Spatially Resolved Electrochemical Performance in a Segmented Planar SOFC

Abstract

Spatially inhomogeneous distributions of current density and temperature in solid oxide fuel cells (SOFC) can contribute significantly to electrode degradation, thermomechanical stresses, and reduced efficiency. A combined experimental and modeling study of the spatial distribution of electrochemistry was performed in order to determine local effects. A planar anode-supported SOFC single cell was locally characterized in a 4x4-segmented cell arrangement in dependence of gas composition and fuel utilization. A two-dimensional elementary kinetic electrochemical model was used to quantitatively interpret experimental observations. The model was validated by comparison to experiments under a wide range of operating conditions. When the cell was operated at high fuel utilization, both measurements and simulations show a strong variation of the electrochemical performance along the flow path. The simulations predict a considerable gradient of gas-phase concentrations along the fuel channel and through the thickness of the porous anode, while the gradients are lower at the cathode side.