KR20220135281A - Method for manufacturing sodium bis(fluorosulfonyl)imide - Google Patents

Abstract

The present invention relates to a method for producing sodium bis(fluorosulfonyl)imide using a single solvent, and a manufacturing process is simple and economical and the sodium bis(fluorosulfonyl)imide with high purity and high yield can be produced.

Description

Method for manufacturing sodium bis(fluorosulfonyl)imide

The present invention relates to a method for preparing sodium bis(fluorosulfonyl)imide, and more particularly, to a method for preparing sodium bis(fluorosulfonyl)imide using a single solvent.

Recently, with the commercialization of various mobile devices, the need for high-performance secondary batteries is increasing, and with the commercialization of electric and hybrid electric vehicles and the development of electric storage devices, secondary batteries with high output, high energy density, and high discharge voltage performance are required. became necessary

Among secondary batteries, a lithium ion battery or a sodium ion battery includes a negative electrode, a positive electrode, a separator, and an electrolyte. The electrolyte consists of lithium or sodium salts dissolved in a solvent, usually a mixture of organic carbonates, and has a good compromise between viscosity and permittivity.

The most widely used salts include lithium hexafluorophosphate (LiPF ₆ ), which has many of the many qualities required, but has the disadvantage of decomposing in the form of hydrofluoric acid gas.

Accordingly, the importance of a metal salt in the composition of a suitable electrolyte is emerging, and there is a need for economically preparing a high-purity bis(fluorosulfonyl)imide metal salt.

On the other hand, bis(fluorosulfonyl)imide metal salts are commercially available such as lithium bis(fluorosulfonyl)imide, sodium bis(fluorosulfonyl)imide, and potassium bis(fluorosulfonyl)imide. is becoming

Among them, lithium bis(fluorosulfonyl)imide, in particular, has increased commercial importance because it exhibits performance required for such lithium secondary batteries for electric vehicles.

In addition, sodium bis(fluorosulfonyl)imide is applied to a sodium secondary battery, which is a next-generation secondary battery, and a mixture of sodium bis(fluorosulfonyl)imide and potassium bis(fluorosulfonyl)imide is 100° C. or less Possibility of application to next-generation secondary batteries using the advantage of melting in

WO2010-113483 discloses a method for preparing lithium bis(fluorosulfonyl)imide by reaction of perfluorosulfonic acid with urea, and WO2010-113835 discloses lithium bis(fluorosulfonyl)imide by reaction of difluorosulfoxide with ammonia. Methods for preparing (fluorosulfonyl)imides are disclosed.

As such, a method for preparing lithium bis(fluorosulfonyl)imide has been studied a lot, but various studies have not been made on a method for preparing sodium bis(fluorosulfonyl)imide. There is a need for development of a method for preparing sodium bis(fluorosulfonyl)imide.

WO2010-113483 WO2010-113835

As a result of various studies conducted by the present inventors, when a single solvent is used in the cation substitution reaction step of replacing the organic cation of bis(fluorosulfonyl)imide ammonium salt with sodium ion, sodium bis(fluorosulfonyl) is already The present invention was completed by confirming that it was possible to improve the purity and yield of de

Accordingly, an object of the present invention is to provide a method for preparing sodium bis(fluorosulfonyl)imide having excellent purity and yield, and a simple manufacturing process.

In order to achieve the above object,

The present invention comprises the steps of: (A) adding an ammonium salt of bis(fluorosulfonyl)imide and a single solvent to a reaction vessel, stirring, and filtering undissolved impurities to form a filtrate;

(B) adding sodium hydroxide and a single solvent to another reaction vessel and stirring;

(C) forming a filtrate by adding the filtrate of step (A) to the mixture of step (B), stirring, and filtering impurities not dissolved in a single solvent; and

(D) concentrating the filtrate of step (C);

(E) preparing sodium bis(fluorosulfonyl)imide by stirring the concentrated filtrate of step (D) in a vacuum and then solidifying it to prepare sodium bis(fluorosulfonyl)imide comprising; provide a way

The method for preparing sodium bis(fluorosulfonyl)imide of the present invention has the effect of obtaining sodium bis(fluorosulfonyl)imide in high purity and in high yield.

