JP2013510383A - Membrane electrode assembly and fuel cell with improved performance - Google Patents

Abstract

The present invention includes (i) at least two electrochemically active electrodes, (ii) the electrodes are separated by at least one polymer electrolyte membrane, or electrolyte matrix, and (iii) the electrodes are A membrane electrode assembly comprising a catalyst layer in contact with the polymer electrolyte membrane or electrolyte matrix, (iv) at the cathode, the catalyst layer comprising, as an ionomeric material, a polymer comprising a repeating unit of formula (I); And a fuel cell with increased performance.
[Selection figure] None

Description

  The present invention relates to a membrane electrode assembly comprising at least two electrochemically active electrodes separated by a polymer electrolyte membrane, and a fuel cell with improved performance.

Polymer electrolyte membrane (PEM) fuel cells are already known. Currently, sulfonic acid-modified polymers are used almost exclusively in these fuel cells as proton conducting membranes. Here, perfluorinated polymers are mainly used. Nation ^™ from DuPont de Nemours, Willington, USA is a prominent example of this. For proton conduction, a relatively high water content is required in the membrane, which is typically an amount of 4-20 molecules per sulfonic acid group. The required water content, and the stability of the polymer in association with acidic water and reactive gases, hydrogen and oxygen typically limits the operating temperature of the PEM fuel cell stack to 80-100 ° C. When pressure is applied, the operating temperature can be increased to> 120 ° C. Otherwise, higher temperature operation will damage the power of the fuel cell.

  For system-specific reasons, fuel cell operating temperatures in excess of 100 ° C. are desirable. The activity of catalysts based on noble metals and contained in membrane electrode assemblies (MEAs) is greatly improved at high operating temperatures. When so-called hydrocarbon reformers are used, the reformer gas contains in particular a substantial amount of carbon monoxide, which usually needs to be removed using a synthesis gas conditioning or gas purification process. . The tolerance of the catalyst for CO impurities increases at higher operating temperatures.

  In addition, heat is generated during operation of the fuel cell. However, cooling these systems to below 80 ° C. is very complex. Depending on the power output, the cooling device can be configured with greatly reduced complexity. This means that the waste heat in fuel cells operating at temperatures above 100 ° C. can be used clearly and better, and therefore the efficiency of the fuel cell system through combined power and heat generation. It means that can be increased.

  To achieve these temperatures, membranes with new conduction mechanisms are usually used. One approach for this purpose is the use of membranes that exhibit conductivity without the use of water. A first promising development in this direction is disclosed in US Pat.

  The tapable (outputtable) voltage of individual fuel cells is relatively low, usually several membrane electrode assemblies are connected in series and connected to each other via a planar separator plate (bipolar plate). .

WO96 / 13872

  In practice, however, currently used membrane electrode assemblies need to be further improved to become a more competitive economic alternative. One improvement required is to increase the performance of the membrane electrode assembly with respect to oxygen reduction at the cathode of the membrane electrode assembly.

  Accordingly, an object of the present invention is to provide a membrane electrode assembly and a fuel cell having the highest possible performance at the cathode of the membrane electrode assembly in which oxygen reduction is performed.

In addition, the improved membrane electrode assembly should preferably have the following properties:
• The fuel cell should have the longest possible service life.
• The fuel cell should be usable at the highest possible operating temperature, in particular above 100 ° C.
In operation, individual batteries (cells) should exhibit constant or improved performance over a period (which should be as long as possible).
After a long operating time, the fuel cell should have the highest open circuit voltage possible and the lowest possible gas crossover. Furthermore, they should be able to be operated as low as possible in stoichiometry.
• Fuel cells should be handled without additional humidification of fuel gas if possible.
• The fuel cell should withstand as well as possible a constant or alternating pressure difference between the anode and cathode.
In particular, the fuel cell should be robust to different operating conditions (T, p, geometry, etc.) and increase the general reliability as good as possible.
Furthermore, the fuel cell should have improved temperature and corrosion resistance and have a relatively low gas permeability, especially at high temperatures. Degradation of mechanical stability and structural integrity, especially at high temperatures, should be avoided as much as possible.

  These objects are achieved by the present invention.

The present invention
(I) comprising at least two electrochemically active electrodes;
(Ii) the electrodes are separated by at least one polymer electrolyte membrane or electrolyte matrix;
(Iii) the electrode has a catalyst layer in contact with the polymer electrolyte membrane or electrolyte matrix;
(Iv) the catalyst comprises at least one ionomeric material;
A membrane electrode assembly comprising:
At least the catalyst layer in contact with the cathode is a general formula (I)

(However, (a)
Ar is the same or different and is a tetracovalent aromatic group or a heteroaromatic group having four covalent bonds, each of which is monocyclic, bicyclic Or X can be the same or different and represent N, O, S, and R ¹ can be the same or different, and the formula

の２つの共有結合を有する基を表し、及び
Ａｒ¹、Ａｒ²が、同一であるか、又は異なり、及び２つの共有結合を有する芳香族基、又は２つの共有結合を有する複素環式芳香族基を表し、それぞれが単環式、二環式、又は多環式が可能であり、及び、
Ｚ¹が、同一であるか、又は異なり、及び二価のアルキル基、及び／又は二価の芳香族基を表し、両方が、少なくとも１個の水素原子がフッ素原子によって置き換えられており、及び
ｎが、０．１〜９９．９モル−％であるか、
又は（ｂ）
Ａｒが、同一であるか、又は異なり、及び式

A group having two covalent bonds, and Ar ¹ and Ar ² are the same or different, and an aromatic group having two covalent bonds, or a heterocyclic aromatic group having two covalent bonds Each represents a monocyclic, bicyclic, or polycyclic group, and
Z ¹ is the same or different and represents a divalent alkyl group and / or a divalent aromatic group, both of which at least one hydrogen atom is replaced by a fluorine atom, and n is 0.1 to 99.9 mol-%,
Or (b)
Ar is the same or different and has the formula

の、４つの共有結合を有する基を表し、
Ａｒ³、Ａｒ⁴が、同一であるか、又は異なり、及び３つの共有結合を有する芳香族基、又は３つの共有結合を有する複素環式芳香族基を表し、それぞれが単環式、二環式、又は多環式が可能であり、及び、
Ｚ²が、同一であるか、又は異なり、及び二価のアルキル基、及び／又は二価の芳香族基を表し、両方が、少なくとも１個の水素原子がフッ素原子によって置き換えられており、及び
Ｘが、同一であるか、又は異なり、及びＮ、Ｏ、Ｓを表し、及び
Ｒ¹が、同一であるか、又は異なり、及び（ｉ）式

Represents a group having four covalent bonds,
Ar ³ and Ar ⁴ are the same or different and each represents an aromatic group having three covalent bonds or a heterocyclic aromatic group having three covalent bonds, each of which is monocyclic or bicyclic Can be of formula or polycyclic, and
Z ² is the same or different and represents a divalent alkyl group and / or a divalent aromatic group, both of which at least one hydrogen atom is replaced by a fluorine atom, and X is the same or different and represents N, O, S, and R ¹ is the same or different and (i)

の２つの共有結合を有する基を表し、及び
Ａｒ⁵、Ａｒ⁶が、同一であるか、又は異なり、及び２つの共有結合を有する芳香族基、又は２つの共有結合を有する複素環式芳香族基を表し、それぞれが単環式、二環式、又は多環式が可能であり、及び
Ｚ³が、同一であるか、又は異なり、及びＮ、Ｏ、Ｓを表すか、
又は（ｉｉ）二価のアルキル基、及び／又は二価の芳香族基を表し、両方が、更に置換されることができ、及び
ｎが０．１〜９９．９モル−％である）
の繰り返し単位を含むポリマーを含むことを特徴とする膜電極アセンブリに関する。

A group having two covalent bonds, and Ar ⁵ and Ar ⁶ are the same or different, and an aromatic group having two covalent bonds, or a heterocyclic aromatic group having two covalent bonds Each represents a monocyclic, bicyclic, or polycyclic group, and Z ³ is the same or different and represents N, O, S,
Or (ii) represents a divalent alkyl group and / or a divalent aromatic group, both can be further substituted, and n is from 0.1 to 99.9 mol-%)
The present invention relates to a membrane electrode assembly comprising a polymer containing repeating units of:

  In both options (a) or (b), n is preferably between 40 and 60 mol%, most preferably 50 mol%, whereby the quota between both secondary units of the repeating unit Are comparable or equal.

  In both options (a) or (b), X is preferably N or O. In option (b), most preferably X is O.

Preferably, the alkyl at Z ¹ and / or Z ² is, independently of one another, a short-chain divalent alkyl group having 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, or i- Propyl, and n-, i-, or t-butyl, n-, i-, or t-pentane, n-, i-, or t-hexane.

Preferably, the alkyl at Z ¹ and / or Z ² is, independently of one another, a short-chain divalent alkyl group having 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, or i- Propyl and n-, i-, or t-butyl, n-, i-, or t-pentane, n-, i-, or t-hexane, and at least one carbon atom is perfluorinated Or at least one carbon atom is substituted by at least one (CF ₃ ) — group, most preferably substituted by two (CF ₃ ) — groups to give —C (CF ₃ ) ₂ —. Form a group.

Preferably, the aromatic groups in Z ¹ and / or Z ² represent, independently of one another, a divalent aromatic group having 5 to 6 carbon atoms, wherein one or more carbon atoms are N , O or S can be replaced by a heteroatom and at least one carbon atom is perfluorinated or at least one carbon atom is replaced by at least one (CF ₃ ) -group It is substituted, or at least one of (CF ₃₎ - substituted by group, and most preferably two (CF ₃₎ - substituted -C (CF ₃₎ by a group ₂ - to form a group Or represents an alkyl group having 2 to 6 carbon atoms substituted by a terminal —C (CF ₃ ) ₃ group.

Preferably, in option (b), R ¹ , independently of each other, is a divalent alkyl group having 1 to 10 carbon atoms, such as methyl, ethyl, n-propyl, or i-propyl, and n- , I-, or t-butyl, n-, i-, or t-pentane, n-, i-, or t-hexane.

Preferably, in option (b), R ¹ , independently of each other, represents a divalent aromatic basis having 5 to 6 carbon atoms, wherein one or more carbon atoms are N, O or It can be replaced by a heteroatom selected from S.

A preferred aromatic group having two covalent bonds, or a heterocyclic aromatic group having two covalent bonds Ar ¹ , Ar ² , Ar ⁵ , Ar ⁶ , independently of each other, is monocyclic, bicyclic, Or a polycyclic fused or unfused aromatic or heteroaromatic ring system having 5 to 20 carbon atoms, said aromatic or heteroaromatic ring system Can have one or more carbon atoms replaced by N, O, S. The aromatic group having two covalent bonds or the heterocyclic aromatic group Ar ¹ , Ar ² , Ar ⁵ , Ar ⁶ having two covalent bonds can be substituted by further groups.

Most preferably, the aromatic group having two covalent bonds or the heterocyclic aromatic group having two covalent bonds Ar ¹ , Ar ² , Ar ⁵ , Ar ⁶ is independently of each other benzene, naphthalene, biphenyl. , Diphenyl ether, diphenylmethane, diphenyldimethylmethane, bisphenone, diphenylsulfone, quinoline, pyridine, bipyridine, pyridazine, pyrimidine, pyrazine, triazine, tetrazine, pyrrole, pyrazole, anthracene, benzopyrrole, benzotriazole, benzooxathiadiazole, benzooxadiazole , Benzopyridine, benzopyrazine, benzopyrazidine, benzopyrimidine, benzopyrazine, benzotriazine, indolizine, quinolidine, pyridopyridine, imidazopyrimidine, pyrazinopyrimidine , Carbazole, aziridine, phenazine, benzoquinoline, phenoxazine, phenothiazine, Akurijijin, derived Benzoputerijin, phenanthroline, and phenanthrene (these can also be optionally substituted).

Preferred aromatic groups having three covalent bonds or heterocyclic aromatic groups having three covalent bonds Ar ³ , Ar ⁴ independently of one another have 5 to 20 carbon atoms, monocyclic, In bicyclic, polycyclic, fused, aromatic, or heteroaromatic ring systems, one or more carbon atoms can be replaced by N, O, S. The aromatic group having 3 covalent bonds or the heterocyclic aromatic group Ar ³ , Ar ⁴ having 3 covalent bonds can be substituted by further groups.

Most preferably, the aromatic group having three covalent bonds or the heteroaromatic group having three covalent bonds Ar ³ and Ar ⁴ are independently of each other benzene, naphthalene, biphenyl, diphenyl ether, diphenylmethane, diphenyldimethylmethane. , Bisphenone, diphenylsulfone, quinoline, pyridine, bipyridine, pyridazine, pyrimidine, pyrazine, triazine, tetrazine, pyrrole, pyrazole, anthracene, benzopyrrole, benzotriazole, benzooxathiadiazole, benzooxadiazole, benzopyridine, benzopyrazine, benzopyrazidine , Benzopyrimidine, benzopyrazine, benzotriazine, indolizine, quinolidine, pyridopyridine, imidazopyrimidine, pyrazinopyrimidine, carbazole, Lysine, phenazine, benzoquinoline, phenoxazine, phenothiazine, Akurijijin, derived Benzoputerijin, phenanthroline, and phenanthrene (these can also be optionally substituted).

