Multi-scale simulation of lithium diffusion in the presence of a 30° partial dislocation and stacking fault in Si

The multi-scale simulation method is employed to investigate how defects affect the performances of Li-ion batteries (LIBs). The stable positions, binding energies and dynamics properties of Li impurity in Si with a 30 degrees partial dislocation and stacking fault (SF) have been studied in comparison with the ideal crystal. It is found that the most table position is the tetrahedral (T-d) site and the diffusion barrier is 0.63 eV in bulk Si. In the 30 degrees partial dislocation core and SF region, the most stable positions are at the centers of the octagons (Oct-A and Oct-B) and pentahedron (site S), respectively. In addition, Li dopant may tend to congregate in these defects. The motion of Li along the dislocation core are carried out by the transport among the Oct-A (Oct-B) sites with the barrier of 1.93 eV (1.12 eV). In the SF region, the diffusion barrier of Li is 0.91 eV. These two types of defects may retard the fast migration of Li dopant that is finally trapped by them. Thus, the presence of the 30 degrees partial dislocation and SF may deactivate the Li impurity and lead to low rate capability of LIB. (C) 2014 AIP Publishing LLC.