A fuel cell cathode plate and its flow field structure

Abstract

The present invention discloses a fuel cell cathode plate flow field structure. A membrane electrode is provided on the top of the fuel cell cathode plate flow field structure. The flow field structure includes: a plurality of parallel air flow channels, the air flow channels extending along the width direction of the fuel cell cathode plate, and a flow channel ridge formed between two adjacent air flow channels; a ridge groove for air flow is provided on the flow channel ridge, the ridge groove is parallel to the air flow channel, and the depth is less than the air flow channel, so that air can flow between the flow channel ridge and the membrane electrode, and react on the membrane electrode to produce water. The present invention provides a ridge groove on the flow channel ridge, so that when the fuel cell cathode plate flow field structure is in use, air flows in the ridge groove and the air flow channel at the same time, and reacts on the membrane electrode to produce water. However, because the depth of the ridge groove is less than the depth of the air flow channel, the resistance of the air when flowing in the ridge groove is relatively large, making it difficult for the water in the membrane electrode near the ridge groove to be carried away by the air, thereby humidifying the membrane electrode.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and in particular to a fuel cell cathode plate and a flow field structure thereof. Background Art

[0002] An open-cathode air-cooled fuel cell is a type of cell that directly exposes the cathode side of the membrane electrode to the air, using air as both the cathode reaction medium and the cooling medium. In this open-cathode air-cooled fuel cell, the amount of air used for heat dissipation is far greater than the amount of air required for the reaction. This results in the air flowing through the cathode side of the cell removing a large amount of moisture, causing the membrane electrode to dry out, resulting in a high internal resistance and poor battery performance. To alleviate this defect, researchers have begun developing membrane electrodes with moisturizing functions to retain moisture in the membrane electrode. Currently, no researchers have been found to have made improvements to the battery plate structure to address the problem of membrane electrode drying. Summary of the Invention

[0003] The purpose of the present invention is to provide a fuel cell cathode plate and a flow field structure thereof, so as to solve the technical problem that the membrane electrode of the existing open air-cooled fuel cell is easy to dry out.

[0004] In order to achieve the above-mentioned purpose, the present invention provides a fuel cell cathode plate flow field structure, wherein a membrane electrode is provided on the top of the fuel cell cathode plate flow field structure, and the fuel cell cathode plate flow field structure comprises: a plurality of parallel air flow channels, wherein the air flow channels extend along the width direction of the fuel cell cathode plate, and a flow channel ridge is formed between two adjacent air flow channels; a ridge groove for air flow is provided on the flow channel ridge, wherein the ridge groove is parallel to the air flow channel and has a depth smaller than that of the air flow channel, so that air can flow between the flow channel ridge and the membrane electrode, and react on the membrane electrode to generate water.

[0005] Optionally, both ends of the ridge groove are connected to the outside.

[0006] Optionally, the depth ratio of the ridge groove to the air flow channel is 1:2-1:10.

[0007] Optionally, the width of the ridge groove is smaller than that of the air flow channel, and the ratio of the width of the ridge groove to the width of the air flow channel is 1:2-1:3.5.

[0008] Optionally, the ridge groove has a depth of 0.4 mm to 0.8 mm and a width of 0.4 mm to 1.1 mm.

[0009] The present invention also provides a fuel cell bipolar plate, which includes a cathode plate and an anode plate. The cathode plate has the above-mentioned fuel cell cathode plate flow field structure.

[0010] Optionally, the cathode plate and the anode plate are made by a metal stamping process.

[0011] Optionally, the cathode plate and the anode plate are fixed by welding or adhesive injection to form a fuel cell bipolar plate.

[0012] Optionally, the cathode plate and the anode plate are made by a graphite carving process.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) The fuel cell cathode plate flow field structure provided by the present invention includes: an air flow channel and a flow channel ridge, wherein the flow channel ridge is provided with a ridge groove, which is parallel to the air flow channel and has a depth less than that of the air flow channel. In use, air flows through the ridge groove and the air flow channel simultaneously, reacting on the membrane electrode to produce water. However, because the depth of the ridge groove is less than that of the air flow channel, the air has a greater resistance when flowing in the ridge groove, making it difficult for the water in the membrane electrode near the ridge groove to be carried away by the air, thereby humidifying the membrane electrode.

