WO2011141308A1

WO2011141308A1 - Fuel cell stack and method for producing a fuel cell stack

Info

Publication number: WO2011141308A1
Application number: PCT/EP2011/056919
Authority: WO
Inventors: Thomas Zeller; Christian Koerber; Bernhard Brüne
Original assignee: Trumpf Werkzeugmaschinen Gmbh + Co. Kg
Priority date: 2010-05-12
Filing date: 2011-05-02
Publication date: 2011-11-17
Also published as: DE102010028957A1

Abstract

The invention relates to a fuel cell stack (2) which comprises a plurality of successive membrane electrode units (5) along a stack axis (4) and medium guiding units (8, 9) arranged between the membrane electrode units (5) along the stack axis (4). At least two successive components (22) along the stack axis (4) of the fuel cell stack (2) are interconnected by means of an adhesive layer (23) consisting of a thermoplastic material or of a two- or multi-component adhesive and extending substantially across the entire stack cross-section. The invention further relates to a method for producing such a fuel cell stack (2).

Description

Fuel cell stack and method for producing a

Fuel cell 11 s sta pel s

The invention relates to a fuel cell stack, which

has at least two, along a stack axis successive media guide units and arranged along the stack axis between the media-guide units membrane electrode assembly. Furthermore, the invention relates to a method for producing a fuel cell stack.

Known fuel cell stacks usually comprise several

Fuel cells stacked along a stacking axis. The individual fuel cells each have at least one membrane electrode unit, which is enclosed on both sides of media-guide units, which the supply and distribution of the media (fuel gas, usually hydrogen, oxidant, usually air, and coolant) and the removal of gaseous reaction products (water vapor) and, in the case of superstoichiometric operation, also the reaction educts (air,

Hydrogen) and the heat of reaction by a coolant serve. In particular, conventional media-guiding units have this Purpose bipolar plates through which the process gases can diffuse and at the same time close the power generated. In the simplest case, a fuel cell stack forms a single fuel cell with a membrane-electrode assembly enclosed by two media guide units.

Fuel cell stacks include a variety of components that must be interconnected and sealed. Regardless of the type of construction, the connection points represent a special challenge during operation, because their functionality is functional and safety-relevant and they are subject to considerable thermal, mechanical, electrical and chemical loads. It is known for sealing individual components of the

Fuel cell stack to use compressible, pliable components or to shed the fuel cell stack in total. The handling of non-sluggish components in (partially) automated production processes, however, has a number of production-technical disadvantages.

It is also known to thermally interconnect individual components of the fuel cell stack by soldering or welding, wherein depending on the specific embodiment, the weld not only the connection, but also the seal can serve.

In US 2001/0001052 Al a fuel cell stack of the type mentioned is described. It consists of several membrane-electrode units as well as between the membrane-electrode units

arranged separating plates, which serve to supply the membrane electrode assemblies with the process gases and the circulation of a cooling medium. It is a system of PEM (proton exchange membrane) fuel cells. The fuel cell stack according to US 2001/0001052 A1 has sealing rings made of a thermoplastic material. The sealing rings made of thermoplastic material have the task of separating layers between individual components of the

Fuel cell stack, edge seal to the outside and at the same time to glue the components together. The individual components of the fuel cell stack are thus by means of the sealing ring only at the edges, ie to the outside, but not inside the

Fuel cell stack sealed and glued together.

In contrast, it is an object of the invention to develop a fuel cell stack and a method for producing a fuel cell stack in such a way that results in a fuel cell stack having a functionally reliable and easy to produce component connection.

According to the invention, the object is achieved by a

Fuel cell stack with the features of claim 1 and by a method for producing a fuel cell stack with the

Features of claim 15.

For the purposes of the invention, an adhesive layer consisting of thermoplastic or two-component or multi-component adhesive, which extends essentially over the entire stacked cross section, serves for

Connecting at least two consecutive components of the fuel cell stack. In the inventive manufacture of the

Fuel cell stack is the thermoplastic or the two- or multi-component adhesive at least on that side surface one of the components applied, which faces the other component in the stacked state.

In general, the stack cross-section of the fuel cell stack can vary along the stack axis. For simple and compact stacking constructions, the stacking cross-section is along the stacking axis

largely uniform. For example, the

Stacked section rectangular or square. The fuel cell stack is z. B. of a housing and other peripheral elements, such as. Process gas lines, power connections, etc., surrounded. For the purposes of the invention, the stacked cross-section of the fuel cell stack does not comprise the housing and the peripheral elements.

