A preparation method of sodium bis(fluorosulfonyl)imide

Abstract

The present invention belongs to the technical field of compound preparation, and specifically relates to a method for preparing sodium bis(fluorosulfonyl)imide, which comprises at least the following steps: the first step is to add anhydrous formic acid to chlorosulfonic acid isocyanate, and stir the reaction to prepare chlorosulfonamide; the second step is to add an organic solvent to the chlorosulfonamide prepared in the first step, and then add sodium fluoride, and then add sulfuryl chloride in batches, and stir the reaction after the feeding is completed; the third step is to filter the reaction product obtained in the second step, remove the filter residue, and concentrate the filtrate under reduced pressure to remove the solvent to obtain a crude sodium bis(fluorosulfonyl)imide; the fourth step is to dissolve the crude product in a protic solvent for recrystallization, and then filter and dry under reduced pressure to obtain a pure sodium bis(fluorosulfonyl)imide. The process is not only simple to operate, but also has a short reaction time and a high yield, and can effectively control metal ion and anion impurities, and can prepare a high-purity target product of sodium bis(fluorosulfonyl)imide.

Description

Technical Field

[0001] The invention belongs to the technical field of compound preparation, and particularly relates to a method for preparing sodium bis(fluorosulfonyl)imide. Background Art

[0002] Alkali metal ion secondary batteries occupy an important position in the field of electrochemical energy storage. The sodium element is abundant in the earth's crust and inexpensive. Sodium ion batteries are superior to lithium ion batteries in terms of safety performance and cost. Therefore, they have broad application prospects in the fields of power and energy storage. They are one of the potential energy storage technologies to replace lithium ion batteries, and are expected to alleviate the problem of limitations in the field of electrochemical energy storage caused by the shortage of lithium resources.

[0003] Electrolyte is one of the key materials of sodium-ion batteries, mainly composed of electrolyte sodium salt, solvent and functional additives. Good electrolyte sodium salt materials have excellent physical and chemical properties and electrochemical performance, including high conductivity and ion migration number, as well as stable SEI interface. The ideal sodium salt should have the ability to completely dissolve and highly dissociate in the electrolyte, and should remain electrochemically inert to other components of the battery (such as electrodes, diaphragms and current collectors). Sodium perchlorate and sodium hexafluorophosphate are the two most commonly used sodium salts in the research of sodium-ion battery systems. However, sodium perchlorate is an explosive substance, and sodium hexafluorophosphate is sensitive to water and easily produces highly corrosive hydrofluoric acid, which affects the battery life.

[0004] Fluorinated sulfonyl imides and related compounds play an extremely important role in the fields of material chemistry and electrochemical energy storage. Bisfluorosulfonyl imides are important raw materials for preparing lithium salts, sodium salts and other alkali metal salts and derivatives. Bisfluorosulfonyl imides are generally prepared by fluorination of bischlorosulfonyl imides. The preparation process of bischlorosulfonyl imides mainly includes: 1) preparation by reaction of phosphorus pentachloride, aminosulfonic acid and chlorosulfonic acid (K. Ruff et al, Inorg. Synth. 1968, 11, 138); 2) preparation by reaction of aminosulfonic acid, dichlorothionyl and chlorosulfonic acid (M. Beran, Z. Anorg Allg Chem., 2005, 631, 55). Fluorination reagents mainly include arsenic trifluoride, antimony trifluoride, zinc fluoride, anhydrous hydrogen fluoride, bismuth trifluoride, etc. The preparation methods of sodium bis(fluorosulfonyl)imide include: 1) preparation by ion exchange of potassium bis(fluorosulfonyl)imide and other sodium salts (such as sodium perchlorate and sodium tetrafluoroborate) (M. Beran, Polyhedron, 2006, 25, 1292); 2) preparation by neutralization of bis(fluorosulfonyl)imide or ammonium salt and sodium carbonate (or sodium hydroxide) (CN101980955A, CN102405189A, CN102917979A, CN104925765A). Among them, the preparation of lithium bis(fluorosulfonyl)imide by ion exchange has a very high potassium ion content in the product, which far exceeds the specifications of lithium ion battery electrolyte, because the byproduct potassium salt is difficult to be fully removed by precipitation / filtration. In the neutralization preparation method, since the boiling points of bischlorosulfonyl imide and bisfluorosulfonyl imide are not very different, it is inevitable that bisfluorosulfonyl imide is mixed with a large amount of chloride ions, so the chlorine content of the product is relatively high. In addition, water is produced during the acid-base neutralization process, resulting in the decomposition of a small amount of bisfluorosulfonyl imide anions, so the sulfate content is high. Therefore, the existing method has the defects of low yield and high ion impurity content.

