Exploring Mixed Protonic/Electronic Conducting Oxides as Cathode Materials for Intermediate Temperature SOFCs Based on Proton Conducting Electrolytes

摘要

Novel mixed protonic/electronic conducting perovskite oxides. BaZr_(0.8-x)Pr_xY_(0.2)O_(3-δ)(BZPYx, 0.1 < x < 0.4), were investigated for use as cathode materials in intermediate temperature solid oxide fuel cells (IT-SOFCs) based on proton conducting electrolytes. Chemical stability tests showed that BZPYx oxides were stable in the presence of CO_2 and water vapor. Conductivity measurements of BZPYx were performed in wet (3% H2O) air atmosphere using electrochemical impedance spectroscopy analysis. Ionic and electronic transport numbers were calculated from conductivity measurements at different oxygen partial pressures, using an established defect model. For all the compositions, electronic conduction decreased with decreasing the temperature. Varying the Pr content, it was found that the ratio between the electronic and ionic conductivity was dependent on the Pr content, being the electronic conductivity proportional to Pr content.