Superior Perovskite Oxide‐Ion Conductor; Strontium‐ and Magnesium‐Doped LaGaO3: III, Performance Tests of Single Ceramic Fuel Cells

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Abstract
The performance of La0.8Sr0.2Ga0.83Mg0.17O2.815 (LSGM) as an optimized electrolyte of a solid oxide fuel cell was tested on single cells having a 500‐µm‐thick electrolyte membrane. The reactivity of NiO and LSGM suggested use of an interlayer to prevent formation of LaNiO3. The interlayer Sm‐CeO2 was selected and sandwiched between the electrolyte and anode. Comparison of Sm‐CeO2/Sm‐CeO2+ Ni and Sm‐CeO2+ Ni as anodes showed that Sm‐CeO2/Sm‐CeO2+ Ni gave an exchange current density 4 times higher than that of Sm‐CeO2+ Ni. The peak power density of the interlayered cell is 100 mW higher than that of the standard cell without the interlayer. This improvement is due to a significant reduction of the anode overpotential; the overpotential of the cathode La0.6Sr0.4CoO3‐delta (LSCo) remained unchanged. Comparison of the peak power density in this study and with that of a previous study, also with a 500‐µm‐thick electrolyte, indicates a factor of 2 improvement, i.e., from 270 mW/cm2 to 550 mW/cm2 at 800°C. The excellent cell performance showed that an LSGM‐based thick membrane SOFC operating at temperatures 600° < Top < 800°C is a realistic goal.