TWI726693B - Process for making carbon fiber composite collector plates applied on fuel cells - Google Patents

Abstract

The present invention relates to a process for making carbon fiber composite collector plates applied in fuel cells, comprising the steps of preparing a plurality of carbon fiber composite prepregs by coating of a resin including a conductive material on a carbon fiber cloth, laminating the plural prepregs inside a mold, thermally compressing the plural prepregs laminated in the mold to form a carbon fiber composite substrate after the resin of the plural prepregs become solidated, and at last cutting the carbon fiver composite substrate into geometric shapes for final collector plates. In this way, the collector plates of the present invention have characteristics of light weight, high conductivity, good corrosion resistance, high mechanical strength, good heat stability and so on. As using such collector plates in a proton exchange membrane fuel cell (PEMFC), the PEMFC is able to operate in a more efficient and stable manner.

Description

Manufacturing method of carbon fiber composite current collector plate applied to fuel cell

The present invention relates to a method for manufacturing a carbon fiber composite collector plate applied to a fuel cell, especially a method of light weight, high conductivity, good corrosion resistance, high mechanical strength and good thermal stability, and can be applied to proton exchange Membrane fuel cell is a method for manufacturing carbon fiber composite collector plates to effectively improve the operating efficiency and stability of proton exchange membrane fuel cells.

According to the key, the portable fuel cell can continuously generate electricity by replenishing fuel and make it into a charging device, which can be used to charge portable electronic products such as notebook computers and mobile phones. The principle of the fuel cell is to use the energy stored in the fuel and convert it into electric energy by electrochemistry. It has the advantages of high conversion efficiency, cleanliness, low noise and simple structure. It is different from the secondary battery which requires charging and energy storage. The active material is stored in fuel, and only needs to be constantly replenished to maintain the electrochemical reaction, that is, sustainable power generation, so it has a very high potential for development.

The traditional fuel cell system mainly uses metal materials such as stainless steel as the collector plate, and the anti-corrosion layer is plated on the surface of the collector plate by electroplating. The collector plate of this metal material has anti-corrosion treatment on the surface, but it operates for a long time. Corrosion still occurs, and the anti-corrosion layer material is mostly precious metals such as gold, so the production cost is expensive. Furthermore, the electrochemical reaction system during the operation of the fuel cell is an exothermic reaction, and the internal temperature It will increase, and long-term operation and stopping will repeatedly produce thermal expansion and contraction effects, which will reduce the adhesion between the metal collector plate and the proton exchange membrane, and increase the contact resistance, resulting in a decrease in fuel cell performance.

Therefore, some companies use graphite material as the current collector plate. The current collector plate made of graphite material has high conductivity, high chemical stability and good corrosion resistance, so it can solve the problem of current collector made of metal materials. The plate is prone to corrosion; however, the current collector plate made of graphite material is heavier, and has high brittleness, toughness and ductility and other mechanical strengths are insufficient, and it is very easy to crack. In addition, the current collector plate of graphite material has high permeability. When in use, it is prone to problems such as hydrogen leakage.

The reason is that, in view of the current collector plates made of metal materials and graphite materials, the inventors still have the above-mentioned shortcomings in the use and implementation. They are assisted by their years of manufacturing and design experience and knowledge in related fields. Ingenious, researched and created the present invention.

The present invention relates to a method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell. Its main purpose is to provide a light weight, high electrical conductivity, good corrosion resistance, high mechanical strength and good thermal stability. Used in proton exchange membrane fuel cells to effectively improve the operating efficiency and stability of the proton exchange membrane fuel cell. A manufacturing method of carbon fiber composite collector plates.

In order to achieve the above-mentioned implementation objectives, the inventors have developed the following method for manufacturing carbon fiber composite current collector plates applied to fuel cells, which is mainly to coat at least one carbon fiber cloth with a resin and add conductive materials to the resin. In order to make a carbon fiber composite prepreg, the composition of the carbon fiber composite prepreg includes a weight percentage of 30-50wt.% carbon fiber cloth, a weight percentage of 45-68wt.% resin and a weight percentage of 2~5wt. % Conductive material, and then stack several pieces of carbon fiber composite prepreg in a mold and perform hot pressing, so that the resin in the several pieces of carbon fiber composite prepreg is cured to form a carbon fiber composite substrate, and then the The carbon fiber composite base material is subjected to geometric shape cutting processing to complete the production of a carbon fiber composite current collector plate.

The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell as described above, wherein the carbon fiber composite substrate is carbonized before the geometric shape cutting processing is performed, so that the carbon fiber composite substrate is The resin burns and carbonizes at high temperatures.

