9 / 2017-12-20 09:20:10

Carbon Nanotubes Grown in situ on Graphene Nanosheets as Efficient Sulfur Host for Lithium-Sulfur Batteries

Graphene Nanosheets,Lithium-Sulfur Batteries,Carbon Nanotubes

Lithium–sulfur (Li-S) batteries have been considered as a promising candidate for next-generation electrochemical energy-storage technologies because of their overwhelming advantages in energy density. Suppression of the polysulfide dissolution while maintaining a high sulfur utilization is the main challenge for Li–S batteries. Here, we have designed and synthesized carbon nanotubes grown in situ on graphene nanosheets (GN@CNTs) by mixing graphene oxide with dimethylimidazole and cobalt nitrate as a conceptually new sulfur host for Li–S batteries. Specifcally, GN@CNTs with stable in-situ structures and nitrogen doping, not only enhance the performance of rapid charge transfer, but also provide sufficient self-functionalized surfaces for chemically bonding with polysulfides to suppress their outward dissolution. As a result, the GN@CNTs /S composite cathode material remains a high discharge capacity of 394 mAh g-1 after 700 cycles at a current density of 1 C (based on the mass of sulfur); this corresponds to a good capacity retention of 53.6% and capacity fading rate of 0.066% per cycle.