Method for monitoring preparation process of bis (fluorosulfonyl) imide metal salt and preparation method of bis (fluorosulfonyl) imide metal salt

Abstract

The invention relates to a monitoring method for a preparation process of bis (fluorosulfonyl) imide metal salt and a preparation method. The monitoring method is used for monitoring the preparation process of synthesizing the bis (fluorosulfonyl) imide metal salt through double decomposition reaction of bis (fluorosulfonyl) imide and metal salt, and comprises the following steps: taking a real-time reaction solution sample of the double decomposition reaction; testing the real-time total mass content W2 of the free acid in the reaction solution sample and the real-time mass content W3 of the free acid HR in the reaction solution sample; according to the initial mass content W1 of the free acid in the imidodisulfuryl fluoride raw material, the real-time total mass content W2 of the free acid in the reaction solution sample and the mass content W3 of the free acid HR in the reaction solution sample, the percentage content X of the mass of the residual imidodisulfuryl fluoride in the reaction solution to the mass of the imidodisulfuryl fluoride raw material is obtained; and judging the preparation process of the bis (fluorosulfonyl) imide metal salt according to the X value. According to the method, the preparation process of the bis (fluorosulfonyl) imide metal salt can be effectively monitored.

Description

Technical Field

[0001] The invention relates to the technical field of testing and analysis, and in particular to a method for monitoring the preparation process of a bis(fluorosulfonyl)imide metal salt and a preparation method thereof. Background Art

[0002] Bis(fluorosulfonyl)imide metal salts are key high-performance electrolyte materials in new energy devices such as metal ion batteries and supercapacitors. Bis(fluorosulfonyl)imide metal salts can be prepared by double decomposition reaction of bis(fluorosulfonyl)imide and metal salt to synthesize bis(fluorosulfonyl)imide metal salts. In this process, how to monitor the raw material conversion process during the double decomposition reaction directly affects the yield and purity of the product.

[0003] Traditionally, online Raman monitoring equipment is used to monitor the reaction process by online sampling and analyzing the component content in the reaction solution; however, online Raman monitoring equipment is expensive and will greatly increase production costs. Summary of the invention

[0004] Based on this, it is necessary to provide a method for monitoring the preparation process of a bisfluorosulfonyl imide metal salt and a preparation method, which can effectively monitor the process of preparing a bisfluorosulfonyl imide metal salt using bisfluorosulfonyl imide.

[0005] In a first aspect of the present application, a method for monitoring the preparation process of a bisfluorosulfonyl imide metal salt is provided, wherein the method is used to monitor the preparation process of synthesizing a bisfluorosulfonyl imide metal salt by performing a double decomposition reaction of bisfluorosulfonyl imide and a metal salt, and the monitoring method comprises the following steps:

[0006] Taking a real-time reaction solution sample of the double decomposition reaction, testing the real-time total mass content W2 of free acid in the reaction solution sample and the real-time mass content W3 of free acid HR in the reaction solution sample;

[0007] According to the mass content W1 of the free acid in the raw material bisfluorosulfonyl imide, the real-time total mass content W2 of the free acid in the reaction solution sample, and the mass content W3 of the free acid HR in the reaction solution sample, the percentage X of the mass of the remaining bisfluorosulfonyl imide in the reaction solution is obtained;

[0008] According to the value of X, the preparation process of the bis(fluorosulfonyl)imide metal salt is judged;

[0009] The free acid HR is the free acid generated during the process of preparing bisfluorosulfonyl imide metal salt from bisfluorosulfonyl imide.

[0010] In the above monitoring process, the free acid mass content W1 in the reaction raw material bisfluorosulfonyl imide, the mass content W2 of the total free acid in the reaction solution, and the mass content W3 of the free acid HR generated in the reaction solution are mainly observed, and the mass content X of the remaining bisfluorosulfonyl imide in the reaction solution is obtained according to the values ​​of W1, W2 and W3, and the degree of reaction is determined by the value of X. The above method does not use expensive online Raman monitoring equipment, but obtains the values ​​of W1, W2 and W3 by simple testing methods, and then obtains the value of X; thus, the mass content of the remaining bisfluorosulfonyl imide in the reaction solution can be quickly and conveniently monitored, and then the reaction progress can be determined. This method is convenient and requires low investment costs.

[0011] In some embodiments, the step of obtaining X according to W1, W2 and W3 is obtained by the following formula:

[0012] X=(W2-W3) / W1×100%。

[0013] In some embodiments, the anion R in the metal salt includes at least one of a halogen ion, a carbonate ion, and a hydroxide ion; the cation Me in the metal salt includes at least one of a sodium ion, a lithium ion, a potassium ion, a rubidium ion, and a cesium ion.

[0014] In some embodiments, the free acid HR is HF or H2CO3.

[0015] In some embodiments, when the value of X is ≤1%, it is determined that the preparation process of the bis(fluorosulfonyl)imide metal salt is completed.

[0016] In some embodiments, ion chromatography is used to test the mass content W3 of free acid HR in the reaction solution sample.

