A fuel cell bipolar plate with a biomimetic h-shaped flow field and method thereof

Abstract

The present application relates to the technical field of fuel cell, and discloses a fuel cell bipolar plate with bionic H-shaped flow field, which comprises a bipolar plate body, the bipolar plate body comprises an inlet, a central main flow channel is engraved in the vertical direction of the inlet, a first top flow channel and a second top flow channel are engraved in the vertical direction connected with the inlet, and a first left side flow channel, a second left side flow channel, a third left side flow channel and a fourth left side flow channel are sequentially arranged on the side surface of the bipolar plate body. The fuel cell bipolar plate with bionic H-shaped flow field and the method thereof change the gas and water transmission mechanism in the flow field through the above mechanism, uniformly distribute the reaction gas in a directional manner, circulate mass transfer and drain water through the multistage flow channel unit structure, reduce the pressure drop and pumping power, improve the mass transfer efficiency, improve the water management of the fuel cell, and finally improve the performance and stability of the fuel cell.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, specifically to a biomimetic H-shaped flow field fuel cell bipolar plate and its method. Background Technology

[0002] With the accelerated pace of industrialization and modernization worldwide, human demand for energy is increasing daily. However, the widespread use of fossil fuels has triggered the dual challenges of energy depletion and environmental degradation. Energy issues are not only crucial to the survival and development of human society but have also become a pressing global problem. Hydrogen energy, possessing the advantages of both traditional and new energy sources (high energy density, green and low-carbon, and widely available), is considered the "ultimate energy" of the future. The utilization of hydrogen energy is mainly achieved through proton exchange membrane fuel cells (PEMFCs). PEMFCs are power generation devices that directly convert the chemical energy stored in hydrogen and oxidant into electrical energy through an electrochemical reaction. They are not limited by the Carnot cycle and have advantages such as simple structure, high energy conversion efficiency, cleanliness, zero carbon emissions, low noise, low operating temperature, and fast start-up response. They are widely regarded as one of the most promising clean and efficient energy technologies for the future, contributing to the optimization of the energy structure and playing a significant role in solving energy problems.

[0003] Bipolar plates are one of the key components of proton exchange membrane fuel cells. Their main functions include collecting and conducting current, separating fuel and oxidant, supporting the membrane electrode assembly, and heat dissipation. In addition, the surface of the plates is designed with a flow field structure, which has another key function of transporting, distributing, and discharging reactants and products inside the cell. The rationality of the flow field design directly affects whether the electrochemical reaction can proceed normally. Different flow fields are composed of gas channels (grooves) of different shapes and structures and ridges that provide support. The flow field structure not only affects the contact resistance between the bipolar plate and the membrane electrode assembly, but also affects the mass transfer and drainage process. In traditional parallel flow fields, the product water tends to accumulate in a certain local area, causing insufficient reactant supply. The long flow channels of serpentine flow fields increase the pressure drop, resulting in pumping power loss. Although interdigitated flow fields improve cell performance, their large pressure drop will cause pumping power loss and shorten cell life. Point flow field reduces gas flow resistance and pumping power loss, but local areas are prone to gas stagnation and flooding. Therefore, we propose a biomimetic H-shaped flow field fuel cell bipolar plate and its method. Summary of the Invention

[0004] To address the shortcomings of existing biomimetic H-shaped flow field fuel cell bipolar plates and methods, this invention provides a biomimetic H-shaped flow field fuel cell bipolar plate and method, which features a multi-stage flow channel unit structure for circulating mass transfer and drainage, reducing pressure drop and pumping power while improving mass transfer efficiency, improving fuel cell water management, and ultimately enhancing fuel cell performance and stability, thus solving the problems mentioned in the background art.

[0005] This invention provides the following technical solution: a biomimetic H-shaped flow field fuel cell bipolar plate, comprising a bipolar plate body, the bipolar plate body including an inlet, a central main channel engraved along the vertical direction of the inlet, a first-stage top channel and a second-stage top channel engraved in the vertical direction connected to the inlet, a first-stage left-side channel, a second-stage left-side channel, a third-stage left-side channel and a fourth-stage left-side channel sequentially opened on the side of the bipolar plate body, a first outlet and a second outlet opened on both sides of the lower part of the bipolar plate body, a first-stage bottom channel and a second-stage bottom channel sequentially opened on both sides of the lower part of the bipolar plate body, a first-stage H-shaped flow channel unit, a second-stage H-shaped flow channel unit, a third-stage H-shaped flow channel unit and a fourth-stage H-shaped flow channel unit sequentially opened inside both sides of the first-stage left-side channel, the second-stage left-side channel, the third-stage left-side channel and the fourth-stage left-side channel, the bipolar plate body is a planar plate, on which the flow channel structure is engraved, and the bottom of the flow channel is a gradient sinusoidal wave structure.

