DE102020207918A1 - Fuel cell assembly and method for manufacturing a fuel cell assembly - Google Patents

Abstract

The invention relates to a fuel cell arrangement (10) with fuel cells (20) stacked in a stacking direction (z), which extend in plate form in first and second transverse directions (x, y) and each have: a bipolar half plate (22) with a channel structure ( 24) for carrying a fuel; a gas diffusion layer (26); a membrane-electrode unit (28) having an electrolyte membrane (30) and electrode layers (32, 34) arranged on both sides thereof; another gas diffusion layer (36); a further bipolar half-plate (38) with a channel structure (40) for guiding the oxidant, which is open on two opposite sides in the first transverse direction (x) in order to allow an oxidant flow in the first transverse direction (x) through the fuel cell arrangement (10 ) to allow. According to the invention, each of the fuel cells (20) has a seal (50) on at least one of two opposite sides in the second transverse direction (y) in its lateral edge region, which is attached to the bipolar half plates (22, 38) and the membrane electrodes - the unit (28) rests, the seals (50) each protruding in the second transverse direction (y) over lateral edges (23, 39) of the bipolar half-plates (22, 38) and embracing these edges (23, 39) in such a way, that the seals (50) of fuel cells (20) that are adjacent to one another in the stacking direction (z) bear against one another.

Description

The present invention relates to a fuel cell arrangement according to the preamble of claim 1 and a method for producing a fuel cell arrangement according to the preamble of claim 7.

Such a fuel cell arrangement is also referred to as a fuel cell stack in the prior art and has fuel cells stacked in a stacking direction, each of which is plate-shaped and, viewed orthogonally to the stacking direction, extends in a first transverse direction and a second transverse direction orthogonal thereto.

• - eine anodenseitige Bipolar-Halbplatte mit einer Kanalstruktur zur Führung eines Brennstoffes,
• - eine anodenseitige Gasdiffusionslage,
• - eine Membran-Elektroden-Einheit, aufweisend eine Elektrolytmembran und in Stapelrichtung beiderseits davon angeordnete Elektrodenschichten, die eine Anode und eine Kathode für eine elektrochemische Reaktion des Brennstoffes mit einem Oxidationsmittel ausbilden,
• - eine kathodenseitige Gasdiffusionslage,
• - eine kathodenseitige Bipolar-Halbplatte mit einer Kanalstruktur zur Führung des Oxidationsmittels.

The individual fuel cells each have, stacked in the stacking direction:

• - an anode-side bipolar half-plate with a channel structure for guiding a fuel,
• - a gas diffusion layer on the anode side,
• - A membrane-electrode unit, comprising an electrolyte membrane and electrode layers arranged on both sides thereof in the stacking direction, which form an anode and a cathode for an electrochemical reaction of the fuel with an oxidizing agent,
• - a cathode-side gas diffusion layer,
• - A cathode-side bipolar half-plate with a channel structure for guiding the oxidizing agent.

For the state of the art of such fuel cell stacks, refer to the publications as an example EP 2 357 698 B1 , EP 2 445 045 B1 , EP 2 584 635 B1 , EP 2 946 431 B1 and EP 3 316 377 A1 referenced.

With a fuel cell arrangement, the chemical reaction energy of a continuously supplied fuel (e.g. hydrogen) and a continuously supplied oxidizing agent (e.g. oxygen or air) can be converted into electrical energy by means of an electrochemical reaction.

During operation of the fuel cells arranged in an electrical series connection via the (electrically conductive) bipolar half-plates, the reactants of the electrochemical reaction, i.e. the fuel (e.g. hydrogen) and the oxidizing agent (e.g. air), must be different when viewed in the stacking direction Sides of the membrane-electrode assembly are fed within each fuel cell.

For this purpose, the bipolar half-plates of each fuel cell are each designed with the above-mentioned channel structure on their sides facing the membrane-electrode unit in order to transfer the fuel and the oxidizing agent on the respective sides of the membrane-electrode unit via these channel structures into the there to introduce adjacent respective gas diffusion layer and thus to bring it up to the respective electrode layer on the corresponding side of the electrolyte membrane via the respective gas diffusion layer.

The electrode layers are usually formed from a carbon material and coated or interspersed with a suitable catalyst. The electrode layer on the fuel side forms an anode and the electrode layer on the oxidizing agent side forms a cathode of the membrane-electrode unit.

In a fuel cell arrangement of the type of interest here, in the individual fuel cells, the channel structure provided for guiding the oxidant is open on two opposite sides of the fuel cell viewed in the first transverse direction in order to enable the oxidant to flow through the fuel cell arrangement in the first transverse direction during operation .

In such a fuel cell arrangement, the oxidizing agent can be driven through the fuel cell arrangement in the first transverse direction, for example with a fan, and at the same time ensure cooling of the fuel cell arrangement. In one embodiment, air (e.g. from the environment) is supplied via the channel structure of the cathode-side bipolar half-plate or flows through this channel structure and thus serves both as an oxidizing agent and a coolant (air-cooled fuel cell stack).

In this regard, this arrangement can also be referred to as “fuel cells with an open cathode”, since the area carrying the oxidizing agent, i.e. the channel structure on the cathode side, gas diffusion layer, electrode layer (cathode) are not sealed off from the environment. Rather, only the (anode-side) fuel-carrying area is sealed against the environment in order to prevent a loss of fuel from this fuel cell area into the environment and an entry of a medium (e.g. air) from the environment into this fuel cell area.

