WO2023142046A1 - 回收双氟磺酰亚胺锂的方法 - Google Patents

回收双氟磺酰亚胺锂的方法 Download PDF

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Publication number
WO2023142046A1
WO2023142046A1 PCT/CN2022/075012 CN2022075012W WO2023142046A1 WO 2023142046 A1 WO2023142046 A1 WO 2023142046A1 CN 2022075012 W CN2022075012 W CN 2022075012W WO 2023142046 A1 WO2023142046 A1 WO 2023142046A1
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Prior art keywords
lifsi
chromaticity value
lithium
manufacturing process
effluent
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PCT/CN2022/075012
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English (en)
French (fr)
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程思聪
黄起森
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宁德时代新能源科技股份有限公司
时代思康新材料有限公司
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Priority to EP22922572.7A priority Critical patent/EP4273096A4/en
Priority to PCT/CN2022/075012 priority patent/WO2023142046A1/zh
Publication of WO2023142046A1 publication Critical patent/WO2023142046A1/zh
Priority to US18/525,902 priority patent/US20240092639A1/en

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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
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/082—Compounds containing nitrogen and non-metals and optionally metals
    • C01B21/086—Compounds containing nitrogen and non-metals and optionally metals containing one or more sulfur atoms
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/082—Compounds containing nitrogen and non-metals and optionally metals
    • C01B21/087—Compounds containing nitrogen and non-metals and optionally metals containing one or more hydrogen atoms
    • C01B21/093—Compounds containing nitrogen and non-metals and optionally metals containing one or more hydrogen atoms containing also one or more sulfur atoms
    • C01B21/0935—Imidodisulfonic acid; Nitrilotrisulfonic acid; Salts thereof
    • 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
    • H01M10/54—Reclaiming serviceable parts of waste accumulators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D11/00—Solvent extraction
    • B01D11/04—Solvent extraction of solutions which are liquid
    • B01D11/0426—Counter-current multistage extraction towers in a vertical or sloping position
    • B01D11/0434—Counter-current multistage extraction towers in a vertical or sloping position comprising rotating mechanisms, e.g. mixers, rotational oscillating motion, mixing pumps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D11/00—Solvent extraction
    • B01D11/04—Solvent extraction of solutions which are liquid
    • B01D11/0446—Juxtaposition of mixers-settlers
    • B01D11/0457—Juxtaposition of mixers-settlers comprising rotating mechanisms, e.g. mixers, mixing pumps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D9/00—Crystallisation
    • B01D9/005—Selection of auxiliary, e.g. for control of crystallisation nuclei, of crystal growth, of adherence to walls; Arrangements for introduction thereof
    • B01D9/0054—Use of anti-solvent
    • 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
    • H01M10/0568—Liquid materials characterised by the solutes
    • 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
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/84—Recycling of batteries or fuel cells

Definitions

  • the application belongs to the field of chemical manufacturing, and more specifically relates to a method for recovering lithium bisfluorosulfonyl imide from the waste residue of the lithium bisfluorosulfonyl imide manufacturing process.
  • LiFSI Lithium bisfluorosulfonyl imide
  • Li + and FSI - have a The lower binding energy is conducive to the dissociation of Li + , so adding LiFSI to the electrolyte of the secondary battery can obtain higher conductivity.
  • LiFSI also has the characteristics of high thermal stability, wide electrochemical window and low corrosion rate. When LiFSI is applied to a power battery, it can improve the cycle performance and rate performance of the power battery, and is expected to be used as an electrolyte lithium salt in a lithium-ion battery.
  • LiFSI LiFSI-styrene-styrene-styrene-styrene-styrene
  • the purpose of this application is to provide a method for reclaiming lithium bisfluorosulfonyl imide from the waste residue of the LiFSI manufacturing process, so as to improve the yield of the LiFSI manufacturing process and realize the maximization of recycling , and reduce environmental pollution.
  • the application provides a method for recycling LiFSI, which includes:
  • the effluent is circulated to the LiFSI manufacturing process.
  • the present application monitors the chromaticity value of the effluent obtained by solid-liquid separation during the process of recovering LiFSI from the waste residue of the LiFSI manufacturing process using carbonate solvents, so as to know the relationship between LiFSI and other lithium salts such as sulfuric acid in the waste residue. Separation of lithium (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ). Only when the chromaticity value of the effluent is less than or equal to a predetermined reference chromaticity value, the effluent is recycled to the LiFSI manufacturing process, so that the residual LiFSI in the waste residue can be recycled to the manufacturing process, so as to maximize the recycling of LiFSI.
  • lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ) in recovered LiFSI-containing materials are fully removed.
  • lithium salts such as lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ) can also be recovered through further processing to realize the utilization of lithium resources. Make full use of it and reduce environmental pollution.
  • the reference chromaticity value is a value not greater than 300 Hazen, optionally not greater than 200 Hazen.
  • the carbonate solvent is diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), ethylene carbonate (EC) and propylene carbonate (PC) one or more of.
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • DMC dimethyl carbonate
  • EC ethylene carbonate
  • PC propylene carbonate
  • the mass ratio of the waste residue to the carbonate solvent is 1:(1-5), optionally 1:(2-4).
  • the solid-liquid separation is performed by centrifugation.
  • the solid-liquid separation is performed by filtration.
  • the primary recovery rate of bisfluorosulfonimide is not less than 85%.
  • the method for recovering LiFSI from LiFSI manufacturing process waste residue of the present application can improve the yield of LiFSI manufacturing process, realize the maximization of LiFSI recycling and reduce environmental pollution.
