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

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.