KR20230010093A - Method for Preparing Bis(fluorosulfonyl)imide Alkali Metal Salt - Google Patents

Abstract

The present invention relates to a method for manufacturing bis(fluorosulfonyl)imide alkali metal salt. More specifically, in a step of manufacturing bis(fluorosulfonyl)imide alkali metal salts by reacting bis(fluorosulfonyl)imide with an alkali metal compound, a cosolvent containing a mixture of a carbonate-based solvent and a nitrile-based solvent is used. Accordingly, productivity can be increased by shortening the production time of bis(fluorosulfonyl)imide alkali metal salt even in low-temperature reactions, and high purity bis(fluorosulfonyl)imide alkali metal salt can be produced in high yield due to low impurity generation.

Description

Method for preparing bis(fluorosulfonyl)imide alkali metal salt {Method for Preparing Bis(fluorosulfonyl)imide Alkali Metal Salt}

The present invention relates to a method for producing bis(fluorosulfonyl)imide alkali metal salt, and more particularly, to improve production efficiency by shortening the production time at a low temperature, and at the same time, high purity bis(fluorosulfonyl) already The present invention relates to a method for preparing a bis(fluorosulfonyl)imide alkali metal salt capable of producing a low alkali metal salt in high yield.

Recently, with the rapid development of electric, electronic, communication and computer industries, demand for high-performance and high-stability secondary batteries is gradually increasing. In particular, according to the trend of miniaturization and weight reduction of these electronic (communication) devices, thinning and miniaturization of lithium secondary batteries, which are core components in this field, are required.

An ion conductive non-aqueous electrolyte in which an electrolyte salt is dissolved in a non-aqueous organic solvent is mainly used as an electrolyte for the lithium secondary battery.

On the other hand, lithium salts such as LiPF ₆ , which are widely used as the electrolyte salt, are low thermal stability and moisture sensitive materials, and when reacted with water, HF is generated as a by-product due to hydrolysis of PF ₆ ^- . The HF thus formed spontaneously reacts with the weakly basic electrode active material to elute components of the electrode active material. More specifically, when the cathode active material and HF react, not only the components of the cathode active material are eluted, but also lithium fluoride (LiF) is formed on the surface of the cathode, thereby increasing the electrical resistance in the electrode and generating gas, thereby reducing the lifespan of the battery. do.

Recently, in order to solve this problem, research on electrolyte salts that can replace LiPF6 has emerged, and lithium imide salts have been proposed as representative materials.

In particular, among lithium imide salts, bis(fluorosulfonyl)imide lithium salt (LiFSI) has high thermal stability and moisture stability, low corrosiveness and viscosity, and high electrical conductivity, so it has excellent performance even under high power conditions and low temperatures. As it is known as a material that can realize, the demand for it is gradually increasing.

In general, a process for preparing bis(fluorosulfonyl)imide alkali metal salt is a process for preparing bis(fluorosulfonyl)imide and bis(fluorosulfonyl)imide from the bis(fluorosulfonyl)imide. It proceeds to a process for preparing an alkali metal salt, and the yield and purity of the bis(fluorosulfonyl)imide alkali metal salt produced are determined by the type of solvent used in the preparation process/reaction time/reaction temperature.

For example, in Patent Document 1, bis (fluorosulfonyl) imide reacts with lithium fluoride in a solvent, solids are removed by centrifugation, and then the solution is concentrated to prepare bis (fluorosulfonyl) imide lithium salt. A method has been proposed, and in Patent Document 2, bis(fluorosulfonyl)imide is reacted with lithium carbonate in a solvent, the solid content is removed by filtration, and then the solution is concentrated to obtain bis(fluorosulfonyl)imide. A method for obtaining a lithium salt has been proposed.

