Membrane electrode assembly
By integrating the voltage monitoring interface element into the membrane electrode assembly and using sub-wafer support, the problems of cumbersome and unreliable installation of the voltage monitoring interface in fuel cell stacks are solved, achieving simplified installation and comprehensive voltage monitoring.
Patent Information
- Application Number
- CN202480039275.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-07-05
- Filing Date
- 2024-07-05
- Publication Date
- 2026-01-09
Smart Images
Figure CN121311979A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a membrane electrode assembly as described in the preamble of claim 1. The invention also relates to fuel cell stacks including such a membrane electrode assembly. Background Technology
[0002] Typically, a fuel cell stack comprises multiple stacked plates separated from each other by an insulating layer. In the special case of a fuel cell stack, the plates are bipolar plates, and the insulating layer is a multilayer membrane electrode assembly (MEA). A bipolar plate itself is a combination of anode and cathode plates fixed to each other, with adjacent bipolar plates then separated by the MEA, or in other words, clamped. The cathode and anode plates forming the bipolar plates are typically conductive metal or graphite plates, known as flow field plates, which have a flow field for the reactants on one side and a flow field for the cooling fluid on the other. In the assembled state of the bipolar plates, the flow field plates are stacked such that the cooling fluid flow fields face each other and the reactant flow fields face the clamped MEA assembly.
[0003] The current is generated in the electron-generating assembly by the membrane electrode assembly (MEA) during fuel cell stack operation. The electron-generating assembly of the MEA includes an ion-conducting membrane and two electrocatalyst layers arranged on both sides of the membrane as the anode and cathode. During fuel cell stack operation, fuel (specifically hydrogen) is supplied at the anode, while the oxidant (typically oxygen or air) is supplied at the cathode.
[0004] At the anode, an electrocatalyst (typically a platinum catalyst) causes hydrogen to split into positively charged hydrogen ions (protons) and negatively charged electrons. An ion-conducting membrane (such as a polymer electrolyte membrane (PEM)) allows only positively charged ions to pass through to the cathode. At the cathode, the electrons and positively charged hydrogen ions combine with oxygen to form water, which flows out of the battery.
[0005] Since the ion-conducting membrane only allows positively charged ions to pass through to the cathode, a voltage potential difference is generated across the membrane electrode assembly, and thus a voltage potential difference is generated between the bipolar plate assemblies.
[0006] During battery stack operation, it is necessary to monitor the voltage generated by the stacked cells to determine whether the battery stack is operating within its expected operating parameters. For this purpose, it is known that bipolar plates are equipped with voltage monitoring units, which are fixed to the bipolar plates and have wires for connecting the voltage monitoring units to an external voltage monitoring controller, which monitors and controls the operation of the battery stack.
[0007] Therefore, it is known, for example, to attach wires directly to bipolar plates by soldering. It is also known to use pin connections, where pins are inserted between the plates of the bipolar plate, and the pins are secured between the plates by friction or press-fit.
[0008] However, placing and securing wires and pins to the fuel cell stack is cumbersome and time-consuming, making the stacking process inefficient and slow. Furthermore, known securing methods are prone to failure, as wires and pins may detach from the board or become misaligned, leading to malfunctions within the stack.
[0009] Furthermore, because bipolar plates and associated membrane electrode assemblies are typically stacked tightly, fuel cell stacks lack the space to install voltage monitoring interface elements, which may be easier to install.
[0010] It is also known to arrange and fix electrical conductors on a foil, which can be positioned between a gas diffusion layer and adjacent electrodes of a membrane electrode assembly, such that the electrical conductors are in electrical contact with the corresponding electrodes. The electrical conductors extend on the membrane electrode assembly, allowing them to be connected to a voltage monitoring unit. Disadvantageously, the electrical conductors are susceptible to damage during fuel cell stack assembly and also hinder proper alignment of the membrane electrode assembly and bipolar plates during the stacking process. Summary of the Invention
[0011] Therefore, the purpose of this invention is to provide a solution for voltage monitoring of fuel cell stacks that is easy and reliable to install without easily damaging or hindering the alignment of components.
[0012] This objective is achieved by the membrane electrode assembly according to claim 1 and the fuel cell stack according to claim 13.
[0013] The following discloses a membrane electrode assembly for a fuel cell stack, comprising at least one power generation component, the power generation component including an ion-conducting membrane and two electrode catalyst layers disposed on opposite sides of the membrane as an anode and a cathode. Furthermore, the membrane electrode assembly includes at least one sub-wafer surrounding the power generation component, wherein the at least one sub-wafer has a first side facing the power generation component and a second side opposite to the first side and facing away from the power generation component.
[0014] It is further proposed to arrange the voltage monitoring interface element at the membrane electrode assembly itself, instead of at the bipolar plate as is known. The voltage monitoring interface element is adapted to contact the voltage supply component of the membrane electrode assembly or fuel cell stack. The voltage monitoring interface element is fully arranged on and supported by at least one side of the sub-gasket, wherein the corresponding side of the sub-gasket supporting the voltage monitoring interface element is at least partially exposed to the external environment to provide a connection area.
[0015] By integrating the voltage monitoring interface element into the membrane electrode assembly, the voltage monitoring interface element is already provided during the assembly of the fuel cell stack. This eliminates the need for cumbersome attachment of pins or wires to the bipolar plates.
[0016] Since the voltage monitoring interface element is fully supported by the sub-wafer of the membrane electrode assembly, the voltage monitoring interface element does not protrude from the membrane electrode assembly, allowing for normal alignment of fuel cell stack elements.
