Cathode open type air-cooled fuel cell bipolar plate and cell stack

Abstract

The invention belongs to the technical field of fuel cells, and discloses a cathode open type air-cooled fuel cell bipolar plate and a cell stack. The cathode open type air-cooled fuel cell bipolar plate comprises a bipolar plate body and a vapor chamber assembly which are integrally formed, one surface of the bipolar plate body is an anode flow field area side, and the other surface of the bipolar plate body is a cathode flow field area side; a plurality of air runners are arranged on the cathode flow field area side, and a runner ridge part between every two adjacent air runners is provided with a ridge part opening hole; the vapor chamber assembly comprises two vapor chambers, and the vapor chambers are symmetrically arranged on the inner side of the annular flow field structure in the circumferential direction. The bipolar plate of the cathode open type air-cooled fuel cell does not need to change the main structure of a cell stack, is easy to process and form, can effectively improve the gas distribution of a flowing dead zone at the ridge part of the bipolar plate, enhances the forced convection effect of a cell stack fan, and enhances the mass and heat transfer performance of the fuel cell.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to an open-cathode air-cooled fuel cell bipolar plate and a cell stack. Background Art

[0002] A proton exchange membrane fuel cell, whose full English name is Proton Exchange Membrane Fuel Cell, abbreviated as PEMFC, is an electrochemical reaction device that converts chemical energy into electrical energy. Among them, an open-cathode proton exchange membrane fuel cell combines the cathode oxidant supply flow field and the cooling flow field and is open to the environment for contact. While directly using ambient air as the oxidant, it cools the PEMFC, eliminating complex subsystems such as cooling, cathode inlet humidification, and pressure control, and enabling the design of a fuel cell system with a compact structure and a higher volume power density, which is widely used in the fields of portable power sources and light-load devices.

[0003] The bipolar plate is one of the key components of a proton exchange membrane fuel cell. Its functions include supporting the membrane electrode assembly, distributing reaction gases and coolant, collecting current, conducting heat, and discharging product water, etc. The bipolar plate flow field is variously shaped grooves machined on the bipolar plate, providing inlet and outlet channels for reaction gases, cooling media, and generated products, and is a key factor in fuel cell design. However, in the prior art, there are flow channel dead zones in the ridges of the cathode flow field of the open-cathode air-cooled PEMFC bipolar plate. When there is a high-density current in the cathode flow field, the oxygen supply on the cathode side is insufficient, resulting in uneven cathode gas distribution; at the same time, the open-cathode air-cooled PEMFC uses the same cathode flow channel for cooling and reaction gas supply. Its special cathode structure leads to the problem of coupled water and heat management in the fuel cell, with uneven cooling and heat dissipation of the fuel cell and serious dry film of the membrane electrode. The uneven distribution of gas and temperature in the cathode flow field of the open-cathode air-cooled PEMFC seriously affects the mass transfer and heat transfer performance of the fuel cell.

[0004] To solve the above technical problems, optimizing the cathode flow channel structure design is the most direct and effective measure to improve the cathode open-type PEMFC, which is crucial for minimizing ohmic losses and enhancing the uniformity of physical quantity distribution within the membrane electrode assembly. Currently, most of the existing technologies optimize the cathode flow field structure design of the bipolar plate for the cathode open-type air-cooled PEMFC by means of the "ridge-groove" shape of the flow channel, cross-sectional area, flow channel diversion, setting of block protrusions, etc., so as to strengthen the mass transfer and heat transfer processes of the cathode gas through forced convection and improve the performance of the fuel cell. For example, the existing technology CN106165172A proposes to strengthen the heat dissipation process of the air-cooled fuel cell by setting a heat-conducting heat sink plate in the cooling channel of the air-cooled fuel cell and designing a partition plate with a partition wall, air flow disturbing protrusions, and transverse air flow bypassing wheel protrusions. However, after setting the heat-conducting heat sink plate in this existing technology, the original structure of the cathode flow channel is changed, the complexity of the flow channel structure is increased, it is not easy to process and form, the processing cost of the plate is high, and it is not conducive to mass production of the product. In the bipolar plate anode flow field of the existing technology CN113451602A, a serpentine flow field is adopted, and the pressure loss of hydrogen in the anode flow channel is relatively large, and the distribution of hydrogen at the inlet and outlet of the anode flow channel is uneven; there is a large temperature gradient at the inlet and outlet of the cathode flow field of the cathode open-type air-cooled proton exchange membrane fuel cell, especially in the fuel cell stack with a circular cylindrical shape, the temperature in the central fan air duct is relatively high, and the annular air duct is not conducive to heat dissipation. Based on the above, the above existing technologies still cannot effectively solve the problems of uneven gas distribution in the cathode flow field ridge, uneven temperature distribution inside the fuel cell stack, serious dry membrane at high current density, and poor water and heat management performance of the fuel cell stack in the cathode open-type air-cooled proton exchange membrane fuel cell. Summary of the Invention

