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 BaTiO 3 @TiO 2 nanoparticles are prepared, in which the BaTiO 3 ( d ~ 8 nm) nanoparticles are encapsulated by the amorphous TiO 2 shell layer. Compared to the conventional BaTiO 3 /PVDF nanocomposite, the BaTiO 3 @TiO 2 /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% BaTiO 3 @10 wt%TiO 2 . Therefore, the gradient design of ultrasmall dielectric nanofillers shows high potential in fabrication of high energy-density nanocomposite.