[0006] Preferably, a right-side flow channel is provided on the right side of the battery bipolar plate body, 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.

[0007] Preferably, the central main channel is divided into four levels vertically along the airflow transmission direction, with the channel width of each level decreasing gradually and the length increasing gradually, satisfying M. V1 =1.1·M V2 =1.1 2 ·M V3 =1.1 3 ·M V4 .

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

[0009] Preferably, a vertically connected flow channel is provided at the gradient point of the flow channel at the top of the battery bipolar plate body. The vertically connected flow channel is divided into four levels in the vertical direction of airflow transmission, and the width and length of the flow channel in each level increase in a gradient, such as... Figure 4 The following satisfy N respectively 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-stage, second-stage, third-stage, and fourth-stage left-side flow channels and the right-side flow channels have the same number of stages as the central main flow channel in the vertical direction of airflow transmission, and the width of each stage decreases gradually while the length increases gradually, satisfying P. V1 =1.1·P V2 =1.1 2 ·P V3 =1.1 3 ·P V4 .

[0011] Preferably, the length and width of the primary bottom channel and the secondary bottom channel both increase in a gradient, and the gradient ratio is the same as that of the top channel.

[0012] Preferably, the first and second outlets 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. The top flow channel, the bottom flow channel, and the side flow channels enclose the main region of the bipolar plate flow field.

[0013] Preferably, the flow channel unit consists of 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 fourth-level H-type flow channel unit. The flow channel is formed by stacking these units vertically. Different levels of these units are interconnected via vertically connected flow channels and a central main flow channel. The main flow field region is composed of these four levels of H-type flow channel units. The system consists of four levels of H-type flow channel units. The vertical spacing between the first-level, second-level, third-level, and fourth-level H-type flow channel units is equal, and the width of each level increases progressively. The width of each level refers to the internal flow channel width of the first-level, second-level, third-level, and fourth-level H-type flow channel unit.

[0014] Compared with existing biomimetic H-shaped flow field fuel cell bipolar plates and methods, the present invention has the following advantages: 1. The biomimetic H-shaped flow field fuel cell bipolar plate and its method, through the sinusoidal wave structure at the bottom of the flow channel, the amplitude and length of which decrease in a gradient, the peak and trough structure of the bottom flow channel causes the reactant gas to generate a flow velocity perpendicular to the membrane electrode, which enhances the mass transfer efficiency through convection, and at the same time, the gradually smaller troughs also promote the rapid discharge of electrochemically generated water.

[0015] 2. The biomimetic H-shaped flow field fuel cell bipolar plate and its method involve a gradient decrease, decrease, increase, and increase in the width of each top channel, central main channel, vertical connecting channel, and bottom channel along the gas transport direction. The number of levels in the central main channel is equal to the number of levels in the vertical connecting channel and the left and right side channels. By changing the width of the channels through the gradient, the cross-sectional area of ​​the channels is changed, ensuring that the same flow rate of reactant gas can be transported at any position. This ensures that channels farther from the inlet can also obtain a large flow rate of reactant gas, thereby improving the mass transfer efficiency of the flow field while directional transport of reactant gas and promoting uniform gas distribution in the flow field.

[0016] 3. The biomimetic H-shaped flow field fuel cell bipolar plate and its method, through the equal sum of the widths of the central main channel, vertical connecting channel and side channel of the same level, allows the reactant gas of the H-shaped channel unit connected to it to enter the entire flow field at an equal flow rate for gas transport, promotes uniform gas distribution in the flow field, and thus allows the reactant gas to enter the catalyst layer uniformly and quickly for electrochemical reaction.

