DE102010048762A1 - Bipolar plate for fuel stack for vehicle, has membrane electrode arrangement comprises electrode that is coupled to channels of the inner structure - Google Patents

Abstract

The bipolar plate has a sub panel (1) comprising a frame (2) to which an inner structure (3) is connected. Several channels (4) are provided in the inner structure. An electrode of membrane electrode arrangement is coupled to channels of the inner structure. The passages (6-8,6'-8') are provided in the boundary portion of the frame for supplying medium such as fuel or air to inner structure. The inner structure and frame are clamped together by an adhesive. An independent claim is included for method for manufacturing bipolar plate for fuel stack.

Description

The invention relates to a bipolar plate for a fuel cell stack, with at least one frame part which is coupled to at least one inner part. The at least one inner part has a plurality of channels, via which an electrode of a membrane electrode assembly of the fuel cell can be acted upon by a reactant. Furthermore, the invention relates to a method for manufacturing a bipolar plate.

The DE 600 17 604 T2 describes a bipolar plate for a molten carbonate fuel cell. The bipolar plate is formed of an inner plate member and four frame members. The four frame parts are each formed as open to a top and a side adjacent to the top side boxes. Two such box-shaped frame parts are connected to an upper surface of the plate member by welding. They form in cooperation with the plate member two lateral, open to one side pockets whose openings are facing each other. In an analogous manner, the two other frame parts are attached by welding to the underside of the plate member, and form on the underside of the plate member has two lateral, unilaterally open pockets. The pockets form wet seals for the molten carbonate fuel cell using the bipolar plate. The plate element is compatible with the oxidizing agent or the fuel used in the fuel cell and highly conductive, such as a nickel-coated stainless steel. In contrast, the frame parts are formed of an aluminum-coated stainless steel and therefore not highly conductive, but extremely resistant to corrosion.

From the DE 102 61 482 A1 Furthermore, a bipolar plate is known, which comprises an inner metal insert part, wherein an edge region of the metal insert part is enclosed in a frame of the bipolar plate, which is formed as an injection molded part.

A disadvantage of such, bipartite bipolar plates is the fact that the production of these bipolar plates is relatively complex.

Object of the present invention is therefore to provide a simple and inexpensive to produce bipolar plate and a corresponding manufacturing process.

This object is achieved by a bipolar plate having the features of patent claim 1 and by a method having the features of patent claim 10. Advantageous embodiments with expedient developments of the invention are specified in the dependent claims.

The bipolar plate according to the invention for a fuel cell stack comprises at least one frame part, which is mechanically coupled to at least one inner part. The at least one inner part has a plurality of channels, via which an electrode of a membrane electrode assembly of the fuel cell can be acted upon by a reactant. Here, the at least one inner part and the at least one frame part are clamped together for coupling. If, in fact, the at least one inner part is connected to the at least one frame part by jamming, it is possible to provide a process-technically particularly simple and thus cost-producible multi-part bipolar plate whose parts are connected to one another at defined interfaces. If only an inner part is to be coupled with a frame part, then the inner part only needs to be clamped in the frame part, and the inner part is then fixed in a position-secured manner at the point provided for this purpose. Such a jamming of the two parts together is to accomplish much faster than overmolding of the inner part with the frame part in an injection molding or welding of the two parts together.

By providing separate parts of the bipolar plate, namely the at least one frame part and the at least one inner part, forming processes can be used for the respective molding part, which are particularly well matched to the function to be performed by the part in the bipolar plate. Thus, a conventional embossing process, which in one of the prior. Technology known manufacturing both for shaping the edge region of the bipolar plate and the integrally formed with this inner part is used for the shaping of the frame part. With such an embossing process, however, only channels of limited width and depth can be produced in the inner part. By virtue of the fact that in the present case the inner part is provided separately from the frame part, a shaping method can be used for the shaping of the channels of the inner part, which is aligned solely with the optimal design of the channels and does not need to take into account the shape of the frame part.

Due to the defined multiple division of the bipolar plate in the at least one frame part and the at least one inner part, which are joined together after the individual production by a clamping connection, then a particularly efficient bipolar plate can be achieved. This leads to a particularly high efficiency of the fuel cell stack. Internal parts with one for the distribution of the fuel or the oxidant particularly favorable channel structure, such as with particularly deep and very narrow channels, namely allow a particularly favorable distribution of the reactants in the region of the membrane electrode assembly of the bipolar plate having fuel cell.

