CN113527363A - Preparation method of lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate - Google Patents
Preparation method of lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate Download PDFInfo
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- CN113527363A CN113527363A CN202110540184.0A CN202110540184A CN113527363A CN 113527363 A CN113527363 A CN 113527363A CN 202110540184 A CN202110540184 A CN 202110540184A CN 113527363 A CN113527363 A CN 113527363A
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- lithium
- phosphate
- oxalato
- difluorobis
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 116
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 116
- 238000002360 preparation method Methods 0.000 title claims abstract description 25
- 229910019142 PO4 Inorganic materials 0.000 title claims description 105
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 title claims description 105
- 239000010452 phosphate Substances 0.000 title claims description 105
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims abstract description 93
- 238000006243 chemical reaction Methods 0.000 claims abstract description 65
- 239000000243 solution Substances 0.000 claims abstract description 45
- UHZYTMXLRWXGPK-UHFFFAOYSA-N phosphorus pentachloride Chemical compound ClP(Cl)(Cl)(Cl)Cl UHZYTMXLRWXGPK-UHFFFAOYSA-N 0.000 claims abstract description 41
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 36
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims abstract description 36
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 31
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 31
- 235000006408 oxalic acid Nutrition 0.000 claims abstract description 31
- 239000003125 aqueous solvent Substances 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims abstract description 21
- 238000003682 fluorination reaction Methods 0.000 claims abstract description 19
- 239000012535 impurity Substances 0.000 claims abstract description 19
- 238000003756 stirring Methods 0.000 claims abstract description 15
- 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 claims abstract description 6
- NBIIXXVUZAFLBC-UHFFFAOYSA-L Phosphate ion(2-) Chemical compound OP([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-L 0.000 claims abstract description 6
- 239000004135 Bone phosphate Substances 0.000 claims abstract description 5
- 239000006185 dispersion Substances 0.000 claims abstract description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 21
- 238000004519 manufacturing process Methods 0.000 claims description 21
- 239000002904 solvent Substances 0.000 claims description 20
- 238000001914 filtration Methods 0.000 claims description 17
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 15
- 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
- 238000002425 crystallisation Methods 0.000 claims description 10
- 230000008025 crystallization Effects 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims description 10
- 239000007787 solid Substances 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 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
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 7
- 229910052786 argon Inorganic materials 0.000 claims description 4
- 239000012045 crude solution Substances 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
- 238000001556 precipitation Methods 0.000 claims description 4
- 238000010926 purge Methods 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 3
- ZYMJSAWYDBRZIC-UHFFFAOYSA-N oxalic acid phosphoric acid Chemical compound OP(O)(O)=O.OC(=O)C(O)=O.OC(=O)C(O)=O.OC(=O)C(O)=O ZYMJSAWYDBRZIC-UHFFFAOYSA-N 0.000 claims description 3
- 229920006395 saturated elastomer Polymers 0.000 claims description 3
- 239000002994 raw material Substances 0.000 abstract description 21
- -1 hydrogen tris (oxalate) phosphate Chemical class 0.000 abstract description 14
- MRDKYAYDMCRFIT-UHFFFAOYSA-N oxalic acid;phosphoric acid Chemical compound OP(O)(O)=O.OC(=O)C(O)=O MRDKYAYDMCRFIT-UHFFFAOYSA-N 0.000 abstract description 11
- 239000001257 hydrogen Substances 0.000 abstract description 4
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 4
- 238000011031 large-scale manufacturing process Methods 0.000 abstract description 3
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 abstract description 3
- 239000002912 waste gas Substances 0.000 abstract description 3
- 239000007788 liquid Substances 0.000 abstract 1
- 239000000047 product Substances 0.000 description 21
- 239000007789 gas Substances 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 14
- 238000010521 absorption reaction Methods 0.000 description 8
- 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
- 238000005481 NMR spectroscopy Methods 0.000 description 5
- IAZDPXIOMUYVGZ-WFGJKAKNSA-N Dimethyl sulfoxide Chemical compound [2H]C([2H])([2H])S(=O)C([2H])([2H])[2H] IAZDPXIOMUYVGZ-WFGJKAKNSA-N 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 239000000654 additive Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 4
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 230000000996 additive effect Effects 0.000 description 3
- 239000012467 final product Substances 0.000 description 3
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 3
- 239000005457 ice water Substances 0.000 description 3
- 238000001291 vacuum drying Methods 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
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000004821 distillation Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000000203 mixture Substances 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
- 238000004321 preservation Methods 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- 239000005049 silicon tetrachloride Substances 0.000 description 2
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 229910004014 SiF4 Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 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
- 150000005678 chain carbonates Chemical class 0.000 description 1
- 150000005676 cyclic carbonates Chemical class 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- YNQRWVCLAIUHHI-UHFFFAOYSA-L dilithium;oxalate Chemical compound [Li+].[Li+].[O-]C(=O)C([O-])=O YNQRWVCLAIUHHI-UHFFFAOYSA-L 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000002349 favourable 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
- 239000000463 material 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
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 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
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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 lithium difluorobis (oxalate) phosphate or lithium tetrafluorooxalate phosphate, which comprises the steps of adding phosphorus pentachloride and oxalic acid into a first non-aqueous solvent, and reacting under stirring to obtain a hydrogen tris (oxalate) phosphate solution; introducing hydrogen fluoride into the hydrogen phosphate tribasic solution to perform fluorination reaction; and adding the fluorinated solution into a second non-aqueous solvent dispersion liquid containing lithium salt, and reacting under stirring to obtain the lithium difluorobis (oxalate) phosphate or the lithium tetrafluorooxalate phosphate. The preparation method of the invention does not use the conventional lithium hexafluorophosphate as a raw material, so that impurities such as lithium difluorophosphate and the like 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 industrial large-scale production.
