Battery-grade sodium fluorosulfonate and preparation method thereof

Abstract

The present invention provides a battery-grade sodium fluorosulfonate and a preparation method thereof, the preparation method comprising: first mixing chlorosulfonic acid and anhydrous hydrogen fluoride, and obtaining fluorosulfonic acid after a first reaction; second mixing sodium chloride and the obtained fluorosulfonic acid, and obtaining battery-grade sodium fluorosulfonate after a second reaction. In the present invention, fluorosulfonic acid is prepared by reacting chlorosulfonic acid with anhydrous hydrogen fluoride, and then fluorosulfonic acid is reacted with sodium chloride to obtain battery-grade sodium fluorosulfonate. The preparation method does not use organic solvents when synthesizing battery-grade sodium fluorosulfonate, will not cause harm to the human body and is environmentally friendly, the tail gas can be sold as a by-product, and the reagents used in the preparation process can be reused; in addition, the preparation method has a high yield when preparing battery-grade sodium fluorosulfonate, and the obtained battery-grade sodium fluorosulfonate has a high purity.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries and relates to a preparation method of battery-grade sodium fluorosulfonate, in particular to battery-grade sodium fluorosulfonate and a preparation method thereof. Background Art

[0002] With the rapid development of the new energy vehicle industry, the market demand for batteries has increased. Lithium-ion batteries will not be able to meet the demand in the future due to the global shortage of lithium resources. At the same time, the price of lithium resource raw materials continues to rise, hindering the development of the new energy industry. Therefore, the market urgently needs to develop a new energy storage system that is rich in resources, low in price, safe and environmentally friendly, has excellent performance, and is suitable for large-scale applications to partially replace lithium-ion batteries in order to alleviate the excessive dependence on lithium resources.

[0003] Sodium is evenly distributed and widespread around the world, and the basic materials related to it are cheap and environmentally friendly. More importantly, sodium ions and lithium ions are both in the first main group of the periodic table, and the electrochemical potential of sodium is -2.71V, and the electrochemical potential of lithium is -3.05V. The charge and discharge platform potentials of the batteries assembled from the two are close, and they have very similar physical and chemical properties. Therefore, the scientific theories and experience accumulated by some lithium-ion batteries can help the development of sodium-ion batteries avoid some detours.

[0004] Sodium fluorosulfonate can be used as the main component of sodium ion battery electrolyte, but there are few reports on the synthesis of sodium fluorosulfonate. In the prior art, a large amount of organic solvents, including dimethyl carbonate, ethyl acetate, dichloromethane, etc., are used in the synthesis of sodium fluorosulfonate, which are not only toxic to the human body but also easily pollute the environment; in addition, the impurity removal process of the sodium fluorosulfonate synthesis method disclosed in the prior art is relatively complicated and requires multiple purifications, and the purity and yield of the final sodium fluorosulfonate cannot meet the needs of practical applications.

[0005] CN117049572A discloses a method for preparing sodium fluorosulfonate, which relates to the technical field of synthetic methods. XSO3H is reacted with sodium chloride and anhydrous hydrogen fluoride, and H in XSO3H (X represents a halogen element other than fluorine) as a strong acid is replaced with sodium to generate a salt, and X is replaced with fluorine, thereby obtaining sodium fluorosulfonate. However, the synthetic method uses a large amount of organic solvents, which are not only toxic to the human body and easily pollute the environment, but also the purity and yield of the finally obtained sodium fluorosulfonate cannot meet the needs of practical applications.

[0006] CN118306951A discloses a method for preparing sodium fluorosulfonate, which comprises reacting anhydrous hydrogen fluoride, sodium chloride and a sulfonic acid source, wherein the sulfonic acid source is sulfur trioxide. The raw materials used in the method provided in the document are easily available, the preparation method is simple, and the yield of the product sodium fluorosulfonate can be significantly improved. However, a large amount of organic solvent is also used in the preparation method, which is not only toxic to the human body and easily pollutes the environment, but also the purity of the obtained sodium fluorosulfonate is insufficient.

