Method for purifying a dihalogenosulfimide acid and use thereof

Abstract

The present application relates to the technical field of lithium ion battery, in particular to a purification method of dihalogen sulfimide acid and application thereof. The purification method of dihalogen sulfimide acid comprises the following steps: adding a medium-polarity solvent to crude dihalogen sulfimide acid for purification to obtain a mixture containing purified dihalogen sulfimide acid; adding a low-polarity solvent to the mixture containing purified dihalogen sulfimide acid and standing for crystallization at ≤5 ℃, and then separating solid and liquid after crystallization to obtain purified dihalogen sulfimide acid; wherein the polarity index of the medium-polarity solvent is 2-6, and the polarity index of the low-polarity solvent is ≤1. The method can improve the purity and yield of dihalogen sulfimide acid simultaneously.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a purification method for dihalosulfonylimide acid and its application, and more specifically to a purification method for dihalosulfonylimide acid, a preparation method for lithium bisfluorosulfonylimide, an electrolyte, and a lithium-ion battery. Background Technology

[0002] Dihalo(chloro / fluorinated) sulfonyl imides are important chemical intermediates used in the preparation of Lewis acid catalysts, ion transporters, organic compound synthesis, and electrolytes. Particularly in the field of lithium-ion battery electrolyte salt synthesis, with the increasing application of lithium bisfluorosulfonylimide (LIFSI) as an electrolyte lithium salt in electrolytes, the preparation of high-purity LIFSI has become a research hotspot. Among current LIFSI synthesis routes, the process of preparing dichlorosulfonylimide followed by fluorination and lithiation to produce LIFSI is the most suitable for industrial production. To improve the purity of LIFSI, the important intermediate, dichloro / fluorosulfonyl imide, needs to be purified.

[0003] For example, existing literature uses distillation to purify dichlorosulfonyl imide acid, but this purification method is time-consuming and energy-intensive, making it unsuitable for industrial production. Another existing method involves heating the reaction mixture to a viscous consistency and turning it light brown, then fractionating the reaction mixture under vacuum, collecting the main fraction within the range of 95–110 °C / 650 Pa. However, this process results in a narrow collection temperature range and is highly susceptible to contamination with highly volatile chlorosulfonic acid, making it difficult to achieve high purity.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The primary objective of this invention is to provide a purification method for dihalosulfonylimines, which uses a moderately polar solvent to extract unreacted raw materials and a low-polarity solvent to promote crystallization of the target product at low temperatures. This method significantly improves the purification efficiency of dihalosulfonylimines, is simple and easy to implement, and yields dihalosulfonylimines with high purity.

[0006] The second objective of this invention is to provide a method for preparing lithium bisfluorosulfonylimide, wherein the purity of the prepared lithium bisfluorosulfonylimide can be improved by purifying the dihalosulfonylimide acid.

[0007] The third objective of this invention is to provide an electrolyte prepared using high-purity lithium bis(fluorosulfonyl)imide, which is beneficial for improving the electrochemical performance of lithium-ion batteries made from it.

[0008] A fourth objective of this invention is to provide a lithium-ion battery with excellent electrochemical performance.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0010] This invention provides a method for purifying dihalosulfonylimine acids, comprising the following steps:

[0011] The crude dihalosulfonylimide acid was purified by adding a moderately polar solvent to obtain a mixture containing the purified dihalosulfonylimide acid.

[0012] A low-polarity solvent was added to the mixture containing the purified dihalosulfonylimide acid and allowed to stand at ≤5°C to crystallize. After the crystallization was completed, solid-liquid separation was performed to obtain the purified dihalosulfonylimide acid.

[0013] The polarity index of the moderately polar solvent is 2 to 6.

[0014] The polarity index of the low-polarity solvent is ≤1.

[0015] This invention purifies dihalosulfonylimine by using a combination of solvents with different polarities, achieving both impurity removal and crystallization of the target product, thus improving the purification efficiency and significantly enhancing the product purity.

[0016] The present invention also provides a method for preparing lithium bis(fluorosulfonyl)imide, including the purification method of the aforementioned bis(halosulfonyl)imide acid.

[0017] This method can significantly improve the purity of lithium bis(fluorosulfonyl)imide.

[0018] The present invention also provides an electrolyte comprising lithium bisfluorosulfonylimide prepared by the method described above.

[0019] This electrolyte uses high-purity lithium bisfluorosulfonylimide with low impurity content, which can improve the electrochemical performance of lithium-ion batteries made from it.

