High Energy Storage Density for Poly(vinylidene fluoride) Composites by Introduced Core-Shell CaCu₃Ti₄O₁₂@Al₂O₃ Nanofibers

In this paper, the one-dimensional (1D) Al₂O₃ nanofibers (Al₂O₃ NFs), CaCu₃Ti₄O₁₂ nanofibers (CCTO NFs), and core-shell CaCu₃Ti₄O₁₂@Al₂O₃ nanofibers (CCTO@Al₂O₃ NFs) were prepared via electrospinning technique. The surface modification with dopamine (PDA) was employed for the above three kinds of nanofibers before being filled the PVDF matrix, which can improve their dispersion and compatibility with the matrix. The microstructure, dielectric properties, leakage current density, breakdown strength, and energy storage performance of composites with three kinds of filler, CCTO NFs/PVDF, Al₂O₃ NFs/PVDF, and CCTO@Al₂O₃ NFs/PVDF, were systematically investigated. By comparing the three composites, it can be found that energy storage density of CCTO@Al₂O₃ NFs/PVDF were enhanced compared to that of pure PVDF, which can be attributed to improvement of polarization and electric breakdown strength. The energy density of 8.46 J/cm³ at 340 kV/mm was obtained for 4 vol % CCTO@Al₂O₃ NFs/PVDF nanocomposites, which is 230% larger than that of PVDF (3.68 J/cm³ at 330 kV/mm). This study provides a method for preparing high energy storage PVDF-based composite film which can be used for the next generation of dielectric capacitors.