DE10208275A1 - Flexible electrolyte membrane based on a carrier comprising polymer fibers, process for their production and the use thereof - Google Patents

Abstract

Proton-conductive, flexible electrolyte membrane for a fuel cell, which is impermeable to the reaction components of the fuel cell reaction, comprising a permeable, flexible, openwork, carrier comprising polymer fibers, the carrier being permeated with a proton-conductive material which is suitable for selectively conducting protons through the membrane. DOLLAR A The invention relates to a proton-conducting membrane, a process for its production and its use. DOLLAR A The membrane according to the invention represents a new class of solid proton-conducting membranes. The basis is a porous and flexible carrier which has polymer fibers, preferably a polymer fleece. This is infiltrated with a proton-conducting material, then the membrane is dried and the proton-conducting material is solidified into a gel or crystalline material, so that in the end an impermeable, proton-conducting membrane is obtained. The electrolyte membrane remains flexible and can easily be used as a membrane in a fuel cell.

Description

The present invention relates to special proton-conductive, flexible electrolyte membranes in particular for a fuel cell, a method for producing it Electrolyte membranes and a flexible membrane electrode assembly for a fuel cell, the one comprises electrolyte membrane according to the invention. The present invention further relates to special intermediates in the manufacture of the membrane electrode assembly and special Uses of the electrolyte membrane and membrane electrode assembly.

Fuel cells contain electrolyte membranes, on the one hand, the proton exchange ensure between the half-cell reactions and on the other hand prevent it from there is a short circuit between the half-cell reactions.

So-called membrane electrode units are conventionally used in fuel cells (MEAs) used, which consist of an ion-conducting electrolyte membrane and the applied, if necessary, catalytically active electrodes (anode and cathode) consist.

From the prior art, proton exchange membranes (PEMs) are used for Fuel cell electrolyte membranes made from organic polymers known to be acidic Groups are modified, such as Nafion® (DuPont, EP 0 956 604), sulfonated Polyether ketones (Höchst, EP 0 574 791), sulfonated hydrocarbons (Dais, EP 1 049 724) or the phosphoric acid-containing polybenzimidazole membranes (Celanese, WO 99/04445).

However, organic polymers have the disadvantage that the conductivity depends on the water content of the Depends on membranes. Therefore, these membranes must be used in the Fuel cells are swollen in water and although water is constantly being formed on the cathode water must be added from the outside during operation of the membrane to prevent dehydration or a decrease in proton conductivity. Typically, organic polymer membranes in a fuel cell must have both anode and and operated on the cathode side in an atmosphere saturated with water vapor.

At elevated operating temperatures, electrolyte membranes can be made from organic polymers not be used because the water content in at temperatures above about 100 ° C the membrane can no longer be guaranteed at atmospheric pressure. The use of such membranes in a reformate or direct methanol fuel cell is therefore in the Usually not possible. In addition, the polymer membranes are used in a Direct methanol fuel cells show too high a permeability for methanol. By the So-called cross-over of methanol on the cathode side can only be slight Realize power densities in the direct methanol fuel cell.

Therefore, conventional organic polymer membranes for use in a reformate or direct methanol fuel cell not in practice despite the high proton conductivity useful.

Inorganic proton conductors are e.g. B. from "Proton Conductors", P. Colomban, Cambridge University Press, 1992 known. For the purposes of a fuel cell, however, proton-conductive zirconium phosphates known from EP 0 838 258 show conductivities which are too low. On the other hand, in the case of defect perovskites, a usable proton conductivity is only achieved at temperatures which are above the operating temperatures of a fuel cell that occur in practice. Known proton-conducting MHSO ₄ salts are readily soluble in water and are therefore only of limited use for fuel cell applications in which water is formed in the fuel cell reaction (WO 00/45447).

Known inorganic proton-conducting materials can also not be in the form of Produce thin membrane films that provide a low overall resistance Cell are required. Low surface resistances and high power densities Fuel cells for technical applications in automotive engineering are familiar with the Materials therefore not possible.

WO 99/62620 proposes an ion-conducting, permeable composite material as well its use as an electrolyte membrane of an MEA in a fuel cell. The Electrolyte membrane from the prior art consists of a metal network, which with a porous ceramic material is coated on a proton conductive material was applied. This electrolyte membrane has an organic one Nafion membrane superior proton conductivity at temperatures above 80 ° C. The However, prior art does not contain an embodiment of a fuel cell in which one such an electrolyte membrane was used.

It has now been found that the electrolyte membrane known from WO 99/62620 has serious disadvantages with regard to the usability of these MEA containing electrolyte membrane in practice and in view of that Manufacturing process required to provide such MEAs. Through this Disadvantages are the MEA known from WO 99/62620 for use in a fuel cell unsuitable in practice. It has been shown that the known electrolyte membranes have good proton conductivity at elevated temperatures, on the other hand but short circuits under practical application conditions in a fuel cell occur that make the electrolyte membranes unusable. Furthermore, those from WO 99/62620 known electrolyte membranes with regard to the adhesion of the ceramic material the metal carrier problematic, so that with long periods of time with a detachment of the Ceramic layer must be expected from the metal network.

Against this background, the applicant has developed membranes that do not Have metal supports (DE 100 61 920, DE 101 15 927, DE 101 15 928). These membranes are comparatively good proton-conducting membranes (hereinafter called cPEM), In practice, however, it has been shown that the conductivity and so that the power density of the fuel cell is not sufficient. The reason for this lies in that the MF membranes used as the base membrane have too low a porosity of Max. 30 vol .-% and also have a non-uniform pore structure on the inside. by virtue of In both effects, the degree of filling with the electrolyte is too low. Other disadvantages are the high Price for the glass fabrics as well as the limited commercial availability extremely thin and cheap fabric. However, the thicker the fabric, the higher it is despite the higher Conductivity necessarily means the resistance of the membrane.

By far the biggest disadvantage of glass fabric based membranes is that glasses used do not have a sufficiently high long-term stability in the very acidic Have operating conditions of the fuel cell. In addition, these membranes have comparatively small minimum bending radii, it comes due to the brittleness in the Reality very easy to buckle anyway. This will make the membranes for the Reaction components of the fuel cell reaction are leaky, i.e. permeable and can are no longer used in the fuel cell. In the worst case, it can the entire cell may also explode (as a result of a detonating gas reaction).

• a) eine hohe Protonenleitfähigkeit bei deutlich reduzierter Luftfeuchtigkeit im Vergleich zu Polymermembranen aufweist,
• b) eine höhere Protonenleitfähigkeit als Membranen zeigen, die auf Verbundwerkstoffen basieren, die wiederum poröse Keramiken aufweisen,
• c) einen geringen Gesamtwiderstand einer Membranelektrodeneinheit ermöglicht,
• d) mechanische Eigenschaften, wie Zugfestigkeit und Flexibilität, aufweist, die für einen Einsatz unter extremen Bedingungen, wie sie beim Betrieb eines Fahrzeugs auftreten, geeignet sind,
• e) erhöhte Betriebstemperaturen von mehr als 80°C toleriert,
• f) Kurzschlüsse und cross-over-Probleme vermeidet, und
• g) einfach hergestellt werden kann.

It is therefore an object of the present invention to provide a proton-conductive, flexible electrolyte membrane for a fuel cell that is suitable for use in practice and in particular

• a) has a high proton conductivity with significantly reduced air humidity compared to polymer membranes,
• b) show a higher proton conductivity than membranes based on composite materials, which in turn have porous ceramics,
• c) enables a low total resistance of a membrane electrode unit,
• d) has mechanical properties, such as tensile strength and flexibility, which are suitable for use under extreme conditions, such as occur during the operation of a vehicle,
• e) tolerated increased operating temperatures of more than 80 ° C,
• f) avoids short circuits and cross-over problems, and
• g) can be easily manufactured.

Surprisingly, it was found that electrolyte membranes perform the above-mentioned tasks solve, can be easily manufactured in the place of the previously used MF Membranes, the substrates made of glass, such as. B. glass fabric or nonwoven, such Membranes or composites are used as supports on substrates based, which have polymer fibers, which are then infiltrated with the electrolytes. Since the Composites based on substrates that have polymer fibers are significantly more flexible are, the electrolyte membranes are significantly more flexible than electrolyte membranes based on membranes based on glass fiber substrates. It is important that the carrier not just in z. B. mineral acids can be soaked, but that the electrolyte immobilized in the form of a gel, glass or crystalline material in the end of the tissue must be available.

The present invention therefore relates to one for the reaction components Fuel cell reaction impermeable, proton conductive, flexible electrolyte membrane for a fuel cell comprising a flexible, permeable composite as Carrier with a flat, multi-hole flexible substrate a coating located on and in this substrate, the material of the Substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating, and wherein the carrier with a proton conductive Material is penetrated, which is suitable for selectively guiding protons through the membrane.

• a) Infiltration eines Trägers, der auf einem stoffdurchlässigen Verbundwerkstoff basiert, der ein flächiges, mit einer Vielzahl von Öffnungen versehenes, flexibles Substrat mit einer auf und in diesem Substrat befindlichen Beschichtung aufweist, wobei das Material des Substrates ausgewählt ist aus gewebten oder ungewebten Polymerfasern und die Beschichtung eine poröse, keramische Beschichtung ist, mit
  • 1. einer Mischung, enthaltend eine immobilisierbare Hydroxysilylalkylsäure von Schwefel oder Phosphor oder einem Salz davon; oder
  • 2. einer Mischung, enthaltend eine Brönstedsäure und/oder eine immobilisierbare Hydroxysilylalkylsäure von Schwefel oder Phosphor oder ein Salz davon sowie ein Sol, das eine Vorstufe für Oxide von Aluminium, Silizium, Titan, Zirkonium, und/oder Phosphor als Netzwerkbildner umfasst, oder
  • 3. einer Mischung, enthaltend Zirkonium- und/oder Titan-Phosphate, -Phosphonate und/oder - Sulfoarylphosphonate sowie gegebenenfalls ein Sol, das eine Vorstufe für Oxide von Aluminium, Silizium, Titan, Zirkonium, und/oder Phosphor als Netzwerkbildner umfasst und
• b) Verfestigung der den Träger infiltrierenden Mischung, um ein den Träger durchsetzendes Protonenleitfähiges Material zu schaffen, das geeignet ist selektiv Protonen durch die Membran zu leiten

erhalten wird. The present invention also relates to a proton-conductive, flexible electrolyte membrane for a fuel cell which is impermeable to the reaction components of a fuel cell reaction and which is characterized by

• a) infiltration of a carrier based on a permeable composite material, which has a flat, with a plurality of openings provided flexible substrate with a coating on and in this substrate, the material of the substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating with
  • 1. a mixture containing an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof; or
  • 2. a mixture containing a Bronsted acid and / or an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof and a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former, or
  • 3. a mixture containing zirconium and / or titanium phosphates, phosphonates and / or sulfoaryl phosphonates and, if appropriate, a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former and
• b) solidification of the mixture infiltrating the carrier in order to create a proton conductive material which penetrates the carrier and is suitable for selectively guiding protons through the membrane

is obtained.

• a) Infiltration eines Trägers, der auf einem stoffdurchlässigen Verbundwerkstoff basiert, der ein flächiges, mit einer Vielzahl von Öffnungen versehenes, flexibles Substrat mit einer auf und in diesem Substrat befindlichen Beschichtung aufweist, wobei das Material des Substrates ausgewählt ist aus gewebten oder ungewebten Polymerfasern und die Beschichtung eine poröse, keramische Beschichtung ist, mit
  • 1. einer Mischung, enthaltend eine immobilisierbare Hydroxysilylalkylsäure von Schwefel oder Phosphor oder einem Salz davon; oder
  • 2. einer Mischung, enthaltend eine Brönstedsäure und/oder eine immobilisierbare Hydroxysilylalkylsäure von Schwefel oder Phosphor oder ein Salz davon sowie ein Sol, das eine Vorstufe für Oxide von Aluminium, Silizium, Titan, Zirkonium, und/oder Phosphor als Netzwerkbildner umfasst, oder
  • 3. einer Mischung, enthaltend Zirkonium- und/oder Titan-Phosphate, -Phosphonate und/oder -Sulfoarylphosphonate sowie gegebenenfalls ein Sol, das eine Vorstufe für Oxide von Aluminium, Silizium, Titan, Zirkonium, und/oder Phosphor als Netzwerkbildner umfasst und
• b) Verfestigung der den Träger infiltrierenden Mischung, um ein den Träger durchsetzendes Protonenleitfähiges Material zu schaffen, das geeignet ist selektiv Protonen durch die Membran zu leiten.

The present invention also relates to a method for producing an electrolyte membrane according to the invention, which is characterized in that the method comprises the following steps:

• a) infiltration of a carrier based on a permeable composite material, which has a flat, with a plurality of openings provided flexible substrate with a coating on and in this substrate, the material of the substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating with
  • 1. a mixture containing an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof; or
  • 2. a mixture containing a Bronsted acid and / or an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof and a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former, or
  • 3. a mixture containing zirconium and / or titanium phosphates, phosphonates and / or sulfoaryl phosphonates and, if appropriate, a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former and
• b) solidification of the mixture infiltrating the carrier in order to create a proton conductive material which penetrates the carrier and is suitable for selectively guiding protons through the membrane.

At the same time, the subject of the present invention is a flexible one Membrane electrode unit for a fuel cell, with an electrically conductive anode and cathode layer, each on opposite sides of a particular one invention for the reaction components of the fuel cell reaction impermeable, proton conductive, flexible electrolyte membrane for a fuel cell are provided, the electrolyte membrane being a flexible, permeable material Composite material as a carrier comprises a flat, with a plurality of openings provided, flexible substrate with a coating located on and in this substrate has, wherein the material of the substrate is selected from woven or non-woven Polymer fibers and the coating is a porous, ceramic coating, and wherein the Carrier is interspersed with a proton conductive material, which is suitable, selective To conduct protons through the membrane, and being the anode layer and the cathode layer are porous and each have a catalyst for the anode and cathode reactions, one proton conductive component and optionally a catalyst support.

• A) Bereitstellung einer insbesondere erfindungsgemäßen für die Reaktionskomponenten der Brennstoffzellenreaktion undurchlässigen, protonenleitfähigen, flexiblen Elektrolytmembran für eine Brennstoffzelle, wobei die Elektrolytmembran einen flexiblen, stoffdurchlässigen Verbundwerkstoff als Träger umfasst, der ein flächiges, mit einer Vielzahl von Öffnungen versehenes, flexibles Substrat mit einer auf und in diesem Substrat befindlichen Beschichtung aufweist, wobei das Material des Substrates ausgewählt ist aus gewebten oder ungewebten Polymerfasern und die Beschichtung eine poröse, keramische Beschichtung ist, und wobei der Träger mit einem protonenleitfähigen Material durchsetzt ist, das geeignet ist, selektiv Protonen durch die Membran zu leiten,
• B) Bereitstellung jeweils eines Mittels zur Herstellung einer Anodenschicht und einer Kathodenschicht, wobei das Mittel jeweils umfasst:
  • 1. eine kondensierbare Komponente, die nach der Kondensation der Elektrodenschicht Protonenleitfähigkeit verleiht,
  • 2. einen Katalysator, der die Anodenreaktion bzw. die Kathodenreaktion katalysiert, oder eine Vorstufenverbindung des Katalysators,
  • 3. gegebenenfalls einen Träger und
  • 4. gegebenenfalls einen Porenbildner,
• C) Aufbringen der Mittel aus Stufe (B) auf jeweils eine Seite der Elektrolytmembran zur Bildung einer Beschichtung,
• D) Schaffung eines festen Verbundes zwischen den Beschichtungen und der Elektrolytmembran unter Ausbildung einer porösen, protonenleitfähigen Anodenschicht oder Kathodenschicht, wobei die Ausbildung der Anodenschicht und der Kathodenschicht gleichzeitig oder nacheinander erfolgen kann.

