Proc. 6 th International Symposium on Solid Oxide Fuel Cells (SOFC-VI) ed. S. C. Singhal et al., Honolulu, Hawaii, Oct. 17-22, 1999 LBNL-43185 May, 1999 PROMISES AND PROBLEMS WITH METALLIC INTERCONNECTS FOR REDUCED TEMPERATURE SOLID OXIDE FUEL CELLS Peggy Y. Hou, Keqin Huang † and Wate T. Bakker* Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley, CA 94720 Texas Materials Institute, ETC 9.102 The University of Texas at Austin Austin, TX 78713 *Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94304 ABSTRACT The oxidation kinetics and electrical properties of oxide scales thermally grown on the surface of a commercial iron-based alloy have been investigated up to 1000 o C. The effect of surface coating to improve performance was studied, and it was found that a double coating of Y and Ni oxide was most beneficial. While the Y oxide reduced the oxidation rate, the Ni oxide increased the Cr 2 O 3 scale conductivity. Different electrodes were applied to the alloy or to pre-oxidized samples. Some of the electrodes, such as LaSrCoO 3 (LSCo), reacted strongly with the alloy upon oxidation by increasing the oxidation rate and forming a mixed Fe/Co/Cr interlayer that impeded conduction. Application of these electrodes to a pre-oxidized surface eliminated these problems. Preliminary results in reducing atmosphere using Ce 0.8 +Sm 0.2 O 1.9 +Ni and Pt electrodes are also reported. The possibility of using Cr 2 O 3 forming alloys as interconnects for low temperature solid oxide fuel cell is discussed in light of these results. INTRODUCTION The trend in planar solid oxide fuel cell (SOFC) development is towards lower temperature operation. This has several advantages such as the elimination of interdiffusion between electrodes and electrolytes, ease of internal reforming and the use of relatively low cost metallic interconnects and balance of plant components. Several methods to operate at low temperatures have been identified and demonstrated at a single cell level. The most prominent are the use of thin film, conventional doped zirconia electrolytes (1,2) and the use of a recently discovered new electrolyte, doped lanthanum