WO2023142023A1 - 双氟磺酰亚胺锂及其制备方法、电解液和二次电池 - Google Patents

双氟磺酰亚胺锂及其制备方法、电解液和二次电池 Download PDF

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WO2023142023A1
WO2023142023A1 PCT/CN2022/074931 CN2022074931W WO2023142023A1 WO 2023142023 A1 WO2023142023 A1 WO 2023142023A1 CN 2022074931 W CN2022074931 W CN 2022074931W WO 2023142023 A1 WO2023142023 A1 WO 2023142023A1
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stream
lithium
optionally
water
triethylamine
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PCT/CN2022/074931
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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 PCT/CN2022/074931 priority Critical patent/WO2023142023A1/zh
Priority to EP22922545.3A priority patent/EP4273095A4/en
Publication of WO2023142023A1 publication Critical patent/WO2023142023A1/zh
Priority to US18/231,255 priority patent/US20230387467A1/en

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    • 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
    • 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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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

Definitions

  • the present application relates to a method for preparing lithium bisfluorosulfonyl imide, and lithium bisfluorosulfonyl imide prepared by the method, including an electrolyte of lithium bisfluorosulfonyl imide prepared by the method and its secondary battery.
  • LiFSI Due to its special molecular structure, LiFSI can be added to the electrolyte to obtain higher conductivity. At the same time, LiFSI also has the characteristics of high thermal stability, wide electrochemical window, and low corrosion rate. Especially in power batteries, it can improve the cycle performance and rate performance of power batteries. Excellent choice.
  • the synthesis and purification of LiFSI in the prior art has many problems in industrialized large-scale production.
  • the synthesis process is cumbersome, the process is long, the product conversion rate is low, and the consumption of raw and auxiliary materials is large and difficult to recycle, so the economy is not high.
  • the present invention aims to solve at least some of these problems, and proposes a new continuous method for producing LiFSI, so that the purity and moisture content of LiFSI can reach battery-level standards, the production cost is low, the three wastes are less, and it is suitable for industrial production.
  • This application is made in view of the above problems, and its purpose is to provide a method for preparing lithium bisfluorosulfonyl imide to solve the problems of low product purity, high moisture content, high production cost, and three wastes involved in the preparation of LiFSI in the prior art. many questions.
  • the application provides a method for preparing lithium bisfluorosulfonyl imide, and lithium bisfluorosulfonyl imide prepared by said method, including bisfluorosulfonyl imide prepared by said method Lithium electrolyte and its secondary battery.
  • the first aspect of the present application provides a method for preparing lithium bisfluorosulfonyl imide, comprising the following steps:
  • Evaporation step Evaporate stream ⁇ 1 to obtain stream ⁇ 2 comprising (SO 2 F-NH-SO 2 F) ⁇ Et 3 N and triethylamine hydrogen fluoride salt, and evaporate the evaporated solvent and triethylamine optional work-up before recycling to step (a);
  • step (c) Extraction step: the stream ⁇ 2 obtained in step (b) is washed with water in an extraction tower or a static mixer to obtain an oil phase ⁇ 3 comprising (SO 2 F-NH-SO 2 F) ⁇ Et 3 N and comprising The water phase ⁇ water of triethylamine hydrogen fluoride salt, separates the oil phase ⁇ 3;
  • Step (f) Precipitation step: adding the stream ⁇ 2 obtained in step (e) and the ester solvent into the evaporator, and evaporating to obtain the crude lithium bisfluorosulfonyl imide ⁇ 3;
  • step (g) Crystallization step: pump the crude lithium bisfluorosulfonyl imide ⁇ 3 obtained in step (f) into a crystallization kettle, and add dichloromethane to precipitate lithium bisfluorosulfonyl imide crystals.
  • LiFSI with high purity and low moisture can be obtained by applying the preparation method of the present application.
  • the preparation method can be produced continuously, has low production cost and less three wastes, and has high industrial application value.
  • the method further includes the following steps:
  • step (h) Drying step: purging the lithium bisfluorosulfonyl imide crystals precipitated in step (g) with an inert gas in a desiccator to obtain powdery lithium bisfluorosulfonyl imide crystals with a water content lower than 50 ppm.
  • step (a) sulfuryl fluoride: ammonia: the molar ratio of triethylamine is (1.5-3.5): 1: (1-6), optionally (2 -3):1:(1-5).
  • the solvent is selected from acetonitrile, propionitrile, isopropionitrile, diethyl ether, propyl ether, isopropyl ether, tetrahydrofuran, acetone, methyl ethyl ketone, methyl isonitrile Butyl ketone, methyl pyrrolidone or a mixture of any two or more thereof, preferably acetonitrile.
  • step (a) wherein, the reaction temperature of the reaction is not higher than 25°C, optionally 3-20°C; and/or, the reaction pressure of the reaction is not Higher than 0.4MPa, optionally not higher than 0.25MPa.
  • a step of filtering stream ⁇ 1 is also included to remove by-product sulfonamide (NH 2 -SO 2 -NH 2 ) solids, for example Use a PTFE filter bag with a pore size of 5 ⁇ m to 20 ⁇ m for filtration.
  • step (b) stream al is evaporated using a falling film evaporator.
  • step (c) the aqueous phase containing triethylamine hydrogen fluoride salt is sent to recovery treatment, and the triethylamine obtained after the aqueous phase is alkalized and purified can be recycled use.
  • step (d) the oil phase ⁇ 3 is mixed and stirred with an aqueous solution of lithium hydroxide, and reacted for 0.5-3 hours, optionally 1-2 hours.
  • step (d) the condensed liquid obtained by evaporating stream ⁇ 1-1 is subjected to static liquid separation, the upper layer liquid is an aqueous solution of triethylamine, and the upper layer liquid is sent to recovery Processing; the lower layer liquid is condensed water, and the lower layer liquid is recovered to prepare the lithium hydroxide aqueous solution required for the alkalization step.
  • step (d) wherein the volume ratio of stream ⁇ 3 to the aqueous solution of lithium hydroxide is optionally (0.8-5): 1, optionally (1-1.2) :1.
  • steps (e) and (f) the aqueous solution of the condensed ester solvent is sent to recovery treatment.
  • the stream ⁇ 2 obtained in step (e) contains 0.1% to 2% by volume of water and 20% to 40% by volume of ester solvent.
  • the crude lithium bisfluorosulfonyl imide ⁇ 3 obtained in step (f) has a water content of 2000 ppm to 4000 ppm, preferably 3000 ppm.
  • steps (e) and (f) are performed in the same evaporator, or steps (e) and (f) are performed in different evaporators.
  • step (d) optionally, the following side reactions exist during step (d) and step (e):
  • the by-product lithium compounds are removed by centrifugal filtration, such as by a scraper centrifuge or a disc centrifuge, prior to the desolventization step (f).
  • the ester solvents are each independently selected from the group having a boiling point greater than 70°C, preferably greater than 80°C, preferably 100°C-130°C and Organic solvent immiscible with water.
  • the ester solvent contains carbonate solvents, including ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethylene propyl carbonate , butylene carbonate, fluoroethylene carbonate or a mixture of two or more thereof.
  • the ester solvent contains a carboxylate solvent, such as propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate or two or more thereof mixture. Further optionally, the ester solvent is at least one selected from ethyl methyl carbonate, dimethyl carbonate and diethyl carbonate.
  • carboxylate solvent such as propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate or two or more thereof mixture.
  • the ester solvent is at least one selected from ethyl methyl carbonate, dimethyl carbonate and diethyl carbonate.
  • the evaporation temperature in the alkalization step (d) is controlled at 30°C-40°C, optionally 30°C-35°C; and/or, the evaporation temperature in the dehydration step (e) The temperature is controlled at 40°C-55°C, optionally 45°C-50°C; and/or, the evaporation temperature in the precipitation step (f) is controlled at 60°C-80°C, optionally 65°C-75°C.
  • an aqueous solution of lithium hydroxide is added so that the pH of the mixture in the evaporator is kept in the range of 7-9, preferably 8 -9 range.
  • the concentration of the lithium hydroxide aqueous solution is 1mol/L to 15mol/L, optionally 2mol/L to 10mol/L.
  • the material containing the ester solvent obtained in the crystallization step (g), dichloromethane and lithium bisfluorosulfonimide crystals is included
  • the flow is pumped into the two-in-one equipment with the function of filtering and washing, in which the crystallization liquid containing diethyl carbonate and dichloromethane is sent to recovery treatment, and the remaining lithium bisfluorosulfonimide crystals fall into the two-in-one equipment by gravity In the drying kettle on the lower floor of the equipment.
  • the dried and condensed liquid phase comprises dichloromethane and water, and the liquid phase is recycled to the crystallization step (g).
  • the dichloromethane used in the crystallization step (g) has a water content ⁇ 200 ppm.
  • the method further includes (i) a potting step, wherein the powdered lithium bisfluorosulfonyl imide crystals obtained in step (h) are dissolved in a solvent
  • a potting step wherein the powdered lithium bisfluorosulfonyl imide crystals obtained in step (h) are dissolved in a solvent
  • acid removal, water removal and filtration the following standards are met: HF ⁇ 50 ⁇ g/g, water content ⁇ 20 ⁇ g/g.
  • the solvent used for dissolving in step (i) is the same as the ester solvent used in step (e) and step (f).
  • the second aspect of the present application also provides lithium bisfluorosulfonyl imide, which is prepared by the method of the first aspect of the present application.
  • the third aspect of the present application also provides an electrolyte solution, including the lithium bisfluorosulfonyl imide prepared by the method of the first aspect of the present application.
  • the fourth aspect of the present application also provides a secondary battery, including the electrolytic solution according to the third aspect of the present application.
