Ultrathin SnS₂ nanosheets as robust polysulfides immobilizers for high performance lithium-sulfur batteries

Highlights: • Ultrathin SnS₂ nanosheets have large surface area and fast charge transfer properties. • Ultrathin SnS₂ nanosheets can greatly improve the electrochemical properties of S/C composites for Li-S batteries. • Superior electrochemical performance of S/C-SnS₂-10 composites can be ascribed to the optimized synergistic effects between SnS₂ and porous carbon. - Abstract: Ultrathin SnS₂ nanosheets modified sulfur/carbon (S/C-SnS₂) composites were synthesized through a facile method by mixing sublimed sulfur, Ketjen Black and ultrathin SnS₂ nanosheets. The ultrathin SnS₂ nanosheets can provide remarkable binding strength, large surface area and fast charge transfer, therefore leading to favorable chemical interaction with polysulfides in Li-S batteries. Accompanied with the synergistic effects between physical confinement of porous carbon and chemical interactions of SnS₂, S/C-SnS₂ composites with different mass ratio of ultrathin SnS₂ nanosheets and C show much improved electrochemical properties. Among them, S/C-SnS₂ composite with 10 wt% of ultrathin SnS₂ nanosheets and 75 wt% of sulfur maintains superior long term cycling capacities of 800 mAh g⁻¹ at 0.5 C after 300 cycles and 540 mAh g⁻¹ at 2 C after 700 cycles.