Sulfur-containing additives for electrochemical or optoelectronic devices

Abstract

The invention relates to sulfur-containing compounds of the formula I, to their preparation, and to their use as additives in electrochemical or electrooptical devices, more particularly in electrolytes for lithium batteries, lithium ion batteries, double layer capacitors, lithium ion capacitors, solar cells, electrochromic displays, sensors and/or biosensors.

Claims

1. An electrolyte additive comprising a compound of formula I
[K—(CH.sub.2)—(CH.sub.2).sub.u—SO.sub.3—(CH.sub.2).sub.v—R″].sup.+[A].sup.−  I, wherein u is 0, 1, 2, 3, 4, 5, 6 or 7 and where a CH.sub.2 group of the —(CH.sub.2).sub.u-alkylene chain may be replaced by O or may have a double bond, v is 0, 1, 2, 3 or 4, —SO.sub.3— is ##STR00043## R″ independently at each occurrence is a straight-chain or branched alkyl group having 1 to 20 C atoms, and may be unfluorinated, partly fluorinated or fully fluorinated, or is a straight-chain or branched alkenyl group having 2 to 20 C atoms and a double bond, a straight-chain or branched alkynyl group having 2 to 20 C atoms and a triple bond, or an aryl group having 6 to 12 C atoms, which group may be singly or multiply substituted by at least one selected from the group consisting of F, Cl, and a straight-chain or branched, partly fluorinated or fully fluorinated alkyl group having 1 to 8 C atoms, K is a cation selected from the group consisting of R.sub.3N.sup.+—*, R.sub.3P.sup.+—*, ##STR00044## wherein R independently at each occurrence is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl, wherein optionally a CH.sub.2 group, not directly joined to N or P, in the radicals R is replaced by O, Y is CH.sub.2, O, S or NR′, R′ is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl, A is an anion selected from the group consisting of [F.sub.zB(C.sub.mF.sub.2m+1).sub.4-z].sup.−, [F.sub.yP(C.sub.mF.sub.2m+1).sub.6-y].sup.−, [(C.sub.mF.sub.2m+1).sub.2P(O)O].sup.−, [C.sub.mF.sub.2m+1P(O)O.sub.2].sup.2−, [O—C(O)—C.sub.mF.sub.2m+1].sup.−, [N(C(O)—C.sub.mF.sub.2m+1).sub.2].sup.−, [N(S(O).sub.2—C.sub.mF.sub.2m+1).sub.2].sup.−, [N(C(O)—C.sub.mF.sub.2m+1)(S(O).sub.2—C.sub.mF.sub.2m+1)].sup.−, [N(C(O)—C.sub.mF.sub.2m+1)(C(O)F)].sup.−, [N(S(O).sub.2—C.sub.mF.sub.2m+1)(S(O).sub.2F)].sup.−, [N(S(O).sub.2F).sub.2].sup.−, [C(C(O)—C.sub.mF.sub.2m+1).sub.3].sup.−, [C(S(O).sub.2—C.sub.mF.sub.2m+1).sub.3].sup.−, [O—S(O).sub.2—C.sub.mF.sub.2m+1].sup.−, ##STR00045## m is 1, 2, 3, 4, 5, 6, 7 or 8, wherein optionally CF.sub.2 groups in the anions are replaced by O, S(O).sub.2, NR or CH.sub.2, z is 1,2 or 3, y is 1, 2, 3, 4, 5 or 6, X is B or Al, R.sup.1 and R.sup.2 are each independently of one another F, Cl, Br, I, a straight-chain or branched perfluoroalkyl group having 1 to 20 C atoms, a straight-chain or branched alkoxy group having 1 to 20 C atoms, which may be unfluorinated, partly fluorinated or fully fluorinated, or —O—C(O)— alkyl, where alkyl is a straight-chain or branched alkyl group having 1 to 20 C atoms, and may be unfluorinated, partly fluorinated or perfluorinated, and where ##STR00046## independently at each occurrence is a bidentate radical which derives from a 1,2- or 1,3-diol, from a 1,2- or 1,3-dicarboxylic acid or from a 1,2- or 1,3-hydroxycarboxylic acid, by entering of pairs of adjacent OH groups in the compound into one bond each to the central atom X, accompanied by formal elimination of two H atoms, wherein an electroneutrality of a corresponding salt thereof is observed.

2. The electrolyte additive according to claim 1, wherein v is 0.

3. The electrolyte additive according to claim 1, wherein u is 1, 2 or 3.

4. The electrolyte additive according to claim 1, wherein R″ is a straight-chain or branched alkyl group having 1 to 8 C atoms, and may be unfluorinated, partly fluorinated or fully fluorinated.

