Iodine-doped fibrous sulfurized polyacrylonitrile with accelerated reaction kinetics

Sulfurized polyacrylonitrile (SPAN) is a promising candidate cathode material for the next-generation lithium-metal batteries due to its unique chemical structure and excellent electrochemical stability. Although SPAN is a type of conductive conjugated polymer, it suffers from the slow reaction kinetics resulting from its insufficient electronic conductivity. In this work, we propose a freestanding fibrous SPAN with an accelerated reaction kinetics by iodine doping. According to Raman, X-ray photoelectron spectroscopy and thermal analysis, sulfur and iodine atoms existing in the form of C–S/S–S and C–I bonds in the iodine-doped sulfurized polyacrylonitrile (I-SPAN), respectively. The electrochemical tests reveal that the charge transfer in I-SPAN improved significantly. A high reversible specific capacity of 1201 mAh g−1 is achieved after 400 cycles at 1000 mA g−1.