  • the electrolyte solution or secondary battery of the present application includes the lithium bisfluorosulfonyl imide prepared by the first aspect of the present application, and therefore has at least the same advantages as the method described in the first aspect of the present application.
  • Figure 1 shows a schematic flow diagram of the ⁇ -stage process (synthesis ⁇ evaporation ⁇ extraction), in which the extraction process uses an extraction tower.
  • Figure 2 shows a schematic flow chart of the ⁇ -stage process (synthesis ⁇ evaporation ⁇ extraction), in which a static mixer is used in the extraction process.
  • Fig. 3 is a schematic flow chart of the ⁇ stage process (basification ⁇ dehydration ⁇ precipitation).
  • Fig. 4 is a schematic flow chart of the crystallization drying process.
  • Figure 5 is a schematic flow chart of the canning process.
  • 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 in any combination, 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 contemplated. Additionally, 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 mean open or closed.
  • 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 of the following: 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 process route of the present invention is: synthesis ⁇ evaporation ⁇ extraction ⁇ alkalization ⁇ dehydration ⁇ precipitation ⁇ crystallization ⁇ drying ⁇ canning (the canning step is an optional process). Each step will be further described below.
  • step (a) the molar ratio of sulfuryl fluoride: ammonia: triethylamine is (1.5-3.5): 1: (1-6), optionally (2-3): 1: (1-5).
  • the ammonia gas is excessive, side reactions are likely to occur, making the reaction mixture turbid, resulting in difficulty in subsequent filtration.
  • step (a) acetonitrile and triethylamine are first added in the reaction device, and then a part of ammonia gas (preferably 2-15% of the total amount of ammonia gas, preferably 3-10%) is fed into the reaction device. , and finally feed ammonia and sulfuryl fluoride simultaneously for reaction.
  • a part of ammonia gas preferably 2-15% of the total amount of ammonia gas, preferably 3-10%
  • the solvent is selected from acetonitrile, propionitrile, isopropionitrile, diethyl ether, propyl ether, isopropyl ether, tetrahydrofuran, acetone, methyl ethyl ketone, methyl isobutyl ketone, Methylpyrrolidone or a mixture of any two or more thereof, preferably acetonitrile.
  • reaction in (a) can be carried out in any suitable manner.
  • the reaction can be carried out in a batch reactor or in at least one semi-continuously operated reactor or at least one continuously operated reactor.
  • the reaction temperature of the reaction is not higher than 25°C, optionally 3°C-20°C; and/or, the reaction pressure of the reaction is not higher than 0.4MPa, Optionally not higher than 0.25MPa. Excessive temperature and pressure will lead to more side reactions. In addition, if the temperature is too high, the solvent will easily vaporize, resulting in excessive pressure in the reactor and affecting safe production.
  • step (a) when the molar ratio of sulfuryl fluoride to ammonia in step (a) is (1.5-4): 1, preferably (2-3): 1, particularly good yield and color are obtained.
  • step (a) at the end of the reaction, an % of triethylamine hydrogen fluoride salt and 0 to 10% by weight of stream ⁇ 1 of triethylamine.
  • the ⁇ 1 stream can be filtered more than once, preferably 2-5 times, optionally 2 times, and the pore size of the filter bag used for the downstream filtration is smaller than the pore size of the upstream filter bag.
  • stream ⁇ 1 is evaporated to obtain stream ⁇ 2 comprising (SO 2 F—NH—SO 2 F) ⁇ Et 3 N and triethylamine hydrogen fluoride salt, and the evaporated
  • the solvent and triethylamine are optionally worked up before recycling to step (a).
  • a step of filtering the stream ⁇ 1 is also included between steps (a) and (b) to remove the by-product sulfonamide (NH 2 -SO 2 -NH 2 ) solid, for example, using a pore size of 5 ⁇ m to 20 ⁇ m, optional 6 ⁇ m to 15 ⁇ m PTFE filter bag for filtration.
  • step (b) stream al is evaporated using a falling film evaporator.
  • the heat exchange medium used in the falling film evaporator can be hot water, and the temperature of the hot water tank is 50°C to 100°C, preferably 60°C to 80°C.
  • the evaporation may be performed using one or two or more evaporators connected in series, preferably falling film evaporators.
  • the gas stream evaporated by the evaporator is condensed using a condenser, preferably a condenser comprising a pre-condenser and a post-condenser, the pre-condensing
  • a condenser preferably a condenser comprising a pre-condenser and a post-condenser, the pre-condensing
  • the condenser is condensed with water at 0°C
  • the post-stage condenser is condensed with water at -15°C.
  • the internal pressure of the evaporator is -0.01MPa to -0.1MPa.
  • the water used in the condenser contains 30-50% by weight of antifreeze, and the antifreeze can be ethylene glycol or glycerin.
  • the evaporation in step (b) can be performed in one or more evaporators.
  • stream ⁇ 2 comprises 60% to 80% by weight of (SO 2 F—NH—SO 2 F) ⁇ Et 3 N and 20% to 40% by weight of triethyl Amine hydrogen fluoride salt.
  • the stream ⁇ 2 obtained in the step (b) is washed with water in an extraction tower or a static mixer to obtain (SO 2 F-NH-SO 2 F) ⁇ Et 3 N
  • the oil phase ⁇ 3 and the aqueous phase ⁇ water comprising triethylamine hydrogen fluoride salt, the oil phase ⁇ 3 is separated.
  • step (c) the mass ratio of the water entering the extraction tower or the static mixer to the stream ⁇ 2 is 1:(1-2), optionally 1:(1.1-1.5).
  • the oil phase ⁇ 3 further comprises 5% to 15% by weight of water.
  • the alpha water comprises 75% to 80% by weight water and 20% to 25% by weight triethylamine hydrogen fluoride salt.
  • step (c) the aqueous phase containing triethylamine hydrogen fluoride salt is sent to recovery treatment, and the triethylamine obtained after the aqueous phase is alkalized and purified can be recycled.
  • the water phase also contains impurity ions (such as F-, SO 4 2- , FSO 3 - or Cl-). After alkalization and purification in the recovery section, triethylamine can be recycled and sold by KF Additional economic benefits can be generated.
  • the extraction tower can be an extraction tower commonly used in the art, such as a packed extraction tower, a sieve tray extraction tower, a rotating disk extraction tower, a vibrating sieve tray, a multistage centrifugal extraction tower, preferably a rotating disk extraction tower.
  • the extraction step is in an extraction tower (stirring frequency 15 ⁇ 1HZ; the weight ratio of deionized water used therein to ⁇ 2 is 1: (1-1.6), preferably 1: (1-1.4)) Carry out, wherein the light phase (low density) enters from the side bottom of the extraction tower, discharges from the top of the extraction tower; better, better cleaning and separation).
  • an extraction tower for extraction can achieve better separation of impurity ions (such as F ⁇ ).
  • the F ion content in ⁇ 3 is ⁇ 1000ppm, and the subsequent alkalization process needs to consume more LiOH; however, after being treated by an extraction tower, the F ion content in ⁇ 3 is ⁇ 100ppm.
  • the determination of F ion content and water content in the stream is a method well known in the art, such as the determination of F ion content by alizarin complex colorimetry and the determination of water content by Karl Fischer method.
  • step (c) stream a2 from step (b) is washed with water in an extraction column.
  • the static mixer may be a static mixer conventionally used in the art, such as a pipeline static mixer.
  • a static mixer the resulting mixture needs to be pumped into a layering tank for static layering, usually for 1-10 hours, preferably 2-6 hours.
  • the water used herein is deionized water, which can minimize the type and content of impurities contained in the final product.
  • step (d) of the present invention the oil phase ⁇ 3 obtained in step (c) is sent to the evaporator, and after being mixed with the aqueous solution of lithium hydroxide, a mixture stream ⁇ 1-1 is obtained, and then the stream ⁇ 1-1 was evaporated under reduced pressure to obtain stream ⁇ 1-2 containing lithium bisfluorosulfonyl imide.
  • step (d) is carried out according to the following reaction formula:
  • the principle of the reaction is that a strong base replaces a weak base, and the alkalinity of LiOH is higher than that of triethylamine in (SO 2 F-NH-SO 2 F) ⁇ Et 3 N, so that triethylamine is replaced, and triethylamine is removed by falling film evaporation.
  • amine while LiOH reacts with (SO 2 F-NH-SO 2 F) ⁇ Et 3 N to generate lithium bisfluorosulfonyl imide (abbreviated as LiFSI).
  • step (d) before evaporating the stream ⁇ 1-1, the oil phase ⁇ 3 is mixed and stirred with the aqueous solution of lithium hydroxide, and reacted for 0.5-3 hours, optionally 1-2 hours .
  • the lithium hydroxide aqueous solution has a concentration of 1 mol/L to 15 mol/L, optionally 2 mol/L to 10 mol/L.
  • step (d) the condensed liquid obtained by evaporating stream ⁇ 1-1 is subjected to standing liquid separation, the upper layer liquid is triethylamine aqueous solution, and the upper layer liquid is sent to recovery treatment; the lower layer liquid For condensed water, the lower layer liquid is reclaimed for preparing the lithium hydroxide aqueous solution required for the alkalization step.
  • step (d) the volume ratio of the stream ⁇ 3 to the lithium hydroxide aqueous solution is (0.8-5):1, optionally (1-1.2):1.
  • step (d) an aqueous solution of lithium hydroxide is added such that the pH of the mixture in the evaporator is maintained in the range of 7-9, preferably in the range of 8-9.
  • step (d) the evaporation is performed using a falling film evaporator, and the evaporation temperature is controlled at 30-40°C, optionally 30-35°C.
  • the evaporation in step (d) can be performed in one or more evaporators.
