CA2321373A1 - Fluorinated sulfonamides as low-flammability solvents for use in electrochemical cells - Google Patents

Abstract

The invention relates to fluorinated sulfonamides as low-flammability solvents for electrolytes for use in electrochemical cells.

Description

Fluorinated sulfonamides as low-flammability solvents for use in electrochemical cells The invention relates to fluorinated sulfonamides as low-flammability solvents for electrolytes for use in electrochemical cells.
Lithium ion batteries. are amongst the most promising systems for mobile applications. The areas of applica-tion extend from high-quality electronic appliances (e.g. mobile phones, camcorders) to batteries for electrically driven motor vehicles.
These batteries consist of a cathode, an anode, a separator and a non-aqueous electrolyte. The cathodes used are typically Li (MnMeZ) Z04, Li (CoMeZ) O2, Li(CoNiXMeZ)02 or other lithium intercalation and insertion compounds. Anodes can consist of lithium metal, carbon materials, graphite, graphitic carbon materials or other lithium intercalation and insertion compounds or alloy compounds. The electrolytes used are solutions containing lithium salts, such as LiPF6, LiBFq, LiC104, LiAsF6, LiCF3S03, LiN (CF3S02) Z or LiC(CF3S02)3 and mixtures thereof, in aprotic solvents.
A great number of additives for use in lithium ion batteries is mentioned in the literature. For example, in EP 0759641 and US 5776627, organic aromatic compounds, such as biphenyl, substituted thiophenes and furans, and in EP 0746050 and EP 0851524, substituted anisole, mesitylene and xylene derivatives, are added to the electrolyte in order to increase the safety of the battery in the case of overcharging. For the same purpose, US 5753389 uses organic carbonates as additives. In order to improve the cycle stability, organic boroxines are added in EP 0856901. However, all these additives have some crucial disadvantages.
Organic substances, as used in the specifications mentioned here, generally have low flash points and low explosion limits.
Additive Explosion limit [$] Flash point [C]

Thiophene 1.5-12 -9 Anisole 0.34-6.3 43 Mesitylene 1-6 54 Furan 2.3-14.3 -35 According to the current state of the art, the electrolyte liquids used are preferably solvent mixtures comprising at least two components. The mixture has to include at least one strongly polar component which, owing to its polarity, has a strong dissociating effect on salts. Examples of these polar components are ethylene carbonate or propylene carbonate. Since these highly polar solvents are usually highly viscous, low-viscosity solvents are generally added to the electrolyte as "diluents". The diluents, typical examples of which are 1,2-~ CA 02321373 2000-09-27 dimethoxyethane, dimethyl carbonate or diethyl carbonate, are added in a proportion between 30 and 70%. A serious disadvantage of these low-viscosity solvents is their low flash point and their high volatility.
When electrolyte solutions are used electrochemically and to an even greater extent in the event of faults (short-circuiting, overcharging), warming always occurs, increasing the risk of ignition of the electrolyte.
To increase safety, cathode and anode spaces can be separated by a microporous separator membrane.
Furthermore, the safety of these cells can be increased by installing overpressure protection devices which react to gas evolution on overcharging.
Flame-retardant phosphorus- and halogen-containing additives are recommended, but these frequently have an adverse effect on the performance characteristics of the batteries.
However, all these measures cannot rule out the possibility that the volatile and flammable "diluent"
nevertheless ignites eventually in the event of malfunctions. Burning lithium reacts very violently not only with water but also with carbon dioxide.

' CA 02321373 2000-09-27 The object of the present invention is therefore to provide additives which have a low volatility and a relatively high flash point and are physically and chemically stable, sufficiently miscible with other suitable solvents and have a good conductivity behaviour.
The object according to the invention is achieved by compounds of the general formula X- ( CYZ ) m-SOzN ( CR1R2R3 ) 2 ( I ) where X is H, F, Cl, CnF2n+1i CnF2n-1 Or (S02) kN (CR1RZR3) 2r Y is H, F or Cl, Z is H, F or C1, R1, R2 and R3 are H and/or alkyl, fluoroalkyl or cycloalkyl, m is 0-9 and, if X = H, m ~ 0, n is 1-9, k is 0 if m = 0, and k = 1 if m = 1-9.

