A fuel cell cathode, bipolar plate structure and design method

Abstract

The present invention belongs to the field of fuel cell bipolar plate design, and specifically relates to a fuel cell cathode, bipolar plate structure and design method. The process takes into account the bipolar plate structural design within the flow channel and within the rib and the necessity of these two designs. The necessity of the design within the flow channel is identified by evaluating the impact of increasing overall blockage on battery performance. In the design within the flow channel, the impact of obstructions in different areas and their synergistic effect with obstructions in other areas on PEMFC performance are taken into account. The blocking effects in different areas are fully designed, the impact of the design method and position of a single rib structure on battery performance is taken into account, and the impact on battery performance after expanding it to multiple ribs is evaluated. The cathode bipolar plate is designed based on this structural design method, which can improve cathode oxygen transmission and increase oxygen distribution uniformity, improve cathode drainage capacity and alleviate flooding, and significantly increase the net output power of the fuel cell under the premise of effectively limiting pumping power.

Description

Technical Field

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

[0002] Dependence on fossil fuels has led to severe energy consumption and environmental pollution, making the energy crisis a pressing issue. Proton exchange membrane fuel cells (PEMFCs) convert chemical energy into electrical energy, offering advantages such as high power density, low operating temperature, fast dynamic response, and zero pollution. They are promising energy conversion devices with broad application prospects. Bipolar plates are key components of PEMFCs, playing a crucial role in the transport of reactants and the removal of liquid water.

[0003] Conventional PEMFC flow fields include serpentine, parallel, point, and interdigitated flow fields. Compared to other flow fields, the serpentine flow field, with its superior output performance and drainage capabilities, has become a benchmark for new flow field designs, inspiring research on optimizing its size and configuration. Although these structural optimizations have improved cell performance, traditional serpentine flow fields still cannot meet the requirements of low-voltage applications.

[0004] In 2014, Toyota proposed a three-dimensional fine-grid flow field that effectively improved mass transfer and drainage in PEMFCs at low voltages, prompting interest in high-performance three-dimensional flow fields. Given the difficulty of fabrication, the most practical three-dimensional flow field is one that incorporates obstructions within the flow channels. While adding obstructions can effectively improve cell performance, the significant heterogeneity within the PEMFC results in significant variations in the impact of obstructions installed at different locations. Therefore, it is necessary to rationally design the distribution of the obstruction effect by considering the impact of obstruction location and its synergistic effects with obstructions in other regions on PEMFC performance to improve the net output power of the PEMFC. Furthermore, the compression of the gas flow path by obstructions can result in a high pressure drop, leading to significant pumping work. Therefore, it is necessary to rationally design the rib structure between the flow channels to reduce power losses and improve mass transfer and drainage beneath the ribs. However, this process is cumbersome and complex, requiring a systematic approach to the structural design of the cathode bipolar plate. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a structural design method for a fuel cell cathode bipolar plate. In the structural design method for a fuel cell cathode bipolar plate, after completing the area division and determining the structural design method of the flow channel and the ribs, the influence of the overall blocking effect improvement is first evaluated to determine whether an in-flow channel design is needed; in the in-flow channel design, based on the evaluation of the impact of each area, the blocking effect of the area with the most significant performance impact is first designed, and then, considering the synergistic effect on the PEMFC performance, the optimal blocking effect design in other areas is determined to improve the net output power of the PEMFC; then, the target area requiring rib structure design is determined, and within the target area, the optimal design of a single rib is first determined, and then the strategy is expanded and the optimal design of multiple ribs is determined to reduce power loss and enhance mass transfer and drainage under the ribs.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: a method for designing a cathode bipolar plate structure of a fuel cell, comprising the following steps:

[0007] S1. Divide the cathode bipolar plate of the fuel cell into multiple areas and determine the structural design method for increasing the blocking effect in the flow channel and adjusting the flow path in the ribs;

