DE102006054951A1 - Ionic liquids and their use - Google Patents

Abstract

Ionic liquid (A) comprises a polymer or copolymer derived from allyl- or vinyl-monomer and containing ammonium-cation (I) and an anion. Ionic liquid (A) comprises a polymer or copolymer derived from allyl- or vinyl-monomer containing an ammonium-cation of formula (-Q1(X)-Q2(Y1)-) (I) and an anion. Q1, Q2-CH(CH3)-CH2- or -CH2-CH(CH3)-CH2-; X, Y1>N+>HR1R2, SO3+>H, imidazolium, 1-6C alkanesulfonic acid-imidazolium or pyridinium; and R1, R2H or 1-6C alkyl. Independent claims are included for: (1) the preparation of the ionic liquid comprising polymerizing the allyl- or vinyl monomer, and subsequently reacting with the corresponding acid compound under anion exchange; (2) the use of (A) as an electrolyte; (3) the use of (A) in the manufacture of fuel cell membrane or of fuel cell membrane-electrode-unit, preferably a membrane separation process from solvents; and (4) a thermal procedure for the preparation of a membrane form (A) comprising the impregnation step.

Description

The Invention relates to ionic liquids comprising polymers derived from allyl or vinyl monomers or Copolymers containing aminium and / or sulfonium cations and their use.

During the Operation of a Polymer Electrolyte Membrane (PEM) Fuel Cell becomes an oxygen-containing gas of the cathode and a hydrogen-containing Gas supplied to the anode. At the anode, the electrochemical oxidation of hydrogen takes place instead, at the cathode the reduction of oxygen. By the direct Conversion of chemical into electrical energy bypassing the Carnot limitation can be a high efficiency in fuel cells be achieved.

Developed at the time most PEM fuel cell technology is based on Nafion ^® membranes as the electrolyte. The electrolytic conduction takes place via hydrated protons, whereby the proton conductivity of the membrane is coupled to the presence of liquid water. This limits the operating temperature of such fuel cell membranes at atmospheric pressure below 100 ° C.

at Temperatures higher as 80-95 ° C performance deteriorates due to the increasing fluid loss clear. To maintain the conductivity of the membrane above from 100 ° C are due to the temperature dependence the vapor pressure of water very large amounts of water for humidification the membrane needed. In systems with a pressure greater than At normal pressure, the temperature can be at the expense of efficiency, size and Weight of the overall system increased become. For a company clearly over 100 ° C would the needed However, pressure is increasing dramatically.

operating temperatures greater than 100 ° C are off for a variety of reasons desirable: the electrokinetics, as well as the catalytic activity for both Electrodes increase with increasing temperature. Besides that is the tolerance Impurities of the operating gases used, such as Carbon monoxide (CO) higher. For the Use of a fuel cell in a vehicle is due to the lower heat emissions through the exhaust one as possible size Temperature difference to the ambient temperature for the removal of waste heat advantageous.

There However, with increasing operating temperature the demands on the thermal stability all components of the fuel cell stack and the system components dramatically increases, is for the vehicle use a continuous operating temperature of 120 to 130 ° C as ideal considered. The decisive factor is that one intended for the vehicle drive MEA (English Membrane Electrode Assembly) preferably no additional Humidification needed, this means The membrane contained a water-neutral or better anhydrous Proton transport enabled. About that In addition, it is crucial that the conductivity has only a low dependence from the operating temperature, so that even at a starting temperature in the range of room temperature and below a sufficient power the MEA is ensured to get the system through waste heat without additional heating to the optimum operating temperature.

Approaches for the realization of high-temperature PEM fuel cells are given. A promising approach, such as one with no, or with very little additional humidification operating at operating temperatures of 120 to 180 ° C working fuel cell can be realized, inter alia, in WO 96/113872 A1 . US 5525436 A . US 5716727 A . US 6025085 A . US 5599639 A . WO 99/04445 A1 . EP 983 134 81 . WO 01/18894 A . EP 954544 A1 and WO 01/18894 A2 described. The conductivity of the fuel cell membrane used here is based on the content of liquid, essentially bound by electrostatic complex binding to the polymer backbone mineral acid (usually phosphoric acid), which takes over the proton conductivity even with complete dryness of the membrane (above the boiling point of water) without additional humidification of the operating gases , The disadvantage of this system is that the LF, which is generally lower by a factor of up to 20, in the range of room temperature compared to the continuous operating temperature (160 ° C.). In addition, the liquid only electrostatically bound to the polymer electrolyte tends to discharge through the at lower temperatures, such as liquid during the start of the cell product water.

Other known approaches to simplify the water balance of the electrolyte membranes, starting from conventional NT membranes based on Nafion ^® or sPEEK, which either in the synthesis of the membrane or in retrospect, such as a sol-gel process, an additional inorganic phase (SiO ₂ , B ₂ O ₃ , ZrP, ZrPPh), which acts on the one hand as a water reservoir, or especially at higher temperatures, as an additional proton conductor.

Corresponding approaches are being pursued worldwide (see EP 926754 B1 . WO 03/081691 A2 . WHERE 02/05370 A1 ). In particular, the long-term stability in the range of high operating temperatures and low moisture contents of the operating gases proves to be problematic in this type of membrane. Also, the desired performance at operating temperatures above 100 ° C and low humidities still far below expectations.

Theoretical considerations led to liquid imidazoles as promising proton transfer agents ( US 6264857 A . DE 19632285 A1 , Electrochimica Acta 43 (1998), page 1281)). By covalent attachment of imidazoles to various polymers, quite promising model compounds for novel proton conductors have now been realized ( Pu; Macromolecular Chemistry & Physics 202 (2001) page 1478, heart; Electrochimica Acta 2002 ). However, the previously observed proton conduction is still orders of magnitude under the conventional electrolytes, moreover, the compounds have a significant temperature dependence. Moreover, it has not been possible to identify stable carrier polymers under the particular conditions of a fuel cell.

