Enhancing the Redox Tolerance of Anode-Supported SOFC by Microstructural Modification

The most commonly used solid oxide fuel cell (SOFC) anode material is a two-phase, nickel- and yttria-stabilized zirconia cermet. During fuel cell operation, this material is exposed to a reducing environment and thus remains a cermet; however, the metallic component of the anode may reoxidize in a commercial SOFC system. Following an initial study of the redox kinetics and dimensional changes after reduction and oxidation, as well as a baseline characterization of the electrochemical performance degradation and microstructural changes after redox cycling, two modifications to the anode microstructure were made in order to enhance cell redox tolerance: the anode functional layer was functionally graded and an oxidation barrier layer was added to the bottom of the cell in order to restrict the ability of oxygen to flow into the anode. Both types of microstructural modification significantly improved the cell redox tolerance compared with standard baseline redox tests.