Novel structured mixed ionic and electronic conducting cathodes of solid oxide fuel cells

A novel structured mixed ionic and electronic conducting cathode was developed based on the (LaSr)MnO3 (LSM) electronic conducting structure impregnated with Gd-doped CeO2 (GDC) ionic conducting phase. The ion impregnation of oxygen ion conducting GDC phase significantly enhances the electrocatalytic activity of the LSM electrodes for the O2 reduction reactions and eliminates the activation effects of the cathodic polarization associated with pure LSM. With impregnation of 5.8 mg cm−2 GDC in the LSM electrode coating, the electrode showed much lower electrode polarization resistance (RE) as compared to those of LSM/Y2O3-ZrO2 and LSM/GDC composite cathodes and the performance was comparable with those of mixed ionic and electronic conducting oxides such as (LaSr)(CoFe)O3 and (GdSr)CoO3. This is most likely due to the unique combination of the high electronic conducting LSM porous structure with high ionic conducting nano-sized GDC phase. The results demonstrated that high oxygen ion conductivity can be developed into conventional and dominant electronic conducting LSM materials by the simple ion impregnation method.