WO2023236574A1

WO2023236574A1 - Lithium bisfluorosulfonylimide and method for purifying lithium bisfluorosulfonylimide

Info

Publication number: WO2023236574A1
Application number: PCT/CN2023/075349
Authority: WO
Inventors: 曾学强; 程思聪; 高俊; 魏新年
Original assignee: 时代思康新材料有限公司
Priority date: 2022-06-10
Filing date: 2023-02-10
Publication date: 2023-12-14
Also published as: CN117246982A

Abstract

The present application relates to lithium bisfluorosulfonylimide and a method for purifying lithium bisfluorosulfonylimide. The method comprises: providing a mixture comprising lithium bisfluorosulfonylimide; adding an organic ammonium salt to the mixture, and reacting same to obtain an intermediate mixture; and under alkaline conditions, reacting the intermediate mixture with lithium ions to obtain lithium bisfluorosulfonylimide. The method of the present application can improve the purity of lithium bisfluorosulfonylimide.

Description

Lithium bisfluorosulfonyl imide and method for purifying lithium bisfluorosulfonyl imide

Cross-references to related applications

This application claims priority to the Chinese patent application 202210652749.9 titled "Lithium Bisfluorosulfonimide and Method for Purifying Lithium Bisfluorosulfonimide" submitted on June 10, 2022. The entire content of this application is approved. Incorporated into this article by reference.

Technical field

This application relates to the technical field of chemical production, in particular to lithium bisfluorosulfonyl imide and a method for purifying lithium bisfluorosulfonyl imide.

Background technique

Rechargeable and rechargeable batteries have the advantages of small size, high energy density, high safety, small self-discharge, and long life. They are widely used in energy storage, communications, electric vehicles, aerospace and other fields. Among rechargeable batteries, lithium-ion batteries have particularly excellent performance and have been extensively studied in the battery field in order to further improve their performance.

Lithium bisfluorosulfonimide is the main component of the electrolyte of lithium-ion batteries. The purity of lithium bisfluorosulfonimide has an important impact on the electrolyte. The higher the purity, the better the performance of the lithium-ion battery; the lower the purity. , the performance of lithium-ion batteries is getting worse, so how to improve the purity of lithium bisfluorosulfonyl imide is an urgent problem to be solved.

Contents of the invention

The present application provides a lithium bisfluorosulfonimide and a method for purifying lithium bisfluorosulfonimide, which method can improve the purity of lithium bisfluorosulfonimide.

In the first aspect, this application proposes a method for purifying lithium bisfluorosulfonimide. The method includes: providing a mixture containing lithium bisfluorosulfonimide; adding an organic ammonium salt to the mixture, and reacting to obtain an intermediate The intermediate mixture is reacted with lithium ions under alkaline conditions to obtain lithium bisfluorosulfonyl imide.

Thus, this application converts the lithium bisfluorosulfonyl imide in the mixture into an intermediate mixture in advance, partially removes the impurities in the mixture during this process, and then reconverts the intermediate mixture into lithium bisfluorosulfonyl imide. , thereby improving the purity of the finally obtained lithium bisfluorosulfonyl imide.

In some embodiments, the method further includes: purifying the intermediate mixture.

Therefore, after the intermediate mixture is generated in this application, there will inevitably be impurities in the intermediate mixture. The intermediate mixture is purified to remove the impurities in the intermediate mixture, thereby improving the purity of the intermediate mixture; and then the purified The intermediate mixture is converted into lithium bisfluorosulfonyl imide, thereby further improving the purity of lithium bisfluorosulfonyl imide.

In some embodiments, the step of purifying the intermediate mixture includes: contacting the intermediate mixture with a decolorizing agent to adsorb and remove colored impurities in the intermediate mixture.

Therefore, the decolorizing agent of the present application can adsorb colored impurities to achieve the purpose of decolorization.

In some embodiments, the step of purifying the intermediate mixture includes: contacting the intermediate mixture with a cleaning agent to remove metal ions in the intermediate mixture.

Therefore, this application uses a cleaning agent to clean the intermediate mixture to elute free sodium ions, potassium ions, calcium ions, iron ions, lead ions, chromium ions, zinc ions and other metal ions in the intermediate mixture out of the system, thereby To achieve the purpose of removing metal ions, and then to achieve the purpose of improving the purity of lithium bisfluorosulfonyl imide.

In some embodiments, the decolorizing agent includes one or more of activated carbon particles, activated carbon fibers, zeolites, and diatomaceous earth.

Therefore, the decolorizing agent of the present application can adsorb colored impurities, thereby achieving the purpose of improving the purity of the intermediate mixture.

