A bipolar plate structure and a stack

Abstract

The application discloses a bipolar plate structure and a fuel cell stack, and belongs to the technical field of fuel cells. The bipolar plate structure comprises a bipolar plate body, one end of the bipolar plate body is provided with a reaction gas inlet and a cooling liquid inlet, the other end of the bipolar plate body is provided with a reaction gas outlet and a cooling liquid outlet, and the middle part of the bipolar plate body is provided with a flow channel communicating the reaction gas inlet and the reaction gas outlet; the flow channel comprises a first flow guide structure arranged on the side wall of the flow channel; the first flow guide structure comprises trapezoidal groove structures and triangular protrusion structures alternately connected along the gas flow direction; the first flow guide structure is arranged in two groups; the triangular protrusion structures of one group of the first flow guide structure are arranged towards the trapezoidal groove structures of the other group of the first flow guide structure. The application can prolong the gas residence time, improve the gas utilization rate, and solve the problem that the traditional parallel flow channel is prone to water blockage.

Description

Technical Field

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

[0002] A fuel cell stack is made up of several individual fuel cell cells connected in series. A single fuel cell cell consists of a membrane electrode assembly (MEA), an anode plate, and a cathode plate. In a fuel cell stack, both the anode plate and the cathode plate can be considered as bipolar plates. Typically, the bipolar plates of two adjacent fuel cells are formed by combining one anode plate and one cathode plate.

[0003] For reference Figure 1 The bipolar plate includes an inlet / outlet area 10, a reactant transition area 11 (reaction gas distribution area), and an effective reaction area 12. The inlet / outlet area 10 includes a hydrogen path, an air path, and a cooling path. The number of chambers involved in each path and the positions of the three chambers are not particularly required; they can be determined by the design of the common pipelines on the hydrogen, air, and cooling paths of the fuel cell stack. In other words, the inlet / outlet areas 10 of each cell combine to form a common pipeline. The shape of the reactant transition area 11 (reaction gas distribution area) is also not particularly required. The purpose of this design is to allow the reactants to be more evenly distributed within the effective reaction area 12, ensuring that the electrochemical reaction can proceed uniformly and fully within the effective reaction area 12.

[0004] Within the effective reaction zone 12, flow channel optimization design is generally performed. Current mainstream flow channel designs include serpentine flow channels, parallel flow channels, interdigitated flow channels, and grid flow channels, among others. (See below for reference.) Figure 2 The parallel flow channel 13 has a simple structure and is easy to manufacture. It features numerous parallel flow field channels, resulting in a short flow distance, low inlet and outlet pressure loss, and parallel channel connection, which facilitates the uniform distribution of reactant gases and cooling water within the channels, enabling uniform distribution of current density and battery temperature. However, its drawbacks include a short residence time of reactant gases in the direct-flow channel, low gas utilization, relatively low flow velocity, and the inability to promptly drain generated water, potentially leading to blockage. Summary of the Invention

[0005] To help overcome the drawbacks of parallel flow channels, this application provides a bipolar plate structure and fuel cell stack.

[0006] The bipolar plate structure provided in this application adopts the following technical solution: First aspect A bipolar plate structure includes a bipolar plate body. One end of the bipolar plate body is provided with a reactant gas inlet and a coolant inlet, and the other end of the bipolar plate body is provided with a reactant gas outlet and a coolant outlet. A flow channel connecting the reactant gas inlet and the reactant gas outlet is provided in the middle of the bipolar plate body. The flow channel includes a first flow guiding structure provided on the sidewall of the flow channel. The first flow guiding structure includes trapezoidal groove structures and triangular protrusion structures alternately connected along the gas flow direction. The first flow guiding structure is configured in two sets, with the triangular protrusion structure of one set of the first flow guiding structure facing the trapezoidal groove structure of the other set of the first flow guiding structure.

