FR3081867A1 - PROCESS FOR THE PREPARATION OF A SALT OF IMIDES CONTAINING A FLUOROSULFONYL GROUP - Google Patents

Abstract

The present invention relates to a process for the preparation of a compound of formula (III): R2- (SO2) -NLi- (SO2) -F (III) said process comprising: - a step b) comprising: ○ a step b1) fluorination of a compound of the following formula (I): R1- (SO2) -NH- (SO2) -CI (I) in which R1 represents one of the following radicals: CI, F, CF3, CHF2, CH2F, C2HF4, C2H2F3, C2H3F2, C2F5, C3F7, C3H4F3, C3HF6, C4F9, C4H2F7, C4H4F5, C5F11, C6F13, C7F15, C8F17 or C9F19, R1 preferably representing CI; with at least one fluorination agent, in the presence of at least one organic solvent SO1; a step c) comprising the addition of the composition obtained in step b), said composition comprising a compound of the following formula (II): R2- (SO2) -NH- (SO2) -F (II), in a composition comprising at least one lithium salt.

Description

PROCESS FOR THE PREPARATION OF A SALT OF IMIDES CONTAINING A FLUOROSULFONYL GROUP

FIELD OF THE INVENTION

The present invention relates to a process for the preparation of lithium salts of imides containing a fluorosulfonyl group.

TECHNICAL BACKGROUND

The sulfonylimide anions, by their very low basicity, are increasingly used in the field of energy storage in the form of inorganic salts in batteries, or organic salts in super capacitors or in the field of liquids ionic. The battery market is booming and the reduction of battery manufacturing costs becoming a major issue, a large-scale and low-cost synthesis process of this type of anions is necessary.

In the specific field of Li-ion batteries, the salt currently used most is LiPFe but this salt shows many disadvantages such as limited thermal stability, sensitivity to hydrolysis and therefore lower battery safety. Recently, new salts with the FSO2 group ^- have been studied and have demonstrated many advantages such as better ionic conductivity and resistance to hydrolysis. One of these salts, LiFSI (LiN (FSO2) 2) has shown very interesting properties which make it a good candidate for replacing LiPFe.

There are various methods for preparing LiFSI. WO2009 / 123328 describes in particular the preparation of LiFSI from bis (chlorosulfonyl) imide, via different stages of preparation of intermediate salts, such as for example a zinc salt of bis (fluorosulfonyl) imide, followed by an ammonium salt bis (fluorosulfonyl) imide.

Most of the existing methods comprise numerous stages, which results in the formation of secondary products having physical properties such that their elimination can prove to be complex, and / or require costly purification stages. Furthermore, the accumulation of stages can cause a reduction in the final yields of LiFSI. In addition, certain processes are not applicable on an industrial scale.

There is therefore still a need for a process for the preparation of a lithium salt of bis (fluorosulfonyl) imide which does not have the above-mentioned drawbacks.

DESCRIPTION OF THE INVENTION

The present invention relates to a process for the preparation of a compound of formula (III) below:

R ₂ - (SO ₂ ) -NLi- (SO ₂ ) -F (III) in which R ₂ represents one of the following radicals: F, CF3, CHF ₂ , CH ₂ F, C ₂ HF4, C ₂ H ₂ F ₈ , C ₂ H ₈ F ₂ , C ₂ Fs, C3F7, C3H4F3, C3HF6, C4F9, C4I-LF7, C4H4F5, C5F11, CeFis, C7F15, CsFi7 or C9F19, preferably R ₂ representing F;

said process comprising:

- a step b) comprising:

o a step b1) of fluorination of a compound of formula (I) below:

Ri- (SO ₂ ) -NH- (SO ₂ ) -CI (I) in which Ri represents one of the following radicals: Cl, F, CF3, CHF ₂ , CH ₂ F, C ₂ HF ₄ , C ₂ H ₂ F ₃ , C ₂ H ₃ F ₂ , C ₂ F ₅ , C3F7, C3H4F3, C ₃ HF ₆ , C4F9, C ₄ H ₂ F ₇ , C4H4F5, C5F11, CeFis, C7F15, C ₈ Fi7 or C9F19, Ri representing preferably Cl;

with at least one fluorination agent, in the presence of at least one organic solvent SO1;

o a possible step b2) of distillation of the composition obtained in step b1);

o a possible step b3) of dissolving the composition obtained in step b1 or in step b2), in an organic solvent SO2;

a step c) comprising the addition of the composition obtained in step b), said composition comprising a compound of formula (II) below:

R ₂ - (SO ₂ ) -NH- (SO ₂ ) -F (II), in a composition comprising at least one lithium salt.

Preferably, the present invention relates to a process for the preparation of a compound of formula (III) below:

R ₂ - (SO ₂ ) -NLi- (SO ₂ ) -F (III) in which R ₂ represents one of the following radicals: F, CF3, CHF ₂ , CH ₂ F, C ₂ HF4, C ₂ H ₂ F ₈ , C ₂ H ₈ F ₂ , C ₂ Fs, C3F7, C3H4F3, C3HF6, C4F9, C4H ₂ F7, C4H4F5, C5F11, CeFis, C7F15, CsFi7 or C9F19, preferably R ₂ representing F;

said method comprising:

- a step a) comprising the reaction of a sulfonamide of formula (A) below:

Ro- (S0 ₂ ) -NH ₂ (A) in which Ro represents one of the following radicals: OH, Cl, F, CF3, CHF ₂ , CH ₂ F, C ₂ HF ₄ , C ₂ H ₂ F ₃ , C ₂ H ₃ F ₂ , C ₂ F ₅ , C3F7, C3H4F3, C ₃ HF ₆ , C4F9, C ₄ H ₂ F ₇ , C4H4F5, C5F11, C ₆ Fi3, C7F15, C ₈ Fi7 or C9F19. Preferably Ro representing OH;

with at least one sulfuric acid and at least one chlorinating agent, to form a compound of formula (I):

Ri- (SO ₂ ) -NH- (SO ₂ ) -CI (I) in which Ri represents one of the following radicals: Cl, F, CF3, CHF ₂ , CH ₂ F, C ₂ HF4,

C ₂ H ₂ F ₈ , C ₂ H ₈ F ₂ , C ₂ Fs, C3F7, C3H4F3, C3HF6, C4F9, C4H ₂ F7, C4H4F5, C5F11, CeFn, C7F15, C ₈ Fi7 or C9F19, Ri preferably representing Cl;

a step b) comprising:

o a step b1) of fluorination of said compound of formula (I) with at least one fluorination agent, in the presence of at least one organic solvent SO1;

o a possible step b2) of distillation of the composition obtained in step b1);

o a possible step b3) of dissolving the composition obtained in step b1 or in step b2) in an organic solvent SO2;

a step c) comprising the addition of the composition obtained in step b), said composition comprising a compound of formula (II) below:

R ₂ - (SO ₂ ) -NH- (SO ₂ ) -F (II), in a composition comprising at least one lithium salt.

The method according to the invention advantageously makes it possible to remedy at least one of the drawbacks of the existing methods. It advantageously allows:

o the preparation of a compound of formula (III), such as for example LiFSI, in a limited number of steps; and / or o the preparation of a compound of formula (III), such as for example LiFSI, on an industrial scale, and at a lower cost; and / or o the preparation of a compound of formula (III), such as for example LiFSI, having a high purity, which allows in particular its use in the electrolytes of Li-ion batteries.

