Biomimetic H-shaped flow field fuel cell bipolar plate and method thereof

Abstract

The present invention relates to the technical field of fuel cells, and discloses a fuel cell bipolar plate of a bionic H-shaped flow field, the fuel cell bipolar plate comprises a cell bipolar plate body, the cell bipolar plate body comprises an inlet, the inlet is engraved with a center main flow channel along the vertical direction of the inlet, and the center main flow channel is provided with an inlet. A first-stage top end flow channel and a second-stage top end flow channel are engraved in the vertical direction connected with the inlet, and a first-stage left side flow channel, a second-stage left side flow channel, a third-stage left side flow channel and a fourth-stage left side flow channel are sequentially formed in the side surface of the battery bipolar plate body. According to the fuel cell bipolar plate of the bionic H-shaped flow field and the method thereof, a gas and water transmission mechanism in the flow field is changed through the mechanism, reaction gas is directionally and uniformly distributed, and the mass transfer efficiency is improved while circulating mass transfer, water drainage, pressure drop reduction and pumping power of a multi-stage flow channel unit structure are realized, so that the water management of a fuel cell is improved; and finally, the performance and stability of the fuel cell are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell bipolar plate with a bionic H-type flow field and a method thereof. Background Art

[0002] With the accelerated advancement of industrialization and modernization around the world, human demand for energy is increasing. However, the widespread use of fossil energy has triggered the dual challenges of energy depletion and environmental degradation. The energy problem is not only a key issue concerning the survival and development of human society, but has also become a global problem that needs to be solved urgently. Hydrogen energy is considered to be the "ultimate energy" of the future because it has the advantages of both traditional energy and new energy (high energy density, green and low-carbon, and a wide range of sources). The main way to utilize hydrogen energy is through proton exchange membrane fuel cells. Proton exchange membrane fuel cells are a power generation device that directly converts chemical energy stored in hydrogen and oxidants into electrical energy through electrochemical reactions. They are not restricted by the Carnot cycle and have the advantages of simple structure, high energy conversion efficiency, clean and environmentally friendly, zero carbon emissions, low noise, low operating temperature, and fast startup response. They are widely considered to be one of the most promising clean and efficient energy technologies in the future, which helps to optimize the energy structure and is of great significance to solving energy problems.

[0003] The bipolar plate is one of the key components of proton exchange membrane fuel cells. Its main functions include collecting and conducting current, separating fuel and oxidant, supporting membrane electrodes, and dissipating heat. In addition, the surface of the plate is designed with a flow field structure. Another key function is to transmit, distribute and discharge the reactants and products inside the battery. Whether the flow field design is reasonable will directly affect whether the electrochemical reaction can proceed normally. Different flow fields are composed of gas flow channels (grooves) of different shapes and structures and supporting ridges. The flow field structure not only affects the contact resistance between the bipolar plate and the membrane electrode, but also affects the mass transfer and drainage process. The product water of the traditional parallel flow field is easy to accumulate in a local area, causing insufficient supply of reactants. The longer flow channel of the serpentine flow field increases the pressure drop, resulting in pumping power loss. Although the interdigitated flow field improves battery performance, its large pressure drop will cause pumping power loss and shorten battery life. The flow resistance of the reaction gas in the point flow field is reduced, and the pumping power loss is reduced accordingly, but gas stagnation and water flooding are prone to occur in local areas. So far, we have proposed a fuel cell bipolar plate with a bionic H-type flow field and a method thereof. Summary of the invention

[0004] In view of the shortcomings of the existing bionic H-type flow field fuel cell bipolar plates and methods, the present invention provides a bionic H-type flow field fuel cell bipolar plate and method, which has a multi-stage flow channel unit structure for cyclic mass transfer and drainage, reduces pressure drop and pumping power while improving mass transfer efficiency, improves water management of fuel cells, and ultimately improves the performance and stability of fuel cells, solving the problems raised in the above-mentioned background technology.