Description
Technical Field
The invention relates to the field of additives for non-aqueous electrolyte of lithium ion batteries, lithium ion capacitors and the like, in particular to a preparation method of lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato 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 positive electrode and the negative electrode, and is an important factor related to the performance of the battery. The additive is an important component in the lithium ion battery electrolyte except for electrolyte and organic solvent, and the proper additive can play an important role in enhancing the performance of the lithium battery. Lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate is mainly applied to non-aqueous electrolyte of lithium ion batteries, lithium ion capacitors and the like. After the additive is added, the thermal stability and the hydrolytic stability of the electrolyte can be improved, the two properties are kept good even after the battery is aged, a more stable solid electrolyte interface film structure can be formed on the surface of a positive electrode material, and the cyclic charge and discharge performance of the battery is improved.
At present, a plurality of methods for preparing lithium difluorobis (oxalato) phosphate and lithium tetrafluoro (oxalato) phosphate are disclosed, most of the methods adopt lithium hexafluorophosphate and silicon tetrachloride and other auxiliaries as main raw materials for reaction, but in the reaction process, lithium hexafluorophosphate is easy to partially decompose to generate phosphorus pentafluoride or react with other oxygen-containing substances to generate lithium difluorophosphate, impurity removal is difficult, and meanwhile, in the reaction process using silicon auxiliaries, a large amount of silicon tetrafluoride and hydrogen chloride gas are generated, so that the silicon tetrafluoride and the hydrogen chloride gas are difficult to separate and utilize, the safety risk is high, and great difficulty is brought to industrialization.
Patent application CN102216311B discloses a method for preparing lithium difluorobis (oxalato) phosphate using oxalic acid, lithium hexafluorophosphate and silicon tetrachloride as raw materials, but this method generates a large amount of highly corrosive acidic gases HCl and SiF4The method has high requirements on equipment, is difficult to separate from the product, is difficult to control the chloride ion content and the acid value in the product, and has hidden danger and risk in safety and reliability.
Patent CN105218348B discloses a method, wherein lithium oxalate is dissolved in anhydrous HF, and then phosphorus pentafluoride obtained by reacting phosphorus pentachloride with hydrogen fluoride is added to prepare lithium tetrafluoro oxalate phosphate, however, a by-product lithium hexafluorophosphate is generated in the reaction process, and is difficult to be completely removed, which results in a decrease in purity, and in addition, the temperature is required to be adjusted at any time during the reaction, which makes industrial mass production difficult.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a preparation method of lithium difluorobis (oxalate) phosphate or lithium tetrafluorooxalate phosphate, which does not use lithium hexafluorophosphate as a raw material, so that the raw material is low in price, in addition, impurities such as lithium hexafluorophosphate and the like are not generated in the reaction process, and the prepared product is high in purity.
The purpose of the invention can be realized by the following technical scheme:
[1] a preparation method of lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalate phosphate is characterized by comprising the following steps:
(1) adding phosphorus pentachloride and oxalic acid into a first non-aqueous solvent, and reacting under stirring to obtain a tri-oxalic acid hydrogen phosphate solution;
(2) introducing hydrogen fluoride into the hydrogen phosphate tribasic solution for fluorination reaction to obtain H [ P (C)2O4)3-(x/2)Fx]The solution is prepared by mixing a solvent and a solvent,
wherein x is 2 or 4, when x is 2, H [ P (C) is obtained2O4)2F2]Solution, when x is 4, gives H [ P (C)2O4)F4]A solution;
(3) reacting said H [ P (C)2O4)3-(x/2)Fx]Adding the solution into a second non-aqueous solvent dispersion containing lithium salt, and reacting under stirring to obtain Li [ P (C)2O4)3-(x/2)Fx]，
Wherein x is 2 or 4; when x is 2, lithium difluorobis (oxalato) phosphate is obtained, and when x is 4, lithium tetrafluorooxalato phosphate is obtained, and the lithium salt is lithium chloride or lithium fluoride.
