A Model of Solid Oxide Fuel Cell Degradation on a Microstructural Level

Marko Nerat

doi:10.3390/app10061906

Abstract

The growth of nickel (Ni) particles in the porous anode is one of the most critical issues in solid oxide fuel cells (SOFC). It reduces the density of triple-phase boundaries (TPBs) over time and increases the polarization resistance of SOFC. Most of the three-dimensional models that are used to simulate this phenomenon in detail are numerically exhausting and as such intractable for on-line applications. This work presents a two-dimensional, microstructural model of reduced complexity as a trade-off between the numerical load and the level of detail. The model of Ni agglomeration is based on the power-law coarsening theory. The resulting model was validated by comparing the relative density of TPBs and the cell voltage to the experimentally measured values. It was shown that the calculated values closely fit the measured data. The advantage of the proposed model is that it takes lower computational load during the simulation compared to the complex phase field models and is suitable for estimation of SOFC electric performance over time.

Highlights

Solid oxide fuel cell (SOFC) systems are a promising technology for stationary applications since they convert hydrogen (H2 ) directly into electricity at high conversion efficiency (η) [1]
The reduced-complexity, two-dimensional, microstructural model of solid oxide fuel cells (SOFC) was proposed since a numerically tractable model is sought for online evaluation of SOFC electric performance degradation
The SOFC degradation that occurs at high temperature due to the nickel agglomeration in the anode was modeled by using power law coarsening theory

Summary

Introduction

Solid oxide fuel cell (SOFC) systems are a promising technology for stationary applications since they convert hydrogen (H2 ) directly into electricity at high conversion efficiency (η) [1]. SOFCs can be fueled with some other hydrocarbon gases (e.g., methane) that need to be reformed externally in a reformer [3] or internally within the cell [3,4]. The major drawbacks of using SOFC systems are relatively high manufacturing costs and a fast degradation rate. One of the most critical issues is structural degradation of the porous anode due to nickel (Ni) agglomeration. Ni agglomeration increases the polarization resistance of SOFC since it decreases the density of electrochemical reaction sites within the anode active layer

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