[0008] S2. Determine whether increasing the overall blocking effect can continuously improve battery performance; if the overall blocking effect increases to a certain level and the performance cannot be further improved, execute S3; otherwise, execute S8;

[0009] S3. increasing the blocking effect of each region separately and evaluating the effect of the increased blocking of each region on the fuel cell performance;

[0010] S4. Design the blocking effect of the area that has the most significant impact on battery performance based on the evaluation results of S3 to obtain the optimal blocking design;

[0011] S5. If increasing the blocking effect of other areas except the area with the most significant impact on battery performance can improve performance, execute S6; otherwise, execute S7;

[0012] S6. Increase the blocking effect in other areas and determine the optimal blocking design;

[0013] S7. For areas where increasing the blocking effect does not improve battery performance, reducing the blocking effect in the area and determining an optimal design;

[0014] S8. Determine the target area requiring rib structure design based on the distribution of oxygen and liquid water in the fuel cell;

[0015] S9. Determine the optimal design of a single rib by comparing the effects of different structural design methods and positions of a single rib on battery performance;

[0016] S10. In the area where rib structure design is required, determine the optimal design among the multiple ribs by evaluating the impact on battery performance after extending the optimal design in a single rib to multiple ribs.

[0017] Furthermore, in S1, from the inlet to the outlet of the three-serpentine flow field are area one, area two, area three, area four and area five respectively. A rectangular guide block is designed in the flow channel to achieve blockage, and an auxiliary flow channel is designed in the rib.

[0018] Furthermore, the influence of the blockage effect of each area on the fuel cell performance is determined based on the impact on the net output power of the fuel cell, and the area with the most significant impact on the fuel cell performance is obtained; rectangular guide blocks are set in the flow channels in area one, area two, area three, and area four, and rectangular guide blocks are set in flow channels one and two in area five.

[0019] Furthermore, by analyzing the oxygen molar concentration and liquid saturation distribution at the interface between the cathode gas diffusion layer and the catalyst layer, it is determined that the area where the hypoxia and water flooding occur is the area where the auxiliary flow channel is opened, and the auxiliary flow channel is opened in this area.

[0020] Furthermore, the net output power and pumping power of the fuel cell under different rib structure design modes corresponding to the auxiliary flow channel opening form are calculated to obtain the optimal auxiliary flow channel opening position and geometric dimensions.

[0021] The present invention also provides a fuel cell cathode bipolar plate structure obtained by the above-mentioned design method, adopting a three-serpentine flow field, which is divided into five areas, namely area one, area two, area three, area four and area five from the flow field inlet to the outlet, each area contains three flow channels, namely flow channel one, flow channel two and flow channel three from the flow field outlet to the inlet, and ribs between the flow channels; a rectangular guide block is arranged in the flow channel, the width of the rectangular guide block is the same as the width of the flow channel, the rectangular guide blocks of flow channel one and flow channel two in area five have the same height, no rectangular guide block is arranged in flow channel three in area five, the height of the rectangular guide block in the flow channel in area four is less than the height of the rectangular guide blocks of flow channel one and flow channel two in area five, the height of the rectangular guide blocks in the flow channels in area one, area two and area three are the same, and less than the height of the rectangular guide block in the flow channel in area four; an auxiliary flow channel is opened on the rib in area five; the auxiliary flow channel is parallel to the flow channel.

[0022] Furthermore, the auxiliary flow channel corresponding to flow channel one is opened on the inner side of the rib close to the edge, and the auxiliary flow channel corresponding to flow channel two is opened on the side of the ribs on the left and right sides near flow channel two. The starting positions of the three auxiliary flow channels are located at the same cross-section of the flow channels, and the entrance of the auxiliary flow channel is located in front of the third rectangular guide block in flow channel one and flow channel two.

