Improved electrochemical performance and thermal compatibility of Fe- and Cu-doped SmBaCo2O5+δ–Ce0.9Gd0.1O1.95 composite cathode for intermediate-temperature solid oxide fuel cells

Abstract Fe- and Cu-doped SmBaCo 2 O 5+ δ (FC-SBCO)–Ce 0.9 Gd 0.1 O 1.95 (CGO) composites with various CGO contents (0–40 wt.%) are investigated as new cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) based on a Ce 0.9 Gd 0.1 O 1.95 electrolyte. The effect of CGO incorporation on the thermal expansion coefficient (TEC), electrochemical properties and thermal stability of the FC-SBCO-CGO composites is investigated. A composite cathode of 30 wt.% CGO–70 wt.% FC-SBCO (CS30-70) coated on a Ce 0.9 Gd 0.1 O 1.95 electrolyte shows the lowest area specific resistance (ASR), i.e., 0.049 Ω cm 2 at 700 °C. The TEC of the CS30-70 cathode is 14.1 × 10 −6  °C −1 up to 900 °C, which is a lower value than that of the FC-SBCO (16.6 × 10 −6  °C −1 ) counterpart. Long-term thermal stability and thermal cycle tests of the CS30-70 cathode are performed. Stable ARS values are observed during both type of test. An electrolyte-supported (300-μm thick) single-cell configuration of CS30-70/CGO/Ni-CGO delivers a maximum power density of 535 mW cm −2 at 700 °C. The unique composite composition of CS30-70 demonstrates improved electrochemical performance and good thermal stability for IT-SOFCs.