CN113527363B - Preparation method of difluoro lithium bisoxalato phosphate or tetrafluoro lithium oxalato phosphate - Google Patents
Preparation method of difluoro lithium bisoxalato phosphate or tetrafluoro lithium oxalato phosphate Download PDFInfo
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- CN113527363B CN113527363B CN202110540184.0A CN202110540184A CN113527363B CN 113527363 B CN113527363 B CN 113527363B CN 202110540184 A CN202110540184 A CN 202110540184A CN 113527363 B CN113527363 B CN 113527363B
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- -1 difluoro lithium Chemical compound 0.000 title claims abstract description 35
- 238000002360 preparation method Methods 0.000 title claims abstract description 23
- 229910019142 PO4 Inorganic materials 0.000 title claims description 91
- 239000010452 phosphate Substances 0.000 title claims description 91
- 229910052744 lithium Inorganic materials 0.000 title claims description 86
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 title claims description 83
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims description 65
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims abstract description 96
- 238000006243 chemical reaction Methods 0.000 claims abstract description 67
- UHZYTMXLRWXGPK-UHFFFAOYSA-N phosphorus pentachloride Chemical compound ClP(Cl)(Cl)(Cl)Cl UHZYTMXLRWXGPK-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000002904 solvent Substances 0.000 claims abstract description 38
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 37
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims abstract description 37
- 235000006408 oxalic acid Nutrition 0.000 claims abstract description 32
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 31
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 31
- 238000004519 manufacturing process Methods 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 21
- 239000012535 impurity Substances 0.000 claims abstract description 19
- 238000003756 stirring Methods 0.000 claims abstract description 16
- 238000003682 fluorination reaction Methods 0.000 claims abstract description 15
- PQIOSYKVBBWRRI-UHFFFAOYSA-N methylphosphonyl difluoride Chemical group CP(F)(F)=O PQIOSYKVBBWRRI-UHFFFAOYSA-N 0.000 claims abstract description 13
- NBIIXXVUZAFLBC-UHFFFAOYSA-L Phosphate ion(2-) Chemical compound OP([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-L 0.000 claims abstract description 4
- 239000006185 dispersion Substances 0.000 claims abstract description 4
- 239000007788 liquid Substances 0.000 claims abstract description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 22
- 238000001914 filtration Methods 0.000 claims description 17
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 14
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 14
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical group [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 14
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 12
- 239000000706 filtrate Substances 0.000 claims description 11
- 229910052757 nitrogen Inorganic materials 0.000 claims description 11
- 238000002425 crystallisation Methods 0.000 claims description 10
- 230000008025 crystallization Effects 0.000 claims description 10
- 239000007787 solid Substances 0.000 claims description 10
- 238000001816 cooling Methods 0.000 claims description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 8
- USGDMCWUHFXPCY-UHFFFAOYSA-M C(C(=O)O)(=O)[O-].P(=O)(O)(O)O.[Li+] Chemical compound C(C(=O)O)(=O)[O-].P(=O)(O)(O)O.[Li+] USGDMCWUHFXPCY-UHFFFAOYSA-M 0.000 claims description 8
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 claims description 8
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 7
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 7
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 7
- 238000001291 vacuum drying Methods 0.000 claims description 6
- YNQRWVCLAIUHHI-UHFFFAOYSA-L dilithium;oxalate Chemical compound [Li+].[Li+].[O-]C(=O)C([O-])=O YNQRWVCLAIUHHI-UHFFFAOYSA-L 0.000 claims description 5
- 229910052786 argon Inorganic materials 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 229910052734 helium Inorganic materials 0.000 claims description 4
- 239000001307 helium Substances 0.000 claims description 4
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 4
- 238000010926 purge Methods 0.000 claims description 4
- 229920006395 saturated elastomer Polymers 0.000 claims description 4
- 238000004334 fluoridation Methods 0.000 claims description 3
- 150000003627 tricarboxylic acid derivatives Chemical class 0.000 claims description 3
- 101150107401 outH gene Proteins 0.000 claims 1
- 239000002994 raw material Substances 0.000 abstract description 20
- 239000002253 acid Substances 0.000 abstract description 15
- 229910001386 lithium phosphate Inorganic materials 0.000 abstract description 8
- LKSCJMIATJONBS-UHFFFAOYSA-K trilithium oxalic acid phosphate Chemical compound P(=O)([O-])([O-])[O-].[Li+].C(C(=O)O)(=O)O.[Li+].[Li+] LKSCJMIATJONBS-UHFFFAOYSA-K 0.000 abstract description 7
- 239000002912 waste gas Substances 0.000 abstract description 4
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 34
- 239000000047 product Substances 0.000 description 21
- 230000000052 comparative effect Effects 0.000 description 14
- 239000007789 gas Substances 0.000 description 14
- 238000005481 NMR spectroscopy Methods 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 7
- 239000003792 electrolyte Substances 0.000 description 7
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 229910001416 lithium ion Inorganic materials 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 5
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 description 5
- 239000000654 additive Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 3
- 230000000996 additive effect Effects 0.000 description 3
- 239000012752 auxiliary agent Substances 0.000 description 3
- 239000012467 final product Substances 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 3
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 3
- 239000005457 ice water Substances 0.000 description 3
- 238000004293 19F NMR spectroscopy Methods 0.000 description 2
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 description 2