In some embodiments, the cleaning agent includes one or more of water, sodium salt, potassium salt, and lithium salt; optionally, the sodium salt includes one or more of sodium chloride, sodium sulfate, and sodium carbonate. ; Potassium salts include one or more of potassium chloride, potassium sulfate and potassium sulfate; lithium salts include one or more of lithium chloride, lithium sulfate and lithium carbonate.

Therefore, the cleaning agent of the present application has the ability to be miscible with metal ions and can elute and remove metal ions, thereby achieving the purpose of improving the purity of the intermediate mixture.

In some embodiments, the organic ammonium salts include hydrogen fluoride salts of tertiary amines and/or hydrogen fluoride salts of quaternary amines. The fluoride ions in the organic ammonium salt easily combine with the lithium ions in lithium bisfluorosulfonimide to form lithium fluoride precipitate, thus promoting the reaction; and the lithium fluoride precipitate may carry some impurities, thereby achieving the purpose of removing impurities. .

In some embodiments, the hydrogen fluoride salt of the tertiary amine includes one or more of trimethylamine hydrogen fluoride salt, triethylamine hydrogen fluoride salt, tripropylamine hydrogen fluoride salt, diisopropylethylamine hydrogen fluoride salt and tributylamine hydrogen fluoride salt; Alternatively, the hydrogen fluoride salt of the tertiary amine includes triethylamine hydrogen fluoride salt. The raw materials of the above-mentioned organic ammonium salt are easily available, and the reaction with lithium bisfluorosulfonyl imide is relatively complete.

In some embodiments, the hydrogen fluoride salt of quaternary ammonium includes one or more of tetramethylamine hydrogen fluoride salt, tetraethylammonium hydrogen fluoride salt, tetrapropylamine hydrogen fluoride salt and tetrabutylamine hydrogen fluoride salt. The raw materials of the above-mentioned organic ammonium salt are easily available, and the reaction with lithium bisfluorosulfonyl imide is relatively complete.

In some embodiments, the molar ratio of the mixture and the organic ammonium salt is 1: (1-10).

Therefore, when the molar ratio of the mixture of the present application and the organic ammonium salt satisfies the above range, the organic ammonium salt can fully react with the lithium bisfluorosulfonyl imide in the mixture, thereby converting the lithium ions in the lithium bisfluorosulfonyl imide into Replace with organic amine cations to a greater extent, and then convert lithium bisfluorosulfonyl imide into an intermediate mixture to the greatest extent, thereby increasing the final yield of lithium bisfluorosulfonyl imide.

In some embodiments, the molar ratio of the intermediate mixture and lithium ions is 1: (1～10).

Therefore, the molar ratio of the intermediate mixture and lithium ions in the present application is within the above range, which can ensure that the organic amine cations in the intermediate mixture are fully replaced by lithium ions, thereby converting the intermediate mixture into bisfluorosulfonate to a greater extent. imide to increase the yield of bisfluorosulfonimide.

In a second aspect, this application proposes a lithium bisfluorosulfonyl imide, which is prepared by the method of any embodiment of the first aspect of this application.

Description of the drawings

In order to explain the technical solutions of the embodiments of the present application more clearly, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. Those of ordinary skill in the art can also obtain other drawings based on the drawings without exerting creative efforts.

Figure 1 is a schematic flow diagram for purifying lithium bisfluorosulfonyl imide provided by some embodiments of the present application;

Figure 2 is a schematic flow chart for purifying lithium bisfluorosulfonimide provided by other embodiments of the present application;

Figure 3 is a schematic flow diagram for purifying lithium bisfluorosulfonyl imide provided by some embodiments of the present application;

Figure 4 is a schematic flow diagram for purifying lithium bisfluorosulfonyl imide provided in some further embodiments of the present application.

Detailed ways

Hereinafter, embodiments specifically disclosing lithium bisfluorosulfonyl imide and a method for purifying lithium bisfluorosulfonyl imide will be described in detail with appropriate reference to the drawings. However, unnecessary detailed explanations may be omitted. For example, omitting detailed explanations of well-known matters or repeating the same structure explained situation. This is to prevent the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

"Ranges" disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5. In this application, unless stated otherwise, the numerical range "a-b" represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations. In addition, when stating that a certain parameter is an integer ≥ 2, it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

If there is no special instructions, all steps of the present application can be performed sequentially or randomly, and are preferably performed sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, mentioning that the method can also include step (c) means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c). , can also include steps Steps (a), (c) and (b) may also include steps (c), (a) and (b), etc.

If there is no special explanation, the words "include" and "include" mentioned in this application represent open expressions, which may also be closed expressions. For example, "comprising" and "comprising" may mean that other components not listed may also be included or included, or only the listed components may be included or included.

In this application, the term "or" is inclusive unless otherwise stated. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).

