Bipolar Plate Structure and Fuel Cell

Abstract

The present invention relates to the technical field of fuel cells, and particularly to a bipolar plate structure and a fuel cell. The bipolar plate structure includes a bipolar plate body, on which a reaction gas inlet and a reaction gas outlet are spaced apart. The area of the reaction gas inlet is smaller than that of the reaction gas outlet. A flow field communicating with the reaction gas inlet and the reaction gas outlet is provided on the side surface of the bipolar plate body. The flow field includes a plurality of first flow channels arranged at intervals and a plurality of second flow channels arranged at intervals. The first flow channels extend along a first direction, the second flow channels are in a wavy shape, and each second flow channel communicates with all the first flow channels. The second flow channels extend along a second direction that forms an angle with the first direction. The present invention can enable the reaction gas to be evenly distributed in the flow field, reduce the pressure drop at the inlet and outlet, enable the generated water to be discharged in time, and improve the efficiency of the fuel cell.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to a bipolar plate structure and a fuel cell. Background Art

[0002] A proton exchange membrane fuel cell is an energy conversion device with fast startup time, light weight, clean, environmentally friendly and efficient. Hydrogen generates electrons and hydrogen protons under the action of a catalyst and a proton exchange membrane, and oxygen combines with hydrogen protons and electrons to generate water under the action of a catalyst and a proton exchange membrane, while generating a working current. The power generation efficiency of a proton exchange membrane fuel cell is as high as over 60% and is not restricted by the Carnot cycle. The electrochemical reaction only produces water, greatly solving the problems of environmental pollution and energy shortage.

[0003] The bipolar plate is one of the key components of a proton exchange membrane fuel cell. Its functions include supporting the proton exchange membrane, evenly distributing reaction gases, collecting and conducting electrons, etc. Flow channels are provided on both sides of the bipolar plate, and a proton exchange membrane is provided between the anode plate of the bipolar plate and the cathode plate of the adjacent bipolar plate. The flow field structure design of the bipolar plate is crucial for the performance of the fuel cell. A reasonable design enables the reaction gases to be evenly distributed in the flow field, accelerates the discharge of the generated water, and improves the discharge performance of the fuel cell. Traditional flow field structures include serpentine flow fields, parallel flow fields, interdigitated flow fields, and dot flow fields. The serpentine flow field has a large pressure drop at the inlet and outlet, can discharge the generated water in time, but the gas concentration gradient is also large, resulting in uneven current distribution. The parallel flow field is simple to process, but it is difficult to discharge water. The flow channels of the interdigitated flow field are discontinuous, and the air pressure inside the flow channels is large. Although it is easy to discharge water, it is also easy to damage the flow channels and reduce the efficiency of the fuel cell.

[0004] Therefore, a bipolar plate structure and a fuel cell are needed to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a bipolar plate structure and a fuel cell, which can enable the reaction gases to be evenly distributed in the flow field, reduce the pressure drop at the inlet and outlet, and enable the generated water to be discharged in time, improving the efficiency of the fuel cell.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] Bipolar plate structure, comprising: a bipolar plate body, on which a reaction gas inlet and a reaction gas outlet are spaced apart, and the area of the reaction gas inlet is smaller than that of the reaction gas outlet; a flow field is provided on the side surface of the bipolar plate body and is communicated with the reaction gas inlet and the reaction gas outlet, the flow field includes a plurality of first flow channels arranged at intervals and a plurality of second flow channels arranged at intervals, the first flow channels extend along a first direction, the first direction is parallel to the direction of reaction gas flow, the second flow channels are in a wavy shape, each second flow channel is communicated with all the first flow channels, and the second flow channels extend along a second direction which forms an angle with the first direction.

[0008] Further, a first distribution area is provided between the reaction gas inlet and the flow field, and a first dot matrix is evenly distributed in the first distribution area, and the first dot matrix is arranged on the bipolar plate body.

[0009] Further, the flow field includes a shunt area, a direct current area and a confluence area, the shunt area, the direct current area and the confluence area are arranged in sequence along the first direction, both the shunt area and the confluence area are trapezoidal, one end of the shunt area communicated with the first distribution area is smaller than one end of the shunt area communicated with the direct current area, and one end of the confluence area communicated with the reaction gas outlet is smaller than one end of the confluence area communicated with the direct current area.

[0010] Further, a first diversion area is provided between the first distribution area and the shunt area, and a plurality of first diversion blocks are convexly arranged at intervals in the first diversion area, and the first diversion blocks are arranged at intervals along the second direction on the bipolar plate body.

[0011] Further, the first diversion block is hexagonal, and each corner of the first diversion block is rounded.

[0012] Further, a second distribution area is provided between the confluence area and the reaction gas outlet, and a second dot matrix is evenly distributed in the second distribution area, and the second dot matrix is arranged on the bipolar plate body.

