High energy density of polyimide composites containing one-dimensional BaTiO3@ZrO2 nanofibers for energy storage device

Novel one-dimensional (1D) core-shell structured BaTiO 3 @ZrO 2 (BT@ZrO 2 ) nanofibers have been synthesized through coaxial electrospinning. Homogeneous composite films containing 1D BT@ZrO 2 nanofibers as filler and polyimide (PI) as the polymer matrix were fabricated. The depolarizing ZrO 2 layer with moderate dielectric constant was introduced onto the BT nanofibers surface and decreased the electric filed caused by the tremendous contrast between the PI matrix and the BT nanofibers in permittivity. The energy density and breakdown strength of the BT@ZrO 2 /PI composites can be substantially enhanced. It was established that the 2 vol% BT@ZrO 2 /PI composite film has the maximum energy density of 2.53 J/cm 3 at 361 kV/mm, which is ≈ 180% higher than that of the pristine PI (1.40 J/cm 3 at 303 kV/mm). Furthermore, finite element simulation was carried out to understand the effect of ZrO 2 layer on the electric field distribution. This work demonstrates the advantages of the moderate inorganics layer in increasing the breakdown strength and highly enhancing the energy density of the polymer based composites.