[0017] In some embodiments, potentiometric titration is used to obtain the mass content W1 of free acid in the raw material bis(fluorosulfonyl)imide sample; and / or, potentiometric titration is used to obtain the real-time total mass content W2 of free acid in the reaction solution sample.

[0018] In some embodiments, in the potentiometric titration method, an ethanol solution of potassium hydroxide is used as a standard titrant.

[0019] In some embodiments, the step of testing the mass content W1 of free acid in the raw material bis(fluorosulfonyl)imide by potentiometric titration comprises:

[0020] Taking a portion of the raw material bis(fluorosulfonyl)imide sample to be tested, dissolving it in a first organic solvent, and then diluting it with an ethanol solution to obtain a sample 1 to be titrated, and performing potentiometric titration on the sample 1 to be titrated; and / or,

[0021] The step of testing the real-time total mass content W2 of free acid in the reaction solution sample by potentiometric titration comprises:

[0022] A portion of the reaction solution sample to be tested is taken, dissolved in a second organic solvent, and then diluted with an ethanol solution to obtain a sample 2 to be titrated, and the sample 2 to be titrated is subjected to potentiometric titration.

[0023] The second aspect of the present application provides a method for preparing a bis(fluorosulfonyl)imide metal salt, comprising the following steps:

[0024] In the double decomposition reaction of bisfluorosulfonyl imide and MeR metal salt, a bisfluorosulfonyl imide metal salt is prepared;

[0025] The preparation process of the bis(fluorosulfonyl)imide metal salt further includes a step of monitoring the reaction progress of the metathesis reaction, and the monitoring step includes the monitoring method described in the first aspect of the present application.

[0026] In some embodiments, the preparation method further comprises the step of obtaining bis(fluorosulfonyl)imide by fluorination reaction of bis(chlorosulfonyl)imide.

[0027] In some embodiments, the preparation method further comprises the following steps:

[0028] Fluorinating bis(chlorosulfonyl)imide to obtain the bis(fluorosulfonyl)imide;

[0029] During the fluorination reaction, the reaction solution in the fluorination reaction is subjected to ion chromatography to obtain an ion chromatogram, and whether the fluorination reaction is completed is determined based on whether there is a characteristic absorption peak of an intermediate product in the ion chromatogram.

[0030] In some embodiments, whether the fluorination reaction is completed is determined based on whether there is a characteristic absorption peak at a retention time of 24 min to 25 min in the ion chromatogram. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are merely embodiments of the present application, and ordinary technicians in this field can obtain other drawings based on the disclosed drawings without paying any creative work.

[0032] Figure 1 This is the ion chromatogram of the bis(chlorosulfonyl)imide raw material used in Example 1.

[0033] Figure 2 This is the ion chromatogram of the bis(fluorosulfonyl)imide standard.

[0034] Figure 3 This is the ion chromatogram of the fluorination reaction solution after the fluorination reaction time in Example 1 is 6 hours.

[0035] Figure 4 This is the ion chromatogram of the fluorination reaction solution after the fluorination reaction time in Example 1 is 22 hours.

[0036] Figure 5 This is the ion chromatogram of the fluorination reaction solution after the fluorination reaction time in Example 1 is 24 hours.

[0037] Figure 6 This is the ion chromatogram of the fluorination reaction solution after the fluorination reaction time in Example 1 is 27 hours.

[0038] Figure 7 This is the ion chromatogram of the fluorination reaction solution after the fluorination reaction time in Example 1 is 30 hours. DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present invention, the present invention is described more comprehensively below. And preferred embodiments of the present invention are given. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0041] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] The weight of the relevant components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also indicate the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the description of the embodiments of the present invention, it is within the scope disclosed in the description of the embodiments of the present invention. Specifically, the weight described in the description of the embodiments of the present invention may be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0043] Bis(fluorosulfonyl)imide metal salts are key high-performance electrolyte materials in new energy devices such as metal ion batteries and supercapacitors. The mainstream synthesis process of bis(fluorosulfonyl)imide metal salts is mainly divided into three steps: the first step is the synthesis of bis(chlorosulfonyl)imide; the second step is the fluorination reaction of bis(chlorosulfonyl)imide and HF to synthesize bis(fluorosulfonyl)imide; the third step is the double decomposition reaction of bis(fluorosulfonyl)imide to synthesize bis(fluorosulfonyl)imide metal salts. In this process, how to monitor the raw material conversion of each step of the reaction directly affects the yield and purity of the product.

[0044] The inventors have found through experiments that by using online Raman monitoring equipment to sample and analyze the component content in the reaction solution to monitor the reaction progress, it is possible to determine whether the reaction is complete; however, online Raman monitoring equipment is expensive and cannot detect changes in the concentration of various ions in the reaction solution.

[0045] In one embodiment of the present application, a method for monitoring the preparation process of a bisfluorosulfonyl imide metal salt is provided. The method is used to monitor the preparation process of synthesizing a bisfluorosulfonyl imide metal salt by performing a double decomposition reaction of bisfluorosulfonyl imide and a metal salt. The monitoring method comprises the following steps:

[0046] Take a real-time sample of the reaction solution of the double decomposition reaction, and test the real-time total mass content W2 of the free acid in the reaction solution sample and the real-time mass content W3 of the free acid HR in the reaction solution sample;

[0047] According to the mass content W1 of the free acid in the raw material bisfluorosulfonyl imide, the mass content W2 of the free acid in the reaction solution sample, and the mass content W3 of the free acid HR in the reaction solution sample, the percentage X of the mass of the remaining bisfluorosulfonyl imide in the reaction solution to the mass of the reaction solution is obtained;

[0048] The preparation process of bis(fluorosulfonyl)imide metal salt can be determined based on the value of X.

