A method for preparing sodium bisfluorosulfonimide

Abstract

In order to overcome the problems of safety risk and high residual potassium ion content in the existing method for preparing sodium fluorosulfonimide from potassium fluorosulfonimide, the application provides a preparation method of sodium bisfluorosulfonimide, which comprises the following operation steps: a strong acid type cation exchange resin is filled in a cation exchange resin column, and the strong acid type cation exchange resin is adsorbed with sodium ions; an aqueous solution of potassium bisfluorosulfonimide is introduced into the cation exchange resin column for ion exchange, so that the potassium ions on the potassium bisfluorosulfonimide are replaced by sodium ions, and an aqueous solution containing sodium bisfluorosulfonimide is obtained; and an organic solution of sodium bisfluorosulfonimide or sodium bisfluorosulfonimide solid is prepared. The preparation method of sodium bisfluorosulfonimide provided by the application is simple in operation and high in safety, and the obtained sodium bisfluorosulfonimide is high in purity, so that the difficulty in purification is effectively reduced; and the obtained organic solution of sodium bisfluorosulfonimide can be directly used for battery electrolyte.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrolyte salt materials, and particularly relates to a preparation method of bisfluorosulfonylimide sodium. BACKGROUND

[0002] Sodium-ion batteries have outstanding advantages such as abundant resources, low price and wide distribution, and become a selectable system of energy storage systems. As an important component of the battery, the stability and safety of the electrolyte are important factors to realize the safety performance of the battery. Benefiting from the good thermal stability of sodium ions, sodium-ion batteries can achieve no fire and no explosion in safety test items such as needle puncture, extrusion, overcharge and overdischarge; in the transportation link, the sodium-ion battery can be completely discharged to realize 0V transportation, thereby reducing the safety risk of battery transportation. In addition, the sodium-ion battery can use widely available and lighter aluminum, and renewable hard carbon as the negative electrode current collector. As a new type of electrolyte salt, compared with sodium perchlorate and sodium hexafluorophosphate, the sodium-ion battery prepared by using bisfluorosulfonylimide sodium (NaFSI) as the electrolyte has higher coulomb efficiency and better cycle performance (Adv. Energy Mater., 2013, 3, 156-160).

[0003] At present, the preparation methods of NaFSI mainly include: in CN 114572945 A, bisfluorosulfonylimide (HFSI) is used to react with sodium salt to prepare NaFSI, and the reaction needs to be carried out at a low temperature and the water content in the reaction system needs to be controlled to prevent HFSI from decomposing.

[0004] In addition, among the alkali metal salts of bisfluorosulfonylimide, due to the stronger coulomb effect, the alkali metal ions with small ionic radius and high charge density are more likely to cause the decomposition of FSI - (Electrochimica Acta, 2019, 321, 134644). Compared with bisfluorosulfonylimide sodium, bisfluorosulfonylimide potassium is more stable, has lower preparation difficulty, and is easier to purify to obtain high-purity product. Therefore, a preparation route is to prepare high-purity fluorosulfonylimide sodium from potassium fluorosulfonylimide. For example, in the prior art CN 101747242 A, NaFSI is prepared by double fluorosulfonylimide potassium (KFSI) and sodium perchlorate or sodium tetrafluoroborate in an organic solvent through a double decomposition exchange reaction, but the content of residual potassium ions in the product is high, and the sodium perchlorate used and the perchloric acid generated in the reaction are explosive compounds, which have certain safety risks and are not suitable for industrial production. If bischlorosulfonylimide is directly reacted with sodium fluoride to obtain NaFSI, a large amount of toxic and corrosive gas hydrogen fluoride will be generated. SUMMARY

[0005] In view of the problems of safety risk and high residual potassium content in the existing method for preparing sodium fluorosulfonylimide from potassium fluorosulfonylimide, the application provides a preparation method of sodium bisfluorosulfonylimide.

[0006] The technical solution adopted by the application to solve the above technical problems is as follows:

[0007] The application provides a preparation method of sodium bisfluorosulfonylimide, which comprises the following operation steps:

[0008] A cation exchange resin column is provided, the cation exchange resin column is filled with strong acid type cation exchange resin, and the strong acid type cation exchange resin is adsorbed with sodium ions;

[0009] Ion exchange: the aqueous solution of potassium bisfluorosulfonylimide is introduced into the cation exchange resin column for ion exchange, the potassium ions on the potassium bisfluorosulfonylimide are replaced by sodium ions, and an aqueous solution containing sodium bisfluorosulfonylimide is obtained;

[0010] The organic solution of sodium bisfluorosulfonylimide or the solid sodium bisfluorosulfonylimide is prepared from the aqueous solution containing sodium bisfluorosulfonylimide.

