Flow field plate and fuel cell

Abstract

The invention provides a flow field plate and a fuel cell comprising the same, and relates to the technical field of cells, a flow field structure is designed in the flow field plate, the flow field structure is divided into a main flow channel and two graded flow fields which are communicated with each other, and each graded flow field is divided into a first flow field area, a redistribution flow field area and a second flow field area; wherein a part of reaction gas can be shunted from the main flow channel, flows into the grading flow field and roughly flows along the arrangement direction of the first flow field area, the redistribution flow field area and the second flow field area, and in the process, the reaction gas can be distributed again after being mixed for multiple times through the structural design of the redistribution flow field area; and the uniformity of reaction gas in the flow field can be improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a flow field plate and a fuel cell. Background Technology

[0002] A fuel cell is an electrochemical reaction device that can directly convert the chemical energy of fuel into electrical energy. Due to its clean, efficient and continuous operation characteristics, fuel cells have received increasing attention today as research and development of clean energy become more and more important.

[0003] The development of fuel cell technology must consider multiple design factors simultaneously. For example, improving the uniformity of the reactant gas in the flow field is an important research direction in the field of battery technology.

[0004] The above statements are for the purpose of providing background information in relation to this application only and do not necessarily constitute prior art. Summary of the Invention

[0005] In view of the above problems, embodiments of this application provide a flow field plate and a fuel cell, which can improve the problem of uneven distribution of reactant gases in the flow field of the fuel cell.

[0006] In a first aspect, embodiments of this application provide a flow field plate suitable for fuel cells, the flow field plate comprising: The plate has a plate surface perpendicular to the thickness direction of the plate, and a flow field structure is provided on the plate surface; The air inlet is connected to the flow field structure and is configured to guide the reactive gas into the flow field structure. The outlet is connected to the flow field structure and is configured to guide the reactant gas out of the flow field structure. The flow field structure includes: The main air duct extends along the first direction and is located between the air inlet and the air outlet; Two graded flow fields are distributed on both sides of the main flow channel along the second direction. The second direction, the first direction, and the thickness direction of the plate are perpendicular to each other. The graded flow field is divided into a first flow field region, a redistributed flow field region, and a second flow field region, which are distributed sequentially along the second direction. Among them, the first flow field area is closer to the main flow channel than the second flow field area, and both the first flow field area and the second flow field area are equipped with interconnected and intersecting first branch flow channels and second branch flow channels. At least a portion of the first branch flow channel within the first flow field region is connected between the main flow channel and the redistribution flow field region, so that the reactant gas can enter the redistribution flow field region from the main flow channel via the first flow field region. The redistribution flow field region is configured to mix the reactant gas flowing out of the first flow field region and guide a portion of the reactant gas from the first flow field region into the second flow field region; At least a portion of the first branch flow channel within the second flow field region is connected to the redistribution flow field region, enabling the reactant gas to enter the second flow field region from the redistribution flow field region.

[0007] In some embodiments, a plurality of staggered protruding baffles are provided in the redistribution flow field region. The protruding baffles are configured to divert the reaction gas flowing out of the first flow field region and guide a portion of the reaction gas into the second flow field region.

[0008] In some embodiments, the size of the redistributed flow field region in the second direction is W1, where W1 satisfies: 4 mm ≤ W1 ≤ 25 mm.

[0009] In some embodiments, a plurality of raised baffles are provided in the main flow channel, distributed along a first direction. The raised baffles are configured to divert the reaction gas entering from the air inlet and guide a portion of the reaction gas into the first flow field region.

[0010] In some embodiments, the main channel satisfies at least one of the following conditions: The main channel has a dimension of W2 in the second direction, which satisfies: 2 mm ≤ W2 ≤ 5 mm; The dimension of the main channel in the thickness direction of the plate is D1, and D1 satisfies: 0.3 mm ≤ D1 ≤ 1 mm.

[0011] In some embodiments, the first branch channel satisfies at least one of the following conditions: The angle between the extension direction of the first branch channel and the extension direction of the main channel is α, and α satisfies: 30°≤α≤90°; The dimension of the first branch flow channel in the third direction is W3, and W3 satisfies: 0.4 mm ≤ W3 ≤ 3 mm. The extension direction of the third direction, the extension direction of the first branch flow channel, and the thickness direction of the plate are perpendicular to each other. The number of first branch channels is multiple, and the multiple first branch channels are arranged along the third direction. The extension length of the first branch channel is L1, and L1 satisfies: 2 mm ≤ L1 ≤ 50 mm. The third direction, the extension direction of the first branch channel and the thickness direction of the plate are perpendicular to each other. The dimension of the first branch channel in the thickness direction of the plate is D2, and D2 satisfies: 0.3 mm ≤ D2 ≤ 1 mm.

[0012] In some embodiments, the second branch channel satisfies at least one of the following conditions: The angle between the extension direction of the second branch channel and the extension direction of the first branch channel is β, and β satisfies: 10°≤β≤80°; The dimension of the second branch channel in the fourth direction is W4, which satisfies: 0.2 mm ≤ W4 ≤ 2 mm. The fourth direction, the extension direction of the second branch channel, and the thickness direction of the plate are perpendicular to each other. There are multiple second branch channels, which are arranged along the fourth direction. The extension length of the second branch channel is L2, which satisfies: 2 mm ≤ L2 ≤ 45 mm. The fourth direction, the extension direction of the second branch channel, and the thickness direction of the plate are perpendicular to each other. The second branch channel has a dimension D3 in the thickness direction of the plate, and D3 satisfies: 0.3 mm ≤ D3 ≤ 1 mm.

[0013] In some embodiments, a third branch flow channel is provided inside the first flow field region and / or the second flow field region, and one end of the third branch flow channel is connected to the second branch flow channel; The third branch flow channel satisfies at least one of the following conditions: The angle between the extension direction of the third branch channel and the extension direction of the second branch channel is θ, and θ satisfies: 30°≤θ≤90°; The dimension of the third branch channel in the fifth direction is W5, which satisfies: 0.2 mm ≤ W5 ≤ 1 mm. The fifth direction, the extension direction of the third branch channel, and the thickness direction of the plate are perpendicular to each other. There are multiple third branch channels, which are arranged along the fifth direction. The extension length of the third branch channel is L3, which satisfies: 2 mm ≤ L3 ≤ 10 mm. The fifth direction, the extension direction of the third branch channel, and the thickness direction of the plate are perpendicular to each other. The dimension of the third branch channel in the thickness direction of the plate is D4, and D4 satisfies: 0.3 mm ≤ D4 ≤ 1 mm.

[0014] In some embodiments, the other end of the third branch channel extends to the first branch channel, so that the other end of the third branch channel is directly connected to the first branch channel; or, the other end of the third branch channel is a closed end that is not directly connected to the first branch channel.

[0015] In some embodiments, when the other end of the third branch channel is a closed end that is not directly connected to the first branch channel, the orthographic projection of the other end of the third branch channel on the plane of the plate surface is dovetail-shaped.

[0016] In some embodiments, the flow field structure satisfies at least one of the following conditions: The dimension of the main channel in the second direction is W2, and the dimension of the main channel in the thickness direction of the plate is D1. W2 and D1 satisfy: 0.5≤W2 / D1≤2; The dimension of the first branch channel in the third direction is W3. The third direction, the extension direction of the first branch channel, and the thickness direction of the plate are perpendicular to each other. The dimension of the first branch channel in the thickness direction of the plate is D2. W3 and D2 satisfy: 0.5≤W3 / D2≤2. The dimension of the second branch channel in the fourth direction is W4. The fourth direction, the extension direction of the second branch channel, and the thickness direction of the plate are perpendicular to each other. The dimension of the second branch channel in the thickness direction of the plate is D3. W4 and D3 satisfy: 0.5≤W4 / D3≤2. A third branch flow channel is provided inside the first flow field region and / or the second flow field region. One end of the third branch flow channel is connected to the second branch flow channel. The dimension of the third branch flow channel in the fifth direction is W5. The fifth direction, the extension direction of the third branch flow channel and the thickness direction of the plate are perpendicular to each other. The dimension of the third branch flow channel in the thickness direction of the plate is D4. W5 and D4 satisfy: 0.5≤W5 / D4≤2.

