Regulating the coordination environment of single atom catalysts anchored on CN monolayer for Li-S battery by first-principles calculations.

Owing to the extremely high theoretical specific capacity and energy density, the catalytic materials of lithium-sulfur (Li-S) batteries are widely explored. The "shuttle effect", poor electrode conductivity, and slow charge-discharge reaction dynamics are some of the key issues that have seriously hampered their commercialization process. Herein, based on the density-functional-theory (DFT), the catalytic performances of a series of single-atom catalysts (SACs) designed by regulating the N-content around coordination center in CN (TM@NC/NC/N-CN (TM = Ti, V, Fe, Co, Ni)), are systematically analyzed and evaluated. Among all the constructed SACs, Ti-centered configurations with fewer d electrons, especially for the Ti@NC-CN, have the remarkable catalytic effect in improving the electron conductivity, trapping soluble polysulfides and accelerating the redox reaction. The in-depth mechanism indicates that the interaction between d orbital of Ti, mainly the splitting [Formula: see text] , and p orbital of S is the key factor for achieving high-effective adsorption. More importantly, the integral value of crystal orbital Hamiltonian population (ICOHP) of the Li-S bond in the adsorbed LiS can serve as an excellent descriptor for evaluating the overall catalytic ability of substrates. Our work has vital guiding significance for designing high-performance SACs of Li-S batteries.