Modeling Polaron-Coupled Li Cation Diffusion in V₂O₅ Cathode Material

The transport of intercalated Li cations in oxide materials comprises two aspects, ion diffusion and migration of an associated small polaron. We examined computationally these two aspects of Li transport in vanadium pentoxide (V₂O₅) cathode material in a consistent fashion, using a DFT+U approach. Exploring various migration scenarios at low Li concentrations, we determined barriers of ∼0.3 eV, mostly due to polaron migration. In consequence, intercalating Li atoms, at low concentrations, migrate in the interlayer region of V₂O₅ as quasi-particles where Li cations remain closely associated with their valence electrons, where a small polaron structure forms around the reduced vanadium center.