' CA 02321373 2000-09-27 The compounds of the formula (I) can be employed in electrochemical cells such as supercapacitors and primary or secondary lithium batteries, in particular as solvents.
It has been found that the compounds of the formula (I) have a low flammability. This makes it possible to reduce the risk of ignition in the event of faults.
Surprisingly, it has been found that the compounds of the formula (I) have a high electrochemical stability.
Experiments have shown that oxidative decomposition of an electrolyte which comprises a compound of the formula (I) and commonly used solvents (e. g. EC, DMC) and a typical conductive salt (e. g. LiPF6) occurs only once a potential of about 5.5 V against Li/Li+ has been reached.
It has been found that the compounds of the formula (I) are miscible with commonly used solvents. Neither phase separation nor crystallization of the conductive salt was observed.
The compounds of the formula (I) may also be used in electrolytes in the form of mixtures, in proportions between 1 and 100, preferably between 10 and 50~, with commonly used solvents such as EC, DMC, PC and DEC.

Electrolytes which can be used are solutions of LiPFs, LiBFq, LiClOq, LiAsF6, LiCF3S03, LiN (CF3S02) 2 or LiC(CF3S02)3 and mixtures thereof, in aprotic solvents such as EC, DMC, PC, DEC, BC, VC, cyclopentanone, sulfolane, DMS, 3-methyl-1,3-oxazolidin-2-one, y-butyrolactone, EMC, MPC, BMC, EPC, BEC, DPC, 1,2-diethoxymethane, THF, 2-methyltetrahydrofuran, 1,3-dioxolane, methyl acetate, ethyl acetate and mixtures thereof.
The electrolytes may further comprise organic isocyanates (DE 199 44 603) to reduce the water content. Likewise, the electrolytes may comprise organic alkali metal salts (DE 199 10 968) as additives. Suitable alkali metal salts are alkali metal borates of the general formula Li+B- ( OR1 ) m ( 0R2 ) p where m and p are 0, 1, 2, 3 or 4 with m + p = 4 and R1 and R2 are identical or different, if desired are joined directly to one another by a single or double bond, are, in each case individually or together, an aromatic or aliphatic carboxylic, dicarboxylic or sulfonic acid radical, or are, in each case individually or together, an aromatic ring selected from the group consisting of phenyl, naphthyl, anthracenyl and phenanthrenyl, which may be unsubstituted or monosubstituted to tetrasubstituted by A or Hal, or are, in each case individually or together, a heterocyclic aromatic. ring selected from the group consisting of pyridyl, pyrazyl and bipyridyl, which may be unsubstituted or monosubstituted to trisubstituted by A or Hal, or are, in each case individually or together, an aromatic hydroxy acid selected from the group consisting of aromatic hydroxycarboxylic acids and aromatic hydroxysulfonic acids, which may be unsubstituted or monosubstituted to tetrasubstituted by A or Hal, and Hal is F, C1 or Br and A is alkyl having from 1 to 6 carbon atoms, which may be monohalogenated to trihalogenated. Likewise suitable are alkali metal alkoxides (DE 9910968) of the general formula Li+OR-where R
is an aromatic or aliphatic carboxylic, dicarboxylic or sulfonic acid radical, or is an aromatic ring selected from the group consisting of phenyl, naphthyl, anthracenyl and phenanthrenyl, which may be unsubstituted or monosubstituted to tetrasubstituted by A or Hal, or is a heterocyclic aromatic ring selected from the group consisting of pyridyl, pyrazyl and bipyridyl, which may be unsubstituted or monosubstituted to trisubstituted by A or Hal, or is an aromatic hydroxy acid selected from the group consisting of aromatic hydroxycarboxylic acids and aromatic hydroxysulfonic acids, which may be unsubstituted or monosubstituted to tetrasubstituted by A or Hal, and Hal is F, C1 or Br, and A is alkyl having from 1 to 6 carbon atoms, which may be monohalogenated to trihalogenated.

