Origin and Acceleration of Insoluble Li2S2−Li2S Reduction Catalysis in Ferromagnetic Atoms‐based Lithium‐Sulfur Battery Cathodes

Accelerating insoluble Li₂ S₂ -Li₂ S reduction catalysis to mitigate the shuttle effect has emerged as an innovative paradigm for high-efficient lithium-sulfur battery cathodes, such as single-atom catalysts by offering high-density active sites to realize in situ reaction with solid Li₂ S₂ . However, the profound origin of diverse single-atom species on solid-solid sulfur reduction catalysis and modulation principles remains ambiguous. Here we disclose the fundamental origin of Li₂ S₂ -Li₂ S reduction catalysis in ferromagnetic elements-based single-atom materials to be from their spin density and magnetic moments. The experimental and theoretical studies disclose that the Fe-N₄ -based cathodes exhibit the fastest deposition kinetics of Li₂ S (226 mAh g^-1 ) and the lowest thermodynamic energy barriers (0.56 eV). We believe that the accelerated Li₂ S₂ -Li₂ S reduction catalysis enabled via spin polarization of ferromagnetic atoms provides practical opportunities towards long-life batteries.