5. The electrolyte additive according to claim 1, wherein K is cation ##STR00047## and where [A].sup.− is selected from the group consisting of [O—S(O).sub.2—C.sub.mF.sub.2m+1].sup.− and [F.sub.zB(C.sub.mF.sub.2m+1).sub.4-z], wherein z=4.

6. The electrolyte additive according to claim 1, wherein A is an anion selected from the group consisting of [F.sub.zB(C.sub.mF.sub.2m+1).sub.4-z].sup.−, [F.sub.yP(C.sub.mF.sub.2m+1).sub.6-y].sup.−, [O—C(O)—C.sub.mF.sub.2m+1].sup.−, [N(S(O).sub.2—C.sub.mF.sub.2m+1).sub.2].sup.−, [N(S(O).sub.2F).sub.2].sup.−, ##STR00048## wherein m is 1, 2, 3, 4, 5, 6, 7 or 8, z is 1, 2 or 3, y is 3, 4, 5 or 6, X is B, R.sup.1 and R.sup.2 are each independently of one another F, a straight-chain or branched perfluoroalkyl group having 1 to 4 C atoms, a straight-chain or branched alkoxy group having 1 to 4 C atoms or —O—C(O)-alkyl, where alkyl is a straight-chain or branched alkyl group having 1 to 20 C atoms, and may be unfluorinated, partly fluorinated or perfluorinated, and where ##STR00049## independently at each occurrence is a bidentate radical which derives from a 1,2- or 1,3-diol, from a 1,2- or 1,3-dicarboxylic acid or from a 1,2- or 1,3-hydroxycarboxylic acid, by entering of pairs of adjacent OH groups in the compound into one bond each to the central atom X, accompanied by formal elimination of two H atoms.

7. A process for preparing a compound of formula I according to claim 1, wherein SO.sub.3 is substructure ##STR00050## the process comprising reacting a compound of formula (II)
K-1  (II), wherein K-1 is selected from the group consisting of R.sub.3N, R.sub.3P, ##STR00051## R independently at each occurrence is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl, and a CH.sub.2 group, not joined to N or P, in the radicals R may be replaced by O, Y is CH.sub.2, O, S or NR′, and R′ is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl, with a compound of formula (III),
Hal-(CH.sub.2)—(CH.sub.2).sub.u—OH  (III), wherein u is 1, 2, 3, 4, 5, 6 or 7, and a CH.sub.2 group, not attached to the oxygen, in the —(CH.sub.2).sub.u-alkylene chain may be replaced by O or may contain a double bond, and Hal is Cl, Br or I, to obtain a resultant intermediate compound of the formula (IV)
[K—(CH.sub.2)—(CH.sub.2).sub.u—OH].sup.+[Hal].sup.−  (IV), reacting the resultant intermediate compound of formula (IV) with a compound of formula (V)
R″—(CH.sub.2).sub.v—SO.sub.2-L  (V), wherein L is a leaving group selected from a straight-chain or branched alkoxy group having 1 to 3 C atoms, Cl or F, with acid catalysis in the case of the alkoxy group as leaving group, or in the presence of a base in the case of Cl or F as leaving group, to obtain a resulting compound of formula (VI)
[K—(CH.sub.2)—(CH.sub.2).sub.u—SO.sub.3—(CH.sub.2).sub.v—R″].sup.+[Hal].sup.−  (VI), and then reacting the resulting compound of formula (VI) in a metathesis reaction with a compound of formula (VII),
[Kt].sup.+[A].sup.−  (VII), wherein [Kt].sup.+ is an alkali metal cation or H.sup.+, and [A].sup.− has a definition indicated in claim 1.