[0017] In some embodiments, the flow field structure further includes two side channels, which surround the outer periphery of the flow field structure. One end of the side channel is connected to the air inlet, and the other end is connected to the air outlet; The side channel is also connected to at least one of the first branch channel, the second branch channel, and the redistributed flow field region.

[0018] In some embodiments, the side channel includes a diverging section and a collecting section connected end to end; The end of the diverging section furthest from the collecting section is connected to the air inlet. The diverging section is also connected to the second branch flow channel and the redistribution flow field region. The end of the collecting section away from the diverging section is connected to the air outlet. The collecting section is also connected to the first branch flow channel and the redistribution flow field region.

[0019] In some embodiments, the side channel satisfies at least one of the following conditions: The dimension of the diverging segment in the sixth direction is W6. The sixth direction, the extension direction of the diverging segment, and the thickness direction of the plate are perpendicular to each other. The dimension of the diverging segment in the thickness direction of the plate is D5. W6 and D5 satisfy: 0.5≤W6 / D5≤2. The size of the collecting segment in the seventh direction is W7. The seventh direction, the extension direction of the collecting segment, and the thickness direction of the plate are perpendicular to each other. The size of the collecting segment in the thickness direction of the plate is D6. W7 and D6 satisfy: 0.5≤W7 / D6≤2.

[0020] In some embodiments, the air inlet is positioned lower than the air outlet, and the air inlet and air outlet are offset in the top and bottom direction of the plate.

[0021] In the above technical solution, by setting a main flow channel between the inlet and outlet, the reactant gas can flow from the inlet to the outlet through the main flow channel. Furthermore, since two staged flow fields are set on both sides of the main flow channel, and a first branch flow field and a second branch flow field connected to the main flow channel are set within each staged flow field, the reactant gas flowing through the main flow channel can diffuse into the two staged flow fields, thereby improving the uniformity of the reactant gas within the flow fields. Moreover, the staged flow fields are divided into a first flow field region, a redistribution flow field region, and a second flow field region arranged sequentially. The first flow field region is close to the main flow channel, allowing the reactant gas to first enter the first flow field region and then enter the second flow field region through the redistribution flow field region. The reactant gas can be mixed in the redistribution flow field region, and a portion of the reactant gas can flow into the second flow field region under the guidance of the redistribution flow field region. During this process, the structural design of the redistribution flow field region allows the reactant gas to be mixed multiple times and then redistributed, further improving the uniformity of the reactant gas within the flow fields.

[0022] Secondly, embodiments of this application also provide a fuel cell, including the flow field plate of any of the first aspects and a plurality of stacked membrane electrode assemblies; The flow field plate is positioned between two adjacent membrane electrode assemblies, and the thickness direction of the flow field plate is consistent with the stacking direction of the multiple membrane electrode assemblies.

[0023] In the above technical solution, the fuel cell includes the flow field plate of any one of the first aspects, and has the same technical effect as the flow field plate of any one of the first aspects; that is, the uniformity of the reactant gas in the flow field of the fuel cell is improved, which has a good effect on improving the working efficiency and service life of the fuel cell. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a three-dimensional structural schematic diagram of a flow field plate provided according to some embodiments of this application; Figure 2 This is a schematic front view of a flow field plate according to some embodiments of this application, showing one layout of the flow field structure; Figure 3 This is a schematic diagram of the main structure of a flow field plate according to some embodiments of this application, showing a layout of the main flow channel and two graded flow fields; Figure 4This is a schematic diagram of the main structure of a flow field plate according to some embodiments of this application, which shows a layout in which a graded flow field is divided into a first flow field region, a redistributed flow field region, and a second flow field region; Figure 5 This is a schematic diagram of the main structure of a flow field plate according to some embodiments of the present application, which shows a layout in which a first branch flow channel and a second branch flow channel are provided in a first flow field region and a second flow field region; Figure 6 This is a front view of a flow field plate provided according to some embodiments of this application, showing a layout of the redistributed flow field region and its internal protruding blocks; Figure 7 This is a three-dimensional structural schematic diagram of a protruding stop provided according to some embodiments of this application; Figure 8 This is a front view of a flow field plate provided according to some embodiments of this application, showing a layout of the main flow channel and its internal protruding blocks; Figure 9 This is a schematic diagram of the main structure of a flow field plate according to some embodiments of the present application, which shows a layout between the first branch flow channel and the main flow channel in the first flow field region; Figure 10 This is a schematic diagram of the main structure of a flow field plate according to some embodiments of the present application, which shows a layout between the second branch flow channel and the first branch flow channel in the first flow field region; Figure 11 for Figure 10 A magnified schematic diagram of part A in the middle shows a layout between the third branch channel and the second branch channel in the first flow field region; Figure 12 This is a schematic diagram of the main structure of a flow field plate according to some embodiments of this application, showing one layout of two side flow channels; Figure 13 This is a schematic diagram of the main structure of a flow field plate according to some embodiments of this application, which shows one layout of the first side flow channel; Figure 14 This is a front view of a flow field plate provided according to some embodiments of this application, showing one layout of the second side flow channel.

[0026] The attached figures are labeled as follows: 1-Plate body, 11-Plate surface; 2-Air intake; 3-Air outlet; 4-Flow field structure, 41-Main flow channel, 42-Graded flow field, 421-First flow field region, 422-Redistributed flow field region, 423-Second flow field region, 424-First branch flow channel, 425-Second branch flow channel, 426-Third branch flow channel, 43-Protruding baffle, 431-Front end, 432-Rear end, 433-Side plate, 44-First side flow channel, 441-First divergence section, 442-First collection section, 45-Second side flow channel, 451-Second divergence section, 452-Second collection section; X - Left and right direction of the plate, Y - Top and bottom direction of the plate, Z - Thickness direction of the plate. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] Unless otherwise defined, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the embodiments of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising" and "having" and any variations thereof in the specification and the foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0029] The term "embodiment" as used in this application means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0030] The specific term "exemplary" used in the embodiments of this application means "serving as an example, embodiment, or illustration." Any embodiment illustrated as "exemplary" is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0031] In the description of the embodiments of this application, the technical terms "first", "second", "third", etc. are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0032] In the description of the embodiments in this application, the technical term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects are in an "or" relationship.

[0033] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms "installation," "connection," "joining," "fixing," etc., should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can refer to a mechanical connection or an electrical connection; it can refer to a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0034] In the description of the embodiments of this application, the technical terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of the embodiments of this application. They are only used to facilitate the description of the embodiments of this application and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0035] In the description of the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of the embodiments of this application, "parallel" includes not only the case of absolute parallelism, but also the case of approximate parallelism as commonly understood in engineering; at the same time, "perpendicular" also includes not only the case of absolute perpendicularity, but also the case of approximate perpendicularity as commonly understood in engineering.

[0037] In the description of the embodiments of this application, "multiple" means two or more (including two), unless otherwise explicitly specified.

[0038] In the description of the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, and other dimensions of various components in the embodiments of this application shown in the drawings, as well as the overall thickness, length, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0039] As part of the inventive concept of this application, before describing the embodiments of this application, it is necessary to analyze the reasons for the uneven distribution of reactant gases in fuel cells in related technologies, and obtain the technical solutions of the embodiments of this application through reasonable analysis.

