Structural screening and descriptor exploration of black phosphorus carbide supported bifunctional catalysts for lithium-sulfur batteries.

Developing optimal catalysts, to suppress the shuttling of lithium polysulfides (LiPSs), and serving as bifunctional catalyst with fast discharge-charge reaction kinetics, are essential for the practical applications of Li-S batteries. Herein, based on density functional theory (DFT) calculations, single-atom catalysts formed by embedding 3d transition metals (TMs) into the nitrogen doped defective black phosphorus carbide (TM@N-CP) are systematically explored toward fast kinetics in Li-S batteries. Remarkably, V@N-CP, possessing excellent metallic features, outstanding structural stability, suitable binding and easy diffusion for LiPSs, eventually stands out as the promising bifunctional electrocatalyst. Our results unveil that d-p orbital hybridization between transition metal (TM) atom and sulfur species is accompanied by weakened surrounding Li-S bonds. Consequently, the formation of TM-S bonds not only ensures inhibition of LiPSs shuttling, but also promotes the dissociation of LiS. With the analysis of correlation map of key parameters, the ICOHP values of TM-S bonds and adsorption energy of *LiS are identified and proposed as descriptors for fast screening towards fast reaction kinetics. Our work shows a feasible strategy for the rational design and retrieval of the decisive feature of active catalysts for Li-S batteries.