Anomalous Ohmic Loss in Solid Oxide Fuel Cells with Doped Ceria Interlayers

The ohmic resistance of an anode-supported SOFC is usually composed of contributions from the following parts: anode, electrolyte, cathode, and contact between the cell components. All of the ohmic resistances of cell components should be as small as possible to achieve an efficient SOFC operation. It is often believed that most of the ohmic resistance attributes to the electrolyte since the ionic conductivity of the electrolyte is usually several orders of magnitude lower than the electrical conductivities of the electrodes.

In an SOFC single cell with YSZ as the electrolyte, however, the contribution of the electrolyte to the total ohmic resistance of the anode-supported SOFC has not yet been fully understood despite of the numerous studies in this area. Several groups reported that the YSZ films in real SOFC environment showed lower ionic conductivities than that of the bulk YSZ material. This is especially true when the doped ceria is screen printed on YSZ-based single cell, in which the magnitude of the ohmic losses in the cell was observed more than three times greater than that for YSZ.  The aim of this paper is to address the origin of the exaggerated ohmic resistance.