' CA 02321373 2000-09-27 _ g _ The electrolytes may likewise comprise compounds of the general formula L ( LR1 (CRZR3) x] iAx) yKt] + -N (CF3) z where Kt is N, P, As, Sb, S or Se, A is N, P, P (0) , 0, S, S (0) , SOz, As, As (0) , Sb or Sb(0), R1, Rz and R3 are identical or different and are each H, halogen, substituted and/or unsubstituted alkyl CnHzn+i. substituted and/or unsubstituted alkenyl having 1-18 carbon atoms and one or more double bonds, substituted and/or unsubstituted alkynyl having 1-18 carbon atoms and one or more triple bonds, substituted and/or unsubstituted cycloalkyl CmHzm_1, mono- or polysubstituted and/or unsubstituted phenyl, substituted and/or unsubstituted heteroaryl, A can be included in R1, Rz and/or R3 in various positions, Kt can be included in a cyclic or heterocyclic ring, the groups bonded to Kt may be identical or different, where n is 1-18 m is 3-7 k is 0 or 1-6 1 is 1 or 2 in the case where x = 1 and 1 in the case where x = 0 x is 0 or 1 y is 1-4 (DE 9941566). The process for preparing the compounds is characterized in that an alkali metal salt of the general formula ~+ N (CF3) z where D+ is selected from the group consisting of the alkali metals, is reacted in a polar organic solvent with a salt of the general formula ~ C ~R1 (CRZR3) xl iAX) yKt] + -E
where Kt, A, R1, R2, R3, k, 1, x and y are as defined above and -E is F-, C1-, Br-, I-, BF4-, C104-, As F6-, SbF6- or PF6-.
Lithium complex salts of the formula Re R5 O~ ~~O
\ S~0 Li ~ ~~OR~
R4 ~ O~g 2 where R1 and R2 are identical or different, if desired are joined directly to one another by a single or double bond, and are, in each case individually or together, an aromatic ring selected from the group consisting of phenyl, naphthyl, anthracenyl and phenanthrenyl, which may be unsubstituted or monosubstituted to hexasubstituted by alkyl (C1 to C6), alkoxy groups (C1 to C6) or halogen (F, Cl, Br), or are, in each case individually or together, an aromatic heterocyclic ring selected from the group consisting of pyridyl, pyrazyl and pyrimidyl, which may be unsubstituted or monosubstituted to tetrasubstituted by alkyl (C1 to C6) , alkoxy groups (C1 to C6) or halogen (F, Cl, Br), or are, in each case individually or together, an aromatic ring selected from the group consisting of hydroxybenzenecarboxyl, hydroxynaphthalenecarboxyl, hydroxybenzenesulfonyl and hydroxynaphthalenesulfonyl, which may be unsubstituted or monosubstituted to tetrasubstituted by alkyl (C1 to C6) , alkoxy groups (C1 to C6) or halogen (F, C1, Br) , R3-R6 can, in each case individually or in pairs, if desired joined directly to one another by a single or double bond, have the following meanings:
1. alkyl (C1 to C6) , alkyloxy (C1 to C6) or halogen (F, Cl, Br) 2. an aromatic ring selected from the groups consisting of phenyl, naphthyl, anthracenyl and phenanthrenyl, which may be unsubstituted or monosubstituted to hexasubstituted by alkyl (C1 to C6), alkoxy groups (C1 to C6) or halogen (F, Cl, Br), pyridyl, pyrazyl and pyrimidyl, which may be unsubstituted or monosubstituted to tetrasubstituted by alkyl (C1 to C6) , alkoxy groups (C1 to C6) or halogen (F, C1, Br) , which are prepared by the following process (DE 199 32 317) a) 3-, 4-, 5-, 6-substituted phenol is admixed in a suitable solvent with chlorosulfonic acid, b) the intermediate from a) is reacted with chlorotrimethylsilane, and the product is filtered and subjected to fractional distillation, c) the intermediate from b) is reacted with lithium tetramethoxyborate(1-) in a suitable solvent and the end product is isolated therefrom, can also be present in the electrolyte.
Use can also be made of electrolytes comprising complex salts of the general formula (DE 199 51 804) M"+[EZ]v xiv where:
x, y are 1, 2, 3, 4, 5 or 6, M"+ is a metal ion, E is a Lewis acid selected from the group consisting of BR1RZR3, AlR1R2R3, PR1RZR3R4R5, AsR1R2R3R9R5 and VR1RZR3R9R5.
R1 to RS are identical or different, if desired are joined directly to one another by a single or double bond, and may be, in each case individually or together, a halogen ( F, C1, Br) , an alkyl or alkoxy radical (C1 to C$) which may be partially or fully substituted by F, C1, Br, an aromatic ring, if desired bonded via oxygen, selected from the group consisting of phenyl, naphthyl, anthracenyl and phenanthrenyl, which may be unsubstituted or monosubstituted to hexasubstituted by alkyl (C1 to C8) or F, C1, Br, an aromatic heterocyclic ring, if desired bonded via oxygen, selected from the group consisting of pyridyl, pyrazyl and pyrimidyl, which may be unsubstituted or monosubstituted to tetrasubstituted by alkyl (G1 to C$) or F, Cl, Br, and Z is OR6, NR6R', CR6R'Re, OSOZR6, N ( S02R6 ) ( S02R' ) , C ( SOZR6 ) ( SOZR' ) ( SOZR$ ) or OCOR6, where R6 to R8 are identical or different, if desired are joined directly to one another by a single or double bond, and are, in each case individually or together, a hydrogen or as defined for R1 to R5, prepared by reacting a corresponding boron or phosphorus Lewis acid-solvent adduct with a lithium or tetraalkyl-ammonium imide, methanide or triflate.
Borate salts (DE 199 59 722) of the general formula Ra R~ Y_ MX+ ~ B
R3 RZ "~Y
where:

