Topological Polymer Electrolyte Design with Dual Confinements for Long‐Life Quasi‐Solid‐State Lithium–Sulfur Batteries

Abstract Sulfurized polyacrylonitrile (SPAN) is considered a promising candidate for lithium–sulfur batteries (LSBs) due to its inherent high conductivity, reversibility, and low cost. However, its poor compatibility with electrolytes, the unavoidable shuttle effect, and limited structural stability in liquid electrolytes hinder its widespread application. To address these challenges, a dual‐constrained topological polymer electrolyte (DCTPE) is synthesized via in situ thermal polymerization, which exhibits strong adsorption and interfacial enhancement. DCTPE covalently adsorbs lithium polysulfides (LiPS) through numerous polar O‐containing functional groups, significantly inhibiting the dissolution and diffusion of LiPS. Additionally, the steric‐hindrance effect of the topological polymer reshapes the Li⁺ solvation environment, promoting the formation of a high‐strength and conductivity interfacial layer, which can enable homogeneous Li‐deposition and rapid ion migration. Consequently, the Li‐SPAN cell achieves excellent cycling stability over 1200 cycles at 1C. Moreover, when tested in the pouch‐type full‐cell, it still steadily operates over 500 cycles at 0.5C without obvious capacity decay and retains a capacity of 1134.4 mAh g −1 with excellent capacity retention of 95.4%. This strategy is facile and cost‐effective, highlighting the potential of topological polymer electrolytes to address the key challenges of LSBs, which will be of great interest to high energy solid‐state batteries.