Process for production of alkaline sulfimide salts

Abstract

The present invention relates to a process for the production of a salt of bis (chlorosulfonyl) imine (HSCI salt), which process is economically viable on an industrial scale and provides a high purity product. The invention also provides a process for the production of a lithium salt of bis (fluorosulfonyl) imide (LiFSI), wherein the HSCI salt is used as an intermediate compound.

Description

[0001] Cross-references to related patent applications

[0002] This application claims priority from European application number 22306391.8 filed on September 22, 2022, the entire contents of which are incorporated herein by reference for all purposes. Technical Field

[0003] The present invention relates to a method for producing a salt of bis(chlorosulfonyl)imide, which is economically feasible on an industrial scale and provides a high-purity product. The present invention also provides a method for producing a lithium salt of bis(fluorosulfonyl)imide (LiFSI), wherein the HCSI salt is used as an intermediate compound. Background Art

[0004] Fluorosulfonyl imide salts, in particular lithium salts of bis(fluorosulfonyl)imide (LiFSI) are useful compounds for battery electrolytes. Different processes, reactants and intermediates for producing LiFSI have been described in the patent literature. Patent CA 2 527802 (in the name of the University of Montreal) lists several routes for preparing LiFSI, such as a method for preparing LiFSI in one step starting from bis(chlorosulfonyl)imide (HCSI) using anhydrous hydrogen fluoride (HF):

[0005]

[0006] Also, KR 20190001092 (in the name of LIM KWANG MIN) discloses a method for manufacturing lithium bis(fluorosulfonyl)imide (LiFSI), the method comprising reacting a lithiating agent, a solvent, and bis(chlorosulfonyl)imide (HCSI) and a fluorinating agent.

[0007] Alternative known methods for preparing LiFSI include a two-step process. For example, one alternative is to fluorinate bis(chlorosulfonyl)imide (HCSI) to bis(fluorosulfonyl)imide (HFSI) using a fluorinating agent such as anhydrous hydrogen fluoride (HF), and then lithiate HFSI to LiFSI using a lithiating agent.

[0008] Another known two-step method for preparing LiFSI involves using NH4F(HF) x The first step of fluorinating bis(chlorosulfonyl)imide (HCSI) as a fluorinating agent to ammonium bis(fluorosulfonyl)imide (NH4FSI) is followed by a second step of lithiating NH4FSI to obtain the LiFSI product.

[0009] Another known two-step method for preparing LiFSI includes lithiating HCSI using a lithiating agent in a first step to prepare LiCSI as an intermediate product, and then fluorinating LiCSI into LiFSI using a fluorinating agent.

[0010] For example, KR 20200049164 (in the name of CLS LABORATORIES INC.) discloses a method for preparing LIFSI, which includes reacting HCSI with a lithiation agent in a (S1) solvent to produce LiCSI as an intermediate product, which is not purified / isolated but directly reacted with an anhydrous fluorination agent without purification. After obtaining lithium bis(fluorosulfonyl)imide, it is then filtered and concentrated, and then the solvent is completely removed using a thin film distiller at low temperature, thereby obtaining a crystalline powder. In this method, a single solvent is used for the reaction, and no additional crystallization or recrystallization process is performed.

[0011] Moreover, CN 103524387 (in the name of China National Offshore Oil Corp.) discloses a preparation method for LiFSI, which includes: (I) reacting aminosulfonic acid and chlorosulfonic acid in a thionyl chloride solvent to prepare HCSI, (II) adding LiCl and removing the thionyl chloride solvent to obtain LiCSI, (III) adding acetonitrile or butyl acetate, and then adding ZnF and filtering to obtain a filtrate containing LiFSI salt, (IV) recrystallizing in methyl chloride to obtain a solid and drying.

[0012] Other methods for the lithiation of HCSI have been disclosed, for example, in WO 02 / 053494 (in the name of Rhodia Chimie, Hydro-Quebec). Summary of the invention

[0013] The applicants believe that there remains a need in the art for improved methods for making intermediate compounds used in the manufacture of LiFSI.

[0014] More specifically, the technical problem faced by the Applicant is to provide a method for producing LiCSI with a low content of impurities so that it can be used for the production of LiFSI.

[0015] Furthermore, the Applicant faced the problem of providing a process characterized by a high productivity using conditions suitable for manufacture on an industrial scale. DETAILED DESCRIPTION

[0016] In this application:

[0017] - Unless otherwise indicated, the numerical ranges disclosed below are to be understood as including the limit values;

[0018] - any description (even those relating to a specific embodiment) is applicable to and interchangeable with other embodiments of the invention;

[0019] -When an element or component is said to be included in and / or selected from a list of listed elements or components, it should be understood that in the relevant embodiments explicitly considered herein, the element or component may also be any of these listed independent elements or components, or may also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component listed in the list of elements or components may be omitted from this list.