M is a metal ion or tetraalkylammonium ion, x, y are 1, 2, 3, 4, 5 or 6, R1 to R4 are identical or different alkoxy or carboxyl radicals (C1-CB) which may be joined directly to one another by a single or double bond can also be present.
These borate salts are prepared by reacting lithium tetraalkoxyborate or a 1:1 mixture of lithium alkoxide and a boric ester in an aprotic solvent with a suitable hydroxyl or carboxyl compound in the ratio 2:1 or 4:1.
The novel compounds can also be used in electrolytes comprising lithium fluoroalkylphosphates of the following general formula Li+ [PFx (CyFZy+i-ZHZ) 6-xJ
where 1 <_ x <_ 5 3 <_ y <_ 8 0 <_ z <_ 2y + 1 and the ligands (CyF2y+i-zHZ) can be identical or different, with the exception of compounds of the general formula Li+ [ PFa (CHbF~ (CF3 ) d) e~
in which a is an integer from 2 to 5, b = 0 or 1, c = 0 or 1, d = 2 and a is an integer from 1 to 4, with the provisos that b and c are not simultaneously 0 and the sum of a + a is 6 and the ligands (CHbF~ (CF3) d) can be identical or different (DE 100 089 55). The process for preparing lithium fluoroalkylphosphates is characterized in that at least one compound of the general formula HmP ( CnH2n+1 ) 3-m ( I I I ) , OP (CnH2n+1) 3 ( IV) r C 1mP ( CnH2n+1 ) 3-m ( V ) r FmP (CnH2n+1) 3-m (VI) , Clop (CnH2n+1) 5-0 (VII ) Or FoP ( CnH2n+1 ) 5-0 ( VI I I ) , where in each case 0 < m < 2, 3 < n < 8 and 0 < o < 4, is fluorinated by electrolysis in hydrogen fluoride, the resulting mixture of fluorination products is fractionated by extraction, phase separation and/or distillation, and the resulting fluorinated alkylphosphorane is reacted with lithium fluoride in an aprotic solvent or solvent mixture in the absence of moisture, and the resulting salt is purified and isolated by customary methods.
The novel compounds can also be used in electrolytes comprising salts of the formula Li [ P ( OR1 ) a ( ORZ ) b ( OR3 ) c ( ~R4 ) dF'e ~
where 0 < a+b+c+d <_ 5 and a+b+c+d+e=6, and Rl to R4 are each, independently of one another, alkyl, aryl or heteroaryl radicals, it being possible for at least two of R1 to Rq to be j oined directly to one another by a single or double bond (DE 100 16801). These compounds are prepared by reacting phosphorus(V) compounds of the general formula P ( OR1 ) a ( ~RZ ) b ( ~R3 ) c ( OR9 ) dFe where 0 < a+b+c+d <_ 5 and a+b+c+d+e=5, and R1 to R4 are as defined above, with lithium fluoride in the presence of an organic solvent.

