CN112028047A - Preparation method of lithium difluorophosphate - Google Patents
Preparation method of lithium difluorophosphate Download PDFInfo
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- CN112028047A CN112028047A CN202010959043.8A CN202010959043A CN112028047A CN 112028047 A CN112028047 A CN 112028047A CN 202010959043 A CN202010959043 A CN 202010959043A CN 112028047 A CN112028047 A CN 112028047A
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- lithium
- lithium difluorophosphate
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/455—Phosphates containing halogen
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
- C01P2006/82—Compositional purity water content
Abstract
The invention provides a preparation method of lithium difluorophosphate. The method takes phosphorus pentafluoride and lithium phosphate as raw materials, prepares lithium difluorophosphate through gas-solid one-step reaction, and has the advantages of short process flow, high reaction efficiency, less side reactions, good product quality, high purity up to 99.99 percent, and no three wastes discharge. The process has short production period and is easy to be industrialized, implemented and popularized.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a preparation method of lithium difluorophosphate.
Background
The quality of the high-low temperature cycle performance of the lithium ion battery directly determines the endurance mileage and the service life of the electric automobile. The most widely used electrolyte material at present is lithium hexafluorophosphate, but the lithium hexafluorophosphate has the problems of sensitivity to water and poor thermal stability. Therefore, the development of a novel electrolyte salt capable of improving the electrochemical and chemical stability of the lithium ion battery as an additive can be matched with lithium hexafluorophosphate for use, and the development is an important research direction for improving the performance of the lithium ion battery.
Lithium difluorophosphate of formula LiPO2F2White powdery solid, melting point 340 ℃, is exposed to air and is easy to absorb moisture in the air and shows acidity. The electrolyte additive is applied to the field of lithium ion batteries, can improve the cycle performance and the high-temperature storage performance of the batteries, can reduce the internal resistance of the batteries, and forms a protective film on the positive electrode of the batteries, so that the cycle performance of the batteries is obviously improved.
Preparation of LiPO2F2The method mainly comprises two categories according to the source of raw materials, wherein one category is a difluorophosphoric acid method, which means that LiPO is prepared2F2In the process of (A), difluorophosphoric acid, difluorophosphoric anhydride (P) are used2O3F4) Or difluorophosphoric acid (HPO)2F2) Is prepared as a target intermediate product thereof to produce LiPO2F2A method of (1). The method comprises the presence of difluorophosphoric acid and difluorophosphoric acidThe anhydride is unstable, has strong toxicity, is expensive, is difficult to obtain high-purity raw materials, and is not beneficial to industrial production. One is a lithium hexafluorophosphate method, which is used for preparing LiPO2F2The processes of (1) are methods using lithium hexafluorophosphate as a raw material, and are divided into a lithium hexafluorophosphate hydrolysis method and a lithium hexafluorophosphate direct reaction method. The method has the defects of difficult control of reaction, more side reactions, low product purity and the like.
In summary, although LiPO2F2The preparation technology of (2) has been studied by many researchers, but still has many problems, and industrial popularization cannot be implemented. Therefore, it is urgently needed to develop a LiPO with simple process, high reaction efficiency and high product purity2F2A preparation method.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a preparation method of lithium difluorophosphate.
The invention provides a preparation method of lithium difluorophosphate, which comprises the following steps:
s1: under inert atmosphere, putting lithium phosphate into an organic solvent, and introducing phosphorus pentafluoride gas into the organic solvent for reaction;
s2: and S1, filtering the product to obtain a first filter residue and a first filtrate, wherein the first filtrate is a lithium difluorophosphate solution, concentrating the lithium difluorophosphate solution under reduced pressure, crystallizing and filtering to obtain a second filter residue and a second filtrate, and drying the second filter residue to obtain the lithium difluorophosphate.
In step S1:
the organic solvent has two functions. In a first aspect: dissolving lithium phosphate to change solid-phase lithium phosphate into liquid phase, and increasing the specific surface area of the substance (the specific surface area of the same substance is smaller than that of the liquid phase, and the gas phase is the largest), so that the contact with the phosphorus pentafluoride gas is increased, and the reaction rate is accelerated; in a second aspect: the lithium difluorophosphate produced is dissolved in an organic solvent, and lithium fluoride is precipitated as insoluble matter.
The inert atmosphere is nitrogen.
In step S2:
the first filter residue is a by-product lithium fluoride.
According to some embodiments of the invention, in step S1, the mass ratio of the lithium phosphate to the organic solvent is 1: (8-12).
