DE102008033209A1 - Fuel cell arrangement i.e. polymer-electrolyte-membrane fuel cell arrangement, for vehicle, has rods arranged relative to each other, such that electrode-arrangement arranged between bipolar plates is corrugated in mounted condition - Google Patents

Abstract

The arrangement (1) has a corrugated membrane-electrode-arrangement (2) arranged between bipolar plates (3.1, 3.2). Flow fields are formed on outer sides of the bipolar plates by channel structures with channels (K1, K2) and rods (S1, S2). The channels run parallel to each other and the rods run parallel to each other between the channels. The rods are arranged relative to each other, such that the electrode-arrangement arranged between the bipolar plates is corrugated in a mounted condition. The electrode-arrangement comprises gas diffusion electrodes and a polymer electrolyte membrane.

Description

The The invention relates to a fuel cell assembly according to the Features of the preamble of claim 1.

A Fuel cell assembly or a fuel cell stack (also short stack) consists of several, electrically connected in series, plane-parallel one above the other Stacked arranged fuel cells. Each fuel cell points as electrodes in the form of gas diffusion electrodes an anode, a Cathode and an intermediate electrolyte, for example in the form of a polymer electrolyte membrane (PEM short), the together a membrane-electrode arrangement (MEA short) form.

Between the membrane electrode assemblies adjacent the fuel cell stack is in each case a bipolar plate (also bipolar separator plate unit called) arranged. The bipolar plate serves the spacing adjacent membrane-electrode assemblies, distributing reactants for the fuel cell like fuel and oxidant over the adjacent membrane-electrode assemblies and the discharge the reactants provided in this, respectively to the Membrane electrode assemblies towards open channels, the Dissipate the heat of reaction via a separate Coolant channels guided coolant and the production of an electrical connection between the Anode and the cathode of adjacent membrane-electrode assemblies.

When Reactants are a fuel and an oxidant used. Most gaseous reactants (in short: reaction gases) are used, z. B. hydrogen or a hydrogen-containing gas (eg, reformate gas) as fuel and oxygen or an oxygen-containing gas (eg. As air) as an oxidizing agent. Under Reactants are all understood substances involved in the electrochemical reaction, including the reaction products, such as. B. water or depleted fuel.

The respective bipolar plate consists of a molded part, preferably However, from two or more plane-parallel interconnected moldings, in particular plates - an anode plate for connection with the anode of a membrane-electrode assembly and a cathode plate for connection to the cathode of the other membrane-electrode assembly - or a plate with introduced on top and bottom channel structures. At the surface facing the membrane-electrode assembly The anode plate are anode channels for distribution a fuel along the membrane electrode assembly arranged wherein facing the other of the membrane-electrode assembly Surface of the cathode plate cathode channels for Distribution of oxidant over the other membrane-electrode assembly are arranged. The cathode channels and the anode channels have no connection with each other.

The Cathode and anode channels are thereby by surveys (called webs hereinafter) separate recesses (hereinafter called channels) on each of the membrane-electrode assemblies facing surfaces of the anode and cathode plate educated. The cathode and anode plates are preferably shaped especially hollow shaped. The walkways and channels For example, they are discontinuous by hollow embossing (with mold and stamp), hydroforming (with mold and liquid), High speed forming (with mold and punch), forming, deep drawing, Extrusion or the like, or continuously Rolling or drawing made.

Around when using a fuel cell assembly for a vehicle in operation has sufficient economy and Low costs are on the one hand the performance per square meter Cell area and the efficiency of the fuel cell for example, by reducing power losses as a result of contact and / or reduced material resistances as well as fabric and Charge transport can be improved. On the other hand, there are increasing inexpensive materials, such. B. rollable electrode layers for the gas diffusion electrodes.

From the DE 10 2005 037 093 A1 For example, a fuel cell with fluid guide channels with countercurrently changing flow cross-sections known.

From the DE 60212001 T2 A fuel cell fluid distribution plate (also called a bipolar plate) is known having on at least one surface a network of progressively finer channels having one or more branched gas delivery channels with a plurality of gas diffusion channels connected thereto of width less than 0.2 mm.

From the US 20020167109 A1 a conventional bipolar plate and its manufacture is described, wherein the flow channels have different channel cross-sectional shapes. The flow channels are introduced by roll embossing in a plate made of a flexible graphite material.

From the US 20030059662 A1 is a conventional bipolar plate is known which a ser pent-like flow channel, wherein the web varies between adjacent channel sections of the channel in width.