[0023] Furthermore, the height of the rectangular guide blocks in the flow channel in area five is 0.9 times the height of the flow channel, the height of the rectangular guide blocks in the flow channel in area four is 0.8 times the height of the flow channel, and the height of the rectangular guide blocks in the flow channels in areas one, two and three is 0.6 times the height of the flow channel.

[0024] Furthermore, the width of the auxiliary flow channel is 0.4 times the width of the flow channel, and the height of the auxiliary flow channel is the same as the height of the flow channel.

[0025] At the same time, a fuel cell cathode can be provided, which adopts the above-mentioned fuel cell cathode bipolar plate structure.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention takes into account the structural design of bipolar plates within the flow channel and within the ribs and the necessity of these two designs. The necessity of the design within the flow channel is identified by evaluating the impact of increasing the overall blockage on battery performance. In the design within the flow channel, the influence of obstructions in different areas and their synergistic effect with obstructions in other areas on the PEMFC performance are considered. The influence of the design method and position of the single rib structure on the battery performance is considered, and the impact on the battery performance after expanding it to multiple ribs is evaluated. The design of the cathode bipolar plate based on this structural design method can reduce power loss and enhance mass transfer and drainage under the ribs.

[0028] Furthermore, the present invention fully designs the blocking effects in different areas. In the rib structure design, the necessity and target areas of the rib design are determined by analyzing the oxygen-deficient and flooded areas. This can improve cathode oxygen transmission and increase the uniformity of oxygen distribution, improve the cathode drainage capacity and alleviate flooding, and significantly increase the net output power of the fuel cell while effectively limiting the pumping power. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] To more intuitively and clearly illustrate the embodiments of this specification, the following is a brief illustration of the embodiments of this specification. Obviously, the following drawings are only some of the embodiments of this specification. For those of ordinary skill in the art, all other embodiments obtained without creative effort are within the scope of protection of this invention.

[0030] Figure 1 This is a schematic diagram of a structural design method for a cathode bipolar plate of a fuel cell according to an embodiment of the present invention;

[0031] Figure 2 2 is a schematic structural diagram of a conventional three-serpentine flow field according to an embodiment of the present invention;

[0032] Figure 3 1 is a top view of a conventional three-serpentine flow field and a schematic diagram of its area division according to an embodiment of the present invention;

[0033] Figure 4 The fuel cell equipped with the three-serpentine flow field according to the embodiment of the present invention gradually improves the net output power and pumping power as the overall blocking effect in all areas gradually improves;

[0034] Figure 5 The fuel cell equipped with three serpentine flow fields according to the embodiment of the present invention can no longer further improve the overall blocking effect of the battery performance, but improves the blocking effect of each area to increase the output power, pumping power and net output power of the PEMFC;

[0035] Figure 6 The graphs are of the oxygen molar concentration distribution at the interface between the cathode gas diffusion layer (GDL) and the catalyst layer (CL) for a fuel cell according to an embodiment of the present invention, when equipped with a conventional three-serpentine flow field, a three-serpentine flow field with a blockage height of 0.8 mm before flow channel design, and a three-serpentine flow field after flow channel design.

[0036] Figure 7 The figure shows the distribution cloud of liquid saturation at the interface between the cathode gas diffusion layer (GDL) and the catalyst layer (CL) when the fuel cell according to the embodiment of the present invention is equipped with a conventional three-serpentine flow field, a three-serpentine flow field with a blockage height of 0.8 mm before the flow channel design, and a three-serpentine flow field after the flow channel design is completed.

[0037] Figure 8 Schematic diagram of different rib structure designs in a single rib near the flow field outlet for completing a three-serpentine flow field designed within a flow channel according to an embodiment of the present invention;

[0038] Figure 9 The net output power and pumping power of the fuel cell under different rib structure design modes are shown in the single rib near the flow field outlet of the single rib near the flow field outlet of the single rib in the embodiment of the present invention.