[0020] In a first aspect, the present application relates to a method for producing a salt of bis(chlorosulfonyl)imide [CSI salt] in solid form, the method comprising:

[0021] (I) contacting at least one first solvent [solvent (S1)] with a compound conforming to formula (1):

[0022] (1)M x B

[0023] in

[0024] M is selected from lithium, sodium, potassium and ammonium;

[0025] x is 1 or 2; and

[0026] B is selected from Cl, CO3 2- 、SO4 2- , carboxylates; silicates, preferably metasilicates; borates, preferably tetraborate; and mixtures thereof; to provide a first mixture [mixture (M1)];

[0027] (II) contacting the mixture (M1) with bis(chlorosulfonyl)imide (HCSI),

[0028] so as to provide a second mixture [mixture (M2)] comprising a salt of HCSI selected from lithium-, sodium-, potassium- or ammonium-CSI [CSI salt] and at least one first solvent (S1);

[0029] (III) contacting the mixture (M2) with at least one second solvent [solvent (S2)] so as to provide a CSI salt in solid form,

[0030] The at least one second solvent (S2) forms a homogeneous mixture with the at least one first solvent (S1) and is an anti-solvent for the CSI salt.

[0031] As used within this specification and in the following claims, the expression "anti-solvent for the CSI salt" referring to the at least one second solvent (S2) is intended to indicate that the CSI salt shows a solubility lower than 2 wt.%, preferably lower than 1 wt.% in the at least one second solvent (S2).

[0032] The process of the present invention can be carried out continuously or batchwise.

[0033] For example, the process of the present invention may be stopped after step (II) to recover the CSI salt from the mixture (M2).

[0034] According to this embodiment, the method of the present invention preferably comprises a step (II-b) of separating the CSI salt from the mixture (M2) after step (II).

[0035] Preferably, when M in formula (1) is lithium, the compound is selected from those that do not generate water or soluble substances during the reaction.

[0036] Advantageously, when M in formula (1) is lithium, the compound is selected from the group consisting of lithium chloride (LiCl), lithium carbonate (Li2CO3), lithium sulfate (Li2SO4), lithium carboxylate (Li n (RCO2) n ), Li2SiO3, Li2B4O7 and mixtures thereof.

[0037] Preferably, in formula (1), M is sodium. The compound is preferably selected from the group consisting of sodium chloride (NaCl), sodium carbonate (Na2CO3), sodium sulfate (Na2SO4) and mixtures thereof.

[0038] Preferably, in formula (1), M is ammonium. The compound is preferably selected from the group consisting of ammonium chloride (NH4Cl), ammonium carbonate and mixtures thereof.

[0039] Preferably, the molar ratio of HCSI to the compound of formula (1) (when M is lithium) ranges from 1:100 to 20:1, specifically 1:10 to 10:1, more specifically 1:2 to 5:1, even more specifically 1:1 to 1:1.5.

[0040] When lithium carbonate is used as the compound of formula (1), it is advantageous that the molar ratio of HCSI to Li2CO3 is lower than 1, ie Li2CO3 is in excess. A molar ratio of 1:2 to 1:5 is even more preferred.

[0041] More preferably, the compound of formula (1) is anhydrous lithium chloride (LiCl) in solid form.

[0042] When LiCl is used as the compound having formula (1), it is advantageous that the molar ratio of HCSI to LiCl is from 1:1 to 1:1.5.

[0043] Preferably, the solvent (S1) is selected from the group consisting of carbonates, such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC); esters, such as ethyl acetate, n-butyl acetate; ethers, such as tetrahydrofuran (THF), methyl tert-butyl ether (MTBE), methyltetrahydrofuran (Me-THF). Carbonates are particularly preferred.

[0044] In any case, the solvent (S1) is different from thionyl chloride (SO2Cl).

[0045] The HCSI provided in step (II) of the process of the present invention can be produced by a known method, for example, by reacting:

[0046] -Chlorosulfonyl isocyanate (ClSO2NCO) and chlorosulfonic acid (ClSO2OH);

[0047] - cyanogen chloride (CNCl) with sulfuric anhydride (SO3) and with chlorosulfonic acid (ClSO2OH); or

[0048] -Aminosulfonic acid (NH2SO2OH) with thionyl chloride (SOCl2) and with chlorosulfonic acid (ClSO2OH).