  • step (d) wherein stream ⁇ 1-2 comprises 70 to 90% by weight lithium bisfluorosulfonyl imide and 5 to 25% by weight water, the balance being LiF, Li 2 SO 4 and lithium sulfamate, etc., based on 100% by weight of stream ⁇ 1-2.
  • the stream ⁇ 1-2 containing lithium bisfluorosulfonyl imide and the ester solvent are added to the evaporator, and evaporated to obtain the stream ⁇ 2 containing lithium bisfluorosulfonyl imide .
  • step (e) the condensed aqueous solution of the ester solvent is sent to recovery treatment.
  • step (e) the stream ⁇ 1-2 is mixed with the ester solvent at a volume ratio of 1:(0.4-0.8), preferably 1:(0.5-0.7).
  • the obtained stream ⁇ 2 further contains 0.1% to 2% by volume of water and 20% to 40% by volume of ester solvent.
  • the evaporator is a falling film evaporator, and the evaporation temperature is controlled at 40-55°C, optionally 45-50°C.
  • the evaporation in step (e) can be performed in one or more evaporators.
  • lithium salts are very hygroscopic, it is difficult to reduce the moisture to the required level by evaporation alone.
  • the adsorption of lithium salts to water can be weakened by adding a large amount of ester organic solvents (such as carbonates and carboxylates, preferably DEC and EMC) that are insoluble in water and preferably have a boiling point greater than water (for example, 100-130 ° C).
  • ester organic solvents such as carbonates and carboxylates, preferably DEC and EMC
  • Evaporating and dehydrating while adding the ester organic solvent can reduce the moisture to the required content, for example, less than 3000ppm.
  • the mixture of ester organic solvent and water obtained by condensation can be recycled after being purified and treated in the recovery section.
  • by-product lithium compounds eg NH 2 SO 3 Li, Li 2 SO 4 , 2LiF
  • centrifugation eg by scraper centrifuge or disc centrifuge.
  • the ester solvent is mixed with the stream ⁇ 1-2, and the pH of the mixture is kept between 7-9 while evaporating and dehydrating, and optionally centrifugally filtered to obtain Stream ⁇ 2 of lithium bisfluorosulfonyl imide, 20-40% by weight of ester solvent and 0.2-1.5% by weight of water.
  • step (e) the pH of the mixture is maintained at 7-9, preferably 8-9 during evaporation by adding aqueous lithium hydroxide solution.
  • the lithium hydroxide aqueous solution has a concentration of 1 mol/L to 15 mol/L, optionally 2 mol/L to 10 mol/L.
  • the stream ⁇ 2 obtained in the step (e) and the ester solvent are added to an evaporator, and evaporated to obtain the crude lithium bisfluorosulfonyl imide ⁇ 3.
  • by-product lithium compounds such as NH2SO3Li , Li2SO4 , and LiF are optionally removed by centrifugation, If removed by a scraper centrifuge or disc centrifuge, stream ⁇ 2-1 is obtained.
  • step (f) the stream ⁇ 2 or stream ⁇ 2-1 is mixed with the ester solvent in a volume ratio of 1:(0.1-0.4), preferably 1:(0.2-0.3) to mix.
  • the evaporator is a scraped evaporator, and the evaporation temperature is controlled at 60-80°C, optionally 65-75°C.
  • the evaporation in step (f) can be performed in one or more evaporators.
  • the lithium bisfluorosulfonyl imide ⁇ 3 obtained in step (f) has a water content of 2000 ppm to 4000 ppm, preferably a water content of 3000 ppm.
  • the lithium bisfluorosulfonyl imide ⁇ 3 comprises 80 wt%-90 wt% lithium bisfluorosulfonyl imide and 10 wt%-20 wt% ester solvent.
  • step (f) the condensed aqueous solution of the ester solvent is sent to recovery treatment.
  • the pH of the evaporated mixture is maintained in the range of 7-9, preferably 8-9 by adding aqueous lithium hydroxide solution.
  • the lithium hydroxide aqueous solution has a concentration of 1 mol/L to 15 mol/L, optionally 2 mol/L to 10 mol/L.
  • steps (e) and (f) are optionally performed in the same evaporator, or steps (e) and (f) are performed in different evaporators.
  • the crude lithium bisfluorosulfonyl imide ⁇ 3 obtained in the step (f) is pumped into a crystallization kettle, and dichloromethane is added to precipitate lithium bisfluorosulfonyl imide crystals.
  • the dichloromethane used in the crystallization step (g) has a water content ⁇ 200 ppm. If the water content of dichloromethane is too high, otherwise it will affect the production of lithium bisfluorosulfonimide crystal nuclei, and the crystals are too small and too fine to be dried easily.
  • the material containing ester solvent, dichloromethane and lithium bisfluorosulfonimide crystals obtained in the crystallization step (g) is included
  • the flow is pumped into the two-in-one equipment with the function of filtering and washing, in which the crystallization liquid containing diethyl carbonate and dichloromethane is sent to recovery treatment, and the remaining lithium bisfluorosulfonimide crystals fall into the two-in-one equipment by gravity In the drying kettle on the lower floor of the equipment.
  • the lithium bisfluorosulfonyl imide crystals precipitated in the step (g) are purged with an inert gas in a desiccator to obtain powdery bisfluorosulfonyl Lithium imide crystals.
  • step (h) the dried condensed liquid phase comprising dichloromethane and water is recycled to the crystallization step (g).
  • the method of the present invention also includes (i) a canning step after the (h) drying step, wherein the powdery lithium bisfluorosulfonyl imide crystals obtained after the drying step are dissolved in a solvent and optionally deacidified and dehydrated And after filtering, reach the following standards: HF ⁇ 50 ⁇ g/g, water content ⁇ 20 ⁇ g/g. If it is detected that the HF content in the solution exceeds the standard (for example, HF>50 ⁇ g/g), lithium hydroxide is used to remove the acid. If it is detected that the water content in the solution exceeds the standard (for example, water content > 20 ⁇ g/g), use molecular sieves to remove water.
  • a canning step after the (h) drying step wherein the powdery lithium bisfluorosulfonyl imide crystals obtained after the drying step are dissolved in a solvent and optionally deacidified and dehydrated And after filtering, reach the following standards: HF ⁇ 50 ⁇ g/g, water content ⁇ 20
  • the solvent used for dissolving in step (i) is the same as the ester solvent used in step (e) and step (f).
  • the second aspect of the present application also provides lithium bisfluorosulfonyl imide, which is prepared by the method of the first aspect of the present application.
  • the third aspect of the present application also provides an electrolyte solution, including the lithium bisfluorosulfonyl imide prepared by the method of the first aspect of the present application.
  • the fourth aspect of the present application also provides a secondary battery, including the electrolyte solution of the third aspect of the present application.
  • the electrolyte solution or secondary battery of the present application includes the lithium bisfluorosulfonyl imide prepared by the first aspect of the present application, and therefore has at least the same advantages as the method described in the first aspect of the present application.
  • the raw and auxiliary materials used in the LiFSI synthesis process route of the present invention are relatively common chemical products, the production cost is low, there is no high temperature and high pressure in the reaction process, and the exothermic heat of the front-end synthesis reaction is cooled by a refrigerator to ensure the reaction at low temperature and the reaction is safe
  • the coefficient is high.
  • the production cost of LiFSI is low, the three wastes are less, the purity is high, the raw materials can be fully recycled, and the by-products can be purified to generate additional economic benefits, which is suitable for industrial production.
  • the consumption of raw and auxiliary materials is reduced, the utilization rate of reaction raw materials is improved, the discharge and treatment costs of compounds are reduced, production costs are effectively reduced, and economic benefits are improved.
  • the obtained reaction mixture stream ⁇ 1 (comprising 40% by weight of (SO 2 F—NH—SO 2 F) ⁇ Et 3 N, 18% by weight of triethylamine hydrogen fluoride salt and 6% by weight of triethylamine) Filter through a tetrafluoro filter bag with a pore size of 5 ⁇ m to filter out the solid by-product sulfonamide.
  • the filtrate is pumped into the falling film evaporator (the temperature of the hot water bucket is 75°C, and the solvent in the filtrate is evaporated under the vacuum degree of -0.02MPa (the front stage of the vacuum pump is condensed with 0°C water, and the latter stage is condensed with -15°C water).
  • a stream ⁇ 2 comprising (SO 2 F—NH—SO 2 F) ⁇ Et 3 N and triethylamine hydrogen fluoride salt (which contains 70% by weight of (SO 2 F—NH—SO 2 F) ⁇ Et 3 N, 28% by weight of triethylamine hydrogen fluoride) and the condensate containing acetonitrile.
  • the condensate is reclaimed for the synthesis of the first step in the synthesis tank.
  • Stream ⁇ 2 is pumped to the rotary disk extraction tower (stirring frequency 15 ⁇ 1Hz; the flow rate is controlled so that the weight ratio of deionized water and ⁇ 2 is 1:1.2), after fully mixing with deionized water in the extraction tower, the aqueous phase ⁇ water containing triethylamine hydrogen fluoride salt as the supernatant (which contains 77% by weight of water+22% by weight of triethylamine hydrogen fluoride salt), and the oil phase ⁇ 3 containing (SO 2 F-NH-SO 2 F) ⁇ Et 3 N as the lower layer liquid (which also contains 15% by weight of water).
  • the upper water phase is sent to the recovery workshop for treatment, and the lower oil phase is sent to the alkalization step. After testing, the oil phase ⁇ 3 also contains 100ppm of F - .
