| Summary: | 碩士 === 國立中山大學 === 材料科學研究所 === 96 === For the last two decades, solid oxide fuel cells (SOFCs) have been operated in high temperatures > 1000°C. Recently, more efforts have been concentrated on the intermediate temperature SOFCs in which Ba0.5Sr0.5Ce0.8Fe0.2O3-δ (BSCF) is a very promising cathode material capable of working in this intermediate temperature range of 500~700°C.
In this work, both glycine and citric acid methods were employed to prepare BSCF powders. Preparation parameters such as concentration of organic components and calcination temperature were varied to obtain powders of different morphologies and particle sizes. Slurries containing the prepared powders were then used to print BSCF cathode films on electrolyte disks. The impedances of the resultant cathodes were measured and analyzed to evaluate the effects of powder preparation parameters and film microstructures.
The results show that the BSCF cathode derived from the powder prepared by the modified citric acid method and then sintered at 900°C has the best electrochemical performance. With high porosity and well dispersed pores, this cathode has interfacial area specific resistance (ASR) values as low as 0.78 Ωcm2 at 500°C, 0.10 Ωcm2 at 600°C and 0.018 Ωcm2 at 700°C, which are significantly lower than that obtained from the unmodified citric acid or glycine method.
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