Fuel cell, fuel cell single cell, bipolar plate and cathode plate thereof

Abstract

The embodiments of the present invention disclose a fuel cell, a fuel cell cell, a bipolar plate and a cathode plate thereof. The fuel cell includes a plurality of fuel cell cells, the fuel cell cell includes a cathode plate, the bipolar plate includes a cathode plate, an anode plate and a cooling medium channel, the cathode plate includes a metal cathode plate body and a gasket, one surface of the cathode plate body includes: an air inlet and an air outlet; a plurality of flow channels connecting the air inlet and the air outlet; at least one flow channel is provided with a gasket at the bottom near one end of the air outlet; the other surface of the cathode plate body is used for contacting with the cooling medium, and the thermal conductivity of the gasket material is less than the thermal conductivity of the cathode plate body. The beneficial effect of the present application is that the generation of liquid water can be reduced, so that more water can be discharged from the cathode plate in gaseous form, thereby avoiding flooding in the downstream of the cathode plate flow field.

Description

Technical Field

[0001] The present application relates to the field of fuel cells, and in particular, to fuel cells, fuel cell cells, bipolar plates and cathode plates thereof. Background Art

[0002] In a proton exchange membrane fuel cell, the fuel gas passes through the anode gas diffusion layer to the catalyst layer, where an electrode reaction occurs under the action of the catalyst. The electrons generated by the electrode reaction flow through the external circuit through the conduction of the catalyst layer to the cathode, while the hydrogen ions reach the cathode under the action of the proton exchange membrane. After passing through the cathode gas diffusion layer, oxygen undergoes an electrode reaction with the hydrogen ions and electrons under the action of the catalyst to generate water.

[0003] Since water is generated at the cathode, only a small amount of water will enter the anode plate through the proton exchange membrane and the anode gas diffusion layer, while a large amount of water will enter the cathode plate through the cathode gas diffusion layer, so the cathode plate is the "hardest hit area" for flooding. In the cathode plate flow field, as the gas participates in the reaction, the gas pressure gradually decreases, the flow rate decreases, but the generated water increases. The lower gas flow rate increases the difficulty of drainage, resulting in flooding downstream of the cathode plate flow field.

[0004] Some existing fuel cells have a certain drainage structure, but it is not completely effective. Summary of the invention

[0005] One of the key points of the present invention is that the inventor has discovered another reason why the current fuel cell cathode plate flow field is prone to flooding. The inventor has discovered that the heat generated when the fuel cell is working will cause part of the generated water to exist in gaseous form, and the cooling system of the fuel cell will also cool the gas in the flow channel when cooling the fuel cell. Therefore, part of the gaseous water is cooled to form condensed water. This problem is more prominent downstream of the cathode plate flow field, making it easy for flooding to occur downstream of the cathode plate flow field. Based on the above findings of the inventor, the present invention proposes a fuel cell cell and a cathode plate thereof, aiming to solve the above problems existing in the prior art.

[0006] To achieve the above object, the present invention provides a fuel cell cathode plate, characterized in that it includes a metal cathode plate body and a gasket;

[0007] One side of the cathode plate body comprises:

[0008] Air inlet and outlet;

[0009] A plurality of flow channels communicating the air inlet and the air outlet, including an opening toward a membrane electrode of the fuel cell;

[0010] At least one of the flow channels is provided with the gasket at the bottom near one end of the air outlet;

[0011] The other side of the cathode plate body is used for contacting with the cooling medium, and the thermal conductivity of the gasket material is smaller than the thermal conductivity of the cathode plate body.

[0012] In some embodiments, the gasket material is rubber;

[0013] The cathode plate body is formed by stamping, and the gasket is fixed in the flow channel by injection molding or bonding.

[0014] In some embodiments, the length of the gasket is 1 / 5-1 / 2 of the length of the flow channel.

[0015] In some embodiments, the maximum height of the gasket is H, the depth of the flow channel is D, and H and D satisfy the following conditions:

[0016] 0.5D<H<0.8D.

[0017] In some embodiments, the spacer is a planar spacer of fixed height;

[0018] The length of the planar gasket is 1 / 5-1 / 4 of the length of the flow channel.

[0019] In some embodiments, the gasket is a wedge-shaped gasket, and the height thereof gradually increases toward the air outlet;

[0020] The length of the wedge-shaped gasket is 1 / 4-1 / 2 of the length of the flow channel.