  • Stream ⁇ 3 is directly alkalized in falling film evaporator B (35 °C of steam heating temperature of hot water barrel), and lithium hydroxide aqueous solution (concentration 5mol/L is added dropwise, wherein the volume ratio of stream ⁇ 3 and the aqueous solution of lithium hydroxide is 1.1:1) while stirring continuously. After 1 hour of reaction, the mixture stream ⁇ 1-1 (crude lithium salt) was obtained. At the same time, use 35°C hot water for heating, and turn on the vacuum to keep the vacuum degree in the kettle at -0.08MPa, and the steaming time is 6 hours. The front and rear stages of the vacuum pump use 25°C water and 0°C water for five-stage condensation respectively.
  • the condensate is left to stand for liquid separation, the upper layer is triethylamine aqueous solution, pumped to the recovery workshop for recovery, and the lower layer is recovered for the alkalization process to prepare lithium hydroxide aqueous solution.
  • a lithium bisfluorosulfonyl imide-containing stream ⁇ 1-2 (comprising 85% by weight of lithium bisfluorosulfonylimide and 10% by weight of water) was obtained.
  • lithium hydroxide aqueous solution (concentration 5 mol/L) was added to keep the pH of the stream ⁇ 1-2 at 8.
  • the stream ⁇ 1-2 continues to evaporate in the falling film evaporator C (50 °C of heating temperature of hot water tank steam). Simultaneously metering pumps into diethyl carbonate (DEC) (control flow meter, make the volume ratio of DEC and material flow ⁇ 1-2 be 0.6:1), continue vacuum (-0.08MPa) heating and evaporating, the front and rear stages of vacuum pump use normal temperature ( 25°C) water and 0°C water are subjected to five-stage condensation, and the condensate is an aqueous solution containing DEC. The condensate is sent to the recovery workshop for recovery.
  • DEC diethyl carbonate
  • the stream ⁇ 2 (it comprises the bisfluorosulfonyl imide lithium of 70% by weight and the diethyl carbonate of 29% by weight and the water of 1% by weight ).
  • an aqueous solution of lithium hydroxide (concentration 5 mol/L) was metered in such that the pH of the stream ⁇ 2 was kept at 8.
  • the stream ⁇ 2 of gained after being evaporated by the falling film evaporator C is centrifugally filtered through a disc centrifuge (rotating speed is 1500rpm), and the by-product lithium compound is filtered out to obtain 1% by weight of water, 30% by weight of diethyl carbonate and Stream ⁇ 2-1 of 69% by weight lithium bisfluorosulfonyl imide.
  • the material stream ⁇ 2-1 is pumped into the scraper evaporator D (heating temperature of hot water barrel steam is 75° C.), and metered and pumped into diethyl carbonate (DEC) at the same time (control the flow meter so that the DEC and material flow ⁇ 2-1 Volume ratio is 0.25:1), continue vacuum (vacuum degree-0.08MPa) heating evaporation dehydration.
  • Lithium hydroxide solution (concentration 5 mol/L) was also added while evaporating through the wiper evaporator D, so that the pH of the resulting stream ⁇ 3 was maintained at 8.
  • the condensate mainly contains DEC and a small amount of water, and the condensate is sent to the recovery workshop for recovery.
  • Lithium bisfluorosulfonimide ⁇ 3 (comprising 85% by weight of lithium bisfluorosulfonylimide and 15% by weight of diethyl carbonate) with a water content of 3000 ppm was obtained after evaporation for 6 hours.
  • the purity of the lithium bisfluorosulfonyl imide powder obtained after the drying step is 99.8%, and the yield reaches 92%, wherein the free acid content is 10 ⁇ g/g, and the moisture content is 20 ⁇ g/g.
  • the material stream ⁇ 2 is pumped to the static mixer, and after being fully mixed with deionized water in the static mixer, it is sent to the stratification tank, and after standing for stratification for 2 hours, the three-containing The water phase ⁇ water of ethylamine hydrogen fluoride salt, and the oil phase ⁇ 3 containing (SO 2 F-NH-SO 2 F) ⁇ Et 3 N as the lower layer liquid, the upper layer water phase is sent to the recovery workshop for processing, and the lower layer oil phase is sent to to the alkalization step. After testing, the ⁇ 3 oil phase contains 1000ppm of F - .