As a result of the bipolar plates constructed as described herein, it is thus possible to achieve particularly high energy densities of the individual components, which lead to lower costs of the fuel cell stack for a given performance to be achieved. Due to the high efficiency of the fuel cell stack can also be realized a lightweight construction, which is particularly advantageous if the fuel cell stack is to be used in a vehicle. In addition, conventionally available process techniques can be used in the shaping of the frame part and the inner part, whereby highly complex designs, in particular of the inner part, can also be realized.

The jamming of the inner part with the at least one frame part can be realized particularly well if at least the at least one inner part is formed from a metal.

In an advantageous embodiment of the invention, the at least one inner part has a marginal web on which it is in contact with the at least one frame part. By means of such an edge web of the inner part, a particularly large contact surface of the inner part on the frame part can be realized, so that the inner part connected to the frame part by the clamping connection is held particularly good non-positively on the frame part.

Alternatively or additionally, the at least one inner part is held on the at least one frame part at least in regions by an adhesive. By using an adhesive, in particular in areas in which a particularly high tightness of the connection between the inner part and the frame part is desired, it can be realized particularly reliably.

In particular, if the frame part is made of an electrically non-conductive material, it is advantageous to use a likewise electrically non-conductive adhesive at the connection points of the inner part with the frame part. In order to save material costs and processing costs, it can be provided in particular, not to provide the outer circumferential side of the adhesive around the inner part, but only in partial areas.

A particularly secure and simple fixing of the inner part to the frame part can be achieved if the at least one inner part and / or the at least one frame part has at least one positive locking element for the positive connection of the parts to one another. As a form-fitting element can be provided in particular a locking element or a headband.

In a further advantageous embodiment of the invention, the at least one frame part has at least one stop for the at least one inner part. It then needs when manufacturing the bipolar plate, the inner part to be moved only to the stop to ensure a correct position positioning of the inner part. It can thus be ensured in particular that there is no undesired displacement of the inner part in relation to the frame part perpendicular to a plane given by the plate-like shape of the bipolar plate. To facilitate the insertion of the inner part in the frame part may also be provided on the frame part, a lateral stop, which also provides in the direction of the definable by the extension of the bipolar plate level for a clamping of the inner part with the frame part facilitating alignment of the parts to each other.

In a further advantageous embodiment of the invention, the at least one frame part on a bulge, through which a bearing surface is formed for a sealing element. As a result, it is particularly easy to achieve a gastight fit of the membrane-electrode arrangement of the respective fuel cell on the bipolar plate.

It is also advantageous if the channels are introduced into the at least one inner part by roll forming or forming rolls. In particular, these forming techniques make it possible to form deeper and narrower channels in the inner part than would be possible by a stamping process. Such deep and narrow channels are particularly favorable with regard to the electrochemical reaction of the reactants on the membrane electrode assembly.

In a further advantageous embodiment of the invention, a base body is formed by a first frame part with at least one passage for one of the reactants or for a coolant, to which a second frame part is arranged with at least one further passage for one of the reactants or for the coolant. It can thus be realized for the at least two frame parts particularly simple and thus inexpensive producible forms, which also bring in the manufacture of the frame parts particularly little waste. In particular, the first frame part may form a rectangular basic body, on which the second, for example one or two passages having frame part is arranged.

Finally, it has proven to be advantageous if a cathode-side or an anode-side partial plate of the bipolar plate is formed by the at least one frame part and the associated at least one inner part, which can be coupled to the corresponding partial plate. It is thus possible to realize specific shapes for the inner parts of the cathode-side sub-plate and the anode-side sub-plate, as is particularly favorable for charging the cathode with the oxidizing agent and for charging the anode with the fuel. Thus, the channels in the inner part of the cathode-side partial plate may be deeper than those in the inner part of the anode-side partial plate.

In the method according to the invention for manufacturing a bipolar plate for a fuel cell stack, at least one frame part is coupled to at least one inner part which has a plurality of channels via which an electrode of a membrane-electrode arrangement of the fuel cell can be acted upon by a reactant. Here, the at least one inner part is connected to the at least one frame part by jamming. This method allows a particularly simple and cost-effective production of the bipolar plate, since the process step of jamming the parts together is particularly fast feasible.

The advantages and preferred embodiments described for the bipolar plate according to the invention also apply to the method according to the invention for manufacturing a bipolar plate.

