Molecular Dynamics modelling a small-molecule crystalline electrolyte: LiBF4(CH3O(CH2CH2O)4CH3)0.5

Molecular Dynamics techniques have been used to investigate structure and ion conductivity in the glyme-based crystalline electrolyte LiBF4(CH3O(CH2CH2O)4CH3)0.5. The structure allows ionic transport in two distinct directions in the structure, y or z, resulting in anisotropic effects. MD simulations have also been carried out under external electric fields of 1-5 x 106 V/m, imposed in y- or z-directions, to induce ion transport on a short time-space scale at room temperature conditions. The MD simulations reproduce the experimentally determined structure satisfactorily, and also the unusually high cationic transport numbers (t+ > 0.6). The simulations suggest that the ion transport is dominated by the Li-ions inside the glyme complexes, while the Li-ions outside comprise stable complexes with the generally immobilized anions.