WO2019175014A1

WO2019175014A1 - Electrochemical energy converter having a reduced contact resistance

Info

Publication number: WO2019175014A1
Application number: PCT/EP2019/055702
Authority: WO
Inventors: Friedrich Kneule; Arne Stephen FISCHER
Original assignee: Robert Bosch Gmbh
Priority date: 2018-03-14
Filing date: 2019-03-07
Publication date: 2019-09-19
Also published as: DE102018203826A1

Abstract

The invention relates to an electrochemical energy converter (1) in which gases are generated and/or consumed, comprising at least one media distribution structure (6, 7) and at least one gas diffusion layer (4, 5), wherein a planar, electrically conductive contact is formed at the contact regions (20) between the surface of the at least one media distribution structure (6, 7) and the surface of the at least one gas diffusion layer (4, 5). The invention also relates to a method for producing such an electrochemical energy converter (1) and to the use thereof.

Description

Electrochemical energy converter with reduced contact resistance

The invention relates to an electrochemical energy converter having a reduced contact resistance between various components of the electrochemical energy converter, such as e.g. between media distribution structure and gas diffusion layer. Furthermore, the invention relates to a method for producing such an electrochemical energy converter and its use.

State of the art

Electrochemical energy converters are electrochemical cells that are capable of converting chemical energy into electrical energy and / or converting electrical energy into chemical energy. Known

Electrochemical energy converters are, for example, fuel cells and electrolyzers. A fuel cell is a galvanic cell that converts the chemical reaction energy of a continuously supplied fuel and an oxidant into electrical energy. At acquaintances

Fuel cells are converted in particular hydrogen (H ₂ ) and oxygen (0 ₂ ) into water (H ₂ 0), electrical energy and heat. An electrolyzer is an electrochemical energy converter, which splits water (H ₂ 0) into hydrogen (H ₂ ) and oxygen (0 ₂ ) by means of electrical energy.

Frequently, during the operation of the electrochemical energy converter, gases are produced (electrolyzer) or consumed (fuel cell). The respective reaction takes place at a membrane arranged centrally in the electrochemical energy converter. To transfer the gases to the membrane in the electrochemical

To direct energy converters (or to conduct away from the membrane), these usually comprise at least one media distribution structure and at least one disposed between the media distribution structure and the membrane

Gas diffusion layer. The media distribution structure takes over the rough

Distribution of gases in the electrochemical energy converter, which then be more evenly distributed through the gas diffusion layer and defined in a fuel cell led to the membrane or be removed in an electrolyzer of this.

The actual electrochemical reaction takes place on the membrane. In order to achieve the best possible degree of energy conversion, it is essential that the electrical conductivity of the media distribution structures and the gas diffusion layers is as high as possible. Critical here is in particular the

Contact resistance between the media distribution structure and the

Gas diffusion layer. This is often referred to as contact resistance. Bonded connections, which are achieved by welding, soldering or sintering, result in a low contact resistance between the components to be connected, but as a rule are only possible if the at least one media distribution structure and the at least one

Gas diffusion layer are made of the same material. Are these

Components made of different materials often result in high contact resistance.

DE 11 2004 001 443 B4 discloses the connection of the anode and the

Cathode side of bipolar plates by means of an electrically conductive adhesive.

DE 43 14 745 CI describes a fuel cell, which consists of a

thermoplastic base polymer is made, and in which a current collector and a gas distributor ring may be connected by gluing or welding together.

E. Firat et al. describe a method for mounting graphitic

Fuel cell stack, among other things, the gas diffusion layer and the bipolar plate are connected by a circumferential adhesive layer and the adhesive is electrically conductive (Poster by E. Firat, S. Brokamp, P. Beckhaus, A. Heinzei, C. Tzschoch, K. Dilger, 9 Workshop "AiF Fuel Cell Alliance" 2016 - SME Research for the Energiewende, 21 June 2016, ZBT, Duisburg). Disclosure of the invention

The invention relates to an electrochemical energy converter in which gases are generated and / or consumed, comprising at least one

Media distribution structure and at least one gas diffusion layer, wherein at the contact areas between the surface of the at least one

Media distribution structure and the surface of at least one

Gas diffusion layer, a planar, electrically conductive contact is formed.

