High-performance, high-entropy perovskite cathodes for low-temperature solid-oxide fuel cells

The application of the high-entropy design principle has opened a number of new opportunities in terms of designing superior functional materials. One of the areas which can particularly benefit from that are air-electrodes for solid-oxide fuel cell technology (SOFC), currently suffering from the performance-functionality trade-off, observed in most state-of-the-art materials. In this work, it is demonstrated that careful optimization of La(Co,Cu,Fe,Mn,Ni)O 3-δ -based electrodes enables obtaining the performance typical for the low-temperature SOFC operation, with the cathodic polarization resistance R p values as low as 0.274 Ω cm 2 at 600 °C. This excellent value for an alkali-free material is obtained while preserving good thermomechanical behavior, and the chemical stability benefits of the Sr-free composition. The reasons behind this excellent performance are studied both experimentally and theoretically, showing that the presence of Cu in the system is responsible for the reported behavior, introducing synergistic effects outside of the rule-of-mixtures. In general, this study proves the potential of high-entropy approach as a powerful tool for designing SOFC materials, while simultaneously providing design guidelines for other materials to follow. • The properties of high-entropy La 1-x Sr x (Co,Cu,Fe,Ni)O 3-δ system are studied • The La(Co,Cu,Fe,Mn,Ni)O 3-δ has polarization resistance of 0.274 Ω cm 2 at 600 °C • The reported performance is the best ever reported for an alkali-free perovskite • The results indicate prominent role of Cu and Ni components