Bis (fluorosulfonyl) imide metal liquid salt and preparation method thereof

Abstract

The invention provides a bis (fluorosulfonyl) imide metal liquid salt and a preparation method thereof, and the preparation method comprises the following steps: reacting bis (fluorosulfonyl) imide with a fluorinated metal compound to obtain a molten reaction liquid, and carrying out devolatilization treatment on the reaction liquid until the EP1 acidity (calculated as HF) is less than or equal to 0.5 ppm to obtain a bis (fluorosulfonyl) imide compound, the preparation method comprises the following steps: dissolving difluorosulfonylimide in a solvent, and carrying out resin deacidification treatment to obtain difluorosulfonylimide metal liquid salt at a heating temperature of lower than 140 DEG C. The invention further discloses a preparation method of the difluorosulfonylimide metal liquid salt. The purity of the molten-state imidodisulfuryl fluoride metal liquid salt prepared through the preparation method of the imidodisulfuryl fluoride metal liquid salt is high, and the method has the advantages of being high in preparation efficiency and low in cost.

Description

Technical Field

[0001] The invention relates to a preparation method of a bisfluorosulfonyl imide metal compound, in particular to a bisfluorosulfonyl imide metal liquid salt and a preparation method thereof, belonging to the technical field of new energy materials. Background Art

[0002] As people pay more and more attention to the green and low-carbon economy, metal compound batteries (such as lithium batteries and sodium batteries) have attracted much attention due to their advantages such as high operating voltage, high energy density, long life and no memory effect, and are widely used in new energy vehicles, digital products, energy storage instruments and other fields. Batteries are composed of four major components: positive electrode, negative electrode, diaphragm and electrolyte. Among them, the electrolyte has a significant impact on the cycle life, high and low temperature performance and safety performance of the battery.

[0003] Hexafluorophosphate metal compounds (such as LiPF6, NaPF6) are currently widely used liquid salt electrolytes, but they still have a series of disadvantages, such as poor thermal stability, poor stability to water, and decomposition to release HF. Bisfluorosulfonyl imide metal compounds (such as LiFSI, NaFSI) are new fluorine-containing metal salts that can be used as the next generation main component of electrolytes. Compared with hexafluorophosphate metal compounds, bisfluorosulfonyl imide metal compounds have a higher decomposition temperature, higher stability to water, and better electrical properties such as conductivity.

[0004] At present, bis(fluorosulfonyl)imide metal compounds are prepared by reacting bis(fluorosulfonyl)imide or its derivatives with alkali metal salts. After the preparation, it is necessary to remove residual acid or high-boiling liquid impurities such as by-product water. However, conventional impurity removal methods are costly and time-consuming, which limits the large-scale production of bis(fluorosulfonyl)imide metal compounds.

[0005] Therefore, how to improve the preparation efficiency and reduce the cost while ensuring the high purity of the bis(fluorosulfonyl)imide metal compound is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0006] The invention provides a method for preparing a bisfluorosulfonyl imide metal liquid salt. The method can prepare a bisfluorosulfonyl imide metal liquid salt with high purity, and the method has the advantages of high production efficiency, low cost, and the like.

[0007] The invention provides a bisfluorosulfonyl imide metal liquid salt, which has high purity.

[0008] The present invention provides a method for preparing a bis(fluorosulfonyl)imide metal liquid salt, which comprises the following steps:

[0009] A bisfluorosulfonyl imide and a fluorinated metal compound are reacted to obtain a molten reaction liquid, the reaction liquid is subjected to a devolatilization treatment until the EP1 (first equivalence point) acidity in terms of HF is ≤ 0.5 ppm to obtain a bisfluorosulfonyl imide metal compound, which is then dissolved in a solvent and then subjected to a resin deacidification treatment to obtain a bisfluorosulfonyl imide metal liquid salt;

[0010] Wherein, the heating temperature of the devolatilization treatment is lower than 140°C.

[0011] The method for preparing the bis(fluorosulfonyl)imide metal liquid salt as described above, wherein the vacuum degree of the devolatilization treatment is 1-0.1 kPa, the heating temperature is not less than 60° C., and the treatment time is 10-20 h;

[0012] Preferably, the heating temperature is 100-135°C.

[0013] In the method for preparing the bisfluorosulfonyl imide metal liquid salt as described above, the dissolution of the bisfluorosulfonyl imide metal compound in the solvent is carried out while maintaining the molten state.

[0014] The method for preparing the bisfluorosulfonyl imide metal liquid salt as described above, wherein the temperature of the obtained bisfluorosulfonyl imide metal compound is maintained and the bisfluorosulfonyl imide metal compound is mixed into a solvent so that the bisfluorosulfonyl imide metal compound is kept in the molten state and dissolved in the solvent.

[0015] The method for preparing the bis(fluorosulfonyl)imide metal liquid salt as described above, wherein the solvent is an electrolyte solvent, and the electrolyte solvent includes at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and ethylene carbonate;

[0016] The mass ratio of the bisfluorosulfonyl imide metal compound to the electrolyte solvent is (59:141)-(61:139).

[0017] The method for preparing the bis(fluorosulfonyl)imide metal liquid salt as described above, wherein the resin comprises one of poly(4-vinylpyridine) (PEP) resin, poly(N,N-dimethyl-p-styrene) (PEB) resin, and poly(N,N-diethyl-p-styrene) (PED) resin;

[0018] A / B is 1-5%, wherein A is the mass of the resin, and B is the mass of the bisfluorosulfonyl imide metal compound.

[0019] In the method for preparing the bis(fluorosulfonyl)imide metal liquid salt as described above, the molten reaction liquid is prepared by reacting bis(fluorosulfonyl)imide and a metal fluoride compound in the absence of a solvent.

[0020] The method for preparing the bisfluorosulfonyl imide metal liquid salt as described above, wherein the reaction temperature of the bisfluorosulfonyl imide and the metal fluoride compound is 130-140° C., and the reaction time is 4-8 hours; and / or the molar ratio of the bisfluorosulfonyl imide and the metal fluoride compound is 1:(0.95-1.05).

[0021] The method for preparing the bis(fluorosulfonyl)imide metal liquid salt as described above, wherein the turbidity of the reaction solution is ≤100;

[0022] Alternatively, the EP1 acidity of the reaction solution calculated as HF is ≤100 ppm.

[0023] The method for preparing the bisfluorosulfonyl imide metal liquid salt as described above, wherein the bisfluorosulfonyl imide comprises, in terms of mass percentage:

[0024] Bisfluorosulfonyl imide 99.93-100%, aminosulfonate ≤200ppm, fluorosulfonate ≤300ppm, fluorosulfonamide ≤100ppm, chloride ion ≤50ppm, fluoride ion ≤50ppm;

[0025] And / or, the metal fluoride compound includes one of lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride, cesium fluoride and francium fluoride;

[0026] And / or, the metal fluoride compound comprises, by mass percentage:

[0027] Fluoride metal compound 99.84-100%, carbonate metal compound ≤1000ppm, water ≤600ppm.

[0028] The method for preparing the bis(fluorosulfonyl)imide metal compound as described above, wherein, before the resin deacidification treatment, the method further comprises performing a first filtration treatment on the bis(fluorosulfonyl)imide metal compound solution;

[0029] And / or, after the resin deacidification treatment, the method further includes performing a second filtration treatment on the deacidified solution system.

[0030] The present invention also provides a bisfluorosulfonyl imide metal liquid salt, wherein the bisfluorosulfonyl imide metal liquid salt is prepared by the preparation method of the bisfluorosulfonyl imide metal compound as described above;

[0031] The impurities in the bis(fluorosulfonyl)imide metal liquid salt include, by mass percentage:

[0032] Aminosulfonate ≤100ppm, fluorosulfonate ≤300ppm, fluorosulfonamide ≤10ppm.

