Hypercrosslinked Polymerization Enabled N-Doped Carbon Confined Fe_2O_3 Facilitating Li Polysulfides Interface Conversion for Li–S Batteries

摘要

Facilitating phase conversion efficiency of Li polysulfides to Li2S and restraining the dissolution of Li polysulfides are critical for stable lithium-sulfur (Li-S) batteries. Herein, an in situ formed sulfiphilic superfine Fe2O3 nanocrystals confined in lithiophilic N-doped microporous carbon (Fe2O3/N-MC) is derived from one-step hypercrosslinked polymerization. Uniquely, the dual active sites (Fe2O3 and N) in Fe2O3/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 Fe2O3/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 mu L 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.