Thermal expansion and electrochemical performance of La 0.7Sr 0.3CuO 3− δ–Sm 0.2Ce 0.8O 2− δ composite cathode for IT-SOFCs

Abstract

The thermal expansion, electrical conductivity and electrochemical properties of La 0.7Sr 0.3CuO 3− δ –Sm 0.2Ce 0.8O 2− δ (LSCu–SDC) composite cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs) were investigated. The addition of SDC to LSCu matrix materials significantly reduced the thermal expansion mismatch between them. SDC also suppressed the LSCu grain growth and increased the porosity of the composite cathode. The electrochemical performance of the interfaces between the porous LSCu–SDC composite cathode and dense SDC electrolyte was examined using AC impedance spectroscopy. The polarization resistance was significantly reduced from 0.62 Ω cm 2 for pure LSCu to 0.29 Ω cm 2 for LSCu–25 wt.% SDC under open circuit condition at 800 °C, showing that the La 0.7Sr 0.3CuO 3− δ –Sm 0.2Ce 0.8O 2− δ composite cathode is very promising to be used as a new cathode for IT-SOFCs.