WO2023142026A1 - 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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WO2023142026A1
WO2023142026A1 PCT/CN2022/074934 CN2022074934W WO2023142026A1 WO 2023142026 A1 WO2023142026 A1 WO 2023142026A1 CN 2022074934 W CN2022074934 W CN 2022074934W WO 2023142026 A1 WO2023142026 A1 WO 2023142026A1
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stream
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water
lithium
solvent
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PCT/CN2022/074934
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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 EP22922859.8A priority Critical patent/EP4276064A1/en
Priority to PCT/CN2022/074934 priority patent/WO2023142026A1/zh
Publication of WO2023142026A1 publication Critical patent/WO2023142026A1/zh
Priority to US18/446,441 priority patent/US20230387468A1/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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • 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, lithium bisfluorosulfonyl imide prepared by the method, an electrolyte containing the lithium bisfluorosulfonyl imide, and a secondary battery thereof.
  • LiFSI lithium bisfluorosulfonyl imide Due to its special molecular structure, lithium bisfluorosulfonyl imide (LiFSI) makes it possible to obtain higher conductivity by adding LiFSI to the electrolyte. 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.
  • This application aims to solve at least some of these problems, and proposes a new continuous method for producing LiFSI, so that the purity and moisture of LiFSI can reach battery-level standards, the production cost is low and the three wastes are less, and it is suitable for industrial production.
  • This application is carried out in view of the above-mentioned 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, lithium bisfluorosulfonyl imide prepared by the method, and an electrolyte containing lithium bisfluorosulfonyl imide and its secondary battery.
  • the first aspect of the 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: mixing the stream ⁇ 2 obtained in step (e) with an ester solvent, then evaporating in an evaporator to obtain lithium bisfluorosulfonyl imide ⁇ 3; and optionally
  • step (g) Refining step: Send the lithium bisfluorosulfonimide ⁇ 3 obtained in step (f) to the dissolution and acid removal kettle, add ester solvent and lithium hydroxide, then perform centrifugal filtration, and send the obtained filtrate g-1 to Go to the dehydration tank containing molecular sieves to remove water, remove the molecular sieves by filtration, and the resulting filtrate g-2 is sent to the product preparation company, and optionally demagnetized and filtered.
  • LiFSI with high purity and low moisture can be obtained by applying the preparation method of the present application. At the same time, its production cost is low and the three wastes are less.
  • 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, ether, propyl ether, isopropyl ether, tetrahydrofuran, acetone, butanone, methyl isobutyl ketone, Methylpyrrolidone or a mixture of any two or more thereof; preferably, the solvent contains at least acetonitrile.
  • 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.
  • a step of filtering the stream ⁇ 1 is further included between steps (a) and (b) to remove the by-product sulfonamide (NH 2 -SO 2 -NH 2 ) solid.
  • the step of filtering includes filtering with a tetrafluoro filter bag with a pore size of 5 ⁇ m to 20 ⁇ m.
  • step (b) stream al is evaporated using a falling film evaporator.
  • step (c) the aqueous phase alpha water 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.
  • 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 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.
  • steps (e) and (f) the aqueous solution of the ester solvent obtained by condensation is sent to recovery treatment.
  • the obtained stream ⁇ 2 contains 0.1% to 2% by volume of water and 20% to 40% by volume of ester solvent.
  • the lithium bisfluorosulfonyl imide ⁇ 3 obtained in step (f) has a water content of 2000 ppm to 4000 ppm, preferably 2300 ppm to 2700 ppm.
  • step (b), step (d), step (e) and step (f) can be performed in one or more evaporators.
  • step (f) and step (g) the centrifugation is performed using a scraper centrifuge or a disc centrifuge.
  • the ester solvents are each independently selected from the group having a boiling point greater than 70°C, preferably greater than 80°C, preferably 100-130°C and Organic solvent immiscible with water.
  • the ester solvent contains a carbonate solvent, further optionally, the carbonate solvent is selected from ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dicarbonate Propyl ester, 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, further optionally, the carboxylate solvent is selected from propyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl Methyl butyrate, ethyl butyrate or a mixture of two or more thereof.
  • 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 of the dehydration step (e) is controlled at 40°C °C-55°C, optionally 45°C-50°C; and/or, control the evaporation temperature in the precipitation step (f) at 60°C-80°C, optionally 65°C-75°C.
  • step (d) step (e) and step (f)
  • the pH of the mixture is maintained at 7-9, preferably 8-9 during evaporation by adding aqueous lithium hydroxide solution.
