Chemical compatibility and electrochemical property of intermediate-temperature SOFC cathodes under Cr poisoning condition

We have investigated the relationship between the chemical compatibility and electrochemical properties of La0.6Sr0.4Fe0.8Co0.2O3 (LSCF), LaNi0.6Fe0.4O3 (LNF), and La0.8Sr0.2MnO3 (LSM) as a cathode against the Cr poisoning condition. Powder mixtures of LSCF–Cr2O3, LSM–Cr2O3, and LNF–Cr2O3 were heated at 1073 K and analyzed by X-ray powder diffraction with the Rietveld refinement. It was found that LNF powder was less reactive with Cr2O3 than LSCF and LSM powder from the viewpoint of the consumption of Cr2O3 in the mixtures. From electrochemical measurement, it was found that the cathodic overvoltage was almost unchanged for cells with LNF cathode, either in the presence or absence of a Cr-containing alloy. On the other hand, the cells with LSCF and LSM cathode in the presence of the alloy exhibited a steep increase in the overvoltage curve. These results show that LNF cathode is more stable against Cr poisoning than the other two cathodes. Therefore, we expect LNF to be a long-life cathode with high stability against Cr poisoning in solid oxide fuel cell because of the low reactivity of LNF with Cr2O3.