CN117361452A - Preparation method of high-purity bis (fluorosulfonyl) imide potassium salt - Google Patents

Preparation method of high-purity bis (fluorosulfonyl) imide potassium salt Download PDF

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CN117361452A
CN117361452A CN202311338947.9A CN202311338947A CN117361452A CN 117361452 A CN117361452 A CN 117361452A CN 202311338947 A CN202311338947 A CN 202311338947A CN 117361452 A CN117361452 A CN 117361452A
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bis
fluorosulfonyl
imide
potassium
beta
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宋蔚昌
张苗苗
张鹏
吴家靖
刘飞
张昭
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Hubei Noah New Materials Technology Co ltd
Zhejiang Nuoya Fluorine Chemical Co ltd
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Hubei Noah New Materials Technology Co ltd
Zhejiang Nuoya Fluorine Chemical Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/082—Compounds containing nitrogen and non-metals and optionally metals
    • C01B21/086—Compounds containing nitrogen and non-metals and optionally metals containing one or more sulfur atoms
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • C01P2006/82—Compositional purity water content
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The application relates to a preparation method of high-purity bis-fluorosulfonyl imide potassium salt, which comprises the following steps: reacting sulfuryl fluoride, ammonia gas and triethylamine to obtain a first reaction solution; washing the first reaction liquid with water and separating to obtain a water phase alpha and an organic phase beta; respectively adding alkali metal carbonate aqueous solution into aqueous phase alpha and organic phase beta, and separating organic phase beta to obtain aqueous phase alpha 1 Beta with organic phase 1 Aqueous phase alpha 1 Separating to obtain water phase alpha 2 Beta with organic phase 2 The method comprises the steps of carrying out a first treatment on the surface of the Combining aqueous phases alpha 1 With aqueous phase alpha 2 Obtaining aqueous phase alpha 3 Continuously adding alkali metal carbonate aqueous solution, separating to obtain aqueous phase alpha 3 And organic phase beta 3 The method comprises the steps of carrying out a first treatment on the surface of the Combining the organic phases beta 1 、β 2 And beta 3 Obtaining bis (fluorosulfonyl) imide triethylamine salt, reacting the bis (fluorosulfonyl) imide triethylamine salt with potassium hydroxide aqueous solution to obtain a second reaction solution, and purifying to obtain the bis (fluorosulfonyl) imide potassium salt pure product. The method can safely and efficiently improve the purity of the prepared difluoro sulfonimide potassium saltAnd the yield, thereby improving the purity and the yield of the lithium bis (fluorosulfonyl) imide.

Description

Preparation method of high-purity bis (fluorosulfonyl) imide potassium salt
Technical Field
The application relates to the field of preparation processes of bis (fluorosulfonyl) imide potassium salt, in particular to a preparation method of high-purity bis (fluorosulfonyl) imide potassium salt.
Background
Along with the popularization of green low-carbon requirements and the national importance and encouragement of new energy development, the lithium battery is widely applied to the fields of new energy automobiles, digital products, energy storage and the like by virtue of the characteristics of high working voltage, high energy density, no memory effect and the like. Among them, lithium bis (fluorosulfonyl) imide (LiFSI) is considered to be the electrolyte lithium salt that has the most potential to replace lithium hexafluorophosphate at present due to its excellent properties.
The traditional route is to synthesize LiFSI first, then obtain the target product after purification and drying, but because LiFSI is sensitive to moisture, the heating process is easy to decompose, thus greatly limiting the large-scale application of LiFSI and lithium ion batteries using the same. At present, liFSI with low specification can only be used as an additive in electrolyte, and certain defects of lithium hexafluorophosphate as main salt are overcome. If LiFSI is to be used as the main salt of lithium battery electrolyte to exert its excellent electrochemical properties, it is necessary to use a high purity product. Therefore, the preparation of LiFSI with the content of more than 99.99 percent, the water content of less than 20ppm and the content of anion/cation impurities is a technical problem to be broken through.
The potassium bis (fluorosulfonyl) imide (KFSI) is stable in air at room temperature, does not contain bound water, can be used for preparing anhydrous potassium salt through neutralization, and can be used for preparing a series of alkali metal bis (fluorosulfonyl) imide salts, such as lithium bis (fluorosulfonyl) imide, sodium bis (fluorosulfonyl) imide and the like. Therefore, the development of a new process for directly reacting pure KFSI as an intermediate to obtain high-quality LiFSI has important social significance and economic value.
The current preparation technology of potassium bis-fluorosulfonyl imide can be divided into three routes:
the first is the production of potassium difluorosulfimide by reacting bischlorosulfimide with a fluorinating agent such as potassium fluoride, zinc fluoride, or hydrogen fluoride. The patent CN114436226A firstly prepares dichlorsulfimide by sulfamic acid, chlorosulfonic acid and thionyl chloride, and the dichlorsulfimide reacts with potassium fluoride in dichloroethane to obtain potassium difluoro sulfimide; the method can generate a large amount of acid gases SO2 and HCl in the first step of reaction, and the second step of reaction needs excessive anhydrous potassium fluoride, SO that the cost is high and the purification is complex.
The second route is that the difluoro-sulfonyl imide reacts with alkaline potassium salt such as potassium hydroxide or potassium carbonate to generate difluoro-sulfonyl imide potassium. Patent CN106006586a proposes that firstly bis (chlorosulfonyl) imide is obtained by reacting chlorosulfonic acid with chlorosulfonyl isocyanate, then bis (fluorosulfonyl) imide is obtained by reacting with hydrogen fluoride, and finally bis (fluorosulfonyl) imide is reacted with an alkaline potassium compound to obtain bis (fluorosulfonyl) imide potassium salt. SO is avoided by chlorosulfonyl isocyanate method 2 And HCl and other gases, but the yield of chlorosulfonyl isocyanate is limited, so that the raw material cost is high, and the industrial mass production advantage is not achieved.