The present invention also relates to a method for producing a membrane electrode unit according to the invention, the method comprising the following steps,

• A) Provision of a proton-conductive, flexible electrolyte membrane for a fuel cell, in particular one that is impermeable to the reaction components of the fuel cell reaction, the electrolyte membrane comprising a flexible, permeable composite material as a carrier, which has a flat substrate with a plurality of openings and a substrate on and has coating located in this substrate, wherein the material of the substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating, and wherein the carrier is permeated with a proton-conductive material which is suitable for selectively protons through the membrane conduct,
• B) Provision in each case of an agent for producing an anode layer and a cathode layer, the agent in each case comprising:
  • 1. a condensable component which gives proton conductivity after the condensation of the electrode layer,
  • 2. a catalyst which catalyzes the anode reaction or the cathode reaction, or a precursor compound of the catalyst,
  • 3. optionally a carrier and
  • 4. if necessary, a pore former,
• C) applying the agents from stage (B) to one side of the electrolyte membrane to form a coating,
• D) Creation of a firm bond between the coatings and the electrolyte membrane with the formation of a porous, proton-conductive anode layer or cathode layer, it being possible for the anode layer and the cathode layer to be formed simultaneously or in succession.

• 1. eine kondensierbare Komponente, die nach der Kondensation einer Anodenschicht oder einer Kathodenschicht einer Membranelektrodeneinheit einer Brennstoffzelle Protonenleitfähigkeit verleiht,
• 2. einen Katalysator, der die Anodenreaktion oder die Kathodenreaktion in einer Brennstoffzelle katalysiert, oder eine Vorläuferverbindung des Katalysators,
• 3. gegebenenfalls einen Katalysatorträger und
• 4. gegebenenfalls einen Porenbildner, und
• 5. gegebenenfalls Additive zur Verbesserung von Schaumverhalten, Viskosität und Haftung.

The present invention also relates to an agent comprising:

• 1. a condensable component which, after the condensation of an anode layer or a cathode layer of a membrane electrode assembly, imparts proton conductivity to a fuel cell,
• 2. a catalyst which catalyzes the anode reaction or the cathode reaction in a fuel cell, or a precursor compound of the catalyst,
• 3. optionally a catalyst support and
• 4. optionally a pore former, and
• 5. optionally additives to improve foam behavior, viscosity and adhesion.

At the same time, the present invention relates to the use of a electrolyte membrane according to the invention in a fuel cell or for the production of a Membrane electrode unit, a fuel cell, or a fuel cell stack.

The present invention also relates to the use of a device according to the invention Membrane electrode unit in a fuel cell and fuel cells with one electrolyte membranes according to the invention or according to the invention Membrane electrode assemblies.

The membranes according to the invention are gas-tight or impermeable to Reaction components in a fuel cell, such as. B. hydrogen, oxygen, air and / or methanol. Under gas-tight or impermeable to the reaction components in the Understand the present invention that through the membranes of the invention less than 50 liters of hydrogen and less than 25 liters of oxygen per day, bar and Square meter passes through and the permeability of the membrane for methanol significantly lower is as with commercial Nafion membranes, which are usually also considered impermeable be designated.

The membranes according to the invention have the advantage that they are high Proton conductivity with significantly reduced air humidity compared to conventional ones Have polymer membranes. In addition, enable according to the invention Electrolyte membranes produce membrane electrode assemblies that are low Have total resistance, the good mechanical properties, such as tensile and Compressive strength as well as flexibility, which are suitable for use under extreme conditions Conditions, as they occur when operating a vehicle, are increased Tolerate operating temperatures of more than 80 ° C and short circuits and in direct methanol Avoid fuel cell cross-over problems.

With the method according to the invention, membranes are obtained which also have the advantage have that they can be extremely flexible and a bending radius of a few mm or more can have below. This is another advantage compared to the PEMs based of MF membranes based on glass fiber supports, which are quite brittle and due to this fact easily catastrophic when sealing or when operating in the fuel cell can fail. The membrane according to the invention based on polymer fibers Composite materials show practically the same elasticity but also the same Strength like the composite materials themselves or like the polymeric fabrics, knitted fabrics, felts or nonwovens on which these composite materials are based.

The electrolyte membrane of the present invention also has the advantage that it does not need to be swelled in water to provide useful conductivity. It is therefore much easier to combine the electrodes and the electrolyte membrane To combine membrane electrode assembly. In particular, there is no need for one to provide the swollen membrane with an electrode layer, as in the case of a Nafion membrane is necessary to prevent the electrode layer from swelling tears. The choice of the special carrier also ensures firm adhesion of the porous one Ceramic material on the carrier possible. This enables a stable MEA to be produced that can withstand high mechanical loads. Due to the good stability and The electrolyte membranes according to the invention can be conductive in a reformate or Direct methanol fuel cells are used, the long service life as well as long Power densities even at low water partial pressures and high temperatures provide. It is also possible to maintain the water balance of the new membrane electrode units by adjusting the hydrophobicity / hydrophilicity of the membrane and electrodes. Through the targeted creation of nanopores in the membrane, the effect of Use capillary condensation. A flooding of the electrodes by product water or Drying out of the membrane at a higher operating temperature or current density can thus be avoided. Through the use of diffusion barriers, i.e. proton conductive Coatings that are not soluble in water and methanol can also do that Prevent the phenomenon of electrolyte bleeding.

The membranes according to the invention, the method according to the invention for producing them Membrane as well as the various uses or articles that this membrane are described below, without the invention being based on this Types of execution should be limited.

The inventive for the reaction components of a fuel cell reaction impermeable, proton-conductive, flexible electrolyte membrane for a fuel cell, comprising a flexible, permeable composite material as a carrier, which has a flat, flexible substrate with a plurality of openings, with and on and in it Has coating located substrate, wherein the material of the substrate is selected Made of woven or non-woven polymer fibers and the coating is a porous, ceramic Is coating, and wherein the carrier is permeated with a proton conductive material, which is suitable for selectively passing protons through the membrane. The proton-conducting material has a plastic and / or elastic deformability.

• a) eine immobilisierte Hydroxysilylalkylsäure von Schwefel oder Phosphor sowie gegebenenfalls ein Oxid von Aluminium, Silizium, Titan, Zirkonium und/oder Phosphor als Netzwerkbildner, und/oder
• b) eine Brönstedsäure und ein Oxid von Aluminium, Silizium, Titan, Zirkonium, und/oder Phosphor als Netzwerkbildner, und/oder
• c) Zirkonium- und/oder Titan-Phosphate, -Phosphonate und/oder -Sulfoarylphosphonate sowie gegebenenfalls ein Oxid von Aluminium, Silizium, Titan, Zirkonium und/oder Phosphor als Netzwerkbildner

The proton conductive material preferably comprises

• a) an immobilized hydroxysilylalkyl acid of sulfur or phosphorus and optionally an oxide of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former, and / or
• b) a Bronsted acid and an oxide of aluminum, silicon, titanium, zirconium, and / or phosphorus as a network former, and / or
• c) zirconium and / or titanium phosphates, phosphonates and / or sulfoaryl phosphonates and optionally an oxide of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former

• a) Infiltration eines Trägers, der auf einem stoffdurchlässigen Verbundwerkstoff basiert, der ein flächiges, mit einer Vielzahl von Öffnungen versehenes, flexibles Substrat mit einer auf und in diesem Substrat befindlichen Beschichtung aufweist, wobei das Material des Substrates ausgewählt ist aus gewebten oder ungewebten Polymerfasern und die Beschichtung eine poröse, keramische Beschichtung ist, mit
  • 1. einer Mischung, enthaltend eine immobilisierbare Hydroxysilylalkylsäure von Schwefel oder Phosphor oder einem Salz davon; oder
  • 2. einer Mischung, enthaltend eine Brönstedsäure und/oder eine immobilisierbare Hydroxysilylalkylsäure von Schwefel oder Phosphor oder ein Salz davon sowie ein Sol, das eine Vorstufe für Oxide von Aluminium, Silizium, Titan, Zirkonium, und/oder Phosphor umfasst, oder
  • 3. einer Mischung, enthaltend Zirkonium- und/oder Titan-Phosphate, -Phosphonate und/oder - Sulfoarylphosphonate sowie gegebenenfalls ein Sol, das eine Vorstufe für Oxide von Aluminium, Silizium, Titan, Zirkonium, und/oder Phosphor als Netzwerkbildner umfasst und
• b) Verfestigung der den Träger infiltrierenden Mischung, um ein den Träger durchsetzendes Protonenleitfähiges Material zu schaffen, das geeignet ist selektiv Protonen durch die Membran zu leiten, erhältlich.

The proton-conductive, flexible electrolyte membranes for a fuel cell, which are impermeable to the reaction components of the fuel cell reaction, are e.g. B. by

• a) infiltration of a carrier based on a permeable composite material, which has a flat, with a plurality of openings provided flexible substrate with a coating on and in this substrate, the material of the substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating with
  • 1. a mixture containing an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof; or
  • 2. a mixture containing a Bronsted acid and / or an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof and a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus, or
  • 3. a mixture containing zirconium and / or titanium phosphates, phosphonates and / or sulfoaryl phosphonates and, if appropriate, a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former and
• b) Solidification of the mixture infiltrating the carrier in order to create a proton conductive material which penetrates the carrier and is suitable for selectively guiding protons through the membrane.

The gel-like structure is ensured by crosslinking the components, the Crosslinking by poly- or oligomerization, especially the hydroxysilylalkyl acids and / or by using the oxides mentioned as network formers.

The proton-conducting material can be an organic and / or an inorganic material. The proton-conducting material can only have material that is proton-conducting Has properties or not in addition to the material with proton-conducting properties have proton-conducting material which, for. B. have support functions or networks can form.

The proton-conductive material of an electrolyte membrane according to the invention preferably comprises a Bronsted acid, an immobilized hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof. These components impart proton conductivity to the electrolyte membrane. The proton-conductive material can optionally contain an oxide of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former. Such an oxide is essential when using Bronsted acid. In the event that an immobilized hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof is present, the additional oxide can be dispensed with, since an SiO ₂ network can form in which the acidic groups contain Si-R-SO ₃ H or SR-PO (OR) (OH) with R = alkyl or aryl radical. The network can also contain other network-forming oxides such as SiO ₂ , Al ₂ O ₃ , ZrO ₂ , or TiO ₂ .

The Bronsted acid can e.g. B. sulfuric acid, phosphoric acid, perchloric acid, nitric acid, hydrochloric acid, sulfurous acid, phosphorous acid and esters thereof and / or a monomeric or polymeric organic acid. Preferred organic acids are immobilized sulfonic and / or phosphonic acids. The oxides of Al, Zr, Ti and Si are used as network formers. In this case, z. B. ZrO ₂ or TiO _{2 from} a network in which the acid residues z. B. the phosphates or phosphonates are immobilized via Zr-OP or Ti-OP groups.

As the hydroxysilylalkyl acid of sulfur or phosphorus, the proton-conductive material in the electrolyte membrane according to the invention preferably has an organosilicon compound of the general formulas

[{(RO) _y (R ² ) _z } _a Si {R ¹ -SO ₃ ^- } _a ] _x M ^{x +} (I)

or

[(RO) _y (R ² ) _z Si {R ¹ -O _b -P (O _c R ³ ) O ₂ ^- } _a ] _x M ^{x +} (II)

where R ^{1 is} a linear or branched alkyl or alkylene group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms or a unit of the general formulas


stands,
where n, m each represents an integer from 0 to 6,
M represents H, NH ₄ or a metal,
x = 1 to 4,
y = 1 to 3, z = 0 to 2 and a = 1 to 3, with the proviso that
y + z = 4 - a,
b, c = 0 or 1,
R, R ^{2 are the} same or different and stand for methyl, ethyl, propyl, butyl or H and
R ^{3 represents} M or a methyl, ethyl, propyl or butyl radical.

The proton-conductive material particularly preferably has in the inventive Electrolyte membrane as hydroxysilylalkyl acid of sulfur or phosphorus Trihydroxysilylpropylsulfonic acid, trihydroxysilylpropylmethylphosphonic acid or Dihydroxysilylpropylsulfonedioic acid.

The hydroxysilylalkyl acid of sulfur or phosphorus is preferred with a hydrolyzed compound of phosphorus or a hydrolyzed nitrate, oxynitrate, chloride, Oxychloride, carbonate, alcoholate, acetate, acetylacetonate of a metal or semimetal or a hydrolyzed compound obtained from diethyl phosphite (DEP), diethyl ethyl phosphonate (DEEP), titanium propylate, titanium ethylate, tetraethyl orthosilicate (TEOS) or Tetramethyl orthosilicate (TMOS), zirconium nitrate, zirconium oxynitrate, zirconium propylate, Zirconium acetate, zirconium acetylacetonate, phosphoric acid methyl ester or with precipitated Immobilized silica.

The proton-conductive material of the mixtures (a1) or (a2) can also be zirconium and / or Titanium phosphates, phosphonates and / or sulfoaryl phosphonates, wherein the Crosslinking or gel formation through at least one oxide of aluminum, silicon, titanium, Zirconium and / or phosphorus takes place.

It can be advantageous if the proton-conductive material has ceramic particles from at least one oxide selected from the series Al ₂ O ₃ , SiO ₂ , ZrO ₂ or TiO ₂ . The proportion of ceramic particles which make no contribution to proton conductivity in the proton conductive material is preferably less than 40 volume percent, particularly preferably less than 30 volume percent and very particularly preferably less than 10 volume percent. It can be advantageous if the ceramic particles have one or more particle size fractions with particle sizes in the range from 10 to 100 nm and / or from 100 to 1000 nm. Particle fractions with particle sizes of 50 nm to 500 nm are particularly preferred, such as. B. Aerosil 200, Aerosil Ox50 or Aerosil VP 25 (each Degussa AG), or very fine-scaled particles, the z. B. be used directly as a suspension, such as. B. Levasil 200E (Bayer AG). However, it should be noted here that the particles used are significantly smaller than the smallest pore diameter of the composite material serving as the carrier. The average particle diameter is typically less than 1/2, preferably less than 1/5 and very particularly preferably less than 1/10 of the average pore diameter of the composite material used.

In contrast to the conventional proton conductive Microfiltration membranes based on e.g. B. Glass fabrics have the membranes of the invention significantly higher proportion of material with proton-conducting properties because the nonwovens preferably used as a substrate have a significantly higher porosity of up to 90% or even beyond. The electrolyte membrane according to the invention has preferably a volume ratio of proton conductive material to carrier of at least 20 to 80 on. The volume ratio of proton-conductive is preferably Material to carrier from 25 to 75 to 45 to 55 and very particularly preferably from 30 to 70 to 40 to 60.

It can be advantageous if the proton-conductive material has further proton-conducting substances. Preferred proton-conducting substances are e.g. For example, selected from the titanium phosphates, Titanphosphonaten, Titansulfoarylphosphonate, zirconium phosphates, Zirkoniumphosphonaten, Zirkoniumsulfoarylphosphonate, iso- and heteropoly acids, preferably tungstophosphoric acid or silicotungstic acid, or nano-crystalline metal oxides and Al ₂ O ₃ - ZrO ₂ -, TiO ₂ - or SiO ₂ powder are preferred. These can also (if necessary) form the proton-conducting material in combination with the network formers mentioned. In this case, ZrO ₂ or TiO _{2 form} a network in which the phosphates or phosphonates are immobilized via Zr-OP or Ti-OP groups.

The electrolyte membrane according to the invention preferably comprises a composite of based on a flat, flexible substrate provided with a large number of openings with a coating on and in this substrate, the material of the Substrate is selected from nonwovens, knitted fabrics, felting or woven fabrics of polymer fibers, preferably from nonwovens of polymer fibers. The coating of the substrate is preferably a porous, ceramic coating. By using a fleece, preferably a very thin and homogeneous non-woven material, becomes a uniform one Porosity achieved.

The substrate of the composite material used particularly preferably has a thickness of 10 to 150 µm. It can be particularly advantageous if the invention Electrolyte membrane has a composite material with a substrate, which has a thickness from 30 to 75 µm, preferably from 25 to 50 µm and particularly preferably from 30 to 40 µm having. It can be advantageous if the substrate contains polymer fibers and / or filaments a diameter of 1 to 50 microns, in particular from 1 to 20 microns. Are the Polymer fibers significantly thicker than the areas mentioned, the flexibility of the substrate suffers and thus also that of the membrane.

The polymer fibers are preferably selected from polyacrylonitrile, polyamides, polyimides, Polyacrylates, polytetrafluoroethylene, polyesters such as B. polyethylene terephthalate and / or Polyolefin. But all other known polymer fibers are also conceivable. Preferably, the membrane of the invention polymer fibers having a softening temperature of greater 100 ° C, a glass transition temperature greater than -10 ° C and a melting temperature of have greater than 150 ° C.

