Purification method of bis (fluorosulfonyl) imide and purified bis (fluorosulfonyl) imide and bis (fluorosulfonyl) imide salt

Abstract

The invention belongs to the technical field of separation and purification, and provides a purification method of imidodisulfuryl fluoride, purified imidodisulfuryl fluoride and imidodisulfuryl fluoride lithium. The purification method comprises the operation of removing impurities by using an impurity removing agent, wherein the impurity removing agent comprises bis (fluorosulfonyl) imide salt; the purification method comprises the following steps: mixing an impurity removal agent with to-be-purified bis (fluorosulfonyl) imide, and carrying out ion exchange reaction on fluorosulfonic acid in the to-be-purified bis (fluorosulfonyl) imide and bis (fluorosulfonyl) imide salt to obtain a liquid-phase mixture; and carrying out separation treatment on the liquid phase mixture to obtain purified bis (fluorosulfonyl) imide. The molar ratio of the bis (fluorosulfonyl) imide radical to the fluorosulfonate radical is more than 1: 1; in the step of carrying out the ion exchange reaction on the bis (fluorosulfonyl) imide salt and the fluorosulfonic acid, the reaction temperature is controlled to be 20 DEG C or above. The purification method provided by the invention can effectively reduce regeneration impurities.

Description

Technical Field

[0001] The invention belongs to the technical field of separation and purification, and specifically relates to a purification method of bisfluorosulfonyl imide and purified bisfluorosulfonyl imide, as well as a bisfluorosulfonyl imide salt. Background Art

[0002] Lithium bis(fluorosulfonyl imide) is an important lithium battery material. Its usage has gradually increased in recent years, and there is a trend from being an electrolyte additive to becoming the main electrolyte salt. At present, most manufacturers use bis(fluorosulfonyl imide) to prepare lithium bis(fluorosulfonyl imide). Therefore, the level of impurities in bis(fluorosulfonyl imide) will largely determine the quality level of lithium bis(fluorosulfonyl imide). One of the main impurities in bis(fluorosulfonyl imide) is fluorosulfonic acid. Under normal pressure, the boiling point of fluorosulfonic acid is 165.5°C, while the boiling point of bis(fluorosulfonyl imide) is 170°C. The boiling points of the two are very close. If the traditional distillation method is used, the equipment investment cost is high and the production efficiency is low.

[0003] At present, the commonly used fluorinated sulfonic acid and impurity removers include sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium acetate, potassium acetate, etc. Using the above impurity removers to remove fluorinated sulfonic acid will introduce other acidic substances, such as chlorides will produce hydrogen chloride tail gas, sulfates will produce sulfuric acid, and acetates will produce acetic acid, which will make the waste gas and waste liquid composition more complicated and even cause safety and environmental protection problems. Summary of the invention

[0004] The present invention aims to solve the problem at least to some extent: reducing regeneration impurities when removing fluorosulfonic acid from bisfluorosulfonyl imide. To this end, one object of the present invention is to provide a method for purifying bisfluorosulfonyl imide and purified bisfluorosulfonyl imide, as well as a lithium bisfluorosulfonyl imide, which can effectively reduce regeneration impurities.

[0005] The first aspect of the embodiment of the present application provides a method for purifying bisfluorosulfonyl imide. According to the embodiment of the present invention, the purification method comprises: adding an impurity remover to the bisfluorosulfonyl imide to be purified, wherein the impurity remover comprises a bisfluorosulfonyl imide salt; performing an ion exchange reaction between the bisfluorosulfonyl imide salt and the fluorosulfonic acid in the bisfluorosulfonyl imide to be purified to obtain a liquid phase mixture; performing separation treatment on the liquid phase mixture to obtain purified bisfluorosulfonyl imide;

[0006] The molar ratio of the bis(fluorosulfonyl)imide radical to the fluorosulfonate radical is greater than 1:1;

[0007] In the step of subjecting the bis(fluorosulfonyl)imide salt to an ion exchange reaction with fluorosulfonic acid, the reaction temperature is controlled to be above 20°C.