Another approach to the realization of high temperature membranes is based on, for example sulfonic acid / sulfonamide / imidazole functionalized copolymers based on alkoxysilanes, for example Ormoceren ( DE 10163518 A1 . EP 1323767 A2 ). With these materials thermally and chemically stable polymers can be realized, at least under the appropriate conditions. The conductivity observed here in the higher temperature ranges, at least when moistened, is of the order of magnitude of Nafion, but at lower temperatures the conductivity breaks down significantly.

Recently, so-called tonic liquids, that is to say salts which are generally liquid at room temperature, are being mentioned as promising candidates for the realization of novel anhydrous proton conductors ( WO 01/93362 A1 . US 6667128 B2 ). These compounds are so-called "designer solvents", ie liquids whose chemical and physical properties (solubility / conductivity / boiling / melting temperature, vapor pressure) can be tailored in a wide field to the respective requirement. The compounds usually consist of organic cations based on nitrogen-containing heterocycles (imidazole, pyridine) in combination with inorganic anions (eg AlCl ₄ , BF ₄ , N (SO ₂ CF ₃ ) ₂ ^- , PF ₆ ^- ).

Depending on the individual structure, proton conductivities up to 0.016 S / cm have been observed over a wide temperature range in these systems under completely anhydrous conditions ( WO 03/083981 A1 ).

The task of a proton-exchanging membrane for fuel cells is in addition to the actual proton conduction and the electrical isolation of the two half-cells in the spatial separation of the reaction gases hydrogen and oxygen. To make this possible, ionic liquids must either be embedded in a suitable porous support framework or, ideally, be a firmly linked constituent of a polymeric material (see, inter alia: WO 03/063266 A2 , or M. Watanabe, K.-I. Ota, ECS Meeting Honolulu 2005 ). In the supported variants, there are attempts to incorporate the ionic liquids in porous matrices, for example, which ensure mechanical stability, but enable proton conduction via channels filled with ionic liquid ( WO 01/093362 A1 . WO 03/063266 A2 ). The porous supports are, for example, completely homologous polymeric matrices (PTFE, PET, for example: WO 01/093362 A1 . WO 03/063266 A2 . US 6299653 A . EP 309259 B1 ) or to oxidic, preferably nanoparticulate composite systems (Al ₂ O ₃ / SiO ₂ , eg: WO 02/047802 A1 ). An alternative is the impregnation of conventional proton exchange membranes based on sulfonated polymers with ionic liquids; For example, when Nafion is impregnated with 1-butyl-3-methylimidazolium trifluoromethanesulfonate, a conductivity of 0.11 S / cm at 180 ° C and complete dryness is observed (see, inter alia M. Doyle, Journal of The Electrochemical Society, 147 (1) 34-37 (2000) ), other approaches are also based on Nafion or BPSH, which are impregnated with 1-ethyl-3-methyl imidazole bis (pentafluoroethylsulfonyl) imide (inter alia E. McGrath, ECS Meeting Honolulu 2005 ).

To a fuel cell functional unit can be reached by combination of the above membranes with electrodes (usually Pt / C on carbonic Carrier) on both sides of the membrane. The unit membrane + electrode becomes referred to as MEA (English Membrane Electrode Assembly).

For commissioning, the cell is exposed to gases and connected to the electrical load. For this purpose, the operating gases from a current of about 0.2 A / cm ² stoichiometrically tracked the respective power requirement.

The The object of the invention was to search for further electrolytes, used for the production of fuel cell membranes and MEAs can be especially for you To provide high temperature PEM fuel cells.

Your Function as a proton conductor results in ionic liquids on the one hand as a high-boiling proton solvent (water substitute), on the other hand as an intrinsic proton conductor with its own covalent or ionically bound proton-conducting groups which have a sufficient proton conductivity also under liquid-free Conditions allow.

• 1. Zersetzungstemperatur der Verbindungen liegt deutlich oberhalb der angestrebten Einsatztemperatur (> 150 °C).
• 2. Siedetemperatur liegt deutlich oberhalb der angestrebten Einsatztemperatur (> 150 °C).
• 3. Leitfähigkeit bei –20 °C (trocken): > 0,01 S/cm.
• 4. Leitfähigkeit bei 20°C (trocken): > 0,05 S/cm.
• 5. Leitfähigkeit bei 80-130 °C (trocken): > 0,1 S/cm.
• 6. Hohe Oxidationsstabilität (Sauerstoff + Radikale).
• 7. Hohe Reduktionsstabilität, insbesondere gegenüber Wasserstoff.
• 8. Geringe Wasserlöslichkeit des Elektrolyten über den gesamten Einsatztemperaturbereich.

Ideal proton conductors for automotive claims must meet the following requirements:

• 1. Decomposition temperature of the compounds is well above the desired use temperature (> 150 ° C).
• 2. Boiling temperature is well above the intended operating temperature (> 150 ° C).
• 3. Conductivity at -20 ° C (dry):> 0.01 S / cm.
• 4. Conductivity at 20 ° C (dry):> 0.05 S / cm.
• 5. Conductivity at 80-130 ° C (dry):> 0.1 S / cm.
• 6. High oxidation stability (oxygen + radicals).
• 7. High reduction stability, especially with respect to hydrogen.
• 8. Low water solubility of the electrolyte over the entire operating temperature range.

• a) von Allyl- oder Vinyl-Monomeren abgeleitete Polymere oder Copolymere, die Ammonium-Kationen enthalten, mit der allgemeinen Formel I
  
  worin Q₁ und Q₂ = gleich oder verschieden
  
  und X und Y gleich oder verschieden ⁺NHR₁R₂, mit R₁ und R₂ gleich oder verschieden H oder C₁ bis C₆-Alkyl; ⁺SO₃H Imidazolium, C₁ bis C₆-Alkyl-Sulfonsäure-Imidazolium oder Pyridinium bedeuten, und
• b) Anionen.

