Rational Design of Two-Layer Fe-Doped PrBa0.8Ca0.2Co2O6-δ Double Perovskite Oxides for High-Performance Fuel Cell Cathodes

A solid oxide fuel cell (SOFC) offers an attractive route to convert chemical energy into electrical energy; however, its commercial application is often limited by the large mismatch in thermal expansion coefficients (TECs) between the cathode and electrolyte and the insufficient activity of cathodes. Fe-doped PrBa0.8Ca0.2Co2O6-delta (PBCC) are promising cathode materials due to their high conductivity and excellent oxygen-reduction activity, in which Fe doping in PBCC can decrease the TEC to achieve better compatibility with the electrolyte, but excessive Fe will inhibit the oxygen kinetics. Here, we construct a two-layer PBCC cathode (TLC), which consists of a high Fe content layer with good thermal compatibility to electrolytes and a low Fe content layer with high ionic and electronic conductivity. Compared to homogeneous PBCC electrodes, the cell with TLC has a lower activation energy and a higher peak power density (1259.3 mW cm(-2) at 700 degrees C). Meanwhile, it exhibits admirable stability up to 200 h in constant potential mode (0.8 V), and importantly, no discernible degradation is observed in further stability tests in the constant current mode (444 mA cm(-2)) for 200 h. The results reveal that the TLC based on double perovskite Fe-doping isostructural oxide is a promising candidate electrode for SOFC.

Automated summary

The double-layer PBCC cathode developed in this study shows promising performance in solid oxide fuel cells, with advantages in electrolyte compatibility and conductivity. Compared to traditional PBCC electrodes, the dual-layer structure cathode exhibits lower activation energy and higher peak power density.