8. A process for preparing a compound of formula I according to claim 1, wherein SO.sub.3 is substructure ##STR00052## and u is 2, 3, 4 or 5, the process comprising reacting a compound of formula (II)
K-1  (II), wherein K-1 is selected from the group R.sub.3N, R.sub.3P, ##STR00053## R independently at each occurrence is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl, and a CH.sub.2 group, not joined to N or P, in the radicals R may be replaced by O, Y is CH.sub.2, O, S or NR′, and R′ is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl, with a compound of formula (VIII) ##STR00054## wherein w is 1, 2, 3 or 4, to obtain an intermediate compound of formula (IX)
[K—(CH.sub.2)—(CH.sub.2).sub.u—SO.sub.3.sup.−]  (IX), subsequently reacting the intermediate compound of formula (IX) with an alkylating agent of formula (X)
L*-(CH.sub.2).sub.v—R″  (X), wherein L* is CF.sub.3—S(O).sub.2O, C.sub.4F.sub.9—S(O).sub.2O, (C.sub.2F.sub.5).sub.2P(O)O, (C.sub.4F.sub.9).sub.2P(O)O, (alkyl).sub.2O.sup.+, alkyl-S(O).sub.2O, alkyl-O—S(O).sub.2O, I or Br, with alkyl independently at each occurrence being a straight-chain or branched alkyl group having 1 to 4 C atoms, to obtain a resulting compound of formula (XI)
[K—(CH.sub.2)—(CH.sub.2).sub.u—SO.sub.3—(CH.sub.2).sub.v—R″].sup.+[L*].sup.−  (XI), and then optionally reacting the resulting compound of formula (XI) with a compound of formula (VII),
[Kt].sup.+[A].sup.−  (VII), wherein [Kt].sup.+ is an alkali metal cation or H.sup.+, and [A].sup.− has a definition stated in claim 1.

9. A process for preparing a compound of formula I according to claim 1, where SO.sub.3 is substructure ##STR00055## the process comprising reacting a compound of formula (II)
K-1  (II), wherein K-1 is selected from the group consisting of R.sub.3N, R.sub.3P, ##STR00056## R independently at each occurrence is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl, and at least one CH.sub.2 group, not joined to N or P, in the radicals R may be replaced by O, Y is CH.sub.2, O, S or NR′, and R′ is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl, with a compound of formula (XII),
Hal-(CH.sub.2)—(CH.sub.2).sub.u-Hal  (XII), wherein u is 0, 1, 2, 3, 4, 5, 6 or 7, and a CH.sub.2 group, not attached to Hal, in the —(CH.sub.2).sub.u-alkylene chain may be replaced by O or may contain a double bond, and Hal is Cl, Br or I, to obtain a resultant intermediate compound of formula (XIII)
[K—(CH.sub.2)—(CH.sub.2).sub.u—Hal].sup.+[Hal].sup.−  (XIII), reacting the resultant intermediate compound of formula (XIII) with an alkali metal sulfite or ammonium sulfite and subsequently with a compound of formula (X)
L*-(CH.sub.2).sub.v—R″  (X), wherein L* is CF.sub.3—S(O).sub.2O, C.sub.4F.sub.9—S(O).sub.2O, (C.sub.2F.sub.5).sub.2P(O)O, (C.sub.4F.sub.9).sub.2P(O)O, (alkyl).sub.2O.sup.+, alkyl-S(O).sub.2O, alkyl-O—S(O).sub.2O, I or Br, with alkyl independently at each occurrence being a straight-chain or branched alkyl group having 1 to 4 C atoms, to obtain a resulting compound of formula (XI)
[K—(CH.sub.2)—(CH.sub.2).sub.u—SO.sub.3—(CH.sub.2).sub.v—R″].sup.+[L*].sup.−  (XI), and then optionally reacting the resulting compound of formula (XI) with a compound of formula (VII),
[Kt].sup.+[A].sup.−  (VII), wherein [Kt].sup.+ is an alkali metal cation or H.sup.+, and [A].sup.− has a definition stated in claim 1.

10. An electrolyte comprising the electrolyte additive according to claim 1, wherein [A].sup.− is selected from the group consisting of [O—S)O).sub.2.sup.−C.sub.mF.sub.2m+1].sup.+ wherein m=1, 2, 3, 4, 5, 6, 7 or 8 and [F.sub.zB(C.sub.mF.sub.2m+1).sub.4-z].sup.− wherein z=4.

11. The electrolyte according to claim 10, further comprising as conductive salt, a lithium salt, a tetraalkylammonium salt, or both.

12. The electrolyte according to claim 10, further comprising an additional additive.

13. An electrochemical or electrooptical device, comprising the electrolyte additive according to claim 1, wherein [A].sup.− is selected from the group consisting of [O—S(O).sub.2—C.sub.mF.sub.2m+1].sup.− wherein m=1, 2, 3, 4, 5, 6, 7 or 8 and [F.sub.zB(C.sub.mF.sub.2m+1).sub.4-z].sup.− wherein z=4.

14. The electrolyte additive according to claim 1, wherein [A].sup.− is selected from the group consisting of [O—S(O).sub.2—C.sub.mF.sub.2m+1].sup.− wherein m=1, 2, 3, 4, 5, 6, 7 or 8 and [F.sub.zB(C.sub.mF.sub.2m+1).sub.4-z].sup.− wherein z=4.