[0008] The purification method provided in the embodiments of the present application has the following beneficial effects: 1) The fluorosulfonic acid in bisfluorosulfonyl imide is removed more thoroughly. Bisfluorosulfonyl imide salt has a certain solubility in bisfluorosulfonyl imide. After entering the system, it belongs to a homogeneous reaction, the reaction efficiency is higher, and fluorosulfonic acid is easier to fully react. 2) It is not easy to introduce new anionic impurities after impurity removal. After impurity removal with bisfluorosulfonyl imide salt, fluorosulfonate and bisfluorosulfonyl imide will be generated, and bisfluorosulfonyl imide is the product itself, which effectively reduces the regeneration of impurities. 3) The water content of some commonly used commercially available salts for removing fluorosulfonic acid is generally difficult to reach the ppm level, and they contain a certain amount of water. The introduced water will cause the bisfluorosulfonyl imide to decompose and produce additional impurities. The bisfluorosulfonyl imide salt used in the embodiment of the present application is itself made from bisfluorosulfonyl imide. Since the bisfluorosulfonyl imide salt is generally used in batteries and has strict moisture control, it is easy to obtain a low-moisture battery-grade bisfluorosulfonyl imide salt product as an impurity remover. Therefore, it is not easy to introduce too much moisture, which can reduce the generation of additional impurities.

[0009] According to an embodiment of the present invention, the above-mentioned method for purifying bis(fluorosulfonyl)imide may further include at least one of the following additional technical features:

[0010] In some embodiments, the bisfluorosulfonyl imide salt includes at least one of an alkali metal salt of bisfluorosulfonyl imide, an alkaline earth metal salt of bisfluorosulfonic acid imide, and an ammonium salt of bisfluorosulfonic acid imide.

[0011] In some embodiments, the bisfluorosulfonyl imide salt satisfies at least one of the following:

[0012] (i) an alkali metal salt of bis(fluorosulfonyl)imide including at least one of lithium bis(fluorosulfonyl)imide, sodium bis(fluorosulfonyl)imide and potassium bis(fluorosulfonyl)imide;

[0013] (ii) alkaline earth metal salts of bis(fluorosulfonyl)imide including magnesium bis(fluorosulfonyl)imide;

[0014] (iii) The ammonium salt of bisfluorosulfonimide includes ammonium bisfluorosulfonimide.

[0015] In some embodiments, the bisfluorosulfonyl imide salt includes at least one of lithium bisfluorosulfonyl imide, sodium bisfluorosulfonyl imide, and potassium bisfluorosulfonyl imide.

[0016] In some embodiments, the molar ratio of the bis(fluorosulfonyl)imide group to the fluorosulfonate group is 4:1 to 1.1:1.

[0017] In some embodiments, in the step of subjecting the bisfluorosulfonyl imide salt to an ion exchange reaction with fluorosulfonic acid:

[0018] The reaction temperature is controlled to be 20°C to 130°C; and / or, a stirring operation is performed and the stirring speed is controlled to be above 150 rpm.

[0019] In some embodiments, the method of separating a liquid mixture includes: separating the liquid mixture by utilizing the difference in volatility of each component.

[0020] In some embodiments, the content of fluorosulfonic acid in the bisfluorosulfonyl imide to be purified is 5000 ppm to 50000 ppm; and the content of fluorosulfonic acid in the purified bisfluorosulfonyl imide is less than 1000 ppm.

[0021] The second aspect of the present application provides a purified bis(fluorosulfonyl)imide. According to an embodiment of the present invention, the purified bis(fluorosulfonyl)imide is obtained by using the above-mentioned purification method.

[0022] The purified bisfluorosulfonyl imide obtained by the above purification method in the embodiment of the present application can avoid the introduction of other anionic impurities and obtain purified bisfluorosulfonyl imide with higher purity.

