Highly conductive copolymer/sulfur composites with covalently grafted polyaniline for stable and durable lithium-sulfur batteries

Due to their high energy density, lithium-sulfur (Li/S) batteries are among the most promising future power sources to replace modern lithium ion batteries, but low conductivity of sulfur-based cathodes significantly impedes their practical applications. In this study, novel conductive sulfur-rich copolymer/sulfur cathode materials, cp(S-g-PANI)/S (SPAS), are developed by grafting conductive polymer segments onto copolymer backbones to improve cell electrical conductivity and enhance lithium diffusion. In a Li/S cell, newly obtained composites deliver an initial discharge capacity of 1151 mAh gsulfur−1 at a current density of 0.1C. Compared to composites lacking conductive polymer segments in the copolymer backbone, such as cp(S-AS)/S (SAS), SPAS provide better rate performance when current density is increased from 0.1C to 5C and exhibit good cycling stability at 0.5C. High capacity and cycling stability of SPAS as lithium-sulfur battery cathodes are ascribed to a synergetic effect between sufur-rich copolymer and conductive PANI.