The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

Further advantages, features and details of the invention will become apparent from the claims, the following description of preferred embodiments and from the drawings. Showing:

1 schematically in a plan view of a partial plate of a bipolar plate, wherein an inner part is connected by clamping with a frame part;

2 schematically in a plan view a section of not yet provided with the inner part frame part according to 1 ;

3 schematically in a plan view of a section of the inner part according to 1 ;

4 a section through the frame part along a line IV-IV in 2 ;

5 a section through the inner part along a line VV in 3 ;

6 the clamped with the frame part inner part in a schematic sectional view;

7 an enlarged detail of a connection region in which the inner part is connected to the frame part;

8th an alternative embodiment of the connection region in an enlarged sectional view; and

9 a further detail enlargement to illustrate a positive fixing of the inner part of the frame part.

An in 1 shown partial plate 1 a bipolar plate for a fuel cell stack is constructed in several parts, in this case in two parts. A frame part 2 the partial plate 1 surrounds an inner part 3 in which a plurality of channels 4 is formed (see. 3 and 5 ). The in the inner part 3 trained channels 4 form a channel structure, which is also referred to as flow field, and about which the reactant, so at a cathode side plate 1 the oxidizing agent or in the case of an anode-side partial plate 1 the fuel, the respective electrodes of a membrane-electrode assembly 5 (see. 8th ) are supplied to the respective fuel cell.

The frame part 2 has no channel structure, but passages 6 . 6 ' . 7 . 7 ' . 8th . 8th' through which the supply and removal of media takes place. For example, the passage serves 6 the supply of the fuel, such as hydrogen, to the flow field of the anode-side inner part 3 the partial plate 1 and the opposite passage 6 ' the removal of unused fuel. In an analogous way, the passage serves 7 supplying the oxidant, such as air or oxygen, to the channels 4 the cathode-side inner part 3 and the passage 7 ' the removal of the oxidizing agent.

To form a bipolar plate, two partial plates 1 coupled to each other, so that at the respectively facing each other surfaces of the sub-plates, a cavity is formed, which consists of the structure of the flow field of a system of several interconnected tunnels. The cavity or system of the tunnels is essentially through the partial plates 1 bordering in the marginal area bordered liquid-tight, being about the passage 8th Coolant introduced into the cavity and over the passage 8th' the coolant is removed.

In peripheral areas 9 . 10 of the inner part 3 are the inner part 3 and the frame part 2 connected with each other. Here, the joining of the two parts takes place by clamping the inner part 3 with the frame part 2 , Especially in the border area 10 , which on the respective short longitudinal side of the present rectangular inner part 3 is formed, in addition by applying an adhesive, the fixing of the inner part 3 on the frame part 2 get supported.

As in the present case, both the inner part 3 as well as the frame part 2 are formed of a metallic material, a compound of the inner part 3 with the frame part 2 additionally done by welding or soldering. For a quick production of the partial plate 1 However, it is particularly advantageous if the joining of the frame part 2 and the inner part 3 by clamping takes place, if necessary, under at least partially application of adhesive, and if a time-consuming welding or soldering is dispensed with. This also allows the frame part 2 made of an electrically non-conductive material.

2 shows the frame part 2 in sections and without that in the frame part 2 inserted inner part 3 (see. 3 ). The frame part 2 can also be formed in several parts itself. In particular, if, as shown here by way of example, the passages 7 . 8th bordering on a base body of the frame part, it may be useful a rectangular body, which the passages 6 . 6 ' has to manufacture separately and to connect laterally over the main body protruding frame parts, which the passages 7 respectively. 7 ' and 8th respectively. 8th' exhibit. Also, in alternative embodiments, all the passages 6 . 7 . 8th be arranged on a short or long longitudinal side of the frame part. Alternatively, only one of the passages 6 . 7 . 8th in a marginally protruding region of the frame part 2 be educated. A rectangular basic body of the frame part 2 can be manufactured from a semi-finished product with very little effort and without much waste.

Also the inner part 3 may be formed in several parts, such as when it has areas with different channel geometry, which can be particularly well made separately from each other by respective forming processes. In such a case, the internal parts can be connected to each other by means of an electrically conductive adhesive.

3 shows the inner part 3 partial, before this in the frame part 2 used and connected to form a clamping connection with this.

In particular from 4 it turns out that the frame part 2 a circumferential and upwardly flat bulge 11 has, which serves as a support surface for a sealing element. This bulge 11 can in the frame part 2 be introduced particularly simple and inexpensive by a stamping process. In contrast, the introduction of the comparatively narrow and deep channels takes place 4 in the inner part 3 (see. 5 ) preferably by roll forming or forming rolls. It can do so for the particular component of the sub-plate 1 to be used for shaping and design of the desired shape particularly favorable forming technology.