[0020] The present invention also provides a lithium-ion battery comprising the electrolyte described above.

[0021] This lithium-ion battery exhibits excellent electrochemical performance.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) The purification method of dihalosulfonylimide acid provided by the present invention purifies dihalosulfonylimide acid by using a combination of solvents with different polarities, thereby achieving the dual effects of impurity removal and crystallization of the target product, improving the purification efficiency of the dihalosulfonylimide acid, and significantly improving the purity of the dihalosulfonylimide acid.

[0024] (2) The purification method of dihalosulfonylimine provided by the present invention, compared with the existing narrow distillation temperature of 110-115℃, allows crystallization at ≤5℃, which has a wider temperature range and lower temperature, thus requiring less operation. It can also significantly reduce the problems of product volatilization and mixed by-products, improve the product recovery rate, and is suitable for large-scale production. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is the LC-MS spectrum of the dihalosulfonylimine obtained in Example 1 of the present invention. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0028] In a first aspect, the present invention provides a method for purifying dihalosulfonylimine acids, comprising the following steps:

[0029] A moderately polar solvent was added to the crude dihalosulfonylimide acid (i.e., the dihalosulfonylimide acid to be purified) for purification to obtain a mixture containing the purified dihalosulfonylimide acid.

[0030] A low-polarity solvent is added to the mixture containing purified dihalosulfonylimide acid to obtain a mixture. The mixture is then allowed to stand at ≤5°C to precipitate crystals (referred to as crystallization). After the crystallization is complete, the solid and liquid are separated to obtain the purified dihalosulfonylimide acid.

[0031] Among them, the polarity index of the medium polarity solvent is 2 to 6, including but not limited to the point value of any one of 2, 2.4, 2.9, 3.0, 3.4, 3.6, 4.0, 4.4, 5.0, and 6.0 or the range between any two.

[0032] The polarity index of low polarity solvents is ≤1; including but not limited to point values ​​of any one of 1.0, 0.5, 0.2, 0.1, 0.06, 0.01 or range values ​​between any two.

[0033] To address the problems of difficult product separation and high energy consumption in the distillation purification process of dihalosulfonylimides in existing technologies, this invention first uses a moderately polar solvent to extract (i.e. purify) the unreacted raw material, and then uses a low-polarity solvent to promote the crystallization of the target product at low temperature. This method can significantly improve the purity of dihalosulfonylimides, and it is simple, easy to implement, and has high purification efficiency.

[0034] Furthermore, in response to the problems of long distillation time, high industrial energy consumption, easy coking of products, and difficulty in achieving high purity of target products in the existing technology of product extraction using short-path distillation, the purification method provided by this method is carried out at a lower temperature, which can significantly reduce product volatilization and the problem of mixed by-products, and improve the product recovery rate to a certain extent. It is more suitable for mass production and has broad application prospects.

[0035] In some specific embodiments, the above solid-liquid separation includes any conventional method, such as pressure filtration, vacuum filtration, centrifugation, etc., but is not limited to these.

[0036] In some specific embodiments, the solid-liquid separation is followed by a drying step.

[0037] In some specific embodiments, the moderately polar solvent includes at least one of isobutanol, acetone, pyridine, p-xylene, ethyl acetate, chloroform, diethyl ether, and toluene.

[0038] Among them, medium-polarity solvents can dissolve unreacted raw materials, purify the target product, and thus improve the purity of the product.

[0039] In some specific embodiments, the low-polarity solvent includes at least one of hexane, cyclohexane, petroleum ether, pentane, trimethylpentane, butyl chloride, cyclopentane, heptane, and carbon disulfide.

[0040] In some specific embodiments, pentane includes at least one of n-pentane and isopentane.

[0041] By adding a low-polarity solvent, the target product can be rapidly crystallized at low temperatures, significantly improving the recovery rate.

[0042] Furthermore, the combination of medium-polarity and low-polarity solvents allows for rapid separation of the target product and solvent through solid-liquid separation.

[0043] In some specific embodiments, the molar ratio of dihalosulfonylimide acid to a moderately polar solvent is 1:0.1 to 1; including but not limited to point values ​​or ranges between any one of 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, and 1:1.

[0044] Using the above-mentioned molar ratio range is beneficial for the complete dissolution and purification of dihalosulfonyl imide acids and ensures the yield.

