Enhanced dielectric properties and energy storage performances by selectively distributed BaTiO₃ in polyvinylidene fluoride/low-density polyethylene blends

The distribution structure of dielectric fillers is attracting more attention in designing composites with excellent dielectric properties and energy storage performances. Barium titanate (BT) and polyvinylidene fluoride (PVDF) were introduced to low-density polyethylene (LDPE) to build the dielectric structure by modulating the phase structure of PVDF/LDPE and the distribution behavior of BT. The results showed that BT particles can be selectively distributed in the phase structure of PVDF/LDPE by controlling the surface modification of BT, which contributed much to the enhancement of dielectric properties and energy storage performances. The dielectric constant and discharge energy density of the composites with the selective distribution of core-shell structured BT@PE in the LDPE phase of PVDF/LDPE blend were increased by 51% and 95% in comparison with PVDF/LDPE blend, respectively. By simulating with finite element analysis (FEA), the increased internal polarization and the decreased electric field distortion of PVDF/LDPE/BT@PE due to BT@PE distributed in the LDPE phase and the small dielectric constant difference between the LDPE/BT@PE phase and PVDF phase were the factors to enhance the dielectric constant and breakdown strength, which consequently enhance the energy storage performances of the composites. Highlights: Phase structure constructed with BT and BT@PE selectively distributed in PVDF/LDPE. Co-enhanced dielectric constant and breakdown strength of PVDF/LDPE/BT@PE. Modulated polarization and electric field due to BT@PE in the LDPE phase of composites.