  • step (d), step (e) and step (f) the concentration of the lithium hydroxide aqueous solution is 1mol/L to 15mol/L, optionally 2mol/L to 10mol/L .
  • step (f) the HF of the lithium bisfluorosulfonimide ⁇ 3 is ⁇ 50 ⁇ g/g and the water content is ⁇ 20 ⁇ g/g.
  • step (e), step (f) and step (g) the ester solvents used are the same.
  • 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, including 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).
  • Figure 4 is a schematic flow diagram of the refining 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 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 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 application is: synthesis ⁇ evaporation ⁇ extraction ⁇ alkalization ⁇ dehydration ⁇ precipitation ⁇ refining (the refining step is an optional process). Each step will be further described below.
  • step (a) the reaction between sulfuryl fluoride, ammonia and triethylamine mainly involves the following main reactions:
  • n 1-12 integer
  • n 1-12 integer.
  • 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) at first, acetonitrile and triethylamine are added in the reaction device, and then a part of ammonia gas is fed, preferably 2%-15% of the total amount of ammonia gas, preferably 3%-10% %, and finally feed ammonia and sulfuryl fluoride to react.
  • 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, the solvent contains at least acetonitrile.
  • the reaction device may be a conventional reaction device used in the art, such as a reaction kettle.
  • the 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 (Et 3 N ⁇ (HF)n) 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 downstream filtration is smaller than that 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 stream ⁇ 1 is also included to remove by-product sulfonamide (NH 2 -SO 2 -NH 2 ) solids, optionally,
  • the filtering step includes filtering with a tetrafluoro filter bag with a pore size of 5 ⁇ m to 20 ⁇ m, optionally 6 ⁇ m to 15 ⁇ m.
  • 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 water phase ⁇ water comprising triethylamine hydrogen fluoride salt are separated into the oil phase ⁇ 3;
  • step (c) the mass ratio of water entering the extraction column or static mixer to 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 alpha water containing triethylamine hydrogen fluoride salt is sent to recovery treatment, and the triethylamine obtained after the aqueous phase alpha water is alkalized and purified can be recycled use.
  • the water phase also contains impurity ions (such as F - , SO 4 2- , FSO 3 - or Cl - ) in addition to triethylamine hydrogen fluoride salt.
  • Triethylamine can be recycled after being alkalized and purified in the recovery section, 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.
  • the oil phase ⁇ 3 obtained in the 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) the basification of step (d) is carried out according to the following equation:
  • the principle of the above 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 LiOH and (SO 2 F-NH-SO 2 F) ⁇ Et 3 N reacts to generate lithium bisfluorosulfonyl imide, abbreviated as LiFSI, and triethylamine is removed by evaporation.
  • LiFSI lithium bisfluorosulfonyl imide
  • 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.
  • 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 oil phase ⁇ 3 to the lithium hydroxide aqueous solution is (0.8-5):1, optionally (1-1.2):1.
  • step (d) during evaporation of stream ⁇ 1-1 under reduced pressure, the pH of the mixture is maintained at 7-9, preferably 8, by adding aqueous lithium hydroxide solution during evaporation. -9.
  • step (d) the evaporation is performed using a falling film evaporator, and the evaporation temperature is controlled at 30°C-40°C, optionally 30°C-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 of lithium bisfluorosulfonyl imide and 5% to 25% by weight of 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 is mixed with an ester solvent, and then evaporated in an evaporator to obtain lithium bisfluorosulfonyl imide Stream ⁇ 2.
  • step (e) the aqueous solution of ester solvent obtained by condensation 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°C-55°C, optionally 45°C-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, 105-130 ° 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.
  • the by-product lithium compounds such as NH2SO3Li , Li2SO4 and LiF
  • centrifugation such as by spatula centrifugation machine 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% to 40% by weight of ester solvent and 0.2% to 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 concentration of the lithium hydroxide aqueous solution is 1mol/L to 15mol/L, optionally 2mol/L to 10mol/L.
  • the stream ⁇ 2 obtained in the step (e) is mixed with an ester solvent, and then evaporated in an evaporator to obtain lithium bisfluorosulfonyl imide ⁇ 3.
  • by-product lithium compounds eg, NH2SO3Li , Li2SO4 , and 2LiF
  • by-product lithium compounds 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 2300 ppm to 2700 ppm.
  • the lithium bisfluorosulfonyl imide ⁇ 3 comprises 80% to 90% by weight of lithium bisfluorosulfonyl imide and 10% to 20% by weight of an ester solvent.
