Hypercrosslinked Polymerization Enabled N‐Doped Carbon Confined Fe2O3 Facilitating Li Polysulfides Interface Conversion for Li–S Batteries

Abstract Facilitating phase conversion efficiency of Li polysulfides to Li 2 S and restraining the dissolution of Li polysulfides are critical for stable lithium–sulfur (Li–S) batteries. Herein, an in situ formed sulfiphilic superfine Fe 2 O 3 nanocrystals confined in lithiophilic N‐doped microporous carbon (Fe 2 O 3 /N‐MC) is derived from one‐step hypercrosslinked polymerization. Uniquely, the dual active sites (Fe 2 O 3 and N) in Fe 2 O 3 /N‐MC tend to form “FeS, LiO or LiN” bonding, and then synchronically enhancing the chemisorption and interface conversion ability of Li polysulfides. As a result, 80 wt% S is loaded on Fe 2 O 3 /N‐MC and the hybrid cathode delivers high mass capacity (730 mA h g ‐1 ) and excellent cycling stability (87.1% capacity retention over 1000 cycles at 5.0 C). Especially, the cathode also exhibits a high reversible areal capacity of 3.69 mA h cm ‐2 at a high areal loading (5.1 mg cm ‐2 ) and a lean electrolyte/sulfur (E/S) ratio (7.5 µL mg ‐1 ) over 500 cycles. This work is anticipated to deepen the comprehension of complex Li polysulfides interphase conversion processes and afford new thoughts for designing new host materials.