[0005] To solve the technical problems of uneven gas distribution in the cathode flow field ridge, uneven temperature distribution inside the fuel cell stack, serious dry membrane at high current density, and poor water and heat management performance of the fuel cell stack existing in the above-mentioned cathode open-type air-cooled proton exchange membrane fuel cell technologies, the present invention provides a bipolar plate and a fuel cell stack for a cathode open-type air-cooled fuel cell.

[0006] The bipolar plate and the fuel cell stack for a cathode open-type air-cooled fuel cell of the present invention are achieved through the following technical solutions:

[0007] A bipolar plate for a cathode open-type air-cooled fuel cell includes a bipolar plate body and a heat sink plate assembly integrally formed within the bipolar plate body, that is, the heat sink plate assembly of the present invention is integrally formed with the bipolar plate body, making the bipolar plate for the cathode open-type air-cooled fuel cell of the present invention easy to process and form, and no external partition plate is required. Among them, the bipolar plate body has a circular flow field structure with an integrated heat sink plate.

[0008] One side of the bipolar plate body of the present invention is the anode flow field region side, and a plurality of hydrogen gas channels are arranged on the anode flow field region side.

[0009] The other side of the bipolar plate body is the cathode flow field region side, and a plurality of air channels are arranged on the cathode flow field region side; the plurality of air channels are arranged in sequence along the radial direction of the circular ring flow field structure, and the channel width of each air channel gradually increases along the radial direction from the center of the circular ring flow field structure, that is, the air channel of the present invention is a gradient air channel.

[0010] In the present invention, there is a channel ridge between adjacent two of the air channels, and a ridge opening is arranged on each channel ridge, and the ridge opening is in three-dimensional directions. By means of the ridge opening of the cathode channel, on the one hand, the gas distribution between the cathode flow field ridge and the flow dead zone of the membrane electrode can be increased, and on the other hand, the disturbance effect of the cooling fluid of adjacent cathode channels can be strengthened, and the temperature distribution uniformity of the fuel cell can be improved.

[0011] In the present invention, the heat sink assembly includes two heat sinks with the same structure, and the two heat sinks are symmetrically arranged along the circumferential direction inside the circular ring flow field structure, so as to strengthen the removal of heat inside the inner side of the annular bipolar plate by exposing each heat sink assembly at the center of the annular plate. In the present invention, preferably, the two heat sinks are respectively a first heat sink and a second heat sink, and the first heat sink and the second heat sink are symmetrically arranged with the center of the circular ring flow field structure as the symmetry center, so that the heat sink structure of the present invention does not need to change the main structure of the fuel cell stack; and by stacking a plurality of the cathode open-air-cooled fuel cell bipolar plates of the present invention in sequence, the heat sink assemblies in adjacent two of the cathode open-air-cooled fuel cell bipolar plates are arranged in a staggered manner inside the cylindrical fuel cell stack, so as to realize arranging a plurality of heat sinks in a staggered manner inside the air duct of the fan, thereby effectively strengthening the gas and temperature distribution of the cathode flow field of the cathode open-air-cooled proton exchange membrane fuel cell, enhancing the forced convection effect of the fan of the cathode open-air-cooled PEMFC stack, strengthening the mass transfer and heat transfer performance of the fuel cell, and improving the water and heat management performance of the fuel cell.