[0017] 4. The biomimetic H-shaped flow field fuel cell bipolar plate and its method change the gas and water transport mechanism inside the flow field through the above mechanism, distribute the reactant gas in a directional and uniform manner, and circulate mass transfer and drainage through a multi-stage flow channel unit structure. This reduces pressure drop and pumping power while improving mass transfer efficiency, improving water management of the fuel cell, and ultimately improving the performance and stability of the fuel cell. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the bipolar plate of the fuel cell with the biomimetic H-shaped flow field of the present invention; Figure 2 This is a schematic diagram of the structure of the bottom of the biomimetic flow channel of the present invention, from the side near the inlet to the side near the outlet; Figure 3 This is a schematic diagram of the biomimetic flow channel unit of the present invention; Figure 4 This is a schematic diagram showing the structural arrangement of the distribution channel, collection channel, and multi-stage biomimetic channel unit of the present invention. Figure 5 This is a schematic diagram of the structural arrangement of the bottom of the biomimetic flow channel of the present invention.

[0019] In the diagram: 1. Inlet; 2. Central main channel; 3. Vertical connecting channel; 41. First-stage top channel; 42. Second-stage top channel; 51. First-stage left side channel; 52. Second-stage left side channel; 53. Third-stage left side channel; 54. Fourth-stage left side channel; 61. First outlet; 62. Second outlet; 71. First-stage bottom channel; 72. Second-stage bottom channel; 81. First-stage H-type channel unit; 82. Second-stage H-type channel unit; 83. Third-stage H-type channel unit; 84. Fourth-stage H-type channel unit; 9. Right side channel. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5A biomimetic H-shaped flow field fuel cell bipolar plate and its method are disclosed. The bipolar plate body includes an inlet 1 that facilitates the flow of gas or liquid. A central main flow channel 2 is engraved along the vertical direction of the inlet 1. A primary top flow channel 41 and a secondary top flow channel 42 are engraved vertically connected to the inlet 1. A primary left side flow channel 51, a secondary left side flow channel 52, a tertiary left side flow channel 53, and a quaternary left side flow channel 54 are sequentially formed on the sides of the bipolar plate body. A first outlet 61 and a second outlet 62 are formed on the lower sides of the bipolar plate body, which facilitate the discharge of liquid. The lower part of the main body has a first-stage bottom flow channel 71 and a second-stage bottom flow channel 72 sequentially opened on both sides. The first-stage left side flow channel 51, the second-stage left side flow channel 52, the third-stage left side flow channel 53 and the fourth-stage left side flow channel 54 have a first-stage H-type flow channel unit 81, a second-stage H-type flow channel unit 82, a third-stage H-type flow channel unit 83 and a fourth-stage H-type flow channel unit 84 sequentially opened inside both sides. The battery bipolar plate body is a flat plate with flow channel structures engraved on it. The bottom of the flow channel has a gradient sinusoidal wave structure. The wave crest and trough structure of the bottom flow channel makes the reactant gas generate a flow velocity perpendicular to the membrane electrode, which enhances the convection and mass transfer efficiency. At the same time, the gradually smaller troughs also promote the rapid discharge of electrochemically generated water.

[0022] Please see Figure 1 A right-side flow channel 9 is formed on the right side of the battery bipolar plate body, aligned with the first-stage left-side flow channel 51, the second-stage left-side flow channel 52, the third-stage left-side flow channel 53, and the fourth-stage left-side flow channel 54. The right-side flow channel 9 has the same structure as the first-stage, second-stage, third-stage, and fourth-stage left-side flow channels 51, 52, 53, and 54. Furthermore, the amplitude and length of the first-stage, second-stage, third-stage, and fourth-stage left-side flow channels 51, 52, 53, and 54 decrease gradually 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， By changing the width of the flow channel through gradient, and thus the cross-sectional area of ​​the flow channel, the flow channel can be controlled to transmit the same flow rate of reactant gas at any position. This ensures that each flow channel far from the inlet can also obtain a large flow velocity of reactant gas, thereby improving the mass transfer efficiency of the flow field while directional transmission of reactant gas and promoting uniform gas distribution in the flow field.

[0023] Please see Figure 1The central main channel 2 is divided into four levels vertically along the airflow direction. Each level has a gradually decreasing channel width and a gradually increasing channel length, satisfying M... V1 =1.1·M V2 =1.1 2 ·M V3 =1.1 3 ·M V4 .

