KR20200049164A - Very efficient Method for preparing lithium bis(fluorosulfonyl)imide - Google Patents

Abstract

The present invention relates to a method for producing lithium bis(fluorosulfonyl)imide. More particularly, the present invention relates to a method of producing lithium bis(fluorosulfonyl)imide which is a lithium salt used in an electrolyte for a secondary lithium battery and a solution thereof in an eco-friendly and economical way by a mild and simple method without a complicated and dangerous process. Lithium bis(fluorosulfonyl)imide can be represented by chemical formula 1.

Description

Very efficient method for preparing lithium bis (fluorosulfonyl) imide}

The present invention relates to a method for producing lithium bis (fluorosulfonyl) imide, and more specifically, lithium bis (fluorosulfonyl) imide, a lithium salt used in an electrolyte for a lithium secondary battery, is economical in a very efficient manner. It relates to a new method for producing lithium bis (fluorosulfonyl) imide.

With the commercialization of various mobile devices, the need for high-performance secondary batteries is increasing, and recently, commercialization of electric vehicles and hybrid electric vehicles, and secondary batteries with high output, high energy density, high discharge voltage, etc. have been developed with the development of electric storage devices. Became necessary.

In particular, the secondary battery required for the electric vehicle should be able to be used for a long time compared to the secondary battery for a small mobile device, and the charge and discharge should be performed in a short period of time, and safety and high power should be exhibited.

The importance of the lithium salt in the composition of the electrolyte solution suitable for this has emerged, and it has been found that the lithium bis (fluorosulfonyl) imide compound has excellent demanding performance compared to the existing lithium hexafluorophosphate compound (LiPF ₆ ), and the demand is explosively increased. Doing.

On the other hand, the secondary battery has a specific gravity close to 40% in the cost structure of an electric vehicle, and the lithium battery has a high specific gravity in the cost structure of the secondary battery. Easily, the need to manufacture has become desperate.

The conventional method for preparing lithium bis (fluorsulfonyl) imide is shown in the following Reaction Scheme 1.

[Scheme 1]

As shown in the above reaction formula, bis (fluorine) is reacted with 1 equivalent of zinc fluoride using bis (chlorosulfonyl) imide (Compound (2)) as a starting material according to a conventional manufacturing method. Sulfonyl) imide (Compound (3)) is prepared. Since lithium bis (fluorosulfonyl) imide is a lithium salt used in electrolytes, removal of zinc metal components is most important because metal components other than lithium must be adjusted to the PPM level.

However, the reaction requires the use of expensive zinc fluoride (II), the removal of poorly soluble zinc components and the generation of a large amount of waste water containing zinc components, whereby some of the bis (fluorsulfonyl) imide is lost. There are disadvantages such as that and finally, zinc metal must be adjusted in units of PPM in the product.

According to another conventional manufacturing method, NH4F (HF) n, n = 0 to 10 is used as a fluorination reagent to react with the bis (chlorosulfonyl) imide (Compound (2)). This is shown in Scheme 2 below.

[Scheme 2]

In the above formula, researchers claim that ammonium bis (fluosulfonyl) imide salt (compound (4)) is produced as an intermediate step in Scheme 2, but actually use NH4F or NH4F. (HF) n (n = 1 ~ 10). When the fluorination reaction proceeds, NH4F is converted to NH4Cl, NH4F. (HF) n is converted to NH4Cl. (HF) n, but ammonium salt of compound (4) can be generated because free ammonia cannot be released. none. As a result of repeated experiments by this researcher, the yield is low and the liquid (3) with low boiling point and some NH4F. (HF) n (n = 0 ~ 10) and NH4Cl. (HF) n (n = 0 ~ 10) together Was obtained. Actually, as can be seen in Comparative Example 2 below, the target was only obtained in a yield of 40%. The reason was that bis (floorsulfonyl) imide (Compound (3)) was lost as it was evaporated during transport or concentration as a liquid substance with a relatively low boiling point (boiling point: 68 to 69 ° C / 25 mmHg). In addition, NH4 (HF) n (n = 1 to 10) and bis (floorsulfonyl) imide (compound (3)) are highly acidic and may cause corrosion of equipment during the production process, making them unsuitable for commercial production.