However, such bis(fluorosulfonyl)imide alkali metal salt can be prepared by reacting bis(fluorosulfonyl)imide with an alkali metal compound such as lithium fluoride in a reaction solvent. ℃), there is a problem in that impurity production is small, but the reaction time is long, resulting in low productivity. there was

Therefore, in order to preoccupy the market of bis(fluorosulfonyl)imide alkali metal salt, it is necessary to develop a method capable of preparing bis(fluorosulfonyl)imide alkali metal salt with high purity while increasing productivity.

Japanese Patent Laid-Open No. 1996-511274 (November 26, 1996) Japanese Patent Laid-Open No. 2015-536898 (2015.12.24)

The main object of the present invention is to solve the above-mentioned problems, and it is possible to increase productivity by shortening the production time of bis (fluorosulfonyl) imide alkali metal salt even at low temperatures, and at the same time, high-purity bis (fluorosulfonyl) It is an object of the present invention to provide a method for preparing an alkali metal imide salt capable of producing the alkali metal imide salt in high yield.

In order to achieve the above object, in one embodiment of the present invention, bis (fluorosulfonyl) imide and an alkali metal compound are mixed and reacted in a co-solvent to obtain bis (fluorosulfonyl) imide alkali metal salt It provides a method for preparing a bis (fluorosulfonyl) imide alkali metal salt, characterized in that the co-solvent is a mixture of a carbonate-based solvent and a nitrile-based solvent.

In a preferred embodiment of the present invention, the carbonate-based solvent is ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl propyl carbonate, methyl propyl carbonate, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate , 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, it may be characterized in that it is selected from the group consisting of vinyl ethylene carbonate and fluoroethylene carbonate.

In a preferred embodiment of the present invention, the nitrile solvent is acetonitrile, propionitrile, butyronitrile, t-butyl cyanide, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbon Nitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, 2-chlorobenozonitrile, 4-chlorobenzonitrile, dichlorobenzonitrile, trichlorobenzonitrile, At least one selected from the group consisting of 2-chloro-4-fluorobezo nitrile, 4-chloro-2-fluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile and 4-fluorophenylacetonitrile that can be characterized.

In a preferred embodiment of the present invention, the co-solvent may be characterized in that the weight ratio of the carbonate-based solvent and the nitrile-based solvent is 80: 20 to 95: 5 by weight.

In a preferred embodiment of the present invention, the alkali metal compound may be characterized in that at least one selected from the group consisting of LiCl, Nacl, RbCl, CsCl, LiF, NaF, RbF and CsF.

In a preferred embodiment of the present invention, the alkali metal compound may be characterized in that LiF and / or LiCl.

In a preferred embodiment of the present invention, the molar ratio of the alkali metal compound to the bis(fluorosulfonyl)imide may be 0.9 to 1.1.

In a preferred embodiment of the present invention, the reaction may be performed at 5 ° C. to 30 ° C. for 1 hour to 10 hours.

In a preferred embodiment of the present invention, the cosolvent may be mixed in an amount of 300 parts by weight to 1000 parts by weight based on 100 parts by weight of bis(fluorosulfonyl)imide.

In a preferred embodiment of the present invention, it may be characterized by including a purification step of filtering the bis(fluorosulfonyl)imide alkali metal salt generated from the reactant after the reaction.

The method for preparing bis(fluorosulfonyl)imide alkali metal salt according to the present invention comprises the steps of preparing bis(fluorosulfonyl)imide alkali metal salt by reacting bis(fluorosulfonyl)imide with an alkali metal compound. By using a co-solvent in which a carbonate-based solvent and a nitrile-based solvent are mixed in, the production time of bis(fluorosulfonyl)imide alkali metal salt can be shortened even at a low temperature reaction, thereby increasing productivity and at the same time producing high-purity products with less impurities. There is an effect of producing bis(fluorosulfonyl)imide alkali metal salt in high yield.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclatures used herein are those well known and commonly used in the art.