[0007] The preparation methods of sodium fluorosulfonate disclosed in the prior art have certain defects. There are problems that a large amount of organic solvents are needed in the preparation process, which are toxic to the human body and easily pollute the environment. There are also problems that the preparation process is complicated, and the purity and yield of the obtained sodium fluorosulfonate cannot meet the needs of practical applications. Therefore, it is very important to develop and design a new type of battery-grade sodium fluorosulfonate and its preparation method. Summary of the invention

[0008] In view of the deficiencies in the prior art, the object of the present invention is to provide a battery-grade sodium fluorosulfonate and a preparation method thereof. In the present invention, fluorosulfonic acid is prepared by reacting chlorosulfonic acid with anhydrous hydrogen fluoride, and then fluorosulfonic acid is reacted with sodium chloride to obtain battery-grade sodium fluorosulfonate. The preparation method does not use an organic solvent when synthesizing battery-grade sodium fluorosulfonate, will not cause harm to the human body and is environmentally friendly, the tail gas can be sold as a by-product, and the reagents used in the preparation process can be reused; in addition, the preparation method has a high yield when preparing battery-grade sodium fluorosulfonate, and the obtained battery-grade sodium fluorosulfonate has a high purity.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a method for preparing battery-grade sodium fluorosulfonate, the preparation method comprising:

[0011] First, chlorosulfonic acid and anhydrous hydrogen fluoride are mixed, and fluorosulfonic acid is obtained after a first reaction; second, sodium chloride is mixed with the obtained fluorosulfonic acid, and battery-grade sodium fluorosulfonate is obtained after a second reaction.

[0012] The principle of the reaction of chlorosulfonic acid with anhydrous hydrogen fluoride to obtain fluorosulfonic acid in the present invention is: HSO3Cl+HF=HSO3F.

[0013] The principle of the reaction of sodium chloride with fluorosulfonic acid to obtain sodium fluorosulfonate is: HSO3F+NaCl=NaSO3F+HCl.

[0014] In the present invention, fluorosulfonic acid is prepared by reacting chlorosulfonic acid with anhydrous hydrogen fluoride, and then fluorosulfonic acid is reacted with sodium chloride to obtain battery-grade sodium fluorosulfonate. The preparation method does not use organic solvents when synthesizing battery-grade sodium fluorosulfonate, will not cause harm to the human body and is environmentally friendly. The tail gas can be sold as a by-product, and the reagents used in the preparation process can be recycled. In addition, the preparation method has a high yield when preparing battery-grade sodium fluorosulfonate, and the obtained battery-grade sodium fluorosulfonate has a high purity.

[0015] Preferably, before the first mixing, the method further comprises: introducing chlorosulfonic acid into the fluorination bottle in a protective atmosphere, and then freezing and cooling the mixture to -20 to 10°C;

[0016] Before the first mixing, the method further comprises: introducing anhydrous hydrogen fluoride into the anhydrous hydrogen fluoride generator at -20 to 19°C, and then controlling the temperature of the anhydrous hydrogen fluoride in the anhydrous hydrogen fluoride generator to rise to 20 to 50°C.

[0017] In the present invention, the temperature is frozen to -20 to 10°C, for example, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C or 10°C, but is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0018] In the present invention, before the first mixing, anhydrous hydrogen fluoride is introduced into the anhydrous hydrogen fluoride generator at -20 to 19°C, for example, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C or 19°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0019] In the present invention, before the first mixing, the temperature of the anhydrous hydrogen fluoride in the anhydrous hydrogen fluoride generator is controlled to rise to 20-50° C., for example, it can be 20° C., 22° C., 25° C., 28° C., 30° C., 32° C., 35° C., 38° C., 40° C., 42° C., 45° C., 48° C. or 50° C., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] Preferably, the first mixing comprises: passing anhydrous hydrogen fluoride at 20 to 50° C. from an anhydrous hydrogen fluoride generator into chlorosulfonic acid at -20 to 10° C. in a fluorination bottle;

[0021] The molar ratio of chlorosulfonic acid to anhydrous hydrogen fluoride in the first mixture is (1-4):1.

