CN113336214A - Preparation method of lithium difluorophosphate - Google Patents
Preparation method of lithium difluorophosphate Download PDFInfo
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- CN113336214A CN113336214A CN202110800356.3A CN202110800356A CN113336214A CN 113336214 A CN113336214 A CN 113336214A CN 202110800356 A CN202110800356 A CN 202110800356A CN 113336214 A CN113336214 A CN 113336214A
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- lithium difluorophosphate
- difluorophosphate
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- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 title claims abstract description 69
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 claims abstract description 72
- 238000006243 chemical reaction Methods 0.000 claims abstract description 65
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims abstract description 58
- 239000007787 solid Substances 0.000 claims abstract description 43
- 239000002904 solvent Substances 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims abstract description 32
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 28
- 238000001914 filtration Methods 0.000 claims abstract description 26
- -1 lithium hexafluorophosphate Chemical compound 0.000 claims abstract description 24
- 239000000706 filtrate Substances 0.000 claims abstract description 19
- 239000000047 product Substances 0.000 claims abstract description 15
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 14
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 14
- 238000001291 vacuum drying Methods 0.000 claims abstract description 8
- 239000002244 precipitate Substances 0.000 claims abstract description 4
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims description 18
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 12
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 11
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 9
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 8
- LZDKZFUFMNSQCJ-UHFFFAOYSA-N 1,2-diethoxyethane Chemical compound CCOCCOCC LZDKZFUFMNSQCJ-UHFFFAOYSA-N 0.000 claims description 4
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 4
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 4
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 4
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 3
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000009776 industrial production Methods 0.000 abstract description 4
- 229910012265 LiPO2F2 Inorganic materials 0.000 description 12
- 239000000126 substance Substances 0.000 description 12
- 238000001035 drying Methods 0.000 description 11
- 239000002994 raw material Substances 0.000 description 11
- 238000004821 distillation Methods 0.000 description 9
- 239000012065 filter cake Substances 0.000 description 9
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000005481 NMR spectroscopy Methods 0.000 description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 239000006227 byproduct Substances 0.000 description 3
- 229910052808 lithium carbonate Inorganic materials 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 229910001290 LiPF6 Inorganic materials 0.000 description 2
- 229910019256 POF3 Inorganic materials 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- AZUYLZMQTIKGSC-UHFFFAOYSA-N 1-[6-[4-(5-chloro-6-methyl-1H-indazol-4-yl)-5-methyl-3-(1-methylindazol-5-yl)pyrazol-1-yl]-2-azaspiro[3.3]heptan-2-yl]prop-2-en-1-one Chemical compound ClC=1C(=C2C=NNC2=CC=1C)C=1C(=NN(C=1C)C1CC2(CN(C2)C(C=C)=O)C1)C=1C=C2C=NN(C2=CC=1)C AZUYLZMQTIKGSC-UHFFFAOYSA-N 0.000 description 1
- QTZBTBLHYPSFMG-UHFFFAOYSA-N 5-chloro-3-methylpyridin-2-amine Chemical compound CC1=CC(Cl)=CN=C1N QTZBTBLHYPSFMG-UHFFFAOYSA-N 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 239000002000 Electrolyte additive Substances 0.000 description 1
- PSAIQABKQGGSFL-UHFFFAOYSA-N FP(F)(=O)OP(F)(F)=O Chemical compound FP(F)(=O)OP(F)(F)=O PSAIQABKQGGSFL-UHFFFAOYSA-N 0.000 description 1
- 229910008963 Li2PO3F Inorganic materials 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 238000000806 fluorine-19 nuclear magnetic resonance spectrum Methods 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- 229910001947 lithium oxide Inorganic materials 0.000 description 1
- 229910001386 lithium phosphate Inorganic materials 0.000 description 1
- SNKMVYBWZDHJHE-UHFFFAOYSA-M lithium;dihydrogen phosphate Chemical compound [Li+].OP(O)([O-])=O SNKMVYBWZDHJHE-UHFFFAOYSA-M 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- CXHHBNMLPJOKQD-UHFFFAOYSA-M methyl carbonate Chemical compound COC([O-])=O CXHHBNMLPJOKQD-UHFFFAOYSA-M 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- OBCUTHMOOONNBS-UHFFFAOYSA-N phosphorus pentafluoride Chemical compound FP(F)(F)(F)F OBCUTHMOOONNBS-UHFFFAOYSA-N 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 description 1