[0045] In some specific embodiments, the molar ratio of dihalosulfonylimide acid and low-polarity solvent is 1:0.8 to 4, including but not limited to any one of 1:0.8, 1:0.9, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4 or any range between the two.

[0046] Using the above-mentioned ratio of dihalosulfonylimide acid and low-polarity solvent is beneficial for the full and rapid precipitation and crystallization of dihalosulfonylimide acid.

[0047] In some specific implementations, the temperature for static crystallization is -30 to 5°C; including but not limited to any one of -30°C, -25°C, -20°C, -15°C, -10°C, -5°C, -1°C, 0°C, 3°C, and 5°C, or any range between two of them.

[0048] Setting the crystallization temperature within the range of -30 to 5℃ is beneficial for separating the purified dihalosulfonylimine product.

[0049] Preferably, the temperature for static crystallization is -30 to -1°C.

[0050] In some specific implementations, the settling time for crystallization is 24 to 48 hours, including but not limited to any one of 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, 38 hours, 40 hours, 44 hours, and 48 hours, or any range between two of them.

[0051] Using the above-mentioned crystallization time can ensure complete crystal precipitation, thereby improving product yield.

[0052] In some specific embodiments, during the process of adding a moderately polar solvent to the crude dihalosulfonylimide acid, the temperature of the mixing system is 30 to 60°C, including but not limited to any one of 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, and 60°C, or any range between two of them.

[0053] In some specific embodiments, the crude dihalosulfonylimide acid is mixed with the moderately polar solvent for 3 to 12 hours, including but not limited to the point value of any one of 3 hours, 5 hours, 7 hours, 9 hours, 10 hours, and 12 hours or the range between any two.

[0054] First, the dihalosulfonyl imide acid is mixed with a moderately polar solvent to dissolve unreacted raw materials, thus purifying the target product. Then, a low-polarity solvent is added, and the mixture is allowed to stand at a low temperature, allowing the target product to crystallize rapidly at that temperature. Simultaneously, the miscibility of the moderately and low-polarity solvents allows for rapid separation of the target product from the solvent via solid-liquid separation. The purification method provided by this invention offers high purification efficiency and high yield.

[0055] In some specific implementations, the crystallization is carried out under an inert atmosphere, which helps to protect the dihalosulfonyl imide acid.

[0056] In some specific implementations, the inert atmosphere includes a nitrogen atmosphere and / or an argon atmosphere.

[0057] In some specific implementations, the purity of the purified dihalosulfonylimine is ≥99%; including but not limited to point values ​​of any one of 99.0%, 99.1%, 99.2%, 99.3%, 99.5%, 99.6%, 99.7%, 99.8%, and 99.9%, or range values ​​between any two.

[0058] The dihalosulfonyl imide acid prepared by the purification method provided in this invention has higher purity, which is beneficial for its application in lithium-ion batteries.

[0059] In some specific embodiments, the HSO3 in the purified dihalosulfonyl imide acid - The content is ≤50ppm; including but not limited to point values ​​of any one of 45ppm, 40ppm, 35ppm, 30ppm, 25ppm, 20ppm, 15ppm, and 10ppm, or a range between any two.

[0060] In some specific implementations, the Cl in the purified dihalosulfonyl imide acid -The content is ≤50ppm, including but not limited to point values ​​of any one of 45ppm, 40ppm, 35ppm, 30ppm, 25ppm, 20ppm, 15ppm, and 10ppm, or a range between any two.

[0061] The dihalosulfonyl imide acid prepared by this invention has a low impurity content, which can avoid the influence of impurities on the electrochemical performance of lithium-ion batteries.

[0062] In some specific embodiments, the dihalosulfonyl imide acid includes at least one of dichlorosulfonyl imide acid and difluorosulfonyl imide acid.

[0063] The method provided by this invention can purify both dichlorosulfonylimide acid and difluorosulfonylimide acid. This method can be introduced into the production of lithium difluorosulfonylimide and has broad application prospects.

[0064] Among them, difluorosulfonylimide acid and dichlorosulfonylimide acid include any commercially available low-purity difluorosulfonylimide acid and dichlorosulfonylimide acid, or difluorosulfonylimide acid and dichlorosulfonylimide acid prepared by any method.

[0065] In some specific embodiments, difluorosulfonylimide acid is mainly prepared by reacting dichlorosulfonylimide acid and a fluorine source under the action of a catalyst.