- AUBNQVSSTJZVMY-UHFFFAOYSA-M P(=O)([O-])(O)O.C(C(=O)O)(=O)F.C(C(=O)O)(=O)F.C(C(=O)O)(=O)F.C(C(=O)O)(=O)F.[Li+] Chemical compound P(=O)([O-])(O)O.C(C(=O)O)(=O)F.C(C(=O)O)(=O)F.C(C(=O)O)(=O)F.C(C(=O)O)(=O)F.[Li+] AUBNQVSSTJZVMY-UHFFFAOYSA-M 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 239000012295 chemical reaction liquid Substances 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 238000004821 distillation Methods 0.000 description 2
- 238000004255 ion exchange chromatography Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000011255 nonaqueous electrolyte Substances 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- OBCUTHMOOONNBS-UHFFFAOYSA-N phosphorus pentafluoride Chemical compound FP(F)(F)(F)F OBCUTHMOOONNBS-UHFFFAOYSA-N 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000005049 silicon tetrachloride Substances 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- GOIXNQVIDQSYOR-UHFFFAOYSA-J tetralithium 2-fluoro-2-oxoacetate Chemical compound C(C(=O)[O-])(=O)F.C(C(=O)[O-])(=O)F.C(C(=O)[O-])(=O)F.C(C(=O)[O-])(=O)F.[Li+].[Li+].[Li+].[Li+] GOIXNQVIDQSYOR-UHFFFAOYSA-J 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 150000005678 chain carbonates Chemical class 0.000 description 1
- 239000012045 crude solution Substances 0.000 description 1
- 150000005676 cyclic carbonates Chemical class 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000002198 insoluble material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic Table
- C07F9/02—Phosphorus compounds
- C07F9/547—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom
- C07F9/6564—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms
- C07F9/6571—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms having phosphorus and oxygen atoms as the only ring hetero atoms
- C07F9/6574—Esters of oxyacids of phosphorus
- C07F9/65748—Esters of oxyacids of phosphorus the cyclic phosphorus atom belonging to more than one ring system
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic Table
- C07F9/02—Phosphorus compounds
- C07F9/547—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom
- C07F9/6564—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms
- C07F9/6571—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms having phosphorus and oxygen atoms as the only ring hetero atoms
- C07F9/6574—Esters of oxyacids of phosphorus
- C07F9/65742—Esters of oxyacids of phosphorus non-condensed with carbocyclic rings or heterocyclic rings or ring systems
-
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Molecular Biology (AREA)
- Secondary Cells (AREA)
Abstract
The invention discloses a preparation method of difluoro double oxalic acid lithium phosphate or tetrafluoro oxalic acid lithium phosphate, which comprises the steps of adding phosphorus pentachloride and oxalic acid into a first nonaqueous solvent, and reacting under stirring to obtain a trioxalic acid hydrogen phosphate solution; introducing hydrogen fluoride into the hydrogen phosphate tricarboxylic acid solution to carry out fluorination reaction; and adding the fluorinated solution into a second nonaqueous solvent dispersion liquid containing lithium salt, and reacting under stirring to obtain difluoro-lithium phosphate or tetrafluoro-lithium phosphate. The preparation method of the invention does not use conventional lithium hexafluorophosphate as a raw material, so that impurities such as lithium difluorophosphate are not generated. The method has the advantages of simple raw materials, low price, simple and practical process, mild reaction conditions, easy treatment of waste gas generated in the reaction and contribution to industrialized mass production.
Description
Technical Field
The invention relates to the field of additives for nonaqueous electrolyte of lithium ion batteries, lithium ion capacitors and the like, in particular to a preparation method of difluoro-lithium bisoxalato-phosphate or tetrafluoro-lithium oxalato-phosphate.
Background
The lithium ion battery mainly comprises a positive electrode, a negative electrode, a diaphragm, electrolyte and the like. The electrolyte mainly comprises electrolyte and organic solvent, is an active component for connecting the anode and the cathode, and is an important factor for connecting the performance of the battery. The additive is an important component except electrolyte and organic solvent in the lithium ion battery electrolyte, and a proper additive can play an important role in enhancing the performance of the lithium battery. The difluoro-lithium oxalate phosphate or the tetrafluoro-lithium oxalate phosphate is mainly applied to nonaqueous electrolyte of lithium ion batteries, lithium ion capacitors and the like. After the additive is added, the heat stability and the hydrolytic stability of the electrolyte can be improved, the two properties still keep good even after the battery ages, a more stable solid electrolyte interface film structure can be formed on the surface of the positive electrode material, and the cycle charge and discharge performance of the battery is improved.
At present, a plurality of methods for preparing difluoro double lithium oxalate phosphate and tetrafluoro lithium oxalate phosphate have been disclosed, most of the methods are prepared by adopting auxiliary agents such as hexafluorophosphate and silicon tetrachloride as main raw materials, but in the reaction process, hexafluorophosphate is easy to be partially decomposed to generate phosphorus pentafluoride or react with other oxygen-containing substances to generate difluoro lithium phosphate, so that the impurity removal is difficult, and meanwhile, in the reaction process by using silicon auxiliary agents, a large amount of silicon tetrafluoride and hydrogen chloride gas are generated, so that the separation and the utilization are difficult, the safety risk is high, and the industrialization is more difficult.
Patent application CN102216311B discloses a process for preparing lithium difluorobisoxalato phosphate using oxalic acid, lithium hexafluorophosphate and silicon tetrachloride as starting materials, but this process produces large amounts of highly corrosive acid gases HCl and SiF 4 The method has high equipment requirements, is difficult to separate from products, has difficult control of chloride ion content and acid value in the products, and has hidden danger and risk in safety and reliability.