[0017] Furthermore, the voltage monitoring interface element is made robust enough to prevent any damage by being fully supported by the sub-wafer. However, the exposed connection area of the voltage monitoring interface element in the environment provides easy access to it.
[0018] The voltage monitoring interface element itself can be attached to the sub-wafer, for example, by gluing.
[0019] Alternatively, the voltage monitoring interface element can be attached to another voltage supply component of the fuel cell stack and supported only by a sub-wafer to provide sufficient robustness for the voltage monitoring interface element.
[0020] The voltage supply component can be part of the membrane electrode assembly itself, such as the electrode or optional gas diffusion layer, but it can also be provided by additional components of the fuel cell stack, particularly the bipolar plates. Even if the voltage monitoring interface element is adapted to contact the bipolar plates, the voltage monitoring interface element itself is still part of the membrane electrode assembly.
[0021] According to a preferred embodiment, the voltage monitoring interface element is disposed on the second side of the sub-gasket and is adapted to make direct or indirect contact with the bipolar plate, which clamps the membrane electrode assembly in the assembled state in the fuel cell stack. By disposing the voltage monitoring interface element "outside" the sub-gasket, the voltage monitoring interface element is easily accessible for connection to the voltage monitoring unit.
[0022] Depending on the alternative or additional arrangement, the membrane electrode assembly may further include a gas diffusion sub-assembly, comprising at least one anode-side gas diffusion layer preferably made of conductive fibers and a cathode-side gas diffusion layer preferably made of conductive fibers, wherein the gas diffusion layers at least hold the electron-generating component. Since the voltage generated by the membrane electrode assembly is transmitted to the adjacent bipolar plate via the gas diffusion layers, the voltage generated at the respective electrode can also be monitored at the gas diffusion layer itself. Therefore, it is preferable to arrange the voltage monitoring interface element on the second side of the sub-gasket, such that the voltage monitoring interface element is in contact with the corresponding gas diffusion layer.
[0023] According to a preferred embodiment, the voltage monitoring interface element is arranged on the first side of the sub-washer and in contact with the power generation assembly, particularly with the anode and / or cathode. This allows for direct voltage monitoring at the voltage generation component, thus enabling significant monitoring.
[0024] In order to expose at least a portion of the voltage monitoring interface element to the environment while still in contact with the power generation components, in a preferred embodiment, at least one sub-wafer has at least one opening, and the voltage monitoring interface element has a first portion, a second portion, and a third portion, the first portion being disposed on a first side of the sub-wafer, particularly between the anode and / or cathode of the membrane electrode assembly and the corresponding sub-wafer, the second portion extending through the opening in the sub-wafer, and the third portion being disposed on a second side of the sub-wafer.
[0025] If the membrane electrode assembly also includes a sub-wafer assembly having an anode-side sub-wafer surrounding the anode periphery and / or a cathode-side sub-wafer surrounding the cathode periphery, rather than just a single sub-wafer, the voltage monitoring interface element may be located at the anode-side sub-wafer or the cathode-side sub-wafer.
[0026] This also allows the voltage monitoring interface element to be positioned on the second side of the corresponding sub-wafer, particularly between the sub-wafer and the gas diffusion layer or bipolar plate. This simplifies access to connection areas exposed to the environment.
[0027] However, the voltage monitoring interface element can also be arranged on the first side of one of the sub-washers, and thus between the anode-side sub-washer and the cathode-side sub-washer. In this case, it is further preferred that one of the sub-washers (anode-side sub-washer or cathode-side sub-washer) is at least partially recessed relative to the corresponding other sub-washer, thereby exposing the voltage monitoring interface element to the environment.
[0028] It goes without saying that the recess does not necessarily need to extend to the entire periphery of the sub-waist; it can be set at only one or more discrete locations on the sub-waist.
[0029] In addition, it should be noted that the voltage monitoring interface element can be attached to the electrode or the corresponding sub-wafer, or both.
[0030] It should be further noted that, with the integration of voltage monitoring interface elements into the membrane electrode assembly itself and the provision of connection areas exposed to the environment, it is possible to arrange multiple voltage monitoring interface elements at a single membrane electrode assembly. Multiple voltage monitoring interface elements may be beneficial, at least during the initial startup of the fuel cell stack.
[0031] Therefore, it should be noted that different arrangements and positions of voltage monitoring elements can be provided at the same membrane electrode assembly or at different membrane electrode assemblies located in the same fuel cell stack.
[0032] According to a further preferred embodiment, the voltage monitoring interface element may have at least one protruding connecting element extending from the periphery of the membrane electrode assembly, wherein at least one of the sub-gaskets further includes at least one strip or flag protruding from the periphery of the membrane electrode assembly and supporting the protruding connecting element of the voltage monitoring interface element. The strip may be arranged in size and shape such that it can robustly support the protruding connecting element of the voltage monitoring interface element.
[0033] As described above, to provide accessibility of the voltage monitoring interface element to the external voltage monitoring controller, at least one of the sub-washers may have a connection area, wherein one of the sub-washers is recessed relative to the other sub-washer, and the voltage monitoring interface element is arranged between the sub-washers and is accessible in the connection area. Thus, the recess may also be arranged at the aforementioned strip.
[0034] According to a further preferred embodiment, the voltage monitoring interface element is designed as an elongated element that contacts at least one of the anode, cathode, membrane, sub-gasket, and / or gas diffusion layer along its length.
[0035] This allows for the collection of voltage information over an extended range of the membrane electrode assembly, making it possible to provide voltage information not only over a very limited area but also over the entire membrane electrode assembly, particularly along the entire length of the active region defined by the area covered by the electron-generating component.
