A fuel cell bipolar plate with a self-draining flow channel structure

Abstract

The utility model discloses a fuel cell bipolar plate with a self-draining flow channel structure, which relates to the technical field of fuel cell bipolar plates. The rectangular structure comprises an air reaction zone, a cathode inlet and a cathode outlet, wherein the cathode inlet and the cathode outlet are symmetrically arranged along the geometric center of the bipolar plate, an upper air distribution zone is provided at the connection between the air reaction zone and the cathode inlet, and a lower air distribution zone is provided at the connection between the air reaction zone and the cathode outlet, wherein the air reaction zone is provided with an air supply channel and the air supply channel is arranged at an inclination angle of no more than 90 degrees with the vertical direction; the technical solution in the application utilizes gravity to discharge liquid water generated by the battery stack, and is designed to have parallel flow channels with a certain inclination angle for the flow channels of the cathode bipolar plate, and realizes the gradient of hydrophobicity from the cathode inlet to the outlet by adding materials with different hydrophobic contents at the lower part of the flow channel side wall.

Description

Technical Field

[0001] The utility model relates to the technical field of fuel cell bipolar plates, in particular to a fuel cell bipolar plate with a self-draining flow channel structure. Background Art

[0002] As the core component of hydrogen fuel cells, bipolar plates play an important role in mass transfer, heat removal and electrical conductivity of fuel cell systems. Since water is produced when the fuel reacts, if the water cannot be discharged in time, it will cause water to be blocked in the flow channel, reducing the reaction efficiency and affecting the performance of the fuel cell. Especially for high-power hydrogen fuel cells, the problem of efficient discharge of generated water must be solved. In the current fuel cell bipolar plates, in order to make the fuel reaction more sufficient, a more complex flow channel structure is usually designed. The complex flow channel structure not only puts higher demands on processing accuracy and processing conditions, but also brings additional cost pressure, which runs counter to the development trend of the fuel cell industry that urgently needs to reduce costs. For this reason, the present application proposes a fuel cell bipolar plate with a self-draining flow channel structure, which has become an urgent problem to be solved. Summary of the invention

[0003] In view of the defects existing in the prior art, the purpose of the utility model is to provide a fuel cell bipolar plate with a self-draining flow channel structure, aiming to increase the flow rate of liquid water by using gravity, prevent water blockage, and assist in solving the water reflux problem.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0005] A fuel cell bipolar plate with a self-draining flow channel structure, the bipolar plate is a rectangular structure and includes an air reaction zone, a cathode inlet, and a cathode outlet, the cathode inlet and the cathode outlet are symmetrically arranged along the geometric center of the bipolar plate, an upper air distribution zone is provided at the connection between the air reaction zone and the cathode inlet, and a lower air distribution zone is provided at the connection between the air reaction zone and the cathode outlet, wherein the air reaction zone is provided with a supply flow channel and the supply flow channel is arranged at an inclination angle of no more than 90 degrees to the vertical direction, the bipolar plate is also provided with an anode inlet, an anode outlet and a hydrogen reaction zone, the hydrogen reaction zone is provided with a supply flow channel and the supply flow channel is arranged at an inclination angle of no more than 90 degrees to the vertical direction.

[0006] On the basis of the above technical solution, the anode inlet and the anode outlet are arranged symmetrically along the geometric center of the bipolar plate.

[0007] On the basis of the above technical solution, an upper hydrogen distribution area and a lower hydrogen distribution area are respectively provided at the connection between the hydrogen reaction zone and the anode inlet and the anode outlet.

[0008] On the basis of the above technical solution, the hydrogen reaction zone and the hydrogen reaction zone both include flow channel ridges, and the flow channel ridges are evenly spaced and distributed on the hydrogen reaction zone and the hydrogen reaction zone.

[0009] On the basis of the above technical solution, the flow channel ridge is further provided with a first coating, a second coating and a third coating, and the first coating, the second coating and the third coating are connected in sequence and the thickness increases in a gradient manner.

