Effect of Polarization on the Activation Process of (La, Sr)MnO3 Electrodes of Solid Oxide Fuel Cells

Abstract

The effect of polarization on the electrode behavior and microstructure of freshly-prepared (La 0.8 Sr 0.2 ) 0.9 MnO 3 (LSM) electrodes was investigated. The electrode polarization (i.e., interface) resistance (Ra) decreased significantly with the cathodic polarization while in the case of the anodic polarization R E increased initially, followed by a gradual decrease, In addition, the polarization treatment has significant effect on the microstructure of the LSM electrode. The original and large agglomerates in freshly-prepared LSM electrodes were broken down into sphere-shaped grains when exposed to cathodic or anodic current passage of 200 mAcm -2 at 800°C in air for 3 hr. The grain growth of the LSM electrodes was inhibited under cathodic polarization as compared to that under open circuit. This explains the observed high stability of the LSM cathode under solid oxide fuel cell operation conditions. The cathodic or anodic polarization treatment also has significant effect on the morphology and topography of the LSM electrode/Y 2 O 3 -ZrO 2 (YSZ) electrolyte interface.