Enhanced breakdown strength and energy storage density of PMMA/PVDF blends by coating superficial layers and doping organic fillers

Polymer-based flexible dielectrics have been widely used in capacitor energy storage due to their advantages of ultrahigh power density, flexibility, and scalability. To develop the polymer dielectric films with high-energy storage density has been a hot topic in the domain of dielectric energy storage. In this study, both of electric breakdown strength and energy storage density of poly(methyl methacrylate)/poly(vinylidene fluoride) (PMMA/PVDF) blending films are significantly improved by coating superficial layers and doping organic fillers, which involves using organic molecular semiconductor [6,6]phenyl C61 butyrate methyl ester (PCBM) as fillers doped into PMMA/PVDF (PMMA/PVDF@PCBM), and growing boron nitride (BN) barrier layer on the surface of the PMMA/PVDF@PCBM film (BN-PMMA/PVDF@PCBM-BN). The increased potential barrier height at the BN inorganic layer/metal electrode interface can remarkably suppress charge injection from electrodes. Additionally, the formation of charge traps at the interfaces of PCBM fillers and PVDF/PMMA matrix can significantly limit charge migration. An ultrahigh breakdown field strength of 889.6 kV/mm is achieved in the BN-PMMA/PVDF@0.7wt%PCBM-BN film, which also delivers a maximum discharged energy density of 25.62 J/cm 3 . This work provides an efficient method to enhance energy storage performance of polymer dielectric films by coating superficial layers and doping organic fillers.