Designing of multifunctional and flame retardant separator towards safer high-performance lithium-sulfur batteries

Owing to unprecedented merits such as high theoretical capacity, superior energy density and low cost, lithium-sulfur batteries (LSBs) show a bright future both in scientific and industrial areas. Whereas, the inherent issues, including highly insulating character, undesired shuttle behavior and lithium dendrites growth, are seriously impeding its practical usage. Here, a metal-organic-frameworks (MOFs) derived N, S co-doped carbon nanotube hollow architecture confining with CoS₂ nanoparticles (CoS₂/NSCNHF) modified separator is designed to surmount these obstacles. Compared with Celgard separator, this designed separator shows obviously enhanced flame retardancy, giving 73.1% and 53.0% reductions in peak heat release rate and total heat release, separately. Concretely, its hollow structure, conductive feature, electrocatalytic activity and Lewis acid-base interaction enable the efficient inhibition on shuttle behavior as well as boost in polysulfides conversion kinetics. The cell with modified separator delivers a high discharge capacity of 1, 284.5 mAh·g^–1. After running for 100 cycles, a discharge capacity of 661.3 mAh·g^–1 is remained. Markedly, the suppression on lithium dendrites growth is also observed, manifesting the enhanced battery safety. Overall, this work may shed light on the effective usage of MOFs-derived hierarchical composite in achieving LSBs with high electrochemical performance as well as safety.