From the US 6586128 B1 For improving and adjusting a mass transport between adjacent channels, a method and a device is known in which pressure differences in the respective channel can be set by changing the channel profile with a constant web width.

From the DE 69901187 T2 Furthermore, a fuel cell assembly with a wave-shaped membrane-electrode assembly by staggered arrangement of uniform webs is known.

Especially through the use of inexpensive materials, such as flexible, rollable gas diffusion electrode layers, the problem is that due to the largely flexible, flexible and / or compliant diffusion layer materials during assembly of the fuel cell assembly an externally applied pressure on the webs (= Flussfeldstege, d. H. Webs in the area of flow fields) poorly distributed to the active layer (the catalyst and the membrane). This results in increased in particular in channel areas Contact resistances between the layers and also in the diffusion layer material itself, which depending on the configuration to very significant power losses being able to lead.

Of the Invention is based on the object, a fuel cell assembly indicate which ones compared to those of the prior art known is improved.

The The object is achieved by the features specified in claim 1.

advantageous Further developments of the invention are the subject of the dependent claims.

The Fuel cell assembly includes a plurality of membrane-electrode assemblies, between each of which at least one bipolar plate consisting of at least one or two plane-parallel plates formed is arranged, wherein at least on one or both outer sides of the respective plate in each case a flow field through in the Plate introduced channel structures with several parallel to each other running channels and between two channels formed parallel to each other webs. At least according to the invention the webs of two mutually directed outer sides of two adjacent bipolar plates arranged to each other and / or provided with mutually corresponding dimensions that a arranged between the two bipolar plates membrane electrode assembly is corrugated in the assembled state.

With In other words, the webs of two adjacent flow fields, each on the outside of the membrane-electrode assembly are formed, in terms of their arrangement and / or dimension formed so varied to one another that a during assembly acting contact pressure of a membrane-electrode assembly to the adjacent bipolar plates along the surface of the Membrane electrode assembly is largely homogenized. Reached This more homogeneous compression of the active layer by the corrugated membrane electrode assembly due to a wavy Tensioning of the gas diffusion electrode layer under the pressing pressure the various bridges. By the deflection of the plane normal position exercises the gas diffusion electrode position of this deflection against a Pressure off, even with wider channels still in the middle of the channel causes a higher compression.

Especially the webs are formed such that in particular opposite webs are formed differently from each other. This can be a clear higher contact pressure and thus a significant increase a material compression of the gas diffusion layer material in the channel area can be achieved even with wider channels. this in turn causes sinking losses, in particular a reduction of pressure losses in the flow field and a much higher power density too at roll gas diffusion electrode layers.

By Such optimization of web widths and / or web heights and / or an offset web arrangement may be an adaptation to local conditions in the adjacent channels and so on accompanied by an optimization of the power density of a fuel cell assembly be achieved. In particular, in a fuel cell assembly with flexible layers of gas diffusion electrodes thus different requirements for the fluid, in particular Gas transport, as well as different thermal and electrical Conductivity requirements by appropriate variation the web widths and / or the web heights and / or the offset Bar arrangement met and achieved.

In one possible embodiment, the webs of the two mutually parallel bipolar plates are arranged laterally offset from one another. When the two bipolar plates are pressed together with the membrane-electrode arrangement arranged therebetween, the corrugated shape results for them, as the membrane-electrode arrangement is replaced by the pressure of the webs of one bipolar plate into the opposite channels of the other bipolar plate is bent.

For this the webs are expediently such side staggered to each other, that the webs of a bipolar plate in the channels of the other bipolar plate at least partially protrude or at least the channels of the other bipolar plate are opposite.

In another alternative or additional embodiment have the webs of the two parallel arranged bipolar plates different heights. Preferably, the webs the respective or each bipolar plate alternately different Heights up. For example, the webs of a cathode flow field (on one side of the membrane-electrode assembly and formed by the webs of a bipolar plate) always alternately a certain Height offset and thus alternately different heights on. The webs of the opposite anode flow field (on the other side of the membrane electrode assembly and formed through the webs of the other bipolar plate) are designed such that their different heights and thus their height offset with the heights and the height offset of the webs of the other bipolar plate correspond in such a way that low bars one bipolar plate high webs of the other bipolar plate or conversely opposed to each other. In other words: The two bipolar plates are arranged relative to one another such that Bars with different heights opposite each other are arranged.

