Joint research project ElChFest: Electro-chemo-mechanical modeling of ceria-based solid oxide electrolysis cells - Electrochemical characterization, modeling and simulation

The overall goal of the "ElChFest" project is the model-based optimization of cerium oxide-based electrolytic cells. The doped cerium oxide exhibits an electro-chemo-mechanical activity that leads to an expansion of the crystal lattice (chemical expansion) at low oxygen electrochemical potential. Apparently, this causes local stresses and the formation of microcracks in the structure. "ElChFest" addresses the problem of electro-chemo-mechanical activity through an interdisciplinary approach aimed at preventing the mechanical failure of the cell and harnessing the high performance of the cell. A three-dimensional electro-chemo-mechanical modeling should make it possible to predict the relationships between the chemical expansion of the Gd-doped cerium oxide (GDC) in the layered structure of the cell, the operating parameters and the resulting cracking in the electrolyte. Optimal design parameters for the cell as well as safe operating ranges are determined via simulations, thus enabling knowledge-based optimization of the cell. The optimized cell with Ni-GDC fuel gas electrode and GDC electrolyte will establish the next generation of cathode-supported SOEC.

The focus at KIT, IAM-ET is in the area of electrochemical characterization and modeling of cells developed by the project partner FZ Jülich. In the modeling, homogenized (equivalent circuit) models for the analysis of the impedance spectra as well as spatially resolved 3D models for the simulation of the distribution of the chemical oxygen potential in the GDC phase are used. The spatially resolved models use 3D microstructure reconstructions (FZ Jülich) and provide the chemical data for modeling the chemo-mechanical stresses (KIT-IDM). The cells are optimized at the FZ Jülich on the basis of electrochemical (IAM-ET) and mechanical (KIT-IDM) simulations.