New polymerized ionic liquid (PIL) gel electrolyte membranes based on tetraalkylammonium cations for lithium ion batteries

New polymerized ionic liquids (PILs) based on tetraalkylammonium cations with N(CF3SO2)(2)(-) (TFSI-) anions are synthesized by homopolymerization and anion exchange reaction. Furthermore, a gel polymer electrolyte membrane based on the Pits as polymer host is prepared incorporating a tetraalkylammonium ionic liquid, LiTFSI salt and nano size SiO2. The gel polymer electrolyte membranes show exceptional thermal and electrochemical properties. They are found to be thermally stable up to 336 degrees C With the increase of the IL, T-g of the PIL-based electrolyte samples decreases obviously. When the IL concentration is 25 wt%, the ionic conductivity of the electrolytes reaches 4.9 x 10(-4) S cm(-1) at 60 degrees C. After 130 cycles, the Li/LiFePO4 battery with the gel polymer electrolyte membranes at 60 degrees C has discharge capacity of 122 mA h g(-1) at 0.1 current rates. (c) 2013 Elsevier B.V. All rights reserved