[0040] Among related technologies, fuel cells are electrochemical reaction devices that can directly convert the chemical energy of fuel into electrical energy. Due to their cleanliness, high efficiency, and continuous operation, fuel cells have received increasing attention today as research and development of clean energy become more and more important.

[0041] Fuel cells can be classified into various types based on differences in electrolyte type, operating temperature, and fuel type. For example, according to electrolyte type, fuel cells can be divided into: proton exchange membrane fuel cells (PEMFC), alkaline fuel cells (AFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), and solid oxide fuel cells (SOFC). Among these, PEMFC can be further divided into high-temperature PEMFC and low-temperature PEMFC.

[0042] High-temperature proton exchange membrane fuel cells typically operate at temperatures between 120 and 200°C, can tolerate small amounts of CO (1%-5%), and feature fast start-up and high power density. They can be widely used in electric vehicles, portable power supplies, distributed power generation equipment, and other fields.

[0043] The core component of a high-temperature proton exchange membrane fuel cell is the single-cell structure, which is the basic unit that constitutes the fuel cell stack. The single-cell structure mainly includes three core parts arranged from the inside out: the membrane electrode assembly (MEA), the flow field plate (also known as the bipolar plate), and the sealing components.

[0044] Regarding the membrane electrode assembly (MEA), it is the core region of the electrochemical reaction, where fuel (such as hydrogen) oxidation and oxidant (such as oxygen) reduction occur. It is composed of a proton exchange membrane (high-temperature proton conduction membrane), a catalyst layer, and a gas diffusion layer (GDL) tightly bonded together. Specifically, the catalyst layer includes an anode catalyst layer and a cathode catalyst layer, respectively disposed on opposite sides of the proton exchange membrane. The gas diffusion layer includes an anode gas diffusion layer and a cathode gas diffusion layer. The anode gas diffusion layer is located on the side of the anode catalyst layer furthest from the proton exchange membrane, and the cathode gas diffusion layer is located on the side of the cathode catalyst layer furthest from the proton exchange membrane. The performance of the MEA directly determines the power density and stability of the battery. The main function of the proton exchange membrane is to conduct protons at high temperatures (…). The catalyst layer separates the fuel and oxidant, while possessing a certain degree of mechanical strength and chemical stability. Its main function is to catalyze the fuel oxidation and oxidant reduction reactions (anode: ;cathode: The main functions of the gas diffusion layer are to support the catalyst layer, conduct electrons, uniformly distribute reactants (hydrogen and oxygen), and remove reaction products (a small amount of water).

[0045] Regarding flow field plates, they play a role in separating reactants, conducting electrons, distributing fluids, and supporting structures in single-cell stacks. For high-temperature proton exchange membrane fuel cells, the reaction rate is fast and the mass transfer requirements of reactants are higher. The flow field design needs to take into account both "uniform distribution" and "low pressure drop".

[0046] Regarding seals, their main function is to prevent the leakage and mixing of reactants (hydrogen, oxygen) while also preventing coolant (if any) from leaking.

[0047] As shown above, the flow field plate is one of the key components in a fuel cell, undertaking multiple functions such as gas distribution, heat transfer, mechanical support, and drainage. The flow channel structure of the flow field plate is a crucial factor affecting its performance, with basic flow fields including parallel flow fields and serpentine flow fields. Traditional parallel flow fields have relatively small pressure drops and numerous branch channels, affecting the uniformity of reactant gases within the flow field; traditional serpentine flow fields are relatively simple to manufacture and have larger pressure drops, but they also suffer from uneven distribution of reactant gases along the gas flow direction. Therefore, improving the uniformity of reactant gases (reactants, fuel, or oxidant) within the flow field is an important research direction in the field of battery technology.

[0048] In view of this, in order to improve the problem of uneven distribution of reactant gas in fuel cells, embodiments of this application provide a flow field plate with a flow field structure designed in the flow field plate, which is divided into a main flow channel and two graded flow fields. The graded flow fields are further divided into a first flow field region, a redistribution flow field region, and a second flow field region. A portion of the reactant gas can be diverted from the main flow channel and flow into the graded flow fields, and flows roughly along the arrangement direction of the first flow field region, the redistribution flow field region, and the second flow field region. In this process, through the structural design of the redistribution flow field region, the reactant gas can be mixed and redistributed multiple times, which can improve the uniformity of the reactant gas in the flow field.

[0049] The technical solutions provided in this application are applicable to fuel cells, which can be high-temperature proton exchange membrane fuel cells, low-temperature proton exchange membrane fuel cells, etc. For ease of description of the following embodiments, this document uses a high-temperature proton exchange membrane fuel cell as an example.

[0050] The technical solutions of the embodiments of this application are described in detail below with reference to the accompanying drawings. The technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0051] Please refer to Figure 1 and Figure 2 This application provides a flow field plate suitable for fuel cells. The flow field plate includes a plate body 1, an air inlet 2, and an air outlet 3. The plate body 1 has a plate surface 11 perpendicular to the thickness direction Z of the plate body, and a flow field structure 4 is disposed on the plate surface 11. The air inlet 2 is connected to the flow field structure 4 and is configured to guide the reactant gas into the flow field structure 4. The air outlet 3 is connected to the flow field structure 4 and is configured to guide the reactant gas out of the flow field structure 4.

[0052] Optionally, the plate 1 is generally rectangular; of course, the plate 1 can also be circular or other plate-shaped structures. The structural design can be adapted to the structural shape of the applicable fuel cell, and there are no restrictions here.

[0053] Optionally, the area occupied by the flow field structure 4 on the plate surface 11 is approximately rectangular; of course, this area can also be circular or other shapes, and a structural design adapted to the structural shape of the applicable fuel cell can be adopted, which is not limited here. However, for ease of description, this article uses the example of the area occupied by the flow field structure 4 on the plate surface 11 being approximately rectangular.

[0054] It should be noted that the flow field structure 4 is provided with a flow channel, and the flow channel is connected to the gas diffusion layer of the membrane electrode assembly. The reaction gas flowing in from the inlet 2 flows in the flow channel of the flow field structure 4 and can diffuse through the gas diffusion layer to the catalytic layer of the membrane electrode assembly. The catalytic layer can catalyze the reaction gas to carry out oxidation and reduction reactions.

[0055] It should be further explained that, in the thickness direction Z perpendicular to the plate body, the plate body 1 of the flow field plate has two plate surfaces 11, which are the anode plate surface and the cathode plate surface, respectively. When the flow field plate is assembled in the fuel cell, the anode plate surface of the flow field plate body 1 is located on the side of the anode gas diffusion layer of the membrane electrode assembly away from the anode catalyst layer, and the cathode plate surface is located on the side of the cathode gas diffusion layer away from the cathode catalyst layer.

[0056] Based on this, a flow field structure 4 can be provided on the anode plate surface of plate 1; or, a flow field structure 4 can be provided on the cathode plate surface of plate 1; or, a flow field structure 4 can be provided on both the anode plate surface and the cathode plate surface of plate 1. However, it should be noted that, since different reaction gases (e.g., hydrogen and oxygen) flowing into the anode side and the cathode side need to be separated in a fuel cell, the flow field structure 4 located on the anode plate surface and the flow field structure 4 located on the cathode plate surface are not connected. The flow field structure 4 located on the anode plate surface needs to be equipped with an inlet 2 and an outlet 3 corresponding to the flow field structure 4 to facilitate the entry and exit of hydrogen, and the flow field structure 4 located on the cathode plate surface needs to be equipped with an inlet 2 and an outlet 3 corresponding to the flow field structure 4 to facilitate the entry and exit of oxygen.

[0057] Optionally, the air inlet 2 and / or the air outlet 3 are circular holes; of course, the air inlet 2 and / or the air outlet 3 can also be square, regular polygonal, or other shapes, which are not limited here.