About that In addition, the webs and / or the channels of a each bipolar plate at least one varying channel width, a varying land width and / or a varying channel spacing exhibit. By appropriate dimensioning of the web and / or Channel widths and / or channel spacing is an improvement the compression possible. For example, a broadened protruding ridge in the convex part of the waveform of the membrane-electrode assembly a high compression even far into the channel of the opposite side cause.

to Achieving the waveform of the membrane-electrode assembly in the pressed State, the two bipolar plates are preferably such to each other arranged that webs with different web widths each other are arranged opposite one another.

alternative or in addition, the two bipolar plates be arranged to each other such that webs with different Bridge widths and / or with different heights each other are arranged opposite one another. In addition, you can the webs at least partially or completely offset be arranged to each other. The webs are preferably such arranged offset to each other that these at least partially or completely engage in or opposite channels are arranged.

Further is any combination of different web shapes, z. B. different Web heights and / or web widths, and / or of different Bridge offsets, z. B. height offset and / or lateral offset, possible. For example, both a height offset, d. H. different web heights, between the webs of a Plate as well as laterally partial or more complete Offset of the webs of corresponding plates against each other possible.

Preferably the two bipolar plates are arranged to each other such that an overall height of an array of two bipolar plates and the intervening membrane-electrode assembly constant is. This allows a higher packing density.

About that In addition, the geometry of the webs of flow conditions and / or parameters of the flow field adapted. In a possible embodiment, the webs of the on both bipolar plates rounded ridge edges. Such rounded ones Web edges cause avoidance or at least a reduction of load peaks of the membrane-electrode assembly.

alternative or additionally, the webs of the two bipolar plates an uneven web surface, in particular an oblique or oval web surface. This too leads to improve the compression effect and to reduce it of load peaks.

For a cost-effective design of the fuel cell assembly is the membrane-electrode assembly of two gas diffusion electrodes and an intermediate polymer electrolyte membrane, the gas diffusion electrodes preferably being made of a flexible, especially rollable layer are formed.

to Cooling of the fuel cell assembly can about it In addition, two directly adjacent bipolar plates such be arranged to each other, that negative structures of the channels and the webs cooling channels and / or Zudosierungskanäle for form the respective flow field.

Preferably, the fuel cell assembly may be a so-called PEM fuel cell assembly of a number of stacked polymer electrolyte membrane fuel cells, between each of which a bipolar plate is arranged.

embodiments The invention will be explained in more detail with reference to drawings.

there demonstrate:

1 1 schematically shows a detail of a fuel cell arrangement with a single of a plurality of plane-parallel stacked membrane-electrode arrangements, each of which is bounded on the outside by a respective bipolar plate with substantially uniform webs according to the prior art,

2 1 schematically shows a possible embodiment of a fuel cell arrangement according to the invention with a corrugated membrane-electrode arrangement between two bipolar plates with webs with different web heights,

3 1 schematically shows a further alternative embodiment of a fuel cell arrangement according to the invention with a corrugated membrane-electrode arrangement between two bipolar plates with webs offset laterally from one another,

4 1 schematically a further alternative embodiment of a fuel cell arrangement according to the invention with a corrugated membrane-electrode arrangement between two bipolar plates with webs with different web heights and different web widths,

5 2 schematically shows a further alternative embodiment of a fuel cell arrangement according to the invention with a corrugated membrane-electrode arrangement between two bipolar plates with webs with different web heights and different web widths and rounded web edges,

6 schematically a further alternative embodiment of a fuel cell assembly according to the invention with a corrugated membrane electrode assembly between two bipolar plates with webs with different web heights and different land widths and rounded web edges and additional cooling channels between two plane-parallel arranged bipolar plates, and

7 schematically a diagram with the profile of the pressing pressure to the active layer as a function of the web offset over a web-channel web segment.

each other corresponding parts are in all figures with the same reference numerals Mistake.

1 schematically shows a section of a fuel cell assembly 1 according to the prior art with a single of a plurality of plane-parallel stacked membrane-electrode assemblies 2 (also called MEA for short), each on the outside of each bipolar plate 3.1 . 3.2 are limited.

It shows the 1 the fuel cell assembly 1 in sectional view for better understanding of the structure and orientation of the individual elements - membrane-electrode assembly 2 (= MEA) and the bipolar plates 3.1 . 3.2 - to each other.

