Electrochemical properties of porous Sr0.86Ti0.65Fe0.35O3 oxygen electrodes in solid oxide cells: Impedance study of symmetrical electrodes

• Published in: International journal of hydrogen energy Vol. 44; no. 3; pp. 1827 - 1838
• Main Authors: Mroziński, A., Molin, S., Karczewski, J., Miruszewski, T., Jasiński, P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.01.2019
• Subjects: Electrical conductivity; Oxygen electrode; Perovskite; Solid oxide cell; Perovskite; Oxygen electrode; Electrical conductivity; Solid oxide cell
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2018.11.203

This work evaluates porous Sr0.86Ti0.65Fe0.35O3 (STF35) as a possible oxygen electrode material for Solid Oxide Cells. The powder synthesis was performed by solid state method. Characterization included DC electrical conductivity study of sintered bulk samples and impedance spectroscopy study of symmetrical electrodes deposited on gadolinium doped ceria substrates. Measurements were carried out in atmospheres with different pO2 levels: 0.1%–20% O2. Detailed equivalent circuit analysis was carried out in order to clarify the reaction pathway on porous electrode, which extends knowledge available for dense model electrodes. At 800 °C in 21% O2, the DC electrical conductivity of STF35 pellet was 0.6 S cm−1 and the polarization resistance of the electrode in the symmetrical cell was ∼100 mΩ cm2. Detailed impedance spectroscopy studies revealed that the largest contribution (∼80%) towards the polarization resistance is due to oxygen adsorption, which is limiting the oxygen reduction performance of the porous STF35 electrode. These results show the applicability of advanced impedance analysis methods (e.g. Distribution of Relaxation Times - DRT) for description of complex impedance electrode phenomena of porous electrodes. •Formation of a dense interface layer for sintering temperature >1000 °C.•Polarization resistance is independent of the calcination temperature.•Performance of the porous STF35 electrode is limited by oxygen adsorption.