[0021] In some embodiments, the gasket is a multi-step gasket, and the step heights gradually increase toward the air outlet;

[0022] The length of the multi-step gasket is 1 / 5-2 / 5 of the length of the flow channel.

[0023] In addition, to achieve the above-mentioned purpose, the present invention also proposes a fuel cell bipolar plate, characterized in that it includes:

[0024] A cathode plate as described in any of the preceding embodiments;

[0025] an anode plate, fixedly connected to the other side of the cathode plate away from the flow channel;

[0026] A cooling medium channel is provided between the anode plate and the cathode plate, and the cooling medium flows in the cooling medium channel.

[0027] In addition, to achieve the above-mentioned purpose, the present invention also proposes a fuel cell cell, characterized in that it includes a cathode plate as described in any of the above-mentioned embodiments.

[0028] In addition, to achieve the above-mentioned purpose, the present invention also proposes a fuel cell, characterized in that it includes a plurality of fuel cell cells as described in the above-mentioned embodiments.

[0029] The fuel cell cathode plate proposed in the present application includes a cathode plate body and a gasket. A gasket is arranged at the bottom of a section of the cathode plate flow channel near the gas outlet. The gasket has a certain height, which can reduce the cross-sectional area of ​​the flow channel, increase the gas flow rate, and speed up drainage. In addition, the thermal conductivity of the gasket material is smaller than the thermal conductivity of the cathode plate body, so that the gasket can play a heat insulation effect. With the heat generated when the fuel cell is working, a higher gas temperature can be maintained at the flow channel with the gasket, so that the water generated by the reaction is discharged in a gaseous form, reducing the generation of liquid water, thereby avoiding flooding downstream of the cathode plate flow field. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0031] The methods, systems and / or programs in the accompanying drawings will be further described according to exemplary embodiments. These exemplary embodiments will be described in detail with reference to the drawings. These exemplary embodiments are non-limiting exemplary embodiments, wherein reference numerals represent similar mechanisms in the various views of the accompanying drawings.

[0032] Figure 1 This is a cathode plate structure diagram involved in some embodiments of the present application;

[0033] Figure 2 for Figure 1 A cross-sectional view of the cathode plate flow field region and the cooling medium channel along line AA;

[0034] Figure 3 A cross-sectional view of a cathode plate flow field region and a cooling medium channel with a wedge-shaped gasket along line AA according to some embodiments of the present application;

[0035] Figure 4 A cross-sectional view of a cathode plate flow field region and a cooling medium channel with a multi-step gasket along line AA according to some embodiments of the present application;

[0036] Figure 5 This is a bipolar plate structure diagram involved in some embodiments of the present application;

[0037] Figure 6 This is a structural diagram of a single fuel cell involved in some embodiments of the present application.

[0038] Icons: 1- cathode plate body, 1'- anode plate body, 2- air inlet, 3- air outlet, 4- distribution area, 5- flow channel, 5'- flow channel, 6- ridge, 6'- ridge, 7- gasket, 8, cooling medium channel, 9- cathode gas diffusion layer, 9'- anode gas diffusion layer, 10- membrane electrode assembly. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0041] Please refer to Figure 1 , Figure 1 It is a schematic diagram of the structure of the cathode plate of the fuel cell in the embodiment of the present application. The cathode plate of the fuel cell in the present embodiment includes a flat metal cathode plate body 1 and a gasket 7. One surface of the cathode plate body 1 includes an air inlet 2, an air outlet 3, two distribution areas 4, a plurality of flow channels 5, and a plurality of ridges 6. The air inlet 2 and the air outlet 3 are located at the two ends of the surface of the cathode plate body 1. The plurality of flow channels 5 are arranged between the air inlet 2 and the air outlet 3. One end of the plurality of flow channels 5 is connected to the air inlet 2 through a distribution area 4, and the other end of the plurality of flow channels 5 is connected to the air outlet 3 through another distribution area 4. Adjacent flow channels 5 are separated by ridges 6. The area where the plurality of flow channels 5 are located is the flow field area. Figure 1 The direction of the large arrow in the figure is the flow direction of the reaction gas in the flow channel 5. The flow channel 5 is a groove-like structure with an opening. Figure 1 In the plane shown and without covering, when the cathode plate is assembled in the fuel cell, the opening of the flow channel 5 faces the membrane electrode of the fuel cell, and the flow field area is in contact with the gas diffusion layer, that is, the ridge 6 and the flow channel 5 are adjacent to the gas diffusion layer, so that the reaction gas in the flow channel 5 can enter the gas diffusion layer through the opening of the flow channel 5. At the same time, the water produced by the reaction will also enter the flow channel 5 through the gas diffusion layer.