[0066] In the process of preparing difluorosulfonylimide acid, the catalyst includes any conventional catalyst, such as antimony pentachloride, but is not limited to it.

[0067] In the preparation of bis(fluorosulfonyl)imide acid, the fluorine source used includes hydrogen fluoride and / or hydrofluoric acid.

[0068] In some specific embodiments, dichlorosulfonylimine is mainly prepared from chlorosulfonic acid, aminosulfonic acid and thionyl chloride.

[0069] In some specific embodiments, dichlorosulfonylimine is mainly prepared by reacting chlorosulfonic acid and chlorosulfonyl isocyanate under the action of a catalyst.

[0070] In the preparation of dichlorosulfonylimine, the catalyst includes nickel chloride.

[0071] Secondly, the present invention provides a method for preparing lithium bisfluorosulfonylimide, including a method for purifying dihalosulfonylimide acid.

[0072] Purifying dihalosulfonyl imide acid can improve the purity of the prepared lithium bisfluorosulfonyl imide, which is beneficial for its application in lithium-ion battery electrolyte salts.

[0073] Thirdly, the present invention provides an electrolyte comprising lithium bisfluorosulfonylimide prepared by a method thereof.

[0074] In some specific implementations, lithium bis(fluorosulfonyl)imide in the electrolyte is used as a solute.

[0075] Using high-purity lithium bisfluorosulfonylimide to prepare the electrolyte is beneficial to improving the electrochemical performance of the lithium-ion battery made from it.

[0076] In some specific embodiments, the electrolyte also includes solvents and additives. The solvents include any conventional solvents, such as propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, etc., but are not limited to these. The additives include any conventional substances with specific functions, such as film-forming additives, high-temperature additives, low-temperature additives, overcharge protection additives, flame-retardant additives, rate-dependent additives, etc., but are not limited to these.

[0077] Fourthly, the present invention provides a lithium-ion battery, including an electrolyte.

[0078] In some specific implementations, the lithium-ion battery also includes a positive electrode, a negative electrode, and a separator.

[0079] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0080] Example 1

[0081] The preparation method of dichlorosulfonyl imide acid provided in this embodiment includes the following steps:

[0082] Under a nitrogen atmosphere, 1456 g of aminosulfonic acid, 3569 g of thionyl chloride, and 1748 g of chlorosulfonic acid were sequentially added to a three-necked flask. The mixture was refluxed and reacted at 125 °C for 14 h to obtain 3085 g of brownish-yellow liquid, which was the crude dichlorosulfonylimide acid, with a yield of 96.1%.

[0083] Example 2

[0084] The purification method for dichlorosulfonylimine provided in this embodiment includes the following steps:

[0085] Under a nitrogen atmosphere, 40.6 g of acetone (the molar ratio of dichlorosulfonylimide acid to acetone was 1:0.5) was added to 300 g of crude dichlorosulfonylimide acid prepared in Example 1, and then the mixture was stirred at 30 °C for 3 h to obtain a mixture containing purified dihalosulfonylimide acid.

[0086] 112.2 g of heptane (the molar ratio of dichlorosulfonylimide to heptane is 1:0.8) was added to the above mixture containing purified dichlorosulfonylimide. After stirring evenly, the mixture was allowed to stand at 5°C for 24 h. After standing, the mixture was filtered under reduced pressure to obtain 297 g of colorless crystals, which is the purified dichlorosulfonylimide.

[0087] Example 3

[0088] The preparation method of dichlorosulfonyl imide acid provided in this embodiment includes the following steps:

[0089] Under an Ar atmosphere, 1165 g of chlorosulfonic acid and 5 g of anhydrous nickel chloride were added to a three-necked flask. After stirring for 15 min, 1415 g of chlorosulfonyl isocyanate was added dropwise to the three-necked flask over 1 h. The mixture was refluxed and reacted at 135 °C for 12 h to obtain 1958 g of brownish-yellow liquid, which was the crude dichlorosulfonyl imide acid, with a yield of 91.5%.

[0090] Example 4

[0091] The purification method for dichlorosulfonylimine provided in this embodiment includes the following steps:

[0092] Under an Ar atmosphere, 59.4 g of dichloromethane (the molar ratio of dichlorosulfonamide acid to dichloromethane was 1:0.5) was added to 300 g of crude dichlorosulfonamide acid obtained in Example 3, and then the mixture was stirred at 30 °C for 3 h to obtain a mixture containing purified dihalosulfonamide acid.