The product of the electrochemical reaction taking place in the individual fuel cells, for example water, can be discharged via the fuel cell area carrying the oxidizing agent (for example air).

All of the features of fuel cell assemblies explained above with reference to the prior art can also be provided individually or in any combination in the fuel cell assembly according to the invention described below.

A disadvantage of known fuel cell arrangements of the type mentioned at the beginning is that when they are used or in their installation environment (e.g.

Fuel cell stacks in a housing) often no special seal is provided between an inlet side and an outlet side for the oxidizing agent (e.g. air), with the result that parasitic oxidizing agent flows e.g. B. flow from the inlet side to the outlet side and thus worsen the system efficiency of the fuel cell arrangement.

Another disadvantageous consequence in this context is that a so-called pressure charging of the stacked fuel cells, which increases the energy conversion efficiency and the cooling efficiency, in order to create an increased pressure of oxidizing agent in the fuel cells with a high flow rate at the same time, is made more difficult, since the aforementioned parasitic oxidizing agent flows are undesirable Way the pressure on the outlet side is increased.

Finally, there is another disadvantage e.g. B. in the fact that the fuel cells or the fuel cell stack formed therefrom cannot (at least in some areas) be introduced gas-tight and electrically insulated into a housing surrounding the stacked fuel cells. It should be noted here that the fuel cell stack does not have any “smooth” side surfaces and that the bipolar half-plates are made from an electrically conductive material.

It is an object of the present invention to avoid the disadvantages mentioned above and, in the case of a fuel cell arrangement of the type mentioned at the beginning, to expand its field of application and / or to improve its performance properties during operation.

According to the invention, this object is achieved according to a first aspect by a fuel cell arrangement according to claim 1. The dependent claims relate to advantageous developments of the invention.

The fuel cell arrangement according to the invention is characterized in that each of the fuel cells on at least one of two sides of the fuel cell arrangement which are opposite to one another when viewed in the second transverse direction also has a seal in its corresponding lateral edge area, which in this lateral edge area is attached to the anode-side bipolar half-plate and the cathode-side Bipolar half-plate and the membrane-electrode-unit rests in order to seal from the anode-side bipolar-half-plate to the membrane-electrode-unit and from the membrane-electrode-unit to the cathode-side bipolar half-plate, and that these seals in each case in the second Project transversely over lateral edges of the bipolar half-plates and encompass these lateral edges in such a way that the seals of fuel cells adjacent to one another in the stacking direction rest against one another.

The seals protruding beyond the lateral edges of the bipolar half-plates in the second transverse direction and in particular their contact with seals adjacent to each other in the fuel cell stack leads to a common enveloping sealing structure formed by the seals on the two relevant sides of the fuel cell assembly, which has many advantages.

So with the invention z. B. the mentioned parasitic air currents can be avoided. This sealing structure thus advantageously improves the performance properties of the fuel cell arrangement, in particular in the case of operation with pressure charging of the fuel cell stack. In addition, an electrical insulation between the fuel cell stack and a component surrounding the fuel cell stack in the installation environment, such as in particular z. B. a housing can be created. Furthermore, improved mechanical stability of the fuel cell stack in a housing can advantageously be achieved by means of seals formed from elastic material, which z. B. is particularly advantageous for mobile applications (in a vehicle).

The individual fuel cells preferably each have a plate-like shape with an at least approximately rectangular contour, so that a corresponding roughly cuboid fuel cell stack results.

In one embodiment, the fuel cells of the fuel cell arrangement are designed to be suitable for operation with hydrogen as the fuel, e.g. B. with an electrolyte membrane designed as a proton conducting membrane.

Alternatively, however, also z. B. a design of the fuel cell assembly for operation with a different fuel such. B. an organic compound (z. B. methane or methanol) or z. B. natural gas into consideration.

In one embodiment, the fuel cell arrangement is designed to be suitable for operation with air as the oxidizing agent, in particular with air (e.g. from the environment) actively guided (e.g. by means of a fan) through the channel structures of the cathode-side bipolar half-plates also as Coolant is used to cool the individual fuel cells and thus the fuel cell arrangement.

In a preferred use of the fuel cell arrangement, operation with pressure charging of the fuel cell stack with the oxidizing agent is provided, in which case the oxidizing agent is supplied under a pressure higher than atmospheric ambient pressure (supply pressure) on an inlet side for the oxidizing agent. This inlet pressure can e.g. B. greater than 1.2 bar, in particular greater than 1.5 bar, be dimensioned. On the other hand, in the case of pressure charging, an inlet pressure of less than 5 bar, in particular less than 4 bar, is usually sufficient.

In a more specific embodiment, the oxidizing agent is discharged at an outlet side at which there is a negative pressure that is below the ambient atmospheric pressure. This outlet pressure can e.g. B. less than 0.8 bar, in particular less than 0.6 bar, be dimensioned. On the other hand, an outlet pressure of at least 0.1 bar, in particular at least 0.2 bar, is usually advantageous.

The channel structures of the individual fuel cells provided in the context of the invention can each have several, e.g. B. more than 10, or z. B. have more than 50, parallel channels.

