Methods for manufacturing an electrochemical cell and electrochemical cell

Abstract

A method for manufacturing an electrochemical cell, in particular an electrolysis cell or a fuel cell, comprising several superimposed layers and / or layers, is proposed, comprising a membrane (1), characterized by the following steps a) at least partial application of at least one sensor material (3) to a surface (2) of the membrane (1) and / or a subgasket surrounding the membrane (1), b) Stacking the layers and / or layers and c) Joining the individual layers and / or layers, preferably by pressing or screwing. Furthermore, the invention relates to a control unit that is configured to carry out a method or individual steps of a method.

Description

[0001] The present invention relates to a method for manufacturing an electrochemical cell. Furthermore, the invention relates to an electrochemical cell that has been manufactured, in particular, according to a method according to the invention.

[0002] Preferred areas of application for the invention are electrolysis systems or fuel cell systems. State of the art

[0003] Electrochemical cells, particularly fuel cells and electrolysis cells, have a layered structure with a cathode-side and an anode-side electrode, and a membrane between them that electrically separates them. In the case of an electrolysis cell, water is split into hydrogen and oxygen under the influence of electrical energy. In the case of a fuel cell, hydrogen and oxygen are converted into electrical energy, heat, and water.

[0004] The electrodes of an electrochemical cell often consist of an electrically conductive base material, which is functionalized by a coating with a catalytic material, such as a precious metal-containing ink. The catalytic material can also be applied directly to the membrane, forming a catalyst layer on one or both sides. In addition, gas diffusion layers, porous transport layers, bipolar plates, and / or separator plates may be present as further layers.

[0005] The described layers and / or components are stacked in a single assembly step and joined under pressure by compression and / or screwing to form an electrochemical cell. Several electrochemical cells can then be connected to form a stack to increase performance. For this reason, the electrochemical cells must exhibit consistently high quality, as even a single defective cell can lead to a leak or short circuit, thus shutting down the entire stack.

[0006] Typically, selected prototypes of the electrochemical cells are assembled and measured to determine advantageous assembly parameters, such as contact pressures. Similarly, the operating conditions in prototypes are measured, and an efficient operating point is identified. The data painstakingly obtained from these prototypes are extrapolated for the assembly and operation of a large number of electrochemical cells. However, since slight differences can occur in practice between theoretically identical electrochemical cells due to production variations, defects and efficiency losses can still occur despite these optimization processes.

[0007] The present invention aims to simplify the production of electrochemical cells and to minimize defects and efficiency losses. Furthermore, it seeks to improve the operation of the electrochemical cells.

[0008] To solve the problem, a method for manufacturing an electrochemical cell with the features of claim 1 is proposed. Furthermore, an electrochemical cell is proposed. Advantageous embodiments of the invention are described in the respective dependent claims. Disclosure of the invention

[0009] A method for manufacturing an electrochemical cell, in particular an electrolysis cell or a fuel cell, comprising several superimposed layers and / or layers, including a membrane, is proposed. According to the invention, the method comprises the following steps: a) at least partial application of at least one sensor material to a surface of the membrane and / or a subgasket surrounding the membrane, b) Stacking the layers and / or layers and c) Joining the individual layers and / or layers, preferably by pressing or screwing.

[0010] Applying sensor material to the surface of the membrane and / or the subgasket enables the determination of at least one assembly parameter, such as the contact pressure. The measured parameter is specific to the respective electrochemical cell and is not extrapolated from other electrochemical cells, thus ensuring high accuracy. In particular, this parameter can be determined in-situ, i.e., during the assembly of the individual layers and / or strata, and applied directly. This allows positioning errors and / or pressure differences during the joining or pressing of the layers and / or strata to be identified. This simplifies the assembly of the layers and / or strata, thereby preventing defects.

[0011] Since the sensor material remains within the electrochemical cell, it can also be used to optimize the cell's operation, for example, to increase efficiency. In conventional electrochemical cells, measurements within the cell, and especially between individual layers, are not possible during operation. Instead, the electrochemical cell is controlled based on empirical correlations or indirect values. The latter are determined outside the cell, for example, using exhaust gas values ​​or electrical parameters. In an electrochemical cell according to the invention, the current operating state can be determined by utilizing the sensor material present within the cell, thus enabling faster detection and correction of faults. In this way, the efficiency of the electrochemical cell can also be increased simultaneously.

