Preparation method of sodium bis (ethoxy) sulfonyl imide and sodium bis (fluorosulfonyl) imide

Abstract

The invention relates to a preparation method of sodium bis (ethoxysulfonyl) imide and sodium bis (fluorosulfonyl) imide, and belongs to the technical field of sodium ion battery additives. The preparation method disclosed by the invention comprises the following steps: (1) reacting bis (chlorosulfonyl) imide acid and sodium ethoxide in an organic solvent to prepare bis (ethoxy) sulfonyl) imide acid; and (2) carrying out reaction on the diethoxy sulfonyl imide acid and sodium chloride in an organic solvent to prepare the diethoxy sulfonyl imide sodium. According to the method, bis (chlorosulfonyl) imide acid and sodium ethoxide are adopted as raw materials to synthesize bis (ethoxy) sulfonyl imide acid, reaction is fast, side reactions are few, and bis (ethoxy) sulfonyl imide acid can be directly used for the next step of reaction without purification. The sodium diethoxy sulfonyl imide is synthesized by taking the diethoxy sulfonyl imide acid and the sodium chloride as raw materials, a catalyst does not need to be added in the reaction process, the reaction raw material sodium chloride is a common chemical material, a byproduct hydrogen chloride generated by the reaction can be absorbed by sodium hydroxide alkali liquor, and the generated sodium chloride can be used for the reaction.

Description

Technical Field

[0001] The invention relates to a preparation method of sodium bisethoxysulfonyl imide and sodium bisfluorosulfonyl imide, belonging to the technical field of sodium ion battery additives. Background Art

[0002] Lithium-ion batteries are one of the important energy storage products in consumer electronics and electric vehicles. However, with the crazy growth of lithium prices, the cost pressure of lithium-ion batteries has gradually become prominent. Sodium-ion batteries have similar working principles to lithium-ion batteries, and compared with metallic lithium, metallic sodium is abundant, widely distributed, and cheap. Therefore, sodium-ion batteries have attracted much attention in recent years.

[0003] Sodium ion battery is a secondary battery that mainly relies on the movement of sodium ions between the positive and negative electrodes to work. Therefore, the electrolyte is a key factor in determining the thermodynamics and kinetics of the electrode-electrolyte interface reaction. Currently known electrolyte sodium salts include sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide and sodium difluorooxalatoborate. Among them, sodium bis(fluorosulfonyl)imide has high application value due to its advantages of high conductivity, excellent stability and high and low temperature performance.

[0004] At present, the preparation method of sodium bis(fluorosulfonyl)imide is basically the same as that of lithium bis(fluorosulfonyl)imide, and generally has the problems of long synthesis route, water, acidic or toxic and explosive gas produced in the synthesis of sodium salt, and complicated crystallization and purification. The Chinese invention patent with application number CN115028146A discloses a preparation method of sodium bis(fluorosulfonyl)imide, comprising the following steps: (1) adding aminosulfonic acid and fluorosulfonic acid into a reaction kettle, and heating the mixture of the two to 50-60°C, introducing carbonyl fluoride gas, stopping introducing carbonyl fluoride gas when the solid aminosulfonic acid is completely reacted and dissolved to the reaction liquid being clear, heating to 70-120°C for reaction, exhausting gas, obtaining a mixture, and subjecting to vacuum distillation to obtain high-purity bis(fluorosulfonyl)imide; (2) introducing an alcohol solution of sodium alkoxide and bis(fluorosulfonyl)imide into a microchannel reactor to mix and form salt to obtain an alcohol solution of sodium bis(fluorosulfonyl)imide, and then filtering-concentrating-stripping crystallization-solid-liquid separation-washing-drying to obtain sodium bis(fluorosulfonyl)imide crystals. However, the preparation method uses toxic gas carbonyl fluoride, which is difficult to obtain and expensive. Therefore, exploring new raw materials for the preparation of sodium bis(fluorosulfonyl)imide is of great significance for reducing the production cost of sodium ion batteries and expanding their application range. Summary of the invention

[0005] The first object of the present invention is to provide a method for preparing sodium bisethoxysulfonyl imide to solve the problem that the preparation of sodium bisfluorosulfonyl imide in the prior art contains toxic substances in the reaction raw materials and is difficult to prepare.

