High-Voltage Resistant\nIonic Liquids for Lithium-Ion\nBatteries

Abstract

With the growing demand for high energy and high power\ndensity\nrechargeable lithium-ion batteries, increasing research is focused\non improving the output voltage of these batteries. Herein, a series\nof pyrrolidinium and piperidinium cations with various N-substituents\n(including cyanomethyl, benzyl, butyl, hexyl, and octyl groups) were\nsynthesized and investigated with respect to their electrochemical\nstability under high voltages. The influence of substitutions at the\nN-position of pyrrolidinium and piperidinium cations on their high-voltage\nresistance was studied by both theoretical and experimental approaches.\nThe voltage resistance was enhanced as the electron-donating ability\nof the substitutes increased. Furthermore, 1-hexyl-1-methylpyrrolidinium\nbis­(trifluoromethylsulfonyl) imide ([C₆Py]­[TFSI]) exhibited\nthe highest decomposition voltage at approximately 5.12 V and showed\npromising potential in a lithium-ion battery.