Fluorosulfonyl imide salt and preparation method thereof

Abstract

The invention discloses a fluorosulfonyl imide salt and a preparation method thereof. A fluorosulfonyl imide salt represented by chemical formula (Ib) of the present invention contains at least one of an impurity [NS2O5F] 2-represented by the following chemical formula (IIb) and an impurity [NS2O6] 3-represented by the following chemical formula (IIIb) wherein the content of [NS2O5F] 2-is 10,000 ppm or less and the content of [NS2O6] 3-is 10,000 ppm or less, in chemical formula (Ib), M2 is any one of Li, Na, K, Ca, Mg, Zn, Sb, Rb, and Cs; a1 is fluorine atoms or alkyl with 1-6 carbon atoms, wherein one or more hydrogen atoms of the alkyl are substituted by the fluorine atoms. The fluorosulfonyl imide salt provided by the invention can reduce the corrosion of electrolyte, additives and current collectors. Chemical formula (Ib)... Chemical formula (IIb)... Chemical formula (IIIb)

Description

Technical Field

[0001] This invention relates to a fluorosulfonyl imide salt and its preparation method, and more specifically, to a fluorosulfonyl imide salt and its preparation method that removes impurities by adding a chlorinating agent. Background Technology

[0002] Fluorosulfonyl imide salts (such as alkali metal fluorosulfonyl imide salts) are versatile compounds that can be used as electrolytes (especially in lithium secondary batteries), fuel cell electrolytes, selective electrophilic fluorinating agents, and infrared absorbing pigments.

[0003] Conventional methods for preparing fluorosulfonyl imide salts include halogen exchange of chlorosulfonyl imide. For example, the preparation method of lithium bis(fluorosulfonyl)imide, which is widely used in industry, involves reacting chlorosulfonyl isocyanate with chlorosulfonic acid to prepare bis(chlorosulfonyl)imide, followed by halogen exchange of the bis(chlorosulfonyl)imide.

[0004] However, the bis(fluorosulfonyl)imide lithium salt prepared in this way is weakly acidic and may therefore corrode the electrolyte, additives, and current collector.

[0005] Research into the causes of corrosion of electrolytes, additives, and current collectors by lithium bis(fluorosulfonyl)imide salts revealed that lithium bis(fluorosulfonyl)imide salts contain ions with sulfonic acid groups (-SO3H) or sulfonate groups (-SO3M). These ions release hydrogen ions into the electrolyte or decompose the electrolyte and additives to produce hydrofluoric acid, thereby causing corrosion of the electrolyte, additives, and current collectors. Summary of the Invention

[0006] Technical issues

[0007] One aspect of the present invention, conceived to solve the above problems, is to provide a fluorosulfonamide salt and a method for preparing the same, which can reduce corrosion of electrolytes, additives and current collectors.

[0008] Another aspect of the present invention is to provide bis(chlorosulfonyl)imide and a method for preparing bis(chlorosulfonyl)imide, wherein the bis(chlorosulfonyl)imide is an intermediate for preparing fluorosulfonylimide salts and the impurity content is reduced.

[0009] Another aspect of the present invention is to provide fluorosulfonylimide and a method for preparing fluorosulfonylimide, wherein the fluorosulfonylimide is an intermediate for preparing fluorosulfonylimide salts and the impurity content is reduced.

[0010] Other objects of the present invention will be more clearly understood through the following embodiments.

[0011] Technical solution

[0012] According to one aspect of the present invention, the bis(chlorosulfonyl)imide contains at least one of the following impurities: H2O5NClS2 represented by the following chemical formula (IIa) in an amount of less than 10,000 ppm and H3O6NS2 represented by the following chemical formula (IIIa) in an amount of less than 10,000 ppm.

[0013] ...Chemical formula (IIa)

[0014] ... Chemical formula (IIIa).

[0015] Here, by adding a chlorinating agent during the preparation of bis(chlorosulfonyl)imide, the content of H2O5NClS2 can be below 10,000 ppm, and the content of H3O6NS2 can be below 10,000 ppm.

[0016] Here, the content of H2O5NClS2 can be 7,100 ppm or less, and the content of H3O6NS2 can be 6,700 ppm or less.

[0017] Here, the chlorinating agent may be at least one compound selected from SOCl2, SO2Cl2, COCl2, C2O2Cl2, POCl3, PCl5, SbCl3, ClSO2NCO, SO2(NCO)2, SiCl4, ICl, ICl3, S2Cl2, SCl2, PCl3, COCl2 and C6H5CCl3.

[0018] According to another aspect of the invention, a fluorosulfonamide represented by the following chemical formula (Ia) contains an impurity represented by the following chemical formula (IIb): [NS₂O₅F]. 2- And the impurity represented by the following chemical formula (IIIb): [NS2O6] 3- At least one of the following, wherein the [NS2O5F] is prepared by adding a chlorinating agent during the preparation process. 2- The content of [NS2O6] is below 10,000 ppm. 3- The content is below 10,000 ppm:

[0019] ...Chemical formula (Ia)

[0020] ...Chemical formula (IIb)

[0021] ...Chemical formula (IIIb)

[0022] In the above chemical formula (Ia), M1 is H, and A1 is a fluorine atom or an alkyl group with 1-6 carbon atoms in which one or more hydrogen atoms are replaced by fluorine atoms.

[0023] Here, [NS2O5F] is mentioned. 2- The content of [NS2O6] can be below 7,100 ppm. 3- The content can be below 6,700 ppm.

[0024] According to another aspect of the present invention, a fluorosulfonamide salt represented by the following chemical formula (Ia) contains an impurity represented by the following chemical formula (IIb): [NS₂O₅F]. 2- And the impurity represented by the following chemical formula (IIIb): [NS2O6] 3- At least one of the following, wherein the [NS2O5F] is prepared by adding a chlorinating agent during the preparation process. 2- The content of [NS2O6] is below 10,000 ppm. 3- The content is below 10,000 ppm:

[0025] ...Chemical formula (Ia)

[0026] ...Chemical formula (IIb)

[0027] ...Chemical formula (IIIb)

[0028] In the above chemical formula (Ia), M1 is any one of NH4, Li, Na, K, Ca, Mg, Zn, Sb, Rb and Cs, and A1 is an alkyl group with 1-6 carbon atoms, or one or more hydrogen atoms replaced by fluorine atoms.

[0029] Here, [NS2O5F] is mentioned. 2- The content of [NS2O6] can be below 7,100 ppm. 3- The content can be below 6,700 ppm.

[0030] According to another aspect of the present invention, a fluorosulfonamide salt represented by the following chemical formula (Ib) contains an impurity represented by the following chemical formula (IIb): [NS₂O₅F]. 2- And the impurity represented by the following chemical formula (IIIb): [NS2O6] 3- At least one of the following, wherein the [NS2O5F] 2- The content of [NS2O6] is below 10,000 ppm. 3-The content is below 10,000 ppm:

[0031] ...Chemical formula (Ib)

[0032] ...Chemical formula (IIb)

[0033] ...Chemical formula (IIIb)

[0034] In the above chemical formula (Ib), M2 is any one of Li, Na, K, Ca, Mg, Zn, Sb, Rb and Cs, and A1 is an alkyl group with 1-6 carbon atoms, or one or more hydrogen atoms replaced by fluorine atoms.

[0035] Here, [NS2O5F] is mentioned. 2- The content of [NS2O6] can be below 7,100 ppm. 3- The content can be below 6,700 ppm.

[0036] Here, [NS2O5F] is mentioned. 2- The content of [NS2O6] can be below 6,300 ppm. 3- The concentration can be below 5,200 ppm.

[0037] Here, [NS2O5F] is mentioned. 2- The content of [NS2O6] can be below 289 ppm. 3- The content can be below 325 ppm.

[0038] Here, [NS2O5F] is mentioned. 2- The content of [NS2O6] can be below 187 ppm. 3- The content can be below 124 ppm.

