Ionic Conductivity in the Solid Glyme Complexes\n[CH₃O(CH₂CH₂O)<i>_n</i>CH₃]:LiAsF₆ (<i>n </i>= 3,4)

Abstract

We have shown that two small molecule solid electrolytes, [CH₃O(CH₂CH₂O)₃CH₃]:LiAsF₆ and [CH₃O(CH₂CH₂O)₄CH₃]:LiAsF₆, differing by only one ethylene oxide unit exhibit markedly different transport numbers, <i>t</i>₊= 0.8 and 0.1, respectively. Such differences are related, on the one hand, to the presence of tunnels for Li⁺ migration in the crystal structure of the G3 complex, but not G4, and, on the other hand, to the weaker binding of AsF₆^- in the structure of G4 than in G3. Learning how to construct solid electrolytes that exhibit high Li⁺ transport numbers is important in minimizing polarization when such electrolytes are used in all-solid-state cells, such as lithium batteries.