Patent Description:
[F-SO<NUM>-N--SO<NUM>-F], NH<NUM>+     (I).

characterized by having at least two particle size fractions, i.e. a small-size fraction and a large-size fraction. The present disclosure also relates to the use of such dispersion to prepare a salt of bis(fluorosulfonyl)imide selected from the group consisting of a lithium slat, a sodium salt or a potassium salt.

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, notably for battery electrolytes.

The production of bis(fluorosulfonyl)imide (FSI) and salts thereof is described in the literature. One of the possible intermediates leading to FSI salts of interest is ammonium bis(fluorosulfonyl)imide (NH<NUM>FSI). For example, <CIT> (CLS) describes a method for producing lithium bis(fluorosulfonyl)imide comprising the steps of: (<NUM>) reacting bis(chlorosulfonyl)imide with a fluorinating reagent in a solvent, followed by treatment with an alkaline reagent, thereby producing NH<NUM>FSI; and (<NUM>) reacting the NH<NUM>FSI with a lithium base.

Because intermediates, such as NH<NUM>FSI salts, are engaged into further manufacturing steps and sometimes need to be moved from one area of the plant to another, it is convenient to have them in form of dry dispersions or powders.

<CIT> relates to dry powders of bis (fluorosulfonyl) imide metal salt having a particle diameter of not less than <NUM>. It also relates to methods for preparing such powders comprising shaping the salt in molten state. The powders are heated and melted to be in molten state, and then shaped using any available method, including dry processes and wet processes (drum flake granulation method, casting method, roll-drop steel belt granulation method, prilling tower granulation method, melt crystallisation.

<CIT> relates to granules or powders of a di(sulfonylamide) salt, such as a di(sulfonylamide) alkali metal salt or a di(sulfonylamide) ammonium salt. The granules or powders in this document consist of a compound of formula [I]:
<CHM>
wherein R<NUM> and R<NUM> each independently represents a fluoroalkyl group having <NUM> to <NUM> carbon atoms, or a fluorine atom, and Y+ represents an alkali metal cation or an ammonium cation, wherein the granules have a modal diameter of less than <NUM> and a median diameter of less than <NUM>, for example between <NUM> and <NUM>.

<CIT> relates to a method for producing a FSI metal salt, comprising the reaction of bis(fluorosulfonyl)imide (HFSI) with an alkali metal halide in a reaction solution including an organic solvent, and a purification step by filtration of the FSI salt obtained therefrom. The filtering is preferably performed by using a filter medium having retained particle diameter of <NUM> to <NUM>.

None of these documents describe the NH<NUM>FSI salts dispersions of the present invention, having at least two particle size fractions, and therefore a flowability and a dissolution into various solvents which make them well-suited to be stocked and engaged into further manufacturing processes.

The present invention relates to a dry dispersion of ammonium bis(fluorosulfonyl)imide (NH<NUM>FSI) salt of formula (I):.

wherein the NH<NUM>FSI salt is possibly in a form of a solvate comprising:.

wherein the dry dispersion comprises at least two particle size fractions, i.e. a small-size fraction and a large-size fraction.

The present invention also relates to a process for preparing a bis(fluorosulfonyl)imide (MFSI) salt of formula (II):.

Another aspect of the present invention is the dry dispersion of bis(fluorosulfonyl)imide (MFSI) salt of formula (II):.

wherein M is selected from the group consisting of Li, Na and K, and comprises at least two particle size fractions. Such dispersion may be obtained from the process described herein.

The dry dispersion of ammonium bis(fluorosulfonyl)imide (NH<NUM>FSI) salt of the present invention is characterized in that it comprises at least two particle size fractions, i.e. a small-size fraction and a large-size fraction. The dispersion of the present invention may comprise more than two fractions. Preferably, the dispersion of the present invention is characterized by a bimodal particle size distribution. The fractions may be characterized by various Particle Size Distribution (PSD) parameters, for example their d<NUM>-value. Also called D50, the d<NUM>-value is known as the median diameter or the medium value of the PSD. It is the value of the particle diameter at <NUM>% in the cumulative distribution. It means that <NUM> vol. % of the particles in the sample are larger than the d<NUM>-value, and that <NUM> vol. % of the particles in the sample are smaller than the d<NUM>-value.

In some preferred embodiments, the small-size fraction has a d<NUM>-value of less than <NUM>, for example less than <NUM>, less than <NUM>, less than <NUM> or even less than <NUM>, as determined by laser diffraction in n-hexane.

The small-size fraction may also be such that:.

In some other preferred embodiments, the large-size fraction has a d<NUM>-value of more than <NUM>, more than <NUM>, more than <NUM> or even more than <NUM>, as determined by laser diffraction in n-hexane.

The large-size fraction may also be such that:.

The volume ratio of the small particles to the large particles may be from <NUM>:<NUM> to <NUM>:<NUM>, from <NUM>:<NUM> to <NUM>:<NUM> or from <NUM>:<NUM> to <NUM>:<NUM>. The volume ratio may be determined by software calculations, for example using SYMPATEC®.

The PSD of the dry dispersion of the present invention may preferably be such that:.