[0058] Optionally, since the flow field structure 4 is roughly rectangular, the air inlet 2 and the air outlet 3 are arranged along the diagonal of the flow field structure 4 at the two apex positions of the flow field structure 4.

[0059] Optionally, the position of the air inlet 2 is lower than that of the air outlet 3, and the air inlet 2 and the air outlet 3 are offset in the top-bottom direction Y of the plate. This structural design allows the reactant gas to automatically diffuse from the flow field structure 4 to the upper part of the flow field structure 4, and under the guidance of the flow channels within the flow field structure 4, it can automatically diffuse from one side of the flow field structure 4 to the other side of the flow field structure 4. This allows the reactant gas to diffuse comprehensively within the flow field structure 4, which helps to improve the uniform distribution of the reactant gas within the flow field structure 4.

[0060] Furthermore, such as Figure 3 As shown, the flow field structure 4 includes a main flow channel 41 and two graded flow fields 42. The main flow channel 41 extends along the first direction and is located between the air inlet 2 and the air outlet 3. The two graded flow fields 42 are distributed on both sides of the main flow channel 41 along the second direction. The second direction, the first direction and the thickness direction Z of the plate are perpendicular to each other.

[0061] Optionally, the main flow channel 41 and the two graded flow fields 42 together form a roughly rectangular flow field structure 4.

[0062] Optionally, the main flow channel 41 is a straight flow channel, and the extension direction of the main flow channel 41 is parallel to the line connecting the air inlet 2 and the air outlet 3. It can also be understood that the first direction is parallel to the diagonal of the flow field structure 4.

[0063] Optionally, the two graded flow fields 42 are symmetrically arranged about the extension direction of the main flow channel 41.

[0064] Optionally, the graded flow field 42 is roughly triangular in structure.

[0065] In the above technical solution, by setting a main flow channel 41 between the inlet 2 and the outlet 3, the reactant gas can flow from the inlet 2 to the outlet 3 through the main flow channel 41. Furthermore, since two graded flow fields 42 are set on both sides of the main flow channel 41, and a first branch flow field 424 and a second branch flow field 425 connected to the main flow channel 41 are set in the graded flow field 42, the reactant gas flowing through the main flow channel 41 can diffuse into the two graded flow fields 42, thereby improving the uniformity of the reactant gas in the flow field.

[0066] Furthermore, such as Figure 4 and Figure 5 As shown, the graded flow field 42 is divided into a first flow field region 421, a redistribution flow field region 422, and a second flow field region 423, which are distributed sequentially along the second direction. The first flow field region 421 is closer to the main flow channel 41 than the second flow field region 423, and both the first flow field region 421 and the second flow field region 423 are provided with interconnected and intersecting first branch flow channels 424 and second branch flow channels 425.

[0067] In this configuration, at least a portion of the first branch flow channel 424 within the first flow field region 421 is connected between the main flow channel 41 and the redistribution flow field region 422, allowing the reactant gas to enter the redistribution flow field region 422 from the main flow channel 41 via the first flow field region 421. The redistribution flow field region 422 is configured to mix the reactant gas flowing out of the first flow field region 421 and guide a portion of the reactant gas from the first flow field region 421 into the second flow field region 423. At least a portion of the first branch flow channel 424 within the second flow field region 423 is connected to the redistribution flow field region 422, allowing the reactant gas to enter the second flow field region 423 from the redistribution flow field region 422.

[0068] Optionally, the first branch flow channel 424 and the second branch flow channel 425 are straight flow channels.

[0069] Optionally, there are multiple first branch channels 424 and multiple second branch channels 425. The multiple first branch channels 424 and multiple second branch channels 425 are arranged intersectingly in the first flow field region 421 and the second flow field region 423, so that the reactant gas can be more evenly distributed in the first flow field region 421 and the second flow field region 423 through the first branch channels 424 and the second branch channels 425.

[0070] Optionally, the first flow field region 421 and the redistribution flow field region 422 are roughly trapezoidal in shape, and the second flow field region 423 is roughly triangular in shape.

[0071] Optionally, the first flow field region 421 is connected to the redistributed flow field region 422 through the first branch flow channel 424 therein, and the second flow field region 423 is connected to the redistributed flow field region 422 through the first branch flow channel 424 therein.

[0072] It should be noted that there are two staged flow fields 42. Each staged flow field 42 can be divided into a first flow field region 421, a redistribution flow field region 422, and a second flow field region 423, or only one of the staged flow fields 42 can be divided into a first flow field region 421, a redistribution flow field region 422, and a second flow field region 423. This is not a limitation. Of course, in order to improve the uniformity of the distribution of reactant gases in the flow field, both staged flow fields 42 adopt the scheme of dividing into a first flow field region 421, a redistribution flow field region 422, and a second flow field region 423. For ease of description, this scheme will be used as an example in this paper.

[0073] In the above technical solution, the graded flow field 42 is divided into a first flow field region 421, a redistribution flow field region 422, and a second flow field region 423 arranged sequentially. The first flow field region 421 is close to the main flow channel 41, so that the reactant gas can first enter the first flow field region 421 and then enter the second flow field region 423 through the redistribution flow field region 422. The reactant gas can be mixed in the redistribution flow field region 422, and a portion of the reactant gas can flow into the second flow field region 423 under the guidance of the redistribution flow field region 422. In this process, through the structural design of the redistribution flow field region 422, the reactant gas can be redistributed after multiple mixing, which can further improve the uniformity of the reactant gas in the flow field and has a good effect on improving the working efficiency and service life of the fuel cell.

[0074] In some embodiments, such as Figure 6 and Figure 7 As shown, multiple staggered protruding blocks 43 are provided in the redistribution flow field region 422. The protruding blocks 43 are configured to divert the reaction gas flowing out of the first flow field region 421 and guide part of the reaction gas into the second flow field region 423.

[0075] Optionally, multiple protruding blocks 43 are arranged in an array within the region of the redistributed flow field region 422.

[0076] Optionally, the orthographic projection of the protruding block 43 onto the plane of the plate 11 resembles a frog's webbed foot; of course, the shape of the orthographic projection of the protruding block 43 onto the plane of the plate 11 can also be a circle, triangle, teardrop, frog's webbed foot, streamline, etc., and is not limited here.

[0077] For example, a specific structure of the protruding stop 43 can be: as follows Figure 7 As shown, the protruding baffle 43 has a front end 431, a rear end 432, and two side plates 433 connecting the front end 431 and the rear end 432; wherein, the width of the front end 431 is smaller than the width of the rear end 432, and the two side plates 433 have a guiding effect on the reactant gas. When the reactant gas flows from the first branch channel 424 in the first flow field region 421 into the redistribution flow field region 422, the reactant gas first reaches the front end 431 of the protruding baffle 43, and then flows in different directions along the two side plates 433. During this process, the reactant gas can be mixed and dispersed again; moreover, by designing the position of the side plates 433, some of the reactant gas can also be guided to flow to the second flow field region 423, and enter the second flow field region 423 through the first branch channel 424 in the second flow field region 423, so that the reactant gas can diffuse in the first branch channel 424 and the second branch channel 425 in the second flow field region 423.

[0078] It should be noted that when a redistribution flow field region 422 is provided in both graded flow fields 42, the arrangement of the protruding baffles 43 in the two redistribution flow field regions 422 is different, so as to facilitate the smooth entry of some of the reacting gases into their respective second flow field regions 423.

[0079] Optionally, the two redistributed flow field regions 422 and the protruding baffles 43 within their respective regions can be symmetrically arranged about the extension direction of the main flow channel 41.