- 229910021642 ultra pure water Inorganic materials 0.000 description 1
- 239000012498 ultrapure water Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Images
Classifications
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
- C01P2002/86—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by NMR- or ESR-data
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
Abstract
The invention relates to a preparation method of lithium difluorophosphate, which comprises the steps of sequentially adding a solvent A, lithium hexafluorophosphate and lithium hydroxide into a container, and reacting in a carbon dioxide atmosphere to obtain a reaction solution; filtering and vacuum drying the reaction solution to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride, pouring the white solid into a solvent B for dissolving, and filtering to respectively obtain a lithium fluoride precipitate and a filtrate; and distilling and vacuum drying the filtrate to constant weight to obtain a pure white solid anhydrous lithium difluorophosphate product. The method has the characteristics of low cost, high efficiency and easy realization of industrial production.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a preparation method of lithium difluorophosphate.
Background
The lithium ion battery is a novel green energy source, and is widely applied to a plurality of fields such as portable electronic products and electric automobiles due to the advantages of high working voltage, environmental protection, no pollution, light weight, no memory effect and the like. Meanwhile, with the conservation of the targets of 'carbon peak reaching' and 'carbon neutralization' in China, the new energy automobile industry is greatly strengthenedAnd meanwhile, the market demand of the lithium ion battery is larger and larger. Japanese patent laid-open No. 11-67270 first mentions the addition of lithium difluorophosphate (LiPO) to the electrolyte2F2) Can improve the high-temperature cycle performance of the battery, thereby initiating people to LiPO2F2Is a wide concern. LiPO2F2The advantages of electrolyte additives are many, for example: LiPO2F2The low-temperature performance of the battery can be improved; using Li2PO3F and LiPO2F2The film-forming additive can obviously improve the high-temperature storage performance of the lithium ion battery; mixing LiPO2F2The material is used together with methylene cyclic carbonate, so that the high-temperature cycle capacity and the high-temperature storage performance of the battery can be improved; mixing LiPO2F2The material is used in an overcharge-preventing additive system and is matched with other overcharge additives for use, so that the material can not only generate oxidation-reduction reaction at a specific potential to protect a battery and improve the safety of the battery, but also play a role in making the discharge capacity of the battery more uniform.
There are many conventional methods for synthesizing lithium difluorophosphate, such as: the preparation method comprises the step of preparing LiPO by reacting lithium oxide, lithium hydroxide (LiOH) and difluorophosphoric anhydride2F2In the preparation process, water is generated by taking LiOH as a raw material, so that the prepared LiPO2F2The possibility of hydrolysis exists; in order to solve the LiPO2F2Problem of hydrolysis, Spanish chemical of Japan uses phosphorus oxyhalides, oxyacids (anhydrides) of phosphorus and hydrogen fluoride to react to prepare difluorophosphoric acid, lithium hexafluorophosphate (LiPF)6) As a lithium source or moisture absorber, but halides may introduce halide ion impurities and hydrogen fluoride is highly corrosive; the patent CN2020114408007 discloses lithium phosphate (Li)2CO3) Lithium dihydrogen phosphate and phosphorus pentafluoride are used as raw materials to prepare LiPO2F2The method has high cost of raw materials and is difficult to meet the industrial requirement; patent CN2017111369615 discloses a LiPF6And Li2CO3Preparation of LiPO using ultrapure water as catalyst as raw material2F2The method has many byproducts and is not easy to control the reaction; patent CN2017100325308 discloses LiPF6And silane boron (or phosphorus) acid ester as raw materials to prepare LiPO2F2The method of (1) but the reaction conditions are harsh, the raw materials are expensive, and the production cost is overhigh; hexa patent CN2020115431439 discloses a gas-liquid-solid three-phase preparation LiPO2F2The method of (1) using a silicon oxide compound, LiF and POF3Is a raw material, but the cost of the raw material is high, and the POF3Is afraid of water, has pungent odor and strong corrosivity, and is not beneficial to industrial production.