[0011] Optionally, the mass concentration of potassium bisfluorosulfonylimide in the aqueous solution of potassium bisfluorosulfonylimide is 1% to 50%.

[0012] Optionally, the cation exchange resin column is prepared by the following preparation method:

[0013] After the strong acid cation exchange resin is packed into the column, the cation exchange resin column is sequentially rinsed with water, an acid solution, water, a sodium hydroxide solution or an alkaline sodium salt solution and water.

[0014] Optionally, when the cation exchange resin column is rinsed with water, the conductivity of the effluent is taken as the end marker of the rinsing;

[0015] When the cation exchange resin column is rinsed with the acid solution, the content of metal cations in the effluent is taken as the end marker of the rinsing;

[0016] When the cation exchange resin column is rinsed with the sodium hydroxide solution or the alkaline sodium salt solution, the pH of the effluent is taken as the end marker of the rinsing.

[0017] Optionally, the acid solution comprises one or more of hydrochloric acid and sulfuric acid, and the acid concentration of the acid solution is 1% to 50%.

[0018] Optionally, the alkaline sodium salt solution comprises one or more of sodium carbonate, sodium bicarbonate, sodium methoxide and sodium ethoxide, and the mass concentration of sodium hydroxide or the alkaline sodium salt in the sodium hydroxide solution or the alkaline sodium salt solution is 0.1% to 50%.

[0019] Optionally, when the sodium ion content of the effluent is <1000 ppm, the cation exchange resin column is regenerated, and the regeneration method is the same as the preparation method of the cation exchange resin column.

[0020] Optionally, the preparation of the sodium bisfluorosulfonylimide solid from the aqueous solution containing sodium bisfluorosulfonylimide comprises the following steps:

[0021] The obtained aqueous solution containing sodium bisfluorosulfonylimide is concentrated by distillation to obtain a sodium bisfluorosulfonylimide aqueous concentrate;

[0022] The first non-aqueous organic solvent is selected from an organic solvent that can form an azeotrope with water, and the distillation is carried out until the concentration of the sodium bisfluorosulfonylimide solution is >50%. The water content in the solution is tested, and if the water content in the solution is >50000 ppm, the non-aqueous organic solvent is continuously added for distillation to remove water until the water content in the solution is <50000 ppm. After filtering the solution, the first non-aqueous organic solvent is removed by distillation, and the sodium bisfluorosulfonylimide solid is obtained by drying.

[0023] Optionally, the mass concentration of the sodium bisfluorosulfonylimide aqueous concentrate is 30%-85%;

[0024] The distillation is carried out under reduced pressure, and the temperature is 5℃-80℃ and the pressure is 0-30KPa;

[0025] The first non-aqueous organic solvent is selected from one or more of pyridine, alcohol, ether, ester, nitrile, and hydrocarbon;

[0026] The drying process is controlled at a temperature of 10℃-100℃.

[0027] Optionally, the preparation of the sodium bisfluorosulfonylimide organic solution from the aqueous solution containing sodium bisfluorosulfonylimide comprises the following steps:

[0028] The obtained aqueous solution containing sodium bisfluorosulfonylimide is concentrated by distillation to obtain a sodium bisfluorosulfonylimide aqueous concentrate;

[0029] The second non-aqueous organic solvent is selected from an organic solvent that can form an azeotrope with water but is insoluble in water, and the distillation is carried out until the water content is <200 ppm based on the mass of NaFSI. The sodium bisfluorosulfonylimide organic solution is obtained.

[0030] Optionally, the mass concentration of the sodium bisfluorosulfonimide aqueous concentrated solution is 30%-85%;

[0031] The distillation is performed by reduced pressure distillation, at a temperature of 5-80℃ and a pressure of 0-30KPa.

[0032] The distillation process maintains the solution concentration at 2-60%;

[0033] The second non-aqueous organic solvent is selected from organic solvents containing at least one functional group of ester group, cyano group and ether bond.

[0034] The mass concentration of the sodium bisfluorosulfonimide organic solution is 10%-80%.