As a result of this study, the researcher has studied the above examples to overcome the disadvantages

i) No wastewater generation

ii) No product loss due to no washing process

iii) It does not go through a multi-step complex manufacturing process

iv) It is easy to make solidified products

 It was confirmed that a highly pure lithium bis (fluorosulfonyl) imide compound can be prepared by a very simple method. The method is described in Examples 2 to 5.

In addition, the existing NH4F or NH4 (HF) n (n = 1 to 10) inevitably contains about 3 to 4% moisture in the manufacturing process.

The researchers mentioned that there is no mention of this and that commercially available ones can be used. On the other hand, if a commercial product is used as it is, starting material bis (chlorosulfonyl) imide, which is very vulnerable to moisture due to a considerable amount of moisture in NH4 (HF) n (n = 0 ~ 10), as can be seen in Comparative Example 1 below ( Compound (2)) is hydrolyzed very easily and the yield is inevitably low.

 When NH4F of the researcher's patent comparative example 1 is blown on the basis of 4.8 equivalents of starting material, 3% by weight of moisture in NH4F corresponds to 0.296 moles per mole of starting compound (2) when the level content is considered to contain 3 wt% moisture of commercial products. In theory, 29.6% of the starting material is hydrolyzed to generate sulfuric acid derivatives and hydrochloric acid, respectively. Therefore, it is not suitable for commercial production at all due to severe yield reduction and secondary decomposition products. In addition, there was no mention of the purity of the product, and it was difficult to manufacture the product with high purity (at least 99.0%) suitable for lithium secondary battery electrolyte.

In addition, there was a method of using an As compound or a Bi compound or a hydrofluoric anhydride as a fluorination reagent in addition to the above method, but in these methods, economical efficiency is reduced, such as the use of a toxic compound, corrosion, and the like. It was not suitable for application.

1. Domestic Publication Patent No. 10-2012-0022833 2. Domestic Publication Patent No. 10-2013-0114738

In order to solve the problems of the prior art as described above, the present invention is a lithium salt used in the electrolyte for a lithium secondary battery, lithium bis (fluorosulfonyl) imide in a multi-step complex and economical by a gentle and simple method without complicated and dangerous process It is to provide a method for producing lithium bis (fluorosulfonyl) imide that can be produced in an environmentally friendly manner with no high-purity and no waste water, and to provide a solution thereof.

In order to achieve the above object, the present invention is prepared by reacting a bis (chlorosulfonyl) imide compound with various lithiation reagents under (S1) solvent to prepare a lithium bis (chlorosulfonyl) imide compound and without an purification, anhydrous fluorine The step of preparing a lithium bis (fluorosulfonyl) imide by reacting with a chemical reagent and obtaining a solid product immediately without going through additional steps such as recrystallization.

It relates to a method for preparing lithium bis (fluorosulfonyl) imide represented by the following Chemical Formula 1, and a solution thereof.

[Formula 1]

The lithiation reagent of the above step is lithium hydroxide (LiOH), lithium hydroxide hydrate (LiOH nH2O), lithium carbonate (Li2CO ₃ ), lithium hydrogen carbonate (LiHCO3), lithium hydride (LiH), lithium metal (Li), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), R may be C1 to C10 linear, condensed or aromatic lithium carboxylate (RCO2Li), lithium oxalate (Li ₂ C ₂ O ₄ ), etc. have.

The fluorination reagent may be ammonium fluoride (NH ₄ F), diethylaminosulfur trifluoride, sulfur tetrafluoride, hydrofluoric acid (HF), buffer oxide etchant (BOE), or the like.

The solvent of the step (S1) is diethyl ether, diisopropyl ether, and methyl-t-butyl ether, which is any one selected from the group consisting of ethers; Alkoxyethanes such as dimethoxyethane and diethoxyethane; Esters of any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; Nitriles selected from the group consisting of acetonitrile, propionitrile, and butyronitrile; Nitromethane, nitroethane, nitropropane, and any one selected from the group consisting of nitrobutane, etc., nitroalkanes, pentane, hexane, and heptane. Alcohols selected from the group consisting of methanol, ethanol, propanol, and butanol; Ketones selected from the group consisting of acetone, methyl ethyl ketone, and methyl isopropyl ketone; And dialkyl carbonates selected from the group consisting of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; It may be selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, and the like, but is not limited thereto. In particular, when a dialkyl carbonate group or an alkylene carbonate that can be used as a solvent in a double electrolyte is used as a solvent, there is an advantage of preparing a solution of lithium bis (fluorosulfonyl) imide that can be used as an electrolyte composition immediately.