The adhesive layer of thermoplastic or two-component or multi-component adhesive extends over the entire, at the

Junction prevailing stack cross section, d. H. essentially, all are along the stacking axis at the junction

opposite or adjacent surface portions of the components by means of the thermoplastic or two- or

Multi-component adhesives existing adhesive layer with each other

connected. In particular, they are with each other

connected components to each other over a large area or adjacent components, so that the thermoplastic adhesive or consisting of two- or multi-component adhesive layer covers relatively large areas of the stack cross-section throughout. The

thermoplastic or of two- or multi-component adhesives

However, existing adhesive layer may well have recesses, holes, etc. If, for example, at least one of the components on the side surface, which faces the other component, a Has recess or the like, is in this area optionally on the thermoplastic or two- or

Mehrkomponentenkleber existing adhesive layer omitted.

Due to the invention, the components with a single Dichtbzw. Kiebemateriaf interconnected and sealed so that the fuel cell stack at the interface of the two components both in the edge areas and in the interior, d. H. over the entire stack cross section, is sealed.

Advantageously, the erfindungsmäße thermoplastic serves

Adhesive layer as a leveling layer for manufacturing tolerances of the other components, since the thermoplastic material can be added regardless of the manufacturing process at any time by heating in a plastic state, corrections z. B. regarding. The

Relativstellung the interconnected components are performed at any time. Since the flexibly adaptable, thermoplastic layer extends over the entire stack cross-section, a high density and strength of the joint remains even with larger

Changes in the relative position of interconnected by means of the adhesive layer components over the entire stack cross-section ensures away. Is for the adhesive layer a two- or

Used multi-component adhesive, the respective plastic components are applied separately to the facing components and then activated under contact and optionally pressure. Since the chemical reaction that takes place between the components of the two-component or multi-component adhesive and leads to sticking together of the components takes a certain amount of time, the components do not stick together immediately, but only together after a certain time. In this way, the adhesive layer consisting of two-component or multi-component adhesive adjusts itself to the shape of the respective components even in the plastic state and thus compensates for manufacturing tolerances without it having to be heated.

Moreover, the invention has the advantage that such a fuel cell stack can be produced inexpensively and in large quantities without a loss of quality in terms of sealing and

Adhesive properties must be accepted. The use of flexible components can be avoided in this way,

Furthermore, it is through the use of a thermoplastic

Plastic possible, the sealing or adhesive surfaces several times

melt and the individual components in this way reversibly separated from each other and then again

put together. That's not just in terms of advanced

Degrees of freedom in the design of manufacturing advantage, but especially in case of failure of a single component of such a fuel cell stack. In this way it is possible

Manufacture maintenance-friendly and recycling-friendly fuel cell stacks in a highly productive and cost-effective manner.

Advantageous developments of the invention will become apparent from the

Claims 2 to 14 and claims 16 and 18.

In a preferred embodiment of the invention, the adhesive layer consisting of the thermoplastic or two- or multi-component adhesives are provided with recesses through which at least one extends along the Stacking axis extending through the adhesive layer therethrough

Functional cavity results. The functional cavity is through the

thermoplastic or of two- or multi-component adhesives

existing adhesive layer sealed at least between the components and transversely to the stack axis circumferentially. By this measure results in a simple way to manufacture a reliable sealed

Function cavity. The functional cavity can be used in particular for

Serving media transport. Other uses are also conceivable.

A compact construction of a media-guide unit of a fuel cell stack according to the invention, which is characterized by a high density, results from the fact that the media-guide unit has a plurality of successive along the stack axis components, each by means of an adhesive layer of thermoplastic material or Two-component or multi-component are connected to each other, wherein the thermoplastic adhesive or consisting of two-component or multi-component adhesive layers extend substantially over the entire stack cross-section.

In particular, the components of the media-guide unit are connected to one another by means of the thermoplastic adhesive layers consisting of two-component or multicomponent calenders, with recesses or openings of the

Components in the interior of the media guide unit, a channel structure is formed, and wherein the channel structure at least between the

Components and transverse to the stack axis by the thermoplastic or consisting of two- or multi-component glue adhesive layers is sealed. Channels of the channel structure resulting in this way can be flexibly guided through the media guide unit without having to

Losses in terms of the tightness of the channels result.