Step a) of chlorination

According to one embodiment, the aforementioned method further comprises a step a), prior to step b), comprising the reaction of a sulfonamide of formula (A) below:

Ro- (S0 ₂ ) -NH ₂ (A) in which Ro represents one of the following radicals: OH, Cl, F, CF3, CHF ₂ , CH ₂ F, C ₂ HF4, C ₂ H ₂ Fs, C ₂ HsF ₂ , C ₂ Fs, C3F7, C3H4F3, C3HF6, C4F9, C4H ₂ F7, C4H4F5, C5F11, CeFn, C7F15, CsFi7 or C9F19;

with at least one sulfuric acid and at least one chlorinating agent, to form a compound of formula (I) as defined above.

Preferably, the compound (A) is that in which Ro represents OH.

Step a) can be carried out:

o at a temperature between 30 ° C and 150 ° C; and / or o with a reaction time of between 1 hour and 7 days; and / or o at a pressure between 1 bar abs and 20 bar abs.

According to the invention, the sulfur agent can be chosen from the group consisting of chlorosulfonic acid (CISO3H), sulfuric acid, oleum, and their mixtures.

According to the invention, the chlorinating agent can be chosen from the group consisting of thionyl chloride (SOCI ₂ ), oxalyl chloride (COCI) ₂ , phosphorus pentachloride (PCI5), phosphonyl trichloride (PCI3) , phosphoryl trichloride (POCI3), and mixtures thereof. Preferably, the chlorinating agent is thionyl chloride.

The chlorination step a) can be carried out in the presence of a catalyst, such as for example chosen from a tertiary amine (such as methylamine, triethylamine, or diethylmethylamine); pyridine; and 2,6-lutidine.

The molar ratio between the sulfuric acid and the compound (A) (in particular in which Ro = OH), can be between 0.7 and 5, preferably between 0.9 and 5.

The molar ratio between the chlorinating agent and the compound (A) (in particular in which Ro = OH), can be between 2 and 10, preferably between 2 and 5.

In particular, when the sulfur-containing agent is chlorosulfonic acid, the molar ratio between it and the compound (A) (in particular in which Ro = OH), is between 0.9 and 5, and / or the molar ratio between the chlorinating agent and the compound (A), in particular with Ro = OH, is between 2 and 5.

In particular, when the sulfur-containing agent is sulfuric acid (or oleum), the molar ratio between sulfuric acid (or oleum) and the compound (A) (in particular in which Ro = OH), is between 0.7 and 5.

In particular, when the sulfur-containing agent is sulfuric acid (or oleum), the molar ratio between sulfuric acid (or oleum) and the compound (A) (in particular in which Ro = OH) is between 0.9 and 5, and / or the molar ratio between the chlorinating agent and the compound (A), (in particular in which Ro = OH) is between 2 and 10.

Step a) advantageously makes it possible to form a compound of formula (I):

Ri- (SO ₂ ) -NH- (SO ₂ ) -CI (I) in which Ri is as defined above, and in particular in which Ri represents Cl.

Step b)

The method according to the invention comprises a step b) comprising:

o a step b1) of fluorination of a compound of formula (I) below:

Ri- (SO ₂ ) -NH- (SO ₂ ) -CI (I) in which Ri represents one of the following radicals: Cl, F, CF3, CHF ₂ , CH ₂ F, C ₂ HF ₄ , C ₂ H ₂ F ₃ , C ₂ H ₃ F ₂ , C ₂ F ₅ , C3F7, C3H4F3, C ₃ HF ₆ , C4F9, C ₄ H ₂ F ₇ , C4H4F5, C5F11, C ₆ Fi3, C7F15, C ₈ Fi7 or C9F19, Ri preferably representing Cl;

with at least one fluorination agent, in the presence of at least one organic solvent SO1;

o a possible step b2) of distillation of the composition obtained in step b1);

o a possible step b3) of dissolving the composition obtained in step b1) or in step b2) in an organic solvent SO2.

Step b1)

Step b1) allows in particular the fluorination of the compound of formula (I) into a compound of formula (II):

R ₂ - (SO ₂ ) -NH- (SO ₂ ) -F (II) in which Fù represents one of the following radicals: F, CF ₃ , CHF2, CH2F, C2HF4, C2H2F ₃ , C2H ₃ F2, C2F5, C ₃ F ₇ , C ₃ H ₄ F ₃ , C ₃ HFe, C4F9, C4H2F7, C4H4F5, C5F11, C ₃ Fi ₃ , C7F15, CsFi? or C9F19, preferably R2 representing F.

Preferably, in formula (II) above, R2 represents F, CF ₃ , CHF2, or CH2F. It is particularly preferred that R2 represents F.

According to one embodiment, the fluorinating agent is chosen from the group consisting of HF (preferably anhydrous HF), KF, AsF ₃ , BiF ₃ , ZnF2, SnF2, PbF2, CuF2, and their mixtures, the agent fluorination preferably being HF, and even more preferably anhydrous HF.

In the context of the invention, by "anhydrous HF" is meant HF containing less than 500 ppm of water, preferably less than 300 ppm of water, preferably less than 200 ppm of water.

Step b1) of the process is carried out in at least one organic solvent SO1. The organic solvent SO1 preferably has a donor number between 1 and 70 and advantageously between 5 and 65. The donor index of a solvent represents the value ΔΗ, ΔΗ being the enthalpy of the interaction between the solvent and the antimony pentachloride (according to the method described in Journal of Solution Chemistry, vol. 13, n ° 9, 1984). As organic solvent SO1, there may be mentioned in particular esters, nitriles, dinitriles, ethers, diethers, amines, phosphines, and mixtures thereof.

Preferably, the organic solvent SO1 is chosen from the group consisting of methyl acetate, ethyl acetate, butyl acetate, acetonitrile, propionitrile, isobutyronitrile, glutaronitrile , dioxane, tetrahydrofuran, triethylamine, tripropylamine, diethylisopropylamine, pyridine, trimethylphosphine, triethylphosphine, diethylisopropylphosphine, and mixtures thereof. In particular, the organic solvent SO1 is dioxane.

Step b1) can be carried out at a temperature between 0 ° C. and the boiling temperature of the organic solvent SO1 (or of the mixture of organic solvents SO1). Preferably, step b) is carried out at a temperature between 5 ° C and the boiling temperature of the organic solvent SO1 (or of the mixture of organic solvents SO1), preferably between 20 ° C and the boiling temperature of the organic solvent SO1 (or mixture of organic solvents SO1).

Step b1), preferably with anhydrous hydrofluoric acid, can be carried out at a pressure P, preferably between 0 and 16 bars abs.

This step b1) is preferably carried out by dissolving the compound of formula (I) in the organic solvent SO1, or the mixture of organic solvents SO1, prior to the step of reaction with the fluorinating agent, preferably with ΙΉF anhydrous.

The mass ratio between the compound of formula (I) and the organic solvent SO1, or the mixture of organic solvents SO1, is preferably between 0.001 and 10, and advantageously between 0.005 and 5.

According to one embodiment, anhydrous ΙΉF is introduced into the reaction medium, preferably in gaseous form.

The molar ratio x between the fluorinating agent, preferably anhydrous HF, and the compound of formula (I) used is preferably between 1 and 10, and advantageously between 1 and 5.

The reaction step with the fluorinating agent, preferably anhydrous HF, can be carried out in a closed medium or in an open medium, preferably step b) is carried out in an open medium with in particular release of HCl in the form gas.

