Main-chain programming of poly(aryl ether ketone)s enables superior high-temperature dielectric energy storage

The urgent demand for dielectric films capable of operating under high temperatures and high electric fields in advanced equipment, such as motor controllers for new energy vehicles, has placed increasing requirements on high-temperature polymer dielectrics. To address the increased leakage current and consequent deterioration in energy-storage efficiency of conventional poly(aryl ether ketone) (PAEK) at elevated temperatures, a synergistic molecular design strategy based on modular backbone programming is proposed. By coordinately regulating the conjugation degree of the polymer chains, dipolar response, and chemical crosslinking behavior, PAEK-based films combining low dielectric loss with high breakdown strength are constructed. The optimized film delivers a discharged energy density of 6.94 J cm^-3 with a charge-discharge efficiency of 90% at 150 °C, while exhibiting fast discharge characteristics, excellent long-term cycling stability, and pronounced electrical self-healing capability. This work provides a new molecular design strategy for high-temperature polymer dielectrics toward highly reliable power electronics and pulsed energy-storage devices.