As used herein, the terms 'about', 'substantially', and the like are used in a sense at or approximating that number when manufacturing and material tolerances inherent in the stated meaning are given, and are intended to convey an understanding of the present invention. Accurate or absolute figures are used to help prevent exploitation by unscrupulous infringers of the disclosed disclosure.

Terms such as 'having', 'includes', 'includes' or 'has' described in this specification indicate that a feature, numerical value, step, operation, component, part or combination thereof described in the specification exists. It does not rule out the possibility that other features, values, steps, operations, components, parts, or combinations thereof not mentioned may exist or be added.

The present invention includes the step of preparing a bis(fluorosulfonyl)imide alkali metal salt by mixing and reacting bis(fluorosulfonyl)imide and an alkali metal compound in a co-solvent, wherein the co-solvent is a carbonate-based solvent and a method for preparing an alkali metal salt of bis(fluorosulfonyl)imide, which is a co-solvent in which a nitrile-based solvent is mixed.

More specifically, the method for preparing bis(fluorosulfonyl)imide alkali metal salt according to the present invention is a mixture of bis(fluorosulfonyl)imide and alkali at low temperature in the presence of a co-solvent in which a carbonate-based solvent and a nitrile-based solvent are mixed. By reacting a metal compound to produce bis(fluorosulfonyl)imide alkali metal salt, the production time of bis(fluorosulfonyl)imide alkali metal salt can be shortened even at a low reaction temperature to increase productivity and generate impurities at the same time With a small amount, high-purity bis(fluorosulfonyl)imide alkali metal salt can be produced in high yield.

In the method for preparing bis(fluorosulfonyl)imide alkali metal salt according to the present invention, bis(fluorosulfonyl)imide as a reactant can be synthesized by a known method. As an example, a method of synthesizing bis(fluorosulfonyl)imide using a fluorinating agent with bis(halogenated sulfonyl)imide may be mentioned. At this time, as the halogen in the bis(halogenated sulfonyl)imide, Cl, Br, I, At, etc. other than F may be used.

A step of fluorinating bis(fluorosulfonyl)imide from the bis(halogenated sulfonyl)imide using a fluorinating agent will be described below. For example, a fluorination reaction of bis(halogenated sulfonyl)imide may be performed. Specifically, the method described in CA2527802, Jean' ne m. Shreeve et al., Inorg. Chem . 1998, 37(24), 6295 - 6303, etc. are mentioned. In addition, bis(halogenated sulfonyl)imide as a starting material may be commercially available or synthesized by a known method, and urea and fluorosulfonic acid described in Japanese Patent Publication No. Hei 08-511274 are used. There is also a method of synthesizing bis(fluorosulfonyl)imide by doing so.

In addition, the alkali metal compound in the production method of the present invention is a chloride such as LiCl, NaCl, KCl, RbCl, CsCl; fluorides such as LiF, NaF, KF, RbF, and CsF; etc. can be used, and among them, LiCl and/or LiF are most preferable.

When the alkali metal compound is LiCl and/or LiF, since the boiling point of HCl or HF, which is a by-product in the reaction of bis(fluorosulfonyl)imide with an alkali metal compound, is low, bis(fluorosulfonyl)imide Purification of the alkali metal salt is facilitated. In addition, since the metal is Li, when used in a lithium ion secondary battery, battery characteristics are excellent. Among them, LiF is more preferable.

In the reaction between the bis(fluorosulfonyl)imide and the alkali metal compound, the molar ratio of the alkali metal compound to the bis(fluorosulfonyl)imide may be 0.9 to 1.1, preferably 0.95 to 1.05. When the molar ratio of the alkali metal compound to bis(fluorosulfonyl)imide satisfies the above range, an equivalent amount or less of the alkali metal compound is used for the reaction, but the remaining unreacted alkali metal compound can be suppressed.

