Unraveling the superior anchoring of lithium polyselenides to the confinement bilayer CN: an efficient host material for lithium-selenium batteries.

Carbonaceous materials with pores or bilayer spaces are a kind of potential host material to confine polyselenide diffusion and mitigate the shuttling effect. In the present work, a theoretical design of bilayer CN (bi-CN) as an efficient host material for lithium-selenium (Li-Se) batteries was explored by first-principles calculations. AA- and AB-stacking bilayer CN could alleviate the dissolution of high-order polyselenides through a synergistic effect of physical confinement and strong Li-N bonds. Lithium polyselenides prefer to anchor on AA- and AB-stacking bilayer CN instead of the commonly used electrolytes, showing their capabilities in suppressing the shuttle effect. Charge transfer occurs from Se and LiSe molecules (LiPSes) to AA- and AB-stacking bilayer CN, giving rise to the formation of strong Li-N bonds. The AA- and AB-stacking LiPSes@CN systems possess high electrical conductivities, which is beneficial for high electrochemical performance. In addition, the reversible conversion mechanisms of LiSe in the AA- and AB-stacking bilayer CN are also investigated through the energy changes and decomposition reaction of the LiSe molecule, and the results indicate that AA- and AB-stacking bilayer CN facilitate the formation and decomposition of LiSe by decreasing the active energy barriers and improving the selenium utilization rates. Our present work could shed some light on a possible strategy for designing highly efficient bilayer host materials for high performance Li-Se batteries.