Morphological and Electrical Stability Studies of Pt/Yttria-Stabilized Zirconia Nanocomposite Thin Film Cathodes for Microfabricated Solid Oxide Fuel Cells

Microfabricated solid oxide fuel cells (mSOFCs) have recently gained attention as a promising technology for portable power applications. At present, porous Pt is the most common cathode being investigated for mSOFCs, which has poor bulk ionic conductivity and suffers from instability due to Ostwald ripening. Nanocomposite materials based on Pt/Yttria-Stabilized Zirconia (YSZ) are a promising alternative approach for high performance mSOFCs because of their potential for providing mixed ionic-electronic conduction, improving adhesion to the YSZ electrolyte, and improving oxygen diffusion characteristics over a pure Pt material. The objective of this research was to systematically explore the processing of the nanocomposite thin films to achieve stable morphological and electrical properties for use as a mSOFC cathode. A percolation theory model was utilized to guide the processing of the Pt/YSZ composition, ensuring a networked connection of ionic- and electronic-conduction through the electrode. The Pt/YSZ nanocomposite cathodes were deposited by co-sputtering. It was observed that the Ar deposition pressure played a key role in stabilizing the morphology of the film to higher temperatures, up of 600°C. Analyses of the Pt/YSZ composite microstructure and composition by TEM confirmed an interconnected network of Pt and YSZ thereby suggesting that it is a viable candidate as a high performance and stable cathode material for mSOFCs.