[0010] On the basis of the above technical solution, the first coating, the second coating and the third coating are hydrophobic coatings and the coating thicknesses are 2 mm, 4 mm and 6 mm respectively.

[0011] On the basis of the above technical solution, the mass fractions of the hydrophobic agent coatings of the first coating, the second coating, and the third coating are 10%, 15%, and 20%, respectively.

[0012] On the basis of the above technical solution, the air supply channel of the air reaction zone is set at an angle of 5-15° to the vertical direction, and the air supply channel of the hydrogen reaction zone is set at an angle of 5-15° to the vertical direction.

[0013] On the basis of the above technical solution, the air supply channels of the air reaction zone and the hydrogen reaction zone are straight flow channels, serpentine flow channels or cross-finger flow channels, or a combination of two of them.

[0014] Compared with the prior art, the advantages of the utility model are:

[0015] Compared with the prior art, the fuel cell bipolar plate with a self-draining flow channel structure in the utility model has a membrane electrode and a bipolar plate of the stack placed perpendicular to the ground, following the principle of gas entering from top to bottom and draining from bottom, and using gravity to discharge the liquid water generated by the stack. The flow channel of the cathode bipolar plate is designed to have a parallel flow channel with a certain inclination angle (5-15°), and the hydrophobic gradient from the cathode inlet to the outlet is achieved by adding materials with different hydrophobic contents to the lower part of the flow channel side wall. At the same time, different thicknesses of the coating can achieve local narrowing of the flow channel, which is more conducive to the removal of moisture on the one hand, and at the same time compensates for the pressure drop caused by the reaction of the gas to a certain extent, so that the current distribution is uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a three-dimensional structure of a fuel cell bipolar plate stacked and formed with a self-draining flow channel structure in an embodiment of the utility model;

[0017] Figure 2 It is a schematic diagram of the structure of the bipolar plate air flow channel in the embodiment of the utility model;

[0018] Figure 3 This is a schematic diagram of the structure of the hydrogen flow channel of the bipolar plate in the embodiment of the utility model;

[0019] Figure 4 It is a schematic structural diagram of the bipolar plate flow channel ridge in an embodiment of the utility model.

[0020] In the figure: 1-cathode inlet, 2-cathode outlet, 3-anode inlet, 4-anode outlet, 5-upper air distribution area, 6-lower air distribution area, 7-air reaction area, 8-hydrogen reaction area, 9-upper hydrogen distribution area, 10-lower hydrogen distribution area, 11-flow channel ridge, 12-first coating, 13-second coating, 14-third coating. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0022] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0023] See Figure 2 It is a structural schematic diagram of the bipolar plate air flow channel in the embodiment of the utility model, a fuel cell bipolar plate with a self-draining flow channel structure, in this embodiment, the bipolar plate is a graphite bipolar plate, and the four corners of the rectangular structure bipolar plate are respectively preset with gas inlet and outlet areas, including air reaction area 7, cathode inlet 1, and cathode outlet 2. The cathode inlet 1 and cathode outlet 2 are designed along the diagonal of the rectangle, and the size and shape of the cathode inlet 1 and cathode outlet 2 are symmetrically arranged along the geometric center of the bipolar plate. Similarly, the anode inlet 3 and the anode outlet 4 are symmetrically arranged along the geometric center of the bipolar plate. Secondly, the upper air distribution area 5 is provided at the connection between the air reaction area 7 and the cathode inlet 1, and the lower air distribution area 6 is provided at the connection between the air reaction area 7 and the cathode outlet 2, wherein the air reaction area 7 is provided with a supply air channel and the supply air channel is set at an angle of not more than 90 degrees with the vertical direction. In this embodiment, the supply air channel is set at an angle of 5-15° with the vertical direction. Similarly, the upper hydrogen distribution area 9 and the lower hydrogen distribution area 10 are respectively provided at the connection between the hydrogen reaction area 8 and the anode inlet 3 and the anode outlet 4. The design of the gas distribution area is conducive to the uniformity of the gas flow field distribution in the gas supply channel.

