Bipolar plate flow field, bipolar plate and fuel cell

Abstract

The present invention provides a bipolar plate flow field, a bipolar plate and a fuel cell, wherein the bipolar plate flow field is divided into at least three sub-flow field areas from the air inlet end to the air outlet end; a transition area is provided between two adjacent sub-flow field areas, and the flow channel width of the sub-flow field area close to the air inlet end is greater than the flow channel width of the sub-flow field area close to the air outlet end; and the flow channel depth of the bipolar plate flow field gradually decreases from the air inlet end to the air outlet end. The present invention divides the flow field into multiple sub-areas and changes the flow channel from wide to narrow and from deep to shallow in multiple stages to redistribute the fluid multiple times, so that the gas can still maintain a high pressure during the consumption process, and at the same time, the difference problems caused by the different reaction consumption, temperature and water production in different areas can be restored to uniformity due to redistribution, ensuring that the flow field can have excellent gas distribution and diffusion consistency while increasing the effective area, thereby further optimizing the performance of the fuel cell.

Description

Technical Field

[0001] The invention belongs to the field of fuel cells and relates to a bipolar plate flow field, a bipolar plate and a fuel cell. Background Art

[0002] Fuel cells have the excellent characteristics of being clean, environmentally friendly and renewable. They are gradually occupying an important position in the development of the new energy field, making them the new energy technology with the most research and development value.

[0003] Nowadays, the fuel cell industry is pursuing the development goal of higher power and greater energy density. The key technical issue is how to build and achieve a larger effective area. Since the distribution and diffusion effect of the fluid on a larger effective area is not uniform, it is easy to cause the actual reaction discharge effect in the effective area to be uneven in various parts. Therefore, simply increasing the area of ​​the plate module cannot effectively improve the performance of the fuel cell. It is also necessary to optimize the distribution and diffusion effect of the fluid to make the temperature, pressure, humidity conditions of various parts in the reaction area more balanced, thereby effectively improving the performance of the fuel cell.

[0004] CN111446464A discloses a fuel cell bipolar plate, including a bipolar plate body, wherein a flow field structure is arranged on one side of the bipolar plate body facing the membrane electrode, wherein the flow field structure includes a plurality of serpentine flow channels arranged in parallel with each other, wherein each serpentine flow channel groove has at least one trapezoidal protrusion arranged in each serpentine cycle, wherein the trapezoidal protrusion includes a front slope surface, a back slope surface and a slope top surface, wherein the slope top surface is parallel to the bottom surface of the flow channel groove. The application of the above fuel cell bipolar plate can improve the mass transfer capacity of the bipolar plate, reduce concentration polarization, and improve the mass transfer performance of the fuel cell under high current density and low stoichiometric ratio. At the same time, the reaction gas velocity component perpendicular to the bipolar plate body is conducive to increasing the oxygen concentration under the ridge of the bipolar plate, thereby improving the water and heat distribution inside the fuel cell and improving the fuel cell performance.

[0005] CN109509896A discloses a flow field structure for increasing the effective area of ​​the wavy flow field of a bipolar plate of a fuel cell. By setting a half-moon-shaped boss that imitates the wavy flow field and the flow channels around it in the electrochemical reaction weakening zone distributed on both sides of the wavy flow field, the electrochemical reaction weakening zone has the same degree of electrochemical reaction as the main flow field of the fuel cell. The invention can increase the effective area of ​​the wavy flow field of the bipolar plate, and increase the effective electrochemical reaction area by reducing the electrochemical reaction weakening zone of each fuel cell.

