Microstructural Control ofLSM/YSZComposite Cathode forLowerTemperature Operation ofSOFC

Lao.8Sro.2MnO3(LSM)/Y203 stabilized ZrO2(YSZ) composite powders weremechanically prepared. Bychanging the mechanical device orprocessing time, threecomposite powders withdifferent size distributions wereobtained. Thenthepoweders wereformedintocathodes ofsolid oxide fuel cells (SOFCs). The microstructures ofthecathodes werecarefully characterized by scanning electron microscope (SEM). Losses byinternal resistance (IR)andbypolarization between theelectrolyte andcathode were measured withthecurrent interruption technique. Thecathode fabricated byusing thepowderwiththenarrowest particle size distribution showedfinegrains, uniform porousstructure and goodcontact withtheelectrolyte layer, thereby resulting inlowIR andpolarization losses. Incontrast, thecathode fabricated from thepowderwiththebroadest particle size distribution contained a large massofcoarse particles andhadless uniform structure inthe grains andpores, thereby resulting inrelatively highIR and polarization losses.