[2] The preparation method of lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to [1], characterized in that the molar ratio of the phosphorus pentachloride, the oxalic acid and the lithium salt is 1: (3.01-3.50) and (1.01-1.20).
[3] The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to [1] or [2], which comprises,
when the molar ratio of the phosphorus pentachloride to the hydrogen fluoride is 1 (2.05-2.20), H [ P (C) is obtained by reaction2O4)2F2]；
When the molar ratio of the phosphorus pentachloride to the hydrogen fluoride is 1 (4.05-4.20), H [ P (C) is obtained by reaction2O4)F4]。
[4] The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to [1] or [2], which comprises,
in the step (1), the first non-aqueous solvent comprises one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, preferably dimethyl carbonate or ethyl methyl carbonate;
the mass of the first non-aqueous 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 lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to [1] or [2], which comprises,
in the step (1), the reaction temperature of the phosphorus pentachloride and the oxalic acid is 30-120 ℃, and preferably 50-80 ℃.
[6] The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to [1] or [2], which comprises,
in the step (2), introducing the hydrogen fluoride into the hydrogen tris-oxalate solution at the temperature of 60-110 ℃ to perform fluorination reaction for 8-12H to generate H [ P (C)2O4)2F2]Filtering the crude solution to remove insoluble impurities, cooling the filtrate to 5-15 ℃, standing for precipitation for 5-10H, and filtering to remove residual oxalic acid to obtain H [ P (C)2O4)3-(x/2)Fx]And (3) solution.
[7] The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to [1] or [2], which comprises,
in the step (3), the second non-aqueous solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, and the second non-aqueous solvent may be the same as or different from the first non-aqueous solvent;
the mass ratio of the lithium salt to the second nonaqueous solvent is 1: (5-10).
[8] The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to [1] or [2], which comprises,
in step (3), the H [ P (C) ]2O4)3-(x/2)Fx]The reaction temperature of the lithium salt is 30-110 ℃, and preferably 50-90 ℃.
[9] The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to [1] or [2], characterized by further comprising, after the reaction of the step (3), the following post-treatment step:
(4) filtering the reaction solution obtained in the step (3), removing redundant lithium salt impurities, and distilling the filtrate at the temperature of 30-80 ℃ under reduced pressure until the filtrate is just saturated;
(5) cooling to 5-10 ℃, adding dichloromethane for crystallization, wherein the crystallization time is 3-8 h, and filtering to obtain the lithium difluorobis (oxalato) phosphate or the wet solid of the lithium tetrafluoro (oxalato) phosphate;
(6) and (3) drying the wet solid at 40-60 ℃ for 5-10 h in vacuum, then heating to 80-100 ℃, and drying for 5-8 h by nitrogen purging to obtain the lithium difluorobis (oxalato) phosphate or the lithium tetrafluoro (oxalato) phosphate.
[10] The method for producing lithium difluorobis (oxalato) phosphate or 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 or argon or helium.
[11] A lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate characterized by being produced by the process for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate 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 lithium difluorobis (oxalato) phosphate or the lithium tetrafluoro (oxalato) phosphate, the materials are fed step by step for reaction, phosphorus pentachloride and oxalic acid are adopted for reaction in the first step to prepare an intermediate reactant, the 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 hydrogen chloride in the tail gas generated by the reaction can be treated by simple tail gas absorption; secondly, hydrogen fluoride gas is introduced to carry out fluorination reaction, the cost of the hydrogen fluoride is low, the application in industrial production is mature, the safety risk is low, the operability is strong, and the fluorination efficiency is high; and thirdly, reacting the fluorination product obtained in the second step with a lithium salt to finally generate the target product lithium difluorobis (oxalate) phosphate or lithium tetrafluorooxalate 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 industrial large-scale production.
Detailed Description
In the present specification, unless otherwise specified, the following meanings are given to the symbols, units, abbreviations and terms. For example, when numerical ranges are expressed using "or", they include both endpoints, 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 lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate, which comprises the following steps:
(1) adding phosphorus pentachloride and oxalic acid into a first non-aqueous solvent, and reacting under stirring to obtain a tri-oxalic acid hydrogen phosphate solution;
(2) introducing hydrogen fluoride into the hydrogen phosphate tribasic solution for fluorination reaction to obtain H [ P (C)2O4)3-(x/2)Fx]The solution is prepared by mixing a solvent and a solvent,
wherein x is 2 or 4, when x is 2, H [ P (C) is obtained2O4)2F2]Solution, when x is 4, gives H [ P (C)2O4)F4]A solution;
(3) reacting said H [ P (C)2O4)3-(x/2)Fx]Adding the solution into a second non-aqueous solvent dispersion containing lithium salt, and reacting under stirring to obtain Li [ P (C)2O4)3-(x/2)Fx]，
Wherein x is 2 or 4; when x is 2, lithium difluorobis (oxalato) phosphate is obtained, and when x is 4, lithium tetrafluorooxalato phosphate is obtained, and the lithium salt is lithium chloride or lithium fluoride, preferably lithium chloride.