[0049] In one embodiment, HCSI is produced by reacting chlorosulfonic acid (ClSO2OH) with chlorosulfonyl isocyanate (ClSO2NCO). According to this embodiment, step (i) comprises preparing a reaction mixture comprising crude HCSI, a heavy fraction and a light fraction in a reactor by reacting chlorosulfonyl isocyanate (ClSO2NCO) with chlorosulfonic acid (ClSO2OH).

[0050] In another embodiment, HCSI is produced by reacting sulfamic acid (NH2SO2OH), chlorosulfonic acid (ClSO2OH) and thionyl chloride (SOCl2). The sulfamic acid to be applied can be ground to a certain particle size and dried under vacuum to reduce its water content and accelerate the conversion kinetics, which significantly reduces the reaction time. When HCSI is prepared by the so-called sulfamic acid route, the sulfamic acid used can optionally be ground and dried under vacuum to reduce its water content and accelerate the conversion kinetics, thereby significantly reducing the reaction time.

[0051] In other embodiments, HCSI is produced by reacting cyanogen chloride CNCl with sulfuric anhydride (SO3) and chlorosulfonic acid (ClSO2OH).

[0052] The HCSI may be provided as a composition comprising HCSI mixed with at least one other compound. Such at least one other compound may be an undesirable compound. The undesirable compound may be selected from, for example, ions, one or more solvents, water and / or reaction byproducts. For example, the HCSI may be provided as a composition comprising 80 to 99 wt.%, preferably 85-98 wt.%, more preferably 90-97 wt.% of HCSI, the remainder to make up 100 wt.% being one or more other compounds. Such one or more other compounds will be removed by the method of the present invention.

[0053] Advantageously, HCSI is provided in step (II) in its molten form.

[0054] According to this embodiment, prior to step (II), HCSI is heated to a temperature above its melting temperature (Tm HCSI ) at a temperature of .

[0055] Although the melting temperature of HCSI is affected by the presence and amount of impurities, it is preferred to heat the HCSI at a temperature equal to or higher than 30° C., such as equal to or higher than 37° C., such as equal to or higher than 38° C., equal to or higher than 40° C., equal to or higher than 45° C., or even equal to or higher than 50° C. In any case, the heating is performed at a temperature below the degradation temperature of the HCSI.

[0056] Preferably, step (II) is carried out at a temperature of 15°C to 60°C, more preferably 20°C to 35°C.

[0057] Preferably, step (II) is carried out under atmospheric pressure.

[0058] Preferably, the at least one second solvent (S2) is selected in the group comprising: dioxane, chlorinated solvents like dichloromethane (DCM), alkanes, toluene, xylene. Dioxane is particularly preferred.

[0059] Preferably, step (III) is carried out at a temperature of 15°C to 60°C, more preferably 20°C to 35°C.

[0060] Preferably, step (III) is carried out under atmospheric pressure.

[0061] Preferably, the CSI salt obtained in solid form at the end of step (III) is in the form of a solvate with said at least one second solvent (S2).

[0062] Preferably, the process according to the invention comprises, after step (III), at least one step (IV) of separating the CSI salt from the impurities.

[0063] The separation step can be performed by any separation means known to those skilled in the art. For example, the separation can be performed by filtration (more preferably under pressure and / or under vacuum), or decantation.

[0064] The mesh size of the filter medium is preferably 100 μm or less, 50 μm or less, 10 μm or less, 2 μm or less, or 0.45 μm or less, or 0.22 μm or less.

[0065] The isolated product(s) may be washed once or several times with one or more appropriate solvents.

[0066] The separation step may be performed once or may be repeated two or more times.

[0067] Some or all of the steps of the process according to the invention are advantageously carried out in equipment capable of withstanding the corrosion of the reaction medium.