[0013] Further, a second diversion area is provided between the confluence area and the second distribution area, and a plurality of second diversion blocks are convexly arranged at intervals in the second diversion area, and the second diversion blocks are arranged at intervals along the second direction on the bipolar plate body.

[0014] Further, the first flow channel includes a first section and a second section which are communicated with each other, the first section is communicated with the wave crest of the second flow channel, the second section passes through the wave crest, the diameter of the first section is smaller than that of the second flow channel, and the diameter of the second section is larger than that of the second flow channel.

[0015] Further, a plurality of annular flow channels are formed in the bipolar plate. The annular flow channels communicate with the first flow channels and are located between two adjacent second flow channels.

[0016] A fuel cell includes the bipolar plate structure as described above.

[0017] Advantages of the present invention:

[0018] In the bipolar plate structure provided by the present invention, a reaction gas inlet and a reaction gas outlet are spaced apart on the bipolar plate body. The reaction gas inlet and the reaction gas outlet are connected through a flow field. The flow field includes a plurality of first flow channels and second flow channels. The first flow channels extend along a first direction, and the second flow channels are wavy. Each second flow channel communicates with all the first flow channels. The second flow channels extend along a second direction that forms an angle with the first direction. This enables the flow field to form a vein-like pattern similar to that of plant leaves, creating a multi-stage bifurcated flow field. This allows the reaction gas to be evenly distributed throughout the entire flow field area, increasing the residence time of the reaction gas. The reaction gas can more fully and evenly reach the membrane electrode through diffusion. At the same time, it also helps the unreacted reaction gas to flow back, improving the utilization rate of the reaction gas and facilitating the full progress of the electrochemical reaction. The multi-stage bifurcated flow field increases the speed at which the generated water is discharged from the reaction gas outlet, reduces the pressure drop, and avoids waterlogging. The size of the reaction gas inlet is smaller than that of the reaction gas outlet, which can effectively reduce the pressure drop at the inlet and outlet and improve the performance of the fuel cell.

[0019] The fuel cell provided by the present invention includes the bipolar plate structure as described above, which can evenly distribute the reaction gas in the flow field, reduce the pressure drop at the inlet and outlet, and enable the generated water to be discharged in a timely manner, thereby improving the efficiency of the fuel cell. Description of the Drawings

[0020] Figure 1 is a schematic diagram of the bipolar plate structure of the present invention;

[0021] Figure 2 is a schematic diagram of some of the first flow channels and second flow channels in the bipolar plate structure of the present invention;

[0022] Figure 3 is a schematic diagram of the first flow guiding block in the bipolar plate structure of the present invention.

[0023] In the figure:

[0024] 1, flow field; 11, shunt zone; 12, direct current zone; 13, confluence zone; 2, first distribution zone; 21, first dot matrix; 3, first flow guiding block; 4, reaction gas inlet; 41, reaction gas outlet; 5, second flow guiding block; 6, second distribution zone; 61, second dot matrix; 7, first flow channel; 71, first section; 72, second section; 8, second flow channel; 9, annular flow channel. Detailed Embodiments

[0025] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only for explaining the present invention, rather than limiting the present invention. In addition, it should be noted that, for the sake of convenience of description, only the parts related to the present invention are shown in the drawings, rather than all of them.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0027] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "beneath" and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0028] When using a fuel cell to generate electricity, in order to enable the reaction gas to be evenly distributed in the flow field, reduce the inlet and outlet pressure drops, and enable the generated water to be discharged in time to improve the efficiency of the fuel cell, as Figures 1-3 shown, the present invention provides a bipolar plate structure. The bipolar plate structure includes a bipolar plate body.

[0029] Among them, a reaction gas inlet 4 and a reaction gas outlet 41 are spaced apart on the bipolar plate body, and the area of the reaction gas inlet 4 is smaller than that of the reaction gas outlet 41; a flow field 1 communicating with the reaction gas inlet 4 and the reaction gas outlet 41 is provided on the side surface of the bipolar plate body. The flow field 1 includes a plurality of first flow channels 7 arranged at intervals and a plurality of second flow channels 8 arranged at intervals. The first flow channels 7 extend along a first direction, and the first direction is parallel to the direction of the reaction gas flow. The second flow channels 8 are in a wave shape, and each second flow channel 8 communicates with all the first flow channels 7. The second flow channels 8 extend along a second direction forming an angle with the first direction.