  Preferred aromatic groups having 4 covalent bonds or heteroaromatic groups Ar having 4 covalent bonds are, independently of each other, monocyclic, bicyclic or polycyclic fused, Or an aromatic or heteroaromatic ring system having 5 to 20 carbon atoms that is not condensed, wherein one or more carbon atoms may be replaced by N, O, S . The aromatic group having 4 covalent bonds or the heterocyclic aromatic group Ar having 4 covalent bonds can be substituted with further groups.

  Most preferably, the aromatic group having four covalent bonds or the heteroaromatic group Ar having four covalent bonds is independently of each other benzene, naphthalene, biphenyl, diphenyl ether, diphenylmethane, diphenyldimethylmethane, bisphenone, diphenyl. Sulfone, quinoline, pyridine, bipyridine, pyridazine, pyrimidine, pyrazine, triazine, tetrazine, pyrrole, pyrazole, anthracene, benzopyrrole, benzotriazole, benzoxathiadiazole, benzoxadiazole, benzopyridine, benzopyrazine, benzopyrazidine, benzopyrimidine, Benzopyrazine, benzotriazine, indolizine, quinolidine, pyridopyridine, imidazopyrimidine, pyrazinopyrimidine, carbazole, aziridine, Enajin, benzoquinoline, phenoxazine, phenothiazine, Akurijijin, derived Benzoputerijin, phenanthroline, and phenanthrene (these can also be optionally substituted).

  In a preferred embodiment of the invention, the polymer comprising repeating units of general formula (I) comprises at least 10, more preferably at least 50 repeating units of general formula (I).

Most preferably, the polymer comprising repeating units of general formula (I) has a weight average molecular weight M _w of greater than 10,000 (as measured by gel permeation chromatography).

Most preferably, the polymer comprising repeating units of general formula (I) has a number average molecular weight M _n of greater than 5000.

  Most preferably, the polymer comprising repeating units of general formula (I) has a solubility in DMAc of at least 0.5% by weight at 25 ° C.

At the cathode, it is preferable to have an ionomeric material according to the present invention present on the catalyst layer in a predetermined proportion relative to the catalyst material. Typical catalyst content, most typically noble metal content in the catalyst layer is 0.1 to 10.0 mg / cm ² , preferably 0.3 to 6.0 mg / cm ² , and especially Preferably it is 1-4.0 mg / cm < ² >. Accordingly, the mass ratio between the ionomeric material and the catalyst is preferably 100: 1 to 1: 100, most preferably 10: 1 to 1:10. A specific preferred ratio is 1: 8 to 1: 3. These amounts and proportions also apply to the catalyst layer in the anode, if desired.

The polymer containing the repeating unit of the general formula (I) is
A) Forming a solution and / or dispersion in polyphosphoric acid to form one or more aromatic di-, tri, or tetraamino compounds (containing at least two acidic groups per carboxylic acid monomer) When mixed with one or more aromatic carboxylic acids, or esters thereof, at least one di-, tri-, or tetraamino compound, or aromatic carboxylic acid has at least one fluorine atom / fluorinated. Or one or more aromatic diamino-dihydroxy compounds are mixed with one or more aromatic carboxylic acids (containing at least two acidic groups per carboxylic acid monomer), or esters thereof, and at least one Of the diamino-dihydroxy compound, or aromatic carboxylic acid has at least one fluorine atom / fluorinated, or one or more aromatics, and Or heteroaromatic diamino carboxylic acids were mixed, at least one diamino-carboxylic acid, is / fluorinated having at least one fluorine atom,
B) The mixture from step A) is heated under inert gas at a temperature of 350 ° C. or lower, preferably 280 ° C. or lower, to form a polymer comprising repeating units of general formula (I).
Can be manufactured.

  The mixture obtained from step B) can be used directly as an ionomer in a catalyst layer (especially a catalyst that later contacts the cathode) into a polymer containing repeating units of general formula (I). it can.

  In an alternative route, the mixture obtained from step B) can be separated by first precipitating the polymer in a medium containing non-solvent, such as water or water, and optionally drying. When such a route is chosen, the polymer containing the recurring unit of general formula (I) can be used as a solvent (eg DMAc, phosphoric acid) for introduction into the catalyst layer as an ionomer (especially later in contact with the cathode). Or polyphosphoric acid).

Proton-conducting electrolyte membranes and matrices, respectively, polymer electrolyte membranes and electrolyte matrices suitable for the purposes of the present invention are known per se.

  In addition to known polymer electrolyte membranes, electrolyte matrices are also suitable. In the context of the present invention, “electrolyte matrix” is understood to mean any other matrix material in which the ion-conducting material or mixture (in addition to the polymer electrolyte matrix) is fixed or immobilized in the matrix. Is done. As an example, a matrix made of SiC and phosphoric acid may be described here.

  Usually, a polymer electrolyte membrane containing an acid is used, where the acid may be covalently bonded to the polymer. Further, a flat material may be doped with an acid in order to form an appropriate film.

  The doped membrane can be produced by, among other methods, a flat film that has been swollen (swelled), such as a polymer film having a liquid containing an acidic compound, or a mixture of a polymer and an acidic compound, It can then be produced by forming a film (by forming a flat structure and then solidifying to form a film).

Suitable polymers for this purpose are in particular polyolefins such as poly (chloroprene), polyacetylene, polyphenylene, poly (p-xylene), polyarylmethylene, polystyrene, polymethylstyrene, polyvinyl alcohol, polyvinyl acetate, polyvinyl ether, Polyvinylamine, poly (N-vinylacetamine), polyvinylimidazole, polyvinylcarbazole, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polyhexafluoropropylene, PTFE, hexafluoropropylene, perfluoro Copolymer of propyl vinyl ether, trifluoronitrosomethane, carbalkoxyperfluoroalkoxy vinyl ether Chromatography, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, poly acrolein, polyacrylamide, polyacrylonitrile, poly cyanoacrylates, polymethacrylimide, cycloolefinic copolymers, in particular of norbornene;
Polymer having C—O bond in the backbone, such as polyacetal, polyoxymethylene, polyether, polypropylene oxide, polyepichlorohydrin, polytetrahydrofuran, polyphenylene oxide, polyether ketone, polyester, especially polyhydroxyacetic acid, polyethylene Terephthalate, polybutylene terephthalate, polyhydroxybenzoate, polyhydroxypropionic acid, polypivalolactone, polycaprolactone, polymalonic acid, polycarbonate;
Polymeric C—S— linkages in the backbone, such as polysulfide ethers, polyphenylene sulfides, polysulfones, polyether sulfones;
Polymeric C—N bonds in the backbone, such as polyimine, polyisocyanide, polyetherimine, polyetherimide, polyaniline, polyaramid, polyamide, polyhydrazide, polyurethane, polyimide, polyazole, polyazole ether ketone, polyazine;
Liquid crystalline pomers, especially Vectra, and inorganic polymers such as polysilanes, polycarbosilanes, polysiloxanes, polysilicic acid, polysilicates, silicones, polyphosphazenes, and polythiazyl.

  In this regard, alkaline polymers are preferred, and alkaline polymers are particularly applicable to acid doped membranes. Almost all of the known polymer membranes that can carry protons are considered as acid-doped alkaline polymer membranes. Here, acids which can carry protons without the use of additional water, for example by the so-called “grottas mechanism” are preferred.

  As the alkaline polymer for the present invention, it is preferable to use an alkaline polymer having at least one nitrogen atom in the repeating unit.

  According to a preferred embodiment, the repeating unit in the alkaline polymer comprises an aromatic ring having at least one nitrogen atom. Aromatic rings are 5-membered or 6-membered rings having 1 to 3 nitrogen atoms (these rings may be fused with other rings, especially other aromatic rings). Preferably).

  In accordance with certain aspects of the present invention, high temperature stable polymers are used that contain at least one nitrogen, oxygen and / or sulfur in one or different repeating units.

  In the context of the present invention, “stable at high temperature” means a polymer that can be operated as a polymer electrolyte in a fuel cell at temperatures in excess of 120 ° C. for extended periods of time. “Over a period of time” means that the membrane according to the invention is at least 100 hours, preferably at least 500 hours, at a temperature of at least 80 ° C., preferably at a temperature of at least 120 ° C., particularly preferably at a temperature of at least 160 ° C. This means that the performance can be operated without a decrease of more than 50% over the initial performance that can be measured according to the method described in / 18894A2.

  The above mentioned polymers can be used individually or as a mixture (blend). Here, blends containing polyazole and / or polysulfone are particularly preferred. In this regard, preferred blending components are polyethersulfone, polyetherketone, and polymers modified with sulfonic acids, as described in WO 02/36249. By using blends, mechanical properties can be improved and material costs can be reduced.

  Polyazoles constitute a particularly preferred group of alkaline polymers. Alkaline polymers based on polyazoles have the general formulas (I) and / or (II) and / or (III) and / or (IV) and / or (V) and / or (VI) and / or (VII) and / or Or (VIII) and / or (IX) and / or (X) and / or (XI) and / or (XII) and / or (XIII) and / or (XIV) and / or (XV) and / or ( XVI) and / or (XVII) and / or (XIII) and / or (XIX) and / or (XX) and / or (XXI) and / or (XXII)

(However,
Ar is the same or different, may be monocyclic or polycyclic, and is a tetracovalent aromatic or heterocyclic aromatic group;
Ar ¹ is the same or different, may be monocyclic or polycyclic, and is an aromatic or heteroaromatic group having two covalent bonds,
Ar ² is the same or different, may be monocyclic or polycyclic, and is an aromatic or heterocyclic aromatic group having two or three covalent bonds;
Ar ³ is the same or different, may be monocyclic or polycyclic, and is an aromatic or heteroaromatic group having three covalent bonds (tricovalent);
Ar ⁴ is an aromatic or heterocyclic aromatic group, which may be the same or different, may be monocyclic or polycyclic, and has three covalent bonds;
Ar ⁵ is an aromatic or heterocyclic aromatic group that may be the same or different, may be monocyclic or polycyclic, and has four covalent bonds;
Ar ⁶ is an aromatic or heteroaromatic group which may be the same or different, may be monocyclic or polycyclic, and has two covalent bonds;
Ar ⁷ is an aromatic or heterocyclic aromatic group that may be the same or different, may be monocyclic or polycyclic, and has two covalent bonds;
Ar ⁸ is an aromatic or heterocyclic aromatic group that may be the same or different, may be monocyclic or polycyclic, and has three covalent bonds;
Ar ⁹ is an aromatic or heterocyclic aromatic group that may be the same or different, may be monocyclic or polycyclic, and has 2 or 3 or 4 covalent bonds;
Ar ¹⁰ is the same or different, may be monocyclic or polycyclic, and is an aromatic or heteroaromatic group having two or three covalent bonds;
Ar ¹¹ is an aromatic or heterocyclic aromatic group, which may be the same or different, may be monocyclic or polycyclic, and has two covalent bonds;
X is the same or different and is an oxygen, sulfur or amino group (these are hydrogen atoms, groups having 1 to 20 carbon atoms, preferably branched or unbranched alkyl- or alkoxy groups, Or an aryl group as a further group)
R is the same or different and is hydrogen, an alkyl group, and an aromatic group (provided that R in formula (XX) is not hydrogen), and n and m are integers of 10 or more, preferably 100 or more Integer)
Of repeating azole units.

  Preferred aromatic or heteroaromatic groups are benzene, naphthalene, biphenyl, diphenyl ether, diphenylmethane, diphenyldimethylmethane, bisphenone, diphenylsulfone, quinoline, pyridine, bipyridine, pyridazine, pyridazine, pyrimidine, pyrazine, triazine, tetrazine, pyrrole , Pyrazole, anthracene, benzopyrrole, benzotriazole, benzooxathiazole, benzooxadiazole, benzopyridine, benzopyrazine, benzopyrazidine, benzopyrimidine, benzotriazine, indolizine, quinolidine, pyridopyridine, imidazopyrimidine, pyrazinopyrimidine, carbazole, Aziridine, phenazine, benzoquinoline, phenoxazine, phenothiazine, acrididine, benzo Terijin, phenanthroline, and phenanthrene (which optionally also may be substituted) is derived from.

In this case, Ar ¹ , Ar ⁴ , Ar ⁶ , Ar ⁷ , Ar ⁸ , Ar ⁹ , Ar ¹⁰ , Ar ¹¹ may have any substitution pattern. For example, in the case of phenylene, Ar ¹ , Ar ⁴ , Ar ⁶ , Ar ⁷ , Ar ⁸ , Ar ⁹ , Ar ¹⁰ , Ar ¹¹ may be ortho-phenylene, meta-phenylene, and para-phenylene. Particularly preferred groups are derived from benzene and biphenylene, which may be substituted.

  Preferred alkyl groups are short-chain alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl or i-propyl and t-butyl groups.

  Preferred aromatic groups are phenyl or naphthyl groups. Alkyl groups and aromatic groups may be substituted.

  Preferred substituents are halogen atoms such as fluorine, amino groups, hydroxy groups or short chain alkyl groups such as methyl or ethyl groups.

  Preference is given to polyazoles having a repeating unit of the formula (I) in which the functional groups X in the repeating unit are identical.

  Polyazoles may in principle have different repeating units (for example with different functional groups X). However, it is preferred that only the same functional group X is present in the repeating unit.