[0012] In some preferred embodiments of the present invention, a plurality of through - hole groups are arranged along the circumferential direction of the circular - ring flow - field structure on the side of the anode flow - field region. Each through - hole group includes two through - holes symmetrically arranged about the center. Among them, two adjacent through - hole groups are respectively used as a hydrogen - input group and a hydrogen - output group. And the first heat - spreader and the second heat - spreader in each heat - spreader assembly are respectively arranged inside the cathode flow - field region corresponding to the two through - holes of the hydrogen - input group or the hydrogen - output group, so as to arrange a plurality of heat - spreaders in a three - dimensional alternating distribution manner inside the circular - ring flow - field structure. Thus, each heat - spreader can affect the air duct of the fan inside the circular - cylinder fuel - cell stack through fins. On the one hand, each heat - spreader can indirectly strengthen the air flow at the inlet of the cathode open - type air - cooled PEMFC cathode flow - field by disturbing the fluid in the fan air duct, and further strengthen the mass transfer and heat transfer process of the air in the cathode flow - field. On the other hand, it can accelerate the heat dissipation of the heat - spreader itself through the disturbance of the fan air - duct fluid, and strengthen the heat - dissipation performance of the heat - spreader assembly.

[0013] For example, in some more preferred embodiments of the invention, two through - hole groups are arranged along the circumferential direction of the circular - ring flow - field structure on the side of the anode flow - field region. Among them, one through - hole group is two hydrogen inlets symmetrically arranged about the center, and the other through - hole group is two hydrogen outlets symmetrically arranged about the center.

[0014] In some preferred embodiments of the present invention, an anode sealing groove is arranged on the side of the anode flow - field region to surround and seal a plurality of the through - hole groups and a plurality of the hydrogen flow channels, for placing a matching sealing ring to prevent hydrogen leakage from the anode of the bipolar plate or the cross - leakage of hydrogen and oxygen gases.

[0015] In some preferred embodiments of the present invention, the hydrogen flow channel is arc - shaped to reduce the pressure drop of the gas in the anode flow channel and improve the gas - distribution uniformity on the anode side. And the hydrogen in the anode flow - field region enters the anode flow channel through the through - holes corresponding to the hydrogen inlets in each hydrogen - input group, distributes the gas to the arc - shaped flow channels on both sides through the hydrogen inlets respectively, and flows out through the through - holes corresponding to the hydrogen outlets in each hydrogen - input group after being mixed at the hydrogen outlets respectively.

[0016] In some preferred embodiments of the present invention, the holes on the ridges of two adjacent air flow channels are arranged in a straight line or staggered arrangement to further improve the improvement effect of the gas distribution in the flow - dead zone of the bipolar - plate ridge. At the same time, it can further enhance the disturbance of the fluid between different cathode flow channels, strengthen the mass transfer and heat transfer process of the air in the cathode flow channel, and improve the performance of the cathode open - type air - cooled PEMFC.

[0017] In some preferred embodiments of the present invention, each heat sink plate is arranged in a sector structure, and each heat sink plate is radially radiated with the center of the circular annular flow field structure as the center, so as to realize the integral molding of the bipolar plate and the heat sink plate, and there is no need to additionally add a heat sink plate externally, reducing the volume of the heat sink plate occupied by the stack. At the same time, through the fluid disturbance in the internal air duct of the annular bipolar plate, the heat dissipation performance of the air-cooled stack is enhanced.

[0018] In some preferred embodiments of the present invention, the material of the heat sink plate is a graphite-based material or a metal-based material.

[0019] In some preferred embodiments of the present invention, the graphite-based material is any one of flexible graphite, expanded graphite and graphite composite material; the metal-based material is a stainless steel stamping bipolar plate material or a titanium stamping bipolar plate material.

[0020] The second object of the present invention is to provide a cathode open fuel cell stack, which includes a plurality of the above-mentioned cathode open air-cooled fuel cell bipolar plates.

