Purification process for lithium battery electrolytes

Abstract

A process for purification of lithium battery electrolyte solutions is provided whereby the concentrations of trace amounts of impurities such as water in the electrolyte solutions can be reduced. Such electrolyte solutions generally include at least one lithium salt solute contained in at least one organic solvent. Lithium and a second metal with which lithium is capable of intercalating are first placed in electrical contact with one another and then placed in the electrolyte solution. Preferably, aluminum is used as the second metal and the two metals are provided as separate layers that are pressed together in a rolling mill to form a bimetallic sheet. The solution containing the bimetallic sheet is agitated to encourage the reactions which reduce the levels of impurities such as water in the electrolyte solution. The resulting purified solution is then filtered to remove any remaining metal or reaction products. The resulting purified electrolyte solution can be used to make lithium batteries having improved cycling characteristics over batteries using unpurified electrolyte solution.