  Further preferred polyazole polymers are polyimidazole, polybenzothiazole, polybenzoxazole, polyoxadiazole, polyquinoxaline, polythiadiazole, poly (pyridine), poly (pyrimidine) and poly (tetrazapyrene).

  In another embodiment of the invention, the polymer having repeating azole units is a copolymer or blend of formulas (I) to (XXII) comprising at least two different units. The polymer can be in the form of a block copolymer (diblock, triblock), random block copolymer, periodic copolymer and / or alternating polymer.

  In a particularly preferred embodiment of the invention, the polymer comprising repeating azole units is a polyazole comprising only units of the formula (I) and / or (II).

  The number of repeating azole units in the polymer is preferably an integer of 10 or more. Particularly preferred polymers contain at least 100 repeating azoles.

  In the present invention, a polymer containing repeating benzimidazole units is preferred. The most useful polymers containing repeating benzimidazole units are represented by the following formula:

  (However, n and m are an integer of 10 or more, preferably an integer of 100 or more.)

  However, the polyazoles used, in particular polybenzimidazoles, are characterized by a high molecular weight. Measured as intrinsic viscosity, this is preferably at least 0.2 dl / g, preferably 0.8 to 10 dl / g, in particular 1 to 10 dl / g.

  The production of such polyazoles is known, wherein the one or more aromatic tetra-amino compounds contain at least two acidic groups per carboxylic acid monomer in the melt. Is reacted with an aromatic carboxylic acid or an ester thereof to form a prepolymer. The resulting prepolymer is solidified (solidified) in the reaction vessel and then mechanically crushed. Powdered prepolymers are usually fully polymerized, usually at temperatures up to 400 ° C., in solid state polymerization.

  Preferred aromatic carboxylic acids are, in particular, dicarboxylic acids and tricarboxylic acids and tetracarboxylic acids or their esters or anhydrides or acid chlorides thereof. The term aromatic carboxylic acid likewise includes heterocyclic aromatic carboxylic acids.

  Preferably, the aromatic dicarboxylic acid is isophthalic acid, terephthalic acid, phthalic acid, 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, 2-hydroxyterephthalic acid, 5-aminoisophthalic acid, 5-N, N-dimethylamino. Isophthalic acid, 5-N, N-diethylaminoisophthalic acid, 2,5-dihydroxyterephthalic acid, 2,6-dihydroxyisophthalic acid, 4,6-dihydroxyisophthalic acid, 2,3-dihydroxyphthalic acid, 2, 4-dihydroxyphthalic acid, 3,4-dihydroxyphthalic acid, 3-fluorophthalic acid, 5-fluoroisophthalic acid, 2-fluoroterephthalic acid, tetrafluorophthalic acid, tetrafluoroisophthalic acid, tetrafluoroterephthalic acid, 1,4 -Naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenic acid, 1,8-dihydroxynaphthalene-3,6-dicarboxylic acid, diphenyl ether-4,4′-dicarboxylic acid, benzophenone-4,4 ′ -Dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, 4-trifluoromethylphthalic acid, 2,2-bis- (4-carboxyphenyl) hexafluoropropane, 4, , 4′-stilbene dicarboxylic acid, 4-carboxycinamic acid, or a C1-C20 alkyl ester thereof, or C5-C12 aryl acid, or an acid anhydride or acid chloride thereof.

  The aromatic tricarboxylic acid, tetracarboxylic acid or its C1-C20 alkyl ester or C5-C12 aryl ester or its acid anhydride or its acid chloride is preferably 1,3,5-benzenetricarboxylic acid (trimesic acid), 1 1,2,4-benzenetricarboxylic acid (trimesic acid), (2-carboxyphenyl) iminodiacetic acid, 3,5,3′-biphenyltricarboxylic acid or 3,5,4′-biphenyltricarboxylic acid is preferred.

  An aromatic tetracarboxylic acid, or a C1-C20 alkyl ester or C5-C12 aryl ester thereof or an acid anhydride or acid chloride thereof is 3,5,3 ′, 5′-biphenyltetracarboxylic acid, 1,2, 4,5-benzenetetracarboxylic acid, benzophenonetetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 2,2 ′, 3,3′-biphenyltetracarboxylic acid, 1,2,5, 6-naphthalenetetracarboxylic acid or 1,4,5,8-naphthalenetetracarboxylic acid is preferred.

  The heterocyclic aromatic carboxylic acid used is preferably a heterocyclic aromatic dicarboxylic acid, tricarboxylic acid and tetracarboxylic acid, or an ester thereof or an anhydride thereof. Heteroaromatic carboxylic acid is understood to mean an aromatic system having at least one nitrogen, oxygen, sulfur or phosphorus atom in the aromatic group. Preferably this is pyridine-2,5-dicarboxylic acid, pyridine-3,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid, pyridine-2,4-dicarboxylic acid, 4-phenyl-2,5- Pyridine dicarboxylic acid, 3,5-pyrazole dicarboxylic acid, 2,6-pyrimidine dicarboxylic acid, 2,5-pyrazine dicarboxylic acid, 2,4,6-pyridine tricarboxylic acid, or benzimidazole-5,6-dicarboxylic acid and its C1-C20 alkyl ester or C5-C12 aryl ester or acid anhydride or acid chloride thereof.

  The content of tricarboxylic acid or tetracarboxylic acid is 0 to 30 mol%, preferably 0.1 to 20 mol%, in particular 0.5 to 10 mol% (relative to the dicarboxylic acid used).

  The aromatic and heteroaromatic diaminocarboxylic acids used are preferably diaminobenzoic acid and its monohydrochloride or dihydrochloride derivatives.

  It is preferred to use a mixture of at least two aromatic carboxylic acids. It is particularly preferred to use a mixture which also contains a heterocyclic aromatic carboxylic acid in addition to the aromatic carboxylic acid. The mixing ratio of the aromatic carboxylic acid to the heterocyclic aromatic carboxylic acid is in the range of 1:99 to 99: 1, preferably in the range of 1:50 to 50: 1.

  These mixtures are in particular mixtures of N-heteroaromatic dicarboxylic acids and aromatic dicarboxylic acids. These examples (but not limited to) are: isophthalic acid, terephthalic acid, phthalic acid, 2,5-hydroxyterephthalic acid, 2,6-dihydroxyisophthalic acid, 4,6-hydroxyisophthalic acid, 2,3-dihydroxy Phthalic acid, 2,4-dihydroxyphthalic acid, 3,4-dihydroxyphthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid , Diphenic acid, 1,8-dihydroxynaphthalene-3,6-dicarboxylic acid, diphenyl ether-4,4′-dicarboxylic acid, benzophenone-4,4′-dicarboxylic acid, diphenylsulfone-4,4′-dicarboxylic acid, biphenyl -4,4'-dicarboxylic acid, 4-trifluoromethylphthalic acid, pyridine-2, -Dicarboxylic acid, pyridine-3,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid, pyridine 2,4-dicarboxylic acid, 4-phenyl-2,5-pyridinedicarboxylic acid, 3,5-pyrazole dicarboxylic acid, It is a mixture of 2,6-pyrimidinedicarboxylic acid and 2,5-pyridinedicabonic acid.

  Preferred aromatic tetraamino compounds are in particular 3,3 ′, 4,4′-tetraaminobiphenyl, 2,3,5,6-tetraaminopyridine, 1,2,4,5-tetraaminobenzene, 3, 3 ′, 4,4′-tetraaminodiphenyl sulfone, 3,3 ′, 4,4′-tetraaminodiphenyl ether, 3,3 ′, 4,4′-tetraaminobenzophenone, 3,3 ′, 4,4 ′ -Tetraaminodiphenylmethane and 3,3 ', 4,4'-tetraaminodiphenyldimethylmethane and their salts, in particular the monohydrochloride, dihydrochloride, trihydrochloride and tetrahydrochloride derivatives thereof.

  Preferred polybenzimidazoles are commercially available under the trade name (registered trademark) Celazole.

Preferred polymers are polysulfones, in particular polysulfones having aromatic and / or heterocyclic aromatic groups in the backbone. According to a particular aspect of the present invention, preferred polysulfones and polyether sulfones, melt volume rate MVR300 / 21.6 is measured in accordance with ISO 1133, 40cm ³ / 10min or less, in particular 30 cm ³ / 10min or less, and in particular it is preferably at most 20 cm ³ / 10min. Here, polysulfone having a Vicat softening temperature VST / A / 50 of 180 ° C. to 230 ° C. is preferable. In a further preferred embodiment of the invention, the number average molecular weight of the polysulfone is preferably greater than 30000 g / mol.

  Polymers based on polysulfones include in particular polymers having repeating units with linking sulphone groups according to the general formula A, B, C, D, E, F and / or G:

(However, the radicals R, independently of one another, are the same or different and represent an aromatic or heterocyclic aromatic basis, and these functional groups are as described above).

  These include in particular 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, 4,4'-biphenyl, pyridine, quinoline, naphthalene, phenanthrene.

  Within the scope of the present invention, preferred polysulfones include homopolymers and copolymers, such as random copolymers. Particularly preferred polysulfones comprise repeating units of the formula H to N:

(However, n> 0)

(However, n <0)

  The above-mentioned polysulfones are trade names (registered trademark) Victrex 200P, (registered trademark) Victrex 720P, (registered trademark) Ultrason E, (registered trademark) Ultrason S, (registered trademark) Mindel, (registered trademark) Radel A, (registered trademark). Commercially available at Radel R, (registered trademark) Victrex HTA, (registered trademark) Astrel, and (registered trademark) Udel.

Furthermore, polyether ketone, polyether ketone ketone, polyether ether ketone, polyether ether ketone ketone and polyaryl ketone are particularly preferred. These high performance polymers are known per se and are commercially available under the trade names Victrex® PEEK ^™ , (registered trademark) Hostatec, (registered trademark) Kadel.

  The aforementioned polysulfones and the aforementioned polyether ketones, polyether ketone ketones, polyether ether ketones, polyether ether ketone ketones and polyaryl ketones can be present as blend components with alkaline polymers, as described above. Furthermore, the above-mentioned polysulfone and the above-mentioned polyetherketone, polyetherketoneketone, polyetheretherketone, polyetheretherketoneketone and polyarylketone can be used as a polymer electrolyte in a sulfonated state. The oxidized material can also be characterized as a blend material with an alkaline polymer, in particular polyazole. The preferred embodiments described above and with respect to alkaline polymers or polyazoles also apply to these embodiments.

  To produce a polymer film, a polymer, preferably an alkaline polymer, in particular polyazole, can be dissolved in a polar, aprotic solvent such as dimethylacetamide (DMAc) in an additional step, and the film is conventionally It can be manufactured by the method.

  In order to remove the remainder of the solvent, the film thus obtained can be treated with a washing liquid as described in WO 02/071518. By washing the polyazole film as described in the above-mentioned patent application to remove the remainder of the solvent, the mechanical properties of the film are surprisingly improved. These properties include, inter alia, the E-module, tear strength and fracture strength of the film.

  Furthermore, the polymer film can have further modifications by crosslinking, for example as described in WO02 / 070592 or WO00 / 44816. In a preferred embodiment, the polymer used, consisting of an alkaline polymer and at least one blend component, additionally contains a cross-linking agent, as described in WO 03/016384.

  The thickness of the polyazole fill can be in a wide range. Preferably, the thickness of the polyazole film before being doped with acid is usually in the range of 5 μm to 2000 μm, particularly preferably in the range of 10 μm to 1000 μm, but is not limited to these ranges.

  In order to achieve proton conductivity, the film is doped with an acid. Here, the acid includes all known Lewis Bronsted acids, preferably inorganic Lewis Bronsted acids.

  Furthermore, it is also possible to apply polyacids, in particular isopolybasic and heteropolybasic acids and mixtures of different acids. Here, in the concept of the present invention, heteropolybasic acid defines inorganic polyacids having at least two different central atoms, each as a partially mixed anhydride, a metal It forms weak polybasic oxygen acids (preferably Cr, MO, V, W) and nonmetals (preferably As, I, P, Se, Si, Te). These include in particular 12-phosphomolybdic acid and 12-phosphotungstic acid.

  Through the degree of doping, the conductivity of the polyazole film can be influenced. The conductivity increases until the doping substance concentration increases and its value reaches a maximum value. In accordance with the present invention, the degree of doping is given as moles of acid per mole of polymer repeat units. Within the scope of the present invention, a degree of doping in the range 3-50, in particular a degree of doping in the range 5-40, is preferred.

Particularly preferred doping substances are sulfuric acid and phosphoric acid (phosphoric acid) or compounds that release these acids (eg during hydrolysis). A highly preferred doping material is phosphoric acid (H ₃ PO ₄ ). Here, highly concentrated acids are usually used. According to a particular aspect of the invention, the concentration of phosphoric acid is at least 50% by weight, in particular at least 80% by weight, based on the doping substance.