[0022] The temperature of the anhydrous hydrogen fluoride in the first mixture of the present invention is 20-50°C, for example, it can be 20°C, 22°C, 25°C, 28°C, 30°C, 32°C, 35°C, 38°C, 40°C, 42°C, 45°C, 48°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] The temperature of the chlorosulfonic acid in the first mixture of the present invention is -20 to 10°C, for example, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C or 10°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] The molar ratio of chlorosulfonic acid to anhydrous hydrogen fluoride in the first mixture of the present invention is (1-4):1, for example, 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, 3.8:1 or 4:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, the first reaction is carried out at a temperature of -20°C to 10°C for 6 to 18 hours.

[0026] The first reaction in the present invention is carried out at a temperature of -20°C to 10°C, for example, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C or 10°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] The time of the first reaction in the present invention is 6 to 18 hours, for example, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours or 18 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] Preferably, the second mixing comprises: transferring fluorosulfonic acid to a separatory funnel and adding dropwise to a reaction vessel filled with sodium chloride at 50 to 120° C.;

[0029] The molar ratio of fluorosulfonic acid to sodium chloride in the second mixture is 1:(0.8-2).

[0030] The temperature of sodium chloride in the second mixture of the present invention is 50-120°C, for example, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0031] The molar ratio of fluorosulfonic acid to sodium chloride in the second mixture of the present invention is 1:(0.8-2), for example, it can be 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8 or 1:2, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] Preferably, the mass concentration of the sodium chloride is greater than 99wt%, for example, it can be 99wt%, 99.1wt%, 99.2wt%, 99.3wt%, 99.4wt%, 99.5wt%, 99.6wt%, 99.7wt%, 99.8wt% or 99.9wt%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] Preferably, the temperature of the second reaction is 70-150° C., and the second reaction ends when no gas is generated.

[0034] The temperature of the second reaction in the present invention is 70-150°C, for example, it can be 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] Preferably, the second reaction further includes purification, and the purification includes: in a protective atmosphere, cooling the crude sodium fluorosulfonate obtained in the second reaction, mixing it with high-purity anhydrous ethanol for a third time, filtering to remove unreacted sodium chloride, and then performing reduced pressure distillation to obtain battery-grade sodium fluorosulfonate;

[0036] Preferably, the temperature of the reduced pressure distillation is 20-60° C., the pressure is 5-50 mbar, and the reduced pressure distillation is stopped until the solution cannot be stirred.

[0037] The temperature of the reduced pressure distillation in the present invention is 20-60°C, for example, it can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] The pressure of the reduced pressure distillation in the present invention is 5 to 50 mbar, for example, it can be 5 mbar, 15 mbar, 20 mbar, 25 mbar, 30 mbar, 35 mbar, 40 mbar, 45 mbar or 50 mbar, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] The vacuum distillation in the present invention is stopped until the solution cannot be stirred. The state of being unable to stir is when the viscosity of the solution reaches or approaches the upper limit of the viscosity limited by the vacuum distillation device. At this time, the turbid liquid obtained by the vacuum distillation is observed to have no obvious fluidity.

[0040] Preferably, the water content in the high-purity anhydrous ethanol is 5 to 100 ppm, for example, it can be 5 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm or 100 ppm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Preferably, the third mixing temperature is 15-30° C., and the method includes stirring.

[0042] The temperature of the third mixing in the present invention is 15-30°C, for example, it can be 15°C, 17°C, 19°C, 20°C, 22°C, 24°C, 26°C, 28°C or 30°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] Preferably, the third mixing and the reduced pressure distillation further include filtering to obtain unreacted sodium chloride and a filtrate, the unreacted sodium chloride is reused as sodium chloride in the second mixing, and the filtrate is subjected to reduced pressure distillation.

[0044] Preferably, the material is filtered after the reduced pressure distillation, and the solid obtained after filtration is dried to obtain battery-grade sodium fluorosulfonate.

[0045] Preferably, the filtrate obtained after the filtration is returned to the reduced pressure distillation for further reduced pressure distillation.

