WO2022242053A1 - 一种二氟磷酸锂及其制备方法和应用 - Google Patents

一种二氟磷酸锂及其制备方法和应用 Download PDF

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WO2022242053A1
WO2022242053A1 PCT/CN2021/129085 CN2021129085W WO2022242053A1 WO 2022242053 A1 WO2022242053 A1 WO 2022242053A1 CN 2021129085 W CN2021129085 W CN 2021129085W WO 2022242053 A1 WO2022242053 A1 WO 2022242053A1
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lithium
lithium difluorophosphate
preparation
carbonate
difluorophosphate
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PCT/CN2021/129085
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English (en)
French (fr)
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岳敏
冯天明
余意
王献明
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深圳市研一新材料有限责任公司
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Priority to JP2023569863A priority Critical patent/JP2024519765A/ja
Priority to US18/290,285 priority patent/US20240072304A1/en
Priority to KR1020237039277A priority patent/KR20230172541A/ko
Publication of WO2022242053A1 publication Critical patent/WO2022242053A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/455—Phosphates containing halogen
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • C01P2006/82—Compositional purity water content
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the invention relates to the technical field of lithium ion batteries, in particular to a preparation method of lithium difluorophosphate.
  • lithium-ion batteries As a new type of mobile portable power supply, lithium-ion batteries have higher specific capacity and discharge voltage than traditional lead-acid batteries and alkaline batteries, and have less environmental pollution.
  • lithium-ion batteries are mainly used as portable mobile power sources, mobile phone batteries, and are widely used in electric vehicles, automobiles, etc. as power batteries. Due to the strong support of national policies and the accumulation of lithium-ion battery technology in recent years, the lithium-ion battery industry has achieved tremendous development. However, there are still many defects in lithium-ion batteries at present. In the development of lithium salts, traditional lithium hexafluorophosphate cannot meet the use of lithium-ion batteries under extreme conditions.
  • Lithium difluorophosphate can improve the high and low temperature performance of lithium-ion batteries, significantly improve the cycle stability at minus 20°C, and form a more stable SEI film under high temperature conditions, which can effectively prevent the electrolyte from corroding electrodes and collectors. Fluid, thereby improving the high and low temperature performance of lithium-ion batteries.
  • lithium difluorophosphate has better stability than lithium hexafluorophosphate, and its tolerance to water and oxygen is significantly stronger than lithium hexafluorophosphate. Therefore, lithium difluorophosphate has great industrial value as a new type of lithium salt additive.
  • lithium difluorophosphate There are many production methods for lithium difluorophosphate, which can be roughly divided into three ways: lithium difluorophosphate method, lithium hexafluorophosphate method, and other methods. High, numerous by-products, difficulty in forming solids, etc., are very unfavorable for the industrialization and promotion of lithium difluorophosphate.
  • CN108147385A prepares lithium difluorophosphate with lithium hexafluorophosphate and water reaction, although halogenated siloxane compound can be decomposed, adopt this method to produce, easily cause the decomposition of lithium hexafluorophosphate, meanwhile, reaction process is difficult to control, and by-product is numerous, very harmful to production unfavorable.
  • CN101847753A has described a kind of method that adopts lithium hexafluorophosphate and lithium carbonate to prepare lithium difluorophosphate in aprotic solvent, but this method reaction time is long, conversion rate is low, and this method can only obtain the non-aqueous solution of lithium difluorophosphate simultaneously, cannot Obtaining high-purity lithium difluorophosphate is not conducive to the promotion of lithium difluorophosphate, and there will be more or less organic impurities and lithium fluoride in the salt solution, and these impurities may have adverse effects on the performance of the battery. influences.
  • CN112591727A discloses a preparation method of lithium difluorophosphate, wherein lithium hexafluorophosphate, oxalate and silicon tetrachloride are reacted in an organic solvent; the reaction is carried out under a protective atmosphere.
  • the yield of this method is low, especially the high acid value, which will affect the performance of the electrolyte.
  • no lye is used to neutralize the acidity, and lithium oxalate is basically not alkaline in the organic solvent.
  • the purpose of the present invention is to provide a preparation method of lithium difluorophosphate solid, the preparation process is simple, the cost is low, the reaction time is short, the conversion rate is high, the whole process is easy to control, no water is produced, and the purification There are no by-product impurities.
  • the present invention provides a kind of preparation method of lithium difluorophosphate, it is characterized in that, it comprises the following steps:
  • lithium difluorophosphate it is characterized in that the molar ratio of lithium hexafluorophosphate, silicon tetrachloride and lithium carbonate is 1:(1-1.5):(2-2.5).
  • the molar concentration of lithium hexafluorophosphate is 1.5-4.0 mol/L, preferably 1.5-2.5 mol/L.
  • the reaction temperature of lithium hexafluorophosphate and silicon tetrachloride in the first non-aqueous solvent is 20-100°C, preferably 50 to 90°C, more preferably 70 to 90°C.
  • the gas used in the degassing and impurity removal is an inert gas, preferably one of nitrogen, argon, helium, etc.
  • the temperature for degassing and removing impurities is 60-120°C, preferably 70-100°C, more preferably 85-100°C.
  • the reaction temperature of lithium difluorotetrachlorophosphate and lithium carbonate is 30-80°C, preferably 50-80°C °C.
  • lithium carbonate dispersion liquid is to adopt lithium carbonate and the second non-aqueous solvent to mix and prepare, and lithium carbonate and the second non-aqueous solvent
  • the mass ratio is 1:(3-5), preferably 1:(4.2-5).
  • the first non-aqueous solvent and the second non-aqueous solvent are each independently one of cyclic carbonates, chain carbonates, and cyclic ethers or Two or more, preferably one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethylene carbonate, 1,4-dioxane, and tetrahydrofuran.
