Lithium bis(fluorosulfonyl)imide containing reduced sulfamide

Abstract

The present invention relates to a bis(fluorosulfonyl)imide lithium salt (LiFSI) having a sulfamide amount of 10 ppm or less by weight, a composition comprising same, and a preparation method therefor. The bis(fluorosulfonyl)imide lithium salt (LiFSI) can be used in a secondary battery having properties such as high output, high energy density and high discharge voltage for a mobile device, an electric vehicle, and an electric storage device.

Description

Lithium bis(fluorosulfonyl)imide with reduced sulfamide content

[0001] The present invention relates to a bis(fluorosulfonyl)imide lithium salt (LiFSI) having a reduced sulfamide content and a method for producing the same.

[0002] With the popularization of mobile devices, the commercialization of electric vehicles, and the increasing demand for energy storage devices, secondary batteries with high output, high energy density, and high discharge voltage are being developed.

[0003] Lithium-ion batteries include a cathode, anode, separator, and electrolyte.

[0004] The above electrolyte serves as a medium for the movement of lithium ions between the positive and negative electrodes, while also improving the thermal, electrical, and physical safety of the battery, and is composed of a solvent, electrolyte salt, and various additives.

[0005] Solvents play a role in dissociating salts, and carbonate and ester types are mainly used, and the bulk ionic conductivity, viscosity, density, and wettability are determined depending on the type of solvent used. There are countless additives and they are related to the formation of SEI (solid electrolyte interphase). Lithium hexafluorophosphate (LiPF6) is mainly used as an electrolyte salt because it has excellent performance and is relatively inexpensive, but LiPF6 has the disadvantage of decomposing into the form of hydrofluoric acid gas.

[0006] To overcome the above drawbacks, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI) have been developed. These salts exhibit little or no spontaneous decomposition and are more hydrolytically stable than LiPF6.

[0007] Meanwhile, LiTFSI is known to have the disadvantage of causing corrosion of aluminum current collectors. However, LiFSI has fewer of these drawbacks and boasts superior performance compared to other conventional salts, attracting attention as a useful salt. In particular, LiFSI exhibits high withstand voltage and conductivity, and its use as an electrolyte is expected to yield various high-performance electrochemical devices.

[0008] The above LiFSI can be prepared from NH4FSI (ammonium bis(fluorosulfonyl)imide).

[0009] Meanwhile, the inventors of the present invention discovered that when using LiFSI as an electrolyte for a secondary battery, the conventional LiFSI contains sulfamide (NH2-SO2-NH2) as an impurity, and that when such LiFSI is used as an electrolyte for a secondary battery, the lifespan of the secondary battery is shortened.

[0010] Accordingly, the present invention sought to provide a lithium bis(fluorosulfonyl)imide that does not shorten the life of a secondary battery.

[0011] In an effort to achieve the above object, the inventors of the present invention have discovered that when the content of sulfamide contained in lithium bis(fluorosulfonyl)imide (LiFSI) is 10 ppm by weight or less, the life of the battery is not shortened even when the LiFSI is used in the electrolyte, and have completed the present invention.

[0012] The present invention provides lithium bis(fluorosulfonyl)imide having a sulfamide content of 10 ppm by weight or less.

[0013] The present invention provides an electrolyte composition comprising 99 wt% or more of lithium bis(fluorosulfonyl)imide and 10 wt ppm or less of sulfamide.

[0014] The present invention relates to a process for producing lithium bis(fluorosulfonyl)imide in the presence of a strong acid, wherein bis(chlorosulfonyl)imide and NH4F(HF) are combined. n It is characterized in that ammonium bis(fluorosulfonyl)imide is prepared by reaction with (n=0 or 1) and is prepared from the ammonium bis(fluorosulfonyl)imide and LiOH.

[0015] In addition, the present invention relates to a method for producing a mixture of bis(chlorosulfonyl)imide (HCSI) and NH4F(HF) in the presence of a strong acid. n The present invention provides a method for producing lithium bis(fluorosulfonyl)imide with reduced sulfamide, comprising the steps of producing ammonium bis(fluorosulfonyl)imide (NH4FSI) using (n=0 or 1); and performing a cation exchange reaction using the ammonium bis(fluorosulfonyl)imide and LiOH.

