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@N4-CP) are systematically explored toward fast kinetics in Li-S batteries. Remarkably, V@N4-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 Li2S. With the analysis of correlation map of key parameters, the ICOHP values of TM-S bonds and adsorption energy of *Li2S 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.