The third route is that the organic alkali salt of the difluoro-sulfonyl imide reacts with a potassium source through double decomposition reaction to obtain the difluoro-sulfonyl imide potassium salt. Patent CN116374966a adopts a two-step process: the sulfuryl fluoride reacts with ammonium salt to obtain difluoro sulfonimide organic ammonium salt, and then the reaction liquid containing the difluoro sulfonimide organic ammonium salt reacts with potassium reagent through double decomposition reaction to obtain difluoro sulfonimide potassium. However, this method has problems: carbon dioxide gas is generated in the double decomposition reaction process, and the principle of atom economy is not met; the use of ammonium fluoride, ammonium chloride, ammonium bromide, ammonium bisulfate, etc. as the ammonium salt introduces Cl - 、SO 4 2- And the like, thereby reducing the purity of the product.
Patent WO2023142028A1 reports a method for recovering raw and auxiliary materials in the production of lithium bis-fluorosulfonyl imide. The patent proposes that a product mixture produced by the reaction of sulfuryl fluoride, triethylamine and ammonia is firstly separated into an oil phase containing difluorosulfonimide triethylamine salt, an aqueous phase containing triethylamine hydrogen fluoride salt and impurity ions, then the oil phase containing difluorosulfonimide triethylamine salt is reacted with a lithium hydroxide aqueous solution to obtain a crude product of difluorosulfonimide lithium, and the aqueous phase containing triethylamine hydrogen fluoride salt and impurity ions is reacted with alkali metal hydroxide.
The method can realize that the reaction solution containing lithium difluorosulfimide and byproduct triethylamine hydrogen fluoride salt are converted into alkali metal fluoride, and the utilization of byproduct triethylamine hydrogen fluoride salt and the recovery of triethylamine are realized, but the purification and recovery of the lithium difluorosulfimide triethylamine salt are not involved, and the following problems are caused: 1) Impurities such as triethylamine hydrogen fluoride salt still exist in the oil phase, the impurities react with lithium hydroxide aqueous solution directly to cause the increase of the lithium hydroxide dosage, and high-quality lithium bis (fluorosulfonyl) imide cannot be obtained after the reaction in the aqueous solution; 2) The aqueous phase still has residual bis (fluorosulfonyl) imide triethylamine salt, resulting in a lower yield of bis (fluorosulfonyl) imide triethylamine salt and a lower yield of lithium bis (fluorosulfonyl) imide.
Disclosure of Invention
In order to safely and efficiently improve the purity and the yield of the prepared bis (fluorosulfonyl) imide potassium salt, thereby improving the purity and the yield of the bis (fluorosulfonyl) imide lithium, the application provides a preparation method of the bis (fluorosulfonyl) imide potassium salt with high purity.
The preparation method of the high-purity difluoro sulfimide potassium salt adopts the following technical scheme:
the preparation method of the high-purity bis-fluorosulfonyl imide potassium salt comprises the following steps:
under the protection of inert gas, taking sulfuryl fluoride, ammonia gas and triethylamine as raw materials, and performing a first reaction in an organic solvent to obtain a first reaction solution containing difluoro sulfonimide triethylamine salt;
filtering, decompressing and concentrating the first reaction liquid, and separating liquid after washing to obtain a water phase alpha and an organic phase beta;
respectively adding alkali metal carbonate aqueous solution into aqueous phase alpha and organic phase beta, and separating the organic phase beta to obtain aqueous phase alpha 1 Beta with organic phase 1 The aqueous phase alpha 1 Separating to obtain water phase alpha 2 Beta with organic phase 2 ；
Combining the aqueous phases alpha 1 With aqueous phase alpha 2 Obtaining aqueous phase alpha 3 Continuously adding alkali metal carbonate aqueous solution, separating to obtain aqueous phase alpha 3 And organic phase beta 3 ；
Combining the organic phases beta 1 、β 2 And beta 3 Obtaining organic phase beta 4 Namely, bis (fluorosulfonyl) imide triethylamine salt, carrying out a second reaction on the bis (fluorosulfonyl) imide triethylamine salt obtained by the method and potassium hydroxide aqueous solution to obtain a second reaction solution containing bis (fluorosulfonyl) imide potassium;
and purifying the second reaction solution to obtain the pure potassium difluorosulfimide salt.
By adopting the technical scheme, under the protection of inert gas, triethylamine and an organic solvent are mixed and then added into a reaction kettle, sulfuryl fluoride is then introduced, ammonia gas is then introduced for reaction, a first reaction liquid containing difluoro sulfonimide triethylamine salt is obtained, solid insoluble matters in the first reaction liquid are removed through filtration, and the organic solvent and the triethylamine are removed through reduced pressure concentration. And separating the liquid after washing to obtain a water phase alpha and an organic phase beta.
The aqueous phase and the organic phase are washed and separated by adopting alkali metal carbonate aqueous solution for multiple times, so that the yield and purity of the bis-fluorosulfonyl imide triethylamine salt can be improved. This is due to the alkaline size: difluorosulfonyl triethylamine salt > alkali metal carbonate > triethylamine hydrofluoric acid salt, and the alkali metal carbonate can neutralize and recycle the triethylamine hydrofluoric acid salt. Alkali metal carbonate is respectively added into the aqueous phase alpha and the organic phase beta, triethylamine hydrofluoric acid salt in the aqueous phase alpha and the organic phase beta is neutralized and recovered, and the aqueous phase alpha is obtained by separating liquid 1 Beta with organic phase 1 The method comprises the steps of carrying out a first treatment on the surface of the Then in the water phase alpha 1 Adding alkali carbonate to neutralize and recover triethylamine hydrofluoric acid salt, and separating to obtain water phase alpha 2 Beta with organic phase 2 The method comprises the steps of carrying out a first treatment on the surface of the Combining aqueous phase alpha 1 And aqueous phase alpha 2 Obtaining aqueous phase alpha 3 Repeating the above operation to obtain water phase alpha 4 And organic phase beta 3 。
Organic phase beta after washing and liquid separation 1 Triethylamine hydrofluoride salt in (C)Is substantially removed, and the organic phase beta 2 Beta of organic phase 3 All are bis-fluorosulfonyl triethylamine salts recovered from aqueous phase, and the organic phase beta is combined 1 、β 2 、β 3 The relatively pure bis (fluorosulfonyl) imide triethylamine salt can be obtained, and the residual bis (fluorosulfonyl) imide triethylamine salt in the water phase can be recovered, so that the purity of the prepared bis (fluorosulfonyl) imide potassium salt is improved, and the yield is also improved. And the method can also neutralize and recycle the residual triethylamine hydrofluoric acid salt in the organic phase so as to improve the utilization and recovery rate of the byproduct triethylamine hydrofluoric acid salt.