Although the above methods have high yields, these methods suffer from high raw material prices and LiPO2F2The production cost is increased, the purification difficulty is high, the byproducts are more, and the like, so that the industrial scale production is difficult to realize.
Disclosure of Invention
The invention aims to solve the technical problem of providing a preparation method of lithium difluorophosphate, which has low cost and high efficiency and is easy to realize industrial production.
In order to solve the problems, the preparation method of lithium difluorophosphate is characterized by comprising the following steps: adding a solvent A, lithium hexafluorophosphate and lithium hydroxide into a container in sequence, and reacting in a carbon dioxide atmosphere to obtain a reaction solution; filtering and vacuum drying the reaction solution to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride, pouring the white solid into a solvent B with the mass 5-7 times that of the white solid for dissolving, and filtering to respectively obtain a lithium fluoride precipitate and a filtrate; and distilling and vacuum drying the filtrate to constant weight to obtain a pure white solid anhydrous lithium difluorophosphate product.
The synthetic route is as follows:
the molar ratio of the lithium hexafluorophosphate to the lithium hydroxide is 1: 4-5.
The ratio of the solvent A to the lithium hexafluorophosphate is 1L: 0.2-0.5 mol.
The solvent A is at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, ethylene carbonate and propylene carbonate.
The reaction conditions include a temperature of 25-80 ℃, a pressure of 1-40 atm and a reaction time of 1-12 hours.
The solvent B is at least one of acetonitrile, acetone, ethylene glycol dimethyl ether and ethylene glycol diethyl ether.
The vacuum drying condition is that the temperature is 40-60 ℃.
Compared with the prior art, the invention has the following advantages:
1. according to the invention, the conversion of lithium hydroxide and the generation of lithium carbonate are realized by utilizing the control of a carbon dioxide gas environment, and the high-activity lithium carbonate is prepared in situ and further reacts with lithium hexafluorophosphate to generate lithium difluorophosphate.
2. The invention has cheap and easily obtained reaction raw materials and solvent, and greatly reduces the production cost.
3. The reaction raw materials and the solvent are clean and nontoxic, the reaction process is clean, the environmental pollution is small, and the green chemical requirements are met.
4. The method has the advantages of mild reaction conditions, simple operation, high product yield, high purity and less by-products, thereby being easy for industrial production.
Drawings
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
FIG. 1 is a schematic representation of lithium difluorophosphate prepared according to example 1 of the present invention19F NMR spectrum.
Figure 2 is an XRD pattern of lithium difluorophosphate prepared in example 1 of the present invention.
Detailed Description
A preparation method of lithium difluorophosphate comprises the steps of sequentially adding a solvent A, lithium hexafluorophosphate and lithium hydroxide into a container, and reacting for 1-12 hours at 25-80 ℃ and 1-40 atm in a carbon dioxide atmosphere to obtain a reaction solution; and filtering the reaction solution, drying in vacuum to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride, pouring the white solid into a solvent B with the mass 5-7 times that of the white solid for dissolving, and filtering to respectively obtain a lithium fluoride precipitate and a filtrate, wherein the filtrate is a lithium difluorophosphate solution. And distilling the filtrate to remove the solvent, and drying the filtrate in vacuum at 40-60 ℃ to constant weight to obtain a white solid pure product of anhydrous lithium difluorophosphate.
