WO2008092700A1

WO2008092700A1 - Fuel cell stack assembly comprising a special current conductor structure

Info

Publication number: WO2008092700A1
Application number: PCT/EP2008/000816
Authority: WO
Inventors: Robert Hahn
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 2007-01-30
Filing date: 2008-01-28
Publication date: 2008-08-07
Also published as: DE102007005232A1; DE102007005232B4

Abstract

The invention relates to a fuel cell stack assembly and to a method for producing the same. The fuel cell assembly (1) contains: a membrane unit (2) comprising at least one electrode in the form of an anode (3) and/or a cathode (4), in addition to at least one current conductor structure (5) containing an electrically conductive current conductor base body (6). The current conductor base body (6) has a passivation layer (7) with individual contacts (8) distributed over the surface, said individual contacts (8) being arranged in such a way that they make electrical contact with an electrode (3, 4) on one side and with the current conductor base body (6) on the other. The invention allows corrosion-resistant fuel cell stack assemblies with excellent long-term stability to be cost-effectively produced.

Description

Fuel cell arrangement

The present invention relates to a fuel cell assembly and a method for their preparation.

An essential, yet unsatisfactorily solved problem in the technical realization of fuel cells is the achievement of a low contact resistance between a Stromableiter- structure (for example, a bipolar plate) and a membrane unit with minimal corrosion and high long-term stability of Stromableiterstruk- structure. This is best achieved by bipolar plates made of graphite, but which are expensive to manufacture and have problems due to their brittle fracture risk for mobile use. It is therefore conceivable to use composite materials as material for bipolar plates, whose electrical conductivity is low. It is also known to use metallic polar plates to use. Metallic bipolar plates are corrosion-resistant if they form an (oxidic) passivation layer, which in turn greatly increases the electrical contact resistance.

It is therefore the object of the present invention to provide a fuel cell assembly which has a current sinker structure which has high corrosion stability and yet exhibits low contact resistance to a membrane unit / electrode. With the manufacturing method according to the invention a cost-effective production, even on an industrial scale, should be possible.

These objects are achieved by the subject-matter of the independent claims. This is initially a fuel cell arrangement, comprising a membrane unit having at least one electrode in the form of an anode and / or a cathode, and at least one Stromabieiterstruktur containing an electrically conductive Stromableitergrundkörper, and the Stromableitergrundkörper has a Passivierungsschicht with distributed therein single contacts, wherein the individual contacts are arranged so that they on the one hand electrically contact an electrode and on the other hand the Stromableitergrundkörper.

The Stromabieiterstruktur, which may be a simple Stromableiterplatte or part of a bipolar plate is inventively constructed so that it has a low contact resistance for electrical connection to a membrane unit due to the high electrical conductivity of the individual contacts. Here, the basic idea is that the individual contacts are distributed over the surface area the Stromabieiterstruktur and with the - preferably made of metal - Stromableitergrundkörper in electrical contact. The individual contacts are incorporated in an insulating coating. This means that the surface of the current drainage structure directed toward the membrane unit or to the specific electrode of the membrane unit has a "double-surface" structure. On the one hand, the flat distributed individual contacts are provided, which make the actual electrical contact. On the other hand, the individual contacts are surrounded by passivated, corrosion-resistant material.

By this "task sharing" on the one hand given the choice of highly conductive and non-corrodible metals for the individual contacts sufficient overall conductivity, on the other hand, the consumption of raw materials is limited only to the extent necessary, since no full-area occupancy must be done with, for example, a precious metal. In addition, a detachment of metal (which is possible, for example, in the case of mechanical deformation of the current conductor structure) is hardly possible, since the area to the current collector base body is significantly minimized here. Also a detachment by stresses due to different thermal expansion coefficients can be avoided by the expansion coefficients and the modulus of elasticity, especially the passivation layer can be very well adjusted.

To ensure corrosion resistance over long periods of time, it is also important to have a good fit between the materials and technologies between the electrically conductive contacts and the insulation area. There must be no formation of cracks or cracks along which a material transport could take place. It would also be used for an alkaline fuel cell materials other than for a fuel cell in which the ionic conductivity is generated by acid groups.