  • the mass ratio of the filter cake mixture to ethyl acetate is 1:(1 ⁇ 2), preferably 1:( 1.90 ⁇ 2), the time for the filter cake mixture to be beaten with ethyl acetate is 3 ⁇ 5h.
  • the concentrated beating liquid is completed by subjecting the filtrate to vacuum distillation, and the vacuum distillation temperature is 40-80°C , preferably 45 to 65°C, more preferably 50 to 65°C.
  • the non-polar solvent is n-hexane, n-pentane, cyclohexane, heptane, dichloromethane, trichloromethane , 1,2-dichloroethane or one or more of them.
  • the crystallization temperature is 0-5°C, preferably 0-3.5°C.
  • step (3) after crystallization, filter cake is obtained by filtration, and the filter cake is dried to obtain lithium difluorophosphate;
  • the temperature for drying the filter cake is 80-120°C, preferably 100-120°C.
  • step (1) and step (2) the reaction is carried out in an atmosphere of an inert gas, and the inert gas is nitrogen, argon, helium one or more of them.
  • the present invention also provides a lithium difluorophosphate, which is prepared by the preparation method described in any one of claims 1 to 14, wherein the purity of the lithium difluorophosphate is ⁇ 99.8%, and the content of free acid is ⁇ 50ppm, preferably ⁇ 25ppm.
  • lithium difluorophosphate it is characterized in that the content of water is ⁇ 10ppm, the content of Cl- is ⁇ 1ppm, preferably ⁇ 0.8ppm, and the sum of the contents of impurity metal ions is ⁇ 2ppm, preferably ⁇ 1.5ppm.
  • the present invention also provides a non-aqueous electrolyte battery, which contains a positive electrode, a negative electrode and an electrolyte containing the aforementioned lithium difluorophosphate.
  • the present invention has the following advantages and effects:
  • the preparation method of the lithium difluorophosphate solid provided by the invention adopts a two-step reaction, and the process is simple. Commonly used lithium hexafluorophosphate, silicon tetrachloride and lithium carbonate are used as raw materials, all of which are common cheap bulk chemicals, and the preparation cost is low.
  • the first step of the reaction process produces the intermediate LiPF 2 Cl 4 , which contains four chlorine atoms in its structure. The chlorine atom has a large atomic radius, and its binding force with phosphorus is smaller than that of the fluorine atom. The chlorine atom is easier to leave, so it is easier to generate difluorophosphoric acid.
  • Lithium has a faster rate and shorter reaction time, and there is no water involved in the whole reaction, which avoids the hydrolysis of the product to produce impurities, resulting in the problem of low purity.
  • lithium carbonate is used as the reaction raw material, which is cheap, widely sourced, and slightly excessive, usually used alone for acid removal in organic solvents, thereby neutralizing free acid and reducing the acid value in the present invention.
  • the preparation method of lithium difluorophosphate provided by the present invention is a two-step reaction method, and its corresponding chemical reaction formula is as follows:
  • the reaction is carried out in the first non-aqueous solvent.
  • the first non-aqueous solvent is a mixture of one or more of cyclic carbonates, chain carbonates, cyclic esters, chain esters, and cyclic ethers, preferably dimethyl carbonate, ethyl methyl carbonate , diethyl carbonate, ethylene carbonate, 1,4-dioxane, tetrahydrofuran, or a mixture of two or more, more preferably dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate.
  • the molar ratio of lithium hexafluorophosphate to silicon tetrachloride is 1: (1 ⁇ 1.5), so that silicon tetrachloride is excessive to ensure the complete reaction of lithium hexafluorophosphate. If the molar ratio is lower than 1:1, a large amount of lithium hexafluorophosphate will remain in the reaction solution; if it is higher than 1 : 1.5, a large amount of silicon tetrachloride will remain, and subsequent removal will cost a lot.
  • the concentration of lithium hexafluorophosphate is 1.5-4.0mol/L, if the concentration is lower than 1.5mol/L, the reaction rate will be affected; if the concentration is higher than 4.0mol/L, the solution will change color easily, which will affect the final product.
  • the reaction temperature is 20 to 100°C, preferably 50 to 90°C, more preferably 70 to 90°C. If the reaction temperature is too low, the reaction rate will be low; if the temperature is too high, the decomposition of lithium hexafluorophosphate will be accelerated, and by-product impurities will easily be produced.
  • the temperature for degassing and removing impurities is 60-120°C, preferably 70-100°C, more preferably 85-100°C.
  • the degassing temperature is lower than 60°C, and the concentration of chlorine compounds in the reaction solution is high, so it cannot be used as an additive for non-aqueous electrolyte. If the degassing temperature is higher than 120°C, it will cause the solution to bump and cause the loss of materials.
  • the gas used for degassing and removing impurities is an inert gas, preferably one or two or more of nitrogen, argon, helium and the like.
  • step (2) the reaction is carried out under the protection of an inert gas.
  • the lithium carbonate dispersion is prepared from lithium carbonate and the second non-aqueous solvent.
  • the mass ratio of lithium carbonate to the second non-aqueous solvent is 1: (3-5), preferably 1: (4.2-5), if the mass If the ratio is lower than 1:3, a normal slurry-like uniform dispersion of lithium carbonate cannot be formed, which may cause insufficient reaction; if the mass ratio is greater than 1:5, it will cause waste of solvent.
  • the second non-aqueous solvent is a mixture of one or more of cyclic carbonates, chain carbonates, cyclic esters, chain esters, and cyclic ethers, preferably dimethyl carbonate, ethyl methyl carbonate , diethyl carbonate, ethylene carbonate, 1,4-dioxane, tetrahydrofuran, or a mixture of two or more, more preferably dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate.
