In situ self-assembled NiS2 nanoparticles on MXene nanosheets as multifunctional separators: Regulating shuttling effect and boosting redox reaction kinetics of lithium polysulfides

The notorious shuttling effect and sluggish redox kinetics towards lithium polysulfides (LiPSs) seriously hinder the practical application of lithium-sulfur (Li-S) batteries. The development of a multifunctional separator, as cooperator of trapper-catalyst-conductor, is deemed to be an efficient and feasible solving strategy. Herein, the NiS2/MXene nanocomposites with mesoporous structures were synthesized by the hydrothermal reaction, in which 0D ultrafine NiS2 nanoparticles were in situ self-assembled on 2D conductive MXene nanosheets. The NiS2/MXene nanocomposites were then modified on PP separators to form a thin layer of 8 μm in the Li-S batteries, which exhibit the significant characteristics of capture and conversion of LiPSs, as well as highly-efficient transferring pathways of electron/Li+ via the synergetic effect of NiS2 and MXene from their strong chemisorption abilities, rich catalyzing active sites, and high electron conductivity, accelerating to the redox reaction kinetics of LiPSs. Consequently, these Li-S batteries by using the modified PP separators show a high reversible capacity of 805.1 mAh g-1 at 0.2 C after 200 cycles. Even at 2 C, it still exhibits a low capacity decay of 0.038 % per cycle after long-term stable 1000 cycles. This work proves that the developing multifunctional separators are efficient strategies for high performance Li-S batteries.