In the case of an alternative Erfindungsbauart have means of a

thermoplastic or of two- or multi-component adhesive

existing adhesive layer interconnected components of a media-guide unit transformations, through which a channel structure is formed in the interior of the media-guiding unit. To name a few are imprints or bead-shaped transformations, resulting in structured components.

In a particularly preferred embodiment, the

Components formed thin surface. For example, the

Components as plates, foils or similar material layers

be educated.

Thin-surface components, in particular sheets, can be easily processed by mechanical, such as punching, or thermal processes, such as. Laser cutting. Machining methods such as milling, drilling or molding by injection molding can be largely avoided.

A cost-effective and manufacturing technology advantageous variant results when the thin-walled components are made of metal, that is, the components are formed in particular as sheets. Particularly preferred is an embodiment of the invention, in which the components or at least a part of the components of

Aluminum sheet are made. An advantage of aluminum sheet for use in the fuel cell stack are its low density, high electrical and thermal conductivity and its corrosion resistance through the passivatable surface. In addition, aluminum is easily machinable and thermally workable.

Preferably, the planar components are also at least largely flat or flat designed, d. H. they have at least largely no from the component level above forming, spacers, etc. on.

According to an independent aspect of the invention results in a

Fuel cell stack with a particularly compact-build media guide unit by the media-guiding unit several

thin-surface and planar components, in particular sheets, which lie flat against each other along the stacking axis, d. H. without

Spacers or the like are stacked on each other. In the interior of the media guide unit, a channel structure is formed by recesses of the components. This aspect of the invention is also without the use of thermoplastic or two- or

Multi-component adhesive for bonding the components independently advantageous. For example, the components may also be soldered together and otherwise connected and sealed together.

Thanks to such a structure of a media guide unit, the channel structure can be inside the compactly constructed media guide unit to be distinctly fiiigran and designed with a high degree of freedom with regard to geometric design. Through the channels of the filigree channel structure, the process gases, or the cooling medium, of the membrane-electrode unit are preferably added to or removed from the latter. The supply and removal of the process gases can be easily by means of such a structure by separate input or

Outflow channels take place. Further, it is possible by such a structure to supply the process gases in a simple manner at several points of the membrane-electrode unit such that even a large area can be supplied with gas evenly, avoiding impoverished zones in the reaction area and current peaks can be largely prevented , High reaction concentrations are also avoided, so that a uniform use of the catalyst particles over the entire reaction surface is possible. Such a construction also allows a smaller excess of gas to Reaktionsedukten and thus an almost stoichiometric operation of the fuel cell stack. Such a configuration of the coolant channels further makes it possible to uniformly cool the fuel cell stack.

Manufacturing advantages arise when a media-guiding unit several, along the stack axis consecutive,

thin-surface components, in particular sheets, which are formed to one, preferably to both, the main axes of the stack cross-section largely mirror-symmetrical. In this way, in the region of the mirror-symmetrical components, a mirror-symmetrically constructed channel structure with a uniform thermal, mechanical and electrical load distribution over the stack cross-section also results. The components are preferably by means of adhesive layers consisting of two-component or multi-component adhesives

connected so that the channels of the channel structure inside the media guide-Einhett against each other and out through the

thermoplastic or from two- or multi-component screed

existing Kiebeschichten are sealed. Thanks to this structure of the media-guide unit filigree cavity structures or

Channel structures can be easily, inexpensively and efficiently produced by means of thermoplastic or two- or

Mehrkomponentenkieber existing Kiebeschichten are functionally sealed.

The fuel cell stack can preferably be formed as a stack of individual cells, wherein at least two of these individual lines are connected to each other by an existing of thermoplastic or two- or multi-component glue adhesive layer which extends substantially over the entire cross section of the individual cells. A single cell consists of a membrane-electrode unit and media-guide units, in particular of the construction described above. It is also possible to provide the membrane-electrode unit with its own frame and the media-guide units without a fixed connection, such. an adhesive layer, to

To arrange membrane electrode assembly. If one of the individual cells is to be removed from the fuel cell stack, the thermoplastic adhesive layer may be used in the case of a thermoplastic bond

melted, the single cell removed and the rest of the

Fuel cell stack mitteis a new thermoplastic

Adhesive layer to be reconnected and sealed. In a Particularly preferred embodiment are the individual

Fuel cells designed as PEM fuel cells.

