Long-Term Chemical Stability of LaNi ( Fe ) O3 as a Cathode Material in Solid Oxide Fuel Cells

Chemical reactivity of LaNi 0.6 Fe 0.4 O 3 (LNF) with Cr 2 O 3 has been investigated in order to examine the long-term stability of the LNF phase at 1073 K, which shows a high performance as the cathode of intermediate-temperature solid oxide fuel cells (IT-SOFCs). The chemical stability of LNF was compared with that of La 0.8 Sr 0.2 MnO 3 (LSM) under the existence of Cr 2 O 3 . The LNF powder, a powder mixture of LNF and Cr 2 O 3 , and a powder mixture of LSM and Cr 2 O 3 were, respectively, heated at 1073 K, and they are analyzed by X-ray powder diffraction with the Rietveld refinement. We found that the LNF phase maintains the hexagonal crystal system heated in air up to 1000 h. In the LNF-Cr 2 O 3 mixture, the LNF phase kept its pristine crystal structure while a new phase, NiCr 2 O 4 , was detected, which was produced by the reaction between Cr 2 O 3 and the residual NiO contained in the starting LNF powder. In the LSM-Cr 2 O 3 mixture, LSM reacted with Cr 2 O 3 and produced a significant amount of MnCr 2 O 4 . LNF showed a much better chemical stability against Cr 2 O 3 than LSM. LNF can serve as a long-life cathode in the IT-SOFC system.