Engineering crystalline property of polymer solid electrolytes for boosted electrochemical performances: a critical review

Abstract

With the growing demand for safe and high-density energy storage systems, solid-state polymer electrolytes (SPEs) have attracted significant research attention because of their exceptional safety, flexibility and processability. However, their practical applications are hindered by the sluggish chain-mediated ion conduction at room temperature. While recent studies have greatly improved ion transport by regulating polymer crystallization behaviors, the underlying mechanism that enhances ion conduction and the absence of precise crystal structure design continue to pose major challenges for the rational development of advanced SPEs. This review first comprehensively examines the basic crystallization principles and ion transport mechanisms in SPEs. Then, three key strategies for engineering crystalline properties in SPEs are summarized, including salt engineering, additive mediation, and physical field regulation. These approaches illustrate the optimization of SPE performance by tailoring crystal morphology, orientation, and defect states. Finally, the limitations of current research are explored, and forward-looking perspectives highlight the critical role of precise crystallization control for developing high-performance SPEs.