Patent Application
20230231158
The invention relates to a method for producing a fuel cell comprising a membrane electrode assembly which is at least partly enclosed by a sub-gasket. The invention also relates to a fuel cell which has in particular been produced according to the method according to the invention.
Fuel cells are used in both mobile and stationary applications. With their help, the chemical reaction energy of a continuously supplied fuel and an oxidizing agent can be converted into electrical energy. To increase performance, multiple fuel cells can be disposed on top of one another to form a fuel cell stack, also referred to as a “stack.”
The “heart” of a fuel cell is the so-called membrane electrode assembly (MEA), which comprises a membrane that is coated on both sides to form a first and a second catalytically active electrode. The first electrode forms the anode and the second electrode forms the cathode. The membrane in between serves as the electrolyte. During operation of the fuel cell or the fuel cell stack, the anode is supplied with a fuel, for example hydrogen. Air is supplied to the cathode as the oxidizing agent.
The MEA is typically laminated in between two thin plastic films, which together are referred to as the “sub-gasket.” They serve as electrical insulation between the anode and the cathode. Both films comprise large windows, so that the active regions of the MEA remain uncovered. The MEA is therefore enclosed by the plastic films adjoining on either side only in a peripheral edge region. The large windows and other openings are created in the plastic films in advance, specifically in each film individually, for example by means of punching. After that, the delicate structures are coated with a glue, positioned on either side of the MEA, so that the openings of the two plastic films lie exactly on top of one another, and then glued to one another. This process is tedious and time consuming, because the work has to be very precise.
The underlying object of the present invention is therefore to simplify the production of a fuel cell. The intent is in particular to achieve a higher degree of automation in the production of fuel cells, in order to make mass production more economical.
Proposed is a method for producing a fuel cell comprising a membrane electrode assembly, which is at least partly enclosed by a sub-gasket. According to the invention, to form the sub-gasket, the membrane electrode assembly is inserted at least partly into a film sleeve, the film sleeve is pressed together so that at least some regions of the two film sleeve halves lie on top of one another and the film sleeve halves lying on top of one another are connected, preferably glued, to one another.
The proposed use of a film sleeve instead of two individual films makes it possible to simplify the formation of the sub-gasket significantly. This is because the difficult handling of two delicate individual films is eliminated. There is also no longer a need for exact alignment of the films to one another. As a result, the formation of the sub-gasket can be carried out in a very short time and also in a highly automated manner, which then enables economical mass production.
Preferably, at least one window-like opening is created in the film sleeve prior to insertion of the membrane electrode assembly in the film sleeve. The purpose of the window-like opening is to leave at least one active region of the membrane electrode assembly uncovered. Since the membrane electrode assembly forms active regions on either side, i.e., on both the anode and the cathode side, the window-like opening can be selected to be correspondingly large and the membrane electrode assembly can be inserted into the film sleeve in such a way that both active regions come to lie within this one window-like opening. In this case, the opening extends from the anode side to the cathode side of the membrane electrode assembly. Alternatively, two window-like openings can be created in the film sleeve instead of one window-like opening. The two window-like openings are preferably disposed opposite to one another. After the membrane electrode assembly is inserted and the film sleeve is pressed together, the two window-like openings therefore lie exactly on top of one another. This ensures that each one of the two active regions of the membrane electrode assembly comes to rest inside the window-like opening assigned to it.
When the membrane electrode assembly is inserted into the film sleeve, it is therefore important to ensure that the active regions configured on both sides of the membrane electrode assembly are positioned within the at least one window-like opening.
It is also possible to use two or more film sleeves instead of a single film sleeve. When two film sleeves are used, one end of the membrane electrode assembly is preferably inserted into a first film sleeve and the other end is inserted into a second film sleeve. The two film sleeves are then respectively pressed together and the respective film sleeve halves of a film sleeve lying on top of one another are connected, preferably glued, to one another. If two film sleeves are used, the formation of the at least one window-like opening in the film sleeve can be omitted. This is because, instead of the opening, the two film sleeves are simply disposed at a sufficient distance from one another for the active regions of the membrane electrode assembly to remain uncovered. The method can thus be simplified further.
When two film sleeves are used, a two-piece sub-gasket is formed. A first part surrounds a first end portion of the membrane electrode assembly, a second part surrounds a second end portion of the membrane electrode assembly. The active regions of the membrane electrode assembly respectively extend between the two end portions. In this case, the active regions are enclosed on only two sides by the two parts of the sub-gasket.
However, it is also possible to use four film sleeves to form the sub-gasket instead of two film sleeves. In this case, the two additional film sleeves are disposed offset 90° from the two first film sleeves, so that the membrane electrode assembly is enclosed all the way around and the active regions are left uncovered.
If only one film sleeve is used, in order to leave the active regions of the membrane electrode assembly uncovered, it is preferable to use a film sleeve comprising at least two window-like openings. The membrane electrode assembly is thus enclosed all the way around, while the active regions on both sides of the membrane electrode assembly remain uncovered. Enclosing the membrane electrode assembly all the way around, also creates an all-around reinforcement of the edge.
The membrane electrode assembly is preferably inserted fully into the film sleeve, so that a respective film sleeve end extends beyond the membrane electrode assembly on either side. Then when the film sleeve is pressed together, two respective film sleeve halves lie on top of one another in the region of the projecting film sleeve ends and can easily be connected, preferably glued, to one another.
In order to achieve bonding of two film sleeve halves lying on top of one another as soon as the film sleeve is pressed together, it is proposed that the inside of the film sleeve be coated with a glue prior to insertion of the membrane electrode assembly in the film sleeve. The method steps pressing together and connecting or gluing can thus be carried out in one work step, which saves even more time.
After the method steps:
By creating the at least one supply opening in the film sleeve halves lying on top of one another later, it is not necessary to ensure that the supply openings lie exactly on top of one another when the membrane electrode assembly is inserted into the film sleeve and/or when the film sleeve is subsequently pressed together, because there are no supply openings yet.
The at least one window-like opening and/or the at least one supply opening is/are advantageously created in a punching process. Punching allows openings to be produced easily and cost-efficiently. Templates can furthermore be produced, which simplify mass production.
Also proposed is a fuel cell comprising a membrane electrode assembly, which is at least partly enclosed by a sub-gasket. According to the invention, the sub-gasket is made of at least one film sleeve. This means that the sub-gasket forms a fold along each of two side edges, which preferably extend substantially parallel. This is because there are not two individual foils lying on top of one another, but two film sleeve halves.
The proposed fuel cell can therefore in particular be produced according to the above-described method according to the invention. This means that the proposed fuel cell can be produced comparatively easily and cost-efficiently. It is in particular possible to achieve a high degree of automation in the production of the fuel cell, so that it is suitable for mass production.
In a further development of the invention, it is proposed that the film sleeve comprise two film sleeve halves, at least some regions of which lie on top of one another and which are connected, preferably glued, to one another. Connecting or gluing the film sleeve halves fixes said halves both to one another and with respect to the membrane electrode assembly.
The invention will be explained in more detail in the following with reference to the accompanying drawings. The figures show:
The highly simplified illustration of
In contrast to the use of two individual foils 7 known in the prior art (see
It is also possible to use two film sleeves 3 instead of a single film sleeve 3. One respective end portion of the membrane electrode assembly 1 is then inserted into one film sleeve 3. This embodiment is shown as an example in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 207 601.4 | Jun 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/065877 | 6/14/2021 | WO |
