GB2525951A

GB2525951A - Bipolar plate assembly, fuel cell system and vehicle

Info

Publication number: GB2525951A
Application number: GB1421472.0A
Authority: GB
Inventors: Martin Keuerleber; Stephen Wade; Claudette Kennette; Vaibhav Patel
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2014-12-03
Filing date: 2014-12-03
Publication date: 2015-11-11
Anticipated expiration: 2034-12-03
Also published as: GB201421472D0; DE102015015392A1; GB2525951B

Abstract

A bipolar plate assembly 28 for fuel cell stacks suitable for vehicles comprises anode 30 and cathode 32 plates. A sealing element 38 is applied to one side of assembly 28 and seals between the assembly 28 and an adjacent membrane electrode assembly in use. The two plates 30, 32 are bonded to each other by a bond 36, such as a weld, differing from the sealing element 38. One of the plates 30, 32 comprises an interlocking element 40 for fixing the sealing element 38 to the assembly 28. In an area of the interlocking element 40 a sealing element portion is located in a space 66 between the two plates 30, 32. The interlocking element may be formed in the anode 30 and comprise base regions 54 extending from welds 36 to slope regions 56 either side of and leading to a third region 54 parallel to the cathode 32. The third region may include openings 46 which allow sealing material to enter and encapsulate the interlocking element during injection moulding of seal 38. The interlocking element may have a curved profile (Figure 5). The sealing element may comprise flat portions 70 either side of a bulge 68.

Description

Bipolar plate assembly, fuel cell system and vehicle The invention relates to a bipolar plate assembly for a fuel cell stack. The bipolar plate assembly comprises an anode plate and a cathode plate. At least one sealing element is applied to at least one side of the bipolar plate assembly. The two plates are bonded to each other by bonding means which differ from the at least one sealing element. The invention further relates to a fuel cell system with a fuel cell stack comprising a plurality of such bipolar plate assemblies and to a vehicle with such a fuel cell system.

In a fuel cell system fuel cells such as proton exchange membrane (REM) fuel cells create electricity through the electro-chemical reaction that takes place when a fuel such as hydrogen and an oxidant such as oxygen are passed across opposing sides of an electrolyte membrane. Further a coolant or cooling fluid is typically used to remove the heat generated from this reaction.

The proton exchange membrane fuel cell comprises a membrane electrode assembly (MEA) which comprises an anode, a cathode and the proton exchange membrane arranged between these electrodes. This membrane electrode assembly is arranged between two separator plates, wherein one separator plate comprises channels for the distribution of the fuel and the other separator plate channels for the distribution of the oxidant. The respective channels facing the membrane electrode assembly build a

channel structure which is called a flow field.

In a fuel cell stack a plurality of such unit cells comprising two separator plates and the membrane electrode assembly arranged between the separator plates are often connected in series. In such a fuel cell stack instead of monopolar separator plates bipolar plates are utilized, which are electrically conductive and act as an anode for one unit cell and as a cathode for the adjacent unit cell.

In a bipolar plate assembly a first plate acting as an anode for a first unit cell and a second plate acting as a cathode for the adjacent unit cell can be bonded together, for example by welding. As the reactants in form of the fuel and the oxidant and the coolant need to be kept separated from each other, the bipolar plate assembly typically comprises sealing elements which can be applied to the anode plate and to the cathode plate. Such sealing elements, for example in the form of elastomeric seals, are thus used to maintain all the gases and the fluids within the areas they are intended to function in.

Document US 6 338 492 Bi describes a fuel cell stack with bipolar plates provided with channels for gases and liquids. Sealing elements which face a membrane electrode assembly interposed between two bipolar plates are inserted into grooves provided in the respective bipolar plates. The sealing elements are injected into each groove in a way that a free gap is provided between the sealing element and lateral walls of the groove.

To retain the sealing element in the groove blind holes are provided in a bottom of the groove and the sealing element forms plugs which are inserted in the blind holes. Thus, the sealing element is anchored to the bipolar plate. Further, on the opposite side of the groove a bore hole can be provided which is connected to the groove through a smaller through hole. When the sealing element is injected into such grooves stoppers are formed in the bore holes, which retain the sealing element on the bipolar plate.

