Coordination engineering of single atom catalysts for lithium-sulfur batteries: from local structure design to catalytic mechanisms

Single-atom catalysts (SACs) have emerged as powerful electrocatalysts to accelerate sulfur redox kinetics in lithium‑sulfur (Li-S) batteries, owing to their maximized atomic utilization and tunable electronic properties. From the perspective of coordination chemistry, this review conceptualizes SAC sites as coordination complexes, systematically outlining how their coordination number, ligand type, local symmetry, and ligand-field strength dictate the metal valence state, spin state, and frontier orbital configuration, thereby governing polysulfide adsorption, activation barriers, and multi-electron conversion pathways. We organize the literature into four coordination-focused families—(i) classical M-N 4 configurations, (ii) non-M-N 4 coordination architectures (e.g., M-N 2 , M-N 3 , M-N 5 ), (iii) heteroatom-coordinated structures (e.g., M-N m X n , where X = O, S, Cl, P, etc.), and (iv) dual-atom catalysts. For each category, we analyze the structure-activity relationships and the underlying mechanisms that govern polysulfide adsorption, activation, and conversion. Finally, we outline current challenges and propose future directions toward the rational design and scalable synthesis of SACs with optimized coordination structures. This coordination-centric review aims to bridge molecular coordination chemistry and electrocatalysis by providing targeted, predictive guidelines for next-generation Li-S catalyst design.