Sulfur-containing polymers for enhancing rate and cycle performance of lithium-sulfur batteries

Sulfur-containing polymer with covalent C-S bonds has become an ideal alternative cathode of element sulfur for lithium-sulfur battery. However, the rational design of polymer structure with high sulfur content and enhanced electrochemical performance of Li-S battery is still a great challenge. In this study, a facial synthesis of sulfur-containing polymer by using 1,2,3-trichloropropane and sulfur as starting materials at a mild condition was reported, and the covalent anchoring of the C-S bonds within the polymer effectively inhibited the shuttle effect of polysulfides, providing a splendid internal environment for the diffusion of lithium ions. As a result, the rich sulfur content (higher than 80 %) and its homogeneous distribution in the polymer backbone determined the excellent rate performance of obtained sulfur-containing polymers. In terms of cycling performance, the reversible specific capacity of the battery is 396 mAh/g after 500 cycles at a current density of 0.5 A/g and 350 mAh/g after 800 cycles at 1 A/g, with a capacity decay of only 0.06 % per cycle.