[0006] The second object of the present invention is to provide a method for preparing sodium bis(fluorosulfonyl)imide to solve the problem that the preparation of sodium bis(fluorosulfonyl)imide in the prior art contains toxic substances in the reaction raw materials and is difficult to prepare.

[0007] In order to achieve the above object, the technical scheme of a method for preparing sodium bis(ethoxy)sulfonyl imide in the present invention is:

[0008] A method for preparing sodium bis(ethoxysulfonylimide) comprises the following steps:

[0009] (1) Bis(chloro)sulfonyl imide acid and sodium ethoxide react in an organic solvent to prepare bis(ethoxy)sulfonyl imide acid;

[0010] (2) Bis(ethoxy)sulfonylimide acid and sodium chloride react in an organic solvent to prepare sodium bis(ethoxy)sulfonylimide.

[0011] The beneficial effect of the above technical scheme is that the preparation method of sodium bisethoxysulfonyl imide of the present invention is a pioneering invention, wherein bisethoxysulfonyl imide acid is synthesized with bischlorosulfonyl imide acid and sodium ethoxide as raw materials, and bisethoxysulfonyl imide acid is reacted with sodium chloride to generate sodium bisethoxysulfonyl imide, and the byproduct sodium chloride of the first step is purified and used to synthesize sodium bisethoxysulfonyl imide. The present invention adopts bischlorosulfonyl imide acid and sodium ethoxide as raw materials to synthesize bisethoxysulfonyl imide acid, which has fast reaction, few side reactions, and can be directly used for the next step reaction without purification. While sodium bisethoxysulfonyl imide is synthesized with bisethoxysulfonyl imide acid and sodium chloride as raw materials, no catalyst needs to be added during the reaction, and the reaction raw material sodium chloride is a common chemical material, which is cheap, and the byproduct hydrogen chloride generated by the reaction can be absorbed by sodium hydroxide lye, and the generated sodium chloride can be used for reaction, so as to realize the circular reaction and reduce the three wastes.

[0012] As a further improvement, the molar ratio of the bischlorosulfonyl imide acid to sodium ethoxide in step (1) is 1:(2.5-4.0).

[0013] The beneficial effect of the above technical solution is that in the reaction process of bischlorosulfonyl imide acid and sodium ethoxide in step (1), the sodium ethoxide is excessive, which can effectively ensure the complete reaction of bischlorosulfonyl imide acid, thereby ensuring the amount of the final reaction product.

[0014] As a further improvement, the molar ratio of the bis-ethoxysulfonyl imide acid to sodium chloride in step (2) is 1:(1.2-2.6).

[0015] As a further improvement, the reaction temperature in step (1) is -10 to 5°C.

[0016] As a further improvement, the reaction temperature in step (2) is 35-40°C.

[0017] As a further improvement, the organic solvent is dichloromethane.

[0018] The beneficial effect of the above technical solution is that: the present invention uses dichloromethane as the organic solvent in the reaction process, which has the advantage of a low boiling point, is conducive to the purification of subsequent reaction products, and there is no solvent residue in the purified final product, which helps to improve the purity of the product and reduce impurities.

[0019] Preferably, the molar ratio of the bischlorosulfonyl imide acid to dichloromethane in step (1) is 1:(2.0-4.0).

[0020] As a further improvement, the bischlorosulfonyl imide acid in step (1) is subjected to a purification step before the reaction.

[0021] The beneficial effect of the above technical solution is that the purification of bischlorosulfonyl imide acid helps to reduce the impurities in the bisethoxysulfonyl imide acid, the product of the first step reaction, so that it can be used as a raw material for the second step reaction without purification.

[0022] As a further improvement, the purification is cooling crystallization of bischlorosulfonyl imide acid, removing the non-crystallized liquid, and heating and melting the crystallized solid. As a further improvement, the cooling crystallization is crystallization at -10 to 5°C for 4 to 8 hours.

[0023] The beneficial effect of the above technical solution is that the cooling crystallization method of the present invention is used to purify bischlorosulfonyl imide acid, which has the advantages of simple purification method, basically zero material loss, and uncrystallized liquid can be recycled into the next batch.

