Enhanced dielectric properties and energy storage of the sandwich‐structured poly(vinylidene fluoride‐ co ‐hexafluoropropylene) composite films with functional BaTiO 3 @Al 2 O 3 nanofibres

Polymer-based composites with ceramic fillers could combine the advantages of both, which can be potentially used in electrical and electronic technology. In this work, the barium titanate (BaTiO 3 ) nanofibres and the core-shell structured BaTiO 3 @Al 2 O 3 nanofibres with Al 2 O 3 insulation layer coated on the BaTiO 3 surface were both prepared via the electrospinning method. The appropriate incorporation of the ceramic nanofibres effectively improves the dielectric properties and energy density of the polymer. Moreover, the poly(vinylidene fluoride- co -hexafluoropropylene)-based composite films with the three-layer sandwich structure were fabricated to further promote the dielectric properties. The results show that the outer two layers with a higher content of BaTiO 3 nanofibres can make more contribution to the improved permittivity of the composites. In addition, the introduction of the interlayer with low loading of BaTiO 3 @Al 2 O 3 nanofibres promotes the breakdown strength. This work gives rise to the potential in high energy storage applications.