Inventive electrochemical energy converters are all

electrochemical cells, in which chemical energy is converted into electrical energy or electrical energy is converted into chemical energy, wherein gases are generated and / or consumed. Examples of such electrochemical energy converters are fuel cells and electrolyzers. More preferred are fuel cells or electrolyzers comprising at least one polymer membrane. The polymer membrane may be conductive to protons or hydroxide ions. Suitable proton exchange membranes (proton exchange membrane, PEM) and hydroxide ion exchange membranes (hydroxy exchange membrane, HEM) are known in the art.

The electrochemical energy converter typically includes at least one anode side and at least one cathode side. At least one structure for the coarse distribution of the media (so-called media distribution structure), at least one structure for the fine distribution of the media (so-called gas diffusion layer), as well as an electrode, which is located directly on the membrane, are located on both the anode side and on the cathode side , Usually, the media distribution structure, the gas diffusion layer and the electrode are each electrically conductive.

The media distribution structure has at least one structure which makes it possible to evenly distribute fluid media. In one embodiment, the media distribution structure is designed, for example, as a bipolar plate. In a fuel cell, the media distribution structure serves, on the one hand, to distribute the fuel on the anode side or the oxidant on the other Cathode side. In addition, it is possible to establish a cooling circuit using a correspondingly designed media distribution structure in order to derive any resulting heat energy from the fuel cell. The fuel or the oxidant are through

Connection points initiated and distributed in the media distribution structure.

For further (finer) distribution of the fuel and the oxidizing agent, the fuel is introduced at the anode side in a porous gas diffusion layer. Similarly, the oxidant on the cathode side in a porous

Gas diffusion situation initiated. The gas diffusion layers distribute the gases evenly and transport them to the membrane, which is located between the gas diffusion layers and separates the anode and cathode sides. The gas diffusion layers are also electrically conductive.

In an electrolyzer, the media distribution structure serves to distribute the medium to be decomposed by electrolysis or to remove the resulting reaction products, in particular gases. In addition, it is possible to establish a cooling circuit using an appropriately designed media distribution structure, so as to remove any resulting heat from the

Derive electrolyzer. In general, the heat is at the

Electrolysis, however, low, so that a cooling circuit is often not needed. Through connection points of the media distribution structure, the starting materials can be introduced and distributed and the products are removed.

The electrolyzer also has porous gas diffusion layers, which serve for the further distribution of the educts to the membrane or for the discharge of the products from the membrane. The gas diffusion layers are also electrically conductive.

The media distribution structures of the electrochemical energy converters are made of an electrically conductive material. This may be a metal, a metal alloy, an electrically conductive polymer or even an electrically conductive carbon compound. As electrically conductive metals and metal alloys are in particular iron, titanium, copper, nickel, aluminum and alloys of said metals mentioned. electrical Conductive polymers include polymers that are electrically conductive (intrinsic conductivity) due to their chemical structure, especially polymers containing conjugated double bonds. As examples are polypyrrole,

Polythiophene, polyaniline, polyparaphenylene, polyacetylene, polyethyne, and derivatives and copolymers of the foregoing. These can also be doped. In addition, conductive polymers can be obtained by the addition of conductive additives to a non-electrically conductive polymer, in particular by addition of particles of metal, carbon black and / or graphite and / or graphene, carbon fibers, carbon nanotubes, as well as by the addition of particles and / or Fibers of the aforementioned intrinsically conductive polymers. These conductive additives are preferably uniformly distributed in the non-electrically conductive polymer. As electrically conductive carbon compounds graphite and graphene are mentioned in particular. In addition, the aforementioned polymers, which already have an intrinsic electrical conductivity, can be improved by the addition of the aforementioned conductive additives in terms of their electrical conductivity.