[0005] In view of this, the present invention aims to provide a method for preparing sodium bis(fluorosulfonyl)imide, which not only has a simple process, a short reaction time, and a high yield, but also can effectively control metal ion and anion impurities, and can prepare a high-purity sodium bis(fluorosulfonyl)imide target product. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing sodium bis(fluorosulfonyl)imide in view of the shortcomings of the prior art, which has the advantages of simple process, short reaction time and high yield, and can effectively control metal ion and anion impurities, so as to prepare a high-purity sodium bis(fluorosulfonyl)imide target product.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for preparing sodium bis(fluorosulfonyl)imide, comprising at least the following steps:

[0009] The first step is to add anhydrous formic acid to chlorosulfonic acid isocyanate and stir the reaction to prepare chlorosulfonamide;

[0010] The second step is to add the first organic solvent to the chlorosulfonamide prepared in the first step, and then add sodium fluoride, and then add sulfuryl chloride in batches, and stir to react after the addition is completed;

[0011] The third step is to filter the reaction product obtained in the second step to remove the filter residue, and the filtrate is concentrated under reduced pressure to remove the solvent to obtain a crude product of sodium bis(fluorosulfonyl)imide;

[0012] The fourth step is to dissolve the crude product in a second organic solvent for recrystallization, filter and dry under reduced pressure to obtain pure sodium bis(fluorosulfonyl)imide.

[0013] The principle of the present invention is:

[0014] ClSO2NCO+HCOOH→ClSO2NH2+CO+CO2

[0015] ClSO2NH2+SO2Cl2+4NaF→Na[N(SO2F)2]+2NaCl+NaHF2

[0016] The process is not only simple to operate, short in reaction time and high in yield, but also can effectively control metal ion and anion impurities, and can prepare a high-purity target product of sodium bis(fluorosulfonyl)imide.

[0017] As an improvement to the preparation method of sodium bis(fluorosulfonyl)imide of the present invention, in the first step, the stoichiometric molar ratio of chlorosulfonic acid isocyanate to anhydrous formic acid is 1:1 to 1:1.5.

[0018] As an improvement of the preparation method of sodium bis(fluorosulfonyl)imide of the present invention, in the second step, the first organic solvent is at least one of acetonitrile, acetone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, propyl acetate, butyl acetate, ether and methyl tert-butyl ether.

[0019] As an improvement to the preparation method of sodium bis(fluorosulfonyl)imide of the present invention, the stoichiometric molar ratio of chlorosulfonamide and sulfuryl chloride in the second step is 1:1 to 1:1.5.

[0020] As an improvement to the preparation method of sodium bis(fluorosulfonyl)imide of the present invention, the stoichiometric molar ratio of chlorosulfonamide and sodium fluoride in the second step is 1:4 to 1:5.

[0021] As an improvement to the preparation method of sodium bis(fluorosulfonyl)imide of the present invention, the reaction temperature in the second step is 25-80°C.

[0022] As an improvement of the preparation method of sodium bis(fluorosulfonyl)imide of the present invention, in the fourth step, the second organic solvent is at least one of acetonitrile, acetone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, propyl acetate, toluene, dichloromethane, ethanol, methanol, propanol, isopropanol, and butanol.

