Thermal and Electrical Stability of Sr_0.9Y_0.1CoO_2.5+δas a Promising Cathode for Intermediate-Temperature Solid Oxide Fuel Cells

Abstract

Here, the present study reports thermal and electrical properties of Sr<sub>1-x</sub>YxCoO<sub>2.5+δ</sub> (x = 0–0.40) as a promising cathode for intermediatetemperature solid oxide fuel cells. The results show that x = 0.10 is the best composition possessing a single primitive cubic perovskite structure, stable conductivity and the lowest polarization resistance. Thermogravimetric analysis indicates an oxygen intake from RT to ~375°C, above which oxygen loss occurs. The oxygen gain-loss behavior corresponds well with the conductivity increase-decrease trending, reflecting that oxygen-nonstoichiometry controls the hole-concentration (or oxidation-state of Co-ions). Electrochemical impedance spectroscopy analysis further reveals that the overall ORR polarization consists of a faster charge-transfer and a slower surface oxygen exchange.