Dynamics behavior of lithium in graphite lattice: MD calculation approach

In order to investigate the diffusion process of Li atom in graphite, molec ular dynamics simulation was achieved on the basis of molecular mechanics 2 (MM2) method using four layers cluster model one of which is composed of C 150H30 With terminating hydrogen atoms. According to the simulations at 500 K, Li atom stabilizes initially around the center of mass, gets out of the graphite layers after 3.0 ps through di ffusion, which is different from the movement of Li+ ion captured by the da ngling bonds of the edge carbon atoms. The diffusion process of Li atom is found to be composed of following four steps in series: (1) vibration aroun d the stabilization point; (2) bulk diffusion; (3) vibration under influenc e of the dangling bonds of edge carbon atoms; and (4) escape from the graph ite layers. The diffusivity for step (3) is smaller than that for step (2). (C) 2000 Elsevier Science Ltd. All rights reserved.