Ca and Fe co-doped SmBaCo2O5 + δ layered perovskite as an efficient cathode for intermediate-temperature solid oxide fuel cells

Abstract A-site Ca and B-site Fe co-doped SmBa 1 −  x Ca x Co 2 −  y Fe y O 5 +  δ ( x  = 0, y  = 0; x  = 0.25, y  = 0; x  = 0.25, y  = 1.0) layered perovskites are prepared and evaluated as the cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The synergistic effects of co-doping on the crystal structure, chemical compatibility with the electrolyte, thermal expansion behavior, electrical conductivity, and electrochemical performance are investigated. Ca and Fe co-doping lowers the thermal expansion coefficient of SmBaCo 2 O 5 +  δ . The area specific resistance of the Ca and Fe co-doped sample (SmBa 0.75 Ca 0.25 CoFeO 5 +  δ -GDC) is decreased by 49.3%, compared with that of the undoped sample at 800 °C, based on a GDC electrolyte. Furthermore, the maximum power density of a GDC electrolyte-supported single cell with a SmBa 0.75 Ca 0.25 CoFeO 5 +  δ -GDC cathode is increased by 50.7% at 800 °C. The results indicate that the Ca and Fe co-doping layered perovskite SmBa 0.75 Ca 0.25 CoFeO 5 +  δ is an excellent cathode material for IT-SOFC applications.