The fluorination reagent in step (S1) may be used in an amount of 2.0 to 10.0 equivalents compared to bis (chlorosulfonyl) imide, and a solvent in an amount of 1.0 to 100.0 equivalents, and the lithiation reagent may be compared to bis (fluorosulfonyl) imide It can be used in 1.0 to 5.0 equivalents.

In addition, the manufacturing method of the present invention may further perform the step of concentration, powdering and purification after step (S1).

In addition, the present invention provides a lithium bis (fluorosulfonyl) imide having a purity of 99.5 to 99.9% or more by the above method.

According to the present invention, lithium bis (fluorosulfonyl) imide, which is a lithium salt used in an electrolyte for a lithium secondary battery, and a solution thereof can be produced in an environmentally friendly and economical manner by a gentle and simple method without complicated and dangerous processes.

Hereinafter, the present invention will be described in detail.

In the present invention, a bis (chlorosulfonyl) imide compound is reacted with various lithiation reagents under (S1) solvent to prepare a lithium bis (chlorosulfonyl) imide compound and reacted directly with anhydrous fluorination reagent without purification to produce lithium bis. Preparation of (fluorosulfonyl) imide and solidifying

It provides a method for producing a lithium bis (fluorosulfonyl) imide represented by the following formula (1) containing (Lithium bis (fluorosulfonyl) imide) and a solution thereof.

[Formula 1]

The lithium bis (fluorosulfonyl) imide represented by Chemical Formula 1 may be prepared as in Scheme 3 below.

[Scheme 3]

According to Reaction Scheme 3, the lithium bis (fluorosulfonyl) imide (Compound 1) represented by Chemical Formula 1 of the present invention uses a bis (chlorosulfonyl) imide as the starting material (Compound 2) and a lithiation reagent. It can be prepared by reacting and in-situ by adding a fluorinated reagent and stirring.

The present invention will be described in more detail as follows.

First, bis (chlorosulfonyl) imide (Compound 2) and a lithiation reagent are reacted under a solvent to prepare lithium bis (chlorosulfonyl) imide (Compound 5).

The lithiation reagent is lithium hydroxide (LiOH), lithium hydroxide hydrate (LiOH nH2O), lithium carbonate (Li2CO ₃ ), lithium hydride carbonate (LiHCO3), lithium hydride (LiH), lithium metal (Li), lithium chloride (LiCl ), Lithium bromide (LiBr), lithium iodide (LiI), and straight, condensed or aromatic lithium carboxylates (RCO2Li) of C _{1 to} C 10 carbon atoms, lithium oxalate (Li ₂ C ₂ O ₄ ), etc. may be used. have.

The lithiation reaction is preferably carried out at a temperature of 20 to 60 ° C, preferably 25 to 40 ° C.

The solvent is any one selected from the group consisting of diethyl ether, diisopropyl ether, and methyl-t-butyl ether, etc .; Alkoxyethanes such as dimethoxyethane and diethoxyethane; Esters of any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; Nitriles selected from the group consisting of acetonitrile, propionitrile, and butyronitrile; Nitromethane, nitroethane, nitropropane, and any one selected from the group consisting of nitrobutane, etc., nitroalkanes, pentane, hexane, and heptane. Alcohols selected from the group consisting of methanol, ethanol, propanol, and butanol; Ketones selected from the group consisting of acetone, methyl ethyl ketone, and methyl isopropyl ketone; And dialkyl carbonates selected from the group consisting of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; Ethylene carbonate, propylene carbonate, butylene carbonate, etc. can be used. In particular, when a dialkyl carbonate group or an alkylene carbonate that can be used as a solvent in a double electrolyte is used as a solvent, there is an advantage of preparing a solution of lithium bis (fluorosulfonyl) imide that can be used as an electrolyte composition immediately.

Ammonium fluoride (NH ₄ F), hydrogen fluoride (HF), diethylaminosulfur trifluoride, sulfur tetrafluoride, etc. may be used as the fluorination reagent, and ammonium fluoride is particularly preferred. Ammonium fluoride is not only economical due to its low cost, but also has a very high reaction rate compared to fluoride of alkali metals or alkaline earth metals, and is very advantageous because it can eliminate contamination problems due to the replacement of lithium metal by using other metals.