[0021] In some preferred embodiments of the present invention, a plurality of the cathode open air-cooled fuel cell bipolar plates are stacked in sequence, and the heat sink plate assemblies in adjacent two cathode open air-cooled fuel cell bipolar plates are arranged in an interleaved manner inside the cylindrical fuel cell stack to strengthen the forced convection of air in the fan air duct; and each cathode open air-cooled fuel cell bipolar plate is respectively assembled with a membrane electrode assembly, an end plate and a current collector plate to assemble into a fuel cell stack.

[0022] In some preferred embodiments of the present invention, a plurality of the cathode open air-cooled fuel cell bipolar plates are coaxially stacked in sequence to form a cylindrical structure, so that the fuel cell stack of the present invention is a cylinder as a whole. And because the heat sink plate assemblies in adjacent two cathode open air-cooled fuel cell bipolar plates are arranged in an interleaved manner, there are a plurality of heat sink plates arranged in an interleaved manner inside the formed cylinder, that is, in the air duct of the fan. And the above-mentioned plurality of cathode open air-cooled fuel cell bipolar plates are assembled with a matching membrane electrode, end plate, current collector plate, etc. into a stack; a fan is installed at one end of the fuel cell stack cylinder, and the inside of the cylinder is an air duct of the fan embedded inside the stack; when the fan works, external air is sucked into the air flow channel from the periphery of the bipolar plate.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The cathode open-air-cooled fuel cell bipolar plate of the present invention includes a bipolar plate body and a heat sink assembly integrally formed, without the need to add an external separator. The heat sink structure does not require changing the main structure of the fuel cell stack and is easy to process and form. The present invention improves the gas distribution in the flow dead zone of the bipolar plate ridge by opening holes in the ridge of the cathode flow channel, solves the problem of uneven cathode gas distribution in the existing cathode open-air-cooled fuel cell, and at the same time, by opening holes in the ridge of the cathode flow channel, enhances the fluid disturbance between different cathode flow channels, strengthens the mass transfer and heat transfer process of the air in the cathode flow channel, and improves the performance of the cathode open-air-cooled PEMFC. At the same time, several heat sink assemblies are arranged on the inner side of the circular flow field structure in the circumferential direction, that is, several heat sinks are arranged in the air duct of the fan, so as to effectively strengthen the gas and temperature distribution of the cathode flow field of the cathode open-air-cooled proton exchange membrane fuel cell, enhance the forced convection effect of the cathode open-air-cooled PEMFC stack fan, strengthen the mass transfer and heat transfer performance of the fuel cell, improve the water and heat management performance of the fuel cell, and thus solve the problems of uneven gas distribution in the ridge of the cathode flow field, uneven internal temperature distribution of the fuel cell stack, serious dry film at high current density, and poor water and heat management performance of the fuel cell stack in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FIG. is a schematic structural diagram of the cathode flow field region side of the cathode open-air-cooled fuel cell bipolar plate of the present invention.

[0026] Figure 2 FIG. is a schematic structural diagram of the anode flow field region side of the cathode open-air-cooled fuel cell bipolar plate of the present invention.

[0027] Figure 3 FIG. is a schematic structural diagram when two adjacent cathode open-air-cooled fuel cell bipolar plates are assembled.

[0028] Figure 4 FIG. is a three-dimensional structural schematic diagram of the stack structure formed by assembling two adjacent cathode open-air-cooled fuel cell bipolar plates.

[0029] Figure 5 is Figure 4 a top view of the stack structure in

[0030] The reference numerals in the figure are:

[0031] 1 - bipolar plate body, 101 - anode flow field region side, 102 - anode flow field region side; 11 - first bipolar plate; 12 - second bipolar plate.

[0032] 2 - heat sink assembly, 201 - first heat sink, 202 - second heat sink.

[0033] 3 - hydrogen flow channel. 4 - air flow channel. 5 - hole in the ridge.

[0034] 6 - Through - hole group, 601 - Hydrogen input group, 602 - Hydrogen output group.

[0035] 7 - Anode sealing groove.