Document US 2004/0180255 Al describes a fuel cell arrangement comprising two stacked plates which are joined to one another to form a module. Between such modules membranes are arranged with an anode catalyst on one side and a cathode catalyst on the other side. The plates are joined to one another by a common seal element of polymer material which is injected onto the plates. A tunnel like cavity can be formed by the two plates in an area in which the seal element is located. The cavity is accessible via openings which can be machined in one plate or in both plates. When the seal element is produced, seal material penetrates through the openings into the cavity so that the seal material fills the cavity. Thus, an adhesive connection can be produced by which the plates are held together.

It is the object of the present invention to provide a bipolar plate assembly of the initially mentioned kind, a fuel cell system with such bipolar plate assemblies and a vehicle with such a fuel cell system, which provides for a particularly accurate positioning of the sealing element.

This object is solved by a bipolar plate assembly having the features of claim 1, by a fuel cell system having the features of claim 9 and by a vehicle having the features of claim 10. Advantageous configurations with convenient developments of the invention are specified in the dependent claims.

The bipolar plate assembly according to the invention comprises an anode plate and a cathode plate. At least one sealing element is applied to at least one side of the bipolar plate assembly. The two plates are bonded to each other by bonding means which differ from the at least one sealing element. At least one of the two plates comprises an interlocking element which is configured to fix the at least one sealing element to the plate having the interlocking element. In an area comprising the interlocking element a portion of the at least one sealing element is located in a space between the two plates. Thus, the sealing element is reliably held in place and securely anchored to the plate comprising the interlocking element. However, it is not the role of the sealing element to hold the two plates together. The two plates are rather bonded to each other by the bonding means which are different from the at least one sealing element. As the interlocking element securely fixes the sealing element to the plate, a particularly accurate positioning of the sealing element on the plate can be achieved.

The importance of this accurate positioning is related to the fact that the components used within each unit cell or each recurring layer of the fuel cell stack have accumulative tolerances which should be accounted for in the design of the sealing element. The extremely small unit cell pitch for current proton exchange membrane fuel cell stacks requires comparatively small sealing elements with for example a thickness of less than 1 mm and having extremely tight tolerances of for example less than 50 pm. Also, the sealing function of the at least one sealing element depends on achieving a correct alignment or positioning of the sealing element relative to the plate or substrate it is applied to. Maintaining this alignment is critical to effectively hold the sealing element in place during all of the manufacturing and handling processes in order to ensure the proper functionality of the sealing element. By providing the interlocking element on at least one of the two plates of the bipolar plate assembly the at least one sealing element is successfully held in place, as the portion located in the space between the two plates acts as an undercut such that the at least one sealing element mechanically grips the plate.

The at least one sealing element is preferably applied to the plate by injection molding.

However, the binding of the sealing element to the plate needs only to be strong enough to allow demolding of the bipolar plate assembly from the injection molding tool without the sealing element being displaced during demolding. After the demolding the force which fixes at least one sealing element to the plate having the interlocking element can diminish, for example due to cooling of the sealing element.

Providing the interlocking element on at least one of the two plates is particularly advantageous if the plates of the bipolar plate assembly are made of metal. Such metal plates as the substrate to which the sealing element is applied typically have a coating on top of the metal surface, which inhibits corrosion and improves conductivity. Such a coating can make it more difficult for the sealing element to sufficiently adhere to the plate to keep it in place. However, this problem is overcome as the plate comprises the interlocking element. Therefore no primer needs to be applied to the coating on the metal surface in order to increase the adherence of the sealing element to the plate material.

Thus, the effort and the costs associated with the application of a primer can be avoided during manufacturing of the bipolar plate assembly.

Also, providing the interlocking element on the plate to hold the sealing element in place is more suitable for volume production than the addition of a priming or adhesive application process prior to the application of the sealing element. As with the present bipolar plate assembly there is no need to add any kind of primers to the plate, the risk of contaminating other components within the fuel cell with primer is also reduced.