  • Fig. 1a and Fig. 1b are process flow charts of stage ⁇ of the LiFSI manufacturing process of the embodiment of the present application.
  • Fig. 2 is a process flow chart of the ⁇ stage of the LiFSI manufacturing process of the embodiment of the present application.
  • Fig. 3 is a process flow chart of the crystallization and drying process of the LiFSI manufacturing process of the embodiment of the present application.
  • Fig. 4 is a process flow diagram of the dissolution process of the LiFSI manufacturing process of the embodiment of the present application.
  • Fig. 5 is the process flow chart of the recovery method of embodiment 1.
  • ranges disclosed herein are defined in terms of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, ie any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2 ⁇ 4 and 2 ⁇ 5.
  • the numerical range “a ⁇ b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed in sequence, and may also include steps (b) and (a) performed in sequence.
  • steps (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c) , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b) and so on.
  • the "comprising” and “comprising” mentioned in this application means an open type or a closed type.
  • the “comprising” and “comprising” may mean that other components not listed may be included or included, or only listed components may be included or included.
  • the term "or” is inclusive unless otherwise stated.
  • the phrase "A or B"" means "A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • the application provides a method for reclaiming lithium bisfluorosulfonyl imide, which comprises:
  • the effluent is recycled to the lithium bisfluorosulfonyl imide manufacturing process.
  • LiFSI solution changes with the concentration of LiFSI and the presence of other lithium salts in the solution.
  • a solution of LiFSI in a carbonate-based solvent has a color value of about 40 at a concentration of about 30% by weight.
  • other lithium salts such as lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ) are present in the solution, the turbidity caused by these lithium salts will increase the color value of the solution. big.
  • LiFSI dissolved in carbonate solvents enters the effluent, and other lithium salts such as lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ) enter the solid residue.
  • Li 2 SO 4 lithium sulfate
  • LiF lithium fluoride
  • LiNH 2 SO 3 lithium sulfamate
  • the chromaticity value of the effluent obtained by solid-liquid separation can reflect the relationship between LiFSI and other lithium salts in the waste residue such as lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ).
  • the effluent is recycled to the LiFSI manufacturing process, so that the residual LiFSI in the waste residue can be recycled to the manufacturing process, so as to maximize the recycling of LiFSI.
  • impurities such as lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ) in the recovered effluent are fully removed.
  • lithium salts such as lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ) can also be recovered through further processing to realize the utilization of lithium resources. Make full use of it and reduce environmental pollution.
  • the present application can know LiFSI and other lithium salts in the waste residue such as lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ).
  • the reference chromaticity value is a value not greater than 300 Hazen, optionally not greater than 200 Hazen.
  • the chromaticity value of the effluent is low, the effluent is recycled to the LiFSI manufacturing process, which can ensure that the solid-liquid separation is fully carried out, the amount of LiFSI remaining in the solid residue is fully reduced, and the effluent is recycled to the LiFSI manufacturing process The content of LiFSI in the medium is increased, thereby improving the recycling of LiFSI.
  • the reference chromaticity value is not greater than 300 Hazen, the primary recovery rate of LiFSI from waste residue can reach more than 85%.
  • the reference chromaticity value is not greater than 200 Hazen, the primary recovery rate of LiFSI from waste residue can reach more than 92%.
  • the carbonate solvent can dissolve LiFSI, there is no specific limitation on the type of carbonate solvent, and those skilled in the art can choose according to actual needs.
  • the carbonate solvent is diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), ethylene carbonate (EC) and propylene carbonate (PC) one or more of.
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • DMC dimethyl carbonate
  • EC ethylene carbonate
  • PC propylene carbonate
  • the mass ratio of the waste residue to the carbonate solvent is 1:(1-5), optionally 1:(2-4).
  • the specific method of solid-liquid separation is not limited, and those skilled in the art can choose according to actual needs.
  • the solid-liquid separation is performed by centrifugation.
  • the solid-liquid separation is performed by filtration.
  • the primary recovery of bisfluorosulfonimide is not less than 85%.
  • lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ) in recovered LiFSI-containing materials are fully removed.
  • lithium salts such as lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ) can also be recovered through further processing to realize the utilization of lithium resources. Make full use of it and reduce environmental pollution.
  • the method for recovering LiFSI of the present application may be applied to a LiFSI manufacturing process including the following steps.
  • An exemplary LiFSI fabrication process is described below with reference to Figures 1a, 1b and 2-4.
  • the material composition mainly includes (SO 2 F-NH-SO 2 F) ⁇ Et 3 N, acetonitrile, triethylamine hydrogen fluoride salt, triethylamine (a small amount) and impurity ions.
  • the impurity ions mainly include F - , SO 4 2- , FSO 3 - and Cl - .
  • Evaporation put the product mixture (material ⁇ 1) into the evaporator to evaporate, and separate the acetonitrile solvent.
  • a falling film evaporator can be used to heat the material, a gas-liquid separator is used to separate the liquid from the vapor, and a condenser is used to condense the vapor of acetonitrile (containing a small amount of triethylamine), which is reused in the first step of synthesis.
  • the material composition mainly includes (SO 2 F-NH-SO 2 F) ⁇ Et 3 N, triethylamine hydrogen fluoride salt, acetonitrile (trace amount) and impurity ions.
  • the content of impurity ions in the oil phase obtained by extraction with a static mixer is about 5 to 30 times the content of impurity ions in the oil phase obtained by extraction with an extraction tower.
  • the ground is about 10 to 20 times.
  • the impurity ion is F - .