[0035] Compared with the prior art of directly preparing sodium bisfluorosulfonimide from potassium bisfluorosulfonimide through chemical reaction, the preparation method of the present application uses a cation exchange resin column with adsorbed sodium ions to treat the aqueous solution of potassium bisfluorosulfonimide, and the sodium bisfluorosulfonimide aqueous solution is prepared by ion exchange, which is simple in operation, low in preparation environment requirement, and high in safety, and the cation exchange resin and solvent can be reused. DETAILED DESCRIPTION

[0036] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0037] The present application provides a preparation method of sodium bisfluorosulfonimide, which comprises the following operation steps:

[0038] A cation exchange resin column is provided, the cation exchange resin column is filled with strong acid type cation exchange resin, and the strong acid type cation exchange resin is adsorbed with sodium ions;

[0039] Ion exchange: the aqueous solution of potassium bisfluorosulfonimide is introduced into the cation exchange resin column for ion exchange, the potassium ions on the potassium bisfluorosulfonimide are replaced by sodium ions, and the aqueous solution containing sodium bisfluorosulfonimide is obtained;

[0040] The organic solution of sodium bisfluorosulfonimide or the solid sodium bisfluorosulfonimide is prepared from the aqueous solution containing sodium bisfluorosulfonimide.

[0041] The potassium bisfluorosulfonimide is used as the initial raw material of the reaction, has the advantages of high purity and less impurities, and is beneficial to reduce the impurity content of the prepared sodium bisfluorosulfonimide.

[0042] Compared with the existing method of preparing sodium bisfluorosulfonimide by chemical reaction of potassium bisfluorosulfonimide, the present preparation method uses a cation exchange resin column with sodium ions to treat the aqueous solution of potassium bisfluorosulfonimide, and the aqueous solution of sodium bisfluorosulfonimide is prepared by ion exchange. The operation is simple, the preparation environment is low, the cation exchange resin and the solvent can be regenerated and used, the safety is high, the aqueous solution of sodium bisfluorosulfonimide obtained has high purity, and the subsequent purification operation is easy, which is beneficial to obtain sodium bisfluorosulfonimide with high purity. At the same time, compared with other organic solvents, the aqueous solution is used as the cation exchange system, which can effectively reduce the cost and avoid the introduction of impurity ions, and reduce the difficulty of subsequent waste liquid treatment.

[0043] In some embodiments, the mass concentration of the aqueous solution of potassium bisfluorosulfonimide is 1% to 50%.

[0044] Specifically, the mass concentration of the aqueous solution of potassium bisfluorosulfonimide can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 27%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 37%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 47%, 49%, or 50%.

[0045] In preferred embodiments, the mass concentration of potassium bisfluorosulfonimide in the aqueous solution of potassium bisfluorosulfonimide is 5% to 25%.

[0046] In some embodiments, the cation exchange resin column is prepared by the following preparation method:

[0047] After the strong acid cation exchange resin is packed, the cation exchange resin column is sequentially rinsed with water, an acid solution, water, a sodium hydroxide solution or an alkaline sodium salt solution, and water.

[0048] In the above operation process, the first water rinsing operation is used to remove the soluble impurities in the strong acid cation exchange resin; the acid solution rinsing operation is used to elute the impurity ions adsorbed in the strong acid cation exchange resin. At this time, the H + ions in the acid solution will be embedded in the strong acid cation exchange resin to replace other impurity ions such as Ca 2+ ions and Mg2+ Ion, Na + Ion, K + Position of the ion, restoring the ion exchange capacity of the strong acid cation exchange resin; by the second water rinse operation, for removing the residual acid of the strong acid cation exchange resin; by the sodium hydroxide or alkali sodium salt solution rinse operation, for replacing the H + Position of the ion, forming the strong acid cation exchange resin adsorbing the sodium ion, for ion exchange with the potassium bisfluorosulfonylimide; by the third water rinse operation, for removing the residual alkali of the strong acid cation exchange resin.

[0049] In some embodiments, the water rinse cation exchange resin is used with the effluent conductivity < 200 μS / cm as the rinse end marker.

[0050] In preferred embodiments, the water rinse cation exchange resin column is used with the effluent conductivity < 100 μS / cm as the rinse end marker.

[0051] In more preferred embodiments, the water rinse cation exchange resin column is used with the effluent conductivity < 50 μS / cm as the rinse end marker.

[0052] In some embodiments, the acid solution rinse cation exchange resin column is used with the effluent metal cation < 100 ppm as the rinse end marker.

[0053] In preferred embodiments, the acid solution rinse cation exchange resin column is used with the effluent metal cation < 50 ppm as the rinse end marker.

