Comparative study of electrochemical properties of different composite cathode materials associated to stable proton conducting BaZr_0.7Pr_0.1Y_0.2O_3-δ electrolyte

Highlights: • BaZr_0.7Pr_0.1Y_0.2O_3-δ (BZPY) powders were synthesized by an EDTA-citrate complexation process. • BZPY exhibits excellent chemical stability in atmospheres containing CO₂ and water vapor. • LSCF-BZPY and LSCF-SDC composite cathodes are fabricated and evaluated for IT-SOFCs. • Proton electron mixed conducting composite cathodes are promising and beneficial. - Abstract: High-temperature proton conductor BaZr_0.7Pr_0.1Y_0.2O_3-δ (BZPY) was investigated as electrolyte for intermediate temperatures (400-800 °C) solid oxide fuel cells (IT-SOFCs), which exhibited excellent chemical stability in atmospheres containing CO₂ and water vapor. In addition, both La_0.4Sr_0.6Co_0.2Fe_0.8O_3-δ-BaZr_0.7Pr_0.1Y_0.2O_3-δ (LSCF-BZPY) and La_0.4Sr_0.6Co_0.2Fe_0.8O_3-δ-Ce_0.8Sm_0.2O_1.9 (LSCF-SDC) composite oxides were fabricated and evaluated as working cathodes for anode-supported IT-SOFCs based upon thin BZPY electrolytes. The single cells with LSCF-BZPY cathode showed the maximum power density of 86.7 mW cm⁻² at 700 °C and the calculated activation energy was 91.19 kJ mol^-1. While the cells with LSCF-SDC cathode exhibited the higher maximum power density of 112.4 mW cm⁻² at 700 °C and the calculated activation energy was 101.61 kJ mol^-1. The experimental results indicated that proton electron mixed conducting composite cathodes are more promising and beneficial than oxygen-ion electron mixed conducting composite cathodes for proton-conducting SOFCs during actual low operating temperatures