Electrochemistry of Reformate Fueled Ni/8YSZ Anodes for Solid Oxide Fuel Cells

Abstract

This paper reports a comprehensive understanding of the electrochemical polarization processes that determine the performance of reformate fueled Solid Oxide Fuel Cells with Ni/8YSZ anodes. State-of-the-art anode supported cells manufactured by Research Center Jülich (FZJ) were analyzed via electrochemical impedance spectroscopy (EIS). A detailed EIS study with the help of the distribution of relaxation times (DRT) method has lead to the identification of the individual polarization processes for reformate operation and the subsequent setup of a physically meaningful equivalent circuit. Quantitative kinetic analysis via a complex nonlinear least-squares (CNLS) fit-method revealed the mechanism of the electrochemical fuel oxidation at the anode. Numerical simulation demonstrates the coupling of reforming chemistry and gas transport in the anode structure. As an outlook, it is shown how the gained insights are applied to monitor the impact of sulfur-poisoning on (i) the electrochemistry and on (ii) the reforming chemistry in the anodes.