  • step (f) the condensed aqueous solution of the ester solvent is sent to recovery treatment.
  • step (f) the HF of the lithium bisfluorosulfonimide ⁇ 3 is ⁇ 50 ⁇ g/g and the water content is ⁇ 20 ⁇ g/g.
  • refining treatment can be performed, that is, the refining step (g) can be performed.
  • the pH of the mixture is maintained at 7-9, preferably 8-9, by adding aqueous lithium hydroxide solution during evaporation.
  • aqueous lithium hydroxide solution during the steps of alkalization, dehydration and desolventization, the pH of the mixture is maintained at 7-9, preferably 8-9, by adding aqueous lithium hydroxide solution during evaporation.
  • lithium hydroxide solvent Preferably by adding lithium hydroxide solvent, thereby keep weak alkaline system, suppress the decomposition of product.
  • 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.
  • the treatment for crystallization of lithium bisfluorosulfonyl imide ⁇ 3 is not included.
  • the bisfluorosulfonimide lithium ⁇ 3 obtained in the step (f) is sent to the dissolution and acid removal kettle, and an ester solvent and lithium hydroxide are added, and then centrifugal filtration is performed, and the resulting The filtrate g-1 is sent to a dehydration kettle containing molecular sieves for dehydration, and the molecular sieves are removed by filtration, and the resulting filtrate g-2 is sent to a product blender, and optionally demagnetized and filtered.
  • lithium bisfluorosulfonyl imide ⁇ 3 refining operations can be optionally performed to meet the final product requirements.
  • the HF of the lithium bisfluorosulfonyl imide ⁇ 3 is >50 ⁇ g/g and/or the water content is >20 ⁇ g/g
  • acid and water removal operations may be required.
  • lithium hydroxide is added according to the measured HF content, for example, according to the measured HF content, then lithium hydroxide is added according to the molar ratio of HF:lithium hydroxide 1:(1.05-1.10).
  • the molecular sieve is 4A molecular sieve, and the weight of the adsorbed water of the 4A molecular sieve is 15-20% of its own weight.
  • step (g) the lithium hydroxide is in solid form.
  • step (g) the HF of the filtrate g-1 is ⁇ 50 ⁇ g/g.
  • the filtrate g-2 has HF ⁇ 50 ⁇ g/g and water content ⁇ 20 ⁇ g/g.
  • the demagnetization operation is performed, for example, by using a demagnetization filter (such as vertical, horizontal, high-efficiency permanent magnet, drum or electromagnetic), and the demagnetization
  • a demagnetization filter such as vertical, horizontal, high-efficiency permanent magnet, drum or electromagnetic
  • the magnetic field strength of the magnetic filter may be 5,000-12,000 Gauss, preferably 6,000-9,000 Gauss.
  • step (f) and step (g) the centrifugation is performed using a scraper centrifuge or a disc centrifuge.
  • the ester solvents are each independently selected from the group having a boiling point greater than 70°C, preferably greater than 80°C, preferably 100-130°C and Organic solvent immiscible with water.
  • the ester solvent contains a carbonate solvent, further optionally, the carbonate solvent is selected from ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, carbonic acid Dipropyl ester, 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
  • the carbonate solvent is selected from propyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyric acid Methyl ester, ethyl butyrate or a mixture of two or more thereof.
  • the ester solvent is at least one selected from ethyl methyl carbonate, dimethyl carbonate and diethyl carbonate.
  • step (e), step (f) and step (g) is the same.
  • 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.
  • the raw and auxiliary materials used in the LiFSI synthesis process route of this application 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, hot water at 35°C was used to heat stream ⁇ 1-1, and the vacuum was turned on to keep the vacuum degree in the kettle at -0.08MPa, and the steaming time was 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.
  • an aqueous solution of lithium hydroxide (concentration 5 mol/L) was added to keep the pH of the stream ⁇ 1-2 at 8.
