Thermal Aging of Anions in Ionic Liquids containing Lithium Salts byIC/ESI-MS

Pyschik M, Kraft V, Passerini S, Winter M, Nowak S

Zusammenfassung

The stability of 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR13TFSI) and1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide (PYR13FSI) ionic liquids at elevated temper-atures (60◦C) is investigated by ion chromatography. Additionally, the influence of the electrolyte salts,lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithiumperchlorate (LiClO4), on the decomposition of both the ionic liquids was analysed over a long term sta-bility study. It has been found out that TFSI has a much higher thermal stability than FSI. The additionof LiTFSI did not show any effect on the aging of both ionic liquid anions. However, PYR13FSI degradedwhen mixed with the electrolyte salts LiPF6and LiClO4, while PYR13TFSI did not. Finally, LiPF6forms thesame hydrolysis products in the investigated ionic liquids as in the commonly used electrolytes basedon organic solvents in lithium-ion batteries.