Electrical breakdown in capacitor dielectric films: Scaling laws and the role of self-healing

Despite a great number of reports on high-energy density dielectric materials, very little attention is paid to determining realistic energy densities of larger scale devices made of these materials. These materials are typically evaluated with very short duration voltage withstand tests on very small sample areas, typically on the order of a few seconds and a few cm2. Conversely, full-scale devices require very long operational lifetimes on the order of years, and dielectric areas as large as several hundreds of m2. Practical components must also include additional material such as major insulation and packaging, resulting in volumetric efficiencies much less than 100%. Increases in total dielectric area, operating time, and packaging inefficiencies reduce practical energy densities by one to two orders of magnitude. Here we highlight the limitations of scaling up such results to high energy density capacitors as well as demonstrate the effect of self-healing and its necessity in high-energy-density, high-total-energy devices.