In the particularly aggressive alkaline environment, the base area on which the precious metal contacts are located may be coated with a metal such as magnesium, titanium or zirconium, which forms a natural lhehe oxide layer which is very stable in the interface with the polymer deposited thereon as a corrosion protection layer against a lye attack. As polymers are particularly suitable for polyamide or materials such as bitumen or asphalt.

The manufacturing method according to the invention provides that a Stromableitergrundkörper is provided with distributed in an insulating coating surface single contacts and then the individual contacts are brought into electrical connection with an electrode of the membrane unit.

This process is also very easy to produce in microstructures and is therefore recommended for cost-effective industrial production.

An advantage of the invention is that the electrical, mechanical and chemical properties of the surface coating need not be optimized in a single material, but practically on two materials (insulating coating to compensate for mechanical stresses, etc. and producing a good electrical Conductivity through the individual contacts) are divided.

So the contact material of the individual contacts should be have a good electrical conductivity, adhesion to the Stromableitergrundkörper and a good corrosion resistance. However, the coefficient of thermal expansion and the ductility of this material are of much less importance, since only very small contiguous areas are connected to the Stromableitergrundkörper. Also, the price of the material can be much higher without increasing the overall cost, since only a small substrate surface is coated with it (it is therefore even possible to use gold for the individual contacts).

In contrast, the passivation layer does not require any electrical conductivity and can be designed for optimum adhesion, ductility and chemical resistance. Here, above all, the use of polymers is possible. This makes it possible, for example, to coat a sheet with flat distributed individual contacts and a passivation arranged between the individual contacts and then to deform, without that (as in a total coating with the precious metal) defects or cracks occur. But even in the choice of material for the Stromableitergrundkörper even greater freedom is given. For example, copper or aluminum with a very high conductivity can be used here. These otherwise so susceptible to corrosion, but inexpensive and well-conductive materials in the non-corroded state are covered by the insulating layer so that there is none

Impairment of the total conductivity of the current collector structure comes. It should also be noted that the corrosion and thus the long-term stability are also strongly dependent on the operating parameters of the fuel cell (voltage, power density, temperature) and the type of fuel cell (hydrogen PEM, DMFC, DEFC). are pending. The contact resistance as a function of the contact pressure is dependent not only on the electrical conductivity of the materials but also on the mechanical properties (modulus of elastic modulus, compression modulus) and the thickness of the layers (in particular a softer partner, such as a gas diffusion layer attached to the membrane unit). These requirements can be well responded by an appropriate vote of the materials mentioned here.

It is preferably to be ensured that the average distance between the conductive individual contacts is so small that the spreading resistance in the membrane unit (electrode or gas diffusion layer) is negligible.

The present arrangement is possible for structures (membrane units) with or without additional gas diffusion layer used. In this case, the entire surface of the Stromabieiterstruktur can be coated with the individual contacts, or even only a portion of the webs, which are in direct contact with the membrane unit. As a field of application, all fuel cells come with planar cell or stack construction in question ge, in particular micro fuel cells, foil fuel cells, portable fuel cells, all suitable for integration into electrical appliances, clothing or vehicles.

The necessary contact pressure between the bipolar plate or the Stromabieiterstruktur and the Elektrodenbzw. Gas diffusion layer of the fuel cell and the electrical contact resistance is simultaneously reduced by applying on the surface of the bipolar plate or the Stromabieiterstruktur finely distributed, raised electrical contacts, which of surrounded by a corrosion-resistant coating. The mean distance between the individual contacts is so small that the spreading resistance in the electrode or gas diffusion layer is negligible. If the contacts, which are preferably made of a noble metal or provided with a stainless steel coating, project clearly beyond the surface of the bipolar plate or current drainage structure, a three-dimensional electrical contact is formed in the electrode or gas diffusion layer, which further reduces the contact resistance. Since the microcontact structure is produced only on the webs of the bipolar plates or the current collector and occupies there only a certain percentage of the total surface, the use of precious metals can be minimized. If the microcontacts are produced as structures with a very high aspect ratio (pillar structures, "no-lawn"), an independent anchorage is created during pressing with the electrode or gas diffusion layer of the fuel cell, so that the contact pressure is removed can be without the contact resistance increases. In this way, the contact resistance is not increased by different thermal expansion or relative movement caused by swelling. As a substrate for the micro-contact structure metals or metallizations, which can be produced cost-effective and lightweight fuel cells.

