Method for manufacturing bis(halogeno sulfonyl)imide

Cross reference to related patent application

[0001] This application claims priority filed on 22 September 2022 in Europe with Nr 22306396.7, the whole content of this application being incorporated herein by reference for all purposes.

Technical field

[0002] The present invention relates to a new synthetic pathway for manufacturing bis(halogeno sulfonyl)imide, which are useful intermediates in the synthesis of lithium bis(fluorosulfonyl)imide (LiFSI).

Background

[0003] Bis(fluorosulfonyl)imide and salts thereof, in particular the lithium salt of bis(fluorosulfonyl)imide (LiFSI), are useful compounds in a variety of technical fields, including in battery electrolytes.

[0004] Several methods for the manufacture of LiFSI have been described in the art. Among the various technologies described, the majority uses a fluorination reaction with a fluorinating agent in a solvent.

[0005] Many efforts have also been taken in the art to improve the manufacturing methods of the intermediate compounds leading to LiFSI, in particular with regard to purity, yield and cost reduction.

[0006] US 2014/0075746 (in the name of Arkema France) discloses a process for the preparation of a bis(sulphonato)imide salt of formula:

(III) (SO ₃ ’)- N- - (SO ₃ ’) 3C ⁺ wherein C ⁺ represents a monovalent cation, the process comprising the reaction of amido-sulphoric acid of formula:

(I) HO-SO2-NH2 with a halo-sulphonic acid of formula:

(II) HO-SO2-X wherein X represents a halon atom, and comprising a reaction with a base which is a salt formed with cation C ⁺ .

[0007] According to an embodiment of such a process, the reaction between compounds of formula (I) and (II) is conducted in the presence of a first base, to provide a bis(sulphonyl)imide of formula : (IV) HO-SO2-NH-SO2-OH which is then reacted with a second base, which is a salt formed with cation C ⁺ to provide the compound of formula (III) above. The compound of formula

(III) thus obtained is further purified in water or other polar solvents, such as alcohols.

[0008] EP 2415757 (in the name of CENTRAL GLASS CO., LTD.) discloses the reaction between halogenated sulfuryl (such as XSO ₂ X with X being Cl or F) or halogenated phosphoryl with ammonia in the presence of an organic base (B) to produce B-XSI structures. Comparative examples 1 and 2 respectively disclose the reaction between SO2F2 and SO2CI2 and NH ₃ without any added base. Only the sulfamide compound was isolated and the conclusion was that the target ammonium salt was hardly obtained in the absence of the organic base.

[0009] US 8,840,856 B2 (in the name of CENTRAL GLASS CO., Ltd.) claims a method for producing an imide salt, which comprises the steps of: reacting an alkali metal fluoride, a sulfuryl dihalide or phosphoryl halide and ammonia or an ammonium salt. The presence of the alkali metal fluoride is mandatory and in the examples it is used in molar excess to ammonia. According to comparative example 1 , the reaction performed in the absence of the alkali metal fluoride did not provide the desired product but sulfamide was obtained as the primary component.

[0010] EP 2920147 B1 (to TRINAPCO Inc.) claims a process for producing a salt of bis(fluorosulfonyl)imide anion, comprising: adding sulfuryl fluoride to solid ammonium fluoride in a solvent in the presence of an aprotic base and isolating the resulting salt. In comparative example 1 , NH ₄ CI is used in combination with 1 ,3-bis (dimethylamino)propane (TMPDA) base. However, no disclosure is made of the products thus obtained, it was only described that a mixture is formed.

[0011] US 2012/0245386 (to TRINAPCO Inc.) discloses a method comparison adding NH ₃ to a SO2F2 solution in the presence of an organic base, preferably selected from N,N,N',N'-tetramethyl-1 ,2-ethanediamine, N,N,N',N’-tetramethyl -1 ,3-propanediamine and combinations thereof.