The fluoride ions in Lithium Bis(fluorosulfonyl)imide (LiFSI) have strong electron-withdrawing properties, which weakens the coordination between anions and cations of Lithium Bis(fluorosulfonyl)imide and reduces the activity of lithium ions. It has strong electrical conductivity, high thermal stability and electrochemical stability, and basically does not generate corrosive gases such as hydrofluoric acid. In view of the excellent characteristics of lithium bisfluorosulfonimide, as a lithium salt in the electrolyte of lithium-ion batteries, it can improve the rate performance, cycle life and safety of lithium-ion batteries.

There are many methods for producing lithium bisfluorosulfonyl imide, such as using sulfonamide to react with sulfonyl chloride and chlorosulfonic acid to obtain bischlorosulfonyl imide, and then undergoing fluorination and lithiation reactions to finally obtain LiFSI; and Or use sulfonyl chloride or sulfuryl fluoride and ammonia to react to obtain bischloro(fluoro)sulfonimide or the alkali salt of bischloro(fluoro)sulfonimide, and then undergo fluorination and lithiation reactions to obtain the product LiFSI. Or use fluorosulfonic acid to react with urea to obtain bisfluorosulfonimide, and then lithiate with a lithiating agent to obtain lithium bisfluorosulfonimide. In the process of generating lithium bisfluorosulfonyl imide, impurities are inevitably produced, resulting in the purity of lithium bisfluorosulfonyl imide not reaching 100%.

The inventor found that in order to improve the purity of lithium bisfluorosulfonimide, lithium bisfluorosulfonimide is usually purified by recrystallization. However, due to the continuous enrichment of impurities in the recrystallization mother liquor, recrystallization will inevitably occur. Mother liquor, resulting in the purity of lithium bisfluorosulfonimide can be obtained in part Improvement, but cannot be further improved, and the purified lithium bisfluorosulfonyl imide may still not meet production needs.

In order to solve the above problems, the inventor proposed a method for purifying lithium bisfluorosulfonyl imide, as shown in Figure 1. The method includes: step S100, providing a mixture containing lithium bisfluorosulfonyl imide; step S200, Add an organic ammonium salt to the mixture, and react to obtain an intermediate mixture; step S300, react the intermediate mixture with lithium ions under alkaline conditions to obtain lithium bisfluorosulfonyl imide. The method of the present application can further improve the purity of lithium bisfluorosulfonimide. The method of the present application is not only applicable to recrystallized lithium bisfluorosulfonyl imide; it is also applicable to wastewater containing lithium bisfluorosulfonyl imide.

Step S100, providing a mixture containing lithium bisfluorosulfonyl imide.

The mixture containing lithium bisfluorosulfonimide can be a recrystallization mother liquor containing lithium bisfluorosulfonimide with a higher purity, such as a purity of 90%, 85%, etc., or it can be a lower purity, such as a purity of 2%, 5%, etc. % and other wastewater containing lithium bisfluorosulfonyl imide. In this article, in addition to containing lithium bisfluorosulfonimide, the mixture will inevitably contain impurities. For example, the impurities may include metal ions, anions, and colored impurities such as pigments. The metal ions may include, for example, sodium ions. , potassium ions, calcium ions, iron ions, lead ions, chromium ions, zinc ions, etc. Anions may include, for example, chloride ions and the like. Purity refers to the ratio of the mass of lithium bisfluorosulfonimide to the total mass of the mixture.

Step S200: Add organic ammonium salt to the mixture and react to obtain an intermediate mixture.

The organic ammonium salt can react with the lithium bisfluorosulfonyl imide in the mixture. The lithium ions in the lithium bisfluorosulfonyl imide are easily replaced by organic ammonium cations to form an intermediate mixture. The intermediate mixture is subsequently further purified to improve Purity of intermediate mixtures.

In some embodiments, the organic ammonium salts include hydrogen fluoride salts of tertiary amines and/or hydrogen fluoride salts of quaternary amines. When the hydrogen fluoride salt of an organic amine reacts with lithium bisfluorosulfonimide, the fluoride ions in the organic ammonium salt easily combine with the lithium ions in lithium bisfluorosulfonimide to form lithium fluoride precipitation, thus promoting the reaction. and the lithium fluoride precipitation may carry some impurities, thereby achieving the purpose of removing impurities. Moreover, the lithium ions in the lithium fluoride precipitation can be recycled.

Exemplarily, the hydrogen fluoride salt of the tertiary amine may include trimethylamine trihydrofluoride (Trimethylamine Trihydrofluoride), triethylamine Trihydrofluoride (TEAHF), tripropylamine Trihydrofluoride (Tripropylamine Trihydrofluoride), diisopropylethylamine hydrogen fluoride ( One or more of Diisopropylethylamine Trihydrofluoride) and Tributylamine Trihydrogenfluoride. Alternatively, the hydrogen fluoride salt of the tertiary amine may include triethylamine hydrogen fluoride salt. The hydrogen fluoride salt of tertiary amine is easily available and reacts relatively thoroughly with lithium bisfluorosulfonyl imide.

