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

Development of nanolayer polymer films demonstrated a new class of dielectric film materials for high energy density and high temperature capacitor applications. Current state-of-the-art biaxially oriented polypropylene (BOPP) dielectric films are limited by low dielectric constant (e = 2.25), low energy density and deteriorated high temperature performance. In contrast, multilayer film technology offers nanolayer dielectric films using COTS materials with high temperature performance (>125 °C), high dielectric constant (4-6, 1.7X to 2.2X higher than BOPP dielectric constant), high breakdown strength (800-1000 MV/m) and low tan delta losses due to synergistic effects of component polymers. These improved properties as compared to BOPP films can translate into significantly smaller capacitor prototypes while allowing higher temperature performance at comparable dielectric film thickness. Technology feasibility at PolymerPlus was also demonstrated by several film production scale-up trials, metallization trials, and fabrication of several small capacitor prototypes (up to 100 Joules) for next generation film capacitors for DoD and commercial applications. Further work to improve film quality, metallization efficiency and fabrication of capacitors toward specific applications are keys to advancing this technology to next TRL levels as proposed.