Iron Porphyrin-Mediated Electrolyte Chemistry for Advanced Lithium–Sulfur Batteries

The real implementation of lithium-sulfur (Li-S) batteries suffers from severe polysulfide shuttling, sluggish sulfur redox reaction kinetics, and inhomogeneous lithium deposition, all of which lead to diminished rate capability, and cycling performance and safety concerns. In this study, iron(III) meso-tetraphenylporphyrin chloride (FeTPP) is introduced into the electrolyte as an effective homogeneous catalyst to address the interconnected challenges in Li-S batteries. The FeTPP molecules present high metal utilization efficiency, an optimized coordination environment, and remarkable mobility within the electrolyte, thereby demonstrating outstanding working activity in homogeneously mediating the kinetic evolution of sulfur and lithium species. Moreover, a saturated concentration of 0.1 wt % further pledges a sufficient number of FeTPP molecules to act as homogeneous promoters in the electrolyte. Therefore, both a highly efficient sulfur cathode and a stable lithium anode are achieved simultaneously, significantly contributing to the enhanced capacity, prolonged cycling life span, and improved operational safety of Li-S batteries.