[0042] In the fuel cell cathode plate of this embodiment, at least one flow channel 5 is provided with a gasket 7 at the bottom near the gas outlet 3. As a preferred embodiment, a gasket 7 is provided at the bottom of each flow channel 5 near the gas outlet 3. It can be understood that Figure 1 The size and number of the flow channel 5 and the ridge 6 are modified in order to clearly show the gasket 7. The present embodiment does not impose any restrictions on the size and number of the flow channel 5 and the ridge 6. The flow channel 5 and the ridge 6 can be Figure 1 It can be a straight line shape, or it can be a wavy shape or other shapes.

[0043] Please refer to Figure 2 , Figure 2 exist Figure 1 A cooling medium channel 8 is added to the cross-sectional view of the cathode plate flow field region along the AA line. The other side of the cathode plate body 1 is in contact with the cooling medium so that the heat generated by the fuel cell cell when generating electricity can be transferred out of the fuel cell cell through the cooling medium, so that the temperature inside the fuel cell cell is kept within the normal operating range. The contact between the other side of the cathode plate body 1 and the cooling medium can be direct contact or indirect contact through other structures. For example, the cooling medium is disposed in the cooling medium channel 8, and the other side of the cathode plate body 1 is in direct contact with the outer wall of the cooling medium channel 8. This embodiment does not limit the contact method between the other side of the cathode plate body 1 and the cooling medium, as long as the heat generated by the fuel cell can be conducted to the cooling medium through the other side of the cathode plate body 1.

[0044] It can be understood that since the other side of the cathode plate body 1 is in contact with the cooling medium, the cooling medium will also cool the gas in the flow channel 5. The water entering the flow channel 5 partially exists in the form of gas, and after being cooled, it forms condensed water and gathers in the flow channel 5, thereby aggravating the flooding phenomenon downstream of the cathode plate flow field.

[0045] In this embodiment, the water generated by the fuel cell is mainly concentrated in the downstream section of the flow channel 5, that is, mainly concentrated in a section of the flow channel 5 near the gas outlet 3, while the flow channel 5 near the gas inlet 2 is relatively lacking in water. In this embodiment, a gasket 7 is arranged at the bottom of the flow channel 5 near the gas outlet 3, and the thermal conductivity of the gasket 7 material is less than the thermal conductivity of the cathode plate body 1, so that the gasket 7 can play a heat insulation effect; the heat generated by the fuel cell when working is gathered at the gasket 7 of the flow channel 5 and maintains a high gas temperature. The high temperature allows more water generated by the reaction to be discharged in a gaseous form, reducing the generation of liquid water, thereby avoiding flooding in the downstream of the cathode plate flow field. As an optional method, the material of the metal cathode plate body 1 in this embodiment includes but is not limited to a combination of one or more of stainless steel, titanium, aluminum, copper and other alloys or metal single substances, and the thermal conductivity can reach tens to hundreds of watts / meter·degree.

[0046] In addition, the gasket 7 in this embodiment is Figure 2 The cross section shown has a certain height, thereby reducing the cross-sectional area of ​​the flow channel 5 that can be ventilated, increasing the pressure and flow rate of the reaction gas, that is, accelerating the speed at which gaseous water is discharged from the cathode plate, and avoiding the occurrence of water flooding.

[0047] In some embodiments, the gasket 7 is made of rubber. The thermal conductivity of rubber is usually less than 1 W / m·deg., which is much smaller than the thermal conductivity of the metal cathode plate body. The specific type of rubber is not limited in this embodiment, and preferably a rubber with high firmness is injection molded on the corresponding metal. To obtain the cathode plate of this embodiment, a cathode plate body 1 having a plurality of flow channels 5 can be obtained by stamping, and then a fixed gasket 7 can be obtained by injection molding in the flow channels 5, or the gasket 7 can be obtained by processing the gasket 7 separately and then fixed in the flow channels 5 by bonding.

