Tailoring Pr0.5Sr0.5FeO3 oxides with Mn cations as a cathode for proton-conducting solid oxide fuel cells

The traditional Pr_0.5Sr_0.5FeO₃ (PSF) cathode is customized with Mn cations to generate the new Pr_0.5Sr_0.5Fe_0.9Mn_0.1O₃ (PSFMn) cathode for proton-conducting solid oxide fuel cells (H-SOFCs). Compared to the PSF oxide, the new PSFMn has a reduced thermal expansion, making it more compatible with electrolytes. Furthermore, Mn-doping enhances oxygen vacancy production in PSF, as revealed by experimental and first-principle calculations. More crucially, doping Mn into PSF improves proton diffusion kinetics, resulting in quicker proton diffusion and surface exchange. As a result, the H-SOFC with the PSFMn cathode achieves an output of 1446 mW cm⁻² at 700 °C, but the PSF cell only achieves fuel cell performance of 1009 mW cm⁻². The fundamental cause of the increased cell performance is the significantly reduced polarization resistance, implying that using the Mn-doping strategy enhances the cathode kinetics of conventional PSF cathodes for H-SOFC.