BC6N as a promising sulfur host material for lithium-sulfur batteries

High Adsorption energy between BC6NA and the substrates. [Display omitted] •Three types of B and N co-doped graphenes are studied as anchoring materials.•BC6NA exhibits excellent anchoring performance, which is superior to several similar doping systems.•BC6NA can improve electronic conductivity and reduce dissociation energy of the Sulfur cathode. Lithium-sulfur batteries (LSBs), which have six times the energy density of traditional lithium-ion batteries, are favorable candidates for the power system of next-generation electric vehicles, however, the sulfur cathode of lithium-sulfur batteries currently suffers from poor capacity retention and bad cycle performance. In this work, we study anchoring properties of B and N co-doped graphene by using density functional theory computations. Three doping configurations are considered and named as the adjacent (BC6NA), meta (BC6NM) and para (BC6NP) dopping, respectively. BC6NA has the best anchoring performance, as it has a strong absorption energy for the three clusters Li2S4 (1.20 eV), Li2S6 (1.51 eV) and Li2S8 (1.81 eV), while both BC6NM and BC6NP have a relatively worse anchoring performance due to their weak physical adsorption, especially for the Li2S4 cluster. Moreover, after adsorption the conductivity of the BC6NA is enhanced and the dissociation energy of the cluster is reduced, which further improve the performance of LSBs. This indicates that monolayer BC6NA is a promising sulfur host material for LSBs with a good anchoring performance.