Moreover, primers can degrade over time and affect the bonding process of the sealing element to the plate. This is in particular true in aggressive environments like that of the fuel cell environment. Also health issues associated with the utilization of primers that are hazardous can be avoided. And the problem associated with successfully holding an injected sealing element in place on a metal substrate is solved.

In an advantageous embodiment the interlocking element comprises a base region in which the plates which are bonded to each other are substantially parallel and a second region adjacent to the base region. In the second region the plate fixing the at least one sealing element has a slope, and the at least one sealing element encapsulates at least the second, sloped region. In this way the sealing element material flowing below the second region and thus encapsulating the sloped region from above and below acts as a mechanical interlock which holds the seal in place on the plate. The sealing material can also get between the two plates in the base region, in which the plates are close to each other but a gap can exist which may taper towards the bonding means. With such a configuration of the interlocking element the at least one sealing element is reliably fixed to the plate and held in place on the plate.

This is in particular valid if the interlocking element comprises a third region adjacent to the second region, wherein the plates are substantially parallel in the third region and the at least one sealing element also encapsulates the third region. With such a configuration the interlocking element has a platform-like base region, a ramp-like second region and again a platform-like third region. Such an interlocking element is easy to manufacture and particularly reliable for holding the sealing element in place.

In addition or alternatively the interlocking element can comprise two base regions facing each other and in which the plates are substantially parallel and a bridge region connecting the two base regions. Herein the at least one sealing element encapsulates at least the bridge region. The bridge region can in particular be curved. Further bridge region can have a flat top portion and sloped or curved flanks leading to the flat top portion. The material forming the sealing element can readily flow below the bridge region and also cover the bridge region during the application of the sealing material to the plate.

Therefore the bridge region can reliably be surrounded or enclosed by the sealing element. This leads to a strong fixing of the sealing element to the plate.

In a further alternative or additional embodiment the interlocking element can comprise a base region adjacent to the bonding means, wherein in this base region the plates are substantially parallel. The portion of the at least one sealing element, which is located in the space between the two plates is then limited to one side by the base region. With such a configuration a very flat interlocking element is provided which helps minimizing the height of the bipolar plate assembly and thus of the unit cells of a fuel cell stack comprising a plurality of the bipolar plate assemblies.

In order to allow a particularly even distribution of the sealing material in the spaces between the two plates, at least one opening and preferably a plurality of openings can be provided between two second regions and/or between two third regions facing each other in a width direction of the at least one sealing element if the interlocking element comprises the second regions and/or the third regions. In a like manner the at least one opening can be provided between two base regions facing each other in the width direction of the at least one sealing element.

Preferably the interlocking element is continuous in a length direction of the at least one sealing element, wherein in the length direction a dimension of the at least one sealing element is greater than in a width direction of the at least one sealing element. Compared to intermittent mechanical interlocking elements or interlocking features much less bonding means are required adjacent to the continuous interlocking element in order to prevent the sealing element material from going freely between the plates. Thus, utilizing a continuous interlocking element significantly reduces the effort in the manufacturing of the bipolar plate assembly.

This is in particular valid if the bonding elements are formed as welds aligned along the length direction. In the case of intermittent interlocking elements welds around each one of these elements cause a significant distortion of the plate. Such a distortion leads to a variation in the thickness and height of the sealing element which in turn negatively impacts the sealing function. With a continuous interlocking element the number of welds is significantly reduced as the welds do not need to go around each one of the individual interlocking elements. The reduced number of welds lowers the plate distortion which is otherwise created from circumferential welds around individual interlocking elements. As by utilizing continuous interlocking elements plate distortion is minimized, the resulting impacts from variations in seal thickness and seal height can be avoided.

By providing the welds arranged parallel to the interlocking element as the bonding means it can be particularly easily and well assured that no sealing element material gets between the plates beyond the welds.

However, it is advantageous if the sealing element comprises a flat portion which extends beyond the welds in the width direction of the interlocking element which coincides with the width direction of the sealing element. Thus, on the surface of the plate having the interlocking element the sealing element extends further in the width direction than in the space between the two plates. With such a relatively wide sealing element manufacturing tolerances of the plates and of plate features such as ports or openings for the reactants and/or the coolant can be compensated for.

