Sintering Mechanisms of Cobalt-Doped Ceria and Zirconia Electrolytes in Intermediate-Temperature Solid Oxide Fuel Cells

Abstract

Ce0.9Gd0.1O1.95 (CGO) and Zr0.79Sc0.2Ce0.01O1.9 (ScSZ) have been proposed as possible alternative electrolytes in intermediatetemperature solid oxide fuel cells (SOFCs). In this study, the mechanisms of densely sintering Co-doped CGO and ScSZ electrolytes during the SOFC fabrication process were investigated using synchrotron X-ray diffraction (SR-XRD) analysis. The addition of CoO enhanced the sintering characteristics of both CGO and ScSZ. Based on the results of SR-XRD analysis, it was found that CGO and CoO did not form a solid solution after heat treatment at 1100{degree sign}C for 10 h. On the other hand, the solubility limit of Co in ScSZ was estimated to be {less than or equal to} 3 mol % after firing at 1200{degree sign}C, and Co-doping accelerated the conversion of the two phases of the fluorite structure into a single cubic phase. The diffusion of Co into ScSZ is thought to assist the densification through reaction sintering.