In-situ crosslinked binder for high-stability S cathodes with greatly enhanced conduction and polysulfides anchoring

An in-situ crosslinked binder based on a new chlorine-containing anionic copolymer for high-performance lithium-sulfur battery is fabricated. The elaborately constructed and optimized network structure shows excellent adhesion strength and suitable electrolyte swellability that ensuring the electrode integrity during long-term cycling. The abundant electron-donating groups on the polymer networks endow sulfur cathode with high lithium-ion conduction and polysulfide-trapping capacity, promoting the electrochemical kinetics. These effects are proved by cyclic voltammetry tests, UV–Vis absorption spectrum, X-ray photoelectron spectroscopy, and density-functional theory calculation (DFT). Consequently, sulfur cathode with this crosslinked binder exhibits a high initial capacity of 1038.1 mAh g−1 and high capacity retention of 77.4% after 800cycles at 0.5C. After 800cycles at 1.0C, the sulfur cathode holds a discharge capacity of 684.2 mAh g−1 and a capacity decay of only 0.033% per cycle. What’s more, the cathode still gains a discharge capacity exceeding 800 mAh g−1 at the rate of 3C. This work gives an effective method to design functional binder for high-performance sulfur cathode with polysulfide-trapping and ion-transporting features.