[0007] By adopting the above technical solution, the airflow forms a low-speed vortex zone at the trapezoidal groove structure. This low-speed vortex zone prolongs the gas residence time and improves gas utilization. Simultaneously, the triangular protrusion structure achieves energy dissipation, ensuring a balanced airflow velocity across the low-speed vortex zones within the flow channel. This, in turn, maintains a consistent gas supply to all parts of the membrane electrode surface, improving the overall reaction uniformity. Furthermore, a high-speed airflow zone is formed at the tip of the triangular protrusion structure, allowing water within the flow channel to be quickly discharged, thus solving the problem of water blockage that easily occurs in traditional parallel flow channels.

[0008] Optionally, the surface of the trapezoidal groove structure is provided with a hydrophobic coating, and the surface of the triangular protrusion structure is provided with a hydrophilic coating.

[0009] By adopting the above technical solution, water in the flow channel can more easily gather on the surface of the triangular protrusion structure, and since the triangular protrusion structure is located in the high-speed airflow zone, it can more easily drain the water in the flow channel, thereby enhancing drainage efficiency.

[0010] Optionally, the tip of the triangular protrusion structure crosses the centerline of the two sets of the first flow guide structures.

[0011] By adopting the above technical solution, the tip of the triangular protrusion structure is more likely to form a high-speed airflow zone, increasing the range and velocity of the high-speed airflow zone and ensuring the smooth discharge of water.

[0012] Optionally, the tip of the triangular protrusion structure is configured as a rounded protrusion.

[0013] By adopting the above technical solution, the area of ​​the hydrophilic coating is increased, making it easier for water to gather at the tip of the triangular protrusion structure, thus making it easier for water to drain out.

[0014] Optionally, the tip of the triangular protrusion structure has a first distance and a second distance with the tips of two adjacent triangular protrusion structures, and the first distance and the second distance are not equal.

[0015] By adopting the above technical solution, the pressure difference between the area where the first distance is located and the area where the second distance is located is not the same, so that the gas and water flow along the flow channel more smoothly under the action of different pressure differences.

[0016] Optionally, the trapezoidal groove structure includes a first inclined surface, a groove plane, and a second inclined surface. The first inclined surface is disposed on the side of the trapezoidal groove structure facing the gas flow direction, and the second inclined surface is disposed on the side of the trapezoidal groove structure away from the gas flow direction. The angle between the first inclined surface and the groove plane is greater than the angle between the second inclined surface and the groove plane.

[0017] By adopting the above technical solutions, the buffering capacity of gas or water flow during the flow process is improved, making the gas or water flow more stable during the flow process; at the same time, the design of the inclined plane is not easy to accumulate air or water flow at the inner corner for a long time, improving the fluidity of air or water flow and ensuring the normal progress of the reaction.

[0018] Optionally, the bottom wall of the flow channel is provided with sequentially connected arrow-shaped hydrophilic patterns, with the arrowheads of the arrow-shaped hydrophilic patterns pointing towards the gas flow direction.

[0019] By adopting the above technical solution, the generated water can be more easily discharged along the flow channel.

[0020] Optionally, the larger end of the arrow-shaped hydrophilic pattern is positioned near the triangular protrusion structure.

[0021] By adopting the above technical solution, more water is gathered at the hydrophilic coating and the arrow-shaped hydrophilic pattern. Since the hydrophilic coating is located in the high-speed airflow zone, the high flow rate of the high-speed airflow zone makes it easier to discharge water from the flow channel.

[0022] Optionally, the flow channel is one of a parallel flow channel, a serpentine flow channel, or a biomimetic flow channel.

[0023] Second aspect An electric stack comprising the bipolar plate structure described above.

[0024] In summary, this application includes at least one of the following beneficial technical effects: 1. The airflow forms a low-speed vortex zone at the trapezoidal groove structure. This low-speed vortex zone prolongs the gas residence time and improves gas utilization. Simultaneously, the triangular protrusion structure achieves energy dissipation, maintaining a balanced airflow velocity across the low-speed vortex zones within the flow channel. This ensures a consistent gas supply to all parts of the membrane electrode surface, improving the overall reaction uniformity. Furthermore, a high-speed airflow zone is formed at the tip of the triangular protrusion structure. Water within the flow channel can be quickly discharged through this high-speed airflow zone, solving the problem of water blockage that easily occurs in traditional parallel flow channels.