[0005] The present invention provides the following technical solution: a bionic H-type flow field fuel cell bipolar plate, comprising a battery bipolar plate body, the battery bipolar plate body comprising an inlet, the inlet being engraved with a central main flow channel along the vertical direction of the inlet, a first-level top flow channel and a second-level top flow channel being engraved in the vertical direction connected to the inlet, a first-level left-side flow channel, a second-level left-side flow channel, a third-level left-side flow channel and a fourth-level left-side flow channel being sequentially opened on the side of the battery bipolar plate body, a first outlet and a second outlet being opened on both sides of the lower part of the battery bipolar plate body, a first-level bottom flow channel and a second-level bottom flow channel being opened on both sides of the lower part of the battery bipolar plate body, a first-level H-type flow channel unit, a second-level H-type flow channel unit, a third-level H-type flow channel unit and a third-level H-type flow channel unit being opened in the interior of both sides of the first-level left-side flow channel, the second-level left-side flow channel, the third-level left-side flow channel and the fourth-level left-side flow channel, the battery bipolar plate body is a flat plate, a flow channel structure is engraved on it, and the flow channel bottom is a gradient sinusoidal wave structure.

[0006] Preferably, a right side flow channel is provided on the right side of the inside of the battery bipolar plate body and aligned with the first-level left side flow channel, the second-level left side flow channel, the third-level left side flow channel and the fourth-level left side flow channel. The right side flow channel has the same structure as the first-level left side flow channel, the second-level left side flow channel, the third-level left side flow channel and the fourth-level left side flow channel. At the same time, the amplitude and length of the first-level left side flow channel, the second-level left side flow channel, the third-level left side flow channel and the fourth-level left side flow channel from the inlet to the outlet increase in a gradient, satisfying k=1.1·k2=1.1 2 k3 = 1.1 3 k4, L T1 =1.1·L T2 =1.1 2 ·L T3 =1.1 3 ·L T4 .

[0007] Preferably, the central main flow channel is divided into four levels in the vertical direction of air flow transmission, and the width and length of the flow channel of each level decreases gradually, respectively satisfying M V1 =1.1·M V2 =1.1 2 ·M V3 =1.1 3 ·M V4, H L1 =1.1·H L2 =1.1 2 ·H L3 =1.1 3 ·H L4 .

[0008] Preferably, the width and length of each level of the primary top flow channel and the secondary top flow channel decrease in a gradient, respectively satisfying W A1 =1.1 W A2 =, L H1 =1.1·L H2 .

[0009] Preferably, a vertical connecting flow channel is provided at the flow channel gradient point at the top of the battery bipolar plate body, and the vertical connecting flow channel is divided into four levels in the vertical direction of air flow transmission, and the flow channel width and length of each level increase in a gradient, such as Figure 4 The following table shows that N V1 =0.9·N V2 =0.9 2 ·N V3 =0.9 3 ·N V4 , K L1 =0.9·K L2 =0.9 2 ·K L3 =0.9 3 ·K L4 .

[0010] Preferably, the first-level left side channel, the second-level left side channel, the third-level left side channel and the fourth-level left side channel have the same number of levels as the central main channel in the direction of vertical airflow transmission, and the width and length of each level decrease in a gradient, respectively satisfying P V1 =1.1·P V2 =1.1 2 ·P V3 =1.1 3 ·P V4 , J L1 =1.1·J L2 =1.1 2 ·J L3 =1.1 3 ·J L4。

[0011] Preferably, the lengths and widths of the primary bottom flow channel and the secondary bottom flow channel increase in a gradient, and the gradient ratios are the same as those of the top flow channel.

[0012] Preferably, the first outlet and the second outlet of the bipolar plate flow field are formed at the confluence of the first-level left side flow channel, the second-level left side flow channel, the third-level left side flow channel and the fourth-level left side flow channel with the right side flow channel, the first-level bottom flow channel and the second-level bottom flow channel, and the top flow channel, the bottom flow channel and the side flow channel surround the main area of ​​the bipolar plate flow field.

[0013] Preferably, the flow channel unit is composed of a primary H-type flow channel unit, a secondary H-type flow channel unit, a tertiary H-type flow channel unit and a tertiary H-type flow channel unit, wherein the flow channel unit is composed of a primary H-type flow channel unit, a secondary H-type flow channel unit, a tertiary H-type flow channel unit and a tertiary H-type flow channel unit and upper and lower superimposed flow channels, and the intervals between the superimposed flow channels are equal, that is, S = 1.0 mm, and the primary H-type flow channel units, the secondary H-type flow channel units, the tertiary H-type flow channel units and the tertiary H-type flow channel units of different levels are connected by The vertical connecting flow channel and the central main flow channel are connected to each other. The main flow field area is composed of a primary H-type flow channel unit, a secondary H-type flow channel unit, a tertiary H-type flow channel unit and a tertiary H-type flow channel unit. The intervals between the primary H-type flow channel unit, the secondary H-type flow channel unit, the tertiary H-type flow channel unit and the tertiary H-type flow channel unit at each level in the vertical direction are equal, and the heights and widths of the primary H-type flow channel unit, the secondary H-type flow channel unit, the tertiary H-type flow channel unit and the tertiary H-type flow channel unit increase step by step, respectively satisfying W B1 =1.1 W B2 =1.1 2 ·W B3 =1.1 3 ·W B4 , L H1 =1.1·L H2 =1.1 2 ·L H3 =1.1 3 ·L H .

