Tetrakis fluoroalkylborate salts and their use as electrolyte salts

The present invention relates to tetrakisfluoroalkylborate salts, processes for their preparation and their use in electrolytes, batteries, capacitors, supercapacitors and galvanic cells.

The spread of portable electronic devices such as laptop and palmtop computers, cell phones or video cameras and with it the need for light and powerful batteries has increased dramatically worldwide in recent years.

In view of this surge in demand for batteries and the associated ecological problems, the development of rechargeable batteries with a long service life is becoming increasingly important.

Rechargeable lithium ion batteries have been commercially available since the early 1990s. Most of these batteries work with lithium hexafluorophosphate as the conductive salt. However, this lithium salt represents an extremely hydrolysis-sensitive compound with a low thermal stability, so that the corresponding lithium batteries can only be produced by very complex and therefore also very cost-intensive processes due to these properties of the salt. The sensitivity of this lithium salt also reduces the life and performance of these lithium batteries and also impairs their use under extreme conditions, such as high temperatures.

There has been no shortage of attempts to provide lithium salts with improved properties. No. 4,505,997 and US Pat. No. 9,202,966 describe the use of lithium [bis (trifluoromethylsulfonyl) imide] and lithium [tris (trifluoromethylsulfonyl) methanide] salts as conductive salts in batteries. Both salts show high anodic stability and form solutions with high conductivity with organic carbonates. However, lithium [bis (trifluoromethylsulfonyl) imide] has the disadvantage that it does not passivate the aluminum metal, which acts as a cathodic current conductor in lithium batteries, to a sufficient degree. Lithium [tris (trifluoromethylsulfonyl) methanide], on the other hand, can only be produced and cleaned with very great effort, so that the use of this salt as a conductive salt in batteries greatly increases the production costs for such lithium batteries.

Another lithium salt that is used in battery cells is lithium tetrafluoroborate. However, this salt is only relatively poorly soluble in most solvents, so that its solutions generally have only a low ionic conductivity.

It was therefore the object of the present invention to provide conductive salts which show no or only the slightest signs of hydrolytic decomposition over a long period of time. Furthermore, these conductive salts should also have high ionic conductivity, high thermal stability and good to very good solubility in the common solvents. Another object of the present invention was to extend or improve the life and performance of primary and secondary batteries, capacitors, supercapacitors and / or galvanic cells.

This object is achieved by the provision of tetrakisfluoroalkyl borate salts of the general formula (I)         M^{n +} ([BR₄]^-)_n     (I) wherein M^{n +} is a monovalent, divalent or trivalent cation, the ligands R are in each case identical and straight-chain or branched and for (C_xF_{2x + 1}) with 1 ≤ x ≤ 8 and n = 1, 2 or 3.

Tetrakisfluoroalkylborate salts of the general formula (I) in which the cation M^{n +} is an alkali metal cation, preferably a lithium, sodium or potassium cation, particularly preferably a lithium cation, a magnesium or aluminum cation.

Furthermore, tetrakisfluoroalkylborate salts of the general formula (I) are preferred, in which the cation M^{n +} an organic cation, preferably a nitrosyl cation, a nitryl cation or a cation of the general formula [N (R⁷)₄]⁺, [P (N (R⁷)₂)_kR_4-k]⁺ with 0 ≤ k ≤ 4 or [C (N (R⁷)₂)₃]⁺ is, the radicals R⁷, are the same or different, and for H,         C._OF_{2o + 1-pq}H_pA_qor A stand wherein 1 o o 10 10, 0 p p 2 2o + 1 and 0 + q 2 2o + 1, preferably 1 o o 6 6, 0 p p 2 2o + 1 and 0 q q 2 2o + 1, and A are each one optionally aromatic heteroatoms or a preferably 5- or 6-membered cycloalkyl radical.

As aromatic or cycloaliphatic radical A, which may optionally have heteroatoms, all known to the person skilled in the art for the preparation of [N (R⁷)₄]⁺, [P (N (R⁷)₂)_kR_4-k]⁺ with 0 ≤ k ≤ 4 or [C (N (R⁷)₂)₃]⁺Cations suitable aromatics, heteroaromatics or cycloaliphatics are used. A is preferably a 5- or 6-membered aromatic radical which may have nitrogen and / or sulfur and / or oxygen atoms, particularly preferably a phenyl or pyridine radical.

In a further preferred embodiment of the present invention, the cation M^{n +} a heteroaromatic cation selected from the group of heteroaromatic cations of the general formulas (II) to (IX):<chemistry id="chem0001" num="0001"><img file="EP1205480A2_D0001.tif" /></chemistry><chemistry id="chem0002" num="0002"><img file="EP1205480A2_D0002.tif" /></chemistry><chemistry id="chem0003" num="0003"><img file="EP1205480A2_D0003.tif" /></chemistry><chemistry id="chem0004" num="0004"><img file="EP1205480A2_D0004.tif" /></chemistry>

The leftovers R¹ to R⁶, which can in each case be the same or different, stand for an H radical, a halogen radical, preferably a fluorine radical, or for a C._1-8-Alkyl radical, which may be substituted with the substituents F, Cl, N (C_aF_{(2a + 1-b)}H_b)₂, O (C_aF_{(2a + 1-b)}H_b), SO₂(C._aF_{(2a + 1-b})H_b) or C_aF_{(2a + 1-b)}H_b can be substituted, in which 1 ≤ a ≤ 6 and 0 ≤ b ≤ 2a + 1.

Two of the residues R¹ to R⁶ together a C_1-8-Alkyl radical, which may be substituted with the substituents F, Cl, N (C_aF_{(2a + 1-b)}H_b)₂, O (C_aF_{(2a + 1-b)}H_b), SO₂(C._aF_{(2a + 1-b)}H_b) or C_aF_{(2a + 1-b)}H_b can be substituted, in which 1 ≤ a ≤ 6 and 0 ≤ b ≤ 2a + 1.