[0023] The third aspect of the present application provides a lithium bis(fluorosulfonyl)imide. According to an embodiment of the present invention, the raw material for preparation includes the purified bis(fluorosulfonyl)imide mentioned above.

[0024] The lithium bis(fluorosulfonyl)imide provided in the embodiment of the present application, which is prepared using the above-mentioned purified bis(fluorosulfonyl)imide as a raw material, can provide a greener and more efficient solution for the production of lithium bis(fluorosulfonyl)imide, a high-quality lithium battery electrolyte material, in the field of new energy.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0027] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0028] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0029] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention but not excluding other contents.

[0030] As used herein, the terms "optionally", "optional" or "optionally" generally mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0031] The first aspect of the present application provides a method for purifying bisfluorosulfonyl imide, comprising: adding an impurity remover to the bisfluorosulfonyl imide to be purified, wherein the impurity remover comprises a bisfluorosulfonyl imide salt; subjecting the bisfluorosulfonyl imide salt to an ion exchange reaction with fluorosulfonic acid in the bisfluorosulfonyl imide to be purified to obtain a liquid mixture; subjecting the liquid mixture to separation treatment to obtain a purified bisfluorosulfonyl imide; wherein the molar ratio of the bisfluorosulfonyl imide radical to the fluorosulfonic acid radical is greater than 1:1; and in the step of subjecting the bisfluorosulfonyl imide salt to an ion exchange reaction with fluorosulfonic acid, controlling the reaction temperature to be greater than 20°C.

[0032] In the embodiment of the present application, the impurity remover includes a bisfluorosulfonyl imide salt, and the bisfluorosulfonyl imide does not react with the bisfluorosulfonyl imide salt. The fluorosulfonic acid in the bisfluorosulfonyl imide to be purified is more acidic than the bisfluorosulfonyl imide. According to the principle of strong acid to weak acid, the fluorosulfonic acid and the bisfluorosulfonyl imide salt undergo an ion exchange reaction to obtain a fluorosulfonate and a bisfluorosulfonyl imide. Subsequently, the fluorosulfonate and the bisfluorosulfonyl imide are separated to obtain purified bisfluorosulfonyl imide. The reaction mechanism is as follows:

[0033]

[0034] The purification method of bis(fluorosulfonyl)imide provided in the embodiments of the present application has the following beneficial effects:

[0035] 1. The removal of fluorosulfonic acid in bisfluorosulfonyl imide is more thorough. Bisfluorosulfonyl imide salt has a certain solubility in bisfluorosulfonyl imide. After entering the system, it is a homogeneous reaction with higher reaction efficiency, and fluorosulfonic acid is easier to fully react.

[0036] 2. It is not easy to introduce new anionic impurities after impurity removal. After using bisfluorosulfonyl imide salt to remove impurities, fluorosulfonate and bisfluorosulfonyl imide will be generated, and bisfluorosulfonyl imide is the product itself, which effectively reduces the regeneration impurities.

[0037] 3. At present, the water content of some commonly used commercial salts for removing fluorinated sulfonic acid is generally difficult to reach the ppm level, and they contain a certain amount of water. The introduced water will cause the decomposition of bisfluorosulfonyl imide and produce additional impurities. The bisfluorosulfonyl imide salt used in the embodiment of the present application is itself made from bisfluorosulfonyl imide. Since bisfluorosulfonyl imide salts are generally used in batteries, the water content is strictly controlled. Therefore, it is easy to obtain low-water battery-grade bisfluorosulfonyl imide salt products as impurity removers. Therefore, it is not easy to introduce too much water, which can reduce the generation of additional impurities.

[0038] The molar ratio of bisfluorosulfonyl imide and fluorosulfonate is 1:1 or more. The dosage ratio of bisfluorosulfonyl imide and fluorosulfonate will affect the impurity removal effect. The embodiment of the present application designs a molar ratio of bisfluorosulfonyl imide and fluorosulfonate of 1:1 or more, which is conducive to obtaining the target fluorinated sulfonic acid removal effect and can reduce regenerated impurities. In a specific example, the molar ratio of bisfluorosulfonyl imide and fluorosulfonate is 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, etc.