  • the molar ratio of lithium hexafluorophosphate to lithium carbonate is 1: (2 ⁇ 2.5). This limit value is to ensure the complete reaction of lithium difluorotetrachlorophosphate.
  • the reaction temperature is 20-80°C, preferably 30-80°C. If the temperature is lower than 20°C, the reaction rate will be too slow; if the temperature is too high, side reactions will easily occur to produce PO 3 - and PO 4 3- .
  • the inert gas is one or more of nitrogen, argon, and helium.
  • the weight of ethyl acetate is 1 to 2 times of the weight of the filter cake mixture, preferably 1.90 to 2 times; if it is less than 1 time, it will easily cause incomplete extraction of the product and reduce the yield; More than 2 times will cause the waste of solvent.
  • the beating time is 3-5 hours, so that the lithium difluorophosphate can be fully dissolved in the ethyl acetate solution. Collecting and concentrating the beating liquid is accomplished by subjecting the filtrate to vacuum distillation.
  • the vacuum distillation temperature is 40-80°C, preferably 45-65°C, more preferably 50-65°C. If it is lower than 40°C, the distillation speed It is slow; if it is higher than 80°C, lithium difluorophosphate may be entrained by the solvent, resulting in a certain loss of yield.
  • the crystallization solvent is selected from a weak polar or non-polar solvent for crystallization, preferably n-hexane, n-pentane, cyclohexane, heptane, dichloromethane, trichloromethane, 1,2-dichloroethane One or two or more; the crystallization temperature is 0-5°C, and the crystallization time is 2-5h.
  • the drying temperature of the filter cake is 80-120°C, preferably 100-120°C, and the drying time is 8-15 hours, preferably 12-15 hours. They are not particularly limited as long as the desired crystallization effect can be achieved.
  • the lithium difluorophosphate prepared by the method of the present invention has a purity of ⁇ 99.8%, a free acid content of ⁇ 50ppm, a moisture content of ⁇ 10ppm, a Cl- content of ⁇ 1ppm, preferably ⁇ 0.8ppm, and the sum of the contents of impurity metal ions ⁇ 2 ppm, preferably ⁇ 1.5 ppm.
  • the raw materials or reagents used in the present invention are all purchased from mainstream manufacturers in the market, and those who do not indicate the manufacturer or the concentration are all analytically pure grade raw materials or reagents that can be routinely obtained. As long as they can play the expected role, There are no particular restrictions.
  • the instruments and equipment used in this example are all purchased from major manufacturers in the market, and there are no special limitations as long as they can play the expected role. If no specific technique or condition is indicated in this example, the technique or condition described in the literature in this field or the product manual shall be followed.
  • Glove box purchased from Michelona, model Siemens S7;
  • Vacuum drying oven purchased from Shanghai Yiheng, model DZF-6050;
  • ICP-OES Inductively coupled plasma optical emission spectrometer
  • Karl Fischer method test uses Jingtai SF-3 Karl Fischer moisture tester for moisture test
  • Dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate, and silicon tetrachloride were purchased from Aladdin Reagent Network;
  • Lithium hexafluorophosphate was purchased from Morita New Energy (Zhangjiagang);
  • Lithium carbonate was purchased from Ganfeng Lithium Industry.
  • the above-mentioned three-neck flask was transferred to the outside of the glove box and placed in an oil bath at normal temperature. Take by weighing 50.29g silicon tetrachloride (0.296mol, the molecular weight of silicon tetrachloride is 169.9g/mol), quickly join in the constant pressure dropping funnel, then install condenser tube, constant pressure dropping funnel, carry out nitrogen gas to the system Protect. Then slowly increase the temperature of the oil bath to 50°C, and at the same time slowly drop silicon tetrachloride into the three-necked flask for reaction, and the tail gas is introduced into the aqueous sodium hydroxide solution through the conduit for absorption.
  • step (3) Add ethyl acetate 160ml (144.32g) to the filter cake mixture obtained in step (2), carry out beating at room temperature, filter after beating for 3.5h, collect the beating liquid, carry out vacuum distillation at 50°C, and distill to Just saturated state, stop the vacuum distillation and cool to about 0°C, add dichloromethane to stir and crystallize, the crystallization time is 3h, after filtering, a pure white powder filter cake is obtained, put it in a vacuum drying oven at 120°C After drying for 10 h, 29.5 g of pure white powdery lithium difluorophosphate solid was obtained with a yield of 93.2%.
  • the high-purity lithium difluorophosphate is a high-purity white powdery solid, its purity is ⁇ 99.9% through ion chromatography, the free acid is 20ppm as detected by titration, the water content is ⁇ 10ppm as measured by Karl Fischer method, and the Cl- The content is 0.3ppm, and the sum of the contents of impurity metal ions measured by the ICP-OES method is 0.5ppm. See Table 3 for details.
  • Lithium difluorophosphate was prepared according to the technical route of "lithium hexafluorophosphate + lithium carbonate + anhydrous and oxygen-free state ⁇ lithium difluorophosphate" disclosed in CN107381531A.
  • Lithium difluorophosphate was prepared according to the technical route of "lithium hexafluorophosphate + lithium carbonate + ultrapure water ⁇ lithium difluorophosphate" disclosed in CN108128764A.
  • Table 3 The relevant parameter tests are shown in Table 3.
  • lithium hexafluorophosphate + chloride + water (solvent-free) ⁇ lithium difluorophosphate disclosed in JP6226643B2
  • lithium hexafluorophosphate + chloride (lithium chloride, silicon tetrachloride, etc.) + water vapor (oxygen element provided by water) disclosed in KR102218938B1 ) ⁇ lithium difluorophosphate to prepare lithium difluorophosphate.
