Comparative characterization of thermodynamic, electrical, and electrochemical properties of Sm0.5Sr0.5Co1−xNbxO3−δ (x = 0, 0.05, and 0.1) as cathode materials in intermediate temperature solid oxide fuel cells

Abstract

The perovskite oxides, such as (La,Sr)CoO3 and (Ba,Sr)CoO3, have received much attention in recent years as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). In this study, we have investigated the structural, electrical, electrochemical, and redox properties of Sm0.5Sr0.5Co1−xNbxO3−δ (SSCNbx) cathodes under conditions relevant to IT-SOFC operation. The SSCNbx (x = 0, 0.05, and 0.1) oxides show gradually decreasing electrical conductivity with increasing Nb doping at the same temperature. The maximum power density of SSCNbx (x = 0.05, 0.1) is lower than that of SSC; however, SSCNbx (x = 0.1) is more stable than SSC considering the thermodynamic behaviour, as determined through redox isotherms. These results suggest that an Nb doped SSC perovskite is suitable, considering its high power density and reasonable redox stability, as an IT-SOFC cathode material.