[0033] The bisfluorosulfonyl imide metal liquid salt as described above, wherein the bisfluorosulfonyl imide metal liquid salt also includes chloride ion and fluoride ion impurities, the mass percentage of the chloride ion in the bisfluorosulfonyl imide metal liquid salt is not higher than 5ppm, and the mass percentage of the fluoride ion in the bisfluorosulfonyl imide metal liquid salt is not higher than 50ppm.

[0034] The preparation method of the bisfluorosulfonyl imide metal liquid salt of the present invention is combined with the devolatilization treatment and the resin deacidification treatment, and can first use the high temperature negative pressure method to efficiently and quickly remove most of the acidic substances in the molten reaction liquid, so that the EP1 acidity of the reaction liquid in terms of HF is ≤0.5ppm, and then use the resin to quickly remove the remaining acidic substances, which can not only prepare a bisfluorosulfonyl imide metal liquid salt with high purity, but also shorten the post-processing time, and enable a batch of resins to be used multiple times, reducing costs, and can also avoid the cumbersome operations caused by frequent replacement of resins. In addition, after the bisfluorosulfonyl imide metal compound is dissolved, it is then deacidified by the resin to obtain the liquid salt, which not only reduces the powderization process required after cooling and solidification, thereby simplifying the production process, shortening the production time, and reducing costs; and the liquid salt can be directly applied to the electrolyte, reducing the process of dissolving the electrolyte salt when preparing the electrolyte.

[0035] The bisfluorosulfonyl imide metal liquid salt provided by the invention has high purity, which is conducive to the wide application of the bisfluorosulfonyl imide metal liquid salt in the battery field. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The present invention provides a method for preparing a bis(fluorosulfonyl)imide metal liquid salt, comprising the following steps:

[0038] A bisfluorosulfonyl imide and a fluorinated metal compound are reacted to obtain a molten reaction liquid, the reaction liquid is subjected to a devolatilization treatment until the EP1 acidity calculated as HF is ≤ 0.5 ppm to obtain a bisfluorosulfonyl imide metal compound, which is then dissolved in a solvent, and then subjected to a resin deacidification treatment to obtain a bisfluorosulfonyl imide metal liquid salt;

[0039] The heating temperature of the devolatilization treatment is lower than 140°C.

[0040] Specifically, after mixing bisfluorosulfonyl imide with a fluorinated metal compound, a reaction occurs at a certain temperature. After the reaction is completed, a reaction liquid including a bisfluorosulfonyl imide metal compound is obtained, and the reaction liquid including the bisfluorosulfonyl imide metal compound is in a molten state. Then, by adjusting parameters such as temperature (lower than 140° C.) and vacuum degree, the reaction liquid is subjected to a devolatilization treatment to quickly remove most of the low-boiling impurities (such as HF and bisfluorosulfonyl imide). The EP1 acidity of the reaction liquid in terms of HF is monitored until it is no more than 0.5 ppm to obtain a bisfluorosulfonyl imide metal compound. Subsequently, the bisfluorosulfonyl imide metal compound is dissolved in a solvent to obtain a bisfluorosulfonyl imide metal compound solution, and the bisfluorosulfonyl imide metal compound solution is subjected to a resin deacidification treatment to obtain a bisfluorosulfonyl imide metal liquid salt.

[0041] The metal fluoride compound of the present invention can be selected according to the target bisfluorosulfonyl imide metal compound. For example, lithium fluoride can be selected to prepare lithium bisfluorosulfonyl imide, and sodium fluoride can be selected to prepare sodium bisfluorosulfonyl imide.

[0042] The main purpose of the reaction of bis(fluorosulfonyl)imide and metal fluoride compound is to generate bis(fluorosulfonyl)imide metal compound. As for the reaction temperature and time, they can be determined according to the selection and proportion of the raw materials, as long as the reaction liquid obtained by the final reaction is in a molten state.

[0043] Before the devolatilization treatment begins, the present invention does not perform any temperature treatment on the reaction liquid, so that the reaction temperature is maintained, so that the bis(fluorosulfonyl)imide metal compound reaction liquid can be directly devolatilized in a molten state.

[0044] For the devolatilization treatment of the reaction solution, as long as the impurities in the reaction solution (such as unreacted bisfluorosulfonyl imide and byproduct HF) can be removed as much as possible in a short time and the EP1 acidity of the bisfluorosulfonyl imide metal compound after devolatilization is ≤0.5ppm in terms of HF, those skilled in the art can determine the relevant parameters of the devolatilization treatment (such as the vacuum degree). The temperature of the devolatilization treatment of the present invention is lower than 140°C. If the heating temperature of the devolatilization treatment is too high, the bisfluorosulfonyl imide metal compound will undergo a condensation reaction to produce byproducts such as fluorosulfonic acid metal compounds, resulting in an abnormal increase in fluorosulfonate.

[0045] The present invention does not limit the specific selection of the solvent, and the solvent can be selected according to actual needs.

[0046] The present invention does not limit the mass ratio of the bis(fluorosulfonyl)imide metal compound to the solvent, as long as the bis(fluorosulfonyl)imide metal compound can be dissolved.

[0047] The present invention does not limit the dissolution temperature of the bis(fluorosulfonyl)imide metal compound in the solvent, and the temperature can be selected according to actual needs.

[0048] The present invention does not limit the specific selection of resin, and the resin can be selected according to actual needs.

[0049] The resin deacidification treatment of the present invention can remove the acidic substances in the bisfluorosulfonyl imide metal compound to obtain a high-purity bisfluorosulfonyl imide metal liquid salt.

[0050] In the preparation method of the present invention, no water is generated, which can not only avoid the waste of energy and time required for subsequent water removal, but also carry out devolatilization treatment on the reaction solution maintaining the reaction temperature, and can efficiently and quickly remove impurities to the reaction solution EP1 acidity of HF ≤ 0.5ppm, and by maintaining the reaction temperature and immediately carrying out devolatilization treatment and controlling the devolatilization concentration to be EP1 acidity of HF ≤ 0.5ppm as the end point, it can not only shorten the time used for devolatilization, avoid spending a lot of time to remove the remaining small amount of acid, and because the acidity is controlled within a certain range, the effect of resin deacidification can be improved, and the high purity of bisfluorosulfonyl imide metal liquid salt can be achieved. In addition, since the acid content in the bisfluorosulfonyl imide metal compound after the devolatilization treatment is low, the effective resin occupancy of the resin deacidification can be reduced, the cost can be reduced, and the resin installed once can be used multiple times, avoiding the cumbersome operation caused by frequent replacement of the resin. In addition, the bisfluorosulfonyl imide metal compound obtained after the devolatilization treatment is dissolved and then subjected to resin deacidification treatment, which can not only improve the resin deacidification effect, but also reduce the powderization process required after cooling and solidification, thereby simplifying the production process, shortening the production time, and reducing costs.

[0051] The present invention does not limit the source and purity of the bisfluorosulfonyl imide, which can be purchased directly or prepared.

[0052] The present invention does not limit the source and purity of the metal fluoride compound, and it can be selected according to actual needs.

[0053] Generally, through the post-treatment process of the present invention, the bisfluorosulfonyl imide metal compound has a higher purity and a lower impurity content. Specifically, according to the mass percentage, the impurities in the bisfluorosulfonyl imide metal compound include: aminosulfonate ≤350ppm, fluorosulfonate ≤1000ppm, fluorosulfonamide ≤50ppm, and chloride ion ≤20ppm.