Further, the proton conductive membrane is obtained by the following steps:
I) dissolving a polymer, especially polyazole, in phosphoric acid,
II) heating the mixture obtained according to step A) to a temperature below 400 ° C. in the presence of an inert gas;
III) forming a membrane on a support using a solution of the polymer according to step II)
IV) treating the film formed in step III) until it becomes self-supporting;
It can also be obtained by a method comprising

Furthermore, the doped polyazole film comprises the following steps:
A) One or more aromatic tetraamino compounds are mixed with one or more aromatic carboxylic acids or esters thereof (containing at least two acid groups per carboxylic acid monomer) or one or more fragrances Mixing aromatic and / or heterocyclic aromatic diaminocarboxylic acids in polyphosphoric acid to form a solution and / or dispersion;
B) using the mixture according to step A) to layer the support or electrode;
C) The flat structure / layer obtained according to step B) is heated in the presence of an inert gas to a temperature of 350 ° C. or lower, preferably to a temperature of 280 ° C. or lower to form a polyazole polymer. Process,
D) processing the film formed in step C) (until it can stand on its own),
Can be obtained by a method comprising

  The aromatic or heterocyclic aromatic carboxylic acid and tetraamino compound used in step A) have been described above.

The polyphosphoric acid used in step A) is, for example, ordinary polyphosphoric acid available from Riedel-de Haen. Polyphosphoric acid H _{n + 2} P _n O _{3n + 1} (n> 1) usually has a concentration of at least 83%, calculated as P ₂ O ₅ (by acid titration). Instead of the monomer solution, it is also possible to produce a dispersion (dispersion) / suspension (suspension). The mixture prepared in step A) has a ratio of polyphosphoric acid to the sum of all monomers of 1: 10000 to 10000: 1, preferably 1: 1000 to 1000: 1, in particular 1: 100 to 100: 1.

  The layer formation according to step B) is carried out by methods known in the prior art for polymer film production (known per se) (pouring, spraying, application with a doctor blade). Any support that is considered inert under these conditions is suitable as a support. To adjust the viscosity, phosphoric acid (concentration, phosphoric acid, 85%) can be added to the solution if necessary. Thus, the viscosity can be adjusted to the desired value and film formation is facilitated.

  The layer produced according to step B) has a thickness of 10 to 4000 μm, preferably 20 to 4000 μm, very particularly preferably 30 to 3500 μm, in particular 50 to 3000 μm.

  If the mixture according to step A) also contains a tricarboxylic acid or a tetracarboxylic acid, branching / crosslinking of the formed polymer is achieved. This contributes to improved mechanical properties. The treatment of the polymer layer produced according to step C) is carried out in the presence of a predetermined moisture (humidity) and temperature and for a period of time sufficient for the layer to have sufficient strength for use in a fuel cell. This treatment is carried out to the extent that the membrane is self-supporting and can be removed from the support without any loss of the membrane.

  According to step C), the flat structure obtained in step B) is heated to a temperature of 350 ° C. or less, preferably to a temperature of 280 ° C. or less and particularly preferably in the range of 200 ° C. to 250 ° C. The The inert gas used in step C) is known to those skilled in the art. These include in particular nitrogen, noble gases such as neon, argon, helium.

  In a variant of the invention, the formation of the oligomer and / or polymer can be carried out by heating the mixture from step A) to a temperature up to 350 ° C., preferably up to 280 ° C. Depending on the selected temperature and duration, the subsequent heating in step C) can be partially or completely omitted. This modification is also one of the objects of the present invention.

  The treatment of the membrane in step D) is at a temperature above 0 ° C. and below 150 ° C., preferably at a temperature between 10 ° C. and 120 ° C., in particular at a temperature between room temperature (20 ° C.) and 90 ° C., with moisture or water and / or It is carried out in the presence of phosphoric acid (85% or less) containing steam and / or water. The treatment is preferably performed at a standard pressure, but can also be performed by applying pressure. The treatment is essentially performed in the presence of sufficient moisture (moisture), and the polyphosphoric acid present solidifies the membrane by partial hydrolysis, forming low molecular weight polyphosphoric acid and / or phosphoric acid. Contribute to doing.

The hydrolysis fluid may be a solution and the fluid may contain suspended and / or dispersed components. The viscosity of the hydrolysis fluid can range over a wide range, and solvent additions or temperature increases can be made to adjust the viscosity. The dynamic viscosity is preferably in the range from 0.1 to 10,000 mPa ^* s, in particular from 0.2 to 2000 mPa ^* s, and these values can be measured, for example, according to DIN 53015.

  The treatment according to step D) can be carried out by any known method. The membrane obtained in step C) can be immersed, for example, in a fluid bath. Furthermore, the hydrolysis fluid can be sprayed onto the membrane. Additionally, the hydrolysis fluid can be poured onto the membrane. The latter method has the advantage that the acid concentration in the hydrolysis fluid is kept constant during the hydrolysis. However, the first method is actually often less expensive.

  Phosphorus and / or sulfur oxoacids are in particular phosphinic acid, phosphonic acid, phosphoric acid (phosphoric acid), secondary phosphonic acid (high positive phosphoric acid), secondary diphosphoric acid (high positive phosphoric acid), oligophosphorus Contains acid, sulfurous acid, disulfurous acid, and / or sulfuric acid. These acids can be used individually or as a mixture.

  In addition, phosphorus and / or sulfur oxoacids can be processed by free-radical polymerization and include monomers containing phosphonic acid and / or sulfonic acid groups.

  Monomers containing phosphonic acid groups are known to those skilled in the art. These are compounds having at least one carbon-carbon double bond and at least one phosphonic acid group. Preferably, the two carbon atoms forming the carbon-carbon double bond have at least 2, preferably 3, bonds to the group, which result in minimal steric hindrance of the double bond . These groups include in particular hydrogen atoms and halogen atoms, in particular fluorine atoms. Within the scope of the present invention, polymers containing phosphonic acids are derived from polymerization products obtained by polymerizing monomers containing phosphonic acid groups alone or with other monomers and / or crosslinkers. can get.

  Monomers containing phosphonic acid groups may contain one, two, three or more carbon-carbon double bonds. Furthermore, the monomer containing phosphonic acid groups may contain one, two, three or more phosphonic acid groups.

  Usually, the monomer containing a phosphonic acid group contains 2 to 20, preferably 2 to 10 carbon atoms.

  Monomers containing phosphonic acid groups preferably have the formula

(However,
R is a bond, a C1-C15 alkylene group having two covalent bonds, a C1-C15 alkyleneoxy group having two covalent bonds, such as an ethyleneoxy group, or a C5-C20 aryl having two covalent bonds, or hetero An aryl group, and the functional groups described above are themselves substitutable with halogen, —OH, COOZ, —CN, NZ ₂ ;
Z is independently of one another hydrogen, a C1-C15 alkyl group, a C1-C15 alkoxy group, an ethyleneoxy group, or a C5-C20 aryl or heteroaryl group, and the functional groups mentioned above are themselves halogen, —OH , -CN, and x is an integer of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10;
y is an integer of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10)
And / or formula

(However,
R is a bond, a C1-C15 alkylene group having two covalent bonds, a C1-C15 alkyleneoxy group having two covalent bonds, such as an ethyleneoxy group, or a C5-C20 aryl having two covalent bonds, or hetero An aryl group, and the functional groups described above are themselves substitutable with halogen, —OH, COOZ, —CN, NZ ₂ ;
Z is independently of one another hydrogen, a C1-C15 alkyl group, a C1-C15 alkoxy group, an ethyleneoxy group, or a C5-C20 aryl or heteroaryl group, and the functional groups mentioned above are themselves halogen, —OH , -CN, and x is an integer of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.)
And / or formula

(However,
A is a group of the formula COOR ² , CN, CONR ² ₂ , OR ² and / or R ² , and R ² is hydrogen, a C1-C15 alkyl group, a C1-C15 alkoxy group, an ethyleneoxy group, or C5 -C20 aryl or heteroaryl group, the above-mentioned functional groups themselves, halogen, -OH, COOZ, -CN, are those that can be substituted by NZ _2,
R is a bond, a C1-C15 alkylene group having two covalent bonds, a C1-C15 alkyleneoxy group having two covalent bonds, such as an ethyleneoxy group, or a C5-C20 aryl having two covalent bonds, or hetero An aryl group, and the above-mentioned group itself may be substituted with halogen, —OH, COOZ, —CN, NZ ₂ ;
Z is independently of one another hydrogen, a C1-C15 alkyl group, a C1-C15 alkoxy group, an ethyleneoxy group, or a C5-C20 aryl or heteroaryl group, and the functional groups mentioned above are themselves halogen, —OH , -CN, and x is an integer of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.)
It is this compound.

  Preferred monomers containing phosphonic acid groups are in particular alkenes containing phosphonic acid groups, such as ethenephosphonic acid, propenephosphonic acid, butenephosphonic acid; acrylic acid compounds containing phosphonic acid groups, and / or methacrylic acid compounds, such as 2-phosphonomethylacrylic acid, 2-phosphonomethylmethacrylic acid, 2-phosphonomethylacrylamide, and 2-phosphonomethylmethacrylamide.

  Commercially available vinylphosphonic acid (ethenephosphonic acid), which is commercially available from, for example, Aldrich or Clariant GmbH, is particularly preferred for use. Preferred vinylphosphonic acids have a purity of more than 70%, in particular more than 90% and particularly preferably more than 97%.

  Monomers containing phosphonic acid groups can also be used in the form of derivatives. The derivative is then converted to an acid, which can also be carried out in the polymerized state. These derivatives include in particular salts, esters, amides and halides of monomers containing phosphonic acid groups.

  Furthermore, after hydrolysis, monomers containing phosphonic acid groups can be introduced onto or into the membrane. This can be done in a manner known per se (known from the prior art) (eg spraying, dipping etc.).

  According to a particular aspect of the present invention, the total mass of phosphoric acid, polyphosphoric acid, and the hydrolysis product of polyphosphoric acid, relative to the mass of the monomer that can be treated by radical polymerization, such as the monomer containing phosphonic acid, is: Preferably it is 1: 2 or more, particularly 1: 1 or more, particularly preferably 2: 1 or more.

  Preferably, the mass ratio of the total mass of phosphoric acid, polyphosphoric acid and the hydrolysis product of polyphosphoric acid to the mass of monomers treatable by radical polymerization is in the range from 1000: 1 to 3: 1, in particular 100: 1. It is in the range of -5: 1 and particularly preferably in the range of 50: 1 to 10: 1.

  This proportion can easily be determined by conventional methods, in which case phosphoric acid, polyphosphoric acid, and their hydrolysis products can often be washed out of the membrane. Thereby, the mass of polyphosphoric acid and its hydrolysis product can be obtained after the hydrolysis to phosphoric acid is completed. Usually this also applies to monomers that can be processed by radical polymerization.

  Monomers containing sulfonic acid groups are known to those skilled in the art. These are compounds having at least one carbon-carbon double bond and at least one sulfonic acid group. Preferably, the two carbon atoms forming the carbon-carbon double bond have at least two, preferably three (to group) bonds, thereby steric hindrance of the double bond. Is minimized. These groups include in particular hydrogen atoms and halogen atoms, in particular fluorine atoms. Within the scope of the present invention, a sulfonic acid-containing polymer is obtained from a polymerization product obtained by polymerizing monomers containing sulfonic acid groups alone or with other monomers and / or crosslinking agents. can get.

  Monomers containing sulfonic acid groups may contain one, two, three or more carbon-carbon double bonds. Further, the monomer containing sulfonic acid groups may contain one, two, three or more sulfonic acid groups.

  Usually, the monomer containing a sulfonic acid group contains 2 to 20, preferably 2 to 10 carbon atoms.

  Monomers containing sulfonic acid groups are preferably of the formula

(However,
R is a bond, a C1-C15 alkylene group having two covalent bonds, a C1-C15 alkyleneoxy group having two covalent bonds, such as an ethyleneoxy group, or a C5-C20 aryl having two covalent bonds, or hetero An aryl group, and the functional group described above may itself be substituted with halogen, —OH, COOZ, —CN, NZ ₂ ;
Z, independently of one another, is hydrogen, a C1-C15 alkyl group, a C1-C15 alkoxy group, an ethyleneoxy group, or a C5-C20 aryl or heteroaryl group, and the aforementioned groups are themselves halogen, —OH, -CN may be substituted, and x is an integer of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10;
y is an integer of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10)
And / or formula

(However,
R is a bond, a C1-C15 alkylene group having two covalent bonds, a C1-C15 alkyleneoxy group having two covalent bonds, such as an ethyleneoxy group, or a C5-C20 aryl having two covalent bonds, or hetero An aryl group, and the functional groups described above are themselves substitutable with halogen, —OH, COOZ, —CN, NZ ₂ ;
Z, independently of one another, is hydrogen, a C1-C15 alkyl group, a C1-C15 alkoxy group, an ethyleneoxy group, or a C5-C20 aryl or heteroaryl group, and the aforementioned groups are themselves halogen, —OH, -CN can be substituted, and x is an integer of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.)
And / or formula

(However,
A is a group of the formula COOR ² , CN, CONR ² ₂ , OR ² and / or R ² , and R ² is hydrogen, a C1-C15 alkyl group, a C1-C15 alkoxy group, an ethyleneoxy group, or C5 -C20 aryl, or heteroaryl group, the above-mentioned functional groups themselves, halogen, -OH, COOZ, -CN, are those that can be substituted by NZ _2,
R is a bond, a C1-C15 alkylene group having two covalent bonds, a C1-C15 alkyleneoxy group having two covalent bonds, such as an ethyleneoxy group, or a C5-C20 aryl having two covalent bonds, or hetero An aryl group, and the above-mentioned group itself may be substituted with halogen, —OH, COOZ, —CN, NZ ₂ ;
Z, independently of one another, is hydrogen, a C1-C15 alkyl group, a C1-C15 alkoxy group, an ethyleneoxy group, or a C5-C20 aryl or heteroaryl group, and the aforementioned groups are themselves halogen, —OH, -CN can be substituted, and x is an integer of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.)
It is this compound.