Advantageous developments of the present invention described in the dependent claims.

An advantageous development provides that the individual contacts have contact tips and the contact tips of the individual contacts for increasing the contact surface with the membrane unit in an electrode and / or gas diffusion layer of the membrane unit frictionally and / or positively introduced.

As a result, a contact pressure of the current collector structure on the membrane unit during operation of the fuel cell may possibly even be completely dispensed with. But at least this can be done by the contact pressure lower. In addition, the penetration of the individual contacts into the electrode or gas diffusion layer gives an even larger contact area (since lateral contact is also provided), so that even total contact areas are possible, which are larger than the planar plate area of the current drainage structure.

A further advantageous embodiment provides that the individual contacts are also partially coated with a corrosion-resistant coating. For example, (except for the individual contact tip, which should necessarily be provided with the highly conductive delimiting metal), the foot region of the individual contact may also be coated to a certain height.

A further advantageous embodiment provides that the contact tips of the individual contacts are plugged into the membrane unit or even executed (for example, "mushroom-shaped") that they engage behind the membrane unit area.

The individual contacts can be made entirely of precious metal (for example gold, silver or platinum). However, it is also possible (this applies in particular for "raised" contacts, which protrude beyond the main level of the insulating layer), that the noble metal coating takes place on a core body, which consists of a metal, a polymer material or a ceramic material. Under certain circumstances, this core body can also be an integral part of the current collector base body. However, it should be noted that the core body, if made of polymer or ceramic, must be electrically conductive or at least has a conductive cover layer which then ultimately connects all the individual contacts, eg gold contact points.

The contact resistances of the individual contacts to the membrane unit should be between 1 milliohm and 10 illiohms per square centimeter.

The individual contacts should in this case have a diameter between 0.1 microns and 1000 microns, preferably between 1 microns and 100 microns, more preferably between 50 microns and 100 microns.

The contact tips may either be planar to the electrical coating, so that overall it is a uniform plane. If the contact tips protrude beyond the plane of the surface of the insulating layer oriented toward the membrane unit, this protrusion should preferably be between 100 microns and 1000 microns.

A further advantageous embodiment provides that the distance of the center axes of adjacent individual contacts to each other is between 10 microns and 1000 microns. For curved individual contacts, the central axis is determined here by approximation (that is, by a linear approximation of the centroids of the cross-sectional areas). The thickness of a possibly gas diffusion layer on the membrane unit is preferably between 50 micrometers and 1000 micrometers.

The gas diffusion layer may be mechanically connected to increase the conductivity with the rest of the membrane unit, thereby the contact resistance is not increased by different thermal expansion or swelling of the partners involved and the resulting relative movement.

The intended Stromabieiterstruktur is applicable to a variety of different fuel cells. Thus, the Stromabieiterstruktur part of a Stromablei- terplatte / monopolar plate or a bipolar plate be. The fuel cell arrangement can also be made planar and have a total thickness between 100 micrometers and 1000 micrometers (this thickness specification refers to a membrane unit with monopolar current collector structures arranged on both sides).

According to the invention, there is also a fuel cell stack in which the individual cells consist of current conductors or bipolar plates which have been described above.

In addition, according to the invention is a planar fuel cell assembly of very low height, which consists of a five-unit membrane unit with compressed gas diffusion layer and due to the mechanical / electrical anchoring of the current collector / channel structures with the five-layer membrane unit can be mounted with a very small contact pressure, so that no solid pressure plates or end plates needed. In the production method according to the invention, it is possible that the individual contacts are first inserted or plugged into a Stromableitergrundkörper and then subsequently pressed with the membrane unit so that the contact tips of the individual contacts are frictionally and / or positively anchored in the membrane unit. This results in a particularly good conductivity due to high coverage areas, and the contact pressure can be kept low.

However, the individual contacts can also be produced by coating, preferably by coating elevations of the main body of the current plate. The individual contacts can also grow in a resist structure, which is then removed, thereby "mushroom shapes", which then engage behind, for example, a gas diffusion layer possible. In addition, many diverse methods of microstructuring are possible, so individual contacts are also by breeding a "nano-lawn" or by growing carbon nanotubes (CNT) possible, diverse applications of CVD or PVD are applicable.