[0014] A method for a fuel cell bipolar plate with a bionic H-type flow field, the specific operation steps are as follows;

[0015] Step 1: When the fuel cell is working, the reaction gas enters from the inlet and passes through the gradient wavy structure at the bottom of the flow channel, changing the gas transmission direction, so that the reaction gas produces a speed perpendicular to the membrane electrode direction, and convection accelerates its transmission to the catalyst layer to participate in the electrochemical reaction. As the amplitude and length of the wavy structure gradually increase, the reaction gas transmission resistance increases, which can generate partial forced convection, and also improve the mass transfer efficiency of the battery;

[0016] Step 2: The top flow channel, the vertical connecting flow channel and the central main flow channel transmit the reaction gas to the H-type flow channel unit. The length and width of the flow channel decrease in a gradient along the gas transmission direction. The width of the flow channel is changed by the gradient, thereby changing the cross-sectional area of ​​the flow channel to transmit the same flow rate of reaction gas, ensuring that the side flow channel far from the inlet position can also obtain a larger reaction gas flow rate, so that the reaction gas is transmitted in a directional manner while improving the mass transfer efficiency of the flow field. At the same time, the widths of the central main flow channel, the vertical connecting flow channel and the side flow channels are added equal at the same level, so that the reaction gas of the H-type flow channel unit connected thereto enters the entire flow field at an equal flow rate for gas transmission;

[0017] Step 3: The length and width of the bottom flow channel increase in a gradient along the gas transmission direction, and the width of the bottom flow channel increases as the distance to the outlet decreases, so as to avoid the blockage of the bottom flow channel with too large a mass transfer task near the outlet, so that the reaction gas and product water collected from different H-type flow channel units and side flow channels are discharged in a gradient in time;

[0018] Step 4: The multi-level H-type flow channel unit performs cyclic mass transfer and drainage through the H-shaped structure flow channels and the upper and lower superimposed flow channels in its different levels. The reaction gas first enters the central main flow channel and the vertical connecting flow channel through the top flow channel, and then is transmitted to the upper superimposed flow channel of the first-level H-type flow channel unit. Due to their symmetrical distribution, they can be uniformly transmitted at the same time, so that the water generated by the reaction is quickly discharged, and then transmitted and distributed through the H-type structure flow channel. When the reaction gas reaches the lower superimposed flow channel, it is directly transmitted to the side flow channel, the vertical connecting flow channel, and the central main flow channel to complete the first transmission reaction in the H-type flow channel unit. Thereafter, multiple transmissions are performed according to the multi-level H-type flow channel units, so that the unreacted gas can be cyclically transmitted and utilized multiple times, so that there is no place in the flow field where the reaction gas has not reached.

[0019] Compared with the existing bionic H-type flow field fuel cell bipolar plate and method, the present invention has the following advantages:

[0020] Beneficial effects:

[0021] 1. The fuel cell bipolar plate and method of the bionic H-type flow field have a sinusoidal wave structure at the bottom of the flow channel, and the amplitude and length increase in a gradient. The crest and trough structure of the bottom flow channel makes the reaction gas flow perpendicular to the membrane electrode, and the convection enhances the mass transfer efficiency. At the same time, the trough gradually becomes smaller, which also promotes the rapid discharge of water generated by electrochemical.

[0022] 2. The fuel cell bipolar plate and method of the bionic H-type flow field have the top flow channel, the central main flow channel, the vertical connecting flow channel, and the bottom flow channels, and the width and length of the flow channels along the gas transmission direction are respectively reduced, reduced, increased, and increased in a gradient manner. The level number of the central main flow channel is equal to the level number of the vertical connecting flow channel and the left and right side flow channels. The width of the flow channel is changed by gradient, thereby changing the cross-sectional area of ​​the flow channel, and the flow channel is controlled to transmit the same flow rate of reaction gas at any position, ensuring that each flow channel far from the inlet position can also obtain a larger reaction gas flow rate, so that the reaction gas is transmitted in a directional manner while improving the mass transfer efficiency of the flow field and promoting uniform distribution of gas in the flow field.

