High‐Strength and High‐Temperature‐Resistant Structural Battery Integrated Composites via Polymeric Bi‐Continuous Electrolyte Engineering

Structural battery integrated composites (SBICs) combining outstanding strength and heat resistance are highly desirable candidates for next generation high speed aircraft. Here, a novel high‐temperature‐resistant bi‐continuous electrolyte based on phthalonitrile resin is presented, allowing the construction of SBICs capable of stable operation across a wide temperature range. Excellent mechanical strength and high ionic conductivity can coexist in a bi‐continuous structure electrolyte (PL50) where the phthalonitrile resin serves as the matrix phase and the ionic liquid electrolyte serves as the conductive phase. Benefiting from the thermal stability of the phthalonitrile resin, SBICs assembled with a PL50 bi‐continuous electrolyte deliver excellent mechanical performance even at temperatures exceeding 200 °C, with a flexural strength of 299 MPa and a flexural modulus of 31.8 GPa. Additionally, with an increase in operating temperature, PL50@SBICs demonstrated enhanced rate performance while maintaining good cycling stability. The demonstration of resisting mechanical abuse at high temperatures and flame retardance further suggests the promise of SBICs with PL50 bi‐continuous electrolytes operating under extreme conditions. The thermal stability of phthalonitrile resin ensures that the bi‐continuous structure electrolyte maintains its structural integrity, excellent mechanical strength, and high ionic conductivity even at extreme temperatures exceeding 200 °C. Consequently, structural battery‐integrated composites assembled with this electrolyte achieve excellent mechanical performance, stable electrochemical properties, and overall safety across a wide temperature range.