The gas diffusion layers are usually made of electrically conductive polymers or electrically conductive carbon compounds. Suitable electrically conductive polymers here likewise include polymers which, owing to their structure, are electrically conductive (intrinsic conductivity), in particular polymers which contain conjugated double bonds. Examples include polypyrrole, polythiophene, polyaniline, polyparaphenylene, polyacetylene, polyethyne, and derivatives and copolymers of the foregoing. These can also be doped. In addition, conductive polymers can be obtained by the addition of conductive additives to a non-electrically conductive polymer, in particular by addition of particles of metal, carbon black and / or graphite, graphene, carbon nanotubes carbon fibers, as well as by the addition of particles and / or fibers of the above mentioned intrinsically conductive polymers. Here are also mixtures of the aforementioned

Materials / particles in question. These conductive additives are preferably uniformly distributed in the non-electrically conductive polymer. As electrically conductive carbon compounds graphite and graphene are mentioned in particular. In addition, the aforementioned polymers, which already have an intrinsic electrical conductivity, by the addition of above-mentioned conductive additives are improved in terms of their electrical conductivity.

The gas diffusion layers have an at least partially porous structure.

The mean diameter of the pores of the gas diffusion layers are typically in a range from 1 to 500 μm. Often they are

Gas diffusion layers made of carbon paper or fabric.

In a preferred embodiment, the media distribution structure and the gas diffusion layer are made of different materials. This is often the case as the media distribution structure and the gas diffusion layer perform different tasks. For example, the media distribution structure gives the

electrochemical energy converter has additional stability and needs

if necessary, safely separate the cooling medium from the reaction space. In addition, for dissipating the heat of reaction as a material for the media distribution structure, a material having high thermal conductivity is preferable. Often that is

Medienverteilstruktur therefore made of a metal or a metal alloy, while the gas diffusion layer is made of an electrically conductive polymer and / or an electrically conductive carbon compound.

The gas diffusion layer and the media distribution structure are arranged adjacent to each other. The individual configuration of both components results in contact areas and areas in which there is no direct contact.

This is achieved primarily by the media distribution structure, which

Structures for distributing a fluid along a surface of the

Gas diffusion layer includes. There is no such thing between these structures

direct contact between the surface of the gas diffusion layer and the surface of the media distribution structure. In the other areas of the

Media distribution structure is a direct mechanical contact between the surface of the gas diffusion layer and the surface of the

Media distribution structure. These areas are also referred to below as contact areas. Due to the porous structure of the gas diffusion layer, the actual area available for electrical contact is in the

Contact areas compared to non-porous materials lower. The contact resistance ie the electrical resistance in these contact areas comparatively high and may in particular increase further, for example due to oxidation and other chemical changes in the surface of the media distribution structure and / or the gas diffusion layer in the course of the useful life.

The electrochemical energy converter according to the invention solves this problem by providing, at the contact areas between the surface of the at least one media distribution structure and the surface of the at least one

Gas diffusion layer, a planar, electrically conductive contact is formed. The planar, electrically conductive contact in the sense of this invention is an electrically conductive contact which is not selectively limited to direct contact points between the surface of the at least one media distribution structure and the surface of the at least one gas diffusion layer, but also by a contacting means between the individual contact points the surrounding areas extends. Thus, the contact resistance of the electrochemical energy converter is significantly reduced and stabilized in the long term.

Preferably, the planar, electrically conductive contact extends at the contact regions over the entire surface of the individual contact regions (contact surface). In a further preferred embodiment, the planar, electrically conductive contact is formed at all contact areas between the surface of the at least one media distribution structure and the surface of the at least one gas diffusion layer. This allows the greatest possible reduction of the contact resistance. In one embodiment, the planar, electrically conductive contact is thus over the entire sum of the contact surfaces of the contact regions between the at least one

Medienverteilstruktur and the at least one gas diffusion layer formed.

In one embodiment, the planar, electrically conductive contact in the form of an electrically conductive cohesive connection is formed. A cohesive connection is a connection in which the connection partners are held together by atomic or molecular forces. A cohesive connection is not solvable and can only be separated by destruction of the bonding agent. In an alternative embodiment, the flat, electrically conductive contact is in the form of a detachable, electrically conductive contact.

The planar, electrically conductive contact is preferably formed by an electrically conductive material as a contacting agent. This material is preferably characterized in that it is under conditions in which the at least one gas diffusion layer and the at least one

Media distribution structure are mechanically stable, at least partially plastically deformable. This ensures that in the production of the

an intimate contact between the surface of the gas diffusion layer or the surface of the media distribution structure and the electrically conductive material can be achieved and the electrochemical energy converter

Contacting means to the surface of the gas diffusion layer or the surface of the media distribution structure conforms. In addition, the electrically conductive material is preferably chemically and mechanically stable under operating conditions of the electrochemical energy converter. This means that the electrically conductive material during operation of the

electrochemical energy converter essentially no chemical

Reactions is received and mechanically not significantly deformed.

