Imidazole-modified separator for uniform polysulfide anchoring and accelerated redox in LiS batteries

Despite their ultrahigh theoretical energy density, the practical application of lithium‑sulfur (Li S) batteries is hindered by severe lithium polysulfides (LiPSs) shuttling and sluggish redox kinetics. To address these challenges, an imidazole polymer layer is grafted onto the polypropylene (PP) separator, enabling equivalent interactions with various LiPSs. Density functional theory (DFT) calculations reveal that this uniform anchoring originates from electrostatic interactions, which promote the redox conversion of LiPSs. Meanwhile, the imidazole-modified separator improves electrolyte affinity, facilitating efficient lithium-ion transport. The low self-discharge, excellent cycling stability, and preserved electrode morphology confirm the successful suppression of LiPSs shuttling. Moreover, pouch cells assembled with the imidazole-modified separator exhibit a capacity of 0.45 Ah, demonstrating the practical feasibility of this separator design. This “equivalent anchoring and accelerated conversion” mechanism offers a new pathway toward high-performance Li S batteries with mitigated shuttle effect.