A Computational Investigation of Channel Structures in Rutile-Related LiM₂SbO₆ (M = Sc, Fe) as Li-Ion Battery Cathode Materials

Lithium-ion batteries find extensive applications in numerous electronic devices and have gained significant attention in recent years. Furthermore, the evaluation of the intrinsic properties of cathode materials is crucial for their practical applications. Hence, utilizing first-principles calculations based on density functional theory and a hybrid functional approach, we conducted a comprehensive investigation into the structural, dynamical, mechanical, electronic, and electrochemical properties of rutile-related LiM₂SbO₆ (M = Sc, Fe) channel structures. We considered various crystal structures including the Pmn2₁ symmetry with Li-tetrahedrally coordinated and the Pnn2 symmetry with Li-octahedrally coordinated and different M arrangements. The Pmn2₁ crystal structures are more preferred over the Pnn2 crystal structures. Additionally, the Pnn2 configurations of LiSc₂SbO₆ were found to be dynamically unstable. LiSc₂SbO₆ has a higher calculated voltage than LiFe₂SbO₆, with cell voltages ranging from 3.03 (4.70) to 4.92 (5.61) V by using the PBE (HSE06) functional. Furthermore, lithiated LiFe₂SbO₆ configurations exhibit enhanced electronic conductivity compared to LiSc₂SbO₆ in Pmn2₁ symmetry. For LiSc₂SbO₆ in the Pmn2₁ symmetry, the Li diffusion barrier is 0.98 eV, while for LiFe₂SbO₆ configurations, it ranges from 0.45 to 1.19 eV. Configurations with higher barriers are expected to have poor Li-ion conductivity and may require synthesis as nanoparticles to enhance Li transfer. This study may provide insights for developing cathode materials in lithium-ion battery applications.