[0093] 112.2 g of heptane (the molar ratio of dichlorosulfonylimide to heptane is 1:0.8) was added to the above mixture containing purified dichlorosulfonylimide. After stirring evenly, the mixture was allowed to stand at 5°C for 24 h. After standing, the mixture was filtered under reduced pressure to obtain 295.5 g of colorless crystals, which is the purified dichlorosulfonylimide.

[0094] Example 5

[0095] The preparation method of bis(fluorosulfonyl)imide acid provided in this embodiment includes the following steps:

[0096] 2140g of purified dichlorosulfonylimide acid prepared in Example 2 and 2.5g of antimony pentachloride were added to a tetrafluoromethane reaction flask. The temperature was raised to 105°C, and 600g of HF gas was slowly introduced under stirring. After reacting for 24h, the temperature was lowered to room temperature, and nitrogen gas was blown for 36h to obtain 1548g of crude dichlorosulfonylimide acid.

[0097] Example 6

[0098] The purification method for difluorosulfonylimine provided in this embodiment includes the following steps:

[0099] Under a nitrogen atmosphere, 70.5 g of dichloromethane (the molar ratio of difluorosulfonylimide to dichloromethane was 1:0.5) was added to 300 g of crude difluorosulfonylimide obtained in Example 5, and then the mixture was stirred at 30 °C for 6 h to obtain a mixture containing purified dihalosulfonylimide.

[0100] Add 371.2g of petroleum ether (molar ratio of difluorosulfonyl imide to petroleum ether is 1:2) to the above mixture containing purified difluorosulfonyl imide. After stirring evenly, let it stand at -10℃ for 24h. After standing, filter under reduced pressure to obtain 295.2g of colorless crystals, which is the purified difluorosulfonyl imide.

[0101] Example 7

[0102] Under an Ar atmosphere, 167.2 g of chloroform (the molar ratio of dichlorosulfonamide acid to chloroform was 1:1) was added to 300 g of crude dichlorosulfonamide acid prepared in Example 1, and then the mixture was stirred at 50 °C for 12 h to obtain a mixture containing purified dihalosulfonamide acid.

[0103] Add 482.7g of cyclohexane (the molar ratio of dichlorosulfonylimide to cyclohexane is 1:4) to the above mixture containing purified dichlorosulfonylimide. After stirring evenly, let it stand at -5℃ for 36h. After standing, filter under reduced pressure to obtain 294.6g of colorless crystals, which is the purified dichlorosulfonylimide.

[0104] Example 8

[0105] The purification method for dichlorosulfonylimine provided in this embodiment includes the following steps:

[0106] Under an Ar atmosphere, 257.8 g of toluene (the molar ratio of dichlorosulfonylimide acid to toluene was 1:1) was added to 600 g of crude dichlorosulfonylimide acid prepared in Example 1, and then the mixture was stirred at 60 °C for 12 h to obtain a mixture containing purified dihalosulfonylimide acid.

[0107] Add 426.2g of carbon disulfide (the molar ratio of dichlorosulfonimide to carbon disulfide is 1:2) to the above mixture containing purified dichlorosulfonimide. After stirring evenly, let it stand at -10℃ for 48h. After standing, filter under reduced pressure to obtain 592.2g of colorless crystals, which is the purified dichlorosulfonimide.

[0108] Example 9

[0109] The purification method for dichlorosulfonylimine provided in this embodiment includes the following steps:

[0110] Under a nitrogen atmosphere, 103.7 g of diethyl ether (the molar ratio of dichlorosulfonimide to diethyl ether is 1:0.5) was added to 600 g of crude dichlorosulfonimide obtained in Example 1, and then the mixture was stirred at 60 °C for 6 h to obtain a mixture containing purified dihalosulfonimide.

[0111] Add 403.7g of n-pentane (the molar ratio of dichlorosulfonylimide to n-pentane is 1:2) to the above mixture containing purified dichlorosulfonylimide. After stirring evenly, let it stand at -20℃ for 36h. After standing, filter under reduced pressure to obtain 594g of colorless crystals, which is the purified dichlorosulfonylimide.

[0112] Example 10

[0113] The purification method for dichlorosulfonylimine provided in this embodiment includes the following steps:

[0114] Under a nitrogen atmosphere, 25.9 g of toluene (the molar ratio of dichlorosulfonimide acid to toluene was 1:0.2) was added to 300 g of crude dichlorosulfonimide acid prepared in Example 3, and then the mixture was stirred at 30 °C for 3 h to obtain a mixture containing purified dihalosulfonimide acid.