  • 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 obtained after evaporation 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 a mixture containing 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 powder obtained by drying the lithium bisfluorosulfonimide with a concentration of 28% by weight is 99.4%, and the yield reaches 95%, wherein the free acid content is 20 ⁇ g/g, and the moisture content is 25 ⁇ 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 powder obtained by drying the above-mentioned lithium bisfluorosulfonyl imide ⁇ 3 was 99.0%, and the yield reached 92%, wherein the free acid content was 25 ⁇ g/g, and the moisture content was 30 ⁇ 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

本申请涉及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；(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；以及任选地(g)精制步骤。本申请的方法可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。

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、包含所述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。本申请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、水分达到电池级的标准，生产成本低且三废少，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、生产成本高和三废多的问题。
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、包含所述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装置中反应，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与酯类溶剂混合，然后在蒸发器中进行蒸发，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与酯类溶剂混合，然后在蒸发器中进行蒸发，得到双氟磺酰亚胺锂β3；以及任选地
(g)精制步骤：将步骤(f)得到的双氟磺酰亚胺锂β3送至溶解除酸釜中并加入酯类溶剂和氢氧化锂，然后进行离心过滤，将所得滤液g-1送至包含分子筛的脱水釜除水，通过过滤除去分子筛，所得滤液g-2送至产品调配釡，并任选地进行除磁和过滤处理。
应用本申请的制备方法可获得纯度高、水分少的LiFSI。同时，它的生产成本低且三废少。
在任意实施方式中，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)。
在任意实施方式中，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；优选地，所述溶剂至少含有乙腈。
在任意实施方式中，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。
在任意实施方式中，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。可选地，所述过滤的步骤包括采用孔径为5μm至20μm的四氟过滤袋进行过滤。
在任意实施方式中，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，在步骤(c)中，将包含三乙胺氟化氢盐的水相α 水送至回收处理，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，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，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，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。
在任意实施方式中，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，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，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2300ppm～2700ppm的含水量。
在任意实施方式中，在步骤(b)、步骤(d)、步骤(e)和步骤(f)中的蒸发可在一个或多个蒸发器中进行。
在任意实施方式中，在步骤(f)和步骤(g)中，所述离心采用刮刀离心机或碟式离心机进行。
在任意实施方式中，在步骤(e)、步骤(f)和步骤(g)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，进一步可选地，所述碳酸酯类溶剂选自碳酸亚乙酯、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。和/或，所述酯类溶剂含有羧酸酯类溶剂，进一步可选地，所述羧酸酯类溶剂选自乙酸丙酯、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。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，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，在步骤(d)、步骤(e)和步骤(f)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。
在任意实施方式中，在步骤(d)、步骤(e)和步骤(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。
在任意实施方式中，在步骤(f)中，所述双氟磺酰亚胺锂β3的HF≤50μg/g且含水量≤20μg/g。
在任意实施方式中，在步骤(e)、步骤(f)和步骤(g)中，所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是精制工艺的流程示意图。
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，否则本申请上下文中的含量和百分比均基于质量计。
本申请的工艺路线为：合成→蒸发→萃取→碱化→脱水→脱溶→精制(精制步骤为任选的工序)。在下文中将进一步描述各个步骤。
[合成步骤]
在本申请的合成步骤(a)中，将硫酰氟、氨气和三乙胺在溶剂的存在下在反应装置中反应，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；
在一些实施方式中，在步骤(a)中，硫酰氟、氨气与三乙胺之间的反应主要涉及以下主反应:
6SO 2F 2+3NH 3+5Et 3N→3(SO 2F-NH-SO 2F)·Et 3N+2Et 3N·(HF)n
其中n＝1-12的整数；
同时，还伴随着以下副反应：
6NH 3+3SO 2F 2+5Et 3N→3NH 2-SO 2-NH 2+2Et 3N·(HF)n
其中n＝1-12的整数。
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，优选地，所述溶剂至少含有乙腈。