Each of the channel structures can e.g. B. in particular each have rectilinear and parallel channels, which z. B. in particular for the anode-side channel structures (on the anode-side bipolar half-plates) represents a preferred embodiment. In particular, the channels of the anode-side bipolar half-plates can, for. B. all run oriented in the first transverse direction.

In one embodiment, straight channels of the anode-side bipolar half-plates and the cathode-side bipolar half-plates all run in a common (same) direction orthogonal to the stacking direction of the fuel cell arrangement. In another embodiment, such straight channels run on the one hand the anode-side bipolar half-plates and on the other hand the cathode-side bipolar half-plates in different directions orthogonal to the stacking direction. In particular, these different directions of the channels can be provided oriented orthogonally to one another and thus z. B. extend in the first or second transverse direction.

As an alternative to rectilinear channels, more complicated courses of the respective channels can in principle also be provided for the anode-side channel structures and / or the cathode-side channel structures, such as, for. B. Gradients containing bends and / or curvatures, z. B. meandering courses in the "fuel cell plane" spanned by the first and second transverse directions. This can e.g. B. represent a preferred embodiment in particular for the cathode-side channel structures (on the cathode-side bipolar half-plates).

The channels of the channel structures can, for. B. have a rectangular or rounded-rectangular cross-section and can, for. B. have been formed by milling, punching, embossing or etching in the course of manufacturing the bipolar half-plates or bipolar plates.

In one embodiment, the bipolar half-plates are formed from a metallic material. Alternatively, the bipolar half-plates can in particular, for. B. of a carbon material or z. B. be formed from an electrically conductive plastic material (z. B. appropriately doped, z. B. With carbon black), or from another electrically conductive material.

According to one embodiment, the bipolar half-plates provided in the invention are each prefabricated separately from one another and inserted into the stack during the production of the fuel cell arrangement by stacking the individual components.

Mostly preferred, however, is an embodiment in which the bipolar half-plates for the interior of the fuel cell stack are each prefabricated separately from one another, but have been connected to one another in pairs before they are inserted into the fuel cell assembly, e.g. B. by gluing or welding, so that bipolar plates are used in the manufacture of the fuel cell stack (which are each composed of two bipolar half-plates). In this embodiment, too, individual bipolar half-plates (“end plates”) can be arranged at the two ends viewed in the stacking direction.

In the interior of the fuel cell stack, in the case of the individual fuel cells, an outside (ie the side facing away from the channel structure) of the anode-side bipolar half-plate z. B. directly on an outside (ie facing away from the channel structure) of the cathode-side bipolar half-plate of an adjacent (adjoining) in the stacking direction The fuel cell, with the outside of the cathode-side bipolar half-plate of a fuel cell correspondingly in contact with the outside of the anode-side bipolar half-plate of an adjacent fuel cell in the stacking direction (be it with or without a fixed connection such as gluing, welding, etc.).

In the context of the invention, however, it should not be ruled out that between such adjacent bipolar half-plates in the stack, for. B. another channel structure for guiding a cooling medium (z. B. cooling water) is formed.

In one embodiment, the gas diffusion layers are formed from a carbon fleece. Alternatively, depending on the intended fuel and oxidizing agent, other materials can also be considered.

In one embodiment, the anode and cathode forming electrode layers of the membrane-electrode unit of the fuel cells with a catalyst such as in particular z. B. coated a material containing platinum or palladium. The electrode layers can have the catalyst in particular on their side facing the associated gas diffusion layer.

As already mentioned, in the invention the seals are provided in the relevant lateral edge regions of the fuel cells on one or both of the opposite sides of the fuel cell arrangement viewed in the second transverse direction, the seals of adjacent fuel cells in the stacking direction bearing against one another.

In one embodiment of the invention, the seals are formed from an elastic plastic material. The material of the seals is preferably a permanently elastic material, whereby in this case too, in particular, it is possible to apply the material for forming the seals in a liquid to viscous state during the production of the fuel cell arrangement and then to harden it (in the preferably permanently elastic state). In one embodiment, the seals are formed from a polymer material.

In one embodiment of the fuel cell arrangement, the seals on the at least one relevant side (the two opposite sides in the second transverse direction) of the fuel cell arrangement are designed and arranged in such a way that a seal is achieved on the relevant side which prevents it from operating the fuel cell arrangement or at least prevents the oxidizing agent (e.g. air), which flows on an inlet side of the fuel cell arrangement provided for the oxidizing agent to openings in the channel structures for the oxidizing agent, parasitically in part also laterally past the stacked fuel cells and thus to an outlet side can.

The inlet side of the fuel cell arrangement provided for the oxidizing agent can be formed by a spatial region which directly adjoins the fuel cell stack at an end of the fuel cell stack viewed in the first transverse direction. In this area z. B. a fan for supplying oxidizing agent can be arranged in the fuel cell stack. In addition, this spatial area can also be delimited by a channel-like structure for guiding the oxidizing agent, in which case a fan supplying the oxidizing agent can also be arranged elsewhere within this channel-like structure. The channel-like structure can, for. B. be formed by a provided for accommodating the fuel cell stack housing or z. B. be connected to an inlet opening of such a housing provided for the oxidizing agent.