[0115] Add 561.1g of heptane (the molar ratio of dichlorosulfonylimide to heptane is 1:4) to the above mixture containing purified dichlorosulfonylimide. After stirring evenly, let it stand at -30℃ for 36h. After standing, filter under reduced pressure to obtain 293.1g of colorless crystals, which is the purified dichlorosulfonylimide.

[0116] Example 11

[0117] The purification method for dichlorosulfonylimine provided in this embodiment includes the following steps:

[0118] Under a nitrogen atmosphere, 118.9 g of dichloromethane (the molar ratio of dichloromethane to dichloromethane was 1:1) was added to 300 g of crude dichlorosulfonimide acid prepared in Example 3, and then the mixture was stirred at 40 °C for 6 h to obtain a mixture containing purified dihalosulfonimide acid.

[0119] Add 213g of carbon disulfide (the molar ratio of dichlorosulfonimide to carbon disulfide is 1:2) to the above mixture containing purified dichlorosulfonimide. After stirring evenly, let it stand at -20℃ for 48h. After standing, filter under reduced pressure to obtain 292.8g of colorless crystals, which is the purified dichlorosulfonimide.

[0120] Example 12

[0121] The purification method for dichlorosulfonylimine provided in this embodiment includes the following steps:

[0122] Under an Ar atmosphere, 123.2 g of ethyl acetate (the molar ratio of dichlorosulfonylimide to ethyl acetate was 1:1) was added to 300 g of crude dichlorosulfonylimide obtained in Example 3, and then the mixture was stirred at 60 °C for 3 h to obtain a mixture containing purified dihalosulfonylimide.

[0123] Add 80.8g of isopentane (the molar ratio of dichlorosulfonylimide to isopentane is 1:0.8) to the above mixture containing purified dichlorosulfonylimide. After stirring evenly, let it stand at -30℃ for 48h. After standing, filter under reduced pressure to obtain 291g of colorless crystals, which is the purified dichlorosulfonylimide.

[0124] Example 13

[0125] The purification method for dichlorosulfonylimine provided in this embodiment includes the following steps:

[0126] Under an Ar atmosphere, 167.2 g of chloroform (the molar ratio of dichlorosulfonamide acid to chloroform was 1:0.5) was added to 600 g of crude dichlorosulfonamide acid obtained in Example 3, and then the mixture was stirred at 60 °C for 12 h to obtain a mixture containing purified dihalosulfonamide acid.

[0127] 1254.4g of petroleum ether (molar ratio of dichlorosulfonimide to petroleum ether is 1:4) was added to the above mixture containing purified dichlorosulfonimide. After stirring evenly, the mixture was allowed to stand at -30℃ for 24h. After standing, the mixture was filtered under reduced pressure to obtain 581.4g of colorless crystals, which is the purified dichlorosulfonimide.

[0128] Example 14

[0129] The purification method for difluorosulfonylimine provided in this embodiment includes the following steps:

[0130] Under an Ar atmosphere, 246g of diethyl ether (the molar ratio of difluorosulfonyl imide to diethyl ether is 1:1) was added to 600g of crude difluorosulfonyl imide obtained in Example 5, and then the mixture was stirred at 40°C for 12h to obtain a mixture containing purified dihalosulfonyl imide.

[0131] 1133.8g of n-hexane (the molar ratio of difluorosulfonylimide to n-hexane is 1:4) was added to the above mixture containing purified difluorosulfonylimide. After stirring evenly, the mixture was allowed to stand at -15℃ for 28h. After standing, the mixture was filtered under reduced pressure to obtain 591g of colorless crystals, which is the purified difluorosulfonylimide.

[0132] Example 15

[0133] The purification method for difluorosulfonylimine provided in this embodiment includes the following steps:

[0134] Under an Ar atmosphere, 61g of toluene (the molar ratio of bis(fluorosulfonyl)imide acid to toluene was added to 600g of crude bis(fluorosulfonyl)imide acid prepared in Example 5, and then stirred at 50°C for 8h to obtain a mixture containing purified bis(halosulfonyl)imide acid.