在本申请中，在步骤(a)中，所述反应装置可为本领域常规使用的反应装置，例如反应釜。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。
本申请的发明人发现，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(Et 3N·(HF)n)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]
在本申请的蒸发步骤(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，可选地，所述过滤的步骤包括采用孔径为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]
在本申请的萃取步骤(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。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，例如茜素络合比色法测定F离子含量、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]
在本申请的碱化步骤(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)的碱化按照以下反应式进行：
(SO 2F-NH-SO 2F)·Et 3N+LiOH→(SO 2F-N-SO 2F) -Li +(LiFSI)+Et 3N+H 2O。
上述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，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，然后通过蒸发移出三乙胺。
在一些实施方案中，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。
在一些实施方案中，在步骤(d)中，在将料流β1-1进行减压蒸发的过程中，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(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重量％至90重量％的双氟磺酰亚胺锂和5重量％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]
在本申请的脱水步骤(e)中，将包含双氟磺酰亚胺锂的料流β1-2与酯类溶剂混合，然后在蒸发器中进行蒸发，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105-130℃)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，在步骤(d)、步骤(e)和步骤(f)期间加入氢氧化锂的过程中还存在以下副反应：
(SO 2F-N-SO 2F) -Li ++4LiOH→NH 2SO 3Li+Li 2SO 4+2LiF+H 2O
因此，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。
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％至80重量％的双氟磺酰亚胺锂、20重量％至40重量％的酯类溶剂和0.2重量％至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]
在本申请的脱溶步骤(f)中，将步骤(e)得到的料流β2与酯类溶剂混合，然后在蒸发器中进行蒸发，得到双氟磺酰亚胺锂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2LiF)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2300ppm～2700ppm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％至90重量％的双氟磺酰亚胺锂和10重量％至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。
在一些实施方案中，在步骤(f)中，所述双氟磺酰亚胺锂β3的HF≤50μg/g且含水量≤20μg/g。当所述双氟磺酰亚胺锂β3不满足上述含量时，可进行精制处理，即进行精制步骤(g)。
在本申请中，在碱化、脱水和脱溶步骤的过程中，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。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。
在一些实施方案中，在本申请的方法中，不包括对双氟磺酰亚胺锂β3进行析出晶体的处理。
[精制步骤]
在本申请的精制步骤(g)中，将步骤(f)得到的双氟磺酰亚胺锂β3送至溶解除酸釜中并加入酯类溶剂和氢氧化锂，然后进行离心过滤，将所得滤液g-1送至包含分子筛的脱水釜除水，通过过滤除去分子筛，所得滤液g-2送至产品调配釡，并任选地进行除磁和过滤处理。
在本申请中，可根据双氟磺酰亚胺锂β3的具体组成，任选地进行精制操作，以满足最终的产品要求。例如，当所述双氟磺酰亚胺锂β3的HF＞50μg/g和/或含水量＞20μg/g时，可能需要进行除酸和除水操作。首先，根据所测定的HF的含量添加氢氧化锂，例如，根据测定的HF含量，然后按照HF：氢氧化锂1：(1.05-1.10)的摩尔比添加氢氧化锂。然后，离心过滤掉杂质(LiF、HF与LiOH反应生成的LiF)并加入分子筛除水，所述分子筛为4A分子筛，所述4A分子筛的吸附水的重量为其本身重量的15-20％。
在一些实施方案中，在步骤(g)中，所述氢氧化锂为固体形式。
在一些实施方案中，在步骤(g)中，所述滤液g-1的HF≤50μg/g。
在一些实施方案中，在步骤(g)中，所述滤液g-2的HF≤50μg/g且含水量≤20μg/g。
在一些实施方案中，在步骤(g)中，所述除磁操例如通过使用除磁过滤器(例如立式、卧式、高效永磁式、转鼓式或电磁式)进行，所述除磁过滤器的磁场强度可为5,000-12,000高斯，优选6,000-9,000 高斯。
在一些实施方案中，在步骤(f)和步骤(g)中，所述离心采用刮刀离心机或碟式离心机进行。
在一些实施方案中，在步骤(e)、步骤(f)和步骤(g)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，例如所述酯类溶剂含有碳酸酯类溶剂，进一步可选地，所述碳酸酯类溶剂选自碳酸亚乙酯、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。和/或，所述酯类溶剂含有羧酸酯类溶剂，进一步可选地，所述碳酸酯类溶剂选自乙酸丙酯、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。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。
在一些实施方案中，在步骤(e)、步骤(f)和步骤(g)中，所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。
本申请的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(26000kg)，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℃℃热水进行加热料流β1-1，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)。
【精制步骤】
结合图4来描述任选的精制步骤。
将70L碳酸二乙酯和0.1kg氢氧化锂加入30kg双氟磺酰亚胺锂β3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g-1(HF≤50μg/g)送至脱水釜，脱水釜中加入20kg分子筛，搅拌转速800rpm，处理2h。然后使用过滤器过滤掉分子筛，将所得滤液g-2(水含量≤20μg/g)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，最后进行罐装。
