Characterization of Ba-deficient PrBa1−xCo2O5+δ as cathode material for intermediate temperature solid oxide fuel cells

Abstract

A-site Ba-deficient PrBa1−xCo2O5+δ (PB1−xCO, x=0–0.08) oxides are synthesized and evaluated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) with respect to crystal structure, chemical stability, thermal expansion behavior, electrical conduction and electrochemical performance. PB1−xCO with Ba-deficiency x=0–0.08 has an orthorhombic structure, which shows lattice shrinkage with bigger x; higher Ba-deficiency x=0.1 causes formation of impurity phases. The PB1−xCO oxides are chemically stable with Gd0.1Ce0.9O1.95 (GDC) electrolyte at 1050°C in air. Thermal expansion coefficient of PB1−xCO decreases slightly with higher Ba-deficiency. Electrical conductivity of PB1−xCO exhibits an initial decrease with higher Ba deficiency to x=0.03 and then increases gradually to a maximum at x=0.08. Introduction of Ba deficiency greatly improves electrochemical performance of PB1−xCO, characterized by decreased area specific resistances (ASRs) with higher Ba deficiency. The ASR values as low as 0.115Ωcm2 and 0.093Ωcm2 have been obtained at 600°C in air for PB1−xCO with x=0.05 and 0.08 respectively. These results have demonstrated that the Ba-deficient PB1−xCO (x=0.03–0.08) oxides are promising cathode materials for IT-SOFCs.