[0024] Please see Figure 1 The width and length of each stage of the first-stage top channel 41 and the second-stage top channel 42 decrease in a gradient, respectively satisfying W A1 =1.1·W A2 L H1 =1.1·L H2 .

[0025] Please see Figure 1 A vertically connected flow channel 3 is located at the gradient point of the flow channel at the top of the battery bipolar plate body. This vertically connected flow channel 3 is divided into four levels along the vertical direction of airflow transmission, with the width and length of each level increasing in a gradient. For example... Figure 4 The following satisfy N respectively 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 widths of the central main channel, vertical connecting channels, and side channels of the same level are equal when added together. This allows the reactant gas of the H-type channel unit connected to it to enter the entire flow field at an equal flow rate for gas transport, promoting uniform gas distribution in the flow field, and thus enabling the reactant gas to enter the catalyst layer uniformly and quickly for electrochemical reaction.

[0026] Please see Figure 1 The first-stage left-side flow channel 51, the second-stage left-side flow channel 52, the third-stage left-side flow channel 53, and the fourth-stage left-side flow channel 54, along with the right-side flow channel 9, have the same number of stages as the central main flow channel 2 in the vertical direction of airflow transmission. Furthermore, the width of each stage decreases gradually while the length increases gradually, satisfying P... V1 =1.1·P V2 =1.1 2 ·P V3 =1.1 3 ·P V4 .

[0027] Please see Figure 1 The length and width of the primary bottom channel 71 and the secondary bottom channel 72 both increase in a gradient, and the gradient ratio is the same as that of the top channel. The bottom channel undertakes the dual task of collecting unreacted gas and product water. The width of the bottom channel increases as the distance to the outlet decreases. While maintaining a low pressure drop, it can ensure a large flow velocity near the outlet and avoid blockage of the collection channel with excessive mass transfer near the outlet, so that the reacting gas and water can be discharged in a gradient in a timely manner.

[0028] Please see Figure 1 The first outlet 61 and the second outlet 62 of the bipolar plate flow field are formed at the confluence of the first-stage left-side flow channel 51, the second-stage left-side flow channel 52, the third-stage left-side flow channel 53 and the fourth-stage left-side flow channel 54 with the right-side flow channel 9, the first-stage bottom flow channel 71 and the second-stage bottom flow channel 72. The top flow channel, the bottom flow channel and the side flow channel enclose the main area of ​​the bipolar plate flow field. The gas or liquid being transported can be discharged through the first outlet 61 and the second outlet 62.

[0029] Please see Figure 3 The flow channel unit consists of 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 fourth-level H-type flow channel unit 84. The flow channel is formed by stacking these units vertically. Different levels of these units are interconnected with a central main flow channel via vertical connecting channels. The main flow field region is composed of these four units. The system consists of H-shaped flow channel units 84. The vertical spacing between the first-level H-shaped flow channel unit 81, the second-level H-shaped flow channel unit 82, the third-level H-shaped flow channel unit 83, and the fourth-level H-shaped flow channel unit 84 is equal. The width of the first-level H-shaped flow channel unit 81, the second-level H-shaped flow channel unit 82, the third-level H-shaped flow channel unit 83, and the fourth-level H-shaped flow channel unit 84 increases progressively. The width of the first-level H-shaped flow channel unit 81, the second-level H-shaped flow channel unit 82, the third-level H-shaped flow channel unit 83, and the fourth-level H-shaped flow channel unit 84 refers to the internal flow channel width of the first-level H-shaped flow channel unit 81, the second-level H-shaped flow channel unit 82, the third-level H-shaped flow channel unit 83, and the fourth-level H-shaped flow channel unit 84.

