Engineering multi-chambered carbon nanospheres@carbon as efficient sulfur hosts for lithium-sulfur batteriesElectronic supplementary information (ESI) available. See DOI: 10.1039/c8ta02911c

Despite their advantages of high theoretical capacity and energy density, lithium-sulfur (Li-S) batteries still suffer from poor electrochemical performance resulting from the accelerated shuttle effect of polysulfides and the intrinsically low electroactivity of elemental sulfur. Herein, we report an ideal core-shell sulfur host material based on core-shell carbon encapsulated multi-chambered carbon nanospheres (MCCN@C) for Li-S batteries. The hierarchical and micro-mesoporous core in MCCN@C can allow a high sulfur loading (83.1 wt%) and serve as the physical barrier to block the polysulfide dissolution, and the carbon shell can provide additional physical confinements for improving the retention of soluble polysulfides. Moreover, the well-designed conductive networks of the MCCN@C material interconnected by carbon chambers can promote fast electron transfer and electrolyte penetration. In Li-S batteries, MCCN-S@C composite cathodes deliver significantly enhanced electrochemical performance with a high reversible capacity of 1163 mA h g −1 at 0.2C after 100 cycles, remarkable rate capability (626 mA h g −1 at 5.0C) and ultrahigh long-term cycle stability at high rates (651 mA h g −1 after 1000 cycles at 2.0C with 0.032% capacity decay per cycle). More importantly, the MCCN@C-S composite cathode with 3.6 mg cm −2 sulfur also delivers a high and stable electrochemical performance over 200 cycles. An optimized structure of core-shell carbon encapsulated multi-chambered carbon nanospheres (MCCN@C) was developed for a Li-S host material.