A one-pot synthesis of hetero-Co9S8-NiS sheets on graphene to boost lithium-sulfur battery performance

Lithium-sulfur batteries have received extensive attention owing to abundant sulfur resources and high energy density. However, their practical applications are hindered by the low utilization of sulfur due to its poor electronic conductivity, the shuttle effect and the sluggish redox kinetics of soluble lithium polysulfides (LiPSs), thus resulting in severe fading capacity. In study, graphene decorated with hetero-Co9S8-NiS sheets (BMS-G) was employed as a host material to support S in cathodes. The hetero-Co9S8-NiS effectively confined numerous LiPS species by chemisorption, and expedited the redox kinetics of LiPS. Consequently, the cathode with the BMS-G composite delivered high reversible specific capacities of 1142.9 mA h g(-1) at 0.2 C and 705.8 mA h g(-1) at 2 C, and had an excellent cycling stability (only 0.031% capacity fading per cycle over 800 cycles at 1 C was observed).