Improved Energy Density and Energy Efficiency of Poly(vinylidene difluoride) Nanocomposite Dielectrics Using 0.93Na0.5Bi0.5TiO3-0.07BaTiO3 Nanofibers

In modern electronic and power systems, it is essential to develop advanced dielectric materials with high energy density. One-dimensional ferroelectric ceramic nanofibers were proved to be a feasible strategy for improving the permittivity and energy density of nanocomposites. In this paper, to overcome the high loss issue of Na0.5Bi0.5TiO3 (NBT), a kind of novel nanofibers 0.93Na0.5Bi0.5TiO3-0.07BaTiO3 (NBT-BT) with large aspect ratio are synthesized by the electrospinning method and used as the dielectric fillers in trilayer structured poly(vinylidene difluoride) (PVDF) nanocomposites for energy storage applications. The finite element analysis is performed to evaluate the electric field distribution in the nanocomposites. The results showed that the trilayer structured nanocomposite loaded with 6 wt % NBT-BT nanofibers in the middle layer achieved the highest discharge energy density of 19.21 J cm-3 at 527 kV mm-1, which is 87.2% higher than that of pure PVDF (10.26 J cm-3 at 420 kV mm-1). Owing to the contribution of the barrier effect and interface polarization between adjacent layers, the energy density of the trilayer structured nanocomposites is significantly higher than that of the single-layer nanocomposites. This work provides a kind of novel one-dimensional ceramic fillers for obviously improving the energy density of polymer-based dielectrics.