[0006] All of the above solutions can achieve the uniformity of mass transfer, distribution and diffusion effects while increasing the effective area. However, the flow field in the provided solution requires the addition of additional microstructures, such as trapezoidal protrusions or half-moon shaped bosses. The setting of these small structures increases the complexity and cost of plate manufacturing and cannot better achieve low-cost large-scale applications. Therefore, it is still necessary to develop a new technical solution to utilize the structural improvement of the flow field itself to optimize the distribution and diffusion effects of the fluid, thereby improving the performance of the fuel cell. Summary of the invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a bipolar plate flow field, a bipolar plate and a fuel cell, wherein the bipolar plate flow field is divided into at least three sub-flow field areas from the air inlet end to the air outlet end; a transition area is provided between two adjacent sub-flow field areas, and the flow channel width of the sub-flow field area close to the air inlet end is greater than the flow channel width of the sub-flow field area close to the air outlet end; from the air inlet end to the air outlet end, the flow channel depth of the bipolar plate flow field gradually decreases. The present invention divides the flow field into multiple sub-areas and changes the flow channel from wide to narrow and from deep to shallow in multiple stages to redistribute the fluid multiple times, so that the gas can still maintain a high pressure during the consumption process, and at the same time, the difference caused by the reaction consumption, temperature and water production in different areas can be restored to uniformity due to redistribution, ensuring that the flow field can have excellent gas distribution and diffusion consistency while increasing the effective area, thereby further optimizing the performance of the fuel cell.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a bipolar plate flow field, which is divided into at least three sub-flow field areas from the air inlet end to the air outlet end; a transition area is arranged between two adjacent sub-flow field areas, and the flow channel width of the sub-flow field area close to the air inlet end is greater than the flow channel width of the sub-flow field area close to the air outlet end; from the air inlet end to the air outlet end, the flow channel depth of the bipolar plate flow field gradually decreases.

[0010] The flow field provided by the present invention is divided into a plurality of sub-flow fields from the air inlet end to the air outlet end, so that the flow field area can be redistributed multiple times, so that the gas originally uniformly distributed into the flow field from the air inlet end can be restored to uniformity after multiple redistributions due to the differences caused by the reaction consumption, temperature distribution, and water production in different areas. Specifically, from the air inlet end to the air outlet end of the flow field, the flow channel is designed to change from wide to narrow in multiple stages between the sub-flow fields, and the gas from the previous sub-flow field area is dispersed in the transition area for redistribution, and then enters the next sub-flow field area with a narrower flow channel, ensuring that the gas can still maintain a high pressure after a part of it is consumed; from the air inlet end to the air outlet end, the flow channel is designed to gradually become shallower from deep, and the cross-sectional area of ​​the flow channel gradually becomes smaller, which can further ensure that the gas is gradually consumed while still maintaining a high pressure; through the above coordination, it is ensured that the flow field can have excellent gas distribution and diffusion consistency while increasing the effective area, so that the performance of the fuel cell is further optimized.

[0011] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0012] As a preferred technical solution of the present invention, the number of the sub-flow field areas is 3 to 6, for example, 3, 4, 5 or 6.

[0013] Preferably, along the gas flow direction, the length of each of the sub-flow field regions is the same.

[0014] As a preferred technical solution of the present invention, the flow channel type of each sub-flow field area is the same.

[0015] Preferably, the flow channel type includes any one of a straight flow channel, a meandering flow channel or a serpentine flow channel, or a combination of at least two of them, preferably a meandering flow channel.

[0016] Preferably, within one of the sub-flow fields, the flow channels are parallel to each other and have the same width.

[0017] As a preferred technical solution of the present invention, the ridge height of the bipolar plate flow field gradually decreases from the air inlet end to the air outlet end, so that the flow channel depth gradually decreases.

[0018] Preferably, the bipolar plate flow field is arranged on both the anode surface and the cathode surface of the bipolar plate.

[0019] Preferably, the ridge heights of the bipolar plate flow fields on the anode surface and the cathode surface have the same variation trend, and the channel depths have the same variation trend, so that the overall thickness of the bipolar plate flow field is uniform.

[0020] From one end to the other end of the bipolar plate, the air inlet end of the flow field on the anode surface corresponds to the air outlet end of the flow field on the cathode surface, and the air outlet end of the flow field on the anode surface corresponds to the air inlet end of the flow field on the cathode surface. Therefore, by keeping the ridge height and flow channel depth of the cathode surface and the anode surface changing in the same trend, the thickness of the bipolar plate can be made exactly the same from one end to the other, ensuring the uniform thickness of the smooth area of ​​the entire bipolar plate.

[0021] Preferably, the range of the width of the flow channel on the anode surface is greater than the range of the width of the flow channel on the cathode surface.