[0023] 3. The fuel cell bipolar plate and method of the bionic H-type flow field have the same width as the sum of the central main channel, vertical connecting channel, and side channel. This allows the reaction gas of the H-type flow channel unit connected to it to enter the entire flow field at an equal flow rate for gas transmission, promotes uniform distribution of the flow field gas, and then allows the reaction gas to enter the catalyst layer evenly and quickly for electrochemical reaction.

[0024] 4. The bionic H-type flow field fuel cell bipolar plate and method thereof change the gas and water transmission mechanism inside the flow field through the above-mentioned mechanism, directionally and evenly distribute the reaction gas, and the multi-stage flow channel unit structure circulates mass transfer and drainage, thereby reducing pressure drop and pumping power while improving mass transfer efficiency, improving water management of fuel cells, and ultimately improving the performance and stability of fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a fuel cell bipolar plate of a bionic H-type flow field according to the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the bottom of the bionic flow channel of the present invention from the side close to the inlet to the side close to the outlet;

[0027] Figure 3 It is a schematic diagram of the bionic flow channel unit of the present invention;

[0028] Figure 4 It is a schematic diagram of the structural arrangement of the distribution channel, the collection channel and the multi-stage bionic channel unit of the present invention;

[0029] Figure 5 It is a schematic diagram of the structural arrangement of the bottom of the bionic flow channel of the present invention.

[0030] In the figure: 1. inlet; 2. central main flow channel; 3. vertical connecting flow channel; 41. first-level top flow channel; 42. second-level top flow channel; 51. first-level left side flow channel; 52. second-level left side flow channel; 53. third-level left side flow channel; 54. fourth-level left side flow channel; 61. first outlet; 62. second outlet; 71. first-level bottom flow channel; 72. second-level bottom flow channel; 81. first-level H-type flow channel unit; 82. second-level H-type flow channel unit; 83. third-level H-type flow channel unit; 84. third-level H-type flow channel unit; 9. right side flow channel. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] See also Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 A fuel cell bipolar plate and method of a bionic H-type flow field, comprising a battery bipolar plate body, the battery bipolar plate body comprising an inlet 1, the inlet 1 drives gas or liquid to circulate, the inlet 1 is engraved with a central main flow channel 2 along the vertical direction of the inlet, the inlet 1 is connected to a vertical direction with a first-level top flow channel 41 and a second-level top flow channel 42, the side of the battery bipolar plate body is sequentially provided with a first-level left side flow channel 51, a second-level left side flow channel 52, a third-level left side flow channel 53 and a fourth-level left side flow channel 54, the two sides of the lower part of the battery bipolar plate body are provided with a first outlet 61 and a second outlet 62, the first outlet 61 and the second outlet 62 drive liquid to be discharged, the battery bipolar plate A first-level bottom flow channel 71 and a second-level bottom flow channel 72 are sequentially opened on both sides of the lower part of the main body, and a first-level H-type flow channel unit 81, a second-level H-type flow channel unit 82, a third-level H-type flow channel unit 83 and a third-level H-type flow channel unit 84 are sequentially opened inside the first-level left side flow channel 51, the second-level left side flow channel 52, the third-level left side flow channel 53 and the fourth-level left side flow channel 54 on both sides. The battery bipolar plate body is a flat plate with a flow channel structure engraved thereon, and the bottom of the flow channel is a gradient sinusoidal wave structure. The crest and trough structure of the bottom flow channel makes the reaction gas produce a flow velocity perpendicular to the membrane electrode, and convection enhances the mass transfer efficiency. At the same time, the gradual reduction of the trough also promotes the rapid discharge of electrochemically generated water.