  • the stage of synthesis-evaporation-extraction can be called the ⁇ stage, and its specific flow can refer to the process flow diagram of Figure 1a (extraction tower scheme) or Figure 1b (static mixer scheme) of this application.
  • the reaction mixture obtained in Reaction 2 (material ⁇ 1) was dehydrated using a falling film evaporator C.
  • the ester solvent is used to carry water, and no chemical reaction is involved. Because the water absorption of lithium salt is very strong, it is unrealistic to reduce the water to the target requirement simply by evaporation. Adding a large amount of ester solvent can weaken the adsorption of lithium salt to water, and the water can be reduced to the target requirement during the process of evaporating the ester solvent while adding the ester solvent.
  • the ester solvent can be reused after being purified in the recovery section.
  • the ester solvent may include ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and the like.
  • LiFSI LiFSI is also decomposed, producing by-products such as lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ).
  • the solid by-products should be filtered or centrifuged before the next precipitation process (for example, using centrifugal sedimentation to remove solid residues, such as scraper centrifuges or disc centrifuges) to obtain waste residues.
  • Desolventization The material (material ⁇ 2) after evaporation and dehydration is desolvated in the falling film evaporator D and scraper evaporator E connected in series. Precipitation does not involve a reaction, but simply removes the ester solvent by evaporation. Because the lithium salt is dissolved in the ester solvent, if the ester solvent is not evaporated to a certain extent (such as from 60% to 65% to 30%), then the later stage cannot be crystallized or the crystallization rate is very low. The ester solvent can be reused after being purified in the recovery section. After the desolvation process, crude LiFSI (material ⁇ 3) with lower water content (eg, less than 3000 ppm) is obtained. In the LiFSI manufacturing process, the stage of alkalization-dehydration-desolventization can be called the ⁇ stage, and its specific process can refer to the process flow chart in Figure 2 of this application.
  • Crystallization means that when a substance is in a non-equilibrium state, another phase will be precipitated, and this phase will be precipitated in the form of crystals.
  • the material ⁇ 3 is passed into the crystallization kettle, and dichloromethane is added.
  • Dichloromethane is used to dissolve the ester solvent without dissolving LiFSI, so that LiFSI is supersaturated and precipitated in the ester solvent, and crystal nuclei grow. Pass the resulting mixture into a two-in-one device with filter and washing functions to wash off other impurities attached to the surface of the LiFSI crystal. After the crystallization liquid is purified by the recovery section, the ester solvent and dichloromethane can be reused.
  • waste residues can also be applied to the method for recovering LiFSI of the present application, and the recovered LiFSI can be recycled to any falling film evaporator.
  • the washed material is passed into the drying tank. After heating the nitrogen, pass it into the drying kettle. The material is fluidized under the action of stirring and air flow. In the large-area gas-solid two-phase contact, the moisture of the material evaporates rapidly, and the high-humidity nitrogen gas is discharged from the kettle to make the material meet the drying requirements.
  • the specific process of crystallization and drying process can refer to the process flow chart of Fig. 3 of the present application
  • the above-mentioned crystallization and drying steps can be omitted, and the material ⁇ 3 can be directly put into the dissolution process.
  • ester solvents such as ethyl methyl carbonate (EMC) or dimethyl carbonate (DMC) can be selected to dissolve the crystals in the above drying kettle (for the crystallization method) or the crude product ⁇ 3 (for different Crystallization method), acid removal (if the HF content in the detection solution exceeds the standard (such as standard HF ⁇ 50 ⁇ g/g), use LiOH to remove acid), water removal (if the moisture content in the detection solution exceeds the standard (such as standard moisture ⁇ 20 ⁇ g/g) ).
  • the solution passes through molecular sieves, adjusts the concentration, and stores (for example, barreling or tank car loading) after the filter core filters.
  • the specific flow process of the dissolving process can refer to the process flow diagram of Fig. 4 of the present application.
  • Ion exchange chromatography is used to measure the LiFSI content in the LiFSI manufacturing process waste residue and the solid residue obtained through the recovery process of the present invention, and then obtain the amount of LiFSI contained in the waste residue or solid residue.
  • a chromatograph (Dion ICS-900, American Thermo Fisher Scientific Co., Ltd.) equipped with an ion-exchange chromatographic column (analytical column Shodex IC SI-90 4E, 4.6 ⁇ 250mm, guard column Shodex IC SI-90G, 4.6 ⁇ 10mm) was used. ), measure the mass fraction of LiFSI in waste residue or solid residue relative to the total mass, and finally obtain the amount of LiFSI contained in waste residue or solid residue.
  • the working parameters of the ion-exchange chromatography are as follows: the temperature of the chromatographic column is 30-45°C, the detector is a DS5 conductivity detector, the eluent is 1.8mmol Na 2 CO 3 +1.8mmol NaHCO 3 +20% acetonitrile (V/V), the eluent is The washing liquid flow rate is 1.0 mL/min, the regeneration liquid is 20 mmol H 2 SO 4 , and the regeneration liquid flow rate is 1.0 mL/min.
  • Ion exchange chromatography was used to measure SO 4 2- content and NH 2 SO 3 - content in the effluent obtained by solid-liquid separation.
  • a chromatograph (Dion ICS-900, American Thermo Fisher Scientific Co., Ltd.) equipped with an ion-exchange chromatographic column (analytical column Shodex IC SI-90 4E, 4.6 ⁇ 250mm, guard column Shodex IC SI-90G, 4.6 ⁇ 10mm) was used. ), measure the SO 4 2- content and the NH 2 SO 3 - content in the effluent.
