Li2S@C composite incorporated into 3D reduced graphene oxide as a cathode material for lithium-sulfur batteries

•Li2S@C composites are strongly embedded into 3D-rGO to form 3D-rGO-Li2S@C.•Double modifications (Top plus bottom) on Li2S nanoparticles is realized.•3D-rGO and outer coating improve the conductivity and inhibit the dissolution.•The electrochemical performance of 3D-rGO-Li2S@C is better than 3D-rGO-Li2S.

Surface conductive engineering on Li2S is critical for construction of advanced cathodes of lithium-sulfur batteries. Herein, we construct a high-performance Li2S-based composite cathode with the help of three-dimensional reduced graphene oxide (3D-rGO) network and outer carbon coating. Typically, the Li2S@C particles are uniformly embedded into 3D-rGO to form a binder-free 3D-rGO-Li2S@C cathode by the combination of a liquid solution-evaporation coating and PVP (Polyvinyl Pyrrolidone) carbonization. The 3D-rGO-Li2S@C cathode exhibits a high initial discharge capacity of 856 mAh g−1 at 0.1C, superior cycling stability with a capacity of 388.4 mAh g−1 after 200 cycles at 1C, corresponding to a low capacity fading rate. It is demonstrated that the outer conductive coating is effective and necessary for electrochemical enhancement of Li2S cathodes by improving electrical conductivity and prohibiting polysulfide from shuttling during cycling.