Lithium and copper transport properties in phosphate glasses: A Molecular Dynamics study

Abstract

Recently glasses have been considered as potential candidates for solid-state batteries applications due to the peculiar properties that they show if compared to crystalline ones. In this work, the dynamic properties of copper (Cu1+) and lithium (Li1+) ions in phosphate glasses, in which Cu2O was progressively substituted to Li2O, were investigated and correlated with the glass structure analysis by using Molecular Dynamic (MD) simulations.The diffusion of Li+ ions and how it is influenced by Cu2+ and Cu1+ ions were highlighted. In this vitreous system, the Cu1+ ions diffuse interacting with the lithium diffusion.This results in the general increase of the activation energy of Li1+ as a function of the Cu2O content in these glasses. At the same time the substitution of Li2O by Cu2O leads to the decrease of the Ea of the Cu1+, mainly due to structural changes that promote the disruption of the Li1+ pathway and the creation of more stable Cu1+ sites. This explains the increased migration of this ion in higher copper content system.