  • the working parameters of the ion-exchange chromatography are as follows: the temperature of the chromatographic column is 30-45° C., the detector is a DS5 conductivity detector, the eluent is 1.8 mmol Na 2 CO 3 +1.8 mmol NaHCO 3 +20% acetonitrile (V/V), and the eluent is The washing liquid flow rate is 1.0 mL/min, the regeneration liquid is 20 mmol H 2 SO 4 , and the regeneration liquid flow rate is 1.0 mL/min.
  • the waste residue from the LiFSI manufacturing process and the ester solvent DEC were stirred in a mixing tank at a mass ratio of 1:3. Open the feed valve of the ester solvent in the mixing tank to feed the DEC, open the 10m 3 mixing tank to stir, and then start to feed the waste residue.
  • the mass ratio of feed waste residue and DEC is 1:3.
  • a 2m 3 centrifuge PLGZ-30000, Wuxi Hongtong Petrochemical Equipment
  • the centrifuge After the feeding is completed, the centrifuge is turned on and centrifuged at a speed of 12000rpm, the speed-up time is 120s, and the centrifugation time is 30min. After the centrifugation process is completed, open the outlet valve of the centrifugal processor, open the vent valve of the storage tank for receiving the centrifuged liquid, and collect the centrifuged liquid.
  • the waste residue from the LiFSI manufacturing process contained 13.4 kg of LiFSI.
  • the amount of LiFSI in the solid slag leaving the centrifugal processor is only 0.4kg.
  • the primary recovery rate of LiSFI is 97.0%.
  • lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ) in the recovered effluent are fully removed, and the contents are all lower than 200ppm.
  • lithium sulfate (Li 2 SO 4 ), lithium fluoride (LiF) and lithium sulfamate (LiNH 2 SO 3 ) in the recovered effluent are fully removed, and the contents are all lower than 100ppm.
  • lithium sulfate Li 2 SO 4
  • lithium fluoride LiF
  • lithium sulfamate LiNH 2 SO 3
  • other lithium salts so as to realize the full utilization of lithium resources and further reduce environmental pollution.
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .
  • the method for recovering LiFSI of the present application can recover LiFSI from the waste residue of the LiFSI manufacturing process, thereby realizing the maximization of LiFSI recycling, increasing the yield of the LiFSI manufacturing process, and reducing environmental pollution.
  • the present application is suitable for industrial applications.

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Abstract

本申请提供了一种回收双氟磺酰亚胺锂的方法。本申请的方法包括：将来自双氟磺酰亚胺锂制造工艺的废渣与碳酸酯类溶剂混合，得到混合料；对所述混合料进行固液分离，得到出液和固渣；监测所述出液的色度值，并将所述出液的色度值与参考色度值比较；当所述出液的色度值大于所述参考色度值时，将所述出液循环至所述混合料中；和当所述出液的色度值小于等于所述参考色度值时，将所述出液循环至双氟磺酰亚胺锂制造工艺。

Description

回收双氟磺酰亚胺锂的方法 技术领域
本申请属于化工制造领域，更具体涉及从双氟磺酰亚胺锂制造工艺的废渣中回收双氟磺酰亚胺锂的方法。
