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

Current state-of-the-art biaxial oriented polypropylene (BOPP) polymer film capacitors exhibit excellent room temperature performance, however, possesses at least two major drawbacks. Wound BOPP capacitors usually occupy one-third to one-half of the volume of pulsed power and power conditioning units, and their performance above 85 degrees C significantly decreases. These problems can be alleviated by increasing the energy storage while maintaining low losses at both ambient and elevated temperatures. The objectives of this Phase I SBIR proposal are to develop further and to optimize the dielectric performance of poly(vinylidene fluoride) (PVDF)-based multilayer films discovered at the National Science Foundation Center for Layered Polymeric Systems (CLiPS) which meet these goals and to demonstrate their viability for large-scale film production, utilizing the multilayer film coextrusion technology developed at Case Western Reserve University and PolymerPlus LLC. The film performance will be optimized in terms of ferroelectric/dielectric polymer pairs, composition, layer thickness and number of layers, temperature, and biaxial stretching. Detailed technical goals are to achieve energy density>10 J/cm3 at electric breakdown, dielectric loss (tan delta) 500 MV/m) and at high temperatures (e.g., 125 degrees C) to meet Navy"s needs for all electric ships.