WO2022043342A1

WO2022043342A1 - Fuel cell unit with end plate for combined use as part of a housing and electric power conduction means

Info

Publication number: WO2022043342A1
Application number: PCT/EP2021/073428
Authority: WO
Inventors: Emanuel MATOS SANTANA
Original assignee: Cellcentric Gmbh & Co. Kg
Priority date: 2020-08-26
Filing date: 2021-08-24
Publication date: 2022-03-03
Also published as: DE102021121913A1; GB202013308D0

Abstract

The invention relates to a fuel cell unit, comprising a fuel cell block (2) with a fuel cell for generating electric power from hydrogen and oxygen, an end plate (4) mounted on an end face of the fuel cell block (2) to seal the end face, a power conduction means configured for conducting the electric power from the fuel cell to a connection tab (6) of the fuel cell unit, and an insulating means (5) to insulate the fuel cell block (2) against a surrounding area. To allow a cost reduction, the end plate (4) may be made of an electrically conductive material to provide a functionality of the end plate and the power conduction means in one part, and the insulating means (5) is provided by an electrically insulating coating of the end plate (4) on an outer face (8) of the end plate (4), wherein the outer face (8) is averted to the fuel cell block.

Description

FUEL CELL UNIT WITH END PLATE FOR COMBINED USE AS PART OF A HOUSING AND ELECTRIC POWER CONDUCTION MEANS

FIELD OF THE INVENTION

[0001] The invention relates to the field of fuel cells, particularly fuel cells for use in a motor vehicle. More particular the invention relates to a fuel cell unit which comprises a fuel cell block with at least one fuel cell for generating an electric power from hydrogen and oxygen, with the fuel cell block comprising at least one oxygen inlet and one hydrogen inlet, at least one end plate mounted on an end face of the fuel cell block to seal the end face, a power conduction means configured for conducting the electric power from the least one fuel cell to a connection tab of the fuel cell unit, and an insulating means to insulate the fuel cell block against a surrounding area.

BACKGROUND INFORMATION

[0002] A fuel cell unit usually comprises a fuel cell block with a housing that houses at least one fuel cell for generating electric power from a fuel, for example methanol, hydrogen or natural gas, and oxygen, for example provided in form of ambient air or oxygen-enriched air. The fuel cell block or the housing of the fuel cell block respectively usually comprises at least one open side or at least one open face. This is necessary to provide access to the at least one fuel cell within the housing. The open face of the fuel cell block may be closed or sealed by an end plate. If there are more than one open faces, each open face may be closed or sealed by a respective end plate. The end plate needs to meet certain requirements for stability. To ensure sufficient stability the end plate is usually made of metal of sufficient thickness. [0003] From US 100 031 12 B1 , US 2015 00 99213 A1 , and DE 10 2010 022 024 A1 , a use of different types of bus bars to electrically connect batteries is known.

[0004] CN 109 994 676 A discloses, also in the context of batteries, a self-supporting component comprising a heat conduction plate, and a tab supporting flow guide piece.

[0005] JP 2010 003 626 A shows a fuel cell stack with end plates and a plurality of side plates, wherein one of the end plates and one of the side plates are formed of a similar material.

[0006] The fuel cell unit also comprises a power conduction means to conduct the electric power generated from the at least one fuel cell to where it is used. The power conduction means is usually routed from an inside of the fuel cell block to an outside of the fuel cell block. For example on the outside of the fuel cell unit, a connection tab may be mounted to provide an electrical connecting possibility of the fuel cell unit.

[0007] In this context, US 2015 009 92 13 A1 discloses a fuel cell stack bus bar assembly system, wherein a terminal plate is incorporated in an insulator plate to insulate the terminal plate against an end plate.

[0008] For wide acceptance of fuel cells, there exists a need in the art for cost reduction in manufacturing such a fuel cell unit.