[0036] According to a further preferred embodiment, the voltage monitoring interface element has an elongated body attached to at least one of the sub-gaskets, and further includes at least one discrete internal connection element extending from the elongated body along the direction of the anode, cathode, membrane and / or gas diffusion layer, and in contact with at least one of the anode, cathode, membrane and / or gas diffusion layer.
[0037] The elongated body has a further advantage: it can be connected to external connecting elements at different locations. This, in turn, allows for offset connection to external connecting elements, ensuring that the external connecting elements do not obstruct each other.
[0038] According to a further preferred embodiment, at least one first voltage monitoring interface element and at least one second voltage monitoring interface element are provided, wherein at least one first voltage monitoring interface element is arranged on the reactant or coolant inlet side of the membrane electrode assembly, and at least one second voltage monitoring interface element is arranged on the reactant or coolant outlet side of the membrane electrode assembly.
[0039] Collecting voltage information at both the reactant inlet and outlet sides of the membrane electrode assembly and the bipolar plate allows for improved monitoring of the voltage distribution across the entire active region.
[0040] According to a further preferred embodiment, the voltage monitoring interface element is a foil made of a conductive material (especially silver or gold foil) attached to at least one of an anode, cathode, membrane, sub-gasket, and / or gas diffusion layer.
[0041] Alternatively or additionally, the voltage monitoring interface element is designed as a conductive coating (particularly a silver or gold coating) of at least one of the following: anode, cathode, membrane, sub-gasket, and / or gas diffusion layer.
[0042] A further aspect of the invention relates to a fuel cell stack comprising a plurality of bipolar plates consisting of anode plates and cathode plates attached to each other, wherein the bipolar plates are alternately stacked with a plurality of membrane electrode assemblies such that the bipolar plates clamp the membrane electrode assemblies, wherein the voltage generated by the membrane electrode assemblies is monitored by means of voltage monitoring interface elements arranged at the membrane electrode assemblies as described above.
[0043] According to a further preferred embodiment, the fuel cell stack also includes a voltage monitoring unit comprising a plug-like element having a plurality of contact pin elements designed to connect to a voltage monitoring interface element in a connection area, wherein the voltage monitoring interface element is exposed to the environment. Because the connection area provided by the voltage monitoring interface element is exposed to the environment, it facilitates contact with the contact pin elements.
[0044] Alternatively or additionally, the plug-like element may also have multiple contact clamping elements designed to connect to the voltage monitoring interface element by clamping it in the connection area, wherein the voltage monitoring interface element is exposed to the environment.
[0045] Further preferred embodiments are defined in the dependent claims, as well as in the specification and drawings. Thus, elements described or shown in combination with other elements may exist alone or in combination with other elements without departing from the scope of protection.
[0046] Preferred embodiments of the invention are described below with reference to the accompanying drawings, which are merely illustrative and not intended to limit the scope of protection. The scope of protection is defined only by the appended claims. Attached Figure Description
[0047] Figure 1 is a schematic diagram of a fuel cell stack with a voltage monitoring device according to the prior art;
[0048] Figure 2 is a schematic top view of the bipolar plate;
[0049] Figure 3a is a schematic top view of the membrane electrode assembly;
[0050] Figure 3b is a schematic cross-section of the membrane electrode assembly of Figure 3a;
[0051] Figure 4 is a schematic diagram of a fuel cell stack with a voltage monitoring device according to the first embodiment;
[0052] Figure 5 is a schematic diagram of a fuel cell stack with a voltage monitoring device according to the second embodiment;
[0053] Figure 6 is a schematic diagram of a fuel cell stack with a voltage monitoring device according to the third embodiment;
[0054] Figure 7 is a schematic diagram of a fuel cell stack with a voltage monitoring device according to the fourth embodiment;
[0055] Figure 8 is a schematic diagram of a plug-shaped element having a voltage monitoring device according to the fifth embodiment;
[0056] Figure 9 is a schematic diagram of a membrane electrode assembly with a voltage monitoring interface element according to the first embodiment;
[0057] Figure 10 is a schematic diagram of a membrane electrode assembly with a voltage monitoring interface element according to the second embodiment;
[0058] Figure 11 is a schematic diagram of a membrane electrode assembly with a voltage monitoring interface element according to a third embodiment;
[0059] Figure 12 is a schematic diagram of a membrane electrode assembly with a voltage monitoring interface element according to the fourth embodiment;
[0060] Figure 13 is a schematic diagram of a membrane electrode assembly with a voltage monitoring interface element according to a fifth embodiment;
[0061] Figure 14 is a schematic diagram of a membrane electrode assembly with a voltage monitoring interface element according to the sixth embodiment;
[0062] Figure 15 is a schematic diagram of a membrane electrode assembly with a voltage monitoring interface element according to the seventh embodiment;
[0063] Figure 16 is a schematic diagram of a membrane electrode assembly with a voltage monitoring interface element according to the eighth embodiment;
[0064] Figure 17 is a schematic diagram of a membrane electrode assembly with a voltage monitoring interface element according to the ninth embodiment; and
[0065] Figure 18 is a schematic diagram of a membrane electrode assembly having a voltage monitoring interface element according to the tenth embodiment. Detailed Implementation
[0066] In the following text, elements that are the same or have similar functions are indicated by the same reference numerals.
