Development of composite LaNi0·6Fe0.4O3-δ-based air electrodes for solid oxide fuel cells with a thin-film bilayer electrolyte

In this study the bilayer composite electrodes based on LaNi0.6Fe0.4O3-δ (LNF) electronic conductor and Bi2O3-based electrolytes doped with Er (Bi1.6Er0.4O3, EDB) and Y (Bi1.5Y0.5O3, YDB) have been developed and their performance has been investigated in the dependence on the electrolyte content and sintering conditions. The polarization resistance of the optimized electrodes with electrolyte content of 50 wt % in the functional layer and with the LNF-EDB-CuO collector is in a range of 0.65–1.09 Ω cm2 at 600 °C and 0.10–0.12 Ω cm2 at 700 °C. The polarization characteristics of the Bi-based electrodes are compared with those for the composite electrodes based on LNF and Ce0.8Sm0.2O1.9 (SDC). The developed electrodes have been tested in a SOFC mode in the anode-supported cells with a thin film electrolyte of YSZ/YDC (Y-doped zirconia/ceria). The single cells with such cathodes are shown to have performance characteristics that are several times higher than that for the cell with a standard platinum cathode. This is due to the optimized content and dispersity of the components; high conductivity of ionic and electronic constituents of the composite electrodes; greatly extended triple phase boundary (TPB) of the electrochemical reaction and advanced electrode design with collector providing uniform current distribution.