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

The performance of La 0.8 Sr 0.2 Ga 0.83 Mg 0.17 O 2.815 (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 LaNiO 3 . The interlayer Sm‐CeO 2 was selected and sandwiched between the electrolyte and anode. Comparison of Sm‐CeO 2 /Sm‐CeO 2 + Ni and Sm‐CeO 2 + Ni as anodes showed that Sm‐CeO 2 /Sm‐CeO 2 + Ni gave an exchange current density 4 times higher than that of Sm‐CeO 2 + 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 La 0.6 Sr 0.4 CoO 3‐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/cm 2 to 550 mW/cm 2 at 800°C. The excellent cell performance showed that an LSGM‐based thick membrane SOFC operating at temperatures 600° < T op < 800°C is a realistic goal.