Enhanced the breakdown strength and energy density in flexible composite films via optimizing electric field distribution

High energy density flexible composite films have been used for the modern compact electronic devices and electric power systems. A novel nanocomposite film is developed by embedding polydopamine encapsulated Ba 0.6 Sr 0.4 TiO 3 nanoparticles (BST NPs) in the polyvinylidene fluoride polymer matrix. The surface functionalization of BST NPs with polydopamine facilitates favorable interaction between the particle and polymer phase, enhancing nanoparticle dispersion. The elaborate functionalization of BST NPs with polydopamine has guaranteed both the increase of dielectric constant and the maintenance of breakdown strength, resulting in significantly enhanced energy storage capability. A finite element simulation of electric field and electric current density distribution suggested the functionalized BST NPs significantly enhanced the breakdown strength and energy density of the composite films. The nanocomposite with 2.5 vol% functionalized BST NPs displays a high energy density of 6.3 J cm −3 at the low field of 3500 kV m −1 , which is larger than that of the biaxially oriented polypropylenes (BOPP) (1.2 J cm −3 at the field of 6400 kV m −1 ). Therefore, the proposed flexible composites films would also find their potential application prospects in electrical devices such as mobile electronic devices, hybrid electric vehicles and military.