Promoting Bidirectional Conversion of Li ₂ S with Single‐Atom Cobalt Coordinated Gel Catalyst for High‐Rate Lithium‐Sulfur Batteries

Abstract Lithium‐sulfur (Li‐S) batteries exhibit extraordinary advantages owing to their high theoretical capacity and the natural abundance of sulfur. However, their practical applications are hindered by sluggish redox kinetics, particularly during the Li 2 S 2 −Li 2 S conversions. Here, we propose a novel metal‐coordinated gel strategy to develop a Co‐SAs/NC (Co‐N5‐C) single‐atom catalyst for efficient insoluble sulfur conversion. By crosslinking cobalt into a polyacrylonitrile matrix via Co‐N coordination, a nitrogen‐coordinated Co single‐atom structure with high Co contents embedded in a layered carbon framework is achieved. Experimental and theoretical results reveal that the unfilled 3d orbitals of Co‐N5 sites enhance d‐p hybridization via Co‐S binding, facilitating the bidirectional conversion between Li 2 S 2 and Li 2 S, Reducing the barrier for reducing Li 2 S 2 to Li 2 S from 1.33 for NC carbon to 0.64 eV for Co‐N5‐C, and that for oxidizing Li 2 S from 2.12 for NC carbon to 1.62 eV for Co‐N5‐C. With the Co‐N5‐C‐modified separator, the Li‐S battery delivers a high discharge capacity of 780 mAh g −1 at 5 C, and an unprecedented areal capacity of 9.0 mAh cm −2 under a high sulfur loading of 8.97 mg cm −2 . This work provides an efficient single‐atom catalysis approach for achieving stable high‐rate Li‐S batteries by redefining the sulfide conversion kinetics.