[0022] The range refers to the difference between the maximum and minimum flow channel widths on the same side. Since the flow channel width gradually decreases from the air inlet to the air outlet between the sub-flow field areas, the range is the flow channel width of the sub-flow field area closest to the air inlet minus the flow channel width of the sub-flow field area closest to the air outlet. The present invention finds that when the difference in flow field width of the flow field (hydrogen flow field) on the anode side is greater and the difference in flow field width of the flow field (air flow field) on the cathode side is smaller, the fuel cell has better performance.

[0023] As a preferred technical solution of the present invention, in the bipolar plate flow field, the flow channel width of the sub-flow field area closest to the air inlet end is 1 to 1.4 mm, for example, 1 mm, 1.02 mm, 1.04 mm, 1.06 mm, 1.08 mm, 1.1 mm, 1.12 mm, 1.14 mm, 1.16 mm, 1.18 mm, 1.2 mm, 1.22 mm, 1.24 mm, 1.26 mm, 1.28 mm, 1.3 mm, 1.32 mm, 1.34 mm, 1.36 mm, 1.38 mm or 1.4 mm, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0024] Preferably, in the bipolar plate flow field, the flow channel width of the sub-flow field area closest to the gas outlet end is 0.7-0.9 mm, for example, 0.7 mm, 0.72 mm, 0.74 mm, 0.76 mm, 0.78 mm, 0.8 mm, 0.82 mm, 0.84 mm, 0.86 mm, 0.88 mm or 0.9 mm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0025] Preferably, in the bipolar plate flow field, the flow channel width of the sub-flow field area closest to the outlet end is 50% to 70% of the flow channel width of the sub-flow field area closest to the inlet end, for example, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68% or 70%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0026] As a preferred technical solution of the present invention, in the bipolar plate flow field, the maximum value of the flow channel depth is 0.6-1mm, for example, 0.6mm, 0.62mm, 0.64mm, 0.66mm, 0.68mm, 0.7mm, 0.72mm, 0.74mm, 0.76mm, 0.78mm, 0.8mm, 0.82mm, 0.84mm, 0.86mm, 0.88mm, 0.9mm, 0.86mm, 0.88mm, 0.9mm, 0.92mm, 0.94mm, 0.96mm, 0.98mm or 1mm, etc., but are not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0027] Preferably, in the bipolar plate flow field, the minimum value of the flow channel depth is 0.1-0.3 mm, for example, 0.1 mm, 0.12 mm, 0.14 mm, 0.16 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.24 mm, 0.26 mm, 0.28 mm or 0.3 mm, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0028] Preferably, in the bipolar plate flow field, the minimum value of the flow channel depth is 20% to 30% of the maximum value of the flow channel depth, for example 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0029] As a preferred technical solution of the present invention, in the bipolar plate flow field, the ridge width is 0.8-1.2 mm, for example, 0.8 mm, 0.82 mm, 0.84 mm, 0.86 mm, 0.88 mm, 0.9 mm, 0.92 mm, 0.94 mm, 0.96 mm, 0.98 mm, 1 mm, 1.02 mm, 1.04 mm, 1.06 mm, 1.08 mm, 1.1 mm, 1.12 mm, 1.14 mm, 1.16 mm, 1.18 mm or 1.2 mm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0030] Preferably, the width of the ridge in the sub-flow field area is the same as the width of the flow channel in the sub-flow field area.

[0031] As a preferred technical solution of the present invention, the structure of the transition zone includes a convex dot matrix.

[0032] Preferably, along the gas flow direction, the convex dot matrix includes at least two columns of convex dots arranged alternately with each other.

[0033] Preferably, the diameter of each convex point in the convex point matrix is ​​the same.

[0034] Preferably, in the convex dot matrix, the diameter of the convex dot is less than or equal to the maximum value of the flow channel width of two adjacent sub-flow field areas, and greater than or equal to the minimum value of the two adjacent sub-flow field areas.

[0035] Preferably, in the convex dot matrix, the diameter of the convex dots is 0.8-1.2 mm, for example, 0.8 mm, 0.82 mm, 0.84 mm, 0.86 mm, 0.88 mm, 0.9 mm, 0.92 mm, 0.94 mm, 0.96 mm, 0.98 mm, 1 mm, 1.02 mm, 1.04 mm, 1.06 mm, 1.08 mm, 1.1 mm, 1.12 mm, 1.14 mm, 1.16 mm, 1.18 mm or 1.2 mm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0036] Preferably, in each column of bumps, the intervals between two adjacent bumps are the same.