[0015] (2) The present invention further increases the heat dissipation area of the battery by providing ridge grooves on the flow channel ridges for air flow, thereby improving the battery's ability to adapt to ambient temperature and thus improving the power density of the battery.

[0016] (3) The fuel cell cathode plate of the present invention is particularly suitable for cathode open air-cooled fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of the cathode plate of an existing fuel cell;

[0018] Figure 2 is a schematic cross-sectional view of a cathode plate of a fuel cell in a conventional embodiment;

[0019] Figure 3 is a schematic cross-sectional view of a cathode plate of a fuel cell in another existing embodiment;

[0020] Figure 4 is a schematic cross-sectional view of a cathode plate of a fuel cell according to one embodiment of the present invention;

[0021] Figure 5 Graph showing test results of a fuel cell comprising the fuel cell cathode plate of the present invention;

[0022] Figure 6 A schematic cross-sectional view of a cathode plate of a fuel cell according to another embodiment of the present invention;

[0023] Figure 7 The fuel cell containing the fuel cell cathode plate of the present invention has a 0.5A / cm 2 Battery voltage.

[0024] In the figure: 1-reaction medium inlet and outlet; 2-flow field, 21-air flow channel, 22-flow channel ridge, 23-hydrogen flow channel, 24-ridge groove, 25-cooling flow channel; 3-membrane electrode DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0026] In existing open-type, air-cooled fuel cells, the cathode side of the fuel cell membrane electrode is directly exposed to air, allowing the air to serve as both a reaction medium and a cooling medium. However, because the amount of air used for heat dissipation far exceeds the amount required for the reaction, the air flowing through the cathode side removes more moisture than is generated by the reaction, causing the membrane electrode to dry out.

[0027] like Figure 1-Figure 3 As shown in FIG, the internal structure of the conventional fuel cell plate includes a reaction medium inlet and outlet 1, a flow field 2, and a sealing structure. Among them, the top surface of the flow ridge 22 in the flow field 2 is flat, and there is no space for air to flow. Therefore, the membrane electrode 3 on the top of the flow ridge 22 does not participate in the reaction. Figure 4 As shown, the present invention provides a fuel cell cathode plate flow field structure, comprising: a plurality of parallel air flow channels 21, the air flow channels 21 extending through the width direction of the fuel cell cathode plate, and a flow channel ridge 22 formed between two adjacent air flow channels 21; a ridge groove 24 is provided on the flow channel ridge 22, the ridge groove 24 is parallel to the air flow channel 21, and the depth is less than the air flow channel 21.

[0028] In the fuel cell cathode plate flow field structure of the present invention, a ridge groove 24 is formed on the top surface of the flow channel ridge 22. This ridge groove 24 is parallel to the air flow channel 21, allowing air to flow through the ridge groove 24 and react on the membrane electrode 3 at the top of the flow channel ridge 22 to produce water. Furthermore, due to the small depth of the ridge groove 24, the resistance to air flow within the ridge groove 24 is relatively large, making it difficult for air to remove moisture from the membrane electrode 3 at the top of the ridge groove 24, thereby increasing the humidity of the membrane electrode 3.

[0029] In some embodiments, both ends of the ridge groove 24 are in communication with the outside, and a wind-generating device such as a fan may be provided outside the fuel cell to deliver air into the ridge groove 24 .

[0030] In some embodiments, the depth ratio of the ridge groove 24 to the air flow channel 21 is 1:2-1:10. If the ridge groove 24 is too deep, the air flow rate will be large, taking away more water, and failing to achieve the water retention effect.

[0031] In some embodiments, the width ratio of the ridge groove 24 to the air flow channel 21 is 1:2-1:3.5. If the ridge groove 24 is too wide, less space is left for the air flow channel 21, and the heat dissipation effect of the battery stack is poor.

[0032] Specifically, the depth of the ridge groove 24 is controlled between 0.4 mm and 0.8 mm, and the width is controlled between 0.4 mm and 1.1 mm.

[0033] The present invention also provides a fuel cell bipolar plate, which includes a cathode plate and an anode plate, wherein the cathode plate has the above-mentioned fuel cell cathode plate flow field structure, which is described below in conjunction with specific embodiments.

[0034] Comparative Example 1

[0035] like Figure 2 As shown, Comparative Example 1 is an existing fuel cell bipolar plate, which is made by graphite carving. The air flow channel 21 in the bipolar plate is 1.2 mm wide, the flow channel ridge 22 is 2.4 mm wide, and no ridge groove is provided on the top surface of the flow channel ridge.