The ceramic coating located on and in the substrate preferably has an oxide of the metals Al, Zr, Si, Ti and / or Y. It particularly preferably has and in which Coating located in the substrate is an oxide of the metals Al, Ti, Zr and / or Si, as inorganic component.

There is preferably at least one inorganic in the coating of the composite material Component in a grain size fraction with an average grain size of 1 to 250 nm or with an average grain size of 251 to 10000 nm, preferably with an average grain size from 250 to 1750 nm or from 300 to 1250 nm. It can be beneficial if the membrane according to the invention has a coating which has at least two Has grain size fractions of at least one inorganic component. It can also be be advantageous if the coating has at least two grain size fractions of at least has two inorganic components. The grain size ratio can range from 1: 1 to 1: 10000, preferably from 1: 1 to 1: 100. The ratio of the Grain size fractions in the composite material can preferably be from 0.01: 1 to 1: 0.01 be.

It can be advantageous if the ceramic coating or the inorganic components that make up the coating are bonded to the substrate, in particular the polymer fibers, via adhesion promoters. Typical adhesion promoters are e.g. B. organofunctional silanes, such as those offered by Degussa under the trade name "Dynasilan", but also pure oxides such as ZrO ₂ , TiO ₂ , SiO ₂ or Al ₂ O ₃ can be suitable adhesion promoters for some fiber materials. Depending on the production conditions and the adhesion promoter used, the adhesion promoters can still be detectably present in the composite materials used according to the invention.

It may be advantageous if the fleece or fabric is first coated with an adhesion promoter was pre-coated. Accordingly, such a composite material then has an interior Fleece, preferably a polymer fleece, the fibers of which are covered with a thin layer of a Adhesion promoter (such as a metal oxide or an organosilane compound) equipped are. The porous is in and on the polymeric, pre-coated carrier Ceramic material.

The carrier must be used both in the course of the production of the electrolyte membrane and under the Operating conditions in a fuel cell must be stable. Therefore, the polymer is for the Carriers comprising polymer fibers are preferably stable to protons by the Membrane and are directed towards the proton-conducting material (gel) with which the Membrane is penetrated.

In the event that the carrier is a fabric, it is preferably a Fabric made of 11-Tex yarns with 5-50 warp or weft threads and in particular 20-28 warp and 28-36 wefts. 5.5 Tex yarns with 10-50 warp yarns are particularly preferred. or weft threads and preferably 20-28 warp and 28-36 weft threads.

The electrolyte membrane according to the invention is preferably at least 80 ° C. preferably at least 100 ° C, and very particularly preferably at least 120 ° C, stable.

The electrolyte membrane preferably has a thickness in the range from 10 to 150 μm, preferably 10 to 80 μm, very particularly preferably 10 to 50 μm. The invention Electrolyte membrane preferably tolerates a bending radius down to 5000 m, preferably 100 m, in particular down to 50 cm, preferably 20 mm and entirely particularly preferably down to 2 mm.

The electrolyte membrane according to the invention exhibits at room temperature and at a relative Air humidity of at most 80%, preferably a conductivity of at least 5 mS / cm, preferably at least 20 mS / cm, very particularly preferably at least 50 mS / cm The electrolyte membrane according to the invention preferably exhibits at room temperature and at a relative air humidity of maximum 50%, a conductivity of at least 5 mS / cm, preferably at least 20 mS / cm and very particularly preferably at least 50 mS / cm on.

It can be advantageous if the membrane according to the invention has an additional, outer proton-conducting coating on one side, preferably on both side surfaces, which is insoluble in water and methanol and which serves as a diffusion barrier and prevents leaching of an electrolyte from the electrolyte membrane. This coating preferably has a water- and methanol-insoluble proton-conducting material, such as Nafion®, sulfonated or phosphonated polyphenylsulfones, polyimides, polyoxazoles, polytriazoles, polybenzimidazoles, polyether ether ketones (PEEK), polyether ketones (PEK) or inorganic proton conductors, such as, for. B. immobilized sulfonic or phosphonic acid (z. B. hydroxysilylalkyl acids), zirconium or titanium phosphates or phosphonates. These inorganic proton conductors can also contain other oxides, e.g. B. of Al, Zr, Ti or Si, included as a network former. The organic proton-conducting polymers can be applied either as pure materials or in the form of inorganic-organic composite materials. Such composite materials can e.g. B. solidified solutions of Nafion with precipitated silica (Levasil®), tetraethoxysilane (Dynasilan A ®) or sols based on Al ₂ O ₃ , SiO ₂ , TiO ₂ or ZrO ₂ . The combination of organic proton conductors with immobilized sulfonic and phosphonic acids is also possible. The use of composite materials has the advantage that the adhesive strength of the protective layer on the membrane is better than that of the pure (hydrophobic) proton-conducting polymer. From the range of polymeric proton conductors in particular, however, it is also possible to use all materials for the production of composite materials which do not form thin films, or which form only very poorly, and which therefore separate as self-supporting membranes.

The presence of a diffusion barrier can prevent the membrane from bleeding out and the mechanical stability can be improved. This results in a higher one Long-term performance compared to membranes that show bleeding of the electrolyte.

To avoid performance losses that can occur because of the diffusion barrier has lower proton conductivity than the membrane according to the invention without Diffusion barrier, the diffusion barrier is made as thin as possible. Preferably points the diffusion barrier has a thickness of less than 5 μm, preferably from 10 to 1000 nm and entirely particularly preferably from 100 to 500 nm. Due to the very thin design of the Diffusion barrier, only affects the lower conductivity of the diffusion barrier the proton conductivity of the actual membrane is insignificant.

The production of the electrolyte membranes according to the invention is described below.

• a) Infiltration eines Trägers, der auf einem stoffdurchlässigen Verbundwerkstoff basiert, der ein flächiges, mit einer Vielzahl von Öffnungen versehenes, flexibles Substrat mit einer auf und in diesem Substrat befindlichen Beschichtung aufweist, wobei das Material des Substrates ausgewählt ist aus gewebten oder ungewebten Polymerfasern und die Beschichtung eine poröse, keramische Beschichtung ist, mit
  • 1. einer Mischung, enthaltend eine immobilisierbare Hydroxysilylalkylsäure von Schwefel oder Phosphor oder einem Salz davon, oder
  • 2. einer Mischung, enthaltend eine Brönstedsäure und/oder eine immobilisierbare Hydroxysilylalkylsäure von Schwefel oder Phosphor oder ein Salz davon sowie ein Sol, das eine Vorstufe für Oxide von Aluminium, Silizium, Titan, Zirkonium, und/oder Phosphor als Netzwerkbildner umfasst, oder
  • 3. einer Mischung, enthaltend Zirkonium- und/oder Titan-Phosphate, -Phosphonate und/oder - Sulfoarylphosphonate sowie gegebenenfalls ein Sol, das eine Vorstufe für Oxide von Aluminium, Silizium, Titan, Zirkonium, und/oder Phosphor als Netzwerkbildner umfasst und
• b) Verfestigung der in den Träger infiltrierten Mischung, um ein den Träger durchsetzendes protonenleitfähiges Material zu schaffen, das geeignet ist selektiv Protonen durch die Membran zu leiten.

An electrolyte membrane of the present invention is e.g. B. obtainable by the method according to the invention for producing an electrolyte membrane, which, starting from the permeable support, comprises in particular the following steps:

• a) infiltration of a carrier based on a permeable composite material, which has a flat, with a plurality of openings provided flexible substrate with a coating on and in this substrate, the material of the substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating with
  • 1. a mixture containing an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof, or
  • 2. a mixture containing a Bronsted acid and / or an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof and a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former, or
  • 3. a mixture containing zirconium and / or titanium phosphates, phosphonates and / or sulfoaryl phosphonates and, if appropriate, a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former and
• b) solidification of the mixture infiltrated into the carrier in order to create a proton-conductive material which penetrates the carrier and is suitable for selectively guiding protons through the membrane.

As available in the mixture Bronsted acid z. B. sulfuric acid, phosphoric acid, Perchloric acid, nitric acid, hydrochloric acid, sulfurous acid, phosphorous acid as well as esters thereof and / or a monomeric or polymeric organic acid become. Preferred organic acids are immobilizable sulfonic acids and / or Phosphonic acids. The oxides of Al, Zr, Ti and Si be used.

Organosilicon compounds of the general formulas are preferably used as the hydroxysilylalkyl acid of sulfur or phosphorus in the mixture

[{(RO) _y (R ² ) _z } _a Si {R ¹ -SO ₃ ^- } _a ] _x M ^{x +} (II)

or

[(RO) _y (R ² ) _z Si {R ¹ -O _b -P (O _c R ³ ) O ₂ ^- } _a ] _x M ^{x +} (II)

used, where R ^{1 is} a linear or branched alkyl or alkylene group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms or a unit of the general formulas


stands,
where n, m each represents an integer from 0 to 6,
M represents H, NH ₄ or a metal,
x = 1 to 4,
y = 1 to 3, z = 0 to 2 and a = 1 to 3, with the proviso that
y + z = 4 - a,
b, c = 0 or 1,
R, R ^{2 are the} same or different and stand for methyl, ethyl, propyl, butyl or H and
R ^{3 represents} M or a methyl, ethyl, propyl or butyl radical.

Particularly preferred are hydroxysilylalkyl acid of sulfur or phosphorus Trihydroxysilylpropylsulfonic acid, trihydroxysilylpropylmethylphosphonic acid or Dihydroxysilylpropyl sulfonedioic acid used in the mixture.

The hydroxysilylalkyl acid of sulfur or phosphorus is preferred with a hydrolyzed compound of phosphorus or a hydrolyzed nitrate, oxynitrate, chloride, Oxychloride, carbonate, alcoholate, acetate, acetylacetonate of a metal or semimetal or a hydrolyzed compound obtained from diethyl phosphite (DEP), diethyl ethyl phosphonate (DEEP), titanium propylate, titanium ethylate, tetraethyl orthosilicate (TEOS) or Tetramethyl orthosilicate (TMOS), zirconium nitrate, zirconium oxynitrate, zirconium propylate, Zirconium acetate, zirconium acetylacetonate, phosphoric acid methyl ester or with precipitated Immobilized silica.

It can be advantageous if the mixture contains further proton-conducting substances selected from the group of iso- or heteropolyacids, such as, for example, tungsten phosphoric acid or silicon tungstic acid, zeolites, mordenites, aluminosilicates, β-aluminum oxides, zirconium, titanium or cerium phosphates or phosphonates sulfoarylphosphonates, antimonic acids, phosphorus oxides, sulfuric acid, perchloric acid or their salts and / or crystalline metal oxides, preference being given to Al ₂ O ₃ , ZrO ₂ , TiO ₂ or SiO ₂ powders.

The mixture with which the carrier is infiltrated preferably has a sol which is obtainable by hydrolysis of a hydrolyzable compound, preferably in one Mixture of water and alcohol, to form a hydrolyzate, the hydrolyzable Compound is selected from hydrolyzable alcoholates, acetates, acetylacetonates, Nitrates, oxynitrates, chlorides, oxychlorides, carbonates, of aluminum, silicon, titanium, Zirconium, and / or phosphorus or esters, preferably methyl esters, ethyl esters and / or Propyl esters of phosphoric acid or phosphorous acid, and peptization of the hydrolyzate to a sol.

It may be advantageous if the hydrolyzable compound is non-hydrolyzable groups in addition to hydrolyzable groups. It is preferred to be hydrolyzed as such Compound an alkyltrialkoxy or dialkyl dialkoxy or trialkylalkoxy compound of Silicon used.

An acid or base which is soluble in water and / or alcohol can be added to the mixture as the hydrolysis and condensation catalyst. Preferably a mineral acid, such as. B. H ₂ SO ₄ , H ₃ PO ₄ , HNO ₃ or HCl are added.

It can furthermore be advantageous if the mixture for infiltrating the carrier next to one Trialkoxysilane as a network former also acidic or basic compounds and water includes. The acidic or basic compounds preferably comprise at least one of the Brönstedt or Lewis acid or base known to those skilled in the art.

Trihydroxysilyl acids are known from EP 0 771 589, EP 0 765 897 and EP 0 582 879. In These publications have made the manufacture of molded acid catalysts based described by trihydroxysilylpropylsulfonic acid and trihydroxysilylpropyl mercaptan.

In a preferred embodiment, the brine or mixtures also contain ceramic Particles that can take on the function of fillers or network formers. The oxides, in particular pyrogenic oxides of the elements Si, Al, are particularly preferred. Zr, Ti. These can be in several particle size fractions. It can be beneficial if the ceramic particles have one or more particle size fractions with particle sizes have in the range from 10 to 100 nm and / or from 100 to 1000 nm. Are preferred here particle fractions with particle sizes of 50 nm-500 nm, such as. B. Aerosil 200, Aerosil Ox50 or Aerosil VP 25 (all Degussa AG), or very fine-scale particles, which e.g. B. be used directly as a suspension, such as. B. Levasil 200E. It is important that the Particles added to the brine are significantly smaller than the pore size of the MF Membrane. With a pore size of the MF membrane of 450 nm, the particles should be significantly less than 100 nm, better less than 50 nm.

The mixtures are preferred by suitable measures, such as. B. by longer Stirring with a magnetic stirrer or wave stirrer, using an Ultraturrax or attritor mill or homogenized using ultrasound before the actual infiltration is carried out.

Infiltration of the carrier can be done by printing, pressing, pressing, rolling, Doctor knife, spread, dip, spray or pour the mixture onto the permeable carrier. The infiltration with the mixture can be repeated be performed. If necessary, a drying step, preferably one elevated temperature in a range from 50 to 200 ° C, preferably from 100 to 150 ° C between repeated infiltration. In a preferred embodiment the infiltration of the carrier continuously. It can be advantageous if the carrier for Infiltration is preheated.

The mixture can be solidified in the carrier by heating to a temperature of 20 to 300 ° C, preferably 50 to 200 ° C, most preferably 80 to 150 ° C, the heating by heated air, hot air, infrared radiation or Microwave radiation can take place. It can be beneficial if heating for 1 second to 60 minutes at a temperature of 20 to 300 ° C. Especially the mixture is preferably heated for solidification, preferably for 0.5 to 5 Minutes to the temperatures mentioned.

The method for producing the electrolyte membrane according to the invention can, for. B. like this be carried out by unrolling the carrier from a roll with a Speed from 1 m / h to 2 m / s, preferably at a speed of 0.5 m / min. up to 20 m / min and very particularly preferably at a speed of 1 m / min to 5 m / min by at least one apparatus which brings the mixture onto and into the carrier and at least one other apparatus, which solidifies the mixture on and in the carrier made possible by heating, passes and the electrolyte membrane thus produced on a second roll is rolled up. In this way it is possible to use the invention Manufacture electrolyte membrane in a continuous process.

As a carrier, which is on a permeable composite material, which is a flat, with a A plurality of openings provided, flexible substrate with one on and in this substrate Coating located, based, wherein the material of the substrate is selected Made of woven or non-woven polymer fibers and the coating is a porous, ceramic Coating is, preferably composite materials are used as described above.

The composite material used is particularly preferably flexible and has a corresponding one good tensile strength, preferably a tensile strength of at least 1 N / cm, especially preferably of at least 3 N / cm. The composite material very particularly preferably has a tensile strength of at least 10 N / cm in the machine direction. By using it of composite materials with a high tensile strength ensures that the Electrolyte membrane has a high tensile strength similar to that of the composite material.

The composite materials are preferably obtainable by a process for producing a Membrane, which is characterized in that a flat, with a variety of Opened, flexible substrate in and on this substrate with a coating is provided, wherein the material of the substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating that is applied to the substrate by applying a suspension, which is at least one oxide the metals Al, Zr, Si Ti and / or Y and a sol, and wherein the suspension on or is solidified in or on and in the carrier by at least one heating. The Suspension can have other inorganic components.

The suspension can e.g. B. by printing, pressing, pressing, rolling, doctoring, Spreading, dipping, spraying or pouring onto and into the substrate.

The material of the substrate is preferably a polymer fabric, knitted fabric, felt or non-woven. A substrate, in particular a substrate, is preferably used to produce the composite material Fleece, which has a thickness of 10 to 150 microns. It can be particularly beneficial if the membrane according to the invention has a substrate which has a thickness of 30 to 75 μm, preferably from 25 to 50 microns and particularly preferably from 30 to 40 microns. It can be advantageous if the substrate polymer fibers and / or filaments with a diameter from 1 to 50 µm, in particular from 1 to 20 µm. Are the polymer fibers clear thicker than the areas mentioned, the flexibility of the substrate and thus that of the suffers Membrane.