  • the purity of the lithium bisfluorosulfonimide powder obtained after the drying step in Example 2 was 99.2%, and the yield reached 89%, wherein the free acid content was 15 ⁇ g/g and the moisture content was 25 ⁇ g/g.
  • 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. .

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Abstract

本申请提供了一种制备双氟磺酰亚胺锂的方法，包括如下步骤：(a)合成步骤；(b)蒸发步骤；(c)萃取步骤；(d)碱化步骤；(e)脱水步骤；(f)脱溶步骤；(g)析晶步骤；(h)干燥步骤，以及包括通过所述方法制备的双氟磺酰亚胺锂、含有所述双氟磺酰亚胺锂的电解液、及其二次电池。

Description

双氟磺酰亚胺锂及其制备方法、电解液和二次电池 技术领域
本申请涉及一种制备双氟磺酰亚胺锂的方法，以及通过所述方法制备的双氟磺酰亚胺锂，包括通过所述方法制备的双氟磺酰亚胺锂的电解液及其二次电池。
背景技术
双氟磺酰亚胺锂(LiFSI)由于其特殊的分子结构，使得在电解液中添加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，尤其在动力电池中，可改善动力电池的循环性能以及倍率性能，因此是锂离子电池的电解质锂盐的极佳选择。
现有技术中合成以及提纯LiFSI在工业化大规模生产中存在诸多问题，其合成过程工艺繁琐、流程较长、产品转化率低，并且原辅材料消耗量大且难以回收，因此经济性不高。本发明旨在解决这些问题中的至少一些，并提出了新的生产LiFSI的连续方法，使LiFSI的纯度、水分含量达到电池级的标准，生产成本低，三废少，适合工业化生产。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种制备双氟磺酰亚胺锂的方法，以解决现有技术制备LiFSI所涉及的产品纯度低、水分高、生产成本高、三废多的问题。
为了达到上述目的，本申请提供了一种制备双氟磺酰亚胺锂的方法，以及通过所述方法制备的双氟磺酰亚胺锂，包括通过所述方法制备的双氟磺酰亚胺锂的电解液及其二次电池。
本申请的第一方面提供了一种制备双氟磺酰亚胺锂的方法，包括以下步骤：
(a)合成步骤：将硫酰氟、氨气和三乙胺在溶剂的存在下在反应釜中反 应，得到包含(SO 2F-NH-SO 2F)·Et 3N、三乙胺氟化氢盐和三乙胺的料流α1；
(b)蒸发步骤：将料流α1进行蒸发，得到包含(SO 2F-NH-SO 2F)·Et 3N和三乙胺氟化氢盐的料流α2，将蒸发出的溶剂和三乙胺任选地进行后处理后再循环至步骤(a)；
(c)萃取步骤：将步骤(b)得到的料流α2在萃取塔或静态混合器中用水洗涤，得到包含(SO 2F-NH-SO 2F)·Et 3N的油相α3和包含三乙胺氟化氢盐的水相α 水，分离出油相α3；
(d)碱化步骤：将步骤(c)得到的油相α3送至蒸发器，在与氢氧化锂的水溶液进行混合后，得到混合物料流β1-1，然后将料流β1-1进行减压蒸发，得到包含双氟磺酰亚胺锂的料流β1-2；
(e)脱水步骤：将包含双氟磺酰亚胺锂的料流β1-2与酯类溶剂加入至蒸发器中，蒸发得到包含双氟磺酰亚胺锂的料流β2；
(f)脱溶步骤：将步骤(e)得到的料流β2与酯类溶剂加入至蒸发器中，蒸发得到双氟磺酰亚胺锂粗品β3；
(g)析晶步骤：将步骤(f)得到的双氟磺酰亚胺锂粗品β3泵入析晶釜中，加入二氯甲烷使得析出双氟磺酰亚胺锂晶体。
应用本申请的制备方法可获得纯度高、水分少的LiFSI。该制备方法能够连续生产，生产成本低且三废少，具有较高的工业应用价值。
在任意实施方式中，可选地，所述方法还包括以下步骤：
(h)干燥步骤：将步骤(g)析出的双氟磺酰亚胺锂晶体在干燥器中用惰性气体进行吹扫，得到含水量低于50ppm的粉状双氟磺酰亚胺锂晶体。
在任意实施方式中，可选地，在步骤(a)中，硫酰氟：氨气：三乙胺的摩尔比为(1.5-3.5):1:(1-6)，可选为(2-3):1:(1-5)。
在任意实施方式中，可选地，在步骤(a)中，所述溶剂选自乙腈、丙腈、异丙腈、乙醚、丙醚、异丙醚、四氢呋喃、丙酮、丁酮、甲基异丁基酮、甲基吡咯烷酮或其任意两种以上的混合物，优选乙腈。
在任意实施方式中，可选地，在步骤(a)中，其中，所述反应的反应温度不高于25℃，可选为3-20℃；和/或，所述反应的反应压力不高于0.4MPa，可选为不高于0.25MPa。
在任意实施方式中，可选地，步骤(a)和(b)之间还包括对料流α1进行过滤的步骤，以移出副产物磺酰胺(NH 2-SO 2-NH 2)固体，例如采用孔径为5μm至20μm的四氟过滤袋进行过滤。
在任意实施方式中，可选地，在步骤(b)中，使用降膜蒸发器对料流α1进行蒸发。
在任意实施方式中，可选地，在步骤(c)中，将包含三乙胺氟化氢盐的水相送至回收处理，所述水相经碱化和纯化处理后得到的三乙胺可循环利用。
在任意实施方式中，可选地，在步骤(d)中，将油相α3与氢氧化锂的水溶液进行混合并搅拌，反应0.5-3小时，可选为1-2小时。
在任意实施方式中，可选地，在步骤(d)中，将蒸发料流β1-1所得的冷凝液进行静置分液，上层液为三乙胺水溶液，将所述上层液送至回收处理；下层液为冷凝水，将下层液回收用于配制碱化步骤所需的氢氧化锂水溶液。
在任意实施方式中，可选地，在步骤(d)中，其中料流α3与氢氧化锂的水溶液的体积比例为可选为(0.8-5)：1，可选为(1-1.2)：1。
在任意实施方式中，可选地，在步骤(e)和(f)中，将冷凝得到的酯类溶剂的水溶液送至回收处理。
在任意实施方式中，可选地，在步骤(e)中得到的料流β2含有0.1体积％至2体积％的水和20体积％至40体积％的酯类溶剂。
在任意实施方式中，可选地，在步骤(f)中得到的双氟磺酰亚胺锂粗品β3具有2000ppm至4000ppm的含水量，优选3000ppm的含水量。
在任意实施方式中，可选地，步骤(e)和(f)在同一个蒸发器中进行，或者步骤(e)和(f)在不同的蒸发器中进行。
在任意实施方式中，可选地，在步骤(d)和步骤(e)期间存在如下副反应：
(SO 2F-N-SO 2F) -Li ++4LiOH→NH 2SO 3Li+Li 2SO 4+2LiF+H 2O
将副产物锂化合物在脱溶步骤(f)之前离心过滤除去，如通过刮刀离心机或碟式离心机除去。
在任意实施方式中，可选地，在步骤(e)、步骤(f)中，所述酯类溶剂各自独立地选自沸点大于70℃，优选大于80℃，优选为100℃-130℃且与水 不互溶的有机溶剂。可选地，所述酯类溶剂含有碳酸酯类溶剂，包括碳酸亚乙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯或其两种以上的混合物。可选地，所述酯类溶剂含有羧酸酯类溶剂，例如乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯或其两种以上的混合物。进一步可选地，所述酯类溶剂选自碳酸甲乙酯、碳酸二甲酯和碳酸二乙酯中的至少一种。
在任意实施方式中，可选地，将碱化步骤(d)中的蒸发温度控制在30℃-40℃，可选为30℃-35℃；和/或，将脱水步骤(e)的蒸发温度控制在40℃-55℃，可选为45℃-50℃；和/或，将脱溶步骤(f)中的蒸发温度控制在60℃-80℃，可选为65℃-75℃。
在任意实施方式中，可选地，在步骤(d)、(e)和(f)中，加入氢氧化锂的水溶液使得蒸发器内混合物的pH保持在7-9的范围内，优选在8-9的范围内。
在任意实施方式中，可选地，在步骤(d)、(e)和(f)中，所述氢氧化锂的水溶液的浓度为1mol/L至15mol/L，可选为2mol/L至10mol/L。
在任意实施方式中，可选地，步骤(g)和(h)之间包括将经析晶步骤(g)得到的含酯类溶剂、二氯甲烷和双氟磺酰亚胺锂晶体的料流泵入具有过滤洗涤功能的二合一设备，其中将含碳酸二乙酯和二氯甲烷的析晶液送至回收处理，剩余的双氟磺酰亚胺锂晶体通过重力落入二合一设备下层的干燥釜中。
在任意实施方式中，可选地，在步骤(h)中，干燥冷凝后的液相包含二氯甲烷和水，将所述液相回收送至析晶步骤(g)。
在任意实施方式中，可选地，在析晶步骤(g)中使用的二氯甲烷的含水量≤200ppm。
在任意实施方式中，可选地，所述方法在(h)干燥步骤之后还包括(i)罐装步骤，其中步骤(h)得到的粉状双氟磺酰亚胺锂晶体在用溶剂溶解并且任选地除酸、除水和过滤后达到如下标准：HF≤50μg/g，含水量≤20μg/g。
在任意实施方式中，可选地，步骤(i)中溶解所使用的溶剂与在步骤(e)和步骤(f)中使用的酯类溶剂是相同的。
本申请的第二方面还提供一种双氟磺酰亚胺锂，其通过本申请第一方面的方法制备。
本申请的第三方面还提供一种电解液，包括通过本申请第一方面的方法制备的双氟磺酰亚胺锂。
本申请的第四方面还提供一种二次电池，包括通过本申请第三方面的电解液。
本申请的电解液或二次电池包括通过本申请第一方面制备的双氟磺酰亚胺锂，因此至少具有与本申请第一方面所述的方法相同的优势。
附图说明
图1示出了α段工艺(合成→蒸发→萃取)的流程示意图，其中萃取工艺采用的是萃取塔。
图2示出了α段工艺(合成→蒸发→萃取)的流程示意图，其中萃取工艺采用的是静态混合器。
图3是β段工艺(碱化→脱水→脱溶)的流程示意图。
图4是析晶干燥工艺的流程示意图。
图5是罐装工艺的流程示意图。
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双氟磺酰亚胺锂的制备方法的实施方式。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”和“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。
