WO2021213497A1

WO2021213497A1 - Fuel cell metal pole plate having surface microstructure and manufacturing method for fuel cell metal pole plate

Info

Publication number: WO2021213497A1
Application number: PCT/CN2021/089240
Authority: WO
Inventors: 彭林法; 李志鹏; 徐竹田; 邱殿凯; 易培云; 来新民; 石伟玉; 侯中军; 姜天豪
Original assignee: 上海交通大学; 上海汽车集团股份有限公司; 上海治臻新能源装备有限公司
Priority date: 2020-04-24
Filing date: 2021-04-23
Publication date: 2021-10-28
Also published as: CN111446462B; CN111446462A

Abstract

The present invention relates to a fuel cell metal pole plate having a surface microstructure and a manufacturing method for the fuel cell metal pole plate. A surface of the metal pole plate is provided with convex or concave microarray structures in a partitioning manner. Compared with the prior art, the present invention uses a two-stage microstructure, so that an effective contact area with a gas diffusion layer can be increased; and then, a contact resistance between the pole plate and the gas diffusion layer is reduced, an output voltage of a fuel cell is improved, hydrophilicity and hydrophobicity of the surface of the pole plate are adjusted by a secondary structure, water management in the cell is improved, certain humidity required by a proton membrane during working is facilitated to be ensured, and liquid water generated in a flow channel can be discharged in time. The surface of the whole pole plate is divided into different blocks, excessive dryness or excessive moisture accumulation in an electric pile is prevented, the performance and efficiency of the fuel cell can be better improved by means of a block design, and the advantages of a simple and environment-friendly manufacturing process, good corrosion resistance, and the like are achieved.

Description

Fuel cell metal pole plate with surface microstructure and manufacturing method thereof

Technical field

The invention belongs to the technical field of fuel cells, and in particular relates to a fuel cell metal electrode plate with a surface microstructure and a manufacturing method thereof.

Background technique

The proton exchange membrane fuel cell is an environmentally friendly new energy device that converts chemical energy into electrical energy through redox reactions. The reaction product is only water. It has the advantages of high efficiency, environmental protection, and low operating temperature. Fuel cells have begun to be applied in fields such as automobiles, drones, portable mobile power supplies, and fixed power supplies. The electrode plate is one of the key components of the fuel cell. The metal electrode plate is widely used because of its low manufacturing cost and good thermal conductivity and electrical conductivity.

In order to increase the output voltage of the fuel cell, the internal resistance of the cell should be reduced as much as possible, which mainly includes the body resistance of various materials in the cell and the contact resistance between interfaces. For two conductors in plane contact, under ideal circumstances, it is desirable that the contact surface has zero resistance to current conduction. However, in fact, from the point of view of the microstructure, the surface of the conductor is not absolutely flat and smooth, which greatly reduces the contact area of the conductor, and some parts of the contact may not be conductive, which leads to the resistance on the contact interface. The impact cannot be ignored. Even the contact form, contact pressure, surface roughness and other factors between the conductors will affect the contact resistance between the conductors. The gas diffusion layer is usually composed of porous carbon fiber, so it is desirable to be able to treat the surface of the metal electrode plate.

After searching the prior art literature, it was found that the patent of China Patent Authorization Publication No. CN110323456A discloses a method for preparing a bipolar plate with a lower contact resistance. Through sandblasting, the surface morphology of the graphite plate is changed and the morphology of the graphite plate is improved. The surface roughness is improved, and the uneven surface structure is trapped in the gas diffusion layer under the action of the tightening force, which increases the contact area and reduces the contact resistance. The Chinese Patent Authorization Publication No. CN205645995U invented a composite electrode plate with at least one side surface as a rough surface to improve the strength and conductivity of the battery. However, the above method does not take into account the drainage condition of the bipolar plate, which is likely to cause water blocking and reduce the efficiency of the battery.

The fuel cell reacts to produce water. If it accumulates in the flow channel and cannot be discharged in time, it will affect gas transmission and reduce battery efficiency. At the same time, the efficient operation of the membrane electrode requires a certain degree of humidity in the flow channel. Therefore, fuel cell water management needs to meet different constraints. At present, the main technical means of water management are to set up a reasonable flow channel structure and optimize the flow field layout. Searching the prior art literature, the Chinese Patent Authorization Publication No. CN110010922A invented a fuel cell metal bipolar plate with a hydrophobic structure. The micro-protrusion structure is set on the gas by using sheet metal forming, incremental forming or material removal methods. The bottom surface of the groove reduces the surface hydrophilicity of the metal electrode plate; the patent publication number CN109065907A invented a flow field structure containing multiple spaced flow channels and flow channel ridges to solve the problem of membrane electrode humidification and battery The problem of drainage; the patent of publication number CN110242214A invented a pole plate with rough sections in the flow channel to accelerate gas turbulence and break water droplets, and improve the drainage capacity of the flow field. However, in different areas of the flow channel, due to different gas purging effects, water generation and accumulation are different, and it is easier to collect at the end of the flow channel and the gas outlet, while the gas inlet is relatively dry. The results of the plates disclosed in the patents do not take into account the different requirements for water in different areas, which may cause the efficiency of some areas to be negatively affected.

