Preparation and transport properties of novel lithium ionic liquids
Preparation and transport properties of novel lithium ionic liquids
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DOI：
10.1016/j.electacta.2004.01.096
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发表时间：
2004-11-30
影响因子：
6.6
通讯作者：
Watanabe, M
中科院分区：
文献类型：
--
作者：
Shobukawa, H;Tokuda, H;Watanabe, M
以LiBH_4为原料，通过连续取代反应合成了具有两个吸电子基团（1，1，1，3，3，3-六氟苯氧基或五氟苯氧基）和两个甲氧基低聚（环氧乙烷）基团（重复单元数：n = 3，4，7.2）的新型硼酸锂盐。所得锂盐在室温下为透明无色液体。测定了锂离子液体的密度、热性能、粘度和离子电导率。脉冲梯度自旋回波NMR（PGSE-NMR）方法被用来独立地确定锂阳离子（Li-7 NMR）和阴离子（F-19 NMR）的自扩散系数在体。在30 ℃时，新型锂盐的离子电导率为10（-5）~ 10（-4）S cm（-1），比典型的离子液体低两个数量级。然而，锂离子液体的自解离度;由复阻抗法确定的摩尔电导率与从自扩散系数和能斯特-爱因斯坦方程计算的摩尔电导率的比率，范围为0.1至0.4，这与非质子极性溶剂中的高度可解离盐和典型离子液体的值相当。锂离子液体电导率低的主要原因是锂离子液体的高粘度。需要说明的是，锂离子液体具有自解离能力，在无有机溶剂存在下，可传导离子。(C)2004年爱思唯尔有限公司保留所有战斗。
Novel lithium salts of borates having two electron-withdrawing groups(either 1,1,1,3,3,3-hexafluoro-2- propoxy or pentafluorophenoxy group) and two methoxy-oligo(ethylene oxide) groups (number of repeating unit: n = 3, 4, 7.2) were prepared by successive substitution-reactions from LiBH4. The obtained lithium salts were clear and colorless liquids at room temperature. The density, thermal property, viscosity, and ionic conductivity were measured for the lithium ionic liquids. The pulsed-gradient spin-echo NMR (PGSE-NMR) method was used to independently determine self-diffusion coefficients of the lithium cation (Li-7 NMR) and the anion (F-19 NMR) in the bulk. The ionic conductivity of the new lithium salts was 10(-5) to 10(-4) S cm(-1) at 30degreesC, which was lower than that of typical ionic liquids by two orders of magnitude. However, the degree of self-dissociation of the lithium ionic liquids; the ratio of the molar conductivity determined by the complex impedance method to that calculated from the self-diffusion coefficients and the Nernst-Einstein equation, ranged from 0.1 to 0.4, which are comparable values to those of a highly dissociable salt in an aprotic polar solvent and of typical ionic liquids. The main reason for the meager conductivity was high viscosities of the lithium ionic liquids. It should be noted that the lithium ionic liquids have self-dissociation ability and conduct the ions in the absence of organic solvents. (C) 2004 Elsevier Ltd. All fights reserved.