[0039] Figure 10 2. It is a schematic structural diagram of different rib structure design positions under the optimal design method in a single rib near the flow field outlet in an embodiment of the present invention that completes the three-serpentine flow field designed in the flow channel;

[0040] Figure 11 The net output power and pumping power of the fuel cell at different rib structure design positions under the optimal design mode in a single rib near the flow field outlet of the three-serpentine flow field designed in the flow channel of an embodiment of the present invention;

[0041] Figure 12 2. It is a schematic structural diagram of different rib structure designs among multiple ribs near the flow field outlet in a three-serpentine flow field designed in a flow channel according to an embodiment of the present invention;

[0042] Figure 13The three-serpentine flow field designed in the flow channel of the embodiment of the present invention is completed. Among the multiple ribs near the flow field outlet, the net output power and pumping power of the fuel cell under different rib structure designs;

[0043] Figure 14 This is a structural design method based on a fuel cell cathode bipolar plate according to an embodiment of the present invention, which completes a schematic diagram of a resistance-adjusted three-serpentine flow field structure with an inner channel design and an inner rib design. DETAILED DESCRIPTION

[0044] The following will be combined with the accompanying drawings of the embodiments of this specification to specifically analyze the specific technical solutions in the embodiments of this specification and provide a more detailed and comprehensive description. It is obvious that the following description is only a part of the present embodiment and does not describe all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] It is hereby noted that, unless otherwise defined, all technical and scientific terms used in the embodiments and accompanying drawings of this specification have the same meanings as commonly understood by persons skilled in the art of the relevant technical fields of this invention. Furthermore, the terms "including," "having," and any variations thereof in the embodiments and accompanying drawings of this specification indicate an inclusive, non-exclusive, relationship.

[0046] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "one side", "one end", "one side" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0047] The present invention provides a structural design method for a cathode bipolar plate of a fuel cell, such as Figure 1As shown, it includes: step 1, regional division and determination of structural design method, dividing the bipolar plate into regions according to its structural characteristics and design accuracy, obtaining multiple regions that are convenient for subsequent design, and determining the structural design methods of increasing the blocking effect in the flow channel and adjusting the flow path in the rib respectively; step 2, judging whether increasing the overall blocking effect can continuously improve the battery performance, gradually improving the overall blocking effect in all regions, calculating the net output power of the fuel cell under different designs as a performance indicator, judging whether increasing the overall blocking effect can continuously improve the battery performance, if it can continuously improve, there is no need to perform the flow channel design, and directly proceed to step 8, if the overall blocking effect is increased to one If the performance cannot be further improved after reaching a certain level, it is necessary to carry out in-channel design and proceed to step three; Step three, evaluate the impact of different areas, based on the overall blocking effect that cannot continue to improve battery performance, improve the blocking effect of each area respectively, and evaluate the impact of the increase in blockage in each area on the fuel cell performance; Step four, design the blocking effect of the area with the most significant impact on battery performance, for the area with the most significant positive impact on fuel cell performance determined in the impact evaluation of different areas, improve the blocking effect in the area and determine the best design; Step five, determine whether increasing the blocking effect in other areas can improve performance, for other areas except the most significant area , respectively judge whether increasing the blocking effect in the area can improve the battery performance, if it can improve the performance, proceed to step six, if not, proceed to step seven; step six, increase the blocking effect and determine the best design, for the area where the battery performance can be improved after increasing the blocking effect, increase the blocking effect in the area and determine the best design; step seven, reduce the blocking effect and determine the best design, for the area where the battery performance cannot be improved after increasing the blocking effect, reduce the blocking effect in the area and determine the best design; step eight, determine the target area that needs further rib structure design, calculate and analyze the oxygen and Liquid water distribution, determine the areas where hypoxia and flooding still exist, and regard them as target areas that require further rib structure design; Step 9, determine the optimal design of a single rib. In the area where rib structure design is required, determine the optimal design of a single rib by comparing the effects of different structural design methods and positions of a single rib on battery performance; Step 10, determine the optimal design of multiple ribs. In the area where rib structure design is required, determine the optimal design of multiple ribs by evaluating the effects of extending the optimal design of a single rib to multiple ribs on battery performance; Among them, steps 3 to 7 are in-channel design, and steps 8 to 10 are in-rib design.