The novel compounds can be used in electrolytes for electrochemical cells which comprise anode material consisting of coated metal cores selected from the group consisting of Sb, Bi, Cd, In, Pb, Ga and tin or alloys thereof (DE 100 16 024). The process for preparing said anode material is characterized in that a) a suspension or a _sol of the metal core or alloy core is prepared in urotropine, b) the suspension is emulsified with C5-C12-hydro-carbons, c) the emulsion is precipitated onto the metal cores or alloy cores, and d) the metal hydroxides or oxyhydroxides are converted into the corresponding oxide by heat-treating the system.
The novel compounds can also be used in electrolytes for electrochemical cells comprising cathodes consisting of commonly used lithium intercalation and insertion compounds or else cathode materials consisting of lithium mixed oxide particles which are coated with one or more metal oxides (DE 199 22 522) by suspending the particles in an organic solvent, admixing the suspension with a solution of a hydrolysable metal compound and a hydrolysis solution and then filtering off, drying and, if desired, calcining the coated particles. They can also consist of lithium mixed oxide particles which are coated with one or more. polymers (DE 199 46 066) and are obtained by a process in which the particles are suspended in a solvent and the coated particles are subsequently filtered off, dried and, if desired, calcined.
Likewise, the novel compounds can be used in systems comprising cathodes which consist of lithium mixed oxide particles, which are singly or multiply coated with alkali metal compounds and metal oxides (DE 100 14 884). The process for preparing these materials is characterized in that the particles are suspended in an organic solvent, an alkali metal salt compound suspended in an organic solvent is added, metal oxides dissolved in an organic solvent are added, the suspension is admixed with a hydrolysis solution, and the coated particles are subsequently filtered off, dried and calcined.
The present invention accordingly provides electrolytes comprising compounds of the formula (I).
The present invention further provides electrochemical cells, in particular primary and secondary lithium batteries and supercapacitors, essentially consisting of a .corresponding electrolyte and a cathode, an anode and a separator.

In mixtures with commonly used conductive salts, the compounds of the general formula (I) have a good conductivity.
A general example of the invention is explained in greater detail below.
Preparation of compounds of the formula (I) An apparatus equipped with stirrer and cooling means is charged with dimethylamine in a suitable solvent.
Suitable solvents are organic solvents, for example diethyl ether or choloroform.
Partially fluorinated or perfluorinated alkylsulfonyl fluorides are added while stirring and cooling to temperatures between -30°C and 0°C. The reaction solution is then warmed to temperatures between room temperature and 40°C. The solvent is distilled off.
However, it is also possible to react halosulfonamides with commonly used fluorinating reagents, for example antimony trifluoride, arsenic trifluoride or potassium fluoride.
Halosulfonamides in suitable solvents, for example benzene, are refluxed for 1-4 hours, preferably for 2 hours, while stirring, with a fluorinating reagent in an apparatus equipped with condenser and stirrer. The reaction solution is cooled down to room temperature and then filtered. The solvent is distilled off and the residue is distilled under reduced pressure. The product is redistilled under atmospheric pressure if necessary.
Flammabilit The flammability of the compounds of the formula (I) was investigated. It was attempted to ignite compounds prepared according to the processes described above by means of an open flame. These attempts were unsuccessful.
Electrochemical stabilit Compounds of the formula (I) are added to an electrolyte consisting of commonly used conductive salts such as LiPF6, LiBF4, LiC104, LiAsF6, LiCF3S03, LiN (CF3SOZ) Z or LiC (CF3SOZ) 3 and mixtures thereof, in aprotic solvents such as EC, DMC, PC, DEC, BC, VC, cyclopentanone, sulfolane, DMS, 3-methyl-1,3-oxazolidin-2-one, 'y-butyrolactone, EMC, MPC, BMC, EPC, BEC, DPC, 1,2-diethoxymethane, THF, 2-methyltetra-hydrofuran, 1,3-dioxolane, methyl acetate, ethyl acetate and mixtures thereof. The proportion of the compounds of the formula (I) in the solvent mixture is between 1 and 1000.

In each case, 3-5 cyclic voltammograms were recorded successively in a measurement cell containing a stainless steel, platinum or gold working electrode, a lithium counterelectrode and a lithium reference electrode. To this end, starting from the rest potential, the potential was firstly increased at a rate of from 1 mV/s to 100 mV/s to voltages above the respective decomposition potential of the corresponding additive against Li/Li+, and then moved back to the rest potential.
The results show that oxidative decomposition of these electrolytes occurs only once a potential of about 5.0 V against Li/Li+ has been reached. They are therefore suitable for use in electrochemical cells.
Miscibility with standard solvents and resulting conductivities Incrementally increasing amounts of compounds of the formula (I) were added to a reference electrolyte consisting of LiPF6, LiBF9, LiC104, LiAsF6, LiCF3S03, LiN (CF3S02) 2 or LiC (CF3S02) 3 and mixtures thereof, in aprotic solvents such as EC, DMC, PC, DEC, BC, VC, cyclopentanone, sulfolane, DMS, 3-methyl-1,3-oxazolidin-2-one, y-butyrolactone, EMC, MPC, BMC, EPC, BEC, DPC, 1,2-diethoxymethane, THF, 2-methyltetra-hydrofuran, 1,3-dioxolane, methyl acetate, ethyl acetate and mixtures thereof.