The polymer fibers are preferably selected from polyacrylonitrile, polyamides, polyacrylates, Polyimides, polytetrafluoroethylene, polyesters such as e.g. B. polyethylene terephthalate and / or Polyolefin, e.g. B. polypropylene (PP), polyethylene (PE) or mixtures of these. But also all other known polymer fibers are conceivable. Preferably, the invention Membrane polymer fibers, which have a softening temperature of greater than 100 ° C, a Glass transition temperature of greater than -10 ° C and a melting temperature of greater than 150 ° C exhibit. In the case of polymer fibers with lower temperatures, these also decrease Application areas.

The suspension used to produce the coating of the composite material has preferably at least one inorganic oxide of aluminum, silicon, titanium and / or Zirconium and at least one sol, at least one semimetal oxide sol or at least one Mixed metal oxide sol or a mixture of this brine, and is by suspending at least one inorganic component in at least one of these brines.

The brines are hydrolyzed by at least one compound, preferably at least a metal compound, at least one semi-metal compound or at least one Mixed metal compound obtained. It can also be advantageous to hydrolyze the Compound prior to hydrolysis in alcohol or an acid or a combination of these To give liquids. The compound to be hydrolyzed is preferably at least one Metal nitrate, a metal chloride, a metal carbonate, a metal alcoholate compound or at least one semimetal alcoholate compound, particularly preferably at least one Metal alcoholate compound hydrolyzed. As a metal alcoholate compound or Semi-metal alcoholate compound is preferably an alcoholate compound of the elements Zr, Ti, Al, Si, Sn, Ce and Y or at least one metal nitrate, metal carbonate or metal halide selected from the metal salts of the elements Zr, Ti, Al, Si, Sn, Ce and Y as Metal compound hydrolyzed. The hydrolysis is preferably carried out in the presence of water, Water vapor, ice, or an acid, or a combination of these compounds.

In one embodiment variant for the production of the composite material, hydrolysis of the compounds to be hydrolyzed particulate brine. This particular brine are characterized by the fact that they are formed in the sol by hydrolysis Connections are particulate. The particulate sols can be as above or as in WO 99/15262 can be produced. These brines usually have a very high high water content, which is preferably greater than 50 wt .-%. It may be beneficial to compound to be hydrolyzed before hydrolysis in alcohol or an acid or a Combination of these liquids. The hydrolyzed compound can be used for Peptize with at least one organic or inorganic acid, preferably with one 10 to 60% organic or inorganic acid, particularly preferably with a Mineral acid selected from sulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid and Nitric acid or a mixture of these acids are treated. The so produced particulate sols can then be used to prepare suspensions, the production of suspensions for application to with polymeric sol pretreated polymer fiber webs is preferred.

In a further embodiment variant of the method for producing the composite material polymeric sols are produced by hydrolysis of the compounds to be hydrolyzed. These polymeric sols are characterized by the fact that they are in the sol by hydrolysis the resulting polymeric compounds (i.e. cross-linked over a larger space) available. The polymeric sols usually have less than 50% by weight, preferably much less than 20% by weight of water and / or aqueous acid. To the The preferred proportion of water and / or aqueous acid is the hydrolysis preferably carried out so that the compound to be hydrolyzed with the 0.5 to 10 times the molar ratio and preferably with half the molar ratio of water, steam or Ice, based on the hydrolyzable group, the hydrolyzable compound, hydrolyzed becomes. Up to 10 times the amount of water can hydrolyze very slowly Connections such as B. be used in tetraethoxysilane. Very fast hydrolyzing Compounds such as zirconium tetraethylate can already do so under these conditions form particulate sols, which is why preferably 0.5 times for the hydrolysis of such compounds Amount of water is used. Hydrolysis with less than the preferred amount Water, steam, or ice also lead to good results. Where a Falling below the preferred amount of half a molar ratio by more than 50% possible but not very sensible, since the hydrolysis does not fall below this value is more complete and coatings based on such brine are not very stable.

To produce this polymeric brine with the desired very low proportion of water and / or acid in the sol it can be advantageous if the compound to be hydrolyzed in an organic solvent, in particular ethanol, isopropanol, butanol, amyl alcohol, Hexane, cyclohexane, ethyl acetate and or mixtures of these compounds is dissolved before the actual hydrolysis is carried out. A sol produced in this way can be used to produce the Suspension or as an adhesion promoter in a pretreatment step.

Both the particulate brine and the polymer brine can be used as sol for the production of the Suspension used in the manufacture of the composite material used as a carrier become. In addition to the brines, which are available as just described, can in principle also commercial brine, such as. B. zirconium nitrate sol or silica sol can be used. The procedure the production of membranes (composite materials) by applying and solidifying a suspension on a carrier in and of itself is known from WO 99/15262, but leave not all parameters or input materials relate to the production of composite materials Transfer base of polymeric substrates. The process described in WO 99/15262 is, in this form, in particular not without compromises on polymeric nonwoven materials transferable, since the very water-containing brine systems described there, often none continuous wetting of the usually hydrophobic polymer fleece in depth enable, since the very water-containing sol systems do not or only do most polymer nonwovens poor wetting. It was found that even the smallest unwetted spots in the Fleece material can lead to the fact that composite materials or membranes are obtained, which have errors and are therefore unusable.

It has now surprisingly been found that a sol system or a suspension, which or which was adapted in the wetting behavior to the polymers, the Nonwoven materials are completely saturated and thus flawless coatings are available. The method according to the invention is therefore preferably adapted to the Wetting behavior of the sol or suspension. This adjustment is preferably done by the production of polymeric sols or suspensions from polymeric sols this brine one or more alcohols, such as. B. methanol, ethanol or propanol or Mixtures containing one or more alcohols, preferably aliphatic Have hydrocarbons include. But there are also other solvent mixtures conceivable, which can be added to the sol or the suspension to this in Adapt networking behavior to the substance used.

It was found that the fundamental change in the sol system and the resulting resulting suspension to a significant improvement in the adhesive properties of the ceramic components on and in a polymeric nonwoven material. Such good ones Adhesive strengths are usually not available with particulate sol systems. Substrates which have polymer fibers are therefore preferred by means of suspensions coated, which are based on polymeric sols or in an upstream step Treatment with a polymeric sol were equipped with an adhesion promoter.

It can be advantageous if, for the preparation of the suspension as an inorganic component, at least one oxide selected from the oxides of the elements Y, Zr, Al, Si, Sn, and Ti, in a sol is suspended. Preferably an inorganic component, at least a compound selected from aluminum oxide, titanium dioxide, zirconium oxide and / or Silicon dioxide, suspended. The mass fraction of the suspended is preferably Component 0.1 to 500 times, particularly preferably 1 to 50 times and very particularly preferably 5 to 25 times the sol used.

It can be advantageous if at least one inorganic component, which is a medium one Grain size from 1 to 10000 nm, preferably from 1 to 10 nm, 10 to 100 nm, 100 to 1000 nm or 1000 to 10000 nm, particularly preferably from 250 to 1750 nm and very particularly preferably from 300 to 1250 nm, is suspended in at least one sol. Through the Use of inorganic components that have an average grain size of 250 to 1250 nm will have a particularly suitable flexibility and porosity of the membrane or of the composite material reached.

To improve the adhesion of the inorganic components to polymer fibers as a substrate, it may be advantageous to add adhesion promoters, such as e.g. B. organofunctional silanes or pure oxides such as ZrO ₂ , TiO ₂ , SiO ₂ or Al ₂ O ₃ . The addition of the adhesion promoters, in particular to suspensions based on polymeric sols, is preferred. In particular, compounds selected from the octylsilanes, the fluorinated octylsilanes, the vinylsilanes, the amine-functionalized silanes and / or the glycidyl-functionalized silanes, such as, for. B. the Dynasilane from Degussa can be used. Particularly preferred adhesion promoters for polytetrafluoroethylene (PTFE) are e.g. B. fluorinated octylsilanes, for polyethylene (PE) and polypropylene (PP) it is vinyl, methyl and octylsilanes, whereby the exclusive use of methylsilanes is not optimal, for polyamides and polyamines it is amine-functional silanes, for polyacrylates and polyesters Glycidyl-functionalized silanes and for polyacrylonitrile it is also possible to use glycidyl-functionalized silanes. Other adhesion promoters can also be used, but these have to be matched to the respective polymers. The addition of methyltriethoxysilane described in WO 99/15262 to the sol system in the coating of polymeric carrier materials is a comparatively poor solution to the problem of the adhesive strength of ceramics on polymer fibers. In addition, the drying time of 30 to 120 minutes at 60 to 100 ° C. is not sufficient for the sol systems described in order to obtain hydrolysis-resistant ceramic materials. This means that these materials will dissolve or be damaged if they are stored in water-containing media for a long time. On the other hand, the temperature treatment of over 350 ° C. described in WO 99/15262 would lead to burning of the polymer fleece used here and thus to the destruction of the composite material. The adhesion promoters must therefore be selected so that the solidification temperature is below the melting or softening point of the polymer and below its decomposition temperature. Suspensions according to the invention preferably have significantly less than 25% by weight, preferably less than 10% by weight, of compounds which can act as adhesion promoters. An optimal proportion of adhesion promoter results from the coating of the fibers and / or particles with a monomolecular layer of the adhesion promoter. The amount of adhesion promoter required in grams can be obtained by multiplying the amount of oxides or fibers used (in g) by the specific surface area of the materials (in m ² g ^-1 ) and then dividing by the specific space requirement of the adhesion promoter (in m ² g ^-1 ) are obtained, the specific space requirement often being in the order of 300 to 400 m ² g ^-1 .

The following table contains an exemplary overview of usable adhesion promoters based on organofunctional Si compounds for typical polymers used as nonwoven material.

The coatings according to the invention are made by solidifying the suspension in and on the substrate applied to the substrate. According to the invention on and in the substrate existing suspension can be solidified by heating to 50 to 350 ° C. Since at the Using polymeric substrate materials the maximum temperature through the substrate is specified, it must be adjusted accordingly. Depending on the version of the Process the suspension on and in the substrate by heating to 100 to 350 ° C and very particularly preferably solidified by heating to 110 to 280 ° C. It can be beneficial if heating for 1 second to 60 minutes at a temperature of 100 to 350 ° C takes place. The suspension is particularly preferably heated to Solidify to a temperature of 110 to 300 ° C, most preferably at one Temperature from 110 to 280 ° C and preferably for 0.5 to 10 minutes.

When the composite material solidifies, it can be depending on the selected temperature level some polymer materials under the influence of temperature to changes in the chemical structure, so that the polymers no longer in their Initial state or modification exist. This can lead to partial carbonization of polyimides or to form so-called conductor polymers with polyacrylonitrile subsequent partial carbonization. These effects always lead to one Change in the properties of the substrates. Depending on the application, this can also be special are intended, as this would, for example, make it resistant to solvents, acids and alkalis can be increased. The degree of conversion can vary over temperature and time to be influenced.

The heating of the composite according to the invention can be done by means of heated air, hot air, Infrared radiation or by other heating methods according to the prior art respectively.

In a particular embodiment of the method according to the invention, the abovementioned adhesion promoters are applied to the substrate, in particular the polymer fleece, in an upstream step. For this, the in a suitable solvent, such as. B. dissolved ethanol. This solution can also contain a small amount of water, preferably 0.5 to 10 times the amount based on the molar amount of the hydrolyzable group, and small amounts of an acid, such as. B. HCl or HNO ₃ , as a catalyst for the hydrolysis and condensation of the Si-OR groups. By the known techniques such. B. spraying, printing, pressing, pressing, rolling, knife coating, brushing, dipping, spraying or pouring, this solution is applied to the substrate and the adhesion promoter is fixed by a temperature treatment at 50 to a maximum of 350 ° C. on the substrate. In this embodiment of the method according to the invention, the suspension is applied and solidified only after the adhesion promoter has been applied.

In another embodiment variant of the method according to the invention adhesion-promoting layers in a pretreatment step in which a polymeric sol, applied and solidified, applied. The application and solidification of the polymer This is preferably done in the same way as the application and solidification of the Suspensions. By applying this polymeric brine, the substrates, in particular the polymer fleece with an oxide of Al, Ti, Zr or Si as an adhesion promoter equipped, whereby the substrate is made hydrophilic. So equipped substrates can then according to the prior art described in WO 99/15262 or as above described can be equipped with a porous coating, whereby by the Pretreatment a significantly better adhesion of the coating, especially on Polymer fleeces can be observed.

A typical polymeric sol for pretreatment is about 0.1 to 10% by weight, and preferably 0.5 to 2% by weight, alcoholic solution of a metal alcoholate (such as Titanium ethylate or zirconium propylate), which additionally 0.5 to 10 mol parts of water and may contain small amounts of an acid as a catalyst. After applying one such sols on the substrate, the substrates, preferably polymer fleece in a Treated temperature of maximum 350 ° C. This creates a dense film from one Metal oxide around the substrate fibers, causing infiltration of the substrate with a Suspension or a slip based on a commercial zirconium nitrate sol or Silicasols is possible without wetting difficulties.

Because polymer sols tend to form dense films than particulate sols, and particulate sols it is always larger quantities of water in the pore structure of the intermediate grain volumes easier to dry polymeric brine than particulate brine. Still, they have to Composites are dried at temperatures above 150 ° C so that the ceramic material receives a sufficiently good adhesive strength on the carrier. Particularly good ones Adhesive strengths can be achieved at a temperature of at least 200 ° C and especially achieve good strength at a temperature of at least 250 ° C. However, are for this then correspondingly temperature-stable polymers are absolutely necessary, such as Polyethylene terephthalate (PET), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), Polyvinylidene fluoride (PVDF) or polyamide (PA). If the substrate is not enough temperature stable, can be pre-dried at a lower temperature (up to 100 ° C) the composite material is first pre-consolidated. When consolidating at then the ceramic layer acts as a support for the support so that it does not more of the substrate can melt away. These process parameters apply not only for the application and solidification of a polymeric sol z. B. as an adhesion promoter but also for the application and solidification of suspensions based on polymers Solen.

By both types of application of an adhesion promoter before the actual one Applying the suspension can particularly adversely affect the adhesive behavior of the substrates aqueous, particulate sols can be improved, which is why pretreated in particular Substrates with suspensions based on commercially available sols, such as. B. Zirconium nitrate sol or silica sol can be coated according to the invention. This approach of Applying an adhesion promoter also means that the manufacturing process of the Composite material must be expanded by an intermediate or pretreatment step. This is feasible, however, also more complex than the use of adapted brines to which adhesion promoters have been added, but also has the advantage that when used better results are obtained from suspensions based on commercially available brines.

The inventive method can, for. B. be carried out so that the substrate of a roll is unrolled, at a speed of 1 m / h to 2 m / s, preferably with a speed of 0.5 m / min. up to 20 m / min and very particularly preferably with a Velocity from 1 m / min to 5 m / min by at least one apparatus which the Suspension on and in the support, such as B. a roller and at least one other Apparatus which solidifies the suspension on and in the support by heating enables such. B. passes through an electrically heated oven and the so produced Composite material is rolled up on a second roll. In this way it is possible to Manufacture composite material according to the invention in a continuous process. Also the Pretreatment steps can be carried out in a continuous process while maintaining the above Parameters are carried out.

Those materials or membranes are preferably used as the composite material average pore sizes from 5 to 5000 nm, particularly preferably from 10 to 1000 nm and entirely particularly preferably have from 100 to 800 nm. According to the desired one As is known to the person skilled in the art, pore size becomes a suitable particle size of the ceramic Powder used in the sol / slip.

A membrane electrode unit according to the invention is described below. The Flexible membrane electrode assembly for a fuel cell comprises an anode layer and a cathode layer, each on opposite sides for the Reaction components of the fuel cell reaction impermeable, proton conductive, flexible electrolyte membrane are provided for a fuel cell, the Electrolyte membrane comprises a flexible, permeable composite material as a carrier, which has a flat substrate with a plurality of openings and a flexible substrate and coating located in this substrate, wherein the material of the substrate is selected from woven or non-woven polymer fibers and the coating one is porous, ceramic coating, and wherein the carrier with a proton conductive Is penetrated material that is capable of selectively guiding protons through the membrane, and wherein the anode layer and the cathode layer are porous and each have a catalyst for the anode and cathode reaction, a proton conductive component and optionally comprise a catalyst carrier.

