Accelerated Reversible Conversion of Li 2 S 2 to Li 2 S by Spidroin Regulated Li + Flux for High‐performance Li‐Sulfur Batteries

Regulating the transformation of sulfur species is the key to improving the electrochemical performance of lithium‐sulfur (Li−S) batteries, in particular, to accelerate the reversible conversion between solid phase Li 2 S 2 and Li 2 S. Herein, we introduced Spidroin, which is a main protein in spider silk, as a dual functional separator coating in Li−S batteries to effectively adsorb polysulfides via the sequence of amino acids in its primary structure and regulate Li + flux through the β‐sheet of its secondary structure, thus accelerating the reversible transformation between Li 2 S 2 and Li 2 S. Spidroin‐based Li−S cells exhibited an exceptional electrochemical performance with a high specific capacity of 744.1 mAh g −1 at 5 C and a high areal capacity of 7.5 mAh cm −2 at a low electrolyte‐to‐sulfur (E/S) ratio of 6 μL mg s −1 and a sulfur loading of 8.6 mg s cm −2 .