TY - JOUR
T1 - Degradation mechanisms of porous La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-δ solid oxide fuel cell cathodes
AU - Wang, Hongqian
AU - Barnett, Scott A.
N1 - Funding Information:
The authors gratefully acknowledge financial support by the US National Science Foundation grant # DMR-1506925. The authors also acknowledge the assistance of the Electron Probe Instrumentation Center (EPIC) at the NUANCE Center-Northwestern University, which has received support from the soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. The metal analysis was performed at the Northwestern University Quantitative Bio-element Imaging Center.
Publisher Copyright:
© 2018 The Electrochemical Society.
PY - 2018
Y1 - 2018
N2 - La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-δ (LSCF) symmetric-electrode cells with Gd0.1Ce0.9O1.95 (GDC) electrolytes were aged in ambient air at temperatures ranging from 550 to 950°C for times up to 1400 h, without current/polarization. Electrochemical impedance spectroscopy measurements, taken periodically during the tests at a testing temperature of 700°C for cells aged at 700, 750 and 800°C, showed a continuous increase in polarization resistance. Focused ion beam-scanning electron microscopy (FIB-SEM) 3D tomography showed that the LSCF electrode did not coarsen measurably at ageing temperatures ≤ 800°C, ruling out LSCF microstructural changes as the mechanism behind the resistance increase. On the other hand, Sr surface segregation, determined by chemical etching with inductively coupled plasma-optical emission spectrometry (ICP-OES) detection, was found to increase with increasing ageing time and temperature > 650°C. The effect of Sr surface segregation on the oxygen surface exchange and diffusion processes is quantified by comparing the measured electrochemical and microstructural data.
AB - La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-δ (LSCF) symmetric-electrode cells with Gd0.1Ce0.9O1.95 (GDC) electrolytes were aged in ambient air at temperatures ranging from 550 to 950°C for times up to 1400 h, without current/polarization. Electrochemical impedance spectroscopy measurements, taken periodically during the tests at a testing temperature of 700°C for cells aged at 700, 750 and 800°C, showed a continuous increase in polarization resistance. Focused ion beam-scanning electron microscopy (FIB-SEM) 3D tomography showed that the LSCF electrode did not coarsen measurably at ageing temperatures ≤ 800°C, ruling out LSCF microstructural changes as the mechanism behind the resistance increase. On the other hand, Sr surface segregation, determined by chemical etching with inductively coupled plasma-optical emission spectrometry (ICP-OES) detection, was found to increase with increasing ageing time and temperature > 650°C. The effect of Sr surface segregation on the oxygen surface exchange and diffusion processes is quantified by comparing the measured electrochemical and microstructural data.
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U2 - 10.1149/2.1211807jes
DO - 10.1149/2.1211807jes
M3 - Article
AN - SCOPUS:85060725983
SN - 0013-4651
VL - 165
SP - F564-F570
JO - Journal of the Electrochemical Society
JF - Journal of the Electrochemical Society
IS - 7
ER -
