Three-dimensional graphene-wrapped porous carbon/sulfur composite for cathode of lithium–sulfur battery

Lithium–sulfur battery with high theoretical capacity becomes the subject of recent attention. Its commercial progress is impeded by its poor electrical conductivity and high dissolubility of intermediate products in organic electrolyte. In the present work, we report a novel three-dimensional graphene-wrapped porous carbon (3D-G) to accommodate sulfur, which consists of outside highly stable interconnected graphene-like sheets and inner activated porous carbon. The 3D-G was synthesized from cheap polyacrylic acid cation-exchange resin, which introduces nickel ions as catalysts in the carbonization process, as a cost effective, facile and simple method. This 3D-G showed hierarchical pores: 0.7 nm micropores and macropores, providing a large specific surface area of 1375.08 m2 g−1. Benefiting from this unique structure, the 3D-G performed well as host materials to achieve a high sulfur content (75.4 wt%). Such a 3D-G@S composite exhibits capacity-fading rate as low as 0.28% per cycle over 100 cycles at 0.1 C, and good cyclability at various cycling rates (0.1–1 C).