Cobalt-free perovskite cathode BaFe0.9Nb0.1O3-δ for intermediate-temperature solid oxide fuel cell

Cobalt-free BaFe0.9Nb0.1O3-delta (BFNb) was investigated as a cathode material for intermediate-temperature solid oxide fuel cell (IT-SOFC). XRD refinements favour the co-existence of at least cubic and tetragonal phases in the BFNb sintered at 1000 or 1100 degrees C, in which the content of the cubic phase decreased with increasing sintering temperature. Because of the presence of BaFe2O4 impurity in the 1100 degrees C prepared sample, the temperature of 1000 degrees C was preferred for the final sample preparation. At IT region (600-800 degrees C), the electrical conductivity of the BFNb sample was 2.5-1.8 S cm(-1), and the average thermal expansion coefficient (TEC) was 18.3 x 10(-6) K-1. The polarization resistance of the BFNb cathode on Gd0.1Ce0.9O1.95 (GDC) electrolyte achieved 0.102 Omega cm(2) at 700 degrees C. For a single cell with BFNb cathode and 300-mu m-thick GDC electrolyte, a peak power density of 397 mW cm(-2) was attained at 700 degrees C, and a 30 h long-term testing demonstrates the good stability of the BFNb cathode under a real SOFC operating condition. (C) 2021 Elsevier B.V. All rights reserved.