[0023] As an improvement of the preparation method of sodium bis(fluorosulfonyl)imide of the present invention, the reaction temperature in the first step is -10°C to 5°C, and the stirring time is 4 hours to 12 hours.

[0024] As an improvement to the preparation method of sodium bis(fluorosulfonyl)imide of the present invention, the reaction time in the second step is 6-20 hours and the reaction temperature is 60° C.-120° C. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the nuclear magnetic resonance image of the sodium bis(fluorosulfonyl)imide product prepared in Example 1. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0027] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0029] Example 1

[0030] ClSO2NCO+HCOOH→ClSO2NH2+CO+CO2

[0031] ClSO2NH2+SO2Cl2+4NaF→Na[N(SO2F)2]+2NaCl+NaHF2

[0032] 71 g (0.5 mol) of chlorosulfonic acid isocyanate was added to a 500 mL reaction bottle, and 0.6 mol of anhydrous formic acid was added under an ice-water bath. After stirring for 8 hours, the chlorosulfonamide product was obtained (reference J. Org. Chem. 1989, 54: 5824).

[0033] Add 200mL dry acetonitrile and 84g (2mol) sodium fluoride to the above reaction bottle, add 67.5g (0.5mol) sulfuryl chloride dropwise at room temperature, stir magnetically, and control the temperature to 80°C for 12 hours after the addition is complete. Filter under reduced pressure to obtain a clear filtrate, remove acetonitrile under reduced pressure to obtain crude sodium bis(fluorosulfonyl)imide. Recrystallize with ethanol, filter and dry to obtain 91.4g of white solid, which is pure sodium bis(fluorosulfonyl)imide, with a yield of 90%. ( 19 F-NMR, 51.4; Cl - <5ppm; SO4 2- <5ppm; K<1ppm; Mg<1ppm; Ca<1ppm; Fe<1ppm; Hg ND; Cr<1ppm). like Figure 1 As shown, the product passed NMR detection, which was consistent with the literature report.

[0034] Example 2

[0035] ClSO2NCO+HCOOH→ClSO2NH2+CO+CO2

[0036] ClSO2NH2+SO2Cl2+4NaF→Na[N(SO2F)2]+2NaCl+NaHF2

[0037] 71 g (0.5 mol) of chlorosulfonic acid isocyanate was added to a 500 mL reaction bottle, and 0.55 mol of anhydrous formic acid was added under an ice-water bath. The mixture was stirred and reacted for 6 hours to obtain the chlorosulfonamide product.

[0038] Add 200 mL of acetone and 88.2 g (2.1 mol) of sodium fluoride to the above reaction flask, add 74.25 g (0.55 mol) of sulfuryl chloride dropwise at room temperature, stir magnetically, and after the addition is complete, control the temperature to 90°C and react for 10 hours. Filter under reduced pressure to obtain a clear filtrate, remove acetone under reduced pressure to obtain a crude product of sodium bis(fluorosulfonyl)imide. Recrystallize using methanol, filter and dry to obtain 91.4 g of a white solid with a yield of 90%. ( 19 F-NMR, 51.4; Cl - <5ppm; SO4 2- <5ppm; K<1ppm; Mg<1ppm; Ca<1ppm; Fe<1ppm; HgND; Cr<1ppm).

[0039] Example 3

[0040] ClSO2NCO+HCOOH→ClSO2NH2+CO+CO2

[0041] ClSO2NH2+SO2Cl2+4NaF→Na[N(SO2F)2]+2NaCl+NaHF2

[0042] 71 g (0.5 mol) of chlorosulfonic acid isocyanate was added to a 500 mL reaction bottle, and 0.60 mol of anhydrous formic acid was added under an ice-water bath. The mixture was stirred and reacted for 10 hours to obtain the chlorosulfonamide product.

