Chapter 38. Improved Sofc Cathodes and Cathode Contact Layers
- Edgar Lara-Curzio and
- Michael J. Readey
Published Online: 26 MAR 2008
Copyright © 2004 The American Ceramic Society
28th International Conference on Advanced Ceramics and Composites A: Ceramic Engineering and Science Proceedings, Volume 25, Issue 3
How to Cite
Tietz, F., Buchkremer, H.-P., Haanappel, V. A. C., Mai, A., Menzler, N. H., Mertens, J., Quadakkers, W. J., Rutenbeck, D., Uhlenbruck, S., Zahid, M. and Stöver, D. (2004) Improved Sofc Cathodes and Cathode Contact Layers, in 28th International Conference on Advanced Ceramics and Composites A: Ceramic Engineering and Science Proceedings, Volume 25, Issue 3 (eds E. Lara-Curzio and M. J. Readey), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291184.ch38
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 2004
Print ISBN: 9780470051498
Online ISBN: 9780470291184
SOFC development at Forschungszentrum Jülich is aiming at high power density and high durability to achieve cost reduction in manufacturing and installation. For higher power density the work on materials development has been focused on improving the cathode performance by modification of the component thickness, the microstructure and the choice of materials. All investigations were first carried out with 5×5 cm2 cells and, if appropriate, scaled up to cells having a size of 10 × 10 and 20 × 20 cm2.
In the case of (La, Sr)MnO3-based cathodes the power output was nearly doubled reproducibly from 0.56 to 1.0 W/cm2 at 800°C and 0.7 V by varying the (La, Sr)MnO3/YSZ ratio in the composite layer as well as the grain size in and the thickness of both the composite layer and the overlaid pure (La, Sr)MnO3 layer. in addition, SOFCs with cathodes based on (La, Sr)(Fe, Co)O3 have successfully been developed giving a power output of 1.2 W/cm2 at the same experimental conditions. Similar performance was achieved by depositing the cathode using either wet powder spraying or screen printing. A prerequisite for comparing different cathodes is the reliable and quality-assured fabrication of all other cell components.
For improved durability the development of cathodic contact materials was directed towards a reduced interaction between the ceramic materials and the ferritic steel used as interconnect material. Several materials solutions are available in which the contact resistance remains constant below 70 mΩ cm2 within the first 1500 h of testing. Currently, contact materials are under development that do not only show a reliable and low contact resistance but simultaneously act as a diffusion barrier for the chromium that is released from the interconnect.