Unveiling the anchoring and catalytic effect of Co@C 3 N 3 monolayer as a high-performance selenium host material in lithium-selenium batteries: a first-principles study.

Suppressing the shuttle effect of high-order polyselenides is crucial for the development of high-performance host materials in lithium-selenium (Li-Se) batteries. Using first-principles calculations, the feasibility of Co@C 3 N 3 monolayer as selenium cathode host material for Li-Se batteries is systematically evaluated from the aspects of binding energy, charge transfer mechanism, and catalytic effect of polyselenides in the present work. The Co@C 3 N 3 monolayer can effectively prevent the solubilization of high-order polyselenides with large binding energy and charge transfer resulting from the synergistic effect of Li-N and Co-Se bonds. The polyselenides are inclined to adsorb on the surface of Co@C 3 N 3 monolayer instead of interacting with the electrolytes, which effectively inhibits the shuttling of high-order polyselenides and improves cycling stability. The cobalt participation improves the conductivity of C 3 N 3 monolayer, and the semi-metallic characteristics of the Co@C 3 N 3 monolayer are maintained after the adsorption of Li 2 Se n ( n = 1, 2, 4, 6, 8) or Se 8 clusters, which is advantageous for the utilization of active selenium material. The crucial catalytic role of the Co@C 3 N 3 monolayer is evaluated by examining the reduction pathway of Se 8 and the decomposition barrier of Li 2 Se, and the results highlight the capability of Co@C 3 N 3 monolayer to enhance the utilization of selenium and promote the transition of Li 2 Se. Our present work could not only provide valuable insights into the anchoring and catalytic effect of Co@C 3 N 3 monolayer, but also shed light on the future investigation on the high performance C 3 N 3 -based host materials for Li-Se batteries.