[0054] In some embodiments, the sodium hydroxide or alkali sodium salt solution rinse cation exchange resin column is used with the effluent pH > 8 as the rinse end marker.

[0055] In some embodiments, the acid solution includes one or more of hydrochloric acid and sulfuric acid, and the acid concentration of the acid solution is 1% to 50%.

[0056] In some embodiments, the acid solution is hydrochloric acid, and the acid concentration of the acid solution is 1% to 30%.

[0057] In some embodiments, the acid solution is sulfuric acid, and the acid concentration of the acid solution is 1% to 50%.

[0058] In some embodiments, the acid solution is hydrochloric acid, and the second water rinse operation is used with the effluent conductivity < 200 μS / cm, and the Cl - < 5 ppm as the rinse end marker, preferably Cl - < 2 ppm.

[0059] In some embodiments, the acid solution is sulfuric acid, the second water rinse operation is performed until the effluent conductivity is <200 μS / cm, and SO4 2- <5 ppm as an end of rinse indicator, preferably SO4 2- <2 ppm.

[0060] In some embodiments, the basic sodium salt solution comprises one or more of sodium carbonate, sodium bicarbonate, sodium methoxide, sodium ethoxide;

[0061] The mass concentration of sodium hydroxide or the basic sodium salt in the sodium hydroxide or the basic sodium salt solution is 0.1% to 50%.

[0062] In preferred embodiments, the cation exchange resin column is rinsed with a sodium hydroxide solution having a mass concentration of sodium hydroxide of 1% to 30%.

[0063] In some embodiments, when the sodium ion in the effluent is <1000 ppm in the ion exchange operation, the cation exchange resin column is regenerated, and the regeneration of the cation exchange resin column is the same as the preparation method of the cation exchange resin column.

[0064] The potassium ion adsorbed in the cation exchange resin column is eluted by the acid solution rinse operation, and the sodium ion loading capacity of the strong acid cation exchange resin is restored by the sodium hydroxide or the basic sodium salt solution rinse operation, thereby ensuring the regeneration and reuse of the cation exchange resin column.

[0065] In preferred embodiments, the sodium ion in the effluent is <500 ppm, and the cation exchange resin column is regenerated.

[0066] In more preferred embodiments, the sodium ion in the effluent is <200 ppm, and the cation exchange resin column is regenerated.

[0067] In some embodiments, the ion exchange operation is completed when the concentration of potassium ion in the effluent is lower than 6 ppm.

[0068] In preferred embodiments, the ion exchange operation is completed when the concentration of potassium ion in the effluent is lower than 3 ppm.

[0069] In more preferred embodiments, the ion exchange operation is completed when the concentration of potassium ion in the effluent is lower than 1 ppm.

[0070] In some embodiments, the ion exchange operation can be performed by passing the aqueous solution of potassium bisfluorosulfonimide through the cation exchange resin column once, or by circulating the aqueous solution of potassium bisfluorosulfonimide through the cation exchange resin column multiple times, or by connecting multiple cation exchange resin columns in series to perform multiple ion exchange operations on the aqueous solution of potassium bisfluorosulfonimide.

[0071] In some embodiments, the strong acid cation exchange resin is selected from sulfonic acid type cation exchange resin.

[0072] In one embodiment, the "preparing sodium bisfluorosulfonimide solid from an aqueous solution containing sodium bisfluorosulfonimide" comprises the following operations:

[0073] The obtained aqueous solution containing sodium bisfluorosulfonimide is concentrated by distillation to obtain a sodium bisfluorosulfonimide aqueous concentrate;

[0074] A first non-aqueous organic solvent is added to the sodium bisfluorosulfonimide aqueous concentrate, the first non-aqueous organic solvent being selected from organic solvents that can form azeotropes with water, and the mixture is distilled. During the distillation, the azeotrope of water and the first non-aqueous solvent is removed. When the solution concentration is greater than 50% after distillation, the water content in the solution is tested. If the water content in the solution is greater than 50,000 ppm, the first non-aqueous organic solvent is continuously added for distillation to remove water until the water content in the solution is less than 50,000 ppm. After filtering the solution, the first non-aqueous organic solvent is removed by distillation, and sodium bisfluorosulfonimide solid is obtained by drying.

[0075] The water content in the solution continuously decreases through distillation to remove the azeotrope. By controlling the distillation conditions, water can be removed without decomposing the product, thereby avoiding decomposition of the generated sodium bisfluorosulfonimide during the drying process.

