Mechanical characterization of SOFC/SOEC cells

Mechanical reliability is one main prerequisite for the long-term operation of Solid Oxide Fuel Cells (SOFCs) and Solid Oxide Electrolysis Cells (SOEC) in stacks and systems. Hence, key mechanical properties were derived for cells to be used in Jülich stacks and systems. Since assembling and joining is typically carried out in oxidized state, whereas operation requires reduction of the anode, mechanical characterizations are performed for cells in oxidized and reduced state with additional consideration of elevated temperature behavior as well as possible mechanical degradation due to subcritical crack growth. In particular, fracture strength, elastic modulus and residual stress for half-cells were assessed. With respect to fracture strength, also subcritical crack growth at different temperatures has been analyzed, being the basis of a derived strength-probability-time plot. Overall, the work provides parameters for determination of failure probability and lifetime prediction.