The purity and the yield of the potassium difluorosulfimide are improved, so that the potassium difluorosulfimide can be used as an intermediate to directly react to obtain high-quality lithium difluorosulfimide, and the purity and the yield of the lithium difluorosulfimide are improved.
In addition, the raw materials used in the preparation method, such as sulfuryl fluoride, ammonia, organic solvent, potassium hydroxide and the like, are cheap and easy to obtain, acid gases such as sulfur dioxide, hydrogen chloride and the like are not generated in the reaction process, hydrogen fluoride is not needed, the environment friendliness is stronger, the requirements on equipment are not high, the production cost is reduced, and the preparation method is suitable for large-scale production.
Optionally, the molar ratio of ammonia gas, sulfuryl fluoride and triethylamine is 1.0: (2.0-2.2): (3.0-3.5).
By adopting the technical scheme, sulfuryl fluoride reacts with ammonia gas to generate difluoro-sulfonyl imide and hydrogen fluoride, and triethylamine reacts with the difluoro-sulfonyl imide to generate difluoro-sulfonyl-imide triethylamine salt and triethylamine hydrogen fluoride salt. However, excessive triethylamine promotes hydrolysis of sulfuryl fluoride to form by-products such as fluorosulfonic acid. And when the molar ratio of ammonia, sulfuryl fluoride and triethylamine is 1.0: (2.0-2.2): (3.0-3.5), the possibility of by-product generation is small, and the yield of the target product is high, namely the yield of the bis-fluorosulfonyl imide triethylamine salt is good.
Optionally, the ammonia gas is introduced at a rate of 0.3-1.0g/min.
By adopting the technical scheme, the ammonia gas inlet rate has a great influence on the intensity of the reaction. When the ammonia gas is passed through quickly, the reaction temperature is fluctuated and is easy to run away, so that a certain risk is brought; and when the ammonia gas passes slowly, the reaction time is longer, which is unfavorable for industrialized amplified production. When the ammonia gas introducing rate is controlled to be 0.3-1.0g/min, the reaction temperature can be well controlled in a set temperature range, the reaction pressure in the whole process is less than or equal to 0.5MPa, and the reaction is safe and efficient.
Optionally, the reaction temperature of the first reaction is-10-25 ℃ and the reaction time is 2-10h.
By adopting the technical scheme, the reaction rate and the reaction degree of ammonia, sulfuryl fluoride and triethylamine can be more suitable due to the reaction temperature and the reaction time.
Optionally, the temperature of the reduced pressure concentration is 50-90 ℃, and the concentrated solution is obtained after the reduced pressure concentration.
Optionally, the water in the water washing step is deionized water, and the dosage of the deionized water is 50% -200% of the weight of the concentrated solution.
Optionally, the alkali metal carbonate is potassium carbonate.
Optionally, the concentration of the alkali metal carbonate aqueous solution is 10-50wt%, and the amount of the alkali metal carbonate aqueous solution is 20-50% of the weight of each grade of water phase or organic phase.
Optionally, the molar ratio of the bis-fluorosulfonyl imide triethylamine salt to potassium hydroxide is 1: (1-1.01).
By adopting the technical scheme, the molar ratio of the bis-fluorosulfonyl imide triethylamine salt to potassium hydroxide can enable the reaction degree of the second reaction to be more sufficient, and the yield of the final bis-fluorosulfonyl imide potassium salt is higher.
Optionally, the concentration of the aqueous potassium hydroxide solution is 5-50wt%.
By adopting the technical scheme, the acid-base neutralization reaction between the difluoro sulfonimide triethylamine salt and potassium hydroxide is particularly important to select a proper reaction solvent. If acetonitrile, acetone and other organic solvents are used for reaction, a heterogeneous system is easy to form, and the reaction yield is reduced. For example, acetonitrile is used as a reaction solvent, and although the solubility of raw materials of the bis-fluorosulfonyl imide triethylamine salt and a product of the bis-fluorosulfonyl imide potassium in acetonitrile is high, inorganic base KOH is hardly dissolved with acetonitrile to form a heterogeneous reaction system, and the reaction efficiency is reduced. The water is used as a reaction solvent, so that the dissolution of raw materials can be increased, the homogeneous reaction is promoted, and the reaction efficiency is improved; and the potassium bis (fluorosulfonyl) imide does not contain bound water, so that the subsequent purification is not affected.
Optionally, the reaction temperature of the second reaction is 20-40 ℃ and the reaction time is 1-3h.
By adopting the technical scheme, the reaction rate and the reaction degree of the bis-fluorosulfonyl imide triethylamine salt and potassium hydroxide can be more suitable due to the adoption of the reaction temperature and the reaction time.
Optionally, the purification treatment comprises the steps of:
filtering the second reaction liquid, concentrating under reduced pressure, dissolving with good solvent, and filtering; concentrating under reduced pressure for the second time, recrystallizing the poor solvent, washing, and drying in vacuum to obtain the pure potassium difluorosulfimide salt.
By adopting the technical scheme, solid insoluble substances in the second reaction liquid are removed by filtration in the purification treatment, and then water and triethylamine are removed by reduced pressure concentration, namely reduced pressure distillation. By precisely controlling the residual quantity of the good solvent; in the process of recrystallization of the poor solvent, the high-yield and high-purity bis (fluorosulfonyl) imide potassium salt can be obtained by precisely controlling the addition amount of the poor solvent and the temperature of a system during addition, and compared with a technical route with lower yield caused by improving the purity of a product by a plurality of recrystallization means, the technical route provided by the invention has great advantages.
Optionally, the good solvent is at least one selected from ethanol, isopropanol, acetonitrile, ethylene glycol dimethyl ether, methyl tert-butyl ether and ethyl acetate.
Alternatively, the amount of good solvent is 0.5-3 times the weight of theoretical potassium difluorosulfimide.
Optionally, the poor solvent is selected from at least one of dichloromethane, dichloroethane, chloroform and toluene.
Optionally, the amount of the poor solvent is 1-10 times of the theoretical potassium bis-fluorosulfonyl imide.
Optionally, the temperature of the system is controlled between 40 ℃ and 60 ℃ when the poor solvent is added.
