Assessment of electrochemical performance and thermal compatibility of Fe and Cu doped SmBaCo2O5+ - CGO composite cathode for IT-SOFCs

Abstract

Fe and Cu doped SmBaCo2O5+ (FC-SBCO) - Ce0.9Gd0.1O1.95 (CGO) composites with various CGO contents (0-40 wt.%) have been investigated for potential cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). The effect of CGO incorporation on the thermal expansion coefficient (TEC), electrochemical performance and microstructure of the FC-SBCO - CGO composite cathodes are investigated. The thermal expansion behavior shows that the TEC values of FC-GBCO cathode decreases with CGO addition. The TEC of 30 wt.% CGO - 70 wt.% FC-SBCO (CS30) cathode shows 14.1 × 10-6 ºC-1 up to 900 ºC, which is lower value than pristine FC-SBCO (16.6 × 10-6 ºC-1). In addition, the addition of CGO to FC-SBCO cathode improves remarkably the electrochemical performance. The composite cathode of 30 wt.% CGO - 70 wt.% FC-SBCO (CS30) coated on Ce0.9Gd0.1O1.95 electrolyte shows the lowest polarization resistance (0.024 Ωcm2 at 750 ºC). An electrolyte-supported (300 μm thick) single-cell configuration of CG30/CGO/Ni-CGO attains a maximum power density of 783 mWcm-2 at 800 oC, respectively. The results indicate that 30 wt.% CGO - 70 wt.% FC-SBCO cathode is promising cathode material for IT-SOFCs.