Structural and Electrical Investigation of Co-Doped Ceria based Electrolytes for Fuel Cells

Abstract

In the fuel cell family, the most competent device for converting energy is the solid oxide fuel cell (SOFC) and has gained high considerable attention. The efficiency of SOFC highly depends on electrolyte materials that can work well at low temperatures. Ionic conductivity is good in a co-doped ceria-based electrolyte material. The most promising electrolyte materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) have been ceria and doped ceria because it shows good ionic conductivity at 600-800 ºC which is still very high and a barrier towards commercialization. Therefore, in this project, the co-doped ceria electrolyte materials (GBDC, CBDC and SBDC) were developed using sol-gel and co-precipitation method. The functionalities of electrolyte materials are investigated in this research. Prominent bands at peak positions 360, 461, 482, 600, 602, 1059 and 1080 cm−1 wavelengths are observed through Raman spectra of co-doped ceria electrolytes, analogous to GdO F2g mode, the first order F2g active mode of CeO2's cubic fluorite structure, structure of CeO2 that shows symmetric stretching modes of O ions around Ce ions, indication of Ca-O, and Ba-O. Ceria based materials behaves as an excellent electrolyte material. The vibratory characteristics are studied through FTIR spectroscopy; different peaks are obtained that indicates different vibrational modes. The direct band gap of the synthesized electrolyte materials were calculated by Tauc plot and obtained 2.5 and 1.5 eV of Gd0.1Ba0.1Ce0.8 .and Ca0.1Ba0.1Ce0.8 respectively. The structural properties are studied with the help of XRD and obtained a cubic fluorite structure of SBDC electrolyte material. DC Conductivity measurements of samples are evaluated by four point probe method. The sample CBDC has maximum ionic conductivity values of 0.82 Scm-1 at 400 ˚C temperature. The results indicate that developed ceria based electrolytes materials are good for SOFC.