Summary of the invention

The purpose of the present invention is to provide a fuel cell metal electrode plate with a surface microstructure and a manufacturing method thereof in order to overcome the above-mentioned defects in the prior art. The microarray structure is designed in different areas, which can reduce contact resistance and improve water management. Thereby reducing the internal resistance of the fuel cell, improving the internal humidity distribution, and increasing the output voltage and working efficiency of the fuel cell.

The object of the present invention can be achieved by the following technical solutions: a fuel cell metal electrode plate with a surface microstructure, which is characterized in that the surface of the metal electrode plate is partitioned with a protruding or recessed microarray structure.

The surface of the metal electrode plate is divided into three areas: a gas inlet area, a flow channel area and a gas outlet area.

The microarray structure changes gradually along the gas inlet area, the flow channel area, and the gas outlet area, or the aspect ratio of the microarray structure gradually changes.

Further, the height or depth of the protrusions or depressions of the microarray structure is 5-30 μm, the aspect ratio is 0.5-4:1, and the distance between two adjacent protrusions or depressions is 5-50 μm. The microarray structure is a regular shape or irregular protrusions or depressions arranged on the surface of a metal electrode plate, wherein the regular shapes include pyramids, cylinders, cones, filaments, ribbons, balls, or cubes.

One or two of the geometric structure, aspect ratio or arrangement density of the microarray structure can be arbitrarily changed to make the surface of the electrode plate in the gas inlet area hydrophilic, and to ensure the wetting of the membrane electrode, and the electrode plate in the gas outlet area The surface is hydrophobic, which promotes the discharge of generated water and ensures the passage of gas.

It is further preferred that the geometric structure and aspect ratio of the microarray structure are the same, and the arrangement density gradually increases along the gas inlet area, the flow channel area and the gas outlet area. The densely packed array features are beneficial to enhance the surface of the electrode plate. The hydrophobicity of the metal plate near the gas inlet makes the metal electrode plate maintain a certain degree of hydrophilicity to ensure the wetting of the membrane electrode, and at the position near the gas outlet, it promotes the discharge of generated water and ensures the passage of gas.

It is further preferred that the geometric structure and arrangement density of the microarray structure are the same, and the aspect ratio gradually increases along the gas inlet area, the flow channel area and the gas outlet area, so that the surface of the electrode plate in the gas inlet area is hydrophilic. The surface of the electrode plate in the gas outlet area is hydrophobic, so that the metal electrode plate maintains a certain degree of hydrophilicity at the position close to the gas inlet to ensure the wetting of the membrane electrode. At the position near the gas outlet, it promotes the discharge of generated water. , To ensure the passage of gas.

It is further preferred that the arrangement density and aspect ratio of the microarray structure are the same, and the geometric structure is different. Different geometric structures are selected for combination, so that the surface of the electrode plate in the gas inlet area is hydrophilic, and the electrode plate in the gas outlet area is hydrophilic. The surface is hydrophobic.

For the microarray structure, the same characteristic aspect ratio and arrangement density, different geometric models can be selected, or the design methods including but not limited to the above design methods can be used in combination to achieve the purpose of processing the hydrophobicity and hydrophilicity of the surface of the electrode plate in different regions.

Regardless of the above-mentioned arrangement of the microarray structure, it can effectively increase the contact area with the gas diffusion layer, thereby reducing the contact resistance between the metal electrode plate and the gas diffusion layer, and increasing the output voltage of the fuel cell. .

A method for manufacturing a metal electrode plate of a fuel cell with a surface microstructure uses a material surface treatment or a mold surface treatment method to produce a microarray structure on the surface of the metal electrode plate.

Further, the method for surface treatment of the material is a method of rolling, stamping, single-point rapid imprinting, laser, electroforming, screen printing or chemical corrosion, using a dressing, no dressing, or material removal methods. A microarray structure is formed on the surface of the metal material;

The mold surface treatment method is to use imprinting, laser, electroforming or chemical etching to form a mirror microarray structure on the surface of the stamping mold for preparing the electrode plate.

Compared with the prior art, the present invention has the following advantages:

(1) In the present invention, a protruding or recessed microarray structure is provided on the metal surface. Under the action of the assembly force, the microstructure is pressed into the subsurface layer of the gas diffusion layer and contacts with it, which can greatly increase the metal plate and The effective contact area between the gas diffusion layers improves the contact situation and reduces the contact resistance between the two.

