Ultrahigh Discharge Efficiency and High Energy Density in Sandwich Structure K0.5Na0.5NbO3 Nanofibers/Poly(vinylidene fluoride) Composites

The high discharge energy density and excellent discharge efficiency are important indicators for measuring the performance of the capacitor. This work systematically studies the sandwich structure ceramic/polymer composites in which the original poly(vinylidene fluoride) (PVDF) is used as the outer layer, and the one-dimensional K0.5Na0.5NbO3 nanofibers and PVDF composites are used as the intermediate layer. The experimental results show that the energy storage performance of the composite films can be effectively improved by rationally designing and optimizing the filler content. The finite element simulation verifies that the sandwich structure composites mainly reduce the electric field strength of the intermediate layer by adding ceramic fibers, which hinder the growth of the electric trees. In addition, reasonable filler content and optimized structural design can significantly reduce the electrical conductivity, thereby achieving excellent discharge efficiency. In the optimized sandwich structure composites, the high energy density of 14.2 J cm(-3) and excellent discharge efficiency (eta = 78.5%) are achieved when the breakdown strength is 420 MV m(-1). This unique sandwich structure design and high aspect ratio achieve high discharge efficiency and energy storage density provide a reference for next-generation dielectric materials.