Using the adiabatic trajectory method, the migration energy barriers for the migration of Li ions and Cr ions along the 1-dimensional diffusion pathway in pure and Cr doped LiFePO4 were obtained from first-principles calculations. The results showed that, while Li ions could easily diffuse along the diffusion pathway, Cr ions did not easily diffuse away from their initial positions. This implied that the heavy Cr ions would block the 1-dimensional diffusion pathway of the material. Monte Carlo simulations were performed in order to evaluate the influence of the blocking behavior. The results showed that the evaluated capacity was highly sensitive to the amount of dopant, the size of the super-cell being used for simulation (particle size of the powder cathode material) and the charge–discharge current density.

The Effect of Cr Doping on Li Ion Diffusion in LiFePO4 from First Principles Investigations and Monte Carlo Simulations. C.Y.Ouyang, S.Q.Shi, Z.X.Wang, H.Li, X.J.Huang, L.Q.Chen: Journal of Physics - Condensed Matter, 2004, 16[13], 2265-72