[0025] 2. The combination of low-speed vortex zone and high-speed airflow zone can prolong gas residence time and improve gas utilization, while also shortening drainage time and improving drainage efficiency.

[0026] 3. The alternating use of hydrophilic and hydrophobic coatings, along with low-speed vortex zones and high-speed airflow zones, can effectively enhance drainage efficiency.

[0027] 4. The flow channel structure, which combines trapezoidal groove structure and triangular protrusion structure, has a uniform flow field distribution, almost no stagnation zone, good energy dissipation effect, uniform and stable flow state, and effectively improves the anti-clogging performance of the flow channel. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a bipolar plate in related technologies.

[0029] Figure 2 This is a schematic diagram of the parallel flow channel structure in related technologies.

[0030] Figure 3 This is a schematic diagram of the bipolar plate body structure of Embodiment 1 of this application.

[0031] Figure 4 This is a planar schematic diagram of the bipolar plate body of Embodiment 1 of this application.

[0032] Figure 5 yes Figure 4 An enlarged schematic diagram of part A in the middle.

[0033] Figure 6 This is a schematic diagram of the flow field distribution within the flow channel.

[0034] Figure 7 This is a planar schematic diagram of the bipolar plate body of Embodiment 2 of this application.

[0035] Figure 8 yes Figure 7 Enlarged schematic diagram of part B.

[0036] Explanation of reference numerals in the attached figures: 10. Outlet area; 11. Reactant transition zone; 12. Effective reaction zone; 13. Parallel flow channel; 20. Bipolar plate body; 21. Reactant gas inlet; 22. Coolant inlet; 23. Reactant gas outlet; 24. Coolant outlet; 30. Flow channel; 40. First flow guide structure; 41. Trapezoidal groove structure; 411. Low-speed vortex zone; 412. First inclined surface; 413. Groove plane; 414. Second inclined surface; 42. Triangular protrusion structure; 421. High-speed airflow zone; 422. Arc protrusion; 50. Arrow-shaped hydrophilic pattern. Detailed Implementation

[0037] The following is in conjunction with the appendix Figure 3-8This application will be described in further detail.

[0038] Example 1 This application discloses a bipolar plate structure. (Refer to...) Figure 3 and Figure 4 The bipolar plate structure includes a bipolar plate body 20. One end of the bipolar plate body 20 is provided with a reaction gas inlet 21 and a coolant inlet 22, and the other end of the bipolar plate body 20 is provided with a reaction gas outlet 23 and a coolant outlet 24. A flow channel 30 connecting the reaction gas inlet 21 and the reaction gas outlet 23 is provided in the middle of the bipolar plate body 20.

[0039] The flow channel 30 is one of the following: parallel flow channel 13, serpentine flow channel, or biomimetic flow channel. In this embodiment, parallel flow channel 13 is used as an example.

[0040] In a preferred embodiment, the length of the flow channel 30 is 70 mm, the width of the flow channel 30 is 1.5 mm, the depth is 1.5 mm, and the interval between adjacent flow channels 30 is 1 mm.

[0041] Reference Figure 5 The flow channel 30 includes a first flow guiding structure 40 disposed on the side wall of the flow channel 30. The first flow guiding structure 40 includes trapezoidal groove structures 41 and triangular protrusion structures 42 that are alternately connected along the gas flow direction. The first flow guiding structure 40 is configured as two sets, with the triangular protrusion structures 42 of one set of the first flow guiding structure 40 facing the trapezoidal groove structures 41 of the other set of the first flow guiding structure 40.

[0042] In a preferred embodiment, the tip of the triangular protrusion 42 crosses the center line of the two sets of first flow guiding structures 40.