(2) The metal electrode plate of the fuel cell with the microarray structure of the present invention increases the effective contact area with the microstructure of the gas diffusion layer through the micron-level structure on the surface of the electrode plate, reduces the contact resistance between the interfaces, and improves the fuel The output voltage of the battery; different microarrays are designed in different areas, which can deal with the water requirements and dry humidity requirements of different areas of the electrode plates, so that the electrode plates have different hydrophilic and hydrophobic properties, which improves the work of the fuel cell. Efficiency and operational stability.

(3) The manufacturing method of the fuel cell metal electrode plate with the microarray structure of the present invention provides two production methods. The surface of the material is pretreated by rolling and other methods. The processing cost is low, the production efficiency is high, and large-scale production can be achieved. Large-scale and large-scale production; the surface of the mold used to prepare the metal plate is processed, and the microarray structure is directly formed on the surface of the metal material through the mold. Scale production.

Description of the drawings

Fig. 1 is a front view of a metal electrode plate of a fuel cell with a microarray structure according to the present invention;

2 is a schematic diagram of the microarray of the distribution area of the metal electrode plate of the fuel cell with the microarray structure of the present invention;

3 is a schematic diagram of the microarray of the flow channel area of the metal electrode plate of the fuel cell with the microarray structure of the present invention;

4 is a schematic view of the contact cross-sectional view of the microarray of the flow channel region of the metal electrode plate of the fuel cell with the microarray structure and the gas diffusion layer of the present invention;

Figure 5 is an enlarged view of part A in Figure 4;

6 is a schematic diagram of the manufacturing method of the surface treatment of the metal electrode plate material of the fuel cell with the microarray structure according to the present invention;

Fig. 7 is an enlarged view of part B in Fig. 6;

8 is a schematic diagram of the structure of a metal electrode plate mold of a fuel cell with a microarray structure according to the present invention;

Fig. 9 is an enlarged view of part C in Fig. 8;

FIG. 10 is a schematic structural diagram of a metal electrode plate placed in the mold shown in FIG. 8 for molding;

Figure 11 is a schematic view of the structure of the metal pole plate after molding.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention.

Example 1

As shown in Figure 1, the cathode and anode of the bipolar plate are divided into a gas inlet area 1, a flow channel area 2, and a gas outlet area 3. For the anode plate, the gas inlet zone 1 is relatively dry. In order to ensure that the membrane electrode can work well, the metal plate should be kept hydrophilic. Therefore, a relatively sparse microarray structure a101 can be used (that is, a cubic shape is set on the surface of the plate. Protrusions, the height of the protrusions is 5-30μm, the aspect ratio is 0.5-4:1, and the distance between two adjacent protrusions at the entrance is 50μm); along the flow path from gas inlet area 1 to gas outlet area 3, in a row The density gradually increases (when reaching the gas outlet, the distance between two adjacent protrusions is 5μm). Because the water generated by the reaction increases the wetness of the entire battery, the density of the array increases accordingly. At this time, the surface of the electrode plate The improved hydrophobicity of the battery is beneficial to avoid excessive humidity in the battery and reduce the operating efficiency of the battery. For the cathode plate, the water generated by the reaction tends to accumulate in the flow channel and affect the gas transmission. Therefore, a microstructure with a larger array density is required (the geometry and aspect ratio of the microarray structure provided on the surface of the cathode plate are the same as those of the anode plate. The density of the distribution is different. From the gas inlet area 1 to the gas outlet area 3, the distance between two adjacent protrusions is gradually reduced from 30μm to 10μm) to improve the hydrophobicity of the entire surface of the cathode plate, promote the discharge of produced water, and regulate the water Management to ensure the stable operation of fuel cells. The microstructures on the surface of the electrode plates on both sides can effectively reduce the contact resistance between the metal electrode plates and the gas diffusion layer, and increase the output voltage of the fuel cell.

Example 2

The geometric shape and arrangement density of the microarray structure on the surface of the anode plate and the cathode plate are the same, the aspect ratio is different, and the geometric structure is a convex cylinder. The height of the cylinder is different from the gas inlet area 1 to the gas outlet area 3. The aspect ratio of the anode plate is gradually increased from 0.5:1 to 4:1. The aspect ratio of the cathode plate is gradually increased from 1:1 to 4:1. The rest is the same as in Example 1.

Example 3

The aspect ratio and arrangement density of the microarray structure on the surface of the anode plate and the cathode plate are the same, but the geometric shapes are different. The shape of the gas inlet area 1 is spherical, the flow channel area 2 is conical, and the gas outlet area 3 is ribbon-shaped. The rest is the same as in Example 1.