[0068] For this purpose, for the parts in contact with the reaction medium, corrosion-resistant materials are selected, such as alloys based on molybdenum, chromium, cobalt, iron, copper, manganese, titanium, zirconium, aluminum, carbon and tungsten (in the order of or alloys of nickel, chromium, iron and manganese to which copper and / or molybdenum are added (known as or Monel TM Sold), and more particularly Hastelloy C276 or Inconel 600, 625 or 718 alloys. Stainless steels, such as austenitic steels and more particularly 304, 304L, 316 or 316L stainless steels, may also be selected. Steels with a nickel content of up to 22 wt.%, preferably between 6 wt.% and 20 wt.%, and more preferably between 8 wt.% and 14 wt.% are used. 304 and 304L steels have a nickel content varying between 8 wt.% and 12 wt.%, and 316 and 316L steels have a nickel content varying between 10 wt.% and 14 wt.%. More particularly, 316L steel is selected. Equipment composed of a polymer compound resistant to corrosion by the reaction medium or equipment coated with a polymer compound resistant to corrosion by the reaction medium may also be used. Materials such as PTFE (polytetrafluoroethylene or Teflon) or PFA (perfluoroalkyl resin) may be particularly mentioned. Glass equipment can also be used, such as glass-coated alloys. The use of equivalent materials will not exceed the scope of the present invention. As other materials that can be suitable for contact with the reaction medium, graphite derivatives can also be mentioned. The material used for filtering must be compatible with the medium used. Fluorinated polymers (PTFE, PFA), supported fluorinated polymers (Viton TM ), as well as polyester (PET), polyurethane, polypropylene, polyethylene, cotton and other compatible materials.

[0069] All raw materials (including reactants) used in the process according to the invention may preferably show very high purity standards. Preferably, their content of metal components such as Na, K, Ca, Mg, Fe, Cu, Cr, Ni, Zn is less than 10ppm, more preferably less than 5ppm, or less than 2ppm.

[0070] According to the method of the present invention, a pure or substantially pure salt of LiCSI is obtained as a solid. This means that the LiCSI salt can be used as it is for other reactions, notably for the preparation of LiFSI.

[0071] In another aspect, the present invention relates to a solid solvate complex [CSI solvate] comprising a solid lithium, sodium, potassium or ammonium salt of bis(chlorosulfonyl)imide and dioxane as solvating solvent.

[0072] As used within this specification and in the following claims, the term "solvate" is intended to indicate a solid lithium, sodium, potassium or ammonium salt of bis(chlorosulfonyl)imide, also known as CSI salt, which comprises molecules of the solvent (S2) attached thereto by non-covalent bonds.

[0073] Preferably, in the CSI solvate, the weight ratio of CSI salt to solvent (S2) as measured as dry powder is in the range of 1:1 to 1:4.

[0074] Advantageously, the solvent (S2) in the CSI solvate is dioxane.

[0075] Advantageously, said CSI solvate is obtained at the end of step (III) or step (IV) of the process according to the invention.

[0076] Preferably, the CSI solvate is in crystalline form.

[0077] In a further embodiment, the present invention relates to the use of the CSI solvate as obtained at the end of step (II) or step (IV) as defined above for the manufacture of a salt of bis(fluorosulfonyl imide) [FSI salt].

[0078] Preferably, the FSI salt is selected from the group consisting of: lithium salt, ammonium salt and sodium salt.

[0079] Another object of the present invention relates to a method for preparing a salt of bis(fluorosulfonyl)imide [FSI salt], the method comprising:

[0080] (V) contacting a CSI salt or a CSI solvate as defined above with at least one fluorinating agent so as to obtain a FSI salt.

[0081] The fluorinating agent used in the method of the present invention is not limited. Preferably, it is anhydrous hydrogen fluoride (aHF). Such aHF advantageously has a high purity, for example, greater than 99.95 mol.%, having less than 1000 ppm of H2O, less than 10 ppm of SO2, less than 100 ppm of H2SO4, less than 20 ppm of H2SiF6 and less than 25 ppm of As.

[0082] When aHF is used as a fluorinating agent in step (V), it can be introduced into the reaction mixture in any form. It can be introduced as a liquid or it can be introduced into the reaction vessel as a gas. For example, step (V) can be carried out by fluorinating LiCSI using aHF gas in a fluidized bed.

[0083] According to other embodiments, the fluorinating agent is selected from the group comprising, preferably consisting of:

[0084] (i) KF(HF) p Where p is 0 or 1;

[0085] (ii) NaF(HF) p Where p is 0 or 1;

[0086] (iii)X2F(HF) p wherein X2 is an onium cation, and p is 0 or 1;

[0087] (iv) NH4F(HF) p Where p varies between 0 and 10;

[0088] (v) LiF;

[0089] (vi) ZnF2.

[0090] According to a preferred embodiment, specific examples of the fluorinating agent (iv) include NH4F, NH4F.HF, NH4F.2HF, NH4F.3HF and NH4F.4HF.

[0091] A preferred fluorinating agent (iv) is NH4F.

[0092] In the present invention, the fluorinating agent used in step (V) is preferably anhydrous. The moisture content may preferably be less than 100 ppm, less than 50 ppm or even less than 10 ppm. A skilled person may determine the most appropriate method to determine this moisture content. For example, such methods may include infrared techniques or Karl Fischer titration (where appropriate).

