Ab initio evaluation of oxygen diffusivity in LaFeO3: the role of lanthanum vacancies

Solid oxide fuel cells (SOFCs) are attractive for clean and efficient electricity generation, but high operating temperatures (T > 800 °C) limit their widespread usage. Oxygen ion conducting cathode materials (mixed ion-electron conductors, MIECs), such as La1−x Sr x Co1−y Fe y O3 (LSCF), enable lower T by reducing cathode polarization losses. Understanding how composition affects oxygen diffusion in LaFeO3 is vitally important for designing high-performance LSCF cathodes. To do this, we employ first-principles density functional theory plus U (DFT+U) calculations to show how lanthanum vacancies in LaFeO3 dramatically change the oxygen diffusion coefficient. Our ab initio results show that A-site substoichiometry is a viable route to increased oxygen diffusion and higher SOFC performance.