SUMMARY OF THE INVENTION

[0009] The present disclosure overcomes one or more shortcomings of the prior art and provides additional advantages. Embodiments and aspects of the disclosure described in detail herein are considered a part of the claimed disclosure. In particular the present disclosure provides possibility for cost reduction in manufacturing a fuel cell unit by reducing the number of necessary parts.

[0010] In one non-limiting embodiment of the present disclosure, a fuel cell unit is described. The fuel cell unit comprises a fuel cell block with at least one fuel cell for generating an electric power from hydrogen and oxygen, with the fuel cell block comprising at least one oxygen inlet and one hydrogen inlet. The fuel cell unit also comprises at least one end plate mounted on an end face of the fuel cell block to seal the end face. The fuel cell further comprises a power conduction means configured for conducting the electric power from the at least one fuel cell to a connection tab of the fuel cell unit, and an insulating means to insulate the fuel cell block against a surrounding area. The end face, on which the at least one end plate is mounted, may be left open to provide access to the at least one fuel cell. Therefore, to avoid fluctuation of fuel through the open end face of the fuel cell block, it is sealed by the at least one end plate. If there are more than one open end face of the fuel cell block, there may be a respective end plate for each of the open end faces.

[0011] According to the invention the end plate is made of an electrically conductive material to provide a functionality of the end plate and the power conduction means in one part, and the insulating means is provided by an electrically insulating coating of the end plate on an outer face of the end plate, wherein the outer face is averted to the fuel cell block. In other words - in contrast to the state of art - the insulating means is arranged on the outside of the fuel cell unit or on the outer face of the end plate, respectively.

[0012] In other words a power conduction means is provided by the end plate. The end plate therefore provides the functionality of conducting the electric power from the least one fuel cell to the connection tab of the fuel cell unit as well as the functionality of sealing the end face. In other words the end plate and the power conduction may be formed in one piece. This means that both the end plate and the power conduction are provided by a single part. According to a further development the connection tab has the same thickness as the end plate. This may lead to a better stability of the connection tab and the connection tab being able to withstand forces coming from an external bus connector cable connecting the fuel cell unit via the connection tab. More particularly the connection tab may be formed in one piece with the end plate. In other words the end plate may also form the connection tab, for example by comprising at least one bulge providing the connection tab. The end plate may have a rectangular shape, wherein the connection tab is mounted on the end plate on a shorter edge of the rectangular shape. Alternatively the connection tab may be mounted on the longer edge of the rectangular shape. According to a further development both sides may comprise a respective connection tab each. This may improve the connectability of the fuel cell unit. In an embodiment, the present invention provides a sufficient cross sectional area (i.e. material thickness) for a power connection to be made, through the connection tab, on the shorter edge of the end plate such that excessive heat is not generated under conditions of high currents. [0013] To provide both stability and electrical conductivity the at least one end plate may be made of metal or a carbon fiber reinforced material. Preferably, the end plate is made of aluminum. The insulating means may be provided by overmolded plastic on the outer face of the end plate. In other words the insulating means may be formed by overmolding the outer face of the end plate with plastic.

[0014] Further advantages, features, and details of the invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and/or shown in the figures alone can be employed not only in the respectively indicated combination but also in any other combination or taken alone without leaving the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings show in:

[0016] Fig. 1 schematically an exploded view of an exemplary fuel cell unit comprising a fuel cell block, and end plate and an insulating means; and

[0017] Fig. 2 a partly sectioned perspective view of the assembled exemplary fuel cell unit.

[0018] In the figures same elements or elements having the same function are indicated by the same reference signs.

DETAILED DESCRIPTION

[0019] In the present document, the word “exemplary” is used herein to mean “serving as an example, instance, or illustration”. Any embodiment or implementation of the present subject-matter described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0020] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

[0021] The terms “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, system or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system or method. In other words, one or more elements in a system or apparatus preceded by “comprises” or “comprise” does not or do not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.

[0022] In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

[0023] The present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.

