Ferroconcrete-Like Helical Carbon Nanotube/Reduced Graphene Oxide Heterostructure 3D Networks as Sulfur Hosts for High-Performance Li-S Batteries

Abstract

A novel helical Carbon nanotubes (HCNT) network with a reduced graphene oxide (rGO) coating was designed and fabricated through a synergistic self-assembly and sulfuration strategy for use as an effective sulfur (S) host. A ferroconcrete frame structure with a hierarchical 3D nanostructure composed of 1D HCNT and 2D rGO nanosheets was obtained. The rGO wraps around the HCNT to form a heterostructure and provide an apparent coating that protects S. HCNT in the composite is boosted to create a 3D network architecture and reinforce the structural stability. Moreover, the heterostructures and rGO coatings, which are rich in wrinkles, can greatly minimize direct contact between the polysulfide and electrolyte; they also provide an abundance of active sites and boundary defects. Furthermore, the 3D interconnected structure creates effective ion diffusion channels and allows effective trapping of S and Li polysulfides. When used as a cathode, the HCNT/rGO/S cathode exhibits a high initial specific capacity of 1,196 mAh g−1 at 0.1 C. The capacity decay rate of the HCNT/rGO/S is only 0.075% per cycle after cycling for 200 times at a rate of 0.1 C. This unique hybrid HCNT/rGO/S electrode design may motivate the development of other high-performance electrodes with excellent electrochemical properties.