The fluorination reaction typically leads to the formation of HCl, the majority of which can be degassed from the reaction medium (just like the excess HF if the fluorination agent is HF), for example by stripping with a neutral gas (such as nitrogen, helium or argon).

However, residual HF and / or HCI can be dissolved in the reaction medium. In the case of HCI the quantities are very small because at working pressure and temperature the HCI is mainly in gas form.

The composition obtained at the end of step b1) can be stored in an HF-resistant container.

The composition obtained in step b1) can comprise HF (it is in particular unreacted HF), the compound of formula (II) above, the solvent SO1 (such as for example dioxane), and optionally HCl, and / or optionally heavy compounds.

Step b2)

According to one embodiment, step b) comprises a step b2) of distillation of the composition obtained in step b1).

According to one embodiment, step b2) of distillation of the composition obtained in step b1) makes it possible to form and recover:

o a first flow F1 comprising HF, the organic solvent SO1 and optionally HCl, preferably at the top of the distillation column, said flow F1 being gaseous or liquid;

a second stream F2 comprising the compound of formula (II), and optionally heavy compounds, preferably at the bottom of the distillation column, said stream F2 being preferably liquid.

When the flow F2 comprises heavy compounds, this can be subjected to an additional stage of distillation in a second distillation column, to form and recover:

o an F2-1 stream comprising the compound of formula (II) free of heavy compounds, preferably at the top of the distillation column, said F2-1 stream being preferably liquid, o an F2-2 stream comprising the heavy compounds and the compound of formula (II), preferably at the bottom of the distillation column, said stream F2-2 containing less than 10% by weight of the compound of formula (II) contained in the composition obtained in step b1), preferably less of 7% by weight, and preferably less than 5% by weight, said flow F2-2 being preferably liquid.

According to one embodiment, step b2) of distillation of the composition obtained in step b1) makes it possible to form and recover, thanks to the use of two distillation columns: o a first flow F1 comprising HF, the solvent organic SO1 and optionally HCl at the head of the first distillation column, said flow F1 being gaseous or liquid;

a second stream F2 comprising the compound of formula (II), and optionally heavy compounds at the bottom of the first distillation column, said stream F2 being preferably liquid;

said stream F2 being subjected to a distillation step in a second distillation column, to form and recover:

o a flow F2-1 comprising the compound of formula (II) free of heavy compounds at the head of the second distillation column, said flow F2-1 being preferably liquid, o a flow F2-2 comprising the heavy compounds and the compound of formula (II), at the bottom of the second distillation column, said stream F2-2 containing less than 10% by weight of the compound of formula (II) contained in the composition obtained in step b1), preferably less than 7% by weight, and preferably less than 5% by weight, said flow F2-2 being preferably liquid.

In the context of the invention, the term “heavy compounds” means organic compounds having a boiling point higher than that of the compound of formula (II). They can result from cleavage reactions of the compound of formula (I) leading for example to compounds such as FSO2NH2, and / or from degradation reactions of solvents leading to the formation of oligomers.

According to one embodiment, step b2) of distillation of the composition obtained in step b1) makes it possible to form and recover:

o a first stream F’1 comprising HF, the organic solvent SO1 and optionally HCl, preferably at the top of the distillation column, said stream F’1 being gaseous or liquid;

o a second flow F’2 comprising the compound of formula (II), preferably recovered by lateral withdrawal, said flow F’2 being preferably liquid;

a third stream F'3 comprising heavy and the compound of formula (II), preferably at the bottom of the distillation column, said stream F'3 containing less than 10% by weight of the compound of formula (II) contained in the composition obtained in step b1), preferably less than 7% by weight, and preferably less than 5% by weight, said flux F'3 being preferably liquid.

To carry out the lateral withdrawal, the distillation column can contain at least one tray.

The distillation step b2) can be carried out at a pressure ranging from 0 to 5 bar abs, preferably from 0 to 3 bar abs, preferably from 0 to 2 bar abs, and advantageously from 0 to 1 bar abs.

The distillation step b2) can be carried out:

o at a temperature at the bottom of the distillation column ranging from 150 ° C to 200 ° C, preferably from 160 ° C to 180 ° C, and preferably from 165 ° C to 175 ° C, at a pressure of 1 bar abs; or o at a temperature at the bottom of the distillation column ranging from 30 ° C to 100 ° C, preferably from 40 ° C to 90 ° C, and preferably from 40 ° C to 85 ° C, at a pressure of 0.03 abs bar

The distillation step b2) can be carried out in any conventional device. It can be a distillation device comprising a distillation column, a boiler and a condenser.

The distillation column can include:

o at least one packing such as for example a loose packing and / or a structured packing, and / or o trays such as for example perforated trays, trays with fixed valves, trays with movable valves, trays with domed caps, or their combinations.

The height of the distillation column typically depends on the nature of the compounds to be separated. Typically, depending on the flow rates used, the distillation column can have any type of diameter: small (less than or equal to 1 meter) or large (greater than 1 meter).

The material of the distillation column, of its internal constituents (packing and / or trays), of the boiler, and / or of the condenser is advantageously chosen from corrosion-resistant materials, because of the potential presence of HF and / or HCl in the composition subjected to distillation.

Corrosion resistant materials can be chosen from enamelled steels, nickel, titanium, chromium, graphite, silicon carbides, nickel-based alloys, cobalt-based alloys, alloys based on chromium, steels partially or totally coated with a protective coating of fluoropolymer (such as for example PVDF: polyvinylidene fluoride, PTFE: polytetrafluoroethylene, PFA: copolymer of C2F4 and perfluorinated vinyl ether, FEP: copolymer of C2F4 and C3F6, ιθ etfe: copolymer of ethylene and tetrafluoroethylene, or FKM: copolymer of hexafluoropropylene and difluoroethylene).

The nickel-based alloys are preferably alloys comprising at least 40% by weight of nickel, preferably at least 50% by weight of nickel relative to the total weight of the alloy. One can for example quote the alloys Inconel®, Hastelloy®, or Monel®.

The flows F1 and F’1 can include HF, HCl, the organic solvent SO1 (in particular dioxane).

According to one embodiment, the flow F1 comprises from 2 to 70% by weight of HF, preferably from 5 to 60% by weight of HF relative to the total weight of the flow F1, and from 30% to 98% by weight of organic solvent SO1, preferably from 40% to 95% by weight of SO1, relative to the total weight of the flow F1.

According to one embodiment, the flow F'1 comprises from 2 to 70% by weight of HF, preferably from 5 to 60% by weight of HF relative to the total weight of the flow F'1, and from 30% to 98 % by weight of organic solvent SO1, preferably from 40% to 95% by weight of SO1, relative to the total weight of the flow F'1.

According to one embodiment, the stream F2 comprises from 50 to 100% by weight of compound of formula (II), preferably from 70 to 99% by weight of compound of formula (II) relative to the total weight of the stream F2.

According to one embodiment, the stream F'2 comprises from 50 to 100% by weight of compound of formula (II), preferably from 70 to 99% by weight of compound of formula (II) relative to the total weight of the stream F '2.

According to one embodiment, the flow F2-1 comprises from 50 to 100% by weight of compound of formula (II), preferably from 70 to 99% by weight of compound of formula (II) relative to the total weight of the flow F2-1.

Step b2) advantageously allows the recovery of a compound of formula (II) having a high purity. The use of a compound of formula (II) of high purity advantageously makes it possible to prepare a compound of formula (III), in particular LiFSI, having a high purity, without requiring additional purification steps.