15. An electrochemical or electrooptical device comprising the electrolyte additive according to claim 1, wherein [A].sup.− is selected from the group consisting of [O—S(O).sub.2—C.sub.mF.sub.2m+1].sup.− wherein m=1, 2, 3, 4, 5, 6, 7 or 8 and [F.sub.zB(C.sub.mF.sub.2m+1).sub.4-z].sup.− wherein z=4.

16. The electrochemical or electrooptical device according to claim 15, wherein the electrochemical or electrooptical device is a device selected from the group consisting of a lithium battery, a lithium ion battery, a double layer capacitor, a lithium capacitor, a solar cell, an electrochromic display, a sensor and a biosensor.

Description

EXAMPLES

Example 1. Synthesis of 3-(1-methylpyrrolidinium-1-yl)propane-1-sulfonate

(1) ##STR00035##

(2) 23.8 g (195 mmol) of 1,3-propane sultone in 50 ml of toluene are admixed slowly dropwise with 16.8 g (197 mmol) of methylpyrrolidine, with cooling in an ice bath. The precipitate is isolated by filtration, washed twice with toluene, and dried under reduced pressure (10.sup.−3 hPa). This gives 37.1 g of 3-(1-methylpyrrolidinium-1-yl)-propane-1-sulfonate in the form of a hygroscopic, colorless solid. The yield is 92%.

(3) .sup.1H NMR (solvent: D.sub.2O), δ (ppm): 3.98 (m, 6H); 3.55 (s, 3H); 3.42 (t, J=7.2 Hz, 2H); 2.74 (m, 6H).

(4) .sup.13C{.sup.1H} NMR (solvent: D.sub.2O), δ (ppm): 64.5 s; 62.4 s; 48.1 s; 47.5 s; 21.3 s; 19.3 s.

Example 2. Synthesis of 1-(3-(methoxysulfonyl)propyl)-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate

(5) ##STR00036##

(6) 6.3 g (30.3 mmol) of 3-(1-methylpyrrolidinium-1-yl)propane-1-sulfonate are suspended in 10 ml of acetonitrile, and 5.6 g (34.0 mmol) of methyl triflate are added. The solid dissolves completely in an exothermic reaction, and the reaction mixture is stirred at room temperature for three hours. On addition of 14.7 g (30.3 mmol) of potassium tris(pentafluoroethyl)trifluorophosphate (KFAP) in 50 ml of ice-cold water, a coarse precipitate is formed. The solid is isolated, washed with four times 40 ml of water, and dried in a desiccator. This gives 19.2 g of 1-(3-(methoxysulfonyl)propyl)-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate in the form of a pale yellow solid. The yield is 95%.

(7) .sup.1H NMR (solvent: CD.sub.3CN), δ (ppm): 3.91 (s, 3H); 3.44 (m, 4H); 3.36 (m, 2H); 3.24 (t, J=7.4 Hz, 2H); 2.97 (s, 3H); 2.25 (m, 2H); 2.19 (m, 4H).

(8) .sup.13C{.sup.1H} NMR (cation) (solvent: CD.sub.3CN), δ (ppm): 64.7; 61.6; 56.7; 48.2; 45.2; 21.2; 18.5.

(9) Elemental analysis; calculated (found), %: C, 27.00 (27.22), H, 3.02 (3.02), N, 2.10 (2.07), S, 4.80 (4.85).

Example 3. Synthesis of 1-(2-hydroxyethyl)-1-methylpyrrolidinium chloride

(10) ##STR00037##

(11) 14.8 g (174 mmol) of methylpyrrolidine are heated in 20 ml of chloroethanol at 70° C. for 7 hours. The clear, pale yellow solution is admixed with 25 ml of diethyl ether, causing the product to precipitate. The precipitate is isolated by filtration and washed with diethyl ether, to give 28 g of 1-(2-hydroxyethyl)-1-methylpyrrolidinium chloride in the form of a pale yellow, waxlike solid. The yield is 97%.

(12) .sup.1H NMR (solvent: CD.sub.3CN), δ (ppm): 6.05 (t, J=5.7 Hz, 1H); 3.91 (m, 2H); 3.62 (m, 4H); 3.52 (m, 2H); 3.15 (s, 3H); 2.14 (m, 4H).

(13) .sup.13C{.sup.1H} NMR (solvent: CD.sub.3CN), δ (ppm): 66.6 s; 66.2 s; 56.9 s; 49.5 s; 22.3 s.