Meanwhile, the reaction solvent used in the reaction between the bis(fluorosulfonyl)imide and the alkali metal compound is a co-solvent in which a carbonate-based solvent and a nitrile-based solvent are mixed, and the carbonate-based solvent used as the co-solvent is ethylmethyl carbonate , dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl propyl carbonate, methyl propyl carbonate, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, It may be at least one selected from the group consisting of 2,3-pentylene carbonate, vinylene carbonate, vinylethylene carbonate and fluoroethylene carbonate, preferably ethylmethyl carbonate, propylene carbonate and dimethyl carbonate.

In addition, the nitrile solvent used as the cosolvent is acetonitrile, propionitrile, butyronitrile, t-butyl cyanide, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, 2-chlorobenozonitrile, 4-chlorobenzonitrile, dichlorobenzonitrile, trichlorobenzonitrile, 2- It may be one or more selected from the group consisting of chloro-4-fluorobezo nitrile, 4-chloro-2-fluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile and 4-fluorophenylacetonitrile, , preferably acetonitrile, butyronitrile and propionitrile.

In this case, the carbonate-based solvent and the nitrile-based solvent may have a weight ratio of 80:20 to 95:5, preferably 85:15 to 90:10.

In addition, the cosolvent may be mixed in an amount of 300 parts by weight to 1000 parts by weight, preferably 500 parts by weight to 700 parts by weight, based on 100 parts by weight of the bis(fluorosulfonyl)imide.

Such a co-solvent is used in the reaction of bis(fluorosulfonyl)imide and an alkali metal compound by mixing a nitrile-based solvent with a carbonate-based solvent, thereby shortening the reaction time even in a low-temperature reaction, thereby increasing productivity and at the same time reducing low High purity bis(fluorosulfonyl)imide alkali metal salt can be produced due to low impurity formation due to the reaction temperature.

The reaction of bis(fluorosulfonyl)imide and an alkali metal compound mixed in the co-solvent phase is performed at 5 ° C to 30 ° C for 1 hour to 10 hours, preferably at 10 ° C to 15 ° C for 3 hours to 5 hours. can be done

When the reaction temperature is less than 5 ℃, a problem in that the reactivity is lowered occurs, and when it exceeds 40 ℃, the reaction product is decomposed and the impurity content may increase. In addition, when the reaction time is less than 1 hour, the reaction does not proceed sufficiently, resulting in a decrease in yield, and when the reaction time exceeds 10 hours, reaction stability is deteriorated and the impurity content increases, resulting in a decrease in purity. In addition, the reaction pressure can be carried out in any case, such as high pressure, normal pressure, and reduced pressure.

Meanwhile, the order of reaction and mixing of the bis(fluorosulfonyl)imide and the alkali metal compound in the cosolvent phase is not particularly limited, but the alkali metal compound is added to the mixture of the cosolvent and the bis(fluorosulfonyl)imide The reaction may be performed while adding, or the reaction may be performed while adding bis(fluorosulfonyl)imide to a mixture of the co-solvent and the alkali metal compound. In addition, the reaction may be performed while adding a mixture of the reaction solvent of the other of the co-solvents and an alkali metal compound to a mixture of the reaction solvent of one of the above co-solvents and bis(fluorosulfonyl)imide. The reaction may be carried out while adding a mixture of the other reaction solvent and bis(fluorosulfonyl)imide among the co-solvents to the mixture of the reaction solvent and the alkali metal compound. It is also possible to start the reaction after mixing the bis(fluorosulfonyl)imide, an alkali metal compound, and a co-solvent.

Since the reaction between the bis(fluorosulfonyl)imide and the alkali metal compound generates hydrogen halide, which is a volatile substance, as a by-product in the process, by discharging and removing the volatile substance, which is a by-product, generated during the reaction process, bis ( The reaction between the fluorosulfonyl)imide and the alkali metal compound can be promoted, and the purification step described later can be efficiently performed.