As an advantage of the outstanding individual contacts (micro-contacts), two aspects can be highlighted: reduction of the electrical contact resistance and reduction of the mechanical contact force in order to obtain a small contact resistance. The fact that you can get by with smaller (or no) contact pressure, you can make the fuel cell thinner, easier to run because no pressure plates are needed.

A further advantageous embodiment provides that the Stromabieiterstruktur towards the electrode additionally has a lattice-shaped structure, which is coated for improved electrical conductivity partially or pointwise with precious metal.

For methanol fuel cells as well as open cathode sides, expanded metals, meshes, metal mesh or perforated metal foils are also used as current conductors. In certain constructions, these grids also lie between the membrane electrode assembly / gas diffusion layer and a current collector plate or flowfield plate with larger structural dimensions. The metals themselves are stainless steel, copper, titanium or Nobium.

Most of these lattices are coated over the entire surface with precious metal such as gold or platinum.

Here, according to the invention, only the outer regions, which are in contact with the gas diffusion layer or the current collector plates / flowfields, could be locally coated with precious metal. It would be sensible to first coat copper with an all-over protective layer of Nobium or titanium and then to produce the punctiform gold or platinum contacts.

Further advantageous developments are described in the other dependent claims.

The present invention will now be explained with reference to several figures. Show it:

1 shows a fuel cell arrangement according to the invention, which is particularly suitable for film fuel cells,

2 shows a further embodiment of an inventive Fuel cell arrangement according to the invention, in which the individual contacts engage behind a gas diffusion layer,

3 is a plan view and a cross-section of a Stromableiterstruktur invention,

Fxg. 4a

Fig. 4b are views of another embodiment of a power drainage structure,

Fig. 5,

FIG. 6 shows current collector structures, which show individual contacts with undercut sections, and FIG. 7, FIG.

Fig. 8 figures for explaining geometric conditions in the individual contacts.

1 shows a fuel cell arrangement 1 according to the invention. This contains a membrane unit 2 with two electrodes, namely an anode 3 and a cathode 4. A separate gas diffusion layer that builds up on these electrodes is not provided in this embodiment. This is followed in each case by the cathode or from the anode groundbreaking Stromablei- terstrukturen 5. These each have an electrically conductive current collector base body 6, wherein the current collector base body 6 has a passivation coating 7 with individual contacts 8 distributed in a planar manner. The individual contacts 8 are in this case arranged so that they contact the one hand, the corresponding anode 3 and cathode 4 and on the other hand, the respective Stromableitergrundkörper 6 electrically.

In the present embodiment, the electrode layer of the MEA is already of such a position and thickness, as well as the channel structure of the current conductor. Terstruktur very finely structured (channel widths between 10 microns and 1 millimeter), so that no further gas diffusion layer is required and the Stromabieiterstruktur (or bipolar plate) with the superficial micro-contact structure containing the individual contacts, pressed directly onto the electrode layer of the anode or cathode can be. This is in particular an advantageous construction for thin, foil-like, planar or micro fuel cells.

FIG. 2 shows a structure of another embodiment, wherein here additionally a gas diffusion layer 9 is shown. The thickness of the gas diffusion layer is mainly at 500 microns.

The individual contacts 8 in this case have contact tips 8a, wherein the contact tips for increasing the contact surface with the membrane unit in the Gasdiffusi- onslage the membrane unit frictionally and positively introduced (even inserted) and engage behind the membrane unit and the associated gas diffusion layer in some areas. When microcontacts (columnar structures, "nano-turf") are produced with a very high aspect ratio, a three-dimensional electrical contact and an independent anchoring are provided during pressing of these individual contacts with the electrodes or gas diffusion layers of the membrane unit, so that then the contact pressure substantially can be canceled without the contact resistance increases or considerably increases. However, in the case of a construction of a fuel cell arrangement with a gas diffusion layer, the prerequisite for canceling the contact pressure or a very small contact pressure is that the gas diffusion layer is already mechanically connected to the membrane unit connected (pressed) is, for example, five-layer gas diffusion layer. In this way, the contact resistance is not increased by different thermal expansion or by relative movement caused by swelling.