[0049] The free acid HR is the acid generated in the process of preparing bisfluorosulfonyl imide metal salt from bisfluorosulfonyl imide.

[0050] Among them, free acid refers to the acid that is ionized to H + Acids that exist in the form of radical ions.

[0051] The free acid content W1 refers to the free H + The mass content of HR when all of it exists in HR.

[0052] The real-time total mass content W2 of free acid in the reaction solution sample refers to the free H + The mass content of HR when all of it exists in HR.

[0053] In the above monitoring process, the free acid mass content W1 in the reaction raw material bisfluorosulfonyl imide, the free acid mass content W2 in the reaction solution, and the free acid HR mass content W3 in the reaction solution sample are mainly observed, and the mass content X of the remaining bisfluorosulfonyl imide in the reaction solution is obtained according to the values ​​of W1, W2 and W3, and the reaction is determined by the value of X. The above method does not use expensive online Raman monitoring equipment, but obtains the values ​​of W1, W2 and W3 through simple testing methods, and then obtains the value of X; thus, the mass content of the remaining bisfluorosulfonyl imide in the reaction solution can be quickly and conveniently monitored, and then the reaction progress can be determined. This method is convenient and requires low investment costs.

[0054] In some embodiments, the step of obtaining X according to W1, W2 and W3 is obtained by the following formula:

[0055] X=(W2-W3) / W1×100%。

[0056] The main process principle of preparing bisfluorosulfonyl imide metal salt from bisfluorosulfonyl imide is that bisfluorosulfonyl imide and metal salt (MeR) undergo double decomposition reaction to generate bisfluorosulfonyl imide metal salt and free acid HR; during the reaction, the free acid in the reaction solution mainly comes from the unreacted bisfluorosulfonyl imide and the generated free acid HR. The free acid content W1 in the raw material bisfluorosulfonyl imide, the total free acid content W2 in the reaction solution during the double decomposition reaction, and the free acid HR content W3 generated in the reaction solution during the double decomposition reaction are measured respectively. By subtracting W3 from W2, the free acid content in the unreacted bisfluorosulfonyl imide in the reaction solution can be obtained, so that the reaction progress of preparing bisfluorosulfonyl imide metal salt from bisfluorosulfonyl imide can be judged.

[0057] In some embodiments, when testing the mass content W1 of free acid in the reaction raw material bisfluorosulfonyl imide sample, the real-time total mass content W2 of free acid in the reaction solution sample, and the real-time mass content W3 of free acid HR in the reaction solution sample, the mass of the reaction raw material bisfluorosulfonyl imide sample and the reaction solution sample weighed are kept consistent (i.e., the mass is the same). It can be understood that the mass of the reaction raw material bisfluorosulfonyl imide sample to be weighed when testing the value of W1, the mass of the reaction solution sample to be weighed when testing the value of W2, and the mass of the reaction solution sample to be weighed when testing the value of W3 are the same.

[0058] In some embodiments, the free acid in the bis(fluorosulfonyl)imide raw material exists in the form of ions. The free acid in the reaction solution exists in the form of ions.

[0059] In some embodiments, the metal salt is present in the reaction solution in the form of ions.

[0060] In some embodiments, the anion R in the metal salt includes at least one of a halogen ion, a carbonate ion, and a hydroxide ion; the cation Me in the metal salt includes at least one of a sodium ion, a lithium ion, a potassium ion, a rubidium ion, and a cesium ion.

[0061] In some embodiments, when the value of X is ≤ 1%, the preparation process of the bis(fluorosulfonyl)imide metal salt is determined to be complete.

[0062] In some embodiments, the free acid HR is HF or H2CO3. It is understood that when the free acid HR is H2CO3, H2CO3 decomposes into water and CO2 in the reaction solution, and the detection value of the free acid HR in the reaction solution is 0.

[0063] In some embodiments, the mass content W1 of free acid in the reaction raw material bis(fluorosulfonyl)imide sample is tested by potentiometric titration.

[0064] In some embodiments, the step of testing the mass content W1 of free acid in the reaction raw material bis(fluorosulfonyl)imide sample by potentiometric titration comprises:

[0065] The reaction raw material bisfluorosulfonyl imide sample is dissolved in a first organic solvent, and then diluted with an ethanol solution to obtain a sample 1 to be titrated, and the sample 1 to be titrated is subjected to potentiometric titration.

[0066] In some embodiments, the ethanol solution is anhydrous ethanol with a purity of ≥99.7%.

[0067] In some embodiments, the first organic solvent is dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), or ethyl methyl carbonate (EMC).

[0068] In some embodiments, the purity of the first organic solvent is 99.99% or higher.