• a) eine immobilisierte Hydroxysilylalkylsäure von Schwefel oder Phosphor oder ein Salz davon sowie gegebenenfalls ein Oxid von Aluminium, Silizium, Titan, Zirkonium und/oder Phosphor, und/oder
• b) eine Brönstedsäure und ein Oxid von Aluminium, Silizium, Titan, Zirkonium, und/oder Phosphor und/oder
• c) Zirkonium- und/oder Titan-Phosphate, -Phosphonate und/oder Sulfoarylphosphonate sowie gegebenenfalls ein Oxid von Aluminium, Silizium, Titan, Zirkonium und/oder Phosphor als Netzwerkbildner.

The proton-conductive component of the anode and / or cathode layer and / or the proton-conductive material of the electrolyte membrane each preferably comprises

• a) an immobilized hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof and optionally an oxide of aluminum, silicon, titanium, zirconium and / or phosphorus, and / or
• b) a Bronsted acid and an oxide of aluminum, silicon, titanium, zirconium, and / or phosphorus and / or
• c) zirconium and / or titanium phosphates, phosphonates and / or sulfoaryl phosphonates and optionally an oxide of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former.

The Bronsted acid can e.g. B. sulfuric acid, phosphoric acid, perchloric acid, nitric acid, Hydrochloric acid, sulfurous acid, phosphorous acid and esters thereof and / or one be monomeric or polymeric organic acid.

In a preferred embodiment, the hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof is an organosilicon compound of the general formulas

[{(RO) _y (R ² ) _z } _a Si {R ¹ -SO ₃ ^- } _a ] _x M ^{x +} (I)

or

[(RO) _y (R ² ) _z Si {R ¹ -O _b -P (O _c R ³ ) O ₂ ^- } _a ] _x M ^{x +} (II)

where R ^{1 is} a linear or branched alkyl or alkylene group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms or a unit of the general formula n


stands,
where n, m each represents an integer from 0 to 6,
M represents H, NH ₄ or a metal,
x = 1 to 4,
y = 1 to 3, z = 0 to 2 and a = 1 to 3, with the proviso that
y + z = 4 - a,
b, c = 0 or 1,
R, R ^{2 are the} same or different and stand for methyl, ethyl, propyl, butyl or H and
R ^{3 represents} M or a methyl, ethyl, propyl or butyl radical.

The hydroxysilylalkyl acid of sulfur or phosphorus is preferred Trihydroxysilylpropylsulfonic acid, trihydroxysilylpropylmethylphosphonic acid or Dihydroxysilylpropylsulfondisäure. The hydroxysilylalkyl acid is preferably sulfur or phosphorus or a salt thereof with a hydrolyzed compound of the phosphorus or a hydrolyzed nitrate, oxynitrate, chloride, oxychloride, carbonate, alcoholate, acetate, Acetylacetonate of a metal or semi-metal immobilized. In another preferred The embodiment is the hydroxysilylalkyl acid of sulfur or phosphorus or Salt thereof with a hydrolyzed compound obtained from titanium propylate, titanium ethylate, Tetraethyl orthosilicate (TEOS) or tetramethyl orthosilicate (TMOS), zirconium nitrate, Zirconium oxynitrate, zirconium propylate, zirconium acetate, zirconium acetylacetonate, Phosphoric acid methyl ester, diethyl phosphite (DEP) or diethyl ethyl phosphonate (DEEP) immobilized.

The proton-conductive component of the anode and / or cathode layer may also include proton-conducting materials selected from titanium phosphates, Titanphosphonaten, zirconium phosphates, Zirkoniumphosphonaten, iso- and heteropoly acids, preferably tungstophosphoric acid or silicotungstic acid, or nano-crystalline metal oxides and Al ₂ O ₃ - ZrO ₂ -, TiO ₂ or SiO ₂ powder are preferred.

The membrane electrode assembly according to the invention can preferably be used in a fuel cell at a temperature of at least 80 ° C, preferably at least 100 ° C, and completely are particularly preferably operated at at least 120 ° C. The invention Membrane electrode unit preferably tolerates a bending radius of at least 5000 mm, preferably 100 mm, in particular of at least 50 mm and particularly preferably of at least 20 mm. The inventive method very particularly preferably tolerates Membrane electrode unit has a bending radius of at least 5 mm.

In a special embodiment of the membrane electrode unit according to the invention have the proton conductive component of the anode layer and cathode layer and that proton conductive material of the electrolyte membrane has the same composition. On the other hand, it is also possible for the proton-conductive component of the anode layer and / or the cathode layer and / or the membrane are different.

The catalyst may be the same on the anode and cathode sides, in the preferred one The embodiment is different. In a preferred embodiment, the Catalyst carrier in the anode layer and in the cathode layer electrically conductive.

To manufacture the membrane electrode assembly, an electrolyte membrane is inserted through a suitable process coated with the catalytically active electrode material.

The electrolyte membrane can be provided with the electrode in various ways. The way and the order of how the electrically conductive material, catalyst, Electrolyte and any other additives that may be applied to the membrane are at will of the specialist. You just have to make sure that the interface Gas space / catalyst (electrode) / electrolyte is formed. In a special case, the electrically conductive material is omitted as a catalyst carrier, in this case the electrically conductive catalyst directly for the derivation of the electrons from the Membrane electrode assembly.

• A) Bereitstellung einer für die Reaktionskomponenten der Brennstoffzellenreaktion undurchlässigen, protonenleitfähigen, flexiblen Elektrolytmembran für eine Brennstoffzelle, insbesondere einer erfindungsgemäßen Elektrolytmembran, wobei die Elektrolytmembran, als Träger einen flexiblen, stoffdurchlässigen Verbundwerkstoff umfasst, der ein flächiges, mit einer Vielzahl von Öffnungen versehenes, flexibles Substrat mit einer auf und in diesem Substrat befindlichen Beschichtung aufweist, wobei das Material des Substrates ausgewählt ist aus gewebten oder ungewebten Polymerfasern und die Beschichtung eine poröse, keramische Beschichtung ist und wobei der Träger mit einem protonenleitfähigen Material durchsetzt ist, das geeignet ist, selektiv Protonen durch die Membran zu leiten,
• B) Bereitstellung jeweils eines Mittels zur Herstellung einer Anodenschicht und einer Kathodenschicht, wobei das Mittel jeweils umfasst:
  • 1. eine kondensierbare Komponente, die nach der Kondensation der Elektrodenschicht Protonenleitfähigkeit verleiht,
  • 2. einen Katalysator, der die Anodenreaktion bzw. die Kathodenreaktion katalysiert, oder eine Vorstufenverbindung des Katalysators,
  • 3. gegebenenfalls einen Katalysatorträger und
  • 4. gegebenenfalls einen Porenbildner,
• C) Aufbringen der Mittel aus Stufe (B) auf jeweils eine Seite der Elektrolytmembran aus Stufe (A) zur Bildung einer Beschichtung,
• D) Schaffung eines festen Verbundes zwischen den Beschichtungen und der Elektrolytmembran unter Ausbildung einer porösen, protonenleitfähigen Anodenschicht oder Kathodenschicht, wobei die Ausbildung der Anodenschicht und der Kathodenschicht gleichzeitig oder nacheinander erfolgen kann.

The method according to the invention for producing a membrane electrode unit according to the invention comprises the following steps:

• A) Provision of a proton-conductive, flexible electrolyte membrane which is impermeable to the reaction components of the fuel cell reaction, for a fuel cell, in particular an electrolyte membrane according to the invention, the electrolyte membrane, as a carrier, comprising a flexible, permeable composite material which has a flat, flexible substrate provided with a plurality of openings with a coating located on and in this substrate, wherein the material of the substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating and wherein the carrier is permeated with a proton-conductive material which is suitable for selectively protons to guide the membrane
• B) Provision in each case of an agent for producing an anode layer and a cathode layer, the agent in each case comprising:
  • 1. a condensable component which gives proton conductivity after the condensation of the electrode layer,
  • 2. a catalyst which catalyzes the anode reaction or the cathode reaction, or a precursor compound of the catalyst,
  • 3. optionally a catalyst support and
  • 4. if necessary, a pore former,
• C) applying the agents from stage (B) to one side of the electrolyte membrane from stage (A) to form a coating,
• D) Creation of a firm bond between the coatings and the electrolyte membrane with the formation of a porous, proton-conductive anode layer or cathode layer, it being possible for the anode layer and the cathode layer to be formed simultaneously or in succession.

The application of the agent in step (C) can, for. B. by printing, pressing, Pressing in, rolling up, knife application, spreading on, dipping, spraying or pouring on.

• 1. Herstellung eines Sols, umfassend
  eine Hydroxysilylalkylsäure des Schwefels oder Phosphors bzw. deren Salz und gegebenenfalls eine die Hydroxysilylalkylsäure des Schwefels oder Phosphors bzw. deren Salz immobilisierende hydrolysierbare Verbindung des Phosphors
  oder ein hydrolysierbares Nitrat, Oxynitrat, Chlorid, Oxychlorid, Carbonat, Alkoholat, Acetat, Acetylacetonat eines Metalls oder Halbmetalls, vorzugsweise Phosphorsäuremethylester, Diethylphosphit (DEP), Diethylethylphosphonat (DEEP), Titanpropylat, Titanethylat, Tetraethylorthosilikat (TEOS) oder Tetramethylorthosilikat (TMOS), Zirkoniumnitrat, Zirkoniumoxynitrat, Zirkoniumpropylat, Zirkoniumacetat oder Zirkoniumacetylacetonat,
• 2. Dispergieren des Katalysators und gegebenenfalls des Katalysatorträgers und Porenbildners in dem Sol aus (S1).

The agent according to step (B) for producing an anode layer or a cathode layer is preferably a suspension which is obtainable from

• 1. Preparation of a sol, comprising
  a hydroxysilylalkyl acid of sulfur or phosphorus or its salt and optionally a hydrolyzable compound of phosphorus immobilizing the hydroxysilylalkyl acid of sulfur or phosphorus or its salt
  or a hydrolyzable nitrate, oxynitrate, chloride, oxychloride, carbonate, alcoholate, acetate, acetylacetonate of a metal or semimetal, preferably methylphosphate, diethylphosphite (DEP), diethylethylphosphonate (DEEP), titanium propylate, titaniumethylate, tetraethylorthosilicate (TEOS) or tetraethyl orthosilicate (TEOS) or Zirconium nitrate, zirconium oxynitrate, zirconium propylate, zirconium acetate or zirconium acetylacetonate,
• 2. Dispersing the catalyst and optionally the catalyst support and pore former in the sol from (S1).

• 1. Hydrolyse einer hydrolysierbaren Verbindung zu einem Hydrolysat, wobei die hydrolysierbare Verbindung ausgewählt ist aus
  einer hydrolysierbaren Verbindung des Phosphors oder
  hydrolysierbaren Nitraten, Oxynitraten, Chloriden, Oxychloriden, Carbonaten, Alkoholaten, Acetaten, Acetylacetonaten eines Metalls oder Halbmetalls, vorzugsweise Aluminiumalkoholaten, Vanadium-alkoholaten, Titanpropylat, Titanethylat, Zirkoniumnitrat, Zirkoniumoxyntrat, Zirkoniumpropylat, Zirkoniumacetat oder Zirkoniumacetylacetonat, oder
  Metallsäuren des Aluminiums, Siliziums, Titans, Vanadiums, Antimons, Zinns, Bleis, Chroms, Wolframs, Molybdäns, Mangans, wobei Wolframphosphorsäure und Siliziumwolframsäure bevorzugt ist,
• 2. Peptisierung des Hydrolysats mit einer Säure zu einer Dispersion,
• 3. Vermischen der Dispersion mit einem nanokristallinen protonenleitenden Metalloxid, vorzugsweise Al₂O₃-, ZrO₂-, TiO₂- oder SiO₂-Pulver,
• 4. Dispergieren des Katalysators und gegebenenfalls des Trägers und Porenbildners.

The agent according to step (B) for producing an anode layer or a cathode layer is very particularly preferably a suspension which is obtainable by

• 1. hydrolysis of a hydrolyzable compound to a hydrolyzate, the hydrolyzable compound being selected from
  a hydrolyzable compound of phosphorus or
  hydrolyzable nitrates, oxynitrates, chlorides, oxychlorides, carbonates, alcoholates, acetates, acetylacetonates of a metal or semimetal, preferably aluminum alcoholates, vanadium alcoholates, titanium propylate, titanium ethylate, zirconium nitrate, zirconium oxyntrate, zirconium propylate, zirconium acetate or zirconium acetate
  Metal acids of aluminum, silicon, titanium, vanadium, antimony, tin, lead, chromium, tungsten, molybdenum, manganese, with tungsten phosphoric acid and silicon tungsten acid being preferred,
• 2. peptizing the hydrolyzate with an acid to form a dispersion,
• 3. Mixing the dispersion with a nanocrystalline proton-conducting metal oxide, preferably Al ₂ O ₃ , ZrO ₂ , TiO ₂ or SiO ₂ powder,
• 4. Dispersing the catalyst and optionally the carrier and pore former.

It can be advantageous if the means for producing an anode layer and a Cathode layer can be printed in step (C) and to create a firm bond between the coatings and the electrolyte membrane to form a porous, proton conductive anode layer or cathode layer in step (D) to a temperature from 20 to 300 ° C, preferably 50 to 200 ° C, most preferably 80 to 150 ° C is heated.

• 1. Aufbringen des Mittels zur Herstellung einer Anodenschicht oder Kathodenschicht auf eine Stützmembran, vorzugsweise aus Polytetrafluorethylen,
• 2. Antrocknen der unter (M1) erhaltenen Beschichtung,
• 3. Aufpressen der angetrockneten Beschichtung auf die Elektrolytmembran bei einer Temperatur von 20 bis 300°C, vorzugsweise 50 bis 200°C, ganz besonders bevorzugt 80 bis 150°C,
• 4. Entfernen der Stützmembran insbesondere durch mechanisches Ablösen, chemisches Auflösen, oder Pyrolisieren oder
• 5. Aufbringen des Mittels zur Herstellung einer Anodenschicht oder Kathodenschicht auf eine Stützmembran, vorzugsweise aus Kohlepapier oder einem elektrisch leitfähigen Vlies oder Gewebe,
• 6. Antrocknen der unter (N1) erhaltenen Beschichtung zur Herstellung einer beschichteten Stützmembran,
• 7. Aufpressen der beschichteten Stützmembran auf die Elektrolytmembran bei einer Temperatur von Raumtemperatur bis 300°C, vorzugsweise 50 bis 200°C, ganz besonders bevorzugt 80 bis 150°C umfassen.

The method according to the invention can also include the steps:

• 1. Applying the agent for producing an anode layer or cathode layer to a support membrane, preferably made of polytetrafluoroethylene,
• 2. drying of the coating obtained under (M1),
• 3. pressing the dried coating onto the electrolyte membrane at a temperature of 20 to 300 ° C., preferably 50 to 200 ° C., very particularly preferably 80 to 150 ° C.,
• 4. Removing the support membrane, in particular by mechanical detachment, chemical dissolving, or pyrolizing or
• 5. applying the agent for producing an anode layer or cathode layer to a support membrane, preferably made of carbon paper or an electrically conductive fleece or fabric,
• 6. drying of the coating obtained under (N1) to produce a coated support membrane,
• 7. Press the coated support membrane onto the electrolyte membrane at a temperature of from room temperature to 300 ° C., preferably 50 to 200 ° C., very particularly preferably 80 to 150 ° C.

• a) ein Katalysatormetallsalz, vorzugsweise Hexachloroplatinsäure umfasst
• b) nach dem Aufbringen der Mittel durch Schritt (C) das Katalysatormetallsalz zu einem Katalysator, der die Anodenreaktion oder die Kathodenreaktion katalysiert, reduziert wird,
• c) in Schritt (D) eine offenporige Gasdiffusionselektrode, vorzugsweise ein offenporiges Kohlepapier, auf den Katalysator aufgepresst oder mit einem elektrisch leitfähigen Klebstoff auf den Katalysator geklebt wird.