The reaction equations (i) to (iii) of steps (1) to (3) in the above production method are as follows:
PCl5+3H2C2O4→H[P(C2O4)3]+5HCl (i)
H[P(C2O4)3]+xHF→H[P(C2O4)3-x/2Fx]+x/2H2C2O4 (ii)
LiY+H[P(C2O4)3-x/2Fx]→HY+Li[P(C2O4)3-(x/2)Fx] (iii)
when x is 2, the final product is lithium difluorobis (oxalato) phosphate, when x is 4, the final product is lithium tetrafluoro (oxalato) phosphate, and Y is Cl or F.
Furthermore, the molar ratio of the phosphorus pentachloride to the oxalic acid to the lithium salt is 1 to (3.01-3.50) to (1.01-1.20).
Preferably, the molar ratio of the phosphorus pentachloride to the oxalic acid to 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 the intermediate are required to be completely reacted, too much phosphorus pentachloride and the intermediate cause raw material waste, and too little phosphorus pentachloride and the intermediate cause incomplete reaction, which affects the yield of the final product.
Further, when the molar ratio of the phosphorus pentachloride to the hydrogen fluoride is 1 to (2.05-2.20), H [ P (C) is obtained by reaction2O4)2F2]；
PreferablyWhen the molar ratio of the phosphorus pentachloride to the hydrogen fluoride is 1: 2.05-2.2, H [ P (C) is generated by reaction2O4)2F2]When the introduction amount of the hydrogen fluoride is less than 2.05mol, incomplete fluorination is caused, and when the introduction amount is more than 2.20mol, waste of raw materials is caused;
when the molar ratio of the phosphorus pentachloride to the hydrogen fluoride is 1: 4.05-4.20, H [ P (C) is obtained by reaction2O4)F4]。
Similarly, when the molar ratio of phosphorus pentachloride to hydrogen fluoride is 1: (4.05-4.2), H [ P (C) is generated2O4)F4]When the amount of hydrogen fluoride introduced is less than 4.05mol, the fluorination tends to be incomplete and impurities tend to be generated, and when the amount is more than 4.2mol, the raw material tends to be wasted.
Further, in the step (1), the first non-aqueous solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, preferably dimethyl carbonate or ethyl methyl carbonate;
the mass of the first non-aqueous solvent is 3.5-5.0 times of the sum of the mass of the phosphorus pentachloride and the mass of the oxalic acid.
Preferably, the first nonaqueous solvent and the second nonaqueous solvent used in the above reaction process are not particularly limited as long as the desired effect can be achieved, and are selected from cyclic carbonates and chain carbonates, preferably one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and more preferably one or more of dimethyl carbonate and ethyl methyl carbonate. The amount of the first nonaqueous solvent is not particularly limited as long as it can dissolve or disperse various reaction components well to promote the synthesis reaction.
Further, in the step (1), the reaction temperature of the phosphorus pentachloride and the oxalic acid is 30-120 ℃, and preferably 50-80 ℃. And (4) when the reaction is carried out until the tail gas absorption bottle does not bubble, continuing stirring and reacting for 3-5 hours at the temperature again to ensure complete reaction.
Further, in the step (2), at room temperatureIntroducing the hydrogen fluoride into the hydrogen tris-oxalate solution at the temperature of 60-110 ℃ to perform fluorination reaction for 8-12H to generate H [ P (C)2O4)2F2]Filtering the crude solution to remove insoluble impurities, cooling the filtrate to 5-15 ℃, standing for precipitation for 5-10H, and filtering to remove residual oxalic acid to obtain H [ P (C)2O4)3-(x/2)Fx]And (3) solution.
And (2) introducing the hydrogen fluoride into the hydrogen trisoxalato phosphate solution at the temperature of 60-110 ℃ to perform 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 temperature is too high, which causes volatilization loss of hydrogen fluoride and reduces fluorination efficiency.
Optionally, in the step (2), the temperature for fluorination by introducing hydrogen fluoride is 60 to 110 ℃, preferably 70 to 100 ℃, and the fluorination effect is the best within the temperature range, above which by-product fluoride is easily generated, and below which the fluorination efficiency is poor. After the introduction of the hydrogen fluoride is finished, continuously reacting for 8-12 h at the temperature to ensure that the fluorination reaction is completely carried out; and then cooling to 5-15 ℃, standing and precipitating for 5-10 h, wherein in order to separate out oxalic acid existing in the reaction solution, the purpose of purifying the reaction solution is achieved by filtering and removing the oxalic acid. Since oxalic acid is solid at ordinary temperature, it can be precipitated by purification at low temperature.
