Electrodeposition of Lithium from Lithium-Containing Solvate Ionic Liquids

Lithium-containing solvate ionic
liquids [Li­(L)n]­[X], with ligands L =
1,2-dimethoxyethane (G1, monoglyme)
or 1-methoxy-2-(2-methoxyethyl)­ether (G2, diglyme) (with n = 1, 2 or 3) and with anions X = bis­(trifluoromethylsulfonyl)­imide
(Tf2N–), bromide (Br–) or iodide (I–), were synthesized and used as
electrolytes for the electrodeposition of lithium metal. Very high
lithium-ion concentrations could be obtained, since the lithium ion
is part of the cationic structure of the solvate ionic liquids. Without
stirring, current densities up to −26 A dm–2 at a potential of −0.5 V vs Li/Li+ were registered
during cyclic voltammetry. The formation of a solid–electrolyte
interface during electrodeposition of lithium from [Li­(G1)2]­[Tf2N] was studied by electrochemical quartz microbalance
and Auger electron spectroscopy. SEM pictures revealed uniform and
nondendritic lithium deposits.