[0054] The mass percentage of impurities in the bisfluorosulfonyl imide and the bisfluorosulfonyl imide metal compound of the present invention can be obtained by ion chromatography and nuclear magnetic fluorine spectrum testing.

[0055] The EP1 acidity of the bisfluorosulfonyl imide metal compound of the present invention can be obtained by potentiometric titration with triethylamine.

[0056] In a specific embodiment, the vacuum degree of the devolatilization treatment is 1-0.1 kPa, for example, the vacuum degree is 1 kPa, 0.9 kPa, 0.8 kPa, 0.7 kPa, 0.6 kPa, 0.5 kPa, 0.4 kPa, 0.3 kPa, 0.2 kPa or 0.1 kPa, the heating temperature is not less than 60°C, for example, the heating temperature is 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C or 139°C, etc., and the treatment time is 10-20 h, for example, the treatment time is 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h or 20 h. When the vacuum degree, heating temperature and treatment time of the devolatilization treatment are within the above ranges, the devolatilization treatment can remove impurities in the reaction solution more quickly, and the separation effect of impurities and the bisfluorosulfonyl imide metal compound is good, avoiding the simultaneous removal of the bisfluorosulfonyl imide metal compound, thereby achieving the preparation of high-purity bisfluorosulfonyl imide metal compounds and high production efficiency, and because the temperature and vacuum degree of the devolatilization treatment are appropriately selected, it has the advantage of low equipment requirements. Preferably, the heating temperature is 100-135°C, for example, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C or 135°C, etc.

[0057] In a specific embodiment, the molten reaction liquid is prepared by bisfluorosulfonyl imide and a fluorinated metal compound under solvent-free conditions. Specifically, no other reaction solvent is added to the reaction of the bisfluorosulfonyl imide and the fluorinated metal compound of the present invention. The bisfluorosulfonyl imide is used as a reaction raw material and also provides a solvent environment for the reaction, so that the bisfluorosulfonyl imide and the metal compound react fully to generate a bisfluorosulfonyl imide metal compound. The bisfluorosulfonyl imide and the fluorinated metal compound react under solvent-free conditions, which can reduce the impurities introduced when the raw materials are added, and can reduce the impact of impurities caused by residual raw materials, thereby further improving the purity of the bisfluorosulfonyl imide metal liquid salt, while reducing the types of raw materials used and reducing costs.

[0058] In a specific embodiment, the reaction temperature of the bisfluorosulfonyl imide and the fluorinated metal compound is 130-140°C, and the reaction time is 4-8h, for example, the reaction temperature is 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C or 140°C, and the reaction time is 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h or 8h, etc. When the reaction temperature and the reaction time are respectively within the above ranges, the bisfluorosulfonyl imide and the fluorinated metal compound can fully react, and are conducive to the subsequent devolatilization treatment and resin deacidification, so that impurities are quickly removed from the reaction solution, thereby realizing the preparation of high-purity bisfluorosulfonyl imide metal liquid salt.

[0059] In a specific embodiment, the molar ratio of bisfluorosulfonyl imide to the metal fluoride compound is 1:(0.95-1.05), for example, the molar ratio is 1:0.95, 1:0.96, 1:0.97, 1:0.98, 1:0.99, 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04 or 1:1.05. When the molar ratio of bisfluorosulfonyl imide to the metal fluoride compound is within the above range, the bisfluorosulfonyl imide and the metal fluoride compound can react to form a bisfluorosulfonyl imide metal compound, thereby reducing the residual unreacted bisfluorosulfonyl imide or metal fluoride compound in the system after the reaction, which is beneficial to the subsequent devolatilization treatment and resin deacidification treatment, and avoids the input of too much metal fluoride compound, resulting in the first filtration treatment being unable to completely remove the metal fluoride compound, and avoids the residual metal fluoride compound resulting in an excessively high fluoride ion content, thereby helping to improve the purity of the bisfluorosulfonyl imide metal liquid salt and reduce the fluoride ion content, while avoiding the waste of raw materials and saving costs.

[0060] In a specific embodiment, the dissolution of the bisfluorosulfonyl imide metal compound in the solvent is carried out while maintaining a molten state. When the bisfluorosulfonyl imide metal compound is dissolved in the solvent while maintaining a molten state, the powderization process required after the bisfluorosulfonyl imide metal compound is cooled and solidified can be reduced, thereby simplifying the production process, shortening the production time, and reducing costs.

[0061] In a specific embodiment, the temperature of the obtained bisfluorosulfonyl imide metal compound is maintained, and it is mixed into a solvent so that the bisfluorosulfonyl imide metal compound is kept in a molten state for the above-mentioned dissolution in the solvent. Specifically, the temperature of the bisfluorosulfonyl imide metal compound obtained by the devolatilization treatment is maintained so that the bisfluorosulfonyl imide metal compound is in a molten state, and then it is mixed into a solvent, and the molten state is maintained to dissolve in the solvent to obtain a bisfluorosulfonyl imide metal compound solution. In this way, the bisfluorosulfonyl imide metal compound is kept in a molten state, which is conducive to rapid dissolution in the solvent, avoiding the bisfluorosulfonyl imide metal compound from being cooled and agglomerated, and being difficult to dissolve in the solvent, thereby being able to reduce the powderization process, shorten the production time, and reduce the time cost.

[0062] In a specific embodiment, the solvent is an electrolyte solvent, and the electrolyte solvent includes at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and ethylene carbonate; the mass ratio of the bisfluorosulfonyl imide metal compound to the electrolyte solvent is (59:141)-(61:139). When the electrolyte solvent is selected from the above solvent, the bisfluorosulfonyl imide metal compound can be dissolved in the electrolyte solvent to form a bisfluorosulfonyl imide metal compound solution, and the impurities in the bisfluorosulfonyl imide metal compound do not react with the electrolyte solvent, thereby avoiding the appearance of by-products. When the mass ratio of the bisfluorosulfonyl imide metal compound to the electrolyte solvent is within the above range, the impurity content in the bisfluorosulfonyl imide metal compound solution is within a suitable range, which is conducive to the subsequent resin deacidification treatment, and the resin has better adsorption of impurities, thereby improving the deacidification effect of the resin deacidification treatment, and further improving the purity of the bisfluorosulfonyl imide metal liquid salt.

[0063] In a specific embodiment, the resin includes one of poly (4-vinylpyridine) resin, poly N, N dimethyl parastyrene resin, and poly N, N diethyl parastyrene resin; A / B is 1-5%, wherein A is the mass of the resin and B is the mass of the bisfluorosulfonyl imide metal compound. When the resin is selected from the above resin, the resin can absorb impurities in the bisfluorosulfonyl imide metal compound solution faster and more efficiently, improve the deacidification effect of the resin deacidification treatment, and improve the purity of the bisfluorosulfonyl imide metal liquid salt. When the mass of the resin and the mass of the bisfluorosulfonyl imide metal compound are within the above range, it is beneficial for the resin to quickly adsorb impurities in the bisfluorosulfonyl imide metal compound, and can avoid the problem of poor deacidification effect caused by excessive adsorption of impurities by the resin, thereby improving the effect of the resin deacidification treatment, improving the purity of the bisfluorosulfonyl imide metal liquid salt, and reducing production costs.