[0016] The lithium bis(fluorosulfonyl)imide of the present invention, having a sulfamide content of 10 ppm by weight or less, has the effect of not shortening the life of the battery when used as an electrolyte salt for a lithium secondary battery. The present invention has the effect of economically producing lithium bis(fluorosulfonyl)imide having a sulfamide content of 10 ppm by weight or less.

[0017] Hereinafter, the present invention will be described in detail. Terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Rather, they should be interpreted with meanings and concepts consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention.

[0018] The present invention relates to lithium bis(fluorosulfonyl)imide having a sulfamide content of 10 ppm by weight or less.

[0019] The present invention relates to an electrolyte composition comprising sulfamide and lithium bis(fluorosulfonyl)imide in an amount of 10 ppm by weight or less.

[0020] The above lithium bis(fluorosulfonyl)imide reacts with bis(chlorosulfonyl)imide (HCSI) and NH4F(HF) in the presence of a strong acid. n A step of preparing ammonium bis(fluorosulfonyl)imide (NH4FSI) using (n=0 or 1); and a step of preparing lithium bis(fluorosulfonyl)imide by a cation exchange reaction using the ammonium bis(fluorosulfonyl)imide (NH4FSI) and LiOH.

[0021] The present inventors have recognized that, in the conventional process of manufacturing ammonium bis(fluorosulfonyl)imide (NH4FSI) using bis(chlorosulfonyl)imide (HCSI) and NH4F, sulfamide is generated as a side reaction, and is not removed even in the subsequent process of manufacturing LiFSI through a cation exchange reaction, and thus remains in the final LiFSI. Furthermore, they have discovered that using LiFSI containing a large amount of sulfamide in this way as an electrolyte for a secondary battery shortens the lifespan of the secondary battery.

[0022] Furthermore, the inventors of the present invention have confirmed that when lithium bis(fluorosulfonyl)imide containing 10 ppm by weight or less is used in a secondary battery electrolyte, the reduction in the lifespan of the battery can be prevented, and completed the present invention, although the absence of sulfamide is most preferred.

[0023] [sulfamide]

[0024]

[0025] The present invention provides lithium bis(fluorosulfonyl)imide having a sulfamide content of 10 wt ppm or less, obtained by reacting lithium bis(fluorosulfonyl)imide containing sulfamide with benzyl to obtain a compound of chemical formula a and measuring the compound using liquid chromatography (LC).

[0026] The measurement of the content of the chemical formula a compound can be accomplished by creating a calibration curve using lithium bis(fluorosulfonyl)imide, which has a known sulfamide content.

[0027] Equation (1)

[0028]

[0029] The above sulfamide is expected to be produced by NH3 replacing chlorine in the presence of basic NH3 in the reaction step between HCSI and NH4F, as in the reaction path of the following formula (2), but is not limited thereto.

[0030] Equation (2)

[0031]

[0032] Accordingly, the inventors of the present invention found that by allowing a small amount of strong acid to be present in the reaction step between HCSI and NH4F, the content of basic NH3 was reduced, and as a result, the content of sulfamide was reduced to 10 wt ppm or less.

[0033] The present invention relates to an electrolyte composition comprising 10 ppm by weight or less of sulfamide and 99 wt% or more of lithium bis(fluorosulfonyl)imide.

[0034] The above electrolyte composition may further include a solvent.

[0035] The electrolyte composition of the present invention contains lithium bis(fluorosulfonyl)imide in an amount of 99 wt% or more, preferably 99.9 wt% or more, and sulfamide in an amount of 10 wt ppm or less, thereby having the effect of preventing shortening of the lifespan at room temperature and the lifespan at high temperatures of a secondary battery when used as an electrolyte for a secondary battery.

[0036] The present invention relates to a process for producing a mixture of bis(chlorosulfonyl)imide (HCSI) and NH4F(HF) in the presence of a strong acid. n The present invention provides a method for producing lithium bis(fluorosulfonyl)imide with reduced sulfamide, comprising the steps of producing ammonium bis(fluorosulfonyl)imide (NH4FSI) using (n=0 or 1); and performing a cation exchange reaction using the ammonium bis(fluorosulfonyl)imide (NH4FSI) and LiOH.