The electrically conductive material has a good electrical conductivity, preferably of at least 0.1 S / cm, more preferably at least 1 S / cm and in particular at least 10 S / cm, at 20 ° C.

The electrically conductive material is preferably a material based on a polymer having a molecular weight of at least 500 g / mol, preferably at least 750 g / mol and in particular at least 1000 g / mol (measured by gel permeation chromatography).

Particularly preferably, the electrically conductive material, at least during operation of the electrochemical energy converter according to the invention in a range of -40 to 120 ° C, a viscosity of at least 10 ⁴ Pa-s, more preferably at least 10 ⁵ Pa-s, and especially at least 10 ⁶ Pa -s up. This can be achieved, for example, by the fact that for the production of the electrochemical energy converter according to the invention an electrical is used conductive material whose viscosity either already meets the above requirements, or that the preparation of the electrochemical energy converter according to the invention, an electrically conductive material is used, the viscosity of which is optionally subsequently increased by curing processes. Suitable curing processes include in particular physical processes, such as the solidification of a molten material or the evaporation of a solvent and chemical processes, such as the chemical crosslinking of a chemically reactive material.

Suitable materials include polymers that are electrically conductive due to their structure (intrinsic conductivity), especially polymers containing conjugated double bonds. Examples include polypyrrole, polythiophene, polyaniline, polyparaphenylene, polyacetylene, polyethyne, and derivatives and copolymers of the foregoing. These can also be doped.

In addition, conductive polymers can be obtained by the addition of conductive additives to a non-electrically conductive polymer, in particular by adding particles of metal, carbon black and / or graphite, carbon fibers, as well as by the addition of particles and / or fibers of the aforementioned intrinsically conductive polymers , Particularly suitable are particles of the abovementioned materials, in particular metal particles, having an average particle diameter of 10 to 1000 nm, preferably 100 to 500 nm.

The electroconductive additives are added to the polymer preferably in an amount of 1 to 95% by weight, more preferably 5 to 90% by weight, and

in particular 10 to 85 wt .-%, based on the total weight of the electrically conductive material, added and is preferably evenly distributed therein.

In one embodiment of the invention, the non-electrically conductive polymer contains metal-containing, electrically conductive additives preferably in an amount of from 1 to 95% by weight, more preferably from 30 to 90% by weight and in particular from 50 to 85% by weight, based on the total weight of the electrically conductive material added. In a further embodiment of the invention, metal-free, electrically conductive additives are preferably added to the non-electrically conductive polymer in an amount of 1 to 95% by weight, more preferably 5 to 75% by weight and in particular 20 to 60% by weight. , based on the total weight of the electrically conductive material. Metal-containing, electrically conductive additives for the purposes of this invention are additives which

Metal atoms or metal ions in any form. Metal-free, electrically conductive additives for the purposes of this invention are additives which are substantially free of metal atoms or metal ions, i. less than 5% by weight, preferably less than 2% by weight and in particular less than 1% by weight of metal atoms or metal ions. As metal-free, electrically conductive additives are in particular carbon black and / or graphite, carbon fibers, as well as by the addition of particles and / or fibers of the aforementioned intrinsically conductive polymers mentioned.

Suitable non-electrically conductive polymers include in particular

Polyolefins such as polyethylene, polypropylene, polystyrene, and copolymers thereof, polyesters such as polyethylene terephthalate, polycarbonates, polyethers such as polyepoxides, polysulfones, polyethersulfones, polyetherketones, and mixtures of the foregoing. In a particularly preferred embodiment, the electrically conductive material according to the invention comprises at least one polyolefin, in particular a polyethylene or polypropylene, having a weight-average molecular weight Mw of from 1000 g / mol to 100,000 g / mol (measured by gel permeation chromatography in trichlorobenzene against a polystyrene standard), and at least an additive, in particular metal particles, carbon black or graphite. The metal particles are preferably selected from copper, nickel and / or aluminum particles.

