Thermal diffusion of correlated Li-ions in graphite: A hybrid quantum–classical simulation study

摘要: Abstract Diffusion of Li-ions in graphite is an essential elementary process the current lithium-ion battery. The C-layers deform with Li due to relatively large size Li-ion, act confine Li-ions, and thereby creates correlation between them. We address theoretically thermal diffusivity such correlated by hybrid quantum–classical simulation method. In this method, quantum-region composed surrounding C atoms treated density-functional theory, while it embedded dynamically total system described empirical inter-atomic interaction potential. take into account long-ranged deformation field simulating Li-ion dynamics. Two kinds settings are considered for runs at temperature 443 K : (i) seven inserted same inter-layer space study their intra-plane correlation, (ii) additional neighboring (i.e., fourteen totally, 7 upper lower spaces) inter-plane correlation. As (i), concentrated initially inter-ion distances 2.5 – 4.2 A , scatter mutual Coulomb repulsion. After about 1 ps thermalize well deformed creating a cage radius 13.5 Li-ions. Diffusivity inside much higher than that itself. long-time diffusion constant order as isolated graphite. (ii), spaces C-layer, firstly form domains, then domains repel each other horizontally. result accord experimental finding Li-rich Li-poor planes stack alternating sequence