Zn-N Codoped Carbon Nanofiber Interlayer for Anchor and Catalysis of Polysulfides in Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries have aroused extensive attention owing to the high theoretical capacity and energy density; however, their practical applications are impeded by the insulation of sulfur and lithium sulfides and the shuttle effect of lithium polysulfides (LiPSs). Here, zinc-nitrogen codoped carbon (ZnNC) nanofibers with pea-shaped voids were fabricated as an interlayer of Li-S batteries. It was found that the ZnNC nanofibers can anchor LiPSs and catalyze their redox conversion effectively. The cross-linked ZnNC nanofiber interlayer acting as an upper current collector can enhance the electron transfer and accelerate the lithium ion diffusion. The combined effects of the addition of the ZnNC nanofiber interlayer endow the Li-S batteries with high capacity, high-rate performance, and long cycle stability. The initial capacity is 1198.5 mAh g(-1) at 0.5 C for the cell with a sulfur loading of about 1.0 mg cm(-2). After 500 cycles at 1 C, a capacity of 694.1 mAh g(-1) is retained with a low capacity fading of 0.073% per cycle. When the sulfur loading is 6.19 mg cm-2, the capacity reaches 754.8 mAh g(-1) after 100 cycles at 0.2 C.