Preferably, the media-guide units located between the membrane-electrode assemblies are constructed so that they respectively face on both sides on like operating sides of the membrane-electrode assemblies, ie, either the anode sides or the cathode sides of the membrane -Electrode units _/ adjacent. This stacking sequence has the advantage of providing a gas barrier between that portion of the media guide unit that supplies one of the two adjacent membrane electrode assembly and that portion of the media guide assembly that houses the other membrane electrode assembly supplied, can be waived.

Incidentally, the current in this arrangement is preferably not passed through the media guide units, but over those

Components that are in direct, stromfeitendem contact with the

Membrane electrode unit stand, derived. In this way, the formation of electrochemical cells is avoided and the use of Bioplarplatten can be completely dispensed with.

Each of the membrane-electrode units can be switched separately, resulting in a wide range of possibilities of interconnecting individual tents, blocks of single cells or sub-stacks. So is also a parallel connection of the single cells or blocks of

Single cells possible, which is particularly advantageous in case of failure of a cell. Preferably, the thermopiastic plastic used has a crystalline behavior, which has the advantage that the

Glass transition temperature does not affect the behavior of the

Plastic at different temperatures. In this case, the thermoplastic material can be both a completely crystalline plastic and also a plastic with a predominantly crystalline structure, which is, for example, 60% crystalline.

The thermoplastic adhesive layer or the thermoplastic

Kiebeschichten, which essentially over the entire

Stack cross-section, allow by a suitable choice of the electrical and thermal conductivity of the plastic used an optimal division of the electrical and thermal properties within the fuel cell stack.

The thermoplastic or the two- or

Mehrkomponentenkieber is preferably formed acid resistant. Since phosphoric acid is frequently used in high-temperature PE fuel cells within the membrane electrode units, and Nafion is frequently used as the electrode in low-temperature fuel cells, the thermoplastic or the two-component or multi-component valve thus retains its properties

sealing and bonding properties, even if it comes into contact with chemically active substances.

In further preferred embodiments, the

thermoplastic, for example, perfluoroalkoxyalkane (PFA), fluorinated ethylene-propylenes (FEP) such as FEP-Norton®, aromatic polymers such as PEEK ™ or polyfluorocarbon coating such as FEP or PFA provided polyimides such as Kapton®, Norton®,

StablEdge®, Taimide® or UL®,

Preferably, the thermoplastic or the two- or multi-component adhesive has an operating temperature between -40 ° C and 200 ° C. In this way, the fuel cell stack can be operated over a wide temperature range, both the operation of a low-temperature fuel cell stack (NT-PEM) and a high-temperature fuel cell stack (HT-PEM) is possible in this way.

In the case of a variant of the invention, at least one component is first attached to the side surface to be joined to the thermoplastic

Plastic or the two- or multi-component adhesive coated and then recesses introduced into the device. The thermoplastic or the two- or multi-component adhesive can be applied in a simple manner to the (still) continuous side surface of the component.

In a particularly preferred embodiment, first recesses, openings, recesses, etc., in at least one

Introduced component and the device only then with a thermoplastic or a two- or

Multi-component adhesive coated. Since both the handling of flexible components can be avoided in this way and the waste can be disposed of sorted, brings such a method

especially in (partially) automated production processes a number of advantages. The application of the thermoplastic material or of the two-component or multi-component adhesive takes place in particular selectively, ie only on the areas of the side surface of the components, which are subsequently also connected to another component.

In practice, has proven to apply the thermoplastic

Plastic or of the two- or multi-component adhesive by

In other advantageous process variants, this is done by dipping, extrusion, screen printing, screen printing with rotating screens or a hotmelt process.

A further aspect of the invention is to provide a mechanical installation for carrying out a method according to the invention for producing a fuel cell stack.

Further advantages of the invention will become apparent from the description and the drawings. The features mentioned above and those listed in more detail can be used individually or in any combination. The embodiments shown and described are not to be understood as exhaustive enumeration, but rather have exemplary character for the description of the invention.

In the following, an embodiment of the invention is explained in more detail with reference to schematic drawings. Show it :

Fig. L: the structure of a fuel cell assembly with a

Fuel cell stack and 2 shows a section through a section of the fuel cell stack of Figure 1,

Fig. 1 shows the structure of a Brennstoffzelienaggregats 1 z. B. for mobile use. The fuel cell unit 1 has a fuel cell stack 2 and a housing 3 surrounding the fuel cell stack 2. The housing 3 includes not shown and

Discharge lines for the process gases, power connections, etc.