[0037] Specifically, the lithium bis(fluorosulfonyl)imide of the present invention

[0038] (a) Bis(chlorosulfonyl)imide and NH4F(HF) in the presence of a strong acid under a nitrogen atmosphere n A step of producing ammonium bis(fluorosulfonyl)imide by reacting (n=0 or 1) in solvent 1;

[0039] (b) After the completion of the reaction in step (a), the reaction product is cooled to room temperature and insoluble substances are filtered out to obtain ammonium bis(fluorosulfonyl)imide; and

[0040] (c) It can be manufactured including a step of manufacturing a bis(fluorosulfonyl)imide lithium salt by reacting ammonium bis(fluorosulfonyl)imide obtained in step (b) with lithium hydroxide (LiOH) in an amount of 1.2 to 2 equivalents of lithium hydroxide per 1 equivalent of bis(chlorosulfonyl)imide.

[0041] Additionally, after step (c)

[0042] (d) a step of adding solvent 2 as an antisolvent to the reaction solution of step (c) to obtain a precipitate;

[0043] (e) It may include a step of filtering the solution of step (d) and recovering the precipitate to obtain a bis(fluorosulfonyl)imide lithium salt.

[0044] The reaction in step (a) is as shown in the following reaction formula.

[0045] Equation (3)

[0046]

[0047] The present invention performs the reaction of step (a) in the presence of a strong acid.

[0048] In one embodiment, the strong acid is an inorganic acid or organic acid having a pKa<0.5, preferably a pKa<0, such as sulfuric acid, CH3SO3H, p-toluenesulfonic acid, CF3COOH, etc.

[0049] In the above reaction, NH4F(HF) n (n=0 or 1) can react in an amount of 2 to 10 moles, preferably 2.5 to 5 moles, per 1 mole of bis(chlorosulfonyl)imide. In this case, chlorine in bis(chlorosulfonyl)imide can be sufficiently replaced with fluorine.

[0050] The above acid is NH4F(HF) n (n=0 or 1) 0.5-10 parts by weight, preferably 0.5-5 parts by weight, can be used per 100 parts by weight. In this case, the production of alkaline NH3 in the reaction solution can be prevented, thereby preventing the production of sulfamide.

[0051] In the above step (a), various acids including HF are generated. At this time, if nitrogen gas is bubbling is performed on the reaction solution, the next step can be performed with HF significantly removed, thereby reducing hydrolysis of starting materials or intermediates. Nitrogen gas bubbling on the reaction solution can be performed during the reaction or before step (b) after the reaction is completed. Nitrogen gas bubbling can be performed until the pH of the gas discharged from the reaction solution becomes 6 to 8. It is more preferable to stop nitrogen gas bubbling when the pH becomes 6.5 to 7.5, and it is even more preferable to stop nitrogen gas bubbling when the pH becomes 6.8 to 7.2.

[0052] The solvent 1 of the above step (a) is a solvent capable of dissolving bis(fluorosulfonyl)imide lithium salt, and may preferably be at least one selected from the group consisting of diethyl ether, diisopropyl ether, methyl-t-butyl ether, methyl acetate, ethyl acetate, propyl acetate, and butyl acetate. In order to prevent hydrolysis of the reactant or product, it is necessary to make the moisture content in the solvent 1 500 ppm or less, preferably 200 ppm or less.

[0053] The temperature during the fluorination reaction in step (a) can be appropriately adjusted depending on the progress of the reaction, but is preferably -40°C to 200°C, more preferably -20°C to 100°C. The time required for the reaction varies depending on the reaction scale, but is preferably 0.1 hour to 48 hours, more preferably 0.5 hour to 24 hours.

[0054] Step (b) is the step of obtaining ammonium bis(fluorosulfonyl)imide by cooling the reaction product to room temperature after the completion of the reaction in step (a) and filtering out insoluble substances such as NH4Cl. The ammonium bis(fluorosulfonyl)imide obtained as an intermediate can be recovered as a solid and then proceeded to the next step, or it can be used as is in solution.