  Preferred monomers containing sulfonic acid groups are, in particular, alkenes containing sulfonic acid groups, such as ethenesulfonic acid, propenesulfonic acid, butenesulfonic acid; acrylic acid compounds containing sulfonic acid groups, and / or methacrylic acid compounds, such as 2-sulfonomethylacrylic acid, 2-sulfonomethylmethacrylic acid, 2-sulfonomethylacrylamide, and 2-sulfonomethylmethacrylamide.

  Commercially available vinyl sulfonic acids (ethene sulfonic acids), which are commercially available from, for example, Aldrich or Clariant GmbH, are particularly preferred for use. Preferred vinyl sulfonic acids have a purity of more than 70%, in particular more than 90% and particularly preferably more than 97%.

  The monomer containing a sulfonic acid group can also be used in the state of a derivative. The derivative is then converted to an acid, which can also be carried out in the polymerized state. These derivatives include, in particular, salts, esters, amides and halides of monomers containing sulfonic acid groups.

  Furthermore, after hydrolysis, monomers containing sulfonic acid groups can be introduced on or into the membrane. This can be done in a manner known per se (known from the prior art) (eg spraying, dipping etc.).

  In other embodiments of the invention, crosslinkable monomers can be used. These monomers can be added to the hydrolysis fluid. Furthermore, a crosslinkable monomer can be applied to the membrane obtained after hydrolysis.

  Crosslinkable monomers are in particular compounds having at least two carbon-carbon double bonds. Diene, triene, tetraene, dimethyl acrylate, trimethyl acrylate, tetramethyl acrylate, diacrylate, triacrylate and tetraacrylate are preferred.

  Particularly preferred are the formulas

のジエン、トリエン、テトラエン、式、

Diene, triene, tetraene, formula,

のジメチルアクリレート、トリメチルアクリレート、テトラメチルアクリレート、式、

Dimethyl acrylate, trimethyl acrylate, tetramethyl acrylate, formula,

のジアクリレート、トリアクリレート、テトラアクリレート、

Diacrylate, triacrylate, tetraacrylate,

(However,
R is a C1-C15 alkyl group, a C5-C20 aryl or heteroaryl group, NR ′, —SO ₂ , PR ′, Si (R ′) ₂ , wherein the above-described groups are themselves substituted Well,
R ′ is independently of one another hydrogen, a C1-C15 alkyl group, a C1-C15 alkoxy group, a C5-C20 aryl or heteroaryl group, and n is at least 2.
It is.

  The substituent of the functional group R described above is preferably a halogen, hydroxyl, carboxy, carboxyl, carboxyl ester, nitrile, amine, silyl, or siloxane group.

  Particularly preferred crosslinking agents are allyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and polyethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, glycerol dimethacrylate, Urethane dimethacrylate, trimethylpropane trimethacrylate, epoxy acrylates such as evacryl, N ′, N-methylenebisacrylamide, carbinol, butadiene, isoprene, chloroprene, divinylbenzene and / or bisphenol A dimethyl acrylate. These compounds are commercially available, for example, under the names CN120, CN104 and CN980 from Sartomer Company Exton, Pennsylvanis.

  The use of the crosslinking agent is arbitrary, and these compounds are typically 0.05 to 30% by mass, preferably 0.1 to 20% by mass, particularly preferably 1%, based on the mass of the membrane. It can be used in the range of -10% by mass.

  It is also possible to introduce cross-linking monomers on the membrane or in the membrane after hydrolysis. This can be done in a manner known per se (known from the prior art) (eg spraying, dipping etc.).

  According to a particular aspect of the present invention, monomers containing phosphonic acid and / or sulfonic acid groups or crosslinking monomers can be polymerized, and the polymerization is preferably radical polymerization. The formation of radicals can be done thermally, photochemically, chemically and / or electrochemically.

  For example, a starter solution containing a substance capable of forming at least one group (radical) can be added to the hydrolysis solution. It is also possible to apply the starting solution to the membrane after hydrolysis. This can be done in a manner known per se (known from the prior art) (for example spraying, dipping etc.).

  Suitable group formers (radical formers) are in particular azo compounds, peroxy compounds, persulfate compounds or azoamidines. Examples (but not limited to) are dibenzoyl peroxide, dicumene peroxide, cumene hydroperoxide, diisopropyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, dipotassium persulfate, Ammonium peroxysulfate, 2,2′-azobis (2-methylpropiononitrile) (AIBN), 2,2′-azobis (isobutyric acid amidine) hydrochloride, benzopinacol, dibenzyl derivative, methyl ethyl ketone peroxide, 1,1 -Azobiscyclohexanecarbonitrile, methyl ethyl ketone peroxide, acetylacetone peroxide, dilauryl peroxide, didecanoyl peroxide, tert-butylper-2 Ethyl hexanoate, ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, 2,5-bis (2-ethylhexanoyl peroxide) -2,5 -Dimethylhexane, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxy-3,5,5-trimethylhexanoate, tert-butylperoxyisobutyrate, tert-butylperoxyacetate, dicumene peroxide, 1,1-bis (tert-butylperoxy) cyclohexane, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, Names of (registered trademark) Vazo, for example (registered trademark) Vazo V50 and (registered trademark) Vazo WS, from milhydroperoxide, tert-butylhydroheroxide, bis (4-tert-butylcyclohexyl) peroxydicarbonate and DuPont Is a group-forming agent commercially available.

  In addition, group formers that form free radicals when exposed to radiation may be used. Preferred compounds are in particular α, α-diethoxyacetophenone (DEAP, Upjon Corp), n-butylbenzoin ether (® Trigonal-14, AKZO) and 2,2-dimethoxy-2-phenylacetophenone ((Register (Trademark) Igacure 651)) and 1-benzoylcyclohexanol ((R) Igacure 184), bis- (2,4,6-trimethylbenzoyl) phenylphosphine oxide ((R) Igacure 819) and 1- [4- (2- Hydroxyethoxy) phenyl] -2-hydroxy-2-phenylpropane-1-one ((R) Igacure 2959), each of which is available from Ciba Geigy Corp. It is commercially available from the company.

  In a typical example, the monomer (which can be treated by radical polymerization; based on the mass of the monomer or crosslinking monomer containing a phosphonic acid group and / or a sulfonic acid group) is 0.0001 to 5% by mass, in particular 0.01 to 3% by mass. The group former is added. The amount of group former can vary according to the degree of polymerization desired.

  Polymerization is IR or NIR (IR = infrared, ie light with wavelength greater than 700 nm; NIR = near infrared, ie light with wavelength in the range of about 700-2000 nm and energy in the range of about 0.6-1.75 eV) This can also be done by the action of

  The polymerization can also be performed by the action of UV light having a wavelength of less than 400 nm. This polymerization method is known per se and is described, for example, in Hans Joerg Elias, Makromolekulare Chemie, 5th edition, volume 1, pp. 492-511; R. Arnold, N.M. C. Baird, J. et al. R. Bolton, J. et al. C. D. Brand, P.M. W. M Jacobs, P.M. de Mayo, W.M. R. Walle, Photochemistry-An Introduction, Academic Press, New York and M .; K. Misra, Radical Photopolymerization of Vinyl Monomers, J. et al. Macromol. Sci. -Revs. Macromol. Chem. Phys. C22 (1982-1983) 409.

  The polymerization may be performed by exposure to β rays, γ rays, and / or electron beams. According to a particular embodiment of the invention, the membrane is irradiated with a radiation dose in the range 1 to 300 kGy, preferably 3 to 200 kGy, and very preferably 20 to 100 kGy.

  Polymerization of monomers containing phosphonic acid groups and / or sulfonic acid groups, or cross-linking monomers is carried out at temperatures above room temperature (20 ° C.) and below 200 ° C., in particular temperatures from 40 ° C. to 150 ° C., particularly preferably 50 ° C. It is preferably performed at a temperature of ˜120 ° C. The polymerization is preferably carried out at standard pressure, but can also be carried out under the action of pressure. Polymerization results in solid structure solidification, which can be observed by measuring microhardness. Preferably, the increase in hardness due to polymerization is at least 20% relative to the correspondingly hydrolyzed membrane hardness without polymerization of the monomers.

  According to a particular aspect of the invention, the molar sum of phosphoric acid, polyphosphoric acid and hydrolysis products of polyphosphoric acid (obtained by polymerization of monomers containing phosphonic acid groups and / or monomers containing sulfonic acid groups) The molar ratio (molar ratio) with respect to the number of moles of phosphonic acid groups and / or sulfonic acid groups in the polymer is preferably 1: 2 or more, particularly 1: 1 or more, and particularly preferably 2: 1 or more.

  Preferably, the phosphonic acid groups in the polymer (obtained by the polymerization of monomers containing phosphonic acid groups and / or monomers containing sulfonic acid groups) of the molar sum of phosphoric acid, polyphosphoric acid and hydrolysis products of polyphosphoric acid and The molar ratio (molar ratio) with respect to the number of moles of sulfonic acid groups is in the range of 1000: 1 to 3: 1, in particular in the range of 100: 1 to 5: 1, particularly preferably in the range of 50: 1 to 10: 1 It is.

  The molar ratio can be measured by a usual method. For this purpose, it is possible in particular to use spectroscopy, for example NMR spectroscopy. In this regard, it is believed that the phosphonic acid group has an apparent oxidation stage of 3, and phosphorous, polyphosphoric acid or phosphorus in these hydrolysates has an oxidation stage of 5, respectively.

Depending on the desired degree of polymerization, the flat structure obtained after polymerization is a self-supporting film. Preferably, the degree of polymerization is at least 2 repeat units, in particular at least 5, particularly preferably at least 30, in particular at least 50, very particularly preferably at least 100 repeat units. The degree of polymerization is measured (determined) by the number average molecular weight M _n , which can be measured by the GPC method. Due to the problem of separating (without degrading) the polymer containing phosphonic acid groups contained in the membrane, this value was obtained (by polymerizing monomers containing phosphonic acid groups without adding polymer). Measured using a sample. Here, the mass proportion of the monomer containing the phosphonic acid group and the radical starter is kept constant (compared to the membrane production rate). The conversion achieved in the comparative polymerization is preferably at least 20%, in particular at least 40%, and particularly preferably at least 75%, based on the monomer containing phosphonic acid used.

  The hydrolysis fluid contains water, and the concentration of water is usually not particularly critical (critical). According to a particular aspect of the invention, the hydrolysis fluid comprises 5 to 80% by weight, preferably 8 to 70% by weight and particularly preferably 10 to 50% by weight of water. The amount of water contained in the apparently oxoacid is not considered in the water content of the hydrolysis fluid.

  Of the acids mentioned above, phosphoric acid and / or sulfuric acid are particularly preferred, and these acids comprise in particular 5 to 70% by weight, preferably 10 to 60% by weight and particularly preferably 15 to 50% by weight of water. .

  The partial hydrolysis of the polyphosphoric acid in step D) results in the solidification of the membrane through a sol-gel transition. This also leads to a reduction of the layer thickness to 15-3000 μm, preferably 20-2000 μm, in particular 20-1500 μm (the film is self-supporting).

  The intermolecular and intermolecular structure (interpenetrating network IPN) present in the polyphosphoric acid according to step B) leads to the formation of an ordered membrane in step C), depending on the specific properties of the membrane formed. .

  The upper temperature limit for the treatment according to step D) is typically 150 ° C. Under very short action of water, for example from superheated steam, this steam can be higher than 150 ° C. The duration of the treatment is substantially for the upper temperature limit.

  Partial hydrolysis (step D) can also be carried out in a climate chamber and the hydrolysis can be controlled to a specific state under the action of defined moisture. In this regard, moisture (moisture) is set to a specific state by temperature or the surrounding area in contact with it, for example the saturation of a gas such as air, nitrogen, carbon dioxide or other suitable gas or vapor. Can do. The duration of the treatment depends on the parameters chosen as described above.

  Furthermore, the duration of the treatment depends on the thickness of the film.

  Typically, the duration of the treatment is from a few seconds to a few minutes, for example by applying superheated steam, or up to several days, for example in air open at room temperature and at relatively low humidity. Preferably, the duration of the treatment is from 10 seconds to 300 hours, in particular from 1 minute to 200 hours.

  When partial hydrolysis is performed at room temperature (20 ° C.) and in an atmosphere with a relative humidity of 40-80%, the duration of the treatment is 1-200 hours.

  The membrane obtained according to step D) can be formed such that the membrane is self-supporting, i.e. the membrane can be removed from the support without any damage, and in some cases Processed directly.

  The concentration of phosphoric acid, and thus the conductivity of the polymer membrane, can be set by the degree of hydrolysis (ie, duration, temperature, and environmental humidity). The concentration of phosphoric acid is given as moles of acid per mole of polymer repeating units. A membrane with a particularly high concentration of phosphoric acid can be obtained by a method comprising steps A) to D). Concentrations of 10 to 50 (formula (I), for example, moles of phosphoric acid relative to one repeating unit of polybenzimidazole), in particular 12 to 40 are preferred. By doping polyazoles using commercially available orthophosphoric acid, it is extremely difficult or impossible to obtain such a high degree of doping (concentration).