[0039] The temperature of the ion exchange reaction between the bis(fluorosulfonyl)imide salt and fluorosulfonic acid will affect the reaction efficiency. If the reaction temperature is too low, the existence form of the bis(fluorosulfonyl)imide salt and bis(fluorosulfonyl)imide and the effect of their mutual dissolution and contact will be affected. In a specific example, the reaction temperature is controlled to be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or 130°C, etc.

[0040] In some embodiments, the metal element corresponding to the metal cation of the bis(fluorosulfonyl)imide salt includes metal elements other than radioactive elements. In specific examples, the metal element includes lithium, sodium, potassium, magnesium, ammonium, and the like.

[0041] Further, under operable temperature conditions, the bisfluorosulfonyl imide salt is soluble or readily soluble in bisfluorosulfonyl imide.

[0042] Furthermore, the bisfluorosulfonyl imide salt satisfies: the saturated concentration in bisfluorosulfonic acid imide at a temperature of 20° C. to 130° C. is ≥ 0.5%.

[0043] Under the operating temperature conditions, the more the bisfluorosulfonyl imide salt is dissolved in the bisfluorosulfonic acid imide, the better the reaction effect is.

[0044] Furthermore, fluorosulfonic acid and bisfluorosulfonyl imide salt undergo ion exchange reaction to obtain fluorosulfonate and bisfluorosulfonyl imide, which can be easily separated.

[0045] In some embodiments, the impurity remover further includes an auxiliary reagent, which includes a reagent that can promote the dissolution of the bisfluorosulfonyl imide salt, or includes a reagent for removing other impurities of the bisfluorosulfonyl imide to be purified.

[0046] In some embodiments, the bisfluorosulfonyl imide salt includes at least one of an alkali metal salt of bisfluorosulfonyl imide, an alkaline earth metal salt of bisfluorosulfonic acid imide, and an ammonium salt of bisfluorosulfonic acid imide.

[0047] In the embodiments of the present application, at least one of the bisfluorosulfonyl imide salts including alkali metal salts of bisfluorosulfonyl imide, alkaline earth metal salts of bisfluorosulfonic acid imide and ammonium salts of bisfluorosulfonic acid imide can be selected for removing fluorosulfonic acid, which is beneficial to reduce the purification cost and facilitate the separation operation of bisfluorosulfonyl imide and fluorosulfonic acid salt.

[0048] In some embodiments, the bisfluorosulfonyl imide salt satisfies at least one of the following:

[0049] (i) an alkali metal salt of bis(fluorosulfonyl)imide including at least one of lithium bis(fluorosulfonyl)imide, sodium bis(fluorosulfonyl)imide and potassium bis(fluorosulfonyl)imide;

[0050] (ii) alkaline earth metal salts of bis(fluorosulfonyl)imide including magnesium bis(fluorosulfonyl)imide;

[0051] (iii) The ammonium salt of bis(fluorosulfonyl)imide includes ammonium bis(fluorosulfonyl)imide.

[0052] In some embodiments, the bisfluorosulfonyl imide salt includes at least one of lithium bisfluorosulfonyl imide, sodium bisfluorosulfonyl imide, and potassium bisfluorosulfonyl imide.

[0053] In the embodiments of the present application, at least one of lithium bis(fluorosulfonyl)imide, sodium bis(fluorosulfonyl)imide and potassium bis(fluorosulfonyl)imide is used to remove fluorosulfonic acid, which has low cost, and the generated fluorosulfonate and bis(fluorosulfonyl)imide are easy to separate by conventional methods such as distillation, and lithium bis(fluorosulfonyl)imide is the target product of bis(fluorosulfonyl)imide, thus avoiding the introduction of other impurity cations.