Also preferred are tetrakisfluoroalkyl borate salts of the general formula (I), in which the ligands R are in each case the same and for (C_xF_{2x + 1}) and x = 1 or 2. Those tetrakisfluoroalkylborate salts in which the ligands R are the same and for a CF are particularly preferred₃-Rest stand.

The salts of the general formula (I) according to the invention can be used both in pure form and in the form of their mixtures as conductive salts in electrolytes, primary and secondary batteries, capacitors, supercapacitors and / or galvanic cells. It is also possible to use the salts according to the invention in a mixture with other lithium salts known to the person skilled in the art as conductive salts.

They can be used in proportions between 1 and 99% in combination with other conductive salts that are used in electrochemical cells. For example, conductive salts selected from the group LiPF are suitable₆, LiBF₄, LiClO₄, LiAsF₆, LiCF₃SO₃, LiN (CF₃SO₂)₂ or LiC (CF₃SO₂)₃ and mixtures of at least two of these compounds.

The salts of the formula (I) and their mixtures can also be used in electrolytes for electrochemical cells. The electrolytes can also contain organic isocyanates (DE 199 44 603) to reduce the water content. Also compounds of the general formula         [([R¹(CR²R³)_k]_lA_x)_yKt]^{+ -}N (CF₃)₂in which<dl id="dl0001" compact="compact"><dt>Kt</dt><dd>N, P, As, Sb, S, Se</dd><dt>A</dt><dd>N, P, P (O), O, S, S (O), SO₂, As, As (O), Sb, Sb (O)</dd></dl> R¹, R² and R³the same or different H, halogen, substituted and / or unsubstituted alkyl C_nH_{2n + 1}, substituted and / or unsubstituted alkenyl with 1-18 carbon atoms and one or more double bonds, substituted and / or unsubstituted alkynyl with 1-18 carbon atoms and one or more triple bonds, substituted and / or unsubstituted cycloalkyl C_mH_2m-1 , mono- or polysubstituted and / or unsubstituted phenyl, substituted and / or unsubstituted heteroaryl, A can be in different positions in R¹, R² and / or R³ be trapped Kt can be enclosed in a cyclic or heterocyclic ring, the groups bonded to Kt can be the same or different with<dl id="dl0002" compact="compact"><dt>n</dt><dd>1-18</dd><dt>m</dt><dd>3-7</dd><dt>k</dt><dd>0, 1-6</dd><dt>l</dt><dd>1 or 2 in the case of x = 1 and 1 in the case of x = 0</dd><dt>x</dt><dd>0,1</dd><dt>y</dt><dd>1-4</dd></dl> mean, can be included (DE 9941566). The process for the preparation of the compounds is characterized in that an alkali salt of the general formula         D^{+ -}N (CF₃)₂with D⁺ selected from the group of alkali metals in a polar organic solvent with a salt of the general formula         [([R¹(CR²R³)_k]_lA_x)_yKt]^{+ -}E in which Kt, A, R¹, R², R³, k, l, x and y have the meaning given above and ^-E F^-, Cl^-, Br^-, I^-, BF₄^-, ClO₄^-, AsF₆^-, SbF₆^- or PF₆^-means is implemented. The compounds according to the invention can also be contained in electrolytes, the compounds of the formula         X- (CYZ)_m-SO₂N (CR¹R²R³)₂With<dl id="dl0003" compact="compact"><dt>X</dt><dd>H, F, Cl, C_nF_{2n + 1}, C_nF_2n-1, (SO₂)_kN (CR¹R²R³)₂</dd><dt>Y</dt><dd>H, F, Cl</dd><dt>Z.</dt><dd>H, F, Cl</dd><dt>R¹, R², R³</dt><dd>H and / or alkyl, fluoroalkyl, cycloalkyl</dd><dt>m</dt><dd>0-9 and if X = H, m ≠ 0</dd><dt>n</dt><dd>1-9</dd><dt>k</dt><dd>0 if m = 0 and k = 1 if m = 1-9</dd></dl> contain, represented by the fact that partially or perfluorinated alkysulfonyl fluorides are reacted with dimethylamine in organic solvents (DE 199 466 73).

Also lithium complex salts of the formula<chemistry id="chem0005" num="0005"><img file="EP1205480A2_D0005.tif" /></chemistry> in which R¹ and R² are the same or different, optionally connected directly to one another by a single or double formation, in each case individually or together, the meaning of an aromatic ring from the group phenyl, naphthyl, anthracenyl or phenanthrenyl, which is unsubstituted or mono- to six-fold by alkyl (C₁ to C₆), Alkoxy groups (C₁ to C₆) or halogen (F, Cl, Br) may have substituted, or in each case individually or jointly the meaning of an aromatic heterocyclic ring from the group pyridyl, pyrazyl or pyrimidyl which is unsubstituted or one to four times by alkyl (C.₁ to C₆), Alkoxy groups (C₁ to C₆) or halogen (F, Cl, Br) may have substituted, or in each case individually or jointly the meaning of an aromatic ring from the group hydroxylbenzoecarboxyl, hydroxylnaphthalenecarboxyl, hydroxylbenzenesulfonyl and hydroxylnaphthalenesulfonyl, which is unsubstituted or one to four times by alkyl (C₁ to C₆), Alkoxy groups (C₁ to C₆) or halogen (F, Cl, Br) may have substituted, R³-R⁶ can have the following meaning individually or in pairs, if necessary directly connected to one another by a single or double bond:<ul id="ul0001" list-style="none" compact="compact"><li>1. Alkyl (C₁ to C₆), Alkyloxy (C₁ to C₆) or halogen (F, Cl, Br)</li><li>2nd an aromatic ring from the groups</li></ul> Phenyl, naphthyl, anthracenyl or phenanthrenyl, which is unsubstituted or one to six times by alkyl (C₁ to C₆), Alkoxy groups (C₁ to C₆) or halogen (F, Cl, Br) can be substituted, Pyridyl, pyrazyl or pyrimidyl, which is unsubstituted or one to four times by alkyl (C₁ to C₆), Alkoxy groups (C₁ to C₆) or halogen (F, Cl, Br) can be substituted, which are shown using the following method (DE 199 32 317)<ul id="ul0002" list-style="none" compact="compact"><li>a) 3-, 4-, 5-, 6-substituted phenol is mixed with chlorosulfonic acid in a suitable solvent,</li><li>b) the intermediate product from a) is reacted with chlorotrimethylsilane, filtered and fractionally distilled,</li><li>c) the intermediate from b) with lithium tetramethanolate borate (1-), reacted in a suitable solvent and the end product is isolated therefrom may be present in the electrolyte.</li></ul>

