A method for preparing lithium bisfluorosulfonylimide using sulfonyl fluoride

Abstract

The present application relates to the technical field of lithium battery, and in particular to a method for preparing lithium bisfluorosulfonimide by using sulfuric fluoride; the present application adopts sulfuric fluoride, ammonia gas, organic base, solvent and lithium hydroxide to prepare lithium bisfluorosulfonimide; the present application firstly purifies preliminarily through distillation and extraction, then filters, and further removes trace impurity components in the crude product after adsorption by fluoric acid group molecular sieve, so as to obtain high-purity lithium bisfluorosulfonimide; the process route of the present application avoids the generation of waste gas such as SO2 and HCl, and is more in line with environmental protection requirements; the present application has the advantages of simple process, strong operability, very obvious purification effect and the like, and has the conditions for industrial production.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a method for preparing lithium difluorosulfonyl imide using sulfuryl fluoride. Background Technology

[0002] Lithium-ion batteries, developed in the 1990s, are a new type of high-energy rechargeable battery and have become one of the most promising battery systems. They possess excellent properties such as high energy density, small size, light weight, high-rate discharge capability, low self-discharge rate, long cycle life, non-toxicity, and no memory effect, making them widely used in portable electronic products, new energy vehicles, and energy storage.

[0003] Lithium difluorosulfonylimide (Li₂F₃) is a novel electrolyte lithium salt, considered the most likely replacement for lithium hexafluorophosphate (Li₂F₃). In addition, Li₂F₃ possesses the following characteristics: compared to Li₂F₃, Li₂F₃ dissociates lithium ions more easily, resulting in higher conductivity; its decomposition temperature is above 200°C, thus exhibiting higher thermal stability and safety; it has good compatibility with electrodes, offering unique advantages in improving low-temperature discharge and high-temperature storage; and it is environmentally friendly and highly safe, possessing the basic conditions for industrialization and gradually becoming a focus of attention in the battery field.

[0004] Chinese Patent CN202211723748.5: Provides a method for preparing lithium bis(fluorosulfonyl)imide, comprising the following steps: (1) mixing chlorosulfonyl isocyanate and fluorosulfonic acid, and continuously introducing anhydrous hydrogen fluoride gas under stirring, and reacting at 25-130°C for 4-30 hours under the action of a catalyst to synthesize bis(fluorosulfonyl)imide; (2) mixing bis(fluorosulfonyl)imide with an organic solvent, adding lithium alloy, and reacting at 15-120°C for 0.5-15 hours, and obtaining lithium bis(fluorosulfonyl)imide after filtration and vacuum distillation of the product.

[0005] Chinese Patent CN202211730109.1: Provides a method for preparing bis(fluorosulfonyl)imide, a lithium bis(fluorosulfonyl)imide, and their preparation method and application. The method for preparing bis(fluorosulfonyl)imide includes: reacting sulfonyl fluoride and hexamethylsilane under an inert atmosphere to obtain an intermediate product, and performing gas-phase separation on the intermediate product to obtain bis(fluorosulfonyl)imide.

[0006] Chinese Patent CN202111101717.1: Belongs to the field of preparation of lithium bisfluorosulfonylimide, specifically relating to a method for preparing lithium bisfluorosulfonylimide. The method includes the following steps: reacting bisfluorosulfonylimide with lithium phosphate in a non-aqueous solvent to obtain a reaction solution containing lithium bisfluorosulfonylimide, followed by post-treatment to obtain lithium bisfluorosulfonylimide.

[0007] The above patents and existing technologies all employ a production process that uses bis(chlorosulfonyl)imide (HClSI) as a raw material, synthesizing LiFSI through fluorination and lithiation (salt formation) reactions. The industrial synthesis processes for HClSI mainly include two methods: the aminosulfonic acid / chlorosulfonic acid method and the aminosulfonic acid / chlorosulfonyl isocyanate method; fluorinating agents mainly include hydrogen fluoride, ammonium fluoride, and potassium fluoride; lithiation agents mainly include lithium hydroxide monohydrate, lithium acetate, lithium carbonate, and lithium halides; and lithiation reaction solvents mainly include dichloromethane, ethers, and carbonates. The lithium bis(chlorosulfonyl)imide prepared by existing technologies suffers from drawbacks such as low purity, low yield, complex processes, and high costs.