[0024] In order to achieve the above object, the technical scheme of a method for preparing sodium bis(fluorosulfonyl)imide in the present invention is:

[0025] A method for preparing sodium bis(fluorosulfonyl)imide comprises the following steps:

[0026] (1) Bis(chloro)sulfonyl imide acid and sodium ethoxide react in an organic solvent to prepare bis(ethoxy)sulfonyl imide acid;

[0027] (2) reacting bis-ethoxysulfonylimide acid and sodium chloride in an organic solvent to prepare bis-ethoxysulfonylimide sodium;

[0028] (3) Sodium bis(ethoxysulfonylimide) and fluoromethane react in a good solvent of sodium bis(ethoxysulfonylimide) to prepare sodium bis(fluorosulfonylimide).

[0029] The beneficial effect of the above technical scheme is that: the present invention uses bischlorosulfonyl imide acid and sodium ethoxide as raw materials to synthesize bisethoxysulfonyl imide acid, and the bisethoxysulfonyl imide acid reacts with sodium chloride to generate sodium bisethoxysulfonyl imide, and then the sodium bisethoxysulfonyl imide reacts with fluoromethane to generate sodium bisfluorosulfonyl imide. The raw materials in the preparation method of the present invention are cheap, the reaction process is simple, the controllability is strong, the generated sodium bisfluorosulfonyl imide is high in purity, meets the use requirements of sodium ion battery electrolyte salt, and is suitable for popularization and use.

[0030] As a further improvement, the molar ratio of sodium bis(ethoxysulfonyl)imide to fluoromethane in step (3) is 1:(1.2-4.0).

[0031] As a further improvement, the reaction temperature in step (3) is 40-80°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the hydrogen spectrum of the purified bischlorosulfonyl imide acid in Example 1 of the present invention;

[0033] Figure 2 This is the carbon spectrum of the purified bischlorosulfonyl imide acid in Example 1 of the present invention;

[0034] Figure 3 is the hydrogen spectrum of the product in Example 1 of the present invention in heavy water;

[0035] Figure 4 The XRD spectrum of the slag material filtered by reaction in Example 1 of the present invention;

[0036] Figure 5 The fluorine spectrum of sodium bis(fluorosulfonyl)imide prepared by the reaction in Example 4 of the present invention in deuterated acetonitrile. DETAILED DESCRIPTION

[0037] The invention provides a method for preparing sodium bisethoxysulfonyl imide, and sodium bisethoxysulfonyl imide is an intermediate product for preparing sodium bisfluorosulfonyl imide, and the purity and quality of the sodium bisfluorosulfonyl imide have an important influence on the quality of the sodium bisfluorosulfonyl imide.

[0038] The present invention uses bischlorosulfonyl imide acid and sodium ethoxide as raw materials to synthesize bisethoxysulfonyl imide acid, and the bisethoxysulfonyl imide acid reacts with sodium chloride to generate bisethoxysulfonyl sodium imide. The byproduct sodium chloride in the first step is purified and used to synthesize bisethoxysulfonyl sodium imide. The present invention uses bischlorosulfonyl imide acid and sodium ethoxide as raw materials to synthesize bisethoxysulfonyl imide acid, which has fast reaction, few side reactions, and can be directly used for the next step reaction without purification. While using bisethoxysulfonyl imide acid and sodium chloride as raw materials to synthesize bisethoxysulfonyl sodium imide, no catalyst needs to be added during the reaction, and the reaction raw material sodium chloride is a common chemical material with low price, and the byproduct hydrogen chloride generated by the reaction can be absorbed by sodium hydroxide lye, and the generated sodium chloride can be used for reaction, so as to realize a cyclic reaction and reduce the three wastes.

[0039] Furthermore, the present invention also provides a method for preparing sodium bisfluorosulfonyl imide, wherein bischlorosulfonyl imide acid and sodium ethoxide are used as raw materials to synthesize bisethoxysulfonyl imide acid, bisethoxysulfonyl imide acid is reacted with sodium chloride to generate sodium bisethoxysulfonyl imide, and then sodium bisethoxysulfonyl imide is reacted with fluoromethane to generate sodium bisfluorosulfonyl imide. The raw materials in the preparation method of the present invention are cheap, the reaction process is simple, the controllability is strong, the generated sodium bisfluorosulfonyl imide is high in purity, meets the use requirements of sodium ion battery electrolyte salt, and is suitable for promotion and use.

