Carbon and Redox Tolerant Infiltrated Oxide Fuel-Electrodes for Solid Oxide Cells

To solve issues of coking and redox instability related to the presence of nickel in typical fuel electrodes in solid oxide cells,Gd-doped CeO₂ (CGO) electrodes were studied using symmetriccells. These electrodes showed high electro-catalytic activity, butlow electronic conductivity. When infiltrated with Sr_0.99Fe_0.75Mo_0.25O_3-δ (SFM), the electronic conductivity wasenhanced. However, polarization resistance of the cells increased,suggesting that the infiltrated material is less electro-catalyticallyactive and was partly blocking the CGO surface reaction sites. Theactivity could be regained by infiltrating nano-sized CGO orNiCGO on top of SFM, while still sustaining the high electronicconductivity. Ohmic resistance of the electrodes was thuspractically eliminated and performance comparable to, or betterthan, state-of-the-art fuel electrodes was achieved. The Nicontaining cells were damaged by carbon deposition in a CO/CO₂-atmosphere, while none of the non-nickel cells catalyzed carbon.Stability towards redox cycles was also proven.