New hydrophobic ionic liquids based on (fluorosulfonyl)(polyfluorooxaalkanesulfonyl)imides with various oniums

Sixteen ionic liquids (ILs) based on two new asymmetric imide anions, (fluorosulfonyl) (polyfluorooxaalkanesulfonyl)imide {[(FSO2)(XCF2CF2OCF2CF2SO2)Nr](-) [5X3O-FOFSI](-), X= H and I), are synthesized and characterized by in combination with various oniums, including 1,3-dialkylimidazolium, quaternary alkyl (or ether-functionalized alkyl)ammonium, N-alkyl-N-methyl-pyrrolidinium and -piperidinium. Their physicochemical properties are investigated, in terms of phase transitions, thermal stability, density, viscosity, ionic conductivity, electrochemical stability, and the capability as electrolytes to allow Li deposition/stripping. The influences of the structural variations in both the cations and anions, particularly introduction of an ether group into the anion, on the above properties are systematically studied. All the ILs are liquids at room temperature and show low glass transition temperatures, suggesting the high flexibility of the ether-functionalized imide anion. It has been demonstrated that only having an ether group into the polyfluoroalkyl chain of the imide anion affect neither the cathodic nor anodic stability of the anion and their ILs. ThelLs based on the [5H30-FOFSI](-) anion have an enough electrochemical stability to allow Li deposition/striping, while those based on the [513O-FOFS](-)] - anion show relatively low cathodic stability due to the presence of a C I bond in the anion. (C) 2013 Elsevier Ltd. All rights reserved.

合成了基于两种新型不对称酰亚胺阴离子，即（氟磺酰基）（多氟氧杂烷烃磺酰基）酰亚胺{[(FSO₂)(XCF₂CF₂OCF₂CF₂SO₂)N⁻][5X₃O - FOFSI]⁻，X = H和I}的16种离子液体（ILs），并结合各种鎓离子（包括1,3 - 二烷基咪唑鎓、季烷基（或醚官能化烷基）铵、N - 烷基 - N - 甲基 - 吡咯烷鎓和 - 哌啶鎓）对其进行了表征。研究了它们的物理化学性质，包括相变、热稳定性、密度、粘度、离子电导率、电化学稳定性以及作为电解质允许锂沉积/剥离的能力。系统地研究了阳离子和阴离子结构变化（特别是在阴离子中引入醚基）对上述性质的影响。所有离子液体在室温下均为液体，且玻璃化转变温度较低，表明醚官能化酰亚胺阴离子具有较高的柔韧性。已经证明，仅在酰亚胺阴离子的多氟烷基链中引入醚基既不影响阴离子及其离子液体的阴极稳定性也不影响阳极稳定性。基于[5H₃O - FOFSI]⁻阴离子的离子液体具有足够的电化学稳定性以允许锂沉积/剥离，而基于[5I₃O - FOFS]⁻阴离子的离子液体由于阴离子中存在C - I键而显示出相对较低的阴极稳定性。© 2013 Elsevier Ltd.保留所有权利。