背景技术
双氟磺酰亚胺锂(化学式Li[N(SO 2F) 2]，以下简称为LiFSI)是一种重要的含氟锂盐，由于其特殊的分子结构，Li +与FSI -之间具有较低的结合能，有利于Li +的解离，因而在二次电池的电解液中添加LiFSI，能获得较高的电导率。同时LiFSI还具有热稳定性高、电化学窗口较宽、腐蚀速率较低的特性。当LiFSI应用于动力电池中时，可以改善动力电池的循环性能以及倍率性能，有望在锂离子电池中用作电解质锂盐。
目前，LiFSI由于合成工艺条件的限制导致其生产成本高昂，现有的制造工艺存在着原料稀缺、工艺繁琐、流程较长、产品转化率低、能耗较大和环境污染等缺点。另外，作为锂离子二次电池电解质，需要满足高纯度、无水等苛刻要求。LiFSI中残余的水分通过升温带水、干燥除水直至分解都很难彻底除去，或者即使能除去也会损失较大的收率。
因此，如何从LiFSI制造工艺的废渣中尽可能地回收残余的LiFSI，以提高LiFSI制造工艺的收率，是本领域技术人员急需解决的问题。
发明内容
鉴于背景技术中存在的上述问题，本申请的目的在于提供一种从LiFSI制造工艺的废渣中回收双氟磺酰亚胺锂的方法，以提高LiFSI制造工艺的收率，实现回收利用的最大化，并且减少环境污染。
为实现上述目的，在一方面，本申请提供一种回收LiFSI的方法，其包括：
将来自LiFSI制造工艺的废渣与碳酸酯类溶剂混合，得到混合料；
对所述混合料进行固液分离，得到出液和固渣；
监测所述出液的色度值，并将所述出液的色度值与参考色度值比较；
当所述出液的色度值大于所述参考色度值时，将所述出液循环至所述混合料中；和
当所述出液的色度值小于等于所述参考色度值时，将所述出液循环至LiFSI制造工艺。
由此，本申请通过在利用碳酸酯类溶剂从LiFSI制造工艺的废渣中回收LiFSI的过程中，监测固液分离得到的出液的色度值，能够获知LiFSI与废渣中的其他锂盐例如硫酸锂 (Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)的分离情况。只有当出液的色度值小于等于预定的参考色度值时，将出液循环至LiFSI制造工艺，能够将废渣中残余的LiFSI回收到制造工艺中，以实现LiFSI回收利用的最大化。而且，回收的含LiFSI物料中硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)等杂质被充分地去除。从回收工艺得到的固渣中，还可以通过进一步处理回收硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)等锂盐，以实现锂资源的充分利用，并减少环境污染。
在任意实施方式中，所述参考色度值是不大于300Hazen的数值，可选为不大于200Hazen。
在任意实施方式中，所述碳酸酯类溶剂是碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸乙烯酯(EC)和碳酸丙烯酯(PC)中的一种或多种。
在任意实施方式中，所述废渣与所述碳酸酯类溶剂的质量比为1:(1～5)，可选为1:(2～4)。
在任意实施方式中，所述固液分离通过离心进行。
在任意实施方式中，所述固液分离通过过滤进行。
在任意实施方式中，双氟磺酰亚胺的一次回收率不小于85％。
本申请的从LiFSI制造工艺废渣中回收LiFSI的方法能够提高LiFSI制造工艺的收率，实现LiFSI回收利用的最大化，并且减少环境污染。
附图说明
图1a和图1b是本申请实施例的LiFSI制造工艺的α段工艺流程图。
图2是本申请实施例的LiFSI制造工艺的β段工艺流程图。
图3是本申请实施例的LiFSI制造工艺的析晶和干燥工序的工艺流程图。
图4是本申请实施例的LiFSI制造工艺的溶解工序的工艺流程图。
图5是实施例1的回收方法的工艺流程图。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的回收双氟磺酰亚胺锂的方法的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60～120和80～110的范围，理解为60～110和80～120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1～3、1～4、1～5、2～3、2～4和2～5。在本申请中，除非有其他说明，数值范围“a～b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0～5”表示本文中已经全部列出了“0～5”之间的全部实数，“0～5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B””表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
本申请提供一种回收双氟磺酰亚胺锂的方法，其包括：
将来自双氟磺酰亚胺锂制造工艺的废渣与碳酸酯类溶剂混合，得到混合料；
对所述混合料进行固液分离，得到出液和固渣；
监测所述出液的色度值，并将所述出液的色度值与参考色度值比较；
当所述出液的色度值大于所述参考色度值时，将所述出液循环至所述混合料中；和
当所述出液的色度值小于等于所述参考色度值时，将所述出液循环至双氟磺酰亚胺锂制造工艺。
虽然机理尚不明确，但本申请人意外地发现：LiFSI溶液的色度值随着LiFSI的浓度以及溶液中其他锂盐的存在而变化。在浓度约30重量％时，LiFSI在碳酸酯类溶剂中的溶液具有约40的色度值。当溶液中存在其他锂盐例如硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)时，这些锂盐导致的浑浊将使溶液的色度值增大。在对来自LiFSI制造工艺的废渣与碳酸酯类溶剂的混合料进行固液分离时，溶于碳酸酯类溶剂的LiFSI进入出液，其他锂盐例如硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)则进入固渣。在这个过程中，固液分离得越彻底，固渣中残留的LiFSI的量越少，出液中残留的其他锂盐例如硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)的含量越低，出液的色度值越小。因此，在利用碳酸酯类溶剂从LiFSI制造工艺的废渣中回收LiFSI的过程中，固液分离得到的出液的色度值，能够反映出LiFSI与废渣中的其他锂盐例如硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)的分离情况。