本申请中使用的术语“以上”、“以下”包含本数，例如“一种以上”是指一种或多种，“A和B中的一种以上”是指“A”、“B”或“A和B”。
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)。
除非另有说明，否则本发明上下文中的含量和百分比均基于质量计。
本发明的工艺路线为：合成→蒸发→萃取→碱化→脱水→脱溶→析晶→干燥→罐装(罐装步骤为任选的工序)。在下文中将进一步描述各个步骤。
[合成步骤]
在本发明的合成步骤(a)中，将硫酰氟、氨气和三乙胺在溶剂的存在下在反应釜中反应，得到包含(SO 2F-NH-SO 2F)·Et 3N、三乙胺氟化氢盐和三乙胺的料流α1。
在一些实施方案中，在步骤(a)中，硫酰氟：氨气：三乙胺的摩尔比为(1.5-3.5):1:(1-6)，可选为(2-3):1:(1-5)。在本申请中，当氨气过量时，易产生副反应，使得反应混合物变得浑浊，造成后续过滤困难。同时为了使物料的颜色变浅，需要避免硫酰氟和三乙胺长时间接触。因此，优选地，在步骤(a)中，首先在反应装置中加入乙腈和三乙胺，然后通入部分氨气(优选通入氨气总量的2-15％，优选3-10％)，最后同时通入氨气和硫酰氟进行反应。
在一些实施方案中，在步骤(a)中，所述溶剂选自乙腈、丙腈、异丙腈、乙醚、丙醚、异丙醚、四氢呋喃、丙酮、丁酮、甲基异丁基酮、甲基吡咯烷酮或其任意两种以上的混合物，优选乙腈。
通常，在(a)中的反应可以任意合适的方式进行。例如，所述反应可在间歇式反应器中或至少一种半连续操作的反应器中或至少一种连续操作的反应器中进行。
在一些实施方案中，在步骤(a)中，所述反应的反应温度不高于25℃，可选为3℃-20℃；和/或，所述反应的反应压力不高于0.4MPa，可选为不高于0.25MPa。温度和压力过高会导致较多的副反应，另外，温度过高，溶剂易汽化，导致反应釜内压力过大，影响安全生产。
本发明的发明人发现，当将步骤(a)中硫酰氟与氨气的摩尔比为(1.5-4):1，优选(2-3):1时，获得特别好的收率和色度。
在一些实施方案中，在步骤(a)中，在反应结束时，得到包含30重量％至50重量％的(SO 2F-NH-SO 2F)·Et 3N、15重量％至30重量％的三乙胺氟化氢盐和0至10重量％的三乙胺的料流α1。
在一些实施方案中，对α1料流可进行一次以上的过滤，优选2-5次，可 选地为2次，下游过滤所使用的过滤袋的孔径小于上游过滤袋的孔径。
[蒸发步骤]
在本发明的蒸发步骤(b)中，将料流α1进行蒸发，得到包含(SO 2F-NH-SO 2F)·Et 3N和三乙胺氟化氢盐的料流α2，将蒸发出的溶剂和三乙胺任选地进行后处理后再循环至步骤(a)。
在一些实施方案中，在步骤(a)和(b)之间还包括对料流α1进行过滤的步骤，以移出副产物磺酰胺(NH 2-SO 2-NH 2)固体，例如采用孔径为5μm至20μm，可选为6μm至15μm的四氟过滤袋进行过滤。
在一些实施方案中，在步骤(b)中，使用降膜蒸发器对料流α1进行蒸发。所述降膜蒸发器使用的换热介质可为热水，热水桶的温度为50℃至100℃，优选60℃至80℃。
在一些实施方案中，在步骤(b)中，所述蒸发可使用一个或两个或更多个串联的蒸发器，优选降膜蒸发器进行。
在一些实施方案中，在步骤(b)中，将通过蒸发器蒸出的气体料流使用冷凝器，优选使用包含前级冷凝器和后级冷凝器的冷凝器进行冷凝，所述前级冷凝器用0℃的水进行冷凝，后级冷凝器用-15℃的水进行冷凝。可选地，所述蒸发器内部压力为-0.01MPa至-0.1MPa。在本文中，本领域的技术人员可以理解，在冷凝器中使用的水中包含30-50重量％的防冻液，所述防冻液可为乙二醇、丙三醇。
在一些实施方案中，在步骤(b)中的蒸发可在一个或多个蒸发器中进行。
在一些实施方案中，在步骤(b)中，料流α2包含60重量％至80重量％的(SO 2F-NH-SO 2F)·Et 3N和20重量％至40重量％三乙胺氟化氢盐。
[萃取步骤]
在本发明的萃取步骤(c)中，将步骤(b)得到的料流α2在萃取塔或静态混合器中用水洗涤，得到包含(SO 2F-NH-SO 2F)·Et 3N的油相α3和包含三乙胺氟化氢盐的水相α 水，分离出油相α3。
在一些实施方案中，在步骤(c)中，进入萃取塔或静态混合器中的水与 料流α2的质量比为1：(1-2)，可选为1：(1.1-1.5)。
在一些实施方案中，在步骤(c)中，油相α3还包含5重量％-15重量％的水。
在一些实施方案中，在步骤(c)中，α 水包含75重量％-80重量％的水和20重量％-25重量％的三乙胺氟化氢盐。
在一些实施方案中，在步骤(c)中，将包含三乙胺氟化氢盐的水相送至回收处理，所述水相经碱化和纯化处理后得到的三乙胺可循环利用。水相除三乙胺氟化氢盐外还包含杂质离子(如F-、SO 4 2-、FSO 3 -或Cl-)，经过回收段碱化并提纯处理后三乙胺可以回收利用，KF外售可以产生额外的经济效益。
在本申请中，所述萃取塔可为本领域常规使用的萃取塔，如填料萃取塔、筛板萃取塔、转盘萃取塔、振动筛板塔、多级离心萃取塔，优选转盘萃取塔。
在一些实施方案中，所述萃取步骤在萃取塔(搅拌频率15±1HZ；其中使用的去离子水与α2的重量比为1：(1-1.6)，优选1：(1-1.4))中进行，其中轻相(密度小)从萃取塔的侧面底部进入，从萃取塔的顶部排出；重相从萃取塔的侧面顶部进入，从萃取塔的底部排出，中间搅拌为呈螺旋状(搅拌效果更好，清洗和分离情况更优)。出乎意料地，发明人发现采用萃取塔进行萃取，可实现对于杂质离子(例如F -)的更好地分离。经静态混合器处理，α3中F离子含量≥1000ppm，后续碱化工序需要消耗更多的LiOH；然而，经萃取塔处理，α3中F离子含量≤100ppm。
在本申请中，测定料流中的F离子含量和水含量是本领域技术所熟知的方法，例如采用茜素络合比色法测定F离子含量、采用卡尔费休法测定水含量。
在一些实施方案中，在步骤(c)中，将步骤(b)得到的料流α2在萃取塔中用水洗涤。
在本申请中，所述静态混合器可为本领域常规使用的静态混合器，例如管道式静态混合器。在使用静态混合器的情况下，需要将所得混合物泵入分层槽进行静置分层，通常需要静置1-10小时，优选2-6小时。
在本申请中，如无特别说明，本文中所使用的水均为去离子水，这样可以最大程度地降低最终产物中所含杂质的种类和含量。
[碱化步骤]
在本发明的碱化步骤(d)中，将步骤(c)得到的油相α3送至蒸发器，在与氢氧化锂的水溶液进行混合后，得到混合物料流β1-1，然后将料流β1-1进行减压蒸发，得到包含双氟磺酰亚胺锂的料流β1-2。
在一些实施方案中，步骤(d)的碱化按照如下反应式进行：
(SO 2F-NH-SO 2F)·Et 3N+LiOH→(SO 2F-N-SO 2F) -Li +(LiFSI)+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，通过降膜蒸发移出三乙胺，同时LiOH与(SO 2F-NH-SO 2F)·Et 3N反应生成双氟磺酰亚胺锂(简称为LiFSI)。
在一些实施方案中，在步骤(d)中，在蒸发料流β1-1前，将油相α3与氢氧化锂的水溶液进行混合并搅拌，反应0.5-3小时，可选为1-2小时。
在一些实施方案中，在步骤(d)中，所述氢氧化锂水溶液的浓度为1mol/L至15mol/L，可选为2mol/L至10mol/L。
在一些实施方案中，在步骤(d)中，将蒸发料流β1-1所得的冷凝液进行静置分液，上层液为三乙胺水溶液，将所述上层液送至回收处理；下层液为冷凝水，将下层液回收用于配制碱化步骤所需的氢氧化锂水溶液。
在一些实施方案中，在步骤(d)中，其中料流α3与氢氧化锂的水溶液的体积比例为(0.8-5)：1，可选为(1-1.2)：1。
在一些实施方案中，在步骤(d)中，加入氢氧化锂的水溶液使得蒸发器内混合物的pH保持在7-9的范围内，优选在8-9的范围内。
在一些实施方案中，在步骤(d)中，所述蒸发使用降膜蒸发器进行，将蒸发温度控制在30-40℃，可选为30-35℃。
在一些实施方案中，在步骤(d)中的蒸发可在一个或多个蒸发器中进行。
在一些实施方案中，在步骤(d)中，其中料流β1-2包含70至90重量％的双氟磺酰亚胺锂和5至25重量％水，余量为LiF、Li 2SO 4和氨基磺酸锂等，基于100重量％的料流β1-2计。
[脱水步骤]
在本发明的脱水步骤(e)中，将包含双氟磺酰亚胺锂的料流β1-2与酯类溶剂加入至蒸发器中，蒸发得到包含双氟磺酰亚胺锂的料流β2。
在一些实施方案中，在步骤(e)中，将冷凝得到的酯类溶剂的水溶液送至回收处理。
在一些实施方案中，在步骤(e)中，将料流β1-2与酯类溶剂以1：(0.4-0.8),优选为1：(0.5-0.7)的体积比进行混合。
在一些实施方案中，在步骤(e)中，得到的料流β2还含有0.1体积％至2体积％的水和20体积％至40体积％的酯类溶剂。
在一些实施方案中，在步骤(e)中，所述蒸发器为降膜蒸发器，将蒸发温度控制在40-55℃，可选为45-50℃。
在一些实施方案中，在步骤(e)中的蒸发可在一个或多个蒸发器中进行。
由于锂盐的吸水性非常强，仅通过蒸发来将水分降低至所需要的标准是困难的。例如，通过添加大量不溶于水且沸点优选大于水(例如100-130℃)的酯类有机溶剂(例如碳酸脂和羧酸酯，优选DEC和EMC)可以减弱锂盐对水的吸附性，因此在添加酯类有机溶剂的同时进行蒸发脱水，可以将水分降低至所需要的含量，例如低于3000ppm。将冷凝得到的酯类有机溶剂与水的混合物经过回收段提纯处理后可以回收利用。
在一些实施方案中，可选地，在步骤(d)和步骤(e)期间存在如下副反应：
(SO 2F-N-SO 2F) -Li ++4LiOH→NH 2SO 3Li+Li 2SO 4+2LiF+H 2O
在脱溶步骤(f)之前，可选地，将副产物锂化合物(例如NH 2SO 3Li，Li 2SO 4，2LiF)离心过滤除去，如通过刮刀离心机或碟式离心机除去。
