Effects of scandium doping on the oxygen diffusion barrier in monoclinic ZrO2 solid electrolyte: A density functional theory approach

• Enhanced Ion Diffusion: Scandium doping reduces activation energy for oxygen ion diffusion. • Scandium Positioning: Optimal placement affects energy reduction. • Vacancy Defect Insights: Scandium promotes vacancy formation, enhancing diffusion. • Electronic Property: Scandium alters zirconia’s electronic characteristics. Solid oxide fuel cells (SOFCs) represent a promising technology for generating efficient and clean energy. However, their high operating temperatures present significant challenges. To address this issue, researchers have explored various electrolytes, particularly zirconia-based materials, as potential electrolyte. This study investigates the effects of doping zirconia electrolytes with scandium (Sc) using density functional theory (DFT) calculations. The primary objective is to gain insights into how Sc doping affects key properties such as oxygen ion diffusion barrier, vacancy formation, and electronic characteristics, ultimately aiming to enhance electrolyte’s performance. The DFT analysis demonstrates a notable reduction in the activation energy required for oxygen ion diffusion when Sc is incorporated into the zirconia, regardless of its specific location within the structure. However, the placement of Sc significantly influences this energy reduction, with the lowest activation energies observed when Sc is positioned away from the main diffusion path. Additionally, the formation energy of vacancies is critical in guiding ion diffusion. The results indicate that the formation of vacancies is more likely to occur adjacent to the doped scandium ion. The analysis further reveals how Sc doping affects the electronic properties of zirconia, particularly in determining the band gap. The findings indicated that the positioning of scandium in relation to the vacancy significantly influences the band gap. This study ultimately aims to enhance the understanding of how the scandium doping influences the behavior of oxygen ion diffusion.