Sandwich‐structured PPy‐TiO ₂ /PVDF composite films with outstanding dielectric properties and energy density

Improving the energy storage density of dielectric capacitors has absorbed extensive attention for energy storage. However, a decrease in breakdown strength may be aroused after the addition of abundant fillers, it is necessary to design the composite film with a sandwich structure without the sacrifice of mechanical properties. The PPy-TiO2/PVDF monolayer film and PVDF/PPy-TiO2/PVDF sandwich-structured composite films were successfully prepared via electrospinning and a hot-press treatment. The experiment results show that the dielectric constant of the composite films can be enhanced effectively by adding PPy-TiO2.When the filling amount is 30 wt%, the energy storage density of PVDF/PPy-TiO2/PVDF sandwich-structured composite films is outstanding before the breakdown strength, which is higher than that of the pure PVDF film. The energy storage density of PVDF/PPy-TiO2/PVDF sandwich-structured composite films could be achieved to 2.68 J/cm3 under the electric strength of 1700 kV/cm.