[0012] WO 2007/104144 (in the name of TRANSFER? PLUS , S.E.C.) discloses the reaction between a compound of formula R1-SO2-R1 and R ₆ -N’ -R ₆ Q ⁺ , wherein each of said R1 is independently F or Cl, each of R ₆ is H, Li, Na, K, Cs or (R?)3Si- and Q ⁺ is chosen from:

[0013] The Applicant is not aware of any disclosure of the preparation of NH ₄ XSI (with X being Cl or F) starting from an ammonium salt, without the use of a base in a stoichiometric amount.

Summary of the invention

[0014] The Applicant is aware that despite all the attempts in the art, the need is still felt for manufacturing intermediate compounds suitable in the synthesis of lithium bis(fluoro sulfonyl)imide (LiFSI), via processes that can be easily implemented on industrial scale.

[0015] In particular, the Applicant faced the problem of manufacturing an intermediate suitable in the synthesis of LiFSI, via a process that satisfies all the above requirements.

[0016] The Applicant surprisingly found that a bis(halogeno sulfonyl)imide can be obtained by reacting a sulfuryl halogenide with at least one ammonium compound.

[0017] Such a process can be advantageously performed in the absence of any base, which makes the process less complex and with a decreased solid waste generation compared to the processes of the prior art. [0018] The process according to the present invention is also advantageous because the reactants and part of the side products generated during the reaction can be recycled, thus lowering the environmental factor (E factor) of the process, which is defined as the ratio between the “mass of total waste” and “mass of product”.

[0019] Further to the above, the reaction according to the present invention can be easily controlled, to limit both exothermic reactions and side reactions.

Disclosure of the invention

[0020] In the present application:

- any description, even though described in relation to a specific embodiment, is applicable to and interchangeable with other embodiments of the present invention;

- where an element or component is said to be included in and/or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individual recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component recited in a list of elements or components may be omitted from such list.

[0021] In a first aspect, the present invention relates to a method for manufacturing bis(halogeno sulfonyl)imide of formula (I) or (II): wherein each of X is independently selected from F, Cl and Br, and

R is a linear or branched alkyl group comprising from 1 to 10 carbon atoms; said method comprising: a) providing a sulfuryl halogenide of formula X _a SO ₂ X _b wherein each of X _a and X _b , identical or different from each other, is selected from F, Cl and Br; b) providing at least one ammonium salt; c) contacting said sulfuryl halogenide and said at least one ammonium salt, to obtain the bis(halogeno sulfonyl)imide of formula (I) or (II).

[0022] Preferably, in the sulfuryl halogenide of formula X _a SO ₂ X _b , X _a and X _b are identical to each other.

[0023] Preferably, the sulfuryl halogenide is selected from CI-SO ₂ -CI, CI-SO ₂ -F and F-SO ₂ -F; more preferably it is CI-SO ₂ -CI.

[0024] Preferably, CI-SO ₂ -CI is provided in its liquid form.

[0025] Preferably, each of CI-SO ₂ -F and F-SO ₂ -F is provided in its gas form.

[0026] Preferably, said at least one ammonium salt complies with formula (III):

+ M

R — -NH-j

(III) wherein

R is a linear or branched alkyl group comprising from 1 to 10 carbon atoms, and

M anion is selected in the group comprising, preferably consisting of: F, Cl, carboxylate, sulfate, hydrogen-sulfate, carbonate, hydrogen-carbonate, tetrafluoroborate and hexafluorophosphate.

[0027] Preferably, said at least one ammonium salt is provided in its solid form.

[0028] Preferably, said ammonium salt is NH ₄ CI or NH ₄ F.

[0029] Under step c), the sulfuryl halogenide reacts with the at least one ammonium salt to obtain the bis(halogeno sulfonyl)imide of formula (I) or (II) as defined above.

[0030] Step c) can be performed in the presence or in the absence of a solvent.

