Outstanding discharge energy density and efficiency of the bilayer nanocomposite films with BaTiO3-dispersed PVDF polymer and polyetherimide layer

Dielectric polymer nanocomposite films have been widely studied because of their high polarization and electric breakdown strength, leading to high discharge energy density (U d ). However, nanocomposites with high U d often show low discharge energy efficiency (η). In order to achieve both high U d and η simultaneously, a series of novel bilayer polymer nanocomposite films composed of pure polyetherimide (PEI) layer and BaTiO 3 -dispersed poly(1,1-difluoroethylene) (BT/PVDF) layer were prepared by hot-pressing method in this work. The bilayer composites exhibit high η > 84% at 600 MV⋅m −1 , which are much larger than most reported values (η < 70%). Specially, the highest η of 84.48% and U d of 8 J·cm −3 at 600 MV·m −1 were obtained for the bilayer films composed of PEI and 3 vol% BT/PVDF layers, which is promising for pulsed power applications.