The invention relates to ionic liquids as novel electrolytes with potential for fuel cell application comprising

• a) derived from allyl or vinyl monomers polymers or copolymers containing ammonium cations, having the general formula I.
  
  wherein Q ₁ and Q ₂ = the same or different
  
  and X and Y are the same or different and are ⁺ NHR ₁ R ₂ , where R ₁ and R _{2 are} identical or different and are H or C ₁ to C ₆ -alkyl; ⁺ SO ₃ H imidazolium, C ₁ to C ₆ alkyl sulfonic acid imidazolium or pyridinium, and
• b) anions.

• 1.1. von Allylamin-Derivaten,
• 1.2. von 1-Allylimidazol,
• 1.3. von 4-Vinylpyridin,
• 1.4. von Allylamin- und Sulfonsäure-Derivaten (Copolymere),
• 1.5. von 1-Allylimidazolium-3-(butan-4-sulfonat),
• 1.6. von 3-Vinylimidazolium-1-(butan-4-sulfonat).

In a preferred embodiment of the invention, the polymer or copolymer cation is derived from the following monomers:

• 1.1. of allylamine derivatives,
• 1.2. of 1-allylimidazole,
• 1.3. of 4-vinylpyridine,
• 1.4. of allylamine and sulfonic acid derivatives (copolymers),
• 1.5. of 1-allylimidazolium-3- (butane-4-sulfonate),
• 1.6. of 3-vinylimidazolium-1- (butane-4-sulfonate).

Preferably, the ionic liquids comprise at least one anion selected from the group consisting of dihydrogen phosphate [H ₂ PO ₄ ] ^- , bis (trifluoromethylsulfonyl) imide [BTA] ^- , or tris (pentafluorene thyl) triphosphate [(C ₂ F ₅ ) ₃ PF ₃ ] ^- as counterion, if appropriate also [PO ₄ ] ^3- , [HPO ₄ ] ^2- , or [N (SO ₂ CF ₃ ) ₂ ].

Very particularly preferred ionic liquids according to the invention are poly- [1-allyl-3- (butane-4-sulfonic acid) imidazolium bis (trifluoromethanesulfonyl) imide] - Example 5,
Poly [1-allylimidazolium dihydrogen phosphate] Example 2
Poly- [4-vinylpyridinium dihydrogen phosphate] - Example 3,
Poly (allyl ammonium dihydrogen phosphate) - Example 1a,
Poly (allylammonium bis (trifluoromethylsulfonyl) imide] - Example 1b,
Poly [1- (butane-4-sulfonic acid) -3-vinylimidazolium bis (trifluoromethylsulfonyl) imide] Example 6.

Poly(diAllylamin)

und co-Poly(Allylamin-Diallylamin) (co-PAA-PDA)

vorteilhaft auch als Copolymere mit Sulfonsäurederivaten gemäß Pkt. 1.4.Allyl-amine derivatives having the following structures are also preferably used according to the invention: poly (oleylamine)

Poly (diallylamine)

and co-poly (allylamine-diallylamine) (co-PAA-PDA)

also advantageous as copolymers with sulfonic acid derivatives according to item 1.4.

In a preferred embodiment, the compounds of the invention are nachimprägniert, preferably with H ₃ PO ₄ , used.

Further very particularly preferred ionic liquids according to the invention are characterized in that they comprise an N-perfluoroalkyl-substituted imidazolyl cation, wherein alkyl denotes a longer-chain carbon residue having 6 to 12 C atoms, preferably compounds which are an N-perfluorooctyl-substituted imidazolyl Cation, and an anion selected from the group consisting of [H ₂ PO ₄ ] ^- , [N (SO ₂ CF ₃ ) ₂ ] ^- or [(C ₂ F ₅ ) ₃ PF ₃ ] ^- as the counterion (Compounds 2.1 , 2.2 and 2.3).

The new proton conductors based on ionic liquids are presented below. Depending on Construction, they are suitable for direct membrane preparation in a drawing process from a suitable solvent, or for the loading of porous media or as electrolytes or electrolyte additives in systems based on impregnated and in the electrolyte-swelling polymers, such as the PBI / H _{3 system} PO ₄ . Alternatively, the new proton conductors can also be introduced only into the electrode, for example as a polymer binder, or as a coating of the electrode to optimize the connection of the electrode or as a barrier layer on a membrane.

component The invention is both the production and structure of the respective Proton conductor, its further processing to proton-conducting membranes and electrodes adapted to these membranes, as well as the insert the resulting MEAs in fuel cells.

• 1. Brennstoffzellenmembranelektrolyte auf der Basis Polymergebundener ionischer Flüssigkeiten wie zum Beispiel der Verbindungen 1.1 bis 1.6 mit einem Strukturmotiv der Art Allyl-Amin, Allyl-Imidazol, Vinyl-Pyridin, Allyl-butylsulfonsäure-Imidazolium, Vinyl-butylsulfonsäure-Imidazolium oder die entsprechenden Copolymere. Die Herstellung von protonenleitenden Membranen aus den Polymeren erfolgt bevorzugt durch etablierte Membranziehprozesse aus den Lösungen der aufgeführten Polymere in entsprechend geeigneten Lösungsmitteln oder durch thermisches Umwandeln.

The invention is preferred:

• 1. Fuel cell membrane electrolytes based on polymer-bound ionic liquids such as compounds 1.1 to 1.6 with a structural motif of the type allyl amine, allyl imidazole, vinyl pyridine, allyl-butylsulfonic acid imidazolium, vinyl-butylsulfonic acid imidazolium or the corresponding copolymers. The preparation of proton-conducting membranes from the polymers is preferably carried out by established membrane drawing processes from the solutions of the polymers listed in appropriately suitable solvents or by thermal conversion.