[0012] The efficiency of an electrochemical cell depends in particular on the membrane temperature, which cannot be directly measured in conventional electrochemical cells. In an electrochemical cell according to the invention, the membrane temperature can be determined and adjusted using the sensor material, thus achieving high efficiency. The sensor material also enables pressure and / or temperature analyses, which allow conclusions to be drawn about the operating and / or aging condition of the electrochemical cell.

[0013] The sensor material can be applied to one or both sides of the membrane. In the latter case, the membrane is turned over and step a) is repeated before step b). If necessary, the sensors can also be applied to both sides in a single step. This allows for a further increase in the accuracy of the measured values ​​of the sensor material and thus better positioning of the layers and / or plies during assembly.

[0014] In addition to the pressure and / or temperature measurement functions already described, the sensor material applied to the surface of the membrane and / or subgasket has further functions. For example, the sensor material can be used to measure humidity for leak detection. It can also detect excessive dryness. If the sensor material functions as a pH sensor, the electrochemical reaction within the cell can be monitored and controlled.

[0015] When using multiple, and especially different, sensor materials, it is preferable to apply them sequentially and / or in different surface areas. With multiple, and especially different, sensor materials, they can be used to determine several parameters, for example, pressure with one sensor material and temperature with a second. This allows for a better and more accurate determination of the assembly and operating status, enabling more efficient detection and prevention of defects. Additionally, the operation of the electrochemical cell can be better controlled by using multiple sensor materials.

[0016] Spatially separating the multiple sensor materials into different surface areas prevents their overlapping, thus avoiding measurement errors and / or defects. Furthermore, applying the sensor materials to defined surface areas allows for precise positioning. This is crucial for accurate evaluation of the measured values. In particular, an alternating arrangement of the different sensor materials distributed across the membrane surface enables a comprehensive analysis of the electrochemical cell during assembly or operation. Moreover, the large number of measurement positions allows even the smallest parameter fluctuations to be detected locally.

[0017] Applying multiple sensor materials sequentially allows each material to bond to the membrane surface and partially cure before the next material is applied. This increases dimensional stability and reduces the occurrence of defects.

[0018] Preferably, the at least one sensor material is applied using a printing process, for example, screen printing, inkjet printing, digital printing, and / or offset engraving. Applying the at least one sensor material using a printing process offers high application accuracy. This allows the at least one sensor material to be applied to the membrane with precise positioning, preventing the mixing of sensor materials in different surface areas and thus avoiding electrical contact and measurement inaccuracies. Precise positioning is particularly important when multiple sensor materials are densely arranged on the surface of the membrane and / or the subgasket. All of the described printing processes are characterized by exceptionally high application accuracy.

[0019] Furthermore, all the described printing processes exhibit a high deposition rate. Since a large number of electrochemical cells or membranes are required in practice to increase the system's performance, a process with a high deposition rate leads to faster membrane production. This increases the economic efficiency of the manufacturing process.

[0020] Preferably, the at least one sensor material is applied in a line. Applying it in a line is particularly easy to implement. Preferably, at least one pattern is formed when applying the at least one sensor material in a line. This pattern allows the at least one sensor material to be applied to a larger surface area. The pattern is preferably wave-shaped, zigzag-shaped, and / or meandering. This allows large surface areas to be covered. This, in turn, ensures accurate measurements distributed across the surface of the membrane and / or the subgasket.

[0021] In an advantageous embodiment of the invention, a chip and / or an electrical contact element are integrated during the application of the at least one sensor material. These are necessary to read the sensor data acquired by the at least one sensor material and make it available for evaluation. A chip and / or an electrical contact element can be easily integrated into the at least one sensor material during its application, eliminating the need for an additional process step. Suitable components include, for example, an active or passive RFID transponder, an NFC chip, or a cable connection connected individually or in series. Both the RFID transponder and the NFC chip enable contactless data transmission. However, the RFID transponder has a greater range, whereas the NFC chip enables two-way communication.A cable connection wired individually has the advantage of being less susceptible to damage and faults. Furthermore, higher data transmission speeds can be achieved. A cable connection wired in series reduces manufacturing costs and material requirements, as the sensors are connected in series, thus requiring only one central cable connection.