Step b3)

According to one embodiment, step b) comprises a step b3) of dissolving the composition obtained in step b1) or in step b2) in an organic solvent SO2, said solvent SO2 preferably being polar aprotic .

The organic solvent SO2 can be a water-miscible solvent.

In the context of the invention, the term "water-miscible solvent" means a solvent which does not form a macroscopic phase separation.

The organic solvent SO2 can be chosen from the group consisting of ethers, diethers, nitriles, amines, carbonates or phosphines. Preferably, the organic solvent SO2 is chosen from the group consisting of methyl acetate, ethyl acetate, butyl acetate, acetonitrile, propionitrile, isobutyronitrile, glutaronitrile , dioxane, tetrahydrofuran, triethylamine, tripropylamine, diethylisopropylamine, pyridine, diethylcarbnoate, dimethylcarbonate, methylethylcarbonate, ethylene carbonate, trimethylphosphine, triethylphosphine, diethylisopropylphosphine and their mixtures , the solvent SO2 preferably being dioxane.

Preferably, step b3) comprises the addition of said solvent SO2 in the composition obtained in step b1) or in step b2).

Preferably, step b) includes step b1), step b2) and step b3).

In the embodiment where step b) comprises step b1), b2) and b3), step b3) notably comprises dissolving the flow F2 (or the flow F2-1 or the flow F ' 2) in an organic solvent SO2.

Step c)

The above-mentioned process comprises a step c) comprising the addition of the composition obtained in step b), said composition comprising a compound of formula (II) below:

R ₂ - (SO ₂ ) -NH- (SO ₂ ) -F (II),

R ₂ being as defined above, and preferably R ₂ representing F, in a composition comprising at least one lithium salt.

Step c) advantageously makes it possible to convert the compound of formula (II) into a compound of formula above-mentioned:

R ₂ - (SO ₂ ) -NLi- (SO ₂ ) -F (III) in which R ₂ represents one of the following radicals: F, CF3, CHF ₂ , CH ₂ F, C ₂ HF4, C ₂ H ₂ Fs, C ₂ HsF ₂ , C ₂ Fs, C3F7, C3H4F3, C3HF6, C4F9, C4H ₂ F7, C4H4F5, C5F11, CeFis, C7F15, CsFi7 or C9F19, R ₂ preferably representing F.

Typically, step c) can be carried out from the composition obtained in step b1) or from the composition obtained in step b2) (flow F2, or flow F2-1 or flow F'2) , or from the composition obtained in step b3) or after any intermediate step between step b) and step c).

According to one embodiment, the composition comprising at least one lithium salt is an aqueous composition, preferably an aqueous suspension or an aqueous solution.

According to another embodiment, the composition comprising at least one lithium salt is a solid composition, preferably the composition consists of at least one solid lithium salt.

In particular, the composition obtained in step b) is added to a container comprising the composition comprising at least one lithium salt. The container can be a reactor, preferably comprising at least one stirring system. The elements making it possible to introduce the composition obtained in step b) are preferably resistant to HF.

According to one embodiment, the lithium salt is chosen from the group consisting of LiOH, LiOH, H ₂ O, UHCO3, Li ₂ CC> 3, LiCI, and their mixtures. Preferably, the lithium salt is Li ₂ CC> 3.

The composition, when it is an aqueous composition comprising at least one lithium salt, can be prepared by any conventional means for preparing an alkaline aqueous composition. It can for example be the dissolution of the lithium salt in ultrapure or deionized water, with stirring.

Preferably, the above-mentioned method comprises a step c) comprising the addition of the composition obtained in step b), said composition comprising a compound of the above-mentioned formula (II):

R ₂ - (SO ₂ ) -NH- (SO ₂ ) -F (II),

R ₂ being as defined above, and preferably R ₂ representing F, in an aqueous composition comprising at least one lithium salt.

To determine the quantity of lithium salt to be introduced, it is typically possible to analyze the total acidity of the mixture to be neutralized.

According to one embodiment, step c) is such that:

the molar ratio of the lithium salt divided by the number of basicities of the said salt with respect to the compound of formula (II) is greater than or equal to 1, preferably less than 5, preferably less than 3, preferably between 1 and 2; and or

the mass ratio of the lithium salt to the mass of water in the aqueous composition is between 0.1 and 2, preferably between 0.2 and 1, preferably between 0.3 and 0.7.

For example, the salt Li ₂ COs has a number of basicities equal to 2.

Step c) of the process according to the invention can be carried out at a temperature less than or equal to 40 ° C, preferably less than or equal to 30 ° C, preferably less than or equal to 20 ° C, and in particular less than or equal at 15 ° C.

According to one embodiment, the method according to the invention comprises an additional step of filtering the composition obtained in step c), leading to a filtrate F and to a cake G.

The compound of formula (III) prepared can be contained in the filtrate F and / or in the cake G.

The filtrate F can be subjected to at least one extraction step with an organic solvent SO3 typically sparingly soluble in water, in order to extract the above-mentioned compound of formula (III) in an organic phase. The extraction step typically leads to the separation of an aqueous phase and an organic phase.

In the context of the invention, and unless otherwise stated, by "sparingly soluble in water" means a solvent whose solubility in water is less than 5% by weight.

The above-mentioned organic solvent SO3 is chosen in particular from the following families: esters, nitriles, ethers, chlorinated solvents, aromatic solvents, and mixtures thereof. Preferably, the organic solvent SO3 is chosen from dichloromethane, ethyl acetate, butyl acetate, tetrahydrofuran, diethyl ether, and their mixtures. In particular, the organic solvent SO3 is butyl acetate.

For each extraction, the mass quantity of organic solvent used can vary between 1/6 and 1 times the mass of the filtrate F. The number of extractions can be between 2 and 10.

Preferably, the organic phase, resulting from the extraction (s), has a mass content of compound of formula (III) ranging from 5% to 40% by mass.

The separate organic phase (obtained at the end of the extraction) can then be concentrated to reach a concentration of compound of formula (III) of between 30% and 60%, preferably between 40% and 50% by mass, said concentration can be achieved by any means of evaporation known to those skilled in the art.

The above-mentioned cake G can be washed with an organic solvent SO4 chosen from the following families: esters, nitriles, ethers, chlorinated solvents, aromatic solvents, and mixtures thereof. Preferably, the organic solvent SO4 is chosen from dichloromethane, ethyl acetate, butyl acetate, tetrahydrofuran, acetronitrile, diethyl ether, and their mixtures. In particular, the organic solvent SO4 is butyl acetate.

The mass amount of organic solvent SO4 used can vary between 1 and 10 times the weight of the cake. The total amount of organic solvent SO4 intended for washing can be used at once or in several times with the particular aim of optimizing the dissolution of the compound of formula (III).

Preferably, the organic phase, resulting from the washing (s) of the cake G, has a mass content of compound of formula (III) ranging from 5% to 20% by mass.

The separate organic phase resulting from the washing (s) of the cake G, can then be concentrated to reach a concentration of compound of formula (III) of between 30% and 60%, preferably between 40% and 50% by mass , said concentration can be achieved by any means of evaporation known to those skilled in the art.

According to one embodiment, the organic phases resulting from (s) the extraction (s) of the filtrate F and of the washing (s) of the cake G, can be combined together, before the concentration step.

Stage d) of purification

The method according to the invention may further comprise a step of purifying the compound of formula above-mentioned.

Step d) of purification of the compound of formula (III) can be carried out by any known conventional method. It can be, for example, an extraction method, a washing method with solvents, a reprecipitation method, a recrystallization method, or a combination thereof.

