Microstructure and cathodic performance of La0.9Sr0.1MnO3 electrodes according to particle size of starting powder

Three La0.9Sr0.1MnO3 (LSM)/YSZ (yttria-stabilized zirconia) electrodes are prepared from LSM powders of different particle size via the silk-printing technique. The mean particle size of the three LSM powders is 1.54, 5.98 and 11.31 μm, respectively. The microstructural changes evolved during the course of electrode adhesion and half-cell operation are traced by taking scanning electron micrographs, and the cathodic activity is measured at 900°C in air using AC impedance spectroscopy. The LSM1 electrode prepared from the smallest powder shows good initial activity, but a rapid decrease in activity along with notable particle growth is observed within a short period of time. By contrast, the LSM3 electrode fabricated with the largest powder has a poor initial activity but the loss in activity is not appreciable as particle growth is insignificant. The LSM2 electrode that is prepared from medium-sized powder gives the best performances in terms of initial activity and long-term stability. It is likely that the LSM2 electrode has a larger number of active sites for the oxygen reduction reaction than LSM3 and the loss of active sites due to particle growth is less severe than with the LSM1 electrode.