[0064] In a specific embodiment, the turbidity of the reaction solution is ≤100; or, the EP1 acidity of the reaction solution in terms of HF is ≤100ppm. When the molar ratio of bisfluorosulfonyl imide to the metal fluoride compound is less than 1, the reaction solution includes unreacted metal fluoride compound, the metal fluoride compound is solid, and the reaction solution is tested for turbidity; when the molar ratio of bisfluorosulfonyl imide to the metal fluoride compound is greater than 1, the reaction solution includes unreacted bisfluorosulfonyl imide, and the reaction solution is tested for acidity. When the turbidity or acidity of the reaction solution is within the above range, the bisfluorosulfonyl imide reacts completely with the metal fluoride compound, and subsequent devolatilization treatment can be performed, and the turbidity or acidity of the reaction solution is low, which reduces the difficulty of subsequent devolatilization treatment and resin deacidification treatment, and greatly improves the purity of the bisfluorosulfonyl imide metal liquid salt.

[0065] In a specific embodiment, the bisfluorosulfonyl imide includes, by mass percentage, bisfluorosulfonyl imide 99.93-100%, aminosulfonate ≤200ppm, fluorosulfonate ≤300ppm, fluorosulfonamide ≤100ppm, chloride ion ≤50ppm, fluoride ion ≤50ppm; and / or, the metal fluoride compound includes one of lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride, cesium fluoride, and francium fluoride; and / or, the metal fluoride compound includes, by mass percentage, metal fluoride compound 99.84-100%, metal carbonate compound ≤1000ppm, and water ≤600ppm. When bisfluorosulfonyl imide with the above purity is selected for reaction with a metal fluoride compound, the bisfluorosulfonyl imide and the metal fluoride compound have few impurities, and the introduction of excessive impurities is avoided, which helps to achieve high purity of the bisfluorosulfonyl imide metal liquid salt, and can reduce the time of devolatilization treatment, improve production efficiency and save costs. At the same time, since chloride ions mainly come from bisfluorosulfonyl imide, reducing the chloride ion content in bisfluorosulfonyl imide helps to achieve the preparation of bisfluorosulfonyl imide liquid salt with low chloride ion content.

[0066] The present invention can prepare the corresponding bisfluorosulfonyl imide metal liquid salt by selecting a specific metal fluoride compound, for example, bisfluorosulfonyl imide lithium, bisfluorosulfonyl imide sodium, bisfluorosulfonyl imide potassium, bisfluorosulfonyl imide rubidium, bisfluorosulfonyl imide cesium, and bisfluorosulfonyl imide francium can be prepared.

[0067] In a specific embodiment, before the resin is deacidified, the bisfluorosulfonyl imide metal compound solution is subjected to a first filtration treatment; and / or, after the resin is deacidified, the deacidified solution system is subjected to a second filtration treatment. Before the resin is deacidified, the bisfluorosulfonyl imide metal compound solution is subjected to a first filtration treatment, which can remove the insoluble substances in the bisfluorosulfonyl imide metal compound solution, avoid the insoluble substances from damaging the resin, causing resin blockage or poor deacidification effect, thereby improving the purity of the bisfluorosulfonyl imide metal liquid salt. After the resin is deacidified, a second filtration treatment is performed to remove the insoluble substances that are not filtered out by the first filtration treatment and the insoluble substances that may be generated after the resin is deacidified, thereby improving the purity of the bisfluorosulfonyl imide metal liquid salt.

[0068] The present invention does not limit the pore size of the filter membrane used in the first filtration treatment and the second filtration treatment, and can be selected according to actual needs. For example, compared with the first filtration treatment, the second filtration treatment uses a filter membrane with a smaller pore size, which can better remove insoluble substances in the system and improve the purity of the bis(fluorosulfonyl)imide metal liquid salt to a greater extent.

[0069] The present invention also provides a bisfluorosulfonyl imide metal liquid salt, which is prepared by the above-mentioned preparation method, and the impurities in the bisfluorosulfonyl imide metal liquid salt include: aminosulfonate ≤100ppm, fluorosulfonate ≤300ppm, fluorosulfonamide ≤10ppm, etc. The bisfluorosulfonyl imide metal liquid salt provided by the present invention has high purity, which is conducive to the wide application of the bisfluorosulfonyl imide metal liquid salt in the field of batteries.

[0070] In a specific embodiment, the bisfluorosulfonyl imide metal liquid salt also includes chloride ion and fluoride ion impurities, the mass percentage of chloride ion in the bisfluorosulfonyl imide metal liquid salt is not higher than 5ppm, and the mass percentage of fluoride ion in the bisfluorosulfonyl imide metal liquid salt is not higher than 50ppm. Exemplarily, during the preparation process, the molar ratio of bisfluorosulfonyl imide and the fluoride metal compound and the purity of bisfluorosulfonyl imide and the fluoride metal compound can be controlled to achieve the preparation of the bisfluorosulfonyl imide metal liquid salt with no more than 5ppm of fluoride ion and no more than 5ppm of chloride ion.

[0071] Hereinafter, the present invention will be further described in detail through specific examples.

[0072] Example 1

[0073] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0074] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0075] Among them, the impurities in bis(fluorosulfonyl)imide (Guangdong Wengjiang Chemical Reagent) include, by mass percentage: 180 ppm aminosulfonate, 150 ppm fluorosulfonate, 44 ppm fluorosulfonamide, 37 ppm chloride ion, and 25 ppm fluoride ion; the impurities in lithium fluoride include, by mass percentage: 99.84% lithium fluoride, 1000 ppm lithium carbonate, and 600 ppm water.

[0076] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent for dissolution, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 80 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 8 ppm of fluorosulfonamide, 3 ppm of chloride ion, and 35 ppm of fluoride ion.

[0077] Wherein, the mass ratio of lithium bis(fluorosulfonyl)imide to electrolyte solvent is 60:140;

[0078] A / B is 2%, A is the mass of the resin, and B is the mass of lithium bis(fluorosulfonyl)imide.

[0079] Example 2

[0080] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0081] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 67 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.8 kPa, a temperature of 120° C., and a time of 15 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0082] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 200 ppm of aminosulfonate, 180 ppm of fluorosulfonate, 50 ppm of fluorosulfonamide, 460 ppm of chloride ion, and 390 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.88% of lithium fluoride, 800 ppm of lithium carbonate, and 400 ppm of water.

[0083] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into diethyl carbonate solvent for dissolution, and keep the temperature of the dissolving system at 20° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PED resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 100 ppm aminosulfonate, 250 ppm fluorosulfonate, 6 ppm fluorosulfonamide, 4 ppm chloride ion, and 45 ppm fluoride ion.

[0084] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0085] Example 3

[0086] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0087] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1.05 at a reaction temperature of 140°C until the turbidity of the reaction solution is 100 to obtain a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 1 kPa, a temperature of 130°C, and a time of 20 hours to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide in terms of HF is 0.1 ppm;

[0088] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 150 ppm of aminosulfonate, 280 ppm of fluorosulfonate, 48 ppm of fluorosulfonamide, 320 ppm of chloride ion, and 480 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.89% of lithium fluoride, 600 ppm of lithium carbonate, and 500 ppm of water.

[0089] 2. Add lithium bis(fluorosulfonyl)imide at 130° C. to dimethyl carbonate solvent, and keep the temperature of the dissolving system at 30° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 55 ppm of aminosulfonate, 240 ppm of fluorosulfonate, 10 ppm of fluorosulfonamide, 4 ppm of chloride ion, and 32 ppm of fluoride ion.

[0090] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 59:141; and A / B is 1%.

[0091] Example 4

[0092] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0093] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1.05 at a reaction temperature of 140°C until the turbidity of the reaction solution is 89 to obtain a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.1 kPa, a temperature of 120°C, and a time of 10 hours to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide in terms of HF is 0.1 ppm;

[0094] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 88 ppm of aminosulfonate, 56 ppm of fluorosulfonate, 22 ppm of fluorosulfonamide, 5 ppm of chloride ion, and 12 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.928% of lithium fluoride, 400 ppm of lithium carbonate, and 320 ppm of water.

