Fast discharge, high energy density capacitor performance

Abstract

Film capacitors with energy densities of greater than 1 J/cc and suitable for millisecond and microsecond discharge applications requiring limited life have been characterized. A variety of polymer films have been tested in model capacitors storing and delivering hundreds of Joules of energy at voltages of 2-10 kV. Self-healing metallized film electrodes have been 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 have been determined. Design modifications to increase life and energy density were made based on those analyses. Full-scale capacitors in the 10 kJ to 300 kJ range have been manufactured and tested to end of life