Tailoring SrFeO3 cathode with Ta and F allows high performance for proton-conducting solid oxide fuel cells

Abstract

To customize the traditional SrFeO₃ (SFeO) cathode for proton-conducting solid oxide fuel cells (H-SOFCs), a Ta cation and F anion co-doping approach is suggested. It has been discovered that Ta-doping can enhance the oxygen vacancy content and the protons' and oxygen's diffusion capacities, enabling improved H-SOFC performance. Ta-doping alone, however, only modestly enhances the cathode's performance, which is still below that of many newly created cathodes. The F anion co-doping is further introduced to further improve performance, resulting in the formation of the SrFe_0.9Ta_0.1O_2.9F_0.1 (SFeTOF) cathode. When SFeTOF is compared to the single Ta-doping material, its proton and oxygen diffusion properties are further improved, demonstrating the efficacy of using Ta and F co-doping for SFeO. Consequently, the fuel cell utilizing the SFeTOF cathode for H-SOFCs displays a fuel cell output of 1559 mW cm⁻² at 700 °C, notably higher than the fuel cell that uses SFeO or Ta-doped SFeO cathodes. The performance is likewise impressive among the H-SOFC cathodes that are now in use. Moreover, the fuel cell utilizing the SFeTOF cathode demonstrates sufficient operational stability in operating conditions, establishing SFeTOF as a reliable and effective cathode for H-SOFCs.