Ultrahigh discharged energy density in polymer nanocomposites by designing linear/ferroelectric bilayer heterostructure

Abstract

The development of advanced dielectric materials with high discharged energy densities is of critical significance for modern electric devices and electric power systems. In this report, linear/ferroelectric bilayer-heterostructured polymer nanocomposites with an ultrahigh discharged energy is presented for the first time. The linear polyimide (PI) is employed as bottom insulating layer to provide high breakdown strength (Eb), while ferroelectric P(VDF-CTFE) with dispersed BaTiO3 nanoparticles as the top layer, provides a high dielectric constant. This linear/ferroelectric bilayer dielectric material exhibits enhanced Eb and (Dmax-Pr) values, which can be attributed to the interfacial barrier and the interfacial polarization effect at the interface of two layers. Favorable distribution of the local electric field within this bilayer dielectric reveals the implication of the collaborative double interface effects on the energy storage performance of the nanocomposites. As a result, the bilayer-heterostructured nanocomposite displays an ultrahigh discharged energy density of 14.2 J/cm3 at 370 MV/m. This energy density is among the highest under the equivalent electric field strength reported so far. This work not only provides a new design to optimize the performance of the dielectric nanocomposites for flexible energy storage applications, but also develops the understanding of the breakdown and polarization mechanism of dielectric materials.