Mechanisms of Performance Degradation of (La, Sr)(Co, Fe)O3-δ Solid Oxide Fuel Cell Cathodes. Issue 6 (26th March 2016)

• Record Type: Journal Article
• Authors: Wang, Hongqian; Yakal-Kremski, Kyle J.; Yeh, Ted; Rupp, Ghislain M.; Limbeck, Andreas; Fleig, Jürgen; Barnett, Scott A.
• Is Part Of: Journal of the Electrochemical Society. Volume 163:Issue 6(2016)
• Page Start: F581
• Page End: F585
• Publication Date: 2016-03-26
• Subjects: 3D tomography -- solid oxide fuel cell -- Sr segregation -- symmetric cell; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0031607jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Symmetric cells with porous La0.6 Sr0.4 Co0.2 Fe0.8 O3-δ (LSCF) electrodes on Gd0.1 Ce0.9 O1.95 (GDC) electrolytes were aged at 800°C for 800 hours in ambient air. Electrochemical impedance spectroscopy (EIS) measurements performed periodically at 700°C showed a continuous increase of the polarization resistance from 0.15 to 0.34 Ω·cm 2 . Three-dimensional (3D) tomographic analysis using focused ion beam–scanning electron microscopy (FIB-SEM) showed negligible changes due to the ageing, suggesting that the observed resistance increase was not caused by electrode morphological evolution. However, an increased amount, by a factor of 3, of a water-soluble Sr rich surface phase on the aged LSCF electrode was detected by an etching procedure coupled with inductively coupled plasma-optical emission spectrometry (ICP-OES). The electrochemical analysis in combination with the microstructural parameters determined by FIB-SEM was used to examine the effect of Sr segregation on the rate of oxygen surface exchange, based on the Adler-Lane-Steele (ALS) model.