Abstract: Sm0.5Sr0.5CoO3 (SSC) powders were prepared using solid-state reaction. The XRD pattern of SSC corresponded to a desired perovskite structure. SSC electrodes sintered at various temperatures (1173～1373 K) and SSC-La0.8Sr0.2Ga0.8Mg0.15Co0.05O3 (SSC-LSGMC5), SSC- La0.8Sr0.2Ga0.8Mg0.09Co0.11O3 (SSC-LSGMC11) composite cathodes sintered at 1173 K were studied using SEM ,impedance spectroscopy, and DC(direct current) polarization. The electrodes studied were prepared on La0.9Sr0.1Ga0.8Mg0.2O3 electrolytes using screen-printing. The particle size of SSC electrodes increased with sintering temperatures, and the porosity decreased accordingly. The addition of LSGMC5 and LSGMC11 into SSC had no obvious effect on the microstructure of SSC electrodes. The results of AC (alternative current) impedance spectroscopy and DC polarization showed that the activity of SSC electrodes increased with decreasing sintering temperature, and the optimum sintering temperature for SSC electrodes was about 1173 K. The addition of LSGMC5 or LSGMC11 into SSC improved both the activity and stability of SSC electrodes significantly.

Key words: Solid oxide fuel cell, Cathode, AC impedance, Sintering temperature,