[0046] As a preferred technical solution of the preparation method of the present invention, the preparation method comprises:

[0047] (1) In a protective atmosphere, chlorosulfonic acid is introduced into a fluorination bottle, and then the temperature is frozen and cooled to -20 to 10°C; anhydrous hydrogen fluoride is introduced into an anhydrous hydrogen fluoride generator at -20 to 19°C, and then the temperature of the anhydrous hydrogen fluoride in the anhydrous hydrogen fluoride generator is controlled to rise to 20 to 50°C;

[0048] (2) passing the anhydrous hydrogen fluoride in step (1) into the chlorosulfonic acid in the fluorination bottle, wherein the molar ratio of chlorosulfonic acid to the anhydrous hydrogen fluoride is (1-4):1, and reacting for 6-18 hours at a temperature of -20°C to 10°C to obtain fluorosulfonic acid;

[0049] (3) transferring the fluorosulfonic acid obtained in step (2) to a separatory funnel, and adding it dropwise to a reaction vessel containing sodium chloride at 50 to 120° C., wherein the molar ratio of the added fluorosulfonic acid to the sodium chloride is 1:(0.8 to 2), and reacting at 70 to 150° C. until the reaction is completed when no gas is generated, and then purging with a protective gas for 1 to 6 hours to obtain a crude sodium fluorosulfonate, and absorbing the tail gas with water during the purging process;

[0050] (4) In a protective atmosphere, the crude sodium fluorosulfonate obtained in the reaction of step (3) is cooled, and then stirred and washed with high-purity anhydrous ethanol having a moisture content of 5 to 100 ppm at 15 to 30° C., and unreacted sodium chloride and a filtrate are obtained by filtration. The unreacted sodium chloride is reused as sodium chloride in the mixing of step (3), and the filtrate is subjected to reduced pressure distillation at 20 to 60° C. and 5 to 50 mbar until the solution can no longer be stirred, and then the turbid liquid obtained by the reduced pressure distillation is filtered, and the solid obtained after filtration is dried to obtain battery-grade sodium fluorosulfonate, and the filtrate obtained after filtration is returned for reduced pressure distillation.

[0051] In a second aspect, the present invention provides a battery-grade sodium fluorosulfonate, wherein the battery-grade sodium fluorosulfonate is obtained by the preparation method described in the first aspect.

[0052] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] In the present invention, fluorosulfonic acid is prepared by reacting chlorosulfonic acid with anhydrous hydrogen fluoride, and then fluorosulfonic acid is reacted with sodium chloride to obtain battery-grade sodium fluorosulfonate. The preparation method does not use organic solvents when synthesizing battery-grade sodium fluorosulfonate, will not cause harm to the human body and is environmentally friendly. The tail gas can be sold as a by-product, and the reagents used in the preparation process can be recycled. In addition, the preparation method has a high yield when preparing battery-grade sodium fluorosulfonate, and the obtained battery-grade sodium fluorosulfonate has a high purity. DETAILED DESCRIPTION

[0055] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0056] Example 1

[0057] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, the preparation method comprising:

[0058] (1) In a protective atmosphere, chlorosulfonic acid is introduced into a fluorination bottle, and then the temperature is frozen and cooled to -5°C; anhydrous hydrogen fluoride is introduced into an anhydrous hydrogen fluoride generator at 0°C, and then the temperature of the anhydrous hydrogen fluoride in the anhydrous hydrogen fluoride generator is controlled to rise to 35°C;

[0059] (2) passing the anhydrous hydrogen fluoride in step (1) into the chlorosulfonic acid in the fluorination bottle, wherein the molar ratio of chlorosulfonic acid to the anhydrous hydrogen fluoride is 2.5:1, and reacting at a temperature of -5°C for 12 hours to obtain fluorosulfonic acid;

[0060] (3) transferring the fluorosulfonic acid obtained in step (2) to a separatory funnel, and adding it dropwise to a reaction vessel containing sodium chloride at 80° C., wherein the molar ratio of the added fluorosulfonic acid to the sodium chloride is 1:1.4, and reacting at 110° C. until the reaction is completed when no gas is generated, and then purging with protective gas for 4 hours to obtain a crude sodium fluorosulfonate product, and using water to absorb the tail gas during the purging process;

[0061] (4) In a protective atmosphere, the crude sodium fluorosulfonate obtained in the reaction of step (3) is cooled, and then stirred and washed with high-purity anhydrous ethanol having a moisture content of 50 ppm at 22° C., and unreacted sodium chloride and a filtrate are obtained by filtration. The unreacted sodium chloride is reused as sodium chloride in the mixing of step (3), and the filtrate is subjected to reduced pressure distillation at 40° C. and 25 mbar until the solution can no longer be stirred, and then the turbid liquid obtained by the reduced pressure distillation is filtered, and the solid obtained after filtration is dried to obtain battery-grade sodium fluorosulfonate, and the filtrate obtained after filtration is returned for reduced pressure distillation.