Example 4. Synthesis of 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium chloride

(14) ##STR00038##

(15) 5.3 g (32 mmol) of 1-(2-hydroxyethyl)-1-methylpyrrolidinium chloride are taken up in 25 ml of dichloromethane and admixed with 4.6 g (35.7 mmol) of diisopropyl ethylamine. Subsequently 5 g (43 mmol) of methanesulfonyl chloride are added slowly dropwise, with cooling in an ice bath, the temperature being held below 15° C. The product is precipitated in the form of a colorless solid and after a reaction time of four hours is isolated by filtration. This gives 5.2 g of 1-methyl-1-(2-(methylsulfoxy)ethyl)pyrrolidinium chloride. The yield is 66%.

(16) .sup.1H NMR (solvent: DMSO-D.sub.6), δ (ppm): 4.75 (m, 2H); 3.94 (m, 2H); 3.61 (m, 4H); 3.38 (s, 3H); 3.13 (s, 3H); 2.09 (m, 4H).

(17) .sup.13C{.sup.1H} NMR (solvent: DMSO-D.sub.6), δ (ppm): 64.9 s; 64.6 s; 61.7 s; 48.2 s; 37.7 s; 21.3 s.

Example 5. Synthesis of 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium tris(pentafluoroethyl)trifluorophosphate

(18) ##STR00039##

(19) 5.2 g (21 mmol) of 1-methyl-1-(2-(methylsulfoxy)ethyl)pyrrolidinium chloride are dissolved in 20 ml of ice-cold water, and 9.7 g (20 mmol) of KFAP are added in the form of an aqueous solution. The resulting precipitate is isolated by filtration, washed with five times 30 ml of ice-cold water, and dried in a desiccator. This gives 12.6 g of 1-methyl-1-(2-(methylsulfonyloxy)ethyl)-pyrrolidinium tris(pentafluoroethyl)trifluorophosphate in the form of a pale pink solid. The yield is 96%.

(20) .sup.1H NMR (solvent: CD.sub.3CN), δ (ppm): 4.59 (m, 2H); 3.68 (m, 2H); 3.52 (m, 4H); 3.13 (s, 3H); 3.03 (s, 3H); 2.19 (m, 4H).

(21) .sup.13C{.sup.1H} NMR (cation) (solvent: CD.sub.3CN), δ (ppm): 66.9 s; 64.7 s; 63.8 s; 50.0 s; 38.3 s; 22.4 s.

Example 6. Synthesis of 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium-bis(oxalatoborate)

(22) ##STR00040##

(23) The synthesis takes place in the same way as for Example 5, by reaction with lithium bis(oxalato)borate. Yield is 86%.

(24) .sup.1H NMR (solvent: DMSO-D.sub.6), δ (ppm): 4.68 (m, 2H); 3.81 (m, 2H); 3.54 (m, 4H); 3.31 (s, 3H); 3.06 (s, 3H); 2.11 (m, 4H).

(25) .sup.11B NMR (solvent: DMSO-d.sub.6) δ (ppm): 7.4 (s),

Example 7. Alternative Synthesis of 3-(1-methylpyrrolidinium-1-yl)propane-1-sulfonate

(26) ##STR00041##

(27) 16.1 g (79.6 mmol) of 1,3-dibromopropane are dissolved in 25 ml of THF, and 6.0 g (70.6 mmol) of methylpyrrolidine are added. As early as toward the end of the addition, a finely divided, colorless precipitate is formed. The mixture is stirred at room temperature for 25 hours and the colorless precipitate is isolated by filtration. This gives 17.2 g of 1-(3-bromopropyl)-1-methylpyrrolidinium bromide in the form of a colorless, hygroscopic solid. Yield 85%.

(28) .sup.1H NMR (solvent: CD.sub.3CN), δ (ppm): 3.59 (m, 8H), 3.09 (s, 3H), 2.35 (m, 2H), 2.16 (m, 4H).

(29) .sup.13C{.sup.1H} NMR (solvent: CD.sub.3CN), δ (ppm): 65.8, 63.6, 49.7, 30.9, 28.2, 22.7.

(30) An aqueous solution of 1-(3-bromopropyl)-1-methylpyrrolidinium bromide (1.9 g; 6.5 mmol) is admixed with 1.0 g of sodium sulfite (8.3 mmol) and heated at 85° C. for three hours. The solvent is removed under reduced pressure, to give 3-(1-methylpyrrolidinium)propane-1-sulfonate in the form of a colorless solid. The conversion is quantitative.

(31) NMR corresponds to the product from the reaction of methylpyrrolidine with 1,3-propane sultone (Example 1).

