Central Glass Company, Limited

Sunao Yamamoto

Hiromi Sasaki

Keiji Sato

Tadayuki Kawashima

Hiroshi Ueda

Hisakazu Itou

Hirokazu Kusunoki

Yasushi Muneno

Mituo Takahata

Shouichi Tsujioka

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 pentafluiride, 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 purify the electrolytic solution. The acid impurity concentration of the electrolytic solution is substantially reduced by this method.

Electrolytic solution for lithium cell and method for producing same

A process of continuously crystalizing sodium percarbonate by the reaction of sodium carbonate with hydrogen peroxide using first and second reaction vessels includes the steps of: (a) continuously feeding a first feed solution containing sodium carbonate and a second feed solution containing hydrogen peroxide into the first reaction vessel, thereby to form therein a first slurry containing seed crystals of sodium percarbonate; (b) continuously discharging the first slurry from the first reaction vessel into the second reaction vessel while step (a) is performed; (c) continuously feeding at least one of hydrogen peroxide and sodium carbonate into the second reaction vessel while steps (a) and (b) are performed thereby to form therein a second slurry containing final sodium percarbonate crystals grown from the seed crystals; (d) continuously discharging the second slurry from the second reaction vessel while steps (a), (b) and (c) are performed; (e) continuously separating the second slurry into the final sodium percarbonate crystals and a mother liquor while steps (a), (b), (c) and (d) are performed; and (f) granulating the final sodium percarbonate crystals thereby to form a final product of sodium percarbonate. According to the process, it is possible to maintain particle size of the final sodium percarbonate crystals not larger than 100 .mu.m, thereby to efficiently produce sodium percarbonate granules having a satisfactory strength.

Continuous process for preparing sodium percarbonate

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Ube, Japan

Sunao Yamamoto