All fluorinated reagents must be low in moisture. This is because, when the moisture content is high, the starting material, bis (chlorosulfonyl) imide, is hydrolyzed and decomposed to degrade yield and cause serious equipment corrosion. However, in the case of ammonium fluoride, when all products are used at 3% moisture, a very serious yield decrease occurs.

The present inventor has developed a technique to use ammonium fluoride without problems by developing a method of dropping moisture from 30,000 PPM level to 1,000 PPM or less in a few hours through a simple slurry method using a low-cost solvent.

Solvents that can be used to remove ammonium fluoride include acetone, methyl ethyl ketone, methyl isopropyl ketone, lower alkyl ketones, methanol, anhydrous ethanol, lower alcohols such as 1-propanol, isopropanol, lower alkyl nitriles such as acetonitrile and propionnitrile. , Tetrahydrofuran, dialkoxy alkanes, and lower ethers are possible, but acetone is inexpensive and has a low boiling point, so it can be easily removed and dried. The amount of the solvent used is sufficient if 0.5 to 1.5 times the weight of ammonium fluoride. The purification method was described in Example 1.

In the reaction (S1), the solvent is used in an amount of 1.0 to 100.0 equivalents compared to bis (chlorosulfonyl) imide, and the lithiation reagent is used in an amount of 1.0 to 3.0 equivalents compared to bis (chlorosulfonyl) imide.

The fluorinated reagent is used in an amount of 2.0 to 10.0 equivalents compared to bis (chlorosulfonyl) imide.

The fluorination reaction is preferably carried out by raising the temperature to a temperature of 30 ~ 100 ℃, preferably 80 ℃.

When the reaction produces lithium bis (fluorosulfonyl) imide (Compound 1), the resulting salt and insoluble components are filtered and concentrated, and then the solvent is completely removed using a thin-film distiller at low temperature to commercialize the crystal powder. It is possible to commercialize it in a very simple process.

In addition, while the existing inventors concentrated and recrystallized at a high concentration after the reaction, the process of contact with water was completely excluded in the process of manufacturing this product, which is very hygroscopic, and after concentration, it was found that powdering is possible under certain conditions using a molecular distiller. It has the advantage of being eco-friendly and economical because it can guarantee high yield and prevent increase of impurities due to long-time operation at high temperature during the concentration process.

That is, in the case of commercialization as a powder after the reaction, the conventional method filters the reactants to remove generated salts and insoluble matters, and after concentration and crystallization purification, the desired crystalline component of lithium bis (fluorosulfonyl) imide Horse products could be obtained. However, in order to obtain a high concentration of 50 wt% or more even in the case of maintaining a low impurity content in the reaction, it is inevitable to perform the concentration process for a long time at a temperature of 60 ° C to 80 ° C and a vacuum of 5 Torr or less. It is difficult to do it, and the content of impurities increases in the process of being left at high temperature for a long time.

To prevent this, by improving the bladder of the thin film distiller and allowing the precipitated crystals to be discharged, the residence time at a high temperature can be significantly shortened and the evaporation rate of the solvent can be dramatically increased to suppress impurities and solidify. You can get the product. Therefore, no additional recrystallization is necessary, and it is much more efficient because the yield lost in the recrystallization process and the multi-step process can be omitted.

The lithium bis (fluorosulfonyl) imide of the present invention prepared as described above can be prepared with a high purity of 99.0% or more, preferably 99.9% or more.

According to the present invention as described above, it is economical by using an inexpensive and cheap fluorination reagent in place of the expensive fluoride zinc used in the production of conventional lithium bis (fluorosulfonyl) imide, and is cheaper than other AsF3 or BiF3 And there are no toxicity and safety issues. In addition, the existing manufacturing method has to go through several steps, but according to the present invention, it is possible to react with a single solvent, and there is no additional crystallization or recrystallization process, so commercialization is possible with a very simple process. In addition, it is possible to guarantee a higher yield, and it is possible to produce high yield lithium bis (fluorosulfonyl) imide in a simple process while having eco-friendly and economical advantages by excluding wastewater generation.

Hereinafter, the present invention will be described in more detail with reference to examples. These examples are for illustrative purposes only and are not intended to limit the protection scope of the present invention.