只有当出液的色度值小于等于预定的参考色度值时，将出液循环至LiFSI制造工艺，能够将废渣中残余的LiFSI回收到制造工艺中，以实现LiFSI回收利用的最大化。而且，回收的出液中硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)等杂质被充分地去除。从回收工艺得到的固渣中，还可以通过进一步处理回收硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)等锂盐，以实现锂资源的充分利用，并减少环境污染。
本申请通过在利用碳酸酯类溶剂从LiFSI制造工艺的废渣中回收LiFSI的过程中，监测固液分离得到的出液的色度值，能够获知LiFSI与废渣中的其他锂盐例如硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)的分离情况。
在一些实施方式中，所述参考色度值是不大于300Hazen的数值，可选为不大于200Hazen。当出液的色度值较低时，将出液循环至LiFSI制造工艺，能够保证固液分离得以充分进行，固渣中残留的LiFSI的量充分地减少，回收到LiFSI制造工艺中的出液中LiFSI的含量提高，从而提升对LiFSI的回收利用。当参考色度值不大于300Hazen时，从废渣中回收LiFSI的一次回收率可以达到85％以上。当参考色度值不大于200Hazen时，从废渣中回收LiFSI的一次回收率可以达到92％以上。
在本申请中，只要碳酸酯类溶剂能够使LiFSI溶解即可，对碳酸酯类溶剂的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。在一些实施方式中，所述碳酸酯 类溶剂是碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸乙烯酯(EC)和碳酸丙烯酯(PC)中的一种或多种。在本申请中，只要碳酸酯类溶剂能够使LiFSI溶解即可，对碳酸酯类溶剂的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。
在本申请中，只要废渣中的LiFSI能够充分溶解于碳酸酯类溶剂中即可，对废渣与碳酸酯类溶剂的质量比不做具体限制，本领域技术人员可以根据实际需求进行选择。在一些实施方式中，所述废渣与所述碳酸酯类溶剂的质量比为1:(1～5)，可选为1:(2～4)。
在本申请中，只要能够实现混合料的固液分离即可，对固液分离的具体方式不做限制，本领域技术人员可以根据实际需求进行选择。在一些实施方式中，所述固液分离通过离心进行。在一些实施方式中，所述固液分离通过过滤进行。
在一些实施方式中，双氟磺酰亚胺的一次回收率不小于85％。
在本申请的方法中，通过在利用碳酸酯类溶剂从LiFSI制造工艺的废渣中回收LiFSI的过程中，监测固液分离得到的出液的色度值，能够获知LiFSI与废渣中的其他锂盐例如硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)的分离情况。通过只有当出液的色度值小于等于预定的参考色度值时，将出液循环至LiFSI制造工艺，能够将废渣中残余的LiFSI回收到制造工艺中，以实现LiFSI回收利用的最大化。而且，回收的含LiFSI物料中硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)等杂质被充分地去除。从回收工艺得到的固渣中，还可以通过进一步处理回收硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)等锂盐，以实现锂资源的充分利用，并减少环境污染。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。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。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
LiFSI制造工艺
作为示例，本申请的回收LiFSI的方法可以应用于包括以下步骤的LiFSI制造工艺。下面参照附图1a、图1b和图2-4说明示例性的LiFSI制造工艺。
合成：使硫酰氟、氨气、三乙胺充分混合，使硫酰氟、氨气充分反应，而三乙胺既充当溶剂又参与反应。还可使用其他有机溶剂，如乙腈，作为反应的溶剂。主反应为SO 2F 2+NH 3+Et 3N→(SO 2F-NH-SO 2F)·Et 3N+Et 3N·(HF) n(n＝1～12)。
当反应釜内温度过高时，会发生以下副反应而影响收率：NH 3+SO 2F 2+Et 3N→NH 2-SO 2-NH 2(磺酰胺，固体)+Et 3N·(HF) n(三乙胺氟化氢盐，溶于CH 3CN中，n＝1～12)。反应后可采用例如5μm四氟过滤袋将副产物磺酰胺固体过滤掉。
合成工序后，物料组成主要包括(SO 2F-NH-SO 2F)·Et 3N、乙腈、三乙胺氟化氢盐、三乙胺(少量)以及杂质离子。所述杂质离子主要包含F -、SO 4 2-、FSO 3 -以及Cl -。
蒸发：将产物混合物(物料α1)通入蒸发器蒸发，分离出乙腈溶剂。可使用降膜蒸发器给物料加热，通过气液分离器使液体与蒸汽分离，再使用冷凝器冷凝蒸汽乙腈(含少量三乙胺)，回用于第一步的合成。
蒸发工序后，物料组成主要包括(SO 2F-NH-SO 2F)·Et 3N、三乙胺氟化氢盐、乙腈(微量)以及杂质离子。
萃取：将蒸发得到的浓缩液(物料α2)用水洗涤，将易溶于水的杂质(主要为三乙胺氟化氢盐)洗除。为此可使用两种方案：
方案一、萃取塔，底部进轻相(密度小)，上部出轻相，顶部进重相，底部出重相，中间搅拌为呈螺旋状；方案二、静态混合器和分层槽。萃取油相(物料α3)主要包含(SO 2F-NH-SO 2F)·Et 3N，而萃取水相(物料α水)主要包含三乙胺氟化氢盐和杂质离子(如F -、SO 4 2-、FSO 3 -、Cl -)。在采用萃取塔进行萃取的方案中，可实现对于杂质离子(例如F -)的更好地分离。在采用静态混合器进行萃取的方案中，通过静态混合器萃取而得到的油相中的杂质离子的含量为萃取塔萃取而得到的油相中的杂质离子含量的约5～30倍，可选地为约10～20倍。可选地，所述杂质离子为F -。在LiFSI制造工艺中，合成-蒸发-萃取的阶段可以称为α段，其具体流程可参照本申请图1a(萃取塔方案)或图1b(静态混合器方案)的工艺流程图。