[0080] In the above technical solution, by setting multiple protruding baffles 43 in the redistribution flow field zone 422, the reaction gas can be mixed and redistributed multiple times, so that the reaction gas entering the redistribution flow field zone 422 can be distributed more evenly; at the same time, by utilizing the diversion effect of the protruding baffles 43, some of the reaction gas can also be guided into the second flow field zone 423, so that the reaction gas can diffuse into the entire flow field structure 4, thereby improving the uniformity of the reaction gas in the flow field.

[0081] In some embodiments, such as Figure 6As shown, the size of the redistributed flow field region 422 in the second direction is W1, and W1 satisfies: 4 mm ≤ W1 ≤ 25 mm. The second direction is perpendicular to the extension direction of the main flow channel 41 (i.e., the first direction) and the thickness direction Z of the plate.

[0082] In the above technical solution, by limiting the size of the redistribution flow field region 422 in the second direction, the redistribution flow field region 422 has a suitable area, which helps to improve the mixing efficiency of the reactant gas in this region, and can also guide an appropriate amount of reactant gas into the second flow field region 423.

[0083] In some embodiments, such as Figure 8 As shown, a plurality of raised baffles 43 are provided in the main flow channel 41, distributed along a first direction. The raised baffles 43 are configured to divert the reactant gas entering from the air inlet 2 and guide a portion of the reactant gas into the first flow field region 421. The first direction is the extension direction of the main flow channel 41.

[0084] It should be noted that the structure and shape of the protruding baffle 43 in the main flow channel 41 can be similar to that of the protruding baffle 43 in the redistribution flow field region 422, and will not be described in detail here.

[0085] Optionally, multiple raised blocks 43 within the main channel 41 are arranged in a line along the first direction.

[0086] In the above technical solution, by setting multiple protruding baffles 43 in the main channel 41, part of the reactant gas flowing through the main channel 41 can be guided to the two graded flow fields 42 on both sides of the main channel 41. Under the diversion effect of the protruding baffles 43, part of the reactant gas can enter the two first flow field regions 421 along the first branch flow channel 424 connected to the main channel 41, so that the reactant gas can diffuse rapidly on both sides of the main channel 41, which can improve the uniformity of gas distribution in the flow field.

[0087] In some embodiments, such as Figure 8 As shown, the main channel 41 satisfies at least one of the following conditions: 1. The dimension of the main channel 41 in the second direction (which can be understood as the slot width of the main channel 41) is W2, and W2 satisfies: 2 mm ≤ W2 ≤ 5 mm; 2. The dimension of the main channel 41 in the thickness direction Z of the plate (which can be understood as the groove depth of the main channel 41) is D1, and D1 satisfies: 0.3 mm ≤ D1 ≤ 1 mm.

[0088] Optionally, the dimensions W2 of the main channel 41 in the second direction and the dimensions D1 of the main channel 41 in the thickness direction Z of the plate satisfy: 0.5≤W2 / D1≤2.

[0089] Optionally, the dimension W2 of the main channel 41 in the thickness direction Z of the plate can be determined based on the number of first branch channels 424 connected to the main channel 41. The two can be positively correlated, that is, the more first branch channels 424 connected to the main channel 41, the larger the dimension W2 of the main channel 41 in the thickness direction Z of the plate.

[0090] In the above technical solution, by limiting the width of the main channel 41, a suitable width is achieved. This allows the reactant gas flowing within the main channel 41 to diffuse sufficiently and smoothly to the corresponding gas diffusion layer. Furthermore, it facilitates the arrangement of the protruding baffles 43 within the main channel 41 and the flow and diversion of the reactant gas within it. By limiting the depth of the main channel 41, the impact on the overall strength of the flow field plate due to excessive depth is reduced. Additionally, an appropriate width is achieved, ensuring a suitable flow area for the main channel 41. This allows for the passage of a suitable amount of reactant gas within the main channel 41, ensuring high flowability and increasing the diffusion rate of the reactant gas, thereby contributing to improved uniformity of gas distribution.

[0091] In some embodiments, such as Figure 9 As shown, the first branch channel 424 satisfies at least one of the following conditions: 1. The angle between the extension direction of the first branch channel 424 and the extension direction of the main channel 41 is α, and α satisfies: 30°≤α≤90°; 2. The dimension of the first branch flow channel 424 in the third direction (which can be understood as the groove width of the first branch flow channel 424) is W3, and W3 satisfies: 0.4 mm ≤ W3 ≤ 3 mm. The third direction, the extension direction of the first branch flow channel 424 and the thickness direction Z of the plate are perpendicular to each other. 3. There are multiple first branch channels 424, and the multiple first branch channels 424 are arranged along the third direction. The extension length of the first branch channel 424 is L1, and L1 satisfies: 2 mm ≤ L1 ≤ 50 mm. The third direction, the extension direction of the first branch channel 424 and the thickness direction Z of the plate are perpendicular to each other. 4. The dimension of the first branch channel 424 in the thickness direction Z of the plate (which can be understood as the groove depth of the first branch channel 424) is D2, and D2 satisfies: 0.3 mm ≤ D2 ≤ 1 mm.

[0092] Optionally, the dimension of the first branch channel 424 in the third direction is W3 and the dimension of the first branch channel 424 in the thickness direction Z of the plate is D2, which satisfies: 0.5≤W3 / D2≤2.

[0093] Optionally, the dimension W3 of the first branch channel 424 in the third direction is smaller than the dimension W2 of the main channel 41 in the second direction.

[0094] Optionally, the extension direction of the first branch channel 424 is parallel to the top and bottom direction Y of the plate.

[0095] Optionally, the first branch flow channel 424 may be a first branch flow channel 424 within the first flow field region 421 and / or the second flow field region 423.

[0096] In the above technical solution, by limiting the angle α between the first branch channel 424 and the main channel 41 to an acute angle, the resistance to the flowing reactant gas is reduced, which can increase the diffusion rate of the reactant gas and help improve the uniformity of the reactant gas distribution. By limiting the groove width of the first branch channel 424, the first branch channel 424 is given a suitable width, which allows the reactant gas flowing in the first branch channel 424 to diffuse sufficiently and smoothly to the corresponding gas diffusion layer, and facilitates the flow and diversion of the reactant gas in the first branch channel 424. By limiting the extension length of the first branch channel 424, multiple first branch channels 424 at different positions can have different extension lengths, thereby making the layout of the first branch channels 424 in the graded flow field 42 more flexible and allowing the first branch channels 424 to occupy a larger area ratio in the graded flow field 42, which can increase the amount of reactant gas in the flow field structure 4. By limiting the groove depth of the first branch flow channel 424, on the one hand, the impact on the overall strength of the flow field plate due to excessive groove depth of the first branch flow channel 424 can be reduced; on the other hand, an appropriate groove width of the first branch flow channel 424 can be matched so that the first branch flow channel 424 has a suitable flow area, so that an appropriate amount of reactant gas can pass through the first branch flow channel 424 and the reactant gas has high flowability in the first branch flow channel 424, which can improve the diffusion rate of the reactant gas and thus help improve the uniformity of the distribution of the reactant gas.

[0097] In some embodiments, such as Figure 10 As shown, the second branch channel 425 satisfies at least one of the following conditions: 1. The angle between the extension direction of the second branch channel 425 and the extension direction of the first branch channel 424 is β, and β satisfies: 10°≤β≤80°; 2. The dimension of the second branch flow channel 425 in the fourth direction (which can be understood as the groove width of the second branch flow channel 425) is W4, and W4 satisfies: 0.2 mm ≤ W4 ≤ 2 mm. The fourth direction, the extension direction of the second branch flow channel 425 and the thickness direction Z of the plate are perpendicular to each other. 3. There are multiple second branch channels 425, which are arranged along the fourth direction. The extension length of the second branch channel 425 is L2, which satisfies: 2 mm ≤ L2 ≤ 45 mm. The fourth direction, the extension direction of the second branch channel 425 and the thickness direction Z of the plate are perpendicular to each other. 4. The dimension of the second branch channel 425 in the thickness direction Z of the plate (which can be understood as the groove depth of the second branch channel 425) is D3, and D3 satisfies: 0.3 mm ≤ D3 ≤ 1 mm.