Also electrolytes with complex salts of the general formula (DE 199 51 804)         M^{x +}[EZ]^y-_{x / y}in which mean:<dl id="dl0004" compact="compact"><dt>x, y</dt><dd>1,2,3,4,5,6</dd><dt>M^{x +}</dt><dd>a metal ion</dd><dt>E</dt><dd>a Lewis acid selected from the group</dd></dl> BR¹R²R³, AlR¹R²R³, PR¹R²R³R⁴R⁵, AsR¹R²R³R⁴R⁵, VR¹R²R³R⁴R⁵, R¹ to R⁵ the same or different, optionally connected directly to one another by a single or double formation, each individually or jointly the meaning a halogen (F, Cl, Br), an alkyl or alkoxy radical (C₁ to C₈) which can be partially or completely substituted by F, Cl, Br, of an aromatic ring, optionally bonded via oxygen, from the group phenyl, naphthyl, anthracenyl or phenanthrenyl, which is unsubstituted or one to six times by alkyl (C₁ to C₈) or F, Cl, Br can be substituted of an aromatic heterocyclic ring, optionally bonded via oxygen, from the group pyridyl, pyrazyl or pyrimidyl, which is unsubstituted or one to four times by alkyl (C₁ to C₈) or F, Cl, Br can be substituted, and<dl id="dl0005" compact="compact"><dt>Z.</dt><dd>OR⁶, NO⁶R⁷, CR⁶R⁷R⁸, OSO₂R⁶, N (SO₂R⁶)(SO₂R⁷), C (SO₂R⁶)(SO₂R⁷)(SO₂R⁸), OCOR⁶, in which</dd></dl> R⁶ to R⁸ are the same or different, optionally connected directly to one another by a single or double bond, each individually or jointly the meaning of a hydrogen or the meaning like R¹ to R⁵ which have been prepared by reacting a corresponding boron or phosphorus-Lewis acid solvent adduct with a lithium or tetraalkylammonium imide, methanide or triflate can be used. Also borate salts (DE 199 59 722) of the general formula in which mean:<chemistry id="chem0006" num="0006"><img file="EP1205480A2_D0006.tif" /></chemistry><dl id="dl0006" compact="compact"><dt>M</dt><dd>a metal ion or tetraalkylammonium ion</dd><dt>x, y</dt><dd>1, 2, 3, 4, 5 or 6</dd></dl> R¹ to R⁴ the same or different, optionally by a single or double bond directly linked alkoxy or carboxy radicals (C₁-C₈) can be included. These borate salts are prepared by reacting lithium tetraalcoholate borate or a 1: 1 mixture of lithium alcoholate with a boric acid ester in an aprotic solvent with a suitable hydroxyl or carboxyl compound in a ratio of 2: 1 or 4: 1.

Also additives such as silane compounds of the general formula         SiR¹R²R³R⁴with R¹ to R⁴   H         C._yF_{2y + 1-z}H_e.g.        OC_yF_{2y + 1-z}H_e.g.        OC (O) C_yF_{2y + 1-z}H_e.g.        OSO₂C._yF_{2y + 1-z}H_e.g.and<maths id="math0001" num=""><math display="block"><mrow><mtext>1≤x &lt;6</mtext></mrow></math><img file="EP1205480A2_D0007.tif" /></maths><maths id="math0002" num=""><math display="block"><mrow><mtext>1≤y≤8</mtext></mrow></math><img file="EP1205480A2_D0008.tif" /></maths> and<maths id="math0003" num=""><math display="block"><mrow><mtext>0≤z≤2y + 1</mtext></mrow></math><img file="EP1205480A2_D0009.tif" /></maths> and R¹-R⁴ the same or different with the meaning of an aromatic ring from the group phenyl, naphthyl which is unsubstituted or one or more times by F, C_yF_{2y + 1-z}H_e.g. or OC_yF_{2y + 1-z}H_e.g., OC (O) C_yF_{2y + 1-z}H_e.g., OSO₂C._yF_{2y + 1-z}H_e.g., N (C_nF_{2n + 1-z}H_e.g.)₂ can be substituted, or with the meaning of a heterocyclic aromatic ring from the group pyridyl, pyrazyl or pyrimidyl, each with one or more F, C_yF_{2y + 1-z}H_e.g. or OC_yF_{2y + 1-z}H_e.g., OC (O) C_yF_{2y + 1-z}H_e.g., OSO₂C._yF_{2y + 1-z}H_e.g., N (C_nF_{2n + 1-z}H_e.g.)₂ may be substituted (DE 100 276 26) may be included.