[0067] Figure 1 shows a schematic diagram of a known voltage monitoring device for a fuel cell stack 2 according to the prior art. The fuel cell stack 2 includes a plurality of bipolar plates 4-1 to 4-5 clamping membrane electrode assemblies 6-1 to 6-5. The bipolar plates 4 themselves are combinations of anode plates (not shown) and cathode plates (not shown) fixed to each other. Figure 2 shows such a bipolar plate 4, where only the cathode plate or anode plate is shown. The cathode plate and anode plate forming the bipolar plate 4 are typically conductive metal plates or graphite plates, i.e., so-called flow field plates, which have a flow field 42 for reactants on one side and a flow field for cooling fluids on the other side (not visible in the schematic diagram of Figure 2). In the assembled state of the bipolar plates 4, the flow field plates are stacked on top of each other such that the cooling fluid flow fields face each other and the reactant flow fields 42 face the clamped membrane electrode assemblies 6. The bipolar plate 4 also has manifold inlet openings 44, 45, 46 and manifold outlet openings 47, 48, 49 for reactants and coolant, respectively, which are fluidly connected to their respective flow fields 42 and form tubes in the stacked arrangement for guiding reactants and coolant through the fuel cell stack.
[0068] Figure 3 schematically shows the membrane electrode assembly 6 in a top view (see Figure 3a) and a cross-sectional view (see Figure 3b).
[0069] Similar to bipolar plate 4, the membrane electrode assembly also has manifold inlet openings 64, 65, 66 and manifold outlet openings 67, 68, 69 for reactants and coolant. These openings, together with the manifolds of the bipolar plates, form conduits in the stacked arrangement for guiding reactants and coolant through the fuel cell stack. The membrane electrode assembly 6 also includes an active region 62, which is covered by the flow field 42 of the bipolar plates and constitutes the location for generating electricity, as will be described in detail with reference to FIG3b.
[0070] As shown in Figure 3b, the membrane electrode assembly 6 typically includes an electron-generating component 14, which includes an ion-conducting membrane 16 and two electrocatalyst layers 18, 20 disposed on opposite sides of the membrane as an anode 18 and a cathode 20. The electron-generating component 14 constitutes the active region 62 of the fuel cell and is typically disposed in the region of the reactant flow field 42 provided by the bipolar plate 4. To uniformly distribute the reactants on the membrane electrode assembly 6, the membrane electrode assembly 6 may further include gas diffusion layers 22, 24 in contact with the electron-generating component 14 and the bipolar plate 4. Furthermore, the gas diffusion layers 22, 24 extend at least over the active region 62 and are disposed at both the cathode and anode sides of the electron-generating component 14, thereby clamping the electron-generating component 14. The gas diffusion layers 22, 24 are typically made of a conductive material and provide voltage transmission from the electron-generating component 14 to the bipolar plate 4.
[0071] Furthermore, the membrane electrode assembly 6 includes an anode-side sub-wafer 26 and a cathode-side sub-wafer 28, which surround the electron-generating assembly 14 like a frame, as shown in FIG3a, and extend across the entire bipolar plate. The sub-wafers 26 and 28 have first sides 26-1 and 28-1 facing the anode and cathode of the membrane electrode assembly 6, respectively, and second sides 26-2 and 28-2 facing the gas diffusion layers 22 and 24, respectively. Since the sub-wafers 26 and 28 can be made of an electrically insulating material, they can also serve as electrical insulation between adjacent bipolar plates 4 to prevent short circuits. Therefore, the membrane electrode assembly 6, and particularly the sub-wafers 26 and 28 of the membrane electrode assembly 6, not only cover the bipolar plate 4 but also protrude from it, as shown in FIG1.
[0072] The fuel cell stack 2 generates a total voltage as a result of the individual voltages of each power generation assembly 14, which are accumulated and transmitted via bipolar plates 4. Since the power generation assemblies 14 and bipolar plates 4 may wear down over time, the generated voltages must be monitored to ensure the performance of the fuel cell stack. For this purpose, voltage monitoring units 8-1 to 8-5 are known to be provided at each bipolar plate 4-1 to 4-5. Each voltage monitoring unit 8-1 to 8-5 includes voltage monitoring interface elements 10-1 to 10-5, each connected to the bipolar plates 4-1 to 4-5, for example, in the form of pins as shown in FIG. 1, or any other type of connection, or may be directly soldered to or molded into the bipolar plates 4. Via the voltage monitoring interface elements 10-1 to 10-5, the corresponding voltages of the bipolar plates 4-1 to 4-5 and the power generation assemblies 14 are intercepted and transmitted to a control unit 12 arranged externally or internally.
[0073] As described above and further as shown in Figure 1, the membrane electrode assemblies 6-1 to 6-5 extend over the bipolar plates 4-1 to 4-5, which prevents the voltage monitoring interface elements 10-1 to 10-5 from being inserted into / attached to the bipolar plates 4-1 to 4-5.
[0074] Therefore, the inventors have suggested placing the voltage monitoring interface element at the membrane electrode assembly 6 instead of at the bipolar plate 4. Since the membrane electrode assembly 6 is typically very thin, the voltage monitoring interface element also needs to be very thin, which in turn makes it susceptible to damage. Therefore, the inventors further suggest placing the voltage monitoring interface element entirely at the sub-washer, so that the sub-washer can support the voltage monitoring interface element and thereby increase its robustness.
[0075] Figures 4 to 18 illustrate various implementations of voltage monitoring via a voltage monitoring interface element arranged at the membrane electrode assembly 6, particularly at the sub-wafer and supported by the sub-wafer.
[0076] Figures 4 through 7 also show a fuel cell stack 2 including multiple bipolar plates 4-1 through 4-6 clamping membrane electrode assemblies 6-1 through 6-6. Figures 4 through 18 also show membrane electrode assemblies 6-1 through 6-6, particularly sub-gaskets, with voltage monitoring interface elements 10-1 through 10-6, wherein voltage monitoring interface element 10 is made of a conductive material (e.g., gold or silver foil or coating) and is in contact with conductive materials present in the membrane electrode assembly 6, particularly with anode / cathode materials 18; 20 and / or gas diffusion layers 22; 24.