• 2. Brennstoffzellenmembranen, die durch Imprägnierung einer porösen Membranmatrix mit Lösungen der Verbindungen der Art 1.1-1.6 in geeigneten beispielsweise organischen Lösungsmitteln nach anschließendem Verdampfen des Lösungsmittels erhalten werden. Bei den porösen Trägern handelt es sich zum Beispiel um PTFE oder PET basierende Systeme unterschiedlicher Porosität (siehe zum Beispiel: WO 01/093362 A , WO 03/063266 A , US 6299653 A , EP 309259 81 ) oder um oxidische, bevorzugt nanopartikulär beschichtete Systeme wie zum Beispiel.: Al₂O₃/SiO₂ beschichtetes PET (zum Beispiel. gemäß WO 02/047802 A ). Bei Verwendung flüssiger Elektrolyte auf Basis ionischer Flüssigkeiten kann die Imprägnierung der porösen Matrix auch direkt im unverdünnten Zustand erfolgen. Bei Verwendung einer PTFE Matrix werden ganz besonders bevorzugt Elektrolyte mit einer fluorierten Alkylseitenkette und einer damit hohen Anbindungstendenz an die poröse Matrix eingesetzt (wie zum Beispiel die Verbindungen 2.1 bis 2.3).
• 3. Verwendung flüssiger Elektrolyte auf Basis ionischer Flüssigkeiten zum Beispiel der Verbindungen 2.1 bis 2.3 als Elektrolytersatz oder Elektrolytzusatz für Protonensäuren in Membransystemen, die auf dem Gehalt flüssiger Elektrolyte in bevorzugt basischen Polymeren beruhen, zum Beispiel als Ersatz für Phosphorsäure im System PBI/H₃PO₄. Die ionischen Flüssigkeiten können dabei zum Beispiel durch Nachimprägnierung in eine undotierte Membran eingebracht werden oder der Ziehlösung bei der Membranherstellung beigemischt werden. Alternativ wird der Elektrolyt bereits bei der Polymerisation des Polymerrohstoffes zugegeben oder es erfolgt nur die Imprägnierung der Elektrode mit einem erfindungsgemäßen Elektrolyten, während die Membran weiterhin zum Beispiel Phosphorsäure enthält, oder die ionische Flüssigkeit wird über die Elektrode in die Membran eingebracht.
• 4. BZ MEA (Membran-Elektrodeneinheit) basierend auf einer Membran wie unter 1 bis 3 genannt, bei der die betreffende Elektrode den entsprechenden auf einer ionischen Flüssigkeit basierenden Polymerelektrolyt beispielsweise Verbindungen 1.1 bis 1.6 als Binder enthält beziehungsweise auf der Katalysatorseite mit dem entsprechenden Polymerelektrolyt zur Optimierung der Anbindung an die Membran beschichtet ist. Diese Beschichtung ermöglicht bevorzugt im Zuge eines Heißpressvorganges eine gleichmäßige und feste Anbindung der Elektrode an die Membran.

Depending on the type of polymer used, additional crosslinking to increase the mechanical and chemical stability is likewise part of the invention, as is the provision of the polymers with additional covalently bonded functional groups. In addition to the polymers shown in the graph, the corresponding compounds with longer alkyl radicals (CH ₂ ) x between the main chain and the functional groups are also part of the invention, as are the corresponding fluorinated or partially fluorinated compounds.

• 2. Fuel cell membranes, which are obtained by impregnation of a porous membrane matrix with solutions of the compounds of the type 1.1-1.6 in suitable, for example, organic solvents after subsequent evaporation of the solvent. The porous supports are, for example, PTFE or PET based systems of different porosity (see, for example: WO 01/093362 A . WO 03/063266 A . US 6299653 A . EP 309259 81 ) or oxidic, preferably nanoparticulate, coated systems such as: Al ₂ O ₃ / SiO ₂ coated PET (for example WO 02/047802 A ). When using liquid electrolytes based on ionic liquids, the impregnation of the porous matrix can also take place directly in the undiluted state. When using a PTFE matrix, very particular preference is given to using electrolytes having a fluorinated alkyl side chain and a high tendency to attach to the porous matrix (such as compounds 2.1 to 2.3).
• 3. Use of liquid electrolytes based on ionic liquids, for example, the compounds 2.1 to 2.3 as an electrolyte replacement or electrolyte additive for protic acids in membrane systems, based on the content of liquid electrolytes in preferably basic polymers, for example as a substitute for phosphoric acid in the system PBI / H ₃ PO ₄ . The ionic liquids can be introduced, for example by Nachimprägnierung in an undoped membrane or the Ziehlösung be mixed in the membrane production. Alternatively, the electrolyte is added already in the polymerization of the polymer raw material or it is only the impregnation of the electrode with an electrolyte according to the invention, while the membrane further contains, for example, phosphoric acid, or the ionic liquid is introduced via the electrode into the membrane.
• 4. BZ MEA (membrane electrode assembly) based on a membrane as mentioned under 1 to 3, in which the electrode in question the corresponding ionic liquid based polymer electrolyte, for example compounds 1.1 to 1.6 as a binder or on the catalyst side with the corresponding polymer electrolyte for Optimization of the connection to the membrane is coated. This coating preferably allows a uniform and firm connection of the electrode to the membrane in the course of a hot pressing process.

