Molecularly Engineered Dual-Crosslinked Polymer Dielectrics for 200 °C Capacitive Energy Storage

Polymer films offer advantages for capacitors, but high-temperature operation requires new dielectric materials. This study develops a molecular engineering strategy for poly(amide-ester-imide) (PAEI). Skeleton customization via amide groups and ultra-long chains enhances the dielectric constant (ε r ) through optimized dipole alignment. Simultaneously, electrostatic interactions between PAEI and the organic semiconductor [6,6]-phenyl-C61 butyric acid methyl ester (PC61BM) promote hydrogen bonding, constructing a robust crosslinked network. Leveraging PC61BM's unique high electron affinity, the composite exhibits strong electron-trapping capability, significantly reducing high-temperature conduction loss (achieving an ultralow conductivity of 4.97 × 10 −13 S cm −1 at 200 °C). This synergistic effect suppresses carrier mobility by constructing deep electron traps. The resulting nanocomposite demonstrates breakthrough performance: ultralow conductivity and exceptional energy storage characteristics ( U e is 5.16 J cm −3 with η is 90.7% at 200 °C). Multiscale validation-integrating DFT calculations, MD simulations, phase-field simulations, and experimental characterization-confirms that the molecularly engineered crosslinked network suppresses leakage current by trapping charges and restricting chain segment motion under coupled thermal/electrical stress. This work establishes a robust molecular blueprint for extreme-condition dielectrics, demonstrating how nanoscale interfacial engineering bridges molecular design to macroscopic high-temperature capacitive performance. The strategy provides a new pathway for next-generation energy storage materials operating in harsh environments.