The comparative effects of cobalt and/or iron ions as dopants into Ba(Zr, Y)O3-δ-based perovskite cathodes for intermediate-temperature SOFCs.

The development of highly active cathode is crucial to promote the electrochemical performance of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Here, it is reported the cobalt and/or iron ions as dopants into Ba(Zr, Y)O 3-δ with the nominal chemical formulae of BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ (BCFZY), BaCo 0.8 Zr 0.1 Y 0.1 O 3-δ (BCZY), and BaFe 0.8 Zr 0.1 Y 0.1 O 3-δ (BFZY), which all form the main cubic perovskites in addition to a small amount of co-assembled hexagonal D-Ba(Co, Fe)O 3-δ , D-BaCoO 3-δ , and D-BaFeO 3-δ under the same preparing condition. Among three samples, BCZY composite shows the highest capacity of O 2 adsorption, lower thermal expansion coefficient (19.1 × 10−6 K−1), and highest electrical conductivity of 2.73 S cm−1 (750 °C). The symmetric cell with BCZY composite cathode exhibits excellent ORR activity with the lowest area specific resistance of 0.10 Ω cm2 at 700 °C, which is 0.71 and 0.67 times those of BCFZY composite and BFZY composite cathodes. Accordingly, the single cell with BCZY composite cathode shows the lowest R P of 0.16 Ω cm2 and the highest peak power density of 2.24 W cm2 at 700 °C. The distribution of relaxation times (DRT) analysis reveals that BCZY composite cathode shows the superior surficial oxygen exchange and charge transfer activity. [ABSTRACT FROM AUTHOR]