[0062] Example 2

[0063] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, the preparation method comprising:

[0064] (1) In a protective atmosphere, chlorosulfonic acid is introduced into a fluorination bottle, and then the temperature is frozen and cooled to -20°C; anhydrous hydrogen fluoride is introduced into an anhydrous hydrogen fluoride generator at -20°C, and then the temperature of the anhydrous hydrogen fluoride in the anhydrous hydrogen fluoride generator is controlled to rise to 20°C;

[0065] (2) passing the anhydrous hydrogen fluoride in step (1) into the chlorosulfonic acid in the fluorination bottle, wherein the molar ratio of chlorosulfonic acid to the anhydrous hydrogen fluoride is 4:1, and reacting for 18 hours at a temperature of -20°C to obtain fluorosulfonic acid;

[0066] (3) transferring the fluorosulfonic acid obtained in step (2) to a separatory funnel, and adding it dropwise to a reaction vessel containing sodium chloride at 120° C., wherein the molar ratio of the added fluorosulfonic acid to the sodium chloride is 1:2, and reacting at 150° C. until the reaction is completed when no gas is generated, and then purging with protective gas for 6 hours to obtain a crude sodium fluorosulfonate product, and using water to absorb the tail gas during the purging process;

[0067] (4) In a protective atmosphere, the crude sodium fluorosulfonate obtained in the reaction of step (3) is cooled, and then stirred and washed with high-purity anhydrous ethanol having a moisture content of 100 ppm at 30° C., and unreacted sodium chloride and a filtrate are obtained by filtration. The unreacted sodium chloride is reused as sodium chloride in the mixing of step (3), and the filtrate is subjected to reduced pressure distillation at 20° C. and 50 mbar until the solution can no longer be stirred, and then the turbid liquid obtained by the reduced pressure distillation is filtered, and the solid obtained after filtration is dried to obtain battery-grade sodium fluorosulfonate, and the filtrate obtained after filtration is returned for reduced pressure distillation.

[0068] Example 3

[0069] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, the preparation method comprising:

[0070] (1) In a protective atmosphere, chlorosulfonic acid is introduced into a fluorination bottle, and then the temperature is cooled to 10° C. by freezing; anhydrous hydrogen fluoride is introduced into an anhydrous hydrogen fluoride generator at 19° C., and then the temperature of the anhydrous hydrogen fluoride in the anhydrous hydrogen fluoride generator is controlled to rise to 50° C.;

[0071] (2) passing the anhydrous hydrogen fluoride in step (1) into the chlorosulfonic acid in the fluorination bottle, with the molar ratio of chlorosulfonic acid to the anhydrous hydrogen fluoride being 1:1, and reacting at a temperature of 10° C. for 6 hours to obtain fluorosulfonic acid;

[0072] (3) transferring the fluorosulfonic acid obtained in step (2) to a separatory funnel, and adding it dropwise to a reaction vessel containing sodium chloride at 50° C., wherein the molar ratio of the added fluorosulfonic acid to the sodium chloride is 1:0.8, and reacting at 70° C. until the reaction is completed when no gas is generated, and then purging with protective gas for 1 hour to obtain a crude sodium fluorosulfonate, and using water to absorb the tail gas during the purging process;

[0073] (4) In a protective atmosphere, the crude sodium fluorosulfonate obtained in the reaction of step (3) is cooled, and then stirred and washed with high-purity anhydrous ethanol having a moisture content of 5 ppm at 15° C., and unreacted sodium chloride and a filtrate are obtained by filtration. The unreacted sodium chloride is reused as sodium chloride in the mixing of step (3), and the filtrate is subjected to reduced pressure distillation at 60° C. and 5 mbar until the solution can no longer be stirred, and then the turbid liquid obtained by the reduced pressure distillation is filtered, and the solid obtained after filtration is dried to obtain battery-grade sodium fluorosulfonate, and the filtrate obtained after filtration is returned for reduced pressure distillation.

