Unveiling the Anchoring and Catalytic Effect of Co@CN 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@CN 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@CN 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@CN 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 CN monolayer, and the semi-metallic characteristics of the Co@CN monolayer are maintained after the adsorption of LiSe ( = 1, 2, 4, 6, 8) or Se clusters, which is advantageous for the utilization of active selenium material. The crucial catalytic role of the Co@CN monolayer is evaluated by examining the reduction pathway of Se and the decomposition barrier of LiSe, and the results highlight the capability of Co@CN monolayer to enhance the utilization of selenium and promote the transition of LiSe. Our present work could not only provide valuable insights into the anchoring and catalytic effect of Co@CN monolayer, but also shed light on the future investigation on the high performance CN-based host materials for Li-Se batteries.