Lassègues Jean-Claude, Grondin Joseph, Aupetit Christian, Johansson Patrik
ISM, UMR 5255, CNRS, Université Bordeaux I, 351 Cours de la Libération, 33405 Talence Cedex, France.
J Phys Chem A. 2009 Jan 8;113(1):305-14. doi: 10.1021/jp806124w.
The solvation of the lithium ion in LiTFSI-doped ionic liquids based on alkyl-substituted imidazolium cations and bis(trifluoromethanesulfonyl)imide anions (TFSI-) was investigated by infrared and Raman spectroscopies. The spectral changes occurring for some TFSI- vibrations sensitive to the lithium coordination were analyzed with the help of DFT calculations. In addition, the vibrations of the lithium ion in its solvating cage were found to produce a broad IR absorption band centered at 374 cm(-1). For low to moderate LiTFSI mole fractions, 0.08 < x < 0.2, the [Li(TFSI)2]- solvating cage was found to involve bidentate coordinations of Li+ with two oxygen atoms of one anion in the trans (C2) conformation and two oxygen atoms of the other anion in the cis (C1) conformation. At higher LiTFSI concentration, up to x = 0.5, the lithium ion-TFSI coordination number progressively becomes less than 2, indicating the possible formation of aggregates.
通过红外光谱和拉曼光谱研究了基于烷基取代咪唑阳离子和双(三氟甲磺酰)亚胺阴离子(TFSI-)的LiTFSI掺杂离子液体中锂离子的溶剂化作用。借助密度泛函理论(DFT)计算分析了一些对锂配位敏感的TFSI-振动所发生的光谱变化。此外,发现锂离子在其溶剂化笼中的振动产生了一个以374 cm(-1)为中心的宽红外吸收带。对于低至中等的LiTFSI摩尔分数,0.08 < x < 0.2,发现[Li(TFSI)2]-溶剂化笼涉及Li+与一个处于反式(C2)构象的阴离子的两个氧原子以及另一个处于顺式(C1)构象的阴离子的两个氧原子的双齿配位。在较高的LiTFSI浓度下,直至x = 0.5,锂离子与TFSI的配位数逐渐小于2,表明可能形成聚集体。