• 5. BZ MEA (Membran-Elektrodeneinheit) unter Verwendung einer Membran gemäß der Punkte 1 bis 3, bei der die Elektrode mit einer herkömmlichen Protonensäure, beispielsweise Phosphorsäure, zusätzlich imprägniert wird.
• 6. BZ MEA gemäß Punkte 4 und 5, bei der nur die Elektrode entweder rein oder als Zusatz zu einem anderen Elektrolyt, etwa H₃PO₄ den erfindungsgemäßen Protonenleiter enthält, während die Membran aus einem anderen Polymerelektrolyt, beispielsweise aus Nafion oder PBI/H₃PO₄ besteht.
• 7. BZ MEA, basierend auf einer BZ Membran, zum Beispiel Nafion oder PBI/H₃PO₄, bei der die Außenseite mit einem der erfindungsgemäßen Polymere, zum Beispiel Verbindungen 1.1 bis 1.6 zur Beeinflussung des Wasserhaushaltes oder der Flüssigelektrolytretention beschichtet ist. Vorteilhaft ist auch die Anwendung als MeOH Sperrschicht bzw. Treibstoffsperrschicht bei einer DMFC/Direkttreibstoffbrennzelle.
• 8. Verwendung der erfindungsgemäßen Membran und MEA in einer Brennstoffzelle.
• 9. Verwendung der erfindungsgemäßen Brennstoffzelle für mobile Anwendungen (zum Beispiel APU + Traktion) und für stationäre Anwendungen (zum Beispiel mobiles Kleinkraftwerk oder Hausenergieversorgung).
• 10. Die Herstellung der unter 1.1.-1.6. aufgeführten Polymere und ihrer Derivate wird anhand der im weiteren aufgeführten Synthesebeispiele dargestellt.
• 11. Die Herstellung der unter 2.1-2.3 aufgeführten Polymere und ihrer Derivate wird anhand der im weiteren aufgeführten Synthesebeispiele dargestellt.
• 12. BZ Membran/MEA unter Weiterverarbeitung der erfindungsgemäßen Polymere gemäß Beispiel 10.

The application of the electrolyte solution to the outer electrode surface takes place, for example, by spraying over an airbrush system. The constituents of the electrode (gas diffusion layer, catalyst powder) are preferably optimized for the operating temperatures of the membrane. Alternatively, a liquid electrolyte, for example, the compounds 2.1 to 2.3, initially introduced in sufficient quantity in the electrode. The acid absorption of the membrane takes place in a corresponding annealing step via the electrode. Another variant is that an MEA obtained by hot pressing is subsequently inserted as a whole in the liquid electrolyte for impregnation. The electrodes used are preferably gas diffusion electrodes optimized for operation in the respective temperature range, such as those offered by the companies ETEK, Umicore or Johnson Matthey, but preferably in particular on the meme Brentyp adapted electrodes containing a suitable proportion of the polymer electrolyte as a binder. The introduction of liquid electrolytes into the electrode preferably takes place in a vacuum, for example by a repeated evacuation / aeration cycle in which remaining air residues within the electrode are successively replaced by the respective electrolyte.

• 5. BZ MEA (membrane electrode assembly) using a membrane according to the items 1 to 3, wherein the electrode is additionally impregnated with a conventional protic acid, for example phosphoric acid.
• 6. BZ MEA according to items 4 and 5, in which only the electrode either pure or as an additive to another electrolyte, such as H ₃ PO ₄ contains the proton conductor according to the invention, while the membrane of another polymer electrolyte, for example Nafion or PBI / H ₃ PO ₄ exists.
• 7. BZ MEA, based on a BZ membrane, for example Nafion or PBI / H ₃ PO ₄ , in which the outside is coated with one of the polymers according to the invention, for example compounds 1.1 to 1.6 for influencing the water balance or the liquid electrolyte retention. Also advantageous is the use as MeOH barrier layer or fuel barrier layer in a DMFC / direct fuel combustion cell.
• 8. Use of the membrane of the invention and MEA in a fuel cell.
• 9. Use of the fuel cell according to the invention for mobile applications (for example APU + traction) and for stationary applications (for example mobile small power station or domestic energy supply).
• 10. The production of 1.1.-1.6. listed polymers and their derivatives is illustrated by the Synthesis Examples listed below.
• 11. The preparation of the polymers listed under 2.1-2.3 and their derivatives is illustrated by the examples of synthesis given below.
• 12. BZ membrane / MEA with further processing of the polymers according to the invention according to Example 10.

in the Furthermore, the new polymeric proton conductors based on ionic liquids presented. The examples are exemplary for the whole Material class listed.

• 1.1 Allylamin-Derivate 1.2 Allylimidazol-Variante 1.3 Vinylpyridin-Variante 1.4. Copolymer-Variante 1.5 1-Allyl-3-(butan-4-sulfonsäure)-imidazolium-Variante 1.6 1-(Butan-4-sulfonsäure)-3-vinyl-imidazolium Variante

Examples of polymers according to the invention are as follows:

• 1.1 allylamine derivatives 1.2 allylimidazole variant 1.3 vinylpyridine variant 1.4. Copolymer variant 1.5 1-Allyl-3- (butane-4-sulfonic acid) imidazolium variant 1.6 1- (butane-4-sulfonic acid) -3-vinylimidazolium variant

Example 1 1.1 allyl-amine variant

a) poly (allyl ammonium dihydrogen phosphate)

In A 250 ml Schlenk flask under inert gas 47.9 g (0.84 mol, M = 57.09 g / mol) allylamine to a solution of 96.6 g (0.84 mol, M = 98.00 g / mol) of 85% phosphoric acid in 150 ml of water. To Addition of 2.27 g of potassium peroxodisulfate (1 mol%, M = 270.32 g / mol) The reaction mixture was boiled for 4 hours under atmospheric oxygen heated. Subsequently the water was first on a rotary evaporator, then removed in a high vacuum.

b) poly (allyl ammonium bis (trifluoromethylsulfonyl) imide)

In In a 250 ml Schlenk flask, 20.3 g (0.36 mol, M = 57.09 g / mol) allylamine to a solution of 100.0 g (0.36 mol, M = 281.15 g / mol) Bistrifluoromethanesulfonimide was added dropwise in 150 ml of water. After addition of 0.96 g of potassium peroxodisulfate (1 mol%, M = 270.32 g / mol), the reaction mixture was 4 hours under atmospheric oxygen heated to boiling. Subsequently the water was first on a rotary evaporator, then removed in a high vacuum.

