A 3D nanostructure of graphene interconnected with hollow carbon spheres for high performance lithium-sulfur batteries

To better suppress the capacity decay over cycling and improve the electrical insulation of the sulfur cathode for lithium-sulfur (Li-S) batteries, we designed a novel three-dimensional nanostructure of graphene interconnected with hollow carbon spheres (3D rGO-HCS) as the sulfur host. The 3D rGO-HCS nanostructure was first prepared via a hydrothermal self-assembly method followed by carbonization and etching of the SiO2 core, then sulfur was impregnated into the nanostructure by an in situ solution deposition method to obtain the S@rGO-HCS cathode. The as-prepared cathode material delivers a high discharge capacity of similar to 770 mA h g(-1) at 4 C rate. More importantly, it has a high capacity retention of 93.9% after 100 cycles and demonstrates a low capacity-decay rate of 0.052% per cycle after 400 cycles at 0.5 C rate. The superior comprehensive electrochemical performance of the S@rGO-HCS cathode is ascribed to the synergic effects from the 3D graphene-network design, including fast electron and ion transportation, efficient confinement of polysulfide dissolution and shuttling and successful maintenance of structural integrity.