Understanding electro-chemo-mechanical stresses in ceria-based solid oxide electrolysis cells using virtual microstructures

Solid oxide electrolysis cells (SOEC) based on a thin ceria electrolyte show excellent performance, but suffer from mechanical instability due to expansion of the ceria electrolyte. The cathodic overpotential of the fuel electrode increases the chemical expansion, which couples the expansion to the operation conditions and can lead to electro-chemo-mechanical failure of the cell. Among the possible mitigation strategies is the optimization of the microstructure to minimize chemical stresses during operation. However, changing individual features of the microstructure experimentally can be extremely time-consuming and even impossible, as the cell production couples the microstructure evolution of support, electrode and electrolyte during sintering. Here, we present an innovative approach using a microstructure generator to tailor synthetic microstructures and examine the influence of microstructural parameters, such as particle size, density, or electrolyte thickness, on the predicted mechanical stresses during operation. This approach yields correlations between microstructure and chemical stresses with greatly reduced effort compared to an experimental approach, and highlights the potential of digital materials design.