The seals are preferably formed and arranged on both sides of the fuel cell arrangement that are opposite to one another in the second transverse direction, so that the aforementioned seal is particularly advantageously achieved on both sides and thus, on an inlet side, oxidant flowing towards openings in the channel structures for the oxidant does not occur on either of the two Sides of the fuel cell stack can flow around this parasitically up to the outlet side.

The outlet side for the oxidizing agent is located in a space area adjoining one side of the fuel cell stack, which, viewed in the first transverse direction, is opposite to the inlet area. As an alternative or in addition to a fan on the inlet side, a fan can also be provided on the outlet side, that is to say in the outlet-side spatial area or an outlet-side channel-like structure, this structure again e.g. B. can be formed by a housing of the fuel cell assembly or z. B. can be connected to it.

In one embodiment, the fuel cell arrangement furthermore has a housing which at least partially surrounds the stacked fuel cells and on the inside of which the seals rest. The housing can e.g. B. represent or at least have a frame structure by means of which the stacked arrangement of the fuel cells together with the seals is fixed.

The housing can be formed from an electrically conductive material, in particular a metallic material, and an electrically insulating material of the seals can provide electrical insulation between the fuel cells and the housing.

The housing can e.g. B. be composed of several housing parts that were connected to one another during the manufacture (assembly) of the fuel cell assembly.

The housing can surround the stacked fuel cells at least on one or on both sides of the fuel cell arrangement which are opposite to one another when viewed in the second transverse direction. On the respective pages, z. B. extend a plate-shaped housing part and z. B. full surface on the seals. Alternatively, such a housing part z. B. be provided with openings and z. B. as a "shape-giving structure" only in places on the seals in order to fix them and / or to keep them in a certain shape by a contact force.

On each of the sides in question, the seals are arranged in a space which is delimited by the fuel cell in question and an inside of the housing and the seals that are adjacent (in the stacking direction).

It is particularly preferred here if, viewed in a cross section of each such spatial area, there are “no gaps in the seal”, ie. H. the material of the seals completely fills this cross-section.

In a preferred embodiment, the seals are made of elastic material and the seals on the relevant side (the opposite sides when viewed in the second transverse direction) of the fuel cell arrangement are compressed in the space that is delimited by the relevant fuel cell and the inside of the housing and the neighboring seals. In this way, the aforementioned gaps in the seal can advantageously be avoided.

In the finished state of the fuel cell assembly, e.g. B. after tensioning the stacked fuel cells between two so-called end plates and / or arrangement of a housing frame or housing, the seals can, for. B. be loaded by compression forces that act in the second transverse direction and / or in the stacking direction.

In one embodiment of the invention, the seals are designed in such a way that, in particular even without the action of compression forces (e.g. caused by tensioning the fuel cell stack), the arrangement of the seals already has essentially “no seal gaps” when viewed in cross section.

In one embodiment of the invention, the seals are designed in such a way that the seals of fuel cells which are adjacent to one another in the stacking direction bear against one another, forming a form-fit connection. In particular, the seals can here, for. B. be provided with projections oriented in the stacking direction and corresponding depressions, so that the projections engage in the corresponding depressions (“tongue and groove connection”).

In one embodiment of the invention, the seals protrude in the second transverse direction over the lateral edges of the bipolar half-plates by an amount that is at least 0.25 times, in particular at least 0.5 times, a thickness measured in the stacking direction Fuel cells is, and / or a maximum of 10 times, in particular a maximum of 5 times, the thickness of the fuel cells measured in the stacking direction.

According to a further aspect, the invention relates to a method for producing a fuel cell arrangement, which comprises: Forming a fuel cell arrangement by stacking fuel cells in a stacking direction, the fuel cells each being plate-shaped, viewed orthogonally to the stacking direction, each in a first transverse direction and one to it extend in the orthogonal second transverse direction, and the fuel cells each have stacked in the stacking direction: an anode-side bipolar half-plate with a channel structure for guiding a fuel; an anode-side gas diffusion layer; a membrane-electrode unit, comprising an electrolyte membrane and electrode layers arranged on both sides thereof in the stacking direction, which form an anode and a cathode for an electrochemical reaction of the fuel with an oxidizing agent; a cathode-side gas diffusion layer; and a cathode-side bipolar half-plate with a channel structure for guiding the oxidizing agent, which is open on two opposite sides of the fuel cell, viewed in the first transverse direction, in order to enable a flow of the oxidizing agent in the first transverse direction through the fuel cell arrangement.

According to the invention, it is provided in this production method that each of the fuel cells is located on at least one of two opposite sides of the fuel cell arrangement as viewed in the second transverse direction its corresponding lateral edge area furthermore has a seal which, in this lateral edge area, rests against the anode-side bipolar half-plate, the cathode-side bipolar half-plate and the membrane-electrode unit in order to move from the anode-side bipolar half-plate to the membrane-electrode unit from the membrane-electrode unit to the cathode-side bipolar half-plate, and that the seals protrude in the second transverse direction over the lateral edges of the bipolar half-plates and encompass these lateral edges in such a way that when the fuel cells are stacked, the seals from in Stack direction adjacent fuel cells come to rest against each other.

In one embodiment, the seals are each formed in one piece. Alternatively, it is possible to form the seals composed of several sealing parts. Each seal or each sealing part can e.g. B. during the stacking arrangement of the fuel cells as an "insert" in the corresponding lateral edge area are "stacked". Alternatively, each seal (or, for example, all of the sealing parts provided for forming a seal) can be designed as part of a prefabrication of the further fuel cell components and connected directly to the fuel cell component (s) concerned, in particular e.g. B. to form before these fuel cell components are stacked to form the fuel cell stack.

