FT-IR studies on interactions of AlCl 3 with PEO–NaSCN polymer electrolytes

Abstract

Solid polymer electrolytes are potentially useful electrolytes to be applied in high-energy batteries. In the present work, a novel polymer electrolyte, polyethylene oxide (PEO)–NaSCN–AlCl 3, was prepared and investigated by FT-IR spectroscopic techniques. Based on the FT-IR data, the bands in the CN stretching envelope have been assigned and the effect of AlCl 3 on ion–ion and ion–polymer interactions in the polymer electrolyte has been examined. It is shown that the Lewis acid–base interaction of AlCl 3 with SCN 1− leads to the formation of the complex anions AlCl 3SCN − and Al 2Cl 6SCN −, depending on the content of AlCl 3 and/or NaSCN in PEO; the preferential interactions of AlCl 3 with crystal complex P(EO) 3NaSCN occur in PEO–NaSCN–AlCl 3 electrolytes; the AlCl 3–NaSCN complex anions can play a plasticization role in PEO–NaSCN–AlCl 3 electrolyte, and are expected to be a important factor to improve the conductivity and to enhance the cation transference number. In addition, the interactions between AlCl 3 and ether oxygen of PEO were analyzed, and their effect on ionic association was also discussed.