Origin and Acceleration of Insoluble Li 2 S 2 -Li 2 S Reduction Catalysis in Ferromagnetic Atoms-based Lithium-Sulfur Battery Cathodes.

Accelerating insoluble Li 2 S 2 -Li 2 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 Li 2 S 2 . 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 Li 2 S 2 -Li 2 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-N 4 -based cathodes exhibit the fastest deposition kinetics of Li 2 S (226 mAh g -1 ) and the lowest thermodynamic energy barriers (0.56 eV). We believe that the accelerated Li 2 S 2 -Li 2 S reduction catalysis enabled via spin polarization of ferromagnetic atoms provides practical opportunities towards long-life batteries.