The fuel cell stack 2 has a plurality of membrane electrode assemblies 5 consecutive along a stacking axis 4, each having an anode side 6 and a cathode side 7. Between

Membrane electrode units 5, a media guide unit 8 and 9 is arranged in each case. For the sake of clarity, the

Size ratios of the fuel cell stack 2 in Fig. 1 not

shown to scale. The membrane-electrode assemblies 5 and the media-guide units 8, 9 are compared to the width of the

Fuel cell stack 2 formed much narrower.

Two different types of media guide units 8 and 9 are provided. By means of the hydrogen-medium-guide unit 8, the combustion gas, in particular hydrogen, the cathode sides 7 of the membrane-electrode units 5 is supplied. A hydrogen medium guide unit 8 is therefore arranged in each case between two membrane electrode Einhetten 5, the cathode sides 7 of the hydrogen medium guide unit 8 are facing.

By means of the oxygen-media-guiding units 9 is the

Oxidizing gas, in particular compressed ambient air, the Anode sides 6 of the membrane Eiektroden units 5 supplied. Accordingly, the oxygen-media-guide units 9 (except for the two outer ones) are each surrounded by two membrane-electrode units 5 whose anode sides 6 face the oxygen-medium-guide unit 9. The media-guiding units 8, 9 are also used for the removal of reaction gases, in particular water vapor, as well as excess starting gases. Furthermore, a coolant may circulate through the media guide units 8, 9.

The fuel cell stack 2 has a substantially uniform, along the stacking axis 4, rectangular stacking cross-section, which is generally designated by the reference numeral 10 in FIG. For example, the stack cross-section 10 may span a rectangular area of 200 mm x 240 mm, but other cross-sectional shapes and sizes may be advantageous depending on the use and installation situation of the fuel cell assembly 1.

Fig. 2 shows an exemplary section of the fuel cell stack 2 in a view of a parallel to the stacking axis 4 extending

Cutting plane. The location of the shown section within the

Fuel cell stack in Figure 1 is indicated by a dashed frame 11, the aspect ratios of the frame accordingly due to the distorted representation of the fuel cell stack 2 in Fig. 1 is not the actual conditions and differ from the

Aspect ratios according to FIG. 2.

In essence, an oxygen-media-guide unit 9, a membrane-electrode unit 5 and a (in Figure 2 from bottom to top) Hydrogen edien guide unit 8 only partially shown. The media-guide units 8, 9 shown adjoin a membrane-electrode unit 5, etc., again along the stacking axis 4.

According to FIG. 2, the membrane electrode unit 5 has a frame-shaped spacer plate 14 with a relatively large, central recess 15. In the recess 15 of the frame-shaped Distanzbiechs 14, d. H. in Figure 2, starting from the shown portion of the spacer plate 14 to the left, are two, for example. Viton existing sealing rings 16th

intended. The sealing rings 16 are followed by two gas diffusion layers 17. In FIG. 2, only a small edge section is in each case

Gas diffusion layers 17 shown. The gas diffusion layers 17

However, they extend over a large section of the central one

Recess 15 of the frame-shaped spacer 14. They include between them the reaction zone of the membrane electrode assembly 5 (not shown), which is a membrane, for. B. a proton exchange membrane, and catalyst layers.

In addition, FIG. 2 shows a boundary 18 arranged between the two gas diffusion layers 17 and the two sealing rings 16, which surrounds the reaction zone of the membrane electrode unit 5 in a circumferential manner.

Furthermore, the membrane-electrode unit 5 has a potential-separating layer 20 arranged along the stacking axis 4 between the frame-shaped spacer bend 14 and the oxygen-medium-guide unit 9. The potential separation layer 20 is congruent with the

frame-shaped spacer plate 14 is formed. It consists of one electrically insulating material and is used for electrical isolation between the spacer plate 14 and the oxygen-media-guide unit 9. In the illustrated embodiment, the potential separation layer 20 is formed of a thermoplastic material layer, which is also designed as an adhesive layer. Alternatively, the potential separation layer 20 z. B. have an adhesive coated plastic film. The potential separation layer 20 can also be inserted without adhesive connection in the appropriate place.