At the end of step c) above, the compound of formula (III) can be in the form of a composition comprising from 30% to 95% by weight of compound of formula (III) relative to the total weight of said composition.

According to a first embodiment, step d) is a step of crystallization of the compound of formula (III) above.

Preferably, during step d), the compound of formula (III) above mentioned is crystallized cold, in particular at a temperature lower than or equal to 25 ° C.

Preferably, during step d), the crystallization of the compound of formula (III) is carried out in an organic solvent SO5 (“crystallization solvent”) chosen from chlorinated solvents, such as for example dichloromethane, and the solvents aromatic, such as for example toluene, in particular at a temperature less than or equal to 25 ° C. Preferably, the compound of formula (III) crystallized at the end of step d) is recovered by filtration.

The crystallization step is preferably carried out on a composition comprising between 75% and 90% by weight of the compound of formula (III). To do this, the composition obtained at the end of step c) can be concentrated to obtain a solution corresponding to the above-mentioned composition. Concentration can be done by any conventional means of concentration. It can in particular be carried out under reduced pressure of between 40mbars and 0.01 mbar at a temperature below 70 ° C, preferably below 50 ° C, preferably below 40 ° C. It can preferably be carried out according to the conditions of step v) described below.

Preferably, when the method according to the invention comprises the step b2) mentioned above, the method comprises a step d) of crystallization of the compound of formula (III) according to this first embodiment.

According to a second embodiment, step d) comprises the following steps:

i) optional dissolution of the compound of formula (III) in an organic solvent S’1;

ii) addition of deionized water to dissolve and extract the compound of formula (III) above, forming an aqueous solution of said compound of formula (III);

iii) optional concentration of said aqueous solution of said compound of formula (ni);

iv) extracting the compound of formula (III) from said aqueous solution, with an organic solvent S’2, preferably said solvent S2 forming an azeotropic mixture with water, this step being repeated at least once;

v) concentration of the compound of formula (III) by evaporation of said organic solvent S’2 and of water, in a short-film thin film evaporator, under the following conditions:

- temperature between 30 ° C and 95 ° C, preferably between 30 ° C and 90 ° C, preferably between 40 ° C and 85 ° C;

- pressure between 10 ' ³ mbar abs and 5 mbar abs;

- residence time less than or equal to 15 min, preferably less than or equal to 10 min, and advantageously less than or equal to 5 min;

vi) optionally crystallization of the compound of formula (III).

Step d) may not include step i) above, if the compound of formula (III) obtained in step c) already comprises an organic solvent (such as for example SO3 and / or SO4).

Preferably, the method comprises this step d) of purification according to this second embodiment, when the method according to the invention does not include step b2) mentioned above.

Step ii) above includes in particular the addition of deionized water to the solution of the compound of formula (III) in the organic solvent S'1 above, to allow the dissolution of said formula (III), and the extraction of said of formula (III) in water (aqueous phase).

The extraction can be carried out by any known means of extraction. The extraction typically allows the separation of an aqueous phase (aqueous solution of said salt in the present case) and an organic phase.

According to the invention, step ii) can be repeated at least once, for example three times. In a first extraction, an amount of deionized water corresponding to half the mass of the initial solution can be added, then an amount equal to approximately 1/3 of the mass of the initial solution during the second extraction, then a amount equal to approximately 1/4 of the mass of the initial solution during the third extraction.

Preferably, step ii) is such that the mass of deionized water is greater than or equal to one third, preferably greater than or equal to half, of the mass of the initial solution of the compound of formula (III) in the organic solvent S'1 (in the case of a single extraction, or for the first extraction only if step ii) is repeated at least once).

In case of multiple extractions (repetition of step ii)), the aqueous phases extracted can be combined together to form a single aqueous solution.

At the end of step ii), an aqueous solution of compound of formula (III) is obtained in particular.

According to one embodiment, the mass content of the compound of formula (III) in the aqueous solution is between 5% and 35%, preferably between 10% and 25%, relative to the total mass of the solution.

Preferably, step d) comprises a concentration step iii) between step ii) and step iv), preferably to obtain an aqueous solution of the compound of formula (III) comprising a mass content of compound of formula (III) between 20% and 80%, in particular between 25% and 80%, preferably between 25% and 70%, and advantageously between 30% and 65% relative to the total mass of the solution. The concentration step can be carried out by a rotary evaporator under reduced pressure, at a pressure of less than 50 mbar abs (preferably less than 30 mbar abs), and in particular at a temperature between 25 ° C and 60 ° C, preferably between 25 ° C and 50 ° C, preferably between 25 ° C and 40 ° C, for example at 40 ° C.

The compound of formula (III), contained in the aqueous solution obtained at the end of step ii), and of a possible concentration step iii) or of any other intermediate step, can then be recovered by extraction with an organic solvent S'2, said solvent S'2 can preferably form an azeotrope with water (step iv). Step iv) of the pipe in particular, after extraction, to an organic phase, saturated with water, containing the compound of formula (III) (it is a solution of compound of formula (III) in the organic solvent S'2, said solution being saturated with water).

The extraction typically allows the separation of an aqueous phase and an organic phase (solution of the compound of formula (III) in the solvent S’2 in the present case).

Step iv) advantageously makes it possible to obtain an aqueous phase and an organic phase, which are separated.

Preferably, the organic solvent S’2 is chosen from the group consisting of esters, nitriles, ethers, chlorinated solvents, aromatic solvents, and mixtures thereof. Preferably, the solvent S’2 is chosen from ethers, esters, and mixtures thereof. For example, mention may be made of diethylcarbonate, methyl-t-butyl ether, cyclopentylmethyl ether, ethyl acetate, propyl acetate, butyl acetate, dichloromethane, tetrahydrofuran, acetronitrile, diethyl ether, and mixtures thereof. Preferably, the solvent S’2 is chosen from methyl-t-butyl ether, cyclopentylmethyl ether, ethyl acetate, propyl acetate, butyl acetate, and mixtures thereof. In particular, the organic solvent S’2 is butyl acetate.

The extraction step iv) is repeated at least once, preferably from one to ten times, and in particular four times. The organic phases can then be combined into one before step v). For each extraction, the mass quantity of organic solvent S’2 used can vary between 1/6 and 1 times the mass of the aqueous phase. Preferably, the organic solvent S’2 / water mass ratio, during an extraction of step iv), varies from 1/6 to 1/1, the number of extractions varying in particular from 2 to 10.

Preferably, during the extraction step iv), the organic solvent S’2 is added to the aqueous solution resulting from step ii) (and optionally step iii).

Step d) according to the second embodiment may comprise a preconcentration step between step iv) and step v), preferably to obtain a solution of the compound of formula (III) in the organic solvent S'2 comprising a mass content of compound of formula (III) of between 20% and 60%, and preferably between 30% and 50% by mass relative to the total mass of the solution. The pre-concentration step can be carried out at a temperature ranging from 25 ° C to 60 ° C, preferably from 25 ° C to 45 ° C, optionally under reduced pressure, for example at a pressure below 50 mbar abs, in particular at a pressure below 30 mbar abs. The pre-concentration step is preferably carried out by a rotary evaporator under reduced pressure, in particular at 40 ° C and at a pressure below 30 mbar abs.

