JPS60251109A - Manufacture of lithium hexafluorophosphate - Google Patents

Abstract

PURPOSE:To obtain easily and efficiently lithium hexafluorophosphate (LiPF6) at a low cost by reacting a lithium halide with PCl5 in the presence of HF. CONSTITUTION:A lithium halide such as LiF is dissolved in anhydrous HF as a reactive solvent in a reactor made of a corrosion resistant material such as stainless steel by an amount 20-50 times the amount of the HF, and a slight excess of PCl5 is slowly added and reacted with the lithium halide at -80-19 deg.C under ordinary pressure. The internal pressure of the reactor is then reduced, and the reactor is heated to -20-100 deg.C to remove HF by vaporization. Colorless LiPF6 crystals of 1-3mm. size contg. partially white powder are obtd.

Description

[Detailed description of the invention] Regarding the manufacturing method.

Lithium hexafluorophosphate (LiPFs) is used as an electrolyte in lithium batteries (U.S. Pat. Nos. 3 and 4).
15,687). Especially electrochemistry, 1, 7
44 (1983), when used as an electrolyte in Li-graphite secondary batteries, it is easier to form intercalation compounds with graphite than other lithium salts such as LiCIO4 and LiBF4, and has excellent charge and discharge characteristics. It has been shown that

, lithium hexafluoride phosphate has conventionally been used as lithium fluoride (L
Jaws are created by reacting phosphorus pentafluoride (PFs) with phosphorus pentafluoride (PFs). For example, a method of conducting a reaction under heating without using a solvent is described in J. H.

SilOnS, ”FltlOrinl3 Cheii
The method for carrying out the reaction in anhydrous hydrogen fluoride is described in J.C.
hem. Soc. , 1963, part 4.

4408 (1963).

In addition, Japanese Patent Publication No. 46-3210 describes the reaction of saturated lower alkyl ethers or lower aliphatic saturated monocarboxylic acids in lower alkyl esters.
No. 33 describes a reaction in acetonitrile.

All of these methods use PFs, which is a gaseous compound and must be handled in a cylinder, which poses an obstacle during transportation. In addition, PFs is usually composed of calcium fluoride (CaF2) and sulfuric anhydride (H2 80
3) is produced by reacting CaF (SO3F) with phosphoric acid to produce POF3, which is further reacted with anhydrous hydrogen fluoride and purified to produce jaws. For this reason, PFs are expensive, and this makes L
This makes iPF5 expensive.

The present invention relates to a method of manufacturing LiPF6 at low cost without using PFS. According to the present invention, LiPF6 is prepared by combining lithium halides (LiF, LiC) in the presence of hydrogen fluoride.
1, Liar or Li1) and PCl5. That is, since solid PCl5 is used instead of gaseous PFs, it is easy to handle, and PCl5 is available at a much lower cost than PFS, so the present invention is excellent as an industrial method.

Hydrogen fluoride is used as the reaction solvent. The reaction vessels are made of corrosion-resistant materials such as nickel, Monel metal, and stainless steel.

The reaction is usually carried out under anhydrous conditions, and LiF is first completely dissolved in anhydrous hydrogen fluoride (AHF). Solvent H
F is used to sufficiently dissolve LiF at the reaction temperature. Normally, the amount of LiF dissolved in ioog AHF at 10°C is about 109. Therefore, when carrying out the reaction at 10° C., AHF is used in an amount 10 times or more as much as LiF. 10
It can be carried out using 0 times more AHF, but if
There is a lot of waste and no meaning. Usually 20 to 50 times the amount is used. Then phosphorus pentachloride (PCIs) is gradually added to this. If the amount of PCl5 is insufficient, unreacted LiF remains.

Even after HF is removed, some of this is mixed into the product as LiHF2. Therefore, it is preferable to add PCl5 in a slightly excess amount compared to LiF. Since the reaction ends immediately, there is no need to continue the reaction after adding PCl5.

The reaction temperature is -80 DEG C. to 19 DEG C. under normal pressure. The temperature is preferably -78.5°C (dry ice temperature) to 0°C. -8
At temperatures below 0°C, anhydrous hydrogen fluoride becomes a solid and becomes 19
If the temperature exceeds .degree. C., AHF will vaporize and the reaction will become extremely violent, which is not preferable.

After the reaction is completed, HF is removed by vaporization. For this purpose, the container is usually heated to -20 to 100°C, preferably 0 to 20°C, to further reduce production. Li produced above 100℃
Since the reaction in which PF6 decomposes into LiF and PFS becomes intense, the yield and purity of the product decrease, and at temperatures below -20°C, it takes a long time to remove 8HF. At this time ^HF
Although it is possible to vaporize rapidly, it is preferable to vaporize gradually. By gradually vaporizing LiPF in the container
, the crystal grows larger, and the larger the crystal, the more LiF and P
This is because the rate of decomposition into F5 becomes slower. The product obtained in this way contains colorless crystals of 1 to 3 IllI and partly a white powder. Although the powder part contains LiF, the LiPF6 content of the crystals is more than 99%. Alternatively, without completely removing AHF, only the crystals can be obtained by filtration at the time when the crystals have grown.

Next, the present invention will be explained in detail with reference to Examples.

Example 1 Reaction container made of Monel metal (inner diameter 80jlll x height 3
00im). All of the following operations were performed in a dry atmosphere, with particular care being taken to avoid contamination with moisture. A container containing 500 g of anhydrous hydrogen fluoride was cooled with dry ice-acetone, and LiF 10.4
9 (0,4101) was added and stirred thoroughly to completely dissolve. There PCl51109 (0,53■01)
was added gradually. When the addition was completed, the temperature of the container was raised to 0°C. The hydrogen chloride was vaporized and then the HF was gradually removed entrained in the nitrogen stream. LiPF6 with decrease in liver
crystallized. This was filtered and the crystals were separated by 20. The mixture was kept at 20° C. under reduced pressure of HQ for 3 hours to remove HF. Obtained LiPF
, was 40.0g, and the purity was over 99% (yield 65.
．． 1%).

Although approximately 109 LiPF6 is present in the filtrate, this filtrate is reused.

Example 2 Without filtration on the way, 0 until no HF comes out.
The temperature was then raised to 20°C and the last HF was removed under a vacuum of 20 amH (J) for 3 hours.

The experiment was conducted in the same manner as in Example 1 except for this. Product is 49.89, LiPF6 content 1i97%, yield 80%
Met.

From LiPF6 obtained in this way, relatively low temperature (
PFs can also be obtained by processing at a temperature of at least 30°C.

Patent Applicant: Daikin Industries, Ltd. Procedural Amendment Writing 1. August 9, 1980 1. Indication of the Case 1982 Patent Application No. 108229 2. Name of the Invention 6. Process for Producing Lithium Fluorophosphate 3. Person Making the Amendment Relationship to the incident Patent applicant location 1-12-39 Umeda, Kita-ku, Osaka New Hankyu Building Name (285) Representative of Daikin Industries, Ltd.
Yama 1) Gen 4 Agent 〒540 5 Subject of amendment (1) Contents of amendment in column 6 of “Detailed Description of the Invention” of the specification (1) Change [H2sOsJ to rsOaJ on page 2, line 19 of the specification]
and correct it.

that's all

Claims (1)

[Claims] 1. A method for producing lithium hexafluorophosphate, which comprises reacting lithium halide and phosphorus pentachloride in the presence of hydrogen fluoride.