[0033] See also Figure 1A right side flow channel 9 is provided on the right side of the inside of the battery bipolar plate body and aligned with the first-level left side flow channel 51, the second-level left side flow channel 52, the third-level left side flow channel 53 and the fourth-level left side flow channel 54. The right side flow channel 9 has the same structure as the first-level left side flow channel 51, the second-level left side flow channel 52, the third-level left side flow channel 53 and the fourth-level left side flow channel 54. At the same time, the amplitude and length of the first-level left side flow channel 51, the second-level left side flow channel 52, the third-level left side flow channel 53 and the fourth-level left side flow channel 54 from the inlet to the outlet increase in gradient, satisfying k=1.1·k2=1.1 2 k3 = 1.1 3 k4, L T1 =1.1·L T2 =1.1 2 ·L T3 =1.1 3 ·L T4， By changing the width of the flow channel and thus the cross-sectional area of ​​the flow channel by gradient, the flow channel is controlled to transmit the same flow rate of reaction gas at any position, ensuring that each flow channel farther away from the inlet position can also obtain a larger reaction gas flow rate, so that the reaction gas is transmitted in a directional manner while improving the mass transfer efficiency of the flow field and promoting uniform distribution of gas in the flow field.

[0034] See also Figure 1 , the central main channel 2 is divided into four levels in the vertical direction of air flow transmission, and the width and length of the channel of each level decreases gradually, respectively satisfying M V1 =1.1·M V2 =1.1 2 ·M V3 =1.1 3 ·M V4 , H L1 =1.1·H L2 =1.1 2 ·H L3 =1.1 3 ·H L4 .

[0035] See also Figure 1 The width and length of each level of the primary top flow channel 41 and the secondary top flow channel 42 decrease in a gradient, respectively satisfying W A1 =1.1 W A2 =, L H1 =1.1·L H2 .

[0036] See also Figure 1 A vertical connecting flow channel 3 is provided at the flow channel gradient point at the top of the battery bipolar plate body. The vertical connecting flow channel 3 is divided into four levels in the vertical direction of air flow transmission. The width and length of the flow channel of each level increase in a gradient manner, such as Figure 4The following table shows that N V1 =0.9·N V2 =0.9 2 ·N V3 =0.9 3 ·N V4 , K L1 =0.9·K L2 =0.9 2 ·K L3 =0.9 3 ·K L4， The sum of the widths of the central main channel, vertical connecting channel, and side channel of the same level is equal, which allows the reaction gas of the H-type channel unit connected to it to enter the entire flow field at an equal flow rate for gas transmission, promotes uniform distribution of the flow field gas, and then allows the reaction gas to enter the catalyst layer evenly and quickly for electrochemical reaction.

[0037] See also Figure 1 The first-level left side channel 51, the second-level left side channel 52, the third-level left side channel 53 and the fourth-level left side channel 54 have the same number of levels as the central main channel 2 in the vertical direction of air flow transmission, and the width and length of each level decrease in a gradient, respectively satisfying P V1 =1.1·P V2 =1.1 2 ·P V3 =1.1 3 ·P V4 , J L1 =1.1·J L2 =1.1 2 ·J L3 =1.1 3 ·J L4。

[0038] See also Figure 1 The length and width of the first-stage bottom flow channel 71 and the second-stage bottom flow channel 72 both increase in a gradient, and the gradient ratio is the same as that of the top flow channel. The bottom flow channel undertakes the dual task of collecting the unreacted gas and the product water. The width of the bottom flow channel increases as the distance to the outlet decreases. While maintaining a low pressure drop, a larger flow rate near the outlet can be ensured, avoiding blockage of the collection flow channel with an excessively large mass transfer task near the outlet, so that the reaction gas and water are discharged in a gradient in a timely manner.

[0039] See also Figure 1The first left side flow channel 51, the second left side flow channel 52, the third left side flow channel 53 and the fourth left side flow channel 54 are combined with the right side flow channel 9, the first bottom flow channel 71 and the second bottom flow channel 72 to form the first outlet 61 and the second outlet 62 of the bipolar plate flow field. The top flow channel, the bottom flow channel and the side flow channels surround the main area of ​​the bipolar plate flow field, and the transmitted gas or liquid can be discharged through the first outlet 61 and the second outlet 62.