[0039] Here, the fluorosulfonamide salt has a pH value of 6 or higher and 9 or lower in aqueous solution.

[0040] According to another aspect of the invention, the electrolyte comprises the above-mentioned fluorosulfonamide or fluorosulfonamide salt.

[0041] According to another aspect of the invention, an electrochemical device comprises the aforementioned electrolyte.

[0042] A method for preparing bis(chlorosulfonyl)imide according to another aspect of the present invention includes: reacting chlorosulfonyl isocyanate with chlorosulfonic acid; and adding a chlorinating agent to the reaction product.

[0043] Here, the reaction product may contain at least one of the following chemical formula (IIa): H2O5NClS2 and the following chemical formula (IIIa): H3O6NS2, wherein the addition of the chlorinating agent comprises removing the impurities contained in the reaction product:

[0044] ...Chemical formula (IIa)

[0045] ... Chemical formula (IIIa).

[0046] Here, by removing impurities, the content of residual H2O5NClS2 in the bis(chlorosulfonyl)imide can be less than 10,000 ppm, and the content of residual H3O6NS2 can be less than 10,000 ppm.

[0047] Here, by removing impurities, the content of residual H2O5NClS2 in the bis(chlorosulfonyl)imide can be less than 7,100 ppm, and the content of residual H3O6NS2 can be less than 6,700 ppm.

[0048] Here, the chlorination reagent may be at least one compound selected from SOCl2, SO2Cl2, COCl2, C2O2Cl2, POCl3, PCl5, SbCl3, ClSO2NCO, SO2(NCO)2, SiCl4, ICl, ICl3, S2Cl2, SCl2, PCl3, COCl2 and C6H5CCl3.

[0049] According to another aspect of the present invention, a method for preparing a fluorosulfonyl imide salt represented by the following chemical formula (Ia) comprises: reacting chlorosulfonyl isocyanate with chlorosulfonic acid to obtain a bis(chlorosulfonyl)imide containing at least one of impurities H2O5NClS2 and H3O6NS2; adding a chlorinating agent to the bis(chlorosulfonyl)imide to remove the impurities; and adding butyl acetate to a fluorine compound and stirring, followed by adding the bis(chlorosulfonyl)imide with the impurities removed.

[0050] ...Chemical formula (Ia)

[0051] In the above chemical formula (Ia), M1 is any one of NH4, Li, Na, K, Ca, Mg, Zn, Sb, Rb, and Cs, and A1 is a fluorine atom.

[0052] According to another aspect of the present invention, a method for preparing a bis(fluorosulfonyl)imide salt comprises: reacting a chlorosulfonyl isocyanate with chlorosulfonic acid to obtain a bis(chlorosulfonyl)imide containing at least one impurity selected from H₂O₅NClS₂ represented by chemical formula (IIa) and H₃O₆NS₂ represented by chemical formula (IIIa); adding a chlorinating agent to the bis(chlorosulfonyl)imide to remove the impurity; obtaining a bis(fluorosulfonyl)imide ammonium salt from the bis(chlorosulfonyl)imide with the impurity removed; and obtaining a bis(chlorosulfonyl)imide salt represented by chemical formula (Ib) from the obtained bis(fluorosulfonyl)imide ammonium salt.

[0053] ...Chemical formula (IIa)

[0054] ...Chemical formula (IIIa)

[0055] ...Chemical formula (Ib)

[0056] In the above chemical formula (Ib), M2 is any one of Li, Na, K, Ca, Mg, Zn, Sb, Rb and Cs, and A1 is a fluorine atom.

[0057] The obtained bis(fluorosulfonyl)imide salt contains an impurity represented by the following chemical formula (IIb): [NS₂O₅F] 2- And the impurity represented by the following chemical formula (IIIb): [NS2O6] 3- At least one of the following, wherein the [NS2O5F] 2- The content of [NS2O6] is below 10,000 ppm. 3- The content is below 10,000 ppm.

[0058] ...Chemical formula (IIb)

[0059] ... Chemical formula (IIIb).

[0060] Here, [NS2O5F] is mentioned. 2- The content of [NS2O6] is below 7,100 ppm. 3- The content is below 6,700 ppm.

[0061] Here, the bis(fluorosulfonyl)imide salt has a pH value of 6 or higher and 9 or lower in aqueous solution.

[0062] Here, the chlorination reagent can be at least one compound selected from SOCl2, SO2Cl2, COCl2, C2O2Cl2, POCl3, PCl5, SbCl3, ClSO2NCO, SO2(NCO)2, SiCl4, ICl, ICl3, S2Cl2, SCl2, PCl3, COCl2 and C6H5CCl3.

[0063] Beneficial effects

[0064] The fluorosulfonamide salts according to embodiments of the present invention can reduce corrosion of electrolytes, additives and current collectors.

[0065] Furthermore, embodiments of the present invention can reduce impurities during the preparation of the intermediate (bis(chlorosulfonyl)imide) of bis(fluorosulfonyl)imide and during the preparation of bis(fluorosulfonyl)imide. Detailed Implementation

[0066] Because this invention allows for various modifications and multiple embodiments, specific embodiments will be shown in the accompanying drawings and described in detail in the written description. However, this is not intended to limit the invention to the specific implementations, and it should be understood that all modifications, equivalents, and substitutions that do not depart from the spirit and scope of the invention are included within its scope. In the description of the invention, certain detailed explanations of related technologies are omitted if it is believed that they might unnecessarily obscure the essence of the invention.

[0067] While terms such as "first" and "second" can be used to describe various components, these components are not limited to the terms mentioned above. The terms mentioned above are only used to distinguish one component from another.

[0068] The terminology used in this specification is for describing particular embodiments only and is not intended to limit the invention. Unless the context clearly indicates otherwise, singular expressions include plural expressions. It should be understood in this specification that terms such as “comprising” or “having” are intended to indicate the presence of features, quantities, steps, actions, components, portions, or combinations thereof disclosed in the specification, and are not intended to exclude the possibility of the presence or addition of one or more other features, quantities, steps, actions, components, portions, or combinations thereof. Certain embodiments of the invention will be described in more detail below.

[0069] The method for preparing bis(chlorosulfonyl)imide according to an embodiment of the present invention is characterized by including a step of adding a chlorinating agent. More specifically, the method is characterized by using a chlorinating agent to remove at least one of impurities 1a and 2a generated during the preparation of bis(chlorosulfonyl)imide as shown in the following reaction formula (I). Here, "removal" can refer to removing the substance to the extent that the remaining trace amount cannot be detected by a measuring device. For example, the remaining amount can be less than 1 ppm, less than 3 ppm, less than 10 ppm, or less than 100 ppm. On the other hand, "removal" can refer to removing the substance to the extent that the negative impact of the substance in a secondary battery is minimized. For example, the remaining amount can be less than 1000 ppm, less than 3000 ppm, less than 5000 ppm, or less than 10000 ppm.

[0070] Removal by chlorination reagent can be carried out according to reaction formulas (IIa) and (IIb) shown below.

[0071]

[0072] Fluorosulfonyl imide salts are core components (electrolytes) in secondary batteries, offering the advantage of higher decomposition temperatures compared to LiPF6, a commonly used electrolyte in existing technologies. A representative example of a fluorosulfonyl imide salt is lithium bis(fluorosulfonyl)imide, represented by the following chemical formula (IV).

[0073] ...chemical formula (IV)

[0074] The conventional process for preparing fluorosulfonyl imide salts mainly includes three steps. Step 1 can be a process for preparing chlorosulfonyl imide from raw materials, Step 2 can be a process for replacing chlorine with fluorine by adding ammonium fluoride, and Step 3 can be a process for replacing ammonium ions with alkali metal ions.

[0075] [Step 1 Process]

[0076] The process in step 1 can be the process for preparing chlorosulfonylimide from raw materials as shown in reaction formula (I). Here, the raw materials may include chlorosulfonyl isocyanate and chlorosulfonic acid.