The oxygen-media guide unit 9 includes in this

Embodiment seven thin-surface and planar structural plates 22, preferably made of aluminum. For alternative designs, the

Oxygen Media Guide Unit 9 also less or more

Have structural plates 22. The structural plates 22 each extend over the entire stacked cross-section 10 and are flat or flat over the entire stacking cross-section 10. They have two different thicknesses, z. B, 0.75 mm and 0.25 mm, on.

Furthermore, the structural plates 22 lie flat against one another along the stacking axis 4. They are connected to each other by means of thermoplastic adhesive layers 23, which extend substantially over the entire stack cross-section 10. Consequently, in each case only the thermoplastic adhesive layer 23 is provided between two successive structural plates 22. An exception is only the connection point between the third and fourth structural plate 22 shown in FIG. 2 from below. Between these structural plates 22, a further potential-separating layer 24 is arranged, which is constructed analogously to the potential-separating layer 20. Due to the potential separation layer 24 is a potential separation between the upper and lower portion of the oxygen-medium guide unit 9. In the operation of the fuel cell stack 2, therefore, the electric potential in the upper portion of the oxygen-medium guide unit 9 by the potential at the Cathode side 7 of the membrane electrode assembly 5 shown in FIG. 2 determined. On the other hand, the potential in the lower portion of the oxygen-medium guide unit 9 is determined by the cathode side 7 of that membrane-electrode unit 5 adjoining the other side of the oxygen-medium guide unit 9 (not shown).

The thermoplastic adhesive layers 23 consist of a

thermoplastic material, which is thermally and electrically insulating and acid-resistant. In addition, the

thermoplastic adhesive layers 23 over a wide

Temperature range thermoresistant.

In alternative embodiments, all or part of the thermoplastic adhesive layers 23 may be made of an electrically conductive thermoplastic. The use of an electrically conductive thermoplastic has the advantage that the current-conducting surface is increased and capacitor effects are avoided. It is thus prevented that build up potentials between the planes defined by the structural plates 22, which can lead to electrolysis esters.

Moreover, the thermoplastic used has crystalline behavior, ie the glass transition temperature can be neglected due to the predominantly crystalline structure of the thermoplastic material in terms of its functionality. Of the Thermoplastic material can be used reliably in a temperature range between -40 ° C and 200 ° C. For example, the thermoplastic is a perfluoroalkoxyalkane (PFA), a fluorinated ethylene-propylene (FEP), an aromatic polymer, or a polyfluorocarbon coating such as FEP or PFA

Polyimides such as Kapton®, Norton®, StablEdge®, Talmide® or UL®.

The structural plates 22 have a plurality of recesses 25, in particular apertures or passage openings. The

Thermoplastic Kiebeschichten 23 have partially corresponding recesses 26 and holes. Through the recesses 25, a filigree channel structure 27 is formed in the interior of the oxygen-media-guide unit 9, which is sealed in and out by the thermoplastic adhesive layers 23,

For example, a recess 25 in the form of a circular passage opening in a structural plate 22 and a recess 25 in the form of a circular passage opening in the adjacent structural plate 22 results in a functional cavity 30 extending along the stacking axis 4 through the thermoplastic adhesive layer 23 arranged between the structural plates 22 extends through. The thermoplastic adhesive layer 23 has at this point a

corresponding recess 26 in the form of a passage opening.

Due to the thermoplastic adhesive layer 23, the functional cavity 30 is circumferentially sealed between the structural bends 22 and transversely to the stacking axis 4. The functional cavity 30 forms a portion of a longitudinal channel 33 of the channel structure 27 of the oxygen-media-guiding unit 9. A transverse channel 34, ie a channel which runs perpendicular to the stacking axis 4, is formed z, B. by a narrow, elongated recess 25 on the second in Figure 2 from below structural plate 22, which extends in the sectional plane of Fig. 2.

In FIG. 2, by way of example only individual recesses 25, 26 and channels 33, 34 are provided with reference symbols. Overall, the includes

Channel structure 27 many communicating longitudinal 33 and transverse channels 34. A portion of the channels 33, 34 serves for the supply of

optionally compressed ambient air to the membrane-electrode unit 5. In particular, the reaction gas to be supplied flows,

optionally compressed air, evenly distributed through a plurality of inlet openings 35 on two structural plates 22, each serving as Elektrodenabdeckbleche, in the adjacent membrane electrode assemblies 5 and there in the reaction zone, not shown.