[0040] See also Figure 3 , the flow channel unit is composed of a primary H-type flow channel unit 81, a secondary H-type flow channel unit 82, a tertiary H-type flow channel unit 83 and a tertiary H-type flow channel unit 84, wherein the flow channel unit is composed of a primary H-type flow channel unit 81, a secondary H-type flow channel unit 82, a tertiary H-type flow channel unit 83 and a tertiary H-type flow channel unit 84 and upper and lower superimposed flow channels, and the intervals between the superimposed flow channels are equal, that is, S = 1.0 mm, and the primary H-type flow channel unit 81, the secondary H-type flow channel unit 82, the tertiary H-type flow channel unit 83 and the tertiary H-type flow channel unit 84 of different levels are connected by vertical The straight connecting flow channel and the central main flow channel are connected to each other, and the main flow field area is composed of a primary H-type flow channel unit 81, a secondary H-type flow channel unit 82, a tertiary H-type flow channel unit 83 and a tertiary H-type flow channel unit 84. The intervals between the primary H-type flow channel units 81, the secondary H-type flow channel units 82, the tertiary H-type flow channel units 83 and the tertiary H-type flow channel units 84 at each level in the vertical direction are equal, and the heights and widths of the primary H-type flow channel units 81, the secondary H-type flow channel units 82, the tertiary H-type flow channel units 83 and the tertiary H-type flow channel units 84 increase step by step, respectively satisfying W B1 =1.1 W B2 =1.1 2 ·W B3 =1.1 3 ·W B4 , L H1 =1.1·L H2 =1.1 2 ·L H3 =1.1 3 ·L H .

[0041] A method for a fuel cell bipolar plate with a bionic H-type flow field, the specific operation steps are as follows;

[0042] Step 1: When the fuel cell is working, the reaction gas enters from the inlet and passes through the gradient wavy structure at the bottom of the flow channel, changing the gas transmission direction, so that the reaction gas produces a speed perpendicular to the membrane electrode direction, and convection accelerates its transmission to the catalyst layer to participate in the electrochemical reaction. As the amplitude and length of the wavy structure gradually increase, the reaction gas transmission resistance increases, which can generate partial forced convection, and also improve the mass transfer efficiency of the battery;

[0043] Step 2: The top flow channel, the vertical connecting flow channel and the central main flow channel transmit the reaction gas to the H-type flow channel unit. The length and width of the flow channel decrease in a gradient along the gas transmission direction. The width of the flow channel is changed by the gradient, thereby changing the cross-sectional area of ​​the flow channel to transmit the same flow rate of reaction gas, ensuring that the side flow channel far from the inlet position can also obtain a larger reaction gas flow rate, so that the reaction gas is transmitted in a directional manner while improving the mass transfer efficiency of the flow field. At the same time, the widths of the central main flow channel, the vertical connecting flow channel and the side flow channels are added equal at the same level, so that the reaction gas of the H-type flow channel unit connected thereto enters the entire flow field at an equal flow rate for gas transmission;

[0044] Step 3: The length and width of the bottom flow channel increase in a gradient along the gas transmission direction, and the width of the bottom flow channel increases as the distance to the outlet decreases, so as to avoid blockage of the bottom flow channel with too large a mass transfer task near the outlet, so that the reaction gas and product water collected from different H-type flow channel units and side flow channels can be discharged in a gradient in time.

[0045] Step 4: The multi-level H-type flow channel unit performs cyclic mass transfer and drainage through the H-shaped structure flow channels and the upper and lower superimposed flow channels in its different levels. The reaction gas first enters the central main flow channel and the vertical connecting flow channel through the top flow channel, and then is transmitted to the upper superimposed flow channel of the first-level H-type flow channel unit. Due to their symmetrical distribution, they can be uniformly transmitted at the same time, so that the water generated by the reaction is quickly discharged, and then transmitted and distributed through the H-type structure flow channel. When the reaction gas reaches the lower superimposed flow channel, it is directly transmitted to the side flow channel, the vertical connecting flow channel, and the central main flow channel to complete the first transmission reaction in the H-type flow channel unit. Thereafter, multiple transmissions are performed according to the multi-level H-type flow channel units, so that the unreacted gas can be cyclically transmitted and utilized multiple times, so that there is no place in the flow field where the reaction gas has not reached.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A fuel cell bipolar plate with a bionic H-type flow field, comprising a battery bipolar plate body, wherein the battery bipolar plate body comprises an inlet (1), wherein the inlet (1) is engraved with a central main flow channel (2) along the vertical direction of the inlet, and wherein: A first-level top flow channel (41) and a second-level top flow channel (42) are engraved in the vertical direction connected to the inlet (1); a first-level left side flow channel (51), a second-level left side flow channel (52), a third-level left side flow channel (53) and a fourth-level left side flow channel (54) are sequentially opened on the side of the battery bipolar plate body; a first outlet (61) and a second outlet (62) are opened on both sides of the lower part of the battery bipolar plate body; a first-level bottom flow channel is sequentially opened on both sides of the lower part of the battery bipolar plate body (71) and a secondary bottom flow channel (72), the first-level left side flow channel (51), the second-level left side flow channel (52), the third-level left side flow channel (53) and the fourth-level left side flow channel (54) are provided with a first-level H-type flow channel unit (81), a second-level H-type flow channel unit (82), a third-level H-type flow channel unit (83) and a third-level H-type flow channel unit (84) in sequence inside the two sides of the first-level left side flow channel (51), the second-level left side flow channel (52), the third-level H-type flow channel unit (83) and the third-level H-type flow channel unit (84), the battery bipolar plate body is a flat plate, on which a flow channel structure is engraved, and the flow channel bottom is a gradient sinusoidal wave structure.