[0054] In some embodiments, the molar ratio of the bis(fluorosulfonyl)imide group to the fluorosulfonate group is 4:1 to 1.1:1.

[0055] The dosage ratio of bisfluorosulfonyl imide and fluorosulfonate affects the production cost and impurity removal effect. The embodiment of the present application designs a molar ratio of bisfluorosulfonyl imide and fluorosulfonate of 4:1 to 1.1:1, which is beneficial to show a higher fluorinated sulfonic acid removal effect at a lower production cost, and can effectively reduce regenerated impurities. In the specific example, the molar ratio of bisfluorosulfonyl imide and fluorosulfonate is 4:1, 3.8:1, 3.6:1, 3.4:1, 3.2:1, 3:1, 2.8:1, 2.6:1, 2.4:1, 2.2:1, 2:1, 1.8:1, 1.6:1, 1.4:1, 1.2:1 and 1.1:1, etc.

[0056] In some embodiments, in the step of subjecting the bisfluorosulfonyl imide salt to an ion exchange reaction with fluorosulfonic acid:

[0057] The reaction temperature is controlled to be 20°C to 130°C; and / or, a stirring operation is performed and the stirring speed is controlled to be above 150 rpm.

[0058] On the one hand, the temperature of the ion exchange reaction between the bisfluorosulfonyl imide salt and fluorosulfonic acid will affect the reaction efficiency. If the reaction temperature is too low, it will affect the existence form of the bisfluorosulfonyl imide salt and the bisfluorosulfonyl imide and the mutual dissolution and contact effect; the higher the reaction temperature, the more conducive to the ion exchange reaction between the bisfluorosulfonyl imide salt and fluorosulfonic acid, but too high a temperature may affect the production cost and production safety. On the other hand, controlling the reaction temperature to match the separation temperature of the later bisfluorosulfonyl imide and fluorosulfonic acid is conducive to improving production efficiency and reducing production costs. In a specific example, the reaction temperature is controlled to be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or 130°C, etc.

[0059] Further, the reaction temperature is controlled to be 70°C to 130°C. In a specific example, the reaction temperature is controlled to be 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, etc. Further, the reaction temperature is controlled to be 100°C to 120°C.

[0060] After adding the impurity remover to the bisfluorosulfonyl imide to be purified, stirring is performed to facilitate the bisfluorosulfonyl imide salt to be fully dispersed and dissolved in the bisfluorosulfonyl imide and fully contact with fluorosulfonic acid, thereby improving the reaction efficiency of the bisfluorosulfonyl imide salt and fluorosulfonic acid. Within the speed range that the production equipment can achieve, the higher the stirring speed, the more conducive the ion exchange reaction is.

[0061] Further, a stirring operation is performed, and the stirring speed is controlled to be 150 rpm to 1000 rpm. In a specific example, the stirring speed is controlled to be 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm or 1000 rpm, etc.

[0062] In some embodiments, the method of separating a liquid mixture includes: separating the liquid mixture by utilizing the difference in volatility of each component.

[0063] Furthermore, the method of separating the liquid mixture by utilizing the difference in volatility of each component includes distillation, and in a specific example, includes vacuum distillation.

[0064] Further, the vacuum distillation control parameters include: pressure of 0-40KPa, temperature of 70°C-130°C. In a specific example, the reaction temperature is controlled to be 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, etc. Further, the reaction temperature is controlled to be 100°C-120°C.

[0065] In some embodiments, the content of fluorosulfonic acid in the bisfluorosulfonyl imide to be purified is 5000 ppm to 50000 ppm; and the content of fluorosulfonic acid in the purified bisfluorosulfonyl imide is less than 1000 ppm.

[0066] The purification method provided in the embodiments of the present application can be used to treat crude bis(fluorosulfonyl)imides with various fluorosulfonic acid contents, and can almost treat crude bis(fluorosulfonyl)imides with all fluorosulfonic acid contents in the actual production process.

