CN116924380A - Preparation method of sodium difluorophosphate - Google Patents
Preparation method of sodium difluorophosphate Download PDFInfo
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- CN116924380A CN116924380A CN202311193837.8A CN202311193837A CN116924380A CN 116924380 A CN116924380 A CN 116924380A CN 202311193837 A CN202311193837 A CN 202311193837A CN 116924380 A CN116924380 A CN 116924380A
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- sodium
- difluorophosphate
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- sodium difluorophosphate
- filtrate
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- KBVUALKOHTZCGR-UHFFFAOYSA-M sodium;difluorophosphinate Chemical compound [Na+].[O-]P(F)(F)=O KBVUALKOHTZCGR-UHFFFAOYSA-M 0.000 title claims abstract description 45
- 238000002360 preparation method Methods 0.000 title claims abstract description 9
- 238000006243 chemical reaction Methods 0.000 claims abstract description 35
- DLYUQMMRRRQYAE-UHFFFAOYSA-N tetraphosphorus decaoxide Chemical compound O1P(O2)(=O)OP3(=O)OP1(=O)OP2(=O)O3 DLYUQMMRRRQYAE-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000013078 crystal Substances 0.000 claims abstract description 26
- 238000000034 method Methods 0.000 claims abstract description 17
- 239000000706 filtrate Substances 0.000 claims abstract description 15
- 238000001914 filtration Methods 0.000 claims abstract description 10
- 239000012454 non-polar solvent Substances 0.000 claims abstract description 7
- 238000001035 drying Methods 0.000 claims abstract description 5
- ZQDZSGHAIZKNHJ-UHFFFAOYSA-N trisodium difluoro oxalate borate Chemical compound [Na+].[Na+].[Na+].[O-]B([O-])[O-].FOC(=O)C(=O)OF ZQDZSGHAIZKNHJ-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000007788 liquid Substances 0.000 claims description 11
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 9
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 9
- 238000004821 distillation Methods 0.000 claims description 8
- 238000001291 vacuum drying Methods 0.000 claims description 8
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 claims description 6
- 239000000047 product Substances 0.000 claims description 5
- SCYULBFZEHDVBN-UHFFFAOYSA-N 1,1-Dichloroethane Chemical compound CC(Cl)Cl SCYULBFZEHDVBN-UHFFFAOYSA-N 0.000 claims description 3
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims description 3
- ZAFNJMIOTHYJRJ-UHFFFAOYSA-N Diisopropyl ether Chemical compound CC(C)OC(C)C ZAFNJMIOTHYJRJ-UHFFFAOYSA-N 0.000 claims description 3
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 5
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 abstract description 11
- 229910052708 sodium Inorganic materials 0.000 abstract description 11
- 239000011734 sodium Substances 0.000 abstract description 11
- 238000000746 purification Methods 0.000 abstract description 3
- 238000003786 synthesis reaction Methods 0.000 abstract description 3
- 239000002341 toxic gas Substances 0.000 abstract description 3
- 239000002000 Electrolyte additive Substances 0.000 abstract description 2
- 239000003054 catalyst Substances 0.000 abstract description 2
- 238000004090 dissolution Methods 0.000 abstract description 2
- 239000012467 final product Substances 0.000 abstract description 2
- 239000012535 impurity Substances 0.000 abstract description 2
- 239000006227 byproduct Substances 0.000 abstract 1
- 238000001953 recrystallisation Methods 0.000 abstract 1
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 description 16
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 10
- 239000000654 additive Substances 0.000 description 10
- 229910052744 lithium Inorganic materials 0.000 description 10
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 description 9
- 230000014759 maintenance of location Effects 0.000 description 7
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- JJFDUEREVQNQCH-UHFFFAOYSA-N B([O-])([O-])[O-].[Na+].C(C(=O)F)(=O)F.[Na+].[Na+] Chemical compound B([O-])([O-])[O-].[Na+].C(C(=O)F)(=O)F.[Na+].[Na+] JJFDUEREVQNQCH-UHFFFAOYSA-N 0.000 description 5
- 230000000996 additive effect Effects 0.000 description 5
- 239000003792 electrolyte Substances 0.000 description 5
- 229910021385 hard carbon Inorganic materials 0.000 description 5
- 229910021260 NaFe Inorganic materials 0.000 description 3
- 230000005611 electricity Effects 0.000 description 3
- FFUQCRZBKUBHQT-UHFFFAOYSA-N phosphoryl fluoride Chemical compound FP(F)(F)=O FFUQCRZBKUBHQT-UHFFFAOYSA-N 0.000 description 3
- RFRYDXDIJOVXOP-UHFFFAOYSA-N B([O-])(F)F.[Na+] Chemical compound B([O-])(F)F.[Na+] RFRYDXDIJOVXOP-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- HIFJUMGIHIZEPX-UHFFFAOYSA-N sulfuric acid;sulfur trioxide Chemical compound O=S(=O)=O.OS(O)(=O)=O HIFJUMGIHIZEPX-UHFFFAOYSA-N 0.000 description 2
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 1