[0077] As further shown in Figure 4, for voltage monitoring, the voltage monitoring interface element 10 should be accessible by the voltage monitoring unit 8, which can be designed as a plug-like element 82 with multiple comb-like support elements 84. The support elements 84 can be designed as rods 84-1 to 84-5 extending from the substrate 86. Thus, the rods 84 can be designed for direct contact with the voltage monitoring interface elements 10-1 to 10-5 arranged at the membrane electrode assemblies 6-1 to 6-5, and / or can be designed as support elements providing contact possibility to the voltage monitoring interface element 10. Since the membrane electrode assemblies 6-1 to 6-5, particularly the sub-gaskets, extend around the corresponding bipolar plates 4-1 to 4-5, the voltage monitoring interface element 10 is exposed to the environment and easily accessible, and can be contacted without problems by means of the plug-like element 82. Additional plug-like elements 82-2… (not shown) can be arranged below or above the shown plug-like element 82 and can be adapted to contact other membrane electrode assemblies, such as 6-6….
[0078] As described above, the support elements 84-1 to 84-5 of Figure 4 can be designed as rods that provide contact elements for the voltage monitoring interface element 10, as shown in Figure 4. However, the support element 84 can also be designed to interact with additional electrical contact elements 88, as shown in Figures 5 and 6.
[0079] As shown in Figure 5, the voltage monitoring unit 8 also includes electrical contact elements 88, for example in the form of pins 88-1 to 88-5, which can be inserted into the base 86 and are designed to contact voltage monitoring interface elements 10-1 to 10-5. Preferably, the pins 88 are inserted between the support element 84 and the voltage monitoring interface element 10, such that the support element 84 ensures that the pins 88 remain in contact with the voltage monitoring interface element 10.
[0080] Alternatively or additionally, the voltage monitoring unit 8, particularly the plug-like element 82, may further include a clamping element 89, which ensures that the membrane electrode assembly 6 is clamped between the clamping element 89 and the support element 84, as shown in FIG6.
[0081] As further shown in Figure 6, the electrical contact element 88, i.e. the pin of the plug-like element, does not necessarily extend through the base 86 (as shown in Figure 5), but can be embedded in the base 86 and interconnected for transmitting voltage measurements to the control unit.
[0082] As further shown in Figure 7, the support element 84, electrical contact element 88, and / or clamping element 89 can be offset from each other to ensure that even with small-sized membrane electrode assemblies 6 and bipolar plates 4, each membrane electrode assembly 6 can be directly contacted by the support element 84 or by means of an additional electrical contact element 88 at its voltage monitoring interface element 10. As further seen in Figure 8, the support element 84 can also have different lengths, which also allows contact with the voltage monitoring interface element 10 at different locations.
[0083] Figures 9 through 12 illustrate different embodiments for integrating the voltage monitoring interface element 10 into the membrane electrode assembly 6. As described above, the membrane electrode assembly 6 typically includes an ion-conducting membrane 16 and two electrocatalyst layers 18, 20 disposed on opposite sides of the membrane as an anode 18 and a cathode 20. The illustrated membrane electrode assembly 6 also includes gas diffusion layers 22, 24 in contact with the power generation assembly 14 and the bipolar plate 4. The gas diffusion layers 22, 24 are typically made of a conductive material and provide voltage transmission from the power generation assembly 14 to the bipolar plate 4. Therefore, both the gas diffusion layers 22, 24 and the electrocatalyst layers 18, 20 provide information about the voltage of the unit fuel cell. Thus, both can be used as voltage information providing elements, which can be used to monitor the voltage generated by the power generation assembly 14.
[0084] Furthermore, as described above, the membrane electrode assembly 6 includes sub-gaskets 26 and 28, which are made of electrically insulating material and also serve as electrical insulation between adjacent bipolar plates 4 to prevent short circuits. As described above with reference to FIG3b, the sub-gaskets 26 and 28 also include a first side 26-1 and 28-1 facing the electrodes 18 and 20 of the membrane electrode assembly 6, and a second side 26-2 and 28-2 facing the gas diffusion layers 22 and 24, respectively. Since the sub-gaskets 26 and 28 surround the active region of the membrane electrode assembly 6 like a frame and protrude from the bipolar plates 2, they provide an ideal location for arranging and supporting voltage monitoring interface elements. The voltage monitoring interface elements then contact the voltage supply components of the fuel cell stack (e.g., anode / cathode, gas diffusion layers, and / or bipolar plates) on one side. On the other side, the voltage monitoring interface elements are exposed to the environment and provide connection areas for contact elements, such as those for plug-like elements 82.
[0085] Since the gas diffusion layers 22, 24 and the electrocatalyst layers 18, 20 provide information about voltage, the voltage monitoring interface element 10 can also be arranged at the gas diffusion layers 22, 24 and / or the electrocatalyst layers 18, 20.
[0086] According to the first embodiment and as shown in FIG9, the voltage monitoring interface element 10 may be arranged to make electrical contact with the gas diffusion layer 22. For this purpose, the voltage monitoring interface element 10 may be a foil or coating made of a conductive material (e.g., silver or gold) disposed / attached to the sub-waist gasket 26. In the illustrated embodiment, the voltage monitoring interface element 10 is disposed between the gas diffusion layer 22 and the sub-waist gasket 26.
