Sinterability, Mechanical, Microstructural, and Electrical Properties of Gadolinium-Doped Ceria Electrolyte for Low-Temperature Solid Oxide Fuel Cells

In this study, we report key functional properties of gadolinium-doped ceria (Gd0.1Ce0.9O1.95, GDC) sintered at low temperatures as well as single-cell electrochemical performance of a single-cell prepared there of. GDC solid solutions were sintered at various temperatures ranging 1100–1400∘C and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), density measurements, mechanical strength tests and electrical conductivity measurements. The dry-pressed GDC disc sample sintered at 1100∘C was found to have 96% of the theoretical density and higher sintering temperatures led to higher densities. SEM micrographs of the fracture and plan surfaces of the sintered discs established the absence of any open pores. The sample sintered at 1100∘C exhibited high electrical conductivity of 0.027 S/cm at 650∘C. The mechanical strength of the sintered samples was determined to be in the range of 150–175 MPa. Greater than 96% of theoretical density, good mechanical strength, and high electrical conductivity of GDC disc samples sintered at 1100∘C established the viability of low-temperature processing of GDC for its use as an SOFC electrolyte. Accordingly, a single-cell was prepared by co-sintering of GDC electrolyte and LSCF-GDC cathode at 1100∘C and subsequent firing of CuO-GDC anode at 900∘C. The electrochemical performance of the cell was evaluated in H2 fuel at 650∘C.