In some embodiments, the aspect ratio defined as the average ratio of Feret's minimum length to the Feret's maximum length, as counted on about <NUM> particles from a scanning electron microscopy (SEM) image) of the dry dispersion ranges between <NUM> and <NUM>, preferably between <NUM> and <NUM>, even more preferably between <NUM> and <NUM>.

The small-size and large-size fractions of the present invention may also be characterized by their particle diameter Dp at the peak of the volume-based particle size distribution.

In some embodiments, the particle diameter Dp at the peak of the small-size fraction is between <NUM> and <NUM>, preferably between <NUM> and <NUM>, more preferably between <NUM> and <NUM>.

In some embodiments, the particle diameter Dp at the peak of the large-size fraction is between <NUM> and <NUM>, preferably between <NUM> and <NUM>, more preferably between <NUM> and <NUM>.

The dispersion of the present invention may be such that it has a shape being at least one selected from the group consisting of a quadrilateral-like shape, a monoclinic-like shape, a sphere-like shape, a rod-like shape, a needle-like shape and mixtures thereof. Preferably, it has a shape being at least two selected from the group consisting of a quadrilateral-like shape, a monoclinic-like shape, a sphere-like shape, a rod-like shape, a needle-like shape and mixtures thereof.

In some embodiments, the dispersion has a shape such that:.

In some embodiments, the NH<NUM>FSI salt in the dispersion is in a form of a solvate, possibly in a crystallized form, comprising:.

In some embodiments, the NH4FSI salt in the dispersion may be a solvate comprising from <NUM> to <NUM> wt. %, from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. % of the NH<NUM>FSI salt. The NH<NUM>FSI salt in the dispersion may also be a solvate comprising from <NUM> to <NUM> wt. %, from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. % of the NH<NUM>FSI salt. The NH<NUM>FSI salt in the dispersion may even be a solvate comprising from <NUM> to <NUM> wt. %, from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. % of the NH<NUM>FSI salt.

In some embodiments, the NH<NUM>FSI salt in the dispersion may be a solvate comprising from <NUM> to <NUM> wt. %, from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. % of the solvent S<NUM>. The NH<NUM>FSI salt in the dispersion may also be a solvate comprising from <NUM> to <NUM> wt. %, from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. % of the solvent S<NUM>. The NH<NUM>FSI salt in the dispersion may even be a solvate comprising from <NUM> to <NUM> wt. %, from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. % of the solvent S<NUM>.

The dry dispersion of the present invention may be obtained by a process comprising the steps of:.

The crude salt of NH<NUM>FSI may comprise from <NUM> to <NUM> wt. % of the salt of NH<NUM>FSI, preferably from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. The crude salt of NH<NUM>FSI also comprises impurities such as FSO<NUM>-, F-, ClO-, SO<NUM><NUM>-, NH<NUM>SO<NUM>-, NH<NUM>[N(SO<NUM>H)(SO<NUM>F)] (OFSI), and/or NH<NUM>[N(SO<NUM>H)<NUM>] (OSI).

The weight content of these impurities may vary between <NUM> and <NUM> wt. %, for example between <NUM> and <NUM> wt. % or between <NUM> and <NUM> wt.

In some embodiments, the solvent S<NUM> is selected from the group consisting of acetonitrile, valeronitrile, adiponitrile, benzonitrile, methanol, ethanol, <NUM>-propanol, <NUM>-propanol, <NUM>,<NUM>,<NUM>,-trifluoroethanol, n-butyl acetate, isopropyl acetate, and mixtures thereof; preferably <NUM>,<NUM>,<NUM>,-trifluoroethanol (TFE).

In some other embodiments, the solvent S<NUM> is selected from the group consisting of diethylether, diisopropylether, methyl-t-butylether, dimethoxymethane, <NUM>,<NUM>-dimethoxyethane, tetrahydrofuran, <NUM>-methyltetrahydrofuran, <NUM>,<NUM>-dioxane, <NUM>-methyl-<NUM>,<NUM>-dioxane, and <NUM>,<NUM>-dioxane, and mixtures thereof; more preferably from the list consisting of diethyl ether, diisopropyl ether, methyl t-butyl ether, <NUM>,<NUM>-dimethoxyethane, tetrahydrofuran, <NUM>-methyltetrahydrofuran, dioxane and mixtures thereof; even more preferably being <NUM>,<NUM>-dioxane or <NUM>,<NUM>-dioxane.

In one preferred embodiment, the dry dispersion is in the form of a solvate, at least partially crystallized, comprising from <NUM> wt. % to <NUM> wt. % of a solvent S<NUM> (preferably dioxane) and from <NUM> to <NUM> wt. % of the NH<NUM>FSI salt, such dispersion being obtained by a process comprising the steps of:.

In some embodiments, the weight ratio of S<NUM>/S<NUM> in the process from preparing the dispersion of the present invention varies between <NUM>/<NUM> and <NUM>/<NUM>, preferably between <NUM>/<NUM> and <NUM>/<NUM>, more preferably between <NUM>/<NUM> and <NUM>/<NUM>.