[0030] Through the design of the first flow channel 7 and the second flow channel 8, the flow field 1 is formed into a vein-like shape similar to that of a plant leaf, forming a multi-stage bifurcated flow field 1. This enables the reaction gas to be evenly distributed throughout the entire flow field 1 area, increases the residence time of the reaction gas, allows the reaction gas to reach the membrane electrode more fully and evenly through diffusion, and also helps the unreacted reaction gas to flow back, improving the utilization rate of the reaction gas and facilitating the full progress of the electrochemical reaction. The multi-stage bifurcated flow field 1 increases the speed of the generated water discharged from the reaction gas outlet 41, reduces the pressure drop while avoiding the phenomenon of flooding. The size of the reaction gas inlet is smaller than that of the reaction gas outlet 41, which can effectively reduce the pressure drop at the inlet and outlet and improve the performance of the fuel cell.

[0031] Further, a first distribution area 2 is provided between the reaction gas inlet 4 and the flow field 1. The first distribution area 2 is evenly distributed with a first dot matrix 21, and the first dot matrix 21 is fixedly arranged on the bipolar plate body. By providing the first distribution area 2 and using the first dot matrix 21 to evenly distribute the reaction gas, it can ensure that the reaction gas enters the flow field 1 evenly, making the reaction gas cover the entire flow field 1 area.

[0032] Further, the flow field 1 includes a flow splitting area 11, a direct flow area 12, and a flow confluence area 13. The flow splitting area 11, the direct flow area 12, and the flow confluence area 13 are arranged in sequence along the first direction. Both the flow splitting area 11 and the flow confluence area 13 are trapezoidal. The end of the flow splitting area 11 connected to the first distribution area 2 is smaller than the end of the flow splitting area 11 connected to the direct flow area 12, and the end of the flow confluence area 13 connected to the reaction gas outlet 41 is smaller than the end of the flow confluence area 13 connected to the direct flow area 12. Specifically, the flow splitting area 11 can effectively distribute the reaction gas evenly throughout the entire flow field 1 area; the width of the direct flow area 12 is consistent with the width of the flow field 1 area. The direct flow area 12 has a large area and uniform fluid distribution, resulting in a long residence time of the reaction gas and more sufficient progress of the relevant electrochemical reaction; the width of the flow confluence area 13 gradually decreases along the fluid flow direction. The flow confluence area 13 can collect the reacted gas and the generated water, increasing the discharge speed of the reaction gas and water and avoiding the flooding phenomenon in the battery.

[0033] Further, a first flow guiding area is provided between the first distribution area 2 and the flow splitting area 11. A plurality of first flow guiding blocks 3 are convexly provided at intervals in the first flow guiding area. The first flow guiding blocks 3 are arranged at intervals along the second direction on the bipolar plate body. The first flow guiding blocks 3 can effectively collect the reaction gas in the first distribution area 2 and then evenly distribute it inside the entire flow field 1.

[0034] Further, the first flow guiding block 3 is hexagonal, and each corner of the first flow guiding block 3 is rounded. By rounding the corners, it can ensure the smoothness of the first flow guiding block 3, thus ensuring that the reaction gas flows smoothly from between the adjacent first flow guiding blocks 3 into the flow field 1.

[0035] Further, a second distribution area 6 is provided between the current collecting area 13 and the reaction gas outlet 41. The second distribution area 6 is evenly distributed with a second dot matrix 61, and the second dot matrix 61 is arranged on the bipolar plate body. By providing the second distribution area 6, the reaction gas and water are evenly distributed by the second dot matrix 61, and then discharged through the reaction gas outlet 41.

[0036] Further, a second flow guiding area is provided between the current collecting area 13 and the second distribution area 6. A plurality of second flow guiding blocks 5 are convexly provided at intervals in the second flow guiding area, and the second flow guiding blocks 5 are arranged on the bipolar plate body at intervals along the second direction. The second flow guiding blocks 5 can effectively collect the reaction gas and the generated water in the flow field 1 area, so as to improve the discharge speed of the reaction gas and the generated water and avoid the phenomenon of waterlogging.

[0037] Further, the first flow channel 7 includes a first section 71 and a second section 72 that are connected to each other. The first section 71 is connected to the peak of the second flow channel 8, and the second section 72 passes through the peak. The diameter of the first section 71 is smaller than that of the second flow channel 8, and the diameter of the second section 72 is larger than that of the second flow channel 8. Specifically, in this embodiment, the width of the first section 71 is 1 mm to 2 mm, for example, it can be 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, but is not limited to the listed values; the width of the second section 72 is 2 mm to 4 mm, for example, it can be 2 mm, 3 mm, 4 mm, but is not limited to the listed values; the width of the second flow channel 8 is 1.5 mm to 3 mm, for example, it can be 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3 mm, but is not limited to the listed values; the depths of the first flow channel 7 and the second flow channel 8 are in the range of 0.1 mm to 3 mm, for example, it can be 0.5 mm, 1 mm, 2 mm, 3 mm, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable. The included angle between the second flow channel 8 and the first flow channel 7 is α, and the value range of α is 30° to 75°, for example, it can be 30°, 40°, 50°, 60°, 70°, 75°, but is not limited to the listed values. Through the above settings, using the bionic principle, the first flow channel 7 and the second flow channel 8 are set as a flow channel unit similar to the shape of plant leaf veins. By utilizing the fact that plant leaf veins in nature have the function of reducing the resistance of fluid flow and improving the uniformity of reaction gas distribution, the reaction gas and the generated water can flow and diffuse more easily and evenly inside the flow field 1.