[0040] Specifically, the equations involved in the present invention are as follows:

[0041]

[0042] To further describe the present invention, it should be noted that, under the premise of no conflict, the embodiments or technical features described below can be arbitrarily combined to form new embodiments. The equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following embodiments are all conventional methods in the art unless otherwise specified.

[0043] 1. A specific embodiment of a method for preparing sodium bis(ethoxysulfonylimide)

[0044] Example 1

[0045] The preparation method of sodium bis(ethoxysulfonylimide) in this embodiment is specifically implemented as follows:

[0046] 1. Purification of bis(chlorosulfonyl)imide acid

[0047] 2000 g of bischlorosulfonyl imide acid was added to a 3-liter three-necked flask with a jacket and a bottom discharge port, and the temperature was gradually lowered to -10°C. When the temperature was reached, crystallization was performed for 6 hours. The bottom discharge port was opened to discharge the uncrystallized liquid, and the valve was closed. The remaining crystalline solid was heated and completely melted to obtain 1932.4 g of purified bischlorosulfonyl imide acid with a yield of 96.62%.

[0048] 2. Preparation of bis(ethoxy)sulfonyl imide acid

[0049] In a 2-liter three-necked flask with a mechanical stirrer and a heating and cooling device, 1070 g of dichloromethane and 425 g of sodium ethoxide (6.25 mol) were added, the temperature was lowered to 5°C, and 535 g of the bischlorosulfonyl imide acid (2.5 mol) purified in step 1 was gradually added dropwise. After the reaction was completed, the solid-liquid separation (excess sodium ethoxide and sodium chloride generated by the reaction were removed) was performed, and the liquid was set aside.

[0050] 3. Preparation of sodium bis(ethoxysulfonylimide)

[0051] 1070 g of methylene chloride and 175.2 g of sodium chloride (2.99 mol) were added to a 3-liter three-necked flask with a mechanical stirrer and a heating and refrigeration device, and the temperature was raised to 40° C. The liquid after solid-liquid separation in step 2 was gradually added dropwise (the addition amount of bisethoxysulfonyl imide acid in step 2 was 2.5 mol, and the amount of sodium ethoxide used in the reaction was excessive. According to the chemical reaction equation, the bisethoxysulfonyl imide acid added in this step was theoretically 2.5 mol), and the acidity was tested by sampling. When the reaction end point was reached (the acidity was below 100 ppm), the reaction was stopped, solid-liquid separation was performed, and the solid was washed with methylene chloride and dried to obtain a crude product of sodium bisethoxysulfonyl imide, which contained excessive sodium chloride. The crude sodium bisethoxysulfonyl imide was first redissolved in ether (sodium bisethoxysulfonyl imide is soluble in ether, while sodium chloride is insoluble in ether), then filtered to remove the sodium chloride, and dichloromethane was added to the filtrate for crystallization, and finally filtered, washed and dried to obtain 470.1 g of sodium bisethoxysulfonyl imide product with a total yield of 84.7%.

[0052] The hydrogen and carbon spectra of the purified bis(chlorosulfonyl)imide acid in step 1 are as follows: Figure 1 , Figure 2 As shown, the hydrogen and carbon spectra of the purified bischlorosulfonyl imide acid in Example 2 and Example 3 are basically the same, and only the free chlorine may be slightly different.

[0053] The hydrogen spectrum of the product prepared after step 3 reaction in heavy water is as follows Figure 3 As shown, the XRD spectrum of the filtered slag in step 3 is as follows Figure 4 As shown. Figure 3 It can be seen from the figure that the final product prepared has a quartet of methylene and a triplet of methyl in heavy water; Figure 4It can be seen that the residue filtered by the reaction is mainly sodium chloride after XRD test, which indirectly proves that the ethoxy group replaces the chlorine of dichloroethylene and produces sodium chloride as a by-product.

