ZIF-8 derived hollow carbon to trap polysulfides for high performance lithium-sulfur batteries.

Lithium-sulfur batteries (LSBs) have been considered very promising due to their high theoretical energy density and low cost. However, the undesirable shuttle effect with solid discharge product Li2S, greatly impedes its market penetration. Functional elements associated conductive carbon materials are beneficial to control the shuttle effect and reactivate the Li2S leading to long term cycling performance of LSBs. Herein, we report Zinc (Zn) and Nitrogen (N) associated ZIF-8 derived hollow carbon (ZHC) as a promising separator coating for LSBs to control the shuttle effect of LSBs. The hollow area in the ZHC is identified to be around 100 nm with a carbonized outer surface thickness of approximately 50 nm. The presence of Zn and N in the nano hollow structure of the carbon helps to mitigate the PS diffusion in LSBs. The hollow interior of the carbon acts as PS pocket to physically capture the PS and in addition Zn and N chemically attract the PS through polar-polar and metal sulfide interactions to further diffuse from cathode to anode during charging and discharging. The ZHC with its unique architecture and functional groups has been very promising to enable initial specific capacity (S.cap) of 842 mAh g-1 at 4.80 mg cm-2 and long run till 400 cycles, which is considerably higher in comparison to the cycling performance of parent ZIF-8.