The compounds according to the invention can also be used in electrolytes which contain lithium fluoroalkyl phosphates of the following formula         Li⁺[PF_x(C._yF_{2y + 1-z}H_e.g.)_6-x]^-wherein<maths id="math0004" num=""><math display="block"><mrow><mtext>1 ≤ x ≤ 5</mtext></mrow></math><img file="EP1205480A2_D0010.tif" /></maths><maths id="math0005" num=""><math display="block"><mrow><mtext>3rd ≤ y ≤ 8</mtext></mrow></math><img file="EP1205480A2_D0011.tif" /></maths><maths id="math0006" num=""><math display="block"><mrow><mtext>0 ≤ z ≤ 2y + 1</mtext></mrow></math><img file="EP1205480A2_D0012.tif" /></maths> mean and the ligands (C_yF_{2y + 1-z}H_e.g.) may be the same or different, the compounds of the general formula         Li⁺[PF_a(CH_bF_c(CF₃)_d)_e]^-

in which a is an integer from 2 to 5, b = 0 or 1, c = 0 or 1, d = 2 and e is an integer from 1 to 4, with the conditions that b and c are not simultaneously = 0 mean and the sum of a + e is 6 and the ligands (CH_bF_c(CF₃)_d) may be the same or different, except (DE 100 089 55). The process for the preparation of lithium fluoroalkylphosphates is characterized in that at least one compound of the general formula         H_mP (C_nH_{2n + 1})_{3 m}     (III),         OP (C_nH_{2n + 1})₃     (IV),         Cl_mP (C_nH_{2n + 1})_{3 m}     (V),         F_mP (C_nH_{2n + 1})_{3 m}     (VI),         Cl_OP (C_nH_{2n + 1})_5-o     (VII),         F_OP (C_nH_{2n + 1})_5-o     (VIII), in each of which 0 &lt;m &lt;2, 3 &lt;n &lt;8 and 0 &lt;o &lt;4 means is fluorinated by electrolysis in hydrogen fluoride, the mixture of the fluorination products thus obtained is separated by extraction, phase separation and / or distillation, and the fluorinated alkylphosphorane thus obtained is reacted with lithium fluoride in an aprotic solvent or solvent mixture with exclusion of moisture, and the salt thus obtained is purified and isolated by the usual methods. The compounds according to the invention can also be used in electrolytes, the salts of the formula         Li [P (OR¹)_a(OR²)_b(OR³)_c(OR⁴)_dF_e] where 0 &lt;a + b + c + d ≤ 5 and a + b + c + d + e = 6, and R¹ to R⁴ are independently alkyl, aryl or heteroaryl radicals, at least two of R¹ to R⁴ can be directly connected to one another by a single or double bond, contain (DE 100 16 801). The compounds are represented by reacting phosphorus (V) compounds of the general formula         P (OR¹)_a(OR²)_b(OR³)_c(OR⁴)_dF_ewhere 0 &lt;a + b + c + d ≤ 5 and a + b + c + d + e = 5, and R¹ to R⁴ have the meanings given above with lithium fluoride in the presence of an organic solvent.

Also ionic liquids of the general formula         K⁺A^-in which mean:<dl id="dl0007" compact="compact"><dt>K⁺</dt><dd>a cation selected from the group</dd></dl><chemistry id="chem0007" num="0007"><img file="EP1205480A2_D0013.tif" /></chemistry><chemistry id="chem0008" num="0008"><img file="EP1205480A2_D0014.tif" /></chemistry><chemistry id="chem0009" num="0009"><img file="EP1205480A2_D0015.tif" /></chemistry><chemistry id="chem0010" num="0010"><img file="EP1205480A2_D0016.tif" /></chemistry> where R¹ to R⁵ the same or different, optionally directly connected to each other by a single or double bond and each individually or together have the following meaning:<ul id="ul0003" list-style="dash" compact="compact"><li>H,</li><li>Halogen,</li><li>Alkyl radical (C₁ to C₈) partially or completely by further groups, preferably F, Cl, N (C_nF_{(2n + 1-x)}H_x)₂, O (C_nF_{(2n + 1-x)}H_x), SO₂(C._nF_{(2n + 1-x)}H_x), C_nF_{(2n + 1-x)}H_x can be substituted with 1 &lt;n &lt;6 and 0 &lt;x≤13</li></ul> and<dl id="dl0008" compact="compact"><dt>A^-</dt><dd>an anion selected from the group</dd></dl>         [BORON¹)_n(OR²)_m(OR³)_O(OR⁴)_p]^-with 0≤n, m, o, p≤4 and m + n + o + p = 4 where R¹ to R⁴ are different or in pairs the same, optionally connected directly to one another by a single or double formation, in each case individually or together the meaning of an aromatic ring from the group phenyl, naphthyl, anthracenyl or phenanthrenyl, which is unsubstituted or one or more times by C_nF_{(2n + 1-x)}H_x can be substituted with 1 &lt;n &lt;6 and 0 &lt;x≤13 or halogen (F, Cl, Br), the meaning of an aromatic heterocyclic ring from the group pyridyl, pyrazyl or pyrimidyl, which is unsubstituted or one or more times by C_nF_{(2n + 1-x)}H_x can be substituted with 1 &lt;n &lt;6 and 0 &lt;x≤13 or halogen or halogen (F, Cl, Br), the importance of an alkyl group (C₁ to C₈) partially or completely by further groups, preferably F, Cl,, N (C_nF_{(2n + 1-x)}H_x)₂, O (C_nF_{(2n + 1-x)}H_x), SO₂(C._nF_{(2n + 1-x)}H_x), C_nF_{(2n + 1-x)}H_x can be substituted with 1 &lt;n &lt;6 and 0 &lt;x≤13, or OR¹ to OR⁴individually or jointly the meaning of an aromatic or aliphatic carboxyl, dicarboxyl, oxysulfonyl or oxycarboxyl radicals, which is partially or completely replaced by further groups, preferably F, Cl,, N (C_nF_{(2n + 1-x)}H_x)₂, O (C_nF_{(2n + 1-x)}H_x), SO₂(C._nF_{(2n + 1-x)}H_x), C_nF_{(2n + 1-x)}H_x can be substituted with 1 &lt;n &lt;6 and 0 &lt;x≤13 (DE 100 265 65), can be contained in the electrolyte. Ionic liquids K⁺A^- with K⁺ defined as above and<dl id="dl0009" compact="compact"><dt>A^-</dt><dd>an anion selected from the group</dd></dl><chemistry id="chem0011" num="0011"><img file="EP1205480A2_D0017.tif" /></chemistry> and    1≤ x &lt;6    1≤ y ≤ 8 and    0≤ z ≤ 2y + 1 can be included (DE 100 279 95).