[0054] Example 2

[0055] The preparation method of sodium bis(ethoxysulfonylimide) in this embodiment is specifically implemented as follows:

[0056] 1. Purification of bis(chlorosulfonyl)imide acid

[0057] 2000 g of bischlorosulfonyl imide acid was added to a 3-liter three-necked flask with a jacket and a bottom discharge port, and the temperature was gradually lowered to 5°C. When the temperature was reached, crystallization was performed for 4 hours. The bottom discharge port was opened to discharge the uncrystallized liquid, and the valve was closed. The remaining crystalline solid was heated and completely melted to obtain 1926.1 g of purified bischlorosulfonyl imide acid with a yield of 96.31%.

[0058] 2. Preparation of bis(ethoxy)sulfonyl imide acid

[0059] In a 3-liter three-necked flask with a mechanical stirrer and a heating and cooling device, 1605 g of dichloromethane and 680 g of sodium ethoxide (10 mol) were added, the temperature was lowered to -10°C, and 535 g of the bischlorosulfonyl imide acid (2.5 mol) purified in step 1 was gradually added dropwise. After the reaction was completed, the solid-liquid separation (excess sodium ethoxide and sodium chloride generated by the reaction were removed) was performed, and the liquid was set aside.

[0060] 3. Preparation of sodium bis(ethoxysulfonylimide)

[0061] 1605g of methylene chloride and 379.6g of sodium chloride (6.49mol) were added to a 5-liter three-necked flask with a mechanical stirrer and a heating and refrigeration device, and the temperature was raised to 35°C. The liquid after solid-liquid separation in step 2 was gradually added dropwise (the addition amount of bisethoxysulfonyl imide acid in step 2 was 2.5mol, and the amount of sodium ethoxide in the reaction was excessive. According to the chemical reaction equation, the bisethoxysulfonyl imide acid added in this step was theoretically 2.5mol), and the acidity was tested by sampling. When the reaction end point was reached (the acidity was below 100ppm), the reaction was stopped, and solid-liquid separation was performed. The solid was washed with methylene chloride and the solid was dried to obtain a crude product of sodium bisethoxysulfonyl imide, which contained excessive sodium chloride. A crude product of sodium bisethoxysulfonyl imide was obtained, which contained excessive sodium chloride. The crude sodium bisethoxysulfonyl imide was first redissolved in ether (sodium bisethoxysulfonyl imide is soluble in ether, while sodium chloride is insoluble in ether), then filtered to remove the sodium chloride, and dichloromethane was added to the filtrate for crystallization, and finally filtered, washed and dried to obtain 454.5 g of sodium bisethoxysulfonyl imide product with a total yield of 81.9%.

[0062] Example 3

[0063] The preparation method of sodium bis(ethoxysulfonylimide) in this embodiment is specifically implemented as follows:

[0064] 1. Purification of bis(chlorosulfonyl)imide acid

[0065] 2000 g of bischlorosulfonyl imide acid was added to a 3-liter three-necked flask with a jacket and a bottom discharge port, and the temperature was gradually lowered to 0°C. When the temperature was reached, crystallization was performed for 8 hours. The bottom discharge port was opened to discharge the uncrystallized liquid, and the valve was closed. The remaining crystalline solid was heated and completely melted to obtain 1928.4 g of purified bischlorosulfonyl imide acid with a yield of 96.42%.

[0066] 2. Preparation of bis(ethoxy)sulfonyl imide acid

[0067] In a 5-liter three-necked flask with a mechanical stirrer and a heating and cooling device, 2140 g of dichloromethane and 510 g of sodium ethoxide (7.5 mol) were added, the temperature was lowered to -5°C, and 535 g of the bischlorosulfonyl imide acid (2.5 mol) purified in step 1 was gradually added dropwise. After the reaction was completed, the solid-liquid separation (excess sodium ethoxide and sodium chloride generated by the reaction were removed) was performed, and the liquid was set aside.

[0068] 3. Preparation of sodium bis(ethoxysulfonylimide)