Taking the organic ammonium salt as triethylamine hydrogen fluoride salt TEAHF as an example, the reaction process with lithium bisfluorosulfonyl imide is explained:

Exemplarily, the hydrogen fluoride salt of the quaternary ammonium may include one or more of tetramethylamine hydrogen fluoride salt, tetraethylammonium hydrogen fluoride salt, tetrapropylamine hydrogen fluoride salt and tetrabutylamine hydrogen fluoride salt. The reaction between quaternary ammonium hydrogen fluoride salt and lithium bisfluorosulfonimide is relatively complete.

In some embodiments, the molar ratio of the mixture and the organic ammonium salt may be 1: (1-10).

When the molar ratio of the mixture and the organic ammonium salt meets the above range, the organic ammonium salt can fully react with the lithium bisfluorosulfonimide in the mixture, thereby replacing the lithium ions in the lithium bisfluorosulfonimide with Organic amine cations are used to convert lithium bisfluorosulfonyl imide into an intermediate mixture to a greater extent, thereby improving the yield and purity of the final lithium bisfluorosulfonyl imide. Exemplarily, the molar ratio of the mixture and the organic ammonium salt can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:2, 1:3, 1:4, 1:5, 1:6, 1: 7, 1:8, 1:9 or 1:10; or the molar ratio between the two can be within the range of any two of the above values.

Step S300: react the intermediate mixture with lithium ions under alkaline conditions to obtain lithium bisfluorosulfonyl imide.

Under alkaline conditions, the intermediate mixture and lithium ions can undergo a lithium reaction for alkali exchange, and the cations in the intermediate mixture are replaced with lithium ions again, thereby generating lithium bisfluorosulfonyl imide. For example, lithium hydroxide can be added to the system to form alkaline conditions to avoid further introduction of other metal ions.

Taking the organic amine salt as triethylamine hydrogen fluoride salt as an example, the reaction process of step S300 is as follows:

In some embodiments, the molar ratio of the intermediate mixture to lithium ions is 1: (1.0-10.0).

The molar ratio of the intermediate mixture and lithium ions is within the above range, which can ensure that the organic amine cations in the intermediate mixture are fully replaced by lithium ions, thereby converting the intermediate mixture into bisfluorosulfonyl imide to a greater extent and improving the bisfluorosulfonyl imide. Yield of fluorosulfonimide. Exemplarily, the molar ratio of the intermediate mixture and lithium ions can be 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8 , 1:1.9, 1:2.0, 1:3.0, 1:4.0, 1:5.0, 1:6.0, 1:7.0, 1:8.0, 1:9.0 or 1:10.0; or the molar ratio of the two can be as above A range of any two values.

In the embodiment of the present application, the lithium bisfluorosulfonyl imide in the mixture is converted into an intermediate mixture in advance, during which the impurities in the mixture are partially removed, and then the intermediate mixture is converted again It is lithium bisfluorosulfonyl imide, thereby improving the purity of the finally obtained lithium bisfluorosulfonyl imide.

As shown in Figure 2, in some embodiments, after step S200, it may also include:

Step S400: Purify the intermediate mixture.

After the intermediate mixture is generated, there will inevitably be impurities in the intermediate mixture, most of which are metal ions, anions, colored impurities, etc. carried by the mixture containing lithium bisfluorosulfonyl imide. The intermediate mixture is purified to remove impurities in the intermediate mixture, thereby improving the purity of the intermediate mixture; then the purified intermediate mixture is converted into lithium bisfluorosulfonimide, thereby improving the final product bisfluorosulfonimide. The purity of lithium amine. In the embodiments of the present application, the purity of lithium bisfluorosulfonimide is improved by converting lithium bisfluorosulfonimide into an intermediate mixture, and purifying the intermediate mixture to remove impurities in the entire system.

As shown in Figure 3, as some examples, step S400 may include:

Step S410, contact the intermediate mixture with a decolorizing agent to adsorb and remove colored impurities in the intermediate mixture.

The decolorizing agent has a decolorizing function. For example, the decoloring agent may include one or more of activated carbon particles, activated carbon fibers, zeolite and diatomaceous earth. Optionally, the decolorizing agent can have a porous skeleton structure, and can adsorb colored impurities into the pores of the porous skeleton structure to achieve the purpose of decolorization; and the decoloring agent will basically not react with the system. The above-mentioned decolorizing agents can be used singly or in combination.

