LA0.6CA0.4COO3 - A STABLE AND POWERFUL CATALYST FOR BIFUNCTIONAL AIR ELECTRODES

High-surface-area La0.6Ca0.4CoO3 perovskite-type oxides were prepared by the citric and malic acid precursor method. The oxide catalyst was homogeneously dispersed on corrosion-resistant graphitized Vulcan XC 72 carbon powder. A manufacturing process for preparing two-layer Teflon(R)-bonded bifunctional O-2 diffusion electrodes in practical sizes for battery applications was developed. The microstructure and the performance of the electrodes were studied experimentally using electrochemical, physical (mercury porosimetry, BET analyses) and imaging (SEM and EDX) techniques. A cycle life of about 1400h of alternating operation as cathodes and anodes was determined for the bifunctional electrodes. Catalyst dissolution due to erosion of the active surface by-oxygen evolution and partial destruction of the perovskite catalyst appear to be the dominant life-limiting processes.