Controlling the amount of Hp (C) by the amount of hydrogen fluoride fed2O4)2F2]And H [ P (C)2O4)F4]When x is 2, H [ P (C) is produced2O4)2F2]When x is 4, the reaction produces H [ P (C)2O4)F4]；
Further, in the step (3), the second non-aqueous solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, and the second non-aqueous solvent may be the same as or different from the first non-aqueous solvent;
the mass ratio of the lithium salt to the second nonaqueous solvent is 1: (5-10).
In the step (3), the second nonaqueous solvent may be the same as or different from the first nonaqueous solvent in the step (1), and preferably, the second nonaqueous solvent is the same as the first nonaqueous solvent in the step (1), and the mass ratio of the lithium salt to the second nonaqueous solvent is 1: (5-10), the amount of the nonaqueous solvent is mainly to form a slurry solution of the lithium salt during stirring.
Reacting said H [ P (C) ]2O4)3-(x/2)Fx]Adding the solution into a second non-aqueous solvent of lithium salt for reaction to obtain lithium salt Li [ P (C)2O4)3-(x/2)Fx]When x is 2, lithium difluorobis (oxalato) phosphate is produced, and when x is 4, lithium tetrafluorooxalato phosphate is produced.
Further, in the step (3), the H [ P (C)2O4)3-(x/2)Fx]The reaction temperature of the lithium salt is 30-110 ℃, and preferably 50-90 ℃. And after the reaction is finished, continuing stirring for reacting for 5-8 hours until no bubbles are generated at the tail gas absorption position, and finishing the reaction.
Further, after the reaction in the step (3) is finished, the method further comprises the following post-treatment steps:
(4) filtering the reaction solution obtained in the step (3), removing redundant lithium salt impurities, and distilling the filtrate at the temperature of 30-80 ℃ under reduced pressure until the filtrate is just saturated;
preferably, after the reaction is completed, impurities are removed by filtration to remove raw material impurities and generated insoluble substances, and then the obtained filtrate is subjected to reduced pressure distillation at 30 to 80 ℃ to remove excess solvent.
(5) Cooling to 5-10 ℃, adding dichloromethane for crystallization, wherein the crystallization time is 3-8 h, and filtering to obtain the lithium difluorobis (oxalato) phosphate or the wet solid of the lithium tetrafluoro (oxalato) phosphate;
and after reduced pressure distillation, stirring and cooling the mixture in an ice water bath at the temperature of 5-10 ℃, and then adding a poor solvent dichloromethane for crystallization, wherein the crystallization time is 3-8 h, preferably 3-5 h.
And after crystallization, filtering to obtain wet lithium difluorobis (oxalato) phosphate or lithium tetrafluoro (oxalato) phosphate.
(6) And (3) drying the wet solid at 40-60 ℃ for 5-10 h in vacuum, then heating to 80-100 ℃, and drying for 5-8 h by nitrogen purging to obtain the lithium difluorobis (oxalato) phosphate or the lithium tetrafluoro (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 for 5-8 hours under nitrogen purging, so that the dry powder of lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate can be obtained. The relative degree of vacuum in the vacuum drying is not particularly limited as long as a predetermined drying effect can be obtained, and may be from-0.01 MPa to-0.09 MPa. The purpose of the two-stage temperature drying is to prevent the temperature from rising too high at a time, resulting in partial decomposition of the product.
By combining the post-treatment steps described above, lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate having a high purity can be obtained.
Further, the steps (1) to (3) are performed 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, and the like.
The invention also provides lithium difluorobis (oxalato) phosphate or lithium tetrafluoro (oxalato) phosphate, which is prepared by the preparation method of the lithium difluorobis (oxalato) phosphate or the lithium tetrafluoro (oxalato) phosphate.
In the lithium difluorobis (oxalato) phosphate or lithium tetrafluoro (oxalato) phosphate prepared by the preparation method, the content of chloride ions is lower than 6ppm, the content of water is lower than 10ppm, and the acid value is lower than 25 ppm.
The raw materials or reagents used in the present invention are purchased from mainstream manufacturers in the market, and those who do not indicate manufacturers or concentrations are all analytical pure grade raw materials or reagents that can be obtained conventionally, and are not particularly limited as long as they can perform the intended function. The ion chromatograph and other instruments used in the present embodiment are not particularly limited as long as they can perform the intended function, and are commercially available from a main market manufacturer. The specific techniques or conditions not specified in this example were performed according to the techniques or conditions described in the literature in the art or according to the product specification.
The raw materials used in the following examples, comparative examples are as follows:
phosphorus pentachloride, oxalic acid and lithium salt are all purchased from alatin, the purity is over 99.8 percent, and dimethyl carbonate and methyl ethyl carbonate are purchased from Shandong Wensheng chemical Co.
