Effect of Ionic Conductivity of Zirconia Electrolytes on the Polarization Behavior of Ceria‐Based Anodes in Solid Oxide Fuel Cells

The polarization behaviors of porous samaria‐doped ceria anodes coupled with zirconia electrolytes with various ionic conductivities (σ ion ) were investigated. The exchange current density, j 0 , on such mixed‐conducting SDC anodes was not influenced by the σ ion at 900 and 1000°C, whereas j 0 increased proportionally to σ ion at a lower temperature of 800°C. However, the dispersion of nanometer‐sized ruthenium catalysts on SDC particles resulted in an increase of j 0 with increase in σ ion in the entire temperature range between 800 and 1000°C. The observations are well explained kinetically i.e. , the anode performance is controlled by the rate of O 2 − supply to the anode layer via the electrolyte, as the anodic reaction rate becomes sufficiently high due to highly dispersed Ru electrocatalysts. Consequently, it is clear that the use of high‐performance electrodes in combination with the solid electrolyte having high σ ion is a prerequisite to achieving high performance of solid oxide fuel cells.