[0043] Add 200mL of diethyl carbonate and 86.1g (2.05mol) of sodium fluoride to the above reaction flask, add 70.2g (0.52mol) of sulfuryl chloride dropwise at room temperature, stir magnetically, and after the addition is complete, control the temperature at 100°C to react for 7 hours. Filter under reduced pressure to obtain a clear filtrate, remove diethyl carbonate under reduced pressure to obtain a crude product of sodium bis(fluorosulfonyl)imide. Recrystallize using propanol, filter and dry to obtain 91.4g of a white solid with a yield of 90%. ( 19 F-NMR, 51.4; Cl - <5ppm; SO4 2- <5ppm; K<1ppm; Mg<1ppm; Ca<1ppm; Fe<1ppm; Hg ND; Cr<1ppm).

[0044] Example 4

[0045] ClSO2NCO+HCOOH→ClSO2NH2+CO+CO2

[0046] ClSO2NH2+SO2Cl2+4NaF→Na[N(SO2F)2]+2NaCl+NaHF2

[0047] 71 g (0.5 mol) of chlorosulfonic acid isocyanate was added to a 500 mL reaction bottle, and 0.58 mol of anhydrous formic acid was added under an ice-water bath. The mixture was stirred and reacted for 6 hours to obtain the chlorosulfonamide product.

[0048] Add 200mL of ethyl methyl carbonate and 100.8g (2.4mol) of sodium fluoride to the above reaction flask, add 81g (0.6mol) of sulfuryl chloride dropwise at room temperature, stir magnetically, and after the addition is complete, control the temperature to 105°C and react for 6.5 hours. Filter under reduced pressure to obtain a clear filtrate, remove ethyl methyl carbonate under reduced pressure to obtain a crude product of sodium bis(fluorosulfonyl)imide. Recrystallize using butanol, filter and dry to obtain 91.4g of a white solid with a yield of 90%. ( 19 F-NMR, 51.4; Cl - <5ppm; SO4 2- <5ppm; K<1ppm; Mg<1ppm; Ca<1ppm; Fe<1ppm; Hg ND; Cr<1ppm).

[0049] Example 5

[0050] ClSO2NCO+HCOOH→ClSO2NH2+CO+CO2

[0051] ClSO2NH2+SO2Cl2+4NaF→Na[N(SO2F)2]+2NaCl+NaHF2

[0052] 71 g (0.5 mol) of chlorosulfonic acid isocyanate was added to a 500 mL reaction bottle, and 0.6 mol of anhydrous formic acid was added under an ice-water bath. The mixture was stirred and reacted for 11 hours to obtain the chlorosulfonamide product.

[0053] Add 200mL of ethyl acetate and 96.6g (2.3mol) of sodium fluoride to the above reaction flask, add 81g (0.6mol) of sulfuryl chloride dropwise at room temperature, stir magnetically, and after the addition is complete, control the temperature to 95°C and react for 9.5 hours. Filter under reduced pressure to obtain a clear filtrate, remove ethyl acetate under reduced pressure to obtain a crude product of sodium bis(fluorosulfonyl)imide. Recrystallize using isopropanol, filter and dry to obtain 91.4g of a white solid with a yield of 90%. ( 19 F-NMR, 51.5; Cl - <5ppm; SO4 2- <5ppm; K<1ppm; Mg<1ppm; Ca<1ppm; Fe<1ppm; Hg ND; Cr<1ppm).

[0054] Example 6

[0055] ClSO2NCO+HCOOH→ClSO2NH2+CO+CO2

[0056] ClSO2NH2+SO2Cl2+4NaF→Na[N(SO2F)2]+2NaCl+NaHF2

[0057] 71 g (0.5 mol) of chlorosulfonic acid isocyanate was added to a 500 mL reaction bottle, and 0.6 mol of anhydrous formic acid was added under an ice-water bath. After stirring for 8 hours, the chlorosulfonamide product was obtained (reference J. Org. Chem. 1989, 54: 5824).

