A Study of SOFC Cathode Degradation in H2O Environments

Monday, 6 October 2014: 14:40
Sunrise, 2nd Floor, Galactic Ballroom 5 (Moon Palace Resort)
C. Pellegrinelli, Y. L. Huang, J. A. Taillon, L. G. Salamanca-Riba, and E. D. Wachsman (University of Maryland)
An understanding of the degradation mechanisms of SOFC cathodes under operating conditions is essential for the development of commercial, low temperature (<700°C) SOFCs with high performance. Literature shows that the presence of H2O in the cathode impacts the performance of SOFCs. In this study, we attempt to determine the degradation mechanisms of two SOFC cathodes ((La0.8Sr0.2)0.95MnO3-x (LSM) and La0.6Sr0.4Co0.2Fe0.8O3-x (LSCF)) in H2O based on a multi-faceted approach. LSM-YSZ/YSZ/LSM-YSZ and LSCF-GDC/GDC/LSCF-GDC symmetric cells will be examined in the presence of the contaminant (H2O) under different cycling, polarization and working conditions. Symmetric cell performance will be measured by in-situ electrochemical impedance spectrometry (EIS), and directly compared to quantitative microstructural parameters obtained from FIB-SEM 3D reconstructions. FIB-SEM is a powerful technique that can help us visualize the complex cathode/electrolyte microstructure, and allow us to quantify important performance characteristics such as triple phase boundary (TPB) length and surface to volume ratio. EIS and FIB-SEM results will then be compared to kinetic rate data, determined by isotope exchange experiments, to determine correlations.