In one variation of the method described herein in which doped polyazole films are produced using polyphosphoric acid, the production of these films comprises the following steps:
1) One or more aromatic tetraamino compounds, one or more aromatic carboxylic acids, or esters thereof (which contain at least two acidic groups per carboxylic acid monomer), or one or more aromatics Reacting with a group and / or heterocyclic diaminocarboxylic acid in a melt at a temperature up to 350 ° C., preferably up to 300 ° C.,
2) A step of dissolving the solid prepolymer obtained in step 1) in polyphosphoric acid,
3) heating the solution obtained in step 2) to a temperature up to 300 ° C., preferably up to 280 ° C. in the presence of an inert gas, to form a dissolved polyazole polymer;
4) A step of forming a membrane on a support using the polyazole polymer solution according to step 3), and 5) A step of treating the membrane formed in step 4) until the membrane becomes self-supporting. ,
Can be performed using a method comprising:

  The steps described under numbers 1) to 5) are those described above for steps A) to D) and are particularly referred to in view of the preferred embodiment.

  Membranes, in particular membranes based on polyazoles, can also be crosslinked on the surface by the action of heat in the presence of atmospheric oxygen. This curing of the membrane surface further improves the properties of the membrane. For this purpose, the membrane can be heated to a temperature of at least 150 ° C., preferably at least 200 ° C., and particularly preferably at least 250 ° C. In this method step, the oxygen concentration is usually 5 to 50% by volume, preferably 10 to 40% by volume, but is not limited thereto.

  Cross-linking is IR or NIR (IR = infrared, ie light with a wavelength above 700 nm; NIR = near infrared, ie light with a wavelength in the range of about 700-2000 nm and energy in the range of about 0.6-1.75 eV) This can also be done by the action of Another method is β-ray irradiation. For this, the irradiation dose is 5 to 200 kGy.

  Depending on the desired degree of crosslinking, the duration of the crosslinking reaction can vary widely. Usually, the reaction time is in the range of 1 second to 10 hours, preferably in the range of 1 minute to 1 hour, but is not limited thereto.

  Particularly preferred polymer membranes exhibit high performance. This is because, in particular, the proton conductivity is improved. This is at least 1 mS / cm, preferably at least 2 mS / cm, in particular at least 5 mS / cm at 120 ° C. Here, these values are achieved without moistening. Thus, the membrane is suitable as a so-called high temperature, polymer electrolyte membrane fuel cell, and for producing high temperature membrane electrode assemblies. The high temperature proton conductivity described above is (i) a basic polymer membrane or matrix, and an acid that allows a so-called “Grott mechanism”, or (ii) a polymer having a covalent bond group that allows a so-called “Grott mechanism”. Achieved by a proton conducting polymer electrolyte membrane, including a material, and a matrix. In the latter case, this is typically achieved by introducing at least 10% by weight of a polymer derived from the above-mentioned monomers containing phosphonic acid groups.

  Specific conductivity is measured using impedance spectroscopy and a platinum electrode (wire, 0.25 mm diameter) within a 4-pole array in constant potential mode. The gap between the current-collecting electrodes is 2 cm. The resulting spectrum is evaluated using a simple model consisting of a parallel array of ohmic resistors and capacitors. The cross section of the sample of the membrane doped with phosphoric acid is measured immediately before mounting the sample. To measure temperature dependence, the measurement cell is brought to the desired temperature in the furnace and adjusted using a Pt-100 thermocouple placed in close proximity to the sample. When the temperature is reached, the sample is maintained at this temperature for 10 minutes before starting the measurement.

Gas Diffusion Layer The membrane electrode assembly according to the present invention has two gas diffusion layers separated by a polymer electrolyte membrane. A mechanically stable material (which does not need to be very light and conductive, but is mechanically stable and includes a faver, for example in the form of a nonwoven fabric, paper or woven fabric), Used as starting material for the gas diffusion layer according to the invention. These include, for example, paper imparted conductivity by adding graphite-fiber paper, carbon-fiber paper, graphite fabric and / or carbon black. With these layers, a fine dispersion of gas and / or liquid is achieved.

The mechanical stabilizing material preferably comprises carbon fibers, glass fibers or fibers (in small amounts) containing organic polymers such as polypropylene, polyester (polyethylene terephthalate), polyphenylene sulfide or polyether ketone. In this regard, the unit weight per area of <150 g / m ^2, preferably in the range mass per unit area of 10 to 100 g / m ² material, is particularly suitable.

  When a carbon material is used as a stabilizing material, a nonwoven fabric composed of carbonized or graphitized fibers and having a mass per unit area within a preferred range is particularly suitable. There are two advantages to using such materials: first, they are light, and second, they have a high open porosity. The open porosity of the stabilizing materials preferably used is in the range of 20-99.9%, preferably in the range of 40-99%, so that they can be easily filled with other materials. And the conductivity and hydrophobicity of the finished gas diffusion layer can be adjusted in a desired manner (over the entire thickness of the gas diffusion layer).

  Usually, the thickness of this layer is in the range from 80 μm to 2000 μm, in particular in the range from 100 μm to 1000 μm, and particularly preferably in the range from 150 μm to 500 μm.

  The production of the gas diffusion layer or gas diffusion electrode is described in detail, for example, in WO 97/20358. The manufacturing methods described therein are also part of the present invention.

  In order to reduce the surface tension, materials (additives or detergents) can be added as described in WO 97/20358. Additionally, the hydrophobicity of the gas diffusion layer can be set by using a perfluorinated polymer together with a non-fluorinated binder. The provided gas diffusion layer is then dried and thermally post-treated by sintering at temperatures above 200 ° C.

  Furthermore, the gas diffusion layer can be composed of several layers. In a preferred embodiment of the gas diffusion layer, it has at least two distinct layers. Four layers are conceivable as the upper limit of the plurality of gas diffusion layers. If more layers are used, it is convenient to use a compression or lamination process to form an intimate bond between these layers, preferably at elevated temperatures. By using a multi-layer gas diffusion layer, a pre-trim layer (a pre-arranged layer) can be produced, thereby setting an effective porosity and / or hydrophobic gradient. Such a gradient can be formed by several successive coating or impregnation steps, but this is typically more elaborate to do.

  According to certain embodiments, the at least one gas diffusion layer can comprise a compressible material. Within the scope of the present invention, compressible materials have the property that the gas diffusion layer can be compressed to half the original thickness (particularly one third) without compromising its quality. Characterized.

The gas diffusion layer according to the invention has a low electrical surface resistance in the range of <100 mOhm per cm ² , preferably <60 mOhm per cm ² .

  This property is usually provided by a gas diffusion layer made of graphite fabric and / or graphite paper that has been rendered conductive by the addition of carbon black. A gas diffusion layer is usually optimized for its hydrophobicity and mass transfer properties by adding additional materials. In this regard, the gas diffusion layer comprises a fluorinated or partially fluorinated material, such as PTFE.

Catalyst layer The catalyst layer (including the case of a plurality of layers) contains a catalytically active substance. These include in particular the platinum group noble metals, ie Pt, Pd, Ir, Rh, Os, Ru, or the noble metals Au and Ag. Furthermore, the metal alloys described above may also be used. In addition, the at least one catalyst layer may comprise a platinum group element and a non-noble metal such as an alloy such as Fe, Co, Ni, Cr, Mn, Zr, Ti, Ga, V. Furthermore, the above-mentioned noble metals and / or oxides of non-noble metals can also be used.

  Catalytically active particles comprising the substances mentioned above may be used as metal powders, in particular platinum and / or platinum alloys, so-called black noble metals. Such particles usually have a particle size (size) in the range of 5 nm to 200 nm, preferably in the range of 7 nm to 100 nm. So-called nanoparticles can also be used.

Furthermore, the metal can also be used on a support material. Preferably, the support comprises carbon that may be used in particular in the form of carbon black, graphite or graphitized carbon black. In addition, conductive metal oxides such as SnO _x , TiO _x , or phosphates such as FePO _x , NbPO _x , Zr _y (PO _x ) _z can also be used as support materials. Here, the symbols x, y and z indicate the oxygen or metal content of the individual compounds, which content is in the known range (since transition metals can take different oxidation stages). Is possible.

  The content of these metal particles on the support is usually 1 to 80% by weight, preferably 5 to 60% by weight, and particularly preferably 10 to 50% by weight, based on the total weight of the bond between the metal and the support. %, But not limited to these ranges. The particle diameter of the support, particularly the carbon particle diameter, is preferably in the range of 20 to 1000 nm, particularly in the range of 30 to 100 nm. The particle size of the metal particles present thereon is preferably in the range from 1 to 20 nm, in particular in the range from 1 to 10 nm, and particularly preferably in the range from 2 to 6 nm.

  The particle size (size) of the various (different) particles represents an average value and can be measured by transmission electron microscopy or X-ray powder diffraction.

  The catalytically active particles described above are usually commercially available.

  In addition to commercially available catalysts or catalyst particles, catalyst nanoparticles made of platinum-containing alloys, in particular catalyst nanoparticles based on Pt, Co and Cu or Pt, Ni and Cu (where the particles are in the outer shell) , Having a higher concentration of Pt than in the nucleus) can also be used. Such particles are P.I. Strasser et al. in Angewante Chemie 2007.

  In addition, the catalytically active layer may contain conventional additives. These include in particular fluoropolymers such as polytetrafluoroethylene (PTFE), proton conducting ionomers and surfactants.

  According to a particular embodiment of the invention, the ratio of fluoropolymer to catalyst material (including at least one noble metal and optionally one or more support materials) is greater than 0.1, this ratio Is in the range of 0.2 to 0.6.

  According to a particular embodiment of the invention, the catalyst layer has a thickness in the range of 1-1000 μm, in particular 5-500 μm, preferably 10-300 μm. This value can be obtained by averaging layer thickness measurements measured from photographs obtained using a scanning electron microscope (SEM).

According to a particular embodiment of the invention, the noble metal content of the catalyst layer is 0.1 to 10.0 mg / cm ² , preferably 0.3 to 6.0 mg / cm ² , and particularly preferably 1 it is a ~4.0mg / cm ^2. This value can be obtained by elemental analysis of a flat sample.

  It is preferred that the ionomeric material according to the invention present on the catalyst layer at the cathode is present in a predetermined proportion with respect to the catalyst material. Accordingly, the mass ratio between the ionomeric material and the catalyst is preferably 100: 1 to 1: 100, most preferably 10: 1 to 1:10. A specific preferred ratio is 1: 8 to 1: 3. These amounts and proportions also apply to the catalyst layer at the anode, if desired.

  The catalyst layer is usually not self-supporting and is usually applied to the gas diffusion layer and / or membrane. Here, a part of the catalyst layer can be diffused into, for example, a gas diffusion layer and / or a film, and as a result, a transition layer can be formed. In this regard, it can also be understood that the catalyst layer is part of the gas diffusion layer. The thickness of the catalyst layer is determined by measuring the thickness of the layer on which the catalyst layer is applied, for example, the gas diffusion layer, or the membrane (by the measurement, the total of the layers corresponding to the catalyst layer, for example, the gas diffusion layer The total of the layers is obtained). The catalyst layer preferably has a gradient, i.e. the content of noble metal increases in the direction of the membrane and the content of hydrophobic material behaves contrary to this.

  For further information on membrane electrode assemblies, reference is made to the technical literature, in particular the patent documents WO 01/18894 A2, DE 1950748, DE 19509749, WO 00/26982, WO 92/15121 and DE 19757492. Disclosures contained in the above-mentioned literature on the structure and manufacture of membrane electrode assemblies and electrodes, selected gas diffusion layers and catalysts are part of this description.

Gaskets The gaskets used or produced within the method according to the invention can also be manufactured and applied in a separate process, or else the peripheral edge (and surrounding, optionally of the gas diffusion layer) It can also be produced directly on the end of a bipolar plate.

  In this regard, mainly the formed structural inner boundary region overlaps inward and thus overlaps with the outer boundary region of the gas diffusion layer or the gas diffusion layer provided with the catalyst layer. This overlap secures the gas diffusion layer to the bipolar plate, thereby eliminating the need for further mounting or fixing frames. Furthermore, it is not necessary to interspace the boundary region of the gas diffusion layer with a sealing material, or it is not necessary to penetrate the sealing material into the boundary region of the gas diffusion layer to obtain a sealing function.

  Furthermore, it is advantageous that the gasket has sufficient mechanical stability and / or integrity and that, for example, the gas diffusion layer and / or the membrane / electrolyte matrix are not damaged in the subsequent compression step. For this purpose, a so-called hard stop function may be integrated into the gasket in an advantageous manner. This embodiment is particularly preferred when the gakket is manufactured on a bipolar plate (without raising the edges).

  The production of the gasket can be done in a separate process, or else the gasket can be produced directly on the peripheral edge of the gas diffusion layer, towards the bipolar plate. The formation of the gasket can be carried out using all known methods, preferably by applying a thermoplastic elastomer or a crosslinkable rubber by spraying and / or crosslinking them using printing methods. Can be performed.

