Rational design of a cobalt sulfide nanoparticle-embedded flexible carbon nanofiber membrane electrocatalyst for advanced lithium-sulfur batteries.

Both the sluggish redox kinetics and severe polysulfide shuttling behavior hinders the commercialization of lithium-sulfur (Li-S) battery. To solve these obstacles, we design a cobalt sulfide nanoparticle-embedded flexible carbon nanofiber membrane (denoted as CoS2@NCF) as sulfiphilic functional interlayer materials. The hierarchically porous structure of carbon nanofiber is conducive to immobilizing sulfur species and facilitating lithium-ion penetration. Moreover, electrocatalytic CoS2nanoparticles can significantly enhance the catalytic effect, achieving favorable adsorption-diffusion-conversion interface of polysulfide. Combined with these synergistic features, the assembled Li-S cell with CoS2@NCF interlayer exhibited a great discharge capacity of 950.9 mAh g-1with prolonged cycle lifespan at 1 C (maintained 648.1 mAh g-1over 500 cycles). This multifunctional interlayer material used in this contribution provides an advanced route for developing high-energy-density Li-S battery.