FIG. 3 again shows, in an enlarged representation, the structure of a current conductor structure according to the invention. On a Stromableitergrundkörper 6, which in the present case of metal (aluminum or copper) is, alternatively, a polymer or composite material with an electrically conductive surface is possible, the individual electrical contacts 8 are applied, which are characterized by a high electrical conductivity and corrosion resistance , The individual contacts here are made of gold, whereby the surface of the individual contacts was produced by galvanic deposition. Around the individual contacts 8 around a passivation layer 7 is generated, which does not have to have good electrical conductivity, important here is a high corrosion resistance. For fuel cells with proton membranes, where the ionic conduction is realized by acid groups, this means, above all, resistance at low pH values. These may be oxides, nitrides, carbides or the like, which are produced by deposition, doping and annealing, oxidation. The passivation layer can also be a thicker deposited layer of a glass or a ceramic or consist of a wide variety of polymers.

Important here is only a good adhesion of the contact material (for example, gold in single contact 8, the passivation layer 7 and the Stromablei- tergrundkörpers 6) and a corresponding adjustment of the thermal expansion. If necessary, the

Passivation layer with a defined pressure In order to ensure that there is always a cohesion between the contacts 1 and the passivation layer 2, even during thermal cycles or mechanical stress, so that no cracks develop at the interface where the corrosion of the underlying layer (current collector base body 6) begins could.

As shown in FIG. 1, on the right side, the individual contacts are coated with the passivation layer in regions (ie in their "foot region").

To save precious metal, the Stromableitergrundkörper taken alone can have from its O- berfläche projecting elevations, which are then only coated with a precious metal. In addition to these metal core bodies, a corresponding core to be coated of the individual contacts can also be made of a polymer material or a ceramic material. It should be noted, however, that the core body, if made of polymer or ceramic, must be electrically conductive, or at least has a conductive capping layer, which ultimately will have all the individual contacts, e.g. Connects gold contact points.

In the present case, the contact resistance of the individual contacts 8 to a membrane unit is 5 milliohms per square centimeter. The individual contacts 8 have, according to FIG. 1, a diameter of 50 micrometers. In this case, the contact tips 8a protrude 100 micrometers from the main surface plane of the current conductor structure (marked E in the right-hand side in FIG. 3).

The distance of the center axes of adjacent individual contacts to each other is (see distance w in FIG. 7) in the present case 90 micrometers. With the present arrangement, which is applicable, for example, for the planar film fuel cell of Fig. 1, a very small constructive possibility is given, the total thickness of the arrangement shown in Fig. 1 is 200 to 500 microns.

FIGS. 4a and 4b show the possibility of providing the contact structure shown in FIG. 3 only on bars 10 of the channel structure 11 or the bars 10 'of a corresponding open grid structure in FIG. 4b (for an open cathode structure). The passivation layer can be provided either only in the area around the individual contacts or in the entire channel or grid structure. If the passivation is produced, for example, by oxidation of the current collector base body 6, this is automatically done at all locations not occupied by individual metal contacts. Alternatively, polymer materials (eg, parylene) may be conformally deposited over the entire surface, or, for example, by spray coating with other polymers. Subsequently, holes are opened (by etching or laser) and then the individual contacts 8 electrodeposited. If the individual contacts were produced first and then the polymer coating was carried out, an exposed contact on the contact surface is subsequently achieved by polishing the surface.

In one variant, the individual contacts according to the invention can be "selectively" attached, so it is not an admixture of particles in a polymer, etc., in order to increase the conductivity over a total area. Instead, this variant deliberately becomes a structured breakdown intended two materials with different property profiles. The contact structure according to the invention is produced, for example, in a second embodiment by using conductive particles on an electrically conductive basic body

(Gold or silver grains, flakes) filled polymer is applied and cured. The shape and density of the particles is in this case such that always arise electrically conductive paths from the conductive body to surface. This can be conveyed during curing by pressing a subsequently to be removed plate. To allow the conductive contacts to protrude, a selective etching of the polymer could then be performed, e.g. done with reactive ion etching. The contacts do not have to be distributed evenly, there is a medium distance.

In addition, it should be noted that the single contacts with high conductivity (also to keep the spreading resistance low) are mounted at a very small distance from each other. These are preferably contacts, which are preferably smaller by an order of magnitude than, for example, in measuring cells in which the conductivity can be determined in some areas with the aid of protruding contacts. In addition, in contrast to the individual contacts in measuring cells, in the present case all contacts are connected to the same electrically conductive basic body, ie (apart from inhomogeneities of the fuel cell) all are at the same potential.

