DRY DISPERSION OF AMMONIUM BIS(FLUOROSULFONYL)IMIDE (NH4FSI) SALT WITH AN AT LEAST BIMODAL PARTICLE SIZE DISTRIBUTION

Abstract

The present disclosure relates to a dry dispersion of ammonium bis(fluorosulfonyl)imide (NH.sub.4FSI) salt of formula (I): [FSO.sub.2N.sup.SO.sub.2F], NH.sub.4.sup.+ (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.

Claims

1. A dry dispersion of ammonium bis(fluorosulfonyl)imide (NH.sub.4FSI) salt of formula (I):
[FSO.sub.2N.sup.SO.sub.2F],NH.sub.4.sup.+(I) wherein the NH.sub.4FSI salt is in a form of a solvate comprising: 50 to 99.9 wt. %, of the NH.sub.4FSI salt, and 0.1 to 50 wt. %, of solvent S.sub.2, 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.

2. The dispersion of claim 1, wherein: the small-size fraction has a d.sub.50-value of less than 120 m; the large-size fraction has a d.sub.50-value of more than 200 m; and/or the volume ratio of the small particles to the large particles is from 5:95 to 95:5, as determined by laser diffraction in n-hexane.

3. The dispersion of any of claim 1, wherein the dry dispersion is such that: its d.sub.10-value is not less than 20 m; its d.sub.50-value is between 140 and 190 m; its d.sub.90-value is between 260 and 300 m; and/or its d.sub.99-value is between 300 and 400 m, as determined by laser diffraction in n-hexane.

4. The dispersion of claim 1, wherein the small-size fraction of the dry dispersion is such that: its d.sub.10-value is not less than 20 m, and/or its d.sub.50-value is between 80 and 115 m, as determined by laser diffraction in n-hexane.

5. The dispersion of claim 1, wherein the large-fraction of the dry dispersion is such that: its d.sub.50-value is between 200 and 250 m; its d.sub.90-value is between 260 and 300 m; and/or its d.sub.99-value is between 300 and 400 m, as determined by laser diffraction in n-hexane.

6. The dispersion of claim 1, having 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.

7. The dispersion of claim 6, having 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.

8. The dispersion of claim 6, having a shape such that: a small fraction F.sub.s is a rod-like shape and/or a needle-like shape; and a large fraction F.sub.L is a quadrilateral-like shape, a monoclinic-like shape and/or a sphere-like shape, wherein the small fraction is less than 50 wt. % and the large fraction is more than 50 wt. %, the sum of F.sub.s+F.sub.L being equal to 100 wt. %.

9. The dispersion of claim 1, wherein the NH.sub.4FSI salt is a solvate comprising a solvent S.sub.2 is selected from the group consisting of diethylether, diisopropylether, methyl-t-butylether, dimethoxymethane, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxane, 4-methyl-1,3-dioxane, and 1,4-dioxane, and mixtures thereof.

10. A process for preparing the dispersion of claim 1, comprising the steps of: i) providing a crude salt of NH.sub.4FSI; ii) dissolving the crude salt of NH.sub.4FSI in at least one solvent S.sub.1; iii) crystallizing the crude salt of NH.sub.4FSI by means of at least one solvent S.sub.2; and iv) separating the NH.sub.4FSI salt from at least part of the solvents S.sub.1 and S.sub.2, by filtration.

11. The process of claim 10, wherein: S.sub.1 is selected from the group consisting of acetonitrile, valeronitrile, adiponitrile, benzonitrile, methanol, ethanol, 1-propanol, 2-propanol, 2,2,2,-trifluoroethanol, n-butyl acetate, isopropyl acetate, and mixtures thereof; S.sub.2 is selected from the group consisting of diethylether, diisopropylether, methyl-t-butylether, dimethoxymethane, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxane, 4-methyl-1,3-dioxane, and 1,4-dioxane, and mixtures thereof; and/or the weight ratio of S.sub.1/S.sub.2 varies between 1/10 and 10/1.

12. A process for preparing a bis(fluorosulfonyl)imide (MFSI) salt of formula (II):
[FSO.sub.2N.sup.SO.sub.2F],M.sup.+(II) wherein M is selected from the group consisting of Li, Na and K, wherein the process comprises reacting the dry dispersion of ammonium bis(fluorosulfonyl)imide (NH.sub.4FSI) salt of formula (I) of claim 1 with a compound (C) selected from the group consisting of lithium compounds, sodium compounds and potassium compounds.