[0036] 8 - Flow channel ridge. Detailed implementation manners

[0037] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely.

[0038] Embodiment 1

[0039] In this embodiment, a cathode - open - type air - cooled fuel cell bipolar plate is provided.

[0040] Please refer to Figure 1 and Figure 2 , the cathode - open - type air - cooled fuel cell bipolar plate in this embodiment includes a bipolar plate body 1 and a heat - sink plate assembly 2 integrally formed within the bipolar plate body 1.

[0041] The bipolar plate body 1 has an annular flow - field structure with an integrated heat - sink plate. One side of the bipolar plate body 1 in this embodiment is the anode flow - field region side 101, and the other side is the cathode flow - field region side 102.

[0042] Please refer to Figure 1 , in this embodiment, a plurality of air flow channels 4 are provided on the cathode flow - field region side 102; the plurality of air flow channels 4 are arranged in sequence along the radial direction of the annular flow - field structure, and the flow - channel width of each air flow channel 4 gradually increases along the radial direction from the center of the annular flow - field structure, that is, the air flow channel 4 of the present invention is a gradient - type air flow channel.

[0043] Moreover, there is a flow - channel ridge 8 between adjacent two air flow channels 4 in this embodiment. Each flow - channel ridge 8 is provided with a ridge opening 5, and the ridge opening 5 is in three - dimensional directions. On the one hand, through the ridge opening 5, the gas distribution between the cathode flow - field ridge and the flow - dead zone of the membrane electrode can be increased. On the other hand, the ridge opening 5 can strengthen the disturbance effect of the cooling fluid in adjacent cathode flow channels and improve the temperature distribution uniformity of the fuel cell.

[0044] Please refer to Figure 2 , a plurality of hydrogen flow channels 3 are provided on the anode flow - field region side 101 of this embodiment, and each hydrogen flow channel 3 is arc - shaped. And in this embodiment, two through - hole groups 6 are provided along the circumferential direction of the annular flow - field structure on the anode flow - field region side 101, that is, the adjacent hydrogen input group 601 and hydrogen output group 602. Among them, the two through - holes in the hydrogen input group 601 are two hydrogen inlets symmetrically arranged at the center, and the two through - holes in the hydrogen output group 602 are two hydrogen outlets symmetrically arranged at the center.

[0045] Please refer to Figure 1 and Figure 2 In this embodiment, the heat pipe assembly 2 includes two heat pipes with the same structure, namely the first heat pipe 201 and the second heat pipe 202. The first heat pipe 201 and the second heat pipe 202 are symmetrically arranged inside the circular annular flow field structure with the center of the circular annular flow field structure as the symmetry center, so as to strengthen the removal of heat inside the annular bipolar plate by exposing multiple heat pipes at the center of the annular electrode plate.

[0046] Please refer to Figure 3 In a preferred embodiment of the present invention, an anode sealing groove 7 is provided on the anode flow field region side 101 to seal a plurality of the through-hole groups 6 and a plurality of the hydrogen flow channels 3, for placing a matching sealing ring to prevent hydrogen leakage from the anode of the bipolar plate or cross-flow of hydrogen and oxygen gases.

[0047] Please refer to Figure 2 In a preferred embodiment of the present invention, the ridge openings 5 of two adjacent air flow channels 4 are arranged in a straight line or staggered, so as to further improve the improvement effect of gas distribution in the flow dead zone of the bipolar plate ridge. At the same time, it can further enhance the fluid disturbance between different cathode flow channels, strengthen the mass transfer and heat transfer process of air in the cathode flow channel, and improve the performance of the cathode open-type air-cooled PEMFC.

[0048] Please refer to Figures 1 - 2 In a preferred embodiment of the present invention, each first heat pipe 201 and each second heat pipe 202 are arranged in a fan-shaped structure, and each first heat pipe 201 and each second heat pipe 202 are radially radiated with the center of the circular annular flow field structure as the center, so as to realize the integral molding of the bipolar plate and the heat pipe, and there is no need to additionally add a heat pipe externally, reducing the volume of the heat pipe occupied by the stack. At the same time, through the fluid disturbance in the internal air duct of the annular bipolar plate, the heat dissipation performance of the air-cooled stack is strengthened.