[0043] The airflow forms a low-speed vortex zone 411 at the trapezoidal groove structure 41. The low-speed vortex zone 411 can prolong the gas residence time and improve gas utilization. At the same time, the triangular protrusion structure 42 achieves an energy dissipation effect, keeping the airflow velocity of each low-speed vortex zone 411 in the flow channel 30 balanced, thereby ensuring that the amount of gas supplied to all parts of the membrane electrode surface is consistent and improving the uniformity of the overall reaction. In addition, the airflow forms a high-speed airflow zone 421 at the tip of the triangular protrusion structure 42. Water in the flow channel 30 can be quickly discharged through the high-speed airflow zone 421, solving the problem of water blockage that is easily caused by the traditional parallel flow channel 13.

[0044] In a preferred embodiment, the surface of the trapezoidal groove structure 41 is provided with a hydrophobic coating, and the surface of the triangular protrusion structure 42 is provided with a hydrophilic coating. The coating can be processed on the bipolar plate body 20 based on techniques such as physical vapor deposition, chemical vapor deposition, or electroplating.

[0045] Since the trapezoidal groove structure 41 and the triangular protrusion structure 42 are arranged opposite each other, the hydrophobic coating and the hydrophilic coating are arranged alternately along the gas flow direction in the flow channel 30. The generated droplets are swept and rolled to the hydrophilic surface by the airflow on the surface of the hydrophobic coating. The hydrophilic surface is in the high-speed airflow zone 421. The droplets on the hydrophilic surface are more easily carried away by the airflow, thus achieving efficient drainage.

[0046] In a preferred embodiment, the tip of the triangular protrusion 42 is configured as a rounded protrusion 422. The rounded protrusion 422 increases the droplet aggregation area, making it easier for droplets to converge at the tip of the triangular protrusion 42, thereby improving the drainage effect.

[0047] Among them, the tip of the triangular protrusion structure 42 has a first distance L1 and a second distance L2 between the tip of the two adjacent triangular protrusion structures 42, and the first distance L1 and the second distance L2 are not equal.

[0048] In a preferred embodiment, the first distance L1 is less than the second distance L2. At this time, the flow velocity in the region where the first distance L1 is located is greater than the flow velocity in the region where the second distance L2 is located. As a result, under the action of different flow velocity differences, the gas and water flow along the channel 30 more smoothly.

[0049] Meanwhile, the trapezoidal groove structure 41 includes a first inclined surface 412, a groove plane 413, and a second inclined surface 414. The first inclined surface 412 is located on the side of the trapezoidal groove structure 41 facing the gas flow direction, and the second inclined surface 414 is located on the side of the trapezoidal groove structure 41 facing away from the gas flow direction. The angle between the first inclined surface 412 and the groove plane 413 is greater than the angle between the second inclined surface 414 and the groove plane 413. Furthermore, the region near the second distance L2 is close to the first inclined surface 412, and the region near the first distance L1 is close to the second inclined surface 414.

[0050] The side facing the airflow direction experiences a greater impact force from the airflow or water flow. In this case, increasing the tilt angle of the side facing the airflow direction helps to slow down the flow velocity. At the same time, increasing the space on the side facing the airflow direction allows the impact force on the inner wall of the flow channel 30 to be kept as balanced as possible, thereby enhancing structural stability.

[0051] The implementation principle of a bipolar plate structure in this application embodiment is as follows: [The structure is described in the original text, but the translation is incomplete and cannot be translated.] Figure 6 It can be seen that the flow field distribution of the flow channel 30 structure, which combines the trapezoidal groove structure 41 and the triangular protrusion structure 42, is uniform, with almost no stagnation zone, good energy dissipation effect, and uniform and stable flow state, effectively improving the anti-clogging performance of the flow channel 30.

