Ionic Liquids as Electrolyte in Lithium Batteries: In Situ FTIRs Studies on the Use of Electrolyte Additives

The solid electrolyte interphase (SEI) formation on commercial graphite, KS6 TIMCAL, in two different ionic liquids, N-methyl-N-butyl pyrrolidinium bis(trifluoromethansulfonyl)imide (PYR14TFSI) and N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (PYR13FSI) has been investigated. The role of the Vinylene Carbonate (VC) addition to the ionic liquid-based electrolyte has also been studied. To monitor the change at the electrode/electrolyte (IL) interface during the SEI formation, we took advantage of the in situ Fourier transform infrared spectroscopy (FTIRS). The results of the investigation performed at room temperature are presented in this manuscript.