[0024] Fig. 1 and 2 each show a fuel cell unit 1 in different representations. Therefore the following description refers to both figures. The fuel cell unit 1 comprises a fuel cell block 2, which houses at least one fuel cell. The fuel cell block 2 may therefore comprise the housing and the at least one fuel cell. The at least one fuel cell is configured to generate electric power from a fuel and oxygen. The fuel may in particular be hydrogen, natural gas or methanol. For supply of both, fuel and oxygen, the fuel cell block 2 comprises at least one oxygen inlet and one hydrogen inlet. The at least one fuel cell may comprise an anode, a cathode, and a membrane. For the sake of brevity the at least one fuel cell is not depicted and not further described, as this is not directly relevant to the present disclosure. [0025] On a bottom side of the fuel cell block 2 lies an open face of the fuel cell block 2. The open face may for example provide access to the at least one fuel cell within the housing of the fuel cell block 2. This open face is to be sealed or closed by an end plate 4. The end plate may also provide stiffness to the fuel cell block 2. In other words the end plate 4 may form a structural backbone for the fuel cell block 2. The end plate 4 may be mounted on the open face of the fuel cell block 2 for example by means of screws, clips or any other fastening means. The end plate 4 may comprise a gasket to ensure a tightness of a connection area between end plate 4 and fuel cell block 2. This may be important to tighten the fuel cell block 2 against a loss of oxygen or a fuel, in particular hydrogen.

[0026] The end plate 4 may be made of metal or another electrically conducting material, for example a carbon fiber composite. Preferably the end plate 4 may made of aluminum. The end plate 4 also forms a power conduction means for conducting electric power from the at least one fuel cell to a connection tab 6 of the fuel cell unit. In other words the end plate 4 is not only used as seal for the open face and reinforcement means, but also as a conductor for the electrical power of the at least one fuel cell. In other words one part is providing the functionality of conducting the electric power as well as sealing and reinforcing the fuel cell block 2 on its open side. Thus the end plate 4 provides the functionality of the end plate 4 and a power conduction means or in other words a bus bar in one piece.

[0027] The end plate 4 may form an electrode, for example the anode or the cathode, of the at least one fuel cell. In other words the anode and/or the cathode may be provided by the end plate 4. Both electrodes, namely the anode and the cathode, may be provided by a respective end plate 4 each. In this case the fuel cell unit 1 may comprise two end plates 4. The two end plates 4 may be arranged on respective open faces of the fuel cell block 2, which are located opposite to each other.

[0028] Alternatively, on the open face or near the open face electrodes or sub connection means of the at least one fuel cell may be located. Therefore, the end plate 4 may be placed adjacent to the electrodes and/or the sub connection means. Especially an inner face 7 which is oriented towards the fuel cell block 2 may be placed adjacent to and/or be oriented towards the electrodes and/or sub connection means. Therefore, the end plate 4 may connect the at least one fuel cell directly via its electrode or indirectly via the sub connection means. The sub connection means may be formed to provide an electrically conductive connection between the at least one fuel cell or each of the fuel cells in the case of more than one fuel cell and the end plate 4. Therefore, the end plate 4 is providing a functionality of a power conduction means or in other words a bus bar. This idea eliminates the need for a separate bus plate component. The metal backbone would act as the bus bar.

[0029] To insulate the fuel cell block 2 and the end plate 4 against a surrounding area, the fuel cell unit comprises an insulating means 5. In other words, the insulating means 5 is configured to insulate an outer surface of both the fuel cell block 2 and the end plate 4 against the surrounding area. This is necessary to reduce unwanted current floating from the fuel cell block and to prevent short-circuits between two poles of the fuel cell block 2. One of the two poles of the fuel cell block 2 may be provided by the connection tabs 6, while the other, usually on the other side of the fuel cell unit 1 is not depicted in the figures. The insulating means 5 is mounted on an outer face 8 of the end plate 4. Therefore, the insulating means 5 is configured to insulate the outer face 8 of the end plate 4 against the surrounding area. The insulating means 5 is configured to partly insulate the connection tab 6. Therefore, the connection tab 6 is partly coated by the insulating means. The connection tab 6 can also be referred to as bus tab, as it may connect the fuel cell block 2 to a bus connector cable. The bus connector cable can be configured to connect a plurality of fuel cell blocks 2 with each other and/or with a power consumer.