[0069] In some embodiments, the purity of the reaction raw material bis(fluorosulfonyl)imide is 99.0% to 99.7%.

[0070] In some embodiments, the concentration of bis(fluorosulfonyl)imide in the sample 1 to be titrated is 3 g / L to 10 g / L.

[0071] In some embodiments, the volume ratio of the first organic solvent to the ethanol solution in the sample 1 to be titrated is 1:(4-8).

[0072] In some embodiments, the above method further comprises performing potentiometric titration on the sample 1 to be titrated using a standard titrant, and when the titration is completed, recording the volume V1 of the consumed standard titrant.

[0073] In some embodiments, the above-mentioned potentiometric titration method uses an ethanol solution of potassium hydroxide as a standard titrant, wherein the ethanol solution of potassium hydroxide as a standard titrant can be expressed as a potassium hydroxide-ethanol standard titrant.

[0074] In some embodiments, the concentration C1 of potassium hydroxide in the potassium hydroxide-ethanol standard titration solution is 0.1 mol / L to 0.7 mol / L.

[0075] In some embodiments, the step of testing the mass content W1 of free acid in the reaction raw material bisfluorosulfonyl imide sample by potentiometric titration also includes: taking a mixed solution of the first organic solvent and ethanol as a control group 1, titrating the control group 1 with a standard titration solution, and recording the volume V2 of the standard titration solution consumed by the control group 1. The ratio of the mass of the first organic solvent to the volume of ethanol in the mixed solution of the control group 1 is consistent with the ratio of the mass of the first organic solvent to the volume of ethanol in the sample 1 to be titrated.

[0076] In some embodiments, the following formula (II) is used to obtain the value of W1.

[0077] (II)

[0078] Where:

[0079] W1---The mass content of free acid in the reaction raw material bis(fluorosulfonyl)imide, in ppm;

[0080] C1---the concentration of potassium hydroxide in the potassium hydroxide-ethanol standard titration solution, in mol / L;

[0081] V1---The volume of potassium hydroxide-ethanol standard titrant consumed in titrating the sample 1 to be titrated, in mL;

[0082] V2---The volume of potassium hydroxide-ethanol standard titration solution consumed in titration of control group 1, in mL;

[0083] M---the molar mass of HR, in g / mol;

[0084] m1---The mass of bis(fluorosulfonyl)imide in sample 1 to be titrated, in g.

[0085] In some embodiments, HR is HF, and the value of M in the above formula (II) is 20 g / mol.

[0086] In some embodiments, the mass content W2 of free acid in the reaction solution sample is tested by potentiometric titration.

[0087] In some embodiments, the step of testing the mass content W2 of free acid in the reaction solution sample by potentiometric titration comprises:

[0088] A portion of the reaction solution sample to be tested is taken, dissolved in a second organic solvent, and then diluted with an ethanol solution to obtain a sample 2 to be titrated, and the sample 2 to be titrated is subjected to potentiometric titration.

[0089] In some embodiments, the second organic solvent is dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), or ethyl methyl carbonate (EMC).

[0090] In some embodiments, the mass ratio of the reaction solution in the sample 2 to be titrated to the volume ratio of the ethanol solution is 1 g:(70 mL-170 mL).

[0091] In some embodiments, the ratio of the volume of the second organic solvent to the volume of the ethanol solution in the sample 2 to be titrated is 1:(4-8).

[0092] In some embodiments, the above method further comprises performing potentiometric titration on the sample 2 to be titrated using a standard titrant, and when the titration is completed, recording the volume V3 of the consumed standard titrant.

[0093] In some embodiments, the step of testing the mass content W2 of free acid in the reaction solution sample by potentiometric titration further comprises:

[0094] The mixed solution of the second organic solvent and ethanol is used as the control group 2, and the control group 2 is titrated with the standard titrant, and the volume V4 of the standard titrant consumed by the control group 2 is recorded. The ratio of the mass of the second organic solvent to the volume of ethanol in the mixed solution of the control group 2 is consistent with the ratio of the mass of the second organic solvent to the volume of ethanol in the sample 2 to be titrated.

[0095] In some embodiments, the following formula (III) is used to obtain the value of W2.

[0096] (III)

[0097] Where:

[0098] W2---The mass content of total free acid in the reaction solution, in ppm;

[0099] C1---the concentration of potassium hydroxide in the potassium hydroxide-ethanol standard titration solution, in mol / L;

[0100] V3---The volume of potassium hydroxide-ethanol standard titrant consumed in titrating the sample 2 to be tested, in mL;

[0101] V4---The volume of potassium hydroxide-ethanol standard titration solution consumed in titration of control group 2, in mL;

[0102] M---the molar mass of HR, in g / mol;

[0103] m2---The mass of the reaction solution in sample 2 to be titrated, in g.

[0104] In some embodiments, ion chromatography is used to test the mass content W3 of free acid HR in the reaction solution sample.

[0105] In some embodiments, the step of testing the mass content W3 of free acid HR in the reaction solution sample by ion chromatography comprises:

[0106] A portion of the reaction solution sample to be tested is diluted to obtain a sample 3 to be tested; the sample 3 to be tested is tested using an ion chromatograph to obtain an ion chromatogram, and the area A1 of the characteristic absorption peak corresponding to the R ion is read.