Patent CN105218348B discloses a method in which lithium oxalate is first dissolved in anhydrous HF, and then phosphorus pentafluoride obtained by the reaction of phosphorus pentachloride and hydrogen fluoride is added to prepare lithium tetrafluorooxalate, but lithium hexafluorophosphate, which is a byproduct generated during the reaction, is difficult to completely remove, resulting in a decrease in purity, and in addition, the temperature is regulated at a desired time during the reaction, so that industrial mass production is not easy to perform.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the preparation method of the difluoro double lithium oxalate phosphate or the tetrafluoro lithium oxalate phosphate, which does not use lithium hexafluorophosphate as a raw material, so the raw material is low in price, in addition, impurities such as lithium hexafluorophosphate and the like are not generated in the reaction process, the purity of the prepared product is high, in addition, the silicon-containing auxiliary agent is not used, the whole process is simple and practical, the reaction condition is mild, the waste gas generated in the reaction is easy to treat, and the industrialized mass production is facilitated.
The aim of the invention can be achieved by the following technical scheme:
[1] the preparation method of the difluoro double lithium oxalate phosphate or the tetrafluoro lithium oxalate phosphate is characterized by comprising the following steps:
(1) Adding phosphorus pentachloride and oxalic acid into a first nonaqueous solvent, and reacting under stirring to obtain a hydrogen phosphate tricarboxylic acid solution;
(2) Introducing hydrogen fluoride into the hydrogen phosphate solution of tricarboxylic acid to perform fluoridation to obtain H [ P (C) 2 O 4 ) 3-(x/2) F x ]The solution is prepared into a liquid preparation,
wherein x=2 or 4, when x=2, H [ P (C 2 O 4 ) 2 F 2 ]When x=4, the solution gives H [ P (C 2 O 4 )F 4 ]A solution;
(3) The H [ P (C) 2 O 4 ) 3-(x/2) F x ]Adding the solution into a second nonaqueous solvent dispersion containing lithium salt, and reacting under stirring to obtain Li [ P (C) 2 O 4 ) 3-(x/2) F x ]，
Wherein x=2 or 4; when x=2, lithium difluorobis (oxalato) phosphate is obtained, and when x=4, lithium tetrafluoro (oxalato) phosphate is obtained, and the lithium salt is lithium chloride or lithium fluoride.
[2] The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to [1], wherein the molar ratio of phosphorus pentachloride, oxalic acid to lithium salt is 1: (3.01-3.50) and (1.01-1.20).
[3] The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate according to [1] or [2], characterized by comprising the steps of,
when the mole ratio of phosphorus pentachloride to hydrogen fluoride is 1 (2.05-2.20), H [ P (C) is obtained by reaction 2 O 4 ) 2 F 2 ]；
When the mole ratio of phosphorus pentachloride to hydrogen fluoride is 1 (4.05-4.20), H [ P (C) is obtained by reaction 2 O 4 )F 4 ]。
[4] The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate according to [1] or [2], characterized by comprising the steps of,
in the step (1), the first nonaqueous solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate, preferably dimethyl carbonate or ethylmethyl carbonate;
the mass of the first nonaqueous solvent is 3.5-5.0 times of the sum of the mass of the phosphorus pentachloride and the mass of the oxalic acid.
[5] The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate according to [1] or [2], characterized by comprising the steps of,
in the step (1), the reaction temperature of the phosphorus pentachloride and oxalic acid is 30-120 ℃, preferably 50-80 ℃.
[6] The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate according to [1] or [2], characterized by comprising the steps of,
in the step (2), the hydrogen fluoride is introduced into the hydrogen phosphate tricarboxylic acid solution at the temperature of 60-110 ℃ for carrying out fluorination reaction for 8-12H, and H [ P (C) is generated 2 O 4 ) 2 F 2 ]Filtering the coarse solution to eliminate insoluble impurity, cooling the filtrate to 5-15 deg.c, standing to precipitate for 5-10 hr, filtering to eliminate residual oxalic acid to obtain H [ P (C) 2 O 4 ) 3-(x/2) F x ]A solution.
[7] The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate according to [1] or [2], characterized by comprising the steps of,
in step (3), the second nonaqueous solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate, and the second nonaqueous solvent may be the same as or different from the first nonaqueous solvent;
the mass ratio of the lithium salt to the second nonaqueous solvent is 1: (5-10).
[8] The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate according to [1] or [2], characterized by comprising the steps of,
in step (3), the H [ P (C) 2 O 4 ) 3-(x/2) F x ]The reaction temperature with the lithium salt is 30 to 110 ℃, preferably 50 to 90 ℃.
[9] The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluoro (oxalato) phosphate according to [1] or [2], characterized by further comprising the following post-treatment steps after the reaction of step (3):
(4) Filtering the reaction solution in the step (3) to remove redundant lithium salt impurities, and distilling the filtrate under reduced pressure at 30-80 ℃ until the filtrate is just saturated;
(5) Cooling to 5-10 ℃, adding dichloromethane to perform crystallization, wherein the crystallization time is 3-8 h, and filtering to obtain wet solid of the difluoro lithium bisoxalato phosphate or the tetrafluoro lithium oxalato phosphate;
(6) And (3) vacuum drying the wet solid at 40-60 ℃ for 5-10 hours, heating to 80-100 ℃, and drying for 5-8 hours by utilizing nitrogen purging to obtain the difluoro lithium bisoxalato phosphate or the tetrafluoro lithium oxalato phosphate.
[10] The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate according to any one of [1] to [9], wherein the steps (1) to (3) are carried out in an inert atmosphere of nitrogen, argon or helium.
[11] A lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate, which is characterized by being produced by the process for producing a lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate as described in any one of [1] to [9 ].
