Synergistic Integration of Fe–N 4 Single‐Atom Sites and Directionally Aligned Electrode Architecture for High‐Performance Lithium–Sulfur Batteries

ABSTRACT Sluggish kinetics of redox reactions and slow ion transport restrict the performance of lithium‐sulfur (Li─S) batteries. Here, we fabricate cathodes containing vertically aligned porous structures hosting atomically dispersed Fe─N 4 single‐atom catalyst (SAC) sites on graphitic carbon nitride (g‐C 3 N 4 ). Density functional theory (DFT) calculations suggest that the Fe─N 4 sites strengthen Li 2 S adsorption, optimize electronic structure, and lower the reaction energy change associated with liquid‐solid transition and Li 2 S oxidation. Experimental results demonstrate that the atomically dispersed Fe─N 4 sites in the vertically aligned porous cathodes made by directional ice templating (DIT) accelerate Li + ion transport and enable high sulfur loading while exposing abundant catalytic centers, resulting in strong polysulfide affinity, promoted nucleation and decomposition of Li 2 S bidirectional redox catalysis, and suppressed polysulfide shuttle effect. Benefiting from this structural‐catalytic synergy, the cathode delivers a high capacity of 1299.2 mAh g −1 at 0.1 C, and the capacity is retained at 505.9 mAh g −1 after 1 000 cycles at 0.5 C, with a low capacity decay rate of ∼0.042% per cycle. This study highlights a scalable strategy to integrate SAC with vertically aligned porous electrode architecture that promotes fast kinetics of sulfur redox in both directions and mass transport for Li─S batteries.