[0031] When step c) is performed in the presence of a solvent, said solvent is preferably selected in the group comprising: ethylene carbonate, propylene carbonate, butylene carbonate, y-butyrolactone, y-valerolactone, dimethoxymethane, 1 ,2-dimethoxyethane, tetrahydrofuran, 2- methyltetrahydrofuran, 1 ,3-dioxane, 4-methyl-1 , 3- dioxolane, methyl formate, methyl acetate, methyl propionate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, sulfolane, 3-methyl sulfolane, dimethylsulfoxide,

N,N-dimethylformamide, N-methyl oxazolidinone, acetonitrile, valeronitrile, benzonitrile, ethyl acetate, isopropyl acetate, n-butyl acetate, nitromethane and nitrobenzene.

[0032] When step c) is performed in the absence of a solvent, the sulfuryl halogenide is advantageously in its liquid form. According to this embodiment, when Cl- SO ₂ -F and F-SO2-F are used, they are liquefied under pressure before performing step c).

[0033] Preferably, step c) is performed at a temperature from about 15°C to about 150°C.

[0034] Preferably, step c) is performed under stirring.

[0035] According to an embodiment, step c) is performed in the presence of a solvent.

[0036] According to this embodiment, the temperature is properly selected based on the solvent used and its boiling temperature. For example, the temperature can be kept between 15°C and 100°C, more preferably between 15°C and 75°C and even more preferably between 20°C and 50°C.

[0037] Also, according to this embodiment, the molar ratio between the sulfuryl halogenide and said at least one ammonium salt in step c) is between 100 to

O.1 , preferably between 10 to 1 , more preferably between 1.5 to 1.

[0038] According to another embodiment, step c) is performed in the absence of any solvent (also referred to as “neat conditions”).

[0039] According to this embodiment, the temperature is between 50°C and 100°C, more preferably between 60°C and 70°C.

[0040] Also, according to this embodiment, the molar ratio between the sulfuryl halogenide and said at least one ammonium salt is between 100 to 0.1 , more preferably between 50 to 1 , and even more preferably between 5 to 1 .

[0041] When the sulfuryl halogenide is used in excess as described in any one of the above embodiments, the unreacted amount of the sulfuryl halogenide can be advantageously distilled off. More preferably, such distilled amount of sulfuryl halogenide is recycled, i.e. provided under step a).

[0042] Preferably, in the method according to the present invention, the sulfuryl halogenide is CISO ₂ CI and the at least one ammonium salt is NH ₄ ⁺ Cl’.

[0043] According to such embodiment, the method according to the present invention comprises: a*) providing a sulfuryl halogenide of formula CISO2CI; b) providing at least one ammonium salt of formula NH ₄ ⁺ Cl’ , c*) contacting said sulfuryl halogenide and said at least one ammonium salt, to obtain the bis(halogeno sulfonyl)imide of formula (I) wherein each of X is chlorine [ammonium-CSI].

[0044] The reaction in step c*) is advantageously performed under the conditions disclosed above for step c).

[0045] Ammonium-CSI can be isolated or purified from the reaction environment. As an alternative, it can be directly used in a subsequent reaction.

[0046] Advantageously, ammonium-CSI can be reacted with a fluorine-containing compound, to manufacture ammonium-FSI.

[0047] According to this embodiment, the method according to the present invention comprises after step c*), a step d) of contacting said ammonium-CSI with at least one fluorinating agent, so as to obtain ammonium-FSI.

[0048] Step d) hence encompasses a fluorination reaction of said ammonium-CSI to obtain ammonium-FSI.

[0049] Such fluorinating agent is preferably selected in the group comprising: HF, more preferably anhydrous HF, or X _c F wherein X _c is selected from NH ₄ , Cs, Li, K.

[0050] When the fluorinating agent is NH ₄ F, the reaction proceeds generating NH ₄ CI as a side-product, which can be advantageously recycled, by providing it under step b).