  Preferably, the gasket according to the invention is formed from a meltable polymer or a thermally processable rubber.

  Among the rubbers, silicone rubber (Q), ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPM), isobutylene-isoprene rubber (IIR), butadiene rubber (BR), styrene-butadiene rubber (SBR), Styrene-isoprene rubber (SIR), isoprene-butadiene rubber (IBR), isoprene rubber (IR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), acrylate rubber (ACM) and / or butadiene rubber (BR), Styrene-butadiene rubber (SBR), isoprene-butadiene rubber (IBR), isoprene rubber (IR), acrylonitrile-butadiene rubber (NBR), polyisobutylene rubber (PIB), fluoro rubber (FPM), fluorosilicone rubber ( FQ, preferably partially hydrogenated rubber from FVMQ).

  In addition, fluoropolymers can be used as sealing materials, preferably poly (tetrafluoroethylene-co-hexafluoropropylene) FEP, polyvinylidene fluoride PVDF, perfluoroalkoxy polymer PFA, and poly (tetrafluoroethylene- Co-perfluoro (methyl vinyl ether)) MFA can be used. These polymers are often marketed, for example, under the names Hostafoon®, Hyflon®, Teflon®, Dyneon®, Nowoflon®.

  Apart from the materials mentioned above, sealing materials based on polyamide can also be used. In addition to imide groups, the class of polymers based on polyimide also includes polymers containing amides (polyamideimide), esters (polyesterimide) and ether groups (polyetherimide) as backbone components.

  Preferred polyimides are those of formula (VI),

(However, the functional group Ar has the above-mentioned meaning, and the functional group R represents an alkyl group or an aromatic or heterocyclic aromatic group having 1 to 40 carbon atoms and having two covalent bonds. )
Of repeating units. Preferably, the functional group R is derived from benzene, naphthalene, biphenyl, diphenyl ether, diphenyl ketone, diphenylmethane, diphenyldimethylmethane, bisphenone, diphenylsulfone, quinoline, pyridine, bipyridine, anthracene, thiadiazole, and phenanthrene, optionally substituted Represents an aromatic or heteroaromatic group having two possible covalent bonds. The index n means that the repeating unit indicates a part of the polymer.

  Such polymers are (registered trademark) Kapton from DuPont, (registered trademark) Vespel, (registered trademark) Toray and (registered trademark) Pyralin, (registered trademark) Ultem from GE Plastics, and (registered trademark) from Ube Industries. (Trademark) It is marketed under the name Upilex.

  The combination of material properties described above, the combination of soft / hard, is also suitable as a sealing material (especially when the hard stop function described above is integrated).

  Particularly preferred sealing materials have a Shor A hardness of 5 to 85, in particular 25 to 80. Shor A hardness is measured according to DIN 53505. Furthermore, it is advantageous that the permanent set of the sealing material is less than 50%. The permanent set is measured according to DINISO 815.

  The thickness of the gasket is affected by several factors. An important factor is how much to choose the elevation of the boundary region of the bipolar plate. The thickness of the gasket is usually formed or applied in the range of 5 to 5000 μm, preferably 10 μm to 1000 μm, and especially 25 μm to 150 μm. In particular, in the case of a bipolar plate that does not have a raised (raised) boundary region, the thickness can be increased.

  The gasket can be composed of a plurality of layers. In this embodiment, different layers are bonded together using a suitable polymer (especially a fluoropolymer is suitable to form a suitable linkage). Suitable fluoropolymers are known to those skilled in the art. These include in particular polytetrafluoroethylene (PTFE) and poly (tetrafluoroethylene-co-hexafluoropropylene) (FEP). The layer made of fluoropolymer present on the sealing layer described above is usually at least 0.5 μm thick, in particular at least 2.5 μm. When an expanded fluoropolymer is applied, the layer thickness is 5-250 μm, preferably 10-150 μm.

  The gasket or sealing material described above fixes the gas diffusion layer in a recess formed with the bipolar plate. For this purpose, it is advantageous for the gasket to overlap the outer boundary region of the gas diffusion layer at the periphery. The overlap between the gasket and the boundary region of the gas diffusion layer is preferably 0.1-5 mm, preferably 0.1-3 mm, based on the outermost end of the gas diffusion layer. Larger overlaps are possible, but the catalytically active surface is greatly impaired. For this reason, the degree of overlap should be balanced in a critical way, thereby covering an unnecessary excess of the catalytically active surface.

  It is advantageous for the gasket to overlap the boundary region of the gas diffusion layer at the periphery, however, there is a discontinuity (especially for the active catalyst surface) at the overlap of the peripheral sealing edge and the boundary region of the gas diffusion layer. It can also exist. In this regard, the function of fixing the gas diffusion layer is still ensured by the gasket.

Bipolar plate The bipolar plate or separator plate used in the present invention is typically a process for the distribution of reactants and other fluids (typically for fuel cells) such as cooling fluids. A media channel (process media channel) is provided.

  Bipolar plates are typically formed from conductive materials; these may be metallic or non-metallic materials.

  When the bipolar plate is made of a non-metallic material, a so-called composite material is preferable. The composite material is a composite made of a matrix material provided with a conductive filler. Polymeric materials, in particular organic polymers, are preferred and suitable as the matrix material. Depending on the operating temperature of the fuel cell, a high-performance polymer, especially a thermally stable polymer, may be required. Depending on the field used, polymers are used whose long-term use temperature is at least 80 ° C., preferably at least 120 ° C., particularly preferably at least 180 ° C.

  It is particularly preferred to use thermoplastics, especially polypropylene (PP), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), and liquid crystalline polymer (LCP). Can also be used as compounds, ie, can be mixed with each other polymer and typical additives, respectively. In addition to thermoplastics, thermosetting plastics and resins are also preferred. In particular, phenol resin (PF), melanin resin (MF), polyester (UP), and epoxy resin (EP) are used.

  Particulate materials that allow as uniform a dispersion as possible in the matrix are used as conductive fillers. Preferably, these fillers have a bulk conductivity of at least 10 mS / cm. Particular preference is given to using carbon, graphite and carbon black. These can also be processed to make the wettability with the matrix material better. There is no particular restriction on the size (diameter) of the particles, but it is necessary to allow the production of such a bipolar plate. Apart from the conductive fillers described above, other additives that improve the application properties can also be added to the matrix material. Fiber reinforcement is also possible, especially if mechanical attachment cannot be ensured otherwise.

  The production of such bipolar plates is preferably carried out using suitable forming methods, in particular using injection molding techniques and injection embossing and embossing techniques.

  In addition to the process medium duct, the bipolar plate can also have further ducts or openings or bores through which, for example, coolants or reaction gases can be supplied and discharged.

  The thickness of the nonmetallic bipolar plate is preferably in the range of 0.2 to 1.0 mm, in particular in the range of 0.5 to 5 mm, and particularly preferably in the range of 0.5 to 2 mm. The conductivity of the nonmetallic bipolar plate is 25 S / cm or more.

  If the bipolar plate is made of a metallic material, a more economical integrated design is possible. Such a bipolar plate configuration is not subject to any substantial limitation.

  Corrosion and acid resistant steels are preferred as metallic materials, particularly those based on V2A and V4A steels and those made of nickel based alloys. More preferred are plated or coated metals, particularly those having a corrosion-resistant surface made of noble metals, nickel, ruthenium, niobium, tantalum, chromium, carbon, and metals coated with ceramic materials, especially CrN, TiN, Those having coatings made of iAlN, complex nitrides, carbides, silicides and oxides of metals and transition metals are preferred.

  Apart from these, metallic bipolar plates additionally reduce, on the one hand, the electrical surface resistance of the contact of the gas diffusion layer / bipolar plate, or else in the fuel cell of the bipolar plate. It is possible to have a coating that increases the chemical and / or physical resistance to the medium present or formed.

  The metal bipolar plate can be constructed from individual plates. Voids (holes) for the coolant or reaction medium to be fed and discharged can be formed in a simple manner. The connection of the individual plates can be made by a material bonding method, for example by welding or soldering. If necessary, the voids can additionally be sealed to one another, for example using a further inner coating in which leakage is avoided.

  If a fuel electronic system is constructed that does not have a cooling layer, or if several individual cells (cells) of the fuel cell stack do not require cooling, a bipolar plate or individual bipolar in the stack The plate may be manufactured from only one metallic or non-metallic individual plate.

  The construction and manufacture of suitable bipolar plates are described in DE-A-10250991, WO 2004/036677, WO 2004/105164, WO 2005/081614, WO 2005/096421 and WO 2006/037661. The assemblies and manufacturing methods described in these documents are also part of the present invention and description.

  The thickness of the metallic bipolar plate is preferably in the range of 0.03 to 1 mm, in particular in the range of 0.05 to 0.5 mm, and particularly preferably in the range of 0.05 to 0.15 mm.

  Bipolar plates used within the scope of the present invention may have a raised boundary region, so that the region of the bipolar plate containing the flow region channels forms a recessed portion. Also good. For the highest rise in the area of the bipolar plate with the process medium channel, the exact height of the boundary area applies to the thickness of the gas diffusion layer or the gas diffusion layer with the catalyst layer. If the gas diffusion layer or the gas diffusion layer with the catalyst layer is not subjected to any further compression during the next compression step, the rise (height) of the boundary region of the bipolar plate is the gas diffusion layer or the catalyst layer. This corresponds to the thickness of the gas diffusion layer having

  If the thickness of the gas diffusion layer, or the gas diffusion layer with the catalyst layer, is higher than the height of the boundary region (relative to the highest rise with the bipolar plate process medium), during the next compression step, Compression of the gas diffusion layer occurs. The degree of compression is determined via the thickness and deformability of the sealing material, where the sealing material functions as a hard stop. This embodiment is particularly advantageous when a flexible or easily deformable polymer electrolyte membrane is used (since membrane damage can be avoided).

  In the design of the rising part of the boundary region, or the rising part design using a frame-forming component, the gas diffusion layer or the gas diffusion layer with the catalyst layer is at least 3% compared to the original (initial) thickness. It has proved advantageous to be subjected to compression. Particularly preferably, the above-mentioned rise of the border region is selected such that the compression is at least 5%. Compression above 50%, in particular compression above 30%, is selected as the upper limit, but it is possible to exceed this upper limit via other parameters.

  The compression of the components is effected by the action of pressure and temperature, thereby forming an intimate connection of the components. Usually, this compression is carried out at a temperature in the range of 10 to 300 ° C., in particular in the range of 20 ° C. to 200 ° C., and a pressure in the range of 1 to 1000 bar, in particular 3 to 300 bar. The compression described above can also be performed during stack manufacture and / or when starting up (starting up) the fuel cell stack. After this, individual cells (cells) for electrochemical cells, in particular fuel cells, can be operated and used. In order to produce a fuel cell stack, the individual cells (cells) that make up the fuel cell are arranged as a stack. Furthermore, the production of the fuel cell stack can be carried out using semi-finished components according to the invention, which can also be provided in advance on the required membrane. In this regard, the membrane can be pre-used, for example as a rolled article, and can be cut individually (using minimal material) to apply to each bipolar plate design. . There is no need to add a handling frame. The production of fuel cell stacks from individual cells for fuel cells is usually known.

  The electrode and membrane electrode assembly according to the present invention provides a polymer comprising fluorine and simultaneously containing imino groups (allowing adsorption of phosphoric acid) as described in the examples below. When this is used as an ionomer coated on an electrode, a considerably large oxygen reduction current is obtained. Thus, electrode overvoltage is reduced and fuel cell voltage is increased. Although not tied to a specific scientific model, this effect is explained by the following facts: That is, it is explained by the fact that inclusion of fluorine in the polymer structure increases its oxygen solubility. The present invention makes it clear that the method of adding or coating such a fluorine-containing polymer to the cathode is an effective means of improving fuel cell performance.

Polymer Production Procedure Polymer 1: Polybenzimidazole (PBI)
Poly (2,2′-m-phenylene-5,5′-bibenzimidazole) from BASF Fuel Cell GmbH was used as the base polymer for comparison.

Polymer 2: Fluorine-containing polymer 1
4,4 ′-(Hexafluoroisopropylidene) dibenzoic acid shown in Formula 1 (Formulation 1) was used as the dicarboxylic acid, and 3,3′-diaminobenzidine tetrahydro shown in Formula 2 (Formulation 2) Chloride was used as a monomer containing an amino group. Under a nitrogen atmosphere, the reaction was carried out using polyphosphoric acid (117% phosphoric acid) as a reaction solvent at 170 ° C. for 12 hours and further at 220 ° C. for 90 hours. The reaction mixture became thicker. The precipitate was collected by pouring the reaction mixture into a large volume of water and filtering. The precipitate was placed in boiling water and refluxed for 24 hours to remove the solvent polyphosphoric acid. Infrared spectroscopy is a 1663Cm ^-1, an absorption at imino (C = N), and in 3400～2600Cm ^-1, an absorption of the imidazole ring was confirmed molecular structure 1. The molecular weight was measured by GPC (gas permeation chromatography) using PEO as internal standard material. Based on the measurement results, the number average molecular weight M _n was 6.0 × 10 ⁴ and the mass average molecular weight M _w was 31 × 10 ⁴ . This polymer was soluble in organic solvents such as dimethylacetylamide and NMP (N-methylpyrrolidone). After spreading a 5 wt% solution of the polymer on a glass plate and removing the solvent by heating, a strong brown film was finally obtained. It was confirmed that by immersing in 85% phosphoric acid for 1 hour at 40 ° C., the film can be converted to a gel film containing 75-80% by mass phosphoric acid.