[0048] In some embodiments, the length l of the gasket 7 accounts for 1 / 5-1 / 2 of the length L of the flow channel 5. Figure 2 As shown, the length l of the gasket 7 and the length L of the flow channel 5 are respectively the lengths of the two along the gas flow direction. When the length l of the gasket 7 is greater than 1 / 2 of the length L of the flow channel 5, the excessively long gasket 7 will hinder the cooling medium from taking away the heat of the fuel cell, affect the normal heat dissipation of the fuel cell, and be detrimental to the normal operation of the fuel cell. In addition, the excessively long gasket 7 increases the difficulty of the injection molding or bonding process and reduces the yield rate of the cathode plate processing. When the length l of the gasket 7 is less than 1 / 5 of the length L of the flow channel 5, the length of the gasket 7 is too short and the required thermal insulation effect cannot be obtained, which will cause more gaseous water to be converted into liquid and flooding to occur downstream of the cathode plate flow field.

[0049] In some embodiments, the maximum height of the gasket 7 is H, the depth of the flow channel 5 is D, and H and D satisfy: 0.5D<H<0.8D. Figure 2 As shown, the maximum height of the gasket 7 is the height of the gasket 7 at the outlet of the flow channel 5. When the maximum height H of the gasket 7 is greater than 0.8D, the gasket 7 will cause the cross-sectional area of ​​the flow channel 5 to be too narrow, which is not conducive to the timely discharge of the accumulated water in the flow channel 5, but will cause flooding in the downstream of the flow field; when the maximum height H of the gasket 7 is less than 0.5D, the gasket 7 cannot play a good heat insulation effect, which will cause more gaseous water to be converted into liquid. At the same time, the cross-sectional area of ​​the flow channel 5 is too large, resulting in a slow gas flow rate, which reduces the drainage efficiency.

[0050] In some embodiments, Figure 2As shown, the gasket 7 is a plane gasket 7 of a fixed height. The plane gasket 7 is easy to process and / or fix in the flow channel 5, but in order to ensure the heat insulation effect near the outlet of the downstream of the flow channel 5, the height of the gasket 7 at the outlet will be set relatively high, and the plane gasket 7 is a fixed height. Therefore, in order to avoid the high-height gasket 7 affecting the heat dissipation of other positions downstream of the flow channel 5, the length of the plane gasket 7 cannot be too long. Preferably, the length l of the plane gasket 7 is 1 / 5-1 / 4 of the length L of the flow channel 5.

[0051] In some embodiments, Figure 3 As shown, the gasket 7 is a wedge-shaped gasket 7 with a gradually changing height, and the height gradually increases toward the gas outlet 3. Compared with the plane gasket 7, the processing and / or fixing of the wedge-shaped gasket 7 is more difficult, but the height of the wedge-shaped gasket 7 can be easily adjusted. The wedge-shaped gasket 7 can have a larger height at the outlet of the flow channel 5 to meet the insulation requirements, and can also have a smaller gasket 7 height at other positions to avoid affecting the heat dissipation of the fuel cell. In addition, the height change rate of the wedge-shaped gasket 7, that is, the slope of the wedge-shaped gasket 7 can be changed according to the required factors such as the reaction gas flow rate. Compared with the plane gasket 7, the length of the wedge-shaped gasket 7 can be set longer. Preferably, the length l of the wedge-shaped gasket 7 is 1 / 4-1 / 2 of the length L of the flow channel 5.

[0052] In some embodiments, Figure 4 As shown, the gasket 7 is a multi-step gasket 7, and the step height gradually increases toward the air outlet 3. In this embodiment, each step has a fixed height, and the step closer to the air outlet 3 is thicker. The processing difficulty of the multi-step gasket 7 is not high, and the height of each step can be adjusted more conveniently. Therefore, the multi-step gasket 7 can have the advantages of the plane gasket 7 and the wedge-shaped gasket 7 to a certain extent, and the length of the gasket 7 can be adjusted according to the number and height of the steps. In order to take into account the processing difficulty and the effect, preferably, the multi-step gasket 7 has two steps, and the length l of the multi-step gasket 7 is 1 / 5-2 / 5 of the length L of the flow channel 5.

[0053] Furthermore, in some embodiments, the cathode plate may have one or more of a flat gasket 7 , a wedge-shaped gasket 7 , and a multi-step gasket 7 .

