Polarization Resistance of Ceria-Containing Fuel Electrodes in Solid Oxide Cells Studied By Impedance and DRT Analysis

Abstract

Solid oxide electrolysis cells (SOECs) can be used to perform steam electrolysis in a process which is the reverse of power generation using a solid oxide fuel cell (SOFCs). They are capable of highly efficient hydrogen production. In this study, various model fuel electrode materials were compared and evaluated over a wide range of current densities in both SOFC and SOEC modes. Here, we prepared three types of cells: (i) with a conventional Ni-scandia-stabilized-zirconia (Ni-ScSZ) cermet fuel electrode, (ii) with a Ni-gadolinia-doped ceria (Gd0.1Ce0.9O2, Ni-GDC) cermet fuel electrode, and (iii) with a Ni-GDC co-impregnated fuel electrode fabricated by the co-impregnation method. The electrode reactions are characterized through measurements of electrochemical impedance spectra (EIS) and subsequent analysis of distribution of relaxation times (DRT). The results suggest that the use of mixed ionic and electronic conductor GDC as a fuel electrode material is advantageous especially in SOEC operation mode.