The compounds according to the invention can be used in electrolytes for electrochemical cells which contain anode material consisting of coated metal cores selected from the group Sb, Bi, Cd, In, Pb, Ga and tin or their alloys (DE 100 16 024). The process for producing this anode material is characterized in that<ul id="ul0004" list-style="none" compact="compact"><li>a) a suspension or a sol of the metal or alloy core is produced in urotropin,</li><li>b) the suspension with hydrocarbons with C₅-C₁₂ be emulsified</li><li>c) the emulsion is struck on the metal or alloy cores and</li><li>d) the metal hydroxides or metal oxides are converted into the corresponding oxide by tempering the system.</li></ul>

The compounds according to the invention can also be used in electrolytes for electrochemical cells, with cathodes made from common lithium intercalation and insertion compounds, but also with 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, the suspension is mixed with a solution of a hydrolyzable metal compound and a hydrolysis solution and then the coated particles are filtered off, dried and optionally calcined. They can also consist of lithium mixed oxide particles which are coated with one or more polymers (DE 199 46 066), obtained by a process in which the particles are suspended in a solvent and then the coated particles are filtered off, dried and optionally be calcined. The compounds according to the invention can likewise be used in systems with cathodes which consist of lithium mixed oxide particles which are coated one or more times with alkali metal compounds and metal oxides (DE 100 14 884). The process for the preparation of these materials is characterized in that the particles are suspended in an organic solvent, an alkali metal salt compound is added suspended in an organic solvent, metal oxides dissolved in an organic solvent are added, the suspension is mixed with a hydrolysis solution and then the coated Particles are filtered off, dried and calcined. The compounds according to the invention can likewise be used in systems which contain anode materials with doped tin oxide (DE 100 257 61). This anode material is made by<ul id="ul0005" list-style="none" compact="compact"><li>a) a tin chloride solution is mixed with urea,</li><li>b) the solution is mixed with urotropin and a suitable doping compound,</li><li>c) the sol thus obtained is emulsified in petroleum ether,</li><li>d) the gel obtained is washed and the solvent is suctioned off and</li><li>e) the gel is dried and tempered.</li></ul>

The compounds according to the invention can also be used in systems which contain anode materials with reduced tin oxide (DE 100 257 62). This anode material is made by<ul id="ul0006" list-style="none" compact="compact"><li>a) a tin chloride solution is mixed with urea,</li><li>b) the solution is mixed with urotropin,</li><li>c) the sol thus obtained is emulsified in petroleum ether,</li><li>d) the gel obtained is washed and the solvent is suctioned off,</li><li>e) the gel is dried and tempered and</li><li>f) the SnO obtained₂ is exposed to a reducing gas flow in a fumigable furnace.</li></ul>

The salts according to the invention are preferably used in pure form as conductive salts, since particularly good reproducibility of the electrochemical properties can be ensured in this way.

Another object of the invention is also a process for the preparation of tetrakisfluoroalkyl borate salts according to the invention of the general formula (I), in which the ligands R are identical in each case and for a CF.₃-Rest stand.

In this process, at least one salt of the general formula (X),         M^{n +} ([B (CN)₄]^-)_n     (X) where M^{n +} and n have the meaning given above, fluorinated by reaction with at least one fluorinating agent in at least one solvent and the fluorinated compound of the general formula (I) thus obtained is purified and isolated by customary methods known to the person skilled in the art.

The tetrakisfluoroalkylborate salts obtained in this way often have a purity of&gt; 99% immediately after the fluorination. If this should be necessary, the salts can be further purified by customary methods known to those skilled in the art, for example by recrystallization in a suitable solvent or solvent mixture. The person skilled in the art can select suitable solvents or solvent mixtures by means of simple preliminary tests.

The synthesis of the compounds of the general formula (X) can be carried out analogously to that described in E. Bernhardt, G. Henkel, H. Willner Z. Anorg. General Chem., 2000, Vol. 626, page 560 published method. This literature is hereby introduced as a reference and is considered part of the disclosure.

In the process according to the invention, the reaction with the fluorinating agent is preferably carried out at a temperature in the range from -80 to + 20 ° C., particularly preferably at a temperature in the range from -60 ° C. to 0 ° C.

Fluorine, chlorofluoride, chlorotrifluoride, chloropentafluoride, bromotrifluoride, bromopentafluoride or a mixture of at least two of these fluorinating agents are preferably used as suitable fluorinating agents in the process according to the invention. Chlorine fluoride, chlorine trifluoride or a mixture of at least two fluorinating agents containing chlorine fluoride and / or chlorine trifluoride are particularly preferably used.

Hydrogen fluoride, iodine pentafluoride, dichloromethane, chloroform or a mixture of at least two of these solvents is preferably used as a suitable solvent for the fluorination of the salts of the general formula (X). Hydrogen fluoride is particularly preferably used as a solvent.

The tetrakisfluoroalkylborate salts of the general formula (I) according to the invention are also suitable for use in solid electrolytes. For the purposes of the invention, solid electrolytes are understood to mean both polymer electrolytes which usually have an optionally crosslinked polymer and a conductive salt, and also gel electrolytes which usually additionally contain at least one solvent in addition to an optionally crosslinked polymer and a conductive salt.