[0037] Preferably, in each column of convex dots, the interval between two adjacent convex dots is equal to the diameter of the convex dots.

[0038] Preferably, in each column of bumps, the interval between two adjacent bumps is 0.8-1.2 mm, for example, 0.8 mm, 0.82 mm, 0.84 mm, 0.86 mm, 0.88 mm, 0.9 mm, 0.92 mm, 0.94 mm, 0.96 mm, 0.98 mm, 1 mm, 1.02 mm, 1.04 mm, 1.06 mm, 1.08 mm, 1.1 mm, 1.12 mm, 1.14 mm, 1.16 mm, 1.18 mm or 1.2 mm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0039] In a second aspect, the present invention provides a bipolar plate, wherein the bipolar plate comprises the bipolar plate flow field described in the first aspect.

[0040] In a third aspect, the present invention provides a fuel cell, wherein the fuel cell comprises the bipolar plate described in the third aspect.

[0041] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0042] (1) The present invention divides the flow field into multiple sub-areas and changes the flow channel from wide to narrow and from deep to shallow in multiple stages to redistribute the fluid multiple times, so that the gas can still maintain a high pressure during the consumption process. At the same time, the differences caused by the reaction consumption, temperature and water production in different areas can be restored to uniformity due to redistribution, ensuring that the flow field can have excellent gas distribution and diffusion consistency while increasing the effective area, thereby further optimizing the performance of the fuel cell;

[0043] (2) The flow field of the present invention can be set on the anode surface and cathode surface of the bipolar plate at the same time, and when the ridge height and flow channel depth of the cathode surface and the anode surface are kept in the same trend, the thickness of the bipolar plate can be made exactly the same from one end to the other, ensuring the uniform thickness of the smooth area of ​​the entire bipolar plate;

[0044] (3) The present invention can further improve the performance of the fuel cell by setting the width difference of the hydrogen flow field on the anode side to be larger and the width difference of the air flow field on the cathode side to be smaller. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a schematic front view of the bipolar plate flow field described in Example 1;

[0046] Figure 2 is a cross-sectional schematic diagram of the bipolar plate flow field along the gas flow direction described in Example 1;

[0047] Figure 3 It is a cross-sectional schematic diagram of the bipolar plate flow field along the gas flow direction described in Example 2. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0049] Example 1

[0050] This embodiment provides a bipolar plate flow field and a bipolar plate containing the same, wherein the bipolar plate flow field is arranged on a surface of one side of the bipolar plate;

[0051] The schematic diagram of the bipolar plate flow field is as follows Figure 1 As shown, the bipolar plate flow field is divided into three sub-flow field areas of the same length from the air inlet end to the air outlet end, namely the first sub-flow field area, the second sub-flow field area and the third sub-flow field area; a transition area is provided between two adjacent sub-flow field areas, wherein the transition area between the first sub-flow field area and the second sub-flow field area is the first transition area, and the transition area between the second sub-flow field area and the third sub-flow field area is the second transition area;

[0052] The flow channels of the first sub-flow field area, the second sub-flow field area and the third sub-flow field area are all serpentine flow channels; inside the first sub-flow field area, the flow channels are parallel to each other, the width of the flow channels is 1.2 mm, and the ridge width is 1.2 mm; inside the second sub-flow field area, the flow channels are parallel to each other, the width of the flow channels is 1 mm, and the ridge width is 1 mm; inside the third sub-flow field area, the flow channels are parallel to each other, the width of the flow channels is 0.8 mm, and the ridge width is 0.8 mm; Figure 2 is a schematic cross-sectional view of the bipolar plate flow field along the gas flow direction, which cuts the ridges in each sub-flow field area along the central axis. Since the flow channel is a winding flow channel, the ridges are divided into discontinuous structures at this time. It can be seen from the figure that the ridge height of the bipolar plate flow field gradually decreases from the air inlet end to the air outlet end, so that the depth of the flow channel gradually decreases from 0.8 mm to 0.2 mm;

[0053] The first transition zone is a convex dot matrix, and along the gas flow direction, the convex dot matrix includes two columns of convex dots arranged alternately, and the diameter of each convex dot is the same, which is 1.2 mm. In each column of convex dots, the interval between two adjacent convex dots is the same, which is 1.2 mm. The second transition zone is a convex dot matrix, and along the gas flow direction, the convex dot matrix includes two columns of convex dots arranged alternately, and the diameter of each convex dot is the same, which is 0.8 mm. In each column of convex dots, the interval between two adjacent convex dots is the same, which is 0.8 mm.