The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell as described above, wherein the carbonization temperature of the resin of the carbon fiber composite substrate is 600 to 900°C.

The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell as described above, wherein the conductive material is carbon nanotube or graphene powder.

The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell as described above, wherein the carbon fiber cloth is a carbon fiber plain weave cloth, a carbon fiber unidirectional reinforcing cloth, a carbon fiber spread gauze cloth or a pitch carbon fiber cloth.

The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell as described above, wherein the resin is epoxy resin or phenolic resin.

The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell as described above, wherein the carbon fiber composite current collector plate is formed with a number of circular holes arranged in an array on its surface.

As a result, the carbon fiber composite current collector plate of the present invention has the characteristics of lightness, thinness, high conductivity, good corrosion resistance, and high mechanical strength, which can reduce the weight and volume of the current collector plate, and improve the toughness of the current collector plate. , Ductility, so that the collector plate is not easy to be broken, and when assembled in a proton exchange membrane fuel cell, it can effectively improve the performance and stability of the proton exchange membrane fuel cell operation, and use the conductivity added in the resin The non-conductive resin is carbonized to form a conductive channel design between the two carbon fiber cloths with the conductive material, which can greatly improve the conductivity of the current collector plate, and achieve the effect of further increasing the power generation of the fuel cell.

1: Carbon fiber cloth

2: resin

3: conductive material

31: Conductive channel

4: Carbon fiber composite base material

5: Carbon fiber composite collector plate

51: round hole

Figure 1: Flow chart of the present invention

Figure 2: Cross-sectional view of the present invention

Figure 3: Partial enlarged cross-sectional view of the present invention

Figure 4: Front view of the collector plate of the present invention

Figure 5: The state diagram of the measurement point planning of the surface resistance measurement of the present invention

Figure 6: Comparison of the efficiency of the carbon fiber composite collector plate and the graphite collector plate of the present invention

Figure 7: Comparison of the efficiency of the carbon fiber composite collector plate and the stainless steel collector plate of the present invention

In order to enable the technical means of the present invention and the effects it can achieve to have a more complete and clear disclosure, the detailed description is as follows, please refer to the disclosure diagrams and figure numbers: first, please refer to the first to second As shown in the figure, it is the manufacturing method of the carbon fiber composite current collector plate applied to the fuel cell of the present invention. The implementation steps include: A. Coating resin: Firstly, the release paper is placed and fixed on a flat table top, and then at least A cut carbon fiber cloth (1) is placed on the release paper to be fixed. The carbon fiber cloth (1) can be a low-density carbon woven cloth such as carbon fiber plain cloth, carbon fiber unidirectional reinforcing cloth, and carbon fiber spread gauze cloth, or High-density pitch carbon fiber cloth, the low-density carbon woven cloth made of prepreg has lower hardness, and the high-density pitch carbon fiber prepreg has higher hardness, and then the liquid resin (2) is coated with a doctor blade Deployed on the carbon fiber cloth (1), the resin (2) can be a thermosetting resin such as epoxy resin or phenolic resin, and the resin (2) is added with carbon nanotubes or graphene powder with high conductivity Conductive material (3), and volatile acetone or methyl ethyl ketone solvent can be added to the resin (2) to reduce the viscosity of the resin (2), so that the liquid resin (2) can be coated smoothly On the carbon fiber cloth (1), after the coating is completed, the carbon fiber cloth (1) is allowed to stand to dry. After the acetone solvent evaporates, the production of a carbon fiber composite prepreg (Prepreg) can be completed. The carbon fiber composite The composition of the prepreg material contains 30-50wt.% carbon fiber cloth (1), 45-68wt.% resin (2) and 2-5wt.% conductive material (3); B. Cutting: Cut a carbon fiber composite prepreg into several pieces of carbon fiber composite prepreg of predetermined size; C. Stacking: Then use a mold to cut the carbon fiber composite prepreg of predetermined size Fixed, according to the thickness requirements of the current collector plate, you can choose to place a piece of carbon fiber composite prepreg in the mold, or stack several pieces of carbon fiber composite prepreg in the mold corresponding to the required thickness; D. Hot pressing: Then put the carbon fiber composite prepreg fixed in the mold into the upper and lower hot pressing plates of a hot press, and apply ^{a pressure of about 150 kg/per square centimeter [kg/cm 2} ] and heat it to About 150℃ to make the resin (2) harden. After reaching the hot pressing temperature, it is maintained for a period of time. After the resin (2) is completely cured, the heating can be stopped. After the temperature drop is completed, the pressure is released and the hot press is turned on To complete the production of a carbon fiber composite base material (4); E. Carbonization: put the carbon fiber composite base material (4) in a high-temperature furnace, and heat the high-temperature furnace To 600~900℃, the non-conductive resin (2) in the carbon fiber composite base material (4) is burned and carbonized at high temperature, and forms a conductive channel with the conductive material (3) to improve conductivity. The resin ( 2) It is non-conductive, so the conductivity of the carbon fiber composite substrate (4) is directional. The horizontal conductivity is good but the vertical conductivity is poor. Therefore, please also refer to the third figure as shown in the two phases. Stacking The conductive material (21) added between the carbon fiber cloth (1) can be used as a conductive channel (31) between the two carbon fiber cloths (1), so as to improve the vertical conductivity of the carbon fiber composite substrate (4), thereby improving the overall Conductive effect; F. Cutting: Then place the carbon fiber composite substrate (4) on a CNC engraving and milling machine or a milling machine and other computer numerically controlled machine tools for cutting and drilling geometric shapes. Please also refer to the fourth As shown in the figure, a carbon fiber composite current collector plate (5) with an array of circular holes (51) formed on the surface is completed.