In addition, the method for preparing sodium bis(fluorosulfonyl)imide of the present invention has an economical effect because the manufacturing process is simple and the manufacturing time can be shortened.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a method for preparing sodium bis(fluorosulfonyl)imide (NaFSI).

Specifically, the method for preparing sodium bis (fluorosulfonyl) imide of the present invention comprises:

(A) bis(fluorosulfonyl)imide ammonium salt and a single solvent were added to the reaction vessel and stirred, followed by filtering undissolved impurities to form a filtrate;

(B) adding sodium hydroxide and a single solvent to another reaction vessel and stirring;

(C) forming a filtrate by adding the filtrate of step (A) to the mixture of step (B), stirring, and filtering impurities not dissolved in a single solvent; and

(D) concentrating the filtrate of step (C);

(E) preparing sodium bis(fluorosulfonyl)imide by stirring the concentrated filtrate in step (D) in a vacuum and then solidifying it.

In step (A), bis(fluorosulfonyl)imide ammonium salt and a single solvent are added to the reaction vessel, stirred, and then undissolved impurities are filtered to form a filtrate.

The stirring in step (A) is performed at room temperature, and stirring may be performed until the ammonium salt of bis(fluorosulfonyl)imide is completely dissolved in a single solvent.

In addition, the filtration of step (A) may be carried out by a general method used in the art, and preferably may be carried out by a method of reduced pressure filtration.

Step (B) is a step of adding sodium hydroxide and a single solvent to another reaction vessel and stirring.

The sodium bis(fluorosulfonyl)imide may be prepared through a cationic substitution reaction of bis(fluorosulfonyl)imide ammonium salt and sodium hydroxide. Accordingly, the sodium hydroxide may be a sodium compound used in a cation substitution reaction.

The stirring in step (B) may be performed at a temperature of 0 to 15° C. for 4 to 6 hours.

If the temperature is less than 0°C, the reaction rate may be slowed and there may be a problem that the manufacturing process takes a long time, and if it exceeds 15°C, impurities may be included, which is not preferable.

The sole solvent used in steps (A) and (B) is an organic solvent, and is selected from the group consisting of butyl acetate, isobutyl acetate, ethyl propionate, ethyl isopropionate, isopropyl acetate and sec-butyl acetate. It may be one type selected from the group consisting of butyl acetate, isobutyl acetate and ethyl propionate, and most preferably butyl acetate.

In addition, the bis(fluorosulfonyl)imide ammonium salt and sodium hydroxide are present in a weight ratio of 5:1 to 1:1, preferably 3:1 to 1:1, and most preferably 2:1. can be mixed.

If the bis(fluorosulfonyl)imide ammonium salt is included in excess of the above weight ratio, the bis(fluorosulfonyl)imide ammonium salt does not participate in the reaction, so the yield of sodium bis(fluorosulfonyl)imide is low. And, when included in less than the weight ratio, sodium hydroxide may be included in excess, which may be uneconomical.

Step (C) is a step of forming a filtrate by adding the filtrate of step (A) to the mixture of step (B) and stirring, and then filtering impurities not dissolved in a single solvent.

The input is to dropwise the filtrate of step (A) to the mixture of step (B).

The stirring in step (C) may be made at a temperature of 0 to 25 °C for 2 to 6 hours, preferably at a temperature of 0 to 10 °C for 3 to 5 hours.

In the stirring temperature range, the properties and yield of sodium bis(fluorosulfonyl)imide are the best, and if the stirring temperature is less than 0°C, the reaction temperature is low, the solvent is cooled, and the reactivity may be reduced, exceeding 25°C If the product is decomposed and the impurity content is increased, the purity and yield of sodium bis(fluorosulfonyl)imide may be reduced.

In addition, if the stirring time is less than 2 hours, the reaction may not proceed sufficiently and the yield of sodium bis(fluorosulfonyl)imide may decrease. If it exceeds 6 hours, the reaction stability decreases and the content of impurities increases. Therefore, the purity may be lowered.

The input and stirring of the filtrate in step (A) may be performed while injecting nitrogen gas (N ₂ ). If the filtrate of step (A) is added to the mixture of step (B) without injecting the nitrogen gas, stirring may not be performed well, so that the yield of sodium bis(fluorosulfonyl)imide may be significantly lowered.