[0077]

[0078] Reaction formula (I)

[0079] Here, at least one of H2O5NClS2 represented by the following chemical formula (IIa) and H3O6NS2 represented by the following chemical formula (IIIa) may be generated as an impurity. The content of the generated impurities H2O5NClS2 and H3O6NS2 may be greater than or equal to 10,000 ppm each or in combination.

[0080] ...Chemical formula (IIa)

[0081] ...Chemical formula (IIIa)

[0082] Step 2 may involve adding ammonium fluoride (NH4F) to the product of step 1 and reacting it. More specifically, this process may include mixing ammonium fluoride with a solvent and then adding the product of step 1. Here, the solvent preferably includes one or more of toluene, haloalkanes, nitriles, ethers, alcohols, esters, and carbonates. Specifically, the solvent may be dimethoxyethane, ethyl acetate, butyl acetate, toluene, chloroform, dichloromethane, dichloroethane, tetrahydrofuran, acetonitrile, etc. After the reaction of ammonium fluoride with the product of step 1 is completed, a step of adding a nonpolar solvent to recrystallize the product of step 2 may also be included. The product of step 1 may be a bis(chlorosulfonyl)imide containing impurities, and the product of step 2 may be a bis(fluorosulfonyl)imide ammonium salt.

[0083] The product of step 1 may contain at least one of H2O5NClS2 and H3O6NS2 as impurities. These impurities can be converted in step 2 into HO5NFS2⁻ (represented by chemical formula (1b) and H2O6NS2 (represented by chemical formula (2b)) according to the following reaction (III). - At least one of O5NFS2²⁻ represented by chemical formula (3b) and O6NS2³⁻ represented by chemical formula (4b). More specifically, impurity 1a represented by chemical formula (IIa) can react with ammonium fluoride in step 2 to form impurity 1b and impurity 3b. Similarly, impurity 2a represented by chemical formula (IIIa) can react with ammonium fluoride in step 2 to form impurity 2b and impurity 4b.

[0084]

[0085] Reaction (III)

[0086]

[0087] ...Chemical formula (IIb)

[0088]

[0089] ...Chemical formula (IIIb)

[0090] Step 3 may involve adding a metal compound to the product of step 2. Here, the metal compound may be a hydroxide. More specifically, the process may include mixing the hydroxide of the metal compound with a solvent, and then adding the product of step 2. The metal in the metal compound may be Li, Na, K, Ca, Mg, Zn, Sb, Rb, or Cs. The solvent preferably includes one or more of toluene, haloalkanes, nitrile solvents, ethers, alcohols, esters, and carbonate solvents. Specifically, the solvent may include isopropyl ether, dimethoxyethane, ethyl acetate, butyl acetate, toluene, chloroform, dichloromethane, dichloroethane, tetrahydrofuran, acetonitrile, etc. Here, NH3 gas is generated as the reaction proceeds; the cessation of NH3 gas production indicates whether the reaction is complete. Furthermore, after the step of adding the metal compound to the product of step 2 and allowing it to react, a step of adding a nonpolar solvent EDC for recrystallization may also be included.

[0091] Impurities 1b, 2b, 3b and 4b contained in the product of process 2 can participate in the reaction of process 3 as shown in the following reaction formula (IV) to generate impurities 1c, 2c, 3c, 4c and 5c.

[0092]

[0093] Reaction formula (IV)

[0094] (In the above reaction formula (IV), M2 is an element selected from Li, Na, K, Ca, Mg, Zn, Sb, Rb and Cs.)

[0095] In summary, during the preparation of bis(fluorosulfonyl)imide salt, the impurities generated in step 1 may participate in the reactions of steps 2 and 3, and thus may ultimately form at least one of impurities 1c, 2c, 3c, 4c and 5c and remain in the bis(fluorosulfonyl)imide salt.

[0096] When a bis(fluorosulfonyl)imide salt containing at least one of impurities 1c, 2c, 3c, 4c, and 5c is added as a salt to the electrolyte of a lithium secondary battery, as shown in reactions (V) and (VI) below, hydrogen ions are released instead of metallic hydrogen ions due to the presence of sulfonic acid groups (-SO3H). This may cause the following problems. First, the electrolyte and electrolyte additives may decompose. In lithium secondary batteries, the electrolyte mainly uses organic solvents such as ethylene carbonate, and the additives mainly use organic compounds such as fluoroethylene carbonate. These organic compounds are not acid-resistant and are easily decomposed, especially when the battery charging and discharging causes the temperature to rise and increases its reactivity with acids. Second, the positive and negative current collectors may be corroded. The hydrogen ions released by the sulfonic acid groups can react directly with the positive and negative current collectors, causing corrosion and producing hydrogen gas, which may lead to battery swelling. In addition, similar to moisture inside the battery, sulfonate groups (-SO3M) may decompose the electrolyte and additives, thereby reducing battery efficiency, and the byproducts generated at this time (i.e., hydrofluoric acid) may shorten battery life by corroding the positive and negative current collectors.

[0097] <Step 1 Method>

[0098] The method for preparing bis(chlorosulfonyl)imide according to embodiments of the present invention may include the steps of reacting chlorosulfonyl isocyanate (OCNSO2Cl) with chlorosulfonic acid (ClSO3H); and the step of adding a chlorinating agent to the above reaction product.

[0099] Here, the reaction temperature in the step of reacting chlorosulfonyl isocyanate (OCNSO2Cl) with chlorosulfonic acid (ClSO3H) can be above 100°C and below 150°C. Preferably, the reaction temperature can be above 125°C and below 135°C. The step of reacting chlorosulfonyl isocyanate with chlorosulfonic acid can continue until the production of carbon dioxide gas stops. This is because carbon dioxide gas is produced in the step of reacting chlorosulfonyl isocyanate with chlorosulfonic acid, so the cessation of carbon dioxide gas production can be regarded as a sign that the reaction is complete.

[0100] When chlorosulfonyl isocyanate reacts with chlorosulfonic acid, in addition to bis(chlorosulfonyl)imide, at least one of impurities 1a and 2a represented in reaction formula (I) may be generated. Impurity 1a may be H2O5NClS2 represented by the following chemical formula (IIa), and impurity 2a may be H3O6NS2 represented by the following chemical formula (IIIa). The content of the generated impurities H2O5NClS2 and H3O6NS2 may be greater than or equal to 10,000 ppm each or in combination.

[0101] ...Chemical formula (IIa)

[0102] ...Chemical formula (IIIa)

[0103] <Step 1 Method>

[0104] Here, the step of adding the chlorinating agent can be a step of removing H2O5NClS2 represented by the above chemical formula (IIa) and H3O6NS2 represented by the above chemical formula (IIIa) contained in the above reaction product.

[0105] The amount of chlorinating agent added can be determined based on the amount of chlorosulfonyl isocyanate added. More specifically, the amount of chlorinating agent added can be 1 / 8 to 1 / 20 of the number of chlorosulfonyl isocyanate molecules. This amount is preferably 1 / 9 to 1 / 15, and more preferably 1 / 10.

[0106] Regarding the steps of adding chlorination reagent, the reasons for adding chlorination reagent are explained below in conjunction with the reaction formulas (I), (IIa), and (IIb) shown below.

[0107]

[0108] Reaction (I) is not written in the correct stoichiometric ratio, but is intended to show that impurities 1 and 2 are obtained as reaction products. Similarly, reactions (IIa) and (IIb) are also not written in the correct stoichiometric ratio, but are intended to show that impurities 1 and 2 are removed by adding a chlorinating agent.

[0109] H₂O₅NClS₂ and H₃O₆NS₂ can be at least partially removed by a chlorinating agent. The chlorinating agent can be selected from at least one compound selected from SOCl₂, SO₂Cl₂, COCl₂, C₂O₂Cl₂, POCl₃, PCl₅, SbCl₃, ClSO₂NCO, SO₂(NCO)₂, SiCl₄, ICl, ICl₃, S₂Cl₂, SCl₂, PCl₃, COCl₂, and C₆H₅CCl₃.