2. The fuel cell bipolar plate with a bionic H-type flow field according to claim 1, characterized in that: A right side flow channel (9) is provided on the right side of the battery bipolar plate body and aligned with the first-level left side flow channel (51), the second-level left side flow channel (52), the third-level left side flow channel (53) and the fourth-level left side flow channel (54). The right side flow channel (9) has the same structure as the first-level left side flow channel (51), the second-level left side flow channel (52), the third-level left side flow channel (53) and the fourth-level left side flow channel (54). At the same time, the first-level left side flow channel (51), the second-level left side flow channel (52), the third-level left side flow channel (53) and the fourth-level left side flow channel (54) increase their amplitude and length in a gradient from the inlet to the outlet, satisfying k=1.1·k2=1.

1. 2 k3 = 1.1 3 k4, L T1 =1.1·L T2 =1.1 2 ·L T3 =1.1 3 ·L T4 .

3. A bionic H-type flow field fuel cell bipolar plate and method according to claim 1, characterized in that: The central main flow channel (2) is divided into four levels in the vertical direction of air flow transmission, and the width and length of the flow channel of each level decreases in a gradient, respectively satisfying M V1 =1.1·M V2 =1.1 2 ·M V3 =1.1 3 ·M V4 , H L1 =1.1·H L2 =1.1 2 ·H L3 =1.1 3 ·H L4 .

4. The fuel cell bipolar plate with a bionic H-type flow field according to claim 1, characterized in that: The width and length of each level of the primary top flow channel (41) and the secondary top flow channel (42) decrease in a gradient, respectively satisfying W A1 =1.1 W A2 =, L H1 =1.1·L H2 .

5. The fuel cell bipolar plate with a bionic H-type flow field according to claim 1, characterized in that: A vertical connecting flow channel (3) is provided at the flow channel gradient point at the top of the battery bipolar plate body. The vertical connecting flow channel (3) is divided into four levels in the vertical direction of air flow transmission. The flow channel width and length of each level increase in a gradient manner. As shown in FIG. 4, N V1 =0.9·N V2 =0.9 2 ·N V3 =0.9 3 ·N V4 , K L1 =0.9·K L2 =0.9 2 ·K L3 =0.9 3 ·K L4 .

6. The fuel cell bipolar plate with a bionic H-type flow field according to claim 1, characterized in that: The first-level left-side flow channel (51), the second-level left-side flow channel (52), the third-level left-side flow channel (53) and the fourth-level left-side flow channel (54) have the same number of levels as the central main flow channel (2) in the direction of vertical air flow transmission, and the width and length of each level decrease in a gradient, respectively satisfying P V1 =1.1·P V2 =1.1 2 ·P V3 =1.1 3 ·P V4 , J L1 =1.1·J L2 =1.1 2 ·J L3 =1.1 3 ·J L4。 7. The fuel cell bipolar plate with a bionic H-type flow field according to claim 1, characterized in that: The lengths and widths of the primary bottom flow channel (71) and the secondary bottom flow channel (72) both increase in a gradient, and the gradient ratio is the same as that of the top flow channel.

8. The fuel cell bipolar plate with a bionic H-type flow field according to claim 1, characterized in that: The first left side flow channel (51), the second left side flow channel (52), the third left side flow channel (53) and the fourth left side flow channel (54) are joined with the right side flow channel (9), the first bottom flow channel (71) and the second bottom flow channel (72) to form a first outlet (61) and a second outlet (62) of the bipolar plate flow field, and the top flow channel, the bottom flow channel and the side flow channel enclose a main area of ​​the bipolar plate flow field.

