CLASSIFICATION CRITERIA FOR SOLID OXIDE FUEL-CELL ELECTRODE MATERIALS

In an attempt to establish comparison criteria for the electrocatalyti cal properties of electrode materials, systematic measurements were ca rried out on microelectrodes of simple shapes. The overpotential resis tances were normalized with respect to the electrode triple-phase boun dary length and the electrode capacitances to the electrode interface area. Results obtained on metals such as Ag, Pt, Au, and Ni, and on so me oxides, under either cathodic or anodic atmospheres, show marked di fferences which allow us to classify them. The positions of several ma terials in the cathode and anode material lists can be significantly d ifferent, indicating different electrocatalytical requirements under s olid oxide fuel cell cathode and anode atmospheres. The dearest exampl e is silver, which exhibits excellent electrocatalytical properties fo r the oxygen electrode reaction and very poor properties for hydrogen oxidation.