[0036] Example 1

[0037] like Figure 4 As shown, this embodiment provides a fuel cell bipolar plate. The difference between this bipolar plate and the comparative example 1 is that a ridge groove 24 is provided on the top surface of the cathode plate flow channel ridge 22. The ridge groove 24 is located in the middle of the top surface of the flow channel ridge 22 and has a width of 0.8 mm and a depth of 0.6 mm. Figure 5 As shown, the performance test of the fuel cell containing the fuel cell bipolar plates of Comparative Example 1 and Example 1 was carried out. The results showed that the fuel cell performance increased from 0.65V@0.4A / cm 2 Increased to 0.66V@0.5A / cm 2 , which has been significantly improved. That is, after the current density of the performance test is increased, the voltage of Example 1 does not change significantly, which shows that the battery performance has been significantly improved.

[0038] Example 2

[0039] like Figure 6 As shown, this embodiment provides a fuel cell bipolar plate, which is made by metal stamping process. The air flow channel 21 in the bipolar plate is 1.6mm wide, and the top surface of the cathode plate flow channel ridge 22 is provided with a ridge groove 24, which is 0.8mm wide and 0.5mm deep. The performance test of the fuel cell containing the fuel cell bipolar plates of Comparative Example 1 and Example 2 shows that the fuel cell performance is improved from 0.65V@0.4A / cm 2 Increased to 0.67V@0.5A / cm 2 At the same time, since the bipolar plates of this embodiment are made by metal stamping process, one side of the cathode plate is the air flow channel 21, and the other side is stamped to form the cooling flow channel 25, the heat dissipation area is more than doubled compared with that of embodiment 1, the heat dissipation efficiency of the battery is higher, and it can work stably in a wider temperature range. Figure 7As shown, the performance of the fuel cell containing the fuel cell bipolar plate of this embodiment improves as the battery temperature increases. The battery voltage is stable below 64°C and the performance is excellent.

[0040] In summary, the fuel cell cathode plate flow field structure provided by the present invention features a ridge groove on the top surface of the flow channel ridge. This ridge groove is parallel to the air flow channel and communicates with the outside at both ends, allowing air to flow through the ridge groove and react on the membrane electrode at the top of the flow channel ridge to produce water. Furthermore, due to the relatively small depth of the ridge groove, the resistance to air flow within the ridge groove is relatively high, making it difficult to remove moisture from the membrane electrode at the top of the ridge groove, thereby increasing the humidity of the membrane electrode.

[0041] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. An open air-cooled fuel cell cathode plate flow field structure, wherein a membrane electrode is provided on the top of the fuel cell cathode plate flow field structure, characterized in that: The fuel cell cathode plate flow field structure includes: a plurality of air flow channels arranged in parallel, the air flow channels extending along the width direction of the fuel cell cathode plate, and a flow channel ridge formed between two adjacent air flow channels; A ridge groove for air flow is provided on the top surface of the flow channel ridge. The ridge groove is parallel to the air flow channel and has a depth smaller than that of the air flow channel, so that air can flow between the flow channel ridge and the membrane electrode and react on the membrane electrode to generate water; both ends of the ridge groove are connected to the outside; the depth ratio of the ridge groove to the air flow channel is 1:2-1:10; the width of the ridge groove is smaller than that of the air flow channel, and the width ratio of the ridge groove to the air flow channel is 1:2-1:3.

5.

2. The fuel cell cathode plate flow field structure according to claim 1, wherein: The ridge groove has a depth of 0.4 mm to 0.8 mm and a width of 0.4 mm to 1.1 mm.

3. An open air-cooled fuel cell bipolar plate, characterized in that: include: A cathode plate and an anode plate, wherein the cathode plate has the fuel cell cathode plate flow field structure according to any one of claims 1-2.

4. The fuel cell bipolar plate according to claim 3, wherein: The cathode plate and the anode plate are made by metal stamping process.

5. The fuel cell bipolar plate according to claim 4, wherein: The cathode plate and the anode plate are fixed together by welding or adhesive injection to form a fuel cell bipolar plate.

6. The fuel cell bipolar plate according to claim 5, wherein: The cathode plate and the anode plate are made by adopting a graphite carving process.

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