Example 8. Synthesis of 1-(bromomethyl)-1-methylpyrrolidinium bromide

(32) ##STR00042##

(33) 21.5 g (123.7 mmol) of dibromomethane are dissolved in 20 ml of THF, and 9.6 g (112.7 mmol) of methylpyrrolidine are added. As early as toward the end of the addition, a finely divided, colorless precipitate is formed. The mixture is stirred at room temperature for 16 hours and the colorless precipitate is isolated by filtration and washed with THF. This gives 4.8 g of 1-(bromomethyl)-1-methylpyrrolidinium bromide in the form of a colorless, hygroscopic solid. Yield 16%.

(34) The yield is increased by longer reaction time. From a solution at rest, the product is obtained in the form of fine needles.

(35) .sup.1H NMR (solvent: DMSO-D.sub.6), δ (ppm): 5.56 (s, 2H), 3.68 (m, 4H), 3.21 (s, 3H), 2.15 (m, 4H). .sup.13C{.sup.1H} NMR (solvent: DMSO-D.sub.6), δ (ppm): 63.9 s, 57.4 s, 48.7 s, 21.8 s.

(36) Electrochemical Characterization:

(37) Test Setup

(38) The test cells used are lithium ion cells consisting of a graphite electrode, a polyolefin-based separator, and an LiNiMnCoO.sub.2 electrode (electrode area 25 cm.sup.2 each, pouch cell construction). Prior to the building of the test cells, both electrodes are dried at 120° C. under reduced pressure, and the separator at 50° C. without reduced pressure, for at least 24 hours.

(39) Test Cell Building:

(40) The anode is placed centrally onto the laminated aluminum foil, so that the current collector protrudes about 20 mm beyond the foil. The cathode is placed onto the anode in such a way that the anode forms a uniform frame around the cathode. A second laminated aluminum foil is placed such that the two foils lie congruently over one another. In order to avoid short circuits, a PE film is placed in each case between current collector and laminated aluminum foil. At the top edge, a weld seam is put in place with welding tongs (temperature 225° C.), so that the electrode stack can no longer slip. Under an inert gas atmosphere of argon, both electrodes are wetted with 1 ml each of the test electrolyte, and a polyolefin separator, placed beforehand for 5 minutes in a Petri dish filled with electrolyte, is placed between anode and cathode. The left-hand and right-hand sides of the test cell are welded shut with welding tongs (225° C.). Using the vacuum welding apparatus, the test cell is evacuated and sealed. Voltage and resistance of the test cell are checked with a commercial multimeter, and are between −0.200 to 0.200 V and between 0.05 and 1 Ohm, respectively. Cells which lie outside of the values are not used.
Measurement Program All test cells are cycled between 3.0 V and 4.2 V at 25° C. The current rates used in this case are as follows: Phase 1: Cycle 1-50: Charge rate: 0.3C Discharge rate 0.3C Phase 2: Cycle 51: Charge rate: 1C Discharge rate 1C Cycle 52: Charge rate: 1C Discharge rate 2C Cycle 53: Charge rate: 1C Discharge rate 4C Cycle 54: Charge rate: 1C Discharge rate 6C Cycle 55: Charge rate: 1C Discharge rate 8C Cycle 56: Charge rate: 1C Discharge rate 10C Phase 3: Cycle 57-107: Charge rate: 1C Discharge rate 1C Further phases: As for phases 2 and 3 The following parameters are recorded per cycle: Charge capacity and discharge capacity in mAh Internal resistance in the charged state (4.2V) Internal resistance in the uncharged state (3V)

(41) The measuring instrument/cycler used is a commercial device from the company BaSyTec.

Example A: Reference/Comparative System

(42) The abovementioned test setup is produced with the electrolyte system 1M LiPF.sub.6 in EC:DMC (1:1) (EC=ethylene carbonate, DMC—dimethyl carbonate).

(43) The durability (1C-10C—The discharge capacity at 1C is taken as 100%) is shown by FIG. 1.

(44) The tables below show the results:

(45) Table 1 shows the results of the loading test:

(46) TABLE-US-00001 C rate 1 C 2 C 4 C 6 C 8 C 10 C Relative discharge capacity 100% 96% 85% 64% 48% 35%

(47) FIG. 2 shows the profile of the internal resistance in the uncharged state (3.0V).