[0093] In some embodiments, the stoichiometric amount (also referred to as molar amount) of the fluorinating agent to the CSI salt in solid form is 0.1:1 to 50:1, eg, 1:1 to 10:1, or 2:1 to 8:1.

[0094] In some embodiments, the stoichiometric amount of the fluorinating agent is not less than 2 equivalents per 1 mol of CSI salt (preferably LiCSI), for example, between 2 and 100 equivalents per 1 mol of CSI salt (preferably LiCSI). Preferably, the stoichiometric amount of the fluorinating agent is between 2 and 80 equivalents per 1 mol of CSI salt (preferably LiCSI), or between 2 and 60 equivalents per 1 mol of CSI salt (preferably LiCSI). More preferably, the stoichiometric amount of the fluorinating agent is between 2 and 50 equivalents per 1 mol of CSI salt (preferably LiCSI).

[0095] Preferably, step (V) is carried out in the presence of a solvent.

[0096] Advantageously, when the CSI salt in solid form is a solvate with dioxane, the solvent is preferably dioxane.

[0097] Preferably, step (V) is carried out at a temperature of 25°C to 90°C, more preferably 40°C to 90°C.

[0098] Preferably, step (V) is carried out at a pressure of 1 to 2 bar.

[0099] Any relevant method such as evaporation under vacuum or stripping using an inert gas or a combination thereof can be used to eliminate the residual HF present in the final reaction crude.

[0100] LiFSI as obtained with the process of the present invention advantageously exhibits at least one, or even more preferably all, of the following:

[0101] - As through 19 A purity of at least 98 wt.%, e.g., between 99 wt.% and 100 wt.% or between 99.50% and 100% as determined by F NMR;

[0102] - a solvent content of less than 20 wt.%, less than 10 wt.%, less than 1 wt.%, preferably between 0 wt.% and 1 wt.% as determined by GC;

[0103] - A moisture content of less than 500 ppm, less than 100 ppm, less than 50 ppm or even less than 20 ppm as determined by infrared methods.

[0104] The LiFSI of the present invention advantageously exhibits at least one of the following features, and preferably exhibits all of the following features:

[0105] - less than 100 ppm, preferably less than 50 ppm, more preferably less than 10 ppm, or more preferably less than 2 ppm of chloride ions (Cl - )content;

[0106] - less than 100 ppm, preferably less than 50 ppm, more preferably less than 40 ppm, more preferably less than 30 ppm, more preferably less than 20 ppm of fluoride ions (F - ) content; and - less than 100ppm, preferably less than 50ppm, more preferably less than 10ppm, or more preferably less than 2ppm sulfate (SO4 2- )content.

[0107] Fluoride and chloride content can be measured by means of titration via silver salts using an ion selective electrode (or ISE). Sulfate content can be measured by ion chromatography

[0108] - or by turbidimetry.

[0109] Advantageously, lithium bis(fluorosulfonyl)imide (LiFSI) prepared according to the method of the present invention can be used in an electrolyte composition of an electrochemical cell.

[0110] In a further aspect, the present invention relates to an electrolyte composition comprising LiFSI as obtained by the method of the present invention. Advantageously, the electrolyte composition is a non-aqueous electrolyte composition.

[0111] Should the disclosure of any patents, patent applications, and publications incorporated herein by reference conflict with the description of the present application to the extent that it renders a term unclear, the present description shall take precedence.

[0112] The present invention will be illustrated by the following examples which are intended to be illustrative rather than limiting of the present invention.

[0113] Experimental Section

[0114] Material

[0115] The following were purchased from Merck: anhydrous lithium chloride (99% - #793620); carbon tetrachloride (CCl4->99.9% - #270652); dimethyl carbonate, diethyl carbonate (DEC-99% - #D91551).

[0116] The following were purchased from VWR: dichloromethane (DCM-#25631.293); dioxane (VWR#23532.297->99%).

[0117] HCSI was prepared in-house starting from chlorosulfonyl isocyanate and chlorosulfonic acid and was then used in its molten state.

[0118] method

[0119] All solvents used in the following examples (DCM, CCl4, DEC, DMC, dioxane) were dried over molecular sieves before use.

[0120] Comparative Example A1 - Preparation of LiCSI Solution by Lithiation of HCSI Using CCl4 as Solvent

[0121] A double-jacketed 100 mL glass reactor equipped with integrated baffles, mechanical stirring, condenser and connected to a 15 wt.% aqueous KOH scrubber was flushed with argon for 30 minutes.The reactor vessel was charged with 3.18 g of anhydrous lithium chloride and 24.7 g of carbon tetrachloride.