[0055] The above step (c) is a step of producing a bis(fluorosulfonyl)imide lithium salt by reacting ammonium bis(fluorosulfonyl)imide obtained as an intermediate with lithium hydroxide, and is expressed by the following formula.

[0056] Equation (4)

[0057]

[0058] The above reaction can be carried out by recovering the ammonium bis(fluorosulfonyl)imide obtained as an intermediate as a solid and then reacting it with lithium hydroxide. However, if lithium hydroxide is added to the filtrate of step (b) without recovering the ammonium bis(fluorosulfonyl)imide obtained as an intermediate as a solid, there is an advantage in that a separate ammonium bis(fluorosulfonyl)imide recovery process is not required, thereby shortening the process time and effort and reducing the loss of the product.

[0059] In the present invention, in step (c), lithium hydroxide is reacted in an amount of 1 to 2 equivalents, preferably 1.2 to 2 equivalents, relative to 1 equivalent of bis(chlorosulfonyl)imide. That is, by reacting lithium hydroxide in excess of 1 equivalent relative to 1 equivalent of bis(chlorosulfonyl)imide, the content of NH4 ions in the final product can be reduced, and in particular, can be reduced to 500 wt ppm or less, so that when this is used as an electrolyte thereafter, the carbonate-based solvent, which is an electrolyte solvent, can not be decomposed. When lithium hydroxide is reacted in an amount exceeding 2 equivalents, the effect of reducing the NH4 ion content or the effect of reducing the decomposition rate of the carbonate-based solvent is minimal, but there is a concern that costs may increase due to increased use of raw materials.

[0060] Therefore, the present inventors react lithium hydroxide in an amount of more than 1 to 2 equivalents with respect to 1 equivalent of bis(chlorosulfonyl)imide to produce lithium bis(fluorosulfonyl)imide that is economically suitable and has a sulfamide content of 10 wt ppm or less. The amount of lithium hydroxide reacting with ammonium bis(fluorosulfonyl)imide is more preferably 1.2 to 1.5 equivalents with respect to 1 equivalent of bis(chlorosulfonyl)imide.

[0061] The temperature of the cation exchange reaction from the ammonium salt of bis(fluorosulfonyl)imide to the lithium salt of bis(fluorosulfonyl)imide is not particularly limited, but is preferably 0°C to 200°C, more preferably 10°C to 100°C. The time required for the reaction varies depending on the reaction scale, but is preferably 0.1 hour to 48 hours, more preferably 0.5 hour to 24 hours.

[0062] The reaction can be carried out under atmospheric pressure, but if carried out under reduced pressure, the by-product ammonia is removed, making it easier to synthesize the target product. When reducing the pressure, the reaction pressure is not particularly limited, but is preferably below atmospheric pressure - 0.01 torr, and a reduced pressure that allows the solvent to reflux at 0°C - 100°C is more preferable.

[0063] The reaction vessel for producing lithium bis(fluorosulfonyl)imide of the present invention is more preferably a resin vessel such as a fluororesin or polyethylene.

[0064] The solvent 2 of the above step (d) is an antisolvent that does not dissolve the bis(fluorosulfonyl)imide lithium salt, and may be at least one selected from the group consisting of toluene, hexane, heptane, chloroform, dichloromethane, etc. After step (c), solvent 2 may be added after removing some of the solvent from the reaction solution.

[0065] In the above step (d), the antisolvent may be added in an amount of 50 to 500 parts by weight based on 100 parts by weight of bis(fluorosulfonyl)imide lithium salt, and more preferably, 80 to 300 parts by weight. If the amount of the antisolvent added is less than the above-mentioned range, the bis(fluorosulfonyl)imide lithium salt may not be sufficiently obtained, which is undesirable. If it exceeds the above-mentioned range, the effect does not increase, and other unnecessary byproducts may also be precipitated, which is undesirable.

[0066] The lithium bis(fluorosulfonyl)imide obtained by the manufacturing method of the present invention has a sulfamide content of 10 wt ppm or less. LiFSI having a sulfamide content of 10 wt ppm or less can stabilize an electrolyte and extend the life of a secondary battery when used as an electrolyte. In addition, the lithium bis(fluorosulfonyl)imide of the present invention stabilizes carbonate-based solvents. Therefore, it can be suitably used as a material for an ion conductor constituting an electrochemical device such as a primary battery, a secondary battery such as a lithium ion secondary battery, an electrolytic capacitor, an electric double-layer capacitor, a fuel cell, a solar cell, and an electrochromic element.

