Measurement of Polarization Resistances of LSCF/YSZ/LSCF Symmetrical Cell Using Alternating Current (AC) and Direct Current (DC) Techniques

Abstract

Lanthanum strontium cobalt iron oxide (LSCF) is a promising mixed ionic-electronic conductor (MIEC) used in solid oxide fuel cells (SOFCs) as electrodes. Symmetrical cells are usually used for study the electrode kinetics in the SOFCs. However, the polarization resistance and the electrode performance on the typical LSCF/YSZ/LSCF disk-shaped cell cannot be studied separately by using the typical two-electrode electrochemical impedance spectroscopy (EIS). Thus, two-electrode EIS with one pseudo-reference electrode needs to be used to study the two electrodes separately. Also, LSCF/YSZ/LSCF bar-shaped sample needs to be made so that platinum strip electrodes can be applied along the length of the YSZ bar for EIS testing. Since SOFCs are usually operated in DC mode, DC measurements also need to be performed to study the electrode polarization resistance and electrode performance. In this study, an LSCF/YSZ/LSCF bar-shaped symmetrical sample was made to measure the electrode polarization resistances of the two electrodes separately using both EIS and DC techniques. Results show that the two electrodes need not be identical. EIS and DC results are in good agreement with each other.