Information content of the voltage vs. current curve of a solid oxide fuel cell

Abstract

Relationships are derived by means of which data on the ionic and electronic conductivity of the electrolyte employed in a fuel cell can be calculated from the U-I curves of the cell, provided that certain conditions in regard to the extent of electrode polarization are met. The capability and limitations of the resulting equations are demonstrated on the basis of known data on the ionic conductivity of gadolinia doped ceria. By applying the relationships to recently published performance data of fuel cells with CuFeO2 as electrolyte or as part of a composite electrolyte, the partial conductivities of this oxide are quantified for the first time. The results prove that CuFeO2, known to be a good mixed ionic-electronic conductor, exhibits unexpectedly high oxygen-ion conductivity under the operating conditions of a fuel cell.