FIGS. FIGS. 5 and 6 show further examples of current collector structures in which the individual contacts have an undercut. If, for example, the contacts are produced galvanically in a resist pattern, which is subsequently removed, a mushroom structure 12 can be produced by monitoring the resist. This can advantageously entangle in the fabric or the fiber structure of the gas diffusion layer, so that there is a kind of Velcro effect and the low contact resistance is maintained even with complete release of the contact force (see analogy to Fig. 2).

As shown in FIG. 6 (see also FIG. 2), even longer individual contact structures can be produced, for example by electrodeposition in polymer membranes in which a microchannel structure was previously produced. Subsequently, these polymer membranes are then dissolved. The microchannel structure can be achieved by puncturing with fine needles or by bombardment with energetic particles. The resulting structures need not be completely symmetric or similar. Important are only a medium, uniform distribution and a preferred direction perpendicular to the substrate. The structures thus produced with diameters of a few micrometers, sometimes even less than 1 micrometre, would also be referred to as "nano-turf". At the same time, however, it is also possible to use carbon nanotubes (CNTs), which have been grown in a structured manner on the substrate before.

FIGS. Figures 7 and 8 serve to illustrate the dimensions of the distances and diameters of the contacts. Since precious metals, such as gold, are to be used for the individual contacts 8, a very small, negligible contact resistance can be assumed at these contacts. The greater resistance is due to the lateral current flow towards the contacts. This resistance (spreading resistance, spreading resistance) depends on the distance and diameter of the contacts and the conductivity p of the layers, with thin layers also on the thickness of the layer. If the substrate (thus also the current collector base body) consists of metal (copper or aluminum or stainless steel), the spreading resistance can be neglected there compared to the spreading resistance in the electrode layer or gas diffusion layer of the membrane unit. The conductivity of steel is so high compared to the conductivity of the usual gas diffusion layers that presumably the conductivity of the gas diffusion layer is ultimately decisive for the spreading resistance. The spreading resistance according to FIG. 7 is calculated approximately according to the following formula

Rsp _r ead p = 4 * d ² / 3w ² * [l + d / (wd)].

The greater the sheet resistance of the current collector base body 6 or the gas diffusion layer or the electrode layer of the membrane unit, the smaller the distance between the individual contacts 8 should be. The contact resistance here (see above) between 1 milliohm and 10 milliohms per square centimeter, the contact diameter of the single contact can be between 0.1 microns and 1000 microns. In an optimized system, the average distance between the individual contacts is so small that the spreading resistance in the electrode or gas diffusion layer is negligible.

FIG. 8 shows how the individual contacts 8 protrude significantly beyond the surface E (see also FIG. 3) of the current drainage structure, so that a three-dimensional surface is formed in the electrode or gas diffusion layer. Sional electrical contact is formed, whereby the contact resistance is further reduced. In addition, the contact pressure of the current collector structure is distributed over a smaller total area of the contact cross sections. In this way, the total contact pressure necessary for the minimum contact resistance can be significantly reduced. This is another important advantage: the achievement of a uniform and sufficient contact pressure. Achieving low contact resistance is one of the most difficult constructive issues, especially with planar fuel cells, thereby finally providing a solution to this problem.

In order to produce the fuel cell arrangements according to the invention, in each case one current-carrying base body is provided with individual contacts 8 distributed over a passivation layer, and then the individual contacts 8 are brought into electrical connection with an electrode (anode 3, cathode 4) of the membrane unit 2, so that the in FIG 1 or 2 generated structures are available. Details of these manufacturing processes have been discussed above in the individual embodiments.

Claims

claims

1. Fuel cell assembly (1) containing a

Membrane unit (2) with at least one electrode in the form of an anode (3) and / or a cathode (4), and at least one Stromabieiterstruktur (5), which contains an electrically conductive Stromableiter- basic body (6), and the Stromableitergrundkörper (6) a passivation layer (7) with distributed therein single contacts (8), wherein the individual contacts (8) are arranged so that they contact on the one hand an electrode (3, 4) and on the other hand the Stromableitergrundkörper (6) electrically.

