Precise design of MOF-derived single-atom catalysts with symmetric and asymmetric coordination for advanced lithium–sulfur batteries

Abstract

Single-atom catalysts (SACs) have demonstrated great potential as ideal electrocatalytic hosts for sulfur cathodes in lithium-sulfur (Li–S) batteries. The coordination microenvironments of SACs greatly influence the lithium polysulfide (LiPS) shuttle effect and sulfur reaction kinetics. Recently, metal–organic frameworks (MOFs) have emerged as a versatile platform for the precise synthesis of SACs, stemming from their high metal loading capacity, structurally ordered porosity and atomic-level tailorability. Many efforts have been made to create symmetric and asymmetric coordination structures in MOF-based SACs for application in Li–S batteries, but a comprehensive summary of catalyst design, structural evolution, and performance evaluation is still lacking. In this review, we systematically categorize the design strategies of symmetric and asymmetric coordination structures in sulfur cathode hosts and their action mechanisms in reinforced Li–S batteries. We also discuss the influence of the coordination symmetry of SACs derived from MOFs on the adsorption energy of LiPSs and their catalytic performance for sulfur conversion in detail. To propel the development of high-performance MOF-derived SACs in Li–S batteries, the current technical challenges and proposed research directions are presented.