[0074] Example 4

[0075] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, which is the same as that of Embodiment 1 except that the chlorosulfonic acid is introduced into the fluorination bottle at a temperature of -30°C and the reaction is carried out at -30°C in step (2), and the temperature is the same as that of Embodiment 1.

[0076] Example 5

[0077] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, which is the same as that of Embodiment 1 except that the chlorosulfonic acid is introduced into the fluorination bottle at a temperature of 20° C. and the reaction is carried out at 20° C. in step (2).

[0078] Example 6

[0079] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, which is the same as that of Embodiment 1 except that the molar ratio of chlorosulfonic acid to anhydrous hydrogen fluoride introduced in step (2) is 0.5:1.

[0080] Example 7

[0081] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, which is the same as that of Embodiment 1 except that the molar ratio of chlorosulfonic acid to anhydrous hydrogen fluoride introduced in step (2) is 5:1.

[0082] Example 8

[0083] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, which is the same as that of Embodiment 1 except that the molar ratio of fluorosulfonic acid to sodium chloride introduced in step (3) is 1:0.4.

[0084] Example 9

[0085] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, which is the same as that of Embodiment 1 except that the molar ratio of fluorosulfonic acid to sodium chloride introduced in step (3) is 1:3.

[0086] Example 10

[0087] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, which is the same as that of Embodiment 1 except that the reaction temperature in step (3) is 50°C.

[0088] Embodiment 11

[0089] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, which is the same as that of Embodiment 1 except that the reaction temperature in step (3) is 180°C.

[0090] Example 12

[0091] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, which is the same as that of Embodiment 1 except that the temperature of the reduced pressure distillation in step (4) is 10°C.

[0092] Example 13

[0093] This embodiment provides a method for preparing battery-grade sodium fluorosulfonate, which is the same as that of Embodiment 1 except that the temperature of the reduced pressure distillation in step (4) is 80°C.

[0094] Comparative Example 1

[0095] This comparative example provides a method for preparing battery-grade sodium fluorosulfonate, which comprises: using dimethyl carbonate and propylene carbonate as solvents, reacting sodium chloride with anhydrous hydrogen fluoride in the solvents to prepare sodium fluorosulfonate.

[0096] Battery-grade sodium fluorosulfonate was prepared using the preparation method of battery-grade sodium fluorosulfonate provided in the above embodiments and comparative examples. The purity of the battery-grade sodium fluorosulfonate finally obtained was tested by ion chromatography as shown in Table 1. In addition, the yield of the battery-grade sodium fluorosulfonate finally obtained was tested, and the yield obtained was shown in Table 1.

[0097] Table 1

[0098] purity(%) Yield (%) Example 1 99.98 97.98 Example 2 99.97 96.65 Example 3 99.94 96.35 Example 4 98.98 92.46 Example 5 97.36 95.13 Example 6 96.42 94.63 Example 7 94.09 90.43 Example 8 95.61 92.36 Example 9 94.17 92.09 Example 10 94.79 91.10 Embodiment 11 90.13 91.49 Example 12 94.17 96.17 Example 13 99.90 89.09 Comparative Example 1 99.51 84.67

[0099] From Table 1, we can get:

[0100] (1) When preparing battery-grade sodium fluorosulfonate using the preparation method of battery-grade sodium fluorosulfonate provided in Examples 1 to 3, the purity of the obtained battery-grade sodium fluorosulfonate is greater than 99.9%, and the yield is greater than 90.5%;