[0054] Some embodiments of the present application relate to a bipolar plate for a fuel cell. Figure 5As shown, the bipolar plate of the fuel cell includes the cathode plate described in any of the aforementioned embodiments; an anode plate fixedly connected to the other side of the cathode plate away from the flow channel 5; a cooling medium channel 8 is provided between the anode plate and the cathode plate, and the cooling medium flows in the cooling medium channel 8. The anode plate in this embodiment may include an anode plate body 1', a flow channel 5' and a ridge 6' similar to the cathode plate. Since water is generated on the cathode side during the electrochemical reaction of the fuel cell, most of the water will pass through the gas diffusion layer of the cathode to reach the flow channel 5 of the cathode plate, and only a small part of the water may pass through the membrane electrode assembly 10 and eventually enter the flow channel 5' of the anode plate. Therefore, in this embodiment, a gasket 7 is not provided in the flow channel 5' of the anode plate.

[0055] Some embodiments of the present application relate to a fuel cell. Figure 6 As shown, a fuel cell single cell includes a cathode plate, a cathode gas diffusion layer 9, a membrane electrode assembly 10, an anode gas diffusion layer 9', and an anode plate stacked in sequence, wherein the cathode plate is the cathode plate described in any of the above embodiments. The membrane electrode assembly 10 includes a proton exchange membrane and catalyst layers respectively attached to both sides of the proton exchange membrane. The anode plate in this embodiment may include an anode plate body 1', a flow channel 5', and a ridge 6' similar to the cathode plate, but does not have a gasket 7.

[0056] Furthermore, some embodiments of the present application relate to a fuel cell, comprising a plurality of fuel cell cells as described in any of the preceding embodiments.

[0057] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the detailed description of other embodiments above, and will not be repeated here.

[0058] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0059] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this application, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0060] It should be noted that similar reference numerals and letters denote similar items in the drawings of the present application, and therefore, once an item is defined in one drawing, it does not require further definition and explanation in subsequent drawings.

[0061] In the description of this application, it should be noted that if the terms "center", "upper", "lower", "left", "right", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the product of the application is usually placed when in use. It is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, if the terms "first", "second", etc. appear in the description of this application, they are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0062] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0063] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this application is hereby incorporated by reference in its entirety, except for application history documents that are inconsistent with or conflicting with the content of this application, and documents that limit the broadest scope of the claims of this application (currently or later attached to this application). It should be noted that if the descriptions, definitions, and / or use of terms in the accompanying materials of this application are inconsistent or conflicting with the content described in this application, the descriptions, definitions, and / or use of terms in this application shall prevail.

Claims

1. A fuel cell cathode plate, characterized in that: It includes a metal cathode plate body and a gasket; One side of the cathode plate body comprises: Air inlet and outlet; A plurality of flow channels communicating the air inlet and the air outlet, including an opening toward a membrane electrode of the fuel cell; At least one of the flow channels is provided with the gasket at the bottom near one end of the air outlet; The other side of the cathode plate body is used to contact with the cooling medium, and the thermal conductivity of the gasket material is smaller than the thermal conductivity of the cathode plate body; The gasket material is rubber; The length of the gasket accounts for 1 / 5-1 / 2 of the length of the flow channel; The maximum height of the gasket is H, the depth of the flow channel is D, and H and D meet the following conditions: 0.5D<H<0.8D.

2. The cathode plate according to claim 1, characterized in that The cathode plate body is formed by stamping, and the gasket is fixed in the flow channel by injection molding or bonding.

3. The cathode plate according to claim 1, characterized in that The gasket is a flat gasket with a fixed height; The length of the planar gasket is 1 / 5-1 / 4 of the length of the flow channel.

4. The cathode plate according to claim 1, characterized in that The gasket is a wedge-shaped gasket, and the height thereof gradually increases toward the air outlet; The length of the wedge-shaped gasket is 1 / 4-1 / 2 of the length of the flow channel.

5. The cathode plate according to claim 1, characterized in that: The gasket is a multi-step gasket, and the step heights gradually increase toward the air outlet; The length of the multi-step gasket is 1 / 5-2 / 5 of the length of the flow channel.

6. A fuel cell bipolar plate, characterized in that: include: The cathode plate according to any one of claims 1 to 5; an anode plate, fixedly connected to the other side of the cathode plate away from the flow channel; A cooling medium channel is provided between the anode plate and the cathode plate, and the cooling medium flows in the cooling medium channel.

7. A fuel cell cell, characterized in that: Comprising the cathode plate as described in any one of claims 1-5.

8. A fuel cell, characterized in that: It comprises a plurality of fuel cell cells as claimed in claim 7.

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