[0087] As further shown in Figure 9, the voltage monitoring interface element 10 at least partially covers the second side 26-2 of the sub-washer 26, particularly in the peripheral region of the sub-washer 26. To further illustrate, the voltage monitoring interface element 10 is entirely supported by the sub-washer 26 and exposed to the environment in the connection area 11, allowing the voltage monitoring interface element 10 to be contacted by the voltage monitoring unit 8, as explained above with respect to Figures 4 through 8.
[0088] Figure 10 illustrates one embodiment in which the voltage monitoring interface element 10 can contact both the anode 18 and the anode-side gas diffusion layer 22. For this purpose, the anode-side sub-gasket 26 has an opening 30 through which the voltage monitoring interface element 10 can be guided. Furthermore, the voltage monitoring interface element 10 has a first portion 10a, a second portion 10b, and a third portion 10c. The first portion 10a is disposed on a first side 26-1 of the sub-gasket 26 and is in electrical contact with the anode layer 18; the second portion 10b extends through the opening in the sub-gasket 26; and the third portion 10c is disposed on a second side 26-2 of the sub-gasket 26 and is in electrical contact with the gas diffusion layer 22. Similarly, the voltage monitoring interface element is entirely supported by the sub-gasket 26, but is equipped with a connection area 11 exposed to the environment, allowing the voltage monitoring interface element 10 to be accessed externally, for example, through the voltage monitoring unit 8. The second part 10b of the voltage monitoring interface element 10 may be a foil or coating that extends through the sub-washer 26 and connects the two more widely distributed parts 10a, 10c of the voltage monitoring interface element 10, or even a wire.
[0089] It goes without saying that, alternatively or otherwise, the voltage monitoring interface element 10 may be disposed at and electrically contacted with the cathode 20 and / or the cathode-side gas diffusion layer 28. It should be further noted that the first portion 10a of the voltage monitoring interface element 10 may also be disposed at the gas diffusion layers 22; 24, and the third portion 10c may be disposed at the electrocatalyst layers 18; 20. However, in this case, further measures are required to expose the voltage monitoring element 10 to the environment, as will be further explained below with reference to Figures 11 and 12.
[0090] Figure 11 illustrates one embodiment in which the voltage monitoring interface element 10 is arranged to make electrical contact only with the electrocatalyst layers 18; 20. As shown, the voltage monitoring interface element 10 may be a coating or foil, which is attached to and supported, for example, on and by the sub-gasket 26 at a first side 26-1 facing the power generation assembly 14. Further shown in the embodiment of Figure 10, the power generation assembly 14 does not extend as far as the sub-gaskets 26, 28, and the sub-gaskets 26, 28 are in contact with each other in the periphery of the membrane electrode assembly 6.
[0091] In order to intercept voltage information from the voltage monitoring interface element 10 and expose the voltage monitoring interface element to the environment, one of the sub-washers 26, 28 may be provided with an area in which the edge 32 of one of the sub-washers 26 is recessed relative to the edge 34 of the other sub-washer 28, so that the voltage monitoring interface element 10 is exposed and can be directly accessed in the connection area 11, as shown in FIG11.
[0092] It goes without saying that the recess does not necessarily need to extend across the entire periphery of the sub-washer, but can be set only at discrete locations or multiple discrete locations, so that the edges 32, 34 of the sub-washers 26; 28 are flush in one region, while one of the edges 32; 34 of the sub-washers 26; 28 is recessed in other regions.
[0093] Figure 12 illustrates one embodiment in which the voltage monitoring interface element 10 is arranged in a frame-like manner around the electrocatalyst layer (e.g., anode 18). Thus, the voltage monitoring interface element 10 can be fully embedded into the power generation assembly 14. However, in the same case, the voltage monitoring interface element is supported by sub-gaskets 16; 28 to provide sufficient robustness.
[0094] To provide access to the voltage monitoring interface element 10, the edges 32, 34 of the sub-washers 26 and 28 are again recessed in at least one region, so that the voltage monitoring interface element 10 is exposed to the environment in the connection area 11.
[0095] It goes without saying that combinations of the embodiments shown in Figures 11 and 12 are also possible.
[0096] Figures 13 to 18 show top views of membrane electrode assemblies 6 having different embodiments of voltage monitoring interface element 10.
[0097] As can be seen in Figure 13 and shown in the cross-sections of Figures 11a and 12c, the voltage monitoring interface element 10 extends to the edges 32, 34 of the sub-gaskets 26; 28. As further seen in Figure 13, the voltage monitoring interface element 10 extends over the entire length of the active region 62 provided by the electron-generating assembly 14, which allows for voltage information to be obtained over the entire length of the membrane electrode assembly. This is particularly interesting during the startup phase, as the voltage at the inlet region 61 of the active region 62 may differ from the voltage at the outlet region 63.
[0098] Alternatively, and as shown in FIG14 and in the cross-sections of FIG11 and FIG12, it is also possible that the voltage monitoring interface element 10 does not extend to the edges 32, 34 of the sub-washers but terminates before them. Again in this case, it is advantageous for the voltage monitoring interface element 10 to extend over the entire length of the active region 62. However, also in this case, one of the sub-washers may be recessed to provide a connection area for the voltage monitoring interface element exposed to the environment.
[0099] Furthermore, by means of the extended voltage monitoring interface element 10 (e.g., along the entire length of the active region), it is possible for the voltage monitoring interface elements 10 of adjacent cell fuel cells to contact each other at different locations along the length of the voltage monitoring interface element 10 (see, for example, Figure 7).
[0100] Alternatively, the contact element 62 may not be along its entire length. It is also possible that the voltage monitoring interface element 10 has a voltage monitoring interface element connection element 13 that contacts the active region 62. Thus, it may have multiple contact elements as shown in FIG. 15 or only a single contact element as shown in FIG. 16.