[0038] Furthermore, the bipolar plates are provided with a plurality of annular flow channels 9, which are connected to the first flow channels 7 and are located between two adjacent second flow channels 8. The provision of the annular flow channels 9 allows the first flow channels 7 and the annular flow channels 9 to swirl and connect with each other, increasing the degree of disturbance of the reactant gas, facilitating a more complete and uniform diffusion of the reactant gas to the membrane electrode, while also facilitating the recirculation of unreacted reactant gas, thereby improving the reusability of the reactant gas.

[0039] Furthermore, a cooling water circulation pipeline is provided on the bipolar plate, and cooling water is used to cool the bipolar plate to ensure smooth electrochemical reaction.

[0040] This embodiment also provides a fuel cell, including the above bipolar plate structure, which can evenly distribute the reaction gas in the flow field 1 while reducing the inlet and outlet pressure drop and allowing the generated water to be discharged in time, thereby improving the efficiency of the fuel cell.

[0041] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. Bipolar plate structure, characterized in that, Comprising: A bipolar plate body, on which a reaction gas inlet (4) and a reaction gas outlet (41) are spaced apart. The area of the reaction gas inlet (4) is smaller than the area of the reaction gas outlet (41). A flow field (1) is provided on the side surface of the bipolar plate body and is communicated with the reaction gas inlet (4) and the reaction gas outlet (41). The flow field (1) includes a plurality of first flow channels (7) arranged at intervals and a plurality of second flow channels (8) arranged at intervals. The first flow channels (7) extend along a first direction, and the first direction is parallel to the direction of reaction gas flow. The second flow channels (8) are in a wavy shape, and each second flow channel (8) is communicated with all the first flow channels (7). The second flow channels (8) extend along a second direction which forms an angle with the first direction. The first flow channel (7) includes a first section (71) and a second section (72) which are communicated with each other. The first section (71) is communicated with the wave crest of the second flow channel (8), and the second section (72) passes through the wave crest. The diameter of the first section (71) is smaller than the diameter of the second flow channel (8), and the diameter of the second section (72) is larger than the diameter of the second flow channel (8).

2. The bipolar plate structure according to claim 1, wherein A first distribution area (2) is provided between the reaction gas inlet (4) and the flow field (1). The first distribution area (2) is evenly distributed with a first dot matrix (21), and the first dot matrix (21) is arranged on the bipolar plate body.

3. The bipolar plate structure according to claim 2, wherein, The flow field (1) includes a diversion area (11), a direct current area (12) and a confluence area (13). The diversion area (11), the direct current area (12) and the confluence area (13) are arranged in sequence along the first direction. Both the diversion area (11) and the confluence area (13) are trapezoidal. The end of the diversion area (11) communicated with the first distribution area (2) is smaller than the end of the diversion area (11) communicated with the direct current area (12). The end of the confluence area (13) communicated with the reaction gas outlet (41) is smaller than the end of the confluence area (13) communicated with the direct current area (12).

4. The bipolar plate structure according to claim 3, characterized in that, A first diversion area is provided between the first distribution area (2) and the diversion area (11). A plurality of first diversion blocks (3) are convexly arranged at intervals in the first diversion area. The first diversion blocks (3) are arranged at intervals along the second direction on the bipolar plate body.

5. The bipolar plate structure according to claim 4, characterized in that, The first diversion block (3) is hexagonal, and each corner of the first diversion block (3) is rounded.

6. The bipolar plate structure according to claim 3, characterized in that, A second distribution area (6) is provided between the confluence area (13) and the reaction gas outlet (41). The second distribution area (6) is evenly distributed with a second dot matrix (61), and the second dot matrix (61) is arranged on the bipolar plate body.

7. The bipolar plate structure according to claim 6, characterized in that, A second diversion area is provided between the confluence area (13) and the second distribution area (6). A plurality of second diversion blocks (5) are convexly arranged at intervals in the second diversion area. The second diversion blocks (5) are arranged at intervals along the second direction on the bipolar plate body.

8. The bipolar plate structure according to claim 1, characterized in that A plurality of annular flow channels (9) are formed in the bipolar plate, the annular flow channels (9) are communicated with the first flow channel (7), and the annular flow channels (9) are located between two adjacent second flow channels (8).

9. A fuel cell, characterized in that, It includes the bipolar plate structure according to any one of claims 1-8.

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