Bi-structural fibers of carbon nanotube coated with nitrogen/oxygen dual-doped porous carbon layer as superior sulfur host for lithium-sulfur batteries

Lithium-sulfur batteries are one of the most promising secondary energy storage systems. However, their fast capacity fading and low reaction kinetics still remain a challenge. In the present study, a unique bi-structural porous carbon hybrid of fibers with carbon nanotube as core and nitrogen/oxygen dual-doped porous carbon as coating layer is synthesized by a self-assembly approach. The one-dimensional (1D) hybrid has large surface area, high porosity, rich nitrogen/oxygen dual-doping and high conductivity, which is admirable as sulfur host for lithium-sulfur battery cathodes. This novel structural carbon host enables the sulfur cathode a significant cyclic stability and superior rate capability. With a sulfur loading as high as 75 wt%, the sulfur cathode achieves an initial capacity of 1110 mAh g−1 and a capacity of 684 mAh g−1 retains after 200 cycles at 0.2 C. This work offers a new structural 1D porous carbon host and its fabrication method for high efficiency sulfur cathodes.