SYNTHESIS OF SmBa_(0.5)Sr_(0.5)Co_2O_(5+δ) POWDER AND ITS APPLICATION AS COMPOSITE CATHODE FOR INTERMEDIATE TEMPERATURE SOLID OXIDE FUEL CELL

摘要

The layered samarium and strontium doped perovskite oxide SmBa_(0.5)Sr_(0.5)Co_2O_(5+δ) (SBSC) is synthesized by glycine nitrate combustion process. The crystallinity of SBSC powder with calcination temperatures shows that the perovskite phase is completely formed above 1000°C . SBSC powders mixed with Sm_(0.2)Ce_(0.8)O_(2-δ) (SDC) have been utilized as cathode materials to form a composite cathode which provides better compatibility with electrolyte and enhances the catalytic property for the cell. The single cell of yittria-stabilized zirconia (YSZ) based electrolyte with structure of NiO-YSZ | YSZ | SDC | SDC-SBSC, is operated from 700 to 800°C with H_2 as a fuel and ambient air as oxidant. The maximum power densities are 603, 449 and 321 mW cm~(-2) at 800, 750 and 700°C , respectively. According to the electrochemical impedance spectroscopy, the charge-transfer resistances of the electrodes are 0.10, 0.14, and 0.27 Ω cm~2, and the non-charge-transfer resistances are 0.87, 0.97, and 1.09 Ω cm~2 at 800, 750, and 700°C , respectively. The experimental results indicate that SBSC is a promising cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC).