High energy density capacitor characterization

This paper will describe how film capacitors with energy densities of greater than 1 J/cc and suitable for millisecond discharge applications requiring limited life have been characterized. A variety of polymer films were tested in "model" capacitors storing and delivering hundreds of Joules of energy at voltages of 2-10 kV. Self-healing metallized film electrodes were utilized in these designs to achieve electric fields greater than 500 MV/m. Maximum operating voltage for short-term and long-term use was determined. Life tests were then performed with the goal of achieving at least 1000 charge/discharge cycles at maximum energy density. Degradation and failure of the capacitor samples was determined by measurements of capacitance and dissipation factor. Failure modes in continuous DC, normal charge/discharge pulse service, and short-circuit fault conditions were determined. Design modifications to increase life and energy density were made based on those analyses. Scale-up of the individual unit energy to 100 kJ is underway