Highly enhanced dielectric strength and energy storage density in hydantoin@BaTiO3–P(VDF-HFP) composites with a sandwich-structure

Abstract

A sandwich-structured composite consisted of a pure poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) central layer and two BaTiO₃–P(VDF-HFP) neighboring layers was developed for high energy storage density. The sandwiched structure effectively enhanced dielectric properties and energy storage capacity of the composites. Breakdown strength and energy storage density of the composite with 35 vol% P(VDF-HFP) central layer reached 315 kV mm⁻¹ and 5.22 J cm⁻³, which were enhanced by 68% and 125% compared to 187 kV mm⁻¹ and 2.32 J cm⁻³ of the single layer composite, respectively. The dielectric constant of the composites with sandwich-structure was approximately 3 times higher than the pure P(VDF-HFP) and the dielectric loss was as low as 0.026 at 1 kHz. These results demonstrated that the sandwich-structured ceramics/polymer composite was an effective way to produce high energy density composites.