Stability and electrochemical performance of lanthanum ferrite-based composite SOFC anodes in hydrogen and carbon monoxide

We here report a lanthanum ferrite-based perovskite anode La_0.9Ca_0.1Fe_1-xNb_xO_3-δ (LCFNbx, x = 0, 0.05, 0.1 and 0.2) for solid oxide fuel cells (SOFCs) with intriguing stability and electrochemical performance. The powders were prepared by citric acid-nitrate method. The LCFNbx/ScSZ ((Sc₂O₃)_0.1(CeO₂)_0.01(ZrO₂)_0.89) composite anodes were constructed by infiltrating the corresponding metal nitrate solution into the ScSZ scaffold followed by heat treatment. X-ray diffractometer results indicated that Nb doping in B site can stabilize the material in the reducing atmospheres up to 800°C. The chemical stability of LCFNb_0.1 is attributed to the constrained valence stability of Fe by the Nb introduction in highly charged state. The maximum power densities of the cell with LCFNb_0.1/ScSZ composite anode were 467.1 and 375.8 mW/cm² in H₂ and CO at 750°C, respectively. The area specific resistances of the cell at open circuit voltage were 0.75 and 2.30 Ωcm², respectively. Scanning electron microscopy results showed that the LCFNb_0.1 layer was porous and well adhered to the ScSZ scaffold, which facilitated the electrochemical processes in H₂ and CO. The obtained results in this paper indicate that the LCFNb_0.1/ScSZ is a promising composite anode for the SOFCs with both high stability and high electrochemical performance in H₂ and CO.