Example 2 1.2 Allylimidazole variant

Poly [1-allyl-imidazolium dihydrogen

In A 250 ml Schlenk flask under protective gas 65.0 g (0.60 mol, M = 108.14 g / mol) of 1-allylimidazole to a solution of 69.3 g (0.60 mol, M = 98.00 g / mol) of 85% phosphoric acid in 150 ml of water dripped. After addition of 1.70 g of potassium peroxodisulfate (1 mol%, M = 270.32 g / mol), the reaction mixture became 4 hours heated to boiling under atmospheric oxygen. Subsequently was the water first on a rotary evaporator, then removed in a high vacuum.

Example 3 1.3 Vinylpyridine variant

Poly (4-vinylpyridinium-dihydrogen phosphate)

In A 250 ml Schlenk flask under inert gas 67.3 g (0.64 mol, M = 105.14 g / mol) 4-vinylpyridine to a solution from 73.8 g (0.64 mol, M = 98.00 g / mol) of 85% strength phosphoric acid in 150 ml of water dripped. After addition of 1.73 g of potassium peroxodisulfate (1 mol%, M = 270.32 g / mol), the reaction mixture became 4 hours heated to boiling under atmospheric oxygen.

Subsequently was the water on a rotary evaporator, then removed in a high vacuum and the product precipitated by addition of ethanol.

Example 4 1.4 Copolymer variant

Example 5 1.5 1-Allyl-3- (butane-4-sulfonic acid) imidazolium variant

Poly [1-allyl-3-butan-4-sulfonic acid) imidazolium bis (trifluoromethylsulfonyl) imide]

In A 500 ml Schlenk flask under inert gas 35.7 g (0.33 mol, M = 108.14 g / mol) of 1-allylimidazole and 44.9 g (0.33 mol, M = 136.17 g / mol) of 1,4-butane sultone in 250 ml of acetone heated to boiling for 14 days. The resulting precipitate of 1-allylimidazolium-3-butane-4-sulfonate) is filtered off, washed with 50 ml of cold acetone and in vacuo dried.

In A 250 ml Schlenk flask under protective gas 54.2 g (0.22 mol, M = 246.33 g / mol) 1-allylimidazolium-3- (butane-4-sulfonate) in portions in a solution from 62.4 g (0.22 mol, M = 281.15 g / mol) bis-trifluoromethanesulfonimide in 150 ml of water. After addition of 0.59 g of potassium peroxodisulfate (1 mol%, M = 270.32 g / mol), the reaction mixture became 4 hours heated to boiling under atmospheric oxygen. Subsequently was the water first on a rotary evaporator, then removed in a high vacuum.

Example 6 1.6 1- (Butane-4-sulfonic acid) -3-vinyl-imidazolium variant

Poly [1- (butan-4-sulfonic acid) -3-vinyl-imidazolium bis (trifluoromethylsulfonyl) imide

In A 250 ml Schlenk flask under protective gas was 69.0 g (0.73 mol, M = 94.11 g / mol) of 1-vinylimidazole and 99.8 g (0.73 mol, M = 136.17 g / mol) butane sultone in 150 ml acetone Stirred for 16 days at room temperature. The resulting colorless precipitate of 3-vinylimidazolium-1- (butane-4-sulfonate) was filtered off, washed with 50 ml of cold acetone and in vacuo dried. Yield: 164 g, 97%.

In a 250 ml Schlenk flask, 46.0 g of 3-vinylimidazolium-1- (betan-4-sulfonate) (0.20 mol, M = 230.31 g / mol) under protective gas and with 56.2 g (0.20 mol, 281.15 g / mol) of bistrifluoromethanesulfonimide. While stirring 1- (butane-4-sulfonic acid) -3-vinylimidazolium bis (trifluoromethylsulfonyl) imide was formed (511.3 g / mol) as a viscous liquid. Yield: 102 g, 100%.

A solution of 75.0 g (0.15 mol, 511.44 g / mol) of 1- (butane-4-sulfonic acid (3-vinylimidazolium bis (trifluoromethylsulfonyl) imide in a mixture of 200 ml of water and 100 ml of ethanol was after Add 0.24 g (1 mol%, M = 164.21 g / mol azobisisobutyronitrile (AIBN) heated to boiling under atmospheric oxygen for 6 hours. The polymer fell first as a light brown emulsion, then as a light brown, viscous sediment. The supernumerary solvent was decanted off and the residual solvent removed in a high vacuum. The residue was heated with acetonitrile. This crystallized as at first tough mass obtained poly [1- (betan-4-sulfonic acid) -3-vinyl-imidazolium-bis (trifluoromethylsulfonyl) imide slowly through. The supernumerary solvent was decanted off and the residual solvent removed in a high vacuum. Yield: 24.8 g, 33%.

Example 7

2.1 1- (perfluorooctyl) imidazolium bis (trifluoromethylsulfonyl) imide

To a solution of 8.00 g (0.20 mol, 40.00 g / mol) sodium hydroxide and 13.6 g (0.20 mol, M = 68.08 g / mol) of imidazole in ethanol was added 100 g (0.20 mol, M = 498.97 g / mol) of perfluorooctylbromide. The Re The reaction mixture was stirred for two days at room temperature. During this time, a white solid precipitated and a second liquid phase formed. The solvent was removed on a rotary evaporator. The residue was taken up in acetone and filtered through silica. The filtrate was concentrated on a rotary evaporator and the resulting 1-Perfluoroctylimidazol dried under high vacuum.

in the A 100 ml round bottomed flask was 18.0 g (37.0 mmol, M = 486.13 g / mol) 1-perfluorooctylimidazole with 10.4 g (37.0 mmol, M = 281.15 g / mol) of bis-trifluoromethanesulfonimide added. After stirring the reaction mixture at room temperature overnight, the thus obtained 1- (perfluorooctyl) imidazolium bis (trifluoromethylsulfonyl) imide Dried under high vacuum.

Example 8

2.2 1- (perfluorooctyl) -imidazolium bis (tripentafluoroethyl) trifluorophosphate

The Reaction was carried out analogously to Example 7.