Further the sealing element can in particular comprise a bulged region or bulge having a greater height than the flat portions extending beyond the welds. Such a design of the sealing element can particularly well provide the sealing function necessary across the entire fuel cell stack with all the manufacturing tolerances of each of the components of the fuel cell stack.

To provide the sealing element preferably soft and elastic materials can be utilized. In particular a silicone rubber material can constitute the sealing element. Further fluoroelastomers such as FKM can be utilized or an ethylene propylene diene monomer (ERDM) rubber. Still further a Rolyisobutylene (RIB) material such as a Butyl rubber can constitute the material utilized to form the sealing element. However, silicone materials such as silicone rubber are preferred. With Such materials, in particular silicone materials, providing the interlocking element is highly beneficial in order to hold the sealing element in place on the plate.

The at least one sealing element can in particular be applied to the bipolar plate assembly by injection molding. However, the at least one sealing element is preferably applied to only one side of the bipolar plate assembly. To provide a sealing element on the other side of the bipolar plate assembly gravure printing can be utilized and other materials can be chosen to provide a sealing element which show a better adhesion to the plate surface even if a corrosion inhibiting coating is provided on the metal surface.

Thus, a sealing element of greater height can be provided on the side of the bipolar plate assembly which comprises the interlocking element whereas a rather flat sealing element is provided on the other side. This leads to a reduced height of the overall bipolar plate assembly comprising different sealing elements on both sides wherein the injection molded sealing element is held in place by the interlocking element.

Finally it has proven advantageous if the bipolar plate assembly comprises a coolant flow field between the cathode plate and the anode plate. Thus, heat generated during the electrochemical fuel cell reaction can be efficiently removed.

The fuel cell system according to the invention, which in particular can be employed in a vehicle, includes a fuel cell stack with a plurality of bipolar plate assemblies according to the invention. Herein a membrane electrode assembly is arranged between a pair of bipolar plate assemblies of the fuel cell stack.

S

Such a fuel cell system can include a plurality of further components usual in particular for fuel cell systems of vehicles, which presently do not have to be explained in detail.

The vehicle according to the invention includes a fuel cell system according to the invention.

The advantages and preferred embodiments described for the bipolar plate assembly according to the invention also apply to the fuel cell system according to the invention and to the vehicle according to the invention.

The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of figures and/or shown in the figures alone are usable not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the invention.

Thus, implementations are also to be considered as encompassed and disclosed by the invention, which are not explicitly shown in the figures or explained, but arise from and can be generated by separated feature combinations from the explained implementations.

Further advantages, features and details of the invention are apparent from the claims, the following description of preferred embodiments as well as based on the drawings in which features having analogous functions are designated with the same reference signs.

Therein show: Fig. 1 schematically components of a fuel cell system of a vehicle, the fuel cell system comprising a fuel cell stack with bipolar plate assemblies and membrane electrode assemblies interposed between the bipolar plate assemblies, wherein each bipolar plate assembly comprises an anode plate bonded to a cathode plate; Fig. 2 a sectional view of the bipolar plate assembly according to Fig. 1, the bipolar plate assembly comprising a sealing element fixed to one of the plates by an interlocking element which holds the sealing element in place on the plate; Fig. 3 a sectional view of a variation of the interlocking element shown in Fig. 2; Fig. 4 a variant of the bipolar plate assembly, wherein the sealing element is fixed to the plate by an interlocking element comprising a curved bridge region; Fig. 5 a sectional view of the bridge region shown in Fig. 4; Fig. 6 a variation of the bridge region shown in Fig. 5, wherein the bridge region comprises a flat top portion; and Fig. 7 another variant of the bipolar plate assembly, wherein the interlocking clement is comparatively flat.

A fuel cell system 10 of a vehicle comprises a fuel cell stack 12 to which fuel such as hydrogen is provided via a supply line 14. The fuel can be stored in a tank 16. Upon leaving the fuel cell stack 12 via an exhaust line 18 any fuel remaining in the exhaust gas can be recirculated to the fuel cell stack 12 via a recirculation line 20. The fuel is provided to anode electrodes of membrane electrode assemblies 22. In a like manner an oxidant such as air is provided via a supply line 24 to cathode electrodes of the membrane electrode assemblies 22. The exhaust air leaves the fuel cell stack 12 via a further exhaust line 26. The electrochemical reaction which creates electrical energy takes place when the fuel and the oxidant are passed across opposing sides of the membrane electrode assemblies 22.

