Extended reaction zone of La 0.6Sr 0.4Co 0.2Fe 0.8O 3 cathode for solid oxide fuel cell

• Published in: Journal of power sources Vol. 198; pp. 90 - 94
• Main Authors: Lu, Zigui, Hardy, John, Templeton, Jared, Stevenson, Jeffry
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2012
• Subjects: Cathode thickness; Electrochemical impedance spectroscopy; Extended reaction zone; Oxygen reduction reaction; Oxygen reduction reaction; Cathode thickness; Extended reaction zone; Electrochemical impedance spectroscopy
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2011.09.020

► Attempts to determine the active cathode reaction zone have been made for the first time. ► The performance of the LSCF cathode showed very different behaviors in flowing air and oxygen. ► The difference in the electrochemical behaviors of the LSCF cathode in flowing oxygen and air were explained. The oxygen reduction reaction can only proceed at locations where gas, electronic conductor, and an oxygen ion conductor meet. Although the extension of the reaction zone beyond the traditional so-called triple-phase-boundary (TPB) is widely accepted for a mixed ionically and electronically conductive cathode, work in this area has yet to reach a consensus on how far the reaction zone can be extended. In this study, anode-supported fuel cells with a variety of LSCF cathode thicknesses were fabricated and tested in two cathode environments, flowing oxygen and flowing air. In flowing oxygen, the cell performance increased with LSCF cathode thickness over the entire range investigated (from 5 to 33 μm) because of the increased number of reaction sites. In flowing air, the cell performance also increased with the LSCF cathode thickness from 5 to 13 μm, but then remained almost constant with further increase in cathode thickness due to depletion of oxygen beyond a certain thickness.