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • the present invention first reacts lithium hexafluorophosphate with silicon tetrachloride to prepare an intermediate, and then reacts the intermediate with lithium carbonate to generate lithium difluorophosphate, which can react more thoroughly with lithium carbonate and directly express Because the product purity and yield are higher than the comparative example, in addition, the present invention can reduce the chloride ion content to below 1ppm by dechlorination and impurity removal. In the reaction system of the present invention, it does not contain water and does not produce water. The moisture content of the product obtained is All can be reduced to less than 10ppm, which meets the actual requirements of lithium battery applications.

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Abstract

一种二氟磷酸锂及其制备方法和应用，利用六氟磷酸锂和四氯化硅生成二氟四氯化磷酸锂，然后使二氟四氯化磷酸锂与碳酸锂反应得到二氟磷酸锂与氯化锂的混合物，然后通过纯化得到高纯度二氟磷酸锂。这种方法步骤简单、成本低、反应时间短、转化率高。

Description

一种二氟磷酸锂及其制备方法和应用 技术领域
本发明涉及锂离子电池技术领域，具体涉及一种二氟磷酸锂的制备方法。
背景技术
作为新型的移动便携式电源，锂离子电池比传统的铅酸电池和碱性电池具有更高的比容量和放电电压，而且对环境污染小。目前，锂离子电池，主要作为便携式移动电源，手机电池，并广泛应用于电动车，汽车等作为动力电池使用。由于国家政策上的大力支持，以及近年来锂离子电池技术的积累，锂离子电池产业获得了巨大发展。但是，目前锂离子电池还存在许多缺陷，在锂盐的开发上，传统的六氟磷酸锂不能满足锂离子电池在极端条件下的使用。二氟磷酸锂可以改善锂离子电池的高低温性能，使其在零下20℃的循环稳定性明显提高，并且在高温条件下可以形成更为稳定的SEI膜，可以有效阻止电解液腐蚀电极和集流体，从而改善锂离子电池的高低温性能。另外，二氟磷酸锂比起六氟磷酸锂，具有更好的稳定性，对水和氧的耐受性明显强于六氟磷酸锂。因此二氟磷酸锂作为一种新型的锂盐添加剂，具有很大的工业价值。
二氟磷酸锂的生产方法有很多，大致分为三种途径：二氟磷酸锂途径法、六氟磷酸锂途径法、其他方法，但是现有的二氟磷酸锂的制备方法，工艺复杂，对生产设备要求较高，副产品众多，生成固体困难等，非常不利于二氟磷酸锂的工业化和推广。
CN103052592B中提到使用五氟化磷、磷酰氟与磷酸锂反应制备二氟磷酸锂产品，所使用的技术路线用到昂贵、剧毒、高危险的五氟化磷气体，工艺复杂，且对生产设备要求严格，产品成本较高。
CN108147385A用六氟磷酸锂和水反应制备二氟磷酸锂，虽然可以将卤化硅氧烷化合物分解，但是采用这种方法生产，容易造成六氟 磷酸锂的分解，同时，反应过程不易控制，且副产物众多，对生产非常不利。
CN101847753A描述了一种采用六氟磷酸锂和碳酸锂在非质子性溶剂中制备二氟磷酸锂的方法，但是该方法反应时间长，转化率低，同时该方法只能得到二氟磷酸锂的非水溶液，不能得到高纯度的二氟磷酸锂，非常不利于二氟磷酸锂的推广，并且该盐溶液中，或多或少会有一些有机杂质和氟化锂，这些杂质可能会对电池的性能产生不利的影响。
CN112591727A公开了一种二氟磷酸锂的制备方法，其中，使六氟磷酸锂、草酸盐和四氯化硅于有机溶剂中进行反应；所述反应在保护气氛下进行。但是该方法的收率偏低，特别是酸值高，会对电解液性能造成影响，该方法中也没有采用碱液去中和酸性，草酸锂在有机溶剂中基本没有碱性。
发明内容
针对现有技术存在的缺陷，本发明的目的在于提供一种二氟磷酸锂固体的制备方法，制备工艺简单，成本低廉，反应时间短，转化率高，整个过程易于控制，不产生水，提纯后无副产物杂质。
本发明提供一种二氟磷酸锂的制备方法，其特征在于，其包括以下步骤：
(1)在基本无水的情况下，将六氟磷酸锂与四氯化硅在第一非水溶剂中进行搅拌反应，脱气除杂，得到二氟四氯化磷酸锂溶液；
(2)将得到的二氟四氯化磷酸锂溶液滴加到碳酸锂分散液中进行反应，过滤得到二氟磷酸锂与氯化锂的滤饼混合物；