Polymer 3: Fluorine-containing polymer 2
4,4′-Oxybis [benzoic acid] shown in Formula 3 (Formulation 3) was used as the dicarboxylic acid and 2,2-bis (3-amino-4-hydroxy shown in Formula 4 (Formulation 4) Phenyl) hexafluoropropane dihydrochloride was used as the amino group-containing monomer. Under a nitrogen atmosphere, the reaction was carried out using polyphosphoric acid (117% phosphoric acid) as a reaction solvent at 170 ° C. for 4 hours and further at 203 ° C. for 34 hours. The reaction mixture became thicker. The precipitate was collected by pouring the reaction mixture into a large volume of water and filtering. The precipitate was placed in boiling water and refluxed for 24 hours to remove the solvent polyphosphoric acid. Infrared spectroscopy is a 1599Cm ^-1, an absorption at imino (C = N), and in 3400～2600Cm ^-1, an absorption of the imidazole ring, and at 1246cm ^-1, absorption of C-O-C The molecular structure 2 was confirmed. The molecular weight was measured by GPC (gas permeation chromatography) using PEO as internal standard material. Based on the measurement results, the number average molecular weight M _n was 0.57 × 10 ⁴ and the mass average molecular weight M _w was 1.7 × 10 ⁴ . This polymer was soluble in organic solvents such as acetamide and NMP (N-methylpyrrolidone). After spreading a 5 wt% solution of the polymer on a glass plate and removing the solvent by heating, a brown hard film was finally obtained. It was confirmed that by immersing in 85% phosphoric acid for 1 hour at 40 ° C., the film could be converted to a gel film containing 50-60 mass% phosphoric acid.

Polymer 4: Fluorine-containing polymer 3
Sebacic acid shown in Formula 5 (Formulation 5) was used as the dicarboxylic acid, and 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane dihydrochloride shown in Formula 6 (Formulation 6) was used. And used as an amino group-containing monomer. Under a nitrogen atmosphere, the reaction was carried out using polyphosphoric acid (117% phosphoric acid) as a reaction solvent at 130 ° C. for 1 hour and further at 180 ° C. for 24 hours. The reaction mixture became thicker. The precipitate was collected by pouring the reaction mixture into a large volume of water and filtering. The precipitate was placed in boiling water and refluxed for 24 hours to remove the solvent polyphosphoric acid. Infrared spectroscopy is a 1629Cm ^-1, an absorption at imino (C = N), and in 3400～2600Cm ^-1, an absorption of the imidazole ring was confirmed molecular structure 3. This polymer was soluble in organic solvents such as dimethylacetylamide and NMP (N-methylpyrrolidone). After spreading a 5 wt% solution of the polymer on a glass plate and removing the solvent by heating, a brown hard film was finally obtained. It was confirmed that by immersing in 85% phosphoric acid for 1 hour at 40 ° C., the film can be converted into a gel film containing 70-75% by mass phosphoric acid.

式２（処方２）

Formula 2 (Prescription 2)

式１（処方１）

Formula 1 (Formulation 1)

分子構造１

Molecular structure 1

式３（処方３）

Formula 3 (Prescription 3)

式４（処方４）

Formula 4 (Prescription 4)

分子構造２

Molecular structure 2

式５（処方５）

Formula 5 (Formulation 5)

分子構造３

Molecular structure 3

Electrochemical measurement a) Production of electrode In order to measure the electrochemical oxygen reduction activity of the electrode containing the polymer described above, a half cell measurement was performed. A porous Pt-carbon electrode (0.5 mg / cm ² Pr loading) was used as a reference and counter electrode. As an electrolyte, a polybenzimidazole film doped with phosphoric acid (80% by mass, 85% by mass phosphoric acid was used) was used. Pt mesh electrodes (1 cm ² geometric region) are dipped in 3 to 3% by mass dimethylacetamide solution. A working electrode was then produced by evaporating the solution. Table 1 quantifies and shows the resulting polymer coating.

表１：操作電極上のポリマー被覆物の質量

Table 1: Mass of polymer coating on working electrode

b) Electrochemical measurements Electrochemical measurements were made by pressing the counter / reference electrode, the acid loaded PBI membrane, and the working electrode between two graphite plates with gas inlet / outlet. The measurement was performed at 140 ° C. The counter / reference electrode was continuously purged with hydrogen. The operating electrode was continuously purged with 0.4 L / min pure oxygen or air (fast rate to ensure near zero gas use). The activity of the electrodes at 0.7 V and 140 ° C. (ambient pressure) is summarized in Table 2.

表２：本発明からの電極の酸素還元活性（この表では、還元電流は、正の電流として示されている）

Table 2: Oxygen reduction activity of electrodes from the present invention (in this table the reduction current is shown as a positive current)

Claims (18)

(I) comprising at least two electrochemically active electrodes;
(Ii) the electrodes are separated by at least one polymer electrolyte membrane or electrolyte matrix;
(Iii) the electrode has a catalyst layer in contact with the polymer electrolyte membrane or matrix;
(Iv) the catalyst layer comprises at least one ionomeric material;
A membrane electrode assembly comprising:
At least the catalyst layer in contact with the cathode is a general formula (I)

(However, (a)
Ar is the same or different and is an aromatic group having four covalent bonds, or a heterocyclic aromatic group having four covalent bonds, each of which is monocyclic, bicyclic, or polycyclic Cyclic is possible and X is the same or different and represents N, O, S, and R ¹ is the same or different, and the formula

A group having two covalent bonds, and Ar ¹ and Ar ² are the same or different, and an aromatic group having two covalent bonds, or a heterocyclic aromatic group having two covalent bonds Each represents a monocyclic, bicyclic, or polycyclic group, and
Z ¹ is the same or different and represents a divalent alkyl group and / or a divalent aromatic group, both of which at least one hydrogen atom is replaced by a fluorine atom, and n is 0.1 to 99.9 mol-%,
Or (b)
Ar is the same or different and has the formula

Represents a group having four covalent bonds,
Ar ³ and Ar ⁴ are the same or different and each represents an aromatic group having three covalent bonds or a heterocyclic aromatic group having three covalent bonds, each of which is monocyclic or bicyclic Can be of formula or polycyclic, and
Z ² is the same or different and represents a divalent alkyl group and / or a divalent aromatic group, both of which at least one hydrogen atom is replaced by a fluorine atom, and X is the same or different and represents N, O, S, and R ¹ is the same or different and (i)

A group having two covalent bonds, and Ar ⁵ and Ar ⁶ are the same or different, and an aromatic group having two covalent bonds, or a heterocyclic aromatic group having two covalent bonds Each represents a monocyclic, bicyclic, or polycyclic group, and Z ³ is the same or different and represents N, O, S,
Or (ii) represents a divalent alkyl group and / or a divalent aromatic group, both can be further substituted, and n is from 0.1 to 99.9 mol-%)
A membrane electrode assembly comprising a polymer containing repeating units of:   In both options (a) or (b), n is 40 to 60 mol-%, preferably 50 mol-%, and the allocation amount between both secondary units of the repeating unit is comparable. The membrane electrode assembly according to claim 1, wherein   The membrane electrode assembly according to claim 1, wherein X is N or O in both options (a) or (b).   The membrane electrode assembly according to claim 1, wherein X is O in option (b). The alkyl in Z ¹ and / or Z ² , independently of one another, is a short-chain divalent alkyl group having 1 to 6 carbon atoms, preferably methyl, ethyl, n-propyl, or i-propyl, And n-, i- or t-butyl, n-, i- or t-pentane, n-, i- or t-hexane. The alkyl in Z ¹ and / or Z ² , independently of one another, is a short-chain divalent alkyl group having 1 to 6 carbon atoms, preferably methyl, ethyl, n-propyl, or i-propyl, And n-, i- or t-butyl, n-, i- or t-pentane, n-, i- or t-hexane, wherein at least one carbon atom is perfluorinated or at least one carbon atoms, at least one of (CF ₃₎ - group, and most preferably two (CF ₃₎ - -C been replaced by group (CF _{3) 2} - claim 1, characterized in that to form a group A membrane electrode assembly according to claim 1. Aromatic groups in Z ¹ and / or Z ² are independent of each other,
Represents a divalent aromatic group having 5 to 6 carbon atoms, wherein one or more carbon atoms can be replaced by a heteroatom selected from N, O or S, and at least one Represents an alkyl group having 2 to 6 carbon atoms, wherein at least one carbon atom is perfluorinated, or at least one carbon atom is substituted by at least one (CF ₃ ) -group, The alkyl group is at least one (CF ₃ ) -group, most preferably by two (CF ₃ ) -groups forming a C (CF ₃ ) ₂ -group, or a terminal C (CF ₃ ) ₃ -group. Has been replaced by,
The membrane electrode assembly according to claim 1. In option (b), R ¹ , independently of ^one another, is a divalent alkyl group having 1 to 10 carbon atoms, preferably methyl, ethyl, n-propyl, or i-propyl, and n-, i 2. Membrane electrode assembly according to claim 1, characterized in that it represents-or t-butyl, n-, i- or t-pentane, n-, i- or t-hexane. In option (b), R ¹ independently of each other represents a divalent aromatic group having 5 to 6 carbon atoms, wherein the divalent aromatic group has one or more carbon atoms, 2. The membrane electrode assembly according to claim 1, wherein the membrane electrode assembly is a group that can be replaced by a heteroatom selected from N, O, and S. An aromatic group having two covalent bonds, or a heteroaromatic group having two covalent bonds Ar ¹ , Ar ² , Ar ⁵ , Ar ⁶ independently of each other, monocyclic, bicyclic, or Represents a polycyclic fused or unfused aromatic or heterocyclic aromatic ring system having 5 to 20 carbon atoms, wherein the aromatic or heterocyclic aromatic ring system is One or more carbon atoms can be substituted by N, O, S, and said two aromatic groups or heteroaromatic groups Ar having two covalent bonds The membrane electrode assembly according to claim 1, characterized in that ¹ , Ar ² , Ar ⁵ , Ar ⁶ can be substituted by further groups.   The membrane electrode assembly according to claim 1, wherein the polymer comprising the repeating unit of the general formula (I) comprises at least 10, more preferably at least 50 repeating units of the general formula (I). The membrane electrode assembly according to claim 1, wherein the polymer containing the repeating unit of the general formula (I) has a mass average molecular weight M _w exceeding 10,000 (measured by gel permeation chromatography). The membrane electrode assembly according to claim 1, wherein the polymer containing the repeating unit of the general formula (I) has a number average molecular weight _Mn of more than 5000.   The membrane electrode assembly according to claim 1, wherein the polymer containing the repeating unit of the general formula (I) has a solubility in DMAc of at least 0.5% by mass at 25 ° C.   The mass ratio of the ionomeric material to the catalyst material in the catalyst layer is 100: 1 to 1: 100, preferably 10: 1 to 1:10, most preferably 1: 8 to 1: 3. The membrane electrode assembly according to claim 1.   2. Membrane according to claim 1, characterized in that the polymer electrolyte membrane or the electrolyte matrix has a proton conductivity of at least 1 mS / cm, preferably at least 2 mS / cm, in particular at least 5 mS / cm at a temperature of 120 ° C. Electrode assembly. Formula (I)

(However, (a)
Ar is the same or different and is an aromatic group having four covalent bonds, or a heterocyclic aromatic group having four covalent bonds, each of which is monocyclic, bicyclic, or polycyclic Cyclic is possible and X is the same or different and represents N, O, S, and R ¹ is the same or different, and the formula

A group having two covalent bonds, and Ar ¹ and Ar ² are the same or different, and an aromatic group having two covalent bonds, or a heterocyclic aromatic group having two covalent bonds Each represents a monocyclic, bicyclic, or polycyclic group, and
Z ¹ is the same or different and represents a divalent alkyl group and / or a divalent aromatic group, both of which at least one hydrogen atom is replaced by a fluorine atom, and n is 0.1 to 99.9 mol-%,
Or (b)
Ar is the same or different and has the formula

Represents a group having four covalent bonds,
Ar ³ and Ar ⁴ are the same or different and each represents an aromatic group having three covalent bonds or a heterocyclic aromatic group having three covalent bonds, each of which is monocyclic or bicyclic Can be of formula or polycyclic, and
Z ² is the same or different and represents a divalent alkyl group and / or a divalent aromatic group, both of which at least one hydrogen atom is replaced by a fluorine atom, and X is the same or different and represents N, O, S, and R ¹ is the same or different and (i)

A group having two covalent bonds, and Ar ⁵ and Ar ⁶ are the same or different, and an aromatic group having two covalent bonds, or a heterocyclic aromatic group having two covalent bonds Each represents a monocyclic, bicyclic, or polycyclic group, and Z ³ is the same or different and represents N, O, S,
Or (ii) represents a divalent alkyl group and / or a divalent aromatic group, both can be further substituted, and n is from 0.1 to 99.9 mol-%)
Using a polymer comprising a repeating unit as an ionomeric material, preferably as an ionomeric material in a cathode.   A fuel cell comprising at least one membrane electrode assembly according to claim 1.