Electrolytic Solution for Lithium Cell and Method for Producing Same

摘要

The present invention relates to a method for producing an electrolytic solution containing a solute of lithium hexafluorophosphate. This method includes a step of (a) reacting lithium fluoride with phosphorus pentafluoride, in a nonaqueous organic solvent that is used for producing a lithium cell's electrolytic solution, thereby to form the lithium hexafluorophosphate dissolved in the solvent. According to this method, both yield and purity of the reaction product are sufficiently high, and the reaction can easily be managed. According to need, after the step (a), the nonaqueous organic solvent may be replaced with another nonaqueous organic solvent. The present invention further relates to a method for purifying an electrolytic solution used for a lithium cell. This electrolytic solution contains an acid impurity having at least one hydrogen atom in the molecule. This method includes steps of (a) adding at least one hydrogen-free halide selected from chlorides, bromides and iodides, to the electrolytic solution, such that the acid impurity is reacted with the at least one hydrogen-free halide, thereby to form at least one hydrogen halide selected from hydrogen chloride, hydrogen bromide and hydrogen iodide; and (b) purging the at least one hydrogen halide from the electrolytic solution to purifythe electrolytic solution. The acid impurity concentration of the electrolytic solution is substantially reduced by this method.