Another object of the present invention is therefore also containing a mixture<ul id="ul0007" list-style="none"><li>a) at least one tetrakisfluoroalkyl borate salt of the general formula (I) and</li><li>b) at least one polymer.</li></ul>

A mixture in the sense of the present invention comprises pure mixtures of components a) and b), mixtures in which the salt of component a) is included in the polymer of component b) and mixtures in which between the salt of component a) and the polymer of component b) chemical and / or physical bonds exist.

In a preferred embodiment of the present invention, the mixture according to the invention contains 5 to 99% by weight of component a) and 95 to 1% by weight of component b), particularly preferably 60 to 99% by weight of component a) and 40 up to 1% by weight of component b). The weight ratios given relate to the sum of components a) and b).

As component b) the mixture according to the invention preferably contains a homopolymer or copolymer of unsaturated nitriles, preferably acrylonitrile, vinylidenes, preferably vinylidene difluoride, acrylates, preferably methyl acrylate, methacrylates, preferably methyl methacrylate, cyclic ethers, preferably tetrahydrofuran, alkylene oxides, preferably ethylene oxide, siloxane, phosphazene Alkoxysilanes or at least one organically modified ceramic or a mixture of at least two of the above-mentioned homopolymers and / or copolymers and optionally at least one organically modified ceramic.

Preferred organically modified ceramics are inorganic-organic hybrid polymers which are obtained by hydrolysis and condensation of organically modified silicon alkoxides and subsequent crosslinking of the crosslinkable groups attached to the inorganic framework. Corresponding organically modified ceramics are marketed for example under the name ORMOCERE®.

Component b) is particularly preferably a homopolymer or copolymer of vinylidene difluoride, acrylonitrile, methyl (meth) acrylate, tetrahydrofuran, very particularly preferably a homopolymer or copolymer of vinylidene difluoride.

These homopolymers and copolymers of vinylidene difluoride are marketed under the names Kynar® and Kynarflex® by Atofina Chemicals, Inc. and under the name Solef® by Solvay.

The polymers used according to the invention can also be at least partially crosslinked. Crosslinking can be carried out using known crosslinking agents by customary methods known to those skilled in the art. The crosslinking can also take place in the presence of component a) and, if appropriate, further components.

In addition to the tetrakisfluoroalkyl borate salts of the general formula (I) and the polymers, the mixture according to the invention can additionally have a solvent or a solvent mixture of two or more solvents.

Preferred solvents are organic carbonates, preferably ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or methyl propyl carbonate, organic esters, preferably methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, γ-ether, preferably diethyl ether, organic ether , Dimethoxyethane, diethoxyethane, organic amides, preferably dimethylformamide or dimethylacetamide, sulfur-containing solvents, preferably dimethyl sulfoxide, dimethyl sulfite, diethyl sulfite or propane sultone, aprotic solvents, preferably acetonitrile, acrylonitrile or acetone, or at least partially fluorinated derivatives of the abovementioned solvents or mixtures of at least two of these solvents and / or fluorinated derivatives of these solvents .

The present invention also relates to a process for the preparation of the mixtures according to the invention, according to which at least one of the abovementioned tetrakisfluoroalkylborate salts of the general formula (I) and at least one polymer and optionally at least one solvent are mixed with one another.

These components are preferably mixed at elevated temperature, particularly preferably at 20 to 90 ° C., very particularly preferably at 40 to 60 ° C., the temperatures being able to vary depending on the components used.

Another object of the present invention is the use of at least one tetrakisfluoroalkyl borate salt according to the invention or a mixture according to the invention in electrolytes, primary batteries, secondary batteries, capacitors, supercapacitors and / or galvanic cells, optionally also in combination with other known conductive salts and / or Additives.

The tetrakisfluoroalkyl borate salts according to the invention are also suitable for the polymerization of olefins. They are also suitable for the preparation of catalytically active compounds in which the tetrakisfluoroalkylborate anions then act as counterions to the cationic catalysts. The use of the tetrakisfluoroalkylborate salts according to the invention for the polymerization of olefins and for the preparation of catalysts is therefore also an object of the present invention.

The invention further relates to electrolytes, primary and secondary batteries, capacitors, supercapacitors and galvanic cells which contain at least one tetrakisfluoroalkylborate salt of the general formula (I) according to the invention or a mixture according to the invention and optionally further conductive salts and / or additives. Other conductive salts and additives are known to the person skilled in the art, for example from Doron Auerbach, Nonaqueous Electrochemistry, Marc Dekker Inc., New York 1999; D. Linden, Handbook of Batteries, Second Edition, McGraw-Hill Inc., New York 1995 and G. Mamantov and AI Popov, Chemistry of Nonaqueous Solutions, Current Progress, VCH Verlagsgesellschaft, Weinheim 1994. They are hereby introduced as a reference and are considered part of the disclosure.

Electrolytes according to the invention preferably have a concentration of the tetrakisfluoroalkyl borate salts (s) according to the invention of 0.01 to 3 mol / l, preferably 0.01 to 2 mol / l, particularly preferably 0.1 to 1.5 mol / l .

As a solvent for the salts according to the invention, the electrolytes preferably contain organic carbonates, preferably ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or methyl propyl carbonate, organic esters, preferably methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate Butyrolactone, organic ethers, preferably diethyl ether, dimethoxyethane, diethoxyethane, organic amides, preferably dimethylformamide or dimethylacetamide, sulfur-containing solvents, preferably dimethyl sulfoxide, dimethyl sulfite, diethyl sulfite or propane sultone, aprotic solvents, preferably acetonitrile, acrylonitrile or acetone, or at least partially fluorinated derivatives of the abovementioned solvents or mixtures of at least two of these solvents and / or fluorinated Derivatives of these solvents.

