Enhancement of the cycling stability of lithium-sulfur batteries by using a reactive additive for blocking dissolution of lithium polysulfides

An addition of hexamethylene diisocyanate into liquid electrolyte effectively blocks the dissolution of lithium polysulfides at the cathode and enhances the cycling stability of the lithium-sulfur battery while maintaining its high energy density. [Display omitted] •Hexamethylene diisocyanate is employed as a reactive and unprecedented additive.•HDI captures polysulfides by chemical reaction at the electrolyte-cathode interface.•A small amount of HDI completely blocks the dissolution of lithium polysulfides.•The addition of HDI enhances the cycling stability of high energy–density Li-S cells. Hexamethylene diisocyanate was employed as a reactive additive to capture lithium polysulfides formed at the cathode of lithium-sulfur batteries. Unlike other solid additives used to trap polysulfides through physical and chemical interactions, it could effectively capture lithium polysulfides through chemical reaction between hexamethylene diisocyanate and lithium polysulfides at the electrode–electrolyte interface. A small amount of hexamethylene diisocyanate was enough to completely block the dissolution of lithium polysulfides into liquid electrolyte due to its high chemical reactivity, which enhanced the cycling stability of the lithium-sulfur battery while maintaining its high energy density. Our results demonstrate that the addition of hexamethylene diisocyanate to liquid electrolyte can provide an efficient strategy to address dissolution of lithium polysulfides and achieve good cycling stability in the high energy–density lithium-sulfur batteries.