Flow field for fuel cell and fuel cell polar plate

Abstract

The present application discloses a flow field for a fuel cell and a fuel electrode plate, the flow field comprising: a flow guide region having a plurality of guide ridges arranged in a staggered array and a plurality of flow channels formed by separating the plurality of ridges from each other; the distribution area comprises a first distribution area and a second distribution area, the first distribution area and the second distribution area are both in a radial shape, the first distribution area is connected with an inlet of the flow guide area, and the second distribution area is connected with an outlet of the flow guide area; wherein the guide ridges are discontinuous in the direction from an inlet of the flow guide area to an outlet of the flow guide area, and the multiple flow channels are arranged in the flow guide area in a sectioned mode. The flow field adopts a sectional flow channel design to promote mixing and disturbance of reaction gas and water, so that mass transfer is promoted, mass transfer resistance is reduced, water generated by reaction is discharged in time, uniform distribution of current density is improved, the electrochemical performance of the fuel cell is improved, and the service life of the fuel cell is prolonged.

Description

Technical Field

[0001] The present invention relates to a fuel cell, and more particularly to a flow field and a fuel cell plate for a fuel cell. Background Art

[0002] A fuel cell is a power generation device that generates electrical energy by electrochemically reacting a fuel such as methanol or hydrogen with an oxidizing gas in a catalyst layer of a membrane electrode assembly. A fuel cell includes a membrane electrode assembly and a first electrode plate and a second electrode plate located on opposite sides of the membrane electrode assembly. The membrane electrode assembly includes an electrolyte membrane and a catalyst layer and a diffusion layer located on both sides of the electrolyte membrane. The first electrode plate and the second electrode plate are used to transport fuel gas and oxidizing gas to the membrane electrode assembly, respectively.

[0003] The first surface of the first electrode plate is, for example, an anode surface adjacent to the membrane electrode assembly, and the second surface is, for example, one of a cathode surface, a cooling surface, and a flat surface. The first surface of the second electrode plate is, for example, a cathode surface adjacent to the membrane electrode assembly, and the second surface is, for example, one of an anode surface, a cooling surface, and a flat surface. Corresponding flow field structures are formed on the anode surface, the cathode surface, and the cooling surface, respectively, for uniformly distributing one of the fuel gas, the oxidizing gas, and the cooling medium.

[0004] The flow field of the fuel cell plate is an important factor affecting the performance of the fuel cell. It can guide the flow direction of the reactant gas, ensure that the reactant gas is evenly distributed to all parts of the electrode, and then reaches the catalyst layer through the electrode diffusion layer to participate in the electrochemical reaction, while discharging the water generated by the electrochemical reaction. Unreasonable flow field design can easily lead to uneven distribution of reactants, or make the generated water unable to be quickly discharged from the battery, resulting in local overheating, flooding, local swelling of the proton membrane, etc., making it difficult for the reactant gas to combine with the catalyst, increasing the mass transfer resistance, reducing the output power, and having a serious impact on the battery life, performance degradation and failure.

[0005] Therefore, there is an urgent need to improve the flow field design of fuel cells so that all parts of the plates can obtain sufficient reaction gas and discharge the generated water in time, ensuring that the fuel cell has good performance and stability. Summary of the invention

[0006] In view of the above problems, the object of the present invention is to provide a flow field and a fuel cell plate for a fuel cell. The flow field adopts a segmented flow channel design to promote the mixing and disturbance of the reaction gas and water, thereby promoting mass transfer, reducing mass transfer resistance and allowing the water produced by the reaction to be discharged in time, thereby improving the uniform distribution of current density and improving the electrochemical performance and life of the fuel cell.

[0007] According to one aspect of the present invention, there is provided a flow field for a fuel cell, comprising: a guide area having a plurality of guide ridges arranged in an array in an alternating manner, and a plurality of flow channels formed by the plurality of ridges being separated from each other; a distribution area, the distribution area comprising a first distribution area and a second distribution area, the first distribution area and the second distribution area being both radial, the first distribution area being connected to the inlet of the guide area, and the second distribution area being connected to the outlet of the guide area; wherein the guide ridges are discontinuous in the direction from the inlet of the guide area to the outlet of the guide area, and the plurality of flow channels are arranged in sections in the guide area.

[0008] Optionally, the distribution area has a plurality of point-shaped guide columns arranged in an array.

[0009] In the above-mentioned flow field, the guide ridge includes at least one of a rectangular, arched, diamond-shaped, flat-convex airfoil, double-convex airfoil, concave-convex airfoil, and S-shaped airfoil.