[0008] Lithium difluorosulfonylimide (LiDI) exhibits excessive levels of residual metal ions, primarily non-heavy metals such as potassium, sodium, magnesium, iron, calcium, and lead. Methods for removing these residual metal ions include using adsorbents such as diatomaceous earth or zeolite powder, and adding cation exchange resins during the preparation process. However, while these methods are effective at removing metal ions, they suffer from drawbacks such as poor removal efficiency, increased metal ion residue, and a tendency to cause excessive acid values. While thionyl chloride can remove water from LiDI, it also introduces difficult-to-remove SO3. 2- The presence of ions increases the difficulty of subsequent purification of lithium bisfluorosulfonylimide. Therefore, further improvements are needed in the purification of lithium bisfluorosulfonylimide. Summary of the Invention

[0009] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for preparing lithium difluorosulfonyl imide using sulfuryl fluoride. The method involves preparing lithium difluorosulfonyl imide using sulfuryl fluoride, ammonia, organic base, solvent, and lithium hydroxide. After preliminary purification by distillation and extraction, the product is filtered and then adsorbed through a fluoropeptide molecular sieve to further remove trace impurities from the crude product, thereby obtaining high-purity lithium difluorosulfonyl imide.

[0010] To achieve the above and other related objectives, the present invention provides a method for preparing lithium bis(fluorosulfonyl)imide using sulfuryl fluoride, the operation steps of which are as follows:

[0011] S1: Weigh out sulfuryl fluoride, ammonia, organic base and solvent by weight and react them in a reaction vessel to obtain the organic base salt of difluorosulfonyl imide;

[0012] S2: Evaporate the organic base salt of bis(fluorosulfonyl)imide, and recover and recycle the evaporated solvent and organic base;

[0013] S3: After extraction and evaporation of the organic base salt of bis(fluorosulfonyl)imide, an aqueous solution of lithium hydroxide is added, and the reaction is carried out for 1-3 hours to obtain crude bis(fluorosulfonyl)imide.

[0014] S4: Crude lithium difluorosulfonylimide is evaporated, then ester solvent and 10-20% lithium hydroxide aqueous solution are added, mixed and stirred, filtered, and then adsorbed through a fluoropeptide molecular sieve with a mass percentage of 3-8% of the crude lithium difluorosulfonylimide to obtain lithium difluorosulfonylimide.

[0015] Preferably, the molar ratio of thioyl fluoride: ammonia: organic base: solvent is (1-3):1:(1-5):(30-50).

[0016] Preferably, the organic base is one or more of triethylamine, triethylenediamine, 1,8-diazabicycloundec-7-ene, 1,5-diazabicyclo[4.3.0]-5-nonene, 4-dimethylaminopyridine, pyridine, N-methylmorpholine and tetramethylethylenediamine.

[0017] Preferably, the solvent is any two or more of acetonitrile and propionitrile, isopropionitrile, diethyl ether, propyl ether, isopropyl ether, tetrahydrofuran, acetone, butanone, methyl isobutyl ketone, and methyl pyrrolidone.

[0018] Preferably, the reaction temperature of S1 is 5-25℃ and the reaction pressure is 0.2-0.3MPa.

[0019] Preferably, the volume ratio of the organic base salt of bis(fluorosulfonyl)imide to lithium hydroxide in S3 is 1:(1-1.2).

[0020] Preferably, the evaporation temperature is 30-50°C.

[0021] Preferably, the ester solvent is at least one selected from methyl ethyl carbonate, dimethyl carbonate, and diethyl carbonate.

[0022] Preferably, the preparation method of the fluoropeptide-based molecular sieve is as follows:

[0023] S1: According to the mass fraction, 0.1-1 parts of H2PtCl6·6H2O and 100-500 parts of isopropanol are added at once to a nitrogen-protected reactor and stirred at room temperature for 1-5 hours to obtain Speiers catalyst;

[0024] S2: According to the mass fractions, add 2-5 parts of 3,4,5,6-tetrafluoropeptide acid, 10-15 parts of 4-vinyl-1,2-phthalic acid, 100-200 parts of allyl-modified MCM-41 mesoporous molecular sieve, 1000-1500 parts of N,N-dimethylformamide, and 0.03-0.6 parts of Speiers catalyst to a stirred tank, stir at 70-80℃ for 50-100 min, then add benzoyl peroxide, continue stirring for 100-140 min, filter, wash with deionized water until neutral, and dry to obtain gold fluoropeptide acid-based molecular sieve.

