High Temperature, High Energy Density Film Capacitors

Production of long life, light weight, high-volumetric-energy-density, high-voltage bus capacitors, which are stable at temperatures over 250C, would enable the electrical system of an electric vehicle to operate at a higher temperature, thereby readying these systems for next-generation SiC-based components. The key to producing these capacitors is through improvements in the capacitor dielectric. Properties such as dielectric strength, temperature stability, and dielectric constant need to be improved over tradition materials. This project will investigate the use of flexible amorphous hafnium dioxide films as a dielectric. Amorphous oxides can have a dielectric constant >25 and breakdown strength in excess of 400 V/micron, and, due to their flexibility, they can be rolled into various compact shapes. These properties make them ideal for improving the temperature stability, durability, and weight of the high voltage bus capacitors found in electric vehicles. In Phase I, amorphous HfO2 dielectric films were deposited on glass and polyimide substrates and tested to demonstrate that HfO2 is an ideal dielectric for the fabrication of high capacitance wound capacitors. Commercial Applications and other Benefits as described by the awardee: Development of an improved dielectric material for capacitors would allow development of a new generation of compact, high-voltage, temperature-stable capacitors that would have many applications, both in commercial and military markets. In particular, these capacitors should find use as bus capacitors in electric vehicles. Temperature tolerant capacitors also could be used in conjunction with wide bandgap materials for the next generation of high temperature electronics