Significantly enhanced energy storage density for poly(vinylidene fluoride) composites by induced PDA-coated 0.5Ba(Zr_0.2Ti_0.8)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ nanofibers

In this study, high aspect ratio TiO₂ nanofibers (TiO₂ NFs), BaTiO₃ nanofibers (BT NFs), CaCu₃Ti₄O₁₂ nanofibers (CCTO NFs) and 0.5Ba(Zr_0.2Ti_0.8)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ nanofibers (BZT-BCT NFs) were prepared via an electrospinning technique. The nanofibers have been modified with polydopamine (PDA), which exhibited excellent dispersion and good compatibility with the polymer matrix. The effects of the structure and morphology of the fillers on the dielectric properties, leakage current density and energy densities of the composites have been also discussed systematically. On comparing the five different poly(vinylidene fluoride) (PVDF) composites, we discovered that the BZT-BCT NFs/PVDF composite displayed low loss, small leakage current and excellent storage performance. On this basis, BZT-BCT NFs/PVDF composites with different volume contents were also fabricated. It can be found that the 7 vol% BZT-BCT NFs/PVDF nanocomposite possessed an excellent dielectric constant (ϵ ∼ 17.6 at 100 Hz). Nevertheless, the 3 vol% BZT-BCT NFs/PVDF nanocomposite demonstrated higher energy storage density (U_e ∼ 7.86 J cm^-3) and greater efficiency (η ∼ 58%) at 310 kV mm^-1. This study may provide a new direction to enhance the energy density of inorganic/PVDF composites.