[0098] Optionally, the dimension of the second branch channel 425 in the fourth direction is W4 and the dimension of the second branch channel 425 in the thickness direction Z of the plate is D3, satisfying: 0.5≤W4 / D3≤2.

[0099] Optionally, the dimension of the second branch channel 425 in the fourth direction is W4, which is smaller than the dimension of the first branch channel 424 in the third direction is W3.

[0100] Optionally, the extension direction of the second branch channel 425 is parallel to the extension direction of the main channel 41.

[0101] Optionally, the second branch flow channel 425 may be a second branch flow channel 425 within the first flow field region 421 and / or the second flow field region 423.

[0102] In the above technical solution, by limiting the included angle β between the second branch channel 425 and the first branch channel 424 to an acute angle, the resistance to the flowing reactant gas is reduced, which can increase the diffusion rate of the reactant gas and help improve the uniformity of the reactant gas distribution. By limiting the groove width of the second branch channel 425, the second branch channel 425 is given a suitable width, which allows the reactant gas flowing in the second branch channel 425 to diffuse sufficiently and smoothly to the corresponding gas diffusion layer, and facilitates the flow and diversion of the reactant gas in the second branch channel 425. By limiting the extension length of the second branch channel 425, multiple second branch channels 425 at different positions can have different extension lengths, thereby making the layout of the second branch channels 425 in the staged flow field 42 more flexible and allowing the second branch channels 425 to occupy a larger area ratio in the staged flow field 42, which can increase the amount of reactant gas in the flow field structure 4. By limiting the depth of the second branch channel 425, on the one hand, the impact on the overall strength of the flow field plate due to excessive depth of the second branch channel 425 can be reduced; on the other hand, an appropriate groove width of the second branch channel 425 can be matched so that the second branch channel 425 has a suitable flow area, so that an appropriate amount of reactant gas can pass through the second branch channel 425 and the reactant gas has high flowability in the second branch channel 425, which can improve the diffusion rate of the reactant gas and thus help improve the uniformity of the distribution of the reactant gas.

[0103] In some embodiments, such as Figure 11 As shown, a third branch flow channel 426 is provided inside the first flow field region 421 and / or the second flow field region 423, and one end of the third branch flow channel 426 is connected to the second branch flow channel 425; the third branch flow channel 426 satisfies at least one of the following conditions: 1. The angle between the extension direction of the third branch channel 426 and the extension direction of the second branch channel 425 is θ, where θ satisfies: 30°≤θ≤90°; 2. The dimension of the third branch flow channel 426 in the fifth direction (which can be understood as the groove width of the third branch flow channel 426) is W5, and W5 satisfies: 0.2 mm ≤ W5 ≤ 1 mm. The fifth direction, the extension direction of the third branch flow channel 426 and the thickness direction Z of the plate are perpendicular to each other. 3. There are multiple third branch channels 426, which are arranged along the fifth direction. The extension length of the third branch channel 426 is L3, which satisfies: 2 mm ≤ L3 ≤ 10 mm. The fifth direction, the extension direction of the third branch channel 426 and the thickness direction Z of the plate are perpendicular to each other. 4. The dimension of the third branch channel 426 in the thickness direction Z of the plate (which can be understood as the groove depth of the third branch channel 426) is D4, and D4 satisfies: 0.3 mm ≤ D4 ≤ 1 mm.

[0104] Optionally, the dimension of the third branch channel 426 in the fifth direction is W5 and the dimension of the third branch channel 426 in the thickness direction Z of the plate is D4, which satisfies: 0.5≤W5 / D4≤2.

[0105] Optionally, the dimension W5 of the third branch channel 426 in the fifth direction is smaller than the dimension W4 of the second branch channel 425 in the fourth direction.

[0106] Optionally, the extension direction of the third branch channel 426 is parallel to the second direction.

[0107] In the above technical solution, by limiting the angle θ between the third branch channel 426 and the second branch channel 425 to an acute angle, the resistance to the flowing reactant gas is reduced, which can increase the diffusion rate of the reactant gas and help improve the uniformity of the reactant gas distribution. By limiting the groove width of the third branch channel 426, the third branch channel 426 is given a suitable width, which allows the reactant gas flowing in the third branch channel 426 to diffuse sufficiently and smoothly to the corresponding gas diffusion layer, and facilitates the flow and diversion of the reactant gas in the third branch channel 426. By limiting the extension length of the third branch channel 426, multiple third branch channels 426 at different positions can have different extension lengths, which makes the layout of the third branch channels 426 in the graded flow field 42 more flexible and allows the third branch channels 426 to occupy a larger area ratio in the graded flow field 42, thereby increasing the amount of reactant gas in the flow field structure 4. By limiting the depth of the third branch channel 426, on the one hand, the impact on the overall strength of the flow field plate due to excessive depth of the third branch channel 426 can be reduced; on the other hand, an appropriate groove width of the third branch channel 426 can be matched so that the third branch channel 426 has a suitable flow area, so that an appropriate amount of reactant gas can pass through the third branch channel 426 and the reactant gas has high flowability in the third branch channel 426, which can improve the diffusion rate of the reactant gas and thus help improve the uniformity of the distribution of the reactant gas.

[0108] Furthermore, one end of the third branch channel 426 is connected to the second branch channel 425, and the other end of the third branch channel 426 extends to the first branch channel 424, so that the other end of the third branch channel 426 is directly connected to the first branch channel 424. Alternatively, one end of the third branch channel 426 is connected to the second branch channel 425, and the other end of the third branch channel 426 is a closed end that is not directly connected to the first branch channel 424.

[0109] The third branch channel 426 has a closed end design at the other end, which can increase the residence time of the reactant gas in the third branch channel 426, so as to facilitate the contact time between the reactant gas and the corresponding gas diffusion layer, which is beneficial to the transport of the reactant gas in the gas diffusion layer.

[0110] It should be noted that when the third branch channel 426 is not directly connected to the first branch channel 424, the third branch channel 426 can be indirectly connected to the first branch channel 424 through the second branch channel 425.

[0111] Furthermore, when the other end of the third branch channel 426 is a closed end that is not directly connected to the first branch channel 424, the orthographic projection of the other end of the third branch channel 426 onto the plane of the plate surface 11 is dovetail-shaped. This structural design increases the contact area between the reacting gas in the third branch channel 426 and the corresponding gas diffusion layer, thereby increasing gas utilization. Additionally, the dovetail shape increases the bending within the flow field structure 4, which is beneficial for improving the structural strength of the flow field plate.

[0112] In some embodiments, such as Figures 12 to 14 As shown, the flow field structure 4 also includes two side channels, which surround the outer periphery of the flow field structure 4; one end of the side channel is connected to the air inlet 2, and the other end is connected to the air outlet 3; the side channel is also connected to at least one of the first branch channel 424, the second branch channel 425, and the redistributed flow field region 422.

[0113] Optionally, the two side channels can be symmetrically arranged about the extension direction of the main channel 41.

[0114] Furthermore, the side channel includes a diverging section and a collecting section connected end to end; the end of the diverging section away from the collecting section is connected to the air inlet 2, and the diverging section is also connected to the second branch channel 425 and the redistribution flow field region 422 respectively; the end of the collecting section away from the diverging section is connected to the air outlet 3, and the collecting section is also connected to the first branch channel 424 and the redistribution flow field region 422 respectively.