[0107] In some embodiments, when diluting a portion of the reaction solution sample to be tested, ultrapure water with a temperature of 4° C. to 7° C. is used for dilution. Controlling the temperature of the diluent is beneficial to inhibiting the hydrolysis of the reaction solution to be tested, thereby improving the accuracy of the test data.

[0108] In some embodiments, the step of testing the mass content W3 of free acid HR in the reaction solution sample by ion chromatography further comprises:

[0109] A standard aqueous solution of R ions is prepared, and the standard solution is tested using an ion chromatograph to obtain an ion chromatogram, and the area A2 of the characteristic absorption peak corresponding to the R ions is read.

[0110] In some embodiments, the mass content W3 of the free acid HR in the reaction solution sample is calculated as shown in the following formula (IV):

[0111] (IV)

[0112] Where:

[0113] W3---mass content of free acid HR in the reaction solution, in ppm;

[0114] C2---The concentration of R ions in the R ion standard solution, in mg / L;

[0115] A1---Characteristic absorption peak area of ​​R ion in sample 3 to be tested;

[0116] A2---Characteristic absorption peak area of ​​R ion in R ion standard solution;

[0117] V5---the total volume of the sample 3 after dilution, in mL;

[0118] m2---The mass of the reaction solution sample in the sample 3 to be tested, in g.

[0119] B--R ion corresponding to the relative atomic mass.

[0120] In some embodiments, the free acid HR is HF, and the value of B is 19.

[0121] In another embodiment of the present application, a method for preparing a bis(fluorosulfonyl)imide metal salt is provided, comprising the following steps:

[0122] In the double decomposition reaction of bisfluorosulfonyl imide and MeR metal salt, a bisfluorosulfonyl imide metal salt is prepared;

[0123] The preparation process of the bis(fluorosulfonyl)imide metal salt further includes a step of monitoring the progress of the double decomposition reaction, and the monitoring step includes the above-mentioned method for monitoring the preparation process of the bis(fluorosulfonyl)imide metal salt.

[0124] In some embodiments, the method for preparing a bisfluorosulfonyl imide metal salt further includes a step of obtaining a bisfluorosulfonyl imide by fluorination reaction of bischlorosulfonyl imide.

[0125] In some embodiments, the method for preparing a bisfluorosulfonyl imide metal salt further includes a step of obtaining a bisfluorosulfonyl imide by fluorination reaction of bischlorosulfonyl imide with hydrogen fluoride.

[0126] In some embodiments, the above preparation method further comprises the following steps:

[0127] Fluorination reaction of bischlorosulfonyl imide to obtain bisfluorosulfonyl imide;

[0128] During the fluorination reaction, the reaction solution in the fluorination reaction is subjected to ion chromatography to obtain an ion chromatogram, and whether the fluorination reaction is completed is determined based on whether there is a characteristic absorption peak of an intermediate product in the ion chromatogram.

[0129] During the process of synthesizing bischlorosulfonyl imide by fluorination reaction to obtain bisfluorosulfonyl imide, one of the chlorine atoms in bischlorosulfonyl imide will be replaced first to obtain an intermediate product containing one fluorine and one chlorine. By observing whether there are characteristic absorption peaks of the intermediate product containing one fluorine and one chlorine in the ion chromatogram of the reaction solution during the reaction, the progress of the reaction can be observed to determine whether the reaction of synthesizing bischlorosulfonyl imide by fluorination to obtain bisfluorosulfonyl imide is completed. Among them, the structural formula of the intermediate product containing one fluorine and one chlorine is as follows:

[0130] .

[0131] In some embodiments, the ion chromatogram of the monofluoro-monochloro intermediate has a characteristic absorption peak at a retention time of 24 min to 25 min.

[0132] In some embodiments, whether the fluorination synthesis reaction is completed is determined based on whether there is a characteristic absorption peak at a retention time of 24 min to 25 min in the ion chromatogram. When there is a characteristic absorption peak at a retention time of 24 min to 25 min in the ion chromatogram, it is determined that the fluorination synthesis reaction is not yet completed.

[0133] In some embodiments, the characteristic absorption peak of the intermediate product is at a position with a retention time of 24.86 min in the ion chromatogram.

[0134] In some embodiments, the preparation method further comprises the following step: sampling at least twice after the reaction starts to observe the change in the content of the monofluoro-monochloro intermediate product in the process of fluorination of bischlorosulfonyl imide to obtain bisfluorosulfonyl imide.

[0135] In order to make the purpose, technical solutions and advantages of the present invention more concise and clear, the present invention is described with the following specific embodiments, but the present invention is by no means limited to these embodiments. The embodiments described below are only preferred embodiments of the present invention, which can be used to describe the present invention and cannot be understood as limiting the scope of the present invention. It should be pointed out that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0136] In order to better illustrate the present invention, the present invention is further described below in conjunction with the embodiments. The following are specific embodiments.