According to some embodiments of the invention, in step S1, the reaction formula of lithium phosphate and phosphorus pentafluoride is:
PF5+Li3PO4→2LiPO2F2+LiF。
according to some embodiments of the present invention, in step S1, the organic solvent is selected from one of an ester solvent, an ether solvent and an alcohol solvent.
According to some embodiments of the present invention, the ester solvent is at least one of dimethyl carbonate, diethyl carbonate, and ethylene carbonate.
According to some embodiments of the invention, the ethereal solvent is at least one of diethyl ether, propyl ether and ethylene glycol dimethyl ether.
According to some embodiments of the invention, the alcoholic solvent is at least one of methanol, ethanol.
According to some embodiments of the invention, in step S1, the molar ratio of the lithium phosphate to the phosphorus pentafluoride gas is (1-1.05): 1.
according to some embodiments of the present invention, in step S1, the reaction temperature is 70-120 ℃ and the reaction time is 1-2 h.
According to some embodiments of the invention, in step S2, the temperature of the reduced pressure concentration is 35-70 ℃, and the pressure of the reduced pressure concentration is-0.09 to-0.1 MPa.
According to some embodiments of the invention, further comprising after step S2, returning the second filtrate to step S1.
The preparation method of lithium difluorophosphate according to the embodiment of the invention has at least the following technical effects:
the preparation method of the invention takes phosphorus pentafluoride and lithium phosphate as raw materials, prepares the lithium difluorophosphate through gas-solid one-step reaction, and has the advantages of short process flow, high reaction efficiency, less side reaction, good product quality, high purity up to 99.99 percent, and no three wastes discharge.
The preparation method of the invention has short process production period and is easy to be industrialized and popularized.
Drawings
FIG. 1 is a flow chart of a process for preparing lithium difluorophosphate according to an embodiment of the present invention.
Detailed Description
The following are specific examples of the present invention, and the technical solutions of the present invention will be further described with reference to the examples, but the present invention is not limited to the examples.
Example 1
The lithium difluorophosphate is prepared by the method, the flow chart is shown in figure 1, and the method comprises the following specific steps:
s1: under the protection of nitrogen, adding 360g of dimethyl carbonate and 30g of lithium phosphate into a closed container with a mechanical stirrer, a thermometer and a condenser, starting stirring, heating to 70 ℃, continuously introducing 29g of phosphorus pentafluoride gas with the gas flow rate of 0.2L/min, continuously reacting for 2h, and obtaining slurry containing lithium difluorophosphate after reaction;
s2: and S1, filtering the product to obtain 6.7g of lithium fluoride product and lithium difluorophosphate filtrate, carrying out reduced pressure distillation on the lithium difluorophosphate filtrate at 35 ℃ under the pressure of-0.1 MPa, concentrating until the mass is 2/3 of the original solution, stopping distillation, cooling, crystallizing, filtering, recycling the filtrate, and drying filter residues to obtain 42.5g of lithium difluorophosphate product.
Example 2
The lithium difluorophosphate is prepared by the following specific steps:
s1: under the protection of argon, adding 500g of ethylene glycol dimethyl ether and 50g of lithium phosphate into a closed container with a mechanical stirrer, a thermometer and a condenser, starting stirring, heating to 100 ℃, continuously introducing 53.2g of phosphorus pentafluoride gas with the gas flow rate of 0.4L/min, continuously reacting for 1h, and obtaining slurry containing lithium difluorophosphate after reaction;
s2: and S1, filtering the product to obtain 10.5g of lithium fluoride product and lithium difluorophosphate filtrate, carrying out reduced pressure distillation on the lithium difluorophosphate filtrate at 70 ℃ under the pressure of-0.095 MPa, concentrating to 3/4 mass of the original solution, stopping distillation, cooling, crystallizing, filtering, recycling the filtrate, and drying filter residues to obtain 83.5g of lithium difluorophosphate product.
Example 3
The lithium difluorophosphate is prepared by the following specific steps:
s1: under the protection of helium, adding 520g of ethylene carbonate and 65g of lithium phosphate into a closed container with a mechanical stirrer, a thermometer and a condenser, starting stirring, heating to 120 ℃, continuously introducing 67.2g of phosphorus pentafluoride gas with the gas flow rate of 0.3L/min, continuing reacting for 1h, and obtaining slurry containing lithium difluorophosphate after the reaction;
s2: and (4) filtering the product obtained in the step (S1) to obtain 14.5g of lithium fluoride product and lithium difluorophosphate filtrate, carrying out reduced pressure distillation on the lithium difluorophosphate filtrate at 50 ℃ under the control of pressure of-0.1 MPa, concentrating until reaching 5/6 of the original solution, stopping distillation, cooling, crystallizing, filtering, recycling the filtrate, and drying filter residues to obtain 1114.1g of lithium difluorophosphate product.
