The past decades have witnessed the increasing interest in polymer film capacitors with enhanced energy density, low dielectric loss, and high temperature tolerance for advanced electrical and power applications. The state-of-the-art multilayer coextrusion technology at Case Western Reserve University has been demonstrated to be a promising strategy for this purpose. In these multilayer films, a high breakdown dielectric polymer [e.g., polycarbonate (PC) or polysulfone (PSF)] is multilayered with a high energy density polymer [e.g., poly(vinylidene fluoride) (PVDF) and its random copolymers]. It is found that impurity ion conduction in PVDF layers, rather than PVDF dipole switching, is responsible for the dielectric loss. In this study, unipolar electric poling at a temperature slightly below the glass transition temperature (T<sub>g</sub>) of PSF was utilized to drive the impurity ions from the PVDF layers to the PSF layers. After cooling far below the T<sub>g</sub> of PSF, these impurity ions were trapped in the frozen PSF layers. Consequently, the dielectric loss from impurity ion conduction could be effectively reduced. In the future, we will investigate the effect of interfacial charges to further enhance the insulation properties for multilayer films.

Reduction of ionic conduction loss in multilayer polymer films for electric energy storage application

254th National Meeting (2017)

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