High Energy Storage Density of Sandwich-Structured Na_0.5Bi_0.5TiO₃/PVDF Nanocomposites Enhanced by Optimizing the Dimensions of Fillers

The dielectric behavior and mechanisms of improved energy storage density of sandwich-structured different dimensions of Na0.5Bi0.5TiO3 /PVDF composites were studied. Compared with NBT-NPs/PVDF, optimized NBT-NFs/PVDF has a greater dielectric polarization strength, so the dielectric constant of NBT-NFs/PVDF is greater than that of composite materials filled with NBT-NPs with the same volume content. With the benefit from the addition of optimized high-aspect-ratio one-dimension NBT fiber as filler and the sandwich configuration for the composites, the experimental results prove that sandwich-structured NBT-NFs/PVDF can achieve a large energy storage density of 11.7 J/cm3 at a relatively lower electric field of 350 kV/mm for the composites with 1% volume fraction of NBT-NFs in the outer layers. The stronger polarization of composites filled by NBT-NFs is proved via electric modulus and the crystallinity of the composite films. Last but not least, the study found that composite materials also have excellent stable performance and good bending cycle stability. In summary, the composite materials obtained in this study can be used in electronic components for flexible energy storage in the future.