在一些实施方案中，将酯类溶剂与料流β1-2混合，在蒸发脱水的同时保持混合物的pH在7-9之间，经任选地离心过滤得到包含60重量％-80重量％的双氟磺酰亚胺锂、20-重量％-40重量％的酯类溶剂和0.2重量％-1.5重量％的水的料流β2。
在一些实施方案中，在步骤(e)中，在蒸发过程中通过加入氢氧化锂水溶液将混合物的pH保持在7-9，优选8-9。
在一些实施方案中，在步骤(e)中，所述氢氧化锂水溶液的浓度为1mol/L 至15mol/L，可选为2mol/L至10mol/L。
[脱溶步骤]
在本发明的脱溶步骤(f)中，将步骤(e)得到的料流β2与酯类溶剂加入至蒸发器中，蒸发得到双氟磺酰亚胺锂粗品β3。
在一些实施方案中，在脱水步骤(e)之后和脱溶步骤(f)之前，可选地，将副产物锂化合物(例如NH 2SO 3Li、Li 2SO 4和LiF)离心过滤除去，如通过刮刀离心机或碟式离心机除去，获得料流β2-1。
在一些实施方案中，在步骤(f)中，将所述料流β2或料流β2-1与酯类溶剂以1:(0.1-0.4)，优选为1:(0.2-0.3)的体积比进行混合。
在一些实施方案中，在步骤(f)中，所述蒸发器为刮板蒸发器，将蒸发温度控制在60-80℃，可选为65-75℃。
在一些实施方案中，在步骤(f)中的蒸发可在一个或多个蒸发器中进行。
在一些实施方案中，在步骤(f)中得到的双氟磺酰亚胺锂β3具有2000ppm至4000ppm的含水量，优选3000ppm的含水量。通过在步骤(e)中继续将料流β2或经过滤得到的料流β2-1与酯类溶剂进行混合，然后继续蒸发，可以更进一步地将料流β2或料流β2-1中的水除去。
在一些实施方案中，在步骤(f)中，双氟磺酰亚胺锂β3包含80重量％-90重量％双氟磺酰亚胺锂和10重量％-20重量％的酯类溶剂。
在一些实施方案中，在步骤(f)中，将冷凝得到的酯类溶剂的水溶液送至回收处理。
在本申请中，在碱化、脱水和脱溶步骤的过程中，均需要保持料流的pH保持在7-9，优选8-9的范围内，优选地通过加入氢氧化锂溶剂，从而保持弱碱性体系，抑制产品的分解。
在一些实施方案中，通过加入氢氧化锂水溶液将蒸发的混合物的pH保持在7-9，优选8-9的范围内。
在一些实施方案中，在步骤(f)中，所述氢氧化锂水溶液的浓度为1mol/L至15mol/L，可选为2mol/L至10mol/L。
由于锂盐溶解于酯类溶剂诸如碳酸二乙酯，因此需要将一定量的脂类溶 剂蒸发移出，否则后期无法析晶或析晶率很低。
在一些实施方案中，可选地，步骤(e)和(f)在同一个蒸发器中进行，或者步骤(e)和(f)在不同的蒸发器中进行。
[析晶步骤]
在本发明的析晶步骤(g)中，将步骤(f)得到的双氟磺酰亚胺锂粗品β3泵入析晶釜中，加入二氯甲烷使得析出双氟磺酰亚胺锂晶体。
在一些实施方案中，在析晶步骤(g)中使用的二氯甲烷的含水量≤200ppm。如果二氯甲烷的含水量过高，否则会影响双氟磺酰亚胺锂晶核生产，晶体太小太细，后续不容易干燥。
在一些实施方案中，可选地，步骤(g)和(h)之间包括将经析晶步骤(g)得到的含酯类溶剂、二氯甲烷和双氟磺酰亚胺锂晶体的料流泵入具有过滤洗涤功能的二合一设备，其中将含碳酸二乙酯和二氯甲烷的析晶液送至回收处理，剩余的双氟磺酰亚胺锂晶体通过重力落入二合一设备下层的干燥釜中。
[干燥步骤]
在本发明的干燥步骤(h)中，将步骤(g)析出的双氟磺酰亚胺锂晶体在干燥器中用惰性气体进行吹扫，得到含水量低于50ppm的粉状双氟磺酰亚胺锂晶体。
在一些实施方案中，在步骤(h)中，干燥冷凝后的液相包含二氯甲烷和水，将所述液相回收送至析晶步骤(g)。
[罐装步骤]
本发明的方法在(h)干燥步骤之后还包括(i)罐装步骤，其中将干燥步骤后得到的粉状双氟磺酰亚胺锂晶体在用溶剂溶解并且任选地除酸、除水和过滤后达到如下标准：HF≤50μg/g，含水量≤20μg/g。如果检测到溶解液中HF含量超标(例如HF＞50μg/g)，则用氢氧化锂进行除酸。如果检测到溶解液中水分含量超标(例如含水量＞20μg/g)，则用分子筛进行除水。
在一些实施方案中，步骤(i)中溶解所使用的溶剂与在步骤(e)和步骤(f)中使用的酯类溶剂是相同的。
本申请的第二方面还提供一种双氟磺酰亚胺锂，其通过本申请第一方面的方法制备。
本申请的第三方面还提供一种电解液，包括通过本申请第一方面的方法制备的双氟磺酰亚胺锂。
本申请的第四方面还提供一种二次电池，包括本申请第三方面的电解液。
本申请的电解液或二次电池包括通过本申请第一方面制备的双氟磺酰亚胺锂，因此至少具有与本申请第一方面所述的方法相同的优势。
本发明的LiFSI合成工艺路线中使用的原辅材料均为较常见的化工产品，生产成本低，反应过程无高温高压，前端合成反应放热通过制冷机进行冷却，保证在低温中反应，反应安全系数高。使LiFSI的生产成本低、三废少、纯度高，原料都能得到充分的循环回收利用，副产物提纯后也能产生额外的经济效益，适合工业化生产。通过回收循环使用原料，降低了原辅材料的消耗，提高反应原料的利用率，减少化合物的排放处理费用，有效降低了生产成本，提高经济效益。
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。
实施例1
【合成步骤→蒸发步骤→萃取步骤】
结合图1来描述α段工艺(合成→蒸发→萃取)，其中萃取工艺采用的是萃取塔。
将40m 3三乙胺、35m 3乙腈泵入体积为100m 3的合成釜中，将釜温降低至15℃，然后先通入120kg氨气，最后同时通入氨气(2000kg)和硫酰氟(26000 kg)，保持釜内压力在0.3MPa，并将釜内温度维持在15℃。持续反应4h后，将釜内压力降低至0.1MPa，停止搅拌。将所获得的反应混合物料流α1(其包含40重量％的(SO 2F-NH-SO 2F)·Et 3N、18重量％的三乙胺氟化氢盐和6重量％的三乙胺)经过孔径为5μm的四氟过滤袋进行过滤，过滤出固体副产品磺酰胺。将滤液泵入降膜蒸发器(热水桶温度为75℃中，在-0.02MPa的真空度(真空泵前级用0℃水冷凝，后级用-15℃水冷凝)下将滤液中的溶剂蒸出，得到包含(SO 2F-NH-SO 2F)·Et 3N及三乙胺氟化氢盐的料流α2(其包含70重量％的(SO 2F-NH-SO 2F)·Et 3N、28重量％的三乙胺氟化氢盐)以及含有乙腈的冷凝液。所述冷凝液被回收用于第一步的合成釜合成。将料流α2泵送至转盘萃取塔(搅拌频率15±1Hz；控制流量使得去离子水与α2的重量比为1：1.2)，在萃取塔中与去离子水充分混合后，得到作为上层液的含三乙胺氟化氢盐的水相α 水(其包含77重量％的水+22重量％的三乙胺氟化氢盐)，以及作为下层液的含(SO 2F-NH-SO 2F)·Et 3N的油相α3(其还包含15重量％的水)。将上层水相送至回收车间进行处理，下层油相送至碱化步骤。经检测，油相α3还含有100ppm的F -。
【碱化步骤→脱水步骤→脱溶步骤】
结合图3来描述β段工艺(碱化→脱水→脱溶)。
将料流α3直接在降膜蒸发器B(热水桶蒸汽加热温度35℃)中碱化，滴加氢氧化锂水溶液(浓度5mol/L，其中料流α3与氢氧化锂的水溶液的体积比例为1.1：1)的同时不断搅拌。反应1小时后得到混合物料流β1-1(锂盐粗品)。与此同时使用35℃热水进行加热，并开启真空，保持釜内真空度-0.08MPa，蒸出时间6小时。真空泵前后级分别用25℃的水和0℃水进行五级冷凝。将冷凝液进行静置分液，上层液为三乙胺水溶液，泵去回收车间回收，下层液回收用于碱化工序配制氢氧化锂水溶液。经过降膜蒸发器B蒸发后得到包含双氟磺酰亚胺锂的料流β1-2(其包含85重量％的双氟磺酰亚胺锂和10重量％的水)。在降膜蒸发器B蒸发的过程中，加入氢氧化锂水溶液(浓度5mol/L)，使得料流β1-2的pH保持在8。
将料流β1-2继续在降膜蒸发器C(热水桶蒸汽加热温度50℃)中继续蒸 发。同时计量泵入碳酸二乙酯(DEC)(控制流量计，使DEC与料流β1-2的体积比为0.6:1)，继续真空(-0.08MPa)加热蒸发，真空泵前后级分别用常温(25℃)水和0℃水进行五级冷凝，冷凝液为含DEC的水溶液。将所述冷凝液送至回收车间回收。经过降膜蒸发器C蒸发后得到包含双氟磺酰亚胺锂的料流β2(其包含70重量％的双氟磺酰亚胺锂和29重量％的碳酸二乙酯和1重量％的水)。在降膜蒸发器C蒸发的过程中，计量加入氢氧化锂水溶液(浓度5mol/L)，使料流β2的pH保持在8。
将经降膜蒸发器C蒸发后所得的料流β2经碟片式离心机进行离心(转速为1500rpm)过滤，过滤出副产品锂化合物，得到含1重量％水、30重量％碳酸二乙酯和69重量％的双氟磺酰亚胺锂的料流β2-1。将料流β2-1再泵入刮板蒸发器D(热水桶蒸汽加热温度75℃)中，同时计量泵入碳酸二乙酯(DEC)(控制流量计，使DEC与料流β2-1的体积比为0.25:1)，继续真空(真空度-0.08MPa)加热蒸发脱水。在经刮板蒸发器D进行蒸发的同时还加入氢氧化锂溶液(浓度5mol/L)，使所得料流β3的pH保持在8。冷凝液主要包含DEC及少量水，将所述冷凝液送至回收车间回收。在蒸发6小时后得到含水量3000ppm的双氟磺酰亚胺锂β3(其包含85重量％的双氟磺酰亚胺锂和15重量％的碳酸二乙酯)。
【析晶步骤→干燥步骤】
结合图4来描述析晶干燥工艺。
将β3泵入析晶釜中，以20L/h速度泵入含水量为100ppm的二氯甲烷，搅拌混合后，泵入带过滤洗涤功能的二合一设备，将二氯甲烷(含DEC)送至回收车间回收，剩余的双氟磺酰亚胺锂晶体通过重力落入二合一设备下层的干燥釜中，在干燥器中通入氮气吹扫晶体以进行干燥，干燥温度为60℃。干燥冷凝后，冷凝液包含99.5％二氯甲烷和0.5％水，将所述冷凝液送至析晶工序循环利用。在晶体水分降至目标要求(50ppm)后，将得到的粉料产品送至罐装工段。
经检测，干燥步骤后获得的双氟磺酰亚胺锂粉末的纯度为99.8％，收率达到92％，其中，游离酸含量为10μg/g、水分含量为20μg/g。
【罐装步骤】
结合图5来描述任选的罐装工艺。
