Stationary 2D FEM Model Framework for SOFC Stack Performance Prediction

Abstract

It is a well-known fact, that high-performing anode-supported cells (ASCs) undergo a significant power reduction when contacted in a stack by metallic interconnectors (MIC) with a specific flow field design (1,2). For profound investigations, a model framework has been presented in previous studies (3-5) which uniqueness is based on its strict use of in-house determined material parameters and validation measurements over broad range of operating conditions. Included are the physically coupled processes (i) electrical/ionic conduction in electrode/electrolyte material, (ii) electrochemical charge transfer at the electrode/electrolyte interfaces and (iii) porous media gas species transport in the porous electrodes [5]. It has become clear that O2 starvation underneath the MIC contact rips and/or electrical cross conduction limitations in the cathode material underneath the gas channel area creates performance losses, which add up additionally for each individual stack layer to the standard cell polarization losses. It will be shown in this work, why (i) by adding a current collector layer (CCL) losses are reduced, that (ii) the degree of loss reduction is highly dependable on CCL thickness and microstructure and that (iii) the overall performance can further be improved by a well-chosen MIC contact rip thickness.