Recent results in the development of composites for high energy density capacitors

The development of novel composites is ongoing in an effort to develop materials with an energy density greater than 5 J/cm³ for use in high voltage capacitors. The materials are composites initially developed to reduce the size of high power antennas. Due to their combination of a high dielectric constant and high dielectric strength, some of the original composites were directly transitioned for evaluation in high voltage, high energy density capacitors while others required modifications to reduce DC leakage current or to make other optimizations for the capacitor application. Recent testing has focused on dielectric strength testing to determine breakdown field levels during short pulse conditions. This initial work has included experiments with the methods of surface preparation and electrode application as well as modifications to the structure and chemistry of some candidate composites. Results are presented on the dielectric strength and dielectric constant of one of the candidate composite materials with various electrode structures designed to reduce field enhancements. Practical operating electric field levels are determined from an analysis of the breakdown data, and energy densities are projected for high energy density capacitor designs.