[0022] Preferably, in step b), data read from the at least one sensor material are used to position and / or align the layers and / or layers. This allows the multiple layers and / or layers to be positioned and aligned more precisely during stacking. If individual layers and / or layers shift, this can be detected and corrected.

[0023] Furthermore, in step c), the pressing of the multiple layers and / or plies can be simplified by reading the data from at least one sensor material, provided it functions as a pressure sensor. This allows the contact pressure to be monitored and, if necessary, corrected based on the sensor data.

[0024] The sensor data from the at least one sensor material of an electrochemical cell according to the invention can be transferred to other structurally identical cells, so that the electrochemical cell according to the invention functions as a kind of "dummy cell". Furthermore, in the "dummy cell", the at least one sensor material can be arranged distributed over the entire surface of the membrane and / or the subgasket, so that it can be measured almost completely.

[0025] To produce a fully functional cell, it is proposed that, prior to step a), a catalytic material be applied to a central surface region of the membrane, and in step a), the at least one sensor material be applied outside this surface region. The catalytic material serves to create an electrode on the membrane where the electrochemical reactions can take place. The application of the catalytic material can be performed in the same process step as the application of the sensor material. This simplifies and accelerates the production of the electrochemical cell. Applying the sensor material to a different surface region than the surface region of the catalytic material ensures the functionality of the electrode and prevents a reduction in the active surface area of ​​the electrode or any defects in the electrode.

[0026] In a further development of the invention, it is proposed that a drying process be carried out after the application of the catalytic material and / or the sensor material. For efficient application to the membrane, the catalytic material and / or the sensor material exhibits high deformability. This is undesirable in the subsequent processes, as even slight forces can lead to deformation and thus to impairment of the catalytic material and / or the sensor material. Drying accelerates the curing and increases the dimensional stability, making the catalytic material and / or the sensor material less susceptible to deformation and thus defects.

[0027] Preferably, the drying process is carried out using heat or radiation. Due to the small amount of material, the catalytic material and / or the sensor material can be easily heated and dried quickly. Furthermore, drying processes using heat are particularly efficient. Drying by radiation can be achieved through the application of ultraviolet (UV) and / or infrared (IR) radiation. In the case of ultraviolet radiation, the radiation curing effect is used to harden the sensor material. This process involves minimal heat input, allowing even temperature-sensitive sensor materials to be used. The use of infrared radiation is characterized by a combined curing process involving both heat and radiation, enabling particularly fast and energy-efficient curing of the sensor material.

[0028] Furthermore, an electrochemical cell, in particular an electrolysis cell or fuel cell, is proposed, comprising several superimposed layers and / or layers, including a membrane. According to the invention, at least one sensor material for forming a sensor, for example a pressure and / or temperature sensor, is applied at least partially to a surface of the membrane and / or a subgasket surrounding the membrane.

[0029] The proposed electrochemical cell is preferably manufactured according to the previously described method, thus also achieving the advantages of that method. Furthermore, the data from the at least one sensor can be used both during the manufacture and operation of the electrochemical cell.

[0030] Preferably, the at least one sensor material has a layer thickness of < 100 µm. Since the application of the sensor material leads to local protrusions on the membrane and / or the subgasket, the layer thickness should be chosen to be as small as possible. A sensor material with a layer thickness of < 100 µm ensures that the layers and / or layers are in electrical contact when stacked, thus guaranteeing the functionality of the electrochemical cell. Preferably, the at least one sensor material has a layer thickness of < 50 µm. Sensor materials of this thickness further improve the contact of the adjacent layers and / or layers and minimize the influence of the applied sensor material on the operation and function of the electrochemical cell.

[0031] Preferably, a chip and / or an electrical contact element is integrated into the sensor material. The chip and / or the electrical contact element serve to read and transmit the data acquired using the at least one sensor material. Integration into the sensor material ensures good contact and low susceptibility to errors. In particular, the chips, transponders, and electrical contact elements previously described in connection with the method can be used.

