Effect of Ionic Conductivity of Zirconia Electrolytes on the Polarization Behavior of Various Cathodes in Solid Fuel Cells

The polarization behaviors of porous platinum and , (LSM) cathodes with zirconia electrolytes with various ionic conductivities were investigated. The exchange current density, , on Pt cathode was not infuenced by the at 900 and 1000°C, whereas increased proportionally to at a lower temperature of 800°C. However, the on LSM cathodes increaesd in proportion to the in the temperature region between 800 and 1000°C. The dispersion of nanometer‐sized Pt catalysts on LSM particles greatly enhanced the performance, the magnitude of which depended on the temperature, the , and the microstructure of LSM. The observations are well explained kinetically, i.e., the cathode performance is controlled by the transport rate of at the interface when the surface reaction rate is sufficiently high. Consequently, the use of high‐performance electrodes in combination with the solid electrolyte having high is very important for achieving the high performance of solid oxide fuel cells. © 1999 The Electrochemical Society. All rights reserved.