Neither phase separations nor crystallizations of the conductive salt were observed. The compounds of the formula (I) are miscible with the reference electrolytes in any proportion.
Conductivity tests are carried out using a reference electrolyte at various_temperatures.
The following examples are intended to explain the invention in more detail without limiting it.
Examples Example 1 N,N-Dimethyltrifluoromethylsulfonamide The reaction is carried out in a three-neck flask equipped with cold trap, stirrer and means for introducing gaseous reagents. The cold trap is maintained at a temperature of -78°C. 250 cm3 of diethyl ether are introduced into the flask and cooled with ice-water. 138 g (3.07 mol) of gaseous dimethylamine, obtained from the reaction of 260 g (3.19 mol) of dimethylamine hydrochloride with 153 g (3.83 mol) of saturated sodium hydroxide solution and dried over potassium hydroxide, are condensed in the flask. 202 g (1.33 mol) of gaseous trifluoromethylsulfonyl fluoride are added in the course of 2 hours while stirring.
After addition of all reagents is complete, the reaction vessel is warmed to 40°C in the course of 2 hours. The reaction mixture is diluted with 0.5 1 of water and subsequently extracted with diethyl ether.
The extract is washed with water and dried over MgS04.
The diethyl ether is distilled off and the residue is distilled under atmospheric pressure.
230.4 g of N,N-dimethyltrifluoromethylsulfonamide are obtained.
Yield: 98%
CF3SOZN(CH3)Z: b.p.. 151-152°C
19F-NMR: -75.1 sep (CF3S02) 1H-NMR : 3 . 0 5 q ( 2 CH3 ) SJH,E ° 1.2 HZ
Example 2 N,N-Dimethylnonafluorobutylsulfonamide The reaction is carried out in a three-neck flask equipped with cold trap, stirrer and dropping funnel.
The cold trap is maintained at a temperature of -78°C.

100 g (0.331 mol) of perfluorobutylsulfonyl fluoride are slowly added to 43 g (0.95 mol) of liquid dimethylamine at -30°C while stirring. After addition is complete, the reaction mixture is warmed to room temperature and stirred for 3 hours . 0 . 1 1 of water is added and the resulting mixture is subsequently extracted with diethyl ether. The extract is washed with water and dried over Na2S0q. The solvent is distilled off.
114.5 g of white crystalline N,N-dimethylnonafluoro-butylsulfonamide are obtained.
Yield: 87.5 C4F9SOZN(CH3)2: m.p.. 32°C
19F-NMR: -81.5 tt (3F, CF3) -112.2 tm (2F, CFZ) -121.9 m (2F, CFZ) -126.4 tm (2F, CFz) 3Je,e = 2.2 Hz qJF,e = 9.9 Hz ' CA 02321373 2000-09-27 4JF,F = 13.9 Hz 1H-NMR : 3 . 1 s ( 2CH3 ) Example 3 Bis(N,N-dimethylamidosulfonyl)difluoromethane The reaction is carried out in a three-neck flask equipped with cold trap, stirrer and dropping funnel.
The cold trap is maintained at a temperature of -78°C.
99 g (0.458 mol) of di(fluorosulfonyl)difluoromethane are slowly added to 101 g (2.084 mol) of liquid dimethylamine in 100 cm3 of chloroform at -30°C while stirring. After addition is complete, the reaction mixture is warmed to room temperature and stirred for 3 hours. The solvent is distilled off 0.3 1 of water is added to the residue and the resulting mixture is subsequently extracted with diethyl ether. The extract is washed with water and dried over Na2S0q. About 80~ of the solvent is distilled off.
91.2 g of white crystalline bis(N,N-dimethylamido-sulfonyl)difluoromethane are obtained.
Yield: 74.8a (CH3) ZNSOZCFzSO2N (CH3) 2: m. p. . 71-72 °C

