Ligand Exchange Conduction of Lithium Ion in a Pentaglyme-Lithium Bis(trifluoromethylsulfonyl)amide Super-Concentrated Electrolyte

Abstract

Ligand exchange conduction or hopping conduction which means ions move faster than their ligands or solvents, is one of the striking phenomena in electrochemistry. Here, we report a glyme-based electrolyte where ligand exchange conduction takes place. The electrolyte is a concentrated pentaglyme (G5) solution of lithium bis(trifluoromethylsulfonyl)amide (LiTf2N; Tf = SO2CF3) with molar ratio of [G5]/[LiTf2N] = 1/2. Since a diglyme (G2) solution [G2]/[LiTf2N] = 1/1 which has the same molar ratio of ether oxygen to Li+ ([O]/[Li+] = 3) does not show ligand exchange conduction, the glyme chain length may need to be long enough to bridge Li+ ions, by which the momentum exchange of Li+ ions via solvent molecules is allowed.