[0069] 2140g of methylene chloride and 292g of sodium chloride (4.99mol) were added to a 5-liter three-necked flask with a mechanical stirrer and a heating and refrigeration device, and the temperature was raised to 38°C. The liquid after solid-liquid separation in step 2 was gradually added dropwise (the addition amount of bisethoxysulfonyl imide acid in step 2 was 2.5mol, and the amount of sodium ethoxide used in the reaction was excessive. According to the chemical reaction equation, the bisethoxysulfonyl imide acid added in this step was theoretically 2.5mol), and the acidity was tested by sampling. When the reaction end point was reached (the acidity was below 100ppm), the reaction was stopped, solid-liquid separation was performed, and the solid was washed with methylene chloride and dried to obtain a crude product of sodium bisethoxysulfonyl imide, which contained excessive sodium chloride. The crude sodium bisethoxysulfonyl imide was first redissolved in ether (sodium bisethoxysulfonyl imide is soluble in ether, while sodium chloride is insoluble in ether), then filtered to remove the sodium chloride, and dichloromethane was added to the filtrate for crystallization, and finally filtered, washed and dried to obtain 457.3 g of sodium bisethoxysulfonyl imide product with a total yield of 82.4%.

[0070] In other embodiments, the reaction between bischlorosulfonyl imide acid and sodium ethoxide is not subjected to solid-liquid separation, and the reaction between bisethoxysulfonyl imide acid and sodium chloride can be directly carried out, and the amount of sodium chloride can be supplemented according to actual reaction requirements.

[0071] 2. Specific embodiment of a method for preparing sodium bis(fluorosulfonyl)imide

[0072] Example 4

[0073] The preparation method of sodium bis(fluorosulfonyl)imide in this embodiment is specifically implemented as follows:

[0074] 255 g of sodium bisethoxysulfonyl imide (1 mol) and 510 g of dimethyl carbonate (sodium bisethoxysulfonyl imide is dissolved in dimethyl carbonate) are added to a glass reaction kettle with a thermometer, a stirring device and a heating device, the air is discharged by filling with nitrogen, the temperature is raised to 60° C., 51.2 g of fluoromethane (1.5 mol) is slowly introduced, and the tail gas is absorbed and treated with a sodium hydroxide aqueous solution; the entire reaction process is monitored by nuclear magnetic resonance, and the reaction is stopped when the content of sodium bisethoxysulfonyl imide in the reaction solution is 0.1%. After concentration, dichloromethane is added to cool and crystallize, and then filtered and dried to obtain 160.1 g of high-purity sodium bisfluorosulfonyl imide solid with a yield of 78.92%.

[0075] from Figure 5 It can be seen that the final product of the reaction is sodium bis(fluorosulfonyl)imide.

[0076] Example 5

[0077] The preparation method of sodium bis(fluorosulfonyl)imide in this embodiment is specifically implemented as follows:

[0078] 255 g of sodium bisethoxysulfonyl imide (1 mol) and 510 g of dimethyl carbonate (sodium bisethoxysulfonyl imide is dissolved in dimethyl carbonate) are added to a glass reaction kettle with a thermometer, a stirring device and a heating device, the air is discharged by filling with nitrogen, the temperature is raised to 40° C., 136 g of fluoromethane (4 mol) is slowly introduced, and the tail gas is absorbed and treated with a sodium hydroxide aqueous solution; the entire reaction process is monitored by nuclear magnetic resonance, and the reaction is stopped when the content of sodium bisethoxysulfonyl imide in the reaction solution is 0.1%. After concentration, dichloromethane is added to cool and crystallize, and then filtered and dried to obtain 153.4 g of high-purity sodium bisfluorosulfonyl imide solid, with a yield of 75.62%.

[0079] Example 6

[0080] The preparation method of sodium bis(fluorosulfonyl)imide in this embodiment is specifically implemented as follows:

[0081] 255 g of sodium bis(ethoxysulfonyl)imide (1 mol) and 510 g of dimethyl carbonate (sodium bis(ethoxysulfonyl)imide is dissolved in dimethyl carbonate) are added to a glass reactor equipped with a thermometer, a stirring device and a heating device, the air is discharged by filling with nitrogen, the temperature is raised to 80° C., 40.8 g of fluoromethane (1.2 mol) is slowly introduced, and the tail gas is absorbed and treated with a sodium hydroxide aqueous solution; the entire reaction process is monitored by nuclear magnetic resonance, and the reaction is stopped when the content of sodium bis(ethoxysulfonyl)imide in the reaction solution is 0.09%. After concentration, dichloromethane is added to cool and crystallize, and then filtered and dried to obtain 156.93 g of high-purity sodium bis(fluorosulfonyl)imide solid with a yield of 77.36%.

