Mechanically Interlocked Polyimide@Cyclodextrin All-Organic Dielectric with Enhanced High-Temperature Capacitive Energy Storage Performance

Polymer dielectric materials find extensive application in electrical and electronic systems. However, the energy storage performance of polymer dielectrics sharply decreased above 150 °C, which did not meet the demands of modern capacitor applications. In this paper, a fluorine-containing polyimide (FPI) with a mechanically interlocked structure is synthesized, where β-cyclodextrins are threaded along the axles of FPI chains to generate a self-cross-linking supramolecular polymer network. Based on the mechanically interlocked structure, both the conjugation effect between polymer chains and the phonon-assisted interchain charge transport are weakened, leading to improved breakdown strength and capacitive performance at high temperatures. As a result, the all-organic dielectric films obtained a discharge energy density (Ud) of 8.24 J/cm3 with an efficiency (η) > 90% at 25 °C and 750 MV/m. Besides, the dielectric films exhibit excellent high-temperature capacitive performance; the upper Uds of the film are 5.03 J/cm3 and 3.02 J/cm3 at 150 and 200 °C (η > 80%), respectively. The obtained result presents an innovative tactic for the synthesis of high-performance all-organic polymer dielectrics that meet the current requirements of extreme environments.