Double-shelled hollow carbon sphere with microporous outer shell towards high performance lithium-sulfur battery

Abstract

To suppress the dissolution of polysulfides and maintain a high sulfur utilization of lithium-sulfur (Li-S) batteries, double-shelled hollow carbon sphere with a microporous outer carbon shell (m-DSHCS) is designed and fabricated as an efficient sulfur host. Specially, the m-DSHCS with an outer microporous carbon shell and foam-like conductive carbon links is an ideal sulfur host. The foam-like carbon links between the shells and inside the hollow structure can not only provide enough space for sulfur loading and volume expansion, but also facilitate fast electron transfer and Li+ diffusion. Additionally, the outer microporous carbon shell can also serve as an efficient physical barrier to suppress the diffusion of sulfur species derived from inner hollow carbon sphere. When used as cathode material for Li-S batteries, the m-DSHCS/S electrode delivered an outstanding reversible capacities (capacity fading of 0.16% per cycle at 0.2C after 200 cycles and 0.07% per cycle at 1C after 1000 cycles) and superior high-rate capabilities (900 mAh g−1 at 1C and 800 mAh g−1 at 2C) than that of graphene wrapped hollow carbon sphere/sulfur (rGO@HCS/S) electrode (100 cycles at 0.2C with 0.54% capacity fading per cycle, 670 mAh g−1 at 1C and 540 mAh g−1 at 2C).