It can be advantageous if in step (B) the agent is provided in each case when providing an agent for producing an anode layer and a cathode layer

• a) comprises a catalyst metal salt, preferably hexachloroplatinic acid
• b) after the application of the agents by step (C), the catalyst metal salt is reduced to a catalyst which catalyzes the anode reaction or the cathode reaction,
• c) in step (D), an open-pore gas diffusion electrode, preferably an open-pore carbon paper, is pressed onto the catalyst or glued to the catalyst with an electrically conductive adhesive.

The inventive method can be carried out so that the application of the Repeatedly carried out by means of producing an anode layer or cathode layer and optionally a drying step, preferably at an elevated temperature in a range from 50 to 200 ° C, preferably from 60 to 150 ° C and very particularly preferably at an elevated temperature of 80 to 120 ° C between the repeated The application is carried out.

It can be advantageous if the agent is used to produce an anode layer or cathode layer on a flexible electrolyte membrane unrolled from a first roll or flexible support membrane. In particular, it can be advantageous if the Application of the agent for producing an anode layer or cathode layer done continuously. It can be particularly advantageous if the application of the agent for Production of an anode layer or cathode layer on a heated electrolyte or Support membrane is made.

To create a firm bond between the coatings and the The composite electrolyte membrane is preferably, at a temperature of 20 to 300 ° C, preferably 50 to 200 ° C, most preferably 80 to 150 ° C heated. The warming can be done using heated air, hot air, infrared radiation or microwave radiation.

In a special embodiment, the membrane electrode assembly is manufactured on the electrolyte membrane according to the invention the catalytically active (Gas diffusion) electrodes built. For this, an ink from a soot Catalyst powder and at least one proton conductive material. The ink But can also contain other additives that have the properties of Improve membrane electrode assembly. The soot can also be caused by other, electrically conductive Materials (such as metal powder, metal oxide powder, carbon, coal) are replaced. In In a special embodiment, a metal or Semimetal oxide powder (such as Aerosil) is used. This ink is then, for example by screen printing, knife coating, spraying on, rolling on or by dipping on the membrane applied.

The ink can contain all proton-conducting materials that are also used to infiltrate the carrier. The ink can thus contain an acid or its salt, which is immobilized by a chemical reaction in the course of a solidification process after the ink has been applied to the membrane. So this acid can e.g. B. simple Bronsted acid, such as sulfuric or phosphoric acid, or a silylsulfonic or silylphosphonic acid. As materials that support the solidification of the acid, for. B. Al ₂ O ₃ , SiO ₂ , ZrO ₂ , TiO ₂ are used, which are also added via molecular precursors of the ink.

In contrast to the proton conductive material of the electrolyte membrane, which for the Reaction components of the fuel cell reaction must be impermeable, both Both cathode and anode have a large porosity so that the reaction gases, such as Hydrogen and oxygen, without inhibiting mass transfer to the catalyst interface and electrolyte can be introduced. This porosity can be measured, for example Use of metal oxide particles with a suitable particle size and of organic pore formers in the ink or by a suitable solvent content in the Affect ink.

• 1. eine kondensierbare Komponente, die nach der Kondensation einer Anodenschicht oder einer Kathodenschicht einer Membranelektrodeneinheit einer Brennstoffzelle Protonenleitfähigkeit verleiht,
• 2. einen Katalysator, der die Anodenreaktion oder die Kathodenreaktion in einer Brennstoffzelle katalysiert, oder eine Vorläuferverbindung des Katalysators,
• 3. gegebenenfalls einen Katalysatorträger
• 4. gegebenenfalls einen Porenbildner und
• 5. gegebenenfalls Additive zur Verbesserung von Schaumverhalten, Viskosität und Haftung.

A medium comprising the following components can be used as the special ink:

• 1. a condensable component which, after the condensation of an anode layer or a cathode layer of a membrane electrode assembly, imparts proton conductivity to a fuel cell,
• 2. a catalyst which catalyzes the anode reaction or the cathode reaction in a fuel cell, or a precursor compound of the catalyst,
• 3. optionally a catalyst support
• 4. if necessary, a pore former and
• 5. optionally additives to improve foam behavior, viscosity and adhesion.

• A) hydrolysierbaren Verbindung des Phosphors und/oder
  hydrolysierbaren Nitraten, Oxynitraten, Chloriden, Oxychloriden, Carbonaten, Alkoholaten, Acetaten, Acetylacetonaten eines Metalls oder Halbmetalls, vorzugsweise Aluminiumalkoholaten, Vanadium-alkoholaten, Titanpropylat, Titanethylat, Zirkoniumnitrat, Zirkoniumoxynitrat, Zirkoniumpropylat, Zirkoniumacetat oder Zirkoniumacetylacetonat, und/oder
  Metallsäuren des Aluminiums, Titans, Vanadiums, Antimons, Zinns, Bleis, Chroms, Wolframs, Molybdäns, Mangans, wobei Wolframphosphorsäure und Siliziumwolframsäure bevorzugt sind, und/oder
• B) einer immobilisierbaren Hydroxysilylalkylsäure von Schwefel oder Phosphor oder ein Salz davon und in einer besonders bevorzugten Ausführungsform zusätzlich eine die Hydroxysilylalkylsäure des Schwefels oder Phosphors bzw. deren Salz immobilisierende hydrolysierbare Verbindung des Phosphors oder ein hydrolisierbares Nitrat, Oxynitrat, Chlorid, Oxychlorid, Carbonat, Alkoholat, Acetat, Acetylacetonat eines Metalls oder Halbmetalls, vorzugsweise Phosphorsäuremethylester, Diethylphosphit (DEP), Diethylethylphosphonat (DEEP) Titanpropylat, Titanethylat, Tetraethylorthosilikat (TEOS) oder Tetramethylorthosilikat (TMOS), Zirkoniumnitrat, Zirkoniumoxynitrat, Zirkoniumpropylat, Zirkoniumacetat oder Zirkoniumacetylacetonat.

The condensable component which imparts proton conductivity to the anode layer or the cathode layer after the condensation is preferably selected from

• A) hydrolyzable compound of phosphorus and / or
  hydrolyzable nitrates, oxynitrates, chlorides, oxychlorides, carbonates, alcoholates, acetates, acetylacetonates of a metal or semimetal, preferably aluminum alcoholates, vanadium alcoholates, titanium propylate, titanium ethylate, zirconium nitrate, zirconium oxynitrate, zirconium propylate, zirconium acetate or zirconium acetate or zirconium acetate
  Metal acids of aluminum, titanium, vanadium, antimony, tin, lead, chromium, tungsten, molybdenum, manganese, with tungsten phosphoric acid and silicon tungsten acid being preferred, and / or
• B) an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof and, in a particularly preferred embodiment, additionally a hydrolyzable compound of phosphorus immobilizing the hydroxysilylalkyl acid of sulfur or phosphorus or its salt or a hydrolyzable nitrate, oxynitrate, chloride, oxychloride, carbonate, alcoholate , Acetate, acetylacetonate of a metal or semimetal, preferably methyl phosphate, diethylphosphite (DEP), diethylethylphosphonate (DEEP) titanium propylate, titanium ethylate, tetraethylorthosilicate (TEOS) or tetramethylorthosilicate (TMOS), zirconium nitrate, zirconium oxynium acetate, zirconium oxonium acetate.

However, the ink can also be used to increase the proton conductivity, nanoscale oxides such. B. of aluminum, titanium, zirconium or silicon, or zirconium or titanium phosphates contain or -phosphonates.

The catalyst or the precursor compound of the catalyst preferably comprises platinum, Palladium and / or ruthenium or an alloy containing one or more of these metals contains.

The pore former, which is optionally contained in the ink, can be an organic and / or be inorganic substance, which is preferred at a temperature between 50 and 300 ° C. decomposed between 100 and 200 ° C. In particular, the inorganic pore former Be ammonium carbonate or ammonium bicarbonate.

The catalyst support, which is optionally contained in the ink, is preferably electrical conductive and preferably comprises carbon black, metal powder, metal oxide powder, carbon or Coal.

In a further embodiment, a prefabricated gas distributor, the Gas diffusion electrode consisting of an electrically conductive material (e.g. a porous Carbon fleece), catalyst and electrolyte contains, are applied directly to the membrane. In the simplest case, the gas distributor and membrane are fixed by a Pressing process. For this it is necessary that the membrane or gas distributor at the Press temperature have thermoplastic properties. The gas distributor can also be fixed on the membrane by an adhesive. This adhesive must be ion-conductive Have properties and can in principle from the material classes already mentioned above consist. For example, a metal oxide sol can be used as the adhesive additionally contains a hydroxysilyl acid. Finally, the gas distributor can also "in situ" applied in the final stage of membrane or gas diffusion electrode manufacture become. At this stage, the proton-conducting material is in the gas distributor or in the membrane not yet cured and can be used as an adhesive. The gluing process takes place in both Precipitation by gelation of the sol followed by drying / solidification.

However, it is also possible to deposit the catalyst directly on the membrane and with a open-pore gas diffusion electrode (such as an open-pore carbon paper). For this purpose, e.g. B. applied a metal salt or an acid to the surface and in one second step to be reduced to metal. For example, platinum can be Apply hexachloroplatinic acid and reduce to metal. In the last step the Lead electrode by a pressing process or by an electrically conductive adhesive fixed. The solution containing the metal precursor can also be a compound contain, which is already proton conductive or at least at the end of the manufacturing process is ionic. Suitable materials come again from those already mentioned above proton-conducting substances in question.

In this way, a membrane electrode unit is obtained which, in a fuel cell, especially in a direct methanol fuel cell or a reformate fuel cell, can be used.

The electrolyte membranes according to the invention can, for. B. in a fuel cell, especially in a direct methanol fuel cell or a reformate fuel cell be used. In particular, the electrolyte membrane according to the invention can Manufacture of a membrane electrode assembly, a fuel cell, or one Fuel cell stacks are used.

The electrolyte membrane according to the invention and the one according to the invention Membrane electrode unit can be used in particular for producing a fuel cell or a Fuel cell stacks are used, the fuel cell in particular one Direct methanol fuel cell or a reformate fuel cell is in a vehicle is used.

Accordingly, there are also fuel cells with an electrolyte membrane according to the invention and / or a membrane electrode unit according to the invention the subject of the present Invention and thus also mobile or stationary system with a membrane electrode unit, a fuel cell or a fuel cell stack containing an inventive Electrolyte membrane or a membrane electrode assembly according to the invention. Preferably are the mobile or stationary systems vehicles or home energy systems.

The invention is explained in more detail below with the aid of examples.

Examples A-D Production of polymer-supported microfiltration membranes as carrier Example A Production of an MF membrane S100PET

15 g of a 5% strength by weight aqueous HCl solution, 10 g, are first added to 160 g of ethanol Tetraethoxysilane, 2.5 g methyltriethoxysilane and 7.5 g Dynasilane GLYMO (manufacturer of all Dynasilane: Degussa AG). In this sol, which initially continues for two hours was stirred, 280 g of the aluminum oxide AlCoA CT3000 are then suspended. This Slurry is homogenized for at least another 24 h using a magnetic stirrer, the Mixing vessel must be covered so that there is no loss of solvent.

A PET fleece with a thickness of approx. 30 µm and a weight per unit area of approx. 20 g / m ² is coated with the above slip in a continuous rolling process (belt speed approx. 8 m / h, T = 200 ° C). In this rolling process, the slip is rolled onto the fleece with a roller that moves in the opposite direction to the belt direction (direction of movement of the fleece). The fleece then runs through an oven at the specified temperature. The same method or arrangement is used in the subsequent experiments. At the end, a microfiltration membrane with an average pore size of approximately 80 to 100 nm is obtained.

Example B Production of an MF membrane S240PO

15 g of a 5% strength by weight aqueous HCl solution, 10 g, are first added to 160 g of ethanol Tetraethoxysilane, 2.5 g of methyltriothoxysilane and 7.5 g of Dynasilane GLYMO. In this Sol, which was initially stirred for two hours, then becomes 150 g of the aluminum oxide AlCoA CT1200 SG suspended. This slip is used with a for at least another 24 h Homogenized magnetic stirrer, the mixing vessel must be covered so that it does not close there is a loss of solvent.

A PO fleece (FS 2202-03, Freudenberg company) with a thickness of about 30 µm is thus in a continuous rolling process (belt speed approx. 8 m / h, T = 110 ° C) Coated above slip. At the end, a microfiltration membrane with a average pore size of approx. 450 nm.

Example C Production of an MF membrane S450PAN

15 g of an S% by weight aqueous HCl solution, 10 g, are first added to 160 g of ethanol Tetraethoxysilane, 2.5 g methyltriethoxysilane and 7.5 g Dynasilan VTEO added. In this Sol, which was initially stirred for two hours, is then 140 g of each Aluminum oxides Martoxid MZS-1 and Martoxid MZS-3 (Martoxid: manufacturer Martinswerke) suspended. This slip is kept for at least another 24 hours with a magnetic stirrer homogenized, whereby the mixing vessel must be covered so that it does not become one Solvent loss is coming.

A PAN fleece (Viledon 1773, company Freudenberg) with a thickness of approximately 100 μm and a weight per unit area of 22 g / m ² is produced in a continuous rolling process (belt speed approx. 8 m / h, T = 250 ° C.) with the above slip coated. At the end, a microfiltration membrane with an average pore size of approximately 450 nm is obtained, which has a very good adhesive strength.

Example D Production of an MF membrane Z450PAN

10 g of a 70 wt .-% solution of zirconium propylate in propanol are in 340 g Dissolved propanol. 0.72 g of water and 0.04 g of water are added to this solution with vigorous stirring concentrated hydrochloric acid. This sol is further stirred for five hours.

A PAN fleece (Viledon 1773, company Freudenberg) with a thickness of about 100 µm and a basis weight of 22 g / m ² is thus in a continuous rolling process (belt speed about 8 m / h, T = 150 ° C) with this Sol coated.

In a mixture of 150 g of deionized water and 22.5 g of ethanol, 1.4 g Zirconium acetylacetonate dissolved. In this solution, 140 g MZS-1 and MZS-3 suspended and the slurry stirred for at least 24 h. About 1 hour before coating 75 g of a commercial 30% by weight zirconium nitrate sol (MEL Chemicals) added to the slip.

The pre-coated PAN fleece is then in a second continuous Roll-on process (belt speed approx. 8 m / h, T = 250 ° C) with this slip coated. At the end, a microfiltration membrane with an average pore size is obtained 450 nm, which has a very good adhesive strength and is very resistant even in very alkaline media (pH> 10).

example 1 Manufacture of cPEMs Example 1a Production of a cPEM based on Trihydroxisilylpropylsulfonsäure / Levasil®

10 g of a 30 wt .-% aqueous solution of trihydroxysilylpropylsulfonic acid are in 50 g of Levasil 200® (Bayer AG), a suspension of precipitated silica, dissolved. A according to Example A (S100PET) manufactured microfiltration membrane is used as a composite used and in a continuous rolling process (belt speed: 10 m / h) with coated this solution and dried briefly at 150 ° C.

Example 1b Production of a cPEM based on Trihydroxisilylpropylsulfonsäure / TEOS

10 g of a 30 wt .-%, aqueous solution of trihydroxysilylpropylsulfonic acid were in 40g ethanol dissolved. First add a few drops of HCl to this solution and then add vigorous stirring 30 ml tetraethoxysilane (TEOS, Dynasilan A®, Degussa AG) and stir the Solution another 24 h. The solution containing trihydroxysilylpropylsulfonic acid is then in applied to a composite material according to example B (S240PO) by a doctor blade process and the membrane dried at 100 ° C for 1 h.

Example 1c Production of a cPEM based on a mineral acid

8 g of a 20% by weight aqueous solution of precipitated silica (Levasil®, Bayer AG)) are mixed with 1 g of diethyl phosphite, 1 g of H ₂ SO ₄ and 1 g of ethanol. After 1 hour, 5% by weight of Aerosil® 200 (Degussa AG) are added to the sol and the suspension is homogenized for a further 30 minutes. A composite material is coated in a continuous rolling process (belt speed 8 m / h, T = 130 ° C.) according to example C (S450PAN). This membrane has an LF of 30 mS / cm at 35% relative humidity r. F. and 85 mS / cm at 85% r. Q. Due to the very good flexibility, it can be installed very well in the fuel cell and shows good performance.

Example 1d Production of a cPEM based on a mineral acid with Double coating

For better infiltration, the membrane from Example 1c is again coated with the Aerosil®-free one Sol from 1c coated on the back under otherwise identical test conditions.