Compared with the prior art, the invention has the following beneficial effects:
in the preparation method of the difluoro lithium bisoxalato phosphate or tetrafluoro lithium oxalato phosphate, stepwise feeding is adopted for reaction, phosphorus pentachloride and oxalic acid are adopted for reaction in the first step to prepare intermediate reactants, raw materials are cheap and easy to obtain, the use of lithium hexafluorophosphate is avoided, the problem that impurities are difficult to remove due to the use of lithium hexafluorophosphate is avoided, and tail gas hydrogen chloride generated by reaction can be treated through simple tail gas absorption; the second step is to introduce hydrogen fluoride gas for fluorination reaction, the hydrogen fluoride has low cost, the application in industrial production is quite mature, the safety risk is low, the operability is strong, and the fluorination efficiency is high; and thirdly, reacting the fluorinated product obtained in the second step with lithium salt to finally generate the target product of difluoro lithium bisoxalato phosphate or tetrafluoro lithium oxalato phosphate with high efficiency. The method has the advantages of simple raw materials, low price, simple and practical process, mild reaction conditions, easy treatment of waste gas generated in the reaction, less impurities in the product, high yield and purity, and contribution to industrialized mass production.
Detailed Description
In the present specification, unless otherwise specified, symbols, units, abbreviations, and terms have the following meanings. For example, when a numerical range is represented by using-or-it includes both end points, and the units are common. For example, 5 to 25% means 5% or more and 25% or less.
The present invention is described in further detail below.
The invention provides a preparation method of difluoro double oxalic acid lithium phosphate or tetrafluorooxalic acid lithium phosphate, which comprises the following steps:
(1) Adding phosphorus pentachloride and oxalic acid into a first nonaqueous solvent, and reacting under stirring to obtain a hydrogen phosphate tricarboxylic acid solution;
(2) Introducing hydrogen fluoride into the hydrogen phosphate solution of tricarboxylic acid to perform fluoridation to obtain H [ P (C) 2 O 4 ) 3-(x/2) F x ]The solution is prepared into a liquid preparation,
wherein x=2 or 4, when x=2, H [ P (C 2 O 4 ) 2 F 2 ]When x=4, the solution gives H [ P (C 2 O 4 )F 4 ]A solution;
(3) The H [ P (C) 2 O 4 ) 3-(x/2) F x ]Adding the solution into a second nonaqueous solvent dispersion containing lithium salt, and reacting under stirring to obtain Li [ P (C) 2 O 4 ) 3-(x/2) F x ]，
Wherein x=2 or 4; when x=2, lithium difluorobis (oxalato) phosphate is obtained, and when x=4, lithium tetrafluoro (oxalato) phosphate is obtained, the lithium salt being lithium chloride or lithium fluoride, preferably lithium chloride.
The reaction equations (i) to (iii) of steps (1) to (3) in the above preparation method are as follows:
PCl 5 +3H 2 C 2 O 4 →H[P(C 2 O 4 ) 3 ]+5HCl (i)
H[P(C 2 O 4 ) 3 ]+xHF→H[P(C2O4) 3-x/2 F x ]+x/2H 2 C 2 O 4 (ii)
LiY+H[P(C 2 O 4 ) 3-x/2 F x ]→HY+Li[P(C 2 O 4 ) 3-(x/2) F x ] (iii)
wherein, when x=2, the final product is difluoro-lithium bisoxalato-phosphate, and when x=4, the final product is tetrafluoro-lithium oxalato-phosphate, and Y is Cl or F.
Further, the mole ratio of the phosphorus pentachloride, the oxalic acid and the lithium salt is 1:3.01-3.50:1.01-1.20.
Preferably, the molar ratio of the phosphorus pentachloride, the oxalic acid and the lithium salt is 1: (3.01-3.5): (1.01-1.2). Regarding the addition amount of oxalic acid and lithium salt, only phosphorus pentachloride and an intermediate are required to be completely reacted, if the amount is too large, raw materials are wasted, and if the amount is too small, the reaction is incomplete, so that the yield of a final product is affected.
Further, when the molar ratio of phosphorus pentachloride to hydrogen fluoride is 1:2.05-2.20, H [ P (C) 2 O 4 ) 2 F 2 ]；
Preferably, when the mole ratio of phosphorus pentachloride to hydrogen fluoride is 1:2.05-2.2, H [ P (C) 2 O 4 ) 2 F 2 ]When the hydrogen fluoride is introduced in an amount of less than 2.05mol, incomplete fluorination is caused, and when the hydrogen fluoride is introduced in an amount of more than 2.20mol, waste of raw materials is caused;
when the mole ratio of phosphorus pentachloride to hydrogen fluoride is 1:4.05-4.20, H [ P (C) 2 O 4 )F 4 ]。
Similarly, when the molar ratio of phosphorus pentachloride to hydrogen fluoride is 1:4.05-4.2, H [ P (C) 2 O 4 )F 4 ]When the amount of hydrogen fluoride to be introduced is less than 4.05mol, incomplete fluorination is caused, impurities are easily generated, and when the amount of hydrogen fluoride to be introduced is more than 4.2mol, waste of raw materials is caused.
Further, in step (1), the first nonaqueous solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate, preferably dimethyl carbonate or ethylmethyl carbonate;
the mass of the first nonaqueous solvent is 3.5-5.0 times of the sum of the mass of the phosphorus pentachloride and the mass of the oxalic acid.
