New electrolytes using Li 2O or Li 2O 2 oxides and tris(pentafluorophenyl) borane as boron based anion receptor for lithium batteries

Abstract

A new system of electrolytes has been developed and studied for lithium-ion batteries. This new system is based on the interactions between Li 2O or Li 2O 2 and tris(pentafluorophenyl) borane (TPFPB) in carbonate based organic solvents. This opens up a completely new approach in developing non-aqueous electrolytes. In general, the solubility of Li 2O or Li 2O 2 is very low in organic solvents and the ionic conductivities of these solutions are almost undetectable. By adding certain amount of tris(pentafluorophenyl) borane (TPFPB), one type of boron based anion receptors (BBARs), the solubility of Li 2O or Li 2O 2 in carbonate based solvents was significantly enhanced. In addition, the Li + transference numbers of these new electrolytes measured were as high as 0.7, which are more than 100% higher than the values for the conventional electrolytes for lithium-ion batteries. The room-temperature conductivities are around 1 × 10 −3 S/cm. These new electrolytes are compatible with LiMn 2O 4 cathode for lithium-ion batteries.