[0095] 2. Add lithium bis(fluorosulfonyl)imide at 130° C. to ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 40° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEB resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 45 ppm of aminosulfonate, 124 ppm of fluorosulfonate, 7 ppm of fluorosulfonamide, 1 ppm of chloride ion, and 22 ppm of fluoride ion.

[0096] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 5%.

[0097] Example 5

[0098] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0099] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 92 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0100] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0101] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 65 ppm of aminosulfonate, 124 ppm of fluorosulfonate, 5 ppm of fluorosulfonamide, 3 ppm of chloride ion, and 17 ppm of fluoride ion.

[0102] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0103] Example 6

[0104] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0105] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution in terms of HF is 78 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the acidity of the lithium bis(fluorosulfonyl)imide in terms of HF is 0.5 ppm;

[0106] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.89% of lithium fluoride, 600 ppm of lithium carbonate, and 500 ppm of water.

[0107] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 88 ppm of aminosulfonate, 145 ppm of fluorosulfonate, 7 ppm of fluorosulfonamide, 3 ppm of chloride ion, and 45 ppm of fluoride ion.

[0108] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0109] Example 7

[0110] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0111] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0112] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0113] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 55 ppm of aminosulfonate, 188 ppm of fluorosulfonate, 4 ppm of fluorosulfonamide, 2.5 ppm of chloride ion, and 37 ppm of fluoride ion.

[0114] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 61:139; and A / B is 2%.

[0115] Example 8

[0116] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0117] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0118] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0119] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 47 ppm of aminosulfonate, 120 ppm of fluorosulfonate, 4 ppm of fluorosulfonamide, 3.7 ppm of chloride ion, and 37 ppm of fluoride ion.

[0120] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 4%.

[0121] Example 9

[0122] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0123] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1.05 at a reaction temperature of 140°C until the turbidity of the reaction solution is 89 to obtain a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.1 kPa, a temperature of 120°C, and a time of 10 hours to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide in terms of HF is 0.1 ppm;

[0124] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 88 ppm of aminosulfonate, 56 ppm of fluorosulfonate, 22 ppm of fluorosulfonamide, 5 ppm of chloride ion, and 12 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.928% of lithium fluoride, 400 ppm of lithium carbonate, and 320 ppm of water.

[0125] 2. Add lithium bis(fluorosulfonyl)imide at 130° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 40° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEB resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 67 ppm of aminosulfonate, 141 ppm of fluorosulfonate, 5 ppm of fluorosulfonamide, 3 ppm of chloride ion, and 37 ppm of fluoride ion.

[0126] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 61:139; and A / B is 5%.

[0127] Example 10

[0128] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0129] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1.05 at a reaction temperature of 140°C until the turbidity of the reaction solution is 89 to obtain a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.1 kPa, a temperature of 120°C, and a time of 10 hours to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide in terms of HF is 0.1 ppm;

[0130] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 88 ppm of aminosulfonate, 56 ppm of fluorosulfonate, 22 ppm of fluorosulfonamide, 5 ppm of chloride ion, and 12 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.928% of lithium fluoride, 400 ppm of lithium carbonate, and 320 ppm of water.

[0131] 2. Add lithium bis(fluorosulfonyl)imide at 130° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 40° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEB resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 67 ppm of aminosulfonate, 130 ppm of fluorosulfonate, 7 ppm of fluorosulfonamide, 2.4 ppm of chloride ion, and 18 ppm of fluoride ion.

[0132] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 3%.

[0133] Embodiment 11

[0134] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0135] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1.1 at a reaction temperature of 130°C until the turbidity of the reaction solution is 150 to obtain a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120°C, and a time of 12 hours to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide in terms of HF is 0.08 ppm;

[0136] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0137] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 24 ppm of aminosulfonate, 147 ppm of fluorosulfonate, 8 ppm of fluorosulfonamide, 3 ppm of chloride ion, and 89 ppm of fluoride ion.

[0138] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0139] Example 12

[0140] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0141] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0142] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0143] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 97 ppm of aminosulfonate, 280 ppm of fluorosulfonate, 8 ppm of fluorosulfonamide, 4 ppm of chloride ion, and 46 ppm of fluoride ion.

[0144] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 50:150; and A / B is 2%.

[0145] Example 13

[0146] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0147] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0148] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0149] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 88 ppm of aminosulfonate, 255 ppm of fluorosulfonate, 9 ppm of fluorosulfonamide, 4.5 ppm of chloride ion, and 47 ppm of fluoride ion.

[0150] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 0.5%.

[0151] Embodiment 14

[0152] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0153] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1.05 at a reaction temperature of 140°C until the turbidity of the reaction solution is 89 to obtain a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.1 kPa, a temperature of 120°C, and a time of 10 hours to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide in terms of HF is 0.1 ppm;

[0154] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 88 ppm of aminosulfonate, 56 ppm of fluorosulfonate, 22 ppm of fluorosulfonamide, 5 ppm of chloride ion, and 12 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.928% of lithium fluoride, 400 ppm of lithium carbonate, and 320 ppm of water.

[0155] 2. Add lithium bis(fluorosulfonyl)imide at 130° C. to ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 40° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEB resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 91 ppm of aminosulfonate, 289 ppm of fluorosulfonate, 10 ppm of fluorosulfonamide, 3 ppm of chloride ion, and 57 ppm of fluoride ion.

[0156] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 70:130; and A / B is 5%.

[0157] Embodiment 15

[0158] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0159] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1.05 at a reaction temperature of 140°C until the turbidity of the reaction solution is 89 to obtain a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.1 kPa, a temperature of 120°C, and a time of 10 hours to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide in terms of HF is 0.1 ppm;

[0160] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 88 ppm of aminosulfonate, 56 ppm of fluorosulfonate, 22 ppm of fluorosulfonamide, 5 ppm of chloride ion, and 12 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.928% of lithium fluoride, 400 ppm of lithium carbonate, and 320 ppm of water.

[0161] 2. Add lithium bis(fluorosulfonyl)imide at 130° C. to ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 40° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEB resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 88 ppm of aminosulfonate, 213 ppm of fluorosulfonate, 7 ppm of fluorosulfonamide, 2.5 ppm of chloride ion, and 44 ppm of fluoride ion.

[0162] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 0.5%.

[0163] Example 16

[0164] The preparation method of lithium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0165] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 74 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.3 ppm;

[0166] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 220 ppm of aminosulfonate, 180 ppm of fluorosulfonate, 150 ppm of fluorosulfonamide, 70 ppm of chloride ion, and 70 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0167] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 100 ppm of aminosulfonate, 278 ppm of fluorosulfonate, 8 ppm of fluorosulfonamide, 6 ppm of chloride ion, and 45 ppm of fluoride ion.

[0168] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0169] Embodiment 17

[0170] The preparation method of the lithium bis(fluorosulfonyl)imide liquid salt provided in this comparative example comprises the following steps:

[0171] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1.05 at a reaction temperature of 140°C until the turbidity of the reaction solution is 89 to obtain a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.1 kPa, a temperature of 120°C, and a time of 10 hours to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide in terms of HF is 0.1 ppm;

[0172] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 88 ppm of aminosulfonate, 56 ppm of fluorosulfonate, 22 ppm of fluorosulfonamide, 5 ppm of chloride ion, and 12 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.8% of lithium fluoride, 1200 ppm of lithium carbonate, and 800 ppm of water.

