Lattice Expansion of LSCF-6428 Cathodes Measured by In-situ XRD during SOFC Operation

Journal Article · Tue Jan 03 04:00:00 EST 2012 · Journal of Power Sources, 198:76-82

DOI:https://doi.org/10.1016/j.jpowsour.2011.09.099· OSTI ID:1033449

Hardy, John S; Templeton, Jared W; Edwards, Danny J; Lu, Zigui; Stevenson, Jeffry W

A new capability has been developed for analyzing solid oxide fuel cells (SOFCs). This paper describes the initial results of in-situ x-ray diffraction (XRD) of the cathode on an operating anode-supported solid oxide fuel cell. It has been demonstrated that XRD measurements of the cathode can be performed simultaneously with electrochemical measurements of cell performance or electrochemical impedance spectroscopy (EIS). While improvements to the technique are still to be made, the XRD pattern of a lanthanum strontium cobalt ferrite (LSCF) cathode with the composition La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF-6428) was found to continually but gradually change over the course of more than 60 hours of operation in air under typical SOFC operating conditions. It was determined that the most significant change was a gradual increase in the cubic lattice parameters of the LSCF from 3.92502 Å (as determined from the integration of the first 20 hours of XRD patterns) to 3.92650 Å (from the integration of the last 20 hours). This analysis also revealed that there were several peaks from unidentified minor phases that increased in intensity over this timeframe. After a temporary loss of airflow early in the test, the cell generated between 225 and 250 mW/cm2 for the remainder of the test. A large low frequency arc in the impedance spectra suggests the cell performance was gas diffusion limited and that there is room for improvement in air delivery to the cell.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1033449
• Report Number(s): PNNL-SA-82491; AA2530000
• Journal Information: Journal of Power Sources, 198:76-82, Journal Name: Journal of Power Sources, 198:76-82 Vol. 198; ISSN JPSODZ; ISSN 0378-7753
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
AIR
CATHODES
COBALT
CUBIC LATTICES
Cathode
DIFFUSION
FERRITE
IMPEDANCE
In-situ XRD
LANTHANUM
LSCF
Lattice Strain
PERFORMANCE
SOFC
SOLID OXIDE FUEL CELLS
SPECTRA
SPECTROSCOPY
STRONTIUM
Segregation
X-RAY DIFFRACTION