- 229910012258 LiPO Inorganic materials 0.000 description 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- DGTVXEHQMSJRPE-UHFFFAOYSA-M difluorophosphinate Chemical compound [O-]P(F)(F)=O DGTVXEHQMSJRPE-UHFFFAOYSA-M 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 description 1
- 229940074371 monofluorophosphate Drugs 0.000 description 1
- 239000006259 organic additive Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- OBCUTHMOOONNBS-UHFFFAOYSA-N phosphorus pentafluoride Chemical compound FP(F)(F)(F)F OBCUTHMOOONNBS-UHFFFAOYSA-N 0.000 description 1
- -1 sodium hexafluorophosphate Chemical compound 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0567—Liquid materials characterised by the additives
-
- 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
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a preparation method of sodium difluorophosphate, and belongs to the field of battery electrolyte additives. And (3) reacting phosphorus pentoxide with sodium difluoro oxalate borate in a nonpolar solvent to obtain a sodium difluoro phosphate solution. Filtering the solution, distilling the filtrate under reduced pressure to obtain a crystal, and drying the crystal in vacuum to obtain sodium difluorophosphate. The invention only needs one-step synthesis reaction, and the reaction process is simple; the whole reaction does not need expensive catalyst; the byproducts can be removed only by filtration, and the yield is high; toxic gas is not required to be added in the reaction process, so that the method is environment-friendly; the purification process only needs to distill the filtrate, thereby avoiding the secondary dissolution of the recrystallization process; the final product has high purity and low impurity content. The synthesized sodium difluorophosphate can obviously improve the high and low temperature performance of the sodium battery, and has wide application prospect.
Description
Technical Field
The invention relates to the field of battery electrolyte additives, in particular to a preparation method of sodium difluorophosphate.
Background
The sodium battery and the lithium battery are rocking chair type secondary batteries, and are secondary batteries which rely on ions to insert and remove back and forth between positive and negative electrodes. With the rapid development of new energy power automobiles, the demand end of lithium resources is continuously vigorous, but the reserve of lithium in the crust is only about 0.0065%, and the lithium resources are distributed in more remote areas, so that the cost of links such as exploitation, extraction, transportation and processing of the lithium resources is increased. Compared with a lithium battery, the sodium battery has obvious cost advantage, and the high lithium price is expected to realize accelerated permeation. Sodium resources are abundant and uniformly distributed, and the sodium battery raw materials have cost advantages and are sufficiently supplied, so that a future supply chain is safer. The sodium ion battery and the lithium ion battery have the same working principle, and the product has the advantages of low cost, excellent multiplying power performance and high low-temperature capacity retention rate. Therefore, the sodium ion battery has wide prospect in energy storage, low-speed electric vehicles, backup power sources and power starting and stopping ponds in the future.
Similar to lithium electricity, the main composition of the sodium-electricity electrolyte also comprises electrolyteSalts, organic solvents and additives. However, through our tests, the additives commonly used in lithium battery electrolytes at present have not ideal effects in sodium electricity, especially in terms of high and low temperature performance. Lithium difluorophosphate has been reported (formula LiPO) 2 F 2 ) The high and low temperature cycle performance of the lithium battery can be obviously improved. However, few reports have been made on the synthesis of sodium difluorophosphate.
In the Chinese patent document with publication number of CN115947351A, a method for co-producing sodium hexafluorophosphate and sodium difluorophosphate is disclosed. However, the process firstly needs anhydrous hydrofluoric acid to react with phosphorus, then generates phosphorus oxytrifluoride with fuming sulfuric acid, and generates sodium difluorophosphate from phosphorus oxytrifluoride, a sodium source and a silicon-oxygen compound, the whole process is complicated, dangerous hydrofluoric acid and fuming sulfuric acid are used as raw materials, the cost of the silicon-oxygen compound in the second step is high, and the generated phosphorus oxytrifluoride and phosphorus pentafluoride are toxic gases, so that the whole process is high in cost and does not have environmental protection.
