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Preparation method of lithium difluorophosphate

A technology of lithium difluorophosphate and difluorophosphoric acid, which is applied in the field of electronic chemicals, can solve problems such as difficult separation and purification, high reaction temperature, and complicated operation, and achieve rapid and thorough reaction, mild reaction conditions, and strong operability Effect

Active Publication Date: 2021-07-23
RONGCHENG QINGMU CHEM MATERIALS
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Problems solved by technology

[0003] Regarding the preparation of difluorophosphate, the preparation methods recorded in the prior art all have deficiencies; for example: document Comprehensive Inorganic Chemistry, 1973, 2,536-537., potassium hexafluorophosphate and polymeric potassium phosphate are heated to 400 ° C, and the reaction ends Finally, obtain a mixture containing 97.5% potassium difluorophosphate, and recrystallize with isopropanol-water to obtain pure potassium difluorophosphate. This method has a high reaction temperature and serious energy consumption; document Z.Anorg.Allg.Chem., 1991 , 600, 221-226., using urea, potassium dihydrogen phosphate and ammonium bifluoride to melt and react to obtain potassium difluorophosphate. The reaction temperature of this method is about 170°C. Ammonia is produced, the environmental pressure is relatively high, and there are many residual ammonium fluoride in the product, which is not conducive to the purification of the final product; the document Journal of Fluorine Chemistry, 1988, 38, 297-302., uses P2O3F4 to react with metal salts or NH3 to prepare di Fluorophosphate, this method has many by-products, it is difficult to achieve separation and purification; Japanese patent JP2005219994 (A) discloses the production of lithium difluorophosphate by reacting lithium hexafluorophosphate with silicon dioxide at 50°C, but the reaction time takes 3 days, The time is too long; Japanese patent JP2013534511 (A) uses P4O10 powder to react with LiF powder, because it is a solid phase reaction, the mixture generated needs to be extracted with an organic solvent. This method has low yield, complicated operation, and easy formation of by-products. Not suitable for industrial production
[0004] In the above-mentioned existing preparation methods, there are problems such as high energy consumption, serious pollution, low yield, many by-products, difficulty in purification, etc., which are difficult for industrialized production
The prepared difluorophosphate has low purity, which affects product performance

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0029] (1) Preparation of sodium dichlorophosphate:

[0030] Add 164.0g of anhydrous trisodium phosphate (1.0mol) into a 3.0L four-neck flask, then add 2.0L of anhydrous acetonitrile, and slowly add 322.0g of phosphorus oxychloride (2.1mol) dropwise at room temperature, and there is exotherm during the dropping process . After the addition, the oil bath was heated to reflux temperature and stirred vigorously for 4h. After cooling, the reaction mixture was filtered, and the filtrate was concentrated to obtain 402.3 g of white solid, namely sodium dichlorophosphate, with a yield of 85.4%.

[0031] (2) Preparation of sodium difluorophosphate:

[0032] Add 402.3g of sodium dichlorophosphate (2.56mol) and 2.0L of anhydrous acetonitrile into a 3.0L four-neck flask, add 322.5g of anhydrous NaF (7.68mol) spray-dried in batches at reflux temperature, and stir vigorously at this temperature for 5 hours. After cooling, the reaction mixture was filtered, and the filtrate was concentrat...

Embodiment 2

[0038] (1) Preparation of Potassium Dichlorophosphate:

[0039] Add 212.3g of anhydrous tripotassium phosphate (1.0mol) into a 3.0L four-neck flask, then add 2.0L of anhydrous acetonitrile, and slowly add 322.0g of phosphorus oxychloride (2.1mol) dropwise at room temperature, and there is exotherm during the dropping process . After the addition, the oil bath was heated to reflux temperature and stirred vigorously for 4h. After cooling, the reaction mixture was filtered, and the filtrate was concentrated to obtain 451.5 g of white solid, namely potassium dichlorophosphate, with a yield of 87.0%.

[0040] (2) Preparation of Potassium Difluorophosphate:

[0041] Add 451.5g of potassium dichlorophosphate (2.61mol) and 2.0L of anhydrous acetonitrile into a 3.0L four-neck flask, add 454.9g of spray-dried anhydrous KF (7.83mol) in batches at reflux temperature, and stir vigorously at this temperature for 5h. After cooling, the reaction mixture was filtered, and the filtrate was c...

Embodiment 3

[0047] (1) Preparation of sodium dichlorophosphate:

[0048] Add 164.0g of anhydrous trisodium phosphate (1.0mol) into a 3.0L four-neck flask, then add 2.0L of anhydrous acetonitrile, and slowly add 322.0g of phosphorus oxychloride (2.1mol) dropwise at room temperature, and there is exotherm during the dropping process . After the addition, the oil bath was heated to reflux temperature and stirred vigorously for 2h. After cooling, the reaction mixture was filtered, and the filtrate was concentrated to obtain 353.5 g of white solid, namely sodium dichlorophosphate, with a yield of 75.0%.

[0049] (2) Preparation of sodium difluorophosphate:

[0050] Add 353.5g of sodium dichlorophosphate (2.25mol) and 2.0L of anhydrous acetonitrile into a 3.0L four-neck flask, add 283.4g of anhydrous NaF (6.74mol) spray-dried in batches at reflux temperature, and stir vigorously at this temperature for 3h. After cooling, the reaction mixture was filtered, and the filtrate was concentrated to...

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Abstract

The invention relates to the technical field of electronic chemicals, in particular to a preparation method of lithium difluorophosphate. The preparation method of the lithium difluorophosphate comprises the following steps: (1) reacting phosphorus oxychloride with anhydrous triphosphate to generate dichlorophosphate; (2) reacting the dichlorophosphate with a fluorinating reagent to generate difluorophosphate; (3) reacting the difluorophosphate with acid to displace difluorophosphoric acid; (4) purifying the difluorophosphoric acid, and reacting with a lithium source to generate lithium difluorophosphate; the step (1) to the step (4) are all carried out in an organic solvent. The method is low in raw material cost and easy to obtain, mild in reaction condition, simple in process, rapid and thorough in reaction, few in three wastes, high in operability and suitable for large-scale production, and a high-purity product is obtained while high yield is guaranteed.

Description

technical field [0001] The invention relates to the technical field of electronic chemicals, in particular to a preparation method of lithium difluorophosphate. Background technique [0002] In recent years, the basic research and application development of lithium-ion batteries have become one of the hot spots in the field of new energy, and all developed countries in the world regard it as a new industrial breakthrough point for development and research. Lithium difluorophosphate, as an electrolyte salt or electrolyte additive that can be used in lithium-ion secondary batteries, can significantly improve battery performance such as low-temperature characteristics, cycle characteristics, and storage characteristics of lithium-ion secondary batteries. [0003] Regarding the preparation of difluorophosphate, the preparation methods recorded in the prior art all have deficiencies; for example: document Comprehensive Inorganic Chemistry, 1973, 2,536-537., potassium hexafluoroph...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/455H01M10/0525H01M10/0567H01M10/0568H01M10/42
CPCC01B25/455H01M10/0567H01M10/0568H01M10/0525H01M10/4235Y02E60/10
Inventor 李维平王晓玲聂孟言孙朋波王芳芳
Owner RONGCHENG QINGMU CHEM MATERIALS
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