According to the invention, step v) of concentration can be carried out at a pressure of between 10 ' ² mbar abs and 5 mbar abs, preferably between 5.10 ^-2 mbar abs and 2 mbar abs, preferably between 5.10 ^_1 and 2 mbar abs, even more preferably between 0.1 and 1 mbar abs, and in particular between 0.4 and 0.6 mbar abs. In particular, step v) is carried out at 0.5 mbar abs or at 0.1 mbar.

According to one embodiment, step v) is carried out at a temperature between 30 ° C and 95 ° C, preferably between 30 ° C and 90 ° C, preferably between 40 ° C and 85 ° C, and in particular between 50 ° C and 70 ° C.

According to one embodiment, step v) is carried out with a residence time less than or equal to 15 minutes, preferably less than 10 minutes and preferably less than or equal to 5 minutes and advantageously less than or equal to 3 minutes.

In the context of the invention, and unless otherwise stated, the term "residence time" means the time which elapses between the entry of the solution of the compound of formula (III) (in particular obtained at the end from step iv) above) into the evaporator and the outlet of the first drop of the solution.

According to a preferred embodiment, the temperature of the condenser of the thin-film evaporator with short path is between -50 ° C and 5 ° C, preferably between -35 ° C and 5 ° C. In particular, the condenser temperature is -5 ° C.

The aforementioned short path thin film evaporators are also known by the name "Wiped film short path" (WFSP). They are typically called so because the vapors generated during evaporation make a "short trip" (short distance) before being condensed in the condenser.

Among the short path thin film evaporators, we can notably mention the evaporators marketed by the companies Buss SMS Ganzler ex Luwa AG, LUC Gmbh or VTA Process.

Typically, short-path thin film evaporators can include a solvent vapor condenser placed inside the device itself (especially in the center of the device), unlike other types of film evaporator in which the condenser is located outside the device.

In this type of apparatus, the formation of a thin film of product to be distilled on the internal hot wall of the evaporator can typically be ensured by continuous spreading over the evaporation surface using mechanical means. detailed below.

The evaporator can in particular be provided at its center with an axial rotor on which are mounted the mechanical means which allow the film to form on the wall. They may be rotors fitted with fixed blades: lobed rotors with three or four blades made of flexible or rigid materials, distributed over the entire height of the rotor, or rotors fitted with movable blades, paddles, scraper brushes, guided wipers. In this case, the rotor can be constituted by a succession of pallets articulated on a pivot mounted on a shaft or axis by means of radial supports. Other rotors can be equipped with movable rollers mounted on secondary axes and said rollers are pressed against the wall by centrifugation. The rotational speed of the rotor, which depends on the size of the device, can be easily determined by a person skilled in the art. The different mobiles can be of various materials, metallic for example steel, alloy steel (stainless steel), aluminum, or polymeric, for example polytetrafluroethylene PTFE or glass materials (enamel); metallic materials coated with polymeric materials.

Process

The method according to the invention may include intermediate steps between the different steps of the aforementioned method.

According to one embodiment, steps a), b), c), and optionally d), are sequential.

According to one embodiment, the method according to the invention comprises:

- a step a) comprising the reaction of a sulfonamide of formula (A) below:

Ro- (S0 ₂ ) -NH ₂ (A) in which Ro represents one of the following radicals: OH, Cl, F, CF ₃ , CHF ₂ , CH ₂ F, C ₂ HF ₄ , C ₂ H ₂ F ₃ , C ₂ H ₃ F ₂ , C ₂ F ₅ , C ₃ F ₇ , C ₃ H ₄ F ₃ , C ₃ HF ₆ , C ₄ F ₉ , C ₄ H ₂ F ₇ , C ₄ H ₄ F ₅ , C5F11 , C6F13, C ₇ Fi5, C ₈ Fi ₇ or CgFw. Preferably Ro representing OH;

with at least one sulfuric acid and at least one chlorinating agent, to form a compound of formula (I):

Ri- (SO ₂ ) -NH- (SO ₂ ) -CI (I) in which Ri represents one of the following radicals: Cl, F, CF ₃ , CHF ₂ , CH ₂ F, C ₂ HF ₄ , C ₂ H ₂ F ₃ , C ₂ H ₃ F ₂ , C ₂ Fs, C ₃ F ₇ , C ₃ H ₄ F ₃ , C ₃ HF ₈ , C ₄ Fg, C ₄ H ₂ F ₇ , C ₄ H ₄ Fs, C5F11, C ₈ Fi ₃ , C ₇ Fis, C ₈ Fi ₇ or C9F19, Ri preferably representing Cl;

a step b) comprising:

o a step b1) of fluorination of a compound of formula (I) with anhydrous HF in the presence of at least one organic solvent SO1, o a step b2) of distillation of the composition obtained in step b1) making it possible to form and recover o a first flow F1 comprising HF, the organic solvent SO1 and optionally HCl, preferably at the top of the distillation column, said flow being gaseous or liquid;

o a second flow F2 comprising the compound of formula (II) above, and optionally heavy compounds, preferably at the bottom of the distillation column, said flow F2 being preferably liquid;

a step c) comprising the addition of the composition obtained in step b2) comprising a compound of the above-mentioned formula (II) (flux F2), in a composition, preferably aqueous, comprising at least one lithium salt.

According to a preferred embodiment, the method according to the invention comprises: a step a) comprising the reaction of a sulfonamide of formula (A) below: Ro- (S0 ₂ ) -NH ₂ (A) in which Ro represents l 'one of the following radicals: OH, Cl, F, CF3, CHF2, CH2F,

C2HF4, C2H2F3, C2H3F2, C2F5, C3F7, C3H4F3, C ₃ HF ₆ , C4F9, C4H2F7, C4H4F5, C5F11, C ₆ Fl3,

C7F15, C ₈ Fi7 or C9F19. Preferably Ro representing OH;

with at least one sulfuric acid and at least one chlorinating agent, to form a compound of formula (I):

Ri- (SO ₂ ) -NH- (SO ₂ ) -CI (I) in which Ri represents one of the following radicals: Cl, F, CF3, CHF2, CH2F, C2HF4, C2H2F3, C2H3F2, C2F5, C3F7, C3H4F3 , C3HF6, C4F9, C4H2F7, C4H4F5, C5F11, C ₆ F13, C7F15, C ₈ Fi7 or C9F19, Ri preferably representing Cl;

- a step b) comprising:

o a step b1) of fluorination of a compound of formula (I) with anhydrous HF in the presence of at least one organic solvent SO1, o a step b2) of distillation of the composition obtained in step b1) making it possible to form and recover o a first flow F1 comprising HF, the organic solvent SO1, and optionally HCl, preferably at the top of the distillation column, said flow being gaseous or liquid;

o a second flow F2 comprising the compound of formula (II) above, and optionally heavy compounds, preferably at the bottom of the distillation column, said flow F2 being preferably liquid;

o a step b3) of dissolving the composition obtained in step b2) and comprising the compound of formula (II) (flow F2), in an organic solvent SO2;

a step c) comprising the addition of the composition obtained in step b3) comprising a compound of the above-mentioned formula (II), in a composition, preferably aqueous, comprising at least one lithium salt.

The method according to the present invention is particularly useful for making the compounds of formula (III) include: LiN (SC> 2F) 2, UNSO2CF3SO2F, UNSO2C2F5SO2F, L1NSO2CF2OCF3SO2F, UNSO2C3HF6SO2F, UNSO2C4F9SO2F, UNSO2C5F11SO2F, UNSO2C6F13SO2F, L1NSO2C7F15SO2F, Linso ₂ -C ₈ Fi7SO ₂ F and UNSO2C9F19SO2F.

