Functional Interlayer with Highly Dispersed Co_1–XS Embedded in N‑Doped Carbon Spheres as Trapping-Catalyst Nanoreactors for Advanced Lithium–Sulfur Batteries

Shuttle effect and sluggish conversion kinetics of lithium polysulfides (LiPSs) have become the bottleneck in lithium–sulfur (Li-S) batteries. Herein, hierarchically porous nitrogen-doped carbon spheres with highly dispersed Co_1–XS nanoparticles (Co_XS-NC) as a trapping-catalyst interlayer for high-performance Li-S batteries is proposed. The nitrogen-doped hierarchically porous carbon spheres generate high specific surface area and large pore volume which provide adequate sites for the adsorption of LiPSs and facilitate the good dispersion of Co_1–XS nanoparticles. Nitrogen doping and Co_1–XS modification improve the polarity, which promotes the adsorption and rapid conversion of LiPSs. The exceptional properties of the Co_XS-NC interlayer are confirmed with an exceeding low delay rate of 0.031% per cycle after 1000 cycles at 0.5 C and an outstanding retention rate of 78.7% over 300 cycles at 2 C. Even employed with high sulfur loading of 6 mg cm^–2, it also delivers a high initial areal capacity of 5.74 mAh cm^–2 at 0.1 C with capacity retention of 4.58 mAh cm^–2 after 100 cycles. This research opens up possibilities for the construction of multifunctional interlayers for use in commercial Li-S batteries.