[0076] In a preferred embodiment, the first non-aqueous organic solvent is selected from organic solvents that can form azeotropes with water but are insoluble in water, which facilitates removal of water in the form of an azeotrope during distillation. During the distillation process, the azeotrope of water and the non-aqueous organic solvent is removed from the system. After condensation, the non-aqueous organic solvent can be separated by layering because water and the non-aqueous organic solvent are immiscible. The non-aqueous organic solvent is then returned to the distillation system, thereby ensuring recycling of the non-aqueous organic solvent and continuously reducing the water content in the distillation system.

[0077] In some embodiments, the mass concentration of the sodium bisfluorosulfonimide aqueous concentrate is 30%-85%.

[0078] In a preferred embodiment, the mass concentration of the sodium bisfluorosulfonylimide aqueous concentrated solution is 50%-75%.

[0079] In some embodiments, the distillation is performed under reduced pressure at a temperature of 5-80℃ and a pressure of 0-30KPa.

[0080] In a preferred embodiment, the distillation temperature is 30-70℃. The distillation temperature can be effectively reduced by reduced pressure distillation, thereby avoiding decomposition of sodium bisfluorosulfonylimide or side reactions with water at high temperatures.

[0081] In some embodiments, the moisture content in the test solution is less than 20000ppm when the solution concentration is greater than 50%;

[0082] In a preferred embodiment, the moisture content in the test solution is 70-90%.

[0083] In some embodiments, the first non-aqueous organic solvent is selected from one or more of pyridine, alcohols, ethers, esters, nitriles, and hydrocarbons.

[0084] In a preferred embodiment, the first non-aqueous organic solvent is selected from anisole, n-butyl acetate, n-pentyl acetate, isoamyl propionate, n-butyl butyrate, ethyl hexanoate, and carbonate solvents.

[0085] In a preferred embodiment, when the first non-aqueous organic solvent is dimethyl carbonate, the moisture content is less than 20000ppm when the solution concentration is greater than 50% after distillation, and the sodium bisfluorosulfonylimide is obtained by further distillation to remove the first non-aqueous organic solvent.

[0086] In a preferred embodiment, when the first non-aqueous organic solvent is methyl ethyl carbonate, the moisture content is less than 50000ppm when the solution concentration is greater than 50% after distillation, and the sodium bisfluorosulfonylimide is obtained by further distillation to remove the first non-aqueous organic solvent.

[0087] In some embodiments, the drying process is controlled at a temperature of 10-100℃.

[0088] In another embodiment, the "obtaining an organic solution of sodium bisfluorosulfonylimide from an aqueous solution containing sodium bisfluorosulfonylimide" comprises the following steps:

[0089] The obtained aqueous solution containing sodium bisfluorosulfonylimide is concentrated by distillation to obtain a sodium bisfluorosulfonylimide aqueous concentrated solution;

[0090] adding a second non-aqueous organic solvent into the sodium bisfluorosulfonimide aqueous concentrated solution, the second non-aqueous organic solvent being selected from organic solvents capable of forming azeotrope with water but insoluble in water, distilling, the water and the second non-aqueous organic solvent in the distillate being separated into two layers, removing the water, and returning the second non-aqueous organic solvent into the distillation solution, distilling to a water content <200 ppm (based on the mass of NaFSI), to obtain an organic solution of sodium bisfluorosulfonimide.

[0091] The organic solution of sodium bisfluorosulfonimide prepared by the above preparation method has the advantages of less impurities and high purity, and the energy consumption for preparing the organic solution of sodium bisfluorosulfonimide is lower compared to distilling the organic solution of sodium bisfluorosulfonimide to precipitate sodium bisfluorosulfonimide solid, and since the existing sodium-ion battery non-aqueous electrolyte also uses an organic solvent of sodium salt, the prepared organic solution of sodium bisfluorosulfonimide can be directly applied to the electrolyte, realizing the co-production of the organic solution of sodium bisfluorosulfonimide and the electrolyte, which can effectively avoid the mixing of water or decomposition of sodium bisfluorosulfonimide during the crystallization and drying process, while shortening the process flow and ensuring the quality of the electrolyte.

[0092] In some embodiments, the mass concentration of the sodium bisfluorosulfonimide aqueous concentrated solution is 30%-85%.

[0093] In some embodiments, the distillation is performed by reduced pressure distillation, at a temperature of 5-80°C and a pressure of 0-30 KPa.

[0094] In preferred embodiments, the distillation temperature is 30-70°C.

[0095] In some embodiments, the solution concentration is maintained at 2-60% during the distillation process.