Example 4

As shown in FIG. 6, the multi-step rolling 7 processing method is used to perform surface pretreatment of the material for manufacturing the metal electrode plate, and the surface of the pressing roller is provided with a microarray structure, as shown in FIG. 7. The microarray structures with different distribution densities are pressed on the metal surface, and the metal plates are prepared by stamping or hydraulic bulging after the material is cut, and the microarray structures a101 and the microarray structure b201 with different densities can be obtained. Polar plate (as shown in Figures 2 to 3). When the electrode plate 5 with the microarray structure is in contact with the gas exchange layer 4 (as shown in FIGS. 4 to 5), the effective contact area increases, the contact resistance decreases, and the output voltage of the battery increases. The microarray structure b201 allows the flow channel near the gas inlet to retain a certain degree of hydrophilicity, which is beneficial to maintain the humidity of the proton exchange membrane, and near the outlet, the hydrophobicity of the electrode plate is greatly increased, which is beneficial to the rapid discharge of the generated water 6 , To ensure the smoothness of the gas channel, and improve the operating efficiency and stability of the fuel cell.

Example 5

As shown in Figures 8-11, on the surface of the stamping die 8 used to prepare the metal plates, the required microarray structure is formed by imprinting, laser, electroforming or chemical etching, as shown in Figure 9, and then used When the metal electrode plate is produced by stamping with the mold, the microstructure is directly formed on the surface of the metal material through the mold, and then the electrode plate with the microarray structure a101 and the microarray structure b201 of different densities can be obtained. When the electrode plate 5 with the microarray structure is in contact with the gas exchange layer 4, the effective contact area increases, the contact resistance decreases, and the output voltage of the battery increases. The microarray structure b201 allows the flow channel near the gas inlet to retain a certain degree of hydrophilicity, which is beneficial to maintain the humidity of the proton exchange membrane, and near the outlet, the hydrophobicity of the electrode plate is greatly increased, which is beneficial to the rapid discharge of the generated water 6 , To ensure the smoothness of the gas channel, and improve the operating efficiency and stability of the fuel cell.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be combined in form and Various changes are made to the details without departing from the scope defined by the claims of the present invention.

Claims

A fuel cell metal electrode plate with surface microstructures is characterized in that the surface of the metal electrode plate is partitioned with a protruding or recessed microarray structure.
The fuel cell metal electrode plate with surface microstructure according to claim 1, wherein the surface of the metal electrode plate is divided into three areas: a gas inlet area, a flow channel area and a gas outlet area.
The fuel cell metal electrode plate with surface microstructures according to claim 1 or 2, characterized in that the microarray structure along the gas inlet area, the flow channel area and the gas outlet area, the degree of fineness of the array Gradually change or gradually change the aspect ratio of the microarray structure.
A fuel cell metal electrode plate with a surface microstructure according to claim 3, wherein the height or depth of the protrusion or depression of the microarray structure is 5-30 μm, and the aspect ratio is 0.5- 4:1, the distance between two adjacent protrusions or recesses is 5-50μm.
The fuel cell metal electrode plate with surface microstructures according to claim 3, characterized in that the geometric structure and aspect ratio of the microarray structure are the same, along the gas inlet area, flow channel area and In the gas outlet area, the arrangement density gradually increases, so that the surface of the electrode plate in the gas inlet area has hydrophilicity, and the surface of the electrode plate in the gas outlet area has hydrophobicity.
The fuel cell metal electrode plate with surface microstructures according to claim 3, characterized in that the geometric structure and arrangement density of the microarray structure are the same, along the gas inlet area, flow channel area and In the gas outlet area, the aspect ratio gradually increases, making the surface of the electrode plate in the gas inlet area hydrophilic, and the surface of the electrode plate in the gas outlet area has hydrophobicity.
A fuel cell metal electrode plate with a surface microstructure according to claim 3, wherein the arrangement density and aspect ratio of the microarray structure are the same, the geometric structure is different, and different geometric structures are selected. The combination makes the surface of the electrode plate in the gas inlet area hydrophilic, and the surface of the electrode plate in the gas outlet area has hydrophobicity.
A fuel cell metal electrode plate with a surface microstructure according to claim 1, wherein the microarray structure is a regular shape or irregular protrusions or depressions arranged on the surface of the metal electrode plate, wherein Regular shapes include pyramids, cylinders, cones, filaments, ribbons, balls, or cubes.
A method for manufacturing a fuel cell metal electrode plate with a surface microstructure according to claim 1, wherein the microarray structure is manufactured on the surface of the metal electrode plate by material surface treatment or mold surface treatment.
The method for manufacturing a fuel cell metal electrode plate with a surface microstructure according to claim 9, wherein the method of surface treatment of the material is roll pressing, stamping, single-point rapid imprinting, laser, electric Casting, screen printing or chemical corrosion methods, using dressings, no dressings, or material removal methods, to form a microarray structure on the surface of metal materials;

The mold surface treatment method is to use imprinting, laser, electroforming or chemical etching to form a mirror microarray structure on the surface of the stamping mold for preparing the electrode plate.