[0137] Example 1

[0138] Preparation of lithium bis(fluorosulfonyl)imide:

[0139] 1. Preparation of bis(fluorosulfonyl)imide:

[0140] The fluorination reaction was carried out using bis(chlorosulfonyl)imide and HF as raw materials. Samples were taken and analyzed during the reaction to observe the changes in the characteristic peaks of the monofluoro-monochloro intermediate products in the ion chromatogram of the reaction solution as the reaction proceeded. The specific operation steps are as follows:

[0141] Accurately weigh 0.2 g (accurate to 0.0001 g) of fluorination reaction solution into a 100 mL volumetric flask at different reaction time periods, dilute to 100 mL with ultrapure water at 4°C, measure the sample solution with an ion chromatograph, and monitor the change in the peak area of ​​the characteristic peak of the monofluoro-monochloro intermediate product in the ion chromatogram. When the characteristic peak of the monofluoro-monochloro intermediate product disappears in the ion chromatogram of the sample solution, it means that the reaction is complete and bis(fluorosulfonyl)imide is obtained.

[0142] See also Figure 1 to Figure 7 , Figure 1This is the ion chromatogram of the bis(chlorosulfonyl)imide raw material used in this embodiment, Figure 2 This is the ion chromatogram of the purchased bis(fluorosulfonyl)imide standard. Figure 3 is the ion chromatogram of the fluorination reaction solution after the fluorination reaction time is 6 hours. Figure 4 is the ion chromatogram of the fluorination reaction solution after the fluorination reaction time is 22h. Figure 5 is the ion chromatogram of the fluorination reaction solution after the fluorination reaction time is 24h. Figure 6 is the ion chromatogram of the fluorination reaction solution after the fluorination reaction time is 27h. Figure 7 This is the ion chromatogram of the fluorination reaction solution after the fluorination reaction time is 30 hours. Figure 1 to Figure 7 It can be found that in the ion color diagram of the reaction solution at different reaction time periods, the position of 24min~25min has a significant difference from Figure 1 and Figure 2 The characteristic absorption peak here is the characteristic absorption peak of the monofluoro-monochloro intermediate product. When the reaction time reaches 30h, the characteristic absorption peak at 24min~25min in the reaction solution disappears, indicating that the reaction is completed and bischlorosulfonyl imide is completely converted into bisfluorosulfonyl imide.

[0143] 2. Preparation of Lithium Bis(Fluorosulfonyl)imide

[0144] The bis(fluorosulfonyl)imide obtained in step 1 and lithium fluoride (MeR=LiF) are used as raw materials to react and prepare bis(fluorosulfonyl)imide metal lithium. Three production lines are set up for the reaction of bis(fluorosulfonyl)imide and lithium fluoride to prepare bis(fluorosulfonyl)imide metal lithium; the raw materials, ratios and reaction conditions in the three production lines are the same, except for the reaction time; the reactions in the three production lines are monitored according to the following steps:

[0145] The reaction monitoring method of the first production line:

[0146] 1) Prepare a potassium hydroxide-ethanol standard solution with a concentration of 0.5 mol / L.

[0147] 2) Test the free acid content W1 in the bis(fluorosulfonyl)imide raw material

[0148] (1) In a glove box, weigh 0.5 g (accurate to 0.0001 g) of the raw material bis(fluorosulfonyl)imide sample into a titration cup containing 9 mL of DMC solution, add 50 mL of ethanol solution into the titration cup, mix thoroughly to obtain the sample 1 to be titrated, and then place the sample on a potentiometric titrator with set parameters for automatic titration. Record the volume V1 of the potassium hydroxide-ethanol standard titration solution consumed.

[0149] (2) Set up a blank control group. Add 9 mL of DMC solution to 50 mL of ethanol solution in a titration cup and mix thoroughly to obtain control group 1. Then place the sample on a potentiometric titrator with set parameters for automatic titration. Record the volume V2 of the potassium hydroxide-ethanol standard titration solution consumed.

[0150] (3) Calculate the free acid content in the raw material bis(fluorosulfonyl)imide according to the following formula:

[0151]

[0152] Where:

[0153] W1---the free acid mass content in the raw material bis(fluorosulfonyl)imide, in ppm;

[0154] C1---Concentration of potassium hydroxide-ethanol standard solution, in mol / L;

[0155] V1---The volume of potassium hydroxide-ethanol standard solution consumed in titrating the sample 1 to be titrated, in mL;

[0156] V2---The volume of potassium hydroxide-ethanol standard solution consumed by titrating control group 1, in mL;

[0157] M---the molar mass of HF, which is 20.00 g / mol;

[0158] m1---The mass of bis(fluorosulfonyl)imide, in g.

[0159] 2) Free acid content W2 in double decomposition reaction solution-1

[0160] (1) In the glove box, weigh 0.5 g (accurate to 0.0001 g) of the double decomposition solution -1 in the first production line into a titration cup containing 9 mL of DMC solution, add 50 mL of ethanol solution into the titration cup, mix thoroughly to obtain the sample 2 to be titrated, and then place it on a potentiometric titrator with set parameters for automatic titration, and record the volume V3 of the potassium hydroxide-ethanol standard titration solution consumed.

