By using first-principles methods, the activation barriers to Li-ion motion were calculated and an estimate was made of the Li diffusion constants in the absence of electrical conductivity constraints. It was found that  the Li diffused through 1-dimensional channels; with high-energy barriers between the channels. With no electrical conductivity limitations, the intrinsic Li diffusivity was high.

Li Conductivity in LixMPO4 (M = Mn, Fe, Co, Ni) Olivine Materials. D.Morgan, A.Van der Ven, G.Ceder: Electrochemical and Solid-State Letters, 2004, 7[2], A30-2