[0051] Preferably, in the method according to the present invention, the sulfuryl halogenide is CISO2CI and the at least one ammonium salt is NH ₄ ⁺ F’. [0052] According to this embodiment, the method according to the present invention comprises: a**) providing a sulfuryl halogenide of formula CISO ₂ CI; b) providing at least one ammonium salt of formula NH ₄ ⁺ F-; c**) contacting said sulfuryl halogenide and said at least one ammonium salt, to obtain the bis(halogeno sulfonyl)imide of formula (I) wherein each of X is fluorine [ammonium-FSI].

[0053] The reaction in step c**) is advantageously performed under the conditions disclosed above for step c).

[0054] The ammonium-FSI obtained at the end of step d) or of step c**) can be isolated or purified. As an alternative, such ammonium-FSI can be directly used in a subsequent reaction.

[0055] The ammonium-FSI obtained at the end of step d) or of step c**) can be advantageously used as an intermediate compound in the manufacture of LiFSI.

[0056] According to a preferred embodiment, NH4-FSI is reacted with a lithiation agent to manufacture LiFSI.

[0057] Thus, in a further embodiment, the present invention relates to a method for manufacturing LiFSI, said method comprising after step d) or step c**), step e) of contacting said ammonium-FSI and a compound of formula LiX _d , thus obtaining LiFSI.

[0058] Preferably, said compound LiX _d is selected from the group consisting of lithium chloride (LiCI), lithium fluoride (LiF), lithium carbonate (Li ₂ CO ₃ ), lithium hydroxide optionally in its hydrate form (LiOH, LiOH.H ₂ O) lithium sulfate (Li ₂ SO ₄ ), lithium carboxylate (Li _n (RCO ₂ ) _n ), Li ₂ SiO ₃ , Li ₂ B ₄ O ₇ and mixtures thereof.

[0059] Preferably, step e) is performed in the presence of at least one solvent, such that LiFSI is obtained as a liquid composition.

[0060] Preferably, said at least one solvent is selected in the group comprising ethylene carbonate, propylene carbonate, butylene carbonate, y- butyrolactone, y-valerolactone, dimethoxymethane, 1 ,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1 ,3-dioxane, 4-methyl-1 ,3- dioxolane, methyl formate, methyl acetate, methyl propionate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, sulfolane, 3-methyl sulfolane, dimethylsulfoxide, N,N-dimethylformamide, N-methyl oxazolidinone, acetonitrile, valeronitrile, benzonitrile, ethyl acetate, isopropyl acetate, n-butyl acetate, nitromethane and nitrobenzene.

[0061] More preferably, said solvent is selected from ethylene carbonate, propylene carbonate, butylene carbonate, tetrahydrofuran, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate, isopropyl acetate and n- butyl acetate, even more preferred solvents include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate, isopropyl acetate and n- butyl acetate. Even more preferably, said solvent is selected from ethyl methyl carbonate and n-butyl acetate.

[0062] More preferably, said liquid composition comprises from 1 to 70 wt.%, even more preferably from 5 to 50 wt.% and still more preferably from 15 to 40 wt.% of said LiFSI based on the total weight of said liquid composition.

[0063] The method of the present invention is performed in a reactor.

[0064] Preferably, some of the steps, or more preferably all steps, of the method according to the invention are carried out in a reactor capable of withstanding the corrosion of the reagents and of the products and/or by-products obtained as the reaction proceeds. For this purpose, corrosion-resistant materials are selected for the part of the reactor in contact with the reaction media.

[0065] Preferably, said corrosion-resistant material is selected from alloys based on molybdenum, chromium, cobalt, iron, copper, manganese, titanium, zirconium, aluminum, carbon and tungsten, commercially available under the trade name Hastelloy®, such as in particular Hastelloy® C276; alloys of nickel, chromium, iron and manganese to which copper and/or molybdenum are added, commercially available under the trade name Inconel® or Monel™, such as in particular Inconel® 600, 625 or 718.

