​The solid-oxide electrolyzer cell (SOEC), made up of an electrolyte “sandwiched" between two electrodes, converts water vapor into hydrogen via electrochemical reactions. During these reactions, one of the most commonly-used oxygen-electrode materials, LSCF (La0.6Sr0.4Co0.2Fe0.8O3-d), undergoes degradation that has been demonstrated in lab experiments to be the biggest contributor to yield losses. The challenge is that the phenomena that underpin the degradation of the electrode material occur at the atomic scale and are thus difficult to observe. Our researchers decided to use multi-scale modeling combined with ab initio calculations based on the density functional theory (DFT) method to better understand these phenomena. The electrodes were very stable according to calculations based on initial models of a controlled, pollutant- and moisture-free atmosphere. These results, which stand in stark contrast to the severe electrode degradation observed in lab experiments, indicate that impurities in the environment are to blame for degradation. Another study, this one of the oxygen molecule reduction reaction (ORR) was then carried out. Looking at the intermediate reactions that make up the overall reaction generated new insights into where, exactly, the overall reaction gets slowed down, impacting performance. 

DFT calculations can provide a deeper understanding of the difficult-to-observe mechanisms that occur inside SOEC materials. The tool developed here will now be used to improve the durability and performance of SOEC materials in the lab. However, it could also help qualify and perhaps even develop new, more durable, higher-performance electrode materials.