. ' CA 02321373 2000-09-27 i9F-NMR: -100.4 m (2F, CFZ) 1H-NMR: 3.06 t (4CH3) SJH,F = 1.0 Hz Example 4 N,N-Dimethylamidosulfonyl fluoride The reaction is carried out in a two-neck flask equipped with stirrer and cooling means. 80 g (0.557 mol) of N,N-dimethylamidosulfonyl chloride in 100 crn3 of dry benzene are added to 66 g (0.369 mol) of antimony trifluoride. 5 cm3 of antimony pentachloride are added while stirring. The reaction mixture is refluxed for 2 hours. The solution is cooled to room temperature and filtered. The benzene is distilled off and the residue is distilled under reduced pressure.
Redistillation under atmospheric pressure afforded 53.8 g of pure N,N-dimethylamidosulfonyl fluoride (R. Heap, J. Chem. Soc. 1948, 1313).
Yield: 76%
FSOZN (CH3) 2: b.p. . 149-150°C
i9F-NMR: 33.0 sep ' CA 02321373 2000-09-27 2.0 HZ
Example 5 Flammability of N,N-dimethyltrifluoromethylsulfonamide It was attempted to ignite 100 ml of N,N-dimethyltrifluoromethyl.sulfonamide in air by means of an open flame. This attempt was unsuccessful.
Example 6 Electrochemical stability of N,N-dimethyltrifluoro-methvlsulfonamide 5 cyclic voltammograms were recorded successively in a measurement cell containing a platinum electrode, a lithium counterelectrode and a lithium reference electrode. To this end, starting from the rest potential, the potential was firstly increased at a rate of 10 mV/s to 6 V against Li/Li+, and then moved back to the rest potential.
The characteristic profile shown in Fig. 1 is obtained.
Oxidative decomposition of the electrolyte, consisting of 1 mol/1 of LiPF6 in EC/DMC/N,N-dimethyltrifluoro-methylsulfonamide (47.5/47.5/5), occurs only once a potential of about 5.5 V against Li/Li+ has been reached. The electrolyte is therefore suitable for use ' CA 02321373 2000-09-27 in lithium ion batteries comprising a transition metal cathode.
Example 7 Miscibility with standard solvents and resulti conductivities Incrementally increasing amounts of N,N-dimethyltri-fluoromethylsulfonamide are added to a reference electrolyte (1 mol/1 of LiPF6 in EC/DMC (1:1)). The fluorinated solvent is miscible with the reference electrolyte in any proportion. Neither phase separation nor crystallization of the conductive salt was observed.
Conductivity data:
Electrolyte: 1 mol/1 of LiPF6 in EC/DMC/N,N-dimethyl-trifluoromethylsulfonamide (47.5/47.5/5) Temperature in C 20 -20 -30 Conductivity in mS/cm 8.6 2.9 2.1

Claims (9)

1. Compounds of the formula X-(CYZ)m-SO2N-(CR1R2R3)2 (I) where X is H, F, Cl, C n F2n+1, C n F2n-1 or (SO2)k N(CR1R2R3)2, Y is H, F or Cl, Z is H, F or Cl, R1, R2 and R3 are H and/or alkyl, fluoroalkyl or cycloalkyl, m is 0-9 and, if X = H, m ~ 0, n is 1-9, k is 0 if m = 0, and k = 1 if m = 1-9.

2. Process for preparing compounds according to Claim 1, characterized in that partially fluorinated or perfluorinated alkylsulfonyl fluorides are reacted with dimethylamine in organic solvents.

3. Process for preparing compounds according to Claim 1, characterized in that halosulfonamide is reacted with commonly used fluorinating reagents in organic solvents.

4. Process according to Claim 2 or 3, characterized in that said organic solvents are selected from the group consisiting of diethyl ether, benzene and chloroform.

5. Use of the compounds according to Claim 1 as low-flammability solvent in electrolytes for electrochemical cells.

6. Use according to Claim 5, wherein said compounds are used together with other commonly used solvents.

7. Electrolyte, characterized in that it comprises one or more compounds according to Claim 1.

8. Electrochemical cell, essentially consisting of a cathode, an anode, a separator and an electrolyte according to Claim 7.

9. Lithium battery and supercapacitor according to Claim 8.