Intercalation processes and corresponding diffusion paths of Li ions into spinel-type structured Li1+xTi2O4 (0 ≤ x ≤ 0.375) were systematically studied by means of periodic density functional theory calculations for different compositions and arrangements. An analysis of the site preference for intercalation processes was carried out, while energy barriers for the diffusion paths were computed in detail. The results indicated that Li insertion was thermodynamically favorable at octahedral sites 16c in the studied composition range, and Li migration from tetrahedral sites 8a to octahedral sites 16c stabilized the structure and became favorable at x ≥ 0.25. Diffusion paths from less stable arrangements involving Li migrations between tetrahedral and octahedral sites exhibited the lowest energy barrier since the corresponding trajectories and energy profiles took place across a triangle made by 3 neighboring O anions without structural modification. Theoretical and experimental diffusion coefficients were in fair agreement.

Intercalation Processes and Diffusion Paths of Lithium Ions in Spinel-Type Structured Li1+xTi2O4 - Density Functional Theory Study. M.Anicete-Santos, L.Gracia, A.Beltrán, J.Andrés, J.A.Varela, E.Longo: Physical Review B, 2008, 77[8], 085112 (11pp)