Reduced graphene oxide-hollow carbon sphere nanostructure cathode material with ultra-high sulfur content for high performance lithium-sulfur batteries

•A rGO-HCS composite loading ultra-high sulfur content of 90 wt% was prepared.•The high sulfur content offers high gravimetric and volumetric energy density.•The thick electrode with 3 mg cm−2 sulfur shows high energy density and good cycling stability.•The rGO-HCS nanostructure design promises excellent performance with high sulfur loading.

Lithium-sulfur (Li-S) batteries have been regarded as promising next generation rechargeable energy storage system, due to the high theoretical specific capacity and energy density. However, the low sulfur content in the cathode electrode greatly decrease the practical energy density of the Li-S batteries. Herein, we report a reduced graphene oxide-hollow carbon sphere (rGO-HCS) composite to encapsulate sulfur with high sulfur contents from 70 to 90 wt% as sulfur cathode. The rGO-HCS/S composite loading 90 wt% sulfur delivers the highest energy density of 1281 Wh kg−1 based on the mass of the whole cathode, even at a high sulfur areal density of 3 mg cm−2, it could still reach a high discharge capacity of 860 mA h g−1 (corresponding to 1300 Wh kg−1 based on mass of the whole cathode) and obtain a high capacity retention of 77% after 78 cycles.These results indicate the great potential of the rGO-HCS nanostructure as promising sulfur host loading high content of sulfur with high gravimetric and volumetric energy density.

Graphical abstractWe report a rGO-HCS composite to encapsulate sulfur with high sulfur contents from 70 to 90 wt% as sulfur cathode. The rGO-HCS/S composite loading 90 wt% sulfur delivers a high discharge capacity of 860 mA h g−1 (corresponding to 1300 Wh kg−1 based on mass of the whole cathode) and obtains a high capacity retention of 77% after 78 cycles at a high sulfur areal density of 3 mg cm−2.The results indicate the great potential of the rGO-HCS nanostructure as promising sulfur host loading high content of sulfur with high gravimetric and volumetric energy density.Figure optionsDownload full-size imageDownload as PowerPoint slide