Atomic-scale mechanisms of oxygen electrode delamination in solid oxide electrolyzer cells

Materials used for different components (electrodes, electrolyte, steel interconnects, etc.) of solid oxide electrolyzer cell (SOEC) devices for hydrogen production have to function in aggressive, corrosive environments and in the presence of electric fields. This results in a number of degradation processes at interfaces between components. In this study, we used a combination of first-principles, density-functional-theory (DFT) calculations and thermodynamic modeling to elucidate the main processes that contribute into the oxygen delamination in typical SOEC device consisting of yttria-stabilized zirconia (YSZ) electrolyte and Sr-doped LaMnO3 (LSM) oxygen electrode. We found that high temperature inter-diffusion of different atoms across the LSM/YSZ interface significantly affects structural stability of the materials and their interface. In particular, we found that La and Sr substitutional defects positioned in ZrO2 oxide and near LSM/YSZ interface significantly change oxygen transport which may develop pressure buildup in the interfacial region and eventually develop delamination process. Simple models for estimating these effects are proposed, and different possibilities for inhibiting and/or mitigating undesirable delamination processes are discussed.