The first nonaqueous solvent and the second nonaqueous solvent to be described below used in the above reaction process are not particularly limited as long as the desired effect can be obtained, and are preferably one or two or more selected from the group consisting of cyclic carbonates and chain carbonates, preferably ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and methylethyl carbonate, more preferably one or two or more selected from the group consisting of dimethyl carbonate and methylethyl carbonate. The amount of the first nonaqueous solvent is not particularly limited as long as it can satisfactorily dissolve or disperse various reaction components to promote the synthesis reaction.
Further, in the step (1), the reaction temperature of phosphorus pentachloride and oxalic acid is 30 to 120 ℃, preferably 50 to 80 ℃. When the reaction is carried out until the tail gas absorbing bottle is not bubbling, stirring and reacting for 3-5 h at the temperature again are continued to ensure complete reaction.
Further, in the step (2), the hydrogen fluoride is introduced into the hydrogen phosphate tricarboxylic acid solution at a temperature of 60 to 110 ℃ for a fluorination reaction for 8 to 12 hours, and H [ P (C) is generated by the reaction 2 O 4 ) 2 F 2 ]Filtering the coarse solution to eliminate insoluble impurity, cooling the filtrate to 5-15 deg.c, standing to precipitate for 5-10 hr, filtering to eliminate residual oxalic acid to obtain H [ P (C) 2 O 4 ) 3-(x/2) F x ]A solution.
In the step (2), the hydrogen fluoride is introduced into the hydrogen phosphate tricarboxylic acid solution at the temperature of 60-110 ℃ for carrying out the fluorination reaction. When the reaction temperature is lower than 60 ℃, the fluorination effect is poor, and the raw material reaction is incomplete; if the temperature is higher than 110 ℃, the volatilization loss of hydrogen fluoride can be caused, and the fluorination efficiency is reduced.
Optionally, in step (2), the temperature at which the fluorination is carried out by passing hydrogen fluoride is 60 to 110 ℃, preferably 70 to 100 ℃, and the fluorination effect is best in this temperature range, and above this range, by-product fluoride is liable to be formed, and below this range, the fluorination efficiency is poor. After the hydrogen fluoride is introduced, continuing to react at the temperature for 8-12 hours to ensure that the fluorination reaction is completely carried out; then cooling to 5-15 ℃, standing and precipitating for 5-10 h, and in order to precipitate oxalic acid in the reaction liquid, filtering to remove the oxalic acid to achieve the purpose of purifying the reaction liquid. Since oxalic acid is a solid at normal temperature, purification can be performed at low temperature to precipitate out.
Control of H [ P (C) 2 O 4 ) 2 F 2 ]And H [ P (C) 2 O 4 )F 4 ]When x=2, the reaction produces H [ P (C 2 O 4 ) 2 F 2 ]When x=4, the reaction produces H [ P (C 2 O 4 )F 4 ]；
Further, in step (3), the second nonaqueous solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate, and the second nonaqueous solvent may be the same as or different from the first nonaqueous solvent;
the mass ratio of the lithium salt to the second nonaqueous solvent is 1: (5-10).
In step (3), the second nonaqueous solvent may be the same as or different from the first nonaqueous solvent of step (1), preferably, the second nonaqueous solvent is the same as the first nonaqueous solvent of step (1), and the mass ratio of the added lithium salt to the second nonaqueous solvent is 1: the nonaqueous solvent amount is (5-10) mainly for forming a slurry solution of the lithium salt during stirring.
The H [ P (C) 2 O 4 ) 3-(x/2) F x ]Adding the solution into a second nonaqueous solvent of lithium salt to react and obtain lithium salt Li [ P (C) 2 O 4 ) 3-(x/2) F x ]Wherein, when x=2, difluoro double oxalic acid lithium phosphate is generated, and when x=4, tetrafluorooxalic acid lithium phosphate is generated.
Further, in step (3), the H [ P (C) 2 O 4 ) 3-(x/2) F x ]The reaction temperature with the lithium salt is 30 to 110 ℃, preferably 50 to 90 ℃. After the reaction is finished, no bubble is generated at the tail gas absorption position, the stirring reaction is continued for 5 to 8 hours, and the reaction is finished.
Further, after the reaction of step (3) is completed, the method further comprises the following post-treatment steps:
(4) Filtering the reaction solution in the step (3) to remove redundant lithium salt impurities, and distilling the filtrate under reduced pressure at 30-80 ℃ until the filtrate is just saturated;
preferably, after the reaction is completed, impurities are removed by filtration to remove raw material impurities and insoluble materials formed, and then the obtained filtrate is distilled under reduced pressure at 30 to 80 ℃ to remove the excess solvent.
(5) Cooling to 5-10 ℃, adding dichloromethane to perform crystallization, wherein the crystallization time is 3-8 h, and filtering to obtain wet solid of the difluoro lithium bisoxalato phosphate or the tetrafluoro lithium oxalato phosphate;
after distillation under reduced pressure, stirring and cooling are carried out in an ice-water bath at a temperature of between 5 and 10 ℃, and then poor solvent methylene dichloride is added for crystallization, wherein the crystallization time is 3 to 8 hours, preferably 3 to 5 hours.
After crystallization, wet difluoro lithium bisoxalato phosphate or tetrafluoro lithium oxalato phosphate is obtained by filtration.
(6) And (3) vacuum drying the wet solid at 40-60 ℃ for 5-10 hours, heating to 80-100 ℃, and drying for 5-8 hours by utilizing nitrogen purging to obtain the difluoro lithium bisoxalato phosphate or the tetrafluoro lithium oxalato phosphate.