Wherein: the molar ratio of lithium hexafluorophosphate to lithium hydroxide is 1: 4-5. The ratio of the solvent A to the lithium hexafluorophosphate is 1L: 0.2-0.5 mol.
The solvent A is at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, ethylene carbonate and propylene carbonate.
The solvent B is at least one of acetonitrile, acetone, ethylene glycol dimethyl ether and ethylene glycol diethyl ether.
Example 1a method for preparing lithium difluorophosphate, the method comprising:
100 mmol of lithium hexafluorophosphate and 400 mmol of lithium hydroxide are weighed, 300 mL of diethyl carbonate is added into a reaction bottle, the whole system is replaced by a carbon dioxide atmosphere, the reaction pressure is kept at 1atm, and the reaction is stopped after 5 hours at 60 ℃. Filtering the reaction solution, and drying the reaction solution at 60 ℃ in vacuum to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride; then pouring the white solid into 80mL of ethylene glycol dimethyl ether, wherein insoluble substances are lithium fluoride, a filter cake after filtration is the lithium fluoride, and a recoverable filtrate is a lithium difluorophosphate solution; after the solvent is removed by distillation, the white solid is dried in vacuum at 40 ℃, namely the pure anhydrous lithium difluorophosphate product, the yield is 91 percent, and the purity is 99.8 percent. The solvent can be recovered and reused.
Selecting Bruker AVANCE III 400 type superconducting nuclear magnetic resonance spectrometer (NMR) to carry out preparation on samples19Detecting nuclear magnetic resonance of the element F; as can be seen from FIG. 1, the chemical shift δ is-81.99X 10-6and-84.54X 10-6There appear 2 absorption peaks, corresponding to 2 fluorine atoms in lithium difluorophosphate.
The sample powder was subjected to phase analysis using a PANalytical X' Pert PRO polycrystalline powder X-ray diffractometer (XRD). As can be seen from FIG. 2, the lithium difluorophosphate powder has 2 groups of strong diffraction peaks between 20 and 25 degrees, 1 group of strong diffraction peaks between 25 and 30 degrees, 1 group of weak diffraction peaks between 30 and 40 degrees, 1 group of weak diffraction peaks between 40 and 50 degrees, and no obvious diffraction peak between 50 and 80 degrees.
Example 2 a method for preparing lithium difluorophosphate, the method comprising:
100 mmol of lithium hexafluorophosphate and 500 mmol of lithium hydroxide are weighed, 200 mL of diethyl carbonate is added into a reaction bottle, the whole system is replaced by a carbon dioxide atmosphere, the reaction pressure is kept at 1atm, and the reaction is stopped after 12 hours at 25 ℃. Filtering the reaction solution, and drying the reaction solution at 60 ℃ in vacuum to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride; then pouring the white solid into 80mL of ethylene glycol dimethyl ether, wherein insoluble substances are lithium fluoride, a filter cake after filtration is the lithium fluoride, and a recoverable filtrate is a lithium difluorophosphate solution; after the solvent is removed by distillation, the white solid is dried in vacuum at 40 ℃, namely the pure anhydrous lithium difluorophosphate product, the yield is 83 percent, and the purity is 99.8 percent. The solvent can be recovered and reused.
Example 3 a method for preparing lithium difluorophosphate, the method comprising:
100 mmol of lithium hexafluorophosphate and 450 mmol of lithium hydroxide are weighed, 400 mL of diethyl carbonate is added into a reaction bottle, the whole system is replaced by a carbon dioxide atmosphere, the reaction pressure is kept at 1atm, and the reaction is stopped after 1 hour of reaction at 80 ℃. Filtering the reaction solution, and drying the reaction solution at 60 ℃ in vacuum to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride; then pouring the white solid into 80mL of ethylene glycol dimethyl ether, wherein insoluble substances are lithium fluoride, a filter cake after filtration is the lithium fluoride, and a recoverable filtrate is a lithium difluorophosphate solution; after the solvent is removed by distillation, the white solid is dried in vacuum at 40 ℃, namely the pure anhydrous lithium difluorophosphate product, the yield is 90%, and the purity is 99.8%. The solvent can be recovered and reused.
