Investigation of Time Stability of Sr-Doped Lanthanum Vanadium Oxide Anode and Sr-Doped Lanthanum Cobalt Oxide Cathode Based on Samaria Doped Ceria Electrolyte Using Electrochemical and TOF-SIMS Methods

Abstract

The time stability of solid oxide fuel cell (SOFC) was tested using all ceramic La0.7Sr0.3VO3–δ-Ce0.85Sm0.15O2–δ (SDC) perovskite material as an alternative anode and La0.8Sr0.2CoO3−δ-SDC as a cathode. Both electrodes were prepared using infiltration method. The time stability measurements were carried out for 220 h under 0.6 V cell polarization in H2 fuel and at working temperatures of 600°C and 700°C. At both temperatures, the total polarization resistance, RP, increased in time and the maximal power density values decreased nearly 7% during testing. At the working temperature of 600°C the RP reached its constant value, 0.50 Ω cm2, during the first 12 h of polarization at 0.6 V. At 700°C noticeable increase in RP was seen within 100 h operation before the constant RP value, 0.50 Ω cm2, was established. The microstructure and composition of the single cells, including the mobility of Sr within the cell components, before and after time stability measurements, were analyzed using secondary ion mass spectrometry method. No degradation of cell components and Sr mobility was observed after the cell preparation process and only minor mobility of elements was seen after 24 h of operation at 600°C and 700°C. However, noticeable Sr, V, Co and La mobility was observed after 220 h operation at 600°C and 700°C.