A new ionic liquid formed by coupling 4,5-dicyano-2-(trifluoromethyl) imidazole (TDI-) anion with N-butyl -N-methyl-pyrrolidinium (Pyr(14)(+)) cation is successfully synthesized and characterized by Raman spectroscopy, thermal and rheological analyses, as well as electrochemical techniques. The Pyr(14)TDI-LiTDI mixture, melting at 49 degrees C, shows remarkable stability within the 50-250 degrees C range, as well as suitable ionic conductivity, lithium ion transport, and electrochemical stability window. Thus, it is proposed for application at 60 degrees C in a lithium cell with stable LiFePO4 cathode. At this temperature, the electrolyte has viscosity of 65.8 mPa s, ionic conductivity of the order of 5 mS cm(-1), and limiting current density of 10(-2)mA cm(-2). Lithium metal/LiFePO4 cells with such an electrolyte offer promising results in terms of stable LiFePO4/electrolyte interface, investigated by impedance spectroscopy, as well as delivered capacity above 160 mAh g(-1) with 81% of retention after 80 galvanostatic cycles. (C) 2017 Elsevier Ltd. All rights reserved.