Optionally, the temperature of the reduced pressure concentration in the purification treatment is 50-90 ℃.
Optionally, the solid content of the obtained concentrated solution after the decompression concentration in the purification treatment is controlled to be 90% -100%.
Optionally, the detergent used in the washing treatment is at least one of toluene, xylene, dichloromethane, dichloroethane and chloroform.
Alternatively, the amount of the detergent used in the washing treatment is 2 to 10 times by weight of the theoretical potassium difluorosulfimide salt.
Optionally, the temperature of the vacuum drying is 30-80 ℃.
The application provides a high-purity difluoro sulfimide potassium salt adopts following technical scheme:
the high-purity difluoro sulfonimide potassium salt comprises purity not less than 99.95%, water content not more than 20ppm, chloride not more than 5ppm, free acid not more than 30ppm, sodium ion not more than 5ppm and insoluble matter not more than 50ppm.
The application of the high-purity difluoro sulfimide potassium salt provided by the application adopts the following technical scheme:
use of a high purity potassium bis (fluorosulfonyl) imide, which can be directly used for synthesizing high quality lithium bis (fluorosulfonyl) imide.
In summary, the present application includes at least one of the following beneficial technical effects:
1. the process is safe and reliable by controlling the reaction conditions, and the aqueous phase and the organic phase are washed and separated by adopting alkali metal carbonate aqueous solution for multiple times, so that on one hand, the bis-fluorosulfonyl imide triethylamine salt remained in the aqueous phase can be recovered, and on the other hand, the triethylamine hydrofluoric acid salt remained in the organic phase can be neutralized and does not react with the bis-fluorosulfonyl triethylamine salt, so that the yield and purity of the bis-fluorosulfonyl imide triethylamine salt are higher;
2. the bis (fluorosulfonyl) imide triethylamine salt reacts with potassium hydroxide aqueous solution, and the bis (fluorosulfonyl) imide potassium salt with high yield and high purity is obtained through further purification treatment, so that the bis (fluorosulfonyl) imide lithium can be directly used for synthesizing to obtain high-quality bis (fluorosulfonyl) imide lithium;
3. the raw materials of sulfuryl fluoride, ammonia, triethylamine, potassium hydroxide and the like are cheap and easy to obtain, acid gases such as sulfur dioxide, hydrogen chloride and the like are not generated in the reaction process, hydrogen fluoride is not needed, the environment friendliness is stronger, the requirements on equipment are low, the production cost is reduced, and the method is suitable for large-scale production.
Drawings
FIG. 1 is a solution of bis-fluorosulfonyl imide triethylamine salt in an embodiment of the present invention 19 F NMR nuclear magnetic spectrum.
FIG. 2 is a pure bis-fluorosulfonyl imide triethylamine salt in the examples of the present invention 19 F NMR nuclear magnetic spectrum.
FIG. 3 is a potassium salt of bis-fluorosulfonyl imide in an embodiment of the present invention 19 F NMR nuclear magnetic spectrum.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the following examples, which are to be construed as merely illustrative and not limitative of the scope of the invention, but are not intended to limit the scope of the invention to the specific conditions set forth in the examples, either as conventional or manufacturer-suggested, nor are reagents or apparatus employed to identify manufacturers as conventional products available for commercial purchase.
The technical scheme of the invention is as follows:
the preparation method of the high-purity bis-fluorosulfonyl imide potassium salt specifically comprises the following steps:
under the protection of inert gas, taking sulfuryl fluoride, ammonia gas and triethylamine as raw materials, and reacting in acetonitrile, wherein the specific reaction formula is shown in the following formula (1), so as to obtain a first reaction solution containing difluoro sulfonimide triethylamine salt; wherein the reaction temperature is-10-25 ℃, the reaction time is 2-10h, preferably-5-5 ℃, and the reaction time is 4-8h.
Filtering the first reaction solution and reducingConcentrating under pressure, washing with water, and separating to obtain water phase alpha and organic phase beta;
wherein the temperature of the reduced pressure concentration is 50-90 ℃, and the concentrated solution is obtained after the reduced pressure concentration; the water for washing is deionized water, and the dosage of the deionized water is 50-200% of the weight of the concentrated solution.
Respectively adding alkali metal carbonate aqueous solution into aqueous phase alpha and organic phase beta, and separating organic phase beta to obtain aqueous phase alpha 1 Beta with organic phase 1 Aqueous phase alpha 1 Separating to obtain water phase alpha 2 Beta with organic phase 2 The method comprises the steps of carrying out a first treatment on the surface of the Combining aqueous phases alpha 1 With aqueous phase alpha 2 Obtaining aqueous phase alpha 3 ，
Continuously adding alkali metal carbonate aqueous solution, separating to obtain aqueous phase alpha 4 And organic phase beta 3 ；
Wherein the alkali metal carbonate aqueous solution is potassium carbonate aqueous solution, the concentration of the alkali metal carbonate aqueous solution is 10-50wt%, preferably, the concentration of the alkali metal carbonate aqueous solution is 15-30wt%; the amount of alkali metal carbonate aqueous solution is 20-50% by weight of each stage of aqueous phase or organic phase.
Combining the organic phases beta 1 、β 2 And beta 3 Obtaining organic phase beta 4 Namely, the bis (fluorosulfonyl) imide triethylamine salt, and the obtained bis (fluorosulfonyl) imide triethylamine salt reacts with potassium hydroxide aqueous solution, the specific reaction formula is shown in the following formula (2), and a second reaction solution containing bis (fluorosulfonyl) imide potassium is obtained; wherein the concentration of the potassium hydroxide aqueous solution is 5-50wt%; wherein the reaction temperature is 20-40 ℃ and the reaction time is 1-3h.