[0010] Optionally, the leading edge of one end of the guide ridge facing the inlet direction of the guide area is pointed or slightly blunt, and the shape and size of at least some of the guide ridges in the guide area are different from those of the remaining guide ridges.

[0011] Optionally, each guide ridge has a thickness of 0.2 mm to 1.5 mm and a length of 10 mm to 50 mm.

[0012] Optionally, a plurality of guide ridges arranged along the second direction form a guide group, and a flow channel along the first direction is formed between adjacent guide ridges in the guide group, and the width of the flow channel is 0.2 mm to 1.5 mm, wherein the direction from the entrance of the guide area to the outlet of the guide area is the first direction, and the second direction is perpendicular to the first direction.

[0013] Optionally, a plurality of the guide groups are arranged along the first direction, and a spacing between adjacent guide groups is 0.1 mm to 3 mm.

[0014] Optionally, the plurality of guide groups are staggered in the second direction, and the staggered distance is 0 mm to 1.5 mm.

[0015] According to another aspect of the present invention, a fuel cell plate is provided, wherein at least one surface of the fuel cell plate comprises the above-mentioned flow field.

[0016] Optionally, the electrode plate is any one of an anode plate, a cathode plate, and a bipolar plate.

[0017] The flow field for fuel cells and the electrode plates for fuel cells of the present application include a point distribution area and a guide area with a segmented flow channel. This design is conducive to the mixing and disturbance of the reaction gas and the water produced by the reaction, and promotes the mass transfer of materials through the three-phase interface of the gas diffusion layer and the catalyst layer in the normal direction. It can not only reduce the mass transfer resistance, but also facilitate the timely discharge of the water produced by the reaction, promote the uniform distribution of current density, improve the electrochemical performance and life of the battery, and thus improve the stability and reliability of the battery. The processing technology required for this design is simple, has high operability, and is suitable for large-scale mass production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings.

[0019] Figure 1 A schematic diagram showing a fuel cell plate according to a first embodiment of the present invention;

[0020] Figure 2 A partial enlarged schematic diagram showing a flow guide area in a flow field of a fuel cell plate according to a first embodiment of the present invention;

[0021] Figure 3 A schematic diagram showing a fuel cell plate according to a second embodiment of the present invention;

[0022] Figure 4 A schematic diagram showing a guide ridge in a flow guide area in a flow field of a fuel cell plate according to a third embodiment of the present invention;

[0023] Figure 5 A schematic diagram showing streamlines of fluid flowing through guide ridges in a fuel cell plate according to an embodiment of the present invention;

[0024] Figure 6 A schematic diagram showing the shape of guide ridges in a fuel cell plate according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0026] All terms used herein have the same meanings as those generally understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

[0028] Figure 1 A schematic diagram of a fuel cell plate according to a first embodiment of the present invention is shown; as can be seen from the figure, the plate 100 is roughly rectangular, including a first side and a second side extending along the x-direction and opposite to each other, and a third side and a fourth side extending along the y-direction and opposite to each other. Specifically, a first through hole 111, a second through hole 121 and a third through hole 131 are provided on one side of the third side of the plate 100, and a fourth through hole 112, a fifth through hole 122 and a sixth through hole 132 are provided on one side of the fourth side of the plate 100.

[0029] Among them, the first through hole 111 and the fourth through hole 112 are respectively used for the inflow and outflow of fuel gas; the second through hole 121 and the fifth through hole 122 are respectively used for the inflow and outflow of oxidizing gas; the third through hole 131 and the sixth through hole 132 are respectively used for the inflow and outflow of cooling fluid.

[0030] The fuel cell plate of the first embodiment is, for example, a cathode plate. In addition to the through holes on the left and right sides, the plate 100 also includes a flow field located on the surface of one side of the plate 100 between the through holes on the two sides. The flow field includes a first distribution area 141, a guide area 150, and a second distribution area 142. The first distribution area 141 and the second distribution area 142 are, for example, both radial. Specifically, one end of the first distribution area 141 is connected to the second through hole 121, and the other end of the first distribution area 141 is connected to the inlet direction of the guide area 150. The first distribution area 141 gradually diverges and expands from the second through hole 121 to the inlet of the guide area 150; similarly, one end of the second distribution area 142 is connected to the fifth through hole 122, and the other end of the second distribution area 142 is connected to the outlet direction of the guide area 150. The second distribution area 142 gradually diverges and expands from the fifth through hole 122 to the outlet of the guide area 150.