The filtration in step (C) may be to remove the distilled water layer containing undissolved impurities after stirring by adding distilled water after completion of stirring to obtain an organic layer.

The stirring time is not particularly set, and may be carried out for about 30 minutes.

In addition, the more the filtration is repeated, the more likely the impurities are removed, but in the present invention, it is preferable to carry out 2-3 times.

After removing the distilled water layer containing the impurities, an organic layer may be obtained.

The filtrate in step (C) may be obtained by filtration of the organic layer, and the filtration method is not particularly limited, but may be preferably carried out by a reduced pressure filtration method.

Step (D) is a step of concentrating the filtrate of step (C).

The concentration may be made in a rotary vacuum evaporator at a temperature of 30 to 60 °C, preferably at a temperature of 35 to 50 °C. The concentration time may be 1 hour or more, and the appropriate time is preferably determined by looking at the progress of the concentration. If the solvent is subsequently solidified in an over-concentrated state, the yield of the final product, sodium bis(fluorosulfinol)imide, is lowered. It is difficult to obtain (fluorosulfonyl)imide and the yield may be poor.

Step (E) is a step of preparing sodium bis(fluorosulfonyl)imide by stirring the concentrated filtrate of step (D) in a vacuum and then solidifying it.

The agitation of step (E) may be performed while injecting nitrogen gas (N ₂ ) in a vacuum state reduced pressure by a vacuum pump. If the nitrogen gas injection is not sufficient, sodium bis(fluorosulfonyl)imide may be prepared in a solid mass rather than a powder form, which is not preferable.

In addition, the stirring may be made at a temperature of 30 to 60 ℃, preferably 40 to 50 ℃, 10 minutes to 90 minutes, preferably 30 minutes to 80 minutes.

In the above stirring temperature range, the properties and yield of sodium bis(fluorosulfonyl)imide are the best, and if the stirring temperature is less than 30°C, the solvent is not completely removed, so sodium bis(fluorosulfonyl)imide is converted into a solid mass. It may be generated, and if it exceeds 60° C., a large amount of impurities may be included, which is not preferable.

In addition, the degree of removing the remaining solvent within the stirring time range is excellent, so that the yield of sodium bis(fluorosulfonyl)imide may be relatively improved. However, if the stirring time is less than 10 minutes, the reaction may not proceed sufficiently and the yield of sodium bis(fluorosulfonyl)imide may decrease.

After the stirring, toluene is added and stirred to solidify the product to form a white solid, and nitrogen gas is injected into the solid, filtered under reduced pressure, and dried under vacuum to finally sodium bis(fluorosulfonyl)imide can get

The sodium bis(fluorosulfonyl)imide prepared by the method of the present invention can be usefully used as a material of an ion conductor constituting an electrochemical device such as a secondary battery.

Hereinafter, the present invention will be described in more detail by way of Examples. However, these examples are only presented in order to understand the content of the present invention and should not be construed as limiting the scope of the present invention to these examples.

Examples 1 to 5. Preparation of sodium bis(fluorosulfonyl)imide

In a one-neck round bottom flask, 20 g (1 equivalent) of Bis(fluorosulfonyl)imide ammonium salt (NH ₄ FSI) and isobutyl acetate as a sole solvent , IBA) was added and stirred at room temperature for 10 minutes to dissolve the bis(fluorosulfonyl)imide ammonium salt. Thereafter, the filtrate was obtained by filtration under reduced pressure to remove undissolved impurities.

In a three-neck round bottom flask, 10 g (2.5 equivalents) of sodium hydroxide (NaOH) and 20 g of isobutyl acetate as a single solvent were added, followed by stirring in an ice bath for 4 hours.

The filtrate was added dropwise for 5 minutes while slowly injecting nitrogen gas (N ₂ ) into the three-necked round-bottom flask, and stirred for 4 hours while maintaining the internal temperature of the three-necked round-bottom flask at 5°C.

After completion of the reaction, 30 g of distilled water was added and stirred, the distilled water layer containing undissolved impurities was removed, and an organic layer was obtained.

The organic layer was filtered under reduced pressure to obtain a filtrate, and the filtrate was concentrated in a rotary vacuum evaporator at a temperature of 45° C. for 1 hour (first concentration).

