New hydrophobic ionic liquids based on perfluoroalkyltrifluoroborate anions

New hydrophobic ionic liquids, 1-ethyl-3-methylimidazolium (EMI+) perfluoroalkyltrifluoroborate ([RfBF3]−) (Rf=C2F5,n-C3F7, and n-C4F9) were prepared in high yield and purity by facile neutralization of 1-ethyl-3-methylimidazolium (EMI+) methylcarbonate (MeOCO2−) with aqueous Hsolv.[RfBF3]solv. solutions. All the salts prepared were characterized by 19F, 1H, 11B NMR, MS and elemental analysis, and thermal and electrochemical properties of these salts have been measured. [EMI][C2F5BF3] melted at lower temperature (−1 °C) than [EMI][BF4] (13 °C), resulting in higher conductivity at low temperature. Its application to double-layer capacitors (DLCs) was examined.