Preferably, regarding the drying mode of the product, vacuum drying is performed at 50 ℃ for 5-10 hours in advance, and then drying is performed under nitrogen purging for 5-8 hours, so that the dry powder of the difluoro-bis-oxalato-phosphate lithium or tetrafluoro-oxalato-phosphate lithium is obtained. The relative vacuum degree in vacuum drying is not particularly limited as long as a predetermined drying effect can be achieved, and may be from-0.01 MPa to-0.09 MPa. The purpose of the two-stage temperature drying is to prevent the product from being partially decomposed by raising the temperature too high at once.
By combining the above post-treatment steps, a lithium difluorobis (oxalato) phosphate or a lithium tetrafluoro (oxalato) phosphate having a high purity can be obtained.
Further, the steps (1) to (3) are carried out in an inert atmosphere of nitrogen or argon or helium.
Preferably, in the above preparation methods, the reaction is carried out in an inert atmosphere, preferably in nitrogen, argon, helium or the like.
The invention also provides a difluoro double oxalic acid lithium phosphate or tetrafluorooxalic acid lithium phosphate, which is prepared by the preparation method of the difluoro double oxalic acid lithium phosphate or tetrafluorooxalic acid lithium phosphate.
In the difluoro double oxalic acid lithium phosphate or tetrafluorooxalic acid lithium phosphate prepared by the preparation method, the chloride ion content is lower than 6ppm, the water content is lower than 10ppm, and the acid value is lower than 25ppm.
The raw materials or reagents used in the present invention are all purchased from market mainstream factories, and are analytically pure grade raw materials or reagents which can be conventionally obtained without any particular limitation as long as they can function as intended. The instruments and equipment such as ion chromatograph used in this example are purchased from major commercial manufacturers, and are not particularly limited as long as they can function as intended. No particular technique or condition is identified in this example, which is performed according to techniques or conditions described in the literature in this field or according to product specifications.
The raw materials used in the following examples and comparative examples are as follows:
phosphorus pentachloride, oxalic acid and lithium salt are all purchased from Alatine, the purity is over 99.8 percent, and dimethyl carbonate and methyl ethyl carbonate are purchased from Shandong Wei Zhenjingsu chemical Co.
The instruments used in the examples and comparative examples below were as follows:
ion chromatograph, model 930, available from vantolon, switzerland,
moisture tester, model 917, from vantolong, switzerland,
potentiometric titrators, model 888, from the swiss vantology,
ICP-OES, type PQ-9000, available from Yes, germany,
nuclear magnetic resonance apparatus, available from Bruker, germany,
the vacuum drying oven was purchased from Shanghai Heng under the model number DZF-6050.
Example 1
(1) Accurately weighing 30.0g (0.144 mol) phosphorus pentachloride and 39.0g (0.433 mol) oxalic acid (the mol ratio of phosphorus pentachloride to oxalic acid is 1:3.01), placing in a 500ml polytetrafluoroethylene three-mouth flask, placing the three-mouth flask in an oil bath pot, adding 277.9g dimethyl carbonate, quickly setting up a reflux device and an air guide device, preparing inert nitrogen protection, heating to 50 ℃ for reaction, introducing tail gas into sodium hydroxide aqueous solution for absorption, continuing stirring for reaction for 4 hours when no bubble is generated at the tail gas absorption part, ending the first-step reaction, enabling the solution in the flask to be slightly turbid, and reacting to generate H [ P (C) 2 O 4 ) 3 ]。
(2) Slowly raising the temperature of the reaction solution of hydrogen phosphate tricarboxylic acid to 70 deg.C, slowly introducing 5.90g (0.295 mol) of hydrogen fluoride gas (the mole ratio of phosphorus pentachloride to hydrogen fluoride is 1:2.05), and after the introduction, continuously maintaining the temperature at 70 deg.C for reaction for 8H to generate H [ P (C) 2 O 4 ) 2 F 2 ]After the reaction, the crude solution is quickly filtered to remove the generated insoluble filter residue, the obtained filtrate is introduced into a flask, and placed in an ice water bath at 10 ℃ for standing and precipitating for 5 hours, and a little oxalic acid is filtered again to obtain H [ P (C) 2 O 4 ) 2 F 2 ]A solution.
(3) 6.16g (0.1454 mol) of lithium chloride (molar ratio of phosphorus pentachloride to lithium chloride: 1:1.01) was weighed into a 500ml three-necked glass flask, and 30.80g of dimethyl carbonate was added thereto to stir the mixture, thereby obtaining H [ P (C) in the step (2) 2 O 4 ) 2 F 2 ]The solution is quickly introduced into a 500ml constant pressure dropping funnel, a reaction, reflux and tail gas absorbing device is built, the reaction is protected by nitrogen, then the temperature is slowly raised to 60 ℃, the solution is slowly dropped into the three-mouth glass flask under the stirring state, the tail gas is introduced into sodium hydroxide aqueous solution for absorption, white smoke is emitted from the tail gas absorption part, after the solution is dropped, when no bubbles are generated from the tail gas absorption part, the solution is continuously dropped into the three-mouth glass flaskAnd (3) carrying out heat preservation reaction for 6 hours at the temperature, and after the reaction is finished, generating a difluoro bis (lithium oxalate) phosphate solution.
Filtering the reaction solution of the reaction (3) to remove insoluble impurities, performing reduced pressure distillation on the obtained difluoro bis (lithium oxalate) phosphate solution at 50 ℃, and concentrating to a just saturated state. Cooling in ice water bath at 10deg.C, adding dichloromethane with the same volume as the concentrated solution, stirring for crystallization for 3 hr, and filtering to obtain wet solid of difluoro lithium bisoxalato phosphate. The wet solid was then dried in a vacuum oven at 50 ℃ for 8 hours, then warmed to 80 ℃ and purged with nitrogen at that temperature for 5 hours to give 30.7g of a white solid of lithium difluorobisoxalato phosphate powder in 84.6% yield.