Example 4 a method for preparing lithium difluorophosphate, the method comprising:
100 mmol of lithium hexafluorophosphate and 400 mmol of lithium hydroxide are weighed, 300 mL of diethyl carbonate is added into a reaction bottle, the whole system is replaced by a carbon dioxide atmosphere, the reaction pressure is kept at 40atm, and the reaction is stopped after 12 hours at 25 ℃. Filtering the reaction solution, and drying the reaction solution at 60 ℃ in vacuum to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride; then pouring the white solid into 80mL of ethylene glycol dimethyl ether, wherein insoluble substances are lithium fluoride, a filter cake after filtration is the lithium fluoride, and a recoverable filtrate is a lithium difluorophosphate solution; after the solvent is removed by distillation, the white solid is dried in vacuum at 40 ℃, namely the pure anhydrous lithium difluorophosphate product, the yield is 8 percent, and the purity is 99.8 percent. The solvent can be recovered and reused.
Example 5a method for preparing lithium difluorophosphate, the method comprising:
100 mmol of lithium hexafluorophosphate and 400 mmol of lithium hydroxide are weighed, 300 mL of diethyl carbonate is added into a reaction bottle, the whole system is replaced by a carbon dioxide atmosphere, the reaction pressure is kept at 1atm, and the reaction is stopped after 2 hours at 60 ℃. Filtering the reaction solution, and drying the reaction solution at 60 ℃ in vacuum to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride; pouring the white solid into 80mL of acetonitrile, wherein insoluble substances are lithium fluoride, a filter cake after filtration is the lithium fluoride, and a filtrate can be recovered to be a lithium difluorophosphate solution; after the solvent is removed by distillation, the white solid is dried in vacuum at 50 ℃, namely the pure anhydrous lithium difluorophosphate product, the yield is 90%, and the purity is 99.8%. The solvent can be recovered and reused.
Example 6 a method for preparing lithium difluorophosphate, the method comprising:
100 mmol of lithium hexafluorophosphate and 500 mmol of lithium hydroxide are weighed, 200 mL of ethyl methyl carbonate is added into a reaction bottle, the whole system is replaced by a carbon dioxide atmosphere, the reaction pressure is kept at 5atm, and the reaction is stopped after 12 hours at 30 ℃. Filtering the reaction solution, and drying the reaction solution at 50 ℃ in vacuum to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride; then pouring the white solid into 80mL of ethylene glycol dimethyl ether, wherein insoluble substances are lithium fluoride, a filter cake after filtration is the lithium fluoride, and a recoverable filtrate is a lithium difluorophosphate solution; after the solvent is removed by distillation, the white solid is dried in vacuum at 40 ℃, namely the pure anhydrous lithium difluorophosphate product, the yield is 65%, and the purity is 99.2%. The solvent can be recovered and reused.
Example 7 a method for preparing lithium difluorophosphate, the method comprising:
100 mmol of lithium hexafluorophosphate and 400 mmol of lithium hydroxide were weighed, 300 mL of methyl carbonate was charged into a reaction flask, the whole system was replaced with a carbon dioxide atmosphere and the reaction pressure was kept at 10atm, and after 12 hours of reaction at 40 ℃, the reaction was stopped. Filtering the reaction solution, and drying the reaction solution at 50 ℃ in vacuum to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride; then pouring the white solid into 80mL of ethylene glycol dimethyl ether, wherein insoluble substances are lithium fluoride, a filter cake after filtration is the lithium fluoride, and a recoverable filtrate is a lithium difluorophosphate solution; after the solvent is removed by distillation, the white solid is dried in vacuum at 40 ℃, namely the pure anhydrous lithium difluorophosphate product, the yield is 57 percent, and the purity is 99.0 percent. The solvent can be recovered and reused.
