Strategies for Suppressing Crystallinity in Poly(ethylene oxide) (PEO)‐Based Solid Polymer Electrolytes to Enhance Ion Transport: A Mini‐Review

PEO‐based solid polymer electrolytes (SPEs) are among the most intensively studied electrolyte systems for solid‐state lithium batteries because of their strong salt‐solvation capability, good processability, and favorable interfacial compatibility. Their practical application at ambient temperature, however, remains limited by the pronounced crystallization tendency of PEO, which suppresses segmental motion and therefore restricts Li + transport. This mini‐review summarizes recent strategies for reducing crystallinity in PEO‐based SPEs and discusses how these strategies influence polymer dynamics and ionic conduction. Representative approaches, including salt regulation, polymer blending and copolymerization, additive/plasticizer incorporation, filler‐based composite design, and cross‐linking/network construction, are comparatively examined. In general, lowering crystallinity, enlarging the amorphous phase, and enhancing segmental mobility improve ionic conductivity, although these gains are often accompanied by compromises in mechanical robustness, dimensional stability, interfacial compatibility, or electrochemical stability. The available literature therefore indicates that suppressing crystallinity is necessary but not sufficient for practical electrolyte design. Future work should integrate anticrystallization strategies with mechanical reinforcement, interfacial stabilization, and more realistic battery‐level evaluation to accelerate the development of high‐performance PEO‐based electrolytes for solid‐state lithium batteries.