[0110] When a chlorination reaction occurs due to the addition of a chlorinating agent, the sulfonic acid group (-SO3H) in H2O5NClS2 and H3O6NS2 can be converted into a chlorosulfonyl group (-SO2Cl), and H2O5NClS2 and H3O6NS2 can be converted into bis(chlorosulfonyl)imine.

[0111] <Step 1 Method>

[0112] The method for preparing bis(chlorosulfonyl)imide according to an embodiment of the present invention is characterized in that, by removing H2O5NClS2 and H3O6NS2, the residual content of H2O5NClS2 and H3O6NS2 in the bis(chlorosulfonyl)imide is 10,000 ppm or less each. Furthermore, the residual content of H2O5NClS2 and H3O6NS2 can be 7,100 ppm or less and 6,700 ppm or less, respectively. Furthermore, the residual content of H2O5NClS2 and H3O6NS2 can be 6,300 ppm or less and 5,200 ppm or less, respectively. Furthermore, the residual content of H2O5NClS2 and H3O6NS2 can be 289 ppm or less and 325 ppm or less, respectively. Furthermore, the residual content of H2O5NClS2 and H3O6NS2 can be 187 ppm or less and 124 ppm or less, respectively.

[0113] <Step 2 Method>

[0114] According to another aspect of the present invention, the present invention can provide a method for preparing a fluorosulfonyl imide salt represented by chemical formula (Ia), the method comprising: reacting chlorosulfonyl isocyanate with chlorosulfonic acid to obtain a bis(chlorosulfonyl)imide containing at least one of H2O5NClS2 and H3O6NS2 as impurities; adding a chlorinating agent to the bis(chlorosulfonyl)imide to remove the impurities; and adding butyl acetate to a fluorine compound and stirring, and then adding the bis(chlorosulfonyl)imide with the impurities removed.

[0115] ...Chemical formula (Ia)

[0116] Here, A1 can be a fluorine atom.

[0117] Here, the chlorinating agent may be selected from at least one compound selected from SOCl2, SO2Cl2, COCl2, C2O2Cl2, POCl3, PCl5, SbCl3, ClSO2NCO, SO2(NCO)2, SiCl4, ICl, ICl3, S2Cl2, SCl2, PCl3, COCl2 and C6H5CCl3.

[0118] Furthermore, the fluorine compound can be selected from any one of HF, NH4F, LiF, NaF, KF, CaF2, MgF2, ZnF2, SbF3, RbF, and CsF. Therefore, M1 in the above chemical formula (Ia) can be any one of H, NH4, Li, Na, K, Ca, Mg, Zn, Sb, Rb, and Cs.

[0119] However, for convenience, the following description uses A1 as a fluorine atom and ammonium fluoride (NH4F) as an example, and the fluorosulfonyl imide salt prepared therefrom is a bis(fluorosulfonyl)imide ammonium salt.

[0120] If impurities are removed by adding a chlorinating agent to bis(chlorosulfonyl)imide, the residual impurity content in the final prepared bis(fluorosulfonyl)imide ammonium salt will also be reduced.

[0121] The step of adding butyl acetate to ammonium fluoride and stirring can be carried out at a temperature cooled to below -5°C. Alternatively, the stirring step can be performed using a magnetic stirrer.

[0122] The step of adding bis(chlorosulfonyl)imide, after removing impurities, can be carried out for more than 40 minutes and less than 80 minutes at a temperature maintained above 0°C and below 15°C. This is because the addition of bis(chlorosulfonyl)imide triggers an exothermic reaction.

[0123] After the exothermic reaction is complete, the temperature can be raised to above 60°C but below 100°C, and the reaction can continue for more than 4 hours but less than 6 hours.

[0124] After the heating reaction is complete, the following steps can be performed: lower the temperature to above 15°C and below 35°C, remove solid impurities by filtration, concentrate the filtrate, and add the non-polar solvent toluene for recrystallization.

[0125] As shown in reaction formula (III) above, the impurities H2O5NClS2 and H3O6NS2 remaining in the product of process 1 can be converted into HO5NFS2 represented by the following chemical formula (1b) in process 2 according to the following reaction formula (III). - H2O6NS2 represented by chemical formula (2b) - O5NFS2 represented by chemical formula (3b) - And O6NS2 represented by chemical formula (4b) 3- At least one of the following. More specifically, impurity 1a, represented by chemical formula (IIa), can react with ammonium fluoride in step 2 to form impurities 1b and 3b. Similarly, impurity 2a, represented by chemical formula (IIIa), can react with ammonium fluoride in step 2 to form impurities 2b and 4b.

[0126] The total content of impurity 1b and impurity 3b can be less than 10,000 ppm, less than 7,100 ppm, less than 6,300 ppm, less than 289 ppm, or less than 187 ppm. Here, the total content of impurity 1b and impurity 3b can be expressed as [NS2O5F]. 2- Measurements are taken in the form of [formula missing].

[0127] Furthermore, the total content of impurities 2b and 4b can be less than 10,000 ppm, less than 6,700 ppm, less than 5,200 ppm, less than 325 ppm, or less than 124 ppm. Here, the total content of impurities 2b and 4b can be [NS2O6]. 3- Measurements are taken in the form of [formula missing].

[0128] <Step 3 Method>

[0129] According to another aspect of the present invention, a method for preparing a bis(fluorosulfonyl)imide salt may include: reacting chlorosulfonyl isocyanate with chlorosulfonic acid to obtain a bis(chlorosulfonyl)imide containing at least one of the impurities H2O5NClS2 represented by chemical formula (IIa) and H3O6NS2 represented by chemical formula (IIIa); adding a chlorinating agent to the bis(chlorosulfonyl)imide to remove the impurities; obtaining a bis(fluorosulfonyl)imide ammonium salt from the bis(chlorosulfonyl)imide with the impurities removed; and obtaining a bis(fluorosulfonyl)imide salt represented by chemical formula (Ib) from the obtained bis(fluorosulfonyl)imide ammonium salt.

[0130] ...Chemical formula (IIa)

[0131] ...Chemical formula (IIIa)

[0132] ...Chemical formula (Ib)

[0133] Here, A1 can be a fluorine atom.

[0134] M2 in the above chemical formula (Ib) can be any one of NH4, Li, Na, K, Ca, Mg, Zn, Sb, Rb and Cs.

[0135] Here, the chlorinating agent can be selected from at least one compound chosen from SOCl2, SO2Cl2, COCl2, C2O2Cl2, POCl3, PCl5, SbCl3, ClSO2NCO, SO2(NCO)2, SiCl4, ICl, ICl3, S2Cl2, SCl2, PCl3, COCl2, and C6H5CCl3. However, for convenience, the following description uses Al as a fluorine atom and M2 as Li as an example. Therefore, the following description uses lithium bis(fluorosulfonyl)imide as an example of bis(fluorosulfonyl)imide salt.

[0136] The reaction temperature in the step of reacting chlorosulfonyl isocyanate (OCNSO2Cl) with chlorosulfonic acid (ClSO3H) can be above 100°C and below 150°C. Preferably, the reaction temperature can be above 125°C and below 135°C. The reaction step of chlorosulfonyl isocyanate with chlorosulfonic acid can continue until the production of carbon dioxide gas stops. This is because carbon dioxide gas is produced in the reaction step of chlorosulfonyl isocyanate with chlorosulfonic acid, so the cessation of carbon dioxide gas production can be regarded as a sign that the reaction is complete.

[0137] When chlorosulfonyl isocyanate reacts with chlorosulfonic acid, in addition to bis(chlorosulfonyl)imide, at least one of impurities 1a and 2a represented in the above reaction formula (I) may be generated. Impurity 1a may be H2O5NClS2 represented by the above chemical formula (IIa), and impurity 2a may be H3O6NS2 represented by the above chemical formula (IIIa). The content of the generated impurities H2O5NClS2 and H3O6NS2 may be greater than or equal to 10,000 ppm each or in combination.