Embodiment 8 a method for preparing lithium difluorophosphate, the method comprising:
100 mmol of lithium hexafluorophosphate and 400 mmol of lithium hydroxide were weighed, 300 mL of ethylene carbonate was charged into a reaction flask, the whole system was replaced with a carbon dioxide atmosphere and the reaction pressure was kept at 20atm, and after 12 hours of reaction at 25 ℃, the reaction was stopped. Filtering the reaction solution, and drying the reaction solution at 60 ℃ in vacuum to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride; pouring the white solid into 80mL of ethylene glycol diethyl ether, wherein insoluble substances are lithium fluoride, a filter cake after filtration is the lithium fluoride, and a filtrate can be recovered to be a lithium difluorophosphate solution; after the solvent is removed by distillation, the white solid is dried in vacuum at 40 ℃, namely the pure anhydrous lithium difluorophosphate product, the yield is 48%, and the purity is 99.3%. The solvent can be recovered and reused.
Example 9 a method for preparing lithium difluorophosphate, the method comprising:
weighing 100 mmol of lithium hexafluorophosphate and 400 mmol of lithium hydroxide, adding 300 mL of propylene carbonate into a reaction bottle, replacing the whole system with a carbon dioxide atmosphere, keeping the reaction pressure at 30atm, reacting at 25 ℃ for 12 hours, and stopping the reaction. Filtering the reaction solution, and drying the reaction solution at 60 ℃ in vacuum to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride; then pouring the white solid into 80mL of acetone, wherein insoluble substances are lithium fluoride, a filter cake obtained after filtration is the lithium fluoride, and a filtrate can be recovered to be a lithium difluorophosphate solution; after the solvent is removed by distillation, the white solid is dried in vacuum at 40 ℃, namely the pure anhydrous lithium difluorophosphate product, the yield is 20%, and the purity is 99.1%. The solvent can be recovered and reused.
Claims (7)
1. A preparation method of lithium difluorophosphate is characterized by comprising the following steps: adding a solvent A, lithium hexafluorophosphate and lithium hydroxide into a container in sequence, and reacting in a carbon dioxide atmosphere to obtain a reaction solution; filtering and vacuum drying the reaction solution to constant weight to obtain a white solid containing lithium difluorophosphate and lithium fluoride, pouring the white solid into a solvent B with the mass 5-7 times that of the white solid for dissolving, and filtering to respectively obtain a lithium fluoride precipitate and a filtrate; and distilling and vacuum drying the filtrate to constant weight to obtain a pure white solid anhydrous lithium difluorophosphate product.
2. The method for preparing lithium difluorophosphate as claimed in claim 1, wherein: the molar ratio of the lithium hexafluorophosphate to the lithium hydroxide is 1: 4-5.
3. The method for preparing lithium difluorophosphate as claimed in claim 1, wherein: the ratio of the solvent A to the lithium hexafluorophosphate is 1L: 0.2-0.5 mol.
4. The method for preparing lithium difluorophosphate as claimed in claim 1 or 3, wherein: the solvent A is at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, ethylene carbonate and propylene carbonate.
5. The method for preparing lithium difluorophosphate as claimed in claim 1, wherein: the reaction conditions include a temperature of 25-80 ℃, a pressure of 1-40 atm and a reaction time of 1-12 hours.
6. The method for preparing lithium difluorophosphate as claimed in claim 1, wherein: the solvent B is at least one of acetonitrile, acetone, ethylene glycol dimethyl ether and ethylene glycol diethyl ether.
7. The method for preparing lithium difluorophosphate as claimed in claim 1, wherein: the vacuum drying condition is that the temperature is 40-60 ℃.
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