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

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 0.115 Ω cm2 and 0.093 Ω cm2 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.

► The Ba-deficiency in PB1−xCO is limited up to x = 0.08. ► No reaction between PB1−xCO and GDC was found at 1050 °C in air. ► Introduction of Ba deficiency results in remarkably decreased ASRs for PB1−xCO. ► Ba-deficient PB1−xCO (x = 0.03–0.08) are promising cathode materials for IT-SOFCs.