Geometrically Matched Bridge Adsorption: Boosting Polysulfide Conversion Kinetics via Fe ₂ N ₆ Catalysts

ABSTRACT

The commercialization of lithium–sulfur batteries (LSBs) is hindered by sluggish lithium polysulfides (LiPSs) conversion kinetics. While single‐atom catalysts (SACs) are widely used, their rigid coordination often causes severe “geometric mismatches” with LiPSs, leading to inefficient end‐on adsorption. Herein, a “spatial geometric matching” strategy is proposed via an in situ constructed homonuclear Fe dual‐atom catalyst (Fe ₂ N ₆ ) featuring a stretched bond‐length network. Theoretical calculations combined with AC‐HAADF‐STEM and XAFS confirm that the adaptively extended Fe─N bonds and specific Fe─Fe interatomic distance in Fe ₂ N ₆ precisely match key intermediate dimensions. This three‐dimensional size matching transitions the adsorption configuration from conventional “end‐on” to “multi‐site synergistic bridging”. Notably, this geometric‐matching‐driven chemical coupling breaks the scaling relation limits of classical d‐band center theory. Benefiting from its dynamic structure and intrinsic catalytic activity, the assembled Fe ₂ N ₆ @CC cell delivers a high capacity of 869.8 mAh g ⁻¹ at 4 C, an ultralow decay rate of 0.011% per cycle over 1000 cycles at 2 C, and a stable areal capacity of 3.46 mAh cm ⁻² under 4.08 mg cm ⁻² sulfur loading. This work establishes a micro‐geometric paradigm for rationally designing advanced LSBs catalysts.