Hot corrosion of Gd2O3-doped CeO2 electrolyte in solid oxide fuel cells with a liquid antimony anode

Abstract

Direct carbon solid oxide fuel cell has garnered increasingly attention due to its high conversion efficiency. However, when a liquid metal is used as the anode, the electrolyte is subjected to hot corrosion by the liquid metal and its oxide. In the present study, both chemical and electrochemical corrosions of Gd2O3-doped CeO2 electrolyte by liquid Sb and Sb2O3 are conducted at 750 °C for up to 100 h to simulate the situations occurring in the direct carbon solid oxide fuel cell. The tested specimens are characterized by a scanning electron microscope and an electron probe micro-analyzer. In the case of chemical corrosion, both liquid Sb and Sb2O3 penetrates into grain boundaries of the electrolyte, resulting spallation of grains from the bulk. The depth of liquid Sb penetration is deeper than that of liquid Sb2O3. Electrochemical corrosion of the electrolyte by liquid Sb occurs in the same way as the chemical corrosion at an increased rate promoted by applied current. It is also found that the electrochemical corrosion of the electrolyte by liquid Sb improves the cell performance with the sacrifice of electrolyte.