13. The process of claim 5, wherein the compound (C) is a lithium compound selected from the group consisting of lithium hydroxide LiOH, lithium hydroxide hydrate LiOH.Math.H.sub.2O, lithium carbonate Li.sub.2CO.sub.3, lithium hydrogen carbonate LiHCO.sub.3, lithium chloride LiCl, lithium fluoride LiF, alkoxide compounds, alkyl lithium compounds, lithium acetate CH.sub.3COOLi, and lithium oxalate Li.sub.2C.sub.2O.sub.4.

14. A dry dispersion of a bis(fluorosulfonyl)imide (MFSI) salt of formula (II):
[FSO.sub.2N.sup.SO.sub.2F],M.sup.+(II) wherein M is selected from the group consisting of Li, Na and K, and wherein the dry dispersion comprises at least two particle size fractions.

15. The dispersion of claim 14, wherein: the dispersion contains at least 1 ppm of solvent S.sub.2.

Description

EXAMPLES

[0082] The PSD of two dispersions of FSI salts were analysed. The first one is a dispersion of NH.sub.4FSI salts according to the present invention (powder #1). The second one is a dispersion of LiFSI salts commercially available as IONEL from Nippon Shokubai (powder #2).

Powder #1Dispersion of a NH.SUB.4.FSI in the Form of a Solvate

[0083] The inventive dispersion was prepared according to the following process:

[0084] A 500 mL 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. 400 g of ethyl methyl carbonate (EMC) were introduced in the reactor at room temperature. 81 g of anhydrous NH.sub.4F was suspended in the reactor. 77 g of molten HCSI was then added gradually during 1 hour, and the mixture was heated at 80 C. under stirring for 15 hours. The reaction mixture was then cooled to room temperature and 25 g of NH.sub.4OH (aq) (ammonia water) was added. The reaction mixture containing NH.sub.4FSI salt was stirred at room temperature for 1 h and then filtered.

[0085] 332 g of this crude NH.sub.4FSI was concentrated to 48 g. 300 g of 2,2,2-trifluoroethanol (TFE) was added into the solution and concentrated into a 170 g solution; this operation was repeated twice. The 170 g solution was then transferred into the 3-necked flask. Appropriate stirring and temperature were set up to ensure a complete dissolution of NH.sub.4FSI in TFE. Then, 139.5 g of 1,4-dioxane was added dropwise to the reactor in 3 h. After completion of the 1,4-dioxane addition, the solution temperature was kept at 60 C. for another period of 2 h. The mixture was then allowed to cool down to room temperature and stirred overnight. The flask content was then filtrated using a 0.22 m PTFE membrane to collect the solid NH.sub.4FSI. The collected solid cake was washed with 60 g of 1,4-dioxane. The collected solid was dried using the rotary evaporator under 70 C. at 20 mbar until there was no more solvent evaporation to afford 28.8 g of a white solid. This white solid is a crystallised solvate of NH4FSI (NH.sub.4FSIS) comprising 80 wt. % of NH.sub.4FSI and 20 wt. % of 1,4-dioxane.

[0086] The recrystallization yield, as calculated by the following formula, is 48%.

[00001]$\mathrm{Yield}=\frac{\mathrm{weight}\left({\mathrm{NH}}_4\mathrm{FSI}\mathrm{in}{\mathrm{NH}}_4\mathrm{FSI}-S\right)}{\mathrm{weight}\left(\mathrm{Crude}{\mathrm{NH}}_4\mathrm{FSI}\right)}$

Test Methods

PSD

[0087] 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. 0.1 mg of solid sample were dispersed in 2.5 mL of n-hexane to give a final particle mass fraction of about 4%.

Shape

[0088] Particle morphology of solid samples was analyzed by optical microscopy (bright field). The samples were prepared in the glove box. 0.1 mg of solid sample were mixed with paraffin on the slide glass, covered with a cover glass, and then sealed by UV curing.

Results

Powder #1

[0089] FIG. 1 shows the bimodal particle size distribution (PSD) of the dry dispersion.

TABLE-US-00001 dispersion small-size fraction large-size fraction d10-value (m) 81 59 157 d50-value (m) 164 100 220 d90-value (m) 285 141 283 d99-value (m) 351 nd nd particle diameter nd 97 229 Dp at the peak (m)

[0090] Volume ratio of the small particles to the large particles: 1/1

[0091] 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.

Powder #2

TABLE-US-00002 dispersion d10-value (m) 138 d50-value (m) 355 d90-value (m) 561