The embodiments of this application use a decolorizing agent to remove colored impurities in the intermediate mixture to remove some impurities in the entire system, which is beneficial to improving the purity of the final lithium bisfluorosulfonimide.

As shown in Figure 4, as another example, step S400 may also include:

Step S420: Contact the intermediate mixture with a cleaning agent to remove metal ions in the intermediate mixture.

Metal ions may include sodium ions, potassium ions, calcium ions, iron ions, lead ions, chromium ions, zinc ions, etc. In particular, sodium, potassium and lithium are elements of the same main group and are difficult to react with each other through chemical reactions. Remove sodium and potassium from the lithium system. In this step, lithium ions are precipitated in advance, that is, lithium ions basically exist as the precipitation of lithium fluoride, while metal ions such as sodium ions and potassium ions may still be free in the intermediate mixture in the form of cations, so this application adopts The cleaning agent cleans the intermediate mixture to elute free sodium ions, potassium ions, calcium ions, iron ions, lead ions, chromium ions, zinc ions and other metal ions in the intermediate mixture out of the system, thereby achieving the purpose of removing metal ions. , thereby achieving the purpose of improving the purity of lithium bisfluorosulfonyl imide. Moreover, the eluted metal ions can be recycled; anions can also be removed to a certain extent in this step, thereby further removing impurities from the system.

The cleaning agent basically does not react with the intermediate mixture, but has the ability to be miscible with metal ions. Exemplarily, the cleaning agent may include one or more of water, sodium salt, potassium salt, and lithium salt. For example, the sodium salt may include one or more of sodium chloride, sodium sulfate, and sodium carbonate; the potassium salt may include one or more of potassium chloride, potassium sulfate, and potassium sulfate; the lithium salt may include chloride One or more of lithium, lithium sulfate and lithium carbonate.

Steps S410 and S420 can be executed individually, for example, only the operation of step S410 is executed, or only the operation of step S420 is executed; of course, both steps can also be executed. When both steps are executed, in no particular order, for example, they can be executed first Step S410, and then execute step S420; you may also execute step S420 first, and then execute step S410.

Optionally, in order to further improve the purity of the finally obtained lithium bisfluorosulfonimide, a cleaning agent can be used for repeated cleaning. Of course, different cleaning agents can also be used for separate cleaning.

On the other hand, the present application also provides a lithium bisfluorosulfonyl imide, which can be prepared by the above embodiments. The purity of the lithium bisfluorosulfonyl imide is relatively high and can meet the requirements of production needs. The lithium bisfluorosulfonyl imide obtained in the embodiments of this application can be applied to electrolytes and then to lithium-ion batteries, thereby improving the electrochemical performance of lithium-ion batteries.

Example

Hereinafter, examples of the present application will be described. The embodiments described below are illustrative and are only used to explain the present application and are not to be construed as limitations of the present application. If specific techniques or conditions are not specified in the examples, the techniques or conditions described in literature in the field or product instructions will be followed. If the manufacturer of the reagents or instruments used is not indicated, they are all conventional products that can be purchased commercially.

Example 1

The mixture is the crystallization mother liquor after multiple recrystallizations.

Example 1-1

S110 provides a mixture containing lithium bisfluorosulfonyl imide.

The mass of the mixture is 100g. Based on the total mass of the mixture, it contains sodium ions 1528.3ppm, calcium ions 9.67ppm, iron ions 7.63ppm, chromium ions 2.22ppm, zinc ions 2.02ppm, potassium ions 6.42ppm, chloride ions 75.15ppm, LiFSI: 55.3% and bisfluorosulfonimide triethylamine salt 29.6%; its color is brown-black.

S120, add organic ammonium salt to the mixture, and react to obtain an intermediate mixture.

The molar ratio of mixture and organic amine salt is 1:1.3. The organic ammonium salt is a triethylamine hydrogen fluoride salt solution. Based on the mass of the triethylamine hydrogen fluoride salt solution, the triethylamine hydrogen fluoride salt contains a fluoride ion mass content of 6.39% and a triethylamine mass content of 18.87%. The main component is three The mass content of ethylamine hydrogen fluoride salt is 25.26%.

During the reaction, an off-white solid is produced and separated into layers, with the lower layer being a brown liquid intermediate mixture. The off-white solid was filtered and dried to obtain 6.8g of lithium fluoride, with a lithium ion recovery rate of 88.9%. The mass of the intermediate mixture was 108g, the moisture content was 9%, and the anion (main component FSI) recovery rate was 95.3%.

S411, contact the intermediate mixture with activated carbon particles to adsorb and remove colored impurities in the intermediate mixture.

108g of brown liquid was decolorized using 5g of powdered activated carbon and stirred at 50°C for 3 hours. 130, in line with the internal control color index.

S421, contact the intermediate mixture with deionized water to remove metal ions in the intermediate mixture.

