Dual Active Sites of Oversaturated Fe‐N5 and Fe2O3 Nanoparticles for Accelerating Redox Kinetics of Polysulfides

Abstract The shuttling effect and sluggish reaction kinetics are the main bottlenecks for the commercial viability of lithium–sulfur (Li–S) batteries. Metal‐nitrogen‐carbon single atom catalysts have attracted much attention to overcoming these obstacles due to their novel electrocatalytic activity. Herein, a novel cooperative catalytic interface with dual active sites (oversaturated Fe‐N 5 and polar Fe 2 O 3 nanocrystals) are co‐embedded in nitrogen‐doped hollow carbon spheres (Fe 2 O 3 /Fe‐SA@NC) is designed by fine atomic regulation mechanism. Both experimental verifications and theoretical calculations disclose that the dual active sites (Fe‐N 5 and Fe 2 O 3 ) in this catalyst (Fe 2 O 3 /Fe‐SA@NC) tend to form “FeS” and “LiN/O” bond, synchronically enhancing chemical adsorption and interface conversion ability of polysulfides, respectively. Specially, the Fe‐N 5 coordination with 3D configuration and sulfiphilic superfine Fe 2 O 3 nanocrystals exhibit the strong adsorption ability to facilitate the subsequent conversion reaction at dual‐sites. Meanwhile, the nitrogen‐doped hollow carbon spheres can promote Li + /electron transfer and physically suppress polysulfides shuttling. Consequently, Li–S battery with the Fe 2 O 3 /Fe‐SA@NC‐modified separator exhibits a high capacity retention of 78% after 800 cycles at 1 C (pure S cathode, S content: 70 wt.%). Furthermore, the pouch cell with this separator shows good performance at 0.1 C for practical application (S loading: 4 mg cm −2 ).