[0054] Example 2

[0055] This embodiment provides a bipolar plate flow field and a bipolar plate containing the same, wherein the bipolar plate flow field is simultaneously arranged on the anode surface and the cathode surface of the bipolar plate;

[0056] The bipolar plate flow field on each surface of the bipolar plate is divided into four sub-flow field areas of equal length from the air inlet end to the air outlet end, namely, the first sub-flow field area, the second sub-flow field area, the third sub-flow field area and the fourth sub-flow field area; a transition area is provided between two adjacent sub-flow field areas, wherein the transition area between the first sub-flow field area and the second sub-flow field area is the first transition area, the transition area between the second sub-flow field area and the third sub-flow field area is the second transition area, and the transition area between the third sub-flow field area and the fourth sub-flow field area is the third transition area;

[0057] The flow channels of the first sub-flow field area, the second sub-flow field area, the third sub-flow field area and the fourth sub-flow field area are all serpentine flow channels; inside the first sub-flow field area, the flow channels are parallel to each other, the width of the flow channels is 1.2 mm, and the ridge width is 1.2 mm; inside the second sub-flow field area, the flow channels are parallel to each other, the width of the flow channels is 1 mm, and the ridge width is 1 mm; inside the third sub-flow field area, the flow channels are parallel to each other, the width of the flow channels is 0.8 mm, and the ridge width is 0.8 mm; inside the fourth sub-flow field area, the flow channels are parallel to each other, the width of the flow channels is 0.7 mm, and the ridge width is 0.7 mm; Figure 3 is a schematic cross-sectional view of the bipolar plate flow field along the gas flow direction, the cross-section cuts the ridges in each sub-flow field area along the central axis thereof, and because the flow channel is a winding flow channel, the ridges are divided into discontinuous structures at this time. It can be seen from the figure that on the cathode surface and the anode surface of the bipolar plate, the ridge height of the bipolar plate flow field gradually decreases from the air inlet end to the air outlet end, so that the depth of the flow channel gradually decreases from 1 mm to 0.3 mm; and the change trends of the ridge height and the flow channel depth on the anode surface and the cathode surface are the same, so that the overall thickness of the bipolar plate flow field is uniform;

[0058] The first transition zone is a convex dot matrix, and along the gas flow direction, the convex dot matrix includes three columns of convex dots arranged alternately, and the diameter of each convex dot is the same, which is 1.2 mm. In each column of convex dots, the interval between two adjacent convex dots is the same, which is 1.2 mm; the second transition zone is a convex dot matrix, and along the gas flow direction, the convex dot matrix includes two columns of convex dots arranged alternately, and the diameter of each convex dot is the same, which is 1 mm. In each column of convex dots, the interval between two adjacent convex dots is the same, which is 1 mm; the third transition zone is a convex dot matrix, and along the gas flow direction, the convex dot matrix includes two columns of convex dots arranged alternately, and the diameter of each convex dot is the same, which is 0.8 mm. In each column of convex dots, the interval between two adjacent convex dots is the same, which is 0.8 mm.

