Vibrational Spectra and Ion-Pair Properties of Lithium Hexafluorophosphate in Ethylene Carbonate Based Mixed-Solvent Systems for Lithioum Batteries

摘要

Thc vihralionaJ spcctra ofLiPF6 solutions formed in aprotic mixed solvcn(, ohlaincd hy mixing cthylene carhon;lte with dimcthyJ carh<)natc and diethyl carhonale arc discussed. The Raman and infrared ~pcl'tra of lithium hcxafluoro- ph()~phatc (LiPF6) and the quantum chenlic;.11 comput.atiun~ of the vihrati(,)nal wavenumhers and intensities arc rCI)()rtcd. Due to the nat.ure of thc ~ollltions. attcnuatcd total internal rcl1cctanl:c ~pcctroscopy wa, u~cd to obtain thc illfrarcd spcl:tra. The infrarcd active vibrational fundamcnlal~ of Pf.6 providcd cvidcncc f()r the anion-,oJvent intcraction a~wcll a~ ion-pair formation. Similarly. the infrarcd active modc, of lhc so!VCnt,holvcd ~ignificant I:hangt?s due to the cati(,ll-solvt?nt intt?raction. Thc computatilms of the mo,t enl'r~etica!ly favorahle ~eomctr)' in thc fI)ri1lation of the Li+ Pf.6 ioh pair arc also prcsl'ntt?d. C'onductivity ntca~urcmcnts carried out 1()r the I M solulion~ scanning a widc tempcraturc intcrval ( -30 to 1- 60 °C) confirm the viahilitv of these electrolytes for practicala pplications.