In addition, the abovementioned polymers which already have an intrinsic electrical conductivity can be used as suitable materials, the electrical conductivity of which has been further improved by the addition of the abovementioned conductive additives. Even small amounts of additives are usually sufficient here.

In a particularly preferred embodiment, the electrically conductive material additionally has anti-corrosive properties. This is preferably achieved by the electroconductive material being hydrophobic, thus suppressing the penetration of corrosive media such as water or acids. In addition, the electrically conductive material is preferably chemical largely inert. Thus, the oxidation or corrosion of the contact surfaces of at least part of the surfaces of the gas diffusion layer and / or the media distribution structure can be reduced or even prevented. Of the

Contact resistance can thus be kept stable at a low level in the long term. These properties are in particular due to the previously

fulfilled polyolefins described.

In a further particularly preferred embodiment, the electrically conductive material comprises at least one adhesive based on epoxy resin. These are characterized by the fact that they are chemically very inert and the

Protect underlying surfaces well against corrosion.

In a further preferred embodiment, further contact areas in the electrochemical energy converter, which have a high electrical

To ensure conductivity, also provided with the inventive electrically conductive material, so as to achieve a planar, electrically conductive contact. Preferably, all contact areas in the electrochemical energy converter, which has a high electrical

Ensure conductivity, also provided with the inventive electrically conductive material.

The invention also provides a process for producing an electrochemical energy converter, the process comprising at least the following steps:

(i) providing at least one media distribution structure and at least one gas diffusion layer;

(ii) coating at least the regions of the at least one

Media distribution structure and / or the at least one gas diffusion layer with an electrically conductive, plastically deformable material, which after joining the at least one media distribution structure and the at least one gas diffusion layer in the electrochemical

Energy converters form the contact areas between the two;

(iii) assembling the at least one media distribution structure and the

at least one gas diffusion layer, so as to achieve a planar, electrically conductive contact between the at least one media distribution structure and the at least one gas diffusion layer, which passes through the at least one electrically conductive, plastically deformable material is formed, wherein the assembly can optionally take place under the action of elevated pressure and / or elevated temperature; and

(iv) optionally curing the electrically conductive, plastically deformable material, wherein the curing can be done physically (e.g., by solidification of a molten material) or chemically (e.g., by chemically crosslinking a chemically reactive material).

With regard to the individual components, the information given above applies. The selected temperature is in a range in which the media distribution structure and the material of the gas diffusion layer are mechanically stable. Preferably, the temperature is in a range of -40 to 200 ° C, especially in a range of -40 to 150 ° C. The selected pressure is preferably in a range of 0 to 1 MPa, especially 0.1 to 0.7 MPa. In this case, pressure and temperature are in particular matched to one another such that an intimate contact is formed between the surface of the gas diffusion layer and the electrically conductive material without the electrically conductive material filling the pores of the gas diffusion layer. Preferably, the electrically conductive material penetrates no more than to a depth of 20%, more preferably 10%, in particular 5%, based on the layer thickness of the entire gas diffusion layer in the pores thereof. In a preferred embodiment, the electrically conductive material penetrates no more than to a depth of 5%, more preferably 2%, in particular 1%, based on the layer thickness of the entire

Gas diffusion layer in the pores of the same one

The invention also provides the use of an electrochemical energy converter according to the invention for converting chemical energy into electrical energy and / or for converting electrical energy into chemical energy.

Advantages of the invention

The electrochemical energy converter according to the invention is characterized both initially and permanently in operation by a reduced resistance between the media distribution structure and the gas diffusion layer. This provides in particular in cases where the media distribution structure and the

Gas diffusion layer are made of different materials and a sufficient electrically conductive contact not by conventional

Manufacturing techniques such as welding or soldering can be achieved, great benefits. In addition, the electrochemical energy converter according to the invention can be produced in a simple process, which can be easily integrated into existing processes for the production of fuel cells or electrolyzers. In addition, the inventive electrochemical energy converter allows for its production a greater manufacturing tolerance, since the used electrically conductive material allows compensation over a wider Toleranzberiech.

Brief description of the drawings

Embodiments of the invention will be explained in more detail with reference to the drawings and the description below.