Example 1. Preparation of anhydrous ammonium fluoride

In a 500 mL flask with a stirrer, condenser and thermometer attached, 100 g of commercial ammonium fluoride (purity: 96%; 3.6% moisture during Karl Fischer analysis) and 120 g of acetone were added at room temperature and stirred at room temperature for 3 hours. After filtering the acetone slurry of ammonium fluoride with filter paper, the ammonium fluoride collected in the filter paper was collected in a 250 mL round flask, and the residual acetone was blown and dried under reduced pressure (10 Torr) at 40 ° C, and 93 g of white crystal anhydrous ammonium Fluoride was obtained. When analyzing the Karl Fischer moisture, the moisture was measured to be 760 ppm and used for the reaction.

Example 2. Preparation of lithium bis (fluorsulfonyl) imide powder (when LiCl is used as a lithiation reagent)

In a 500 mL fluorine resin container equipped with a stirrer, a condenser, and a thermometer, 20.0 g of anhydrous lithium chloride, 100 g of dimethyl carbonate and 100 g of bis (dichlorosulfonyl) imide were slowly added at room temperature in a nitrogen atmosphere. After the reaction was stirred to proceed to the lithiation reaction, the generated gas was removed by stirring for 60 minutes at a reduced pressure of 30 torr or less, and then 36.0 g of ammonium fluoride was added at room temperature. While the reaction was stirred, the reaction was performed while heating to 80 ° C to prepare lithium bis (fluorosulfonyl) imide.

After the reaction was completed, the reactant was cooled to room temperature, and the generated salt was filtered through filter paper, and then a dimethyl carbonate solution of colorless and transparent lithium bis (fluorosulfonyl) imide was obtained. The obtained dimethyl carbonate solution was concentrated under reduced pressure and concentrated, powdered, and dried at 40 ° C or lower and 0.01 Torr or lower using a thin film distiller to obtain 82.2 g of a lithium bis (fluorosulfonyl) imide compound as a white crystalline component (yield). : 95%, purity: 99.5%)

Example 3. Preparation of lithium bis (fluorsulfonyl) imide powder (when Li2CO3 is used as a lithiation reagent)

In a 500 mL fluororesin container with a stirrer, condenser and thermometer, 18.0 g of anhydrous lithium carbonate, 100 g of dimethyl carbonate and 100 g of bis (dichlorosulfonyl) imide were slowly added at room temperature in a nitrogen atmosphere. After the reaction was stirred to proceed to the lithiation reaction, the mixture was stirred for 30 minutes at 30 torr under reduced pressure, and then 36.0 g of ammonium fluoride was added at room temperature. While the reaction was stirred, the reaction was performed while heating to 80 ° C to prepare lithium bis (fluorosulfonyl) imide.

After the reaction was completed, the reactant was cooled to room temperature, and the generated salt was filtered through filter paper, and then a dimethyl carbonate solution of colorless and transparent lithium bis (fluorosulfonyl) imide was obtained. The obtained dimethyl carbonate solution was concentrated under reduced pressure and concentrated, powdered, and dried at 40 ° C or lower and 0.01 Torr or lower using a thin film distiller to obtain 81.3 g of a lithium bis (fluorosulfonyl) imide compound as a white crystalline component (yield). : 94%, Purity: 99.8%)

Although the present invention has been described as a preferred embodiment mentioned above, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Also, the appended claims include such modifications or variations that fall within the spirit of the present invention.

Claims (21)

Under the (S1) solvent, a bis (chlorosulfonyl) imide compound is reacted with various lithiation reagents to prepare a lithium bis (chlorosulfonyl) imide compound, and immediately reacted with anhydrous fluorination reagent without purification to produce lithium bis (fluoro). Sulfonyl) imide production step and concentration, drying process to produce a solid product immediately
Method for preparing lithium bis (fluorosulfonyl) imide represented by the following formula (1) comprising:
[Formula 1]