[0048] Figure 2 This is a schematic diagram of the structure of a conventional three-serpentine flow field in an embodiment of the present invention, which will be used later. Figure 1The structural design method of the fuel cell cathode bipolar plate shown is combined with the three-dimensional multiphase numerical simulation of PEMFC to present the complete process of structural design of the three-serpentine flow field.

[0049] Execute step one, Figure 3 It is a top view of a conventional three-serpentine flow field of an embodiment of the present invention and a schematic diagram of its regional division, which divides the three-serpentine flow field into five areas, which are area one, area two, area three, area four and area five from the flow field inlet to the outlet, and each area contains three flow channels, which are flow channel one, flow channel two and flow channel three from the flow field outlet to the inlet, and the adjacent areas are connected by the turning of the flow channels, and there are ribs between the flow channels. In addition, in this structural design, the structural design in the flow channel is to add rectangular guide blocks, and six blocks are arranged in each flow channel of each area, while the structural design in the rib is to add auxiliary flow channels connected to the main flow channel. Preferably, the height and width of the main flow channel are both 1mm, the rib width is 1mm, the block length and width are both 1mm, the spacing between the rectangular guide blocks is 2mm, and the width of the auxiliary flow channel is 0.4mm.

[0050] Execute step 2. Figure 4 The fuel cell equipped with three serpentine flow fields according to the embodiment of the present invention gradually improves the net output power and pumping power as the overall blocking effect in all areas gradually increases. Figure 4 It can be seen that as the blockage height increases from 0.8mm to 0.9mm, the pumping power of the PEMFC increases significantly by 2.6 times, and the increase in output power is largely offset by power loss, so that the net output power of the PEMFC corresponding to the overall block height of 0.9mm is only 0.3% higher than the net output power at 0.8mm. Therefore, in order to further improve the net output power of the PEMFC while limiting the pumping power, the blockage height in different areas must be optimized.

[0051] Execute step three. Figure 5 The invention relates to the fuel cell equipped with three serpentine flow fields, which, on the basis of the overall blocking effect that cannot further improve the battery performance, improves the blocking effect of each area to increase the output power, pumping power and net output power of the PEMFC. Figure 5 It can be seen that in Region 1, the increase in pumping power due to the increased blockage height exceeds the increase in output power, resulting in a decrease in the PEMFC's net output power. In contrast, increasing the blockage height to 0.9 mm in other regions improves the cell's net output power, particularly in areas closer to the flow field outlet. Notably, increasing the blockage height in Region 5 has the greatest positive impact on the fuel cell's net output power, so detailed design of the blockage height in Region 5 is a priority.

[0052] Execute step 4 and conduct detailed design of the blockage heights in the three flow channels of region 5 to obtain the optimal blockage design in this region. The optimal blockage heights in flow channels 1, 2, and 3 in region 5 are 0.9 mm, 0.9 mm, and 0, respectively. If the blockage heights in flow channels 1 and 2 are further increased from 0.9 mm, the pumping power will increase significantly, thereby limiting the increase in the net output power of the PEMFC. The optimal blockage height in flow channel 3 is 0 because removing the blockage in flow channel 3 can increase the pressure drop between regions 4 and 5, thereby promoting mass transfer and drainage under the ribs. This makes it possible to significantly reduce the pumping power while maintaining the net output power of the PEMFC after removing the blockage in flow channel 3.