[0101] (2) By comparing Example 1 with Examples 4 and 5, it can be seen that the temperature of freezing and cooling after the introduction of chlorosulfonic acid, the temperature of chlorosulfonic acid during the first mixing and the temperature during the reaction in the present invention will affect the purity and yield of the obtained battery-grade sodium fluorosulfonate; when the temperature of freezing and cooling after the introduction of chlorosulfonic acid, the temperature of chlorosulfonic acid during the first mixing and the temperature during the first reaction are -20 to 10°C, the purity and yield of the obtained battery-grade sodium fluorosulfonate are higher. This is because the reaction of fluorosulfonic acid and hydrogen fluoride is exothermic, and secondly, the vaporization temperature of hydrogen fluoride is 19°C. If the temperature of the first reaction is too high, hydrogen fluoride will be directly vaporized before reacting, resulting in a lower yield of battery-grade sodium fluorosulfonate; if the temperature of the first reaction is too low, it will result in too much energy consumption and cause side reactions to occur, resulting in a decrease in the purity of the battery-grade sodium fluorosulfonate;

[0102] (3) By comparing Example 1 with Examples 6 and 7, it can be seen that the molar ratio of chlorosulfonic acid to the anhydrous hydrogen fluoride introduced in step (2) affects the purity and yield of the obtained battery-grade sodium fluorosulfonate; when the molar ratio of chlorosulfonic acid to the anhydrous hydrogen fluoride introduced is (1-4):1, the purity and yield of the obtained battery-grade sodium fluorosulfonate are relatively high. This is because when the ratio of chlorosulfonic acid to hydrogen fluoride is too small, the hydrogen fluoride will not react fully, resulting in waste, and it is easy to introduce hydrogen fluoride as an impurity into the subsequent reaction, thereby reducing the purity of the battery-grade sodium fluorosulfonate; when the ratio of chlorosulfonic acid to hydrogen fluoride is too large, chlorosulfonic acid will be excessive, resulting in waste of chlorosulfonic acid, and chlorosulfonic acid will be introduced into the subsequent reaction, introducing impurities, thereby reducing the purity of the battery-grade sodium fluorosulfonate;

[0103] (4) By comparing Example 1 with Examples 8 and 9, it can be seen that the molar ratio of fluorosulfonic acid to sodium chloride introduced in step (3) affects the purity and yield of the obtained battery-grade sodium fluorosulfonate; when the molar ratio of fluorosulfonic acid to sodium chloride is 1:(0.8-2), the purity and yield of the obtained battery-grade sodium fluorosulfonate are relatively high. This is because when the molar ratio of fluorosulfonic acid to sodium chloride is too small, the content of unreacted sodium chloride is too high, resulting in a smaller yield of battery-grade sodium fluorosulfonate; when the molar ratio of fluorosulfonic acid to sodium chloride is too large, there will be too much fluorosulfonic acid, and the unreacted fluorosulfonic acid will become an impurity, resulting in a higher acid content, a lower purity, and a waste of materials and a low yield;

[0104] (5) By comparing Example 1 with Examples 10 and 11, it can be seen that the reaction temperature in step (3) affects the purity and yield of the obtained battery-grade sodium fluorosulfonate; when the reaction temperature is 70 to 150° C., the purity and yield of the obtained battery-grade sodium fluorosulfonate are higher. This is because at a temperature of 70 to 150° C., the reaction of sodium chloride and fluorosulfonic acid is sufficient, the reaction time is short, and the purity of the obtained battery-grade sodium fluorosulfonate is higher and the yield is greater;

[0105] (7) By comparing Example 1 with Comparative Example 1, it can be seen that in the present invention, fluorosulfonic acid is prepared by reacting chlorosulfonic acid with anhydrous hydrogen fluoride, and then fluorosulfonic acid is reacted with sodium chloride to obtain battery-grade sodium fluorosulfonate. The preparation method does not use organic solvents when preparing battery-grade sodium fluorosulfonate, will not cause harm to the human body and is environmentally friendly. The tail gas can be sold as a by-product, and the reagents used in the preparation process can be recycled. In addition, the preparation method has a higher yield when preparing battery-grade sodium fluorosulfonate, and the obtained battery-grade sodium fluorosulfonate has a higher purity.

[0106] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing battery-grade sodium fluorosulfonate, characterized in that: The preparation method comprises: First, chlorosulfonic acid and anhydrous hydrogen fluoride are mixed, and fluorosulfonic acid is obtained after a first reaction; second, sodium chloride is mixed with the obtained fluorosulfonic acid, and battery-grade sodium fluorosulfonate is obtained after a second reaction.

