Characterization of thin-film YSZ deposited via EB-PVD technique in anode-supported SOFCs

Abstract

An anode-supported solid oxide fuel cell (SOFC) based on 8 mol % yttria-stabilized zirconia (8YSZ) electrolyte that was deposited via an electron-beam physical vapor deposition (EB-PVD) technique, was investigated. A NiO-8YSZ plate was used as both an anode substrate and as a substrate for the deposition of 8YSZ. An additional buffering layer was coated on the anode substrate via a screen printing before the deposition of YSZ film in order to enhance the surface smoothness for the film deposition. In this study, we controlled various experimental variables for the film deposition and subsequent heat treatment process to obtain highly dense and impervious electrolyte film. Consequently, we were able to obtain a large area (12 x 12 cm) and dense YSZ film with a uniform thickness of similar to 8 mu m. The surface and cross-sectional microstructure and the corresponding phase of deposited film were thoroughly analyzed by scanning electron microscopy and X-ray diffraction. The electrochemical performance of the EB-PVD unit cell was investigated using dc current-voltage load testing, a dc current interruption technique, and an ac-impedance spectroscopy. Peculiar microstructural features of the deposited film, such as the columnar structure of grains along the growing axis, and the film's microstructural effect on unit cell performance, were addressed. (C) 2006 The Electrochemical Society.