Infrared spectroscopic study of the interaction between lithium salt LiClO4 and the plasticizer ethylene carbonate in the polyacrylonitrile-based electrolyte

The infrared (IR) spectra of ethylene carbonate (EC) containing different contents of lithium perchlorate (LiClO4) have been measured and analyzed. It is found that, with the increase of the LiClO4 content in the solution, both the vibrational frequencies and the relative intensities of the bands related to the ring structure and to the C=O group of EC molecule are changed. The data have shown that there is a rather strong interaction between the Li+ ion and the EC molecule. The interactions between the Li+ ions and the EC molecules mainly occur on the C=O group of the molcules. In the meantime, the structure of the ClO4- anion is also affected by the EC molecules, forming solvent-shared ion pairs, Li+-EC-ClO4-.