An In-Situ Cross-Linked Binder for High-Performance Lithium-Sulfur Batteries

The lithium-sulfur batteries suffer from volume variation, insulation of sulfur and shuttle effect, leading to poor cycling performance. Herein, an in-situ cross-linked binder (CPS) based on carboxymethyl cellulose conjugated with catechol groups and thiolated branched polyethylenimine was prepared for lithium-sulfur batteries. The cross-linked structure of CPS was formed through Michael addition reaction avoiding consumption of catechol groups. The CPS with abundant polar groups (amine, catechol and hydroxyl groups) strongly traps lithium polysulfides, suppressing the shuttle effect. The polar groups of the CPS also facilitate the lithium-ion diffusion. Moreover, the polar groups, cross-linked structure and rigid-soft moieties of CPS provide superior mechanical performance, tolerating and buffering the volume change of active materials. Therefore, the cycling stability and rate performance of sulfur cathodes using CPS are significantly improved.