Ricerc@Sapienza

Two ionic liquids (ILs), which are functionalized with bis(oxalato)borate (BOB) and difluoro(oxalato)borate (DFOB) as the anion, have been synthesized and applied as additives for the battery grade electrolyte 1 M LiPF6 in an equivolume mixture of EC-DEC-DMC (LP71). When 0.3 M IL was added to LP71,peaks attributed to the formation of solid electrolyte interface (SEI) were observed during cyclic voltammetry for both cathodic and anodic sides. The presence of peaks during anodic scans suggests thatthe ILs possess the ability to form SEI on cathode surfaces.

We demonstrate that the addition of 1-butyl-1-methylpyrrolidinium hexafluorophosphate ([Py14]PF6)to1.0 M LiPF6in ethylene carbonate-dimethyl carbonate (LP30) widens the temperature range, in which theelectrolyte mixtures are ion conductive and safe. Specifically, at the concentrations of [Py14]PF6above50 wt%, the electrolyte mixtures exhibit aflash point higher than room temperature and fulfill the re-quirements of liquids having controlledflammability.