[0122] In a glove box, a dropping funnel was filled with 26 g CCl4 and 20.0 g molten HCSI. The funnel was connected to the reactor.

[0123] The temperature setting of the condenser was fixed at 6°C and the stirring rate was fixed at 700 rpm, and then the HCSI solution was introduced over 20 min. The reaction medium was heated to reflux. After 5 hours of reflux, the LiCl conversion was about 19% (estimated by KCl titration in the scrubber).

[0124] The reflux was extended for 60 h, supplementing with CCl4 to correct for solvent loss. The slurry was filtered, washed with 20 mL CCl4, and dried under argon to obtain a light brown powder (8.3 g).

[0125] Proton NMR of the filtrate diluted in CDCl3 showed the presence of HCSI, and titration of chloride ions in the solid indicated that the remaining LiCl in the LiCSI was 6 wt.%.

[0126] Overall, the reaction rate was considered too slow.

[0127] Example A2 - Preparation of LiCSI solution by lithiation of HCSI using DEC as solvent

[0128] A double-jacketed 250 mL glass reactor equipped with integrated baffles, mechanical stirring, condenser, bottom valve and connected to a 15 wt.% aqueous KOH scrubber was flushed with nitrogen for 60 minutes.The reactor vessel was charged with 6.34 g of anhydrous lithium chloride and 15.98 g of diethyl carbonate (DEC).

[0129] In the glove box, a glass flask was filled with 31.77 g of molten HCSI and 15.98 g of DEC. The resulting light yellow solution was transferred to a syringe and mounted on a syringe pump.

[0130] The temperature setting of the condenser was fixed at 10°C, that of the reaction mixture was fixed at 25°C and the stirring rate was fixed at 400 rpm, then 47.84 g of HCSI solution were introduced over 27 min.

[0131] Agitation and temperature were maintained for 7.6 hours. A beige slurry was obtained which settled easily.

[0132] The HCSI conversion estimated by HCl change was 97.0%.

[0133] The supernatant was analyzed by NMR: no HCSI was detected by proton NMR, and 7 Li NMR shows a LiCSI signal at 1.08 ppm.

[0134] The reaction crude was diluted with 18.99 g DEC and pumped into the filter under a controlled N2 atmosphere. The solid residue containing excess LiCl was washed with 2.00 g DEC and 79.25 g of filtrate containing 36 wt.% LiCSI was recovered.

[0135] Overall, very high selectivity was achieved using mild conditions, and complete conversion took only a few hours.

[0136] Example A3 - Preparation of LiCSI solution by lithiation of HCSI using DEC as solvent

[0137] A double-jacketed 500 mL glass reactor equipped with integrated baffles, mechanical stirring, condenser, bottom valve and connected to a 15 wt.% aqueous KOH scrubber was flushed with nitrogen for 60 minutes.The reactor vessel was charged with 56.5 g of anhydrous lithium chloride and 94.3 g of DEC.

[0138] In the glove box, a dropping funnel was filled with 192.9 g of molten HCSI (prepared from chlorosulfonyl isocyanate and chlorosulfonic acid) and 100.8 g of DEC. The funnel was then connected to the reactor.

[0139] The temperature setting of the condenser was fixed at 13°C, the temperature setting of the reaction mixture was fixed at 30°C and the stirring rate was fixed at 400 rpm, and then the HCSI solution was introduced over 45 min. The stirring and temperature were maintained for 4.5 hours.

[0140] The HCSI conversion estimated by HCl change was 98.6%.

[0141] The crude reaction product was taken out and filtered in a glove box to separate 354 g of a transparent filtrate and 18 g of a solid residue.

[0142] The filtrate was analyzed by NMR: no HCSI was detected by proton NMR, and 7 In Li-NMR, a LiCSI signal was observed at 1.14 ppm.

[0143] Comparative Example B1 - Preparation of solid LiCSI using DCM as anti-solvent

[0144] 32.9 g of the LiCSI solution obtained as described in Example A2 above were concentrated to 20.0 g using a rotary evaporator at 50° C. and 8 mbar under nitrogen atmosphere.

[0145] 36.5 g of dichloromethane (DCM) were added to the concentrate LiCSI at room temperature, and the mixture was stored at -26°C for 16 hours. A white solid was formed, and the suspension was filtered on a 0.22 micron PTFE membrane in a glove box.

[0146] A solid cake was observed, which was washed 3 times with 10 g of DCM and dried to afford a fine white powder.

