The formation of strong-couple interactions between nitrogen-doped graphene and sulfur/lithium (poly)sulfides in lithium-sulfur batteries

A lithium-sulfur battery with a very high theoretical energy density (2600 Wh kg(-1)) is one of the most promising candidates for next-generation energy storage devices. However, there are still many problems impeding the practical use of lithium-sulfur batteries, including the 'shuttle effect' and irreversible loss of active materials. Enhancing the interfacial interaction between the carbon hosts and the sulfur-containing guests by rational nitrogen doping is an effective route. First principle calculations were performed to illustrate the adsorption behavior between sulfur/lithium (poly) sulfides and pristine/nitrogen-doped graphene nanoribbons with different edge structures. N-dopants on doped graphene nanoribbon in pyrrolic and pyridinic forms donated extra binding energies of 1.12 similar to 1.41 eV and 0.55 similar to 1.07 eV, respectively. Quaternary nitrogen enriched on the edge can benefit from the adsorption of active materials. Compared with pristine graphene nanoribbon, nitrogen-doped graphene nanoribbons exhibited strong-couple interactions for anchoring sulfur-containing species, achieving high stability and reversibility, which was consistent with experimental findings. These results shed light on the cathode design of lithium-sulfur batteries and on the potential to understand host-guest interactions in other energy storage systems.