[0173] 2. Add lithium bis(fluorosulfonyl)imide at 130° C. to ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 40° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEB resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 97 ppm of aminosulfonate, 214 ppm of fluorosulfonate, 10 ppm of fluorosulfonamide, 1.4 ppm of chloride ion, and 18 ppm of fluoride ion.

[0174] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 5%.

[0175] Embodiment 18

[0176] The preparation method of sodium bis(fluorosulfonyl)imide liquid salt provided in this embodiment comprises the following steps:

[0177] 1. Bis(fluorosulfonyl)imide and sodium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 80 ppm to obtain a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h to obtain sodium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the sodium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0178] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in sodium fluoride include, by mass percentage, 99.9% of sodium fluoride, 600 ppm of sodium carbonate, and 400 ppm of water.

[0179] 2. Sodium bis(fluorosulfonyl)imide maintained at 120° C. is added to ethyl methyl carbonate solvent, and the temperature of the dissolving system is maintained at 10° C. during the dissolution process to obtain a sodium bis(fluorosulfonyl)imide solution, and then the sodium bis(fluorosulfonyl)imide solution is subjected to a first filtration treatment, and then the sodium bis(fluorosulfonyl)imide solution is subjected to a resin deacidification treatment using a PEP resin, and finally a second filtration treatment is performed to obtain a sodium bis(fluorosulfonyl)imide liquid salt; the impurities in the sodium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 60 ppm of aminosulfonate, 122 ppm of fluorosulfonate, 7 ppm of fluorosulfonamide, 3 ppm of chloride ion, and 33 ppm of fluoride ion.

[0180] The mass ratio of sodium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0181] Embodiment 19

[0182] The preparation method of bis(fluorosulfonyl)imide potassium liquid salt provided in this embodiment comprises the following steps:

[0183] 1. Bis(fluorosulfonyl)imide and potassium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution in terms of HF is 80 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h, thereby obtaining potassium bis(fluorosulfonyl)imide;

[0184] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in bisfluorosulfonyl imide include, by mass percentage, 99.9% of potassium fluoride, 600 ppm of potassium carbonate, and 400 ppm of water.

[0185] 2. Potassium bis(fluorosulfonyl)imide maintained at 120° C. is added to ethyl methyl carbonate solvent, and the temperature of the dissolving system is maintained at 10° C. during the dissolution process to obtain a potassium bis(fluorosulfonyl)imide solution, and then the potassium bis(fluorosulfonyl)imide solution is subjected to a first filtration treatment, and then the potassium bis(fluorosulfonyl)imide solution is subjected to a resin deacidification treatment using a PEP resin, and finally a second filtration treatment is performed to obtain a potassium bis(fluorosulfonyl)imide liquid salt; the impurities in the potassium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 88 ppm of aminosulfonate, 247 ppm of fluorosulfonate, 6 ppm of fluorosulfonamide, 4 ppm of chloride ion, and 34 ppm of fluoride ion.

[0186] The mass ratio of potassium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0187] Embodiment 20

[0188] The preparation method of bis(fluorosulfonyl)imide potassium liquid salt provided in this embodiment comprises the following steps:

[0189] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 135° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0190] Among them, the impurities in bis(fluorosulfonyl)imide (Guangdong Wengjiang Chemical Reagent) include, by mass percentage: 180 ppm aminosulfonate, 150 ppm fluorosulfonate, 44 ppm fluorosulfonamide, 37 ppm chloride ion, and 25 ppm fluoride ion; the impurities in lithium fluoride include, by mass percentage: 99.84% lithium fluoride, 1000 ppm lithium carbonate, and 600 ppm water.

[0191] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent for dissolution, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 78 ppm of aminosulfonate, 161 ppm of fluorosulfonate, 7 ppm of fluorosulfonamide, 4 ppm of chloride ion, and 44 ppm of fluoride ion.

[0192] Wherein, the mass ratio of lithium bis(fluorosulfonyl)imide to electrolyte solvent is 60:140;

[0193] A / B is 2%, A is the mass of the resin, and B is the mass of lithium bis(fluorosulfonyl)imide.

[0194] Embodiment 21

[0195] The preparation method of bis(fluorosulfonyl)imide potassium liquid salt provided in this embodiment comprises the following steps:

[0196] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm to obtain a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 100° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0197] Among them, the impurities in bis(fluorosulfonyl)imide (Guangdong Wengjiang Chemical Reagent) include, by mass percentage: 180 ppm aminosulfonate, 150 ppm fluorosulfonate, 44 ppm fluorosulfonamide, 37 ppm chloride ion, and 25 ppm fluoride ion; the impurities in lithium fluoride include, by mass percentage: 99.84% lithium fluoride, 1000 ppm lithium carbonate, and 600 ppm water.

[0198] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent for dissolution, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 89 ppm of aminosulfonate, 198 ppm of fluorosulfonate, 7 ppm of fluorosulfonamide, 4 ppm of chloride ion, and 38 ppm of fluoride ion.

[0199] Wherein, the mass ratio of lithium bis(fluorosulfonyl)imide to electrolyte solvent is 60:140;

[0200] A / B is 2%, A is the mass of the resin, and B is the mass of lithium bis(fluorosulfonyl)imide.

[0201] Embodiment 22

[0202] The preparation method of bis(fluorosulfonyl)imide potassium liquid salt provided in this embodiment comprises the following steps:

[0203] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 80° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0204] Among them, the impurities in bis(fluorosulfonyl)imide (Guangdong Wengjiang Chemical Reagent) include, by mass percentage: 180 ppm aminosulfonate, 150 ppm fluorosulfonate, 44 ppm fluorosulfonamide, 37 ppm chloride ion, and 25 ppm fluoride ion; the impurities in lithium fluoride include, by mass percentage: 99.84% lithium fluoride, 1000 ppm lithium carbonate, and 600 ppm water.

[0205] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent for dissolution, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 88 ppm of aminosulfonate, 243 ppm of fluorosulfonate, 8 ppm of fluorosulfonamide, 3 ppm of chloride ion, and 41 ppm of fluoride ion.

[0206] Wherein, the mass ratio of lithium bis(fluorosulfonyl)imide to electrolyte solvent is 60:140;

[0207] A / B is 2%, A is the mass of the resin, and B is the mass of lithium bis(fluorosulfonyl)imide.

[0208] Embodiment 23

[0209] The preparation method of bis(fluorosulfonyl)imide potassium liquid salt provided in this embodiment comprises the following steps:

[0210] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 60° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0211] Among them, the impurities in bis(fluorosulfonyl)imide (Guangdong Wengjiang Chemical Reagent) include, by mass percentage: 180 ppm aminosulfonate, 150 ppm fluorosulfonate, 44 ppm fluorosulfonamide, 37 ppm chloride ion, and 25 ppm fluoride ion; the impurities in lithium fluoride include, by mass percentage: 99.84% lithium fluoride, 1000 ppm lithium carbonate, and 600 ppm water.

[0212] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent for dissolution, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 90 ppm of aminosulfonate, 294 ppm of fluorosulfonate, 8 ppm of fluorosulfonamide, 4 ppm of chloride ion, and 49 ppm of fluoride ion.

[0213] Wherein, the mass ratio of lithium bis(fluorosulfonyl)imide to electrolyte solvent is 60:140;

[0214] A / B is 2%, A is the mass of the resin, and B is the mass of lithium bis(fluorosulfonyl)imide.

[0215] Comparative Example 1

[0216] The preparation method of the lithium bis(fluorosulfonyl)imide liquid salt provided in this comparative example comprises the following steps:

[0217] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution in terms of HF is 92 ppm, to obtain a molten reaction solution;

[0218] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0219] 2. The reaction solution is subjected to a first filtration treatment, and then the reaction solution is subjected to a resin deacidification treatment using a PEP resin, and finally a second filtration treatment is performed to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 1450 ppm of aminosulfonate, 3657 ppm of fluorosulfonate, 77 ppm of fluorosulfonamide, 145 ppm of chloride ion, and 889 ppm of fluoride ion.