[0059] Example 3

[0060] This embodiment provides a bipolar plate flow field and a bipolar plate containing the same, wherein the bipolar plate flow field is simultaneously arranged on the anode surface and the cathode surface of the bipolar plate;

[0061] On the cathode surface of the bipolar plate, the bipolar plate flow field is divided into three sub-flow field areas of equal length from the air inlet end to the air outlet end, namely, the first sub-flow field area, the second sub-flow field area and the third sub-flow field area; a transition area is provided between two adjacent sub-flow field areas, wherein the transition area between the first sub-flow field area and the second sub-flow field area is the first transition area, and the transition area between the second sub-flow field area and the third sub-flow field area is the second transition area;

[0062] The flow channels of the first sub-flow field area, the second sub-flow field area and the third sub-flow field area are all linear flow channels; inside the first sub-flow field area, the flow channels are parallel to each other and the width of the flow channels is 1.4 mm, and the ridge width is 1.4 mm; inside the second sub-flow field area, the flow channels are parallel to each other and the width of the flow channels is 1.2 mm, and the ridge width is 1.2 mm; inside the third sub-flow field area, the flow channels are parallel to each other and the width of the flow channels is 0.9 mm, and the ridge width is 0.9 mm; on the cathode surface and the anode surface of the bipolar plate, the ridge height of the bipolar plate flow field gradually decreases from the air inlet end to the air outlet end, so that the depth of the flow channel gradually decreases from 0.6 mm to 0.12 mm;

[0063] The first transition zone is a convex dot matrix, and along the gas flow direction, the convex dot matrix includes two columns of convex dots arranged alternately, each convex dot has the same diameter of 1.2 mm, and in each column of convex dots, the interval between two adjacent convex dots is the same as 1.2 mm; the second transition zone is a convex dot matrix, and along the gas flow direction, the convex dot matrix includes two columns of convex dots arranged alternately, each convex dot has the same diameter of 0.9 mm, and in each column of convex dots, the interval between two adjacent convex dots is the same as 0.9 mm;

[0064] On the anode surface of the bipolar plate, the bipolar plate flow field is divided into three sub-flow field areas of equal length from the air inlet end to the air outlet end, namely, the first sub-flow field area, the second sub-flow field area and the third sub-flow field area; a transition area is provided between two adjacent sub-flow field areas, wherein the transition area between the first sub-flow field area and the second sub-flow field area is the first transition area, and the transition area between the second sub-flow field area and the third sub-flow field area is the second transition area;

[0065] The flow channels of the first sub-flow field area, the second sub-flow field area and the third sub-flow field area are all linear flow channels; inside the first sub-flow field area, the flow channels are parallel to each other and the width of the flow channels is 1.4mm, and the ridge width is 1.4mm; inside the second sub-flow field area, the flow channels are parallel to each other and the width of the flow channels is 1mm, and the ridge width is 1mm; inside the third sub-flow field area, the flow channels are parallel to each other and the width of the flow channels is 0.7mm, and the ridge width is 0.7mm; on the cathode surface and the anode surface of the bipolar plate, the ridge height of the bipolar plate flow field gradually decreases from the air inlet end to the air outlet end, so that the depth of the flow channel gradually decreases from 0.6mm to 0.12mm; and the change trends of the ridge height and the flow channel depth on the anode surface and the cathode surface are the same, so that the overall thickness of the bipolar plate flow field is uniform;

[0066] The first transition zone is a convex dot matrix, and along the gas flow direction, the convex dot matrix includes two columns of convex dots arranged alternately, each convex dot has the same diameter of 1.2 mm, and in each column of convex dots, the interval between two adjacent convex dots is the same, both 1.2 mm; the second transition zone is a convex dot matrix, and along the gas flow direction, the convex dot matrix includes two columns of convex dots arranged alternately, each convex dot has the same diameter of 0.9 mm, and in each column of convex dots, the interval between two adjacent convex dots is the same, both 0.9 mm.

[0067] Comparative Example 1

[0068] This comparative example provides a bipolar plate flow field and a bipolar plate containing the same, wherein the bipolar plate flow field is arranged on a surface of one side of the bipolar plate;

[0069] The bipolar plate flow field is divided into three sub-flow field areas of the same length from the air inlet end to the air outlet end, namely the first sub-flow field area, the second sub-flow field area and the third sub-flow field area; a transition area is provided between two adjacent sub-flow field areas, wherein the transition area between the first sub-flow field area and the second sub-flow field area is the first transition area, and the transition area between the second sub-flow field area and the third sub-flow field area is the second transition area;