In the fuel cell assembly 1 it may in particular be a so-called PEM fuel cell arrangement (with PEM = polymer electrolyte membrane). This includes the fuel cell assembly 1 as a membrane electrode assembly 2 two gas diffusion electrodes 2.1 . 2.2 (one as an anode, the other as a cathode) and an interposed electrolyte 2.3 , z. B. a polymer electrolyte membrane. One of the surfaces of the respective gas diffusion electrode 2.1 . 2.2 is the electrolyte 2.3 , z. B. the polymer electrolyte membrane, and the other surface of one of the bipolar plates 3.1 . 3.2 facing.

The respective bipolar plate 3.1 . 3.2 is preferably formed from at least one plate or two plane-parallel plates, wherein the plates are made of a metal and are, for example, thin metal sheets, which allows a robust construction and a simple introduction of the channel structure in the two plates. In principle, the two plates can also be made of carbon or a carbon material (carbon). Such plates can nowadays be produced very thin-walled and have the advantage that they do not have to be coated.

In at least one outer side of the plate or one of the plates or both plates of the respective bipolar plate 3.1 . 3.2 are channels K1, K2 and webs S1, S2 introduced, z. By hollow embossing (with mold and stamp), hydroforming (with mold and liquid), high speed forming (with mold and stamp), forming, deep drawing, extrusion or the like, or continuously by rolling or drawing. The respective bipolar plate 3.1 . 3.2 can thus be a molding that z. B. is formed from one or two thin metal sheets, which / s elevations (= webs S1, S2) and depressions (= channels K1, K2), which to the outside, ie, the respective associated membrane electrode assembly 2 , form a flow field F1, F2 with the channels K1, K2.

During operation of the fuel cell assembly 1 are the channels K1, K2 of the respective flow field F1, F2 flows through a fluid, for. B. an anode flow field of a fuel, for. As hydrogen, and a cathode flow field of an oxidizing agent, for. As oxygen or air.

In 1 is only part of the fuel cell assembly 1 - A membrane electrode assembly 2 with two externally adjacent bipolar plates 3.1 . 3.2 - shown. In a manner not shown border outside the respective bipolar plate 3.1 . 3.2 further membrane-electrode assemblies not shown in detail 2 plan in parallel.

In the prior art, the webs S1, S2 are opposing bipolar plates 3.1 . 3.2 formed largely uniform.

Hereinafter, various alternative embodiments of the invention will be described with reference to FIGS 2 to 7 described in more detail.

In order to avoid or at least reduce transport losses, contact and / or material resistances as well as fluid or gas, heat transport and / or charge transport losses, the webs S1, S2 are two mutually directed outer sides of two adjacent bipolar plates 3.1 . 3.2 so arranged to each other and / or provided with mutually corresponding dimensions, that between the bipolar plates 3.1 . 3.2 arranged membrane electrode assembly 2 is corrugated in the assembled state.

2 schematically shows a possible first embodiment for different webs S1, S2 of two bipolar plates 3.1 . 3.2 ,

In this case, the webs S1 and S2 of the two opposing bipolar plates 3.1 respectively. 3.2 different heights H1 or H2. The bipolar plates are preferred 3.1 and 3.2 arranged to each other and provided with webs S1 and S2 with different heights H1 and H2, that a short web S1 of a bipolar plate 3.1 a long bridge S2 of the other bipolar plate 3.2 or vice versa.

In addition, the respective bipolar plate 3.1 or 3.2 provided with webs S1 and S2 such that the webs S1 or S2 of the respective bipolar plate 3.1 respectively. 3.2 alternately have different heights H1.1 and H1.2 or H2.1 and H2.2. Here are then alternately a lower web S1 of a bipolar plate 3.1 a high bridge S2 of the other bipolar plate 3.2 and adjacent a high ridge S1 of the bipolar plate 3.1 a low bridge S2 of the other bipolar plate 3.2 opposite each other.

When pressing the bipolar plates 3.1 and 3.2 and the intervening membrane-electrode assembly 2 then results in the illustrated waveform, through which a significant higher material compression is effected and thus pressure losses in the respective flow field F1 or F2 are reduced.

In order to achieve a sufficient material compression at wider channels K1 or K2, can, as in 3 shown in more detail, the webs S1, S2 of the two bipolar plates 3.1 . 3.2 in addition to the different web heights H1, H2 or alternatively laterally offset from one another.

In this case, the webs S1 and S2 may be offset from each other such that their web surface in the channels K2 and K1 of the other bipolar plate 3.2 respectively. 3.1 at least partially protrude or at least face it. This results in an analogous manner, as to 2 described, when pressed the corrugated shape of the membrane-electrode assembly 2 ,

Alternatively or additionally, the webs S1, S2 may have different web widths b _S1 or b _S2 . Also, the channels K1, K2 may have different channel widths b _K1 and b _K2 , respectively. In this case, the webs S1 or S2 of the respective bipolar plate 3.1 respectively. 3.2 also alternately different web widths b _S1.1 , b _S1.2 and b _S2.1 , b have _S2.2 .

