A flame retardant separator modified by MOFs-derived hybrid for safe and efficient Li-S batteries

In this work,we have successfully prepared a novel separator modified with N,S co-doped carbon framework(named NSPCF)with confined CoS_(2) nanoparticles and rooted carbon nanotubes material(named NSPCF@CoS_(2))to apply for high-performance Lithium-Sulfur batteries(Li-S batteries).Robust carbon structure with large specific surface can act as a physical barrier and possess physical adsorption effect on lithium polysulfides(LiPSs).In addition,highly-conductive carbon can improve integral conductivity,leading to the fast charge transport and reaction kinetics.Also,doping heteroatoms could form more active sites to adsorb LiPSs strongly so that modified separator could inhibit the shuttle effect effectively.Moreover,the presence of CoS_(2) further enhances the ability of modified separator to trap LiPSs owing to the Lewis acid-base action.As a result,the NSPCF@CoS_(2)@C-150 battery can deliver initial discharge capacities of 863.0,776.2,649.1 and 489.4 mAh g^(-1) at 0.1,0.5,1 and 2C with a high sulfur loading of 2.04 mg cm^(-2),respectively.Notably,when turning the current density back to 0.1 C,its discharge capacity can recover to 1008.7 mAh g^(-1).In addition,the modified separators exhibit outstanding capacities to restrain the growth of lithium dendrites.It is noteworthy that the flame retardant performances of Li-S batteries are improved dramatically owing to the novel structures of modified separators.This rationally designed separator endows Li-S batteries with higher safety and excellent electrochemical performances,providing a feasible strategy for practical application of Li-S batteries.

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 CoS_(2) nanoparticles(CoS_(2)/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.