[0053] Executing step 5, increasing the blockage effect in all regions except region 5 revealed no improvement in net output power. Therefore, step 7 was performed on regions 4, 3, 2, and 1. Reducing the blockage height in region 4 reduced the PEMFC net output power, so the blockage height in region 4 remained unchanged at 0.8 mm. Reducing the blockage height in regions 3, 2, and 1 revealed optimal cell performance when the blockage height was 0.6 mm. Therefore, the optimal blockage heights for regions 4, 3, 2, and 1 were 0.8 mm, 0.6 mm, 0.6 mm, and 0.6 mm, respectively.

[0054] Execute step eight. Figure 6 and Figure 7 The following are the distribution cloud diagrams of oxygen molar concentration and liquid saturation at the interface between the cathode gas diffusion layer (GDL) and the catalyst layer (CL) when the fuel cell of the embodiment of the present invention is equipped with a conventional three-serpentine flow field, a three-serpentine flow field with a blockage height of 0.8 mm before the flow channel design, and a three-serpentine flow field after the flow channel design is completed. Figure 6 and Figure 7 It can be seen that after the in-channel design, the area near the flow field outlet still has obvious hypoxia and water flooding phenomena, so it is regarded as a target area that requires further rib structure design.

[0055] Execute step nine. Figure 8 1 is a schematic diagram of a structure of different rib structure designs in a single rib near the flow field outlet for completing the three-serpentine flow field designed in the flow channel according to an embodiment of the present invention. Figure 9 is the net output power and pumping power of the fuel cell when these rib structure designs are applied. Figure 9 It can be seen that the auxiliary flow channel design methods that branch off from the flow channel in area 5 and extend to the flow field outlet, namely Method 1, Method 2 and Method 3, can improve the net output power of PEMFC. Therefore, the influence of Method 1, which has the most significant effect, under different design positions was further explored. Figure 101 is a schematic structural diagram of different rib structure design positions under the optimal design method in a single rib near the flow field outlet of a three-serpentine flow field designed in a flow channel according to an embodiment of the present invention, and Figure 11 is the net output power and pumping power of the fuel cell when these rib structure design positions are applied. Figure 11 It can be seen that as the flow diversion point of the auxiliary flow channel gradually moves away from the flow field outlet, the net output power of the PEMFC first increases and then decreases. Taking into account the net output power and pumping power, positions 3 and 4 are considered to be the better design positions for method 1.

[0056] Execute step 10. Figure 12 1 is a schematic diagram of a structure of different rib structures in a plurality of ribs near the outlet of a three-serpentine flow field designed in a flow channel according to an embodiment of the present invention. Figure 13 is the net output power and pumping power of the fuel cell when these rib structure designs are applied. Figure 13 It can be seen that expanding the auxiliary flow channel design from a single rib to multiple ribs can further improve the net output power of the PEMFC. Taking into account the net output power and pumping power, the structure corresponding to Design 6 is the optimal design among the multiple ribs.

[0057] Figure 14 This is a structural design method for a fuel cell cathode bipolar plate based on an embodiment of the present invention. It demonstrates a schematic diagram of a resistance-adjusted three-serpentine flow field structure, featuring both in-channel and in-rib designs. A non-uniform blockage height design is employed within the flow channels, while auxiliary flow channels are incorporated within the multiple ribs near the flow field outlet. Simulations show that the resistance-adjusted three-serpentine flow field can increase the net output power of a PEMFC by 19.0% compared to a conventional three-serpentine flow field. This significantly exceeds the 10.8% achieved by a flow field with a uniform blockage height of 0.8 mm before design. Furthermore, the pumping power is reduced by 32.4% compared to a uniformly blocked flow field.

[0058] At the same time, the fuel cell cathode bipolar plate structure fuel cell cathode obtained by the design method of the present invention can be used.