9. The fuel cell bipolar plate with a bionic H-type flow field according to claim 1, characterized in that: The flow channel unit is composed of a primary H-type flow channel unit (81), a secondary H-type flow channel unit (82), a tertiary H-type flow channel unit (83) and a tertiary H-type flow channel unit (84), wherein the flow channel unit is composed of a primary H-type flow channel unit (81), a secondary H-type flow channel unit (82), a tertiary H-type flow channel unit (83) and a tertiary H-type flow channel unit (84) and upper and lower superimposed flow channels, and the intervals between the superimposed flow channels are equal, that is, S=1.0 mm, and the primary H-type flow channel units (81), the secondary H-type flow channel units (82), the tertiary H-type flow channel units (83) and the tertiary H-type flow channel units (84) of different levels are connected by vertical The connecting flow channel and the central main flow channel are connected to each other, and the main flow field area is composed of a primary H-type flow channel unit (81), a secondary H-type flow channel unit (82), a tertiary H-type flow channel unit (83) and a tertiary H-type flow channel unit (84). The primary H-type flow channel unit (81), the secondary H-type flow channel unit (82), the tertiary H-type flow channel unit (83) and the tertiary H-type flow channel unit (84) are spaced equally in the vertical direction, and the height and width of the primary H-type flow channel unit (81), the secondary H-type flow channel unit (82), the tertiary H-type flow channel unit (83) and the tertiary H-type flow channel unit (84) are increased step by step, respectively satisfying W B1 =1.1 W B2 =1.1 2 ·W B3 =1.1 3 ·W B4 , L H1 =1.1·L H2 =1.1 2 ·L H3 =1.1 3 ·L H .

10. The method for preparing a fuel cell bipolar plate with a bionic H-type flow field according to claims 1-9, characterized in that: The specific steps are: Step 1: When the fuel cell is working, the reaction gas enters from the inlet and passes through the gradient wavy structure at the bottom of the flow channel, changing the gas transmission direction, so that the reaction gas produces a speed perpendicular to the membrane electrode direction, and convection accelerates its transmission to the catalyst layer to participate in the electrochemical reaction. As the amplitude and length of the wavy structure gradually increase, the reaction gas transmission resistance increases, which can generate partial forced convection, and also improve the mass transfer efficiency of the battery; Step 2: The top flow channel, the vertical connecting flow channel and the central main flow channel transmit the reaction gas to the H-type flow channel unit. The length and width of the flow channel decrease in a gradient along the gas transmission direction. The width of the flow channel is changed by the gradient, thereby changing the cross-sectional area of ​​the flow channel to transmit the same flow rate of reaction gas, ensuring that the side flow channel far from the inlet position can also obtain a larger reaction gas flow rate, so that the reaction gas is transmitted in a directional manner while improving the mass transfer efficiency of the flow field. At the same time, the widths of the central main flow channel, the vertical connecting flow channel and the side flow channels are added equal at the same level, so that the reaction gas of the H-type flow channel unit connected thereto enters the entire flow field at an equal flow rate for gas transmission; Step 3: The length and width of the bottom flow channel increase in a gradient along the gas transmission direction, and the width of the bottom flow channel increases as the distance to the outlet decreases, so as to avoid the blockage of the bottom flow channel with too large a mass transfer task near the outlet, so that the reaction gas and product water collected from different H-type flow channel units and side flow channels are discharged in a gradient in time; Step 4: The multi-level H-type flow channel unit performs cyclic mass transfer and drainage through the H-shaped structure flow channels and the upper and lower superimposed flow channels in its different levels. The reaction gas first enters the central main flow channel and the vertical connecting flow channel through the top flow channel, and then is transmitted to the upper superimposed flow channel of the first-level H-type flow channel unit. Due to their symmetrical distribution, they can be uniformly transmitted at the same time, so that the water generated by the reaction is quickly discharged, and then transmitted and distributed through the H-type structure flow channel. When the reaction gas reaches the lower superimposed flow channel, it is directly transmitted to the side flow channel, the vertical connecting flow channel, and the central main flow channel to complete the first transmission reaction in the H-type flow channel unit. Thereafter, multiple transmissions are performed according to the multi-level H-type flow channel units, so that the unreacted gas can be cyclically transmitted and utilized multiple times, so that there is no place in the flow field where the reaction gas has not reached.

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