Quasi-Three-Dimensional Diffusion of Li ions in Li3FePO4CO3: First-Principles Calculations for Cathode Materials of Li-Ion Batteries

Crystal structure, electronic structure, and diffusion mechanism of Li ions in a new cathode material, Li3FePO4CO3, for Li-ion batteries were investigated based on first-principles calculations by using the GGA+U method. Eight possible elementary diffusion processes and three possible diffusion pathways of polaron-Li vacancy complex were revealed. The quasi-three-dimensional characteristic of the Li diffusion was explored. In the [010] and [001] directions, Li ions can diffuse with the barriers of 0.37 and 0.33 eV, respectively. Along the [100] direction, Li ions can hop through carbon layers with a barrier of 0.5 eV, but might be blocked by iron layers. (C) 2013 The Japan Society of Applied Physics