[0067] In a specific example, the content of fluorosulfonic acid in the bisfluorosulfonyl imide to be purified is 5000 ppm, 6000 ppm, 7000 ppm, 8000 ppm, 9000 ppm, 10000 ppm, 11000 ppm, 15000 ppm, 20000 ppm, 25000 ppm, 30000 ppm, 35000 ppm, 40000 ppm, 45000 ppm or 50000 ppm, etc.

[0068] The purification method provided in the embodiments of the present application can effectively remove fluorosulfonic acid, so that the content of fluorosulfonic acid in the purified bis(fluorosulfonyl)imide reaches below 1000 ppm. In specific examples, the content of fluorosulfonic acid reaches 1000 ppm, 900 ppm, 800 ppm, 700 ppm, 600 ppm, 500 ppm, 400 ppm, 300 ppm, etc.

[0069] In some embodiments, the purification method is performed in an anhydrous environment.

[0070] Furthermore, nitrogen replacement is performed in the reaction container, and then the bisfluorosulfonyl imide to be purified and the bisfluorosulfonyl imide salt are added into the reactor.

[0071] The second aspect of the present application provides a purified bis(fluorosulfonyl)imide obtained by the above-mentioned purification method.

[0072] The purified bisfluorosulfonyl imide obtained by the above purification method in the embodiment of the present application can avoid the introduction of other anionic impurities and obtain purified bisfluorosulfonyl imide with higher purity.

[0073] In some embodiments, the content of fluorosulfonic acid in the purified bisfluorosulfonimide is less than 1000 ppm.

[0074] The third aspect of the present application provides a bisfluorosulfonyl imide salt, comprising at least one of lithium bisfluorosulfonyl imide and sodium bisfluorosulfonyl imide, and the raw materials for preparation include the above-mentioned purified bisfluorosulfonyl imide.

[0075] The bisfluorosulfonyl imide salt provided in the embodiments of the present application, which is prepared using the above-mentioned purified bisfluorosulfonyl imide as a raw material, can provide a greener and more efficient solution for the production of lithium bisfluorosulfonyl imide / sodium bisfluorosulfonyl imide, a high-quality lithium / sodium battery electrolyte material, in the field of new energy.

[0076] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.

[0077] Example 1

[0078] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as follows:

[0079] The reactor (reactor material is PTFE-lined) was replaced with nitrogen, 350 g of crude bis(fluorosulfonyl)imide was added, the content of fluorosulfonic acid in the crude bis(fluorosulfonyl)imide was 8700 ppm, 22.78 g of lithium bis(fluorosulfonyl)imide was added, and ion exchange reaction was carried out. The reaction temperature was set to 110° C. and the stirring speed was set to 400 rpm.

[0080] After 0.5 h, when the ion exchange reaction was completed, vacuum distillation was performed at a pressure of 2 KPa and a temperature of 110° C. Purified bisfluorosulfonyl imide was obtained by vacuum distillation. The content of fluorosulfonic acid in the purified bisfluorosulfonyl imide is shown in Table 1.

[0081] Example 2

[0082] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0083] The amount of lithium bis(fluorosulfonyl)imide added was 17.08 g.

[0084] Example 3

[0085] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0086] The amount of lithium bis(fluorosulfonyl)imide added was: 11.39 g.

[0087] Example 4

[0088] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0089] The amount of lithium bis(fluorosulfonyl)imide added was: 6.26 g.

[0090] Example 5

[0091] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0092] The amount of lithium bis(fluorosulfonyl)imide added was: 25.43 g.

[0093] Example 6

[0094] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0095] Sodium bis(fluorosulfonyl)imide was used to replace lithium bis(fluorosulfonyl)imide, and the added amount was: 24.73 g.

[0096] Example 7

[0097] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0098] Sodium bis(fluorosulfonyl)imide was used to replace lithium bis(fluorosulfonyl)imide, and the added amount was: 12.37 g.