[0115] For example, the two side channels are a first side channel 44 and a second side channel 45. The first side channel 44 includes a first diverging section 441 and a first collecting section 442 connected end to end; the end of the first diverging section 441 away from the first collecting section 442 is connected to the air inlet 2, and the first diverging section 441 is connected to the second branch channel 425 and the redistribution flow field region 422 respectively; the end of the first collecting section 442 away from the first diverging section 441 is connected to the air outlet 3, and the first collecting section 442 is connected to the first branch channel 424 and the redistribution flow field region 422 respectively. The second side channel 45 includes a second diverging section 451 and a second collecting section 452 connected end to end; the end of the second diverging section 451 away from the second collecting section 452 is connected to the air inlet 2, and the second diverging section 451 is connected to the second branch channel 425 and the redistribution flow field region 422 respectively; the end of the second collecting section 452 away from the second diverging section 451 is connected to the air outlet 3, and the second collecting section 452 is connected to the first branch channel 424 and the redistribution flow field region 422 respectively.

[0116] In the above technical solution, by setting a divergence section, the reactant gas entering from the inlet 2 can be diverted along with the main flow channel 41. The diverted reactant gas can enter the first flow field region 421 and the second flow field region 423, as well as the redistribution flow field region 422, through the second branch flow channel 425 connected to the divergence section. It can also mix and redistribute with the reactant gas entering the graded flow field 42 from the main flow channel 41, which helps to improve the uniformity of the reactant gas in the flow field structure 4. By setting a collection section, which is connected to the first branch flow channel 424, the redistribution flow field region 422, and the outlet 3, the reactant gas flowing out of the first flow field region 421 and the second flow field region 423, as well as the reactant gas flowing out of the redistribution flow field region 422, can be collected through the first branch flow channel 424. The collected reactant gas can be guided to the outlet 3 for discharge, so that a complete gas flow circulation path can be formed in the flow field structure 4, which helps to improve the uniformity of the reactant gas in the flow field structure 4.

[0117] Furthermore, such as Figure 13 and Figure 14 As shown, the side flow channel satisfies at least one of the following conditions: 1. The dimension of the diverging segment in the sixth direction (which can be understood as the groove width of the diverging segment) is W6. The sixth direction, the extension direction of the diverging segment, and the thickness direction Z of the plate are perpendicular to each other. The dimension of the diverging segment in the thickness direction Z of the plate (which can be understood as the groove depth of the diverging segment) is D5. W6 and D5 satisfy: 0.5≤W6 / D5≤2. 2. The dimension of the collecting section in the seventh direction (which can be understood as the groove width of the collecting section) is W7. The seventh direction, the extension direction of the collecting section, and the thickness direction Z of the plate are perpendicular to each other. The dimension of the collecting section in the thickness direction Z of the plate (which can be understood as the groove depth of the collecting section) is D6. W7 and D6 satisfy: 0.5≤W7 / D6≤2.

[0118] The diverging segment can be a first diverging segment 441 and / or a second diverging segment 451, and the collecting segment can be a first collecting segment 442 and / or a second collecting segment 452.

[0119] Optionally, in the first side channel 44, both the first diverging section 441 and the first collecting section 442 are straight channels. The extension direction of the first diverging section 441 can be the top-bottom direction Y of the plate, and the extension direction of the first collecting section 442 can be the left-right direction X of the plate.

[0120] Optionally, in the second side channel 45, both the second diverging section 451 and the second collecting section 452 are straight channels. The extension direction of the second diverging section 451 can be the left-right direction X of the plate, and the extension direction of the second collecting section 452 can be the top-bottom direction Y of the plate.

[0121] In the above technical solution, by limiting the width and depth of the diverging section, a suitable flow area can be achieved, allowing an appropriate amount of reactant gas to pass through and ensuring high flowability within the diverging section. This enhances the diffusion rate of the reactant gas and thus contributes to improving the uniformity of its distribution. Similarly, by limiting the width and depth of the collecting section, a suitable flow area can be achieved, allowing an appropriate amount of reactant gas to pass through and ensuring high flowability within the collecting section. This enhances the diffusion rate of the reactant gas and thus contributes to improving the uniformity of its distribution.

[0122] In some embodiments, the cross-sectional shape of the flow channels (including the main flow channel 41, the first branch flow channel 424, the second branch flow channel 425, the third branch flow channel 426, and the side flow channels) within the flow field structure 4 can be square, trapezoidal, arc-shaped, etc., and is not limited herein.

[0123] Based on the technical solutions disclosed in the embodiments above, the working principle is as follows: After the reactant gas is introduced from the inlet 2, it flows along the main flow channel 41. During the flow, due to the turbulence effect of the protruding baffle 43 in the main flow channel 41, the reactant gas is directed to the first branch flow channel 424 near the inlet 2 in the first flow field region 421. Some of the reactant gas continues to move forward along the main flow channel 41 and gradually disperses into other first branch flow channels 424 in the subsequent region. Part of the reactant gas entering the first branch channel 424 within the first flow field region 421 is guided by the second branch channel 425 and orderly transported to the third branch channel 426. Another portion of the reactant gas reaches the redistribution flow field region 422 through the first branch channel 424 within the first flow field region 421. There, the secondary mixing and redistribution of the reactant gas is achieved by the staggered arrangement of protruding baffles 43 within this region, which guides the reactant gas into the second flow field region 423. The reactant gas then diffuses within the second flow field region 423 through the first branch channel 424, the second branch channel 425, and the third branch channel 426. Simultaneously, some of the reactant gas introduced from the inlet 2 can also enter the two staged flow fields 42 through the divergence section in the side channel. Ultimately, the reactant gases flowing out of the two graded flow fields 42 can be collected in the collection section of the side flow channel and the remaining reactant gases in the main flow channel 41. After unified guidance, they are discharged from the outlet 3, thus forming a complete gas flow circulation system within the flow field structure 4.

[0124] Secondly, embodiments of this application also provide a fuel cell, including a flow field plate of any of the above embodiments and a plurality of stacked membrane electrode assemblies; wherein the flow field plate is disposed between two adjacent membrane electrode assemblies, and the thickness direction Z of the flow field plate is consistent with the stacking direction of the plurality of membrane electrode assemblies.

[0125] In the above technical solution, the fuel cell includes the flow field plate of any of the above embodiments, and has the same technical effect as the flow field plate of any of the above embodiments; that is, the uniformity of the reactant gas in the flow field of the fuel cell is improved, so that the reactant gas can be relatively uniformly distributed on the corresponding gas diffusion layer, which has a good effect on improving the working efficiency and service life of the fuel cell.

[0126] The description of the various embodiments above tends to emphasize the differences between the various embodiments. The similarities or similarities between them can be referred to, and for the sake of brevity, they will not be repeated here.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. This application is not limited to the specific embodiments applied herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A flow field plate suitable for fuel cells, characterized in that, The flow field plate includes: The plate has a plate surface perpendicular to the thickness direction of the plate, and a flow field structure is provided on the plate surface; An air inlet is connected to the flow field structure, and the air inlet is configured to guide the reactive gas into the flow field structure. An outlet is connected to the flow field structure, and the outlet is configured to guide the reactant gas out of the flow field structure. The flow field structure includes: The main channel extends along the first direction and is disposed between the air inlet and the air outlet; Two graded flow fields are distributed on both sides of the main flow channel along the second direction, and the second direction, the first direction, and the thickness direction of the plate are perpendicular to each other; The graded flow field is divided into a first flow field region, a redistributed flow field region, and a second flow field region, which are distributed sequentially along the second direction. The first flow field region is closer to the main flow channel than the second flow field region, and both the first flow field region and the second flow field region are provided with interconnected and intersecting first branch flow channels and second branch flow channels. At least a portion of the first branch flow channel within the first flow field region is connected between the main flow channel and the redistribution flow field region, so that the reactant gas can enter the redistribution flow field region from the main flow channel via the first flow field region; The redistribution flow field region is configured to mix the reactant gas flowing out of the first flow field region and guide a portion of the reactant gas from the first flow field region into the second flow field region; At least a portion of the first branch channel within the second flow field region is connected to the redistribution flow field region, allowing the reactant gas to enter the second flow field region from the redistribution flow field region.