Filtering the second reaction liquid, concentrating under reduced pressure, dissolving with good solvent, and filtering; concentrating under reduced pressure for the second time, recrystallizing the poor solvent, washing, and drying to obtain a pure potassium difluorosulfimide salt product;
wherein the temperature range of the reduced pressure concentration is 50-90 ℃, and the solid content of the obtained concentrated solution is controlled to be 90-100% after the reduced pressure concentration; the good solvent is at least one of ethanol, isopropanol, acetonitrile, ethylene glycol dimethyl ether, methyl tertiary butyl ether and ethyl acetate; the amount of the good solvent is 0.5-3 times of the weight of the theoretical potassium bis-fluorosulfonyl imide, preferably, the amount of the good solvent is 1-2 times of the weight of the theoretical potassium bis-fluorosulfonyl imide;
wherein the poor solvent is at least one of dichloromethane, dichloroethane, chloroform and toluene, and the temperature of the system is controlled at 40-60 ℃ when the poor solvent is added; the amount of the poor solvent is 1 to 10 times, preferably 3 to 5 times, the weight of the theoretical potassium bis-fluorosulfonyl imide;
wherein the washing agent used in the washing treatment is at least one of toluene, xylene, methylene dichloride, dichloroethane and chloroform; the amount of the detergent used in the washing treatment is 2 to 10 times by weight of the theoretical potassium salt of the bisfluorosulfonyl imide, preferably, the amount of the detergent used in the washing treatment is 3 to 6 times by weight of the theoretical potassium salt of the bisfluorosulfonyl imide;
wherein the temperature of vacuum drying is 30-80deg.C, preferably 40-60deg.C.
1. Examples
Example 1:
step 1:
under the protection of nitrogen, 600g of acetonitrile and 618g (6.11 mol) of triethylamine are mixed and added into a 2L reaction kettle, stirring is started, the temperature of the reaction kettle is controlled to be 0-5 ℃, 418.45g (4.10 mol) of sulfuryl fluoride is added into the reaction kettle, 34.06g (2.00 mol) of ammonia gas is added into the reaction kettle through a mass flowmeter, the ammonia gas charging rate is 0.7g/min, and the reaction is continued for 3h after the ammonia gas is charged; the molar ratio of ammonia, sulfuryl fluoride and triethylamine is about 1:2:3.
and after the reaction is finished, discharging to obtain a first reaction solution containing the difluoro sulfonimide triethylamine salt, and filtering the first reaction solution to remove solid insoluble matters to obtain the difluoro sulfonimide triethylamine salt solution.
Step 2:
concentrating the difluoro sulfonimide triethylamine salt solution under reduced pressure, transferring the concentrated solution to a 2L separating funnel, adding deionized water with half mass of the concentrated solution, oscillating, standing and separating to obtain 942g of water phase alpha and 648g of organic phase beta.
130g of 25% potassium carbonate aqueous solution (20% of the weight of the organic phase beta) is added into the organic phase beta, the mixture is oscillated and kept stand for separation to obtain aqueous phase alpha 1 And an organic phase β1; 188g of 25% potassium carbonate aqueous solution (20% of the weight of the aqueous phase alpha) is added into the aqueous phase alpha, the mixture is oscillated and kept stand for separation to obtain the aqueous phase alpha 2 Beta with organic phase 2 ；
Combining aqueous phases alpha 1 With aqueous phase alpha 2 1440g of aqueous phase alpha are obtained 3 288g (aqueous phase alpha) of 25% aqueous potassium carbonate solution (aqueous phase alpha) 3 20% of the weight), oscillating, standing and separating to obtain water phase alpha 4 Beta with organic phase 3 ；
Combining the organic phases beta 1 、β 2 And beta 3 Obtaining organic phase beta 4 I.e., bis-fluorosulfonyl imide triethylamine salt.
Step 3:
transferring the obtained difluoro sulfonimide triethylamine salt to a 2L three-neck flask, dropwise adding a 20% potassium hydroxide aqueous solution (the molar ratio of the difluoro sulfonimide triethylamine salt to the potassium hydroxide is 1:1) at room temperature, continuously stirring for 0.5h after the dropwise addition is completed for 2h, and obtaining a second reaction solution containing the difluoro sulfonimide potassium.
Filtering the second reaction solution to remove insoluble substances, concentrating under reduced pressure to obtain a potassium bis (fluorosulfonyl) imide crude product, adding acetonitrile with the same mass as that of theoretical potassium bis (fluorosulfonyl) imide, stirring to fully dissolve, filtering, and concentrating under reduced pressure for the second time until the solid content of the solution is 95%;
when the concentrated solution is cooled to 50 ℃, dropwise adding dichloromethane with the mass which is 2 times that of theoretical potassium bis (fluorosulfonyl) imide into the concentrated solution under stirring, naturally cooling to room temperature, gradually separating out potassium bis (fluorosulfonyl) imide crystals in the process, crystallizing for 2 hours at room temperature, and filtering to obtain potassium bis (fluorosulfonyl) imide solid;
adding dichloromethane with the mass 3 times of that of theoretical potassium bis (fluorosulfonyl) imide into the potassium bis (fluorosulfonyl) imide solid, stirring for 30min, repeating the washing operation for 1-2 times to obtain a potassium bis (fluorosulfonyl) imide wet product, and vacuum drying the wet product at 60 ℃ for 12h to obtain a white solid product.
Example 2:
a method for preparing high-purity bis-fluorosulfonyl imide potassium salt, which is different from example 1 in that: in the step 1, the temperature of the reaction kettle is controlled to be-5-0 ℃.
Example 3:
a method for preparing high-purity bis-fluorosulfonyl imide potassium salt, which is different from example 1 in that: 600g of acetonitrile and 708g (7.00 mol) of triethylamine are mixed, added into a 2L reaction kettle, stirring is started, the temperature of the reaction kettle is controlled to be 0-5 ℃, 449.06g (4.40 mol) of sulfuryl fluoride is added into the reaction kettle, 34.06g (2.00 mol) of ammonia gas is added into the reaction kettle through a mass flowmeter, and the reaction is continued for 3 hours after the ammonia gas is completely introduced; the molar ratio of ammonia, sulfuryl fluoride and triethylamine is about 1:2.2:3.5.
example 4:
a method for preparing high-purity bis-fluorosulfonyl imide potassium salt, which is different from example 1 in that: 600g of acetonitrile, 647.62g (6.40 mol) of triethylamine are mixed, added into a 2L reaction kettle, stirring is started, the temperature of the reaction kettle is controlled to be 0-5 ℃, 428.65g (4.20 mol) of sulfuryl fluoride is added into the reaction kettle, 34.06g (2.00 mol) of ammonia gas is added into the reaction kettle through a mass flowmeter, and the reaction is continued for 3 hours after the ammonia gas is completely introduced; the molar ratio of ammonia, sulfuryl fluoride and triethylamine is about 1:2.1:3.2.
examples 5 to 6:
a process for preparing a high purity bis-fluorosulfonyl imide potassium salt, which differs from example 1 in that it is shown in Table 1.
