Kanto Denka Kogyo Co., Ltd.

Takuro Abe

Osamu Omae

Hiroki Takizawa

Wataru Kashikura

Hiroyuki Uehara

Kazuhide Yoshiyama

Teppei Ota

Keisuke Kude

Mitsuhara Shimoda

Disclosed is a method for purifying a difluorophosphate, the method including mixing a difluorophosphate containing an impurity with at least one treatment agent selected from the group consisting of carbonates, hydroxides, and halides of alkali metals or alkali earth metals and amines to isolate the impurity. It is preferable that the method further include filtering off, by filtration, a salt or a complex that has been formed by allowing the impurity to be mixed with the treatment agent. Preferably, a carbonate, a hydroxide, or a halide of an alkali metal is used as the treatment agent, and more preferably a carbonate, a hydroxide, or a halide of lithium is used as the treatment agent.

Method for purifying difluorophosphate

The purpose of the present invention is to provide a method for easily producing a difluorophosphate using only low-cost starting materials without requiring cumbersome operations. According to the present invention, at least one salt selected from the group consisting of halides, carbonates, borates, phosphates, hydroxides and oxides of an alkali metal, an alkaline earth metal or an onium, at least one phosphorus compound selected from the group consisting of oxychlorides and chlorides of phosphorus, water and hydrogen fluoride are reacted. The above-mentioned purpose is achieved preferably using, as hydrogen fluoride, one substance selected from the group consisting of hydrogen fluoride anhydride, a mixed solution of hydrogen fluoride anhydride and an organic solvent and a mixed gas of hydrogen fluoride anhydride and an inert gas, as a salt used in the reaction, at least one substance selected from the group consisting of halides and carbonates of an alkali metal, and as a phosphorus compound, phosphoryl chloride.

Method for producing difluorophospate

Provided are a nonaqueous electrolyte for secondary batteries containing an electrolyte having high solubility in ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or a like solvent and capable of forming a good-quality film on the positive and the negative electrode interface and a nonaqueous secondary battery having the nonaqueous electrolyte. Specifically, an electrolyte for secondary batteries containing a lithium salt as a solute and a nonaqueous solvent is provided, the nonaqueous solvent containing a monofluorophosphoric ester salt having general formula 1 or 2, in which symbols are as defined in the description. 

Nonaqueous electrolyte containing monofluorophosphoric ester salt and nonaqueous secondary battery using same

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Gunma, Japan

Takuro Abe