High-performance GdBaCo2O5+δ–Ce0.9Gd0.1O1.95 composite cathode for solid oxide fuel cells

GdBaCo2O5+δ (GBCO)–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 GBCO–CGO composite cathodes are investigated. The thermal expansion behavior shows that the TEC values of GBCO cathode decrease with CGO addition. The TEC of 30 wt.% CGO–70 wt.% GBCO (CG30) cathode shows 14.7 × 10−6 °C−1 up to 900 °C, which is lower value than pristine GBCO (20.0 × 10−6 °C−1). In addition, the addition of CGO to GBCO cathode improves remarkably the electrochemical performance. The composite cathode of 30 wt.% CGO–70 wt.% GBCO (CG30) coated on Ce0.9Gd0.1O1.95 electrolyte shows the lowest polarization resistance (0.029 Ω cm2 at 700 °C). An electrolyte-supported (300 μm thick) single-cell configuration of CG30/CGO/Ni-CGO attains a maximum power density of 340 and 525 mW cm−2 at 650 and 700 °C, respectively. The results indicate that 30 wt.% CGO–70 wt.% GBCO cathode is a promising cathode material for IT-SOFCs.