[0025] Preferably, the preparation method of the allyl-modified MCM-41 mesoporous molecular sieve is as follows:

[0026] According to the mass fractions, 2-5 parts of allyl dimethoxysilane, 2-5 parts of MCM-41 mesoporous molecular sieve, and 2-5 parts of deionized water are stirred at 70-80℃ for 50-100 min, filtered, and dried to obtain allyl modified MCM-41 mesoporous molecular sieve.

[0027] The method for preparing lithium bis(fluorosulfonyl)imide using sulfuryl fluoride of the present invention has the following significant advantages compared with the prior art:

[0028] 1. This invention first purifies the crude product through distillation and extraction, followed by filtration and further purification using a fluoropeptide-based molecular sieve to remove trace metal impurities. In the fluoropeptide molecular sieve, multiple functional groups can simultaneously bind to metal ions, significantly improving the adsorption rate and selectivity. Most metal ions can form complex chelate structures on the chelating agent surface. Due to the wide pore size and specific surface area of ​​the fluoropeptide-based molecular sieve, it can efficiently adsorb various metal ions, resulting in high-purity lithium bis(fluorosulfonyl)imide with low metal ion residue.

[0029] 2. The process route of this invention avoids the generation of waste gases such as SO2 and HCl, which is more in line with environmental protection requirements;

[0030] 3. The present invention has the advantages of simple process, strong operability, and obvious purification effect, and has the conditions for industrial production. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below through specific embodiments. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention.

[0032] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0033] In a specific embodiment of the present invention, product purity and yield are calculated using the following formula:

[0034] 1. Purity: The purity of lithium bis(fluorosulfonyl)imide = mass of lithium bis(fluorosulfonyl)imide in the mixture ÷ mass of the mixture × 100%;

[0035] 2. Yield: The yield of lithium bis(fluorosulfonyl)imide = actual amount of lithium bis(fluorosulfonyl)imide produced / theoretical amount of lithium bis(fluorosulfonyl)imide produced × 100%.

[0036] Example 1

[0037] A method for preparing lithium bis(fluorosulfonyl)imide using sulfuryl fluoride, comprising the following steps:

[0038] S1: Weigh out sulfuryl fluoride, ammonia, organic base and solvent and react them in a reaction vessel to obtain the organic base salt of difluorosulfonyl imide;

[0039] S2: Evaporate the organic base salt of bis(fluorosulfonyl)imide, and recover and recycle the evaporated solvent and organic base;

[0040] S3: After extraction and evaporation of the organic base salt of bis(fluorosulfonyl)imide, an aqueous solution of lithium hydroxide is added, and the reaction is carried out for 1 hour to obtain crude bis(fluorosulfonyl)imide.

[0041] S4: Crude lithium difluorosulfonylimide was evaporated, then an ester solvent and a 10% lithium hydroxide aqueous solution were added, mixed and stirred, filtered, and then adsorbed through a 3% (by mass) fluoropeptide molecular sieve to obtain lithium difluorosulfonylimide.

[0042] The molar ratio of sulfuryl fluoride: ammonia: organic base: solvent is 1:1:1:30.

[0043] The organic base mentioned is triethylamine.

[0044] The solvent is a mixture of acetonitrile and propionitrile.

[0045] The reaction temperature of S1 is 5℃ and the reaction pressure is 0.2MPa.

[0046] In S3, the volume ratio of the organic base salt of bis(fluorosulfonyl)imide to lithium hydroxide is 1:1.

[0047] The evaporation temperature is 30°C.

[0048] The ester solvent mentioned is ethyl methyl carbonate.

[0049] The preparation method of the fluoropeptide-based molecular sieve is as follows:

[0050] S1: 0.1g H2PtCl6·6H2O and 100g isopropanol were added at once to a nitrogen-protected reactor and stirred at room temperature for 1 hour to obtain Speiers catalyst;

[0051] S2: 2g of 3,4,5,6-tetrafluoropeptide acid, 10g of 4-vinyl-1,2-phthalic acid, 100g of allyl-modified MCM-41 mesoporous molecular sieve, 1000g of N,N-dimethylformamide, and 0.03g of Speiers catalyst were added to a stirred tank and stirred at 70℃ for 50min. Then, benzoyl peroxide was added and stirring was continued for 100min. The mixture was filtered, washed with deionized water until neutral, and dried to obtain gold fluoropeptide acid-based molecular sieve.

