First-Principles Calculations of Phase Stability, Electronic Structure, and Defect Properties of Perovskites for SOFC/SOEC Electrodes

Solid oxide fuel cells (SOFC) and solid oxide electrolyzer cells (SOEC), which transform chemical into electrical energy and vice versa, have the potential to make a significant contribution to the efforts of overcoming present problems of the energy economy in the near future. An optimal functionality of these devices requires a high catalytic activity at the electrodes, which strongly depends on point defect concentrations and on the capability of the material to allow for fast charge transfer reactions. Promising anode materials regarding these requirements are perovskite compounds (ABO\(_3\)), where the transition-metal ion on the B site can adopt different oxidation states by accepting and releasing electrons during the oxygen reactions at the SOEC/SOFC surfaces. For LaFeO\(_3\), a typical representative of this material class, we present results regarding the phase stability and point defect formation energies derived by density functional theory GGA+U calculations. The influence of point defects on the electronic charge-carrier concentrations as a function of the oxygen partial pressure is studied and compared for the perovskite materials LaFeO\(_3\), LaMnO\(_3\) and CaMnO\(_3\). In addition to the scientific results, the performance of the DFT calculations applied for these studies on the ForHLR I computer cluster is reported.