Activation and Ripening of Impregnated Manganese Containing Perovskite SOFC Electrodes under Redox Cycling

The impregnation of electrode precursor solutions is a very powerful technique for creating novel electrode microstructures constrained within preformed scaffolds. Here we report on the microstructural evolution of Mn-containing perovskites impregnated into yttria stabilized zirconia scaffolds on heating and redox cycling. Good performances have previously been reported for SOFC anodes with similar structure, and our objective is to better understand the origins of this good performance. For La0.75Sr0.25Cr0.5Mn0.5O3−δ a remarkable thin coating with microfissures is formed on the scaffold after firing the electrode precursors at 1200 °C, and such behavior can be considered as wetting of one oxide by another. On further treating this microstructure at 800 °C in H2 the microstructure changes dramatically forming an interconnected array of ∼10 nm scale particles. This seems to offer a very attractive structure with extensive triple phase boundary regions where electrochemical reactions can occur. On reoxidati...