A novel aromatic polyurea for high energy density capacitors

Abstract

Dielectric film capacitors with high energy density represent some of the most pervasive devices used in electrical and electronic systems. With the rapid growing demands in electrification, new polymer film dielectrics with high dielectric constant and high breakdown strength are needed. A toluene diisocyanate (TDI) based organic polymer with a flexible diaminoether backbone (EDR148™) was synthesized and fabricated into ∼10 μm films by a blade cast method. Systematic dielectric spectroscopy study was performed to characterize the complex dielectric spectra over a broad range of frequencies and temperatures to probe global, segmental, and local relaxations. Furthermore, high field characterizations were conducted by using a D-E polarization loop tester and a specially designed pre-breakdown conduction measurement system for the fundamental understanding of the relationship between molecular structure and high filed polarization and breakdown. TDI-EDR148 exhibited a high dielectric constant of > 6 with a low loss factor of ∼1.5% and a high breakdown strength of >600 MV/m. These properties represent a high energy density of ∼12 J/cc for this aromatic polyuria film. The result was compared with a previously studied high K polymer to correlate and reveal mechanism leading to the design of polymers with high dipolar energy density.