Another part of the channels 33, 34 serves to remove formed water vapor and unreacted reaction gases. For this purpose, the structural plates 22 serving as electrode covering plates have a multiplicity of outflow openings, not shown, through which the water vapor and excess reaction gas from the membrane-electrode units 5 can be carried out. Finally, part of the channels 33, 34 serve to circulate a coolant.

The hydrogen media guide unit 8 is constructed analogously to the oxygen media guide unit 9. It includes in this

Embodiment also seven structural plates 22, which are connected by means of thermoplastic adhesive layers 23, which extend substantially over the entire stack cross section 10. A Filigree channel structure 27 is also formed according to the channel structure 27 of the oxygen-medium guide unit 9 inside the hydrogen-medium guide unit 8 by a plurality of recesses 25 in the structural plates 22. Two structural plates 22 serving as electrode cover sheets are provided with inlet openings 35 and outflow openings (not shown). Finally, the hydrogen-media-guide unit 8 also has a potential separation layer 24.

The structural plates 22 of both media-guiding units 8, 9 are largely mirror-symmetrical to the main axes of the stack cross-section 10. Therefore, the channel structures 27 are the

Media guide units 8, 9 also designed mirror-symmetrically to the main axes of the stack cross-section 10. The symmetrical design of the channel structures 27 advantageously results in a uniform thermal, mechanical and electrical load distribution across the stack cross-section 10. In addition, in the case of a mechanical manufacturing tool costs are reduced.

Incidentally, the current generated in the reaction zone of the membrane electrode assembly 5 is discharged at least via the pattern plates 22, the electrode cover plates, directly adjacent to the membrane electrode assembly 5. Is there electrical contact between

at least one of the Elektrodenabdeckblechen and at least one other level, the current can also be additionally or exclusively dissipated via this other level or levels, resulting in a reduction of the internal resistance. In this way, each of the membrane electrode assemblies 5 can be interconnected individually. Therefore no current has to flow off via the media guide unit 8, 9, so that no electrochemical potential can form between the individual levels and so the risk of corrosion is minimized.

The fuel cell stack 2 is essentially two

alternately repeating stacking sequences of their components

(Structural sheets 22 and components of the membrane electrode assemblies 5) aufgeba ut. In FIG. 2, one of the stacking sequences is shown. The second Stapelelfoige joins each in Figure 2 above and below. Of

Furthermore, the fuel cell stack 2 is made up of a plurality of individual cells 37 a. Advantageously, the successive use

Single cells 37 each have a common structural plate 22, z, B. The bottom in Figure 2 from below structural plate 22 or in Figure 2 from the top fourth structural plate 22nd

To produce the fuel cell stack 2, the structural sheets 22 are first provided with Ausneh rules 25. Subsequently, the thermoplastic adhesive and sealant is selectively applied to at least one side surface of one of the structural sheets 22 to be joined together. The application of the adhesive and sealant can, for example, be effected by extrusion, lamination, dipping or screen printing or as a hotmelt. Such a procedure is possible because of the thermoplastic as adhesive and sealant repeatedly and without quality and performance losses, for example. Can be activated by heating, Ie mlich the first order and later baking, while he after the

Initial order or the bonding of the fuel cell stack 2 is no longer sticky.

A concrete application example for a mechanical plant for

Manufacturing a fuel cell stack 2 provides one below described transfer line. At a first station of the transfer line raw sheets are separated from a coli and directed, then the raw sheets are mechanically or at a second station

thermally provided with recesses 25, then they are z. B, surface-cleaned by plasma etching (third station). At a fourth station, the structural sheets 22 are then selectively coated on at least one side surface by means of lamination, dipping, screen printing or extrusion with thermoplastics. Finally, the coated ones

Structured sheets 22 are fed to a stacking device in which they are bonded together under pressure and, for example, inductively introduced process heat. The form of the stacking device ensures that the components produced are plane-parallel

Have surfaces, so that dimensional deviations are minimized by chain dimensions in the subsequent juxtaposition to a fuel cell stack 2.

Claims

claims

1. fuel cell stack (2), which

at least two, along a stacking axis (4) successive media-guide units (8, 9) and one along the

Stacking axis (4) between the media-guide units (8, 9) arranged membrane electrode assembly (5), characterized in that at least two, along the stacking axis (4) successive components (22) of the fuel cell stack (2) by means of an adhesive layer (23) consisting of thermoplastic material or of a two-component or multi-component adhesive, which adhesive layer extends essentially over the entire stacked cross-section (10), are connected to one another.

