Effect of synthesis conditions on the performance of Cu-CeO2-YSZ anodes in SOFCs

The effect that synthesis procedures have on the performance of Cu-CeO2-YSZ (yttria-stabilized zirconia! anodes for solid oxide fuel cells (SOFC) has been investigated. Using a fixed concentration of 20 wt % Cu and 10 wt % CeO2, impregnated into a porous YSZ matrix using metal salts, it is shown that the methods used to prepare CeO2 and Cu have a large effect on the cell performance. Direct reduction of Cu(NO3)(2) to Cu, without intermediate calcination to CuOx, results in Cu films that have better electrical connectivity, but this does not enhance the final cell performance after exposure to n-butane. The calcination temperature for preparing CeO2 from Ce(NO3)(3) has a much more significant effect, with the area-specific resistance (ASR) of the anode in H-2 at 973 K increasing from 0.8 Omega cm(2) at 723 K to >1.8 Omega cm(2) at 1273 K and >2.6 Omega cm(2) at 1523 K. X-ray diffraction results indicate that most of the ceria has not formed a solid solution, even at 1523 K. The cell performance is also affected by the solvent used for impregnation of CeO2. Forming the CeO2 film with (NH4)(2)Ce(NO3)(6) in ethanol resulted in a cell with an anode ASR of similar to0.4 Omega cm(2). Possible reasons for the strong dependence of the ceria film on cell performance are discussed. (C) 2003 The Electrochemical Society.