Mechanical Characterization and Modeling Of Solid Oxide Fuel Cells and Stacks

摘要

Planar Solid Oxide Fuel Cells (SOFCs) are made up of repeating sequences of thin layers of cermet electrodes, ceramic electrolytes, seals, and current-collectors. For electro-chemical reasons it is best to keep the electrolyte layers as thin as possible. However, for electrolyte-supported cells, the thin electrolytes are more susceptible to damage during production, assembly, and operation. The latest-generation electrolyte-supported SOFCs employ a honeycomb-type support structure that includes both thick and thin regions within the electrolyte. The thin regions are more electro-chemically efficient, while the thick regions provide mechanical support. The performance of the electrolyte within the context of a mechanically and thermally loaded stack is being investigated. Temperature profiles are obtained from CFD models. Mechanical and thermal material properties are obtained from experiments with individual components. Single-component models are used to further characterize components with complex geometries, particularly the electrolyte and the compliant, electrically conducting metal foams. A 2-D stack model uses the data from experiments and single-component models to evaluate the mechanical response of the cells to loads comparable to those experienced in assembly and operation. The model is run both at room temperature and at operating temperature to determine which parameters can best reduce the demands on the brittle electrolyte without sacrificing electro-chemical efficiency.