(3)用醋酸乙酯将所述滤饼混合物进行打浆，过滤除去不溶性物质，浓缩打浆液，再加入非极性溶剂进行结晶，得到二氟磷酸锂。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，六氟磷酸锂、四氯化硅与碳酸锂的投料摩尔比为1：(1～1.5)：(2～2.5)。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，在步骤(1)中，六氟磷酸锂的摩尔浓度为1.5～4.0mol/L，优选为1.5～2.5mol/L。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，在步骤(1)中，六氟磷酸锂与四氯化硅在所述第一非水溶剂中的反应温度为20～100℃，优选为50～90℃，更优选为70～90℃。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，在步骤(1)中，脱气除杂中使用的气体为非活性气体，优选为氮气、氩气、氦气等中的一种或二种以上，脱气除杂的温度为60～120℃，优选为70～100℃，更优选为85～100℃。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，在步骤(2)中，所述二氟四氯化磷酸锂与碳酸锂的反应温度为30～80℃，优选为50～80℃。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，在步骤(2)中，碳酸锂分散液是采用碳酸锂与第二非水溶剂混合配制得到，碳酸锂与第二非水溶剂的质量比为1：(3～5)，优选为1：(4.2～5)。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，第一非水溶剂和第二非水溶剂各自独立地环状碳酸酯、链状碳酸酯、以及环状醚中的一种或二种以上，优选为碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、碳酸乙烯酯、1,4-二氧六环、四氢呋喃中的一种或二种以上。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，在步骤(3)中，所述滤饼混合物与醋酸乙酯的质量比为1：(1～2)，优选为1：(1.90～2)，所述滤饼混合物用醋酸乙酯进行打浆的时间为3～5h。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，在步骤(3)中，所述浓缩打浆液是通过将滤液进行减压蒸馏而完成的，减压蒸馏温度为40～80℃，优选为45～65℃，更优选为50～65℃。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，在步骤(3)中，非极性溶剂为正己烷、正戊烷、环己烷、庚烷、二氯甲烷、三氯甲烷、1,2-二氯乙烷中的一种或二种以上。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，在步骤(3)中，析晶的温度为0～5℃，优选为0～3.5℃。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，在步骤(3)中，进行结晶之后，还进行过滤而得到滤饼，并将所述滤饼干燥而得到二氟磷酸锂；滤饼干燥的温度为80～120℃，优选为100～120℃。
优选地，根据上述二氟磷酸锂的制备方法，其特征在于，在步骤(1)和步骤(2)中，反应均是在惰性气体的气氛中进行，惰性气体为氮气、氩气、氦气中的一种或二种以上。
本发明还提供一种二氟磷酸锂，其由权利要求1～14任一项所述的制备方法制得，其中，该二氟磷酸锂的纯度≥99.8％，游离酸的含量≤50ppm，优选≤25ppm。
优选地，根据上述二氟磷酸锂，其特征在于，水分的含量≤10ppm，Cl -的含量≤1ppm，优选≤0.8ppm，杂质金属离子的含量之和≤2ppm，优选≤1.5ppm。
本发明还提供一种非水电解液电池，其含有正极、负极和包含前面所述的二氟磷酸锂的电解液。
上述二氟磷酸锂在制备非水电解液电池中的应用。
相对于现有技术，本发明具有以下的优点及效果：
本发明提供的二氟磷酸锂固体的制备方法，采用两步法反应，工艺简单，原料采用常用的六氟磷酸锂、四氯化硅和碳酸锂，均为常见廉价大宗化学药品，制备成本低廉。第一步反应过程生成中间体LiPF 2Cl 4，其结构含有四个氯原子，氯原子的原子半径大，与磷元素结合力小于氟原子，氯原子更易离去，因此更容易生成二氟磷酸锂，速率更快，反应时间更短，并且，反应全程无水参与，避免了产物的水解而产生杂质，导致纯度不高的问题。本发明中使用碳酸锂作为反应原料，价格低廉，来源广泛，且稍微过量，平常就单独用于在有机溶剂中除酸，因而在本发明中能够中和游离酸，降低酸值。
具体实施方式
为了更好的理解上述技术方案，下面通过具体实施例对本申请技术方案做详细的说明，应当理解本申请实施例以及实施例中的具体特征是对本申请技术方案的详细的说明，而不是对本申请技术方案的限定，在不冲突的情况下，本申请实施例以及实施例中的技术特征可以相互结合。
本发明提供的二氟磷酸锂的制备方法是两步反应法，其对应的化学反应式如下：
LiPF 6+SiCl 4→LiPF 2Cl 4+SiF 4↑
LiPF 2Cl 4+2Li 2CO 3→LiPO 2F 2+2CO 2↑+4LiCl
其具体在一个优选的方案中，本发明的制备方法的具体步骤如下：