2. The preparation method according to claim 1, characterized in that: Before the first mixing, the method further comprises: introducing chlorosulfonic acid into the fluorination bottle in a protective atmosphere, and then freezing and cooling the temperature to -20 to 10°C; Before the first mixing, the method further comprises: introducing anhydrous hydrogen fluoride into the anhydrous hydrogen fluoride generator at -20 to 19°C, and then controlling the temperature of the anhydrous hydrogen fluoride in the anhydrous hydrogen fluoride generator to rise to 20 to 50°C.

3. The preparation method according to claim 2, characterized in that: The first mixing comprises: passing anhydrous hydrogen fluoride from an anhydrous hydrogen fluoride generator into chlorosulfonic acid at -20 to 10° C. in a fluorination bottle; The molar ratio of chlorosulfonic acid to anhydrous hydrogen fluoride in the first mixture is (1-4):

1.

4. The preparation method according to claim 1, characterized in that: The first reaction is carried out at a temperature of -20°C to 10°C for 6 to 18 hours.

5. The preparation method according to claim 1, characterized in that: The second mixing comprises: transferring fluorosulfonic acid to a separatory funnel and adding dropwise to a reaction vessel filled with sodium chloride at 50 to 120° C.; The molar ratio of fluorosulfonic acid to sodium chloride in the second mixture is 1:(0.8-2).

6. The preparation method according to claim 1, characterized in that: The temperature of the second reaction is 70-150° C., and the second reaction is terminated when no gas is generated.

7. The preparation method according to claim 1, characterized in that: The second reaction also includes purification, which includes: in a protective atmosphere, cooling the crude sodium fluorosulfonate obtained in the second reaction, mixing it with high-purity anhydrous ethanol for a third time, filtering to remove unreacted sodium chloride, and then performing reduced pressure distillation to obtain battery-grade sodium fluorosulfonate.

8. The preparation method according to claim 7, characterized in that: The temperature of the reduced pressure distillation is 20-60° C., the pressure is 5-50 mbar, and the reduced pressure distillation is stopped until the solution cannot be stirred.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The preparation method comprises: (1) In a protective atmosphere, chlorosulfonic acid is introduced into a fluorination bottle, and then the temperature is frozen and cooled to -20 to 10°C; anhydrous hydrogen fluoride is introduced into an anhydrous hydrogen fluoride generator at -20 to 19°C, and then the temperature of the anhydrous hydrogen fluoride in the anhydrous hydrogen fluoride generator is controlled to rise to 20 to 50°C; (2) passing the anhydrous hydrogen fluoride in step (1) into the chlorosulfonic acid in the fluorination bottle, wherein the molar ratio of chlorosulfonic acid to the anhydrous hydrogen fluoride is (1-4):1, and reacting for 6-18 hours at a temperature of -20°C to 10°C to obtain fluorosulfonic acid; (3) transferring the fluorosulfonic acid obtained in step (2) to a separatory funnel, and adding it dropwise to a reaction vessel containing sodium chloride at 50 to 120° C., wherein the molar ratio of the added fluorosulfonic acid to the sodium chloride is 1:(0.8 to 2), and reacting at 70 to 150° C. until the reaction is completed when no gas is generated, and then purging with a protective gas for 1 to 6 hours to obtain a crude sodium fluorosulfonate, and absorbing the tail gas with water during the purging process; (4) In a protective atmosphere, the crude sodium fluorosulfonate obtained in the reaction of step (3) is cooled, and then stirred and washed with high-purity anhydrous ethanol having a moisture content of 5 to 100 ppm at 15 to 30° C., and unreacted sodium chloride and a filtrate are obtained by filtration. The unreacted sodium chloride is reused as sodium chloride in the mixing of step (3), and the filtrate is subjected to reduced pressure distillation at 20 to 60° C. and 5 to 50 mbar until the solution can no longer be stirred, and then the turbid liquid obtained by the reduced pressure distillation is filtered, and the solid obtained after filtration is dried to obtain battery-grade sodium fluorosulfonate, and the filtrate obtained after filtration is returned for reduced pressure distillation.

10. A battery-grade sodium fluorosulfonate, characterized in that: The battery-grade sodium fluorosulfonate is obtained by the preparation method according to any one of claims 1 to 9.