Ionic Liquids Containing 1,1-Dicyano-1-acetylmethanide Anion as Potential Electrolytes

Various types of room temperature ionic liquids (RTILs) containing 1,1-dicyano-1-acetylmethanide anion ($[C(CN)_2(COCH_3)]^-$, $[DCNAcC]^-$) were prepared and their physical and electrochemical properties were studied. All of these ILs exhibited high thermal stabilities over $200^{\circ}C$ and relatively high ionic conductivities up to 29.4 $mS\;cm^{-1}$ at $80^{\circ}C$. Although the ionic conductivity of IL containing bis(trifluoromethanesulfonyl)-imide ($[Tf_2N]^-$) anion is higher than that of ILs bearing $[DCNAcC]^-$ anion, the specific capacitance of ILs bearing $[DCNAcC]^-$ anion are higher than that of IL containing $[Tf_2N]^-$ anion and showed high temperature dependence. Such favorable electrochemical properties of these ILs are likely to be attributed to the efficient dissociation of cation and anion at higher temperature and enhanced electrosorption of $[DCNAcC]^-$ anion at the electrode.