[0135] Add 478.7g of cyclopentane (molar ratio of difluorosulfonylimide to cyclopentane is 1:2) to the above mixture containing purified difluorosulfonylimide. After stirring evenly, let it stand at -25℃ for 32h. After standing, filter under reduced pressure to obtain 583.8g of colorless crystals, which is the purified difluorosulfonylimide.

[0136] Comparative Example 1

[0137] The purification method for dichlorosulfonylimine provided in this comparative example includes the following steps:

[0138] 310.7 g of crude dichlorosulfonimide acid obtained in Example 1 was subjected to vacuum distillation at a pressure of -0.05 to -0.07 MPa. The fraction collected at 110 to 115 °C yielded 277.1 g of brownish-yellow liquid, with a yield of 89.2%.

[0139] Comparative Example 2

[0140] The purification method for dichlorosulfonylimine provided in this comparative example includes the following steps:

[0141] 1945g of crude dichlorosulfonimide acid obtained in Example 3 was subjected to vacuum distillation at a pressure of -0.05 to -0.07 MPa. The fraction collected at 110 to 115°C yielded 1598.8g of liquid dichlorosulfonimide acid, with a yield of 82.2%.

[0142] Comparative Example 3

[0143] The purification method of dichlorosulfonylimine provided in this comparative example is basically the same as that in Example 12, except that isopentane was not added.

[0144] This comparative example yielded 20.2g of colorless crystals.

[0145] Comparative Example 4

[0146] The purification method of dichlorosulfonylimine provided in this comparative example is basically the same as that in Example 7, except that chloroform was not added.

[0147] This comparative example yielded 299.2g of colorless crystals.

[0148] Comparative Example 5

[0149] The purification method for difluorosulfonylimine provided in this comparative example includes the following steps:

[0150] 300g of crude difluorosulfonyl imide acid obtained in Example 5 was subjected to vacuum distillation to remove the fraction at 110-115℃. The liquid in the flask after distillation was collected, yielding 259.8g of liquid.

[0151] Comparative Example 6

[0152] The purification method for difluorosulfonylimine provided in this comparative example includes the following steps:

[0153] Under a nitrogen atmosphere, 600g of crude difluorosulfonylimide acid obtained in Example 5 and 123g of diethyl ether were added to a three-necked flask (i.e., the molar ratio of difluorosulfonylimide acid to diethyl ether was 1:0.5). The mixture was stirred at 50°C for 24 hours. After stirring, it was allowed to stand at -30°C for 36 hours. After standing, it was filtered under reduced pressure to obtain 134.4g of colorless crystals, which was the purified difluorosulfonylimide acid.

[0154] Comparative Example 7

[0155] The purification method for difluorosulfonylimine provided in this comparative example includes the following steps:

[0156] Under a nitrogen atmosphere, 600g of crude difluorosulfonamide acid obtained in Example 5 and 478.8g of pentane were added to a three-necked flask and stirred at 30°C for 24 hours. After stirring, the mixture was allowed to stand at -30°C for 48 hours. After standing, the mixture was filtered under reduced pressure to obtain 586.8g of colorless crystals, which is the purified difluorosulfonamide acid.

[0157] Comparative Example 8

[0158] The purification method of difluorosulfonylimine provided in this comparative example is basically the same as that in Example 14, except that the diethyl ether is replaced with an equimolar amount of water.

[0159] In this comparative example, 12.4 g of colorless crystals were obtained.

[0160] Comparative Example 9

[0161] The purification method of bis(fluorosulfonyl)imide acid provided in this comparative example is basically the same as that in Example 15, except that cyclopentane is replaced with an equimolar amount of methanol.

[0162] This comparative example yielded 612.4 g of colorless crystals.

[0163] Comparative Example 10

[0164] The purification method of difluorosulfonylimine provided in this comparative example is basically the same as that in Example 15, except that the temperature for static crystallization is replaced with 15°C.

[0165] This comparative example yielded 0g of colorless crystals.

[0166] Experimental Example

[0167] The recovery rate, purity, and HSO3 content of the dihalosulfonylimide acids obtained from the purification methods of the above embodiments and comparative examples are described. - Content and Cl - The content is shown in Table 1 below.

[0168] Among them, HSO3 - The content was determined using a UV spectrophotometer; Cl - The content was determined according to the method specified in GB / T 13025.5-2012.

[0169] Table 1. Recovery rate, purity, and HSO3 content of each group. - Content and Cl - Content results

[0170]

[0171]

[0172] As shown in Table 1, the purification methods used in each embodiment have higher yields, and the resulting dihalosulfonyl imide acids have higher purity and lower impurity content.

