Graphene-like MoS2/C sandwiched-structures for kinetic acceleration of polysulfide conversion in LiS batteries

Abstract

Graphene-like MoS₂/C composites with sandwiched-structures have been fabricated through a facile hydrothermal process and subsequent annealing treatment, which are used to modify separators for LiS batteries. The sandwiched carbons could not only generate fast electronic conducting channels between MoS₂ layers to endow MoS₂/C with high conductivity, but also prevent MoS₂ layers from re-stacking to obtain few- or single-layered MoS₂ with large amounts of active-sites for polysulfide adsorption and electro-catalysis. Therefore, the MoS₂/C composites could effectively promote the polysulfide conversion and Li₂S deposition, and the MoS₂/C modified polypropylene (MoS₂/C@PP) separators could greatly prohibit the polysulfide shuttling to enhance the electrochemical performances of LiS batteries. The LiS batteries equipped with MoS₂/C-3@PP separators at an optimized MoS₂ content deliver a high reversible capacity of 1262 mAh g⁻¹ at the 1st cycle and outstanding cycling stability with 791, 763 and 722 mAh g⁻¹ after 100 cycles at 0.2C, 0.5C and 1C, respectively. Furthermore, the MoS₂/C-3@PP separators could help the LiS pouch cells possessing high-areal-loading S/C cathodes and lean electrolytes to exhibit better electrochemical performances. These encouraging results suggest that the sandwich-structured composites constructed by graphene-like transition-metal dichalcogenides (TMDs) and carbon layers could be a type of promising catalyst for advanced LiS batteries.