Preferably, the process according to the invention is a process for preparing LiN (SO ₂ F) ₂ (LiFSI).

In the context of the invention, the terms "lithium salt of bis (fluorosulfonyl) imide", "lithium bis (sulfonyl) imide", "LiFSI", "LiN (SO2F) 2", "lithium are used in an equivalent manner. of bis (sulfonyl) imide ", or" bis (fluorosulfonyl) imide of lithium ".

The process according to the invention advantageously leads to a compound of formula (III), and in particular to LiFSI, having a high purity, in particular at least equal to 99.5% by weight, advantageously at least equal to 99.95% by weight, and possibly including the following impurities in the contents indicated: 0 <H2 <D <40 ppm, 0 <Cl '<80ppm, 0 <SO ₄ ² '<80 ppm, 0 <F '<20 ppm, 0 < FSOsLi <20 ppm, 0 <FSO2NH2S 5 ppm, 0 <K ⁺ <50 ppm, and 0 <Na ⁺ <80 ppm.

In the context of the invention, the term "ppm" means ppm by weight.

uses

The present invention also relates to the use of the compound obtained by the process according to the invention, in Li-ion batteries, in particular in electrolytes of Li-ion batteries.

In particular, it can be Li-ion batteries of portable devices (for example mobile phones, cameras, tablets or portable computers), or electric vehicles, or renewable energy storage (such than photovoltaic or wind).

In the context of the invention, by "lying between x and y", or "ranging from x to y", is meant an interval in which the limits x and y are included. For example, the temperature "between -20 and 80 ° C." includes in particular the values -20 ° C. and 80 ° C.

All of the embodiments described above can be combined with each other. In particular, each embodiment of any stage of the process of the invention can be combined with another particular embodiment.

The present invention is illustrated by the following example, to which it is not however limited.

EXAMPLES

Methods of analysis

The conditions for analyzing anions in ion chromatography (Cl) are as follows:

o Thermo ICS 5000 DUAL device o Precolumn: AG 19 o AS19 column o Flow rate 1 ml / min o Eluent KOH isocratic at 20 mmol / l o Conductometric detection o ASRS suppressor 4 mm with 50 mA of imposed current.

o Injection of 25 μΙ of LiFSI solutions at 5g / l and 10g / I according to the sensitivity required by anionic species present o Calibration of each anionic species with five synthetic solutions ranging from 0.1 mg / l to 25 mg / l .

The limits of detection of anions by this method are as follows:

LD (F ') = 10ppm LD (CI') = 10ppm LD (SO ₄ ² -) = 20ppm

The conditions for cation analysis in ion chromatography (Cl) are as follows:

o Thermo ICS 5000 DUAL device o Precolumn: CG16 o Column CS16 o Flow rate 1 ml / min o Eluent isocratic methane sulfonic acid at 30 mmol / l o Conductometric detection o CSRS suppressor 4 mm with 88mA of imposed current.

o Injection of 25 μΙ of LiFSI solutions at 5g / l and 10g / I according to the sensitivity required by cationic species present.

o Calibration of each cationic species with five synthetic solutions ranging from 0.1 mg / l to 25 mg / l.

The limits of cation detection by this method are as follows:

LD (K ⁺ ) = 20ppm LD (Na ⁺ ) = 20ppm

The NMR analysis conditions for fluorinated species such as FSO3L1 and FSO2NH2 in ¹⁹ F, H1 NMR are as follows:

Equipment: The NMR spectra and quantifications were carried out on a Bruker AV 400 spectrometer, at 1376.47 MHz for ¹⁹ F, on a 5 mm BBFO ⁺ probe.

Sampling:

The samples are dissolved in DMSO-d6 (approximately 30 mg in 0.6 ml). In the case of detection of fluorides or addition of LiF used to check the undesirable presence of fluorides, the solvent used is D ₂ O due to the insolubility of LiF in DMSO.

Quantification:

The relative quantification in NMR of fluorine 19 (NMR ¹⁹ F) is made by integration of the signals of the fluorinated species, weighted by the number of fluorine contributing to the signal, a method well known to those skilled in the art.

The absolute quantification in ¹⁹ F NMR is made by metered addition of a, a, a-trifluorotoluene (TFT), Aldrich in the tube containing the sample, and by integration of the signals of the fluorinated species to be assayed in comparison with that of CF3 of this internal standard, according to a method well known to those skilled in the art. The limit of quantification of a species is of the order of fifty ppm.

Water content :

Carried out by Karl Fischer 684 KF coulometer type dosing coupled with 860 KF Thermoprep (Metrohm equipment).

The solid LiFSI sample is transferred to a glove box in a bottle suitable for Thermoprep. It is heated for 30 minutes at 50 ° C. then the gas phase is introduced into the metering cell of the KF titrimeter.

Example: LiFSI manufacturing process by direct lithiation

In a 2 liter glass reactor thermostatically controlled by a thermofluid circulation whose temperature is regulated, provided with stirring, with a temperature probe, with a refrigerant thermostatically controlled at 5 ° C. connected to a water trap. introduced 240g of sulfamic acid and 255g of 95% sulfuric acid. At room temperature, 1187 g of thionyl chloride are poured. While stirring, the reaction mixture is protected up to 35 ° C in successive steps of + 5 ° C. A gas evolution appears at 35 ° C. The temperature continues to rise to 95 ° C (wall temperature) by controlling the release of gas. The total duration of the reaction is 66 hours.

A white product of 608 g is recovered, corresponding to 115% of the expected theoretical weight. 314 g of dioxane are poured under gentle agitation into the reaction mixture. 461 g of the bis (chlorosulfonyl) imide mixture with dioxane are transferred to a 1 liter autoclave. This autoclave with a PTFE skirt is thermostatically controlled by a thermofluid circulation in a double wall, equipped with a stirrer, a temperature probe, a dip tube and a coolant. With stirring, 123 g of anhydrous H F gas are introduced by means of the dip tube at a flow rate of 15 g / h. The temperature of the medium is maintained between 22 ° C and 25 ° C throughout the reaction. A release of H F and HCl is observed during fluorination. These gases are trapped.

At the end of the reaction, the reaction medium is degassed using a 3.5 l / h sweep with nitrogen for 12 hours. 392 g of solution are obtained.

390 g of solution from the fluorination reaction are taken up. We measure the total acidity of this mixture which is 2 moles which corresponds to the acidity of HFSI and HF remaining in the medium after degassing. In a stirred thermostatically controlled reactor, fitted with a PTFE pouring bulb connected with a PTFE dip tube and a temperature probe, 148 g of I ^ COs are suspended in 400 g of deionized water. The reaction mixture resulting from the fluorination is poured through the dropping funnel by adjusting the rate of introduction so as to maintain the reaction temperature below 20 ° C. At the end of the reaction, the reaction medium is recovered which is filtered. The cake is washed with 125g of butyl acetate. The filtrate is extracted 3 times with 175g of butyl acetate then with 95g of butyl acetate then 200ml of butyl acetate.

