Reduced porous carbon/N-doped graphene nanocomposites for accelerated conversion and effective immobilization of lithium polysulfides in lithium-sulfur batteries

Highlights: • rPC-NG matrix was prepared by calcinations of PAN and ball milling of NG. • rPC alleviates volume variation and NG improves the conductivity of cathode. • The constructed rPC-NG matrix can be strong adsorbent and effective catalyst of LiPSs. • The rPC-NG/S cathode exhibits excellent cycling stability and rate performance. -- Abstract: Lithium sulfur (Li-S) batteries have been foreseen as the next generation energy storage device because of their high theoretical energy density. However, a low-cost, efficient and replicable way for mass producing suitable host materials that enable high-performance Li-S batteries is still a huge challenge. To tackle this issue, a rPC-NG composite was fabricated by mixing reduced porous carbon material (rPC) prepared from PAN fiber and N-doped graphene (NG) through a simple and scalable ball milling process. Herein, the rPC and NG immobilize sulfur via strong physical and chemical adsorption and inhibit the shuttle effect of lithium polysulfides (LiPSs) successfully. Importantly, such composite possesses a layered porous structure which can contribute to a high loading of sulfur, leading to the excellent conductivity, outstanding utilization rate and stability of adsorbed sulfur. The resultant rPC-NG/S cathode exhibits a stable cycling performance (503 mAh g⁻¹ at 0.5 C after 500 cycles and 770 mAh g⁻¹ at 0.2 C after 200 cycles) and high rate performance (540 mAh g⁻¹ at 2 C).