The tetrakisfluoroalkylborate salts according to the invention and the mixtures according to the invention have the advantage that they show no or almost no signs of decomposition in the presence of water over a very long period of time and have good to very good solubility in most solvents or solvent mixtures.

Furthermore, they have high thermal stability and high chemical stability both in the solid and in the dissolved state. The salts and mixtures according to the invention are stable, for example, against strong oxidizing agents, such as fluorine.

These properties make it possible to use electrolytes, batteries, capacitors, supercapacitors and galvanic cells containing these conductive salts under extreme conditions, such as at high temperatures, without their service life and performance being impaired by these conditions.

Furthermore, the corresponding batteries, capacitors, supercapacitors and galvanic cells are characterized by very good voltage stability, unrestricted functionality over many charging and discharging cycles and low manufacturing costs.

The use of the tetrakisfluoroalkyl borate salts according to the invention or the mixtures according to the invention in large batteries, such as are used, for example, in electric road vehicles or hybrid road vehicles, is also very advantageous, since if the batteries are damaged, for example in the event of an accident, even if they come into contact with water, For example, no toxic and highly corrosive hydrogen fluoride is formed by air humidity or extinguishing water.

In the following the invention will be explained with the aid of examples. These examples serve only to illustrate the invention and do not restrict the general idea of ​​the invention.

Examples

Example 1:

Synthesis of potassium tetrakistrifluoromethylborate K [B (CF

3

)

4

]

1a)

85 mg (0.60 mmol) NH₄[B (CN)₄] were dried in a 250 ml PFA (tetrafluoroethylene perfluoropropyl vinyl ether copolymer) reactor in vacuo. About 5 ml of hydrogen fluoride and 28.4 mmol of chlorofluoride (measured by gas volumetry) were then condensed into the reactor. The reaction mixture was slowly heated to a temperature of 20 to 25 ° C. with stirring and the mixture was stirred at this temperature for a further 48 hours. The reaction mixture was then freed of all volatile constituents in vacuo. The residue thus obtained was taken up in about 5 ml of distilled water, neutralized with 200 mg of potassium carbonate and the water was then removed again in vacuo. The potassium tetrakistrifluoromethylborate K [B (CF₃)₄] extracted with diethyl ether. After the diethyl ether was distilled off, 173 mg (0.53 mmol) of K [B (CF₃)₄] receive.

Alternatively, the synthesis of K [B (CF₃)₄] also take place in accordance with regulation 1b) or 1c):

1b)

1.512 g (11.4 mmol) NH₄[B (CN)₄] were dried in a 500 ml stainless steel autoclave in vacuo. About 30 to 40 ml of hydrogen fluoride and 562 mmol of chlorofluoride (measured by gas volumetry) were then condensed into the autoclave.

The reaction mixture was then slowly heated to a temperature of 20 to 25 ° C. with stirring and the mixture was stirred at this temperature for a further 48 to 72 hours. The reaction mixture was then freed of all volatile constituents in vacuo. The residue thus obtained was taken up in about 50 ml of distilled water, neutralized with 3.8 g of potassium carbonate and the water was then removed again in vacuo. The potassium tetrakistrifluoromethylborate K [B (CF₃)₄] extracted with diethyl ether. After the diethyl ether was distilled off, 3.4 g (11.2 mmol) of K [B (CF₃)₄] receive.

1c)

105 mg (0.79 mmol) NH₄[B (CN)₄] were dried in a 250 ml PFA (tetrafluoroethylene perfluoropropyl vinyl ether copolymer) reactor in vacuo. About 5 ml of hydrogen fluoride and 11.4 mmol of chlorine trifluoride (measured by gas volumetry) were then condensed into the reactor. The reaction mixture was then slowly heated to a temperature of 20 to 25 ° C. with stirring and the mixture was stirred at this temperature for a further 19 hours. The reaction mixture was then freed of all volatile constituents in vacuo. The residue thus obtained was taken up in about 7 ml of distilled water, neutralized with 300 mg of potassium carbonate and the water was then removed again in vacuo.

The potassium tetrakistrifluoromethylborate K [B (CF₃)₄] extracted with diethyl ether. After the ether was distilled off, 209 mg (0.69 mmol) of K [B (CF₃)₄] receive.

Part of the K [B (CF₃)₄] was dissolved in deuterated acetonitrile (200 mg / ml, 1 mol / 25 mol CD₃CN) and by means of ¹¹Federation ¹⁹F-NMR spectroscopy characterized. The inclusion of the¹¹B-NMR spectrum was carried out at a frequency of 160.5 MHz, that of ¹⁹F-NMR spectrum at 470.6 MHz and that of ¹³C-NMR spectrum at 125.8 MHz. As an internal standard for the¹¹B NMR spectroscopy (C₂H₅)₂OBF₃ with δ = 0 ppm, for which ¹⁹F NMR spectroscopy CFCl₃ with δ = 0 ppm and for ¹³C-NMR spectroscopy used tetramethylsilane (TMS) with δ = 0 ppm. The NMR spectroscopic data were as follows:<ul id="ul0008" list-style="none"><li>¹¹B-NMR spectrum: δ = -18.94 ppm, ²J (¹¹B¹⁹F) = 25.92 Hz, ¹J (¹¹B¹³C) = 73.4 Hz, ¹Δ¹¹B (^12/13C) = 0.0030 ppm with a line width of 0.5 Hz.</li><li>¹⁹F-NMR spectrum: δ = -61.60 ppm, ²J (¹⁹F¹¹B) = 25.92 Hz, ²J (¹⁹F¹⁰B) = 8.68 Hz, ²Δ¹⁹F (^10/11B) = 0.0111 ppm, ¹J (¹⁹F¹³C) = 304.3 Hz, ¹Δ¹⁹F (^12/13C) = 0.1315 ppm, ³J (¹⁹F¹³C) = 3.9 Hz, ³Δ¹⁹F (^12/13C) = 0.0010 ppm, ⁴J (¹⁹F¹⁹F) = 5.8 Hz with a line width of 0.4 Hz.</li><li>¹³C-NMR spectrum: δ = 132.9 ppm, ¹J (¹³C.¹⁹F) = 304.3 Hz, ³J (¹³C.¹⁹F) = 4.0 Hz, ¹J (¹³C.¹¹B) = 73.4 Hz, ¹J (¹³C.¹⁰B) = 24.6 Hz, ¹Δ¹³C (^10/11B) = 0.0029 ppm with a line width of 1.5 Hz.</li></ul>

