Advanced Crosslinked Solid Polymer Electrolytes: Molecular Architecture, Strategies, and Future Perspectives

Abstract Solid‐state batteries (SSBs) have attracted much attention for high‐energy‐density and high‐safety energy storage devices. Solid polymer electrolytes (SPEs) have emerged as a critical component in the advancement of SSBs, owing to the compelling advantages of strong molecular structure‐designability, low cost, easy manufacturing, and no liquid leakage. However, linear SPEs usually have low room‐temperature ionic conductivity due to crystallization, and melting at high temperature. Thus, crosslinked SPEs have been proposed in that the chemical bonding between internal molecule chains can maintain solid state to expand operational temperature, disrupt regularity of segment, and diminish crystalline degree, leading to an enhancement of room‐temperature ionic conductivity. Furthermore, the integration of functional groups within crosslinked SPE network can significantly augment the electrochemical performance of SPEs. Herein, according to the network structure, crosslinked SPEs are categorized into four types: simple network, AB crosslinked polymers (ABCP), semi‐interpenetrating network (semi‐IPN), and interpenetrating network (IPN), then the structure features and advantages and disadvantages of commonly used polymers for these types of crosslinked SPEs are reviewed. In addition, crosslinked SPEs with self‐healing, flame‐retardant, degradable, and recyclability are introduced. Finally, challenges and prospects of crosslinked SPEs are summarized, hoping to provide guidance for the molecular design of SPEs in the future.