A Highly Crosslinked and Conductive Sulfur-Rich Copolymer with Grafted Polyaniline for Stable Cycling Lithium–Sulfur Batteries

Abstract

Lithium–sulfur batteries offer promisingly high energy density, but suffer from low lithium ion diffusion and lithium polysulfide shuttling, resulting in capacity loss. Herein, we present a novel sulfur-rich copolymer combination Poly(S-r-DIB)-g-PANI (SBPA) to address these chronic issues. Two organic compounds 1,3-diisopropylbenzene and p-aminostyrene are sequentially grafted to sulfur forming multiple crosslinking carbon-sulfur bonds; the amino group of p-aminostyrene then provides a site for aniline polymerization. The combination of the copolymer graftings create a novel structure of highly crosslinked copolymer chains with covalently grafted polyaniline. As cathode material for lithium–sulfur batteries, the sulfur has high specific capacity, impressive cycling stability, and good rate capability, i.e. 1089 mAh g−1 at 0.1 C after 160 cycles (∼84% retention) and 612 mAh g−1 after 450 cycles at 0.5 C (∼73% retention). Compared to controls of sulfur/polyaniline mixtures or to non-aniline-reacted sulfur-copolymer, the polyaniline crosslinked copolymer has superior capacity retention and rate capability due to the unique combination of crosslinked sulfur and grafted polyaniline.