Dopamine-modified separator anchoring polysulfides via electrostatic interaction for enhanced Lithium-sulfur batteries

Abstract

Lithium‑sulfur (LiS) batteries possess high energy density and low cost, which have been considered as the most promising energy storage devices. However, the commercialization of LiS batteries has been impeded by the severe shuttling of soluble polysulfides during the charge-discharge cycling. In this work, we propose a novel strategy to modify polypropylene (PP) separator by grafting dopamine, a compound with phenolic hydroxyl and amino groups, to anchor polysulfides while maintaining the separator's porous structure for efficient lithium ion transport. Density functional theory (DFT) calculations reveal that dopamine polymer layer can effectively suppress polysulfides shuttling through electrostatic interaction with lithium atoms in polysulfides. Moreover, dopamine-modified separator enhances the electrolytes affinity and facilitates lithium ion transport. Cyclic voltammetry measurements, a high initial capacity of 1123 mAh·g⁻¹ at 0.5C, lithium metal corrosion resistance, and the morphology of the cycled separators all confirm that dopamine-modified separator effectively mitigates the shuttle effect while maintaining the improved battery performance. This work opens up a new approach for the practical application of LiS batteries.