The Chinese patent document with publication number of CN116101996A discloses a combined preparation method of difluorophosphate and monofluorophosphate. Hydrofluoric acid is used in the first step, so that the risk is high; and the first step and the second step need purification, and the steps are complicated.
Therefore, a simple method for synthesizing sodium difluorophosphate is found, and the method has wide industrialized prospect.
Disclosure of Invention
The invention aims to provide a preparation method of sodium difluorophosphate, which has the advantages of simple process route, low cost, high product yield and high purity. The sodium difluorophosphate is also evaluated as a sodium electric additive, and the result shows that compared with Vinylene Carbonate (VC) and fluoroethylene carbonate (FEC), the sodium difluorophosphate synthesized by the invention can obviously improve the high and low temperature cycle performance of the sodium battery.
The preparation method of the sodium difluorophosphate provided by the invention comprises the following steps:
reacting phosphorus pentoxide with sodium difluorooxalate borate in a nonpolar solvent at 50-80 ℃ for 60-120min, filtering the reaction completion liquid after the reaction is completed, and purifying the filtrate to obtain a sodium difluorophosphate product; the molar ratio of the phosphorus pentoxide to the sodium difluoro oxalate borate is 1:1.8-2.2.
The equation for the reaction of phosphorus pentoxide and sodium difluorooxalato borate is:
2C 2 BF 2 NaO 4 +P 2 O 5 →2NaPO 2 F 2 +2CO+2CO 2 +B 2 O 3 。
preferably, the reaction temperature is 60-70 ℃ and the reaction time is 80-100min.
The nonpolar solvent is one of toluene, dichloroethane, chloroform, cyclohexane, ethyl acetate and isopropyl ether.
The proportion of the phosphorus pentoxide to the nonpolar solvent is 1mol:200-400ml.
The method for purifying the filtrate comprises the following steps: and (3) distilling the filtrate under reduced pressure to obtain a crystal, and drying the crystal in vacuum to obtain sodium difluorophosphate crystals with purity of more than 99% and yield of more than 98%.
The reduced pressure distillation temperature is 50-70 ℃, the pressure is 21Kpa-90Kpa, the vacuum drying temperature is 40-60 ℃, and the drying time is 18-24h.
The sodium difluorophosphate synthesized by the invention is used as an additive of sodium electricity and is 3.3V NaFe 1/3 Ni 1/3 Mn 1/3 O 2 Evaluating a hard carbon soft package battery system, and respectively performing high-temperature and low-temperature cycle life tests; and compared with 1.5% VC+1.5% FEC, 2% VC and base liquid respectively. By respectively comparing with VC+FEC, VC and base liquid, the sodium difluorophosphate of the invention is prepared by the method that the sodium difluorophosphate is prepared by the method of the invention under the condition of 3.3V NaFe 1/ 3 Ni 1/3 Mn 1/3 O 2 The high and low temperature cycle performance of the battery can be obviously improved under the hard carbon soft package battery system.
The preparation method of sodium difluorophosphate provided by the invention can complete the synthesis reaction in one step, and has a simple process route. The purification process avoids the secondary dissolution process, and has simple flow and high yield. The reaction process does not need the introduction of toxic gas, the temperature is also relatively mild, and the method is energy-saving and environment-friendly. The reaction does not need a catalyst, and the cost is low. The obtained final product has high purity (more than 99%), low impurity content (less than 40ppm of free acid, less than 20ppm of water, less than 5ppm of chloride ion and sulfate ion), high yield (more than 98%), and meets the requirements of battery-grade products.
Detailed Description
The technical scheme of the invention is clearly and completely described below by examples. Those skilled in the art will appreciate that the embodiments described below are some, but not all, embodiments of the present invention and are intended to be illustrative of the present invention only and should not be construed as limiting the scope of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
2.2mol of sodium difluorooxalate borate, 1.1mol of phosphorus pentoxide and 300ml of toluene are added into a 500ml reaction bottle, and stirred at 60 ℃ for reaction for 80min; filtering the reaction completion liquid after the reaction is finished, carrying out reduced pressure distillation on the filtrate for 12 hours at the temperature of 60 ℃ and the pressure of 21Kpa to obtain a crystal, and carrying out vacuum drying on the crystal at the temperature of 50 ℃ for 22 hours to obtain sodium difluorophosphate crystals; purity 99.9% and yield 98.9%.