Accordingly, when the carbon fiber composite current collector plate (5) is manufactured, it can be assembled in a proton exchange membrane fuel cell for use, and the carbon fiber composite current collector plate (5) is light in weight, high in conductivity, and The characteristics of good corrosion resistance, high mechanical strength and good thermal stability can effectively improve the operating efficiency and stability of the proton exchange membrane fuel cell.

In addition, in the present invention, after the carbon fiber composite substrate (4) is manufactured, the physical density and mechanical properties such as stretching and three-point bending will be measured. The physical density is measured using a densitometer, and the stretching The experiment is carried out using a universal material testing machine in accordance with ASTM-D3039-D3039M-14 to measure the tensile strength of the carbon fiber composite substrate (4) [Tensile Strength, MPa], tensile modulus of elasticity [Tensile modulus of Elasticity, GPa], Poisson’s Ratio, etc., and the three-point bending test is carried out using a universal material testing machine in accordance with ASTM D7264/D7264M-07 specifications to measure the flexural strength of the carbon fiber composite substrate (4) [Flexible Strength, MPa] and Flexural Modulus [Flexural Modulus, GPa] and other properties.

And when the carbon fiber composite base material (4) is finished, conductivity test will be conducted to judge its conductivity, and then feedback to the improvement of process control parameters, the present invention uses four-point probe surface resistance measurement Please also refer to the figure shown in the fifth figure. A carbon fiber composite base material (4) has several measuring points planned for each area for surface resistance measurement. The present invention is based on a carbon fiber composite base material ( 4) There are 9 measuring points in the above plan, so as to know the conductivity and uniformity of the carbon fiber composite substrate (4).

Please refer to Table 1. In the surface resistance measurement, the carbon fiber composite base material (4) is compared without carbonization and different carbonization times. The measurement results show that the carbon fiber composite base material that has been carbonized once The surface resistance value of material (4) is significantly reduced. The surface resistance value of the second carbonization is significantly lower than that of the first carbonization, and the surface resistance value of the third carbonization is not significantly lower than that of the second carbonization. The reason is that the After the second carbonization, the resin (2) has already been carbonized to a considerable degree, and the second carbonization has no obvious benefit, and The carbon fiber composite substrate (4) with a lower surface resistance value will have better conductivity after being cut and processed into a carbon fiber composite collector plate (5). In addition, when the carbon fiber composite substrate (4) is completed, the scanning electron microscope (SEM) will be used for measurement, and the surface of the carbon fiber composite substrate (4) will be scanned with a focused electron beam to generate a surface image. Combining the results of the surface resistance measurement, the effect of the surface type on the surface resistance can be known to facilitate adjustment and improvement after judging the advantages and disadvantages of the material formulation, process parameters, and surface treatment.

Furthermore, after the physical density, mechanical quality test, conductivity test and electron microscope surface measurement are completed, the carbon fiber composite substrate (4) can be cut and processed into a carbon fiber composite collector plate (5), and then Carry out corrosion resistance test. The corrosion resistance test process is to place a carbon fiber composite collector plate (5) into the acidic environment generated by the reaction of a proton exchange membrane fuel cell (PEMFC), and then use a potentiostat Carry out Tafel (Tafel) polarization curve and cyclic voltammetry for corrosion resistance measurement. After the corrosion resistance test is completed, the carbon fiber composite current collector plate (5) of the present invention is assembled in a proton exchange membrane fuel cell jig for characteristic measurement, including polarization curve and electrochemical spectrum analysis measurement. , Stability test with long-term proton exchange membrane fuel cell (PEMFC) operation.

