Significantly enhanced energy density and breakdown strength of polymer nanocomposites using highly textured [111]c BaTiO3 platelets

•x wt%-BT/P(VDF-HFP) films were prepared by topochemical microcrystal conversion process and solution casting process.•The composite films exhibit a high breakdown strength of 480 MV/m and the energy density of 19.5 J/cm³ .•The excellent cycle life stability of discharge energy density has been achieved in 1.0 wt%-BT/P(VDF-HFP) composite films. Polymer-based dielectric films are considered as most promising materials for pulsed power capacitors due to their ultra-high power density and current density, fast discharging speed, excellent cycle lifetime and so on. However, the relatively low energy density and efficiency limit their applications in modern electronics and electrical power systems. Here we demonstrate a remarkable improvement in the breakdown strength and energy density of [111]c-BaTiO3 (BT) textured ceramic platelets synthesized in a poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) matrix. The breakdown strength of 1.0 wt% BT/P(VDF-HFP) composite films is 130 MV/m higher than that of pristine poly(vinylidene fluoride-hexafluoropropylene) films. The highest energy density of 19.5 J/cm³ and discharged energy density of 10.6 J/cm³ are achieved under an electric field of 480 MV/m in the 1.0 wt% BT/P(VDF-HFP) composite films. Fatigue experimental results show that the energy density and efficiency enhanced with the increase of cycles. This study provides a new paradigm to develop the polymer composites with high breakdown strength and energy density, which has great potential for flexible electrical energy storage applications.