Example 2
1.8mol of sodium difluorooxalate borate, 1mol of phosphorus pentoxide and 200ml of dichloroethane are added into a 500ml reaction bottle, and stirred at 50 ℃ for reaction for 60min; filtering the reaction completion liquid after the reaction is finished, carrying out reduced pressure distillation on the filtrate for 12 hours at the temperature of 50 ℃ and the pressure of 25Kpa to obtain a crystal, and carrying out vacuum drying on the crystal for 18 hours at the temperature of 40 ℃ to obtain sodium difluorophosphate crystals; purity 99.1% and yield 98.1%.
Example 3
2.2mol of sodium difluoroborate, 1mol of phosphorus pentoxide and 400ml of chloroform are added into a 500ml reaction bottle, and stirred and reacted for 120min at the temperature of 80 ℃; filtering the reaction completion liquid after the reaction is finished, carrying out reduced pressure distillation on the filtrate for 12 hours at the temperature of 55 ℃ and the pressure of 85Kpa to obtain a crystal, and carrying out vacuum drying on the crystal for 24 hours at the temperature of 60 ℃ to obtain sodium difluorophosphate crystals; purity 99.2% and yield 98.5%.
Example 4
1.9mol of sodium difluorooxalate borate, 0.9mol of phosphorus pentoxide and 301ml of cyclohexane are added into a 500ml reaction bottle, and stirred at 65 ℃ for reaction for 90min; filtering the reaction completion liquid after the reaction is finished, carrying out reduced pressure distillation on the filtrate for 12 hours at the temperature of 70 ℃ and 80Kpa to obtain a crystal, and carrying out vacuum drying on the crystal for 20 hours at the temperature of 45 ℃ to obtain sodium difluorophosphate crystals; purity 99.6% and yield 98.8%.
Example 5
2.1mol of sodium difluorooxalate borate, 1.1mol of phosphorus pentoxide and 355ml of ethyl acetate are added into a 500ml reaction bottle, and the mixture is stirred at 75 ℃ for reaction for 100min; filtering the reaction completion liquid after the reaction is finished, carrying out reduced pressure distillation on the filtrate for 12 hours at the temperature of 65 ℃ and the pressure of 82Kpa to obtain a crystal, and carrying out vacuum drying on the crystal at the temperature of 55 ℃ for 21 hours to obtain sodium difluorophosphate crystals; purity 99.3% and yield 98.2%.
Example 6
1.7mol of sodium difluoroborate, 0.8mol of phosphorus pentoxide and 228ml of isopropyl ether are added into a 500ml reaction bottle, and stirred at 70 ℃ for reaction for 70min; filtering the reaction completion liquid after the reaction is finished, carrying out reduced pressure distillation on the filtrate for 12 hours at the temperature of 60 ℃ and the pressure of 90Kpa to obtain a crystal, and carrying out vacuum drying on the crystal at the temperature of 50 ℃ for 22 hours to obtain sodium difluorophosphate crystals; purity 99.4% and yield 98.6%.
The performance indexes of the sodium difluorophosphate prepared in each example comprise purity, free acid content, moisture content, chloride ion content and sulfate ion content; see table 1.
Sodium difluorophosphates prepared in examples 1-6 were used as additives in 3.3V NaFe 1/3 Ni 1/3 Mn 1/3 O 2 The capacity retention rate of 0.5C/50 ℃ cycle 300 times and the capacity retention rate of 0.5C/-20 ℃ cycle 500 times are tested under the hard carbon soft package battery system and are respectively compared with the comparative examples; the additives used in comparative example 1 were VC and FEC, the amounts of added VC and FEC were 1.5% each (1.5% by mass of the additives VC and FEC based on the mass of the electrolyte)Percentage); the additive used in comparative example 2 was VC, the added amount of VC was 2% (2% is the percentage of the additive VC mass to the electrolyte mass); comparative example 3 is a base liquid (without any additives); the addition amount of the sodium difluorophosphate is 1.5 percent (1.5 percent is the percentage of the mass of the sodium difluorophosphate as the additive in the mass of the electrolyte). The test uses a battery test system, and the model is CT-4008-5A6V; the test results are shown in Table 2.