Example 9

Production of proton-conducting membranes from compounds of the invention

9.1: Preparation of a solution of Links:

To Weigh a suitable amount of the respective polymer into a 100 ml beaker is carefully stirred with a magnetic stirrer 50th ml of the solvent, preferably acetone, acetonitrile, dimethoxyethane, ethanol or isopropanol added. Depending on the type of polymer used for the solution process higher Temperatures in the range up to 120 ° C possibly also applied over it. In the used liquid Electrolytes become higher Loading in the matrix achieved when diluting with a solvent is used.

9.2: Porous carrier materials:

Are used PTFE films, for example by the companies Bohlender, Exxon ^® or Porex ^®. Alternatively, oxidic, preferably nanoparticulate coated systems such as: Al ₂ O ₃ / SiO ₂ coated PET from Creavis ^® used. The selection of the porous carrier takes place depending on the type of electrolytes used. For hydrophilic electrolytes, the oxidic supports are preferably used; for electrolytes with long, preferably fluorinated alkyl chains, the hydrophobic ones are used. In order to prevent a discharge of the electrolytes by liquid water, preferably hydrophobic support materials are used for the fuel cell application. The pore radii of the support materials used are between 10 and 150,000 nm. The thickness of the support materials between 2 and 600 microns. The porosity is at least 10%.

9.3: Incorporation of Polymer Solutions in a porous one Carrier:

The solution or the pure liquid Electrolyte can be described in various ways in the under 10.2 porous support materials are introduced, this is in particular a uniform bubble-free Enforcement of all pores necessary for the resulting membrane afterwards gas-tight and proton-conducting throughout.

The support material is preferred for support on a massive carrier, for example. made of PTFE or PP. Depending on the degree of wetting achieved have to the procedures described several times be repeated in order to complete gastightness of the porous membrane film to get.

The Apply the solution takes place preferably from above onto the fleece with a pipette, the porous fleece is best located on a filter frit evacuated from below. Alternatively, the solution also be applied to the carrier with an airbrush gun.

9.3.1 Introducing the solution through a repeated evacuation / aeration cycle. The sample will alternately evacuated and then in the evacuated state with the solution commissioned, ventilated and evacuated again, leaving all remaining gas residues in the Pores gradually can be removed.

9.3.2 A turn over a solid frame stabilized porous film is in a corresponding concentrated solution of the respective electrolyte in a high-pressure autoclave several Hours with Ar charged (in the trial to 660 bar). The process is repeated several times after releasing the pressure, until a sufficiently high Loading the porous carrier with the electrolyte solution is ensured. For Each one of the links will apply one for each one Method corresponding combination of solvent and suitable porous carrier determined so as to ensure optimum wetting, full penetration of the porous support and uniform drying without blistering. At the undiluted liquid Electrolytes can be introduced directly into the carrier without solvent respectively. By choosing the appropriate dilution is a significantly higher load to achieve.

The Determination of the electrolyte absorption is done via the weight difference of porous carrier before and after the loading tests after removal of the solvent after 9.4. additionally is the degree of hydrogen permeation before and after loading as criterion for the effectiveness the loading determined. The degree of penetration of the polymer solution in the foil leaves with the help of scanning electron microscopy on sections of the Check slides.

9.4: Removal of the solvent after introduction in the porous Carrier:

Of the impregnated according to 10.3 porous carrier is transferred to a vacuum oven and there to remove the solvent carefully evacuated. Depending on the boiling point and decomposition temperature of the respective electrolyte may be used for drying a certain Temperature not exceeded become. To avoid blistering, it is necessary to slowly lower the pressure and to raise the temperature very slowly. The required drying time to constant weight is usually at least 10 h. It may turn out to be positive, the received proton-conducting membrane during to press the drying phase between two heated flat sheets. proven have pressing pressures of at least 5 bar.

9.5: solvent-free Production process of membranes by hot pressing:

The Process is especially for the production of films (polymer pellets) from sparingly soluble polymer electrolytes suitable. Loading a carrier film (PTFE / PP) with powdered Polymer electrolyte. hot pressing between steel jaws (pressing pressure ≥ 5 bar, temperature> 120 ° C). To Removal of the PTFE film gives a transparent film. Alternatively, in the powder in the hot pressing process, a porous carrier according to 10.3.2. be introduced. For this purpose, the porous support is placed on a powder layer placed on top and also covered with powder from above. The thus obtained Sandwich will follow also hot pressed under the conditions described above. The membranes thus obtained are suitable for evaluating the conductivity novel sparingly soluble Polymer electrolytes.

9.6: Determination of proton conductivity:

The obtained by the above methods samples are in a heatable and humidity regulated conductivity cell between electrically conductive carbon nonwovens or gold platelets clamped. Subsequently becomes the conductivity of the samples in the temperature range between room temperature and 160 ° C with help of impedance spectroscopy.

9.7: Carrying out the hydrogen permeation measurement:

The volumetric flow is determined by means of a sample disk having a surface area of 2 cm ² by applying a hydrogen overpressure. Determination of permeance (ml / (cm ² * min.) After loading with the electrolyte.

Claims (27)

Ionic liquids comprising a) polymers derived from allyl or vinyl monomers or copolymers containing ammonium cations having general formula I.