碱化：将萃取后得到的萃取油相(物料α3)与氢氧化锂水溶液混合并充分反应。所述反应为反应2：(SO 2F-NH-SO 2F)·Et 3N+LiOH→(SO 2F-N-SO 2F) -Li ++Et 3N+H 2O。反应原理为强碱置换弱碱，LiOH碱性高于(SO 2F-NH-SO 2F)·Et 3N中的三乙胺，使得三乙胺被置换出。通过降膜蒸发器B除去三乙胺，同时LiOH与(SO 2F-NH-SO 2F)·Et 3N产生反应生成锂盐LiFSI。
脱水：将反应2得到的反应混合物(物料β1)使用降膜蒸发器C脱水。采用酯类溶剂带水，不涉及化学反应。因锂盐的吸水性非常强，若单纯靠蒸发来将水分降低至目标要求是不现实的。补加大量酯类溶剂可以减弱锂盐对水的吸附性，一边补加酯类溶剂，一边蒸发酯类溶剂的过程中可以将水分降低至目标要求。酯类溶剂经过回收段提纯处理后可以回用。酯类溶剂可包括碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)等。 脱水过程中LiFSI也在分解，生成副产物硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)等。在接下来的脱溶工序前要把固体副产物过滤或离心出来(例如使用离心沉降除固渣，如刮刀离心机或碟式离心机)，得到废渣。
来自脱水工序的废渣中，除上述副产物LiF、Li 2SO 4、氨基磺酸锂等，还不可避免地残留有少量的LiFSI产物。通过本申请的回收LiFSI的方法，可以将该废渣中残留的LiFSI回收到任一降膜蒸发器。
脱溶：将蒸发脱水后的物料(物料β2)在串联的降膜蒸发器D和刮板蒸发器E中进行脱溶。脱溶不涉及到反应，只是为了将酯类溶剂蒸发除去。因为锂盐是溶解于酯类溶剂的，若不将酯类溶剂蒸发到一定程度(如从60％～65％到30％)，则后期无法析晶或析晶率很低。酯类溶剂经过回收段提纯处理后可以回用。脱溶工序后得到含水量较低(例如低于3000ppm)的LiFSI粗品(物料β3)。在LiFSI制造工艺中，碱化-脱水-脱溶的阶段可以称为β段，其具体流程可参照本申请图2的工艺流程图。
在脱水和脱溶工序中，为了避免蒸发过程中LiFSI产品的分解，需不断加入氢氧化锂水溶液，保持pH在7～9之间，从而保持弱碱性体系，抑制LiFSI产品的分解。在脱溶工序中，由于加入氢氧化锂水溶液，引入了水分，因此脱溶过程中继续加入DEC，以将水带出。
析晶：析晶指的是当物质在处于非平衡态时，会析出另外的相，该相以晶体的形式被析出。将物料β3通入析晶釜，并加入二氯甲烷。利用二氯甲烷溶解酯类溶剂而不溶解LiFSI，使得LiFSI在酯类溶剂中过饱和析出，晶核生长。将得到的混合物通入带过滤洗涤功能的二合一设备中，将附着在LiFSI晶体表面的其他杂质洗掉。析晶液经过回收段提纯处理后，酯类溶剂和二氯甲烷可以回用。
尽管图2中并未示出，本领域技术人员可以根据实际需要，在脱水工序和/或析晶工序前将固体副产物过滤或离心出来，得到废渣。这些废渣同样可以应用于本申请的回收LiFSI的方法，回收的LiFSI可以循环至任一降膜蒸发器。
干燥：将洗涤后的物料通入干燥釜。将氮气加热后，通入干燥釜内。物料在搅拌和气流作用下形成流态化，在大面积气固两相接触中，物料水分快速蒸发，高湿度氮气排出釜内，使物料达到干燥要求。析晶和干燥工序的具体流程可参照本申请图3的工艺流程图
在LiFSI制造工艺中，可以不进行上述析晶和干燥步骤，而将物料β3直接投入溶解工序。
溶解：在溶解工序中，可根据需要选择用酯类溶剂如碳酸甲乙脂(EMC)或碳酸二甲 酯(DMC)溶解以上干燥釜中的晶体(对于析晶方法)或粗产物β3(对于不析晶方法)，除酸(若检测溶液中HF含量超标(如标准HF≤50μg/g)，用LiOH进行除酸)，除水(若检测溶液中水分含量超标(如标准水分≤20μg/g)。溶液过分子筛，调浓，过滤芯过滤后进行储存(例如装桶或装槽罐车)。溶解工序的具体流程可参照本申请图4的工艺流程图。
测量方法
(1)色度测量方法
首先，配制500Hazen的铂-钴标准溶液。具体而言，称取1.246g氯铂酸钾(K 2PtCl 6)和1.000g干燥的六水合氯化钴(CoCl 2·6H 2O)溶于100mL纯水中，加入100mL盐酸(ρ20＝1.19g/mL)，用纯水定容至1000mL，得到500Hazen铂-钴标准溶液。然后，根据公式V＝N/5，由500Hazen铂-钴标准溶液配制成具有不同色度值(例如，20Hezen、30Hezen、40Hezen等)的一系列标准溶液，其中N是要配制的标准溶液的色度(Hezen)，V是配制100mL该标准溶液所需要的500Hezen标准溶液的体积(mL)。
将配制好的一系列铂-钴标准溶液分别装入50mL比色管，按色度大小放置在比色架上。光源箱中放置白色背景，将25mL样品装入50mL比色管，放在光源箱底板中部位置。在标准光源箱中沿比色管轴线方向用目视法将待测样品与铂-钴标准溶液比较，取颜色深于待测样品的色度值最小的标准溶液的色度值记为样品的色度值。
(2)LiFSI的量的测量方法
采用离子交换色谱法(IC)，测定LiFSI制造工艺废渣以及通过本发明的回收工艺所得的固渣中的LiFSI含量，进而得到废渣或固渣中所含LiFSI的量。
具体而言，使用装配离子交换色谱柱(分析柱Shodex IC SI-90 4E，4.6×250mm，保护柱Shodex IC SI-90G，4.6×10mm)的色谱仪(戴安ICS-900，美国赛默飞)，测定废渣或固渣中LiFSI相对于总质量的质量分数，最终得到废渣或固渣中所含LiFSI的量。离子交换色谱工作参数如下：色谱柱温度为30～45℃，检测器为DS5电导检测器，淋洗液为1.8mmol Na 2CO 3+1.8mmol NaHCO 3+20％乙腈(V/V)，淋洗液流速为1.0mL/min，再生液为20mmol H 2SO 4，再生液流速为1.0mL/min。
(3)出液中杂质离子含量的测量方法
采用离子交换色谱法(IC)，测定经固液分离得到的出液中SO 4 2-含量和NH 2SO 3 -含量。