[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A biomimetic H-shaped flow field fuel cell bipolar plate, comprising a battery bipolar plate body, the battery bipolar plate body including an inlet (1), and a central main flow channel (2) engraved along the vertical direction of the inlet (1), characterized in that: The inlet (1) is vertically connected to a first-stage top flow channel (41) and a second-stage top flow channel (42). The side of the battery bipolar plate body is sequentially provided with a first-stage left-side flow channel (51), a second-stage left-side flow channel (52), a third-stage left-side flow channel (53), and a fourth-stage left-side flow channel (54). The lower part of the battery bipolar plate body has a first outlet (61) and a second outlet (62) on both sides. The lower part of the battery bipolar plate body also has a first-stage bottom flow channel (71) and a second-stage bottom flow channel (72) on both sides. The interior of the first-stage left-side flow channel (51), the second-stage left-side flow channel (52), the third-stage left-side flow channel (53), and the fourth-stage left-side flow channel (54) is arranged according to… The battery bipolar plate body is 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 fourth-level H-type flow channel unit (84). The bipolar plate body is a flat plate with flow channel structure engraved on it. The bottom of the flow channel is a gradient sinusoidal wave structure. The 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). The central main channel (2) is divided into four levels in the vertical direction of airflow transmission. The channel width of each level decreases gradually while the length increases gradually. The channel widths are M respectively. V1 M V2 M V3 M V4 The flow channel lengths are H L1 H L2 H L3 H L4 Satisfying M V1 =1.1·M V2 =1.1 2 ·M V3 =1.1 3 ·M V4 ; The width and length of each stage of the primary top channel (41) and the secondary top channel (42) decrease in a gradient manner. The width of each stage of the primary top channel (41) and the secondary top channel (42) are W respectively. A1 and W A2 The lengths are L H1 and L H2 Satisfying W A1 =1.1·W A2 L H1 =1.1·L H2 ; A vertically connected flow channel (3) is provided at the gradient point of the flow channel at the top of the battery bipolar plate body. The vertically connected flow channel (3) is divided into four levels in the vertical direction of airflow transmission. The width and length of the flow channel in each level increase in a gradient. The width of the flow channel in each level is N. V1 N V2 N V3 N V4 The flow channel length for each level is K. L1 K L2 K L3 K L4 Each satisfies 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 first-stage left-side channel (51), the second-stage left-side channel (52), the third-stage left-side channel (53), and the fourth-stage left-side channel (54) have the same number of stages as the right-side channel (9) in the vertical direction of airflow transmission as the central main channel (2), and the width of each stage decreases gradually while the length increases gradually. The width of each stage is P. V1 P V2 P V3 P V4 The length of each level is J. L1 J L2 J L3 J L4 Satisfying P V1 =1.1·P V2 =1.1 2 ·P V3 =1.1 3 ·P V4 ; Furthermore, the widths of the first-level H-type flow channel unit (81), the second-level H-type flow channel unit (82), the third-level H-type flow channel unit (83), and the fourth-level H-type flow channel unit (84) increase progressively. The widths of the first-level H-type flow channel unit (81), the second-level H-type flow channel unit (82), the third-level H-type flow channel unit (83), and the fourth-level H-type flow channel unit (84) refer to the internal flow channel widths of the first-level H-type flow channel unit (81), the second-level H-type flow channel unit (82), the third-level H-type flow channel unit (83), and the fourth-level H-type flow channel unit (84).

2. The biomimetic H-shaped flow field fuel cell bipolar plate according to claim 1, characterized in that: The length and width of the primary bottom channel (71) and the secondary bottom channel (72) both increase in a gradient, and the gradient ratio is the same as that of the top channel.

3. The biomimetic H-shaped flow field fuel cell bipolar plate 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) converge with the right-side flow channel (9), the first-level bottom flow channel (71) and the second-level 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 channel enclose the main area of ​​the bipolar plate flow field.

4. The biomimetic H-shaped flow field fuel cell bipolar plate according to claim 1, characterized in that: The flow channel unit consists 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 quaternary H-type flow channel unit (84). The flow channel is formed by stacking the primary H-type flow channel unit (81), secondary H-type flow channel unit (82), tertiary H-type flow channel unit (83), and quaternary H-type flow channel unit (84) on top of each other. Different levels of primary H-type flow channel units (81), secondary H-type flow channel units (82), tertiary H-type flow channel units (83), and quaternary H-type flow channel units (84) are combined to form the flow channel. The first-level H-type flow channel unit (83) and the fourth-level H-type flow channel unit (84) are interconnected with the central main flow channel through vertical connecting channels. The main flow field region is composed of the first-level H-type flow channel unit (81), the second-level H-type flow channel unit (82), the third-level H-type flow channel unit (83) and the fourth-level H-type flow channel unit (84). The intervals between the first-level H-type flow channel unit (81), the second-level H-type flow channel unit (82), the third-level H-type flow channel unit (83) and the fourth-level H-type flow channel unit (84) in the vertical direction are equal.

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