[0059] In summary, the present invention provides a structural design method for a fuel cell cathode bipolar plate, wherein the process takes into account the bipolar plate structural design within the flow channel and within the rib and the necessity of these two designs, and identifies the necessity of the design within the flow channel by evaluating the impact of increasing the overall blockage on the battery performance. In the design within the flow channel, the impact of blockages in different areas and their synergistic effect with blockages in other areas on the PEMFC performance are considered, thereby fully designing the blockage effects in different areas. In the rib structure design, the necessity and target areas of the design within the rib are determined by analyzing the oxygen-deficient and flooded areas, and the impact of the design mode and position of a single rib structure on the battery performance is considered, and the impact of its expansion to multiple ribs on the battery performance is evaluated. The cathode bipolar plate is designed based on this structural design method, which can improve the cathode oxygen transmission and improve the uniformity of oxygen distribution, improve the cathode drainage capacity and alleviate the flooding phenomenon, and significantly improve the net output power of the fuel cell under the premise of effectively limiting the pumping power, thereby obtaining a fuel cell cathode bipolar plate structure. Specifically, a three-serpentine flow field is adopted as the basic flow field, and the three-serpentine flow field is divided into five areas, which are area one, area two, area three, area four and area five from the flow field inlet to the outlet, and each area contains three flow channels, which are flow channel one, flow channel two and flow channel three from the flow field outlet to the inlet, and there are ribs between the flow channels; in the designed resistance-adjusted three-serpentine flow field, a rectangular guide block is set in the flow channel, and the width of the rectangular guide block is the same as the width of the flow channel, the rectangular guide blocks of flow channel one and flow channel two in area five have the same height, no rectangular guide block is set in flow channel three in area five, the height of the rectangular guide block in the flow channel in area four is less than the height of the rectangular guide blocks of flow channel one and flow channel two in area five, the height of the rectangular guide blocks in the flow channels in area one, area two and area three are the same, and Smaller than the height of the rectangular guide block in the flow channel in area four; the height of the rectangular guide block in the flow channel in area five is 0.9 times the height of the flow channel, the height of the rectangular guide block in the flow channel in area four is 0.8 times the height of the flow channel, and the height of the rectangular guide block in the flow channels in areas one, two and three is 0.6 times the height of the flow channel; multiple ribs in area five are provided with auxiliary flow channels that are parallel to the main channel, have a width of 0.4 times the width of the main channel and have the same height as the main channel, the auxiliary flow channel corresponding to flow channel one is provided on the inner side of the rib close to the edge, and the two auxiliary flow channels corresponding to flow channel two are respectively provided on one side of the ribs on both sides near flow channel two, the starting positions of the three auxiliary flow channels are located at the same cross-section of the flow channel, and the entrance of the auxiliary flow channel is located in front of the third rectangular guide block in flow channel one and flow channel two.

[0060] The above description is merely an illustration of the preferred embodiments of the present invention and is not intended to limit the present invention. Persons skilled in the art will readily be able to make various modifications and variations to the aforementioned embodiments. Therefore, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for designing a fuel cell cathode bipolar plate structure, characterized in that: The following steps are involved: S1. Divide the fuel cell cathode bipolar plate into multiple regions and determine a structural design approach to increase the blocking effect within the flow channel and adjust the flow path within the ribs. The fuel cell cathode bipolar plate is based on a three-serpentine flow field, with regions 1, 2, 3, 4, and 5 from the inlet to the outlet of the three-serpentine flow field. Rectangular guide blocks are designed within the flow channel to achieve blocking, and auxiliary flow channels are designed within the ribs. S2. Determine whether increasing the overall blocking effect can continuously improve battery performance; if the overall blocking effect increases to a certain level and the performance cannot be further improved, execute S3; otherwise, execute S8; S3. increasing the blocking effect of each region separately and evaluating the effect of the increased blocking of each region on the fuel cell performance; S4. Design the blocking effect of the area that has the most significant impact on battery performance based on the evaluation results of S3 to obtain the optimal blocking design; S5. If increasing the blocking effect of other areas except the area with the most significant impact on battery performance can improve performance, execute S6; otherwise, execute S7; S6. Increase the blocking effect in other areas and determine the optimal blocking design; S7. For areas where increasing the blocking effect does not improve battery performance, reducing the blocking effect in the area and determining an optimal design; S8. Determine the target area requiring rib structure design based on the distribution of oxygen and liquid water in the fuel cell; S9. Determine the optimal design of a single rib by comparing the effects of different structural design methods and positions of a single rib on battery performance; S10. In the area where rib structure design is required, determine the optimal design among the multiple ribs by evaluating the impact on battery performance after extending the optimal design in a single rib to multiple ribs.