[0049] In a preferred embodiment of the present invention, the material of the heat pipe is a graphite-based material or a metal-based material.

[0050] In a preferred embodiment of the present invention, the graphite-based material is any one of flexible graphite, expanded graphite, and graphite composite material; the metal-based material is a stainless steel stamping electrode plate material or a titanium stamping electrode plate material.

[0051] Embodiment 2

[0052] This embodiment provides a cathode-open fuel cell stack, which includes a plurality of the above-mentioned cathode-open air-cooled fuel cell bipolar plates 1. The plurality of cathode-open air-cooled fuel cell bipolar plates 1 are coaxially stacked in sequence to form a cylindrical structure, so that the cathode-open fuel cell stack of the present invention is a cylindrical structure as a whole.

[0053] In this embodiment, each of the cathode-open air-cooled fuel cell bipolar plates 1 is respectively assembled with a membrane electrode assembly, an end plate and a current collector plate to assemble a fuel cell stack. And a fan is installed at one end of the cylindrical structure of the cathode-open fuel cell stack, and the air duct of the fan is embedded inside the cylindrical structure of the cathode-open fuel cell stack.

[0054] To facilitate understanding of the assembly relationship between two adjacent cathode-open air-cooled fuel cell bipolar plates when forming the fuel cell stack of the present invention, please refer to Figures 3 - 5 , in this embodiment, the heat sink assemblies 2 in two adjacent cathode-open air-cooled fuel cell bipolar plates 1 are arranged in an interleaved manner, so that a plurality of heat sinks are arranged in an interleaved manner inside the cylindrical structure of the fuel cell stack, thereby strengthening the forced convection of the air in the fan air duct. When the fan works, external air is sucked into the air flow channel from the periphery of the cathode-open air-cooled fuel cell bipolar plate 1. When the cathode-open air-cooled fuel cell bipolar plates 1 of this embodiment are assembled into an air-cooled stack, the heat sinks in the extended area extend into the air duct of the fan, which not only enhances the disturbance of the air inside the cathode flow channel, but also speeds up the removal of its own heat, double-strengthening the heat dissipation process of the fuel cell stack and improving the uniformity of the temperature distribution inside the stack.

[0055] And two adjacent cathode-open air-cooled fuel cell bipolar plates are respectively denoted as the first bipolar plate 11 and the second bipolar plate 12.

[0056] In this embodiment, a heat sink assembly 2 is arranged in the circumferential direction of the circular flow field structure of the first bipolar plate 11, and the heat sink of the heat sink assembly 2 on the first bipolar plate 11 is arranged inside the cathode flow field area corresponding to the two hydrogen inlets of the first bipolar plate 11. The structure of the second bipolar plate 12 is the same as that of the first bipolar plate 11.

[0057] Among them, the first heat spreader 201 and the second heat spreader 202 in the first bipolar plate 11 are respectively arranged inside the cathode flow field regions corresponding to two hydrogen inlets in the hydrogen input group 601, and the first heat spreader 201 and the second heat spreader 202 in the second bipolar plate 12 are respectively arranged inside the cathode flow field regions corresponding to two hydrogen outlets in the hydrogen output group 602. Hydrogen in the anode flow field region enters the anode flow channel through the through holes corresponding to the hydrogen inlets in each hydrogen input group 601, and the gas is respectively distributed to the arc-shaped flow channels on both sides. Then, it is mixed and flows out through the through holes corresponding to the hydrogen outlets in each hydrogen output group in the hydrogen output group 602. As a result, the four heat spreaders in the first bipolar plate 11 and the second bipolar plate 12 are alternately arranged inside the fan air duct in the cylindrical fuel cell stack. On the one hand, it can indirectly strengthen the air flow at the inlet of the cathode flow field of the cathode open-type air-cooled PEMFC by disturbing the fluid in the fan duct, thereby strengthening the mass transfer and heat transfer process of the air in the convective enhanced cathode flow field. On the other hand, the heat spreader assembly can accelerate the heat dissipation of the heat spreader itself through the disturbance of the fluid in the fan duct, strengthening the heat dissipation performance of the heat spreader assembly.