[0096] In preferred embodiments, the solution concentration is maintained at 30-40% during the distillation process.

[0097] In some embodiments, the second non-aqueous organic solvent is selected from organic solvents containing at least one functional group of ester group, cyano group, and ether bond.

[0098] In preferred embodiments, the second non-aqueous organic solvent is selected from carbonate solvents.

[0099] In some embodiments, the mass concentration of the organic solution of sodium bisfluorosulfonimide is 10%-80%.

[0100] In some embodiments, the water content in the organic solution of sodium bisfluorosulfonimide is <200 ppm (based on the mass of NaFSI);

[0101] In preferred embodiments, the water content in the organic solution of sodium bisfluorosulfonimide is <100 ppm (based on the mass of NaFSI);

[0102] In a more preferred embodiment, the content of water in the organic solution of sodium bisfluorosulfonylimide is < 50 ppm (by mass of NaFSI).

[0103] The present application is further illustrated by the following examples.

[0104] Preparation Example 1, Sodium Resin A: The preparation method is as follows:

[0105] About 300 mL of sulfonic acid type strong acidic cation exchange resin was measured and added into a 500 mL chromatographic column, 250 mL of ultrapure water was added for elution, the conductivity of the effluent was 45 μS / cm, then 250 mL of 16% hydrochloric acid solution was added, the K + = 0.39 ppm, Na + = 0.98 ppm, then 1250 mL of ultrapure water was added for elution of the resin column, the conductivity of the effluent was 175 μS / cm, Cl - = 1.41 ppm, 600 mL of 10% NaOH solution was added, the pH of the effluent was 14, and finally 1750 mL of ultrapure water was added for elution of the resin column, the conductivity of the effluent was 160 μS / cm.

[0106] Preparation Example 1, Sodium Resin B: The preparation method is as follows:

[0107] About 300 mL of sulfonic acid type strong acidic cation exchange resin was measured and added into a 500 mL chromatographic column, 250 mL of ultrapure water was added for elution, the conductivity of the effluent was 42 μS / cm; then 250 mL of 8% sulfuric acid solution was added, the K + = 0.68 ppm, Na + = 0.62 ppm, then 1250 mL of ultrapure water was added for elution of the resin column, the conductivity of the effluent was 166 μS / cm, SO4 2- = 1.15 ppm; then 1600 mL of 8% Na2CO3 solution was added, the pH of the effluent was 11; finally 1750 mL of ultrapure water was added for elution of the resin column, the conductivity of the effluent was 163 μS / cm.

[0108] Example 1

[0109] This example is used to illustrate the preparation method of sodium bisfluorosulfonylimide disclosed in the present application, which comprises the following operations:

[0110] A 1976 g KFSI aqueous solution with a concentration of 7.5% was prepared and added into the chromatographic column with sodium resin A, the effluent flow rate was controlled at 40-90 mL / h, and a total of 1940 g of effluent was obtained (K += 1.19 ppm). The effluent was added to a flask and distilled under reduced pressure at 50°C to concentrate to 166 g, dimethyl carbonate 332 g was added, distilled under reduced pressure at 40-70°C to concentrate to 291 g, the distillate was refluxed into the flask, and the above distillation-reflux operation was repeated until the moisture content was 120 ppm (based on the mass of NaFSI), filtered, and distilled under reduced pressure at 50°C to concentrate to a solution of 232.60 g (0.5729 mol), to obtain a liquid NaFSI product with a concentration of 50%, a yield of 84.66% (based on KFSI), a moisture content of 89 ppm (based on the mass of NaFSI), and a main content of 99.97%.

[0111] Example 2

[0112] This example is used to illustrate the preparation method of the disclosed sodium bisfluorosulfonylimide, comprising the following steps:

[0113] A KFSI aqueous solution with a concentration of 10% of 742 g was prepared and added to a chromatographic column with sodium resin A, the effluent flow rate was controlled at 40-90 mL / h, and the effluent was obtained as a total of 729 g (K + = 2.03 ppm). The effluent was added to a flask and distilled under reduced pressure at 55°C to concentrate to 72 g, methyl ethyl carbonate 144 g was added, distilled under reduced pressure at 35-60°C to concentrate to a solution of 192 g, the moisture content was 69570 ppm (based on the mass of NaFSI), then methyl ethyl carbonate was added in batches a total of 216 g, distilled under reduced pressure at 35-60°C to concentrate to 192 g, the moisture content of the solution was 127 ppm (based on the mass of NaFSI), filtered, and distilled under reduced pressure at 60°C to concentrate to a solution of 144.13 g (0.2840 mol), to obtain a liquid NaFSI product with a concentration of 40%, a yield of 83.83% (based on KFSI), a moisture content of 90 ppm (based on the mass of NaFSI), and a main content of 99.98%.

