Nanostructured porous carbons derived from nitrogen-doped graphene nanoribbon aerogels for lithium-sulfur batteries.

A nanostructured porous carbon (NPC) is prepared by using a facile physical activation method, with nitrogen-doped graphene nanoribbon aerogel and carbon dioxide as a precursor and an activating agent, respectively. The morphology, porosity parameters, and chemical properties of the as-prepared NPC have been revealed by using various characterization methods, including scanning electron microscopy, nitrogen sorption analysis, and X-ray photoelectron spectroscopy (XPS). The NPC with a moderate nitrogen content (5.1 atom % on the basis of XPS analysis) retains the sponge-like morphology of nitrogen-doped graphene nanoribbon aerogel, shows a high Brunauer-Emmett-Teller specific surface area (1380 m g), and possesses hierarchically porous structures. Based on its excellent properties such as high porosity, conductive network, and nitrogen-doping, NPC as a superior host is used to fabricate a sulfur-based cathode for lithium-sulfur batteries. The high specific surface area and the pore volume of NPC not only allow uniform distribution of sulfur in an amorphous form, but also help to alleviate the shuttle effect of polysulfides. As a result, the as-obtained cathode exhibits a good rate capability and cycling stability.