2. The method for designing a fuel cell cathode bipolar plate structure according to claim 1, wherein: The influence of the blockage effect of each area on the fuel cell performance is determined based on the impact on the net output power of the fuel cell, and the area with the most significant impact on the fuel cell performance is obtained; rectangular guide blocks are set in the flow channels in areas one, two, three, and four, and rectangular guide blocks are set in flow channels one and two in area five.

3. The method for designing a fuel cell cathode bipolar plate structure according to claim 1, wherein: By analyzing the oxygen molar concentration and liquid saturation distribution at the interface between the cathode gas diffusion layer and the catalyst layer, it is determined that the area where the oxygen deficiency and water flooding occur is the area where the auxiliary flow channel is opened, and the auxiliary flow channel is opened in this area.

4. The method for designing a fuel cell cathode bipolar plate structure according to claim 3, wherein: The net output power and pumping power of the fuel cell under different rib structure design methods corresponding to the auxiliary flow channel opening form are calculated, and the optimal auxiliary flow channel opening position and geometric dimensions are obtained.

5. The fuel cell cathode bipolar plate structure obtained by the design method according to any one of claims 1 to 4, characterized in that: A three-serpentine flow field is adopted, and the three-serpentine flow field is divided into five areas, which are area one, area two, area three, area four and area five from the flow field entrance to the exit. Each area contains three flow channels, which are flow channel one, flow channel two and flow channel three from the flow field exit to the entrance, and there are ribs between the flow channels. Rectangular guide blocks are set in the flow channels, and the width of the rectangular guide blocks is the same as the width of the flow channels. The rectangular guide blocks of flow channels one and two in area five have the same height. No rectangular guide blocks are set in flow channel three in area five. The height of the rectangular guide blocks in the flow channel in area four is less than the height of the rectangular guide blocks of flow channels one and two in area five. The height of the rectangular guide blocks in the flow channels in areas one, two and three are the same and less than the height of the rectangular guide blocks in the flow channel in area four. An auxiliary flow channel is opened on the rib in area five. The auxiliary flow channel is parallel to the flow channel.

6. The fuel cell cathode bipolar plate structure according to claim 5, characterized in that: The auxiliary flow channel corresponding to flow channel one is opened on the inner side of the rib close to the edge, and the auxiliary flow channel corresponding to flow channel two is opened on the side of the ribs on the left and right sides near flow channel two. The starting positions of the three auxiliary flow channels are located in the same cross-section of the flow channels, and the entrance of the auxiliary flow channel is located in front of the third rectangular guide block in flow channel one and flow channel two.

7. The fuel cell cathode bipolar plate structure according to claim 5, characterized in that: The height of the rectangular guide blocks in the flow channel in area five is 0.9 times the height of the flow channel, the height of the rectangular guide blocks in the flow channel in area four is 0.8 times the height of the flow channel, and the height of the rectangular guide blocks in the flow channels in areas one, two and three is 0.6 times the height of the flow channel.

8. The fuel cell cathode bipolar plate structure according to claim 5, characterized in that: The width of the auxiliary flow channel is 0.4 times the width of the flow channel, and the height of the auxiliary flow channel is the same as the height of the flow channel.

9. A fuel cell cathode, characterized in that: A fuel cell cathode bipolar plate structure according to any one of claims 6 to 8 is adopted.

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