The purity of the potassium tetrakistrifluoromethyl borate thus obtained was&gt; 99%. The K [B (CF₃)₄] is very soluble in water, diethyl ether and acetonitrile, but insoluble in dichloromethane, pentane and heptane. According to differential scanning calorimetry measurements, the salt is stable in the solid state up to 320 ° C (ΔH = -90 J / g) and exhibits at -63 ° C (ΔH = 4.5 J / g) and at - 47 ° C ( ΔH = 7.8 J / g) two phase transformations.

If, instead of potassium carbonate, other carbonates or their mixtures, for example lithium carbonate, sodium carbonate, rubidium carbonate or cesium carbonate, are used to neutralize the respective crude product, the corresponding lithium, sodium, rubidium or cesium tetrakistrifluoromethylborate salts can be obtained analogously, with the corresponding lithium or . Sodium salt solvent molecules are bound, which can be successively removed by slowly heating the respective salt.

Example 2:

Synthesis of [Li (THF)

X

] [B (CF

3

)

4

]

173 mg K [B (CF₃)₄] (0.57 mmol) and 24 mg lithium chloride were dried in a 50 ml glass flask with a polytetrafluoroethylene valve in a vacuum. About 10 ml of tetrahydrofuran were then condensed into the flask and the reaction mixture was stirred at a temperature of 20 to 25 ° C. for one hour. A precipitate of potassium chloride formed, which was then filtered off. The solution thus obtained was completely concentrated at a temperature of 20 to 25 ° C in a vacuum. After removal of the tetrahydrofuran, 300 mg [Li (THF)_X] [B (CF₃)₄] receive.

Lithium tetrakistrifluoromethylborate is stable up to 168 ° C in the solid state (ΔH = -260 J / g). It is very soluble in water, tetrahydrofuran, acetonitrile, methanol and acetone. The tetrahydrofuran solvate molecules are gradually removed up to 140 ° C (97 ° C, ΔH = 7 g / J, 130 ° C, ΔH = 4 J / g).

Example 3:

Synthesis of Li [B (CF

3

)

4

]

4.233 g (12.99 mmol) K [B (CF₃)₄] and 1.225 g (13.07 mmol) Li [BF₄] were placed in 13.052 g solvent mixture of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a ratio of 2: 1: 2. A precipitate of K [BF₄], which was separated by filtration. The solution of Li [B (CF₃)₄] (14.522 g, 11.7 ml) had a salt concentration of 22.6% by weight or 0.96 mol / l.

Example 4:

Synthesis of 1-ethyl-3-methylimidazolium tetrakistrifluoromethylborate

Equimolar amounts of potassium tetrakistrifluoromethyl borate and 1-ethyl-3-methylimidazolium chloride were suspended in acetonitrile at a temperature of 20 to 25 ° C. This mixture was then stirred at this temperature for 10 hours and vacuum filtered with cooling through a glass frit in order to completely remove the potassium chloride formed. The solvent was distilled off in vacuo and the product thus obtained was dried in vacuo.

Example 5:

Comparison of the specific ionic conductivity of Li [B (CF₃)₄] and LiPF₆:

A solution of the corresponding salt in a mixture of ethylene carbonate, diethyl carbonate and dimethyl carbonate in a volume ratio of 2: 1: 2 was prepared and measured at a temperature of 25 ° C.

The conductivity measurement was carried out using a Knick 703 conductivity meter and a Knick 4-pole measuring cell with a cladding tube. Thermostatization was carried out in the TI 4 climatic cabinet, and the temperature was checked using a Pt 100 resistance thermometer.

The corresponding concentrations and the corresponding ionic conductivities are given in Table 1 below: <tables id="tabl0001" num="0001"><table frame="all"><title>Table 1:</title><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="center">Li [B (CF₃)₄]</entry><entry namest="col3" nameend="col3" align="center">LiPF₆</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">Concentration of the solution in mol / l</entry><entry namest="col2" nameend="col2" align="char" char=",">0,96</entry><entry namest="col3" nameend="col3" align="center">1</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">Ionic conductivity in mS / cm</entry><entry namest="col2" nameend="col2" align="char" char=",">10,1</entry><entry namest="col3" nameend="col3" align="center">9,6</entry></row></tbody></tgroup></table></tables>

The Li [B (CF₃)₄] Salt shows one compared to LiPF₆ improved specific ionic conductivity.

Example 6:

Investigation of the electrochemical stability Li [B (CF₃)₄]:

In a measuring cell with platinum working electrode, lithium counter electrode and lithium reference electrode, a 0.96 molar solution of Li [B (CF₃)₄] three successive cyclic voltammograms recorded in ethylene carbonate, diethyl carbonate and dimethyl carbonate (volume ratio of 2: 1: 2). For this purpose, starting from the resting potential, the potential was first compared to the potential of Li / Li at a feed rate of 10 mV / s to 6.0 volts⁺ increased and then lowered back to the resting potential. The cyclic voltammograms obtained in this way showed no signs of decomposition of the electrolyte.