▎ 摘　　要

A nitrogen-doped carbon nanotubes/graphene (NCNTs-G) composite as the sulfur host for a lithium-sulfur battery has been fabricated by in situ growth of NCNTs on graphene in a onestep nickel-catalyzed thermolysis. The graphene sheet can function as a robust support to anchor NCNTs so that the specific surface area of the composite can be increased and the charge-transfer resistance is reduced. These features, together with the high N-doping level, impart the NCNTs-G/S cathode a high utilization of sulfur, and the polysulfide shuttle effect can be effectively inhibited by both physical confinement and chemical adsorption. Therefore, the NCNTs-G/S cathode shows high reversible capacities of 1484 mA h g(-1) and 985 mA h g(-1 )at the current rate of 0.1 C and 0.5 C, respectively. It also exhibits a good cycling stability; 82% of its initial capacity is retained after 150 cycles at 0.5 C, and a very small capacity decay rate of 0.06% per cycle resulted in 400 cycles at 1 C. Based on the above structural characteristics and battery performance results, the NCNTs-G/S is a promising cathode for a high-performance Li S battery.