Oxide ion and proton conduction in doped ceria—carbonate composite materials

摘要

The direct current four-probe method has been employed to investigate the conduction of oxide ion and proton in a doped ceria-carbonate composite electrolyte for fuel cells. The measurements are conducted in oxygen and in hydrogen atmospheres in the temperature range of 425-650 ℃. The conductivities of both of O~2 and H~1 increase with the increase of carbonate content above the melting point of the carbonate. The ionic conductivities of the composite electrolytes have also been simulated using the effective medium percolation theory. The deviations between experimental results and simulated values of O~2 conductivity are caused by the associating effect of ceramic and carbonate phases, which leads to a higher O~2 migration energy through the phase interface. According to the comparison of experimental data and simulated values, the conduction mechanisms of O~2 and H~1 have been proposed.