The membrane electrode assemblies 22 are arranged between bipolar plate assemblies 28, which comprise an anode plate 30. The anode plate 30 faces the anode electrode of a membrane electrode assembly 22 of a first unit cell. The bipolar plate assembly 28 further comprises a cathode plate 32 which faces the cathode electrode of the membrane electrode assembly 22 of a second, adjacent unit cell. Only the outermost electrode assemblies 22 in the fuel cell stack 12 are not sandwiched between two bipolar plate assemblies 28, but between one bipolar plate assembly 28 and an end plate 34. The anode plate 30 and the cathode plate 32 of each bipolar plate assembly 28 are preferably made of metal and are preferably bonded to each other by bonding means such as welds 36 (see Fig. 2). The plates 30, 32 joined together in the bipolar plate assembly 28 preferably form a coolant flow field (not shown), i.e. a channel structure for a coolant fluid which removes heat generated by the electrochemical reaction taking place in the membrane electrode assemblies 22.

In order to keep the reactants such as the hydrogen and the air as well as the exhaust fluids and the coolant separated from each other, a number of sealing elements 38 is typically provided on the bipolar plate assembly 28. In Fig. 2 only one such sealing element 38 is shown.

The metal bipolar plate assemblies 28 typically have a coating on top of the metal surface which inhibits corrosion and improves conductivity. Such a coating makes it difficult for the material of the sealing element 38 to adhere to the surface of one of the plates 30, 32, for example to the surface of the anode plate 30 (see Fig. 2). This is in particular true if a silicone material such as silicone rubber is utilized to form the sealing element 38 in an injection molding process.

Therefore, in the bipolar plate assembly 28 one of the plates 30, 32, for example the anode plate 30, comprises an interlocking element 40 in an area between the welds 36, which are aligned along a length direction 42 indicated in Fig. 2 by an arrow. In this length direction 42 a dimension of the sealing element 38 is greater than in a width direction 44 of the sealing element 38, which is indicated in Fig. 2 by another arrow.

The interlocking element 40 is continuous in the length direction 42. Consequently the welds 36 are only present at both sides of the interlocking element 40. The interlocking element 40 shown in Fig. 2 comprises raised mechanical features including openings or slots 46 alternating with bridges 48. The slots 46 which are of rectangular shape in the present embodiment but which can be of different shapes in other embodiments can have a length 50 and a width 52 which can vary from one embodiment of the bipolar plate assembly 28 to another.

In the area of the slots 46 and the bridges 48 the interlocking element 40 comprises base regions 54 in which the plates 30, 32 are substantially parallel. These base regions 54 extend from the welds 36 towards a sloped second region 56 of the interlocking element in the embodiment shown in Fig. 2. The interlocking element 40 further comprises a third region 58 adjacent to the sloped second region 56. In the area of the slots 46 two such third regions 58 are facing each other in the width direction 44 of the sealing element 38. In the embodiment shown in Fig. 2 the third regions 58 of the anode plate 30 are parallel to the cathode plate 32.

The length of the sloped regions 56 defines a height 60 of the interlocking element 40, wherein the height 60 can vary according to the design of the bipolar plate assembly 28 and in particular of the sealing element 38. In a like manner a length 62 of the bridges 48 of the interlocking element 40 can vary from one embodiment of the bipolar plate assembly 28 to another. This length 62 corresponds to a distance between two adjacent slots 46. Further a distance 64 between the sloped second regions 56 and the welds 36 and thus a width of the base regions 54 can vary from one design of the bipolar plate assembly 28 to another.

