Ln1−xSrxCoO3 (Ln=Gd, Pr) as a cathode for intermediate-temperature solid oxide fuel cells

Researchers at Argonne National Laboratory have tested several cathodes on yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (CGO) electrolytes for use in solid oxide fuel cells (SOFCs). The Pr0.5Sr0.5CoO3 (PSC) and Gd0.5Sr0.5CoO3 (GSC) cathodes show the best performance on CGO, achieving an area-specific resistance (ASR) between 0.1 and 0.2 Ω·cm2 at 650 °C. However, the desirable operating temperature for CGO is between 500 and 600 °C, where the ASRs remain very high. The cobalt-based materials in contact with the YSZ electrolyte exhibit severe reactions. To prevent these reactions, a dense interlayer of CGO has been added between the YSZ and the cobalt-based cathodes. The results for the PSC and GSC cathodes on the YSZ electrolyte protected by a CGO layer reveal ASR values between 0.1 and 0.2 Ω·cm2 at 750 °C and 0.3 Ω·cm2 at 700 °C. Long-term testing of both PSC and GSC cathodes on YSZ electrolytes with CGO interlayers showed stable ASR values for 500 h at 800 °C. Thermal cycling between room temperature and 800 °C after long-term testing showed minimal degradation.