Influence of the oxygen electrode and inter-diffusion barrier on the degradation of solid oxide electrolysis cells

• Published in: Journal of power sources Vol. 223; pp. 349 - 357
• Main Authors: Hjalmarsson, Per, Sun, Xiufu, Liu, Yi-Lin, Chen, Ming
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2013; Elsevier
• Subjects: Applied sciences; Co-electrolysis; Degradation; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrolysis; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; MIEC; SOEC; Solid oxide electrolysis cell; Solid oxide electrolysis cell; Degradation; Co-electrolysis; Electrolysis; SOEC; MIEC; Iron oxide; Carbon dioxide; Diffusion layer; Solid oxide fuel cell; Lanthanum oxide; Crack propagation; Ferrites; Strontium Manganites; Electrolysis cell; Damaging; Electrical impedance; Lanthanum Manganites; Cobalt oxide; Oxygen electrode; Sandwich structure; Stabilized zirconia; Electrical measurement; Electrolyte; Cermet; Diffusion barrier; Nickel; Strontium oxide; Electrochemical impedance spectroscopy
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2012.08.063

Two Solid Oxide Electrolysis Cells (SOECs) with different oxygen electrodes have been tested in galvanostatic tests carried out at −1.5 Acm−2 and 800 °C converting 60% of a 50:50% mixture of H2O and CO2 (co-electrolysis). One of the cells had an LSM:YSZ oxygen electrode. The other had an CGO inter-diffusion barrier sandwiched between the YSZ electrolyte and an LSCF:CGO oxygen electrode. Impedance Spectroscopy was used during the tests to diagnose the change in electrochemical response of the different components of the SOECs. The results showed a significantly lower degradation rate for the cell with an LSCF:CGO oxygen electrode. This was attributed to three different effects: (1) The LSCF electrode was found to be more stable than its LSM:YSZ based counterpart. (2) The crack propagation in the YSZ electrolyte was less severe in the cell with an LSCF electrode. (3) The Ni:YSZ degradation was less severe in the cell with an LSCF electrode. We hypothesize further that (2) is an effect of the CGO inter-diffusion layer and that (3) is an indirect effect of (2). ► Two SOECs with LSCF:CGO and LSM:YSZ oxygen electrodes were tested. ► The tests were carried out at −1.5 Acm−2 and co-electrolysis conditions. ► The LSCF electrode was electrochemically more stable than its LSM counterpart. ► The electrolyte of the LSCF cell was more stable than that of the LSM:YSZ cell. ► The Ni:YSZ electrode was more stable in the cell with an LSCF:CGO electrode.