[0099] Example 8

[0100] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0101] Sodium bis(fluorosulfonyl)imide was used to replace lithium bis(fluorosulfonyl)imide, and the added amount was: 6.80 g.

[0102] Example 9

[0103] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0104] Potassium bis(fluorosulfonyl)imide was used to replace lithium bis(fluorosulfonyl)imide, and the added amount was: 26.68 g.

[0105] Example 10

[0106] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0107] Potassium bis(fluorosulfonyl)imide was used to replace lithium bis(fluorosulfonyl)imide, and the added amount was: 13.34 g.

[0108] Embodiment 11

[0109] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0110] Potassium bis(fluorosulfonyl)imide was used to replace lithium bis(fluorosulfonyl)imide, and the added amount was 7.34 g.

[0111] Example 12

[0112] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0113] Bis(fluorosulfonyl)imide magnesium was used to replace bis(fluorosulfonyl)imide lithium, and the added amount was: 23.39 g.

[0114] Example 13 Example 18

[0115] This embodiment provides a method for purifying bisfluorosulfonyl imide, and the specific operation is as shown in Example 3, except that:

[0116] The reaction temperatures were set at 20°C, 70°C, 100°C, 120°C, 130°C, and 150°C, respectively.

[0117] Example 19-Example 22

[0118] This embodiment provides a method for purifying bisfluorosulfonyl imide, and the specific operation is as shown in Example 3, except that:

[0119] The stirring speeds were set to 80 rpm, 120 ppm, 150 rpm, and 600 rpm, respectively.

[0120] Example 23-Example 25

[0121] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0122] The contents of fluorosulfonic acid in the crude bis(fluorosulfonyl)imide were 5000ppm, 20000ppm and 50000ppm respectively.

[0123] Embodiment 26

[0124] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0125] Ammonium bis(fluorosulfonyl)imide was used to replace lithium bis(fluorosulfonyl)imide, and the added amount was: 12.06 g.

[0126] Embodiment 27

[0127] This embodiment provides a method for purifying bis(fluorosulfonyl)imide, and the specific operation is as shown in Example 1, except that:

[0128] Ammonium bis(fluorosulfonyl)imide was used to replace lithium bis(fluorosulfonyl)imide, and the added amount was: 6.63 g.

[0129] Comparative Example 1

[0130] This case provides a method for purifying bis(fluorosulfonyl)imide. The specific operation is as shown in Example 3, except that sodium chloride is used to replace lithium bis(fluorosulfonyl)imide.

[0131] Comparative Example 2

[0132] This case provides a method for purifying bis(fluorosulfonyl)imide. The specific operation is as shown in Example 3, except that sodium sulfate is used to replace lithium bis(fluorosulfonyl)imide.

[0133] Comparative Example 3

[0134] This case provides a method for purifying bis(fluorosulfonyl)imide. The specific operation is as shown in Example 3, except that the amount of lithium bis(fluorosulfonyl)imide used is 5.41 g.

[0135] Comparative Example 4

[0136] This case provides a method for purifying bis(fluorosulfonyl)imide. The specific operation is as shown in Example 3, except that the reaction temperature is set to 10°C.

[0137] Detection method:

[0138] 1. Detection method of fluorosulfonic acid: anion chromatography detection of fluorosulfonate.

[0139] 2. Detection method for other impurities: anion chromatography to detect chloride ions.

[0140] Test results:

[0141] The results of the purification tests of the various embodiments and comparative examples are shown in Table 1.

[0142] Table 1 Test results of purification effects of various embodiments and comparative examples

[0143]

[0144] From the results of purifying bisfluorosulfonyl imide in the above-mentioned embodiments and comparative examples, it can be seen that the embodiments of the present application use bisfluorosulfonyl imide salt as an impurity remover to remove fluorosulfonic acid. By controlling the molar ratio of bisfluorosulfonyl imide and fluorosulfonate to be above 1:1 and controlling the reaction temperature to be above 20°C, fluorosulfonic acid can be effectively removed and the fluorosulfonic acid content in bisfluorosulfonyl imide can be controlled to be below 1000 ppm.

