Microporous Carbon Decorated With Iron Fluoride as Interlayer for Effective Polysulfide Utilization and Anode Protection for Advanced Lithium–Sulfur Batteries

Abstract Lithium–sulfur batteries suffer challenges like polysulfide shuttling and poor sulfur utilization, hindering their practical applications. Here, microporous carbon decorated FeF 2 (C‐FeF 2 ) is synthesized from polyvinylidene fluoride (PVDF) and FeCl 3 precursor sheets via optimized annealing. PVDF serves as both a carbon source and fluorinating agent, yielding a microporous carbon matrix with an ultrahigh specific surface area of 3062.0 m 2 g −1 . Prepared C‐FeF 2 is employed as an interlayer opposite to the sulfur cathode to enhance polysulfide capture and improve cell performance. Its fluorine‐rich polar carbon matrix with micropores enables strong physical entrapment of soluble Li 2 S x , while FeF 2 nanoparticles act as chemical adsorbents, accelerating redox kinetics. This physical‐chemical synergy boosts sulfur utilization via efficient Li 2 S precipitation‐dissolution and rapid Li 2 S x conversion. The cell with the microporous carbon decorated FeF 2 interlayer exhibits remarkable cycling stability, retaining 71.7% capacity at 2C after 450 cycles and 76.1% at 0.5C under 2.5 mg cm −2 sulfur loading after 300 cycles. Furthermore, the interlayer promotes LiF‐rich interface on the cathode, acting as an additional polar immobilizer to polysulfides, suppressing shuttling. The LiF‐rich anode SEI offers superior anode protection versus carbon interlayers, which suffer severe lithium decomposition. This multifunctional strategy offers a compelling pathway toward high‐performance durable Lithium–sulfur batteries.