NOVEL IONIC LIQUIDS RESULTING FROM THE ASSOCIATION OF A SPECIFIC CATION AND A SPECIFIC ANION

Abstract

Ionic liquids comprising the association of a cation have the following formula (I), in which R1 is an acyclic hydrocarbonated group, n is a whole number between 0 and 3, and m is a whole number between 1 and 4, and an anion selected from a nitrate anion, a phosphate anion or an imidide anion.

Claims

1.-16. (canceled)

17. An ionic liquid comprising the association of a cation having the following formula (I): ##STR00017## in which: R.sup.1 is an acyclic hydrocarbon group; n is an integer ranging from 0 to 3; m is an integer ranging from 1 to 4; and an anion chosen from a nitrate anion, a phosphate anion or an imide anion.

18. The ionic liquid according to claim 17, wherein the cation of formula (I) has the following specific formula (Ib): ##STR00018##

19. The ionic liquid according to claim 17, wherein R.sup.1 is an alkyl group comprising from 1 to 4 carbon atoms.

20. The ionic liquid according to claim 17 wherein m is 2.

21. The ionic liquid according to claim 17, wherein the anion is an imide anion.

22. The ionic liquid according to claim 17, wherein the anion is an imide anion having the following formula (II): ##STR00019## in which R.sup.2 and R.sup.3 represent, independently of each other, a fluorine atom or a perfluorocarbon group.

23. The ionic liquid according to claim 17, wherein the anion is an imide anion which has one of the following formulae (IV) and (V): ##STR00020##

24. The ionic liquid according to claim 17, which has one of the following formulae (VI) and (VII): ##STR00021##

25. A salt comprising the association of at least one cation having the following formula (Ib): ##STR00022## in which: R.sup.1 is an acyclic hydrocarbon group; m is an integer ranging from 1 to 4; and at least one anion Y.

26. The salt according to claim 25, wherein the anion Y is chosen from halide anions, a nitrate anion, a phosphate anion, imide anions.

27. The salt according to claim 25, wherein the anion Y is a chloride type halide anion.

28. An electrolyte comprising at least one ionic liquid as defined in claim 17.

29. The electrolyte according to claim 28, further comprising at least one lithium salt or at least one potassium salt.

30. The electrolyte according to claim 29, wherein the lithium salt is chosen from lithium hexafluorophosphate (LiPF.sub.6), lithium bis(oxalatoborate), lithium tetrafluoroborate (LiBF.sub.4), lithium bis(trifluoromethanesulphonyl)imide (known under the abbreviation LiTFSI), lithium bis(fluorosulphonyl)imide, lithium hexafluoroarsenate (LiAsF.sub.6), lithium nitrate (LiNO.sub.3) or even lithium perchlorate (LiCIO.sub.4).

31. The electrolyte according to claim 29, wherein the potassium salt is chosen from potassium hexafluorophosphate (KPF.sub.6), potassium tetrafluoroborate (KBF.sub.4), potassium bis(trifluoromethanesulphonyl)imide, potassium bis(fluorosulphonyl)imide, potassium hexafluoroarsenate (KAsF.sub.6), potassium nitrate (KNO.sub.3) or even potassium perchlorate (KClO.sub.4).

32. An energy storage device comprising at least one cell comprising a positive electrode and a negative electrode which are separated from each other by a separator comprising an electrolyte as defined in claim 28.

Description

DETAILED DISCLOSURE OF PARTICULAR EMBODIMENTS

Example 1

[0074] This example illustrates the preparation of a salt in accordance with the invention: N-(methyl)-(2-vinyloxyethyl)pyrrolidinium chloride of the following formula:

##STR00014##

[0075] To do this, 25 g of 2-chlorovinyloxyethyl (0.234 mol) and 25 g of methylpyrrodiline (0.293 mol) are previously distilled and then diluted in 200 mL of acetonitrile. The mixture is kept under stirring for 120 hours at 30 C. The excess reagents and solvent are then evaporated under reduced pressure.

[0076] At the end of this evaporation, about 14 g of a yellow-orange coloured liquid (0.073 mol) are obtained, that is a yield of about 30%.

[0077] The liquid obtained is analysed by .sup.1H NMR and .sup.13C NMR, the results of which are reported below.

[0078] .sup.1H NMR (D.sub.2O)=2.16 (br s, 4H); 3.02 (s, 3H); 3.67-3.49 (m, 6H); 4.35-4.17 (m, 4H); 6.2 (m, 1H).

[0079] .sup.13C NMR (D.sub.2O)=21.1 (CH.sub.2); 48.2 (CH.sub.3); 62.2 (CH.sub.2); 62.4 (CH.sub.2); 65.3 (CH.sub.2); 89.0 (CH.sub.2); 150.1 (CH).