[0138] When a chlorination reaction occurs due to the addition of a chlorinating agent, the sulfonic acid group (-SO3H) in H2O5NClS2 and H3O6NS2 can be converted into a chlorosulfonyl group (-SO2Cl), and H2O5NClS2 and H3O6NS2 can be converted into bis(chlorosulfonyl)imine.

[0139] If impurities are removed by adding a chlorinating agent to bis(chlorosulfonyl)imide, the residual impurity content in the final prepared bis(fluorosulfonyl)imide lithium salt will also be reduced.

[0140] Impurities 1b, 2b, 3b and 4b contained in the step of obtaining bis(fluorosulfonyl)imine ammonium salt can react in the step of obtaining bis(fluorosulfonyl)imine lithium salt as shown in the following reaction formula (IV) to generate impurities 1c, 2c, 3c, 4c and 5c.

[0141]

[0142] The total content of impurity 1c and impurity 3c can be less than 10,000 ppm, less than 7,100 ppm, less than 6,300 ppm, less than 289 ppm, or less than 187 ppm. Here, the total content of impurity 1c and impurity 3c can be expressed as [NS2O5F]. 2- Measurements are taken in the form of [formula missing].

[0143] Furthermore, the total content of impurities 2c, 4c, and 5c can be less than 10,000 ppm, less than 6,700 ppm, less than 5,200 ppm, less than 325 ppm, or less than 124 ppm. Here, the total content of impurities 2c, 4c, and 5c can be expressed as [NS2O6]. 3- Measurements are taken in the form of [formula missing].

[0144] <Product of Step 1>

[0145] According to one aspect of the present invention, the present invention relates to a bis(chlorosulfonyl)imide containing at least one of the impurity H2O5NClS2 represented by the following chemical formula (IIa) and the impurity H3O6NS2 represented by the following chemical formula (IIIa), wherein the content of said impurities is 10,000 ppm or less.

[0146] ...Chemical formula (IIa)

[0147] ...Chemical formula (IIIa)

[0148] Here, by adding a chlorinating agent during the preparation of bis(chlorosulfonyl)imide, the content of H2O5NClS2 can be reduced to below 10,000 ppm and the content of H3O6NS2 can be reduced to below 10,000 ppm.

[0149] Here, the chlorination reagent can be selected from SOCl2, SO2Cl2, COCl2, C2O2Cl2, POCl3, PCl5, SbCl3, ClSO2NCO, SO2(NCO)2, SiCl4, ICl, ICl3, S2Cl2, SCl2, PCl3, COCl2 and C6H5CCl3.

[0150] Conventional methods for preparing bis(chlorosulfonyl)imide may result in the presence of at least one of the impurities represented by chemical formula (IIa) and chemical formula (IIIa) above. If bis(chlorosulfonyl)imide containing these impurities is used in steps 2 to 3 of the above process, the impurities will continue to participate in subsequent reactions, thereby reducing the purity of the final product, fluorosulfonylimide salt. Therefore, in this invention, after step 1, impurities are removed using a chlorination reagent, thereby improving the purity of the final product, fluorosulfonylimide salt.

[0151] In other words, if the content of at least one of H2O5NClS2 represented by chemical formula (IIa) and H3O6NS2 represented by chemical formula (IIIa) in bis(chlorosulfonyl)imide exceeds 10,000 ppm, these impurities may adversely affect subsequent processes, leading to reduced yield and the generation of acidic impurities. The impurity content is preferably below 10,000 ppm, with a lower limit of about 1 ppm.

[0152] <Product of Step 2>

[0153] According to another aspect of the invention, the invention can provide a fluorosulfonamide represented by chemical formula (Ia) containing an impurity represented by the following chemical formula (IIb): [NS₂O₅F]. 2- And the impurity represented by the following chemical formula (IIIb): [NS2O6] 3- At least one of the following, wherein [NS2O5F] is obtained by adding a chlorinating agent during the preparation process. 2- The content is below 10,000 ppm, [NS2O6] 3- The content is below 10,000 ppm.

[0154] ...Chemical formula (Ia)

[0155] ...Chemical formula (IIb)

[0156] ...Chemical formula (IIIb)

[0157] Here, M1 is H, and A1 is a 1-6 carbon alkyl group in which one or more hydrogen atoms are replaced by fluorine atoms.

[0158] In addition, [NS2O5F] 2- The content can be below 7,100 ppm, [NS2O6] 3- The content can be below 6,700 ppm.

[0159] In addition, the added chlorination reagent can be selected from SOCl2, SO2Cl2, COCl2, C2O2Cl2, POCl3, PCl5, SbCl3, ClSO2NCO, SO2(NCO)2, SiCl4, ICl, ICl3, S2Cl2, SCl2, PCl3, COCl2 and C6H5CCl3.

[0160] According to another embodiment of the present invention, the present invention can provide a fluorosulfonyl imide salt represented by chemical formula (Ia) containing an impurity represented by the following chemical formula (IIb): [NS₂O₅F]2- And the impurity represented by the following chemical formula (IIIb): [NS2O6] 3- At least one of the following, wherein [NS2O5F] is obtained by adding a chlorinating agent during the preparation process. 2- The content is below 10,000 ppm, [NS2O6] 3- The content is below 10,000 ppm.

[0161] ...Chemical formula (Ia)

[0162] ...Chemical formula (IIb)

[0163] ...Chemical formula (IIIb)

[0164] Here, A1 is an alkyl group with 1-6 carbon atoms in which one or more hydrogen atoms are replaced by fluorine atoms, and M1 is any one of NH4, Li, Na, K, Ca, Mg, Zn, Sb, Rb and Cs.

[0165] In addition, [NS2O5F] 2- The content can be below 7,100 ppm, [NS2O6] 3- The content can be below 6,700 ppm.

[0166] In addition, the added chlorination reagent can be selected from SOCl2, SO2Cl2, COCl2, C2O2Cl2, POCl3, PCl5, SbCl3, ClSO2NCO, SO2(NCO)2, SiCl4, ICl, ICl3, S2Cl2, SCl2, PCl3, COCl2 and C6H5CCl3.

[0167] <Product of Step 3>

[0168] A fluorosulfonyl imide salt represented by the following chemical formula (Ib) contains an impurity represented by the following chemical formula (IIb): [NS₂O₅F] 2- And the impurity represented by the following chemical formula (IIIb): [NS2O6] 3- At least one of the following, wherein [NS2O5F] 2- The content is below 10,000 ppm, [NS2O6] 3- The content is below 10,000 ppm.

[0169] ...Chemical formula (Ib)

[0170] ...Chemical formula (IIb)

[0171] ...Chemical formula (IIIb)

[0172] Here, M2 is any one of Li, Na, K, Ca, Mg, Zn, Sb, Rb, and Cs.

[0173] In the above chemical formula (Ib), A1 represents a hydrocarbon group with 1-6 carbon atoms in which one or more hydrogen atoms are replaced by fluorine atoms. The hydrocarbon group is preferably a straight-chain fluoroalkyl group with 1-6 carbon atoms. Examples of such groups include fluoromethyl, difluoromethyl, trifluoromethyl, fluoroethyl, difluoroethyl, trifluoroethyl, pentafluoroethyl, etc. Preferably, A1 is a fluorine atom, trifluoromethyl, or pentafluoroethyl. The bis(fluorosulfonyl)imine or N-(fluorosulfonyl)-N-(fluoroalkylsulfonyl)imine salts of the present invention are suitable as ion-conducting materials for various electrochemical devices. In particular, lithium fluorosulfonylimine with lithium as the cation can be used as an electrolyte or ionic liquid in lithium secondary batteries, capacitors, etc., or as an intermediate for fluorosulfonyl compounds.