[0024] The inclination of the air delivery channel facilitates the removal of the reaction generated water, and utilizes the structural gravity to accelerate the drainage effect of the stack. In actual engineering use, the bipolar plates in this application are required to be stacked vertically. If they are laid flat, the drainage effect of the flow channel inclination design will be greatly offset.

[0025] See Figure 3 The structure diagram of the bipolar plate hydrogen flow channel in the embodiment of the utility model is shown. The bipolar plate is also provided with an anode inlet 3 and an anode outlet 4 and a hydrogen reaction zone 8. The hydrogen reaction zone 8 is provided with a flow channel and the flow channel is set at an angle of no more than 90 degrees to the vertical direction. In the present application, the cathode plate air reaction zone 7 and the anode plate hydrogen reaction zone 8 are centrally symmetrically arranged, both with an upper air inlet and a lower air outlet, which is convenient for ensuring the drainage utilization of gravity.

[0026] In this embodiment, a hydrophobic flow channel ridge 11 is provided. The hydrogen reaction zone 8 and the hydrogen reaction zone 8 both include the flow channel ridge 11, and the flow channel ridge 11 is evenly spaced and distributed on the hydrogen reaction zone 8 and the hydrogen reaction zone 8.

[0027] See Figure 4 The structure diagram of the bipolar plate flow channel ridge in the embodiment of the utility model is shown. The flow channel ridge 11 is also provided with a first coating 12, a second coating 13, and a third coating 14. The first coating 12, the second coating 13, and the third coating 14 are connected in sequence and the thickness increases in a gradient. Specifically, in this embodiment, the hydrophobic coating thickness of the first coating 12, the second coating 13, and the third coating 14 is set to 2mm, 4mm, and 6mm, respectively. The gradient of the coating thickness can achieve a gradient change in the height of the flow channel ridge 11, thereby achieving a gradient change in the porosity of the MEA in a compressed state, further improving the drainage effect.

[0028] The mass fractions of the hydrophobic coatings of the first coating 12, the second coating 13, and the third coating 14 are 10%, 15%, and 20%, respectively. The different mass fractions of the hydrophobic coatings make the hydrophobic properties of the coatings present a certain gradient characteristic, so that the internal drainage conditions of the single fuel cell are smoother, which is conducive to better guiding the moisture in the anode plate ridge area to the flow channel area of ​​the plate, thereby achieving a drainage effect.

[0029] See Figure 1 This is a schematic diagram of a three-dimensional structure of a stacked bipolar plate of a fuel cell with a self-draining flow channel structure in an embodiment of the utility model. In this application, the bipolar plates of the fuel cell are stacked and formed at an angle to the horizontal direction, and gravity is used to enhance the drainage effect. A single bipolar plate is placed perpendicular to the ground. At this time, the air supply channel of the air reaction zone 7 is set at an angle of 5-15° to the vertical direction, and the air supply channel of the hydrogen reaction zone 8 is set at an angle of 5-15° to the vertical direction. It can achieve good drainage performance, make full use of the combination of layout position and structural design, and achieve passive drainage effect. It does not increase additional parasitic power for the fuel cell system, does not require auxiliary components to be designed, and has a good engineering application effect.

[0030] In this embodiment, the flow channel design of the air counter zone 7 and the hydrogen reaction zone 8 can be designed according to the output performance requirements, volume power density index, fuel cell working environment requirements, etc. The air supply flow channel of the air counter zone 7 and the hydrogen reaction zone 8 is one or a combination of a flat straight flow channel, a serpentine flow channel or an interdigital flow channel. In this embodiment, the use of a straight flow channel can provide a more uniform gas distribution, which helps to improve the reaction efficiency of the fuel cell. Since the gas flow path is short and straight, the supply flow channel has a lower pressure drop, and hydrogen can pass through the flow channel at a lower pressure, thereby reducing the power of the hydrogen pump. On the other hand, the design and manufacturing process of the flat straight flow channel is relatively simple, which helps to reduce production costs.