wherein Q ₁ and Q _{2 are the} same or different

and X and Y are the same or different and are ⁺ NHR ₁ R ₂ , where R ₁ and R _{2 are} identical or different and are H or C ₁ to C ₆ -alkyl; ⁺ SO ₃ H imidazolium, C ₁ to C ₆ alkanesulfonic acid imidazolium or pyridinium, and b) anions. Ionic liquid according to claim 1, characterized in that the polymer or copolymer cation derived from the following monomers - of allylamine derivatives, - of 1-allyimidazole, - of 4-vinylpyridine, - of allylamine and sulfonic acid derivatives, - of 1-allylimidazolium-3- (betan-4-sulfonate), - of 3-vinylimidazolium-1- (betan-4-sulfonate). Ionic liquid according to one of claims 1 or 2, characterized in at least one anion selected from the group consisting of dihydrogen phosphate [H ₂ PO _4] that it ^-, bis (trifluoromethylsulfonyl) imide [BTAT] ^-, or tris (pentafluoroethyl) triphosphate [ (C ₂ F ₅ ) ₃ PF ₃ ] ^- , [PO ₄ ] ^3- , [HPO ₄ ] ^2- , or [N (SO ₂ CF ₃ ) ₂ ] ^- as the counterion. Ionic liquid according to one of the claims 1 to 3, namely Poly [1-allyl-3- (Betan-4-sulfonic acid) imidazolium bis (trifluoromethylsulfonyl) imide] Poly [1-allyl-imidazolium dihydrogen phosphate] Poly [4-vinylpyridinium dihydrogen phosphate] Poly [allyl-ammonium dihydrogen phosphate] Poly [allyl-ammonium-bis (trifluoromethanesulfone) imide] Poly [1-Betan-4-sulfonic acid) -3-vinyl-imidazolium bis (trifluoromethylsulfonyl) imide] Poly (oleyl amine), Poly (diallylamine), Co-poly (allylamine-diallylamine) (co-PAA PDA). An ionic liquid, characterized in that it comprises an N-perfluoroalkyl-substituted imidazolyl cation, wherein alkyl is a longer-chain carbon radical having 6 to 12 carbon atoms, preferably an N-perfluorooctyl-substituted imidazolyl cation, and an anion selected from the group consisting of [H ₂ PO ₄ ] ^- , [BTA] ^- , [N (SO ₂ CF ₃ ) ₂ ] ^- or [(C ₂ F ₅ ) ₃ PF ₃ ] ^- as the counterion. Process for the preparation of an ionic liquid according to one the claims 1 to 4, characterized in that the corresponding allyl or vinyl monomer polymerized in a first step and then with the corresponding acid compound under anion exchange to the desired Implemented target connection. Process for the preparation of an ionic liquid according to one the claims 1 to 4, characterized in that the corresponding allyl or vinyl monomer in a first step with the corresponding one acid compound converted to an ionic salt and then polymerized. Process for the preparation of an ionic liquid according to claim 5, characterized in that imidazole in a solution of Sodium hydroxide and ethanol with the corresponding perfluoroalkyl bromide or -jodid to N- or H-Perfluoralkylylimidazol and subsequently the corresponding acid compound to receive the desired ionic salt admits. Use of the ionic liquids according to one of claims 1 to 5 as electrolytes. Use according to claim 9, characterized that they are used to make fuel cell membranes or fuel cell membrane electrode assemblies (MEA) can be used, preferably via a membrane drawing process from solvents. Use according to claim 9 or 10, characterized that it uses with known Polymermembranmatrices which may already be combined with other liquid electrolytes, preferably phosphoric acid, impregnated / impregnate are. Use according to claim 9 or 10, characterized that they are for the aftermath impregnation of porous Membrane matrices are used. Use according to claim 9 or 10, characterized that they are right in the drawing solution used in the manufacture of membranes or already in the polymerization solution in the preparation of the base polymers. Use according to claim 9 or 10, characterized that they are used to prepare an MEA for impregnating or wetting the electrode be used. Use according to claim 14, characterized that the ionic liquids directly for impregnation or wetting the electrode on the facing to a membrane Page or in a solution for brushing, spraying or with a vaporizable solvent for coating the electrode, preferably in the course of a hot pressing operation. Use according to any one of claims 9 to 15 for obtaining Fuel cell membranes, characterized in that porous Membranmatrices with the ionic liquids according to one of claims 1 to 5 in an organic solvent waterproof and the solvent subsequently is evaporated. Use according to any one of claims 9 to 15 for obtaining Fuel cell membranes, characterized in that from the ionic liquid or their solution according to one of the claims 1 to 5 a membrane directly, preferably in a casting process, will be produced. Use according to claim 16 or 17, characterized that as porous Membrane matrices on polytetrafluoroethylene (PTFE) or polyethylene terephthalate (PET) based systems or oxidic, preferably nanoparticulate, coated Systems and their derivatives are used. Use according to one of Claims 9 to 15, characterized that the ionic liquids according to one the claims 1 to 5 as an electrolyte replacement or as an electrolyte additive for protic acids in Membrane systems based on basic polymers, preferably PBI, be used. Use according to claim 19, characterized in that the basic polymer is selected from polybenzimidazole (PBI), a poly (pyridine), a poly (pyrimidine), a polyimidazole, a poly benzthiazole, a polybenzoxazole, a polyoxadiazole, a polyquinoxaline, a polythiadiazole and a poly (tetrazapyrene) and derivatives thereof. Use according to any one of claims 9 to 15 for obtaining a Fuel cell membrane electrode assembly (BZ MEA), characterized in that an electrode is an ionic liquid according to one the claims 1 to 5 as a binder or that the electrode on the catalyst side with an ionic liquid according to one the claims 1 to 5 is coated. Use according to claim 21, characterized that the introduction of the electrolytes takes place in a vacuum. Use according to claim 21 or 22, characterized that the diaphragm in addition to the ionic liquid with a conventional one Proton acid, preferably phosphoric acid waterproof is. Use according to one of claims 21 to 23, characterized in that the electrode of an MEA alone or as an addition to another electrolyte comprises an ionic liquid according to any one of claims 1 to 7, wherein the membrane of preferably a per se known polymer electrolyte, preferably from Nafion or PBI / H ₃ PO ₄ exists. Use according to one of Claims 9 to 24, characterized that the outside a per se known polymer electrolyte membrane for influencing the water balance or the liquid electrolyte retention or to reduce DMFC permeability with an ionic liquid according to one of claims 1 to 5 is coated. Fuel cell comprising an ionic liquid according to one the claims 1 to 5. Thermal process for producing a membrane from compounds according to one the claims 1 to 5 optionally followed by an impregnation step.