Sr-doped LaCrO3 anode for solid oxide fuel cells

• Published in: Journal of the Electrochemical Society 2001, Vol.148 (1), p.A74-A81
• Main Authors: PRIMDAHL, S, HANSEN, J. R, GRAHL-MADSEN, L, LARSEN, P. H
• Format: Article
• Language: English
• Subjects: Applied sciences; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.1344519

A number of doped lanthanum chromite perovskites are considered to be suitable as anode materials for solid oxide fuel cells with a YSZ electrolyte operating in hydrogen at 850 C. The polarisation resistance, as measured by impedance spectroscopy, was shown to depend significantly on the type and amount of doping. In particular, the composition La0.8Sr0.2Cr0.97V0.03O3 (LSCV) was examined in detail. Reactivity studies indicate the presence of secondary phases in LSCV. These phases are reactive towards YSZ, resulting in the formation of SrZrO3. The secondary phases may be readsorbed during prolonged calcination under reducing conditions. The polarisation resistance was shown to increase severely over a few days, and to be recoverable by temporary oxidation. The time constant of the degradation was shown not to match that of the changes in stoichiometry and conductivity during reduction of the perovskite. Two rate limiting processes are generally observed. The low frequency process is suggested to relate to adsorption of hydrogen on the LSCV surface or a chemical reaction step. The high frequency process is suggested to relate to the LSCV/YSZ contact interface. LSCV does not exhibit significant catalytic activity towards steam reforming of methane, and shows no sign of direct methane oxidation. 36 refs.