An all-in-one flourite-based symmetrical solid oxide fuel cell

A novel concept of solid oxide fuel cell (SOFC), the symmetrical SOFC, that uses simultaneously the same material as both anode and cathode has been investigated. Common materials typically used as anode components such as a combination of YSZ and CeO2 plus a noble metal may be considered good candidates for such a configuration at relatively high temperatures (i.e. above 900 °C). These symmetrical electrodes exhibit enhanced electrochemical properties under both reducing and oxidising conditions, in part due to the catalytic properties of the noble metal used. In air the polarisation values are improved by a factor of four compared to electrodes without CeO2, whereas under reducing conditions an improvement of two–three orders of magnitude has been observed. The best results correspond to cermets containing 50–60% of CeO2. This simple combination allows the assembly of all-in-one fluorite-based symmetrical fuel cells (SFCs): YSZ–CeO2/YSZ/YSZ–CeO2 plus a noble metal with good catalytic behaviour. Performances of 140 mW cm−2 at 950 °C were obtained when using H2 as fuel and thick YSZ electrolytes. Interesting performances of 500 mW cm−2 are expected for thin YSZ electrolyte layer under identical experimental conditions.