Table 1:
example 7:
a method for preparing high-purity bis-fluorosulfonyl imide potassium salt, which is different from example 1 in that: the 25% aqueous potassium carbonate solution was replaced with a 15% aqueous potassium carbonate solution.
Example 8:
a method for preparing high-purity bis-fluorosulfonyl imide potassium salt, which is different from example 1 in that: the 25% aqueous potassium carbonate solution was replaced with a 30% aqueous potassium carbonate solution.
Example 9:
a method for preparing high-purity bis-fluorosulfonyl imide potassium salt, which is different from example 1 in that: in the step 3, when the concentrated solution is cooled to 50 ℃, dichloromethane which is 5 times of the theoretical potassium bis (fluorosulfonyl) imide in mass is added dropwise into the concentrated solution under stirring.
Example 10:
a method for preparing high-purity bis-fluorosulfonyl imide potassium salt, which is different from example 1 in that: in the step 3, insoluble substances are removed by filtration, then the crude product of the potassium bis-fluorosulfonyl imide is obtained by vacuum concentration, acetonitrile with the same mass as the theoretical potassium bis-fluorosulfonyl imide is added, stirring is carried out to fully dissolve, then filtration is carried out, and the solid content of the solution is 90% by vacuum concentration for the second time.
Example 11:
a method for preparing high-purity bis-fluorosulfonyl imide potassium salt, which is different from example 1 in that: in the step 3, insoluble substances are removed by filtration, then the crude product of the potassium bis-fluorosulfonyl imide is obtained by vacuum concentration, acetonitrile with the same mass as the theoretical potassium bis-fluorosulfonyl imide is added, stirring is carried out to fully dissolve, then filtration is carried out, and the solid content of the solution is 100% by vacuum concentration for the second time.
Example 12:
a method for preparing high-purity bis-fluorosulfonyl imide potassium salt, which is different from example 1 in that: the ammonia gas was introduced at a rate of 0.3g/min.
Example 13:
a method for preparing high-purity bis-fluorosulfonyl imide potassium salt, which is different from example 1 in that: the ammonia gas was introduced at a rate of 1.0g/min.
2. Comparative example
Comparative example 1:
the difference from example 1 is that: and (3) directly transferring the organic phase beta in the step (2) to a three-neck flask, dropwise adding a 20% potassium hydroxide aqueous solution (the molar ratio of the bis-fluorosulfonyl imide triethylamine salt to potassium hydroxide is 1:1) at room temperature, continuously stirring for 0.5h after the dropwise addition is completed, and ending the reaction to obtain a second reaction solution containing the bis-fluorosulfonyl imide potassium.
Comparative example 2:
the difference from example 1 is that: under the protection of nitrogen, 74.4g of ammonium fluoride is added into a 2L high-pressure reaction kettle, the temperature is controlled to 10 ℃, 480g of acetonitrile is stirred for 0.5 hour, 408g of sulfuryl fluoride gas is slowly introduced at the temperature of 10 ℃, the temperature is continuously kept at 10 ℃ for 4 hours, and the reaction is ended; the reaction solution is distilled under reduced pressure to recover the reaction solvent, and the concentrated solution is washed with water to obtain an organic phase, namely bis (fluorosulfonyl) imide triethylamine salt;
under the protection of nitrogen, adding the obtained bis (fluorosulfonyl) imide triethylamine salt into a three-port reaction bottle, then adding 25% potassium hydroxide aqueous solution (the molar ratio of the bis (fluorosulfonyl) imide triethylamine salt to potassium hydroxide is 1:1), stirring and heating for reflux until no carbon dioxide gas is generated. Filtering insoluble inorganic matters, and distilling the reaction solution under reduced pressure to recover the reaction solvent to obtain the potassium bis-fluorosulfonyl imide solid.
3. Performance test
1) Difluorosulfonyl imide triethylamine salt solutions prepared in examples 1 to 13 and comparative examples 1 to 2 and organic phase beta were subjected to a nuclear magnetic resonance spectrometer 4 And solid products were tested, wherein the test results of example 1 are shown in FIGS. 1-2;
2) The yields of potassium difluorosulfimide of examples 1 to 13 and comparative examples 1 to 2 were calculated, yield (%) = actual product mass/theoretical product mass x 100%;
3) The purity of potassium bis (fluorosulfonyl) imide of examples 1 to 13 and comparative examples 1 to 2 was measured using a liquid chromatograph;
4) Anion detection method: the potassium difluorosulfimide of examples 1-13 and comparative examples 1-2 was detected by ion chromatograph in ppm;
5) The moisture detection method comprises the following steps: the potassium difluorosulfimide of examples 1-14, comparative examples 1-3 were tested using a meltrehler-tolidocompany karl fischer moisture tester in ppm;
6) Free acid detection method: the potassium difluorosulfimide of examples 1-13 and comparative examples 1-2 was titrated with potassium hydroxide-ethanol standard solution using potentiometric titration;
7) The method for testing the content of the trace metal elements comprises the following steps: the content of each trace metal element in ppm in potassium bis-fluorosulfonyl imide of examples 1 to 13 and comparative examples 1 to 2 was measured using an inductively coupled plasma emission spectrometer (ICP-OES).
8) DMC insoluble content detection method: the sample was dissolved in dimethyl carbonate (DMC), filtered using a membrane filter, and dried at 105.+ -. 2 ℃ until the mass was constant.
The above test results are shown in Table 2.
Table 2:
as can be seen from the combination of examples 1-13, comparative examples 1-2 and FIGS. 1-3, FIG. 1 shows that the bis-fluorosulfonyl imide triethylamine salt solution contains a small amount of triethylamine hydrofluoric acid salt in addition to bis-fluorosulfonyl imide triethylamine salt; as can be seen by comparing FIG. 2 with FIG. 1, the organic phase beta is obtained after decompression and compression and fractional washing and liquid separation of the alkali metal carbonate aqueous solution 4 The triethylamine hydrofluoride salt in the solution is basically removed, and the organic phase beta is 4 Is relatively pure bis-fluorosulfonyl imide triethylamine salt. Finally, as can be seen from fig. 3, the white solid product finally obtained is the relatively pure potassium bis-fluorosulfonyl imide. Other examples and comparative examples 19 The F NMR nuclear magnetic pattern situation is substantially identical to example 1.