[0220] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0221] During the resin deacidification process, the PEP resin needs to be replaced after one use due to the high impurity content in the reaction solution.

[0222] Comparative Example 2

[0223] The preparation method of the lithium bis(fluorosulfonyl)imide liquid salt provided in this comparative example comprises the following steps:

[0224] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:1 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 92 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.5 ppm;

[0225] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0226] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then filter the lithium bis(fluorosulfonyl)imide solution twice to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 148 ppm of aminosulfonate, 347 ppm of fluorosulfonate, 5 ppm of fluorosulfonamide, 3 ppm of chloride ion, and 266 ppm of fluoride ion.

[0227] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140.

[0228] Comparative Example 3

[0229] The preparation method of lithium bis(fluorosulfonyl)imide provided in this comparative example comprises the following steps:

[0230] 1. Add sulfamic acid, chlorosulfonic acid and thionyl chloride into a reactor at a molar ratio of 1:1.3:2.3 under nitrogen protection, stir and disperse them evenly, heat to 120°C and react for 120 minutes. After the reaction, remove low-boiling point compounds by atmospheric distillation, then perform reduced pressure distillation, collect the fraction of 112-114°C / 2mm Hg, and condense to obtain HClSI.

[0231] 2. HClSI is introduced into a reactor, and HF gas is introduced at 90° C. to make a molar ratio of HF to HClSI of 2.25:1; react at 90° C. for 8 hours and then cool to room temperature; nitrogen is introduced into the reactor for 3 hours to remove the mixed gas of HCl and HF to obtain bisfluorosulfonyl imide; bisfluorosulfonyl imide and NaCl are mixed at a mass ratio of 100:3, react at 70° C. for 3 hours, and then nitrogen is introduced into the reactor for 0.5 hours to remove HCl gas; the obtained product is subjected to reduced pressure distillation at -0.05 MPa and 100° C. for 2 hours, and the fractions are collected to obtain the HFSI.

[0232] 3. Add HFSI to the reactor, slowly add LiF to the reactor in a closed state and under stirring conditions, so that the molar ratio of HFSI to LiF is 1.05:1; react at 145°C for 6 hours to obtain LiFSI; dissolve the crystallized LiFSI in solvent ethyl methyl carbonate (EMC) to obtain EMC solution of LiFSI. After ion chromatography and nuclear magnetic resonance fluorine spectrum testing, the impurities in lithium bis(fluorosulfonyl)imide include: aminosulfonate 4599ppm, fluorosulfonate 22110ppm, fluorosulfonamide 124ppm, chloride ion 518ppm, fluoride ion 247ppm.

[0233] Comparative Example 4

[0234] The preparation method of the lithium bis(fluorosulfonyl)imide liquid salt provided in this comparative example comprises the following steps:

[0235] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 200 ppm to obtain a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 12 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.6 ppm;

[0236] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0237] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 150 ppm of aminosulfonate, 581 ppm of fluorosulfonate, 8 ppm of fluorosulfonamide, 3.4 ppm of chloride ion, and 267 ppm of fluoride ion.

[0238] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0239] Comparative Example 5

[0240] The preparation method of the lithium bis(fluorosulfonyl)imide liquid salt provided in this comparative example comprises the following steps:

[0241] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 1.5 kPa, a temperature of 120° C., and a time of 10 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 34 ppm;

[0242] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0243] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 214 ppm of aminosulfonate, 547 ppm of fluorosulfonate, 5 ppm of fluorosulfonamide, 3.8 ppm of chloride ion, and 145 ppm of fluoride ion.

[0244] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0245] Comparative Example 6

[0246] The preparation method of the lithium bis(fluorosulfonyl)imide liquid salt provided in this comparative example comprises the following steps:

[0247] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.5 kPa, a temperature of 120° C., and a time of 8 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 8 ppm;

[0248] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0249] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 314 ppm of aminosulfonate, 648 ppm of fluorosulfonate, 11 ppm of fluorosulfonamide, 4 ppm of chloride ion, and 245 ppm of fluoride ion.

[0250] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0251] Comparative Example 7

[0252] The preparation method of the lithium bis(fluorosulfonyl)imide liquid salt provided in this comparative example comprises the following steps:

[0253] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.1 kPa, a temperature of 140° C., and a time of 10 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.2 ppm;

[0254] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0255] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate as a solvent, and keep the temperature of the solvent system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then perform a first filtration treatment on the lithium bis(fluorosulfonyl)imide solution, and then perform a resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution using a PEP resin, and finally perform a second filtration treatment to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 78 ppm aminosulfonate, 1891 ppm fluorosulfonate, 7 ppm fluorosulfonamide, 3.4 ppm chloride ion, and 36 ppm fluoride ion.

[0256] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0257] Comparative Example 8

[0258] The preparation method of the lithium bis(fluorosulfonyl)imide liquid salt provided in this comparative example comprises the following steps:

[0259] 1. Bis(fluorosulfonyl)imide and lithium fluoride are reacted in a molar ratio of 1:0.95 at a reaction temperature of 130° C. until the EP1 acidity of the reaction solution calculated as HF is 88 ppm, thereby obtaining a molten reaction solution; then the reaction solution is subjected to a devolatilization treatment at a vacuum degree of 0.1 kPa, a temperature of 145° C., and a time of 10 h to obtain lithium bis(fluorosulfonyl)imide, wherein the EP1 acidity of the lithium bis(fluorosulfonyl)imide calculated as HF is 0.2 ppm;

[0260] Among them, the impurities in bisfluorosulfonyl imide include, by mass percentage, 180 ppm of aminosulfonate, 150 ppm of fluorosulfonate, 44 ppm of fluorosulfonamide, 37 ppm of chloride ion, and 25 ppm of fluoride ion; the impurities in lithium fluoride include, by mass percentage, 99.84% of lithium fluoride, 1000 ppm of lithium carbonate, and 600 ppm of water.

[0261] 2. Add lithium bis(fluorosulfonyl)imide at 120° C. into ethyl methyl carbonate solvent, and keep the temperature of the dissolving system at 10° C. during the dissolution process to obtain a lithium bis(fluorosulfonyl)imide solution, and then use PEP resin to perform resin deacidification treatment on the lithium bis(fluorosulfonyl)imide solution to obtain a lithium bis(fluorosulfonyl)imide liquid salt; the impurities in the lithium bis(fluorosulfonyl)imide liquid salt include, by mass percentage, 78 ppm aminosulfonate, 1289 ppm fluorosulfonate, 6 ppm fluorosulfonamide, 4 ppm chloride ion, and 49 ppm fluoride ion.

[0262] The mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is 60:140; and A / B is 2%.

[0263] By comparing Examples 1-4 and Example 11, it can be seen that when the molar ratio of bis(fluorosulfonyl)imide to lithium fluoride is in the range of 1:(0.95-1.05), bis(fluorosulfonyl)imide and lithium fluoride can fully react, and the corresponding turbidity of the molten reaction liquid is ≤100, or the acidity is ≤100ppm, thereby reducing the content of fluoride ions in the bis(fluorosulfonyl)imide lithium liquid salt.

[0264] By comparing Examples 1, 7, and 12 and Examples 4, 9, and 14, it can be seen that when the mass ratio of lithium bis(fluorosulfonyl)imide to the electrolyte solvent is (59:141)-(61:139), the impurity content in the lithium bis(fluorosulfonyl)imide liquid salt can be controlled within a limited range.

