2005 Volume 73 Issue 1 Pages 20-30
The electrolytes currently investigated for high temperature solid oxide fuel cells are reviewed in their electrical and mass transfer properties. First, these features are summarized and compared for the yttria stabilized zirconia, doped ceria and LaGaO3-based oxide. It has been clarified that the high electron conductivity in doped ceria makes this material unfavorable as electrolyte, whereas the LaGaO3-based oxides hold as good electrolyte even at low temperatures. Detailed behavior in the electrical properties for the fluorite oxides are reviewed with an emphasis on the dopant dependence in rare earth doped systems and also on the host dependence in zirconia-ceria solid solutions. The following topics are discussed in details: (1) Correlation of water solubility with hole conductivity; (2) Roles of ceria as the oxide component in anode and as the interlayer between electrolyte and electrode; (3) For the LaGaO3-based oxides, the electrical properties in its relation to the Co doping; (4) Cation diffusivity in LSGM from different techniques are summarized. Finally, effects of nano-crystalline size are briefly discussed concerning their enhancement in electron conduction.