[0058] Obviously, the above-mentioned embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

Claims

1. A cathode open air-cooled fuel cell bipolar plate, characterized in that: It comprises a bipolar plate body (1), and a heat spreader assembly (2) integrally formed in the bipolar plate body (1); The bipolar plate body (1) has a circular annular flow field structure with an integrated heat spreader; One side of the bipolar plate body (1) is an anode flow field region side (101), and a plurality of hydrogen flow channels (3) are provided on the anode flow field region side (101); The other side of the bipolar plate body (1) is a cathode flow field region side (102), and a plurality of air flow channels (4) are arranged on the cathode flow field region side (102); the plurality of air flow channels (4) are sequentially arranged along the radial direction of the annular flow field structure, and the flow channel width of each air flow channel (4) gradually increases along the radial direction from the center of the annular flow field structure; there is a flow channel ridge (8) between two adjacent air flow channels (4), and each of the flow channel ridges (8) is provided with a ridge opening (5); The vapor chamber assembly (2) comprises two vapor chambers with identical structures, and the two vapor chambers are symmetrically arranged on the inner side of the annular flow field structure along the circumferential direction to enhance heat dissipation in the bipolar plate flow field area.

2. The cathode open air-cooled fuel cell bipolar plate according to claim 1, characterized in that: The anode flow field region side (101) is provided with a plurality of through hole groups (6) along the circumference of the annular flow field structure, each of the through hole groups (6) comprising two through holes that are centrally symmetrically arranged; Two adjacent through hole groups (6) serve as a hydrogen input group (601) and a hydrogen output group (602) respectively; The two vapor chambers in each vapor chamber assembly (2) are respectively arranged inside the cathode flow field area corresponding to the two through holes of the hydrogen input group (601) or the hydrogen output group (602).

3. The cathode open air-cooled fuel cell bipolar plate according to claim 2, characterized in that: An anode sealing groove (7) is provided on the anode flow field area side (101), surrounding and sealing a plurality of the through hole groups (5) and a plurality of the hydrogen flow channels (3), and is used to place a corresponding sealing ring to prevent hydrogen leakage from the bipolar plate anode or hydrogen and oxygen gas cross-talk.

4. The cathode open air-cooled fuel cell bipolar plate according to claim 1, characterized in that: The hydrogen flow channel (3) is in an arc shape.

5. The cathode open air-cooled fuel cell bipolar plate according to claim 1, characterized in that: The ridge openings (5) of two adjacent air flow channels (4) are arranged in a straight line or in a staggered arrangement.

6. The cathode open air-cooled fuel cell bipolar plate according to claim 1, characterized in that: Each of the heat spreaders is arranged in a fan-shaped structure, and each of the heat spreaders is arranged radially with the center of the annular flow field structure as the center.

7. The cathode open air-cooled fuel cell bipolar plate according to claim 1, characterized in that: The material of the heat spreader is graphite material or metal material.

8. The cathode open air-cooled fuel cell bipolar plate according to claim 7, characterized in that: The graphite material is any one of flexible graphite, expanded graphite and graphite composite material; The metal material is a stainless steel stamped plate material or a titanium stamped plate material.

9. A cathode open fuel cell stack, characterized in that: The invention comprises a plurality of cathode open air-cooled fuel cell bipolar plates as described in any one of claims 1 to 8.

10. The cathode open fuel cell stack according to claim 9, characterized in that: A plurality of the cathode open air-cooled fuel cell bipolar plates are stacked in sequence, and the vapor chamber assemblies in two adjacent cathode open air-cooled fuel cell bipolar plates are staggeredly arranged inside the column fuel cell stack to strengthen the forced convection of air in the fan duct; Each of the cathode open air-cooled fuel cell bipolar plates is respectively equipped with a membrane electrode assembly, an end plate and a current collecting plate to assemble into a battery stack.

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