Chapter 35. Microstructure-Performance Relationships in Lsm-Ysz Cathodes
- 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
Ruud, J. A., Striker, T., Midha, V., Ramamurthi, B. N., Linsebigler, A. L. and Fogelman, D. J. (2004) Microstructure-Performance Relationships in Lsm-Ysz Cathodes, 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.ch35
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 2004
Print ISBN: 9780470051498
Online ISBN: 9780470291184
Quantitative methods for engineering efficient solid oxide fuel cell (SOFC) composite electrodes are presented. Four strontium-doped lanthanum manganite (LSM)- yttria-stabilized zirconia (YSZ) microstructures were produced by varying batching and sintering conditions. the microstructures were imaged using scanning electron microscopy (SEM) and the phases were identified using scanning Auger analysis. Cathode microstructure was quantified through stereographical analysis of the size distributions and volume fractions of the phases.
Performance of cathodes of various thicknesses was measured using 4-wire symmetric single atmosphere air AC impedance spectroscopy as a function of temperature. All microstructures showed a decrease in total resistance (polarization and ohmic) as the thickness increased up to a critical thickness at which the resistance remained constant. Microstructures with smaller particle sizes had lower resistances, as expected.
The effect of microstructure on performance was modeled analytically based on a particle percolation model. As inputs, the model used temperature-independent microstructural parameters (active area, degree of particle necking), and temperature-dependent parameters (exchange current density, YSZ ionic conductivity, LSM electronic conductivity). Good agreement between the model and the data was observed over a range of microstructures and measurement temperatures. the exchange current density and the active surface area were determined independently from the model fits. the methods can be extended to composite anode microstructures, such as Ni-YSZ or to advanced cathode microstructures.