The butyl acetate fractions are combined. They are reextracted with deionized water. The butyl acetate phase is eliminated. The aqueous phases are combined and then again extracted with butyl acetate (3 extractions). The butyl acetate phases are combined and then concentrated under vacuum at a temperature of 40 ° C under a pressure of 20mbars on a rotary evaporator. The dry extract of the concentrate is 44%. This solution is then concentrated on a thin film evaporator of the “short path” type under 0.5 mbar at 60 ° C. The concentrate is quickly mixed with 100g of dichloromethane. LiFSI crystallizes. Solid LiFSI is recovered by filtration and dried under vacuum at 40 ° C. 91 g of LiFSI are obtained, the analysis of which is as follows:

Species Amount Method of analysis FSO2NH2 <DL RMN ¹⁹ F FSO3U <DL rmn ¹⁹ f H ₂ O 40 ppm 25 Karl Fischer SO ₄ ² ' <DL Cl gold 82ppm Cl F- <DL NMR K <DL Cl N / A <DL Cl 30

LD: detection limit

Claims (16)

1. Process for the preparation of a compound of formula (III) below: R ₂ - (SO ₂ ) -NLi- (SO ₂ ) -F (III) in which R ₂ represents one of the following radicals: F, CF3, CHF ₂ , CH ₂ F, C ₂ HF4, C ₂ H ₂ F ₈ , C ₂ H ₈ F ₂ , C ₂ Fs, C3F7, C3H4F3, C3HF6, C4F9, C4I-LF7, C4H4F5, C5F11, CeFis, C7F15, C ₈ Fi7 or C9F19, preferably R ₂ representing F ; said method comprising: a step b) comprising: o a step b1) of fluorination of a compound of formula (I) below: Ri- (SO ₂ ) -NH- (SO ₂ ) -CI (I) in which Ri represents one of the following radicals: Cl, F, CF3, CHF ₂ , CH ₂ F, C ₂ HF ₄ , C ₂ H ₂ F ₃ , C ₂ H ₃ F ₂ , C ₂ F ₅ , C3F7, C3H4F3, C ₃ HF ₆ , C4F9, C ₄ H ₂ F ₇ , C4H4F5, C5F11, C ₆ Fi3, C7F15, C ₈ Fi7 or C9F19, Ri preferably representing Cl; with at least one fluorination agent, in the presence of at least one organic solvent SO1; o a possible step b2) of distillation of the composition obtained in step b1); o a possible step b3) of dissolving the composition obtained in step b1 or in step b2) in an organic solvent SO2; a step c) comprising the addition of the composition obtained in step b), said composition comprising a compound of formula (II) below: R ₂ - (SO ₂ ) -NH- (SO ₂ ) -F (II), in a composition comprising at least one lithium salt. 2. Method according to claim 1, in which the fluorinating agent is chosen from the group consisting of HF (preferably anhydrous HF), KF, AsF ₈ , B1F3, ZnF ₂ , SnF ₂ , PbF ₂ , CuF ₂ , and of their mixtures, the fluorinating agent preferably being HF. 3. Method according to any one of claims 1 to 2, further comprising a step a), prior to step b), comprising the reaction of a sulfonamide of formula (A) below: Ro- (S0 ₂ ) -NH ₂ (A) in which Ro represents one of the following radicals: OH, Cl, F, CF3, CHF ₂ , CH ₂ F, C ₂ HF ₄ , C ₂ H ₂ F ₃ , C ₂ H ₃ F ₂ , C ₂ F ₅ , C3F7, C3H4F3, C ₃ HF ₆ , C4F9, C ₄ H ₂ F ₇ , C4H4F5, C5F11, C ₆ Fi3, C7F15, C ₈ F17 or C9F19; with at least one sulfuric acid and at least one chlorinating agent, to form a compound of formula (I) as defined in claim 1. 4. Method according to any one of claims 1 to 3, in which the lithium salt is chosen from the group consisting of LiOH, LiOH, H ₂ O, UHCO3, Li ₂ CO3, LiCI, and their mixtures, the salt preferably being Li ₂ CO3. 5. Method according to any one of claims 1 to 4, in which: the composition comprising at least one lithium salt is an aqueous composition, preferably an aqueous suspension or an aqueous solution; or o the composition comprising at least one lithium salt is a solid composition, preferably the composition consists of at least one lithium salt. 6. Method according to any one of claims 1 to 5, in which: the molar ratio of the lithium salt divided by the number of basicities of the said salt with respect to the compound of formula (II) is greater than or equal to 1, preferably less than 5, preferably less than 3, preferably between 1 and 2; and or the mass ratio of the lithium salt to the mass of water in the aqueous composition is between 0.1 and 2, preferably between 0.2 and 1, preferably between 0.3 and 0.7. 7. Method according to any one of claims 1 to 6, in which step c) is carried out at a temperature less than or equal to 40 ° C, preferably less than or equal to 30 ° C, preferably less than or equal to 20 ° C, and in particular less than or equal to 15 ° C. 8. Method according to any one of claims 1 to 7, further comprising a step d) of purification of the compound of formula (III). 9. Method according to any one of claims 1 to 8, comprising a step b2) of distillation of the composition obtained in step b1). 10. Method according to any one of claims 1 to 9, in which step b2) of distillation of the composition obtained in step b) makes it possible to form and recover: at. a first flow F1 comprising HF, the organic solvent SO1, and optionally HCl, preferably at the top of the distillation column, said flow F1 being gaseous or liquid; b. a second stream F2 comprising the compound of formula (II), and optionally heavy compounds, preferably at the bottom of the distillation column, said stream F2 being preferably liquid. 11. The method as claimed in claim 10, in which the stream F2 is subjected to a distillation step in a second distillation column, to form and recover: o a flow F2-1 comprising the compound of formula (II) free of heavy compounds at the head of the second distillation column, said flow F2-1 being preferably liquid, o a flow F2-2 comprising the heavy compounds and the compound of formula (II), at the bottom of the second distillation column, said stream F2-2 containing less than 10% by weight of the compound of formula (II) contained in the composition obtained in step b1), preferably less than 7% by weight, and preferably less than 5% by weight, said flow F2-2 being preferably liquid. 12. Method according to any one of claims 1 to 9, in which step b2) of distillation of the composition obtained in step b1) makes it possible to form and recover: o a first stream F’1 comprising HF, the organic solvent SO1 and optionally HCl, preferably at the top of the distillation column, said stream F’1 being gaseous or liquid; o a second flow F’2 comprising the compound of formula (II), preferably recovered by lateral withdrawal, said flow F’2 being preferably liquid; a third stream F'3 comprising heavy and the compound of formula (II), preferably at the bottom of the distillation column, said stream F'3 containing less than 10% by weight of the compound of formula (II) contained in the composition obtained in step b1), preferably less than 7% by weight, and preferably less than 5% by weight, said flux F'3 being preferably liquid. 13. Method according to any one of claims 1 to 12, in which the step b2) of distillation is carried out at a pressure ranging from 0 to 5 bar abs, preferably from 0 to 3 bar abs, and preferably from 0 to 1 bar abs. 14. Method according to any one of claims 1 to 13, in which step b2) of distillation is carried out: o at a temperature at the bottom of the distillation column ranging from 150 ° C to 200 ° C, preferably from 160 ° C to 180 ° C, and preferably from 165 ° C to 175 ° C, at a pressure of 1 bar abs; or o at a temperature at the bottom of the distillation column ranging from 30 ° C to 100 ° C, preferably from 40 ° C to 90 ° C, and preferably from 40 ° C to 85 ° C, at a pressure of 0.03 bar abs . 15. Method according to any one of claims 1 to 14, further comprising a step b3) comprising dissolving the composition obtained in step b1) or b2), in an organic solvent SO2. 16. Use of the compound of formula (III) obtained according to the method as defined according to any one of claims 1 to 15, in a Li-ion battery, in particular in a Li-ion battery electrolyte.