[0052] The preparation method of the allyl-modified MCM-41 mesoporous molecular sieve is as follows:

[0053] 2g of allyl dimethoxysilane, 2g of MCM-41 mesoporous molecular sieve, and 2g of deionized water were stirred at 70℃ for 50min, filtered, and dried to obtain allyl modified MCM-41 mesoporous molecular sieve.

[0054] In this embodiment, the purity of lithium bis(fluorosulfonyl)imide was calculated to be 99.95%, and the reaction yield was 94.07%.

[0055] Example 2

[0056] A method for preparing lithium bis(fluorosulfonyl)imide using sulfuryl fluoride, comprising the following steps:

[0057] S1: Weigh out sulfuryl fluoride, ammonia, organic base and solvent and react them in a reaction vessel to obtain the organic base salt of difluorosulfonyl imide;

[0058] S2: Evaporate the organic base salt of bis(fluorosulfonyl)imide, and recover and recycle the evaporated solvent and organic base;

[0059] S3: After extraction and evaporation of the organic base salt of bis(fluorosulfonyl)imide, an aqueous solution of lithium hydroxide is added, and the reaction is carried out for 2 hours to obtain crude bis(fluorosulfonyl)imide.

[0060] S4: Crude lithium difluorosulfonylimide is evaporated, then ester solvent and 15% lithium hydroxide aqueous solution are added, mixed and stirred, filtered, and then adsorbed through a 5% (by mass) fluoropeptide molecular sieve to obtain lithium difluorosulfonylimide.

[0061] The molar ratio of sulfuryl fluoride: ammonia: organic base: solvent is 2:1:2:35.

[0062] The organic base mentioned is triethylamine.

[0063] The solvent is a mixture of acetonitrile and diethyl ether.

[0064] The reaction temperature of S1 is 10℃ and the reaction pressure is 0.25MPa.

[0065] The volume ratio of the organic base salt of bis(fluorosulfonyl)imide to lithium hydroxide in S3 is 1:1.1.

[0066] The evaporation temperature is 35°C.

[0067] The ester solvent mentioned is dimethyl carbonate.

[0068] The preparation method of the fluoropeptide-based molecular sieve is as follows:

[0069] S1: 0.4 g H2PtCl6·6H2O and 200 g isopropanol were added to a nitrogen-protected reactor at one time and stirred at room temperature for 2 hours to obtain Speiers catalyst;

[0070] S2: Add 3g of 3,4,5,6-tetrafluoropeptide acid, 12g of 4-vinyl-1,2-phthalic acid, 140g of allyl-modified MCM-41 mesoporous molecular sieve, 1100g of N,N-dimethylformamide, and 0.2g of Speiers catalyst to a stirred tank and stir at 75°C for 60min. Then add benzoyl peroxide and continue stirring for 110min. Filter, wash with deionized water until neutral, and dry to obtain gold fluoropeptide acid-based molecular sieve.

[0071] The preparation method of the allyl-modified MCM-41 mesoporous molecular sieve is as follows:

[0072] 3g of allyl dimethoxysilane, 3g of MCM-41 mesoporous molecular sieve, and 3g of deionized water were stirred at 75℃ for 60min, filtered, and dried to obtain allyl-modified MCM-41 mesoporous molecular sieve.

[0073] In this embodiment, the purity of lithium bis(fluorosulfonyl)imide was calculated to be 99.96%, and the reaction yield was 93.91%.

[0074] Example 3

[0075] A method for preparing lithium bis(fluorosulfonyl)imide using sulfuryl fluoride, comprising the following steps:

[0076] S1: Weigh out sulfuryl fluoride, ammonia, organic base and solvent and react them in a reaction vessel to obtain the organic base salt of difluorosulfonyl imide;

[0077] S2: Evaporate the organic base salt of bis(fluorosulfonyl)imide, and recover and recycle the evaporated solvent and organic base;

[0078] S3: After extraction and evaporation of the organic base salt of bis(fluorosulfonyl)imide, an aqueous solution of lithium hydroxide is added, and the reaction is carried out for 2 hours to obtain crude bis(fluorosulfonyl)imide.

