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 ~ 1.41 eV and 0.55 ~ 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.