2. fuel cell stack according to claim 1,

characterized in that the interconnected by means of the adhesive layer (23) components (22) recesses (25) through which at least one along the stacking axis (4) through the adhesive layer (23) extending therethrough

Functional cavity (30) results, which by the adhesive layer (23) at least between the components (22) and transversely to

Stacking axis (4) is circumferentially sealed, wherein the

Functional cavity (30) preferably forms a portion of a media guide channel (33).

3. fuel cell stack according to one of the preceding claims, characterized in that at least one media-guiding unit (8, 9) has a plurality of along the stacking axis (4) successive components (22), each by means of a thermoplastic or from a two- or

Multi-component adhesive existing adhesive layer (23)

connected to each other, wherein the Kiebeschichten (23) each extend substantially over the entire stacking cross-section (10).

4. Fuel cell stack according to one of the preceding claims, characterized in that the means of the adhesive layer (23) interconnected components (22) of a media-guiding unit (8, 9) lie flat against each other, wherein in the interior of the media guide unit (8, 9) a channel structure (27) is formed by recesses (25) on the components (22).

5. Fuel cell stack according to one of claims 1 to 3,

characterized in that the interconnected by means of the adhesive layer components of a media-guiding unit have deformations through which a channel structure is formed in the interior of the media-guiding unit.

6. fuel cell stack according to one of the preceding claims, characterized in that the components (22) thin surface, in particular as sheets, preferably as aluminum sheets, are formed,

7. Fuel cell stack according to one of claims 1 to 4 or 6, characterized in that the components (22) are flat.

8. fuel cell stack according to the preamble of claim 1, characterized in that at least one media-guiding unit (8, 9) has a plurality of thin-surface and planar components (22), in particular sheets, which lie flat against each other along the stacking axis (4) and in particular mitteis each a thermoplastic or one of a Two- or Mehrkomponentenkieber existing adhesive layer (23) are interconnected, wherein in the interior of the media guide unit (8, 9) a channel structure (27) by recesses (25) on the components (22) is formed.

9. fuel cell stack according to one of the preceding claims, characterized in that at least one media-guiding unit (8, 9) has a plurality of along the stacking axis (4) successive, thin-surface components (22), in particular sheets, which at least one, preferably two, main axes of the stack cross-section (10) are formed largely play gel symmetrical.

10. Fuel cell stack according to one of the preceding claims, characterized in that the fuel cell stack (2) comprises a plurality of individual cells (37), wherein two, by means of a thermoplastic or consisting of two- or multi-component glue adhesive layer (23) interconnected components (22) two different Single cells (37) are assigned.

11. Fuel cell stack according to one of the preceding claims, characterized in that the thermoplastic material has crystalline behavior.

12. Fuel cell test after one of the previous ones

Claims, characterized in that the thermoplastic material is thermally conductive, electrically conductive and / or

is formed acid-resistant.

13. Fuel cell stack according to one of the preceding

Claims, characterized in that it is in the

thermoplastic is a perfluoroalkoxyalkane (PFA), a fluorinated ethylene-propylene (FEP), an aromatic polymer or a PFA or FEP-coated polyimide,

14. Fuel cell stack according to one of the preceding claims, characterized in that the thermoplastic material has a permissible use temperature between -40 ° C and 200 ° C.

15. A method for producing a fuel cell stack

which at least two, along a stacking axis (4) successive media-guide unit (8, 9) and along the stacking axis (4) between the media-guide units (8, 9) arranged membrane electrode assemblies (5 ), characterized in that at least two, along the stacking axis (4) successive components (22) by a thermoplastic K! ebeschicht (23) or an adhesive layer of two- or

Mehrkomponentenkleber be joined together by a thermoplastic or a two- or

Mehrkomponentenkleber, before the components (22) are stacked, at least on that side surface of the Components (22) is applied, which faces the other component (22) in the stacked state.

16. The method according to claim 15, characterized in that 5 the components (22), preferably before the application of

thermoplastic or two- or

Mehrkomponentenklebers be provided with recesses (25), which form at least a portion of a media guide Kanai (33, 34) after connecting the components (22).

0

17. The method according to claim 15 or 16, characterized

characterized in that the thermoplastic material by means of

Lamtnieren, dipping, extrusion, screen printing and / or a Hotmelt- method on the one or more components (22) is applied. s

18. A machine installation for carrying out a method according to one of claims 15 to 17.