A modeling framework is presented based on a stationary finite element method (FEM) model. The model geometry is a twodimensional repeat unit representing all individual layers of an anode supported cell sandwiched between metallic interconnect (MIC) structures. The model is capable of analyzing performance limiting factors for planar solid oxide fuel cell (SOFC) stacks. These factors arise from material composition, microstructure, layer thickness, or MIC flowfield design. Herein, setup and validation of the modeling framework are presented and discussed in detail. Charge-transfer chemistry is modeled with detailed Butler-Volmer kinetics. Ion and electron conduction is modeled with Ohm's law and porous-media gas species transport is represented by the Dusty-Gas model. All physical parameters in the model equations were determined by our own measurements, conducted on anode supported cells and components thereof. The stationary finite element model was validated against measured current/voltage characteristics for a temperature range of 621 to 871 • C, fuel humidification from 5.5% to 60%, and current densities up to a maximum of 2 A/cm 2 . This more than exceeds the standard operating range for multi-kW SOFC stack units. The applicability of the model is demonstrated using the electrical and dimensional data of anode supported cells and the MIC design similar to stationary 5 and 10 kW stacks (from Forschungszentrum Jülich). It is shown that the MIC flow field design induces gas transport limitations and electronic current constrictions in the cell components. The simulation results clearly indicate the cathode layer thickness as the most sensitive factor in limiting stack performance.Although the performance of planar solid oxide fuel cells (SOFC) at the single cell layer has been continuously improved over the past decade, 1 there are vast optimization potentials at stack-level, where the area specific power density decreases by 50%. 2 Stacking single cells sandwiched between metal interconnects (MICs) is a practical way to increase the voltage of SOFC systems. The MIC structure, however, contributes massively to immediate power losses and the long term degradation of cells. The applied MIC material, a ferritic high-temperature steel, emits chromium species that poison the SOFC cathode, thereby inducing a strong degradation of the stack performance in the long-term. 3-6 Independent thereof, the ab initio power loss compared to single cells is inherently determined by the interconnector design. 6 Besides providing current collection, MICs also act as gas flow manifold, providing the porous electrodes with gaseous reactants. Common MIC designs accordingly feature contact ribs and gas channels in a parallel setup. Underneath the gas channel, current constriction arises from non-ideal electronic pathways in the porous electrode structures. Meanwhile, non-ideal gas supply beneath the contact rib induces gas transport limitations. As of the moment of writing, there is no overall understanding of how these system-imma...

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The potential of MS-SOFCs was demonstrated through the previous EU METSOFC project, which concluded that the development of oxidation resistant novel metal-supported solid oxide fule cell (MS-SOFC) design and stack is the requirement to advance this technology to the next level. The following EU METSAPP project has been executed with an overall aim of developing advanced metal-supported cells and stacks based on a robust, reliable and up-scalable technology. During the project, oxidation resistant nanostructured anodes based on modified SrTiO 3 were developed and integrated into MS-SOFCs to enhance their robustness. In addition, the manufacturing of metal-supported cells with different geometries, scalability of the manufacturing process was demonstrated and more than 200 cells with an area of~1 50 cm 2 were produced. The electrochemical performance of different cell generations was evaluated and best performance and stability combination was observed with doped SrTiO 3 based anode designs. Furthermore, numerical models to understand the corrosion behavior of the MS-SOFCs were developed and validated. Finally, the cost effective concept of coated metal interconnects was developed, which resulted in 90% reduction in Cr evaporation, three times lower Cr 2 O 3 scale thickness and increased lifetime. The possibility of assembling these cells into two radically different stack designs was demonstrated.

High performance anode–supported cells (ASC), contacted in a planar stack by metallic interconnectors (MIC), undergo a significant power density reduction. Performance limiting factors originating from the MIC-design were identified by detailed experimental data analysis and via a straightforward FEM simulation. Conclusively, gas diffusion polarisation contributes close to the sum of all ohmic losses to the overall polarization, both controlling stack performance. Based on this knowledge, a multiphysic-FEM-model was developed, considering coupled ohmic, gas diffusion and nonlinear polarization losses in the electrodes and ohmic losses in the electrolyte. Consequential ASC-performance depends over a broad range of operating conditions on i) an optimal MIC-design and ii) a well-chosen cathode thickness increases the overall power output.

This work presents a non-isothermal 2D FEM gas channel model, capable of performance predictions for hydrocarbon-fueled SOFC stack layers. Therefore, a previously developed isothermal model, incorporating relevant loss mechanisms for SOFC operated on hydrocarbons, was extended by implantation of the energy balance equations. Heat transport is described in a physically meaningful way by heat conduction, convection and radiation. This enables the model to predict the spatial temperature distribution within Ni/YSZ-based SOFC while taken into account the different loss mechanisms. Furthermore, the deactivation of active catalyst surface area via sulfur poisoning is considered by implementing surface area-dependent reforming kinetics. This global kinetic approach was determined by measuring the conversion of fuels containing different amounts of H 2 S in a specialized test rig with gas extraction and temperature tracking probes along the gas channel. The presented results show how poisoning of the Ni surface will affect the reforming-activity.