Structure and Conductivity of Small-Molecule Electrolytes [CH₃O(CH₂CH₂O)_<i>n</i>CH₃]:LiAsF₆ (<i>n</i> = 8−12)

Abstract

The crystal structures of [CH₃O(CH₂CH₂O)<i>_n</i>CH₃]:LiAsF₆ (<i>n</i> = 8−12) are reported. Each glyme forms a structurally unique complex with LiAsF₆. In all glymes Li⁺ ions are six coordinated when only ether oxygens are involved in coordination. The coordination number is reduced to five when a fluorine from the AsF₆⁻ anion is involved in coordination. The absence of convenient pathways for Li⁺ ions in the structures account for low lithium transport numbers (<i>t</i>₊ < 0.3) in the reported complexes, while greater distances between neighboring anions explain lower conductivities, compared with complexes prepared with lower glymes (<i>n</i> = 3, 4).