[0079] S4: Crude lithium difluorosulfonylimide was evaporated, then an ester solvent and a 15% lithium hydroxide aqueous solution were added, mixed and stirred, filtered, and then adsorbed through a 7% (by mass) fluoropeptide molecular sieve to obtain lithium difluorosulfonylimide.

[0080] The molar ratio of sulfuryl fluoride: ammonia: organic base: solvent is 2:1:4:45.

[0081] The organic base mentioned is triethylamine.

[0082] The solvent is a mixture of acetonitrile and tetrahydrofuran.

[0083] The reaction temperature of S1 is 15℃ and the reaction pressure is 0.25MPa.

[0084] The volume ratio of the organic base salt of bis(fluorosulfonyl)imide to lithium hydroxide in S3 is 1:1.1.

[0085] The evaporation temperature is 45°C.

[0086] The ester solvent mentioned is dimethyl carbonate.

[0087] The preparation method of the fluoropeptide-based molecular sieve is as follows:

[0088] S1: 0.8 g H2PtCl6·6H2O and 400 g isopropanol were added to a nitrogen-protected reactor at one time and stirred at room temperature for 4 hours to obtain Speiers catalyst;

[0089] S2: Add 4g of 3,4,5,6-tetrafluoropeptide acid, 14g of 4-vinyl-1,2-phthalic acid, 180g of allyl-modified MCM-41 mesoporous molecular sieve, 1400g of N,N-dimethylformamide, and 0.4g of Speiers catalyst to a stirred tank and stir at 75°C for 80min. Then add benzoyl peroxide and continue stirring for 130min. Filter, wash with deionized water until neutral, and dry to obtain gold fluoropeptide acid-based molecular sieve.

[0090] The preparation method of the allyl-modified MCM-41 mesoporous molecular sieve is as follows:

[0091] 4g of allyl dimethoxysilane, 4g of MCM-41 mesoporous molecular sieve, and 4g of deionized water were stirred at 75℃ for 80min, filtered, and dried to obtain allyl modified MCM-41 mesoporous molecular sieve.

[0092] In this embodiment, the purity of lithium bis(fluorosulfonyl)imide was calculated to be 99.99%, and the reaction yield was 96.02%.

[0093] Example 4

[0094] A method for preparing lithium bis(fluorosulfonyl)imide using sulfuryl fluoride, comprising the following steps:

[0095] S1: Weigh out sulfuryl fluoride, ammonia, organic base and solvent and react them in a reaction vessel to obtain the organic base salt of difluorosulfonyl imide;

[0096] S2: Evaporate the organic base salt of bis(fluorosulfonyl)imide, and recover and recycle the evaporated solvent and organic base;

[0097] S3: After extraction and evaporation of the organic base salt of bis(fluorosulfonyl)imide, an aqueous solution of lithium hydroxide is added, and the reaction is carried out for 3 hours to obtain crude bis(fluorosulfonyl)imide.

[0098] S4: Crude lithium difluorosulfonylimide was evaporated, then an ester solvent and a 20% lithium hydroxide aqueous solution were added, mixed and stirred, filtered, and then adsorbed through a fluoropeptide molecular sieve with a mass percentage of 8% of the crude lithium difluorosulfonylimide to obtain lithium difluorosulfonylimide.

[0099] The molar ratio of sulfuryl fluoride: ammonia: organic base: solvent is 3:1:5:50.

[0100] The organic base mentioned is triethylamine.

[0101] The solvent is a mixture of acetonitrile and acetone.

[0102] The reaction temperature of S1 is 25°C and the reaction pressure is 0.3 MPa.

[0103] The volume ratio of the organic base salt of bis(fluorosulfonyl)imide to lithium hydroxide in S3 is 1:1.2.

[0104] The evaporation temperature is 50°C.

[0105] The ester solvent mentioned is diethyl carbonate.

[0106] The preparation method of the fluoropeptide-based molecular sieve is as follows:

[0107] S1: 1g H2PtCl6·6H2O and 500g isopropanol were added to a nitrogen-protected reactor at one time and stirred at room temperature for 5 hours to obtain Speiers catalyst;

[0108] S2: Add 5g of 3,4,5,6-tetrafluoropeptide acid, 15g of 4-vinyl-1,2-phthalic acid, 200g of allyl-modified MCM-41 mesoporous molecular sieve, 1500g of N,N-dimethylformamide, and 0.6g of Speiers catalyst to a stirred tank and stir at 80℃ for 100min. Then add benzoyl peroxide and continue stirring for 140min. Filter, wash with deionized water until neutral, and dry to obtain gold fluoropeptide acid-based molecular sieve.

