From theory to experiment: BaFe0.125Co0.125Zr0.75O3−δ, a highly promising cathode for intermediate temperature SOFCs

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-02, Vol.8 (6), p.3413-3420
• Main Authors: Sánchez-Ahijón, Elena, Marín-Gamero, Rafael, Molero-Sánchez, Beatriz, Ávila-Brande, David, Manjón-Sanz, Alicia, Fernández-Díaz, M Teresa, Morán, Emilio, Schmidt, Rainer, Prado-Gonjal, Jesús
• Format: Article
• Language: English
• Subjects: Cathodes; Citric acid; Conduction; Electrochemical impedance spectroscopy; Electrochemistry; Electrolytes; Electrolytic cells; Fuel technology; Impedance; Neutron diffraction; Oxygen; Solid oxide fuel cells; Spectroscopy; Spectrum analysis; Synchrotron radiation; Temperature; Thermal expansion; Vacancies; X-ray diffraction
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c9ta12208g

In a recent theoretical study [Jacobs et al., Adv. Energy Mater., 2018, 8, 1702708], BaFe0.125Co0.125Zr0.75O3−δ was predicted to be a stable phase with outstanding performance as an auspicious cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). It is shown here that the theoretical predictions are valid. The material can be synthesized by the citrate method as a single cubic Pm3m phase with a significant amount of oxygen vacancies, randomly distributed in the anionic sublattice facilitating oxygen vacancy conduction. A thermal expansion coefficient of 8.1 × 10−6 K−1 suggests acceptable compatibility with common electrolytes. Electrochemical impedance spectroscopy of symmetrical cells gives an area-specific resistance of 0.33 Ω cm2 at 700 °C and 0.13 Ω cm2 at 800 °C. These values are reduced to 0.13 Ω cm2 at 700 °C and 0.05 Ω cm2 at 800 °C when the material is mixed with 30 wt% Ce0.9Gd0.1O2−δ.