Structure and Conductivity of Small-Molecule Electrolytes [CH₃O(CH₂CH₂O)_nCH₃]:LiAsF₆ (n = 8−12)

Abstract

The crystal structures of [CH3O(CH2CH2O)nCH3]:LiAsF6 (n = 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 (t+ < 0.3) in the reported complexes, while greater distances between neighboring anions explain lower conductivities, compared with complexes prepared with lower glymes (n = 3, 4).