[0145] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for purifying bis(fluorosulfonyl)imide, characterized in that: Including the use of impurity removal operations: The impurity remover comprises a bisfluorosulfonyl imide salt; the impurity remover is mixed with the bisfluorosulfonyl imide to be purified, so that the fluorosulfonic acid in the bisfluorosulfonyl imide to be purified undergoes an ion exchange reaction with the bisfluorosulfonyl imide salt to obtain a liquid phase mixture; The liquid phase mixture is separated to obtain purified bis(fluorosulfonyl)imide; The molar ratio of the bis(fluorosulfonyl)imide radical to the fluorosulfonate radical is greater than 1:1; In the step of subjecting the bis(fluorosulfonyl)imide salt to an ion exchange reaction with fluorosulfonic acid, the reaction temperature is controlled to be above 20°C.

2. The method for purifying bis(fluorosulfonyl)imide according to claim 1, characterized in that: The bisfluorosulfonyl imide salt satisfies: the saturation concentration in the bisfluorosulfonic acid imide is ≥ 0.5% under the temperature condition of 20°C to 130°C.

3. The method for purifying bis(fluorosulfonyl)imide according to claim 1, characterized in that: The bisfluorosulfonyl imide salt includes at least one of an alkali metal salt of bisfluorosulfonyl imide, an alkaline earth metal salt of bisfluorosulfonic acid imide and an ammonium salt of bisfluorosulfonic acid imide.

4. The method for purifying bis(fluorosulfonyl)imide according to claim 3, characterized in that: The bisfluorosulfonyl imide salt satisfies at least one of the following: (i) the alkali metal salt of bis(fluorosulfonyl)imide comprises at least one of lithium bis(fluorosulfonyl)imide, sodium bis(fluorosulfonyl)imide and potassium bis(fluorosulfonyl)imide; (ii) the alkaline earth metal salt of bis(fluorosulfonyl)imide includes magnesium bis(fluorosulfonyl)imide; (iii) The ammonium salt of bisfluorosulfonyl imide includes ammonium bisfluorosulfonyl imide.

5. The method for purifying bis(fluorosulfonyl)imide according to claim 1, characterized in that: The bisfluorosulfonyl imide salt includes at least one of lithium bisfluorosulfonyl imide, sodium bisfluorosulfonyl imide and potassium bisfluorosulfonyl imide.

6. The method for purifying bisfluorosulfonyl imide according to any one of claims 1 to 5, characterized in that: The molar ratio of the bis(fluorosulfonyl)imide radical to the fluorosulfonate radical is 4:1 to 1.1:

1.

7. The method for purifying bisfluorosulfonyl imide according to claim 1, characterized in that: In the step of subjecting the bis(fluorosulfonyl)imide salt to an ion exchange reaction with fluorosulfonic acid: Control the reaction temperature to: 20℃~130℃; And / or, perform a stirring operation and control the stirring speed to be above 150 rpm.

8. The method for purifying bisfluorosulfonyl imide according to claim 1, characterized in that: The method for separating the liquid mixture comprises: separating the liquid mixture by utilizing the difference in volatility of each component.

9. The method for purifying bisfluorosulfonyl imide according to claim 1, characterized in that: The content of fluorosulfonic acid in the bisfluorosulfonyl imide to be purified is 5000 ppm to 50000 ppm; and / or the content of fluorosulfonic acid in the purified bisfluorosulfonyl imide is less than 1000 ppm.

10. A method for purifying bis(fluorosulfonyl)imide, characterized in that: Obtained by the purification method according to any one of claims 1 to 9.

11. A bisfluorosulfonyl imide salt, characterized in that: The preparation raw materials include the purified bisfluorosulfonyl imide according to claim 10.

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