具体而言，使用装配离子交换色谱柱(分析柱Shodex IC SI-90 4E，4.6×250mm，保护柱Shodex IC SI-90G，4.6×10mm)的色谱仪(戴安ICS-900，美国赛默飞)，测定所述出液中的SO 4 2-含量和NH 2SO 3 -含量。离子交换色谱工作参数如下：色谱柱温度为30～45℃， 检测器为DS5电导检测器，淋洗液为1.8mmol Na 2CO 3+1.8mmol NaHCO 3+20％乙腈(V/V)，淋洗液流速为1.0mL/min，再生液为20mmol H 2SO 4，再生液流速为1.0mL/min。
实施例1
将来自LiFSI制造工艺的废渣和酯类溶剂DEC以1:3的质量比在混料釜中搅拌。打开混料釜的酯类溶剂进料阀进DEC，打开10m 3混料釜搅拌，再开始进废渣。进料的废渣和DEC的质量比为1:3。搅拌半小时后，使用2m 3离心机(PLGZ-30000，无锡弘通石化设备)对混料釜中的物料进行离心处理。具体而言，打开混料釜底阀和离心机进料泵的出口阀，启动离心机进料泵，开始给离心机进料。进料完成后，开启离心机，以12000rpm的转速进行离心处理，升速时间为120s，离心时间为30min。离心处理完成后，打开离心处理器出液阀，打开用于接收离心出液的储罐的放空阀，收集离心出液。
通过上文所述的色度测量方法，监测离心出液的色度，并与参考色度值40Hazen比较。如果色度＞40Hazen，将出液送到混料釜重新处理；如果出液的色度≤40Hazen)直接打回LiFSI制造工艺的降膜蒸发器(如图2中所示的降膜蒸发器B、C或D)。
实施例1的回收LiFSI的方法的具体流程可参照本申请图5的工艺流程图。
通过上文所述的测量方法，测得来自LiFSI制造工艺的废渣中含有13.4kg的LiFSI。经上述回收处理后，离开离心处理器的固渣中LiFSI的量仅有0.4kg。通过以下公式得出，LiSFI一次回收率为97.0％。
LiFSI一次回收率＝(1－处理后固渣中LiFSI的量/处理前废渣中LiFSI的量)×100％
另外，测定在离开离心处理器的出液中，SO 4 2-含量和NH 2SO 3 -含量分别为17.6ppm和15.6ppm。
实施例2～17
通过与实施例1中基本上相同的方法，将来自双氟磺酰亚胺制造工艺的废渣中残余的双氟磺酰亚胺锂回收到LiFSI制造工艺，不同之处仅在于，实施回收时采用的参考色度值如表1所示。
通过上文所述的测量方法，分别测量来自双氟磺酰亚胺制造工艺的废渣中含有的LiFSI的量、经上述回收处理后离开离心处理器的固渣中含有的LiFSI的量、离开离心处理器的出液中的SO 4 2-含量和NH 2SO 3 -含量，并计算LiFSI一次回收率。结果示于表1中。实施例1的实验结果也一并列于表1中。
表1
Figure PCTCN2022075012-appb-000001
从实施例1～17的结果可以看出，在利用DEC从LiFSI制造工艺的废渣中回收LiFSI的过程中，监测固液分离得到的出液的色度值，当参考色度值是不大于300Hazen的优选数值时，监测固液分离得到的出液的色度值，只有当出液的色度值小于等于优选的参考色度值时，将固液分离得到的出液循环至LiFSI制造工艺，能够将废渣中85％以上的LiFSI都回收到制造工艺中，进一步实现LiFSI回收利用的最大化。而且，回收的出液中硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)等杂质被充分地去除，含量均低于200ppm。
在实施例1～17中，当参考色度值是不大于200Hazen的进一步优选的数值时，监测固液分离得到的出液的色度值，只有当出液的色度值小于等于进一步优选的参考色度值时，将固液分离得到的出液循环至LiFSI制造工艺，能够将废渣中92％以上的LiFSI都回收到制造工艺中，更进一步实现LiFSI回收利用的最大化。而且，回收的出液中硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)等杂质被充分地去除，含量均低于100ppm。
本领域技术人员能够认识到，从本申请的回收工艺得到的固渣中，还可以通过进一步处理回收硫酸锂(Li 2SO 4)、氟化锂(LiF)和氨基磺酸锂(LiNH 2SO 3)等锂盐，以实现锂资源的充分利用，并进一步减少环境污染。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在 本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。
工业应用性
本申请的回收LiFSI的方法能够从LiFSI制造工艺的废渣中回收LiFSI，从而实现LiFSI回收利用的最大化，提高LiFSI制造工艺的收率，并且减少环境污染。因而，本申请适于工业应用。

Claims (7)

  1. 一种回收双氟磺酰亚胺锂的方法，其包括：
    将来自双氟磺酰亚胺锂制造工艺的废渣与碳酸酯类溶剂混合，得到混合料；
    对所述混合料进行固液分离，得到出液和固渣；
    监测所述出液的色度值，并将所述出液的色度值与参考色度值比较；
    当所述出液的色度值大于所述参考色度值时，将所述出液循环至所述混合料中；和
    当所述出液的色度值小于等于所述参考色度值时，将所述出液循环至双氟磺酰亚胺锂制造工艺。
  2. 根据权利要求1所述的方法，其中所述参考色度值是不大于300Hazen的数值，可选为不大于200Hazen。
  3. 根据权利要求1或2所述的方法，其中所述碳酸酯类溶剂是碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)和碳酸二甲酯(DMC)、碳酸乙烯酯(EC)、碳酸丙烯酯(PC)中的一种或多种。
  4. 根据权利要求1～3中任一项所述的方法，其中所述废渣与所述碳酸酯类溶剂的质量比为1:(1～5)，可选为1:(2～4)。
  5. 根据权利要求1～4中任一项所述的方法，其中所述固液分离通过离心进行。
  6. 根据权利要求1～4中任一项所述的方法，其中所述固液分离通过过滤进行。
  7. 根据权利要求1～6中任一项所述的方法，其中双氟磺酰亚胺的一次回收率不小于85％。
PCT/CN2022/075012 2022-01-29 2022-01-29 回收双氟磺酰亚胺锂的方法 WO2023142046A1 (zh)

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