Furthermore, any combination of different webs S1, S2 with different web heights H1, H1.1, H1.2 or H2, H2.1, H2.2 and / or different web widths b _S1 , b _S1.1 , b _{S1. 2} or b _S2 , b _S2.1 , b _S2.2 and / or different channels K1, K2 with different channel widths b _K1 or b _K2 possible.

Also, the channel spacings a1, a2 may be different. In this case, the distance between a channel wall of a channel and the same channel wall of an adjacent channel of a bipolar plate arranged parallel to this channel is understood as the particular channel spacing a1, a2. Thus, the channel distance a1 corresponds approximately to the sum of the channel width b _{K1 of} a channel K1 and the bridge width b _{S1 of} an adjacent web S1 of the bipolar plate 3.1 ,

In the case of the possible combinations of variations of the channel and / or web contours and / or dimensions, it is always ensured that the overall height and thus the thickness of two bipolar plates 3.1 and 3.2 and the intervening membrane-electrode assembly 2 stays the same.

4 shows a possible embodiment to achieve the corrugated membrane-electrode assembly 2 by webs S1, S2 with different web heights H1.1, H1.2 or H2.1, H2.2 and different web widths b _S1 or b _S2 and channels K1, K2 with different channel widths b _K1 and b _K2, respectively. These are the bipolar plates 3.1 . 3.2 arranged such that their webs S1, S2 are arranged opposite one another. In 3 is an example of laterally staggered webs S1, S2 shown.

5 schematically shows a further alternative embodiment of a fuel cell assembly according to the invention 1 with a corrugated membrane electrode assembly 2 between two bipolar plates 3.1 and 3.2 , In this case, the webs S1, S2 to each other web heights H1 and H2 and / or mutually different land widths b _S1 , b _S2 . Furthermore, the respective webs S1 and S2 on rounded web edges, whereby load peaks are reduced or avoided.

6 schematically shows a further alternative embodiment of a fuel cell assembly according to the invention 1 , For cooling the fuel cell assembly 1 are additional cooling channels KK between two plane-parallel arranged bipolar plates 3.1 and 3.2 provided, without interposition of a membrane-electrode assembly 2 are arranged directly on top of each other.

The cooling channels KK are, for example, on the inside by negative structures of the outer channel structures of the channels K1, K2 and the webs S1, S2 of the two bipolar plates 3.1 and 3.2 educated. In this case, acting as an anode plate and acting as a cathode plate, for example, such channel bottom placed on the channel bottom to each other that their side walls and webs form the inner coolant channels KK. Alternatively or additionally, metering channels can also be formed in an analogous manner.

7 schematically shows a diagram with different profiles V1 of the pressing pressure p of the gas diffusion electrode layer 4 to the active layer along a line from web center to web center according to 4 with different ridge offsets s of s = 0 during the course V1, s = 0.1 mm in the course V2, s = 0.2 mm in the course V3 and s = 0.3 mm in the course V4. As the web offset s increases, the material compression in the region around the web edge of the widened web S1 increases in accordance with FIG 4 which also leads to an increase in the minimum compression in the channel K2.

1

A fuel cell assembly

2

Membrane electrode assembly

2.1 2.2

Gas diffusion electrode

2.3

Polymer electrolyte membrane

3.1 3.2

bipolar plates

a1, a2

channel spacing

b _K1 , b _K2

channel width

b _S1 , b _S1.1 , b _S1.2

web width the webs of a bipolar plate

b _S2 , b _S2.1 , b _S2.2

web width the webs of the other bipolar plate bridge width

F1, F2

flow field

H1, H1.1, H1.2

web heights the webs of a bipolar plate

H2, H2.1, H2.2

web heights the webs of the other bipolar plate

K1, K2

channels

S1, S2

Stege

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 102005037093 A1 [0008]
• - DE 60212001 T2 [0009]
• US 20020167109 A1 [0010]
• US 20030059662 A1 [0011]
• - US 6586128 B1 [0012]
• - DE 69901187 T2 [0013]

Claims (15)