Recovered sodium ions 0.73ppm, calcium ions 0.78ppm, iron ions 0.42ppm, chromium ions 0.02ppm, zinc ions 0.23ppm, potassium ions 0.82ppm and chloride ions 1.33ppm, etc., reaching the intermediate internal control indicators, and finally obtained 95.3g of qualified bisfluoride Sulfonylimide triethylamine salt, the total recovery rate is 85.5%. The total recovery rate refers to the total recovery rate after three steps including reaction, dehydration, washing and other steps.

S300, react the intermediate mixture with lithium ions under alkaline conditions to obtain lithium bisfluorosulfonyl imide.

Take the bisfluorosulfonimide triethylamine salt obtained in step S421, add lithium hydroxide according to the lithium loading process, and perform alkali exchange, wherein the molar ratio of bisfluorosulfonimide triethylamine salt to lithium hydroxide is 1:1.1 . After dehydration, dichloromethane recrystallization, filtration, drying, dissolution and other steps, the dimethyl carbonate solution of LiFSI was finally obtained (moisture content 20.3ppm; density 1.2233g/cm ³ ; HF: 2.4ppm, chroma 32.3; chloride ion 1.71 ppm; calcium ions 0.34ppm; sodium ions 13.57ppm; iron ions 0.26ppm; potassium ions 1.43ppm; LiFSI: 30.25%), all of which meet the finished product specifications.

Example 1-2

Different from Example 1-1, the molar ratio of the mixture and the organic amine salt in step S120 is 1:1.1.

In step S120, the off-white solid produced was filtered and dried to obtain 6.7 g of lithium fluoride, with a lithium ion recovery rate of 87.6%. The mass of the intermediate mixture was 108g, the moisture content was 10.2%, and the anion recovery yield was 94.5%.

In step S300, a LiFSI dimethyl carbonate solution (moisture 17.5ppm; density 1.2236g/cm ³ ; HF: 15.1ppm, color 15; chloride ions 0.7387ppm; calcium ions 1.969ppm; sodium ions 65.829ppm; iron ions 0.522ppm; potassium ion 2.113ppm; LiFSI: 30.88%), all meet the finished product specifications.

Example 1-3

Different from Example 1-1, the molar ratio of the mixture and the organic amine salt in step S120 is 1:1.5.

In step S120, the off-white solid produced was filtered and dried to obtain 6.82g of lithium fluoride, with a lithium ion recovery rate of 89.0%. The mass of the intermediate mixture was 109g, the moisture content was 11.1%, and the anion recovery yield was 95.3%.

In step S300, a dimethyl carbonate solution of LiFSI (moisture content 13.3ppm; density 1.2232g/cm ³ ; HF: 19.0ppm, color 11; chloride ions 0.6323ppm; calcium ions 1.190ppm; sodium ions 51.161ppm; iron ions 0.374ppm; potassium ion 1.349ppm; LiFSI: 30.87%), all of which meet the finished product specifications.

Examples 1-4

Different from Example 1-1, the molar ratio of the mixture and the organic amine salt in step S120 is 1:1.0.

In step S120, the off-white solid produced was filtered and dried to obtain 6.3 g of lithium fluoride, with a lithium ion recovery rate of 81.2%. The mass of the intermediate mixture was 99g, the moisture content was 9.5%, and the anion recovery yield was 86.6%.

In step S300, a LiFSI dimethyl carbonate solution (moisture content 12.9 ppm; density 1.2250 g/cm ³ ; HF: 7.9 ppm, color 15; chloride ions 0.7211 ppm; calcium ions 1.105 ppm; sodium ions 56.476 ppm; iron ions 0.599ppm; potassium ion 3.279pm; LiFSI: 30.87%), all of which meet the finished product specifications.

Examples 1-5

Different from Example 1-1, the molar ratio of the mixture and the organic amine salt in step S120 is 1:5.

In step S120, the off-white solid produced is filtered and dried to obtain 7.1g of lithium fluoride. The ion recovery rate is 91.5%. The mass of the intermediate mixture was 109g, the moisture content was 10.1%, and the anion recovery yield was 95.3%.

In step S300, a dimethyl carbonate solution of LiFSI (moisture content 17.9 ppm; density 1.2235 g/cm ³ ; HF: 22.9 ppm, color 11; chloride ions 0.7774 ppm; calcium ions 1.781 ppm; sodium ions 67.169 ppm; iron ions 0.841ppm; potassium ion 2.397ppm; LiFSI: 30.79%), all of which meet the finished product specifications.

Examples 1-6

What is different from Example 1-1 is that the molar ratio of the mixture and the organic amine salt in step S120 is 1:10.

