Engineering Oversaturated Fe‐N5 Multifunctional Catalytic Sites for Durable Lithium‐Sulfur Batteries

Abstract Lithium‐sulfur (Li‐S) batteries are regarded as a promising next‐generation system for advanced energy storage owing to a high theoretical energy density of 2600 Wh kg−1. However, the practical implementation of Li‐S batteries has been thwarted by the detrimental shuttling behavior of polysulfides, and the sluggish kinetics in electrochemical processes. Herein, a novel single atom (SA) catalyst with oversaturated Fe‐N5 coordination structure (Fe‐N5‐C) is precisely synthesized by an absorption–pyrolysis strategy and introduced as an effective sulfur host material. The experimental characterizations and theoretical calculations reveal synergism between atomically dispersed Fe‐N5 active sites and the unique carbon support. The results exhibit that the sulfur composite cathode built on the Fe‐N5‐C can not only adsorb polysulfides via chemical interaction, but also boost the redox reaction kinetics, thus mitigating the shuttle effect. Meanwhile, the robust three‐dimensional nitrogen doped carbon nanofiber with large surface area, and high porosity enables strong physical confinement and fast electron/ion transfer process. Attributed to such unique features, Li‐S batteries with S/Fe‐N5‐C composite cathode realize outstanding cyclability and rate capability, as well as high areal capacities under raised sulfur loading, which demonstrates great potential in developing advanced Li‐S batteries.