(1)在基本无水的情况下，在惰性气体保护下将六氟磷酸锂与四氯化硅反应，制得二氟四氯化磷酸锂溶液，该步骤反应完成后需要进行脱气除杂，目的是脱除四氟化硅，防止残留的四氟化硅对下一步反应造成影响。
(2)将制得的二氟四氯化磷酸锂溶液滴入到碳酸锂分散液中进行反应，可以得到二氟磷酸锂与氯化锂的混合物。
(3)用醋酸乙酯对上述滤饼进行打浆，过滤，收集打浆液，再进行浓缩，之后加入非水溶剂进行析晶，得到滤饼，干燥后，得到二氟磷酸锂。
在步骤(1)中，反应是在第一非水溶剂中进行的。第一非水溶剂是环状碳酸酯、链状碳酸酯、环状酯、链状酯、以及环状醚中的一种或二种以上的混合物，优选为碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、碳酸乙烯酯、1,4-二氧六环、四氢呋喃中的一种或二种以上的混合物，更优选为碳酸二甲酯、碳酸甲乙酯或碳酸二乙酯。六氟磷酸锂与四氯化硅的摩尔比为1：(1～1.5)，让四氯化硅过量，保证六氟磷酸锂完全反应，摩尔比低于1：1，则反应液会残留大量的六氟磷酸锂；高于1：1.5，则会残留大量四氯化硅，后续除去需要耗费成本。 六氟磷酸锂的浓度为1.5～4.0mol/L，浓度低于1.5mol/L，影响反应速率；浓度高于4.0mol/L，其溶液容易变色，对最终产品有影响。反应温度为20～100℃，优选为50～90℃，进一步优选为70～90℃。反应温度过低则反应速率低；温度过高，六氟磷酸锂分解加快，易产生副产物杂质。脱气除杂的温度为60～120℃,优选为70～100℃，更优选为85～100℃。脱气的温度低于60℃，反应液中氯化合物的浓度高，不能作为非水电解液添加剂使用。脱气的温度高于120℃，则会造成溶液的爆沸，造成物料的损失。脱气除杂使用的气体为非活性气体，优选为氮气、氩气、氦气等中的一种或二种以上。
在步骤(2)中，反应是在惰性气体保护下进行的。碳酸锂分散液是由碳酸锂与第二非水溶剂配制而成，碳酸锂与第二非水溶剂的质量比为1：(3～5)，优选为1：(4.2～5)，如果质量比低于1：3，不能形成正常的碳酸锂浆状均匀分散液，可能会造成反应不充分；若质量比大于1：5，则会造成溶剂的浪费。第二非水溶剂是环状碳酸酯、链状碳酸酯、环状酯、链状酯、以及环状醚中的一种或二种以上的混合物，优选为碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、碳酸乙烯酯、1,4-二氧六环、四氢呋喃中的一种或二种以上的混合物，更优选为碳酸二甲酯、碳酸甲乙酯或碳酸二乙酯。六氟磷酸锂与碳酸锂的摩尔比为1：(2～2.5)，此限定值为了保证二氟四氯化磷酸锂完全反应，高于1：2.5，则造成碳酸锂的浪费；低于1：2，反应无法完全进行。反应温度为20～80℃，优选为30～80℃，温度低于20℃，则反应速率太慢；温度过高，则容易产生副反应而生成PO 3 -、PO 4 3-。
在步骤(1)和(2)中，惰性气体为氮气、氩气、氦气中的一种或二种以上。
在步骤(3)中，醋酸乙酯的重量为滤饼混合物重量的1～2倍，优选为1.90～2倍；如果低于1倍，则容易造成产物提取不完全，造成产率降低；高于2倍则会造成溶剂的浪费。打浆时长为3～5h，使得二氟磷酸锂能充分溶解到醋酸乙酯溶液中。收集打浆液并浓缩是通过将滤液进行减压蒸馏而完成的，减压蒸馏温度为40～80℃，优选 为45～65℃，更优选为50～65℃，低于40℃，则蒸馏速度偏慢；高于80℃则可能会造成二氟磷酸锂被溶剂夹带，对产率造成一定的损失。
析晶溶剂选用弱极性或非极性溶剂进行析晶，优选为正己烷、正戊烷、环己烷、庚烷、二氯甲烷、三氯甲烷、1,2-二氯乙烷中的一种或两种以上；析晶的温度为0～5℃，析晶时长为2～5h。滤饼干燥温度为80～120℃，优选为100～120℃,干燥时长为8～15h，优选为12～15h。只要能到达预期的析晶效果即可，对它们并没有特别限定。
用本发明的方法制备得到的二氟磷酸锂，纯度≥99.8％，游离酸的含量≤50ppm，水分的含量≤10ppm，Cl -的含量≤1ppm，优选≤0.8ppm，杂质金属离子的含量之和≤2ppm，优选≤1.5ppm。
实施例
本发明中使用的原料或试剂均购自市场主流厂家，未注明生产厂商者或者未注明浓度者，均为可以常规获取的分析纯级的原料或试剂，只要能起到预期的作用，并无特别限制。本实施例中使用的仪器设备均购自市场主要厂家，只要能起到预期的作用，并无特别限定。本实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。
原料和仪器：
手套箱，购自米开罗那，型号Siemens S7；
真空干燥箱，购自上海一恒，型号DZF-6050；
离子色谱，采用瑞士万通833型离子色谱仪；
电感耦合等离子体发射光谱仪(ICP-OES)，采用吉天仪器ICP-5000电感耦合等离子体发射光谱仪；
卡尔费休法测试采用精泰SF-3卡尔费休水分测试仪进行水分测试；
碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、醋酸乙酯、四氯化硅购自阿拉丁试剂网；
六氟磷酸锂，购自森田新能源(张家港)；
碳酸锂，购自赣锋锂业。
实施例1
