Transition metal embedded C2N with efficient polysulfide immobilization and catalytic oxidation for advanced lithium-sulfur batteries: A first principles study.

Developing highly efficient host materials to suppress the lithium polysulfides (LiPSs) shuttling and accelerate the Li 2 S conversion is essential for advanced lithium-sulfur (Li–S) batteries. In this work, based on first principles computations, we explored transition metal embedded C 2 N monolayers (M@C 2 N, M = Mn, Fe, Co, Ni, Cu) as host materials and catalysts for Li–S batteries. Our results show that M@C 2 N monolayers could prevent the LiPSs shuttling with strong adsorption energies towards LiPSs, due to the synergistic effect of M-S and Li–N bonds. Moreover, the presence of transition metal atoms in the C 2 N could improve its electric conductivity. On the whole lithiation process, all the adsorbed systems are still conductive, which is helpful to boost the sulfur utilization. Importantly, M@C 2 N monolayers could promote the Li 2 S decomposition and thus enhance the oxidation kinetics of Li 2 S back to sulfur. Among them, Co@C 2 N monolayer is the best host material, which possesses the largest adsorption energies with LiPSs and the lowest decomposition energy of Li 2 S. This work opens a new avenue for the development of host materials with excellent catalytic activity towards LiPSs, and also sheds light on M@C 2 N as superior cathode materials. [ABSTRACT FROM AUTHOR]