[0161] (2) Set up a blank control group. Add 9 mL of DMC solution to 50 mL of ethanol solution in a titration cup and mix thoroughly to obtain control group 2. Then place the sample on a potentiometric titrator with set parameters for automatic titration. Record the volume V2 of the potassium hydroxide-ethanol standard titration solution consumed.

[0162] (3) Calculate the free acid content in the double decomposition reaction solution-1 according to the following formula:

[0163]

[0164] Where:

[0165] W2---free acid mass content in double decomposition reaction solution-1, in ppm;

[0166] C1---Concentration of potassium hydroxide-ethanol standard solution, in mol / L;

[0167] V3---The volume of potassium hydroxide-ethanol standard solution consumed by titrating the double decomposition reaction solution-1 sample, in mL;

[0168] V4---The volume of potassium hydroxide-ethanol standard solution consumed in titrating DMC solution, in mL;

[0169] M---the molar mass of HF, which is 20.00 g / mol;

[0170] m2---The mass of double decomposition reaction solution-1, in g.

[0171] 3) Test the mass content of free acid HF in the double decomposition reaction solution-1 W3

[0172] (1) In a glove box, weigh 0.5 g (accurate to 0.0001 g) of the double decomposition reaction solution -1 in the first production line into a 100 mL volumetric flask, dilute to volume with ultrapure water at 4°C, and use an ion chromatograph to determine the fluoride ion content in the sample solution. The HF content in the sample can be calculated based on the fluoride ion content, thereby calculating the free acid content in HF. The specific calculation formula is as follows:

[0173]

[0174] Where:

[0175] W3---mass content of free acid HF in the double decomposition reaction solution-1 sample in the first production line, in ppm;

[0176] C2---the concentration of the fluoride ion standard solution, in mg / kg; in this embodiment, C2 is 2.0 mg / kg;

[0177] A1---Characteristic absorption peak area of ​​fluoride ions in the sample solution;

[0178] A2---Characteristic absorption peak area of ​​fluoride ion in fluoride ion standard solution;

[0179] V5---the total volume of the double decomposition reaction solution-1 sample, in mL;

[0180] m3---mass of double decomposition reaction solution-1 sample, in g;

[0181] B--The relative atomic mass of fluorine is 19.

[0182] 4) Calculate the test value X of bis(fluorosulfonyl)imide in mixed sample-1

[0183] Combining the results of the above potentiometric titration and ion chromatography, the content of unreacted bisfluorosulfonyl imide in the double decomposition reaction solution in the first production line can be calculated, thereby monitoring the progress of the reaction of bisfluorosulfonyl imide to synthesize bisfluorosulfonyl imide metal salt. The specific calculation formula is as follows:

[0184] X=(W2-W3) / W1×100%

[0185] Where:

[0186] X---the percentage of the mass of the remaining bis(fluorosulfonyl)imide in the metathesis reaction solution-1 to the mass of the metathesis reaction solution-1, unit is %;

[0187] W1---the free acid mass content in the raw material bis(fluorosulfonyl)imide, in ppm;

[0188] W2---free acid mass content in double decomposition reaction solution-1, in ppm;

[0189] W3---Mass content of free acid HF in double decomposition reaction solution-1, in ppm.

[0190] The above test results are shown in Table 1.

[0191] The monitoring methods in the second and third production lines are consistent with the monitoring method of the first production line. The specific test results are shown in Table 1 below.

[0192] Table 1

[0193]

[0194] Note: The residual HFSI content X in the reaction solution is the percentage of the mass of the remaining unreacted HFSI in the metathesis reaction solution to the mass of the entire reaction solution.

[0195] From the data in Table 1, it can be seen that the minimum HFSI mass content in the reaction solution of the third production line corresponding to the metathesis reaction liquid-3 is 0.455%, and is less than 1%, which means that the reaction of the third production line corresponding to the metathesis reaction liquid-3 has been completed.

[0196] Example 2

[0197] Accuracy test of the method for monitoring the reaction process of bisfluorosulfonyl imide to synthesize bisfluorosulfonyl imide metal salt:

[0198] Appropriate amounts of bis(fluorosulfonyl)imide metal lithium standard and bis(fluorosulfonyl)imide standard were weighed and mixed to prepare mixed samples-1, mixed samples-2 and mixed samples-3 with different bis(fluorosulfonyl)imide mass concentrations. The specific proportions of the bis(fluorosulfonyl)imide metal lithium standard and the bis(fluorosulfonyl)imide standard in the above mixed samples are shown in Table 1.

[0199] The test methods of free acid content, free acid HF content, and free acid content in HFSI standard samples in mixed sample-1, mixed sample-2, and mixed sample-3 are consistent with the test methods in the metathesis reaction solution-1 in Example 1. HF is not added to the mixed sample-1, mixed sample-2, and mixed sample-3 configured in this embodiment, and when the free acid HF content in the mixed sample is tested, the test values ​​are all 0. The calculation results of the content X value of bisfluorosulfonyl imide in mixed sample-1, mixed sample-2, and mixed sample-3 are shown in Table 2.

