Ionic liquid electrolytes based on multi-methoxyethyl substituted ammoniums and perfluorinated sulfonimides: Preparation, characterization, and properties

New functionalized ionic liquids (ILs), comprised of multi-methoxyethyl substituted quaternary ammonium canons (i.e. [N(CH2CH2OCH3)(4-n)(R)(n)](+) : n=1, R=CH3OCH2CH2; n=1, R=CH3, CH2CH3: n=2, R=CH3CH2), and two representative perfluorinated sulfonimide anions (i.e. bis(fluorosulfonyl)imide (FSI-) and bis(trifluoromethanesulfonyl)imide (TFSI-)), were prepared. Their fundamental properties, including phase transition, thermal stability, viscosity, density, specific conductivity and electrochemical window, were extensively characterized. These multi-ether functionalized ionic liquids exhibit good capability of dissolving lithium salts. Their binary electrolytes containing high concentration of the corresponding lithium salt ([Li+] >1.6 mol kg(-1)) show Li+ ion transference number (t(Li+)) as high as 0.6-0.7. Their electrochemical stability allows Li deposition/stripping realized at room temperature. The desired properties of these multi-ether functionalized ionic liquids make them potential electrolytes for Li (or Li-ion) batteries. (C) 2010 Elsevier Ltd. All rights reserved.