Enhancement of electrochemical performance and thermal compatibility of GdBaCo2/3Fe2/3Cu2/3O5+δ cathode on Ce1.9Gd0.1O1.95 electrolyte for IT-SOFCs

Transition-metal doped double-perovskite structure oxides GdBaCo2/3Fe2/3Ni2/3O5+δ (FN-GBCO), GdBaCo2/3Fe2/3Cu2/3O5+δ (FC-GBCO), GdBaCoCuO5+δ (C-GBCO) and pristine GdBaCo2O5+δ (GBCO) were synthesized via a citrate combustion method. The thermal-expansion coefficient (TEC) and electrochemical performance of the oxides were investigated as potential cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The TEC exhibited by the FC-GBCO cathode up to 900 °C is 14.6 × 10−6 °C−1, which is lower than the value of GBCO (19.9 × 10−6 °C−1). Area specific resistances (ASR) of 0.165 Ω cm2 at 700 °C and 0.048 Ω cm2 at 750 °C were achieved for the FC-GBCO cathode on a Ce0.9Gd0.1O1.95 (CGO) electrolyte. An electrolyte supported (300 μm thick) single-cell configuration of FC-GBCO/CGO/Ni-CGO attained a maximum power density of 435 mW cm−2 at 700 °C. The unique composition of GBCO co-doped with Fe and Cu ions in the Co sites exhibited reduced TEC and enhancement of electrochemical performance and good chemical compatibility with CGO, and this composition is proving to be a potential cathode for IT-SOFCs.