Investigation of novel solid oxide fuel cell cathodes based on impregnation of SrTixFe1-xO3-δ into ceria-based backbones

Solid oxide fuel cell (SOFC) cathodes were prepared by impregnating the nitrates corresponding to SrTixFe1-xO3-δ (STF), x= 0; 0.1; 0.2; 0.3; 0.4 and 0.5, into a porous backbone of Ce 0.9Gd0.1O2-δ (CGO). STF was chosen as very high oxygen surface exchange rate, high ionic conductivity and electrochemical stability as a thin film electrode have been reported for these materials. XRD measurements showed a high degree of secondary phase formation in the infiltrate as well as reaction with the CGO backbone. Microstructural analysis showed that the STF infiltrate had formed a coating on the CGO backbone. All prepared electrodes were characterized as symmetric cells using impedance spectroscopy. Within the investigated series the infiltrate with x = 0.1 (STF10) showed the best performance with an area specific resistance (ASR) of ASR ≈ 6.4 Ω cm2 (STF10) at 600°C in air. The relatively poor performance is believed to originate from poor electronic conduction in the electrodes and possibly also reactions between Sr-containing compounds and CGO. To circumvent the low electronic conductivity, backbones of a composite cathode containing LaCo0.4Ni0.6O 3-δ (LCN60) and CGO were also tried infiltrated with STF. The ASR of the backbone was 8.7 Ω cm2 prior to infiltration and this decreased to 0.34 Ω cm2 after infiltration with STF10.