Development of a Low Temperature Operation Solid Oxide Fuel Cell

Lowering operation temperature of the solid oxide fuel cell (SOFC) would promote the commercialization of a power-generation module in terms of the manufacturing cost, lifetime, reliability, etc. Mitsubishi Materials Corporation and Oita University have been jointly developing a planar-type SOFC which could operate at a temperature of about 700°C. As an electrolyte, lanthanum gallate (LaGaO₃) with substitution of Sr for the La site and Mg and Co for the Ga site was used at this temperature. So far we have established a technique for large-scale cell production, and currently we are examining the performance of a commercial-size cell as large as 154 mm in diam. The obtained cell attained an output power of 31 W with an effective electrode area of 177 cm² at 650°C. Furthermore, a stuck of two cells has been tested and the use of stainless steel for the separator was found to be possible during the examined time period at this temperature. The internal CH₄ reforming on the cell has been examined, and the cell output performance using methane [steam/carbon ratio (S/C) = 2 ] was about 93% of the power density of the cell using hydrogen.