For example, the seal can be provided in one piece and molded onto the relevant lateral edge or edges of the membrane-electrode unit. Another possibility would be e.g. B. a two-part design of the seal, the two sealing parts are each formed on a bipolar half-plate (which represent the anode-side and cathode-side bipolar half-plate after stacking).

In one embodiment of the production method, this also includes the introduction of the fuel cell stack formed by the stacking arrangement of the fuel cells into a housing in such a way that the seals come to rest against the inside of the housing.

In one embodiment, the seals are compressed by accommodating or introducing the fuel cells or the stack formed from the fuel cells into the housing, preferably in such a way that a sealing effect of the seals resting against one another is further improved by this compression, in particular z . B. the aforementioned "sealing gaps" are closed.

• 1 eine Schnittansicht einer Brennstoffzelle gemäß eines Ausführungsbeispiels,
• 2 eine Schnittansicht einer Brennstoffzellenanordnung aus gestapelt angeordneten Brennstoffzellen des in 1 gezeigten Beispiels,
• 3 eine Schnittansicht einer in einem Gehäuse untergebrachten Brennstoffzellenanordnung des in 2 gezeigten Beispiels, und
• 4 eine Schnittansicht einer Brennstoffzellenanordnung gemäß eines weiteren Ausführungsbeispiels.

The invention is further described below on the basis of exemplary embodiments with reference to the accompanying drawings. They each show schematically:

• 1 a sectional view of a fuel cell according to an embodiment,
• 2 a sectional view of a fuel cell arrangement of stacked fuel cells of the FIG 1 example shown,
• 3 a sectional view of a housing accommodated in a housing fuel cell arrangement of FIG 2 example shown, and
• 4th a sectional view of a fuel cell arrangement according to a further embodiment.

1 shows a fuel cell 20th to convert the chemical reaction energy of a supplied fuel, in the example hydrogen, and a supplied oxidizing agent, in the example air, into electrical energy.

The fuel cell 20th is plate-shaped and extends in a plate plane of this shape in a first transverse direction x and a second transverse direction y orthogonal thereto.

The direction orthogonal to the plate plane spanned by the transverse directions x, y is referred to as the stacking direction z.

One below (with reference to the 2 and 3 ) described fuel cell arrangement 10 is made up of several fuel cells stacked in this stacking direction z 20th formed, each fuel cell 20th is composed in each case of a plurality of plate-shaped shaped and stacked components arranged in the stacking direction z.

It is initially a bipolar half-plate on the anode side 22nd , on the inside (ie the inside of the fuel cell 20th facing side) a channel structure 24 is designed to guide the fuel (hydrogen). Via the bipolar half-plate made of electrically conductive material (e.g. metal) 22nd is in operation of the fuel cell 20th generated electric current dissipated.

On the inside of the bipolar half-plate 22nd and thus on the channel structure 24 adjacent is an electrically conductive gas diffusion layer permeable to the fuel 26th (z. B. carbon fleece) provided over which the fuel in operation of the fuel cell 20th to a membrane-electrode unit adjoining it in the stacking direction z 28 got.

The membrane-electrode unit 28 comprises an electrically non-conductive, proton-conductive electrolyte membrane 30th and, viewed in the stacking direction z, arranged on both sides thereof, electrically conductive and with a catalyst 35 (e.g. platinum or palladium) coated electrode layers 32 and 34 (e.g. made of metal). The electrode layer 32 forms the anode and the electrode layer 34 forms the cathode for an electrochemical reaction of the fuel (hydrogen) with the oxidizing agent (air).

In operation of the fuel cell 20th becomes the fuel (hydrogen) based on the channel structure 24 via the gas diffusion layer on the anode side 26th to the electrode layer 32 (Anode) brought up.

The oxidizing agent (air) is attached to the electrode layer via a 34 (Cathode) adjoining cathode-side gas diffusion layer 36 to this electrode layer 34 introduced.

In the stacking direction z to this electrically conductive gas diffusion layer permeable to the oxidizing agent 36 adjacent is an electrically conductive cathode-side bipolar half-plate 38 provided, on the inside of which a channel structure 40 is designed to guide the oxidizing agent. The bipolar half-plate 38 is used when the fuel cell is in operation 20th on the cathode side, it is also used to remove the from the fuel cell 20th generated electric current.

A first specialty of the fuel cell 20th is that the oxidizing agent-carrying channel structure 40 on two opposite sides of the fuel cell viewed in the first transverse direction x 20th is open to a flow of the oxidizing agent in the first transverse direction x through the channel structure 40 to allow through. In accordance with the schematic representation of the channel structure 40 in 1 this oxidizing agent-carrying channel structure exists 40 of oxidizing agent channels running parallel to one another in the first transverse direction x and in particular in each case in a straight line parallel to one another (for example more than 10, in particular more than 50 channels per fuel cell 20th ). It then results for each fuel cell 20th a corresponding number of inlet openings of these channels on one inlet side (in 1 z . B. above the plane of the drawing) and a corresponding number of outlet openings on one outlet side (in 1 z . B. below the plane of the drawing).