In step S120, the off-white solid produced was filtered and dried to obtain 7.0 g of lithium fluoride, with a lithium ion recovery rate of 90.2%. The mass of the intermediate mixture was 108g, the moisture content was 8.9%, and the anion recovery yield was 94.5%.

In step S300, a LiFSI dimethyl carbonate solution (moisture 9.6ppm; density 1.2241g/cm ³ ; HF: 30.9ppm, color 13; chloride ions 0.7428ppm; calcium ions 1.952ppm; sodium ions 58.922ppm; iron ions 0.438ppm; potassium ion 1.420ppm; LiFSI: 30.77%), all of which meet the finished product specifications.

Example 1-7

Different from Example 1-1, the molar ratio of bisfluorosulfonimide triethylamine salt and lithium hydroxide in step S300 is 1:1.2.

In step S300, a dimethyl carbonate solution of LiFSI (moisture 14.3ppm; density 1.2215g/cm ³ ; HF: 8.2ppm, color 20; chloride ions 1.018ppm; calcium ions 0.461ppm; sodium ions 63.687ppm; iron ions 0.229ppm; potassium ion 3.308ppm; LiFSI: 30.62%), all of which meet the finished product specifications.

Example 1-8

What is different from Example 1-1 is that in step S300, bisfluorosulfonimide triethylamine salt and The molar ratio of lithium hydroxide is 1:1.8.

In step S300, a dimethyl carbonate solution of LiFSI is obtained (moisture content 13.2ppm; density 1.2240g/cm ³ ; HF: 12.3ppm, color 19; chloride ions 0.8029ppm; calcium ions 0.542ppm; sodium ions 69.551ppm; iron ions 0.287 ppm; potassium ion 1.23ppm; LiFSI: 30.87%), all meet the finished product specifications.

Example 1-9

Different from Example 1-1, the molar ratio of bisfluorosulfonimide triethylamine salt and lithium hydroxide in step S300 is 1:1.0.

In step S300, a dimethyl carbonate solution of LiFSI (moisture 13.0ppm; density 1.2237g/cm ³ ; HF: 26.4ppm, color 19; chloride ions 0.7964ppm; calcium ions 0.970ppm; sodium ions 68.161ppm; iron ions 0.256ppm; potassium ion 4.062pm; LiFSI: 30.86%), all of which meet the finished product specifications.

Examples 1-10

Different from Example 1-1, the molar ratio of bisfluorosulfonimide triethylamine salt and lithium hydroxide in step S300 is 1:5.

In step S300, LiFSI dimethyl carbonate solution (moisture 13.2ppm; density 1.2236g/cm ³ ; HF: 8.6m, color 31; chloride ions 1.4972ppm; calcium ions 0.91ppm; sodium ions 52.94ppm; iron ions 0.373ppm; potassium ion 1.782ppm; LiFSI: 30.72%), all of which meet the finished product specifications.

Example 1-11

Different from Example 1-1, the molar ratio of bisfluorosulfonimide triethylamine salt and lithium hydroxide in step S300 is 1:10.

In step S300, a LiFSI dimethyl carbonate solution (moisture 9.8ppm; density 1.2230g/cm ³ ; HF: 11.1ppm, color 15; chloride ions 0.9278ppm; calcium ions 0.883ppm; sodium ions 47.284ppm; iron ions 0.225ppm; potassium ion 1.607ppm; LiFSI: 30.90%), all meet the finished product specifications.

Example 2

S210 provides a mixture containing lithium bisfluorosulfonyl imide.

The mixture is derived from 100g of washing waste liquid (such as washing filter residue, filter element, etc.). Based on the total mass of the mixture, the main components are lithium bisfluorosulfonimide 24.02%, sodium ions 1523.22ppm, calcium ions 314.76ppm, iron ions 3.48ppm, Lead ions are 4.73ppm and lithium ions are 8414.81ppm; their color is yellow.

S220, add organic ammonium salt to the mixture, and react to obtain an intermediate mixture.

The molar ratio of mixture and organic amine salt is 1:1.3. The organic ammonium salt is triethylamine hydrogen fluoride salt solution. Based on the mass of triethylamine hydrogen fluoride salt solution, the mass content of fluoride ions contained in triethylamine hydrogen fluoride salt is 6.39%, the mass content of triethylamine is 18.87%, and the main component is three The mass content of ethylamine hydrogen fluoride salt is 0.58%.

During the reaction, an off-white solid is produced and separated into layers, with the lower layer being a brown liquid intermediate mixture. The off-white solid was filtered and dried to obtain 2.51g of lithium fluoride, with a lithium ion recovery rate of 86.85%. The mass of the intermediate mixture was 38.5g, the moisture content was 8.9%, and the anion recovery yield was 96.7%.

S422, contact the intermediate mixture with deionized water to remove metal ions in the intermediate mixture.

