Gradient design of ultrasmall dielectric nanofillers for PVDF-based high energy-density composite capacitors

Dielectric capacitors are key devices in pulsed power systems for their high power density. To improve the energy density, compact nanocomposite films comprising PVDF polymer and core-shell BaTiO3@TIO2 nanoparticles are prepared, in which the BaTiO3 (d similar to 8 nm) nanoparticies are encapsulated by the amorphous TiO2 shell layer. Compared to the conventional BaTiO3/PVDF nanocomposite, the BaTiO3@TiO2/PVDF nanocomposite in this report takes advantage of the small particle size and the gradient dielectric design of the interface, which enhances the electric displacement as high as 65% and the breakdown strength of 20% simultaneously. A maximal discharged energy density of 11.34 J . cm(-3) is achieved under an electric field of 420 kV. mm(-1) in the nanocomposite film containing 5 vol% BaTiO3@10 wt%TiO2. Therefore, the gradient design of ultrasmall dielectric nanofillers shows high potential in fabrication of high energy-density nanocomposite. (C) 2020 Published by Elsevier Ltd.