[0080] These results confirm that the product obtained is the salt having the formula defined above.

Example 2

[0081] This example illustrates the preparation of an ionic liquid in accordance with the invention: N-(methyl)-(2-vinyloxyethyl)pyrrolidinium bis(fluorosulphonyl)imide of the following formula:

##STR00015##

[0082] To do this, 19 g (0.099 mol) of the salt of example 1 and 22 g of potassium bis(fluorosulphonyl)imide (0.100 mL) are respectively dissolved in 100 mL of ultrapure water (having a resistivity of 18.2 mm.sup.1) to form two solutions (respectively, a solution comprising the salt of example 1 and a solution comprising potassium bis(fluorosulphonyl)imide). Both solutions are mixed at room temperature for 24 hours. An aqueous phase comprising potassium chloride and the excess reagents and an organic phase essentially comprising N-(methyl)-(2-vinyloxyethyl)pyrrolidinium bis(fluorosulphonyl)imide result from this mixture. The organic phase is recovered using dichloromethane and then transferred in a reparatory funnel, in order to be washed 5 times with 100 mL of ultrapure water. The organic phase is isolated and then the dichloromethane is removed by evaporation under reduced pressure, in order to obtain a raw ionic liquid. This ionic liquid is then diluted in ethyl acetate and then active carbon (13 g) is added. The mixture is placed under stirring for 96 hours at 35 C. The active carbon is then removed by filtration. The solution is then purified by adding about 255 g of alumina and then the resulting mixture is stirred for at least 5 hours at room temperature. The alumina is then removed by filtration and then the ionic liquid is recovered after removing ethyl acetate by vacuum evaporation (35 C., 1 mbar) for 72 hours.

[0083] At the end of this removal, about 24 g (that is 0.070 mol) of a pale yellow coloured liquid are obtained.

[0084] The liquid obtained is analysed by .sup.1H NMR and .sup.13C NMR, the results of which are reported below.

[0085] .sup.1H NMR (CDCl.sub.3)=2.10 (br s, 4H); 2.90 (s, 3H); 3.55-3.39 (m, 6H); 4.22-3.94 (m, 4H); 6.32 (m, 1H).

[0086] .sup.13C NMR (CDCl.sub.3)=21.0 (CH.sub.2); 48.4 (CH.sub.3); 62.1 (CH.sub.2); 62.3 (CH.sub.2); 65.4 (CH.sub.2); 88.9 (CH.sub.2); 150.2 (CH).

[0087] These results confirm that the product obtained is the ionic liquid having the formula defined above.

Example 3

[0088] This example illustrates the preparation of an ionic liquid in accordance with the invention: N-(methyl)-(2-vinyloxyethyl)pyrrolidinium bis(trifluoromethanesulphonyl)imide of the following formula:

##STR00016##

[0089] The synthesis protocol is similar to that described in the framework of example 2, except that 14 g of N-(methyl)-(2-vinyloxyethyl)pyrrolidinium chloride (0.073 mol) have been used and 21 g of lithium bis(trifluoromethanesulphonyl)imide (0.073 mol) have been used in place of 22 g of potassium bis(fluorosulphonyl)imide.

[0090] 22 g of a pale yellow ionic liquid are obtained.

[0091] The liquid obtained is analysed by .sup.1H NMR and .sup.13C NMR, the results of which are reported below.

[0092] .sup.1H NMR (CDCl.sub.3)=2.17 (br s, 4H); 3.02 (s, 3H); 3.55-3.35 (m, 6H); 4.55-4.02 (m, 4H); 6.20 (m, 1H)

[0093] .sup.13C NMR (CDCl.sub.3)=21.1 (CH.sub.2); 48.4 (CH.sub.3); 62.3 (CH.sub.2); 62.5 (CH.sub.2); 65.54 (CH.sub.2); 89.0 (CH.sub.2); 120 (q, CF.sub.3); 150.3 (CH).

[0094] These results confirm that the product obtained is the ionic liquid having the formula defined above.

Example 4

[0095] In this example, the ionic liquids obtained in examples 2 and 3 are characterised in terms of conductivity (mS/cm) at 25 C., viscosity (mPa.Math.s) at 25 C. and crystallisation temperature ( C.).

The results are reported in the table below.

TABLE-US-00001 Crystallisation Ionic Conductivity Viscosity temperature liquid (mS/cm) (mPa .Math. s) ( C.) Example 2 4.7 79.2 65 Example 3 2.5 100.8 67

[0096] The ionic liquids have conductivity values higher than 2 mS/cm and melting temperatures lower than 20 C. Hence, these ionic liquids are of a very particular interest for use in electrochemical storage systems.