Highly active and stable zirconium-doped Fe-based cathodes for solid oxide fuel cells

Designing and developing highly active and stable cathode materials is of great concern to large-scale commercial applications of solid oxide fuel cells (SOFCs). Herein, a series of perovskite oxides, La_0.5Ba_0.5Fe_1-xZr_xO_3-δ (LBFZ_xO, x = 0∼0.075), are synthesized and systematically assessed. All LBFZ_xO samples present cubic perovskite structure and possess better chemical compatibility with the SDC electrolyte. The introduction of Zirconium into the parent material yields lower thermal expansion coefficient and higher oxygen vacancy. Among all the components, La_0.5Ba_0.5Fe_0.95Zr_0.05O_3-δ achieves the lowest polarization resistant (0.076 Ω cm²) and the highest power density (523 mWcm⁻²) at 800 °C, while rendering exceptional stability over a duration of 100 h. In addition, combining with the analyses of impedance and the distribution of relaxation times, the rate-determining steps for the entire oxygen reduction process are further clarified. The current research results highlight that La_0.5Ba_0.5Fe_0.95Zr_0.05O_3-δ is a viable cathode candidate for SOFCs.