The apparatus used in the following examples, comparative examples is as follows:
ion chromatograph, model 930, available from warong, switzerland,
moisture tester, model 917, from Wantong, Switzerland,
potentiometric titrators, model 888, available from warrion, switzerland,
ICP-OES, model PQ-9000, available from Jena, Germany,
NMR, from Bruker, Germany,
the vacuum drying oven is purchased from Shanghai Yiheng, and has model number of DZF-6050.
Example 1
(1) Accurately weighing 30.0g (0.144mol) of phosphorus pentachloride and 39.0g (0.433mol) of oxalic acid (the molar ratio of the phosphorus pentachloride to the oxalic acid is 1:3.01), placing the mixture into a 500ml polytetrafluoroethylene three-neck flask, placing the three-neck flask into an oil bath pan, adding 277.9g of dimethyl carbonate, quickly building a reflux device and an air guide device, carrying out inert nitrogen protection, heating to 50 ℃ for reaction, introducing tail gas into a sodium hydroxide aqueous solution for absorption, continuing stirring for reaction for 4 hours when no bubbles are generated at the tail gas absorption position, finishing the first-step reaction, wherein the solution in the flask is in a micro-turbid state, and generating H [ P (C) (H is C) through reaction2O4)3]。
(2) Slowly raising the temperature of the hydrogen phosphate tribasic reaction solution to 70 ℃, then slowly introducing 5.90g (0.295mol) of hydrogen fluoride gas (the molar ratio of phosphorus pentachloride to hydrogen fluoride is 1: 2.05), after the introduction, continuing the heat preservation reaction at 70 ℃ for 8H to generate H [ P (C)2O4)2F2]The crude solution is quickly filtered after the reaction is finished, the generated insoluble filter residue is removed, the obtained filtrate is introduced into a flask,standing in ice water bath at 10 deg.C for precipitation for 5 hr, filtering again to remove a little oxalic acid to obtain H [ P (C)2O4)2F2]And (3) solution.
(3) 6.16g (0.1454mol) of lithium chloride (molar ratio of phosphorus pentachloride to lithium chloride: 1.01) was weighed in a 500ml three-necked glass flask, 30.80g of dimethyl carbonate was added thereto and stirred to obtain H [ P (C) obtained in step (2)2O4)2F2]The solution is quickly led into a 500ml constant-pressure dropping funnel, a reaction, reflux and tail gas absorption device is well built, nitrogen protection is carried out on the reaction, then the temperature is slowly raised to 60 ℃, the solution is slowly dropped into the three-mouth glass flask under the stirring state, tail gas is led into the sodium hydroxide aqueous solution to be absorbed, white smoke is emitted from the tail gas absorption position, after the solution is dropped, when bubbles are not generated at the tail gas absorption position any more, the heat preservation reaction is continuously carried out for 6 hours at the temperature, the reaction is finished, and a lithium difluorobis (oxalato) phosphate solution is generated.
The reaction solution of the reaction (3) was filtered to remove insoluble impurities, and the obtained lithium difluorobis (oxalato) phosphate solution was distilled under reduced pressure at 50 ℃ and concentrated to a state of just saturation. Cooling in 10 deg.C ice water bath, adding dichloromethane with the same volume as the concentrated solution, stirring for crystallization for 3 hr, and filtering to obtain wet lithium difluorobis (oxalate) phosphate solid. Then, the wet solid was dried in a vacuum oven at 50 ℃ for 8 hours, then warmed to 80 ℃ and purged with nitrogen gas at that temperature for 5 hours to obtain 30.7g of lithium difluorobis (oxalato) phosphate powder as a white solid with a yield of 84.6%.
NMR detection by a NMR spectrometer showed 19F NMR (376MHz, DMSO-d6) delta-59.35(s) and-61.46(s), and the product was lithium difluorobis (oxalato) phosphate.
The purity of the product was 99.93% (mol) as measured by an ion chromatograph (model 930, manufactured by Switzerland), the chloride ion content was 3.1ppm as measured by an ion chromatograph (model 930, manufactured by Switzerland), the moisture content was 8.9ppm as measured by a moisture meter (model 917, manufactured by Switzerland), and the acid value was 21ppm as measured by a potentiometric titrator (model 888, manufactured by Switzerland).
Examples 2 to 4
The procedure of the preparation method was substantially the same as in example 1 except that the kind and amount of each raw material and the parameters of each condition were changed as shown in tables 1 and 2, and the reaction product was lithium difluorobis (oxalato) phosphate as well.
