An Amino Acid‐Modified Bifunctional Separator for Shuttle Control and Li Metal Stabilization in Li‐S Batteries

Lithium–sulfur batteries offer high theoretical energy density, affordability, and environmental friendliness, but lack commercial viability due to performance issues stemming from Li dendrite growth and the shuttle effect. In this study, we apply a positively charged amino acid in a surface coating for commercial polypropylene separators, endowing it with shuttle‐inhibiting and anode‐stabilizing functions. The amino acid‐modified separator ( A ‐PC@PP) features a nanocomposite interlayer of L‐Arginine ( Arg ), polyacrylic acid (PAA), and carbon nanofibers (CNFs) to trap and convert polysulfides. Meanwhile, Arg and PAA functional groups introduced throughout the separator homogenize the flux of Li + , suppressing the growth of dendrites on the Li metal anode. Arising from these favorable functions, Li‐S cells equipped with A ‐PC@PP separators show excellent rate capability (> 530 mAh/g at an ultrahigh current density of 5 A/g) and improved cycling stability (with a low decay rate of 0.068% per cycle for 500 cycles at 0.5 A/g). This study showcases the viability of a promising and abundant amino acid in addressing the critical issues of Li‐S batteries.