The purification step is a step of filtering the solid bis(fluorosulfonyl)imide alkali metal salt produced after the reaction from the reactants, and filtering the reactants after the reaction to obtain bis(fluorosulfonyl)imide as the final product from the reactants. Alkali metal salts can be obtained. In addition, the purification step may include known solid precipitation such as crystallization other than filtration, washing, distillation, concentration, and the like.

Filtration in the purification step can be performed by pressure filtration or suction filtration, etc., and any filter that can be used in the art can be used without limitation as long as it is a filter that can be used in the filtration, and one example is a fluororesin such as PTFE. , stainless steel fibers, polyolefins such as polyethylene, ultra-high density polyethylene, and polypropylene, nylon, cellulose fibers, glass fibers, silica fibers, polycarbonate, cotton, polyethersulfone, and cellulose acetate. there is. Among these, fluororesins, stainless steel fibers, and polyolefins are preferable, and fluororesins, stainless steel fibers, and the like are more preferable.

In addition, the concentration of the purification step may be carried out in a conventional manner. For example, it can be carried out using a rotary vacuum evaporator, and the concentration time is carried out for 1 hour or more, and the appropriate time is preferably determined by looking at the degree of progress of the concentration. If solidification is performed after the co-solvent is over-concentrated, the yield of the final product is lowered, and if solidification is performed in a less concentrated state, it is difficult to obtain the final product because solids are not produced, and the yield may decrease.

In the manufacturing method according to the present invention, the bis(fluorosulfonyl)imide alkali metal salt obtained in the purification step may be used as a product as it is, but in order to increase stability during storage and facilitate distribution of the product, bis(fluorosulfonyl)imide A pulverization step capable of pulverizing the sulfonyl)imide alkali metal salt may also be included. In addition, in the case of obtaining a bis(fluorosulfonyl)imide alkali metal salt in a solid state in the purification step, the obtained solid may be dried in a drying device as it is, and bis(fluorosulfonyl)imide alkali metal salt After dissolving the metal salt in a solvent, it can be applied to drying and powderization processes.

The bis(fluorosulfonyl)imide alkali metal salt prepared by this preparation method is bis(fluorosulfonyl)imide lithium salt (LiFSI), bis(fluorosulfonyl)imide sodium salt (NaFSI), bis (fluorosulfonyl)imide potassium salt (KFSI) and the like, preferably bis(fluorosulfonyl)imide lithium salt.

The bis(fluorosulfonyl)imide alkali metal salt can be usefully used as a material for an ion conductor constituting electrochemical devices such as primary batteries and secondary batteries.

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

<Example 1>

A co-solvent in which 980 g of ethyl methyl carbonate (EMC, A) and 110 g of acetonitrile (ACN, B) were mixed in a four-neck Teflon reaction vessel, 26 g of LiF (1.0 mol) and HFSI [bis(fluorosulfonyl ) imide] was mixed with 181 g (1.0 mol), and the reaction was carried out while stirring the mixture at 10 ° C. for 3 hours under normal pressure. After the reaction, the reaction product was filtered under pressure using a PTFE filter paper, and the filtrate was washed with 90 g of ethyl methyl carbonate (EMC). Thereafter, the washing solution and the filtrate obtained by washing the filtrate were concentrated under reduced pressure at 50 ° C. to 50 Torr, crystallized by adding 360 g of toluene to the concentrated residue, filtered, and dried under reduced pressure to obtain the final product, LiFSI [bis(fluoro Rosulfonyl)imide lithium salt] 166 g was obtained. The yield of the final product obtained above is shown in Table 1.

<Examples 2 to 5>

LiFSI [bis (fluorosulfonyl) imide lithium salt] was prepared in the same manner as in Example 1, but LiFSI [bis (fluorosulfonyl) imide lithium salt was prepared by changing the conditions shown in Table 1, The yield of the final product obtained above is shown in Table 1.

