Molecular dynamics computer simulations are used to study lithium-ion diffusion in SiO2 doped amorphous vanadia intergranular films (IGFs) in nanocrystalline V2O5 cathodes. Previous simulations showed rapid transport paths for Li intercalation from a solid electrolyte into vanadia cathodes via amorphous IGFs separating the vanadia crystals as a function of IGF thickness. However, ordering at the IGF/crystalline vanadia interface affected Li intercalation and required a minimum IGF thickness for rapid transport. The current simulations evaluate the role of Si (as SiO2) as an impurity in the IGF on interface ordering and Li transport. The simulations are done on the three different concentrations of Si ions in the IGF: 5, 10 and 15% in molar percentage. Results show that the presence of Si in the IGF retards the lithium-ion diffusion in IGF and hence, intercalation. (c) 2005 The Electrochemical Society.