[0147] By NMR ( 1 H. 7 Li) and FTIR analysis of the powder. LiCSI was observed and its recovery was poor, i.e., 14% (1.8 g).

[0148] Comparative Example B2—Crystallization of LiCSI from DEC Solution

[0149] In a glove box under argon atmosphere, 20.35 g of the LiCSI solution obtained as described in Example A2 above was loaded into a 25 mL three-necked glass round-bottom flask equipped with a PTFE stirring bar.

[0150] The flask was connected to a vacuum pump and immersed in a constant temperature bath, and DEC evaporation was then carried out at 8 mbar, 35° C. and 600 rpm. After 2 hours, DEC no longer evaporated and the LiCSI concentration had reached 54 wt.%.

[0151] The concentrated solution was seeded with 13 mg of solid LiCSI and stored at -26° C. After 7 days, no obvious crystallization of LiCSI was observed.

[0152] Example B3 - Preparation of solid LiCSI using dioxane as antisolvent

[0153] 36.1 g of the LiCSI solution obtained as described in Example A3 above was mixed with 100 g of dioxane in a glove box. The solution was seeded with 53 mg of solid LiCSI obtained according to the procedure described in Example A3 and stored at -26°C for 3 days. The sample returned to room temperature was a white suspension, which was filtered on a 0.22 micron PTFE membrane and washed with dioxane.

[0154] The filter cake was dried under vacuum at 50°C to obtain a mixture still containing 47 wt% (as determined by 1 H NMR and DSC analysis) as a dry white powder in dioxane (25.87 g).

[0155] The LiCSI recovery rate was 75%.

[0156] Example C1 - Preparation of LiFSI from LiCSI.dioxane solvate using aHF in dioxane

[0157] In an initially thoroughly inertized C276 autoclave equipped with a magnetically coupled stirrer, a heating / cooling double jacket, a temperature probe, a pressure sensor, a condenser and connected to an alkaline aqueous scrubber, solid LiCSI.dioxane (23 g, dioxane content 47 wt.%) prepared according to the procedure in Example B3 was introduced under N2 blanketing.

[0158] Dioxane (91.4 g) was then charged via cannulation. After homogenization by stirring at 800 rpm for 15 min, anhydrous HF (66 g) was gradually introduced. After complete addition of HF, the resulting mixture was heated at 70° C. for 22 h. The pressure reached a maximum of 1.6 bar.

[0159] After pressure release, the reaction mixture was stripped with N2 at 50°C for 12 h to vent most of the excess HF.

[0160] Quantification of reaction mixture 19 F NMR showed LiFSI as the major species with a selectivity above 72%. Chloride titration of the scrubber showed a high conversion of about 96%.

[0161] Comparative Example C2-Preparation of LiFSI from a Solution of LiCSI in DEC with aHF A 50.4%wt solution of LiCSI in DEC (111.6 g) was charged into the container disclosed in Example C1 by cannula under N2 cover. After homogenization by stirring at 800 rpm for 15 minutes, anhydrous HF (8.5 g) was gradually introduced. The mixture was heated at 70°C for 43 hours. The reaction mixture was stripped with N2 at 50°C for 12 hours to evacuate most of the excess HF. Fluoride / chloride titration of the scrubber showed low conversion (chloride recovery in the scrubber was 25.1%).

[0162] Quantification of reaction mixture 19 F-NMR showed a mixture of LiFSI (7.2%) with a large amount of FSO3Li, FSO2NH2 (or its lithium salt), residual HF and other unknown impurities.

[0163] Comparative Example C3 - Preparation of LiFSI starting from a solution of LiCSI in DEC using NH4F

[0164] A 50 mL glass round bottom flask equipped with a condenser, magnetic stirring, and a thermostatic oil bath was flushed with nitrogen for 30 min. The reactor vessel was charged with 15.55 g of diethyl carbonate and 7.74 g of NH4F.

[0165] In the glove box, a 60 mL PP syringe was filled with 48 g of a LiCSI solution (37 wt.% LiCSI) obtained by lithiation of HCSI in DEC and mounted on a syringe pump. The temperature setting of the condenser was fixed at 10°C, the temperature setting of the reaction mixture was fixed at 60°C and the stirring rate was fixed at 400 rpm, and then 46.34 g of LiCSI solution was introduced over 60 min. The medium temperature was then set at 75°C-80°C for 10 hours. After cooling to room temperature, the supernatant was sampled: the total chloride content was about 60% of its initial value (titrated in aqueous solution), which showed that the LiCSI was not completely converted. 19 F-NMR showed the formation of 53.0 ppm of FSI anion as well as by-products (FSI yield = 30%).