(48) Table 2 is a summary of the cycling test (the discharge capacity in the 10th cycle is taken as 100%)

(49) TABLE-US-00002 Cycle 50 100 200 300 400 500 Rel. discharge capacity 99 94 93 93 92 91 % Internal resistance at 0.9 1.0 1.1 1.3 1.4 1.6 Ohms 3.0 V Internal resistance at 3.7 3.6 3.8 4.2 4.7 4.9 Ohms 4.2 V

(50) Table 3 is a summary of the relative discharge capacity at 10C (the discharge capacity of the 1st 1C discharging is taken as 100%)

(51) TABLE-US-00003 Number of repetition of the loading test 1 2 3 4 5 6 7 Relative discharge capacity 35 30 30 25 25 23 20 % at 10 C

(52) In summary, for the first loading with 10C, a derivable capacity of just 35% is found (FIG. 1). This falls with increasing repetition of the load. In the case of the 7th run (about 500th cycle, FIG. 2) a derivable capacity of only about 20% is measured. Even after the first strong loading of 10C, the cell does not achieve the capacity figures measured beforehand (FIG. 2). At the same time it is notable that the internal resistance in the charged state rises slightly over the number of cycles (FIG. 3), and rises sharply in the uncharged state (FIG. 4).

Example B: Electrolyte comprising 1-(3-(methoxysulfonyl)propyl)-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate

(53) The above test setup is implemented with the electrolyte system 1M LiPF.sub.6 in EC:DMC (1:1)+1% 1-(3-(methoxysulfonyl)propyl)-1-methylpyrrolidinium-tris(pentafluoroethyl)trifluorophosphate.

(54) FIGS. 3 and 4 and also Tables 4 to 6 show the results.

(55) FIG. 3 shows the 1C to 10C durability: the discharge capacity at 10 is taken as 100%.

(56) Table 4 shows the results of the loading test:

(57) TABLE-US-00004 C rate 1 C 2 C 4 C 6 C 8 C 10 C Relative discharge capacity 100% 97% 89% 70% 48% 32%

(58) The profile of the internal resistance in the uncharged state (3V) is shown by FIG. 4.

(59) Table 5 provides a summary of the cycling test (the discharge capacity in the 10th cycle is taken as 100%).

(60) TABLE-US-00005 Cycle 50 100 200 300 400 Rel. discharge capacity 100 98 98 99 98 % Internal resistance at 3 V 0.94 0.95 0.99 1.02 1.05 Ohms Internal resistance at 4.2 V 2.07 2.14 1.99 2.02 2.14 Ohms

(61) Table 6 gives a summary of the relative discharge capacity at 10C (the discharge capacity of the 1st 1C discharge is taken as 100%).

(62) TABLE-US-00006 Number of repetition of the loading test 1 2 3 4 5 6 7 Relative discharge capacity 32 25 28 25 27 26 25 % at 10 C

(63) In summary, for the first loading with 10C, a derivable capacity of 32% is found (FIG. 5). In contrast to the situation with the reference, the drop is significantly less with increasing repetition of the loading, and even after the 7th run (400 cycles) it still achieves 25%. Under the same conditions, the reference falls to 20%.

(64) In contrast to the situation in the reference cell (Example A), the capacity measured in the first cycles is regained even after multiple loading with 10C. The cell ages much more slowly and exhibits amazingly low capacity fading.

(65) Striking at the same time is the very constant profile of the internal resistances. In the discharged state in particular, the internal resistance remains very constant over 400 cycles, and shows a reduction by a factor of 2 in comparison to the reference.

Example C: Electrolyte comprising 1-methyl-1-(2-(methylsulfoxy)ethyl)-pyrrolidinium tris(pentafluoroethyl)trifluorophosphate

(66) The above test setup is implemented with the electrolyte system 1M LiPF.sub.6 in EC:DMC (1:1)+1% 1-methyl-1-(2-(methylsulfoxy)ethyl)-pyrrolidinium tris(pentafluoroethyl)trifluorophosphate.

(67) FIGS. 5 and 6 and also Tables 7 to 9 show the results.

(68) FIG. 5 shows the 1C to 10C durability: the discharge capacity at 1C is taken as 100%.

(69) Table 7 shows the results of the loading test:

(70) TABLE-US-00007 C rate 1 C 2 C 4 C 6 C 8 C 10 C Relative discharge capacity 100% 98% 90% 71% 54% 43%

(71) The profile of the internal resistance in the uncharged state (3.0V) is shown by FIG. 6.

(72) Table 8 provides a summary of the cycling test (the discharge capacity in the 10th cycle is taken as 100%).

(73) TABLE-US-00008 Cycle 50 100 200 300 400 Rel. discharge capacity 100 98 96 95 95 % Internal resistance at 3.0 V 0.9 0.9 1.0 1.0 1.1 Ohms Internal resistance at 4.2 V 3.6 2.1 2.2 2.3 2.3 Ohms

(74) Table 9 gives a summary of the relative discharge capacity at 10C (the discharge capacity of the 1st 1C discharge is taken as 100%).