6 schematically shows that in the edge regions 9 with the circumferential frame part 2 internal part connected by jamming 3 ,

According to 7 points in the border area 9 in which the inner part 3 with the frame part 2 forms a clamping connection, the inner part 3 a randlichen footbridge 12 on which one with a wall 13 of the frame part 2 in attachment. This is the inner part 3 on the frame part 2 and set to form a frictional connection. A lower stop 14 of the frame part 2 makes sure that with the frame part 2 bound inner part 3 is kept in a defined altitude. Both the frame part 2 as well as the inner part 3 point in this embodiment in the edge region 9 a substantially L-shaped shape.

According to 8th is in the border area 9 in which the inner part 3 with the frame part 2 is connected to the jetty 12 a flat extension 15 formed, which in turn with another stop 16 of the frame part 2 in attachment. Both the frame part 2 as well as the inner part 3 in this embodiment, therefore, in the edge region 9 a substantially Z-shaped shape. In the fuel cell stack acts on the membrane-electrode assembly 5 which the channels 4 to its upper, open side, an area load 17 , which is for intimate contact of the inner part 3 with the membrane electrode assembly 5 provides.

9 finally shows an exemplary embodiment of the edge area 9 in which the wall 13 of the frame part 2 a catch 18 having, which with the narrow side of the web 12 forms a positive connection. In alternative embodiments, other form-fitting elements and / or joining methods for connecting the frame part 2 and the inner part 3 take care of each other.

In the 7 to 9 shown embodiments of the connection area 9 can also in combination with each other for a positionally secure fixing of the inner part 3 on the frame part 2 to care. Also, in addition, at least partially adhesive for a determination of the inner part 3 on the frame part 2 to care.

LIST OF REFERENCE NUMBERS

1

subpanel

2

frame part

3

inner part

4

channel

5

Membrane electrode assembly

6, 6 '

passage

7, 7 '

passage

8, 8 '

passage

9

border area

10

border area

11

bulge

12

web

13

wall

14

attack

15

extension

16

attack

17

distributed load

18

locking lug

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• DE 60017604 T2 [0002]
• DE 10261482 A1 [0003]

Claims (10)

Bipolar plate for a fuel cell stack, comprising at least one frame part ( 2 ), which with at least one inner part ( 3 ), wherein the at least one inner part ( 3 ) a plurality of channels ( 4 ), via which an electrode of a membrane electrode assembly ( 5 ) of the fuel cell can be acted upon by a reactant, characterized in that the at least one inner part ( 3 ) and the at least one frame part ( 2 ) are clamped together for coupling. Bipolar plate according to claim 1, characterized in that the at least one inner part ( 3 ) a randlichen bridge ( 12 ), on which it is connected to the at least one frame part ( 2 ) is in plant. Bipolar plate according to claim 1 or 2, characterized in that the at least one inner part ( 3 ) on the at least one frame part ( 2 ) is held at least partially by a, in particular electrically non-conductive, adhesive. Bipolar plate according to one of claims 1 to 3, characterized in that the at least one inner part ( 3 ) and / or the at least one frame part ( 2 ) at least one positive-locking element ( 18 ), in particular a latching element or a retaining clip, for positively connecting the parts together. Bipolar plate according to one of claims 1 to 4, characterized in that the at least one frame part ( 2 ) at least one attack ( 14 . 16 ) for the at least one inner part ( 3 ) having. Bipolar plate according to one of claims 1 to 5, characterized in that the at least one frame part ( 2 ) a bulge ( 11 ), by which a bearing surface is formed for a sealing element. Bipolar plate according to one of claims 1 to 6, characterized in that the channels ( 4 ) in the at least one inner part ( 3 ) are introduced by roll forming or forming rolls. Bipolar plate according to one of claims 1 to 7, characterized in that by a first frame part with at least one passage ( 6 ) is formed for one of the reactants or for a coolant, in particular rectangular, base body, to which a second frame part with at least one further passage ( 7 . 8th ) is arranged for one of the reactants or for the coolant. Bipolar plate according to one of claims 1 to 8, characterized in that by the at least one frame part ( 2 ) and the associated at least one inner part ( 3 ) a cathode-side or an anode-side partial plate ( 1 ) of the bipolar plate is formed, which is coupled to the corresponding sub-plate. Method for manufacturing a bipolar plate for a fuel cell stack, in which at least one frame part ( 2 ) with at least one inner part ( 3 ), which has a plurality of channels ( 4 ), via which an electrode of a membrane electrode assembly ( 5 ) of the fuel cell can be acted upon by a reactant, characterized in that the at least one inner part ( 3 ) with the at least one frame part ( 2 ) is connected by jamming.

Images