Inhibiting polysulfide shuttling with a flexible "skin" for highly stable Lithium-Sulfur batteries

Ion electrokinetic regulation on separator is crucial for reducing polysulfide shuttling in lithium-sulfur (Li-S) batteries. Inspired by the electrostatic shielding effect, we implant a flexible "skin" composed of organic mole-cules (PDDA/PSS) with different charges anchored on carbon nanotubes (CNT), which act as a functional interlayer to prevent the shuttling of polysulfides. Systematic experiments and advanced theoretical calculations show that PDDA@CNT with positively charged amino groups not only provides adequate surface affinity to capture polysulfide anions, but also the highly conductive and high specific surface area CNT enables fast electron/ion migration and physical barrier. Consequently, the cell with PDDA@CNT/PP exhibits a high discharge capacity of 706 mAh g-1 and a favorable cycle stability of 1054 mAh g-1 after 250 cycles at 1C with high coulombic efficiency of 97%. This proof-of-concept work offers new perspectives on how to tailor the ionic behaviors of separators for high-energy Li-S batteries.