Superior high-temperature capacitive performance of polyaryl ether ketone copolymer composites enabled by interfacial engineered charge traps

Metalized film capacitors with high-temperature capacitive performance are crucial components in contemporary electromagnetic energy systems. However, the fabrication of polymer-based dielectric composites with designed structures faces the challenge of balancing high energy density (U_e) and low energy loss induced by electric field distortion at the interfaces. Here, BN nanoparticles coated with a thin layer of aminobenzoic acid (ABA) voltage stabilizer are introduced into a copolymer of aryletherketone and 2,6-bis(2-benzimidazolyl)pyridine (P(AEK-BBP)). Our results demonstrate that the ABA voltage stabilizer, possessing high electron affinity, significantly improves the dispersion of BN particles within the matrix, mitigates electric field distortion, and creates effective charge traps. This, in turn, effectively suppresses high-temperature-induced Schottky emission and P-F emission, leading to a dramatic decrease in leakage loss. As a result, the optimized composite film, filled with 0.3 vol% m-ABA-BN particles, exhibites a U_e of 10.1 J cm⁻³ and a η of 90% at 150 °C and 600 MV m⁻¹, surpassing the majority of previously reported materials. Furthermore, even after undergoing 100 000 cycles at 150 °C and 250 MV m⁻¹, the composite dielectric films demonstrate favorable charge-discharge characteristics. This work offers a novel approach to fabricate polymer-based dielectric materials with high-temperature resistance and high discharging efficiency for long-term high energy storage applications.