[0031] A plurality of guide columns arranged in an array are provided in the first distribution area 141. The cross section of the guide column is, for example, circular. The first distribution area 141 guides and diverts the oxidizing gas through the guide columns arranged in a point shape.

[0032] The guide area 150, for example, includes a plurality of guide ridges 151 arranged in an array, and the guide ridges 151 are evenly arranged in the guide area 150. The first side and the second side of the electrode plate 100 are also provided with protrusions 152 corresponding to the plurality of guide ridges 151 arranged in an array on the side close to the guide area 150. The flow channel formed between adjacent guide ridges 151 (as well as between the guide ridge 151 and the first side, and between the guide ridge 151 and the second side) is not continuous from the entrance to the exit of the guide area 150, that is, the guide area 150 adopts a segmented flow channel.

[0033] In a fuel cell, the fuel gas and the oxidizing gas will transfer mass to the three-phase interface of the gas diffusion layer and the catalyst layer in the flow field area of ​​the plate, and the fuel gas and the oxidizing gas will react, and the water generated by the reaction between the two will enter the flow field area. By using a segmented flow channel in the flow field guide area 150, the segmented design is conducive to the mixing and disturbance of water and gas, which can promote the mass transfer of the reaction gas (fuel gas and oxidizing gas) to the catalyst layer, and is also conducive to the timely discharge of the water generated by the reaction, promoting the uniform distribution of the current density of the fuel cell, improving the electrochemical performance and life of the fuel cell, and improving the stability and reliability of the fuel cell.

[0034] Specifically, see Figure 2 As shown, a plurality of guide ridges 151 arranged along the y direction, for example, form a guide group 1510, and a flow channel along the x direction is formed between adjacent guide ridges 151 in the guide group 1510. The plurality of guide groups 1510 are arranged along the x direction and staggered in the y direction. Further, the guide ridge 151 is, for example, strip-shaped, wing-like structure. In order to reduce fluid resistance loss, the leading edge of the guide ridge 151 facing the end of the flow field inlet direction is preferably pointed or slightly blunt. The thickness h of the guide ridge 151 is, for example, 0.2 mm to 1.5 mm, and the length d of the guide ridge 151 is, for example, 10 mm to 50 mm. Preferably, the thickness h of the guide ridge 151 is 0.3 mm to 1 mm; the length d is 20 mm to 35 mm. The width H of the flow channel formed between adjacent guide ridges 151 in the guide group 1510 is, for example, 0.2 mm to 1.5 mm. Preferably, the width H of the flow channel is 0.3 mm to 1.2 mm. The spacing between the guide groups 1510, that is, the spacing D between adjacent flow channels in the segmented flow channel, is, for example, 0.1mm~3mm, preferably, the spacing D is 0.5mm~2mm; in the x-direction, adjacent flow channels are arranged in a staggered or parallel manner, that is, adjacent guide groups 1510 are staggered from each other in the x-direction, specifically, the staggered distance S between left and right adjacent flow channels is 0mm~1.5mm, preferably, the staggered distance S is 0.3mm~0.8mm.

[0035] Furthermore, the shapes and sizes of the guide ridges 151 in the guide area 150 may be the same or different, that is, the guide area 150 may include guide ridges of various shapes and sizes.

[0036] Figure 3 A schematic diagram of a fuel cell plate according to a second embodiment of the present invention is shown; the fuel cell plate according to the second embodiment is similar to the first embodiment, except that the guide ridge 151 in the second embodiment is rectangular and the second embodiment also adopts a segmented flow channel design.

[0037] Although Figure 1 and Figure 3The fuel cell plates in the invention are all cathode plates, but the flow field design in the invention is not limited to cathode plates, but can also be used for anode plates or bipolar plates of fuel cells. When used for anode plates or bipolar plates, the flow field is similar to that of cathode plates and will not be described in detail.

[0038] Figure 4 A schematic diagram of a guide ridge in a flow field of a fuel cell plate according to a third embodiment of the present invention is shown; the guide ridge 151 is an airfoil-like shape, including a chord 1514, a leading edge 1511 at one end of the chord 1514, a trailing edge 1515 at the other end of the chord 1514, and an upper camber 1512 and a lower camber 1513 connecting the leading edge 1511 and the trailing edge 1515. Figure 5 When the fluid flows through the guide ridge 151, an airfoil flow is formed. The streamlines near the upper arc 1512 are denser and the flow velocity is large; the streamlines near the lower arc 1513 are sparser and the flow velocity is small. The different flow velocities on the upper and lower surfaces cause different pressure distributions. The flow velocity on the upper side is large and the pressure is small, while the flow velocity on the lower side is small and the pressure is large. Under the action of the pressure difference between the upper and lower sides, the fluids flowing through the upper and lower sides of the guide ridge 151 will be mixed and disturbed in the trailing edge 1515 area. The segmented design provides space for its mixing and disturbance. This design can further promote the mixing and disturbance of the gas and the water produced by the reaction, reduce the mass transfer resistance and discharge the water produced by the reaction in time.