[0200] Table 2

[0201]

[0202] Note: The mass content of HFSI in the mixed sample in the table (wt%) = the mass of bis(fluorosulfonyl)imide standard sample / the total mass of the mixed sample × 100% = the mass of bis(fluorosulfonyl)imide standard sample / (the mass of bis(fluorosulfonyl)imide standard sample + the mass of bis(fluorosulfonyl)imide metal lithium standard sample) × 100%.

[0203] Deviation = (Content of HFSI in the mixed sample X-Mass content of HFSI in the mixed sample) / Mass content of HFSI in the mixed sample × 100%.

[0204] From the data in Table 2, it can be seen that the test method of the present application can more accurately test the content of bis(fluorosulfonyl)imide in the mixed sample, indicating that the monitoring test method of the present application is feasible.

[0205] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0206] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A method for monitoring the preparation process of a bis(fluorosulfonyl)imide metal salt, characterized in that: The method is used to monitor the preparation process of synthesizing bisfluorosulfonyl imide metal salt by double decomposition reaction of bisfluorosulfonyl imide and metal salt, and the monitoring method comprises the following steps: Taking a real-time reaction solution sample of the double decomposition reaction, testing the real-time total mass content W2 of free acid in the reaction solution sample and the real-time mass content W3 of free acid HR in the reaction solution sample; According to the mass content W1 of the free acid in the raw material bisfluorosulfonyl imide for synthesizing the bisfluorosulfonyl imide metal salt, the real-time total mass content W2 of the free acid in the reaction solution sample, and the mass content W3 of the free acid HR in the reaction solution sample, the percentage X of the mass of the remaining bisfluorosulfonyl imide in the reaction solution to the mass of the reaction solution is obtained; According to the value of X, the preparation process of the bis(fluorosulfonyl)imide metal salt is judged; The free acid HR is the free acid generated during the process of preparing bisfluorosulfonyl imide metal salt from bisfluorosulfonyl imide.

2. The monitoring method according to claim 1, characterized in that: According to W1, W2 and W3, the steps to obtain X are obtained by the following formula: X=(W2-W3) / W1×100%。 3. The monitoring method according to claim 1, characterized in that: When X≤1%, it is determined that the preparation process of the bis(fluorosulfonyl)imide metal salt is completed.

4. The monitoring method according to claim 1, characterized in that: The anion R in the metal salt includes at least one of a halogen ion, a carbonate ion and a hydroxide ion; the cation Me in the metal salt includes at least one of a sodium ion, a lithium ion, a potassium ion, a rubidium ion and a cesium ion.

5. The monitoring method according to claim 4, characterized in that: The free acid HR is HF or H2CO3.

6. The monitoring method according to claim 5, characterized in that: Ion chromatography was used to determine the free acid HR according to R - The content of free acid HR in the reaction solution sample is tested by W3.

7. The monitoring method according to any one of claims 1 to 6, characterized in that: The mass content W1 of free acid in the raw material bis(fluorosulfonyl)imide is obtained by potentiometric titration; and / or, the real-time total mass content W2 of free acid in the reaction solution is obtained by potentiometric titration.

8. The monitoring method according to claim 7, characterized in that: In the potentiometric titration method, an ethanol solution of potassium hydroxide is used as a standard titrant.

9. The monitoring method according to claim 8, characterized in that: The step of testing the mass content W1 of free acid in the raw material bis(fluorosulfonyl)imide by potentiometric titration comprises: Taking a portion of the raw material bis(fluorosulfonyl)imide sample to be tested, dissolving it in a first organic solvent, and then diluting it with an ethanol solution to obtain a sample 1 to be titrated, and performing potentiometric titration on the sample 1 to be titrated; and / or, The step of testing the real-time total mass content W2 of free acid in the reaction solution sample by potentiometric titration comprises: A portion of the reaction solution sample to be tested is taken, dissolved in a second organic solvent, and then diluted with an ethanol solution to obtain a sample 2 to be titrated, and the sample 2 to be titrated is subjected to potentiometric titration.

10. A method for preparing a bis(fluorosulfonyl)imide metal salt, characterized in that: The steps include: In the double decomposition reaction of bisfluorosulfonyl imide and metal salt, bisfluorosulfonyl imide metal salt is prepared; Wherein, the preparation process of the bis(fluorosulfonyl)imide metal salt further includes a step of monitoring the reaction progress of the metathesis reaction, and the monitoring step includes the monitoring method according to any one of claims 1 to 9.

11. The preparation method according to claim 10, characterized in that: The method also includes the step of obtaining bisfluorosulfonyl imide by fluorination reaction of bischlorosulfonyl imide.

12. The preparation method according to claim 11, characterized in that: The preparation method further comprises the following steps: Fluorinating bis(chlorosulfonyl)imide to obtain the bis(fluorosulfonyl)imide; During the fluorination reaction, the reaction liquid in the fluorination reaction process is subjected to ion chromatography to obtain an ion chromatogram, and whether the fluorination reaction is completed is determined based on whether there is a characteristic absorption peak of an intermediate product in the ion chromatogram.

13. The preparation method according to claim 12, characterized in that: Whether the fluorination reaction is completed is determined based on whether there is a characteristic absorption peak at a retention time of 24 min to 25 min in the ion chromatogram.

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