Example of detection
The lithium difluorophosphate products prepared in examples 1 to 3 were tested and the results are shown in Table 1.
Table 1 test results of lithium difluorophosphate products obtained in examples
The detection results in table 1 show that the lithium difluorophosphate prepared by the method of the invention has high purity and low impurity content, and can meet the application requirements of lithium battery electrolyte salt or additives.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.
Claims (10)
1. A preparation method of lithium difluorophosphate is characterized by comprising the following steps:
s1: under inert atmosphere, putting lithium phosphate into an organic solvent, and introducing phosphorus pentafluoride gas into the organic solvent for reaction;
s2: and S1, filtering the product to obtain a first filter residue and a first filtrate, wherein the first filtrate is a lithium difluorophosphate solution, concentrating the lithium difluorophosphate solution under reduced pressure, crystallizing and filtering to obtain a second filter residue and a second filtrate, and drying the second filter residue to obtain the lithium difluorophosphate.
2. The method according to claim 1, wherein in step S1, the mass ratio of the lithium phosphate to the organic solvent is 1: (8-12).
3. The method according to claim 1 or 2, wherein in step S1, the organic solvent is one selected from the group consisting of an ester solvent, an ether solvent, and an alcohol solvent.
4. The method according to claim 3, wherein the ester solvent is at least one of dimethyl carbonate, diethyl carbonate, and ethylene carbonate.
5. The method according to claim 3, wherein the ethereal solvent is at least one of diethyl ether, propyl ether and ethylene glycol dimethyl ether.
6. The method according to claim 3, wherein the alcoholic solvent is at least one of methanol and ethanol.
7. The production method according to claim 1, wherein in step S1, the molar ratio of the lithium phosphate gas to the phosphorus pentafluoride gas is (1 to 1.05): 1.
8. the method according to claim 1, wherein in step S1, the reaction temperature is 70-120 ℃ and the reaction time is 1-2 h.
9. The method according to claim 1, wherein the temperature of the vacuum concentration is 35 to 70 ℃ and the pressure of the vacuum concentration is-0.09 to-0.1 MPa in step S2.
10. The method of claim 1, further comprising returning the second filtrate to step S1 after step S2.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112456465A (en) * | 2020-12-11 | 2021-03-09 | 安阳工学院 | Preparation method of lithium difluorophosphate |
| CN115571900A (en) * | 2022-11-21 | 2023-01-06 | 东营领仕科技咨询有限公司 | Preparation method of lithium difluorophosphate and lithium hexafluorophosphate co-production |
Citations (4)
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|---|---|---|---|---|
| CN101626978A (en) * | 2007-03-12 | 2010-01-13 | 中央硝子株式会社 | Method for producing lithium difluorophosphate and nonaqueous electrolyte battery using the same |
| CN103052592A (en) * | 2010-08-04 | 2013-04-17 | 索尔维公司 | Manufacture of lipo2f2 from pof3 or pf5 |
| CN105236368A (en) * | 2015-09-10 | 2016-01-13 | 天津金牛电源材料有限责任公司 | Preparation method of difluorophosphoric acid alkali metal salt |
| CN106882782A (en) * | 2017-03-25 | 2017-06-23 | 山东永浩新材料科技有限公司 | A kind of synthetic method of difluorophosphate |
-
2020
- 2020-09-14 CN CN202010959043.8A patent/CN112028047A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101626978A (en) * | 2007-03-12 | 2010-01-13 | 中央硝子株式会社 | Method for producing lithium difluorophosphate and nonaqueous electrolyte battery using the same |
| CN103052592A (en) * | 2010-08-04 | 2013-04-17 | 索尔维公司 | Manufacture of lipo2f2 from pof3 or pf5 |
| US20130129595A1 (en) * | 2010-08-04 | 2013-05-23 | Solvay Sa | Manufacture of LiPO2F2 from POF3 or PF5 |
| CN105236368A (en) * | 2015-09-10 | 2016-01-13 | 天津金牛电源材料有限责任公司 | Preparation method of difluorophosphoric acid alkali metal salt |
| CN106882782A (en) * | 2017-03-25 | 2017-06-23 | 山东永浩新材料科技有限公司 | A kind of synthetic method of difluorophosphate |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112456465A (en) * | 2020-12-11 | 2021-03-09 | 安阳工学院 | Preparation method of lithium difluorophosphate |
| CN115571900A (en) * | 2022-11-21 | 2023-01-06 | 东营领仕科技咨询有限公司 | Preparation method of lithium difluorophosphate and lithium hexafluorophosphate co-production |
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