The aim of this paper is to address three issues in solid oxide fuel cells (SOFC): (i) cross-validation of the polarization of a single cell measured using both dc and ac approaches, (ii) the precise determination of the total area specific resistance (ASR), and (iii) understanding cathode polarization with (La0.60 Sr0.40) (Co0.20 Fe0.80) O3 cathodes. The ASR of an SOFC is a dynamic property, meaning it changes with current density. The ASR measured using impedance spectroscopy (low frequency interception with the real Z′ -axis of the ac impedance spectrum) matches that measured from a dc current-voltage (i-E) sweep (the tangent of a dc i-E curve). Due to the dynamic nature of ASR, we found that an impedance spectrum measured under open-circuit voltage or on a half-cell may not represent the cathode performance under real operating conditions, particularly at a high current density. In this work, the electrode polarization was governed by the cathode activation polarization; the anode contribution was negligible.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry