Performance analysis of cobalt-based cathode materials for solid oxide fuel cell

Abstract

The area specific resistance (ASR) characteristics of Ln 1 − x Sr x M ′ 1 − y M″ y O 3 – δ (Ln=Lanthanides, M′ and M″: transition metal such as Co and Fe), Sm 0.5Sr 1.5Co 1 − y Ni y O 4 – δ and Sm 0.5Sr 1.5Co 1 − y Fe y O 4 – δ oxides were investigated as cathode materials for intermediate temperature operating solid oxide fuel cell (IT-SOFC) application. As an effect of Sr substitution in A-site of perovskite, ASR of Nd 0.5Sr 0.5CoO 3 (NSC55) was 0.14 Ω cm 2 at 700 °C. Sm 0.5Sr 0.5CoO 3 – δ (SSC55) on Ce 0.9Gd 0.1O 2 – δ (CGO91) and Ce 0.8Sm 0.2O 2 – δ (CSO82) showed the lowest ASR as 0.10 Ω cm 2 and 0.085 Ω cm 2 at 700 °C among various perovskite compositions in this study. ASR of B-site substituted Pr 0.3Sr 0.7Co 0.3Fe 0.7O 3 – δ (PSCF3737) in the Pr 0.3Sr 0.7Co 1 − y Fe y O 3 – δ was about 0.13 Ω cm 2 at 700 °C. Comparing ASR of SSC55 as a perovskite structure with the value of Sm 0.5Sr 1.5Co 1 − y Fe y O 4 – δ ( y = 0, 0.3, 0.5 and 0.7) as a spinel structure, the ASR of SSC55 was 0.085 Ω cm 2. However, the value of Sm 0.5Sr 1.5Co 1 − y Fe y O 4 – δ ( y = 0, 0.3, 0.5 and 0.7) was much higher than SSC55 at 700 °C. In XPS analyses, the atomic percentage values of PSC55 and PSC37 were 83.5, and 83.1%. However, the value of SrCoO 3 – δ was 50.2%. The results claim that more oxygen sites including oxygen vacancies on the surface of PSC55 and PSC37 exist than that of SrCoO 3 – δ .