An Elastomeric Electrolyte Based on Lithium‐Ion‐Selective Transmembrane Transport for Solid‐State Lithium‐Sulfur Batteries

Abstract Solid‐state lithium‐sulfur batteries (SSLSBs) exhibit advantages such as high specific energy, safety, and low cost, making them an ideal candidate for next‐generation batteries. However, the current mechanical and electrochemical properties of solid‐state electrolytes do not meet the requirements of the practical application of SSLSBs. Herein, a construction strategy of fiber‐network‐based elastomeric solid electrolytes (FESE) based on electrospinning‐induced phase separation is proposed. The FESE features a structure in which an elastomeric layer with Li + ‐selective permeability encapsulates a fibrous plastic crystal electrolyte (PCE). This structure originates from the phase separation and fiberization of a hydrogenated nitrile rubber (HNBR) stabilized emulsion, driven by electrostatic jetting. Subsequently, in situ polymerization of methoxy polyethylene glycol is performed within the battery to achieve void filling. Benefiting from the interconnected ion transport channels, the Li + ‐selectivity, and the conformal interface, the as‐prepared FESE electrolyte achieves a high room‐temperature ionic conductivity of 1.11 mS cm⁻¹ and a Li + transference number of 0.77. The as‐assembled SSLSB delivers a high initial discharge capacity (1188 mAh g −1 ), remarkable rate capability (356 mAh g −1 at 4C), and excellent cycling performance (71.2% capacity retention after 800 cycles). This research presents a constructive strategy for the elastomeric electrolytes for high‐performance solid‐state batteries.