As is clear from the combination of examples 1-2 and Table 2, the first reaction temperatures of examples 1-2 were different, and the yields of the potassium difluorosulfimide salts produced in examples 1-2 were not less than 87%, the purities were not less than 99.95%, the water content was not more than 20ppm, the chloride content was not more than 5ppm, the free acid content was not more than 30ppm, the sodium ion content was not more than 5ppm, and the insoluble matter content was not more than 50ppm. As is clear from the above, the yield and purity of the potassium difluorosulfimide salt prepared in the temperature range of-5-5 ℃ in the first reaction are high, the content of moisture, free acid, insoluble substances and other impurity ions is extremely low, and the potassium difluorosulfimide salt can be directly used for synthesizing high-quality lithium difluorosulfimide.
As can be seen by combining the example 1, the examples 3-4 and the Table 2, the molar ratios of ammonia, sulfuryl fluoride and triethylamine in the example 1 and the examples 3-4 are different, the yields of the potassium difluorosulfimide salt prepared in the examples 3-4 are more than or equal to 87%, the purities are more than or equal to 99.95%, the water content is less than or equal to 20ppm, the chloride content is less than or equal to 5ppm, the free acid content is less than or equal to 30ppm, the sodium ion content is less than or equal to 5ppm, and the insoluble matters content is less than or equal to 50ppm; and example 4 is better in yield and purity than examples 1 and 3, and lower in moisture, free acid, insoluble and other impurity ions.
From the above, the molar ratio of ammonia, sulfuryl fluoride and triethylamine was 1.0: (2.0-2.2): (3.0-3.5) can react to prepare high-purity high-quality bis (fluorosulfonyl) imide potassium salt, and the molar ratio of ammonia, sulfuryl fluoride and triethylamine is 1:2.1:3.2, the yield, purity and quality of the prepared difluoro sulfonimide potassium salt are better.
As can be seen from the combination of examples 1, examples 5 to 6 and Table 2, the proportion of the alkali metal carbonate aqueous solution added to each of the aqueous phase or the organic phase of examples 5 to 6 is different from that of example 1, and the yields of the potassium difluorosulfimide salt prepared in examples 5 to 6 are not less than 87%, the purities are not less than 99.95%, the water content is not more than 20ppm, the chloride content is not more than 5ppm, the free acid content is not more than 30ppm, and the sodium ion content is not more than 5ppm; and example 5 is better in yield and purity than examples 1 and 6, and lower in moisture, free acid, insoluble and other impurity ions. From the above, the high-purity and high-quality potassium difluorosulfimide salt can be prepared by reaction when the amount of the alkali metal carbonate aqueous solution is 20-50% of the weight of each grade of aqueous phase or organic phase, and the yield, purity and quality of the prepared potassium difluorosulfimide salt are better when the amount of the alkali metal carbonate aqueous solution is 35% of the weight of each grade of aqueous phase or organic phase.
As is clear from the combination of examples 1, 7-8 and Table 2, the alkali metal carbonate aqueous solutions of examples 1 and 7-8 are different in mass fraction, and the yields of the potassium difluorosulfimide salt prepared in examples 7-8 are not less than 87%, the purities are not less than 99.95%, the water content is not more than 20ppm, the chloride content is not more than 5ppm, the free acid content is not more than 30ppm, the sodium ion content is not more than 5ppm, and the insoluble matters content is not more than 50ppm. The obtained potassium difluorosulfimide has high yield and purity, and extremely low contents of moisture, free acid, insoluble substances and other impurity ions, and can be directly used for synthesizing high-quality lithium difluorosulfimide.
As is clear from the combination of example 1, example 9 and Table 2, the addition factors of the poor solvents in example 1 and example 9 are different, and the yields of the potassium difluorosulfimide salt obtained in example 9 are not less than 87%, the purities are not less than 99.95%, the water content is not more than 20ppm, the chloride content is not more than 5ppm, the free acid content is not more than 30ppm, and the sodium ion content is not more than 5ppm. From the above, it is apparent that the yield and purity of the prepared potassium difluorosulfimide are high, the contents of moisture, free acid, insoluble substances and other impurity ions are extremely low, and the potassium difluorosulfimide can be directly used for synthesizing high-quality lithium difluorosulfimide by dropwise adding a poor solvent 3-5 times of the theoretical potassium difluorosulfimide into the concentrated solution.
As can be seen from the combination of examples 1, 10-11 and Table 2, the secondary reduced pressure concentration of examples 10-11 and example 1 was carried out until the solid contents of the solutions were different, and the yields of examples 10-11 were not less than 87%, the purities were not less than 99.95%, the water content was not more than 20ppm, the chloride content was not more than 5ppm, the free acid content was not more than 30ppm, and the sodium ion content was not more than 5ppm. The obtained potassium difluorosulfimide is concentrated under reduced pressure for the second time until the solid content of the solution is within 90-100%, the yield and purity of the potassium difluorosulfimide are high, the content of moisture, free acid, insoluble matters and other impurity ions is extremely low, and the potassium difluorosulfimide can be directly used for synthesizing high-quality lithium difluorosulfimide.
As is clear from the combination of examples 1, examples 12 to 13 and Table 2, the ammonia gas introduction rates of examples 12 to 13 and example 1 were different, and the yields of the potassium difluorosulfimide salts produced in examples 12 to 13 were not less than 87%, the purities were not less than 99.95%, the water content was not more than 20ppm, the chloride content was not more than 5ppm, the free acid content was not more than 30ppm, and the sodium ion content was not more than 5ppm. The yield and purity of the potassium difluorosulfimide salt prepared by the ammonia gas with the feeding rate of 0.3-1.0g/min are high, the content of moisture, free acid, insoluble substances and other impurity ions is extremely low, and the potassium difluorosulfimide salt can be directly used for synthesizing high-quality lithium difluorosulfimide.