Nuclear magnetic resonance NMR was performed using a nuclear magnetic resonance spectrometer with a spectrum of 19F NMR (376 MHz, DMSO-d 6) delta-59.35(s), -61.46(s), demonstrating that the product was lithium difluorobis (oxalato) phosphate.
The purity of the product was 99.93% (mol) by ion chromatography (model 930, manufactured by Swiss Wantoon), the chloride ion content was 3.1ppm by ion chromatography (model 930, manufactured by Swiss Wantoon), the moisture content was 8.9ppm by moisture tester (model 917, manufactured by Swiss Wantoon), and the acid value was 21ppm by potentiometric titrator (model 888, manufactured by Swiss Wantoon).
Examples 2 to 4
The procedure of the preparation method was substantially the same as in example 1, except that the kinds, amounts and respective condition parameters of the respective raw materials were changed as shown in tables 1 and 2, and the reaction product was lithium difluorobis (oxalato) phosphate.
Examples 5 to 6
As shown in tables 1 and 2, the preparation method was substantially the same as in example 1 except that the kinds, amounts and various condition parameters of the raw materials were changed, the molar ratio of phosphorus pentachloride to hydrogen fluoride was 1 (4.05 to 4.20), lithium tetrafluorooxalate was used as the reaction product, lithium fluoride was used as the lithium salt in example 5, lithium chloride was used as the lithium salt in example 6, and the like.
Nuclear magnetic resonance NMR was performed using a nuclear magnetic resonance spectrometer with a spectrum of 19F NMR (376 mhz, dmso-d 6) delta-56.97 (dt, j= 776.2), -73.57 (dt, j= 749.2), demonstrating that the product was lithium tetrafluorooxalate phosphate.
Comparative example 1
The procedure of example 1 was followed except that the molar ratio of phosphorus pentachloride to oxalic acid in step (1) was 1:4.0.
Comparative example 2
The procedure of example 1 was followed except that in step (2), the molar ratio of phosphorus pentachloride to hydrogen fluoride was 1:2.4.
Comparative example 3
The procedure of example 6 was followed except that in step (2), the molar ratio of phosphorus pentachloride to hydrogen fluoride was 1:4.4.
TABLE 1
TABLE 2
The parameters of the properties of the products in each case are given in table 3.
TABLE 3 Table 3
| Examples | Yield (%) | Purity (%) | Chloride ion content (ppm) | Moisture contentQuantity (ppm) | Acid value (ppm) |
| Example 1 | 84.6 | 99.93 | 5.1 | 8.9 | 21 |
| Example 2 | 89.0 | 99.96 | 3.2 | 5.9 | 19 |
| Example 3 | 86.1 | 99.95 | 4.2 | 6.4 | 18 |
| Example 4 | 87.3 | 99.92 | 4.5 | 8.5 | 22 |
| Example 5 | 85.6 | 99.93 | 3.6 | 7.8 | 16 |
| Example 6 | 88.7 | 99.95 | 3.1 | 5.4 | 19 |
| Comparative example 1 | 84.8 | 99.62 | 3.8 | 9.2 | 56 |
| Comparative example 2 | 80.8 | 92.48 | 4.9 | 8.8 | 25 |
| Comparative example 3 | 82.5 | 94.37 | 3.5 | 6.3 | 46 |
As shown in Table 3, the analysis of the property parameters of examples 1 to 6 and comparative examples 1 to 3 revealed that the yields and purities of examples 1 to 6 were higher than those of comparative examples, and the acid numbers were lower than those of comparative examples. The invention uses phosphorus pentachloride, oxalic acid, hydrogen fluoride and lithium salt as raw materials, and precisely controls the reaction molar ratio of each component and the reaction conditions of each step, thereby finally successfully preparing difluoro-lithium bisoxalato phosphate or tetrafluoro-lithium oxalato phosphate. According to the preparation method, the feeding amount of hydrogen fluoride is freely controlled, so that the difluoro lithium bisoxalato phosphate or tetrafluoro lithium oxalato phosphate is selectively prepared, the production flexibility is high, and the investment of production equipment is reduced. The preparation method has excellent yield and purity, the chloride ion content is lower than 6ppm, the water content is lower than 10ppm, and the acid value is lower than 25ppm. The preparation method does not use conventional lithium hexafluorophosphate as a raw material, so that impurities such as lithium difluorophosphate are not generated, the purity is greatly improved, and the preparation method is different from other company products and can meet the high requirement of the current market on the purity. The method has the advantages of simple raw materials, low price, simple and practical process, mild reaction conditions, easy treatment of waste gas generated in the reaction, less impurities in the product, high yield and purity, and contribution to industrialized mass production.
In comparative example 1, in the step (1), the molar ratio of phosphorus pentachloride to oxalic acid is 1:4.0, and the addition amount of oxalic acid is excessive and exceeds the preferred range of the invention, so that the acid value of the product is high, and the application of the product in electrolyte is not facilitated.
In comparative example 2, in the step (2), the molar ratio of phosphorus pentachloride to hydrogen fluoride is 1:2.4, and the addition amount of hydrogen fluoride is beyond the preferred range when preparing lithium difluorobis (oxalato) phosphate according to the invention, so that impurities such as lithium tetrafluoro (oxalato) phosphate are generated in the product, and the yield and purity of the product are greatly reduced.