[0032] The electrochemical cell can be a "dummy cell" or a fully functional electrochemical cell. In the latter, a catalytic material is preferably applied to a central surface region of the membrane, while the at least one sensor material is applied outside this surface region. The electrochemical reactions can take place on the catalytic material. Applying the sensor material to a different surface region than the catalytic material prevents an overlap of the two materials, thus preserving their functionalities. Furthermore, a reduction in the active surface area of ​​the catalytic material, and therefore efficiency losses, are avoided.

[0033] The invention and its advantages are explained in more detail below with reference to the accompanying figures. These show Fig. 1 a schematic top view of a membrane of an electrochemical cell according to the invention in a first preferred embodiment, Fig. 2 a schematic top view of a membrane of an electrochemical cell according to the invention in a second preferred embodiment and Fig. 3 a schematic representation of a system for the production of an electrochemical cell according to a method according to the invention. Detailed description of the drawings

[0034] Fig. Figure 1 shows a membrane 1 of an electrochemical cell, which forms a "dummy cell". Two different sensor materials 3, 3' are applied to a surface 2 of the membrane 1 in different surface areas 4, 4'. These sensor materials 3, 3' form sensors for detecting various parameters, such as pressure and temperature. The surface areas 4, 4' and thus the sensor materials 3, 3' alternate. The sensor materials 3, 3' are applied as lines in a zigzag pattern 9 to the surface 2 of the membrane 1. There is no contact between individual zigzag lines, either within a surface area 4, 4' or between surface areas 4, 4'. The distribution of the sensor materials 3, 3' across the surface of the membrane 1 results in a large number of measurement positions. These enable locally resolved measurements of the respective parameter at the surface 2 of the membrane 1.Contacting the sensor materials 3, 3' with a chip and / or an electrical contact element is not shown, but is typically done to read and transmit the acquired data.

[0035] Fig. Figure 2 shows a membrane 1 of an electrochemical cell, forming a fully functional electrochemical cell. This cell has various sensor materials 3, 3' on its surface 2 in surface regions 4, 4' to form sensors. The surface regions 4, 4' are arranged around an active area of ​​the membrane 1, which is coated with a catalytic material 5. During cell operation, the electrochemical reaction takes place at the coated active area of ​​the membrane 1. This reaction can be monitored and / or controlled using the sensors.

[0036] Fig. Figure 3 schematically shows a system 6 for the production of an electrochemical cell according to a method according to the invention. A membrane 1, designed as a strip, is moved through the system 6 via a roller system. A catalytic material 5 is applied to a surface 2 of the membrane 1 by a first printing unit 7. The printing unit 7 can apply the catalytic material 5 by various possible printing methods, for example, screen printing, inkjet printing, digital printing, and / or offset engraving.

[0037] In a first drying unit 8 and a subsequent second drying unit 8, the applied catalytic material 5 is at least partially dried. Drying can be carried out under the influence of heat. A first sensor material 3 is applied to the surface 2 of the membrane 1 in at least one defined surface area 4 by a second pressure unit 7. The application takes place outside the surface 2 of the membrane 1 already coated with the catalytic material 5. Subsequently, the first sensor material 3 is at least partially dried by a further drying unit 8. In a further process step, a second sensor material 3' is applied to the surface 2 of the membrane 1 in at least one further surface area 4' by a third pressure unit 7.The at least one further surface area 4' of the second sensor material 3' lies both outside the surface 2 coated with the catalytic material 5 and outside the surface area 4 coated with the first sensor material 3. The second sensor material 3' is dried in a final drying unit 8. Finally, the membrane 1, which is supplied as a strip, is wound up and / or divided into individual membranes 1 for further processing.

[0038] To produce a "dummy cell" as exemplified in the Fig.As shown in Figure 1, the application of the catalytic material 5 can be omitted. In this case, the central surface area 4 is also coated with at least one sensor material 3, 3'. If the membrane 1 is to be coated on both sides, the membrane 1 is turned over and the described process steps are repeated. If necessary, the membrane 1 can also be coated on both sides with a sensor material 3, 3' in one step.

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