LaCoO3 – δ as the Material of an Oxygen Electrode for a Molten Carbonate Fuel Cell: II. Catalytic Activity of LaCoO3 – δ for the Electroreduction of Oxygen in Molten (Li0.62K0.38)2CO3

Resumo

The kinetics of the electroreduction of O₂ in the (Li_0.62K_0.38)₂CO₃ eutectic melt on the oxide electrode prepared of in situ lithiated LaCoO_{3 – δ} is studied. Superoxide ions and molecular oxygen are shown to be the major electroactive particles under the studied conditions, which correlates with the investigations on a gold electrode. The reaction mechanism on the oxide electrode differs from the mechanisms proposed for the gold electrode. Several mechanisms are proposed to take into account the specificity of the oxide electrode. The exchange current densities are found to be independent of the partial oxygen pressure and to vary in a range of 220–290 mA/cm² depending on the experimental conditions and the operating mechanism.