[0174] Here, [NS2O5F] 2- The content can be below 7,100 ppm, below 6,300 ppm, below 289 ppm, or below 187 ppm. Furthermore, [NS2O6] 3- The content can be below 6,700 ppm, below 5,200 ppm, below 325 ppm, or below 124 ppm.

[0175] Here, the pH value of the fluorosulfonamide alkali metal salt in aqueous solution can be 6 or higher and 9 or lower. According to another embodiment, the pH value can be 6.9 or higher and 7.1 or lower.

[0176] Here, when the fluorosulfonyl imide salt is an alkali metal salt of fluorosulfonyl imide, the impurity represented by the following chemical formula (IIb) [NS₂O₅F] can be suppressed. 2- And the impurity represented by chemical formula (IIIb) [NS2O6]. 3- The content of is such that the fluorosulfonamide alkali metal salt does not exhibit acidity in the aqueous phase.

[0177] <Electrolytes containing the product of step 3>

[0178] According to another aspect of the invention, the invention may include an electrolyte containing a fluorosulfonylimide salt. For example, the fluorosulfonylimide salt may be lithium bis(fluorosulfonyl)imide. In the fluorosulfonylimide salt, [NS₂O₅F] 2- The content can be below 7100 ppm, [NS2O6] 3-The content can be below 6700 ppm.

[0179] Impurity [NS2O5F] 2- and [NS2O6] 3- The content of [NS₂O₅F] can be measured by ion chromatography. Ion chromatography is used to assess the types and contents of anions and cations, and is suitable for measuring ionizable [NS₂O₅F]. 2- and [NS2O6] 3- The existence and content of.

[0180] Electrochemical devices (e.g., batteries) that contain the product of step 4.

[0181] According to another aspect of the invention, the invention can be an electrochemical device comprising the above-described electrolyte.

[0182] Electrochemical devices using the electrolyte described in this invention (e.g., lithium secondary batteries) suffer from impurities [NS2O5F]. 2- and [NS2O6] 3- The reduced content of electrolytes and additives can prevent the decomposition of electrolytes and additives, as well as the corrosion of the current collector.

[0183] The following specific test examples and comparative examples illustrate the superiority and inventiveness of the present invention. However, it should be understood that the present invention is not limited to the embodiments described below.

[0184] [Test Implementation Example]

[0185] [Example 1]

[0186] (Step 1 Reaction) Slowly add 25.8 g of chlorosulfonic acid (ClSO3H) to 30 g of chlorosulfonyl isocyanate (OCNSO2Cl), and then stir with a magnetic stirrer. Heat the stirred solution from room temperature to 130°C and react for 20 hours. The progress of the reaction can be judged by whether CO2 gas is produced. Specifically, if no more CO2 gas is produced, the reaction is considered complete. Then, add 2.52 g of thionyl chloride (SOCl2) and react thoroughly until no more SO2 gas is produced. After the reaction is complete, 44.92 g of a yellow liquid bis(chlorosulfonyl)imide (HCSI) (yield: 99%) is obtained.

[0187] (Step 2) 120 g of butyl acetate was added to 20.76 g of ammonium fluoride (NH4F), cooled to below -5°C, and stirred with a magnetic stirrer. Next, 30 g of bis(chlorosulfonyl)imide (HCSI) obtained in Step 1 was slowly added dropwise. Heat was generated at this point, so the mixture was stirred at 15°C for about 1 hour to stabilize the reaction. After heat generation ceased, the reaction temperature was increased to 80°C at a rate of 1°C per minute, and the reaction continued for 5 hours. After the reaction was complete, the mixture was cooled to 25°C, filtered to remove solid impurities, and the filtrate was concentrated. Then, 90 g of the nonpolar solvent toluene was added for recrystallization. Recrystallization yielded 23.05 g of a white crystalline solid bis(fluorosulfonyl)imide ammonium salt (NH4FSI) (yield: 83%).

[0188] (Step 3) Add 30g of isopropyl ether to 20g of the bis(fluorosulfonyl)imide ammonium salt (NH4FSI) obtained in Step 2 above, and stir with a magnetic stirrer at 25°C. Next, add 5.08g of lithium hydroxide (LiOH·H2O), and react at room temperature for 3 hours. Here, the reaction can be considered complete when the production of NH3 gas stops. After the reaction is complete, cool to room temperature, filter to remove solid impurities, concentrate the filtrate, and then add the nonpolar solvent 1,2-dichloroethane (EDC) for recrystallization. By recrystallization, 17.18g of white crystalline solid bis(fluorosulfonyl)imide lithium (LiFSI) (yield: 91%) is obtained.

[0189] (Measurement) The purity, impurity type and impurity content of lithium bis(fluorosulfonyl)imide obtained in step 3 of Example 1 were measured using ion chromatography.

[0190] [Example 2]

[0191] (Step 1 Reaction) 25.8 g of chlorosulfonic acid (ClSO3H) was slowly added to 30 g of chlorosulfonyl isocyanate (OCNSO2Cl), and the mixture was stirred with a magnetic stirrer. The reaction temperature was raised from room temperature to 130°C, and the mixture was reacted for 20 hours. The reaction was continued until no more CO2 gas was produced. Next, 2.09 g of phosgene (COCl2) was added, and the reaction was allowed to proceed until no more CO2 gas was produced. After the reaction was complete, 44.90 g of a yellow liquid bis(chlorosulfonyl)imide (HCSI) was obtained (yield: 99%).

[0192] (Step 2 reaction) The bis(chlorosulfonyl)imide obtained in step 1 reaction was reacted in the same manner as in step 2 reaction of Example 1 to prepare bis(fluorosulfonyl)imide ammonium salt (yield: 83%).

[0193] (Step 3 reaction) The bis(fluorosulfonyl)imine ammonium salt obtained in step 2 reaction was reacted in the same manner as in step 3 reaction of Example 1 to prepare bis(fluorosulfonyl)imine lithium (yield: 92%).

[0194] (Measurement) The purity, impurity type and impurity content of lithium bis(fluorosulfonyl)imide obtained in step 3 of Example 2 were measured using ion chromatography.

[0195] [Example 3]

[0196] (Step 1 Reaction) Slowly add 25.8 g of chlorosulfonic acid (ClSO3H) to 30 g of chlorosulfonyl isocyanate (OCNSO2Cl), and then stir the mixture with a magnetic stirrer. Raise the reaction temperature from room temperature to 130°C, and react the mixture for 20 hours. Continue the reaction until no more CO2 gas is produced. Next, add 2.86 g of sulfonyl chloride (SO2Cl2), and react thoroughly until no more SO3 gas is produced. After the reaction is complete, 44.45 g of yellow liquid bis(chlorosulfonyl)imine (HCSI) (yield: 98%) is obtained.

[0197] (Step 2 reaction) The bis(chlorosulfonyl)imide obtained in step 1 reaction was reacted in the same manner as in step 2 reaction of Example 1 to prepare bis(fluorosulfonyl)imide ammonium salt (yield: 85%).

[0198] (Step 3 reaction) The bis(fluorosulfonyl)imine ammonium salt obtained in step 2 reaction was reacted in the same manner as in step 3 reaction of Example 1 to prepare bis(fluorosulfonyl)imine lithium (yield: 92%).

[0199] (Measurement) The purity, impurity type and impurity content of lithium bis(fluorosulfonyl)imide obtained in step 3 of Example 2 were measured using ion chromatography.

[0200] [Example 4]

[0201] (Step 1 Reaction) Slowly add 25.8 g of chlorosulfonic acid (ClSO3H) to 30 g of chlorosulfonyl isocyanate (OCNSO2Cl), and then stir the mixture with a magnetic stirrer. Raise the reaction temperature from room temperature to 130°C, and react the mixture for 20 hours. Continue the reaction until no more CO2 gas is produced. Next, add 2.69 g of oxalyl chloride (C2O2Cl2), and react thoroughly until no more CO2 and CO gas are produced. After the reaction is complete, 44.89 g of yellow liquid bis(chlorosulfonyl)imine (HCSI) (yield: 99%) is obtained.

