A SrCo0.9Ta0.1O3-δ derived medium-entropy cathode with superior CO2 poisoning tolerance for solid oxide fuel cells.

The development of highly efficient and robust cathodes is crucial for intermediate temperature solid oxide fuel cells (IT-SOFC). Perovskite type SrCo 0.9 Ta 0.1 O 3-δ (SCT91) is a promising cathode but its instability against CO 2 limits the practical application. In this work, a new medium-entropy SrCo 0.5 Fe 0.2 Ti 0.1 Ta 0.1 Nb 0.1 O 3-δ (SCFTTN52111) cathode is designed and evaluated. The effect of configuration entropy on electrical conductivity, physical and electrochemical properties are studied in detail. The SCFTTN52111 cathode exhibits a lower polarization resistance of 0.033 Ω cm2 at 700 °C, superior to 0.040 Ω cm2 of SCT91 parent. The higher oxygen reduction activity is attributed to its larger surface exchange coefficient and smaller particle size. More importantly, SCFTTN52111 displays outstanding stability and high CO 2 tolerance, due to a more negative value of average metal-oxygen bond energy and significantly reduced surface Sr segregation. Our study provides a feasible and effective entropy engineering approach to design high-active and durable cathode materials for SOFCs. [Display omitted] • A medium-entropy cathode is developed for IT-SOFC. • SCFTTN52111 achieves a low polarization resistance of 0.033 Ω cm2 at 700 °C. • Greatly suppressed Sr segregation is found in medium-entropy cathode. • SCFTTN52111 shows superior resistance towards CO 2 poisoning. • Tailoring configuration entropy is a promising approach for new cathode design. [ABSTRACT FROM AUTHOR]