B-site doping effect of double perovskite for cathodes of solid oxide fuel cells

BackgroundThe performance of solid oxide fuel cells (SOFCs) can be promoted by optimizing cathode materials.PurposeThis study aims to boost the electrochemical performances of cathodes for SOFCs by doping transition metal at the B-site of double perovskite.MethodsFirstly, a series of B-site doped PrBa0.8Ca0.2Co2O5+δ (PBCC) oxides as cathodes for SOFCs were prepared by sol-gel. The effects of B-site doped content and doped elements on the crystalline structure of the cathodes were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). Then, the trends of conductivity and thermal expansion coefficient with B-site doped PBCC oxides were investigated. Finally, the electrochemical performances of cathodes with different B-site doped PBCC oxides were tested to find optimal doping element type and content.ResultsTest results show that polarization is reduced and the electrochemical catalytic activity is improved when 5 mol% of Fe is doped on the B-site of the PBCC cathode. Compared to the PBCC cathode, the max power density of the full cell with a 5-mol% Fe-doped cathode increases from 988 mW∙cm-2 to 1 259 mW∙cm-2 at 700 ℃.ConclusionsThe electrochemical performances of SOFCs can be boosted by modifying the B-site of double perovskite using transition metal.