[en] Degradation processes of oxygen electrodes in solid oxide electrolysis cells (SOECs) were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Mössbauer spectroscopy. La0.58Sr0.4Fe0.5Co0.5O3−x (LSCF) anodes (oxygen electrode) were analyzed after different longterm operations durations of 1774, 6100 and 9000 h. The results were compared with a cell in the initial state. Besides the LSCF anode, the SOECs were composed of a Ce0.8Gd0.2O1.9 barrier layer between the anode and electrolyte, yttria-stabilized zirconia (YSZ) as electrolyte and Ni-YSZ as cathode (hydrogen electrode). Mössbauer spectra of the iron-containing anode were acquired in order to determine the alteration of the iron oxidation state and its local environment during operation. Mössbauer spectroscopy yields indirect information about the degradation mechanism, especially in combination with SEM, TEM, and XRD. XRD and TEM revealed the appearance of Co3O4 during the SOEC operation and SEM analyses confirmed the formation of SrZrO3 at the electrode/electrolyte interface. The spectral analysis confirmed the reduction of iron from Fe(IV) to Fe(III) in LSCF after long-term operation. The fraction of Fe(IV) in the electrode decreased with time and 18, 15, 13 and 11% were obtained for 0, 1774, 6100, and 9000 h of operation, respectively.
Disciplines :
Chemistry
Author, co-author :
Mahmoud, Abdelfattah ; Université de Liège - ULiège > Département de chimie (sciences) > LCIS - GreenMAT
Al Daroukh, Mahmoud
Lipinska-Chwalek, Marta
Luysberg, Martina
Tietz, Frank
Hermann, Raphaël ; Université de Liège - ULiège > Département de chimie (sciences) > Département de chimie (sciences)
Language :
English
Title :
A Mössbauer spectral study of degradation in La0.58Sr0.4Fe0.5Co0.5O3−x after long-term operation in solid oxide electrolysis cells
Publication date :
06 October 2017
Journal title :
Solid State Ionics
ISSN :
0167-2738
Publisher :
Elsevier Science, Amsterdam, Netherlands
Volume :
312
Pages :
38-43
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
DGTRE - Région wallonne. Direction générale des Technologies, de la Recherche et de l'Énergie [BE]
Tietz, F., Haanappel, V.A.C., Mai, A., Mertens, J., Stöver, D., J. Power Sources 156 (2006), 20–22.
The, D., Grieshammer, S., Schröder, M., Martin, M., Tietz, F., Brisse, A., Al Daroukh, M., Schefold, J., J. Power Sources 275 (2015), 901–911.
Schefold, J., Brisse, A., Tietz, F., J. Electrochem. Soc. 159:2 (2012), A137–A144.
Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), FEI Helios NanoLab 400S FIB-SEM. J. Large-Scale Res. Fac., 2, 2016, A60, 10.17815/jlsrf-2-106.
Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), FEI Titan G2 80-200 CREWLEY. J. Large-Scale Res. Fac., 2, 2016, A43, 10.17815/jlsrf-2-68.
Al Daroukh, M., Tietz, F., Sebold, D., Buchkremer, H.P., Ionics 21 (2015), 1039–1043.
Schefold, J., Brisse, A., ECS Trans. 53:9 (2013), 53–61.
JCPDS, 49-285 File. ICDD PDF-2 Release. 2008, Joint Committee on Powder Diffraction Standards 411 (JCPDS) — International Centre for Diffraction Data (ICDD), Pennsylvania 412 Powder Diffraction File (PDF) database.
Mineshige, A., Izutsu, J., Nakamura, M., Nigaki, K., Abe, J., Kobune, M., Fujii, S., Yazawa, T., Solid State Ionics 176 (2005), 1145–1149.
Mineshige, A., Inaba, M., Yao, T., Ogumi, Z., Kikuchi, K., Kawase, M., J. Solid State Chem. 121 (1996), 423–429.