[0114] Example 3

[0115] This example is used to illustrate the preparation method of the disclosed sodium bisfluorosulfonylimide, comprising the following steps:

[0116] A KFSI aqueous solution with a concentration of 12.5% of 537 g was prepared and added to a chromatographic column with sodium resin B, the effluent flow rate was controlled at 40-90 mL / h, and the effluent was obtained as a total of 530 g (K += 3.12 ppm). The effluent was added to a flask and distilled under reduced pressure at 60°C to concentrate to 74 g, ethyl methyl carbonate 148 g was added, distilled under reduced pressure at 40-65°C to concentrate to 65 g, the distillate was refluxed into the flask, the above distillation-reflux operation was repeated until the moisture content in the solution was 10200 ppm, filtration was performed, and the drying under reduced pressure at 60°C was continued to obtain the product 52.01 g (0.2562 mol) in the form of white powder, the yield was 83.59% (based on KFSI), the moisture content was 107 ppm (based on the mass of NaFSI), and the main content was 99.98%.

[0117] Example 4

[0118] This example is used to illustrate the preparation method of the disclosed sodium bisfluorosulfonylimide, which comprises the following steps:

[0119] A KFSI aqueous solution with a concentration of 7.5% and a volume of 3536 g was prepared and added to the chromatographic column containing sodium resin A, the flow rate of the effluent was controlled to be 40-90 mL / h, and the sodium content in the final effluent was 0.5% (based on the mass of NaFSI). + = 160 ppm, and the sodium in the resin column was consumed; the resin column was regenerated by sequentially adding 1000 mL of ultrapure water, 5500 mL of 16% hydrochloric acid solution, 2250 mL of ultrapure water, 1250 mL of 10% NaOH solution, and 2250 mL of ultrapure water to the resin column for elution; the above effluent was added to the sodium resin column, 2912 g of KFSI aqueous solution with a concentration of 7.5% was added again, the flow rate of the effluent was controlled to be 40-90 mL / h, and then the resin column was regenerated again; all the above effluents were added to the resin column, the flow rate of the effluent was controlled to be 40-90 mL / h, and a total of 6372 g of effluent (K + = 1.67 ppm). The effluent was added to a flask and distilled under reduced pressure at 60°C to concentrate to 590 g, ethyl methyl carbonate 1181 g was added, distilled under reduced pressure at 35-60°C to concentrate to 521 g, the moisture content in the solution was 16233 ppm, filtration was performed, and the drying under reduced pressure at 60°C was continued to obtain the product 442.74 g (2.1810 mol) in the form of white powder, the yield was 98.77% (based on KFSI), the moisture content was 85 ppm (based on the mass of NaFSI), and the main content was 99.98%.

[0120] Comparative Example 1

[0121] A KFSI aqueous solution with a concentration of 12.5% and a volume of 537 g was prepared and added to the chromatographic column containing sodium resin B, the flow rate of the effluent was controlled to be 40-90 mL / h, and a total of 525 g of effluent (K += 2.92 ppm). The effluent was added to a flask and distilled at 60°C under reduced pressure to give the product 51.07 g (0.2516 mol) as a white powder, with a yield of 82.08% (based on KFSI), a moisture content of 1730 ppm (based on the mass of NaFSI), and a main content of 98.005%.

[0122] The above description is only the preferred embodiment of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for producing sodium bisfluorosulfonimide, characterized by, The method comprises the following steps: A cation exchange resin column is provided, the cation exchange resin column is filled with strong acid cation exchange resin, and the strong acid cation exchange resin is adsorbed with sodium ions, and the cation exchange resin column is prepared by the following preparation method: After the strong acid cation exchange resin is packed, the cation exchange resin column is sequentially eluted with water, an acid solution, water, a sodium hydroxide or alkali sodium salt solution and water; Ion exchange: the aqueous solution of potassium bisfluorosulfonimide is introduced into the cation exchange resin column for ion exchange, potassium ions on the potassium bisfluorosulfonimide are replaced with sodium ions, and an aqueous solution containing sodium bisfluorosulfonimide is obtained; when the sodium ion content in the effluent is less than 1000 ppm during the ion exchange operation, the cation exchange resin column is subjected to a regeneration operation, and the regeneration operation of the cation exchange resin column is the same as the preparation method of the cation exchange resin column; The aqueous solution containing sodium bisfluorosulfonimide is used to prepare an organic solution of sodium bisfluorosulfonimide or a solid of sodium bisfluorosulfonimide.

