Effect of Cobalt-Doped Electrolyte on the Electrochemical Performance of LSCFO/CGO Interfaces

In this work, we have studied La0.4Sr0.6Co0.8Fe0.2O3-delta/Ce0.8Gd0.2O2-delta./La0.4Sr0.6Co0.8Fe0.2O3-delta symmetrical cells containing Ce0.8Gd0.2O2-delta electrolytes synthetized with and without the addition of cobalt as sintering aid. Electrochemical impedance spectroscopy results indicate that both electrolyte and cathode impedance response are affected by the addition of Co to the electrolyte, despite using cathodes with similar nano/microstructure according to scanning electron microscopy observations. Transmission electron microscopy characterization revealed the formation of columnar structures at the cathode/electrolyte interface of the cell with Co-doped electrolyte. These columnar structures would negatively affect the cell performance hindering the diffusion of oxide ions from the cathode to the electrolyte.