[0173] Comparative Examples 1, 2, and 5 were purified using traditional vacuum distillation, with fractions at 110–115°C, a narrow temperature range, and high purification requirements. In contrast, Examples 2, 4, 6, 8, 10, 12, and 14 of this application were purified at a temperature range of -30°C to 5°C, a wider temperature range, lower temperatures, and lower purification requirements. However, the purity of the resulting dihalosulfonylimine was reduced, the impurity content was high, and the yield was significantly lower.

[0174] In Comparative Examples 4 and 7, although the recovery rates were high, some polar raw materials, such as chlorosulfonic acid, aminosulfonic acid, and dichlorosulfonimide, could not be removed by filtration without being dissolved in the polar solvent, resulting in a significant reduction in the purity of the final product.

[0175] In Comparative Examples 3 and 6, the lack of a low-polarity solvent resulted in the target product failing to form stable crystals in a short time, significantly reducing the recovery efficiency.

[0176] In Comparative Example 8, the difluorosulfonamide acid and water underwent a hydrolysis reaction, resulting in the failure to obtain the target product.

[0177] In Comparative Example 9, methanol is highly polar and has good solubility in both raw materials and target products, making it impossible to separate the product from the impurities.

[0178] In Comparative Example 10, the product did not crystallize at a higher temperature due to being left to stand, thus failing to achieve the separation effect and therefore could not be purified.

[0179] In addition, such as Figure 1 The LC-MS spectrum of the dihalosulfonylimide acid prepared in Example 1 of the present invention is shown. As can be seen from the spectrum, the main absorption peak is the target product peak, and there are no other impurity peaks.

[0180] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for purifying dihalosulfonylimine acids, characterized in that, Includes the following steps: The crude dihalosulfonylimide acid was purified by adding a moderately polar solvent to obtain a mixture containing the purified dihalosulfonylimide acid. A low-polarity solvent was added to the mixture containing the purified dihalosulfonylimide acid and allowed to stand at -30~5°C to crystallize. After the crystallization was completed, solid-liquid separation was performed to obtain the purified dihalosulfonylimide acid. The moderately polar solvent includes at least one of dichloromethane, isobutanol, acetone, pyridine, p-xylene, ethyl acetate, chloroform, diethyl ether, and toluene. The low-polarity solvent includes at least one of hexane, cyclohexane, petroleum ether, pentane, trimethylpentane, butyl chloride, cyclopentane, heptane, and carbon disulfide; The molar ratio of the dihalosulfonylimide acid to the moderately polar solvent is 1:0.1~1; The molar ratio of the dihalosulfonylimide acid to the low-polarity solvent is 1:0.8~4; During the process of adding a moderately polar solvent to the crude dihalosulfonylimide acid, the temperature of the mixing system is 30~60℃; The purity of the purified dihalosulfonyl imide acid is ≥99%; HSO3 content in the purified dihalosulfimide acid is ≤ 50 ppm - ; The content of Cl in the purified dihalogen sulfimide acid is ≤ 50 ppm. - The content of Cl in the purified dihalogen sulfimide acid is ≤ 50 ppm.

2. The purification method for dihalosulfonylimine according to claim 1, characterized in that, The time for static crystallization is 24~48h.

3. The purification method for dihalosulfonylimine according to claim 1, characterized in that, The crude dihalosulfonylimide acid is mixed with the moderately polar solvent for 3 to 12 hours.

4. The purification method for dihalosulfonylimine according to claim 1, characterized in that, The dihalosulfonyl imide acid includes at least one of dichlorosulfonyl imide acid and difluorosulfonyl imide acid.

5. The purification method for dihalosulfonylimine according to claim 4, characterized in that, It includes at least one of the following features (1) to (3): (1) The difluorosulfonyl imide acid is mainly prepared by reacting dichlorosulfonyl imide acid and a fluorine source under the action of a catalyst; (2) The dichlorosulfonylimine is mainly prepared from chlorosulfonic acid, aminosulfonic acid and thionyl chloride; (3) The dichlorosulfonyl imide acid is mainly prepared by reacting chlorosulfonic acid and chlorosulfonyl isocyanate under the action of a catalyst.

6. A method for preparing lithium bis(fluorosulfonyl)imide, characterized in that, The purification method includes the method for dihalosulfonylimine as described in any one of claims 1 to 5.

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