Enhanced dielectric performance in PVDF/Al-Al₂O₃ core–shell nanocomposites

Abstract

We report on scalable, time saving, and cost effective method to synthesize core–shell based nanodielectrics for energy storage applications. Nanodielectric films were fabricated by embedding highly ferroelectric β-phase polyvinilydine fluoride (PVDF) polymer with high electrical conductivity alumina coated aluminum nanoparticles. Al-Al₂O₃ core–shell nanoparticles were successfully synthesized through a simple, cost effective, and scalable blending procedure in PVDF to yield high performance energy storage capacitors. The results on electrical permittivity values, structural morphology and phases change with thermal annealing, thermal and frequency response of capacitance, dielectric strength, and dielectric loss of the produced films with different loadings of core–shell nanoparticles are presented. The dielectric permittivity K of the nanocomposite is found to increase from 12 for pure PVDF polymer to a value of 23.6 when PVDF was embedded with a 20% volume loading of Al-Al₂O₃ core–shell nanoparticles. Electrical characterization showed reproducible and stable capacitance values of 10–25 nF/in² over frequencies of up to 10 MHz as well as an increase in capacitance with temperature below 70 °C, and a decrease thereafter. Breakdown voltage for the Al-Al₂O₃/PVDF composite films reached 70 V/µm at a loading of 10% and decreased to 63 V/µm for 20% loading films. Results show that proper loadings (10–20%) of engineered oxidized aluminum (Al-Al₂O₃) in PVDF provide high permittivity low loss nanodielectrics on par with commercially leading dielectrics manufacturer (3M C-Ply) along with the added structural flexibility and cost-saving to the end user.