Performance and reaction process of Ba1-xCo0.7Fe0.2Nb0.1O3-δ cathode for intermediate-temperature solid oxide fuel cell

Perovskite-type cathode Ba1-xCo0.7Fe0.2Nb0.1O3-delta (B1-xCFN, x = 0.0-0.15) are proposed for intermediate-temperature solid oxide fuel cell(IT-SOFC). The changes in crystal structure, thermal expansion and electrochemical reaction through XRD, SEM, ac impedance spectroscopy and single-cell test are studied. The results show that except for the B0.95CFN has a small amount of impurity, B1-xCFN oxides present cubic perovskite structure. The porosity decreases as A-site deficiency increases, B0.9CFN has a lowest porosity. The interfacial polarization resistance of B0.9CFN drops nearly 66.2% than BCFN at 800 degrees C. The process of generating lattice oxygen is the major rate-limiting step when oxygen partial pressure is higher than 0.01 atm. Ba deficiency mainly accelerates the ionization process of oxygen atoms in the cathode bulk. The performance of single-cell B0.9CFN/SDC/Ni0.9Cu0.1-SDC is higher than other cathodes in the operation temperature, which means B0.9CFN is a better cathode for IT-SOFC. (C) 2021 Elsevier B.V. All rights reserved.