[0202] (Step 2 reaction) The bis(chlorosulfonyl)imide obtained in step 1 reaction was reacted in the same manner as in step 2 reaction of Example 1 to prepare bis(fluorosulfonyl)imide ammonium salt (yield: 84%).

[0203] (Step 3 reaction) The bis(fluorosulfonyl)imine ammonium salt obtained in step 2 reaction was reacted in the same manner as in step 3 reaction of Example 1 to prepare bis(fluorosulfonyl)imine lithium (yield: 93%).

[0204] (Measurement) The purity, impurity type and impurity content of lithium bis(fluorosulfonyl)imide obtained in step 3 of Example 4 were measured using ion chromatography.

[0205] [Comparative Example]

[0206] (Step 1) Slowly add 25.8 g of chlorosulfonic acid (ClSO3H) to 30 g of chlorosulfonyl isocyanate (OCNSO2Cl), and then stir the mixture with a magnetic stirrer. Increase the reaction temperature from room temperature to 130 °C, and react the mixture for 24 hours until no more CO2 gas is produced. After the reaction is complete, 43.09 g of a yellow liquid bis(chlorosulfonyl)imide (HCSI) (yield: 95%) is obtained.

[0207] (Step 2) 120 g of butyl acetate was added to 20.76 g of ammonium fluoride (NH4F), cooled to below -5°C, and stirred with a magnetic stirrer. Next, 30 g of bis(chlorosulfonyl)imide (HCSI) was slowly added dropwise. Heat was generated at this point, so the mixture was stirred at 15°C for about 1 hour to stabilize the reaction. After heat generation ceased, the reaction temperature was raised to 80°C, and the reaction continued for 5 hours. After the reaction was complete, the mixture was cooled to 25°C, filtered to remove solid impurities, and the filtrate was concentrated. Then, 90 g of the nonpolar solvent toluene was added for recrystallization. Recrystallization yielded 20.27 g of a white crystalline solid bis(fluorosulfonyl)imide ammonium salt (NH4FSI) (yield: 73%).

[0208] (Step 3) To 20g of the bis(fluorosulfonyl)imide ammonium salt (NH4FSI) obtained in Step 2 above, 30g of isopropyl ether was added, and the mixture was stirred with a magnetic stirrer at 25°C. Next, 5.08g of lithium hydroxide hydrate (LiOH·H2O) was added, and the reaction was carried out at 25°C for 3 hours. Here, the reaction can be considered complete when the production of NH3 gas stops. After the reaction is complete, the mixture was cooled to 25°C, filtered to remove solid impurities, the filtrate was concentrated, and then recrystallized in the nonpolar solvent 1,2-dichloroethane (EDC). By recrystallization, 16.04g of white crystalline solid bis(fluorosulfonyl)imide lithium (LiFSI) was obtained (yield: 85%).

[0209] [result]

[0210] The impurity content of lithium bis(fluorosulfonyl)imide (LiFSI) obtained in Examples 1 to 4 and the Comparative Examples was measured using ion chromatography. The measurement results are shown in Table 1 below.

[0211] [Table 1]

[0212]

[0213] In addition, the purity and pH value of lithium bis(fluorosulfonyl)imide (LiFSI) obtained in Examples 1 to 4 and the Comparative Example were measured. The measurement results are shown in Table 2 below.

[0214] [Table 2]

[0215]

[0216] According to Table 2 above, in Examples 1 to 4 where chlorine substitution was performed using a chlorinating agent, compared to the comparative example where no chlorinating agent was used, the impurity [NS2O5F] that could potentially cause internal corrosion of the battery was [missing information]. 2- and [NS2O6] 3- The content of [unspecified substance] was better suppressed. Furthermore, pH measurements of 6.9 to 7.0 indicate that it is in a neutral state. This indicates that the lithium bis(fluorosulfonyl)imide of the present invention can suppress battery corrosion when used as a lithium salt for batteries. Furthermore, it was confirmed that in Examples 1 to 4, where chlorination was carried out by a chlorinating agent, the yield of each reaction step was improved compared to the comparative example without the use of a chlorinating agent. According to the embodiments of the present invention, the reaction yield of step 1 in Examples 1 to 4 reached a high value of 98% to 99%, while the comparative example had a relatively low yield of 95% due to the generation of impurities.

[0217] The reaction yields for step 2 in Table 2 are calculated based on the number of molecules of bis(chlorosulfonyl)imide added in step 2 relative to the number of bis(fluorosulfonyl)imide ammonium salts produced in each example and comparative example. The reaction yields for step 2 in Examples 1 to 4 were 83% to 85%, while the reaction yield for step 2 in Comparative Example 1 was 73%. This is presumably because impurities interfered with the reaction between bis(chlorosulfonyl)imide and ammonium fluoride, and reacted directly with ammonium fluoride to produce other impurities.

[0218] The reaction yields in Step 3 of Table 2 are calculated based on the number of molecules of bis(fluorosulfonyl)imide ammonium salt added in Step 3 of each Example and Comparative Example relative to the number of molecules of bis(fluorosulfonyl)imide lithium salt produced. The reaction yields in Step 3 of Examples 1 to 4 were 91% to 93%, while the reaction yield in Step 3 of the Comparative Examples was 85%. This is presumably because the impurities added together in Step 3 of the Comparative Examples interfered with the reaction between the bis(fluorosulfonyl)imide ammonium salt and lithium hydroxide, and reacted directly with lithium hydroxide, generating impurities in the final step.

[0219] Table 2 above shows the purity of the final bis(fluorosulfonyl)imide lithium salt, measured based on the fluorosulfonylimide ion. Examples 1 to 4 achieved high purity values ​​of 99.5% to 99.7%, while the comparative examples had relatively low purity of 98.4%. Such low purity may pose a risk of degraded battery performance.

[0220] The preferred embodiments of the present invention provided above are merely illustrative disclosures. It should be understood that those skilled in the art can make various modifications, alterations, and additions without departing from the spirit and scope of the present invention, and such modifications, alterations, and additions are included within the scope of the following claims.

Claims

1. A bis(chlorosulfonyl)imide containing at least one of the following impurities: H₂O₅NClS₂ represented by chemical formula (IIa) in an amount of less than 10,000 ppm and H₃O₆NS₂ represented by chemical formula (IIIa) in an amount of less than 10,000 ppm. ...Chemical formula (IIa) ... Chemical formula (IIIa).

2. The bis(chlorosulfonyl)imide according to claim 1, wherein, In the preparation of the bis(chlorosulfonyl)imide, a chlorinating agent is added so that the content of H2O5NClS2 is less than 10,000 ppm and the content of H3O6NS2 is less than 10,000 ppm.

3. The bis(chlorosulfonyl)imide according to claim 2, wherein the content of H2O5NClS2 is less than 7,100 ppm and the content of H3O6NS2 is less than 6,700 ppm.

4. The bis(chlorosulfonyl)imide according to claim 2, wherein, The chlorination reagent comprises at least one compound selected from SOCl2, SO2Cl2, COCl2, C2O2Cl2, POCl3, PCl5, SbCl3, ClSO2NCO, SO2(NCO)2, SiCl4, ICl, ICl3, S2Cl2, SCl2, PCl3, COCl2, and C6H5CCl3.

5. A fluorosulfonylimide represented by the following chemical formula (Ia), containing the impurity [NS₂O₅F] represented by the following chemical formula (IIb). 2- And the impurity represented by the following chemical formula (IIIb): [NS2O6] 3- At least one of the following: ...Chemical formula (Ia) ...Chemical formula (IIb) ...Chemical formula (IIIb) in, In the above chemical formula (Ia), M1 is H, and A1 is a fluorine atom, or an alkyl group with 1-6 carbon atoms in which one or more hydrogen atoms are replaced by fluorine atoms. The [NS2O5F] is prepared by adding a chlorinating agent during the preparation process. 2- The content of [NS2O6] is below 10,000 ppm, and the [NS2O6] content is... 3- The content is below 10,000 ppm.

