Electrochemical performance of highly active ceramic symmetrical electrode La0.3Sr0.7Ti0.3Fe0.7O3-δ-CeO2 for reversible solid oxide cells

Abstract

The electrolyte supported cells with the La0.3Sr0.7Ti0.3Fe0.7O3-δ (LSTF0.7)-CeO2|ScSZ (scandia-stabilized zirconia)|La0.3Sr0.7Ti0.3Fe0.7O3-δ-CeO2 symmetrical configuration are fabricated by infiltration method and investigated as reversible solid oxide cells (RSOCs) at different CO/CO2 ratios. A well-deposited microstructure is observed in the infiltrated electrode. From the I–V curves, the maximum current density of 1.90Acm−2 at 2.0V is obtained for CO: CO2 ratio of 1: 1 for CO2 electrolysis at 850°C, while the corresponding power density under the same conditions is 357mWcm−2 in fuel cell mode. Electrochemical impedance spectroscopy (EIS) is conducted for better understanding the electrode catalytic mechanism. The whole symmetrical cell achieves the polarization resistance (Rp) values of 0.284 and 0.203Ωcm2 at 850°C under open circuit and at 1.4V, respectively. Under reversible operation (cyclic voltammetry) at 800°C, no distinct degradation is found in the cell with the infiltrated LSTF0.7 symmetrical electrodes. The long-term stability at 1.2–2.0V characterized by potentiostatic measurement indicates that the prepared LSTF0.7-CeO2 composite electrode is comparatively stable at low voltages while a degradation behavior is observed at high voltages. These results illustrate that the LSFT0.7-CeO2 composite is a promising active ceramic electrode for symmetrical RSOCs.