Lithium‐sulfur (Li−S) batteries have been attracting growing interest in the past few years due to their outstanding theoretical energy density, but the lower cycle performance and especially the migration of polysulfides significantly inhibited its applicability. Herein, we propose a novel strategy for trapping lithium polysulfides (LiPSs) by combining nitrogen‐deficient graphitic carbon nitride (g‐C3N4–x) and carbon nanotubes (CNTs) to form a functional interlayer between the separator and sulfur cathode in Li−S batteries. The defect chemistry present in g‐C3N4–x not only improves the chemical affinity toward polysulfides but also catalyzes the polysulfide reactions. Besides, the interwoven scaffold‐like CNT network in the g‐C3N4–x/CNT composite accelerates the process of electron transfer. Based on this synergistic effect, the cells with g‐C3N4–x/CNT‐modified separators showed a remarkable discharge capacity of 1128 mAh g−1 at 0.2 C, and a reversible capacity of 774 mAh g−1 after 100 cycles, indicating an efficient strategy toward high‐performance modified separators.
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 CoS2 nanoparticles 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−1 with prolonged cycle lifespan at 1 C (maintained 648.1 mAh g−1 over 500 cycles). This multifunctional interlayer material used in this contribution provides an advanced route for developing high-energy-density Li–S battery.
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