As material of the sealing element 38 is applied to the plate 30 by injection molding, the dimension of the slots 46 has an influence on the flow of the material in a space 66 between the two plates 30, 32. Such a space 66 is for example present below the second, sloped regions 56 and the third, flat regions 58 of the anode plate 30 and above the cathode plate 32. The space 66 is further present below the bridges 48. Further, the injected material can get between the plates 30, 32 in the base regions 54 until it reaches the welds 36 (see Fig. 7). By portions of the sealing element 38 which occupy these spaces 66 the sealing element 38 is mechanically fixed to the plate 30 and is thus securely held in place. This is in particular important during demolding of the bipolar plate assembly 28 from the injection molding tool utilized to apply the sealing element 38 to the plate 30.

However, the injected material of the sealing element 38 does not only flow in the space 66 between the plates 30, 32 but it also covers the area of the slots 46 and bridges 48.

Thus by flowing above and below the raised parts of the interlocking element 40 the metal features such as the third regions 58, the sloped second regions 56 and the bridges 48 are encapsulated by material of the sealing element 38. By encapsulating these formed metal features the injected material acts as a mechanical interlock which holds the sealing element 38 in place on the plate 30.

In the embodiment shown in Fig. 2, the sealing element 38 forms a bulge 68 in an area extending between the sloped regions 56. The sealing element 38 further comprises flat portions 70 which extend from the bulge 68 in the width direction 44 towards the welds 36 arranged in lines parallel to the interlocking element 40. These flat portions 70 are located above the base regions 54 of the interlocking element 40. In these flat portions 70 the material of the sealing element 38 can extend beyond the welds 36 in the width direction 44 of the interlocking element 40.

As can be seen from Fig. 3, the interlocking element 40 can comprise only the second, sloped region 56 in the area of the slots 46. Also the extension of the third region 58 in the width direction 44 of the sealing element 38, which coincides with a width direction 44 of the interlocking element 40, can vary from one design to another. In the variant shown in Fig. 3 the width 52 of the slots 46 is such that no third region 58 is present anymore, wherein in Fig. 2 two third regions 58 of a certain extension in the width direction 44 are facing each other. A number of variations and transitions between these exemplary configurations can be present in alternative forms of the bipolar plate assembly 28. With other words the shape of the interlocking element 40 can vary from one design of the bipolar plate assembly 28 to another.

The bipolar plate assembly 28 shown in Fig. 4 comprises an interlocking element 40 which also comprises base regions 54 in which the plates 30, 32 are parallel. Also in this embodiment it can be possible that the material of the sealing element 38 flows in a space 66 between the plates 30, 32 until the material reaches the welds 36 (see Fig. 7).

The space 66 is then provided in the area of the base regions 54.

Further the bridges 48 in the embodiment shown in Fig. 4 are configured as curved bridge regions which connect the two base regions 54 facing each other. In this embodiment the injected material that forms the sealing element 38 in the injection molding process can flow above and below the bridges 48, and it encapsulates the bridge features. Thus, the injected material acts as a mechanical interlock to hold the sealing element 38 in place on the plate 30.

The width 52 of the slots 46 or openings between the base regions 54 can be varied according to the design of the bipolar plate assembly 28. Also the height 60 of the bridges 48 can be varied as needed to suit the design. Further the distances 64 from the bottom of the bridge 48 to the welds 36 can be varied. As in the embodiment shown in Fig. 2 also the length 62 of the bridges 48 and the length 50 of the slots 46 can be varied as needed.

In the embodiment shown in Fig. 4 the bridges 48 have a curved form which corresponds to the curved form of the bulge 68 formed by the sealing element 38. However, the form of the bridges 48 can vary. Fig. 5 shows the smoothly but continuously curved bridge 48 presented in Fig. 4 in a section view, whereas Fig. 6 shows a bridge region or bridge 48 with a flat top portion 72. Variations and transitions between the forms shown in Fig. 5 and in Fig. 6 can be provided in alternative designs of the bipolar plate assembly 28.

In the embodiment shown in Fig. 7 the bipolar plate assembly 28 has a comparatively flat interlocking element 40. There are the openings or slots 46 between the base regions 54 facing each other. However, there are no elevated features such as the bridges 48 shown in Fig. 2 and in Fig. 4. In the variant shown in Fig. 7 the injected material which forms the sealing element 38 in the injection molding process can flow above and between the plates 30, 32 in the spaces 66 provided between the plates 32, 34 in the base regions 54.