[0039] The present invention is used for the flow field of a fuel cell, and the guide ridges in the flow field can be in various shapes, for example, including Figure 6 The 10 shapes shown, specifically, can be, for example Figure 6 The rectangle at the first position on the left, the curved bow at the second position on the left, the first flat convex shape of the wing-like at the third position on the left (the leading edge width is greater than the trailing edge width, the upper side is an arc, and the lower side is a straight line), the first biconvex shape of the wing-like at the fourth position on the left (both the upper side and the lower side are arcs), the second flat convex shape at the fifth position on the left (the leading edge width is the same as the trailing edge width, symmetrical along the dotted line), the second biconvex shape at the first position on the right (the upper side and the lower side are symmetrical along the chord line), the laminar wing shape at the second position on the right, the rhombus at the third position on the right, the arc shape at the fourth position on the right (the leading edge has a pointed shape, the upper side and the lower side are both arcs), and the S shape at the fifth position on the right (similar to a tadpole, with a leading edge size greater than the trailing edge size). Of course, the guide ridge can also adopt other wing-like structures, and the shape and size of the guide ridges in the same guide area can be the same or different.

[0040] The flow field for fuel cells and the electrode plates for fuel cells of the present application include a point distribution area and a guide area with a segmented flow channel. This design is conducive to the mixing and disturbance of the reaction gas and the water produced by the reaction, and promotes the mass transfer of materials through the three-phase interface of the gas diffusion layer and the catalyst layer in the normal direction. It can not only reduce the mass transfer resistance, but also facilitate the timely discharge of the water produced by the reaction, promote the uniform distribution of current density, improve the electrochemical performance and life of the battery, and thus improve the stability and reliability of the battery. The processing technology required for this design is simple, has high operability, and is suitable for large-scale mass production and application.

[0041] It should be noted that in the description of the present invention, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0042] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the embodiments. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived from them are still within the scope of protection of the present invention.

Claims

1. A flow field for a fuel cell, characterized in that: include: A flow guide area having a plurality of guide ridges arranged in an array and staggered, and a plurality of flow channels formed by the plurality of ridges being separated from each other; A distribution area, the distribution area includes a first distribution area and a second distribution area, the first distribution area and the second distribution area are both radial, the first distribution area is connected to the inlet of the guide area, and the second distribution area is connected to the outlet of the guide area; The guide ridge is discontinuous in the direction from the inlet of the guide area to the outlet of the guide area, and the plurality of flow channels are arranged in sections in the guide area.

2. The flow field according to claim 1, characterized in that The distribution area has a plurality of dot-shaped guide columns arranged in an array.

3. The flow field according to claim 1, characterized in that: The guide ridge includes at least one of a rectangular, arched, diamond-shaped, flat-convex airfoil, double-convex airfoil, concave-convex airfoil, and S-shaped airfoil.

4. The flow field according to claim 1, characterized in that The leading edge of one end of the guide ridge facing the inlet direction of the guide area is pointed or slightly blunt, and the shape and size of at least some of the guide ridges in the guide area are different from those of the other guide ridges.

5. The flow field according to claim 1, characterized in that: Each guide ridge has a thickness of 0.2 mm to 1.5 mm and a length of 10 mm to 50 mm.

6. The flow field according to claim 1, characterized in that A plurality of guide ridges arranged along the second direction form a guide group, and a flow channel along the first direction is formed between adjacent guide ridges in the guide group, and the width of the flow channel is 0.2 mm to 1.5 mm, wherein the direction from the entrance of the guide area to the outlet of the guide area is the first direction, and the second direction is perpendicular to the first direction.

7. The flow field according to claim 6, characterized in that The plurality of guide groups are arranged along the first direction, and the spacing between adjacent guide groups is 0.1 mm to 3 mm.

8. The flow field according to claim 7, characterized in that The plurality of guide groups are staggered in the second direction, and the staggered distance is 0 mm to 1.5 mm.

9. A fuel cell plate, characterized in that: At least one side surface of the fuel cell plate comprises the flow field as claimed in any one of claims 1 to 8.

10. The fuel cell plate according to claim 9, characterized in that: The electrode plate is any one of an anode plate, a cathode plate, and a bipolar plate.

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