Nd2−xGdxZr2O7 electrolytes: Thermal expansion and effect of temperature and dopant concentration on ionic conductivity of oxygen

• Published in: International journal of hydrogen energy Vol. 39; no. 16; pp. 8437 - 8448
• Main Authors: Razmkhah, M., Mosavian, M.T. Hamed, Moosavi, F.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 27.05.2014; Elsevier
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Complex dopant; Energy; Exact sciences and technology; Fuels; Hydrogen; Molecular dynamics simulation; Oxygen ion conductivity; Solid oxide fuel cells; Structural behavior; Zirconia solid oxide electrolyte; Complex dopant; Solid oxide fuel cells; Zirconia solid oxide electrolyte; Molecular dynamics simulation; Structural behavior; Oxygen ion conductivity; Hydrogen; Ionic conductivity; Solid electrolyte; Molecular dynamics; Solid oxide fuel cell; Zirconia; Thermal expansion; Zirconium oxide
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2014.03.177

The effect of temperature and complex dopant composition on oxygen ion conductivity in solid oxide electrolyte fuel cells was investigated by atomistic molecular dynamics simulation. A new electrolyte (Nd2−xGdxZr2O7) was selected to study oxygen ion conductivity using three Gd compositions (x = 0.8, 1.0, and 1.2) in a wide range of temperature (T = 1273 K–1873 K). MSD results of cations showed these groups of electrolyte are stable at high operating temperature. The first composition (x = 0.8) had the highest ionic conductivity that was in good agreement with the experimental data. A simple effective model that works with configuration energy of the oxygen crossing plate was applied to explain the observed conductivity trend. The model illustrated the point as well. Increasing Gd concentration decreases existence probability of easy crossing plate. Radial distribution function analysis also confirmed results. Thermal expansion of the electrolyte has a major effect on the selecting of the electrolyte materials; thus, this important factor was also studied. Results showed the first composition had the greatest thermal expansion. [Display omitted] •Proposing new electrolytes and investigating their ionic conductivity.•Studying the effect of temperature and dopant composition on the ionic conductivity of electrolytes.•Presenting a simple model to shed light on the unclear part of the ionic conductivity.•Investigating the thermal expansion of the electrolytes.