Polymer Electrolytes for All‐Solid‐State Lithium Batteries Materials, Mechanisms, and Manufacturing

Abstract The growing demand for safer, high‐performance, and environmentally sustainable lithium‐ion batteries (LIBs) has accelerated research on advanced solid‐state electrolyte systems. Among them, SPEs and single‐ion conducting polymer electrolytes (SICPEs) have gained prominence due to their favorable mechanical flexibility, electrochemical tunability, and compatibility with scalable fabrication processes. However, challenges such as low ionic conductivity at ambient temperatures, limited lithium‐ion transference numbers, and interfacial instability persist. This review critically evaluates recent progress in polymer electrolyte development, focusing on the relationship between polymer matrix structure, ionic transport mechanisms, and the role of functional fillers. Special attention is given to the design of anionic groups—such as carboxylate, sulfonate, and sulfonylimide—and their influence on charge dissociation and ion mobility. Rather than merely listing known systems, we offer a comparative analysis of their electrochemical performance, highlight unresolved bottlenecks, and identify emerging material strategies that address conductivity–mechanical strength trade‐offs. Additionally, state‐of‐the‐art membrane fabrication techniques, including in situ polymerization, electrospinning, and phase inversion, are assessed for their potential in large‐scale integration. By synthesizing findings across multiple approaches, this review outlines a framework for next‐generation polymer electrolytes tailored for high‐energy‐density and intrinsically safe solid‐state lithium batteries.