International audienceIn this work, ionic liquids based on trihexyl(tetradecyl) phosphonium associated with bis(2,4,4-trimethylpentyl) phosphinate [TMP] and dicyanamide [DCA] counter anions were used as reactive additives within epoxy/amine networks. We have demonstrated that the addition of ionic liquids plays a key role on the kinetics of polymerization but also on the final properties of the epoxy networks. Structurations at the nanoscale combined with excellent thermal stability and good mechanical properties have been highlighted. By processing sub-stoichiometric epoxy-amine networks and thanks to the reactivity of phosphinate counter-anions towards glycidyl moieties, more than 70 percent of the ionic liquid was introduced which opens new perspectives in the development of high performance gel electrolytes for the safety improvement of electrochemical devices such as lithium ion batteries

In this work, new gelled electrolytes were prepared based on a mixture containing phosphonium ionic liquid (IL) composed of trihexyl(tetradecyl)phosphonium cation combined with bis(trifluoromethane)sulfonimide [TFSI] counter anions and lithium salt, confined in a host network made from an epoxy prepolymer and amine hardener. We have demonstrated that the addition of electrolyte plays a key role on the kinetics of polymerization but also on the final properties of epoxy networks, especially thermal, thermo-mechanical, transport, and electrochemical properties. Thus, polymer electrolytes with excellent thermal stability (>300 °C) combined with good thermo-mechanical properties have been prepared. In addition, an ionic conductivity of 0.13 Ms·cm−1 at 100 °C was reached. Its electrochemical stability was 3.95 V vs. Li0/Li+ and the assembled cell consisting in Li|LiFePO4 exhibited stable cycle properties even after 30 cycles. These results highlight a promising gelled electrolyte for future lithium ion batteries.