[0109] The preparation method of the allyl-modified MCM-41 mesoporous molecular sieve is as follows:

[0110] 5g of allyl dimethoxysilane, 5g of MCM-41 mesoporous molecular sieve, and 5g of deionized water were stirred at 80℃ for 100min, filtered, and dried to obtain allyl modified MCM-41 mesoporous molecular sieve.

[0111] In this embodiment, the purity of lithium bis(fluorosulfonyl)imide was calculated to be 99.98%, and the reaction yield was 95.33%.

[0112] Comparative Example 1

[0113] A method for preparing lithium bis(fluorosulfonyl)imide using sulfuryl fluoride, comprising the following steps:

[0114] S1: Weigh out sulfuryl fluoride, ammonia, organic base and solvent and react them in a reaction vessel to obtain the organic base salt of difluorosulfonyl imide;

[0115] S2: Evaporate the organic base salt of bis(fluorosulfonyl)imide, and recover and recycle the evaporated solvent and organic base;

[0116] S3: After extraction and evaporation of the organic base salt of bis(fluorosulfonyl)imide, an aqueous solution of lithium hydroxide is added, and the reaction is carried out for 1 hour to obtain crude bis(fluorosulfonyl)imide.

[0117] S4: Crude lithium difluorosulfonylimide was evaporated, then an ester solvent and a 10% lithium hydroxide aqueous solution were added, mixed and stirred, filtered, and then adsorbed through a 3% (by mass) fluoropeptide molecular sieve to obtain lithium difluorosulfonylimide.

[0118] The molar ratio of sulfuryl fluoride: ammonia: organic base: solvent is 1:1:1:30.

[0119] The organic base mentioned is triethylamine.

[0120] The solvent is a mixture of acetonitrile and propionitrile.

[0121] The reaction temperature of S1 is 5℃ and the reaction pressure is 0.2MPa.

[0122] In S3, the volume ratio of the organic base salt of bis(fluorosulfonyl)imide to lithium hydroxide is 1:1.

[0123] The evaporation temperature is 30°C.

[0124] The ester solvent mentioned is ethyl methyl carbonate.

[0125] The preparation method of the fluoropeptide-based molecular sieve is as follows:

[0126] S1: 0.1g H2PtCl6·6H2O and 100g isopropanol were added at once to a nitrogen-protected reactor and stirred at room temperature for 1 hour to obtain Speiers catalyst;

[0127] S2: Add 2g of 3,4,5,6-tetrafluoropeptide acid, 10g of 4-vinyl-1,2-phthalic acid, 1000g of N,N-dimethylformamide, and 0.03g of Speiers catalyst to a stirred tank and stir at 70℃ for 50min. Then add benzoyl peroxide and continue stirring for 100min. Filter, wash with deionized water until neutral, and dry to obtain gold fluoropeptide acid-based molecular sieve.

[0128] In this embodiment, the purity of lithium bis(fluorosulfonyl)imide was calculated to be 87.96%, and the reaction yield was 92.55%.

[0129] Comparative Example 2

[0130] A method for preparing lithium bis(fluorosulfonyl)imide using sulfuryl fluoride, comprising the following steps:

[0131] S1: Weigh out sulfuryl fluoride, ammonia, organic base and solvent and react them in a reaction vessel to obtain the organic base salt of difluorosulfonyl imide;

[0132] S2: Evaporate the organic base salt of bis(fluorosulfonyl)imide, and recover and recycle the evaporated solvent and organic base;

[0133] S3: After extraction and evaporation of the organic base salt of bis(fluorosulfonyl)imide, an aqueous solution of lithium hydroxide is added, and the reaction is carried out for 1 hour to obtain crude bis(fluorosulfonyl)imide.

[0134] S4: Crude lithium difluorosulfonylimide was evaporated, then an ester solvent and a 10% lithium hydroxide aqueous solution were added, mixed and stirred, filtered, and then adsorbed through a 3% (by mass) fluoropeptide molecular sieve to obtain lithium difluorosulfonylimide.

[0135] The molar ratio of sulfuryl fluoride: ammonia: organic base: solvent is 1:1:1:30.

[0136] The organic base mentioned is triethylamine.

[0137] The solvent is a mixture of acetonitrile and propionitrile.