As can be seen from the test results of Table 2, naFe at 3.3V 1/3 Ni 1/3 Mn 1/3 O 2 Under a hard carbon soft package battery system, the capacity retention rate of the battery added with 1.5% of the sodium difluorophosphate prepared in the embodiment 1 after being cycled 300 times at 0.5C/50 ℃ is up to 89.2%, compared with 1.5% of VC+1.5% of FEC (79.4%), 2% of VC (71.3%), the contrast base solution (61.8%) is greatly improved, and the capacity retention rate of the sodium difluorophosphate prepared in other embodiments after being cycled 300 times at 0.5C/50 ℃ is higher than that of the contrast example, which indicates that the sodium difluorophosphate provided by the invention can improve the high-temperature performance of the battery.
As can be seen from the test results of Table 2, naFe at 3.3V 1/3 Ni 1/3 Mn 1/3 O 2 Under a hard carbon soft package battery system, the capacity retention rate of the battery added with 1.5% of the sodium difluorophosphate prepared in the embodiment 1 is as high as 91.5% when the battery is cycled 500 times at 0.5C/-20 ℃, compared with 1.5% of VC+1.5% of FEC (75.3%), 2% of VC (72.2%), the comparative base solution (54.2%), and the capacity retention rate of the sodium difluorophosphate prepared in other embodiments is higher than that of the comparative example when the battery is cycled 500 times at 0.5C/-20 ℃, which indicates that the sodium difluorophosphate provided by the invention can improve the low-temperature performance of the battery.
Claims (6)
1. A preparation method of sodium difluorophosphate is characterized in that:
the method comprises the following steps:
reacting phosphorus pentoxide with sodium difluoro oxalate borate in a nonpolar solvent at 50-80 ℃ for 60-120min, filtering the reaction completion liquid after the reaction is completed, and purifying the filtrate to obtain a sodium difluoro phosphate product; the molar ratio of the phosphorus pentoxide to the sodium difluoro oxalate borate is 1:1.8-2.2.
2. The method for producing sodium difluorophosphate as defined in claim 1, wherein: the reaction temperature is 60-70 ℃ and the reaction time is 80-100min.
3. The method for producing sodium difluorophosphate as defined in claim 1, wherein: the nonpolar solvent is one of toluene, dichloroethane, chloroform, cyclohexane, ethyl acetate and isopropyl ether.
4. The method for producing sodium difluorophosphate as defined in claim 1, wherein: the proportion of the phosphorus pentoxide to the nonpolar solvent is 1mol:200-400ml.
5. The method for producing sodium difluorophosphate as defined in claim 1, wherein: the method for purifying the filtrate comprises the following steps: and (3) distilling the filtrate under reduced pressure to obtain a crystal, and drying the crystal in vacuum to obtain sodium difluorophosphate crystals with purity of more than 99% and yield of more than 98%.
6. The method for producing sodium difluorophosphate as defined in claim 5, wherein: the temperature of the filtrate for reduced pressure distillation is 50-70 ℃, the pressure is 21-90 Kpa, the vacuum drying temperature is 40-60 ℃, and the drying time is 18-24h.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE813848C (en) * | 1949-04-06 | 1951-09-17 | Bayer Ag | Production of salts of difluorophosphoric acid |
| US3378340A (en) * | 1963-02-26 | 1968-04-16 | Socete D Etudes Chimiques Pour | Process for the preparation of potassium phosphate |
| JP2010155773A (en) * | 2008-12-02 | 2010-07-15 | Stella Chemifa Corp | Method for producing difluorophosphate |
| CN116216688A (en) * | 2023-03-27 | 2023-06-06 | 苏州华一新能源科技股份有限公司 | Preparation method of lithium difluorophosphate |
| CN116239130A (en) * | 2023-05-12 | 2023-06-09 | 广州天赐高新材料股份有限公司 | Method for co-producing hexafluorophosphate and difluorophosphate by one-pot method |
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2023
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE813848C (en) * | 1949-04-06 | 1951-09-17 | Bayer Ag | Production of salts of difluorophosphoric acid |
| US3378340A (en) * | 1963-02-26 | 1968-04-16 | Socete D Etudes Chimiques Pour | Process for the preparation of potassium phosphate |
| JP2010155773A (en) * | 2008-12-02 | 2010-07-15 | Stella Chemifa Corp | Method for producing difluorophosphate |
| CN116216688A (en) * | 2023-03-27 | 2023-06-06 | 苏州华一新能源科技股份有限公司 | Preparation method of lithium difluorophosphate |
| CN116239130A (en) * | 2023-05-12 | 2023-06-09 | 广州天赐高新材料股份有限公司 | Method for co-producing hexafluorophosphate and difluorophosphate by one-pot method |
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