Exploring the anchoring mechanism of polyselenides on C 4 N 3 monolayer as selenium host material: A first-principles study

Lithium-Selenium (Li Se) batteries encounter several challenges, including low active Se utilization, slow kinetics, volume expansion during charging and discharging, and the shuttle effect of high-order polyselenides. The development of high-performance selenium host materials is essential to suppress the shuttle effect of high-order polyselenides and increase the Li 2 Se conversion rate. In this regard, a theoretical design of C 4 N 3 monolayer as the potential host material for Li Se batteries is proposed through first-principles calculations. The analysis of the lowest energy configuration, binding energy, and charge transfer shows that the C 4 N 3 monolayer can inhibit the solubilization of high-order polyselenides by creating the strong Li N bonds. Compared to conventional electrolytes, the polyselenides are more readily adsorbed on the surface of C 4 N 3 monolayer, which effectively inhibits the shuttling of high-order polyselenides and improves cycling stability. The catalytic role of the C 4 N 3 monolayer was evaluated in terms of the reduction pathway of Se 8 and decomposition barrier of Li 2 Se. The results showed that C 4 N 3 could promote the formation and decomposition of Li 2 Se molecule during the discharge and charge processes and improve the utilization of selenium active material. Our current study not only offers a theoretical understanding of the anchoring and catalytic roles of C 4 N 3 monolayer but also provides valuable insights into the general principles for investigating C 4 N 3 -based host materials for Li Se batteries.