<Comparative Examples 1 to 4>

LiFSI [bis (fluorosulfonyl) imide lithium salt] was prepared in the same manner as in Example 1, but LiFSI [bis (fluorosulfonyl) imide lithium salt was prepared by changing the conditions shown in Table 1, The yield of the final product obtained above is shown in Table 1.

division reactant reaction conditions transference number(%) Carbonate solvent type (A) nitrile
Solvent type (B) solvent weight
ratio
(A:B) reaction temperature
(℃) reaction time
(hr) Example 1 EMC ACN 90:10 10 3 89 Example 2 DMC ACN 90:10 10 4 86 Example 3 PC ACN 90:10 10 4 87 Example 4 DMC BN 90:10 10 4 84 Example 5 EMC PCN 90:10 10 4 87 Comparative Example 1 EMC - 100:0 10 9 81 Comparative Example 2 - ACN 0:100 10 12 72 Comparative Example 3 EMC ACN 70:30 10 5 77 Comparative Example 4 EMC ACN 98:2 10 9 82 EMC: ethyl methyl carbonate
DMC: Dimethyl carbonate
PC: Propylene carbonate
ACN: Acetonitrile
BN: Butyronitrile
PCN: Propionitrile

As shown in Table 1, it can be seen that Examples 1 to 5 tend to have slightly longer reaction times and lower yields than Comparative Examples 1 to 4, which are out of a single solvent or a certain weight ratio.

Therefore, since the method for preparing bis(fluorosulfonyl)imide alkali metal salt according to the present invention uses a co-solvent and the reaction proceeds in a relatively short time even at a low temperature, productivity can be increased while reducing the generation of impurities.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and it is possible to make various modifications and practice within the scope of the claims and the detailed description of the invention and the accompanying drawings, and this is also the present invention. It is natural to fall within the scope of

Claims (7)

Mixing and reacting bis(fluorosulfonyl)imide and an alkali metal compound in a co-solvent phase to prepare a bis(fluorosulfonyl)imide alkali metal salt,
The co-solvent is a method for producing a bis(fluorosulfonyl)imide alkali metal salt, characterized in that a co-solvent in which a carbonate-based solvent and a nitrile-based solvent are mixed in a weight ratio of 80: 20 to 95: 5.
According to claim 1,
The carbonate-based solvent is ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl propyl carbonate, methyl propyl carbonate, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, At least one selected from the group consisting of 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, vinylethylene carbonate and fluoroethylene carbonate,
The nitrile solvent is acetonitrile, propionitrile, butyronitrile, t-butyl cyanide, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, 2-chlorobenozonitrile, 4-chlorobenzonitrile, dichlorobenzonitrile, trichlorobenzonitrile, 2-chloro-4-fluorobezo At least one selected from the group consisting of nitrile, 4-chloro-2-fluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile and 4-fluorophenylacetonitrile, Method for producing phonyl) imide alkali metal salt.
According to claim 1,
The alkali metal compound is bis (fluorosulfonyl) imide alkali metal salt, characterized in that at least one selected from the group consisting of LiCl, Nacl, RbCl, CsCl, LiF, NaF, RbF and CsF Manufacturing method.
According to claim 1,
The alkali metal compound is a method for producing a bis (fluorosulfonyl) imide alkali metal salt, characterized in that LiF and / or LiCl.
According to claim 1,
Method for producing bis (fluorosulfonyl) imide alkali metal salt, characterized in that the molar ratio of the alkali metal compound to the bis (fluorosulfonyl) imide is 0.9 to 1.1.
According to claim 1,
The reaction is a method for producing a bis (fluorosulfonyl) imide alkali metal salt, characterized in that carried out at 5 ℃ ~ 30 ℃ for 1 hour to 10 hours.
According to claim 1,
The co-solvent is a method for producing a bis (fluorosulfonyl) imide alkali metal salt, characterized in that mixed with 300 parts by weight to 1000 parts by weight based on 100 parts by weight of bis (fluorosulfonyl) imide.