As can be seen from a combination of example 1, comparative example 1 and Table 2, comparative example 1, in which aqueous phase α and organic phase β were not subjected to fractional washing and liquid separation treatment using an alkali metal carbonate aqueous solution, the purity and yield of the potassium salt of bisfluorosulfonyl imide obtained in comparative example 1 were far lower than those of example 1, the insoluble content was far higher than that of example 1, and the free acid content of the potassium salt of bisfluorosulfonyl imide obtained in comparative example 1 was far higher than 30ppm, and the chloride and Na ion contents were also significantly higher than those of example 1. From the above, after the aqueous phase alpha and the organic phase beta are subjected to fractional washing and liquid separation treatment by using alkali metal carbonate aqueous solution, the yield and purity of the prepared difluoro sulfimide potassium salt are higher, and the contents of moisture, free acid, insoluble matters and other impurity ions are lower.
As can be seen from a combination of example 1, comparative example 2 and Table 2, comparative example 2 is a bis-fluorosulfonyl imide triethylamine salt obtained by reacting sulfuryl fluoride with ammonium fluoride, and as can be seen from Table 2, the purity and yield of the bis-fluorosulfonyl imide potassium salt obtained in comparative example 2 are far lower than those in example 1, the insoluble content is far higher than that in example 1, and the free acid content of the bis-fluorosulfonyl imide potassium salt obtained in comparative example 2 is far higher than that in example 1, the chloride and Na ion contents are also significantly higher than those in example 1, because the reaction is conducted with ammonium fluoride directly to introduce a lot of impurity ions. The method can obtain the difluoro sulfonimide triethylamine salt through the reaction path that the sulfonyl fluoride reacts with ammonia gas to generate the difluoro sulfonimide and the hydrogen fluoride, and the triethylamine reacts with the sulfonyl fluoride to generate the difluoro sulfonimide triethylamine salt and the triethylamine hydrogen fluoride salt, so that the yield and the purity of the regenerated difluoro sulfonimide potassium salt are higher, and the contents of moisture, free acid, insoluble matters and other impurity ions are lower.
The foregoing are all preferred embodiments of the present application, and are not intended to limit the scope of the present application in any way, therefore: all equivalent changes of products, methods and principles of this application are intended to be covered by the scope of this application.

Claims (10)

1. The preparation method of the high-purity bis-fluorosulfonyl imide potassium salt is characterized by comprising the following steps:
under the protection of inert gas, taking sulfuryl fluoride, ammonia gas and triethylamine as raw materials, and performing a first reaction in an organic solvent to obtain a first reaction solution containing difluoro sulfonimide triethylamine salt;
filtering, decompressing and concentrating the first reaction liquid, and separating liquid after washing to obtain a water phase alpha and an organic phase beta;
respectively adding alkali metal carbonate aqueous solution into aqueous phase alpha and organic phase beta, and separating the organic phase beta to obtain aqueous phase alpha 1 Beta with organic phase 1 The aqueous phase alpha 1 Separating to obtain water phase alpha 2 Beta with organic phase 2 ；
Combining the aqueous phases alpha 1 With aqueous phase alpha 2 Obtaining aqueous phase alpha 3 Continuously adding alkali metal carbonate aqueous solution, separating to obtain aqueous phase alpha 3 And organic phase beta 3 ；
Combining the organic phases beta 1 、β 2 And beta 3 Obtaining organic phase beta 4 Namely, bis (fluorosulfonyl) imide triethylamine salt, carrying out a second reaction on the bis (fluorosulfonyl) imide triethylamine salt obtained by the method and potassium hydroxide aqueous solution to obtain a second reaction solution containing bis (fluorosulfonyl) imide potassium;
and purifying the second reaction solution to obtain the pure potassium difluorosulfimide salt.
2. The method for preparing the high-purity bis-fluorosulfonyl imide potassium salt according to claim 1, characterized in that: the molar ratio of the ammonia gas to the sulfuryl fluoride to the triethylamine is 1.0: (2.0-2.2): (3.0-3.5).
3. The method for preparing the high-purity bis-fluorosulfonyl imide potassium salt according to claim 1, characterized in that: the ammonia gas is introduced at a rate of 0.3-1.0g/min.
4. The method for preparing the high-purity bis-fluorosulfonyl imide potassium salt according to claim 1, characterized in that: the reaction temperature of the first reaction is-10-25 ℃ and the reaction time is 2-10h.
5. The method for preparing the high-purity bis-fluorosulfonyl imide potassium salt according to claim 1, characterized in that: the concentration of the alkali metal carbonate aqueous solution is 10-50wt%, and the dosage of the alkali metal carbonate aqueous solution is 20-50% of the weight of each grade of water phase or organic phase.
6. The method for preparing the high-purity bis-fluorosulfonyl imide potassium salt according to claim 1, characterized in that: the molar ratio of the bis-fluorosulfonyl imide triethylamine salt to potassium hydroxide is 1: (1-1.01).
7. The method for preparing the high-purity bis-fluorosulfonyl imide potassium salt according to claim 1, characterized in that: the purification treatment comprises the following steps:
filtering the second reaction liquid, concentrating under reduced pressure, dissolving with good solvent, and filtering; concentrating under reduced pressure for the second time, recrystallizing the poor solvent, washing, and drying in vacuum to obtain the pure potassium difluorosulfimide salt.
8. The method for preparing high-purity bis-fluorosulfonyl imide potassium salt according to claim 7, characterized in that: the dosage of the poor solvent is 1-10 times of the weight of theoretical potassium difluorosulfimide, and the temperature of the system is controlled at 40-60 ℃ when the poor solvent is added.
9. A high purity bis-fluorosulfonyl imide potassium salt produced by the production process of any one of claims 1-8 characterized in that: the purity is more than or equal to 99.95 percent, the moisture is less than or equal to 20ppm, the chloride is less than or equal to 5ppm, the free acid is less than or equal to 30ppm, the sodium ion is less than or equal to 5ppm, and the insoluble matter is less than or equal to 50ppm.
10. Use of the high purity bis-fluorosulfonyl imide potassium salt produced by the production process of any one of claims 1-8 characterized in that: the high-purity potassium bis (fluorosulfonyl) imide can be directly used for synthesizing high-quality lithium bis (fluorosulfonyl) imide.
CN202311338947.9A 2023-10-12 2023-10-12 Preparation method of high-purity bis (fluorosulfonyl) imide potassium salt Pending CN117361452A (en)

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