[0067] Hereinafter, preferred examples are presented to help understand the present invention, but the following examples are only illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it is also natural that such changes and modifications fall within the scope of the patent claims of the present invention.

[0068] Example 1. Synthesis of bis(fluorosulfonyl)imide lithium salt 1

[0069] In a reactor equipped with a stirrer, a condenser, and a thermometer, 79.57 g of purified ammonium fluoride and 600 g of butyl acetate with a moisture content of 100 wt ppm were charged at room temperature under a nitrogen atmosphere, and 0.8 g of sulfuric acid was added. While stirring the mixture, 100 g (0.47 mol, 1 eq) of bis(chlorosulfonyl)imide was slowly added, and the temperature was raised to 80°C and reacted for 2 hours.

[0070] The temperature was cooled to 60°C without removing the waste solid from the above reaction mixture, and nitrogen gas bubbling was performed. The pH of the escaping gas was checked using pH paper at 5-minute intervals (initial pH approximately 3), and the nitrogen gas bubbling was stopped when the pH reached 7.

[0071] The temperature of the reaction product was cooled to below 10℃ and filtered.

[0072] To the filtrate containing the above-mentioned filtered ammonium bis(fluorosulfonyl)imide, 39.5 g (0.94 mol, 2 eq) of lithium hydroxide monohydrate was added and stirred. Afterwards, the reaction was carried out at less than 5°C for 4 hours and then terminated.

[0073] 74.97 g of distilled water was added, stirred, and the layers were separated to remove the distilled water layer. 22.49 g of distilled water was added again, stirred, and the layers were separated to remove the distilled water layer. The obtained organic layer was filtered and concentrated, and 208.31 g of toluene was added, filtered to obtain a solid, and vacuum-dried to obtain bis(fluorosulfonyl)imide lithium salt (yield 95%).

[0074] Example 2. Synthesis of bis(fluorosulfonyl)imide lithium salt 2

[0075] Bis(fluorosulfonyl)imide lithium salt (yield: 94%) was obtained by performing the same procedure as in Example 1 except that methanesulfonic acid was used instead of sulfuric acid.

[0076] Example 3. Synthesis of bis(fluorosulfonyl)imide lithium salt 3

[0077] Bis(fluorosulfonyl)imide lithium salt (yield: 95%) was obtained by performing the same procedure as in Example 1 except that toluenesulfonic acid was used instead of sulfuric acid.

[0078] Example 4. Synthesis of bis(fluorosulfonyl)imide lithium salt 4

[0079] Bis(fluorosulfonyl)imide lithium salt (yield: 93%) was obtained by performing the same procedure as in Example 1 except that trifluoroacetic acid was used instead of sulfuric acid.

[0080] Example 5. Synthesis of bis(fluorosulfonyl)imide lithium salt 5

[0081] Bis(fluorosulfonyl)imide lithium salt (yield 93%) was obtained by performing the same procedure as in Example 1 except that 1.2 g of sulfuric acid was used.

[0082] Example 6. Synthesis of bis(fluorosulfonyl)imide lithium salt 6

[0083] Bis(fluorosulfonyl)imide lithium salt (yield 94%) was obtained by performing the same procedure as in Example 1 except that 1.5 g of sulfuric acid was used.

[0084] Example 7. Synthesis of bis(fluorosulfonyl)imide lithium salt 7

[0085] Bis(fluorosulfonyl)imide lithium salt (yield: 95%) was obtained by performing the same procedure as in Example 1 except that 0.6 g of sulfuric acid was used.

[0086] Example 8. Synthesis of bis(fluorosulfonyl)imide lithium salt 5

[0087] Bis(fluorosulfonyl)imide lithium salt (yield 93%) was obtained by performing the same procedure as in Example 1 except that 1.2 g of methanesulfonic acid was used.

