Construction of multifunctional and flame retardant separator towards stable lithium-sulfur batteries with high safety

The cell with flame retardant separator shows promoted rate property as well as inhibited dendrites growth. [Display omitted] •A MOFs-derived hierarchical composite (NSPCFS@CoS2) modified separator is designed.•This designed separator possesses markedly improved flame retardancy.•The effective suppression on shuttle behavior of polysulfides is realized.•The suppressed growth of lithium dendrites corroborates the higher battery safety. Considering the unprecedented advantages such as superb theoretical capacity, high energy density and low cost, lithium-sulfur batteries (LSBs) have been under spotlight in past several years. Nevertheless, limited by its intrinsic drawbacks of highly insulating character, serious shuttle effect and lithium dendrites growth, there is still a long way from large-scale application of LSBs. Here, a polyacrylonitrile@metal organic frameworks (PAN@MOFs) composite-derived heteroatoms doped carbon@encapsulated CoS2 nanoparticles (NSPCFS@CoS2) modified separator is designed to surmount these issues. Notably, the modified separator shows improved flame retardancy. By using this separator, the effective suppression on shuttle behavior as well as boost in polysulfides conversion kinetics are realized, which can be assigned to the integrative superiorities of conductive carbon fiber network, electrocatalytic activity, polar-polar interaction and Lewis acid-base interaction. The cell with modified separator shows an initial discharge capacity of 1140.7 mAh g−1. After running for 100 cycles, a high capacity of 631.6 mAh g−1 is retained. Notably, the inhibited growth of lithium dendrites is also obtained, indicating the promoted battery safety. Overall, this work may provide useful inspirations for the utilization of MOFs-derived hierarchical composite in implementing safer high-performance LSBs.