[0082] 3. Experimental Examples

[0083] Experimental Example 1

[0084] This experimental example tests the sodium bis(ethoxysulfonylimide) products prepared in Examples 1 to 3, and the product test results of each example are shown in Table 1. The test is carried out with reference to the industry standard for lithium bis(fluorosulfonylimide) YS / T 1302-2019 "Lithium bis(fluorosulfonylimide) salt for power battery electrolyte".

[0085] Table 1 Test of sodium bis(ethoxysulfonyl)imide

[0086]

[0087]

[0088] As can be seen from Table 1, the main content of sodium bis(ethoxysulfonylimide) obtained in Examples 1 to 3 is not less than 99.96%, the water content is not higher than 35 ppm, the free acid is not higher than 50 ppm, the insoluble matter is not higher than 100 ppm, and the content of other impurity ions is extremely low.

[0089] Experimental Example 2

[0090] This experimental example tests the sodium bis(fluorosulfonyl)imide products prepared in Examples 4 to 6, and the product test results of each example are shown in Table 2. The test is carried out with reference to the industry standard for lithium bis(fluorosulfonyl)imide YS / T 1302-2019 "Lithium bis(fluorosulfonyl)imide salt for power battery electrolyte".

[0091] Table 2 Test of sodium bis(fluorosulfonyl)imide

[0092]

[0093] As can be seen from Table 2, the main content of sodium bis(fluorosulfonyl)imide obtained in Examples 4 to 6 is not less than 99.96%, the water content is not higher than 30 ppm, the free acid is not higher than 41 ppm, the insoluble matter is not higher than 100 ppm, and the content of other impurity ions is extremely low.

[0094] The test results show that the sodium bis(ethoxysulfonylimide) and sodium bis(fluorosulfonylimide) products prepared by the preparation method of the present invention have high purity, meet the use requirements of sodium ion battery electrolyte salts, and are suitable for popularization and use.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the contents of the specification of the present invention should also be included in the protection scope of the present invention.

Claims

1. A method for preparing sodium bis(ethoxysulfonylimide), characterized in that: The following steps are involved: (1) Bis(chloro)sulfonyl imide acid and sodium ethoxide react in an organic solvent to prepare bis(ethoxy)sulfonyl imide acid; (2) Bis(ethoxy)sulfonylimide acid and sodium chloride react in an organic solvent to prepare sodium bis(ethoxy)sulfonylimide.

2. The method for preparing sodium bis(ethoxy)sulfonylimide according to claim 1, wherein: The molar ratio of bis(chlorosulfonyl)imide acid to sodium ethoxide in step (1) is 1:(2.5-4.0).

3. The method for preparing sodium bis(ethoxy)sulfonylimide according to claim 1, wherein: The molar ratio of the bis(ethoxy)sulfonyl imide acid to sodium chloride in step (2) is 1:(1.2-2.6).

4. The method for preparing sodium bis(ethoxy)sulfonylimide according to claim 1, wherein: The reaction temperature in step (1) is -10~5°C.

5. The method for preparing sodium bis(ethoxy)sulfonylimide according to claim 1, wherein: The reaction temperature in step (2) is 35-40°C.

6. The method for preparing sodium bis(ethoxy)sulfonylimide according to any one of claims 1 to 5, characterized in that: The organic solvent is dichloromethane.

7. A method for preparing sodium bis(fluorosulfonyl)imide, characterized in that: The following steps are involved: (1) Bis(chloro)sulfonyl imide acid and sodium ethoxide react in an organic solvent to prepare bis(ethoxy)sulfonyl imide acid; (2) Bis(ethoxy)sulfonyl imide acid and sodium chloride react in an organic solvent to prepare sodium bis(ethoxy)sulfonyl imide; (3) Sodium bis(ethoxysulfonylimide) and fluoromethane react in a good solvent of sodium bis(ethoxysulfonylimide) to prepare sodium bis(fluorosulfonylimide).

8. The method for preparing sodium bis(fluorosulfonyl)imide according to claim 7, characterized in that: The molar ratio of sodium bis(ethoxysulfonyl)imide to fluoromethane in step (3) is 1:(1.2-4.0).

9. The method for preparing sodium bis(fluorosulfonyl)imide according to claim 7, characterized in that: The reaction temperature in step (3) is 40-80°C.

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