After stacking several such fuel cells 20th to form a fuel cell stack (cf. 2 and 3 ), forms a space adjacent to the entirety of the inlet-side channel openings of the channel structures 40 the fuel cells 20th an inlet side of the fuel cell assembly 10 and a space region adjoining the entirety of their outlet-side channel openings, an outlet side of the fuel cell arrangement 10 .

In contrast, the fuel-carrying channel structures are 24 on either side of the fuel cell assembly 10 open, but rather towards an environment from the fuel cells 20th formed stack sealed. In order to operate the fuel cells 20th the channel structures 24 to supply or to flow through, has the fuel cell arrangement 10 at least one fuel inlet and at least one fuel outlet, each of which via openings (passage openings) in the individual fuel cells which are arranged congruently in the xy plane 20th with the individual channel structures 24 are connected. In this way, for the fuel cell assembly 10 at least one in the stacking direction z through the fuel cell arrangement 10 running fuel supply channel and at least one in the stacking direction z through the fuel cell arrangement 10 running fuel discharge channel can be formed by inlet passage openings and outlet passage openings arranged congruently in each case in the xy plane (not shown in the figures).

A second specialty of the fuel cell 20th or by stacking such fuel cells 20th formed fuel cell assembly 10 is that each of the fuel cells 20th on at least one of two opposite sides of the fuel cell arrangement viewed in the second transverse direction y 10 a seal in its corresponding lateral edge area 50 has, in this lateral edge area on the anode-side bipolar half-plate 22nd , the cathode-side bipolar half-plate 38 and the membrane-electrode assembly 28 is applied to from the anode-side bipolar half-plate 22nd to the membrane electrode unit 28 to and from the membrane-electrode assembly 28 to the cathode-side bipolar half-plate 38 to seal, and that these seals 50 each in the second transverse direction y over lateral edges 23 , 39 of the bipolar half plates 22nd , 38 stick out and those side edges 23 , 39 in such a way (and at least partially) that the seals 50 of fuel cells adjacent to one another in the stacking direction z 20th rest against each other.

2 illustrates the fuel cell assembly 10 made by stacking fuel cells 20th ( 1 ) was formed in the stacking direction z.

To distinguish the fuel cells 20th in this fuel cell stack are in 2 the individual fuel cells 20th according to their Arrangement in the stack with 20-1, 20-2, ... and the associated seals 50 ( 1 ) in 2 denoted by 50-1, 50-2, ...

In the example of the fuel cell 20th according to 1 is the poetry 50 formed in one piece and extends here in strips in the first transverse direction x z. B. over the entire length of the corresponding lateral edge area (in 1 Left).

The electrolyte membrane protrudes in this lateral edge area 30th in the second transverse direction y over the side edges of the adjacent gas diffusion layers 26th , 36 out, being at the protruding portion of the electrolyte membrane 30th a so-called sub-seal 42 is provided in the example during the prefabrication of the membrane-electrode unit 28 was trained as part of the same.

The one-piece seal 50 lies in the in 1 shown lateral edge area of the fuel cell 20th on the inside of the bipolar half-plates 22nd , 38 and on the subgasket 42 the membrane electrode assembly 28 on. The seal 50 thus seals both from the anode-side bipolar half-plate 22nd to the membrane electrode unit 28 to and from the membrane-electrode unit 28 to the cathode-side bipolar half-plate 38 down. Deviating from the in 1 In the example shown, the subgasket (which in conventional fuel cell arrangements also serves as a holding frame for the membrane-electrode unit) could also be omitted.

Out 1 can also be seen as the seal 50 in the second transverse direction y, in 1 to the left, over the side edges 23 (the bipolar half-plate 22nd ) and 39 (of the bipolar half-plate 38 ) protrudes and these side edges 23 , 39 partially encompassed. The seal 50 is therefore on the in 1 Outside of the fuel cell shown on the left 20th , ie over the side edges 23 , 39 addition, expanded, with the partial encirclement of these margins 23 , 39 the two ends of the seal 50 viewed in the stacking direction z, a little over the bipolar half-plates 22nd , 38 survive (in 1 up and down).

This “difference in height” between the outer end faces of the bipolar half-plates on the one hand 22nd , 38 and on the other hand the ends of the seal 50 Viewed in the stacking direction z ensures that in the fuel cell arrangement 10 how out 2 can be seen the seals 50-1 , 50-2 , ... of the fuel cells adjacent to one another in the stacking direction z 20-1 , 20-2 , ... lie against each other.

On the in 2 not shown, in the second transverse direction y opposite side of the fuel cell arrangement 10 is the fuel cell assembly 10 preferably designed in a way that corresponds to the design of the in 2 corresponds to the side shown on the left, ie there are also provided (mirror-inverted) seals.

In the example according to the 1 and 2 the lateral protrusion of the seals leads 50-1 , 50-2 , ... to one on the corresponding side of the fuel cell assembly 10 trained, the stacked fuel cells 20th on this side to a certain extent enveloping sealing structure, through which z. B. parasitic oxidant flows from the inlet side past the fuel cell stack to the outlet side can advantageously be suppressed. In addition, this sealing structure advantageously makes one on the relevant side of the fuel cell arrangement 10 effective electrical insulation formed.

These advantages come into full effect once the in 2 fuel cell stack shown in a corresponding installation environment, such as in 3 illustrated.