(1)在水分含量低于10质量ppm的手套箱中，准备一个250ml的三口烧瓶，将水分含量为10质量ppm以下的碳酸二甲酯150ml加入烧瓶内，将三口烧瓶置于手套箱的冰箱内进行冷冻，然后称取45.0g六氟磷酸锂(0.296mol，分子量151.9g/mol)，使得六氟磷酸锂的摩尔浓度为1.97mol/L。缓慢溶解于冷冻后的碳酸二甲酯溶剂中，控制溶解过程中溶液温度在5～10℃。操作完毕后，将上述三口烧瓶转移至手套箱外，置于常温油浴锅内。称取50.29g四氯化硅(0.296mol，四氯化硅的分子量169.9g/mol)，快速加入到恒压滴液漏斗内，然后装上冷凝管、恒压滴液漏斗，将体系进行氮气保护。然后缓慢升高油浴温度至50℃，同时向三口烧瓶中缓慢滴加四氯化硅进行反应，尾气经过导管导入到氢氧化钠水溶液进行吸收。反应至尾吸口不再有气泡冒出时，继续再反应2～3h，反应结束。此时，将反应液温度升高至80℃，在三口烧瓶内插入鼓泡器并使用氮气缓慢鼓泡，鼓出的气体使用氢氧化钠水溶液吸收，直至湿润的pH试纸接触鼓出的气泡后呈中性，说明残存的四氯化硅和四氟化硅气体已被完全排出。此时，将第一步反应生成的LiPF 2Cl 4溶液冷却至室温，快速导入恒压滴液漏斗中密封备用。
(2)取另一个500ml三口烧瓶，加入140ml水分含量小于10质量ppm的碳酸二甲酯溶剂，置于油浴锅内室温下搅拌，称取45.8g(0.62mol，碳酸锂的分子量为73.9g/mol)碳酸锂，快速加入到三口烧瓶内搅拌均匀，形成碳酸锂的碳酸二甲酯浆状液。将前面步骤(1)得到的装有LiPF 2Cl 4溶液的恒压滴液漏斗、冷凝管装到该步骤(2)的三口烧瓶上，做好氮气保护，在30℃时缓慢滴加LiPF 2Cl 4溶液，将所产生的二氧化碳气体导入尾气吸收瓶，用氢氧化钠溶液吸收，反应至尾气吸收瓶内无气泡冒出，反应结束。冷却至室温下，快速过滤，得 到118g的湿固体混合物(滤饼混合物)，将其转移到烧瓶内。
(3)在步骤(2)得到的滤饼混合物中加入醋酸乙酯160ml(144.32g)，进行室温下打浆，打浆3.5h后过滤，收集打浆液，在50℃下进行减压蒸馏，蒸馏至恰饱和状态，停止减压蒸馏并冷却至0℃左右，加入二氯甲烷进行搅拌结晶，结晶时长为3h，过滤后，得到纯白色粉末状滤饼，将其置于真空干燥箱内，120℃下干燥10h，得到纯白色粉末状二氟磷酸锂固体29.5g，产率为93.2％。
所述高纯二氟磷酸锂为高纯白色粉末状固体，经过离子色谱检测其纯度≥99.9％，滴定法检测游离酸为20ppm，利用卡尔费休法测得水分≤10ppm，滴定法测试Cl -含量为0.3ppm，ICP-OES法测得杂质金属离子的含量之和为0.5ppm。具体参见表3。
实施例2～6
除按照表1和表2选定各种物质及其用量、条件参数等外，其他与实施例1相同。
对比例1
按照CN107381531A公开的“六氟磷酸锂+碳酸锂+无水无氧状态→二氟磷酸锂”的技术路线制备二氟磷酸锂。
在1L的容器中加入600ml的碳酸二乙酯(DEC)，添加1.0mol的碳酸锂，升温至62℃，然后缓慢投入0.5mol的六氟磷酸锂，温度控制在68℃，加完后升温至73℃，搅拌2h，将得到的反应液过滤，过滤后，得到滤饼湿固体102g，加入醋酸乙酯153g进行5h打浆，然后滤去不溶性滤渣，得到的滤液在60℃下减压蒸馏至恰饱和，放入0℃冰浴中，加入不良溶剂二氯甲烷搅拌析晶，结晶时长4h，将得到的二氟磷酸锂产品放入真空干燥箱内120℃下干燥10h，得到39.42g二氟磷酸锂固体，收率73.0％，相关参数测试见表3。
对比例2
按照CN108128764A公开的“六氟磷酸锂+碳酸锂+超纯水→二氟磷酸锂”的技术路线制备二氟磷酸锂。
将152g(1.0mol)的六氟磷酸锂溶解到1000ml的碳酸二甲酯之中， 加入0.5g超纯水，升温至80℃，然后加入148g(2.0mol)碳酸锂，搅拌反应1.5h，过滤后，得到滤饼湿固体235g，加入醋酸乙酯329g进行5h打浆，然后滤去不溶性滤渣，得到的滤液在60℃下减压蒸馏至恰饱和，放入0℃冰浴中，加入不良溶剂二氯甲烷搅拌析晶，析晶时长5h，将得到的二氟磷酸锂产品放入真空干燥箱内120℃下干燥12h，得到98.5g二氟磷酸锂固体，收率92.1％，相关参数测试见表3。
对比例3
按照JP6226643B2公开的“六氟磷酸锂+氯化物+水(无溶剂)→二氟磷酸锂”及KR102218938B1公开的“六氟磷酸锂+氯化物(氯化锂、四氯化硅等)+水蒸汽(由水提供氧元素)→二氟磷酸锂”的方法制备二氟磷酸锂。
在505g的碳酸甲乙酯中溶解152g(1.0mol)的LiPF6和258.1g(2.0mol)的二甲基二氯硅烷，冷却至0℃。接着缓慢滴加36g(2mol)的水之后，升温至25℃，搅拌3小时，然后升温至30度，先进行减压预脱气，然后在30℃、绝对压力30Pa正式脱气，将得到的浆状液过滤，得到湿滤饼217g，加入325.5g醋酸乙酯进行4h打浆，然后滤去不溶性滤渣，得到的滤液在60℃下减压蒸馏至恰饱和，放入0℃冰浴中，加入不良溶剂二氯甲烷搅拌析晶，析晶时长4h，将得到的二氟磷酸锂产品放入真空干燥箱内120℃下干燥10h，得到94.7g二氟磷酸锂固体，收率87.7％，相关参数测试见表3。
表1
Figure PCTCN2021129085-appb-000001
注：DMC为碳酸二甲酯；DEC为碳酸二乙酯；EMC为碳酸甲乙酯
表2
Figure PCTCN2021129085-appb-000002
表3
Figure PCTCN2021129085-appb-000003
如表3所示，分析实施例1～6与对比例1、2、3的测试结果可知，与对比例1、2、3相比，在实施例1～6中，在收率方面具有优异的效果，在产品纯度方面具有很大的优势，本发明的反应体系中，不含水，不产水，因而在产品纯度和含水量方面具有绝对优势。