[0031] In this application, a serpentine or interdigital flow channel design is used for low-power application scenarios to improve mass transfer efficiency and obtain better battery performance. Due to its tortuous shape, the serpentine flow channel can form water accumulation at the high point of the flow channel, thereby promoting water discharge. In a serpentine or interdigital flow channel, the gas flow is more dynamic, reducing the formation of gas dead zones and avoiding insufficient gas supply or water accumulation. The interdigital flow channel uses the pressure difference formed between adjacent flow channels to push water to the exhaust end to achieve better drainage.

[0032] The present invention is not limited to the above-mentioned embodiments. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A fuel cell bipolar plate with a self-draining flow channel structure, characterized in that: The bipolar plate is a rectangular structure and comprises an air reaction zone (7), a cathode inlet (1), and a cathode outlet (2). The cathode inlet (1) and the cathode outlet (2) are symmetrically arranged along the geometric center of the bipolar plate. An upper air distribution zone (5) is provided at the connection between the air reaction zone (7) and the cathode inlet (1), and a lower air distribution zone (6) is provided at the connection between the air reaction zone (7) and the cathode outlet (2). The air reaction zone (7) is provided with an air supply channel, and the air supply channel is arranged at an angle of not more than 90 degrees to the vertical direction. The bipolar plate is also provided with an anode inlet (3), an anode outlet (4) and a hydrogen reaction zone (8). The hydrogen reaction zone (8) is provided with an air supply channel, and the air supply channel is arranged at an angle of not more than 90 degrees to the vertical direction.

2. A fuel cell bipolar plate with a self-draining flow channel structure according to claim 1, characterized in that: The anode inlet (3) and the anode outlet (4) are symmetrically arranged along the geometric center of the bipolar plate.

3. The fuel cell bipolar plate with a self-draining flow channel structure according to claim 1, characterized in that: An upper hydrogen distribution area (9) and a lower hydrogen distribution area (10) are respectively provided at the connection between the hydrogen reaction area (8) and the anode inlet (3) and the anode outlet (4).

4. A fuel cell bipolar plate with a self-draining flow channel structure according to claim 1, characterized in that: The hydrogen reaction zone (8) and the hydrogen reaction zone (8) both comprise flow channel ridges (11), and the flow channel ridges (11) are arranged at equal intervals on the hydrogen reaction zone (8) and the hydrogen reaction zone (8).

5. A fuel cell bipolar plate with a self-draining flow channel structure according to claim 4, characterized in that: The flow channel ridge (11) is further provided with a first coating (12), a second coating (13), and a third coating (14); the first coating (12), the second coating (13), and the third coating (14) are connected in sequence and their thickness increases in a gradient manner.

6. A fuel cell bipolar plate with a self-draining flow channel structure according to claim 5, characterized in that: The first coating (12), the second coating (13), and the third coating (14) are hydrophobic coatings, and the coating thicknesses are 2 mm, 4 mm, and 6 mm, respectively.

7. A fuel cell bipolar plate with a self-draining flow channel structure according to claim 6, characterized in that: The mass fractions of the hydrophobic coatings in the first coating (12), the second coating (13), and the third coating (14) are 10%, 15%, and 20%, respectively.

8. The fuel cell bipolar plate with a self-draining flow channel structure according to claim 1, characterized in that: The air supply channel of the air reaction zone (7) is arranged at an angle of 5-15° to the vertical direction, and the air supply channel of the hydrogen reaction zone (8) is arranged at an angle of 5-15° to the vertical direction.

9. The fuel cell bipolar plate with a self-draining flow channel structure according to claim 1, characterized in that: The air supply channels of the air reaction zone (7) and the hydrogen reaction zone (8) are straight flow channels, serpentine flow channels or interdigital flow channels, or a combination of the two.

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