Enhanced permittivity and energy density of P(VDF-HFP)-based capacitor using core-shell structured BaTiO 3 @TiO 2 fillers

As the electronic industry developed rapidly, greater demands are required on the performance of dielectric composites, such as high permittivity, low dielectric loss, and high-energy density. Improving the compatibility of fillers in polymer matrix and uniform distribution of the electric field could increase the permittivity of such composites. Therefore, BaTiO3 nanoparticles were coated by TiO2 sol to fabricate BaTiO3@TiO2 core-shell structured fillers in this paper. BaTiO3@TiO2 fillers with gradient permittivity were firstly modified by dopamine in order to disperse in the composites homogeneously and adhere to poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix tightly. At 1 kHz, the permittivity of the composite with 20 vol% BaTiO3@TiO2 was 32.15, obviously larger than that of pure P(VDF-HFP) (6.92), and the dielectric loss was just 0.052. Consequently, the discharged energy density of the composite was enhanced to 0.23 J/cm3 at 40 kV/mm, which was two times higher than that of pure P(VDF-HFP). This work provides a feasible approach to prepare high-performance dielectric composites.