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Electrochemical and physicochemical properties of small phosphonium cation ionic liquid electrolytes with high lithium salt content
journal contributionposted on 14.04.2015, 00:00 authored by Gaetan Girard, Matthias HilderMatthias Hilder, Haijin Zhu, D Nucciarone, K Whitbread, S Zavorine, M Moser, Maria ForsythMaria Forsyth, D R MacFarlane, Patrick HowlettPatrick Howlett
Electrolytes of a room temperature ionic liquid (RTIL), trimethyl(isobutyl)phosphonium (P111i4) bis(fluorosulfonyl)imide (FSI) with a wide range of lithium bis(fluorosulfonyl)imide (LiFSI) salt concentrations (up to 3.8 mol kg(-1) of salt in the RTIL) were characterised using a combination of techniques including viscosity, conductivity, differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), nuclear magnetic resonance (NMR) and cyclic voltammetry (CV). We show that the FSI-based electrolyte containing a high salt concentration (e.g. 1 : 1 salt to IL molar ratio, equivalent to 3.2 mol kg(-1) of LiFSI) displays unusual transport behavior with respect to lithium ion mobility and promising electrochemical behavior, despite an increase in viscosity. These electrolytes could compete with the more traditionally studied nitrogen-based ionic liquids (ILs) in lithium battery applications.