Electrochemical Properties of Composite (Sm0.5Sr0.5)(Co0.8M0.2)O3−δ (M=Cu, Mn) Cathodes for Intermediate Temperature Solid Oxide Fuel Cells

Abstract

This study investigates the electrochemical properties of (Sm0.5Sr0.5)(Co0.8M0.2)O3−δ (M=Cu, Mn) cathodes and evaluates them for solid oxide fuel cells (SOFCs). According to the relationship between interfacial polarization resistance at high frequency (R2) and oxygen partial pressure (Po2) at different temperatures, it indicates that oxygen reduction reactions are almost entirely dominated by the electron-transfer process for (Sm0.5Sr0.5)CoO3−δ-based cathodes with increasing the temperature. The result of the interfacial polarization resistance at high frequency (R3) as a function of oxygen partial pressure revealed that oxygen reduction reactions are nearly dominated by oxygen adsorption/desorption processes for (Sm0.5Sr0.5)CoO3−δ-based cathodes with increasing the temperature. The exchange current density (i0), is an important parameter for evaluating the electrocatalytic activity of cathode. The SSC-Cu revealed the largest i0 value among SSC-based cathodes at the temperature range of 600–800°C. Based on experimental results, the SSC-Cu showed the better performance in terms of electrochemical properties than those in the SSC cathode. Therefore, SSC-Cu may potentially be applied in intermediate temperature solid oxide fuel cell (IT-SOFC).