This membrane has an LF of 50 mS / cm at 35% relative humidity r. F. and 140 mS / cm at 85% r. F. Because of the very good flexibility, it can be used very well in the fuel cell install and shows a good performance.

Example 1e Production of a cPEM based on a mineral acid with Double coating

200 g of a 20% by weight aqueous solution of precipitated silica (Levasil®) are mixed with 25 g of diethyl phosphite, 25 g of H ₂ SO ₄ and 38 g of ethanol. After stirring for two hours using a magnetic stirrer, an MF membrane (S450 PAN according to Example C) is infiltrated with this sol using a roller application from the front and dried at 120 ° C. The belt speed is about 10 m / h. For better infiltration, this membrane is coated on the back in a second step with the same sol under otherwise identical conditions. This membrane has a conductivity of 95 mS / cm at 85% r. F. and 40 mS / cm at 35% r. F.

Example 2 Coating a cPEM with diffusion barriers Example 2a Coating with pure Nafion

A membrane according to Example 1a is in a continuous rolling process with a commercial, aqueous / alcoholic 5% by weight Nafion® solution (company Aldrich) coated and dried at 100 ° C. The LF of the overall membrane decreases somewhat, that However, membrane is suitable for the DMFC.

Example 2b Coating with Nafion / TEOS

To 10 ml of a commercial, aqueous / alcoholic 5% by weight Nafion® solution (Aldrich company) 10 ml Dynasil A® are added with vigorous stirring and so long stirred until there is only a clear phase. A membrane according to Example 1c is in a continuous rolling process coated with this solution and at 100 ° C dried.

Example 2c Coating with Nafion / TEOS / ethanol

To 90 ml of a commercial, aqueous / alcoholic 5% by weight Nafion® solution (Aldrich company) 90 ml of Dynasil A® are dissolved in 90 ml of ethanol with vigorous stirring added and stirred for a short time. A membrane according to Example 1e is in a continuous rolling process (belt speed of 8 m / h, T = 120 ° C) with coated on both sides of this solution. Compared to the membrane without a diffusion barrier the conductivity decreases somewhat to 80 mS / cm at 85% r. F. and 30 mS / cm at 35% r. F.

Example 2d Coating with trihydroxysilylpropylsulfonic acid / Levasil

10 g of an aqueous 30% by weight trihydroxysilylpropylsulfonic acid solution are in 50 g Levasil200® solved. A membrane according to Example 1d is in a continuous Roll-up process coated with this solution and dried at 100 ° C.

Example 2e Coating with trihydrogisilylpropylsulfonic acid / TEOS

10 g of an aqueous 30% by weight trihydroxysilylpropylsulfonic acid solution are in 40 g Ethanol dissolved. First add a few drops of HCl to this solution and then add vigorous stirring 30 ml Dynasilan A ® and the solution is stirred for a further 24 h. A membrane according to Example 1e, is in a continuous rolling process with this solution coated and dried at 100 ° C.

Example 2f Coated with zirconium phosphate

A membrane produced according to Example 1c is first coated with a thin layer of zirconium propylate using a doctor blade. The alcoholate is hydrolyzed in the presence of air humidity. The freshly precipitated zirconium hydroxide / oxide is then reacted with H ₃ PO ₄ and the membrane is briefly dried at 200 ° C. in order to solidify the zirconium phosphate formed. This thin layer is then insoluble in water and prevents the electrolyte from bleeding out.

Example 3 Production of an anode ink

10 ml of anhydrous trihydroxysilylpropylsulfonic acid, 60 ml of ethanol and 5 ml of water are mixed by stirring. 40 ml of TEOS (tetraethyl orthosilicate) are slowly added dropwise to this mixture with stirring. The catalyst known from DE 197 21 437 and DE 198 16 622 is dispersed in this sol so that a degree of catalyst coverage of approximately 0.2 mg / cm ² or 0.5 mg / cm ² can be achieved in the electrode.

Example 4 Production of an anode ink

100 ml of titanium isopropylate are dropped into 1200 ml of water with vigorous stirring. The resulting precipitate is aged for 1 h and then concentrated with 8.5 ml. HNO _{3 was} added and peptized at the boiling point for 24 h. 50 g of tungsten phosphoric acid are dissolved in 50 ml of this sol and the catalyst is then dispersed therein as described in Example 3.

Example 5 Production of an anode ink

20 g of aluminum alcoholate and 17 g of vanadium alcoholate are hydrolyzed with 20 g of water and the resulting precipitate is peptized with 120 g of nitric acid (25%). This Solution is stirred until clear and after adding 40 g of titanium dioxide Degussa (P25) is stirred until all agglomerates have dissolved. After hiring 6, the catalyst is dispersed therein as described in Example 3.

Example 6 Production of a cathode ink

10 ml of anhydrous trihydroxysilylpropylsulfonic acid, 60 ml of ethanol and 5 ml of water are mixed by stirring. 20 ml of TEOS (tetraethyl orthosilicate) and 20 ml of methyltriethoxysilane are slowly added dropwise to this mixture with stirring. The catalyst used in DE 196 11 510 or the one used in DE 198 12 592 is dispersed in this sol, so that a Pt coverage level of about 0.15 mg / cm ² or 0.25 mg / cm ² can be achieved in the electrode ,

Example 7 Production of a cathode ink

20 g of methyltriethoxysilane, 20 g of tetraethyl orthosilicate and 10 g of aluminum trichloride are added 50 g of water hydrolyzed in 200 g of ethanol. 190 g of zeolite USY (CBV 600 from Zeolyst). The mixture is stirred until all agglomerates have dissolved and then the catalyst is dispersed therein as described in Example 6.

Example 8 Manufacture of a membrane electrode assembly Example 8a Manufacture of a membrane electrode assembly

A membrane according to Example 2e is screen printed with the ink according to Example 3 first printed on the front. This page serves in the later Membrane electrode unit as an anode. The printed membrane is at a temperature of 150 ° C dried. In addition to the escape of the solvent, there is also a Immobilization of the silylpropylsulfonic acid.

In the second step, the membrane on the back, which will later serve as the cathode, is attached printed on the ink from Example 6. Even now the printed membrane is in turn at one Dried temperature of 150 ° C whereby the solvent escapes and at the same time it becomes a Immobilization of the silylpropylsulfonic acid comes. Since the cathode is hydrophobic, the Operation of the membrane electrode assembly in the fuel cell makes the product water easily escape. This membrane electrode assembly can be used in a direct methanol fuel cell or a reformate fuel cell can be installed.

Example 8b Manufacture of a membrane electrode assembly

To produce the electrodes, both the anode ink according to Example 4 and Cathode ink according to Example 7 each applied to an electrically conductive carbon paper. The solvent is removed by heat treatment at a temperature of 150 ° C and immobilized the proton-conductive component. These two gas diffusion electrodes become a with a proton conductive membrane according to Example 2e Compressed membrane electrode unit, which can then be installed in the fuel cell.

Example 9 Manufacture of a fuel cell

To manufacture the MEA, the electrodes are first manufactured. For this, a Ceramic fleece coated with a soot / platinum mixture (40%). These electrodes are on the electrolyte membrane is pressed according to Example 2c. The pressure is applied via a graphitic gas distribution plate, which also serves for electrical contacting. On the Pure hydrogen is added to the anode side and pure oxygen is added to the cathode side Commitment. Both gases are moistened via water vapor saturators (so-called "bubblers").

Comparative example

A fuel cell was made as described in Example 9, except that as proton conductive membrane a conventional Nafion®117 membrane was used. It it was found that the proton conductivity when using a Nafion membrane a relative humidity of less than 100% and the Surface resistance increased sharply so that the fuel cell can no longer be operated could. The membrane according to the invention, however, could also be used in a relative Air humidity operated, the anode side at about a maximum of 50% and the cathode side was at most 0 to 50% without the function of the fuel cell essential was affected.

Claims (73)

1. Proton-conductive, flexible electrolyte membrane for a fuel cell, impermeable to the reaction components of a fuel cell reaction, comprising a flexible, permeable composite material as a carrier, which has a flat, provided with a plurality of openings, flexible substrate with a coating on and in this substrate, wherein the material of the substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating, characterized in that the carrier is interspersed with a proton-conductive material which is suitable for selectively guiding protons through the membrane. 2. Electrolyte membrane according to claim 1, characterized in that the proton conductive material a) an immobilized hydroxysilylalkyl acid of sulfur or phosphorus and optionally an oxide of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former, and / or b) a Bronsted acid and an oxide of aluminum, silicon, titanium, zirconium, and / or phosphorus as a network former, and / or c) zirconium and / or titanium phosphates, phosphonates and / or sulfoaryl phosphonates and optionally an oxide of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former includes. 3. Proton-conductive, flexible electrolyte membrane for a fuel cell, impermeable to the reaction components of a fuel cell reaction, obtainable from a) infiltration of a carrier based on a permeable composite material, which has a flat, with a plurality of openings provided flexible substrate with a coating on and in this substrate, the material of the substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating with 1. a mixture containing an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof; or 2. a mixture containing a Bronsted acid and / or an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof and a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus, or 3. a mixture containing zirconium and / or titanium phosphates, phosphonates and / or sulfoaryl phosphonates and, if appropriate, a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former and b) Solidification of the mixture infiltrating the carrier in order to create a material which penetrates the carrier and is suitable for selectively guiding protons through the membrane. 4. electrolyte membrane according to one of claims 2 or 3, characterized, that the Bronsted acid sulfuric acid, phosphoric acid, perchloric acid, nitric acid, Hydrochloric acid, sulfurous acid, phosphorous acid and esters thereof and / or comprises a monomeric or polymeric organic acid. 5. Electrolyte membrane according to one of claims 2 to 4, characterized in that the hydroxysilylalkyl acid of sulfur or phosphorus is an organosilicon compound of the general formulas

[{(RO) _y (R ² ) _z } _a Si {R ¹ -SO ₃ ^- } _a ] _x M ^{x +} (I)

or

[(RO) _y (R ² ) _z Si {R ¹ -O _b -P (O _c R ³ ) O ₂ ^- } _a ] _x M ^{x +} (II)

, where R ^{1 is} a linear or branched alkyl or alkylene group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms or a unit of the general formulas


or


stands,
where n, m each represents an integer from 0 to 6,
M represents H, NH ₄ or a metal,
x = 1 to 4,
y = 1 to 3, z = 0 to 2 and a = 1 to 3, with the proviso that
y + z = 4 - a,
b, c = 0 or 1,
R, R ^{2 are the} same or different and stand for methyl, ethyl, propyl, butyl or H and
R ^{3 represents} M or a methyl, ethyl, propyl or butyl radical. 6. electrolyte membrane according to claim 5, characterized, that the hydroxysilylalkyl acid of sulfur or phosphorus Trihydroxysilylpropylsulfonic acid, trihydroxysilylpropylmethylphosphonic acid or Dihydroxysilylpropylsulfonedioic acid. 7. electrolyte membrane according to one of claims 2 to 6, characterized, that the hydroxysilylalkyl acid of sulfur or phosphorus is hydrolyzed with a Compound of phosphorus or a hydrolyzed nitrate, oxynitrate, chloride, Oxychloride, carbonate, alcoholate, acetate, acetylacetonate of a metal or semimetal or a hydrolyzed compound obtained from diethyl phosphite (DEP), Diethyl ethyl phosphonate (DEEP), titanium propylate, titanium ethylate, tetraethyl orthosilicate (TEOS) or tetramethyl orthosilicate (TMOS), zirconium nitrate, zirconium oxynitrate, Zirconium propylate, zirconium acetate, zirconium acetylacetonate, Phosphoric acid methyl ester or immobilized with precipitated silica. 8. electrolyte membrane according to one of claims 1 to 7, characterized, that the volume ratio of proton conductive material to carrier is at least 30 70 is. 9. Electrolyte membrane according to one of claims 1 to 8, characterized in that the proton-conductive material comprises ceramic particles of at least one oxide selected from the series Al ₂ O ₃ , SiO ₂ , ZrO ₂ or TiO ₂ . 10. electrolyte membrane according to claim 9, characterized, that the ceramic particles have one or more particle size fractions with medium Have particle sizes in the range from 10 to 100 nm and / or from 100 to 1000 nm. 11. Electrolyte membrane according to one of claims 1 to 10, characterized in that 3 the proton conductive material has proton conductive substances selected from the titanium phosphates, titanium phosphonates, zirconium phosphates, zirconium phosphonates, iso- and heteropolyacids, preferably tungsten phosphoric acid or silicon tungsten acid, or nanocrystalline metal oxides, wherein Al ₂ O ₃ , ZrO ₂ , TiO ₂ or SiO ₂ powder are preferred. 12. Electrolyte membrane according to one of claims 1 to 11, characterized, that the composite woven and / or non-woven polymer fibers as the substrate having. 13. Electrolyte membrane according to one of claims 1 to 12, characterized, that the composite fabric, knitted fabrics, felts and / or nonwovens made of polymer fibers has as a substrate. 14. electrolyte membrane according to claim 13, characterized, that the substrate of the composite material is a nonwoven made of polymer fibers. 15. electrolyte membrane according to one of claims 1 to 14, characterized, that the substrate polymer fibers, of polymers selected from polyacrylonitrile (PAN), Polyamide, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyolefin, Has polyimide, polyethylene terephthalate or mixtures thereof. 16. electrolyte membrane according to at least one of claims 1 to 15, characterized, that the composite material is a ceramic coating of oxides, carbides or Has nitrides of the elements Ti, Si, Zr or Al. 17. electrolyte membrane according to claim 16, characterized, that the composite is based on a substrate having polymer fibers and / or in which at least one inorganic component is present by solidifying a suspension of an inorganic component and a sol was obtained. 18. Electrolyte membrane according to one of claims 1 to 17, characterized, that the substrate has a thickness in the range from 10 to 150 μm, preferably 10 to 80 μm, very particularly preferably has 10 to 50 microns. 19. Electrolyte membrane according to one of claims 1 to 18, characterized, that they are up to a temperature of at least 80 ° C, preferably to at least 100 ° C, and very particularly preferably up to at least 120 ° C, is stable. 20. Electrolyte membrane according to one of claims 1 to 19, characterized, that they have a bending radius down to 5000 m, preferably down to 50 cm and very particularly preferably tolerated down to 2 mm. 21. Electrolyte membrane according to one of claims 1 to 20, characterized, that they are at room temperature and at a relative humidity of up to 80%, and preferably of at most 50%, a conductivity of at least 5 mS / cm, preferably at least 20 mS / cm and very particularly preferably at least 50 mS / cm having. 22. Electrolyte membrane according to one of claims 1 to 21, characterized, that the electrolyte membrane has an outer proton conductive on at least one side Has coating that is insoluble in water and methanol. 23. electrolyte membrane according to claim 22, characterized, that the electrolyte membrane has an outer proton conductive on both sides Has coating that is insoluble in water and methanol. 24. electrolyte membrane according to one of claims 22 or 23, characterized, that the polymeric proton conductor, which is insoluble in water and methanol, selected from Nafion®, sulfonated or phosphonated polyphenyl sulfones, Polyimides, polyoxazoles, polytriazoles, polybenzimidazoles, polyether ether ketones (PEEK), polyether ketones (PEK), or inorganic proton conductors, selected from Sulfonic or phosphonic acids, or their salts, Zr or Ti phosphates, phosphonates or Sulfoarylphosphonates or mixtures of organic and inorganic Has proton conductors. 25. A method for producing an electrolyte membrane according to one of claims 1 to 24, characterized in that the method comprises the following steps: a) infiltration of a carrier based on a permeable composite material, which has a flat, with a plurality of openings provided flexible substrate with a coating on and in this substrate, the material of the substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating with 1. a mixture containing an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof; or 2. a mixture containing a Bronsted acid and / or an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof and a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus, or 3. a mixture containing zirconium and / or titanium phosphates, phosphonates and / or sulfoaryl phosphonates and, if appropriate, a sol which comprises a precursor for oxides of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former and b) solidification of the mixture infiltrating the carrier in order to create a proton conductive material which penetrates the carrier and is suitable for selectively guiding protons through the membrane. 26. The method of claim 25, wherein the sol is obtainable by 1. hydrolysis of a hydrolyzable compound, preferably in a mixture of water and alcohol, to give a hydrolyzate, the hydrolyzable compound being selected from hydrolyzable alcoholates, acetates, acetylacetonates, nitrates, oxynitrates, chlorides, oxychlorides, carbonates, of aluminum, silicon, titanium , Zirconium, and / or phosphorus or esters, preferably methyl esters, ethyl esters and / or propyl esters of phosphoric acid or phosphorous acid, 2. Peptization of the hydrolyzate to a sol. 27. The method according to claim 25 or 26, characterized in that the mixture further proton-conducting substances, preferably titanium phosphates, titanium phosphonates, zirconium phosphates, zirconium phosphonates, iso- and heteropoly acids, preferably tungsten phosphoric acid or silicon tungstic acid, nanocrystalline metal oxides, wherein Al ₂ O ₃ -, ZrO ₂ -, TiO ₂ or SiO ₂ powder are preferred. 28. The method according to any one of claims 25 to 27, wherein the infiltration by printing, Pressing on, pressing in, rolling up, knife application, spreading on, dipping, spraying or The mixture is poured onto the permeable carrier. 29. The method according to any one of claims 25 to 28, wherein the infiltration with the mixture is carried out repeatedly and optionally a drying step, preferably at an elevated temperature in a range of 50 to 200 ° C, between the repeated infiltration occurs. 30. The method according to any one of claims 25 to 29, wherein the infiltration of the permeable carrier takes place continuously. 31. The method according to any one of claims 25 to 30, wherein the solidification by heating to a temperature of 20 to 300 ° C, preferably 50 to 200 ° C, very particularly preferably 80 to 150 ° C. 32. The method according to claim 30 or 31, wherein the heating by heated air, Hot air, infrared radiation or microwave radiation takes place. 33. Flexible membrane electrode assembly for a fuel cell, with an electrical conductive anode and cathode layers, each on opposite sides one impermeable to the reaction components of the fuel cell reaction, proton conductive, flexible electrolyte membrane for a fuel cell, in particular according to one of claims 1 to 24, are provided, wherein the electrolyte membrane comprises flexible, permeable composite material as a carrier, which has a flat, with a plurality of openings provided, flexible substrate with one on and in this Has coating located substrate, the material of the substrate is selected from woven or non-woven polymer fibers and the coating one is porous, ceramic coating, and wherein the carrier with a proton conductive Is penetrated material that is capable of selectively guiding protons through the membrane, and wherein the anode layer and the cathode layer are porous and one each Catalyst for the anode and cathode reaction, a proton conductive component and optionally include a catalyst support. 34. Membrane electrode unit according to claim 33, wherein the proton-conductive component of the anode and / or cathode layer and / or the electrolyte membrane each comprises a) an immobilized hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof and optionally an oxide of aluminum, silicon, titanium, zirconium and / or phosphorus, and / or b) a Bronsted acid and an oxide of aluminum, silicon, titanium, zirconium and / or phosphorus and / or c) zirconium and / or titanium phosphates, phosphonates and / or sulfoaryl phosphonates and optionally an oxide of aluminum, silicon, titanium, zirconium and / or phosphorus as a network former. 35. membrane electrode assembly according to claim 34, characterized, that the Bronsted acid sulfuric acid, phosphoric acid, perchloric acid, nitric acid, Hydrochloric acid, sulfurous acid, phosphorous acid and esters thereof and / or comprises a monomeric or polymeric organic acid. 36. Membrane electrode unit according to claim 34, wherein the hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof is an organosilicon compound of the general formulas