Examples 5 to 6
As shown in tables 1 and 2, the preparation method is basically the same as that of example 1 except that the molar ratio of phosphorus pentachloride to hydrogen fluoride is 1 (4.05-4.20), the reaction product is lithium tetrafluoro oxalate phosphate, and the lithium salt is lithium fluoride for the lithium salt of example 5 and lithium chloride for the lithium salt of example 6, and the types and the amounts of the raw materials and the condition parameters are changed.
NMR detection using a NMR spectrometer showed 19F NMR (376MHz, DMSO-d6) δ -56.97(dt, J-776.2), -73.57(dt, J-749.2), which confirmed that the product was lithium tetrafluoro oxalate phosphate.
Comparative example 1
The procedure of the preparation method is substantially the same as in example 1 except that the molar ratio of phosphorus pentachloride to oxalic acid in step (1) is 1: 4.0.
Comparative example 2
The procedure of the preparation method is substantially the same as in example 1 except that in step (2), the molar ratio of phosphorus pentachloride to hydrogen fluoride is 1: 2.4.
Comparative example 3
The procedure of the preparation method was substantially the same as in example 6 except that in the step (2), the molar ratio of phosphorus pentachloride to hydrogen fluoride was 1: 4.4.
TABLE 1
TABLE 2
The product properties of each example are given in table 3.
TABLE 3
| Examples | Yield (%) | Purity (%) | Chloride ion content (ppm) | Moisture content (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, when the property parameters of examples 1 to 6 and comparative examples 1 to 3 were analyzed, the yield and purity of examples 1 to 6 were higher than those of comparative examples, and the acid value was lower than those of comparative examples. The invention successfully prepares the lithium difluorobis (oxalato) phosphate or the lithium tetrafluoro (oxalato) phosphate finally by using the phosphorus pentachloride, the oxalic acid, the hydrogen fluoride and the lithium salt as raw materials and precisely controlling the reaction molar ratio of each component and the reaction conditions of each step. The preparation method of the invention selectively prepares the lithium difluorobis (oxalate) phosphate or the lithium tetrafluoro (oxalate) phosphate by freely controlling the feeding amount of the hydrogen fluoride, has high production flexibility and reduces the investment of production equipment. The preparation method of the invention has excellent yield and purity, and the chloride ion content is lower than 6ppm, the moisture content is lower than 10ppm, and the acid value is lower than 25 ppm. The preparation method does not use the conventional lithium hexafluorophosphate as a raw material, so that impurities such as lithium difluorophosphate and the like are not generated, the purity is greatly improved, and the preparation method is different from products of other companies 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 industrial large-scale production.
In comparative example 1, in step (1), the molar ratio of phosphorus pentachloride to oxalic acid is 1:4.0, and the amount of oxalic acid added is too much outside the preferred range of the present invention, resulting in a higher acid value of the product, which is not favorable for the application of the product in the electrolyte.
In comparative example 2, in step (2), the molar ratio of phosphorus pentachloride to hydrogen fluoride was 1:2.4, and the amount of hydrogen fluoride added was out of the preferable range for the preparation of lithium difluorobis (oxalato) phosphate according to the present invention, resulting in the formation of impurities such as lithium tetrafluorooxalato phosphate in the product, and the yield and purity of the product were greatly reduced.
In comparative example 3, in step (2), the molar ratio of phosphorus pentachloride to hydrogen fluoride was 1:4.4, and the amount of hydrogen fluoride added was out of the preferable range for the preparation of lithium tetrafluoro oxalate phosphate according to the present invention, resulting in the formation of impurities such as lithium hexafluorophosphate in the product, a great reduction in the yield and purity of the product, and an increase in the acid value.
The above description is only for the purpose of illustrating the present invention, but not for the purpose of limiting the same, and the present invention is not limited thereto. Numerous simple deductions, modifications or substitutions may be made by those skilled in the art in light of the teachings of the present invention. Such deductions, modifications or alternatives also fall within the scope of the claims of the present invention.
Claims (11)
1. A preparation method of lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalate phosphate is characterized by comprising the following steps:
(1) adding phosphorus pentachloride and oxalic acid into a first non-aqueous solvent, and reacting under stirring to obtain a tri-oxalic acid hydrogen phosphate solution;
(2) introducing hydrogen fluoride into the hydrogen phosphate tribasic solution for fluorination reaction to obtain H [ P (C)2O4)3-(x/2)Fx]The solution is prepared by mixing a solvent and a solvent,
wherein x is 2 or 4, when x is 2, H [ P (C) is obtained2O4)2F2]Solution, when x is 4, gives H [ P (C)2O4)F4]A solution;
(3) reacting said H [ P (C)2O4)3-(x/2)Fx]Adding the solution into a second non-aqueous solvent dispersion containing lithium salt, and reacting under stirring to obtain Li [ P (C)2O4)3-(x/2)Fx]，
Wherein x is 2 or 4; when x is 2, lithium difluorobis (oxalato) phosphate is obtained, and when x is 4, lithium tetrafluorooxalato phosphate is obtained, and the lithium salt is lithium chloride or lithium fluoride.
