Computational Design and Experimental Validation of the Optimal Bimetal-Doped SrCoO3-δ Perovskite as Solid Oxide Fuel Cell Cathode.

ABSTRACT

Strontium cobaltite-based perovskites (SrCoO3-δ) have been widely studied as a promising cathode for the next-generation solid-oxide fuel cell (SOFC). Here, we found a balance between oxygen vacancy (VO) formation and its migration in designing SrCoO3-δ-based materials by using two activity descriptors, i.e., radius and electronegativity. The ORR activity of these types of perovskites is found to strongly rely on the two proposed descriptors, and Nb- or Ta-doped SrCoO3-δ locates in the promising zone as predicted with a moderate value of both VO formation energy and ion migration barrier. Then Sc-Ta co-doped SrCoO3-δ (SSTC) and Sc-Nb co-doped SrCoO3-δ (SSNC) are screened out to be the best among 91 bimetal-doped SrCoO3-δ perovskites. Further experiments have been carried out to synthesize the co-doped SSTC and prove ultralow area-specific resistance values (0.071, 0.198, and 0.701 Ω·cm2 at 550, 500, and 450 °C, respectively), which is only one-third of that of benchmark materials for the SOFC cathodes. Our results open a novel pathway in designing SOFC cathodes with an optimal performance.