Sulfonic Acid‐Functionalized Zn Single‐Atom Catalysts With Dual Thiophilic and Sodiophilic Sites for High‐Performance Sodium−Sulfur Batteries

ABSTRACT Metal single‐atom catalysts (SACs) for sodium−sulfur (Na−S) batteries typically rely solely on thiophilic binding sites to interact with the polysulfide anions of sodium polysulfides (NaPSs), which intrinsically restricts their catalytic efficiency in sulfur redox reactions. Herein, the sulfonic acid‐functionalized Zn single‐atom catalysts (Zn−N 4 −SO 3 H/C) featuring dual thiophilic and sodiophilic binding sites are designed to improve the energy storage performance of Na−S batteries. The resulting Zn−N 4 −SO 3 H/C provides Zn single‐atom sites and sulfonic acid groups to selectively interact with the polysulfide anions and the sodium cations of NaPSs, respectively. This dual interaction simultaneously strengthens the adsorption of NaPSs and facilitates the Na─S bond cleavage by Na−O interaction, thereby lowering the energy barrier of the rate‐limiting step and accelerating sulfur redox kinetics. The S@Zn−N 4 −SO 3 H/C exhibits a high reversible capacity of 1284 mAh g −1 at 0.1 C after 100 cycles and long‐term stability with a low capacity decay rate of 0.023% per cycle over 1200 cycles at 3.0 C. This work highlights that incorporating metal‐free chemical groups adjacent to metal single‐atom sites offers a synergistic strategy to boost sulfur redox kinetics for high‐efficiency Na−S batteries.