Simultaneously improved dielectric constant and breakdown strength of PVDF/Nd-BaTiO3 fiber composite films via the surface modification and subtle filler content modulation

Flexible dielectric capacitors with large energy storage density play key role in modern electronic devices. Ceramic fibers with large dielectric constants are benign candidates to be introduced into the polymer matrix to enhance the energy storage density while guaranteeing the flexibility. In present work, Nd doped BaTiO3 (NBT) fibers with and without dopamine (PDA) coating were successfully fabricated and introduced into the Poly (vinylidene fluoride) (PVDF) matrix. The dielectric constants and breakdown strength were simultaneously enhanced with a small loading of NBT filler. The subtle modulation was then performed around the filler loading at which the large energy density was obtained. With the NBT loading of 2.5 wt% and 4.2 wt%, the maximum energy density of 9.3 and 10.4 J/cm(3) were obtained in PVDF/NBT and PVDF/NBT@PDA composites, respectively. Both of experimental results and simulation indicate the effectiveness of dopamine coating on the uniform distribution of electric field and good comparability between the matrix and fillers.