New electrolytes using Li2O or Li2O2 oxides and tris(pentafluorophenyl) borane as boron based anion receptor for lithium batteries

A new system of electrolytes has been developed and studied for lithium-ion batteries. This new system is based on the interactions between Li2O or Li2O2 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 Li2O or Li2O2 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 Li2O or Li2O2 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 X 10(-3) S/cm. These new electrolytes are compatible with LiMn2O4 cathode for lithium-ion batteries. (C) 2008 Elsevier B.V. All rights reserved.