In comparative example 3, in the step (2), the molar ratio of phosphorus pentachloride to hydrogen fluoride is 1:4.4, and the addition amount of hydrogen fluoride is out of the preferred range when lithium tetrafluorooxalate phosphate is prepared according to the present invention, resulting in the formation of impurities such as lithium hexafluorophosphate in the product, the yield and purity of the product are greatly reduced, and the acid value is increased.
The foregoing is merely a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and the present invention is described by using the specific examples, which are only for aiding in understanding the present invention, and are not limited thereto. Several simple deductions, modifications or substitutions may also be made by a person skilled in the art according to the idea of the invention. Such deductions, modifications or alternatives fall within the scope of the claims of the present invention.
Claims (10)
1. The preparation method of the difluoro double lithium oxalate phosphate or the tetrafluoro lithium oxalate phosphate is characterized by comprising the following steps:
(1) Adding phosphorus pentachloride and oxalic acid into a first nonaqueous solvent, and reacting under stirring to obtain a hydrogen phosphate tricarboxylic acid solution;
(2) Introducing hydrogen fluoride into the hydrogen phosphate solution of tricarboxylic acid at 60-110 deg.c for fluoridation to obtain H [ P (C) 2 O 4 ) 3-(x/2) F x ]The solution is prepared into a liquid preparation,
wherein x=2 or 4, when x=2, H [ P (C 2 O 4 ) 2 F 2 ]When x=4, the solution gives H [ P (C 2 O 4 )F 4 ]A solution;
(3) The H [ P (C) 2 O 4 ) 3-(x/2) F x ]Adding the solution to a second nonaqueous solvent dispersion containing a lithium salt, and allowing the reaction to proceed with stirring, said H [ P (C) 2 O 4 ) 3-(x/2) F x ]The reaction temperature with lithium salt is 30-110 deg.c to obtain Li [ P (C) 2 O 4 ) 3-(x/2) F x ]，
Wherein x=2 or 4; when x=2, obtaining difluoro bis (lithium oxalate) phosphate, and when x=4, obtaining tetrafluoro (lithium oxalate) phosphate, wherein the lithium salt is lithium chloride or lithium fluoride;
the second nonaqueous solvent is selected from one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate, and can be the same as or different from the first nonaqueous solvent; the mass ratio of the lithium salt to the second nonaqueous solvent is 1: (5-10);
when the mole ratio of phosphorus pentachloride to hydrogen fluoride is 1 (2.05-2.20), H [ P (C) is obtained by reaction 2 O 4 ) 2 F 2 ]；
When the mole ratio of phosphorus pentachloride to hydrogen fluoride is 1 (4.05-4.20), H [ P (C) is obtained by reaction 2 O 4 )F 4 ]。
2. The method for preparing difluoro-lithium bis (oxalato) phosphate or tetrafluoro-lithium oxalato phosphate according to claim 1, wherein the molar ratio of phosphorus pentachloride, oxalic acid to lithium salt is 1: (3.01-3.50) and (1.01-1.20).
3. The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate according to claim 1 or 2, characterized in that,
in the step (1), the first nonaqueous solvent is selected from one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate;
the mass of the first nonaqueous solvent is 3.5-5.0 times of the sum of the mass of the phosphorus pentachloride and the mass of the oxalic acid.
4. The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to claim 3, wherein the first nonaqueous solvent is dimethyl carbonate or ethyl methyl carbonate.
5. The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate according to claim 1 or 2, characterized in that,
in the step (1), the reaction temperature of the phosphorus pentachloride and oxalic acid is 30-120 ℃.
6. The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to claim 5, wherein in step (1), the reaction temperature of phosphorus pentachloride and oxalic acid is 50 to 80 ℃.
7. The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate according to claim 1 or 2, characterized in that,
in the step (2), the hydrogen fluoride is introduced into the hydrogen phosphate tricarboxylic acid solution at the temperature of 60-110 ℃ for carrying out fluorination reaction for 8-12 h, and the reaction is carried outH [ P (C) should be generated 2 O 4 ) 2 F 2 ]Filtering the coarse solution to eliminate insoluble impurity, cooling the filtrate to 5-15 deg.c, standing to precipitate for 5-10 hr, filtering to eliminate residual oxalic acid to obtain H [ P (C) 2 O 4 ) 3-(x/2) F x ]A solution.
8. The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate according to claim 1 or 2, characterized in that,
in step (3), the H [ P (C) 2 O 4 ) 3-(x/2) F x ]The reaction temperature with lithium salt is 50-90 ℃.
9. The method for producing a lithium difluorobis (oxalato) phosphate or a lithium tetrafluoro (oxalato) phosphate according to claim 1 or 2, further comprising the following post-treatment steps after the reaction of step (3) is completed:
(4) Filtering the reaction solution in the step (3) to remove redundant lithium salt impurities, and distilling the filtrate under reduced pressure at 30-80 ℃ until the filtrate is just saturated;
(5) Cooling to 5-10 ℃, adding dichloromethane to perform crystallization, wherein the crystallization time is 3-8 h, and filtering to obtain wet solid of the difluoro lithium bisoxalato phosphate or the tetrafluoro lithium oxalato phosphate;
(6) And (3) vacuum drying the wet solid at 40-60 ℃ for 5-10 hours, heating to 80-100 ℃, and drying for 5-8 hours by utilizing nitrogen purging to obtain the difluoro lithium bisoxalato phosphate or the tetrafluoro lithium oxalato phosphate.
10. The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to claim 1 or 2, wherein the steps (1) to (3) are carried out in an inert atmosphere of nitrogen or argon or helium.
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