Molecular dynamics studies of combined carbon/electrolyte/lithium-metal oxide interfaces

Abstract

Molecular dynamics simulations are performed on three-dimensional unit cells with periodic boundary conditions for a combined system representing anode-electrolyte-cathode materials. Evaluations of structural changes in bulk phases and at liquid-solid interfaces, as well as lithium-ion diffusion coefficients in each phase are performed. Calculated solid-phase diffusion coefficients of lithium ions in carbons are in the range 10 −14 to 10 −13 m 2 s −1. The presence of curved regions in the modeled amorphous carbon slows the diffusion of lithium ions and allows a higher lithium storage capacity than in graphite. In the lithium-metal oxide system, the lithium ionic diffusion coefficients are in the order of 10 −12 to 10 −11 m 2 s −1. A spatial variation is found in the diffusion of lithium ions within the modeled cathode phase.