Axial Coordination Regulating Electronic Delocalization of p‐Block In−N₄ Sites to Accelerate Sulfur Reduction Reaction

Abstract Modulating the electron delocalization of catalysts can improve the activation and conversion capabilities of lithium polysulfides (LiPSs) in lithium‐sulfur batteries, while the precise mechanism underlying this enhancement remains unclear. Herein, a p‐block In single‐atom catalysts (In‐N₄) is constructed with moderate electron delocalization via axial coordination engineering of gallium nitride (GaN), which exhibits the best adsorption and electrocatalytic activity toward LiPSs. In situ characterization analysis combined with advanced theoretical calculations demonstrate that the axial In‐N‐Ga coordination induces the electron transfer from In sites toward the N sites of GaN and the unconventional sp³d² hybridization interactions of In sites. This further helps to optimize adsorption configuration through the orbital hybridization between sp³d² hybrid orbital of In sites and p orbital of S atoms in LiPSs, namely the sp³d² − p orbital hybridization, which can weaken S−S covalent bonds of LiPSs and significantly accelerate the sulfur reduction reaction. Accordingly, the capacity decay of lithium‐sulfur battery with In−SA/GaN catalyst is only 0.040% per cycle over 800 cycles at 5 C. The stacked pouch cell delivers a reversible capacity of 600 mAh after 100 cycles. This work elaborates on the activity origin of p‐block metal catalysts and provides a new perspective on designing advanced catalysts for other catalytic systems.