6. The fluorosulfonamide according to claim 5, wherein the [NS2O5F] 2- The content of [NS2O6] is below 7,100 ppm. 3- The content is below 6,700 ppm.

7. A fluorosulfonyl imide salt represented by the following chemical formula (Ia), containing the impurity [NS₂O₅F] represented by the following chemical formula (IIb). 2- And the impurity represented by the following chemical formula (IIIb): [NS2O6] 3- At least one of the following: ...Chemical formula (Ia) ...Chemical formula (IIb) ...Chemical formula (IIIb) in, In the above chemical formula (Ia), M1 can be any one of NH4, Li, Na, K, Ca, Mg, Zn, Sb, Rb, and Cs. A1 is an alkyl group with 1-6 carbon atoms, in which one or more hydrogen atoms are replaced by fluorine atoms. The [NS2O5F] is prepared by adding a chlorinating agent during the preparation process. 2- The content of [NS2O6] is below 10,000 ppm, and the [NS2O6] content is... 3- The content is below 10,000 ppm.

8. The fluorosulfonyl imide salt according to claim 7, wherein, The [NS2O5F] 2- The content of [NS2O6] is below 7,100 ppm. 3- The content is below 6,700 ppm.

9. A fluorosulfonyl imide salt represented by the following chemical formula (Ib), containing the impurity [NS₂O₅F] represented by the following chemical formula (IIb). 2- And the impurity represented by the following chemical formula (IIIb): [NS2O6] 3- At least one of the following: ...Chemical formula (Ib) ...Chemical formula (IIb) ...Chemical formula (IIIb) in, In the above chemical formula (Ib), M2 is any one of Li, Na, K, Ca, Mg, Zn, Sb, Rb, and Cs, and A1 is an alkyl group having 1-6 carbon atoms, or one or more hydrogen atoms replaced by fluorine atoms. The [NS2O5F] mentioned above 2- The content of [NS2O6] is below 10,000 ppm. 3- The content is below 10,000 ppm.

10. The fluorosulfonyl imide salt represented by chemical formula (Ib) according to claim 9, wherein, The [NS2O5F] 2- The content of [NS2O6] is below 7,100 ppm. 3- The content is below 6,700 ppm.

11. The fluorosulfonyl imide salt represented by chemical formula (Ib) according to claim 10, wherein, The [NS2O5F] 2- The content of [NS2O6] is below 6,300 ppm. 3- The content is below 5,200 ppm.

12. The fluorosulfonyl imide salt represented by chemical formula (Ib) according to claim 11, wherein, The [NS2O5F] 2- The content of [NS2O6] is below 289 ppm. 3- The content is below 325 ppm.

13. The fluorosulfonylimide salt represented by chemical formula (Ib) according to claim 12, wherein, The [NS2O5F] 2- The content of [NS2O6] is below 187 ppm. 3- The content is below 124 ppm.

14. The fluorosulfonamide salt according to claim 9, wherein the pH value in aqueous solution is 6 or higher and 9 or lower.

15. An electrolyte comprising the fluorosulfonamide or fluorosulfonamide salt as described in any one of claims 5 to 14.

16. An electrochemical device comprising the electrolyte of claim 15.

17. A method for preparing bis(chlorosulfonyl)imide, the method comprising: Reaction of chlorosulfonyl isocyanate with chlorosulfonic acid; and Add a chlorinating agent to the reaction product.

18. The method for preparing bis(chlorosulfonyl)imide according to claim 17, wherein, The reaction product contains at least one of the following chemical formulas: H2O5NClS2 (represented by formula (IIa) and H3O6NS2 (represented by formula (IIIa)). ...Chemical formula (IIa) ...Chemical formula (IIIa) The addition of the chlorinating agent includes removing impurities contained in the reaction product.

19. The method for preparing bis(chlorosulfonyl)imide according to claim 18, wherein, By removing impurities, the residual H2O5NClS2 content in the bis(chlorosulfonyl)imide is less than 10,000 ppm, and the residual H3O6NS2 content is less than 10,000 ppm.

20. The method for preparing bis(chlorosulfonyl)imide according to claim 19, wherein, By removing impurities, the residual H2O5NClS2 content in the bis(chlorosulfonyl)imide is less than 7,100 ppm, and the residual H3O6NS2 content is less than 6,700 ppm.

21. The method for preparing bis(chlorosulfonyl)imide according to claim 17, wherein, The chlorination reagent comprises at least one compound selected from SOCl2, SO2Cl2, COCl2, C2O2Cl2, POCl3, PCl5, SbCl3, ClSO2NCO, SO2(NCO)2, SiCl4, ICl, ICl3, S2Cl2, SCl2, PCl3, COCl2, and C6H5CCl3.

22. A method for preparing a fluorosulfonylimide salt represented by the following chemical formula (Ia): ...Chemical formula (Ia) in, In the above chemical formula (Ia), M1 is any one of NH4, Li, Na, K, Ca, Mg, Zn, Sb, Rb, and Cs, and A1 is a fluorine atom. The method includes: By reacting chlorosulfonyl isocyanate with chlorosulfonic acid, a bis(chlorosulfonyl)imide containing at least one of the impurities H2O5NClS2 and H3O6NS2 is obtained. A chlorinating agent is added to the bis(chlorosulfonyl)imide to remove the impurities; and Butyl acetate was added to the fluorinated compound and stirred, and then the bis(chlorosulfonyl)imide, which had been purified of impurities, was added.

23. A method for preparing a bis(fluorosulfonyl)imide salt, the method comprising: By reacting chlorosulfonyl isocyanate with chlorosulfonic acid, a bis(chlorosulfonyl)imide containing at least one of the following chemical formulas (IIa) H2O5NClS2 and (IIIa) H3O6NS2 is obtained. A chlorinating agent is added to the bis(chlorosulfonyl)imide to remove the impurities; From the bis(chlorosulfonyl)imide after impurities have been removed, bis(fluorosulfonyl)imide ammonium salt is obtained, and The bis(fluorosulfonyl)imide ammonium salt obtained yields the bis(fluorosulfonyl)imide salt represented by the following chemical formula (Ib). ...Chemical formula (IIa) ...Chemical formula (IIIa) ...Chemical formula (Ib) In the above chemical formula (Ib), M2 can be any one of Li, Na, K, Ca, Mg, Zn, Sb, Rb, and Cs. A1 is a fluorine atom.

24. The method for preparing bis(fluorosulfonyl)imide salt according to claim 23, wherein, The obtained bis(fluorosulfonyl)imide salt contains an impurity represented by the following chemical formula (IIb): [NS₂O₅F] 2- And the impurity represented by the following chemical formula (IIIb): [NS2O6] 3- At least one of the following: ...Chemical formula (IIb); ...Chemical formula (IIIb) The [NS2O5F] mentioned above 2- The content of [NS2O6] is below 10,000 ppm. 3- The content is below 10,000 ppm.

25. The method for preparing bis(fluorosulfonyl)imide salt according to claim 24, wherein, The [NS2O5F] 2- The content of [NS2O6] is below 7,100 ppm. 3- The content is below 6,700 ppm.

26. The method for preparing bis(fluorosulfonyl)imide salt according to claim 23, wherein, The bis(fluorosulfonyl)imide salt has a pH value of 6 or higher and 9 or lower in aqueous solution.

27. The method for preparing bis(fluorosulfonyl)imide salt according to claim 23, wherein, The chlorination reagent is at least one compound selected from SOCl2, SO2Cl2, COCl2, C2O2Cl2, POCl3, PCl5, SbCl3, ClSO2NCO, SO2(NCO)2, SiCl4, ICl, ICl3, S2Cl2, SCl2, PCl3, COCl2 and C6H5CCl3.

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