[0070] The flow channels of the first sub-flow field area, the second sub-flow field area and the third sub-flow field area are all serpentine flow channels; the flow channels inside the first sub-flow field area, the second sub-flow field area and the third sub-flow field area are parallel to each other and the width of the flow channels is 1.2 mm, and the ridge width is 1.2 mm; from the air inlet end to the air outlet end, the ridge height of the bipolar plate flow field gradually decreases, so that the depth of the flow channel gradually decreases from 0.8 mm to 0.2 mm;

[0071] The first transition zone and the second transition zone are both convex dot matrices. Along the gas flow direction, the convex dot matrices include two rows of convex dots arranged alternately with each other, each convex dot has the same diameter of 1.2 mm, and in each row of convex dots, the interval between two adjacent convex dots is the same, that is, 1.2 mm.

[0072] Comparative Example 2

[0073] This comparative example provides a bipolar plate flow field and a bipolar plate containing the same, wherein the bipolar plate flow field is arranged on a surface of one side of the bipolar plate;

[0074] The bipolar plate flow field is divided into three sub-flow field areas of the same length from the air inlet end to the air outlet end, namely the first sub-flow field area, the second sub-flow field area and the third sub-flow field area; a transition area is provided between two adjacent sub-flow field areas, wherein the transition area between the first sub-flow field area and the second sub-flow field area is the first transition area, and the transition area between the second sub-flow field area and the third sub-flow field area is the second transition area;

[0075] The flow channels of the first sub-flow field area, the second sub-flow field area and the third sub-flow field area are all serpentine flow channels; the flow channels inside the first sub-flow field area, the second sub-flow field area and the third sub-flow field area are parallel to each other and the width of the flow channels is 0.8 mm, and the ridge width is 0.8 mm; from the air inlet end to the air outlet end, the ridge height of the bipolar plate flow field gradually decreases, so that the depth of the flow channel gradually decreases from 0.8 mm to 0.2 mm;

[0076] The first transition zone and the second transition zone are both convex dot matrices. Along the gas flow direction, the convex dot matrices include two rows of convex dots arranged alternately with each other, each convex dot has the same diameter of 0.8 mm, and in each row of convex dots, the interval between two adjacent convex dots is the same, which is 0.8 mm.

[0077] Comparative Example 3

[0078] This comparative example provides a bipolar plate flow field and a bipolar plate containing the same, wherein the bipolar plate flow field is arranged on the surface of one side of the bipolar plate, and the ridge height of the bipolar plate flow field from the air inlet end to the air outlet end does not change and is 0.8 mm, and the flow channel depth does not change. Apart from this, other conditions are exactly the same as those in Example 1.

[0079] Comparative Example 4

[0080] This comparative example provides a bipolar plate flow field and a bipolar plate containing the same, wherein the bipolar plate flow field is arranged on the surface of one side of the bipolar plate, and the ridge height of the bipolar plate flow field from the air inlet end to the air outlet end does not change and is 0.2 mm, and the flow channel depth does not change. Apart from this, other conditions are exactly the same as those in Example 1.

[0081] Comparative Example 5

[0082] This comparative example provides a bipolar plate flow field and a bipolar plate containing the same. The bipolar plate flow field is arranged on the surface of one side of the bipolar plate. The bipolar plate flow field does not have a transition zone. Apart from this, other conditions are exactly the same as those in Example 1.

[0083] The bipolar plates obtained in the examples and comparative examples were assembled into fuel cells, and tested and compared under the following conditions. The results are recorded in Table 1.

[0084] Experimental conditions:

[0085] Current density 2A / cm 2 ; Battery temperature 75℃; Hydrogen-air stoichiometric ratio 1.5 / 2.0; Hydrogen-air humidity 50% / 0%; Hydrogen-air pressure 140kPa / 120kPa.

[0086] Table 1

[0087]

[0088]

[0089] It can be seen from Table 1 that:

[0090] The present invention significantly improves the battery discharge performance compared with only using a single flow field by setting multiple sub-flow fields with gradually decreasing widths, and the battery discharge performance is significantly improved by gradually decreasing the flow channel depth from the air inlet end to the air outlet end; compared with comparative example 5, embodiment 1 improves the battery discharge performance through multiple gas redistribution transition zones; embodiment 2 has a more significant effect of improving gas distribution and air pressure distribution and improving performance by setting a four-stage sub-flow field than the three-stage sub-flow field of embodiment 1; embodiment 3 uses a straight flow channel, which has a smaller gas flow resistance than a winding flow channel, and by setting the change in the flow channel width on the cathode side (air side) to be smaller than that on the anode side, it is beneficial to discharge the water generated by the reaction.

