Helical Keratin‐Derived Aqueous Binders for High‐Performance Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) possess ultrahigh energy density, low cost, and environmental friendliness, making them strong contenders for next‐generation energy storage technologies. However, their development is hindered by multiple interfacial challenges, including the shuttling of lithium polysulfides (LiPS), sluggish reaction kinetics, and severe volume expansion of the cathode. To address these issues, a multifunctional biomass‐derived aqueous binder was designed by crosslinking an α‐helical protein (α‐HP) with polyvinyl alcohol (PVA) and glycerol (GL). The α ‐helical structure of α‐HP in the α‐HP/PVA/GL adhesive acts as a “molecular spring”, effectively buffering volume expansion and stabilizing the electrode structure. Additionally, its abundant N‐ and O‐containing polar groups efficiently anchor LiPS, significantly suppressing the shuttling effect and accelerating redox kinetics. Consequently, lithium‐sulfur batteries employing the α‐HP/PVA/GL binder exhibit exceptional long‐term cycling stability. The α‐HP/PVA/GL cathode delivers an initial discharge specific capacity of 737.3 mAh g −1 and retains 487.9 mAh g −1 after 600 stable cycles at 2 C, with an average capacity decay rate of only 0.056% per cycle. This study provides a green, facile, and efficient strategy for developing multifunctional binders to overcome practical bottlenecks in lithium‐sulfur battery applications.