[0088] Example 9. Synthesis of bis(fluorosulfonyl)imide lithium salt 5

[0089] Bis(fluorosulfonyl)imide lithium salt (yield: 93%) was obtained by performing the same procedure as in Example 1 except that 1.2 g of trifluoroacetic acid was used.

[0090] Comparative Example 1.

[0091] Bis(fluorosulfonyl)imide lithium salt was obtained by performing the same procedure as in Example 1 without adding sulfuric acid.

[0092]

[0093] Experimental Example 1. Measurement of sulfamide content

[0094] The sulfamide content of the bis(fluorosulfonyl)imide lithium salts manufactured in the examples and comparative examples was measured by the following method.

[0095] To prepare a calibration curve, a dimethyl carbonate solution was prepared by dissolving LiFSI containing 10, 50, 100, 150, 200, and 300 wt ppm of sulfamide, respectively, and then reacting the solution with benzyl as shown in the following formula to obtain a compound of formula a, and a calibration curve for the compound of formula a was prepared using liquid chromatography (LC). Thereafter, the content of the compound of formula a in the LiFSI prepared by reacting the LiFSI prepared in the examples and comparative examples with benzyl was obtained by comparing it with the calibration curve, and the content of sulfamide was obtained.

[0096] Equation (1)

[0097]

[0098] Example Comparative Example 1123456789 Sulfamide content (weight ppm) 7981076889150

[0099] In the case of the bis(fluorosulfonyl)imide lithium salts prepared in Examples 1 to 9 of the present invention with the addition of a strong acid, the content of sulfamide was confirmed to be 10 ppm by weight or less, whereas in the case of the lithium bis(fluorosulfonyl)imide of the comparative example, the content of sulfamide was confirmed to exceed 10 ppm by weight.

[0100] Experimental Example 2. Preparation of Non-Aqueous Electrolyte

[0101] Experimental Example 2-1.

[0102] A 0.5 M LiFSI solution was prepared by mixing the lithium bis(fluorosulfonyl)imide of Example 1 with a solvent of 3:7 by volume of ethylene carbonate (EC) and ethyl methyl carbonate (EMC). LiPF6 was added to the solution at a concentration of 0.5 M, and LiPO2F2 was added as an additive in an amount of 1 wt% based on 100 wt% of the total electrolyte, and then mixed to prepare a non-aqueous electrolyte.

[0103] Experimental examples 2-2 to 2-9 and comparative experimental example 2-1

[0104] A non-aqueous electrolyte was prepared in the same manner as in Experimental Example 2-1 using lithium bis(fluorosulfonyl)imide of Examples 2 to 7 and Comparative Example 1, respectively.

[0105] Experimental Example 3. Confirmation of Lithium Secondary Battery Life Characteristics

[0106] A 1.4 Ah pouch battery was assembled using a conventional method using a cathode material using LiNi / Co / Mn as a cathode active material and an anode material using artificial graphite and natural graphite in a 1:1 weight ratio, and 6.0 g of the electrolyte prepared in Experimental Example 2 was injected to complete the secondary battery.

[0107] (1) Room temperature lifespan

[0108] The secondary battery was charged at room temperature (25°C) at 1C to 4.5 V, then discharged at 1C to 2.75 V to measure the initial capacity. After repeating this process 100 times, the capacity was measured and the life maintenance rate (%) was calculated using the following mathematical formula 1.

[0109] [Mathematical Formula 1]

[0110] Life maintenance rate = (discharge capacity after 100 repetitions / initial discharge capacity) × 100

[0111] (2) High temperature lifespan maintenance rate

[0112] The secondary battery was charged at a high temperature (45°C) at 1C to 4.5V, then discharged at 1C to 2.75V to measure the initial capacity, and after repeating this 100 times, the capacity was measured to calculate the life maintenance rate (%) using the above mathematical formula 1.