[0066] Said corrosion-resistant material can be selected from stainless steels, such as austenitic steels and more particularly the 304, 304L, 316 or 316L stainless steels. Preferably, a steel having a nickel content of at most 22 wt.%, preferably of between 6 wt.% and 20 wt.% and more preferentially of between 8 wt.% and 14 wt.%, is used. The 304 and 304L steels have a nickel content that varies between 8 wt.% and 12 wt.%, and the 316 and 316L steels have a nickel content that varies between 10 wt.% and 14 wt.%. More preferably, 316L steels are chosen.

[0067] Said corrosion-resistant material can be a polymeric compound resistant to the corrosion of the reaction medium, which provides a coating onto the part of the reactor in contact with the reaction media. For example, mention can be made of PTFE (polytetrafluoroethylene or Teflon) or PFA (perfluoroalkyl resins).

[0068] As an alternative and more preferably, said anti-corrosion material is selected from glass, glass-lined and enamel equipment.

[0069] Preferably and advantageously, all materials used in the method according to the invention, including reactants, may preferably show very high purity.

[0070] Preferably, their content of metal components such as Na, K, Ca, Mg, Fe, Cu, Cr, Ni, Zn, is below 10 ppm, more preferably below 5 ppm, or below 2 ppm.

[0071] In a further object, the present invention relates to the use of said liquid composition as a non-aqueous electrolyte solution in a battery.

[0072] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

[0073] The present invention will be now described in more detail with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the disclosure.

[0074] EXAMPLES

[0075] Materials

Sulfuryl chloride, acetonitrile and ammonium chloride were purchased and used as such. SO2CI2 : Sigma Aldrich (product code #157767, batch #STBK3652) NH ₄ CI : Alfa Alesar (product code #12361 , batch #Y28E029)

[0076] Methods

¹⁵ N-NMR analysis was performed using Insensitive Nuclear Enhancement by Polarization Transfer (INEPT) as a signal enhancement method.

[0077] Example 1 (neat conditions)

[0078] In an oven-dried 25 mL round bottom flask containing a PTFE-coated magnetic stirrer, ammonium chloride (1 .6 g, 30 mmol, 0.3 equiv.) was added portionwise to neat sulfuryl chloride (8.08 mL, 100 mmol, 1 equiv.) under stirring, at 0 °C. The flask was equipped with a reflux condenser and the reaction mixture was stirred at reflux for 24 hours. The reaction mixture was then cooled down to room temperature, filtered and concentrated under reduced pressure to give an orange solid.

[0079] Trituration in acetonitrile finally afforded the pure product as a white solid. [0080] Yield was 44% (1 .54 g, 6.6 mmol) and the characteristic peaks were found with ¹ H-NMR and ¹⁵ N-NMR analysis.

[0081] Example 2 (with acetonitrile as the solvent)

[0082] Following the procedure disclosed in Eample 1 above, an excess of sulfuryl chloride was reacted with ammonium chloride, but in the presence of acetonitrile as the solvent.

[0083] The reaction medium was filtered to remove ammonium chloride, and a mixture was obtained, which was analyzed via ¹ H-NMR.

[0084] This compound was further analyzed by ¹ H-NMR and ¹⁵ N-NMR. No peak was detected for HCSI or other side products.

[0085] Example 3 (neat conditions)

[0086] Following the same procedure disclosed in Example 1 above, SO ₂ CI ₂ kept at its boiling point was reacted with a sub-stoichiometric amount of NH4CI. [0087] After 1 hour at 69 °C, the reaction medium started to solidify and at the end of 24 hours reaction, a mixture of ammonium-CSI and unreacted solid NH ₄ CI was recovered.

[0088] Ammonium-CSI was obtained at a yield of 48 %. The product was analyzed and characterized by ¹ H-NMR and ¹⁵ N-NMR.