Bis(oxalato)borate and difluoro(oxalato)borate-based ionic liquids as electrolyte additives to improve the capacity retention in high voltage lithium batteries
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.