According to claim 1,
The lithiation reagent is lithium hydroxide (LiOH), lithium hydroxide hydrate (LiOH nH2O), lithium carbonate (Li2CO ₃ ), lithium hydride carbonate (LiHCO3), lithium hydride (LiH), lithium metal (Li), lithium chloride (LiCl ), Lithium bromide (LiBr), lithium iodide (LiI), R is a C1 ~ C10 straight chain, condensed or aromatic lithium carboxylate (RCO2Li), lithium oxalate (Li ₂ C ₂ O ₄ ) any one selected from Method for producing lithium bis (fluorosulfonyl) imide, characterized in that the above. According to claim 1,
The lithiation reagent is a method for producing lithium bis (fluorosulfonyl) imide, characterized in that it is used in an amount of 1.0 to 5.0 equivalents compared to bis (chlorosulfonyl) imide. According to claim 1,
The fluorination reagent is ammonium fluoride (NH ₄ F), hydrogen fluoride (HF), diethylaminosulfur trifluoride, sulfur bis characterized in that at least one selected from lithium bis (fluorosulfonyl) ) Method for producing imide. According to claim 1,
The fluorination reagent is a method of producing lithium bis (fluorosulfonyl) imide, characterized in that a water content of 3,000 PPM or less is used. According to claim 3,
A method characterized by using a solvent slurry method as a method for removing water from a fluorinated reagent. The method of claim 6,
Usable solvents include lower alkyl ketones such as acetone, methyl ethyl ketone, and methyl isopropyl ketone, lower alcohols such as methanol, ethanol anhydride, 1-propanol, and isopropanol, lower alkyl nitriles such as acetonitrile and propionitrile, tetrahydrofuran, and dialkoxy Method characterized in that at least one selected from lower ethers such as alkanes. According to claim 1,
The fluorination reagent is bis (chlorosulfonyl) imide method of producing lithium bis (fluorosulfonyl) imide, characterized in that used in an amount of 2.0 to 10.0 equivalents. According to claim 1,
The solvent is any one selected from the group consisting of diethyl ether, diisopropyl ether, and methyl-t-butyl ether, etc .; Alkoxyethanes such as dimethoxyethane and diethoxyethane; Esters of any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; Nitriles selected from the group consisting of acetonitrile, propionitrile, and butyronitrile; Nitromethane, nitroethane, nitropropane, and any one selected from the group consisting of nitrobutane, etc., nitroalkanes, pentane, hexane, and heptane. Alcohols selected from the group consisting of methanol, ethanol, propanol, and butanol; Ketones selected from the group consisting of acetone, methyl ethyl ketone, and methyl isopropyl ketone; And dialkyl carbonates selected from the group consisting of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. Method for producing lithium bis (fluorosulfonyl) imide, characterized in that at least one selected from ethylene carbonate, propylene carbonate, butylene carbonate. According to claim 1,
The solvent is a method of producing lithium bis (fluorosulfonyl) imide, characterized in that a water content of 100 PPM or less is used. According to claim 1,
The solvent is a method for producing lithium bis (fluorosulfonyl) imide, characterized in that it is used in an amount of 1.0 to 100.0 equivalents compared to bis (chlorosulfonyl) imide. According to claim 1,
Method for producing lithium bis (fluorosulfonyl) imide, characterized in that the content of the ammonium group is 5000 PPM or less. According to claim 1,
Method of producing lithium bis (fluorosulfonyl) imide further comprising the step of concentration and drying after the (S2) step. The method of claim 13,
The concentration is a method of producing lithium bis (fluorosulfonyl) imide, characterized in that the ratio of the residual reaction solvent and the Kurdish concentrate is 0.01 to 1 times by weight. The method of claim 13,
The method for producing lithium bis (fluorosulfonyl) imide, wherein the concentration and drying are performed at 60 ° C. or less. The method of claim 13,
The method for producing lithium bis (fluorosulfonyl) imide, wherein the concentration and drying are performed under a vacuum of 10 Torr or less. The method of claim 13,
The method of manufacturing lithium bis (fluorosulfonyl) imide, wherein the concentration and drying are performed using a thin film distiller. The method of claim 13,
A method for producing lithium bis (fluorosulfonyl) imide, characterized in that additional removal of insolubles and recrystallization are performed to obtain a product having a purity of 99.99% or more. The method of claim 18,
The solvent is a method of producing lithium bis (fluorosulfonyl) imide, characterized in that at least one selected from alcohols, ketones, ethers, esters, carbonates. The method of claim 18,
The solvent is a method of producing lithium bis (fluorosulfonyl) imide, characterized in that a water content of 100 PPM or less is used. A lithium bis (fluorosulfonyl) imide prepared by the method of any one of claims 1 to 20 and having a purity of 99.5% or more.