2. Fuel cell assembly according to claim 1, characterized in that the individual contacts (8) contact tips (8a) and the contact tips (8a) of the individual contacts (8) to increase with the contact surface with the Membranein- unit (2) in an electrode and / or gas diffusion layer (9) of the membrane unit (2) is frictionally and / or positively introduced.

3. Fuel cell arrangement according to claim 1 or 2, characterized in that the individual contacts (8) are partially coated with the passivation layer (7).

4. Fuel cell arrangement according to one of claims 2 or 3, characterized in that the Contact tips (8a) are inserted into the membrane unit (2).

5. Fuel cell arrangement according to one of claims 2 to 4, characterized in that the contact tips (8a) engage behind the membrane unit (2) in regions.

6. Fuel cell arrangement according to one of the preceding claims, characterized in that the individual contacts (8) are made of precious metal or have a core body which is coated with noble metal.

7. Fuel cell assembly according to claim 6, characterized in that the noble metal is gold, silver or platinum.

8. fuel cell assembly according to any one of claims 6 or 7, characterized in that the core body of a metal, an electrically conductive polymer or an electrically conductive ceramic, wherein it is sufficient that the body of polymer or ceramic provided with an externally conductive layer are.

9. Fuel cell arrangement according to one of the preceding claims, characterized in that the contact resistances of the individual contacts (8) amount to between 1 milliohm and 10 milliohms per square centimeter.

10. fuel cell assembly according to any one of the preceding claims, characterized in that the individual contacts (8) see a diameter between 0.1 and 0.1 microns, preferably between 1 micron and 100 microns, especially preferably between 50 microns and 100 microns.

11. Fuel cell arrangement according to one of claims 2 to 10, characterized in that the contact tips (8a) between 100 microns and

1000 microns protrude from the main surface plane.

12. Fuel cell assembly according to one of the preceding claims, characterized in that the distance between the center axes of adjacent individual contacts (8) to each other between 10 microns and 1000 microns.

13. Fuel cell arrangement according to one of the preceding claims, characterized in that the thickness of the gas diffusion layer (9) between 50

Micrometer and 1000 microns.

14. Fuel cell arrangement according to one of the preceding claims, characterized in that the gas diffusion layer (9) with the remaining membrane unit (2) is already mechanically connected.

15. Fuel cell arrangement according to one of the preceding claims, characterized in that the Stromabieiterstruktur (5) is part of a Stromableiterplatte or a bipolar plate.

16. Fuel cell arrangement according to one of the preceding claims, characterized in that said fuel cell assembly (1) is planar and has a total thickness between 100 microns and 1000 microns.

17. A fuel cell stack, comprising at least one fuel cell arrangement according to one of the preceding claims.

18. Fuel cell arrangement according to one of the preceding claims, namely planar fuel cell arrangement of very small height, which consists of a five-layer membrane unit with compressed gas diffusion layer and due to the mechanical / electrical anchoring of the current discharge / channel structures with the five-layer

Membrane unit can be mounted with only a very small contact pressure, and thus massive pressure plates or end plates are dispensable.

19. Fuel cell arrangement according to one of the preceding claims, characterized in that the Stromabieiterstruktur (5) to the electrode (3, 4) out additionally has a lattice-shaped structure, which is partially or selectively coated with noble metal for improved electrical conductivity.

20. A method for producing a fuel cell arrangement (1), wherein at least one current conductor main body (6) is provided with individual contacts distributed in an insulating coating, and then the individual contacts (8) are electrically connected to an electrode (3, 4) the membrane unit (2) or diffusion layer (9) are brought.

21. Method according to claim 20, characterized in that the individual contacts (8) are subsequently pressed with a membrane unit (2) in such a way that the contact tips (8a) of the individual components clocks (8) frictionally and / or positively anchored in the membrane unit (2).

22. The method according to claim 20, characterized in that the individual contacts (8) in the Stromab- conductor base body (6) are inserted or plugged.

23. The method according to claim 21, characterized in that the individual contacts (8) by coating, preferably of elevations of the Stromabieiterkörpers (6) arise.

24. The method according to claim 20, characterized in that the individual contacts (8) grow in a resist structure, which is subsequently removed.

25. The method according to claim 20, characterized in that the individual contacts (8) by CVD or PVD process arise.