Development and Processing of Dielectric Films for Application in Large Wound Capacitors

Current state-of-the-art biaxially oriented polypropylene (BOPP) polymer film capacitors exhibit excellent room temperature performance, but show significant deterioration in properties above 85 C. In Phase I, poly(vinylidene fluoride) (PVDF) and polycarbonate (PC) multilayer films were found to demonstrate excellent room temperature and high temperature performance. The viability of the technology for large-scale film process development on a near commercial coextrusion facility was also demonstrated in Phase I. In Phase II, PolymerPlus LLC will optimize these PVDF/PC films by studying the effect of processing variables on film morphology and dielectric properties, downselect and process multilayered films for prototype capacitor fabrication, fabricate demonstrative prototype capacitors, and develop a manufacturing process which is ready for scale up to commercial operation. The specific goal of Phase II is to deliver several 10-joule capacitors with 1 kHz discharge time, high temperature performance (up to 120 C) and a wound capacitor energy density of 2 J/cc. Other high temperature polymers will also be investigated to expand the film storage capability of the technology, which will allow for broader acceptance in capacitor applications.