Tailoring Solvation Architectures in I─Bi ₂ Se _3‐x Modified High‐Conductivity Gel Electrolytes for Semi‐Solid Lithium–sulfur Batteries

Abstract Solid polymer electrolytes are ideal candidates for safe and high‐energy‐density lithium–sulfur batteries (LSBs). However, the ether oxygen bonds in traditional polyether‐based electrolytes tend to form stable solvation structures with Li⁺, resulting in low ionic conductivity and limiting their practical applications. To address this, the work presents a new design and synthesis of an iodine‐doped bismuth selenide‐modified poly(dimethylacrylamide) composite gel polymer electrolyte (I─Bi 2 Se 3‐x @PDMA), which significantly enhances the Li⁺ conductivity. Theoretical and experimental results demonstrate that rationally designing polyether functional groups can effectively regulate the Li⁺ solvation structure, promoting rapid Li⁺ transport, uniform Li deposition, and suppressing Li dendrite growth. Additionally, the incorporation of I─Bi 2 Se 3‐x , rich in Lewis acid sites, effectively modulates ion transport dynamics and accelerates sulfur redox kinetics. Benefiting from the synergistic effect, I─Bi 2 Se 3‐x @PDMA composite gel electrolyte achieves a high Li⁺ transference number of 0.91 and an ionic conductivity of 1.33 mS cm −1 , endowing LSBs with exceptional rate capability and cycling stability. Even under high sulfur loading of 6 mg cm −2 and low E/S ratio of 3, the areal capacity remains as high as 6.95 mAh cm −2 . This study provides a valuable reference for the development of high‐rate semi‐solid LSBs.