Hierarchical Rambutan-Like CNTs-Assembled N-Co-C@rGO Composite as Sulfur Immobilizer for High-Performance Lithium-Sulfur Batteries

The design of efficient sulfur-host materials is of great significance to enhance the conductivity of lithium-sulfur (Li-S) batteries and inhibit the shuttle effect of polysulfides. Hence, a nitrogen and cobalt co-doped graphitized carbon (N-Co-C)-coated reduced graphene oxide (rGO) with plenty of carbon nanotubes (CNTs) was rationally designed. The composite had abundant multiple adsorptive and electrocatalytic sites to provide strong chemical trapping for polysulfides and simultaneously propel their electrochemical kinetics. The densely grafted small-diameter CNTs could shorten the ion-diffusion pathways and maintain the structural stability of the electrode materials. Meanwhile, abundant pore structures could provide enough volume for sulfur impregnation and physical adsorption of polysulfides. Owing to these favorable features, the as-prepared rambutan-like S/N-Co-C@rGO-CNTs (S/NCoC@G-CNTs) composite demonstrated excellent electrochemical performance with a high initial specific capacity of 1225.8 mAh g(-1) at 0.2 C and high rate performance of 632.5 mAh g(-1) at 5.0 C and possessed decent areal capacity under high raised sulfur loading of up to 5 mg cm(-2).