The effect of Cr doping on Li ion diffusion in LiFePO4 from first principles investigations and Monte Carlo simulations

Using the adiabatic trajectory method, the migration energy barriers for the migration of Li ions and Cr ions along the one-dimensional diffusion pathway in pure and Cr doped LiFePO4 are obtained from first principles calculations. The results show that while Li ions can diffuse along the diffusion pathway easily, Cr ions do not easily diffuse away from their initial positions. This means that the heavy Cr ions will block the one-dimensional diffusion pathway of the material. Monte Carlo simulations are performed to evaluate the influences of the blocking behaviours on the electrochemical performance of LiFePO4 cathode material for Li ion secondary batteries. The results show that the evaluated capacity is highly sensitive to the amount of the dopant, the size of the super-cell being used for simulation (particle size of the powder cathode material) and the Monte Carlo steps for statistics (charge–discharge current density).

[1]  H. Monkhorst,et al.  SPECIAL POINTS FOR BRILLOUIN-ZONE INTEGRATIONS , 1976 .

[2]  D. Vanderbilt,et al.  Soft self-consistent pseudopotentials in a generalized eigenvalue formalism. , 1990, Physical review. B, Condensed matter.

[3]  Christopher Roland,et al.  Ab initio investigations of lithium diffusion in carbon nanotube systems. , 2002, Physical review letters.

[4]  Hafner,et al.  Ab initio molecular-dynamics simulation of the liquid-metal-amorphous-semiconductor transition in germanium. , 1994, Physical review. B, Condensed matter.

[5]  Kresse,et al.  Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. , 1996, Physical review. B, Condensed matter.

[6]  John O. Thomas,et al.  Thermal stability of LiFePO4-based cathodes , 1999 .

[7]  G. Kresse,et al.  Ab initio molecular dynamics for liquid metals. , 1993 .

[8]  Siqi Shi,et al.  Enhancement of electronic conductivity of LiFePO4 by cr doping and its identification by first-principles calculations , 2003 .

[9]  K. S. Nanjundaswamy,et al.  Phospho‐olivines as Positive‐Electrode Materials for Rechargeable Lithium Batteries , 1997 .

[10]  Zhang,et al.  Ab initio studies of the diffusion barriers at single-height Si(100) steps. , 1995, Physical review letters.

[11]  T. Arias,et al.  Iterative minimization techniques for ab initio total energy calculations: molecular dynamics and co , 1992 .

[12]  Kurt Binder,et al.  Applications of Monte Carlo methods to statistical physics , 1997 .

[13]  G. Kresse,et al.  Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set , 1996 .

[14]  Blöchl,et al.  Improved tetrahedron method for Brillouin-zone integrations. , 1994, Physical review. B, Condensed matter.

[15]  Yet-Ming Chiang,et al.  Electronically conductive phospho-olivines as lithium storage electrodes , 2002, Nature materials.

[16]  Wang,et al.  Theory of Zn-enhanced disordering in GaAs/AlAs superlattices. , 1992, Physical review letters.

[17]  Yoji Sakurai,et al.  Reaction behavior of LiFePO4 as a cathode material for rechargeable lithium batteries , 2002 .