[0138] The reaction temperature of S1 is 5℃ and the reaction pressure is 0.2MPa.

[0139] In S3, the volume ratio of the organic base salt of bis(fluorosulfonyl)imide to lithium hydroxide is 1:1.

[0140] The evaporation temperature is 30°C.

[0141] The ester solvent mentioned is ethyl methyl carbonate.

[0142] The preparation method of the fluoropeptide-based molecular sieve is as follows:

[0143] S1: 0.1g H2PtCl6·6H2O and 100g isopropanol were added at once to a nitrogen-protected reactor and stirred at room temperature for 1 hour to obtain Speiers catalyst;

[0144] S2: 2g of 3,4,5,6-tetrafluoropeptide acid, 100g of allyl-modified MCM-41 mesoporous molecular sieve, 1000g of N,N-dimethylformamide, and 0.03g of Speiers catalyst were added to a stirred tank and stirred at 70℃ for 50min. Then, benzoyl peroxide was added and stirring was continued for 100min. The mixture was filtered, washed with deionized water until neutral, and dried to obtain gold fluoropeptide acid-based molecular sieve.

[0145] The preparation method of the allyl-modified MCM-41 mesoporous molecular sieve is as follows:

[0146] 2g of allyl dimethoxysilane, 2g of MCM-41 mesoporous molecular sieve, and 2g of deionized water were stirred at 70℃ for 50min, filtered, and dried to obtain allyl modified MCM-41 mesoporous molecular sieve.

[0147] In this embodiment, the purity of lithium bis(fluorosulfonyl)imide was calculated to be 90.13%, and the reaction yield was 93.37%.

[0148] Comparative Example 3

[0149] A method for preparing lithium bis(fluorosulfonyl)imide using sulfuryl fluoride, comprising the following steps:

[0150] S1: Weigh out sulfuryl fluoride, ammonia, organic base and solvent and react them in a reaction vessel to obtain the organic base salt of difluorosulfonyl imide;

[0151] S2: Evaporate the organic base salt of bis(fluorosulfonyl)imide, and recover and recycle the evaporated solvent and organic base;

[0152] S3: After extraction and evaporation of the organic base salt of bis(fluorosulfonyl)imide, an aqueous solution of lithium hydroxide is added, and the reaction is carried out for 1 hour to obtain crude bis(fluorosulfonyl)imide.

[0153] S4: Crude lithium difluorosulfonylimide was evaporated, then an ester solvent and a 10% lithium hydroxide aqueous solution were added, mixed and stirred, filtered, and then adsorbed through a 3% (by mass) fluoropeptide molecular sieve to obtain lithium difluorosulfonylimide.

[0154] The molar ratio of sulfuryl fluoride: ammonia: organic base: solvent is 1:1:1:30.

[0155] The organic base mentioned is triethylamine.

[0156] The solvent is a mixture of acetonitrile and propionitrile.

[0157] The reaction temperature of S1 is 5℃ and the reaction pressure is 0.2MPa.

[0158] In S3, the volume ratio of the organic base salt of bis(fluorosulfonyl)imide to lithium hydroxide is 1:1.

[0159] The evaporation temperature is 30°C.

[0160] The ester solvent mentioned is ethyl methyl carbonate.

[0161] The preparation method of the fluoropeptide-based molecular sieve is as follows:

[0162] S1: 0.1g H2PtCl6·6H2O and 100g isopropanol were added at once to a nitrogen-protected reactor and stirred at room temperature for 1 hour to obtain Speiers catalyst;

[0163] S2: Add 2g of 3,4,5,6-tetrafluoropeptide acid, 10g of 4-vinyl-1,2-phthalic acid, 100g of allyl-modified MCM-41 mesoporous molecular sieve, and 1000g of N,N-dimethylformamide to a stirred tank and stir at 70℃ for 50min. Then add benzoyl peroxide and continue stirring for 100min. Filter, wash with deionized water until neutral, and dry to obtain gold fluoropeptide acid-based molecular sieve.

[0164] The preparation method of the allyl-modified MCM-41 mesoporous molecular sieve is as follows:

[0165] 2g of allyl dimethoxysilane, 2g of MCM-41 mesoporous molecular sieve, and 2g of deionized water were stirred at 70℃ for 50min, filtered, and dried to obtain allyl modified MCM-41 mesoporous molecular sieve.