[0058] Add 200 mL of dry acetonitrile and 84 g (2 mol) of sodium fluoride to the above reaction flask, add 67.5 g (0.5 mol) of sulfuryl chloride dropwise at room temperature, stir magnetically, and control the temperature to 80°C for 12 hours after the addition is complete. Filter under reduced pressure to obtain a clear filtrate, remove acetonitrile under reduced pressure to obtain a crude product of sodium bis(fluorosulfonyl)imide. Recrystallize with diethyl carbonate, filter and dry to obtain 91.4 g of a white solid, which is pure sodium bis(fluorosulfonyl)imide, with a yield of 90%. ( 19 F-NMR, 51.4; Cl - <5ppm; SO4 2- <5ppm; K<1ppm; Mg<1ppm; Ca<1ppm; Fe<1ppm; Hg ND; Cr<1ppm). like Figure 1 As shown, the product passed NMR detection, which was consistent with the literature report.

[0059] Example 7

[0060] ClSO2NCO+HCOOH→ClSO2NH2+CO+CO2

[0061] ClSO2NH2+SO2Cl2+4NaF→Na[N(SO2F)2]+2NaCl+NaHF2

[0062] 71 g (0.5 mol) of chlorosulfonic acid isocyanate was added to a 500 mL reaction bottle, and 0.6 mol of anhydrous formic acid was added under an ice-water bath. After stirring for 8 hours, the chlorosulfonamide product was obtained (reference J. Org. Chem. 1989, 54: 5824).

[0063] Add 200mL of dimethyl carbonate and 84g (2mol) of sodium fluoride to the above reaction flask, add 67.5g (0.5mol) of sulfuryl chloride dropwise at room temperature, stir magnetically, and after the addition is complete, control the temperature to 80°C and react for 12 hours. Filter under reduced pressure to obtain a clear filtrate, remove dimethyl carbonate under reduced pressure to obtain a crude product of sodium bis(fluorosulfonyl)imide. Recrystallize with acetonitrile, filter and dry to obtain 91.4g of white solid, which is pure sodium bis(fluorosulfonyl)imide, with a yield of 90%. ( 19 F-NMR, 51.4; Cl - <5ppm; SO4 2- <5ppm; K<1ppm; Mg<1ppm; Ca<1ppm; Fe<1ppm; Hg ND; Cr<1ppm). like Figure 1 As shown, the product passed NMR detection, which was consistent with the literature report.

[0064] Comparative Example 1

[0065] 109.5 g (0.5 mol) of potassium bis(fluorosulfonyl)imide was added to a 1000 mL reaction bottle, 500 mL of dimethyl carbonate was added as a solvent at room temperature, and 61 g (0.5 mol) of sodium perchlorate was added, stirred for 3 hours, filtered under reduced pressure, and the clear filtrate was dried under reduced pressure to obtain 96.5 g of sodium bis(fluorosulfonyl)imide product. 19 F-NMR, 51.4; Cl - <5ppm; SO4 2- <5ppm; K 1800ppm; Mg<1ppm; Ca<1ppm; Fe<1ppm; Hg ND; Cr<1ppm).

[0066] Comparative Example 2

[0067] 42.8 g (0.2 mol) of bis(chlorosulfonyl)imide was added to a 500 mL reaction bottle, and 24.7 g (0.24 mol) of anhydrous zinc fluoride was added at room temperature. After stirring for 5 hours, the crude product of bis(fluorosulfonyl)imide was obtained by water pump vacuum distillation. The distillation was repeated three times to obtain 27.2 g of bis(fluorosulfonyl)imide.

[0068] 27.2 g of bis(fluorosulfonyl)imide was dissolved in 100 mL of DMC, 15.2 g (0.15 mol) of triethylamine was added, and then 50 mL of water and 6 g of sodium hydroxide (0.15 mol) were added. After stirring for 2 hours, the organic phase was separated and dried under reduced pressure to obtain a crude product of sodium bis(fluorosulfonyl)imide, which was recrystallized from a dimethyl carbonate / toluene mixed solvent, filtered, and dried under reduced pressure to obtain 25.8 g of sodium bis(fluorosulfonyl)imide ( 19 F-NMR, 51.5; Cl - 12ppm; SO4 2- 100ppm; K<2ppm; Mg<1ppm; Ca<1ppm; Fe<1ppm; Hg ND; Cr<1ppm).