[0101] In addition to arranging the voltage monitoring interface element 10 on the long side of the membrane electrode assembly 6 and thus on the long side of the active region 62, the voltage monitoring interface element 10 can also be arranged in the region of the manifold openings 64-69. Figures 17 and 18 show two embodiments with the voltage monitoring interface element 10 arranged in the region of the manifold openings 64-69.
[0102] As shown in Figure 17, the voltage monitoring interface element 10 can be designed as an elongated element, which is connected to the active region 62 by means of the connecting element 13. The elongation of the voltage monitoring interface element 10 again allows for contact at different locations from unit fuel cell to unit fuel cell as described above.
[0103] Alternatively, as shown in Figure 18, discrete voltage monitoring flags or strips 10-1, 10-2, 10-3 may be designed, extending from the membrane electrode assembly 6 and accessible to or integrated into a specially designed voltage monitoring unit 8. Strips 10-1 to 10-3 may be supported by strips or flags 31-1 to 31-3 formed from sub-washers 28; 26.
[0104] Even though the voltage monitoring interface element 10 is shown only as being arranged on the inlet side of the membrane electrode assembly 6 in Figures 17 and 18, the voltage monitoring interface element 10 may also be arranged on the outlet side of the membrane electrode assembly, or even on both the inlet and outlet sides.
[0105] In all cases, it is also possible that one of the sub-washers is partially recessed, exposing the voltage monitoring interface element 10 for direct access.
[0106] Alternatively, the voltage monitoring interface element is arranged on the second side 26-2; 28-2 of the corresponding sub-washers 26; 28.
[0107] A voltage monitoring device can be proposed by providing the voltage monitoring interface element 10 directly at the membrane electrode assembly 6, which can be easily manufactured during the fabrication of the membrane electrode assembly 6 itself. Since the membrane electrode assembly 6 typically extends over the bipolar plate 4, the voltage monitoring interface element 10 disposed at the membrane electrode assembly 6 can be accessed in a simple manner. To provide sufficient robustness for the voltage monitoring interface element, even though it is located at the membrane electrode assembly, the voltage monitoring interface element is entirely supported by a sub-wafer and has a connection area in which the voltage monitoring interface element is exposed to the environment for easy access. Furthermore, due to the elongated shape of the voltage monitoring interface element 10, or due to the possibility of arranging the voltage monitoring interface element 10 at both the inlet and outlet sides of the membrane electrode assembly 6, information about the voltage difference across the entire unit fuel cell can be obtained, which is particularly important during startup or for determining wear on the fuel cell stack or unit fuel cell.
[0108] Figure Labels
[0109] 2. Fuel Cell Stack
[0110] 4 bipolar plates
[0111] 6. Membrane Electrode Assembly
[0112] 8 Voltage Monitoring Unit
[0113] 10 Voltage monitoring interface components
[0114] 11 Connecting Area
[0115] 13 Connecting elements
[0116] 12. Control units arranged externally or internally.
[0117] 14 electronic components
[0118] 16 Ion Conducting Membranes
[0119] 18. Electrocatalyst layer, anode
[0120] 20 Electrocatalyst layer, cathode
[0121] 22, 24 Gas diffusion layers
[0122] 26 Anode side gasket
[0123] 28 Cathode side gasket
[0124] 26-1; 28-1 First side of the sub-washer
[0125] 26-2, 28-2 Second side of the sub-washer
[0126] 30 Opening
[0127] 31 Sub-wafer flag
[0128] 32, 34, 36 Edges
[0129] 42 Flow Field
[0130] 44, 45, 46 Bipolar plate inlet openings
[0131] 47, 48, 49 Bipolar plate outlet openings
[0132] 61 Membrane electrode assembly inlet area
[0133] 62 Active region of membrane electrode assembly
[0134] 63 Membrane Electrode Module Outlet Area
[0135] 64, 65, 66 Membrane electrode assembly inlet openings
[0136] 67, 68, 69 Membrane electrode assembly outlet openings
[0137] 82 Plug-like components
[0138] 84. Comb-shaped support element, rod
[0139] 86 matrix
[0140] 88 Electrical contact elements, pins
[0141] 89 Fixture Components
Claims
1. A membrane electrode assembly (6) for a fuel cell stack (2), comprising at least one electron generating assembly (14), the electron generating assembly (14) comprising an ion-conducting membrane (16) and two electrocatalyst layers (18, 20) disposed on opposite sides of the membrane as an anode (18) and a cathode (20), wherein the membrane electrode assembly further comprises at least one sub-wafer (26) surrounding the electron generating assembly (14), wherein the at least one sub-wafer (26, 28) has a first side (26-1; 28-1) facing the electron generating assembly (14) and a second side (16-2; 28-2) opposite to the first side and facing away from the electron generating assembly (14). Its features are, At least one voltage monitoring interface element (10) is disposed at the membrane electrode assembly (6) and adapted to contact the voltage supply component of the membrane electrode assembly (6) or the fuel cell stack, wherein the voltage monitoring interface element (10) is disposed entirely on and supported by at least one side of the sub-wafer (26; 28), wherein the corresponding side (26-1, 28-1; 26-2, 28-2) of the sub-wafer (26; 28) supporting the voltage monitoring interface element (10) is at least partially exposed to the external environment to provide a connection area (11).
2. The membrane electrode assembly (6) according to claim 1, wherein at least one of the at least one voltage monitoring interface element (10) is disposed on the second side (26-2; 28-2) of the sub-wafer (26; 28) and is adapted to be in direct or indirect contact with the bipolar plate, wherein the bipolar plate clamps the membrane electrode assembly (6) in the assembled state of the fuel cell stack.