经检测，通过干燥上述浓度为28重量％的双氟磺酰亚胺锂所得粉末的纯度为99.4％，收率达到95％，其中，游离酸含量为20μg/g、水分含量为25μg/g。
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，通过干燥上述双氟磺酰亚胺锂β3所得粉末的纯度为99.0％，收率达到92％，其中，游离酸含量为25μg/g、水分含量为30μg/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 (24)

  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装置中反应，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与酯类溶剂混合，然后在蒸发器中进行蒸发，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与酯类溶剂混合，然后在蒸发器中进行蒸发，得到双氟磺酰亚胺锂β3；以及任选地
    (g)精制步骤：将步骤(f)得到的所述双氟磺酰亚胺锂β3送至溶解除酸釜中并加入酯类溶剂和氢氧化锂，然后进行离心过滤，将所得滤液g-1送至包含分子筛的脱水釜除水，通过过滤除去分子筛，所得滤液g-2送至产品调配釡，并任选地进行除磁和过滤处理。
  2. 根据权利要求1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)。
  3. 根据权利要求1或2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；优选地，所述溶剂至少含有乙腈。
  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。
  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)和步骤(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，所述过滤的步骤包括采用孔径为5μm至20μm的四氟过滤袋进行过滤。
  6. 根据权利要求1至5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。
  7. 根据权利要求1至6中任一项所述的方法，其中，在步骤(c)中，将所述包含三乙胺氟化氢盐的水相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。
  8. 根据权利要求1至7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。
  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。
  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，其中所述油相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。
  11. 根据权利要求1至10中任一项所述的方法，其中，在步骤(e)和步骤(f)中，将冷凝得到的所述酯类溶剂的水溶液送至回收处理。
  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)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。
  13. 根据权利要求1至12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β3具有2000ppm至4000ppm的含水量，优选2300ppm～2700ppm的含水量。
  14. 根据权利要求1至13中任一项所述的方法，其中，在步骤(b)、步骤(d)、步骤(e)和步骤(f)中的蒸发可在一个或多个蒸发器中进行。
  15. 根据权利要求1至14中任一项所述的方法，其中，在步骤(g)中，所述离心采用刮刀离心机或碟式离心机进行。
  16. 根据权利要求1至15中任一项所述的方法，其中，在步骤(e)、步骤(f)和步骤(g)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，进一步可选地，所述碳酸酯类溶剂选自碳酸亚乙酯、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；和/或，
    所述酯类溶剂含有羧酸酯类溶剂，进一步可选地，所述羧酸酯类溶剂选自乙酸丙酯、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；
    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。
  17. 根据权利要求1至16中任一项所述的方法，其中，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℃。
  18. 根据权利要求1至17中任一项所述的方法，其中，在步骤(d)、步骤(e)和步骤(f)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。
  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，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。
  20. 根据权利要求1至19中任一项所述的方法，其中，在步骤(f)中，所述双氟磺酰亚胺锂β3的HF≤50μg/g且含水量≤20μg/g。
  21. 根据权利要求1至20中任一项所述的方法，其中，在步骤(e)、步骤(f)和步骤(g)中，所使用的酯类溶剂是相同的。
  22. 双氟磺酰亚胺锂，其通过权利要求1至21中任一项所述的方法制备。
  23. 一种电解液，其包括通过权利要求1-21中任一项所述的方法制备的双氟磺酰亚胺锂。
  24. 一种二次电池，其包括根据权利要求23所述的电解液。
PCT/CN2022/074934 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 WO2023142026A1 (zh)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102378755A (zh) * 2009-03-31 2012-03-14 中央硝子株式会社 酰亚胺酸化合物的制造方法
CN106044728A (zh) * 2016-05-27 2016-10-26 上海康鹏科技有限公司 一种双氟磺酰亚胺锂盐的制备方法
CN110436424A (zh) * 2019-07-04 2019-11-12 湖南福邦新材料有限公司 一种双氟磺酰亚胺及双氟磺酰亚胺锂的制备方法
WO2020102907A1 (fr) * 2018-11-21 2020-05-28 HYDRO-QUéBEC Compositions polymériques comprenant au moins deux sels de lithium et leur utilisation dans des cellules électrochimiques

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102378755A (zh) * 2009-03-31 2012-03-14 中央硝子株式会社 酰亚胺酸化合物的制造方法
CN106044728A (zh) * 2016-05-27 2016-10-26 上海康鹏科技有限公司 一种双氟磺酰亚胺锂盐的制备方法
WO2020102907A1 (fr) * 2018-11-21 2020-05-28 HYDRO-QUéBEC Compositions polymériques comprenant au moins deux sels de lithium et leur utilisation dans des cellules électrochimiques
CN110436424A (zh) * 2019-07-04 2019-11-12 湖南福邦新材料有限公司 一种双氟磺酰亚胺及双氟磺酰亚胺锂的制备方法

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