2. The method for preparing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate as claimed in claim 1, wherein the molar ratio of the phosphorus pentachloride, oxalic acid and lithium salt is 1: (3.01-3.50) and (1.01-1.20).
3. The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to claim 1 or 2,
when the molar ratio of the phosphorus pentachloride to the hydrogen fluoride is 1 (2.05-2.20), H [ P (C) is obtained by reaction2O4)2F2]；
When the molar ratio of the phosphorus pentachloride to the hydrogen fluoride is 1 (4.05-4.20), H [ P (C) is obtained by reaction2O4)F4]。
4. The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to claim 1 or 2,
in the step (1), the first non-aqueous solvent comprises one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, preferably dimethyl carbonate or ethyl methyl carbonate;
the mass of the first non-aqueous 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 lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to claim 1 or 2,
in the step (1), the reaction temperature of the phosphorus pentachloride and the oxalic acid is 30-120 ℃, and preferably 50-80 ℃.
6. The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to claim 1 or 2,
in step (2), at a temperature of 60 deg.CIntroducing the hydrogen fluoride into the hydrogen phosphate solution of the trimalic acid at the temperature of 110 ℃ below zero to perform fluorination reaction for 8-12H to generate H [ P (C)2O4)2F2]Filtering the crude solution to remove insoluble impurities, cooling the filtrate to 5-15 ℃, standing for precipitation for 5-10H, and filtering to remove residual oxalic acid to obtain H [ P (C)2O4)3-(x/2)Fx]And (3) solution.
7. The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to claim 1 or 2,
in the step (3), the second non-aqueous solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, and the second non-aqueous solvent may be the same as or different from the first non-aqueous solvent;
the mass ratio of the lithium salt to the second nonaqueous solvent is 1: (5-10).
8. The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to claim 1 or 2,
in step (3), the H [ P (C) ]2O4)3-(x/2)Fx]The reaction temperature of the lithium salt is 30-110 ℃, and preferably 50-90 ℃.
9. The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to claim 1 or 2, further comprising the following post-treatment step after the reaction in step (3) is completed:
(4) filtering the reaction solution obtained in the step (3), removing redundant lithium salt impurities, and distilling the filtrate at the temperature of 30-80 ℃ under reduced pressure until the filtrate is just saturated;
(5) cooling to 5-10 ℃, adding dichloromethane for crystallization, wherein the crystallization time is 3-8 h, and filtering to obtain the lithium difluorobis (oxalato) phosphate or the wet solid of the lithium tetrafluoro (oxalato) phosphate;
(6) and (3) drying the wet solid at 40-60 ℃ for 5-10 h in vacuum, then heating to 80-100 ℃, and drying for 5-8 h by nitrogen purging to obtain the lithium difluorobis (oxalato) phosphate or the lithium tetrafluoro (oxalato) phosphate.
10. The method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to any one of claims 1 to 9, wherein the steps (1) to (3) are carried out in an inert atmosphere of nitrogen or argon or helium.
11. A lithium difluorobis (oxalato) phosphate or a lithium tetrafluorooxalato phosphate, which is produced by the method for producing lithium difluorobis (oxalato) phosphate or lithium tetrafluorooxalato phosphate according to any one of claims 1 to 9.
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| CN109824726A (en) * | 2018-12-29 | 2019-05-31 | 东莞东阳光科研发有限公司 | A kind of preparation method of difluorobisoxalate lithium phosphate, non-aqueous electrolyte and battery |
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| CN111606952A (en) * | 2020-05-14 | 2020-09-01 | 东莞东阳光科研发有限公司 | Preparation method, non-aqueous electrolyte and battery of lithium tetrafluorooxalate phosphate |
| CN111574566A (en) * | 2020-06-23 | 2020-08-25 | 香河昆仑化学制品有限公司 | Preparation method of lithium tetrafluoro oxalate phosphate and lithium difluorobis oxalate phosphate |
| CN111690010A (en) * | 2020-06-28 | 2020-09-22 | 香河昆仑化学制品有限公司 | Preparation method of lithium tetrafluoro oxalate phosphate and lithium difluorobis oxalate phosphate |
| CN112661791A (en) * | 2020-12-23 | 2021-04-16 | 多氟多化工股份有限公司 | Preparation method of lithium difluorobis (oxalate) phosphate |
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| CN117551133A (en) * | 2024-01-12 | 2024-02-13 | 如鲲(江苏)新材料科技有限公司 | Difluoro-di-oxalic acid phosphate composition, preparation method and application thereof |
| CN117551133B (en) * | 2024-01-12 | 2024-05-24 | 如鲲(江苏)新材料科技有限公司 | Difluoro-di-oxalic acid phosphate composition, preparation method and application thereof |
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