Bifunctional Binder with Nucleophilic Lithium Polysulfide Immobilization Ability for High-Loading, High-Thickness Cathodes in Lithium-Sulfur Batteries.

Lithium-sulfur batteries remain a promising next-generation renewable energy storage device due to their high theoretical energy density over the current commercial lithium-ion battery technology. However, to have any practical viability toward reaching the theoretical value, high-loading cathodes with sufficient sulfur content and specifically the effect of nonconductive binders must be investigated. We consider the limitations of conventional binders for high-loading, high-thickness cathodes by integrating a bifunctional binder with a linear polyethylene chain and maleate-capped ends. The linear polymer allows for flexibility within the high-loading cathode whereas the maleate ends improve the polysulfide trapping ability with carbon-sulfur binding. With the strong polysulfide immobilization ability due to the nucleophilic binding, the binder achieves high sulfur loadings of 12 mg cm-2 with a high sulfur content of 80 wt %. The work serves as a proof of concept for exploring the incorporation of polymeric materials into sulfur cathodes to realize practical viability.