Ageing of anode-supported solid oxide fuel cell stacks including thermal cycling, and expansion behaviour of MgO–NiO anodes

• Published in: Journal of power sources Vol. 182; no. 2; pp. 389 - 399
• Main Authors: Van herle, J., Perednis, D., Nakamura, K., Diethelm, S., Zahid, M., Aslanides, A., Somekawa, T., Baba, Y., Horiuchi, K., Matsuzaki, Y., Yoshimoto, M., Bucheli, O.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 01.08.2008; Elsevier Sequoia
• Subjects: (Mg, Ni)O solid solution; Ageing; Anode-supported SOFC; Anodes; Applied sciences; Degradation; Electric potential; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; Fuels; Magnesium; Magnesium oxide; Nickel anode expansion; Stacks; Thermal cycling; Voltage; Anode-supported SOFC; (Mg, Ni)O solid solution; Nickel anode expansion; Thermal cycling; Ageing; Scanning electron microscopy; Anode; Magnesium oxide; Thermal behavior; Solid solution; Dispersive spectrometry; Solid oxide fuel cell; Ni)O solid solution; Discharge charge cycle; Open circuit voltage; Anode-supported SOFC; Ageing; Thermal cycling; Nickel anode expansion; (Mg; X ray diffractometry; Nickel oxide
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2008.03.006

This paper reports on medium term tests of anode-supported five-cell short stacks, as well as on some separate anode development. Two stacks were operated under steady-state conditions: one with unprotected metal interconnects, H 2 fuel and 0.35 A cm −2 (40% fuel utilisation) polarisation current showed an average cell voltage degradation of 56 mV per 1000 h for 2750 h; one with coated metal interconnects, synthetic reformate fuel and 0.5 A cm −2 (60% fuel utilisation) polarisation current showed an averaged cell voltage degradation slope of 6.6 mV per 1000 h for 800 h before a power cut prematurely interrupted the test. A third stack was subjected to 13 complete thermal cycles over 1000 h, average cell voltage degradation was evaluated to −2 mV per cycle for operation at 0.3 A cm −2, open circuit voltage (OCV) remained stable, whereas area specific resistance (ASR) increase amounted on average to 0.008 Ω cm 2 per cycle. To improve anode reoxidation tolerance, MgO addition was considered. (Mg, Ni)O solid solutions were synthesized from MgO and NiO powders at 1500 °C for 2 h in air. Samples were reduced at 1000 °C in 4 vol% H 2 in N 2, and their expansion behaviour was observed. XRD and SEM/EDX analysis suggested that the expansion was caused by the segregation of Ni particles between (Mg, Ni)O grains.