[0052] Example 2 The difference between this embodiment and Embodiment 1 is that, referring to... Figure 7 and Figure 8The bottom wall of the flow channel 30 is also provided with arrow-shaped hydrophilic patterns 50. Multiple arrow-shaped hydrophilic patterns 50 are provided and connected sequentially along the gas flow direction, with the arrow ends of the arrow-shaped hydrophilic patterns 50 pointing towards the gas flow direction.

[0053] The arrow-shaped hydrophilic pattern 50 can be processed on the bipolar plate body 20 by techniques such as physical vapor deposition, chemical vapor deposition or electroplating.

[0054] Meanwhile, the larger end of the arrow-shaped hydrophilic pattern 50 is positioned near the triangular protrusion structure 42, while the smaller end is positioned near the trapezoidal groove structure 41. This allows more water to converge at the hydrophilic coating and the arrow-shaped hydrophilic pattern 50. Since the hydrophilic coating and the arrow-shaped hydrophilic pattern 50 are located in the high-speed airflow zone 421, the high flow rate of the high-speed airflow zone 421 makes it easier to discharge water from the flow channel 30.

[0055] This application also discloses an electric fuel cell stack. The electric fuel cell stack includes the above-described bipolar plate structure.

[0056] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A bipolar plate structure, comprising a bipolar plate body (20), wherein one end of the bipolar plate body (20) is provided with a reactant gas inlet (21) and a coolant inlet (22), and the other end of the bipolar plate body (20) is provided with a reactant gas outlet (23) and a coolant outlet (24), and a flow channel (30) communicating the reactant gas inlet (21) and the reactant gas outlet (23) is provided in the middle of the bipolar plate body (20), characterized in that: The flow channel (30) includes a first flow guiding structure (40) disposed on the side wall of the flow channel (30). The first flow guiding structure (40) includes a trapezoidal groove structure (41) and a triangular protrusion structure (42) that are alternately connected along the gas flow direction. The first flow guiding structure (40) is configured in two groups, with the triangular protrusion structure (42) of one group of the first flow guiding structure (40) facing the trapezoidal groove structure (41) of the other group of the first flow guiding structure (40). The tip of the triangular protrusion structure (42) crosses the center line of the two sets of the first flow guiding structures (40); The trapezoidal groove structure (41) includes a first inclined surface (412), a groove plane (413), and a second inclined surface (414). The first inclined surface (412) is disposed on the side of the trapezoidal groove structure (41) facing the gas flow direction, and the second inclined surface (414) is disposed on the side of the trapezoidal groove structure (41) away from the gas flow direction. The angle between the first inclined surface (412) and the groove plane (413) is greater than the angle between the second inclined surface (414) and the groove plane (413).

2. The bipolar plate structure according to claim 1, characterized in that: The surface of the trapezoidal groove structure (41) is provided with a hydrophobic coating, and the surface of the triangular protrusion structure (42) is provided with a hydrophilic coating.

3. The bipolar plate structure according to claim 2, characterized in that: The tip of the triangular protrusion structure (42) is set as an arc protrusion (422).

4. A bipolar plate structure according to claim 1 or 2, characterized in that: The tip of the triangular protrusion structure (42) has a first distance and a second distance with the tips of two adjacent triangular protrusion structures (42), and the first distance and the second distance are not equal.

5. A bipolar plate structure according to claim 2, characterized in that: The bottom wall of the flow channel (30) is provided with arrow-shaped hydrophilic patterns (50) connected in sequence, with the arrow ends of the arrow-shaped hydrophilic patterns (50) facing the gas flow direction.

6. A bipolar plate structure according to claim 5, characterized in that: The larger end of the arrow-shaped hydrophilic pattern (50) is positioned near the triangular protrusion structure (42).

7. A bipolar plate structure according to claim 1 or 2, characterized in that: The flow channel (30) is one of a parallel flow channel (13), a serpentine flow channel, or a biomimetic flow channel.

8. A fuel cell stack, characterized in that: Includes the bipolar plate structure as described in any one of claims 1-7.

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