2. The method for producing sodium bisfluorosulfonimide according to claim 1, characterized by, The mass concentration of potassium bisfluorosulfonimide in the aqueous solution of potassium bisfluorosulfonimide is 1% to 50%.

3. The method for preparing sodium difluorosulfonyl imide according to claim 1, characterized in that, When the cation exchange resin column is eluted with water, the conductivity of the effluent is less than 200 muS / cm as the elution end marker; When the cation exchange resin column is eluted with an acid solution, the metal cation content in the effluent is less than 100 ppm as the elution end marker; When the cation exchange resin column is eluted with a sodium hydroxide or alkali sodium salt solution, the pH of the effluent is greater than 8 as the elution end marker.

4. The method for preparing sodium difluorosulfonamide according to claim 1, characterized in that, The acid solution comprises one or more of hydrochloric acid and sulfuric acid, and the concentration of the acid solution is 1% to 50%; The alkali sodium salt solution comprises a solution of one or more of sodium carbonate, sodium bicarbonate, sodium methoxide and sodium ethoxide, and the mass concentration of sodium hydroxide or alkali sodium salt in the sodium hydroxide or alkali sodium salt solution is 0.1% to 50%.

5. The method for preparing sodium difluorosulfonamide according to claim 1, characterized in that, The "solid of sodium bisfluorosulfonimide prepared from the aqueous solution containing sodium bisfluorosulfonimide" comprises the following operations: The obtained aqueous solution containing sodium bisfluorosulfonimide is concentrated by distillation to obtain a sodium bisfluorosulfonimide water concentrate; In the sodium bisfluorosulfonimide aqueous concentrated solution, a first non-aqueous organic solvent is added and mixed, the first non-aqueous organic solvent is selected from an organic solvent capable of forming an azeotrope with water, distillation is carried out, and when the concentration of the sodium bisfluorosulfonimide solution is greater than 50%, the water content in the solution is tested; if the water content in the solution is greater than 50,000 ppm, the first non-aqueous organic solvent is continuously added for distillation to remove water until the water content in the solution is less than 50,000 ppmAfter the solution is filtered, the first non-aqueous organic solvent is removed by distillation, and sodium bisfluorosulfonimide solid is obtained by drying.

6. The process for preparing sodium bisfluorosulfonimide according to claim 5, characterized in that, The mass concentration of the sodium bisfluorosulfonimide water concentrate is 30% to 85%; The distillation is performed by reduced pressure distillation at a temperature of 5°C to 80°C and a pressure of 0 to 30 KPa; The first non-aqueous organic solvent is selected from one or more of pyridine, alcohol, ether, ester, nitrile and hydrocarbon; The drying process is controlled at a temperature of 10°C to 100°C.

7. The method for preparing sodium difluorosulfonamide according to claim 1, characterized in that, The "organic solution of sodium bisfluorosulfonimide prepared from the aqueous solution containing sodium bisfluorosulfonimide" comprises the following operations: The obtained aqueous solution containing sodium bisfluorosulfonimide is concentrated by distillation to obtain a sodium bisfluorosulfonimide water concentrate; In the sodium bisfluorosulfonimide aqueous concentrated solution, a second non-aqueous organic solvent is added and mixed, the second non-aqueous organic solvent is selected from an organic solvent capable of forming an azeotrope with water but insoluble in water, distillation is carried out, water and the second non-aqueous organic solvent are separated in the distillate, water is removed, and the second non-aqueous organic solvent is returned to the distillation liquid, the distillation is carried out to a water content of <200 ppm based on the mass of NaFSI, and an organic solution of sodium bisfluorosulfonimide is obtained.

8. The process for preparing sodium bisfluorosulfonimide according to claim 7, characterized in that, The mass concentration of the sodium bisfluorosulfonimide aqueous concentrated solution is 30%-85%; The distillation is carried out by reduced pressure distillation, the temperature is 5°C-80°C, and the pressure is 0-30 KPa; The solution concentration is maintained at 2-60% during the distillation process; The second non-aqueous organic solvent is selected from an organic solvent containing at least one functional group of an ester group, a cyano group, and an ether bond; The mass concentration of the organic solution of sodium bisfluorosulfonimide is 10%-80%.