Engineering Spatially Adjacent Sites with Synergistic Spin Polarization Effect to Promote Sulfur Redox Kinetics in Lithium-Sulfur Batteries.

The kinetics of sulfur catalytic reactions serve as a fundamental cornerstone for maximizing both the capacity and stability of lithium-sulfur batteries (LSBs). Recently, investigations into Li-S catalysts predominantly center around the optimization of energy levels to bolster adsorption and catalytic conversion processes. However, a significant oversight persists, as the profound influence of electron spin states on charge transfer dynamics and orbital interactions is frequently neglected. Herein, NH4MnF3 is synthesized as a sulfur host due to the strongly polarized Mn-F bonds, which generate a stronger ligand field and endow it with remarkable electrochemical activity. By capitalizing on the electric field-induced effect exerted by adjacent Co atoms, the crystal structure of NH4MnF3 is optimized, successfully inducing spin-orbit splitting at the Mn centers. This achievement significantly enhances the overlap with the pz orbitals of polysulfides, effectively expediting the kinetic processes of sulfur redox reactions within LSBs. Notably, the Co-NH4MnF3 demonstrates exceptional electrochemical performance. Specifically, at a high rate of 2 C, it retains a remarkable specific capacity of 686 mAh g-1 even after 1000 cycles. This work unveils the pivotal role played by the electron spin states of active centers in sulfur catalytic conversion.