[0030] The insulating means 5 and the end plate 4 may together form an insulated end plate part 3. The insulated end plate part 3 may be formed in one piece. For example, the end plate 4 and the insulating means 5 may be connected to each other irreversibly. In other words the end plate 4 and the insulating means 5 may not be detachable from each other. For example, the insulating means 5 is provided by overmolded plastic on the outer face 8 of the end plate 4. In other words the end plate 4 may be coated with the insulating means 5 by means of overmolding the end plate 4 with plastic or a plastic coating respectively.

[0031] The end plate 4 and the connection tab 6 in the present case may also be formed in one piece. In other words the end plate 4 comprises a bulge which forms the respective connection tab 6. In the present case the end plate 4 comprises two bulges to provide a respective connection tab 6 each. Therein, the respective connection tab 6 may have the same thickness as the end plate 4. The respective connection tab 6 and the end plate 4 is also formed in one piece. Both leads to a better stability of the connection tab 6. So another advantage of the present invention is the fact that respective connection tab 6 is relatively thick and strong. A connection tab 6 formed like this can withstand forces coming from a bus connector cable connecting the connection tab 6 by itself. Therefore a further reinforcement means for reinforcing the connection tab 6 or the bus connector cable may be omitted.

[0032] The connection tab 6 may be located on one of two shorter edges 10 of the fuel cell block 2. Consequently, another advantage of the exemplary embodiment consists in the fact that generally it is hard and/or space-consuming to have the connection tab 6 or bus tab (interface with power cables) coming from the short edges 10 of the fuel cell block 2 and therefore on the same side where gases, namely oxygen and the above-mentioned fuel, are fed into the fuel cell block 2. This makes it necessary for the connection tab 6 to bypass the oxygen inlet and/or the hydrogen or fuel inlet. However, in the present embodiment this is not a problem as there is enough material thickness of the end plate 4 to allow current to pass between the inlets.

Reference signs

1 fuel cell unit

2 fuel cell block

3 insulated end plate part

4 end plate

5 insulating means

6 connection tab

7 inner face

8 outer face

10 shorter edge

Claims

CLAIMS A fuel cell unit, comprising

- a fuel cell block with at least one fuel cell for generating electric power from hydrogen and oxygen,

- at least one end plate mounted on an end face of the fuel cell block to seal the end face,

- a power conduction means configured for conducting the electric power from the at least one fuel cell to a connection tab of the fuel cell unit, and

- an insulating means to insulate the fuel cell block against a surrounding area, characterized in that

- the end plate is made of an electrically conductive material to provide a functionality of the end plate and the power conduction means in one part, and

- the insulating means is provided by an electrically insulating coating of the end plate on an outer face of the end plate, wherein the outer face is averted to the fuel cell block. The fuel cell unit according to claim 1 , characterized in that the insulating means is provided by overmolded plastic on the outer face of the end plate. The fuel cell unit according to claim 1 or 2, characterized in that the end plate is made of metal, in particular aluminum. The fuel cell unit according to any one of claims 1 to 3, characterized in that the power conduction means and the end plate are formed in one piece. The fuel cell unit according to any one of claims 1 to 4, characterized in that the connection tab has the same thickness as the end plate. The fuel cell unit according to any one of claims 1 to 5, characterized in that the end plate and the at least one connection tab are formed in one piece The fuel cell unit according to claim 6, characterized in that the connection tab is provided by a bulge of the end plate. The fuel cell unit according to any one of claims 1 to 7, characterized in that the end plate has a rectangular shape, wherein the at least one connection tab is mounted on the end plate on one of its shorter edges. The fuel cell unit according to claim 8, characterized in that the end plate comprises two connection tabs, wherein the first connection tab is mounted on the end plate on one of its shorter edges, and the second connection tab is mounted on one of its longer edges.