In some embodiments, the compound (C) is a lithium compound, preferably selected from the group consisting of lithium hydroxide LiOH, lithium hydroxide hydrate LiOH. H<NUM>O, lithium carbonate Li<NUM>CO<NUM>, lithium hydrogen carbonate LiHCO<NUM>, lithium chloride LiCl, lithium fluoride LiF, alkoxide compounds such as CH<NUM>OLi and EtOLi, alkyl lithium compounds such as EtLi, BuLi and t-BuLi, lithium acetate CH<NUM>COOLi, and lithium oxalate Li<NUM>C<NUM>O<NUM>, more preferably LiOH. H<NUM>O or Li<NUM>CO<NUM>.

The present invention also relates to a dry dispersion of a bis(fluorosulfonyl)imide (MFSI) salt of formula (II):.

The dry dispersion of MFSI salt may be obtained from the process described above.

The MFSI salt described herein is preferably LiFSI.

In some embodiments, the dry dispersion of MFSI salt contains at least <NUM> ppm of solvent S<NUM>. The dry dispersion of MFSI salt may for example contain from <NUM> to <NUM> ppm of solvent S<NUM>, from <NUM> to <NUM> ppm, from <NUM> to <NUM> ppm, from <NUM> to <NUM> ppm or from <NUM> to <NUM> ppm of solvent S<NUM>.

Should the disclosure of any patents, patent applications, and publications conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

The disclosure 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.

The PSD of two dispersions of FSI salts were analysed. The first one is a dispersion of NH<NUM>FSI salts according to the present invention (powder #<NUM>). The second one is a dispersion of LiFSI salts commercially available as IONEL® from Nippon Shokubai (powder #<NUM>).

The inventive dispersion was prepared according to the following process:
A <NUM> reactor with stirring means, a double jacket for thermal regulation, a condenser, a pressure regulator means and a liquid or gas addition means was used. <NUM> of ethyl methyl carbonate (EMC) were introduced in the reactor at room temperature. <NUM> of anhydrous NH<NUM>F was suspended in the reactor. <NUM> of molten HCSI was then added gradually during <NUM> hour, and the mixture was heated at <NUM> under stirring for <NUM> hours. The reaction mixture was then cooled to room temperature and <NUM> of NH<NUM>OH (aq) (ammonia water) was added. The reaction mixture containing NH<NUM>FSI salt was stirred at room temperature for <NUM> and then filtered.

<NUM> of this crude NH<NUM>FSI was concentrated to <NUM>. <NUM> of <NUM>,<NUM>,<NUM>-trifluoroethanol (TFE) was added into the solution and concentrated into a <NUM> solution; this operation was repeated twice. The <NUM> solution was then transferred into the <NUM>-necked flask. Appropriate stirring and temperature were set up to ensure a complete dissolution of NH<NUM>FSI in TFE. Then, <NUM> of <NUM>,<NUM>-dioxane was added dropwise to the reactor in <NUM>. After completion of the <NUM>,<NUM>-dioxane addition, the solution temperature was kept at <NUM> for another period of <NUM>. The mixture was then allowed to cool down to room temperature and stirred overnight. The flask content was then filtrated using a <NUM> PTFE membrane to collect the solid NH<NUM>FSI. The collected solid cake was washed with <NUM> of <NUM>,<NUM>-dioxane. The collected solid was dried using the rotary evaporator under <NUM> at <NUM> mbar until there was no more solvent evaporation to afford <NUM> of a white solid. This white solid is a crystallised solvate of NH4FSI (NH<NUM>FSI-S) comprising <NUM> wt. % of NH<NUM>FSI and <NUM> wt. % of <NUM>,<NUM>-dioxane.

The recrystallization yield, as calculated by the following formula, is <NUM>%.

The PSD was determined by laser diffraction method (HELOS CUVETTE). The diffraction information (raw data) was converted to the cumulative distribution as well as the normalized differential distribution by the SYMPATEC® software provided by device manufacturer. The samples, meanwhile, were prepared in the glove box. <NUM> of solid sample were dispersed in <NUM> of n-hexane to give a final particle mass fraction of about <NUM>%.

Particle morphology of solid samples was analyzed by optical microscopy (bright field). The samples were prepared in the glove box. <NUM> of solid sample were mixed with paraffin on the slide glass, covered with a cover glass, and then sealed by UV curing.

<FIG> shows the bimodal particle size distribution (PSD) of the dry dispersion.

The particle morphology was mixed with a majority of quadrilateral-like, monoclinic-like and sphere-like particles, as well as a small portion of rod-like and needle-like shapes.

Claim 1:
A dry dispersion of ammonium bis(fluorosulfonyl)imide (NH<NUM>FSI) salt of formula (I):

        [F-SO<NUM>-N--SO<NUM>-F], NH<NUM>+     (I)

wherein the NH<NUM>FSI salt is possibly in a form of a solvate comprising:
- <NUM> to <NUM> wt.%, of the NH<NUM>FSI salt, and
- <NUM> to <NUM> wt.%, of solvent S<NUM>, which is selected from the group consisting of cyclic and acyclic ethers,
wherein the dry dispersion comprises at least two particle size fractions, a small-size fraction and a large-size fraction.