将70L碳酸二乙酯和0.1kg氢氧化锂加入30kg经析晶干燥后得到的双氟磺酰亚胺锂粉末中。然后使用碟片式离心机进行离心(转速为1500rpm)，除去固体，然后将滤液送至脱水釜，脱水釜中加入20kg分子筛，搅拌转速800rpm，处理时间2h。然后使用过滤器过滤掉分子筛，将所得滤液送至产品调配釜。最后进行除磁(立式除磁过滤器，8000高斯)并过滤(分别通过1微米过滤器、0.5微米过滤器、0.1微米过滤器)，得到浓度为28重量％的双氟磺酰亚胺锂的碳酸二乙酯溶液(HF≤50μg/g，含水量≤20μg/g)，最后进行罐装。
实施例2：实施例2的技术方案与实施例1相同，区别在于，在萃取步骤中，萃取工艺采用的是静态混合器(长度与管径之比L/D＝10；控制流量使得去离子水与α2的重量比为1：1.2)。根据图2所示，将料流α2泵送至静态混合器，在静态混合器中与去离子水充分混合后，送至分层槽，静置分层2小时后得到作为上层液的含三乙胺氟化氢盐的水相α 水，以及作为下层液的含(SO 2F-NH-SO 2F)·Et 3N的油相α3，上层水相送至回收车间进行处理，下层油相送至碱化步骤。经检测，α3油相含有1000ppm的F -。
经检测，实施例2的干燥步骤后获得的双氟磺酰亚胺锂粉末的纯度为99.2％，收率达到89％，其中，游离酸含量为15μg/g、水分含量为25μg/g。
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。

Claims (28)

  1. 一种制备双氟磺酰亚胺锂的方法，包括以下步骤：
    (a)合成步骤：将硫酰氟、氨气和三乙胺在溶剂的存在下在反应釜中反应，得到包含(SO 2F-NH-SO 2F)·Et 3N、三乙胺氟化氢盐和三乙胺的料流α1；
    (b)蒸发步骤：将所述料流α1进行蒸发，得到包含(SO 2F-NH-SO 2F)·Et 3N和三乙胺氟化氢盐的料流α2，将蒸发出的溶剂和三乙胺任选地进行后处理后再循环至步骤(a)；
    (c)萃取步骤：将步骤(b)得到的所述料流α2在萃取塔或静态混合器中用水洗涤，得到包含(SO 2F-NH-SO 2F)·Et 3N的油相α3和包含三乙胺氟化氢盐的水相α 水，分离出所述油相α3；
    (d)碱化步骤：将步骤(c)得到的所述油相α3送至蒸发器，在与氢氧化锂的水溶液进行混合后，得到混合物料流β1-1，然后将所述料流β1-1进行减压蒸发，得到包含双氟磺酰亚胺锂的料流β1-2；
    (e)脱水步骤：将包含双氟磺酰亚胺锂的所述料流β1-2与酯类溶剂加入至蒸发器中，蒸发得到包含双氟磺酰亚胺锂的料流β2；
    (f)脱溶步骤：将步骤(e)得到的所述料流β2与酯类溶剂加入至蒸发器中，蒸发得到双氟磺酰亚胺锂粗品β3；
    (g)析晶步骤：将步骤(f)得到的所述双氟磺酰亚胺锂粗品β3泵入析晶釜中，加入二氯甲烷使得析出双氟磺酰亚胺锂晶体。
  2. 根据权利要求1所述的方法，其中，所述方法还包括以下步骤：
    (h)干燥步骤：将步骤(g)析出的所述双氟磺酰亚胺锂晶体在干燥器中用惰性气体进行吹扫，得到含水量低于50ppm的粉状双氟磺酰亚胺锂晶体。
  3. 根据权利要求1至2中任一项所述的方法，其中，在步骤(a)中，硫酰氟：氨气：三乙胺的摩尔比为(1.5-3.5):1:(1-6)，可选为(2-3):1:(1-5)。
  4. 根据权利要求1至3中任一项所述的方法，其中，在步骤(a)中，所述溶剂选自乙腈、丙腈、异丙腈、乙醚、丙醚、异丙醚、四氢呋喃、丙酮、丁酮、甲基异丁基酮、甲基吡咯烷酮或其任意两种以上的混合物，优选乙腈。
  5. 根据权利要求1至4中任一项所述的方法，其中，在步骤(a)中，其中，所述反应的反应温度不高于25℃，可选为3℃-20℃；和/或，所述反应的反应压力不高于0.4MPa，可选为不高于0.25MPa。
  6. 根据权利要求1至5中任一项所述的方法，其中，步骤(a)和(b)之间还包括对所述料流α1进行过滤的步骤，以移出副产物磺酰胺固体，可选地，所述过滤的步骤采用孔径为5μm至20μm的四氟过滤袋进行过滤。
  7. 根据权利要求1至6中任一项所述的方法，其中，在步骤(b)中，使用降膜蒸发器对所述料流α1进行蒸发。
  8. 根据权利要求1至7中任一项所述的方法，其中，在步骤(c)中，将包含三乙胺氟化氢盐的所述水相α 水送至回收处理，所述水相α 水经碱化和纯化处理后得到的三乙胺可循环利用。
  9. 根据权利要求1至8中任一项所述的方法，其中，在步骤(d)中，将所述油相α3与氢氧化锂的水溶液进行混合并搅拌，反应0.5-3小时，可选为1-2小时。
  10. 根据权利要求1至9中任一项所述的方法，其中，在步骤(d)中，将蒸发所述料流β1-1所得的冷凝液进行静置分液，上层液为三乙胺水溶液，将所述上层液送至回收处理；下层液为冷凝水，将所述下层液回收用于配制所述碱化步骤所需的氢氧化锂水溶液。
  11. 根据权利要求1至10中任一项所述的方法，其中，在步骤(d)中，所述油相α3与氢氧化锂的水溶液的体积比例为(0.8-5)：1，可选为(1-1.2)：1。
  12. 根据权利要求1至11中任一项所述的方法，其中，在步骤(e)和步骤(f)中，将冷凝得到的酯类溶剂的水溶液送至回收处理。
  13. 根据权利要求1至12中任一项所述的方法，其中，在步骤 (e)中得到的所述料流β2含有0.1体积％至2体积％的水和20体积％至40体积％的酯类溶剂。
  14. 根据权利要求1至13中任一项所述的方法，其中，在步骤(f)中得到的所述双氟磺酰亚胺锂粗品β3具有2000ppm至4000ppm的含水量，优选2300ppm～2800ppm的含水量。
  15. 根据权利要求1至14中任一项所述的方法，其中，步骤(e)和步骤(f)在同一个蒸发器中进行，或者步骤(e)和步骤(f)在不同的蒸发器中进行。
  16. 根据权利要求1至15中任一项所述的方法，其中，在步骤(d)和步骤(e)期间存在如下副反应：
    (SO 2F-N-SO 2F) -Li ++4LiOH→NH 2SO 3Li+Li 2SO 4+2LiF+H 2O
    将副产物锂化合物在脱溶步骤(f)之前离心过滤除去，可选地，为通过刮刀离心机或碟式离心机除去。
  17. 根据权利要求1至16中任一项所述的方法，其中，在步骤(e)、步骤(f)中，所述酯类溶剂选自沸点大于70℃，优选大于80℃，优选为100℃-130℃且与水不互溶的有机溶剂；
    可选地，所述酯类溶剂含有碳酸酯类溶剂，包括碳酸亚乙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯或其两种以上的混合物；
    可选地，所述酯类溶剂含有羧酸酯类溶剂，包括乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯或其两种以上的混合物；
    进一步可选地，所述酯类溶剂选自碳酸甲乙酯、碳酸二甲酯或碳酸二乙酯中的至少一种。
  18. 根据权利要求1至17中任一项所述的方法，其中，将所述碱化步骤(d)中的蒸发温度控制在30℃-40℃，可选为30℃-35℃；和/或，将脱水步骤(e)的蒸发温度控制在40℃-55℃，可选为45℃-50℃；和/或，将脱溶步骤(f)中的蒸发温度控制在60℃-80℃，可选为65℃-75℃。
  19. 根据权利要求1至18中任一项所述的方法，其中，在步骤(d)、步骤(e)和步骤(f)中，加入氢氧化锂的水溶液使得蒸发器内混合物的pH保持在7-9的范围内，优选在8-9的范围内。
  20. 根据权利要求1至19中任一项所述的方法，其中，在步骤(d)、步骤(e)和步骤(f)中，所述氢氧化锂的水溶液的浓度为1mol/L至15mol/L，可选为2mol/L至10mol/L。
  21. 根据权利要求1至20中任一项所述的方法，其中，步骤(g)和步骤(h)之间包括将经析晶步骤(g)得到的含酯类溶剂、二氯甲烷和双氟磺酰亚胺锂晶体的料流泵入具有过滤洗涤功能的二合一设备，其中将含碳酸二乙酯和二氯甲烷的析晶液送至回收处理，剩余的双氟磺酰亚胺锂晶体通过重力落入二合一设备下层的干燥釜中。
  22. 根据权利要求1至21中任一项所述的方法，其中，在步骤(h)中，干燥冷凝后的液相包含二氯甲烷和水，将所述液相回收送至析晶步骤(g)。
  23. 根据权利要求1至22中任一项所述的方法，其中，在析晶步骤(g)中使用的二氯甲烷的含水量≤200ppm。
  24. 根据权利要求1至23中任一项所述的方法，所述方法在(h)干燥步骤之后还包括(i)罐装步骤，其中步骤(h)得到的粉状双氟磺酰亚胺锂晶体在用溶剂溶解并且任选地除酸、除水和过滤后达到如下标准：HF≤50μg/g，含水量≤20μg/g。
  25. 根据权利要求24所述的方法，其中步骤(i)中溶解所使用的溶剂与在步骤(e)和步骤(f)中使用的酯类溶剂是相同的。
  26. 双氟磺酰亚胺锂，其通过权利要求1至25中任一项所述的方法制备。
  27. 一种电解液，包括通过权利要求1-25中任一项所述的方法制备的双氟磺酰亚胺锂。
  28. 一种二次电池，包括根据权利要求27所述的电解液。
PCT/CN2022/074931 2022-01-29 2022-01-29 双氟磺酰亚胺锂及其制备方法、电解液和二次电池 WO2023142023A1 (zh)

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EP22922545.3A EP4273095A4 (en) 2022-01-29 2022-01-29 LITHIUM BIS(FLUOROSULFONYL)IMIDE AND PREPARATION METHOD THEREFOR, ELECTROLYTE AND SECONDARY BATTERY
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