[0166] Heating at 75°C-85°C was extended for 5 hours and the supernatant was sampled again: the chloride content was reduced to 50 ppm from 19 The FSI yield by F-NMR analysis was 53%. 7 Li-NMR failed to detect lithium signals in the liquid phase.

Claims

1. A method for producing a salt of bis(chlorosulfonyl)imide [CSI salt] in solid form, the method comprising: (I) contacting at least one first solvent [solvent (S1)] with a compound conforming to formula (1): (1)M x B in M is selected from lithium, sodium, potassium and ammonium; x is 1 or 2; and B is selected from Cl, CO3 2- 、SO4 2- , carboxylates; silicates, preferably metasilicates; borates, preferably tetraborate; and mixtures thereof; to provide a first mixture [mixture (M1)]; (II) contacting the mixture (M1) with bis(chlorosulfonyl)imide (HCSI), so as to provide a second mixture [mixture (M2)] comprising a salt of HCSI selected from lithium-, sodium-, potassium- or ammonium-CSI [CSI salt] and at least one first solvent (S1); (III) contacting said mixture (M2) with at least one second solvent [solvent (S2)] so as to provide the CSI salt in solid form, The at least one second solvent (S2) forms a homogeneous mixture with the at least one first solvent (S1) and is an anti-solvent for the CSI salt.

2. The method according to claim 1, wherein: In the compound having formula (1): -M is lithium, the compound having formula (1) is selected from the group consisting of LiCl, Li2CO3, Li2SO4, Li n (RCO2) n , Li2SiO3, Li2B4O7 and mixtures thereof; or - M is sodium, and the compound of formula (1) is selected from the group consisting of: NaCl, Na2CO3, Na2SO4 and mixtures thereof; or - M is ammonium and the compound having formula (1) is selected from the group consisting of NH4Cl, ammonium carbonate and mixtures thereof.

3. The method according to claim 1 or 2, wherein: The solvent (S1) is selected from the group consisting of carbonates, such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC); esters, such as ethyl acetate, n-butyl acetate; ethers, such as tetrahydrofuran (THF), methyl tert-butyl ether (MTBE), methyltetrahydrofuran (Me-THF).

4. The method according to any one of claims 1 to 3, wherein: The solvent (S1) is different from thionyl chloride (SO2Cl).

5. A method according to any one of the preceding claims, wherein: HCSI is provided in step (II) in its molten form.

6. The method according to claim 5, comprising, before step (II), HCSI ), preferably a step of heating the HCSI at a temperature equal to or higher than 30°C.

7. A method according to any one of the preceding claims, wherein: Step (II) is carried out at a temperature of 15°C to 60°C and / or under atmospheric pressure.

8. A method according to any one of the preceding claims, wherein: The at least one second solvent (S2) is selected in the group comprising: dioxane, chlorinated solvents like dichloromethane (DCM), alkanes, toluene, xylene.

9. A method according to any one of the preceding claims, wherein: Step (III) is carried out at a temperature of 15°C to 60°C and / or under atmospheric pressure.

10. A method according to any one of the preceding claims, wherein: The CSI salt obtained in solid form at the end of step (III) is in the form of a solvate with said at least one second solvent (S2).

11. A solid solvate complex [CSI solvate] comprising a solid lithium, sodium, potassium or ammonium salt of bis(chlorosulfonyl)imide [CSI salt] and dioxane as a solvating solvent.

12. The CSI solvate according to claim 11, wherein In the CSI solvate, the weight ratio of CSI salt to dioxane, as measured as dry powder, ranges from 1:1 to 1:

4.

13. A method for producing a salt of bis(fluorosulfonyl)imide [FSI salt], the method comprising: (V) contacting the CSI salt as obtained according to any one of claims 1 to 10 or the CSI solvate according to any one of claims 11 and 12 with at least one fluorinating agent so as to obtain the FSI salt.

14. The method according to claim 13, wherein: The fluorinating agent is selected from anhydrous hydrogen fluoride or from the group consisting of: (i) KF(HF) p Where p is 0 or 1; (ii) NaF(HF) p Where p is 0 or 1; (iii)X2F(HF) p wherein X2 is an onium cation, and p is 0 or 1; (iv) NH4F(HF) p Where p varies between 0 and 10; (v) LiF; (vi) ZnF2.

15. An electrolyte composition comprising the FSI salt as obtained at the end of the process according to any one of claims 13 and 14.

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