Modeling of solid electrolyte based on ceria for intermediate temperature fuel cells

Impedance Spectroscopy (IS) is considered one of the most popular methods to the characterization of ceramic materials used as electrolytes for fuel cells, such as, solid oxide fuel cells (SOFCs) and intermediate temperature - solid oxide fuel cells (IT-SOFCs). However, experimental data analysis requires developing a model describing the electrical behavior of the solid electrolyte. The aim of this paper is to characterize the electrical behavior of sintered composite based on ceria using a new model. Therefore, the measurements of impedance components (Z\´ and Z"), of two composites based on ceria, designed to be used as solid electrolytes for intermediate temperature fuel cells (IT-SOFC) were performed by Impedance Spectroscopy (IS). The materials are two different composites based on ceria 10YDC + (10%) 150ppm YA (E1) and 10ScDC + (10%) 150ppm YA (E2), obtained by sol-gel method and sintered at temperature of 1500 °C. Two models (microstructural and electric) were applied for determining the electrical conductivity and permittivity of grains (σ_g and ε_rg) and grain boundaries (σ_gb and ε_rgb) values and the components of the complex impedance Z (Z\´ and Z") at different frequencies. The composite E1 presents better conductivities (σ_g and σ_gb) than E2 and it is favorable for use as solid electrolyte fuel cells.