[0166] In this embodiment, the purity of lithium bis(fluorosulfonyl)imide was calculated to be 92.52%, and the reaction yield was 93.32%.

[0167] By comparing the above examples with comparative data, the present invention, through distillation and extraction for preliminary purification, followed by filtration and passing through a fluoropeptide molecular sieve, further removes trace metal impurities from the crude product, thereby obtaining high-purity lithium difluorosulfonylimide with low metal ion residue.

[0168] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1.A method for preparing lithium bisfluorosulfonimide by using sulfonyl fluoride, comprising the following steps: S1: weighing sulfonyl fluoride, ammonia, organic base and solvent in a reactor by weight parts, and reacting to obtain an organic base salt of bisfluorosulfonimide; S2: evaporating the organic base salt of bisfluorosulfonimide, and recycling the evaporated solvent and organic base; S3: adding lithium hydroxide aqueous solution to the organic base salt of bisfluorosulfonimide after extraction and evaporation, and reacting for 1-3 hours to obtain a crude lithium bisfluorosulfonimide; S4: adding an ester solvent and a lithium hydroxide aqueous solution with a mass concentration of 10-20% to the crude lithium bisfluorosulfonimide after evaporation, mixing and stirring, filtering, and adsorbing by a fluoropeptide acid-based molecular sieve with a mass percentage of 3-8% of the crude lithium bisfluorosulfonimide to obtain lithium bisfluorosulfonimide; and the preparation method of the fluoropeptide acid-based molecular sieve is as follows: S1: adding 0.1-1 parts of H2PtCl6.6H2O and 100-500 parts of isopropyl alcohol into a reactor under nitrogen protection, and stirring at room temperature for 1-5 hours to obtain a Speiers catalyst; S2: adding 2-5 parts of 3,4,5,6-tetrafluoropeptide acid, 10-15 parts of 4-vinyl-1,2-benzenedicarboxylic acid, 100-200 parts of allyl-modified MCM-41 mesoporous molecular sieve, 1000-1500 parts of N,N-dimethylformamide, and 0.03-0.6 parts of the Speiers catalyst into a stirring kettle, stirring at 70-80℃ for 50-100 minutes, then adding benzoyl peroxide, continuing to stir for 100-140 minutes, filtering, washing with deionized water until neutral, and drying to obtain a fluoropeptide acid-based molecular sieve; and the preparation method of the allyl-modified MCM-41 mesoporous molecular sieve is as follows: adding 2-5 parts of allyldimethoxysilane, 2-5 parts of MCM-41 mesoporous molecular sieve, and 2-5 parts of deionized water into a stirring kettle, stirring at 70-80℃ for 50-100 minutes, filtering, and drying to obtain the allyl-modified MCM-41 mesoporous molecular sieve; the molar ratio of the sulfonyl fluoride, ammonia, organic base and solvent is (1-3) : 1: (1-5) : (30-50); the organic base is one or more of triethylamine, triethylenediamine, 1,8-diazabicycloundec-7-ene, 1,5-diazabicyclo[4.3.0]-5-nonene, 4-dimethylaminopyridine, pyridine, N-methylmorpholine and tetramethylethylenediamine; the solvent is a mixture of any two or more of acetonitrile, propionitrile, isopropionitrile, diethyl ether, propyl ether, isopropyl ether, tetrahydrofuran, acetone, butanone, methyl isobutyl ketone and methyl pyrrolidone, and acetonitrile must be included; the reaction temperature of S1 is 5-25℃, and the reaction pressure is 0.2-0.3 MPa; the volume ratio of the organic base salt of bisfluorosulfonimide to lithium hydroxide in S3 is 1: (1-1.2); the evaporation temperature is 30-50℃; and the ester solvent is at least one of methyl ethyl carbonate, dimethyl carbonate and diethyl carbonate. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The method for preparing lithium bisfluorosulfonylimide using sulfonyl fluoride according to claim 1, characterized by: ​ 3. The method for preparing lithium bisfluorosulfonylimide using sulfonyl fluoride according to claim 1, characterized by: ​ 4. The method of claim 1, wherein the method is characterized by: ​ 5. The method of claim 1, wherein the method is characterized by: ​ 6. The method of claim 1, wherein the method is characterized by: ​ 7. The method of claim 1, wherein the method is characterized by: ​ 8. The method of claim 1, wherein the method is characterized by: ​