3. The membrane electrode assembly (6) according to claim 1 or 2, wherein the membrane electrode assembly (6) further comprises an anode-side gas diffusion layer (26) preferably made of conductive fibers and a cathode-side gas diffusion layer (28) preferably made of conductive fibers, wherein the gas diffusion layers (22, 24) at least clamp the power generation assembly (14), and wherein at least one of the at least one voltage monitoring interface elements (10) is disposed on the second side of the sub-gasket and in contact with the anode-side (26) and / or cathode-side (28) gas diffusion layers.
4. The membrane electrode assembly (6) according to any one of the preceding claims, wherein at least one of the at least voltage monitoring interface elements (10) is disposed on a first side (26-1; 28-1) of the at least one sub-wafer (26; 28) and is in contact with at least one of the electrocatalyst layers (18, 20) of the electron generating assembly (14), particularly with the anode (18) and / or cathode (20).
5. The membrane electrode assembly (6) according to claim 4, wherein the membrane electrode assembly (6) further comprises an anode-side sub-wafer (26) surrounding the periphery of the anode (18) and a cathode-side sub-wafer (28) surrounding the periphery of the cathode (20), and wherein at least one voltage monitoring interface element (10) is disposed between the anode-side sub-wafer (26) and the cathode-side sub-wafer (28), and wherein one of the sub-wafers (26, 28) is recessed relative to the other sub-wafer (26, 28) at at least one location to form the connection region (11) in which the voltage monitoring interface element (10) is exposed to the environment.
6. The membrane electrode assembly (6) according to any one of the preceding claims, wherein the at least one sub-gasket (26, 28) has at least one tunnel-like opening (30) extending from the first side (26-1; 28-1) of the sub-gasket (26; 28) to the second side (26-2; 28-2), and at least one of the at least one voltage monitoring interface elements (10) has a first portion (19a), a second portion (10b) and a third portion (10c), the first portion (19a) being disposed on the first side (16-1; 28-1) of the sub-gasket (26; 28) and in contact with the electrocatalyst layer (18, 20), the second portion (10b) extending through the tunnel-like opening (30) in the sub-gasket (26, 28), and the third portion (10c) being disposed on the second side (16-2; 28-2) of the sub-gasket and exposed to the environment to provide the connection area (11).
7. The membrane electrode assembly (6) according to any one of the preceding claims, wherein at least one of the sub-gaskets (26, 28) further comprises at least one strip (31) protruding from the periphery of the membrane electrode assembly (6), and wherein the voltage monitoring interface element (10) has at least one protruding connecting element extending from the periphery of the membrane electrode assembly (6), wherein preferably, the at least one strip (31) of the sub-gasket is sized and / or shaped to support the at least one protruding connecting element.
8. The membrane electrode assembly (6) according to any one of the preceding claims, wherein the voltage monitoring interface element (10) is designed as an elongated element having a length that contacts at least one of the anode (18), the cathode (20), the membrane (6), the sub-gaskets (26, 28) and / or the gas diffusion layer (22, 24) along its length.
9. The membrane electrode assembly (6) according to any one of claims 1 to 8, wherein the voltage monitoring interface element (10) has an elongated body (86) attached to the at least one sub-wafer (26, 28), and further includes at least one discrete internal electrical connection element (13) extending from the elongated body (86) along the direction of the anode (18), the cathode (20), the membrane (6) and / or the gas diffusion layer, and contacting at least one of the anode (18), the cathode (20), the membrane (6) and / or the gas diffusion layer (22, 24).
10. The membrane electrode assembly (6) according to any one of the preceding claims, wherein at least one first voltage monitoring interface element (10) and at least one second voltage monitoring interface element (10) are provided, wherein the at least one first voltage monitoring interface element (10) is disposed on the reactant or coolant inlet side (61) of the membrane electrode assembly (6), and the at least one second voltage monitoring interface element (10) is disposed on the reactant or coolant outlet side (63) of the membrane electrode assembly (6).
11. The membrane electrode assembly (6) according to any one of the preceding claims, wherein the voltage monitoring interface element (10) is designed as a conductive coating of the at least one sub-wafer, particularly a silver or gold coating.
12. The membrane electrode assembly (6) according to any one of the preceding claims, wherein the voltage monitoring interface element (10) is a foil made of a conductive material (in particular silver or gold foil) attached to at least one of the anode (18), the cathode (20), the membrane (6), the sub-gaskets (26, 28) and / or the gas diffusion layer (22, 24).
13. A fuel cell stack (2) comprising a plurality of bipolar plates consisting of anode plates (18) and cathode plates (20) attached to each other, wherein the bipolar plates are alternately stacked with a plurality of membrane electrode assemblies such that the bipolar plates clamp the membrane electrode assemblies (6), characterized in that, The membrane electrode assembly (6) is the membrane electrode assembly according to any one of claims 1 to 12.
14. The fuel cell stack (2) according to claim 13 further includes a voltage monitoring unit (8) comprising a plug-like element (82) having a plurality of contact pin elements (84) designed to connect to the voltage monitoring interface element (10) in the connection area, wherein the voltage monitoring interface element is exposed to the environment.
15. The fuel cell stack (2) according to claim 13 further includes a voltage monitoring unit (8) comprising a plug-like element (82) having a plurality of contact clamping elements (84) designed to connect to the voltage monitoring interface element (10) by clamping the voltage monitoring interface element (10) in the connection area, wherein the voltage monitoring interface element is exposed to the environment.