Li intercalation mechanisms in CaTi₅O₁₁, a bronze-B derived compound

A first-principles study was performed to elucidate the electrochemical properties of CaTi₅O₁₁, a recently discovered compound that is a crystallographic variant of TiO₂(B) and that shows promise as an anode material for Li-ion batteries. The crystal structure of CaTi₅O₁₁ was further refined and two symmetrically distinct interstitial sites that can accommodate Li at positive voltage were identified. A statistical mechanics study relying on density functional theory (DFT) calculations predicted that interstitial Li in CaTi₅O₁₁ forms a solid solution with Li insertion resulting in a sloping voltage profile. Li diffusion within CaTi₅O₁₁ was found to be highly anisotropic with low barrier diffusion pathways forming one-dimensional channels parallel to the c axis.