[0091] The present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0092] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0093] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0094] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A bipolar plate flow field, characterized in that: The bipolar plate flow field is divided into at least three sub-flow field areas from the air inlet end to the air outlet end; a transition area is provided between two adjacent sub-flow field areas, and the flow channel width of the sub-flow field area close to the air inlet end is greater than the flow channel width of the sub-flow field area close to the air outlet end; the flow channel depth of the bipolar plate flow field gradually decreases from the air inlet end to the air outlet end; The air inlet end and the air outlet end are in the same straight line; From the air inlet end to the air outlet end, the ridge height of the bipolar plate flow field gradually decreases, so that the flow channel depth gradually decreases; The maximum value of the flow channel depth is 0.6~1mm; The minimum value of the flow channel depth is 0.1~0.3mm; The minimum value of the flow channel depth is 20% to 30% of the maximum value of the flow channel depth; The flow channel type is a meandering flow channel; The bipolar plate flow field is arranged on both the anode surface and the cathode surface of the bipolar plate; The ridge height of the bipolar plate flow field on the anode surface and the cathode surface has the same change trend, and the flow channel depth has the same change trend, so that the overall thickness of the bipolar plate flow field is uniform; The range of the width of the flow channel on the anode surface is greater than the range of the width of the flow channel on the cathode surface; The range is the width of the flow channel of the sub-flow field area closest to the air inlet minus the width of the flow channel of the sub-flow field area closest to the air outlet; The structure of the transition zone includes a convex dot matrix; The diameter of each convex point in the convex point matrix is ​​the same; In the convex dot matrix, the diameter of the convex dot is less than or equal to the maximum value of the flow channel width of two adjacent sub-flow field areas, and greater than or equal to the minimum value of the two adjacent sub-flow field areas; Along the gas flow direction, the length of each of the sub-flow field regions is the same; Inside one of the sub-flow fields, the flow channels are parallel to each other and have the same width; Along the gas flow direction, the convex dot matrix includes at least two rows of convex dots arranged alternately with each other; In each column of bumps, the interval between two adjacent bumps is equal to the diameter of the bumps.

2. The bipolar plate flow field according to claim 1, characterized in that: The number of the sub-flow field areas is 3 to 6.

3. The bipolar plate flow field according to claim 1, characterized in that: The flow channel type of each sub-flow field area is the same.

4. The bipolar plate flow field according to claim 1, characterized in that: In the bipolar plate flow field, the flow channel width of the sub-flow field area closest to the air inlet end is 1-1.4 mm.

5. The bipolar plate flow field according to claim 1, characterized in that: In the bipolar plate flow field, the flow channel width of the sub-flow field area closest to the gas outlet is 0.7-0.9 mm.

6. The bipolar plate flow field according to claim 1, characterized in that: In the bipolar plate flow field, the flow channel width of the sub-flow field area closest to the gas outlet end is 50% to 70% of the flow channel width of the sub-flow field area closest to the gas inlet end.

7. The bipolar plate flow field according to claim 1, characterized in that: In the bipolar plate flow field, the ridge width is 0.8-1.2 mm.

8. The bipolar plate flow field according to claim 7, characterized in that: The ridge width in the sub-flow field area is the same as the flow channel width in the sub-flow field area.

9. The bipolar plate flow field according to claim 1, characterized in that: In the convex dot matrix, the diameter of the convex dots is 0.8-1.2 mm.

10. The bipolar plate flow field according to claim 1, characterized in that: In each column of bumps, the intervals between two adjacent bumps are the same.

11. The bipolar plate flow field according to claim 1, characterized in that: In each column of bumps, the interval between two adjacent bumps is 0.8~1.2mm.

12. A bipolar plate, characterized in that: The bipolar plate comprises the bipolar plate flow field according to any one of claims 1-11.

13. A fuel cell, characterized in that: The fuel cell comprises the bipolar plate according to claim 12.

Images