Fuel cell assembly ( 1 ) comprising a plurality of membrane-electrode assemblies ( 2 ), between each of which at least one bipolar plate ( 3.1 . 3.2 ), which is formed from at least one or two planes arranged parallel to each other, wherein at least on one or both outer sides in each case a flow field (F1, F2) by introduced into the respective plate channel structures with a plurality of mutually parallel channels (K1, K2 ) and between two channels (K1, K2) parallel to each other extending webs (S1, S2) is formed, characterized in that the webs (S1, S2) of two mutually directed outer sides of two adjacent bipolar plates ( 3.1 . 3.2 ) are arranged to one another and / or provided with mutually corresponding dimensions such that one between the two bipolar plates ( 3.1 . 3.2 ) arranged membrane electrode assembly ( 2 ) is corrugated in the assembled state. Fuel cell assembly ( 1 ) according to claim 1, characterized in that the webs (S1, S2) of the two mutually parallel bipolar plates ( 3.1 . 3.2 ) are arranged laterally offset from one another. Fuel cell assembly ( 1 ) according to claim 2, characterized in that the webs (S1, S2) are arranged laterally offset from one another such that the webs (S1 or S2) of a bipolar plate ( 3.1 or 3.2 ) into the channels (K2 or K1) of the other bipolar plate ( 3.2 or 3.1 ) at least partially protrude or the channels (K2 or K1) of the other bipolar plate ( 3.2 or 3.1 ) are opposite. Fuel cell assembly ( 1 ) according to one of the preceding claims, characterized in that the webs (S1, S2) of the two mutually parallel bipolar plates ( 3.1 . 3.2 ) have different heights (H1, H2). Fuel cell assembly ( 1 ) according to claim 4, characterized in that the webs (S1 or S2) of the respective bipolar plate ( 3.1 or 3.2 ) alternately have different heights (H1.1, H1.2 or H2.1, H2.2). Fuel cell assembly ( 1 ) according to claim 4 or 5, characterized in that the two bipolar plates ( 3.1 . 3.2 ) are arranged to each other such that webs (S1 and S2) with different heights (H1.1 and H2.2 or H1.2 and H2.1) are arranged opposite to each other. Fuel cell assembly ( 1 ) according to one of the preceding claims, characterized in that the webs (S1, S2) and / or channels (K1, K2) of each bipolar plate ( 3.1 . 3.2 ) have at least one varying channel width (b _K1 , b _K2 ), a varying land width (b _S1 , b _S2 ) and / or a varying channel spacing (a ₁ , a ₂ ). Fuel cell assembly ( 1 ) according to claim 7, characterized in that the two bipolar plates ( 3.1 . 3.2 ) are arranged to each other such that webs (S1 and S2) with different web widths (b _S1.1 and b _S2.2 or b _S1.2 and b _S2.1 ) are arranged opposite to each other. Fuel cell assembly ( 1 ) according to claim 7 or 8, characterized in that the two bipolar plates ( 3.1 . 3.2 ) are arranged to each other such that webs (S1 and S2) with different web widths (b _S1.1 and b _S2.2 or b _S1.2 and b _S2.1 ) and / or with different heights (H1.1 and H2. 2 or H1.2 and H2.1) are arranged opposite one another or at least partially or completely offset from one another. Fuel cell assembly ( 1 ) according to one of the preceding claims, characterized in that the two bipolar plates ( 3.1 . 3.2 ) are arranged in such a way that a total height of an arrangement of two bipolar plates ( 3.1 . 3.2 ) and the intervening membrane electrode assembly ( 2 ) is constant. Fuel cell assembly ( 1 ) according to one of the preceding claims, characterized in that the webs (S1, S2) of the two bipolar plates ( 3.1 . 3.2 ) have rounded ridge edges. Fuel cell assembly ( 1 ) according to one of the preceding claims, characterized in that the webs (S1, S2) of the two bipolar plates ( 3.1 . 3.2 ) have an uneven web surface, in particular an oblique or oval web surface. Fuel cell assembly ( 1 ) according to one of the preceding claims, characterized in that the membrane electrode assembly ( 2 ) of two gas diffusion electrodes ( 2.1 . 2.2 ) and an intervening polymer electrolyte membrane ( 2.3 ) is formed. Fuel cell assembly ( 1 ) according to claim 13, characterized in that the gas diffusion electrodes ( 2.1 . 2.2 ) is designed as a flexible, in particular rollable position. Fuel cell assembly ( 1 ) according to one of the preceding claims, characterized in that two directly adjacent bipolar plates ( 3 ) are arranged to each other such that negative structures of the channels (K1, K2) and the webs (S1, S2) cooling channels (KK) and / or Zu form dosage channels.