Show it:

Figure 1 is a schematic representation of a conventional

electrochemical energy converter using the example of a

Fuel cell stack,

Figure 2 is a schematic representation of an inventive

electrochemical energy converter using the example of a

Fuel cell stack.

Embodiments of the invention

In the following description of the embodiments of the invention, the same or similar elements are denoted by the same reference numerals, wherein a repeated description of these elements is dispensed with in individual cases. The drawings illustrate the subject matter of the invention only schematically. Fig. 1 shows schematically a section of a conventional

electrochemical energy converter 1. This is exemplified in the form of a fuel cell stack comprising a plurality of individual

Fuel cells 2. In the present case, two fuel cells 2 are shown. Each fuel cell 2 comprises a central membrane 3 which is permeable to protons or hydroxide ions. On a surface of the membrane 3 a gas diffusion layer 4 is arranged flat. On the opposite surface of the membrane 3, a gas diffusion layer 5 is also arranged areally. These gas diffusion layers 4, 5 serve to introduce the reactants, for example hydrogen and oxygen, uniformly distributed from the different sides to the membrane 3. In addition, the reaction products, for example water, which is formed in the reaction of oxygen and hydrogen, by at least one of

Gas diffusion layers 4 and 5 transported away from the membrane 3. The

Reaction partners are through the media distribution structure 6 and the

Media distribution structure 7 fed into the fuel cell and passed evenly to the gas diffusion layers 4 and 5 respectively. This is done via the channels 10 and 11, which are formed between the surface of the media distribution structures 6 and 7 and the surface of the gas diffusion layers 4 and 5 respectively. The channels 10 and 11 are delimited from one another by contact regions 20 in which there is direct contact between the surface of the media distribution structure 6 or 7 and the surface of the gas diffusion layers 4 and 5, respectively. As a rule, the media distribution structures 6 and 7 comprise, in addition to the channels 10 and 11, further channels 12 through which a temperature control medium, in particular a coolant, can flow. This serves the resulting

Reaction heat from the fuel cell 2 to remove. The channels 12 are not in direct contact with the channels 10 and 11 or the

Gas diffusion layers 4 and 5, respectively. The heat transfer takes place via the material from which the media distribution structures 6 and 7 are made. The

Temperature control can thus not enter the gas diffusion layers 4 and 5 respectively.

The gas diffusion layers 4 and 5 are usually made of a porous, electrically conductive material. Often an electrically conductive polymer or graphite is used. The media distribution structures 6 and 7 are usually made of a non-porous, electrically conductive and thermally conductive material. Often a metal or a metal alloy is used.

The contact areas 20 serve, in addition to the mechanical stabilization of the electrochemical energy converter 1, among other things, to an electrically conductive contact between the electrically conductive gas diffusion layers 4 and

5 and the electrically conductive media distribution structures 6 and 7, respectively. This is necessary to transport away the electrical current generated at the membrane 3. Are the gas diffusion layers 4 and 5 and the

Media distribution structures 6 and 7 made of different materials, so sufficient electrically conductive contact can not be formed at the contact areas 20, since the areas are e.g. can not be welded or soldered together. This results in high electrical resistance (also referred to herein as junction resistance or contact resistance) which reduces the performance of the fuel cell.

The schematic representation shown in FIG. 1 can also be transferred to other electrochemical energy converters, in particular electrolyzers. These have in principle the same structure and only often dispense with the channels 12, since in the electrolysis often no cooling is needed. However, it is also possible to operate a fuel cell 2 as an electrolyzer.

Fig. 2 shows schematically an electrochemical according to the invention

Energy converter 1, also shown in the form of a fuel cell stack, which comprises a plurality of fuel cells 2. The electrochemical energy converter 1 according to the invention differs from the conventional electrochemical energy converter 1 shown in FIG. 1 in that an electrically conductive material 30 is arranged in the contact region 20 between the surface of the gas diffusion layers 4 and 5 and the media distribution structures 6 and 7. The electrically conductive material 30 is preferably at least during the production of the electrochemical according to the invention