3 FIG. 3 shows the fuel cell stack of FIG 2 in one housing 60 housed so that the seals 50-1 , 50-2 , ... in the corresponding area (in 3 left) on the inside of the housing 60 issue. This in 3 housing shown schematically 60 can in practice be made in one piece or preferably in several parts (composed of several housing parts).

In the case of the housing 60 having fuel cell assembly 10 in 3 are the seals made of electrically insulating, elastic material 50-1 , 50-2 , ... as far as it is compressed, ie mechanically on the one hand by the housing 60 and on the other hand by the fuel cells 20-1 , 20-2 , ... loaded so that each of the seals over the entire surface on the one hand on the respective edges of the bipolar half-plates and on the other hand on a relevant inner side section of the housing 60 issue.

In this way, an advantageous separation (sealing) of spaces can be achieved on the one hand on the supply side (inlet side) and on the other hand on the discharge side (outlet side) of the fuel cell stack. With such a fuel cell arrangement according to the invention 10 can also be advantageous for. B. an inlet-side pressure and an outlet-side pressure of the oxidizing agent can be set independently of one another without parasitic oxidizing agent flows around the fuel cell stack causing a tendency to equalize the pressure between the inlet side and the outlet side.

If the electrically conductive housing 60 like in 3 shown above also on one or both ends of the fuel cell stack viewed in the stacking direction z, so can, for. B. by inserting an insulation layer 61 As shown, the relevant "end plates" (top and bottom bipolar half-plates in the stack) are electrically isolated from the housing 60 be ensured.

In one embodiment, the housing is 60 composed of at least two housing parts, of which a first housing part is one (in 3 shown) first side wall (at one end of the fuel cell arrangement viewed in the second transverse direction 10 ) and a second housing part one (in 3 not shown) forms the second side wall, which is arranged opposite the first side wall. In the context of the invention, such housing parts can be advantageous when assembling the fuel cell arrangement 10 z. B. connected to each other and / or to other housing parts (e.g. screwed or welded).

Out 3 is another advantage of the fuel cell assembly 10 can be seen, which consists in the fact that the avoidance of an undesired flow of oxidizing agent laterally past the fuel cell stack does not result in a tightness of the housing 60 even in the relevant side wall section of the housing 60 required, as the required seal is already provided by the seals resting against one another 50-1 , 50-2 , ... is achieved. The case 60 can therefore z. B. can easily be formed with openings or the like to reduce weight and material costs.

4th shows a fuel cell assembly 10 according to a further embodiment, in which two modifications compared to the example of 3 are made.

A first modification is that the seals 50-1 , 50-2 , ... are designed in such a way that the arrangement of the seals even without the action of compression forces 50-1 , 50-2 , ... in cross section ( 4th ) already essentially has "no gasket gaps" (e.g. in contrast to the one in 2 shown arrangement 50-1 , 50-2 , ...). The in 4th apparent cross-section has at least at the lateral end (in 4th far left) up to the lateral edges of the bipolar half-plates, there are no such gaps.

A second modification is that the seals 50-1 , 50-2 , ... are designed in such a way that the seals 50-1 , 50-2 , ... of fuel cells adjacent to one another in the stacking direction z 20-1 , 20-2 , ... rest against one another with the formation of a respective form-fit connection. In the example of 4th are the seals 50-1 , 50-2 , ... provided with projections and corresponding recesses oriented in the stacking direction z, so that the projections engage in the corresponding recesses.

In the example, each of the seals has 50-1 , 50-2 , ... a protrusion and a recess (at the opposite ends in the stacking direction z). In a departure from this, a plurality of projections and corresponding depressions could also be provided on each seal, for example to form multiple toothed contact areas between adjacent seals 50-1 , 50-2 , ....

Deviating from the in 4th example shown could e.g. B. only the first or only the second of the modifications explained above can be provided.

Around the stacked arrangement of the fuel cells 20-1 , 20-2 , ... including the seals 50-1 , 50-2 , ... to stabilize or fix mechanically are in the example of 4th at both ends of the fuel cell arrangement viewed in the stacking direction z 10 so-called "end plates" are provided, of which in 4th one can be seen and is denoted by 62. The two end plates can be used during the assembly of the fuel cell stack z. B. be clamped to each other (z. B. by means of a screw connection).

The end plate 62 is (like each of the seals) provided with a projection oriented in the stacking direction z, which protrudes into the corresponding recess of the adjacent seal 50-1 intervenes. In the 4th End plate, not shown, at the opposite end of the fuel cell stack in this example would accordingly have to be provided with a recess into which a corresponding projection of the adjoining seal engages.

The in 4th (without a housing) shown fuel cell assembly 10 can still be provided with a housing, be it with or without exerting a compressive force from the housing on the seals 50-1 , 50-2 , ....