[0113] Experimental reserve electrolyte room temperature life maintenance rate (%) High temperature life maintenance rate (%) Experimental example 3-1 Experimental example 2-193.787.4 Experimental example 3-2 Experimental example 2-291.882.3 Experimental example 3-3 Experimental example 2-392.583.5 Experimental example 3-4 Experimental example 2-491.683.0 Experimental example 3-5 Experimental example 2-593.587.4 Experimental example 3-6 Experimental example 2-693.987.6 Experimental example 3-7 Experimental example 2-792.984.5 Experimental example 3-8 Experimental example 2-892.784.9 Experimental example 3-9 Experimental example 2-992.183.1 Comparative experimental example 3-1 Comparative experimental example 2-188.775.9

[0114] It can be seen that the non-aqueous electrolyte using lithium bis(fluorosulfonyl)imide of the present invention has a reduced sulfamide content, and thus has a higher room temperature lifespan and a higher high temperature lifespan than the non-aqueous electrolyte containing lithium bis(fluorosulfonyl)imide of Comparative Example 1.

[0115] The bis(fluorosulfonyl)imide lithium salt (LiFSI) with reduced sulfamide content of the present invention can be used in secondary batteries having high output, high energy density, high discharge voltage, etc. for mobile devices, electric vehicles, and electric storage devices.

Claims

1. Lithium bis(fluorosulfonyl)imide having a sulfamide content of 10 ppm by weight or less.

2. In claim 1, lithium bis(fluorosulfonyl)imide containing sulfamide is reacted with benzyl to obtain a compound of formula a, and the sulfamide content obtained by measuring it by liquid chromatography (LC) is 10 ppm by weight or less. Equation (1) 3. In claim 2, the content of the compound of formula a is measured by a method of creating a calibration curve using lithium bis(fluorosulfonyl)imide, which has a known content of sulfamide.

4. In claim 1, lithium bis(fluorosulfonyl)imide reacts with bis(chlorosulfonyl)imide and NH4F(HF) in the presence of a strong acid. n Lithium bis(fluorosulfonyl)imide characterized in that it is produced by reaction with (n=0 or 1) and produced from ammonium bis(fluorosulfonyl)imide and LiOH.

5. In claim 4, the strong acid is lithium bis(fluorosulfonyl)imide, which is at least one selected from the group consisting of sulfuric acid, CH3SO3H, p-toluenesulfonic acid, and CF3COOH.

6. An electrolyte composition comprising 10 ppm by weight or less of sulfamide and 99% by weight or more of lithium bis(fluorosulfonyl)imide.

7. A composition for an electrolyte, wherein the content of sulfamide is 10 wt ppm or less, obtained by reacting a lithium bis(fluorosulfonyl)imide-containing composition containing sulfamide with benzyl to obtain a compound of formula a and measuring it by liquid chromatography (LC) according to claim 6. Equation (1) 8. In claim 7, a composition for an electrolyte, wherein the content of the compound of formula a is measured by a method of creating a calibration curve using lithium bis(fluorosulfonyl)imide having a known sulfamide content.

9. Bis(chlorosulfonyl)imide (HCSI) and NH4F(HF) in the presence of strong acid n A step of preparing ammonium bis(fluorosulfonyl)imide (NH4FSI) using (n=0 or 1); and A method for producing lithium bis(fluorosulfonyl)imide with reduced sulfamide, characterized by including a step of performing a cation exchange reaction using the above ammonium bis(fluorosulfonyl)imide and lithium hydroxide.

10. A method for producing lithium bis(fluorosulfonyl)imide with reduced sulfamide, comprising 10 ppm by weight or less of sulfamide in claim 9.

11. In claim 9, a method for producing lithium bis(fluorosulfonyl)imide with reduced sulfamide, wherein the cation exchange reaction is performed by reacting 1.2 to 2 equivalents of lithium hydroxide with 1 equivalent of bis(chlorosulfonyl)imide.

12. A method for producing lithium bis(fluorosulfonyl)imide with reduced sulfamide, characterized in that the strong acid in claim 9 is an inorganic acid or organic acid with pKa<0.

5.

13. A method for producing lithium bis(fluorosulfonyl)imide with reduced sulfamide, characterized in that in claim 12, the strong acid is at least one selected from the group consisting of sulfuric acid, CH3SO3H, p-toluenesulfonic acid, and CF3COOH.

14. In claim 13, the strong acid is NH4F(HF) n A method for producing lithium bis(fluorosulfonyl)imide with reduced sulfamide, characterized in that the reaction is performed in the presence of 0.5 to 10 parts by weight per 100 parts by weight of (n=0 or 1).

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