Recovered sodium ions 0.84ppm, calcium ions 2.1ppm, iron ions 30.27ppm, lead ions 0.16ppm, lithium ions 1.82ppm and chloride ions 2.15ppm, etc., with a color of 103, reaching the intermediate internal control index, and finally obtained 35.1g of qualified bisfluorosulfonate. Imide triethylamine salt, the total recovery rate is 88.2%.

Take the bisfluorosulfonimide triethylamine salt obtained in step S422 and add it according to the lithium adding process. Lithium hydroxide undergoes base exchange, and the molar ratio of bisfluorosulfonimide triethylamine salt to lithium hydroxide is 1:1.5. . After dehydration, dichloromethane recrystallization, filtration, drying, dissolution and other steps, the dimethyl carbonate solution of LiFSI was finally obtained (moisture content 20.3ppm; density 1.2233g/cm ³ ; HF: 2.4ppm, chroma 32.3; chloride ion 1.71 ppm; calcium ions 0.34ppm; sodium ions 13.57ppm; iron ions 0.26ppm; potassium ions 1.43ppm; LiFSI: 30.25%), all of which meet the finished product specifications.

It can be seen from Example 1 and Example 2 that the purification method of the present application has a wide application range, and is not only suitable for high-purity recrystallization mother liquor, but also for low-purity wastewater. During the test, adjusting the molar ratio of the mixture and the organic ammonium salt can adjust the degree of purity improvement. For example, when the molar ratio of the mixture and the organic ammonium salt is 1: (1~10), the degree of reaction between the mixture and the organic ammonium salt is relatively complete. , the lithium bisfluorosulfonimide in the mixture can be converted into an organic ammonium salt of bisfluorosulfonimide. When the molar ratio of the intermediate mixture and lithium ions is 1: (1-10), the intermediate mixture can be converted into lithium bisfluorosulfonyl imide through the lithium reaction, thereby improving the purity of lithium bisfluorosulfonyl imide.

Although the application has been described with reference to preferred embodiments, various modifications may be made and equivalents may be substituted for parts thereof without departing from the scope of the application, in particular provided that no structural conflicts exist , the technical features mentioned in each embodiment can be combined in any way. The application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

A method for purifying lithium bisfluorosulfonyl imide, including:

Mixtures are provided that include lithium bisfluorosulfonyl imide;

Add organic ammonium salt to the mixture, and react to obtain an intermediate mixture;

Under alkaline conditions, the intermediate mixture is reacted with lithium ions to obtain lithium bisfluorosulfonyl imide.
The method of claim 1, further comprising:

The intermediate mixture was purified.
The method according to claim 2, wherein the step of purifying the intermediate mixture includes:

contacting the intermediate mixture with a decolorizing agent to adsorb and remove colored impurities in the intermediate mixture; and/or

The intermediate mixture is contacted with a cleaning agent to remove metal ions in the intermediate mixture.
The method of claim 3, wherein,

The decolorizing agent includes one or more of activated carbon particles, activated carbon fibers, zeolite and diatomaceous earth.
The method according to claim 3 or 4, wherein,

The cleaning agent includes one or more of water, sodium salt, potassium salt and lithium salt;

Optionally, the sodium salt includes one or more of sodium chloride, sodium sulfate and sodium carbonate;

The potassium salt includes one or more of potassium chloride, potassium sulfate and potassium sulfate;

The lithium salt includes one or more of lithium chloride, lithium sulfate and lithium carbonate.
The method according to any one of claims 1 to 5, wherein,

The organic ammonium salt includes a hydrogen fluoride salt of a tertiary amine and/or a hydrogen fluoride salt of a quaternary amine.
The method of claim 6, wherein

The hydrogen fluoride salt of the tertiary amine includes one or more of trimethylamine hydrogen fluoride salt, triethylamine hydrogen fluoride salt, tripropylamine hydrogen fluoride salt, diisopropylethylamine hydrogen fluoride salt and tributylamine hydrogen fluoride salt; optionally, The hydrogen fluoride salt of the tertiary amine includes triethylamine hydrogen fluoride salt;

The hydrogen fluoride salt of quaternary amine includes one or more of tetramethylamine hydrogen fluoride salt, tetraethylamine hydrogen fluoride salt, tetrapropylamine hydrogen fluoride salt and tetrabutylamine hydrogen fluoride salt.
The method according to any one of claims 1 to 7, wherein,

The molar ratio of the mixture and the organic ammonium salt is 1: (1-10).
The method according to any one of claims 1 to 8, wherein,

The molar ratio of the intermediate mixture and the lithium ions is 1: (1-10).
A lithium bisfluorosulfonyl imide prepared by the method according to any one of claims 1 to 9.