The injected material can flow in these spaces 66 until it reaches the welds 36. The portion of the sealing material which occupies the spaces 66 acts as an interlock feature which holds the sealing element 38 in place on the plate 30.

As discussed above, also in the embodiment shown in Fig. 7 the width 52 of the slots 46 can be varied in order to facilitate the entry of the sealing element 38 material in the spaces 66 or gaps between the two plates 30, 32 during injection molding. Further, the distances 64 from outer borders of the slots 46 to the welds 36 can be varied. Still further a length 62 of the part of the interlocking element 40, which is formed by the plate 30 between the slots 46 can be varied as needed.

List of reference signs fuel cell system 12 fuel cell stack 14 supply line 16 tank 18 exhaust line recirculation line 22 membrane electrode assembly 24 supply line 26 exhaust line 28 bipolar plate assembly anode plate 32 cathode plate 34 end plate 36 weld 38 sealing element interlocking element 42 length direction 44 width direction 46 slot 48 bridge length 52 width 54 base region 56 second region 58 third region height 62 length 64 distance 66 space 68 bulge flat portion 72 top portion

Claims

Claims Bipolar plate assembly for a fuel cell stack (12), comprising an anode plate (30) and a cathode plate (32), wherein at least one sealing element (38) is applied to at least one side of the bipolar plate assembly (28), and wherein the two plates (30, 32) are bonded to each other by bonding means (36) differing from the at least one sealing element (38), characterized in that at least one of the two plates (30, 32) comprises an interlocking element (40) configured to fix the at least one sealing element (38) to the plate (30), wherein in an area comprising the interlocking element (40) a portion of the at least one sealing element (38) is located in a space (66) between the two plates (30, 32).
2. Bipolar plate assembly according to claim 1, characterized in that the interlocking element (40) comprises a base region (54) in which the plates (30, 32) are substantially parallel and a second region (56) adjacent to the base region (54), in which the plate (30) fixing the at least one sealing element (38) has a slope, wherein the at least one sealing element (38) encapsulates at least the second region (56).
3. Bipolar plate assembly according to claim 2, characterized in that the interlocking element (40) comprises a third region (58) adjacent to the second region (56), in which the plates (30, 32) are substantially parallel, wherein the at least one sealing element (38) also encapsulates the third region (58).
4. Bipolar plate assembly according to any one of claims ito 3, characterized in that the interlocking element (40) comprises two base regions (54) facing each other and in which the plates (30, 32) are substantially parallel and a bridge region (48) connecting the two base regions (54), wherein the at least one sealing element (38) encapsulates at least the bridge region (48).
5. Bipolar plate assembly according to any one of claims ito 4, characterized in that the interlocking element (40) comprises a base region (54) adjacent to the bonding means (36), in which the plates (30, 32) are substantially parallel, wherein the portion of the at least one sealing element (38) located in the space (66) is limited to one side by the base region (54).
6. Bipolar plate assembly according to any one of claims 2 to 5, characterized in that at least one opening (46) is provided between two second regions (56) and/or between two third regions (58) and/or between two base regions (54) facing each other in a width direction (44) of the at least one sealing element (38).
7. Bipolar plate assembly according to any one of claims ito 6, characterized in that the interlocking element (40) is continuous in a length direction (42) of the at least one sealing element (38), in which a dimension of the at least one sealing element (38) is greater than in a width direction (44) of the at least one sealing element (38), wherein the bonding means are formed as welds (36) aligned along the length direction (42).
8. Bipolar plate assembly according to any one of claims ito 7, characterized in that the at least one sealing element (38) is applied, in particular by injection molding to only one side of the bipolar plate assembly (28), in particular comprising a coolant flow field between the cathode plate (32) and the anode plate (30).
9. Fuel cell system (10), in particular for a vehicle, with a fuel cell stack (12) comprising a plurality of bipolar plate assemblies (28) according to any one of claims 1 to 8, wherein a membrane electrode assembly (22) is arranged between a pair of the bipolar plate assemblies (28) of the fuel cell stack (12).
10. Vehicle with a fuel cell system (10) according to claim 9.