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Long-term stability of composite cathode at high current densities

Langzeitstabilität der Verbundkathode bei hohen Stromdichten
 
: Kusnezoff, M.; Trofimenko, N.; Mosch, S.; Beckert, W.; Graff, A.; Altmann, F.

:

Eguchi, K.; Mizusaki, J.; Singhal, S.; Yokokawa, H. ; Electrochemical Society -ECS-:
Solid Oxide Fuel Cells 10 (SOFC-X). Vol.1 : 10th International Symposium on Solid Oxide Fuel Cells (SOFC-X), June 3-June 8, 2007, Nara, Japan
Pennington, NJ: ECS, 2007 (ECS transactions 7.2007,Nr.1)
ISBN: 978-1-566-77555-7
ISBN: 978-1-566-77554-0
pp.1033-1040
International Symposium on Solid Oxide Fuel Cells (SOFC) <10, 2007, Nara>
English
Conference Paper, Journal Article
Fraunhofer IKTS ()
Fraunhofer IWM ()
Festoxidbrennstoffzelle; Kathodenwerkstoff; Lebensdauerprüfung; yttriumoxidstabilisiertes Zirkoniumoxid; Scandiumoxid; Impedanzspektrometrie; Manganit; Betriebsbedingung; Langzeitprüfung; Cermet; Mikrostruktur; Rasterelektronenmikroskopie; Transmissionselektronenmikroskopie; Simultansintern; Stromdichte

Abstract
The durability tests were carried out on substrate supported cells based on yttria and scandia stabilized zirconia (YSZ and ScSZ) with conventional A-site deficient lanthanum strontium manganite(uLSM)/YSZ and Ni/YSZ electrodes. The cells were operated at 850 deg C in air/H2:H2O (1:1) for more than 1000 h at current densities >450 mA/cm(exp 2). The reduction of the cathode polarization resistance is observed from the analysis of the impedance spectra. Microstructure investigations of the composite cathode using FESEM and TEM revealed that the composite cathode undergoes morphology changes during the first 200-500 h of the operation creating some nano-porosity at the uLSM/YSZ interface. Furthermore it was found that the change of the microstructure is strongly affected by the magnitude of the current density. The depth of the electrochemically structured zone as well as the change of the uLSM-composition at the uLSM/YSZ-interface was investigated using transmission electron microscopy.

: http://publica.fraunhofer.de/documents/N-58697.html