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.