[0069] From the results of Example 1 and Comparative Examples 1 and 2, it can be seen that Comparative Example 1 uses an ion exchange method to prepare lithium difluorosulfonyl imide. Since the byproduct potassium salt is difficult to fully remove by precipitation / filtration, the potassium ion content of the product is very high, far exceeding the specifications of lithium ion battery electrolyte. In Comparative Example 2, since the boiling points of dichlorosulfonyl imide and difluorosulfonyl imide are not too different, difluorosulfonyl imide is inevitably mixed with a large amount of chloride ions, so the chlorine content of the product is relatively high. In addition, water is produced during the acid-base neutralization process, resulting in the decomposition of a small amount of bisfluorosulfonyl imide anions, so the sulfate content is high.

[0070] In contrast, in the intermediate product obtained by the method provided by the present invention, CO and CO2 are gases and are easy to remove, NaCl and NaHF2 can be well removed during the recrystallization process, and excess raw materials such as formic acid, sulfuryl chloride, NaF, etc. can also be well removed. The whole process has a short reaction time, a high yield, and can effectively control metal ion and anion impurities, and can prepare a high-purity sodium bis(fluorosulfonyl)imide target product.

[0071] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A method for preparing sodium bis(fluorosulfonyl)imide, characterized in that: At least the following steps are included: The first step is to add anhydrous formic acid to chlorosulfonic acid isocyanate and stir the reaction to prepare chlorosulfonamide; The second step is to add the first organic solvent to the chlorosulfonamide prepared in the first step, and then add sodium fluoride, and then add sulfuryl chloride in batches, and stir to react after the addition is completed; The third step is to filter the reaction product obtained in the second step to remove the filter residue, and the filtrate is concentrated under reduced pressure to remove the solvent to obtain a crude product of sodium bis(fluorosulfonyl)imide; The fourth step is to dissolve the crude product in a second organic solvent for recrystallization, filter and dry under reduced pressure to obtain a pure product of sodium bis(fluorosulfonyl)imide; In the second step, the first organic solvent is at least one of acetonitrile, acetone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, propyl acetate, butyl acetate, ether and methyl tert-butyl ether; In the fourth step, the second organic solvent is at least one of acetonitrile, acetone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, propyl acetate, toluene, dichloromethane, ethanol, methanol, propanol, isopropanol and butanol.

2. The method for preparing sodium bis(fluorosulfonyl)imide according to claim 1, characterized in that: In the first step, the stoichiometric molar ratio of chlorosulfonic acid isocyanate to anhydrous formic acid is 1:1 to 1:1.

5.

3. The method for preparing sodium bis(fluorosulfonyl)imide according to claim 1, characterized in that: The stoichiometric molar ratio of chlorosulfonamide and sulfuryl chloride in the second step is 1:1 to 1:1.

5.

4. The method for preparing sodium bis(fluorosulfonyl)imide according to claim 1, characterized in that: The stoichiometric molar ratio of chlorosulfonamide and sodium fluoride in the second step is 1:4 to 1:

5.

5. The method for preparing sodium bis(fluorosulfonyl)imide according to claim 1, characterized in that: The reaction temperature in the second step is 25-80°C.

6. The method for preparing sodium bis(fluorosulfonyl)imide according to claim 1, characterized in that: The reaction temperature in the first step is -10 °C to 5 °C, and the stirring time is 4 hours to 12 hours.

7. The method for preparing sodium bis(fluorosulfonyl)imide according to claim 1, characterized in that: The reaction time in the second step is 6-20 hours, and the reaction temperature is 60°C-120°C.

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