Article: Structure−Properties Relationships of Lithium Electrolytes Based on Ionic Liquid

My Loan Phung Le, Fannie Alloinli, Pierre Strobel, Jean-Claude Leprtre, Carlos Prez del Valle§ and Patrick Judeinstein [/li]LEPMI-Grenoble-INP/UJF/CNRS, BP75, 38402 Saint Martin d’Hres, France, Institut Nel, 38054, Grenoble, France, DCM-UJF-CNRS, BP53, 38041 Grenoble, France, and ICMMO, CNRS 8182, Btiment 410, Universit Paris-Sud, 91405 Orsay Cedex, France

J. Phys. Chem. B, 2010, 114 (2), pp 894–903 DOI: 10.1021/jp9098842 Publication Date (Web): December 29, 2009 Copyright © 2009 American Chemical Society

Low-melting ionic liquid, IL, based on small aliphatic quaternary ammonium cations ([R1R2R3NR]+, where R1, R2, R3 = CH3 or C2H5, R = C3H7, C4H9, C6H13, C8H17, CF3C3H6) and imide anion were prepared and characterized. The physicochemical and electrochemical properties of these ILs, including melting point, glass transition, and degradation temperatures; viscosity; density; ionic conductivity; diffusion coefficient; and electrochemical stability, were determined. Heteronuclear Overhauser NMR spectroscopy experiments were also performed to point out the presence of pair correlation between the different moieties. The LiTFSI addition effect on the IL properties was studied with the same methodology. Some nanoscale organization with segregation of polar and apolar domains was observed. ILs with small alkyl chain length or fluorinated ammonium exhibit very high electrochemical stability in oxidation.