The concentrated filtrate was transferred to a three-necked round-bottom flask equipped with a thermometer, and stirred at a temperature of 45° C. for 40 minutes while injecting nitrogen gas in a vacuum (second concentration).

Thereafter, as 82 g of toluene was added, a solid was gradually generated, and the mixture was stirred at room temperature for 10 minutes. After stirring, nitrogen gas was injected and filtered under reduced pressure, and the filtered solid was dried in a vacuum to obtain sodium bis(fluorosulfonyl)imide (NaFSI), and the yield was 79%.

In Examples 2 to 5, sodium bis(fluorosulfonyl)imide was prepared in the same manner as in Example 1, except for the stirring time of the single solvent and the secondary concentration of Example 1, and the conditions were It is shown in Table 1 below.

NH ₄ FSI NaOH Sole solvent Second concentration time transference number Example 1 20 g (1 equivalent) 10 g (2.5 equivalents) IBA 40 minutes 79% Example 2 15 g (1 equivalent) 7.5 g (2.5 equivalents) EP 30 minutes 74% Example 3 20 g (1 equivalent) 10 g (2.5 equivalents) EP 35 minutes 77% Example 4 20 g (1 equivalent) 10 g (2.5 equivalents) BA 70 minutes 78% Example 5 20 g (1 equivalent) 10 g (2.5 equivalents) BA 75 minutes 81%

IBA: isobutyl acetate

EP: ethyl propionate

BA: butyl acetate

The reactions of Examples 1 to 5 are shown in Scheme 1 below.

[Scheme 1]

From the results of Examples 1 to 5, it was found that the production method of the present invention can produce sodium bis(fluorosulfonyl)imide in high yield in a simple process using a single solvent. In addition, it was found that butyl acetate can prepare sodium bis(fluorosulfonyl)imide with the highest yield among single solvents.

Claims (9)

(A) bis(fluorosulfonyl)imide ammonium salt and a single solvent were added to the reaction vessel and stirred, followed by filtering undissolved impurities to form a filtrate;
(B) adding sodium hydroxide and a single solvent to another reaction vessel and stirring;
(C) forming a filtrate by adding the filtrate of step (A) to the mixture of step (B), stirring, and filtering impurities not dissolved in a single solvent; and
(D) concentrating the filtrate of step (C);
(E) preparing sodium bis(fluorosulfonyl)imide by stirring the concentrated filtrate of step (D) in a vacuum and then solidifying it to prepare sodium bis(fluorosulfonyl)imide comprising; Way.
According to claim 1,
The sole solvent is sodium bis (fluorosulfonyl), characterized in that it is one selected from the group consisting of butyl acetate, isobutyl acetate, ethyl propionate, ethyl isopropionate, isopropyl acetate and sec-butyl acetate imide manufacturing method.
According to claim 1,
The bis(fluorosulfonyl)imide ammonium salt and sodium hydroxide are mixed in a weight ratio of 5:1 to 1:1.
According to claim 1,
Sodium bis (fluorosulfonyl) imide manufacturing method, characterized in that the input and stirring of step (C) is made while injecting nitrogen gas.
According to claim 1,
The stirring in step (C) is a sodium bis (fluorosulfonyl) imide manufacturing method, characterized in that it proceeds for 2 to 6 hours at a temperature of 0 to 25 ℃.
According to claim 1,
In the filtration of step (C), distilled water is additionally added and stirred, and then the distilled water layer containing undissolved impurities is removed, and sodium bis(fluorosulfonyl)imide preparation, characterized in that to obtain an organic layer Way.
7. The method of claim 6,
The filtrate of step (C) is a sodium bis (fluorosulfonyl) imide manufacturing method, characterized in that the organic layer is filtered under reduced pressure.
According to claim 1,
The concentration of step (D) is sodium bis (fluorosulfonyl) imide preparation method, characterized in that proceeding at a temperature of 30 to 60 ℃.
According to claim 1,
The stirring of step (E) is sodium bis (fluorosulfonyl) imide manufacturing method, characterized in that it proceeds for 10 to 90 minutes at a temperature of 30 to 60 ℃ while injecting nitrogen gas in a vacuum state.