Energy converter 1 plastically deformable and also preferably has corrosion-inhibiting properties. The electrical conductivity of the electrically conductive material 30 is preferably at least 0.1 S / cm, more preferably at least 1 S / cm, and most preferably at least 10 S / cm, at 20 ° C. The electrically conductive material 30 comprises, for example, a polyolefin, in particular a polyethylene or polypropylene, having a weight-average molecular weight Mw of from 1000 g / mol to 100,000 g / mol (measured with

Gel permeation chromatography in trichlorobenzene against a polystyrene standard), which 10 to 85 wt .-%, based on the total weight of the electrically conductive material 30, of copper particles with a medium

Particle size of 100 to 500 nm includes. This electrically conductive material 30 thus provides excellent electrical contact between the

Gas diffusion layers 4 and 5 and the media distribution structures 6 and 7 forth, by an intimate, planar contact at the contact areas 20, preferably at all contact areas 20, is formed. In addition, the electrically conductive material 30 is hydrophobic and forms by this property a corrosion-inhibiting coating, since the water which is formed during operation of the fuel cell in this, in the

Contact areas 20 can not come into contact with the surfaces of the gas diffusion layers 4 and 5 and / or the media distribution structures 6 and 7 and can corrode them.

The inventive electrochemical energy converter according to FIG. 2 can also be operated both as a fuel cell and as an electrolyzer. In the case of use as an electrolyzer, the channels 12, in which coolant flows through the energy converter, are not mandatory.

The invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, within the scope given by the claims a variety of modifications are possible, which are within the scope of expert action.

Claims

claims

An electrochemical energy converter (1) in which gases are generated and / or consumed, comprising at least one media distribution structure (6, 7) and at least one gas diffusion layer (4, 5), wherein at the contact regions (20) between the surface of the at least one media distribution structure (6, 7) and the surface of the at least one gas diffusion layer (4, 5) is formed a planar, electrically conductive contact.

2. Electrochemical energy converter (1) according to claim 1, wherein the

at least one media distribution structure (6, 7) and the at least one gas diffusion layer (4, 5) are made of different materials.

3. Electrochemical energy converter (1) according to claim 1 or 2, wherein the flat, electrically conductive contact is formed by a contacting agent.

4. Electrochemical energy converter (1) according to one of claims 1 to

3, wherein the electrically conductive contact on all

Contact areas (20) between the surface of the at least one media distribution structure (6, 7) and the surface of the at least one gas diffusion layer (4, 5) is formed.

5. Electrochemical energy converter (1) according to one of claims 1 to

4, wherein the electrically conductive contact is formed over the entire sum of the contact regions (20) between the surface of the at least one media distribution structure (6, 7) and the surface of the at least one gas diffusion layer (4, 5).

6. Electrochemical energy converter (1) according to one of claims 1 to 5, wherein the electrically conductive contact by an electrically conductive material (30) is formed.

7. Electrochemical energy converter (1) according to claim 6, wherein the

electrically conductive material (30) additionally has anti-corrosive properties.

8. An electrochemical energy converter (1) according to claim 6 or 7, wherein the electrically conductive material (30) comprises at least polymeric material.

9. A process for producing an electrochemical energy converter (1), the process comprising at least the following steps:

(I) providing at least one media distribution structure (6, 7) and

at least one gas diffusion layer (4, 5);

(ii) coating at least the regions of the at least one

Media distribution structure (6, 7) and / or the at least one

Gas diffusion layer (4, 5) with an electrically conductive, plastically deformable material, which after the joining of the at least one media distribution structure (6, 7) and the at least one gas diffusion layer (4, 5) in the electrochemical energy converter (1) the contact regions (20) form between the two; and

(iii) assembling the at least one media distribution structure (6, 7) and the at least one gas diffusion layer (4, 5) so as to produce a planar, electrically conductive contact between the at least one media distribution structure (6, 7) and the at least one

Gas diffusion layer (4, 5) to be achieved, which is formed by the at least one electrically conductive, plastically deformable material, the assembly may optionally take place under the action of elevated pressure and / or elevated temperature.

10. Use of an electrochemical energy converter (1) according to any one of claims 1 to 8 or an electrochemical energy converter, obtained by a process according to claim 9, for the conversion chemical energy into electrical energy and / or for converting electrical energy into chemical energy.