In a method for manufacturing a fuel cell assembly 10 the in 4th are shown in a stacking arrangement of the fuel cells 20-1 , 20-2 , ... the seals 50-1 , 50-2 , ... brought into contact with one another by fuel cells adjacent to one another in the stacking direction z, forming the form-fitting connections described above.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 2357698 B1 [0004]
• EP 2445045 B1 [0004]
• EP 2584635 B1 [0004]
• EP 2946431 B1 [0004]
• EP 3316377 A1 [0004]

Claims (8)

Fuel cell arrangement (10) comprising fuel cells (20) stacked in a stacking direction (z), the fuel cells (20) each being plate-shaped and viewed orthogonally to the stacking direction (z) in a first transverse direction (x) and an orthogonal to it in the second transverse direction (y), the fuel cells (20) each having, stacked in the stacking direction (z): - an anode-side bipolar half-plate (22) with a channel structure (24) for guiding a fuel, - an anode-side gas diffusion layer (26) - A membrane electrode unit (28), having an electrolyte membrane (30) and electrode layers (32, 34) arranged on both sides thereof in the stacking direction (z), the anode (32) and a cathode (34) for an electrochemical reaction of the fuel with an oxidizing agent, - a cathode-side gas diffusion layer (36), - a cathode-side bipolar half-plate (38) with a channel structure (40) for guiding the oxidizing agent, which is open on two opposite sides of the fuel cell (20), viewed in the first transverse direction (x), in order to allow the oxidizing agent to flow in the first transverse direction (x) through the fuel cell arrangement (10) enable, characterized in that each of the fuel cells (20) on at least one of two opposite sides of the fuel cell arrangement (10) viewed in the second transverse direction (y) furthermore has a seal (50) in its corresponding lateral edge region, which in this lateral edge area Edge area on the anode-side bipolar half-plate (22), the cathode-side bipolar half-plate (38) and the membrane-electrode unit (28) to move from the anode-side bipolar half-plate (22) to the membrane-electrode unit (28) to and from the membrane-electrode unit (28) to the cathode-side bipolar half-plate (38) to be sealed, and that the seals (50) each in d he second transverse direction (y) protrude over lateral edges (23, 39) of the bipolar half-plates (22, 38) and encompass these lateral edges (23, 39) in such a way that the seals (50) are adjacent to one another in the stacking direction (z) Fuel cells (20) rest against one another. Fuel cell assembly (10) according to Claim 1 wherein the seals (50) are provided in the relevant lateral edge regions of the fuel cells (20) on both of the opposite sides of the fuel cell arrangement (10) viewed in the second transverse direction (y). Fuel cell arrangement (10) according to one of the preceding claims, further comprising a housing (60) surrounding the stacked fuel cells (20) at least on the two opposite sides of the fuel cell arrangement (10) viewed in the second transverse direction (y), on the inside of which the The seals (50) are in contact. Fuel cell assembly (10) according to Claim 3 wherein the housing (60) is formed from an electrically conductive material, in particular a metallic material. Fuel cell arrangement (10) according to one of the preceding claims, wherein the seals (50) are designed in such a way that the seals (50) of fuel cells (20) adjacent to one another in the stacking direction (z) rest against one another, forming a form-fit connection. Fuel cell arrangement (10) according to one of the preceding claims, wherein the seals (50) each protrude in the second transverse direction (y) over the lateral edges (23, 39) of the bipolar half-plates (22, 38) by an amount that is at least that 0.25 times, in particular at least 0.5 times, a thickness of the fuel cells (20) measured in the stacking direction (z), and / or a maximum of 10 times, in particular a maximum of 5 times that measured in the stacking direction ( z) measured thickness of the fuel cells (20). Method for producing a fuel cell arrangement (10) according to one of the preceding claims, comprising - forming a fuel cell arrangement (10) by stacking fuel cells (20) in a stacking direction (z), the fuel cells (20) each being plate-shaped, orthogonally to the stacking direction (z) each extend in a first transverse direction (x) and a second transverse direction (y) orthogonal thereto, and the fuel cells (20) each stacked in the stacking direction (z) have: an anode-side bipolar half-plate (22) with a channel structure (24) for guiding a fuel; an anode-side gas diffusion layer (26); a membrane electrode unit (28), comprising an electrolyte membrane (30) and electrode layers (32, 34) arranged on both sides thereof in the stacking direction (z), the anode (32) and a cathode (34) for an electrochemical reaction of the fuel form with an oxidizing agent; a cathode-side gas diffusion layer (36); and a cathode-side bipolar half-plate (38) with a channel structure (40) for guiding the oxidizing agent, which is open on two opposite sides of the fuel cell (20) viewed in the first transverse direction (x) in order to allow the oxidizing agent to flow in the first Transverse direction (x) through the fuel cell arrangement (10) enable, characterized in that each of the fuel cells (20) on at least one of two opposite sides of the fuel cell arrangement (10) viewed in the second transverse direction (y) furthermore has a seal (50) in its corresponding lateral edge region, which in this lateral edge area Edge area on the anode-side bipolar half-plate (22), the cathode-side bipolar half-plate (38) and the membrane-electrode unit (28) to move from the anode-side bipolar half-plate (22) to the membrane-electrode unit (28) to and from the membrane-electrode unit (28) to the cathode-side bipolar half-plate (38), and that the seals (50) each in the second transverse direction (y) over the lateral edges (23, 39) of the bipolar half-plates (22, 38) protrude and encompass these lateral edges (23, 39) in such a way that when the fuel cells (20) are stacked, the seals (50) of B fuel cells (20) come to rest against one another. Procedure according to Claim 7 , further comprising introducing the fuel cell stack formed by the stacking arrangement of the fuel cells (20) into a housing (60) such that the seals (50) come to rest against the inside of the housing (60).

Images