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.