(75) TABLE-US-00009 Number of repetition of the loading test 1 2 3 4 5 6 Relative discharge capacity at 10 C 43 42 39 39 35 36 %

(76) In summary, in the first loading with 10C, a derivable capacity is found which is much higher in comparison to the reference, of 43% (FIG. 5).

(77) At the same time, as for example B, the very constant profile of the internal resistances is striking. In particular in the discharged state, as with example B, the internal resistance is situated at very low values, and well below the reference (reduction by a factor of 2).

(78) With this additive as well, a significantly lower ageing and capacity fading is achieved.

Example D: Electrolyte comprising 1-methyl-1-(2-(methylsulfoxy)ethyl)-pyrrolidinium-bis(oxalato)borate

(79) The above test setup is implemented with the electrolyte system 1M LiPF.sub.6 in EC:DMC (1:1)+1% 1-methyl-1-(2-(methylsulfoxy)ethyl)-pyrrolidinium-bis(oxalato)borate.

(80) FIGS. 7 and 8 and also Tables 10 to 12 show the results.

(81) FIG. 7 shows the 1C to 10C durability: the discharge capacity at 1C is taken as 100%.

(82) Table 10 shows the results of the loading test:

(83) TABLE-US-00010 C rate 1 C 2 C 4 C 6 C 8 C 10 C Relative discharge capacity 100% 98% 85% 68% 52% 40%

(84) The profile of the internal resistance in the uncharged state (3.0V) is shown by FIG. 8.

(85) Table 11 provides a summary of the cycling test (the discharge capacity in the 10th cycle is taken as 100%).

(86) TABLE-US-00011 Cycle 50 100 200 300 400 Rel. discharge capacity 98 97 96 96 % Internal resistance at 3.0 V 0.99 0.98 0.99 0.99 Ohms Internal resistance at 4.2 V 2.2 2.1 2.0 2.0 Ohms

(87) Table 12 shows the summary of the relative discharge capacity at 10C (the discharge capacity of the 1st 1C discharge is taken as 100%).

(88) TABLE-US-00012 Number of repetition of the loading test 1 2 3 4 Relative discharge capacity at 10 C 40 39 39 38 %

(89) Similarly to the situation in examples B and C, for the loading with 10C, a derivable capacity is found which is much higher in comparison to the reference, of 40%. At the same time, as for example B and C, the very constant profile of the internal resistances is striking. The internal resistance particularly in the discharged state is well below the reference.

INDEX TO THE FIGURES

(90) FIG. 1 shows the 1C to 10C durability of the reference system 1M LiPF.sub.6 in EC:DMC (1:1).

(91) FIG. 2 shows the profile of the internal resistance in the uncharged state (3.0V) of the reference system 1M LiPF.sub.6 in EC:DMC (1:1).

(92) FIG. 3 shows the 1C to 10C durability of example B 1M LiPF.sub.6 in EC:DMC (1:1), 1% 1-(3-(methoxysulfonyl)propyl)-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate.

(93) FIG. 4 shows the profile of the internal resistance in the uncharged state (3.0V) of the example B 1M LiPF.sub.6 in EC:DMC (1:1), 1% 1-(3-(methoxysulfonyl)propyl)-1-methylpyrrolidinium-tris(pentafluoroethyl)trifluorophosphate.

(94) FIG. 5 shows the 1C to 10C durability of example C 1M LiPF.sub.6 in EC:DMC (1:1), 1% 1-methyl-1-(2-(methylsulfoxy)ethyl)pyrrolidinium tris(pentafluoroethyl)trifluorophosphate.

(95) FIG. 6 shows the profile of the internal resistance in the uncharged state (3.0V) of the example C 1M LiPF.sub.6 in EC:DMC (1:1), 1% 1-methyl-1-(2-(methylsulfoxy)ethyl)-pyrrolidinium-tris(pentafluoroethyl)trifluorophosphate.

(96) FIG. 7 shows the 1C to 10C durability of example D 1M LiPF.sub.6 in EC:DMC (1:1), 1% 1-methyl-1-(2-(methylsulfoxy)ethyl)pyrrolidinium bis(oxalato)borate.

(97) FIG. 8 shows the profile of the internal resistance in the uncharged state (3.0V) of the example D 1M LiPF.sub.6 in EC:DMC (1:1), 1% 1-methyl-1-(2-(methylsulfoxy)ethyl)pyrrolidinium bis(oxalato)borate.