[0265] By comparing Examples 1, 8, and 13 and Examples 4, 10, and 15, it can be seen that when the mass ratio of the resin to the bisfluorosulfonyl imide metal compound is in the range of 1-5%, the resin can fully absorb impurities in the bisfluorosulfonyl imide lithium liquid salt to achieve high purity of the bisfluorosulfonyl imide lithium liquid salt.

[0266] By comparing Examples 1, 6, 16, and 17, it can be seen that when the purity of bisfluorosulfonyl imide or lithium fluoride is higher, the impurity content in the prepared bisfluorosulfonyl imide lithium liquid salt is lower.

[0267] By comparing Examples 1, 20-23 and Comparative Examples 7 and 8, it can be seen that when the temperature of the devolatilization treatment is higher than 140°C, lithium bis(fluorosulfonyl)imide undergoes a condensation side reaction to generate lithium fluorosulfonate byproduct, resulting in an excessively high fluorosulfonate content in the lithium bis(fluorosulfonyl)imide liquid salt.

[0268] According to Example 19, the preparation method of the bisfluorosulfonyl imide metal liquid salt of the present invention can also be applied to the preparation of bisfluorosulfonyl imide potassium liquid salt, which is beneficial to the preparation of various bisfluorosulfonyl imide metal liquid salts.

[0269] By comparing Example 1 with Comparative Examples 1-3, it can be seen that the impurities such as aminosulfonate, fluorosulfonate, fluorosulfonamide, chloride ion and fluoride ion in the lithium bis(fluorosulfonyl)imide liquid salt can be effectively removed by devolatilization treatment and resin deacidification treatment.

[0270] By comparing Example 1 with Comparative Examples 4-6, it can be seen that if most of the acidic substances in the reaction solution are not removed during the devolatilization treatment, so that the acidity of the reaction solution is higher than 0.5ppm, the subsequent use of resin can also remove the acidic substances in the reaction solution, but it will lead to waste of resin, so that the resin needs to be frequently replaced, and the preparation cost and time cost of bis(fluorosulfonyl)imide lithium liquid salt are increased. Therefore, most of the acidic substances in the molten reaction solution are first quickly removed by devolatilization treatment, and then the remaining acidic substances are quickly removed by using resin, which can simplify the production process, shorten the production time, and reduce the production cost.

[0271] In summary, the method for preparing the bisfluorosulfonyl imide metal liquid salt of the present invention can prepare the bisfluorosulfonyl imide metal liquid salt with high purity by controlling the devolatilization treatment and the resin deacidification treatment, and takes into account the advantages of cost saving, simple process, convenient operation, etc.

[0272] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a bis(fluorosulfonyl)imide metal liquid salt, characterized in that: The following steps are involved: A bisfluorosulfonyl imide and a fluorinated metal compound are reacted to obtain a molten reaction liquid, the reaction liquid is subjected to a devolatilization treatment until the EP1 acidity calculated as HF is ≤0.5 ppm to obtain a bisfluorosulfonyl imide metal compound, which is then dissolved in a solvent and then subjected to a resin deacidification treatment to obtain a bisfluorosulfonyl imide metal liquid salt; Wherein, the heating temperature of the devolatilization treatment is lower than 140°C.

2. The method for preparing the bis(fluorosulfonyl)imide metal liquid salt according to claim 1, characterized in that: The vacuum degree of the devolatilization treatment is 1-0.1 kPa, the heating temperature is not less than 60° C., and the treatment time is 10-20 hours; Preferably, the heating temperature is 100-135°C.

3. The method for preparing a bis(fluorosulfonyl)imide metal liquid salt according to claim 1 or 2, characterized in that: The dissolution of the bisfluorosulfonyl imide metal compound in the solvent is carried out while maintaining the compound in a molten state.

4. The method for preparing the bis(fluorosulfonyl)imide metal liquid salt according to claim 3, characterized in that: The obtained bisfluorosulfonyl imide metal compound is mixed into a solvent while maintaining its temperature so that the bisfluorosulfonyl imide metal compound is kept in the molten state and is dissolved in the solvent.

5. The method for preparing the bis(fluorosulfonyl)imide metal liquid salt according to any one of claims 1, 2 or 4, characterized in that: The solvent is an electrolyte solvent, and the electrolyte solvent includes at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and ethylene carbonate; The mass ratio of the bisfluorosulfonyl imide metal compound to the electrolyte solvent is (59:141)-(61:139).

6. The method for preparing a bis(fluorosulfonyl)imide metal liquid salt according to claim 1 or 2, characterized in that: The resin includes one of poly(4-vinylpyridine) resin, poly-N,N-dimethyl-p-styrene resin and poly-N,N-diethyl-p-styrene resin; A / B is 1-5%, wherein A is the mass of the resin, and B is the mass of the bisfluorosulfonyl imide metal compound.

7. The method for preparing a bis(fluorosulfonyl)imide metal liquid salt according to claim 1 or 2, characterized in that: The molten reaction liquid is prepared by reacting bis(fluorosulfonyl)imide and a metal fluoride compound in the absence of a solvent.

8. The method for preparing the bis(fluorosulfonyl)imide metal liquid salt according to claim 7, characterized in that: The reaction temperature of the bis(fluorosulfonyl)imide and the metal fluoride compound is 130-140° C., and the reaction time is 4-8 hours; and / or the molar ratio of the bis(fluorosulfonyl)imide and the metal fluoride compound is 1:(0.95-1.05).

9. The method for preparing a bis(fluorosulfonyl)imide metal liquid salt according to claim 1 or 8, characterized in that: The turbidity of the reaction solution is ≤100; Alternatively, the EP1 acidity of the reaction solution calculated as HF is ≤100 ppm.

10. The method for preparing a bis(fluorosulfonyl)imide metal liquid salt according to claim 1 or 8, characterized in that: The bis(fluorosulfonyl)imide comprises, by mass percentage: Bisfluorosulfonyl imide 99.93-100%, aminosulfonate ≤200ppm, fluorosulfonate ≤300ppm, fluorosulfonamide ≤100ppm, chloride ion ≤50ppm, fluoride ion ≤50ppm; And / or, the metal fluoride compound includes one of lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride, cesium fluoride and francium fluoride; And / or, the metal fluoride compound comprises, by mass percentage: Fluoride metal compound 99.84-100%, carbonate metal compound ≤1000ppm, water ≤600ppm.

11. The method for preparing a bis(fluorosulfonyl)imide metal liquid salt according to claim 1, characterized in that: Before the resin deacidification treatment, the method further includes performing a first filtration treatment on the bis(fluorosulfonyl)imide metal compound solution; And / or, after the resin deacidification treatment, the method further includes performing a second filtration treatment on the deacidified solution system.

12. A bis(fluorosulfonyl)imide metal liquid salt, characterized in that: The bisfluorosulfonyl imide metal liquid salt is prepared by the preparation method of the bisfluorosulfonyl imide metal compound according to any one of claims 1 to 11; The impurities in the bis(fluorosulfonyl)imide metal liquid salt include, by mass percentage: Aminosulfonate ≤100ppm, fluorosulfonate ≤300ppm, fluorosulfonamide ≤10ppm.

13. The bis(fluorosulfonyl)imide metal liquid salt according to claim 12, characterized in that: The bisfluorosulfonyl imide metal liquid salt also includes chloride ion and fluoride ion impurities, the mass percentage of the chloride ion in the bisfluorosulfonyl imide metal liquid salt is not higher than 5ppm, and the mass percentage of the fluoride ion in the bisfluorosulfonyl imide metal liquid salt is not higher than 50ppm.