries (LSBs) owing to their dual functionality in chemically anchoring lithium polysulfides (LiPSs) and catalytically facilitating redox reactions. Nevertheless, poor electrical conductivity and limited catalytic efficiency restrict their practical implementation for LiPS transformation kinetics. To address these issues, we prepared Mo-doped SnS₂ (Mo–SnS₂) nanosheets with sulfur vacancies through a rapid one-pot formamide-assisted method. The incorporation of Mo heteroatoms not only improves conductivity but also induces favorable sulfur vacancies, synergistically promoting both adsorption and electrocatalytic conversion of LiPSs. The Li–S cell with a Mo–SnS₂ nanosheet-modified separator delivers a remarkable initial capacity of 1007.5 mAh g⁻¹ at 1C, maintains 799.5 mAh g⁻¹ after 600 cycles with a low fading ratio of 0.034% per cycle, and demonstrates a favorable rate performance of 591.9 mAh g⁻¹ at 5C. This defect engineering strategy through heteroatom doping offers a promising approach to concurrently mitigate the polysulfide shuttle effect and enhance the reaction kinetics in sulfur-based energy storage systems.