Kinetic Modeling of Nickel Oxidation in SOFC Anodes

Kurzfassung

Understanding the mechanisms of performance degradation is of key importance for increasing the lifetime of solid oxide fuel cells (SOFC). The aim of this work is to achieve a deeper understanding of the processes leading to nickel oxidation at Ni/YSZ composite anodes. We present a kinetic model of chemical nickel oxidation which was integrated into a two-dimensional model of an anode-supported single cell. The feedback between nickel oxidation and cell performance was modeled by taking into account both, a loss in kinetic performance (via reducing three-phase boundary length) and a reduction in gas-phase diffusivity (via porosity decrease upon solid volume expansion). The simulations allow the quantification of nickel oxide formation over time and its influence on the cell performance.