Titanate Capacitors for Power Electronics

Abstract

Titanium alloys were synthesized and coated with oxide dielectric films using anodizing in electrolytic baths. They possess high specific energies based on high charge-densities and high breakdown-electric-fields. These were made into alloy ribbons by rapid solidification by vacuum-spin casting, then anodized to form homogeneous dielectric films that serve as the medium in which electric charges are stored with high specific energy density in electrolytic capacitors. The new energy-dense dielectrics were formed by anodizing homogeneous Ti-Zr-X anode alloys, where X is a combination of Hf, Nb, Mo, Be, and/or Si. Thus homogeneous, dense and essentially-defect-free oxide-glass films were formed, e.g., (Ti-Zr-Hf-Be)O 2 films with high specific energy with stability over a wide voltage range, up to over 300 Volt, at temperatures from cryogenic to over 100 degrees C. When packaged with oxidizing electrolyte the dielectric is self-repairing in the event that accidental defects spring up. This provides reliable high-energy and high power performance with little de-rating, i.e., high reliability and lifetime in pulsed or high-frequency operating conditions.