[{(RO) _y (R ² ) _z } _a Si {R ¹ -SO ₃ ^- } _a ] _x M ^{x +} (I)

or

[(RO) _y (R ² ) _z Si {R ¹ -O _b -P (O _c R ³ ) O ₂ ^- } _a ] _x M ^{x +} (II)

, where R ^{1 is} a linear or branched alkyl or alkylene group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms or a unit of the general formulas


stands,
where n, m each represents an integer from 0 to 6,
M represents H, NH ₄ or a metal,
x = 1 to 4,
y = 1 to 3, z = 0 to 2 and a = 1 to 3, with the proviso that
y + z = 4 - a,
b, c = 0 or 1,
R, R ^{2 are the} same or different and stand for methyl, ethyl, propyl, butyl or H and
R ^{3 represents} M or a methyl, ethyl, propyl or butyl radical. 37. Membrane electrode unit according to claim 36, wherein the hydroxysilylalkyl acid Sulfur or phosphorus trihydroxysilylpropylsulfonic acid, Is trihydroxysilylpropylmethylphosphonic acid or dihydroxysilylpropylsulfondioic acid. 38. Membrane electrode unit according to one of claims 34, 36 or 37, characterized characterized in that the hydroxysilylallicylic acid of sulfur or phosphorus or a Salt thereof with a hydrolyzed compound of phosphorus or a hydrolyzed one Nitrate, oxynitrate, chloride, oxychloride, carbonate, alcoholate, acetate, acetylacetonate one Metal or semi-metal or with a hydrolyzed compound obtained by Hydrolysis of diethyl phosphite (DEP), diethyl ethyl phosphonate (DEEP), titanium propylate, Titanium ethylate, tetraethyl orthosilicate (TEOS) or tetramethyl orthosilicate (TMOS), Zirconium nitrate, zirconium oxynitrate, zirconium propylate, zirconium acetate, Zirconium acetylacetonate, phosphoric acid methyl ester or immobilized with precipitated silica. 39. Membrane electrode unit according to one of claims 33 to 38, characterized in that the proton-conducting component has proton-conducting substances selected from the titanium phosphates, titanium phosphonates, zirconium phosphates, zirconium phosphonates, iso- and heteropolyacids, preferably tungsten phosphoric acid or silicon tungstic acid, or nanocrystalline metal oxides, where Al ₂ O ₃ , ZrO ₂ , TiO ₂ or SiO ₂ powder are preferred. 40. membrane electrode assembly according to one of claims 33 to 39, characterized, that they are at a temperature of at least 80 ° C, preferably at least 100 ° C, and very particularly preferably can be operated at at least 120 ° C. 41. Membrane electrode unit according to one of claims 33 to 40, which has a bending radius down to 5000 mm, preferably down to 100 mm, most preferably up to tolerated down to 50 mm. 42. Membrane electrode unit according to one of claims 33 to 41, wherein the proton conductive component of the anode layer and cathode layer and that proton conductive material of the electrolyte membrane the same composition exhibit. 43. Membrane electrode unit according to one of claims 33 to 42, wherein the proton conductive component of the anode layer and the cathode layer the same Have composition. 44. Membrane electrode unit according to one of claims 33 to 43, wherein the Anode layer and the cathode layer have different catalysts. 45. Membrane electrode unit according to one of claims 33 to 44, wherein the Catalyst carrier in the anode layer and in the cathode layer electrically conductive is. 46. A method for producing a membrane electrode unit according to one of claims 33 to 45, the method comprising the following steps, A) Providing a proton-conductive, flexible electrolyte membrane for a fuel cell, which is impermeable to the reaction components of the fuel cell reaction, in particular according to one of claims 1 to 24, wherein the electrolyte membrane comprises a flexible, permeable composite material as a carrier, which has a flat, provided with a plurality of openings , Flexible substrate with a coating located on and in this substrate, wherein the material of the substrate is selected from woven or non-woven polymer fibers and the coating is a porous, ceramic coating, and wherein the carrier is interspersed with a proton-conductive material that is suitable to selectively direct protons through the membrane, B) Provision in each case of an agent for producing an anode layer and a cathode layer, the agent in each case comprising: 1. a condensable component which gives proton conductivity after the condensation of the electrode layer, 2. a catalyst which catalyzes the anode reaction or the cathode reaction, or a precursor compound of the catalyst, 3. optionally a catalyst support and 4. if necessary, a pore former, C) applying the agents from stage (B) to one side of the electrolyte membrane from stage (A) to form a coating, D) Creation of a firm bond between the coatings and the electrolyte membrane with the formation of a porous, proton-conductive anode layer or cathode layer, it being possible for the anode layer and the cathode layer to be formed simultaneously or in succession. 47. The method of claim 46, wherein the application of the agent in step (C) by Printing on, pressing on, pressing in, rolling up, knife coating, spreading on, dipping, Spraying or pouring takes place. 48. The method according to any one of claims 46 or 47, wherein the agent according to step (B) for producing an anode layer or a cathode layer is a suspension which is obtainable by 1. Preparation of a sol, comprising
a hydroxysilylalkyl acid of sulfur or phosphorus or its salt and optionally a hydrolyzable compound of phosphorus immobilizing the hydroxysilylalkyl acid of sulfur or phosphorus or its salt
or a hydrolyzable nitrate, oxynitrate, chloride, oxychloride, carbonate, alcoholate, acetate, acetylacetonate of a metal or semimetal, preferably methylphosphate, diethylphosphite (DEP), diethylethylphosphonate (DEEP), titanium propylate, titaniumethylate, tetraethylorthosilicate (TEOS) or tetraethyltosilicate (TEOS) or Zirconium nitrate, zirconium oxynitrate, zirconium propylate, zirconium acetate or zirconium acetylacetonate, 2. Dispersing the catalyst and optionally the catalyst support and pore former in the sol from (S1). 49. The method according to any one of claims 46 to 48, wherein the agent according to step (B) for producing an anode layer or a cathode layer is a suspension which is obtainable by 1. hydrolysis of a hydrolyzable compound to a hydrolyzate, the hydrolyzable compound being selected from
a hydrolyzable compound of phosphorus or hydrolyzable nitrates, oxynitrates, chlorides, oxychlorides, carbonates, alcoholates, acetates, acetylacetonates of a metal or semimetal, preferably aluminum alcoholates, vanadium alcoholates, titanium propylate, titanium ethylate, zirconium nitrate, zirconium oxynitate or zirconium propacyl acetate or zirconium propacyl acetate
Metal acids of aluminum, silicon, titanium, vanadium, antimony, tin, lead, chromium, tungsten, molybdenum, manganese, with tungsten phosphoric acid and silicon tungsten acid being preferred, 2. peptizing the hydrolyzate with an acid to form a dispersion, 3. Mixing the dispersion with a nanocrystalline proton-conducting metal oxide, preferably Al ₂ O ₃ , ZrO ₂ , TiO ₂ or SiO ₂ powder, 4. Dispersing the catalyst and optionally the carrier and pore former. 50. The method according to any one of claims 46 to 49, wherein the means for producing a Anode layer and a cathode layer are printed in step (C) and for Creation of a firm bond between the coatings and the Electrolyte membrane with the formation of a porous, proton-conductive anode layer or cathode layer in step (D) to a temperature of 20 to 300 ° C, preferably 50 to 200 ° C, most preferably 80 to 150 ° C is heated. 51. The method according to claim 48 or 49, characterized by 1. Applying the agent for producing an anode layer or cathode layer to a support membrane, preferably made of polytretrafluoroethylene, 2. drying of the coating obtained under (M1), 3. pressing the dried coating onto the electrolyte membrane at a temperature of 20 to 300 ° C., preferably 50 to 150 ° C., very particularly preferably 50 to 120 ° C., 4. Removing the support membrane, in particular by mechanical detachment, chemical dissolving, or pyrolizing or characterized by 5. applying the agent for producing an anode layer or cathode layer to a support membrane, preferably made of carbon paper or an electrically conductive fleece or fabric, 6. drying of the coating obtained under (N1) to produce a coated support membrane, 7. Pressing the coated support membrane onto the electrolyte membrane at a temperature from room temperature to 800 ° C., preferably 150 to 500 ° C., very particularly preferably 180 to 250 ° C. 52. The method according to any one of claims 48 or 49, wherein in step (B) in each case providing an agent for producing an anode layer and a cathode layer, the agent a) comprises a catalyst metal salt, preferably hexachloroplatinic acid b) after the application of the agents by step (C), the catalyst metal salt is reduced to a catalyst which catalyzes the anode reaction or the cathode reaction, c) in step (D), an open-pore gas diffusion electrode, preferably an open-pore carbon paper, is pressed onto the catalyst or glued to the catalyst with an electrically conductive adhesive. 53. The method according to any one of claims 46 to 52, wherein the application of the agent for Production of an anode layer or cathode layer is carried out repeatedly and optionally a drying step, preferably at an elevated temperature in a range of 50 to 200 ° C, between repeating the Applying. 54. The method according to any one of claims 46 to 53, wherein the application of the agent for Production of an anode layer or cathode layer on one of a first roll unrolled flexible electrolyte membrane or flexible support membrane. 55. The method according to any one of claims 46 to 54, wherein the application of the agent for Production of an anode layer or cathode layer takes place continuously. 56. The method according to any one of claims 46 to 55, wherein the application of the agent for Production of an anode layer or cathode layer on a heated electrolyte or support membrane. 57. The method according to any one of claims 46 to 56, wherein in step (D) to create a firm bond between the coatings and the electrolyte membrane on a Temperature of 20 to 300 ° C, preferably 50 to 200 ° C, very particularly preferred 80 to 150 ° C is heated. 58. The method of claim 57, wherein by means of heated air, hot air, infrared radiation or microwave radiation is heated. 59. Medium comprising: 1. a condensable component which, after the condensation of an anode layer or a cathode layer of a membrane electrode assembly, imparts proton conductivity to a fuel cell, 2. a catalyst which catalyzes the anode reaction or the cathode reaction in a fuel cell, or a precursor compound of the catalyst, 3. optionally a catalyst support and 4. optionally a pore former, and 5. optionally additives to improve foam behavior, viscosity and adhesion. 60. Composition according to claim 59, wherein the condensable component which, after the condensation of the anode layer or the cathode layer, gives proton conductivity is selected from A) hydrolyzable compounds of phosphorus or
hydrolyzable nitrates, oxynitrates, chlorides, oxychlorides, carbonates, alcoholates, acetates, acetylacetonates of a metal or semimetal, preferably aluminum alcoholates, vanadium alcoholates, titanium propylate, titanium ethylate, zirconium nitrate, zirconium oxynitrate, zirconium propylate, zirconium acetate or zirconium acetate
Metal acids of aluminum, titanium, vanadium, antimony, tin, lead, chromium, tungsten, molybdenum, manganese, with tungsten phosphoric acid being preferred, and / or B) an immobilizable hydroxysilylalkyl acid of sulfur or phosphorus or a salt thereof and optionally a hydrolysable compound of phosphorus or a hydrolysable nitrate, oxynitrate, chloride, oxychloride, carbonate, alcoholate, acetate, acetylacetonate one of the hydroxysilylalkyl acid of sulfur or phosphorus or its salt Metal or semimetal, preferably diethylphosphonate (DEP), diethylethylphosphonate (DEEP), phosphoric acid methyl ester, titanium propylate, titanium ethylate, tetraethylorthosilicate (TEOS) or tetramethylorthosilicate (TMOS), zirconium nitrate, zirconium oxynitrate, zirconium propyl acetate, zirconium propyl acetate. 61. Agent according to claim 59, in which the catalyst or the precursor compound of Catalyst includes platinum, palladium and / or ruthenium. 62. Agent according to one of claims 59 to 61, wherein the pore former is an organic and / or inorganic substance that is at a temperature between 50 and 300 ° C. and preferably decomposes between 100 and 200 ° C. 63. Agent according to claim 62, in which the inorganic pore former is ammonium carbonate or is ammonium bicarbonate. 64. Agent according to one of claims 59 to 63, wherein the catalyst support is electrical is conductive and preferably made of carbon black, graphite, carbon, carbon, activated carbon or Metal oxides exist. 65. Use of an electrolyte membrane according to one of claims 1 to 24 in one Fuel cell. 66. Use according to claim 65, wherein the fuel cell is a direct methanol Fuel cell or a reformate fuel cell. 67. Use of an electrolyte membrane according to one of claims 1 to 24 for Manufacture of a membrane electrode assembly, a fuel cell, or one Fuel cell stacks. 68. Use of a membrane electrode assembly according to any one of claims 33 to 45 in a fuel cell. 69. Use according to claim 68, wherein the fuel toe is a direct methanol Fuel cell or a reformate fuel cell. 70. Fuel cell with an electrolyte membrane according to one of claims 1 to 24. 71. Fuel cell with a membrane electrode unit according to one of claims 33 to 45th 72. Mobile or stationary system with a membrane electrode assembly, one Fuel cell or a fuel cell stack containing an electrolyte membrane according to one of claims 1 to 4 or a membrane electrode assembly according to one of the Claims 33 to 45. 73. Mobile or stationary system according to claim 72, characterized, that the mobile system is a vehicle and the stationary system is a home energy system is.