Electrochemical performance of Pr1−xYxBaCo2O5+δ layered perovskites as cathode materials for intermediate-temperature solid oxide fuel cells

Abstract

Pr1−xYxBaCo2O5+δ (x = 0.3, 0.5 and 0.7) oxides were prepared and evaluated as cathode materials for intermediate-temperature solid oxide fuel cells. The effect of Y-doping on the crystal structure, oxygen vacancy concentration, thermal expansion coefficient (TEC), electrical conductivity and cathode performance of Pr1−xYxBaCo2O5+δ was investigated. These properties were compared with that of GdBaCo2O5+δ having a middle element of lanthanides. Pr1−xYxBaCo2O5+δ shows TEC (∼17.6 × 10−6 K−1) lower than that of undoped PrBaCo2O5+δ, but similar to the one for GdBaCo2O5+δ. Y-doping causes a decrease in electrical conductivity, but at the same time induces an increase in oxygen vacancy concentration. With increasing Y-doping level, the area specific resistance (ASR) of Pr1−xYxBaCo2O5+δ-based electrode in a symmetrical cell increases, and correspondingly, the peak power density of single-cell decreases slightly. Nevertheless, comparing to GdBaCo2O5+δ-based electrode, Pr1−xYxBaCo2O5+δ (x = 0.3–0.7) exhibits significantly lower ASR, and allows to obtain cells with higher maximum power density.