G. E. Welsch, D. McGervey, Case Western Reserve University, Cleveland, OH; J. W. Ki, formerly PhD student at CWRU, now at POSCO, Pohang, South Korea
High-purity titanium and tailored titanium alloys can serve as electrodes and dielectric substrate in electrolytic supercapacitors. Alloy composition and surface-modification processing play critical roles in the generation of titanium-supported dielectric film. Chemical stoichiometry and structural integrity at the atomic scale are essential for the formation of a dielectric with high field strength and low leakage current. These are requisites for high energy density. Additionally, a nanometer-scale open-porous titanium topography provides high specific surface area and a low series-resistance electrical connectivity. Design principles based on pure titanium and on Ti-alloys will be presented. Experimental data from first generation 'titanium spine electrodes' show their potential for high combined energy density and power. [Acknowledgement: Research support by NRO]
Summary: High-purity titanium and selected alloys are suited as electrodes for high-energy-density electrolytic capacitors. The alloy composition and the processing conditions play critical roles in the auto-generation of titanium-supported dielectric films with structure integrity in the sub-nm range to enable high electric field strength and low leakage current, requisites of a high-energy-density capacitor. We will discuss the Ti-alloy and electrode design principles and present experimental results that show the potential for high energy density and high power.