Please also refer to the sixth figure. In the present invention, the carbon fiber composite current collector plate (5) is assembled in the proton exchange membrane fuel cell fixture, and the performance is compared with the current collector plate made of graphite material. This experiment The fuel is controlled to 300sccm (standard ml/min) for the anode hydrogen and 600sccm oxygen for the cathode, and the cathode and anode gases are humidified and heated to 50°C for testing. The experimental results in the sixth figure show that the present invention is The performance of the carbon fiber composite collector plate (5) is significantly improved after being carbonized twice, and its performance is equivalent to that of the graphite collector plate after being carbonized three times. Please also refer to the seventh figure. After the carbon fiber composite collector plate (5) of the present invention is assembled in the proton exchange membrane fuel cell fixture, the performance is compared with the collector plate made of stainless steel. This experiment Similarly, the fuel is controlled to 300sccm hydrogen at the anode and 600sccm oxygen at the cathode. The anode and cathode gases are both humidified and heated to 50°C for testing. The experimental results in the seventh figure show that the carbon fiber composite current collector of the present invention The efficiency of the plate (5) is better than that of the stainless steel collector plate. It can be verified that when the carbon fiber composite collector plate (5) of the present invention is applied to a proton exchange membrane fuel cell, it can effectively achieve the benefits of improving the operating efficiency and stability of the proton exchange membrane fuel cell.

The foregoing embodiments or drawings do not limit the implementation of the manufacturing method of the carbon fiber composite current collector plate applied to the fuel cell of the present invention. Any appropriate change or modification made by a person with ordinary knowledge in the technical field should be regarded as Does not depart from the scope of the patent of the present invention.

It can be seen from the above structure and implementation that the present invention has the following advantages:

1. The manufacturing method of the carbon fiber composite current collector plate applied to the fuel cell of the present invention is to use carbon fiber to make the current collector plate. The light and thin carbon fiber, high conductivity, good corrosion resistance, and high mechanical strength are used to reduce the current collection. The weight and volume of the plate are reduced, and the toughness and ductility of the collector plate are greatly improved, so that the collector plate is not easy to be broken, and it is beneficial to increase the power generation of the fuel cell.

2. The manufacturing method of the carbon fiber composite current collector plate applied to the fuel cell of the present invention is based on the conductive material added to the resin, and the non-conductive resin is carbonized to form a two-phase stacked carbon fiber cloth with the conductive material A conductive channel is formed between them to further improve the conductivity of the carbon fiber composite collector plate.

In summary, the embodiments of the present invention can indeed achieve the expected effects, and the specific structure disclosed by it has not been seen in similar products, nor has it been disclosed before the application. It is in full compliance with the provisions of the Patent Law and Requirement, Yan filed an application for a patent for invention in accordance with the law, and pleaded for favor of review and granting a patent, which would be more virtuous.

Claims (7)

A method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell is mainly to coat at least one carbon fiber cloth with resin, and add conductive material to the resin to make a carbon fiber composite prepreg. The composition of the carbon fiber composite prepreg material contains 30-50wt.% carbon fiber cloth, 45-68wt.% resin and 2-5wt.% conductive material, and then several pieces of carbon fiber composite The prepreg is stacked in a mold and hot-pressed to solidify the resin in several carbon fiber composite prepregs to form a carbon fiber composite substrate, and then the carbon fiber composite substrate is subjected to geometric shape cutting processing to Complete the production of a carbon fiber composite collector plate. The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell according to claim 1, wherein the carbon fiber composite base material is subjected to a carbonization treatment before geometrical shape cutting processing is performed, so that the carbon fiber composite material The resin in the substrate is burned and carbonized at high temperatures. The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell according to claim 2, wherein the carbonization temperature of the resin of the carbon fiber composite substrate is 600 to 900°C. The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell according to claim 1, wherein the conductive material is carbon nanotube or graphene powder. The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell according to claim 1, wherein the carbon fiber cloth is a carbon fiber plain cloth, a carbon fiber unidirectional reinforcing cloth, a carbon fiber spread gauze cloth or a pitch carbon fiber cloth. The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell according to claim 1, wherein the resin is epoxy resin or phenolic resin. The method for manufacturing a carbon fiber composite current collector plate applied to a fuel cell according to claim 1, wherein the carbon fiber composite current collector plate is formed with a number of circular holes arranged in an array on its surface.

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