2. The flow field plate according to claim 1, characterized in that, The redistributed flow field region is provided with a plurality of staggered protruding baffles, which are configured to divert the reaction gas flowing out of the first flow field region and guide a portion of the reaction gas into the second flow field region.

3. The flow field plate according to claim 1, characterized in that, The size of the redistributed flow field region in the second direction is W1, and W1 satisfies: 4 mm ≤ W1 ≤ 25 mm.

4. The flow field plate according to claim 1, characterized in that, The main flow channel is provided with a plurality of raised baffles distributed along the first direction. The raised baffles are configured to divert the reaction gas entering from the air inlet and guide a portion of the reaction gas into the first flow field region.

5. The flow field plate according to claim 1, characterized in that, The main channel satisfies at least one of the following conditions: The dimension of the main channel in the second direction is W2, and W2 satisfies: 2 mm ≤ W2 ≤ 5 mm; The dimension of the main channel in the thickness direction of the plate is D1, and D1 satisfies: 0.3 mm ≤ D1 ≤ 1 mm.

6. The flow field plate according to claim 1, characterized in that, The first branch channel satisfies at least one of the following conditions: The angle between the extension direction of the first branch channel and the extension direction of the main channel is α, and α satisfies: 30°≤α≤90°; The dimension of the first branch flow channel in the third direction is W3, and W3 satisfies: 0.4 mm ≤ W3 ≤ 3 mm. The third direction, the extension direction of the first branch flow channel, and the thickness direction of the plate are perpendicular to each other. The number of first branch channels is multiple, and the multiple first branch channels are arranged along a third direction. The extension length of the first branch channel is L1, and L1 satisfies: 2 mm ≤ L1 ≤ 50 mm. The third direction, the extension direction of the first branch channel and the thickness direction of the plate are perpendicular to each other. The first branch channel has a dimension D2 in the thickness direction of the plate, and D2 satisfies: 0.3 mm ≤ D2 ≤ 1 mm.

7. The flow field plate according to claim 1, characterized in that, The second branch channel satisfies at least one of the following conditions: The angle between the extension direction of the second branch channel and the extension direction of the first branch channel is β, wherein β satisfies: 10°≤β≤80°; The second branch channel has a dimension of W4 in the fourth direction, which satisfies: 0.2 mm ≤ W4 ≤ 2 mm. The fourth direction, the extension direction of the second branch channel, and the thickness direction of the plate are perpendicular to each other. The number of second branch channels is multiple, and the multiple second branch channels are arranged along the fourth direction. The extension length of the second branch channel is L2, and L2 satisfies: 2 mm ≤ L2 ≤ 45 mm. The fourth direction, the extension direction of the second branch channel, and the thickness direction of the plate are perpendicular to each other. The second branch channel has a dimension D3 in the thickness direction of the plate, and D3 satisfies: 0.3 mm ≤ D3 ≤ 1 mm.

8. The flow field plate according to claim 1, characterized in that, A third branch flow channel is provided inside the first flow field region and / or the second flow field region, and one end of the third branch flow channel is connected to the second branch flow channel; The third branch channel satisfies at least one of the following conditions: The angle between the extension direction of the third branch channel and the extension direction of the second branch channel is θ, and θ satisfies: 30°≤θ≤90°; The dimension of the third branch channel in the fifth direction is W5, and W5 satisfies: 0.2 mm ≤ W5 ≤ 1 mm. The fifth direction, the extension direction of the third branch channel, and the thickness direction of the plate are perpendicular to each other. The number of the third branch channels is multiple, and the multiple third branch channels are arranged along the fifth direction. The extension length of the third branch channel is L3, and L3 satisfies: 2 mm ≤ L3 ≤ 10 mm. The fifth direction, the extension direction of the third branch channel and the thickness direction of the plate are perpendicular to each other. The dimension of the third branch channel in the thickness direction of the plate is D4, and D4 satisfies: 0.3 mm ≤ D4 ≤ 1 mm.

9. The flow field plate according to claim 8, characterized in that, The other end of the third branch channel extends to the first branch channel, so that the other end of the third branch channel is directly connected to the first branch channel; or, the other end of the third branch channel is a closed end that is not directly connected to the first branch channel.

10. The flow field plate according to claim 9, characterized in that, When the other end of the third branch channel is a closed end that is not directly connected to the first branch channel, the orthographic projection of the other end of the third branch channel on the plane where the plate is located is in the shape of a swallowtail.

11. The flow field plate according to claim 1, characterized in that, The flow field structure satisfies at least one of the following conditions: The dimension of the main channel in the second direction is W2, and the dimension of the main channel in the thickness direction of the plate is D1. W2 and D1 satisfy: 0.5≤W2 / D1≤2; The dimension of the first branch channel in the third direction is W3. The third direction, the extension direction of the first branch channel, and the thickness direction of the plate are perpendicular to each other. The dimension of the first branch channel in the thickness direction of the plate is D2. W3 and D2 satisfy: 0.5≤W3 / D2≤2. The dimension of the second branch flow channel in the fourth direction is W4. The fourth direction, the extension direction of the second branch flow channel, and the thickness direction of the plate are perpendicular to each other. The dimension of the second branch flow channel in the thickness direction of the plate is D3. W4 and D3 satisfy: 0.5≤W4 / D3≤2. A third branch flow channel is provided inside the first flow field region and / or the second flow field region. One end of the third branch flow channel is connected to the second branch flow channel. The dimension of the third branch flow channel in the fifth direction is W5. The fifth direction, the extension direction of the third branch flow channel, and the thickness direction of the plate are perpendicular to each other. The dimension of the third branch flow channel in the thickness direction of the plate is D4. W5 and D4 satisfy: 0.5≤W5 / D4≤2.

12. The flow field plate according to any one of claims 1-11, characterized in that, The flow field structure also includes two side flow channels, which surround the outer periphery of the flow field structure. One end of the side channel is connected to the air inlet, and the other end is connected to the air outlet; The side channel is also connected to at least one of the first branch channel, the second branch channel, and the redistributed flow field region.

13. The flow field plate according to claim 12, characterized in that, The side channel includes a diverging section and a collecting section connected end to end; The end of the diverging section away from the collecting section is connected to the air inlet, and the diverging section is also connected to the second branch flow channel and the redistribution flow field region respectively; The end of the collecting section away from the diverging section is connected to the air outlet, and the collecting section is also connected to the first branch channel and the redistribution flow field region.

14. The flow field plate according to claim 13, characterized in that, The side flow channel satisfies at least one of the following conditions: The dimension of the diverging segment in the sixth direction is W6. The sixth direction, the extension direction of the diverging segment, and the thickness direction of the plate are perpendicular to each other. The dimension of the diverging segment in the thickness direction of the plate is D5. W6 and D5 satisfy: 0.5≤W6 / D5≤2. The size of the collecting segment in the seventh direction is W7. The seventh direction, the extension direction of the collecting segment, and the thickness direction of the plate are perpendicular to each other. The size of the collecting segment in the thickness direction of the plate is D6. W7 and D6 satisfy: 0.5≤W7 / D6≤2.

15. The flow field plate according to any one of claims 1-11, characterized in that, The air inlet is positioned lower than the air outlet, and the air inlet and air outlet are offset in the top and bottom direction of the plate.

16. A fuel cell, characterized in that, It includes the flow field plate as described in any one of claims 1-15 and a plurality of stacked membrane electrode assemblies; The flow field plate is disposed between two adjacent membrane electrode assemblies, and the thickness direction of the flow field plate is consistent with the stacking direction of the plurality of membrane electrode assemblies.

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