由测试结果可知，实施例2、4、6在纯度、收率方面具有更好的 效果，说明打浆溶剂的加入量相对多时比较有利，是优选的。
概括而言，本发明采用先将六氟磷酸锂与四氯化硅反应，制备中间体，再利用中间体与碳酸锂反应生成二氟磷酸锂，该中间体可以与碳酸锂反应地更为彻底，直接表现为产品纯度及收率比对比例更高，另外本发明通过脱氯除杂，可以将氯离子含量降低至1ppm以下，本发明的反应体系中，不含水，不产生水，所得的产品水分含量均可降低至10ppm以下，达到了满足锂电池应用的实际要求。
以上所述仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，以上应用了具体实例对本发明进行阐述，只是用于帮助理解本发明，并不用以限制本发明。本发明所属技术领域的技术人员依据本发明的构思，还可以做出若干简单推演、变形或替换。这些推演、变形或替换方案也落入本发明的权利要求范围内。

Claims (15)

  1. 一种二氟磷酸锂的制备方法，其特征在于，其包括以下步骤：
    (1)在基本无水的情况下，将六氟磷酸锂与四氯化硅在第一非水溶剂中进行搅拌反应，脱气除杂，得到二氟四氯化磷酸锂溶液；
    (2)将得到的二氟四氯化磷酸锂溶液滴加到碳酸锂分散液中进行反应，过滤得到二氟磷酸锂与氯化锂的滤饼混合物；
    (3)用醋酸乙酯将所述滤饼混合物进行打浆，过滤除去不溶性物质，浓缩打浆液，再加入非极性溶剂进行结晶，得到二氟磷酸锂。
  2. 根据权利要求1所述的二氟磷酸锂的制备方法，其特征在于，六氟磷酸锂、四氯化硅与碳酸锂的投料摩尔比为1：(1～1.5)：(2～2.5)。
  3. 根据权利要求1或2所述的二氟磷酸锂的制备方法，其特征在于，在步骤(1)中，六氟磷酸锂的摩尔浓度为1.5～4.0mol/L，优选为1.5～2.5mol/L。
  4. 根据权利要求1～3中任一项所述的二氟磷酸锂的制备方法，其特征在于，
    在步骤(1)中，六氟磷酸锂与四氯化硅在所述第一非水溶剂中的反应温度为20～100℃，优选为50～90℃，更优选为70～90℃；或者
    在步骤(1)中，脱气除杂中使用的气体为非活性气体，优选为氮气、氩气、氦气等中的一种或二种以上，脱气除杂的温度为60～120℃，优选为70～100℃，更优选为85～100℃。
  5. 根据权利要求1～4中任一项所述的二氟磷酸锂的制备方法，其特征在于，
    在步骤(2)中，所述二氟四氯化磷酸锂与碳酸锂的反应温度为30～80℃，优选为50～80℃；或者
    在步骤(2)中，碳酸锂分散液是采用碳酸锂与第二非水溶剂混合配制得到，碳酸锂与第二非水溶剂的质量比为1：(3～5)，优选为1： (4.2～5)。
  6. 根据权利要求1～5中任一项所述的二氟磷酸锂的制备方法，其特征在于，第一非水溶剂和第二非水溶剂各自独立地为环状碳酸酯、链状碳酸酯、以及环状醚中的一种或二种以上，优选为碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、碳酸乙烯酯、1,4-二氧六环、四氢呋喃中的一种或二种以上。
  7. 根据权利要求1～6中任一项所述的二氟磷酸锂的制备方法，其特征在于，在步骤(3)中，所述滤饼混合物与醋酸乙酯的质量比为1：(1～2)，优选为1：(1.90～2)，所述滤饼混合物用醋酸乙酯进行打浆的时间为3～5h；或者
    在步骤(3)中，所述浓缩打浆液是通过将滤液进行减压蒸馏而完成的，减压蒸馏温度为40～80℃，优选为45～65℃，更优选为50～65℃。
  8. 根据权利要求1～7中任一项所述的二氟磷酸锂的制备方法，其特征在于，
    在步骤(3)中，非极性溶剂为正己烷、正戊烷、环己烷、庚烷、二氯甲烷、三氯甲烷、1,2-二氯乙烷中的一种或二种以上。
  9. 根据权利要求1～8中任一项所述的二氟磷酸锂的制备方法，其特征在于，在步骤(3)中，析晶的温度为0～5℃，优选为0～3.5℃。
  10. 根据权利要求1～9中任一项所述的二氟磷酸锂的制备方法，其特征在于，在步骤(3)中，进行结晶之后，还进行过滤而得到滤饼，并将所述滤饼干燥而得到二氟磷酸锂，滤饼干燥的温度为80～120℃，优选为100～120℃。
  11. 根据权利要求1～10中任一项所述的二氟磷酸锂的制备方法，其特征在于，在步骤(1)和步骤(2)中，反应均是在惰性气体的气氛中进行，惰性气体为氮气、氩气、氦气中的一种或二种以上。
  12. 一种二氟磷酸锂，其由权利要求1～11中任一项所述的制备方法制得，其中，该二氟磷酸锂的纯度≥99.8％，游离酸的含量≤50ppm，优选≤25ppm。
  13. 根据权利要求12所述的二氟磷酸锂，其特征在于，水分的含量≤10ppm，Cl -的含量≤1ppm，优选≤0.8ppm，杂质金属离子的含量之和≤2ppm，优选≤1.5ppm。
  14. 一种非水电解液电池，其含有正极、负极和包含权利要求12或13所述的二氟磷酸锂的电解液。
  15. 权利要求12或13所述的二氟磷酸锂在制备非水电解液电池中的应用。
PCT/CN2021/129085 2021-05-20 2021-11-05 一种二氟磷酸锂及其制备方法和应用 WO2022242053A1 (zh)

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