A process for making a fuel cell membrane electrode

Abstract

The application relates to a manufacturing process of a fuel cell membrane electrode, which comprises the following steps: S1, cutting a proton exchange membrane roll into a sheet and placing the sheet in a constant-temperature and constant-humidity cabinet for 2-20 hours; S2, taking out the proton exchange membrane sheet, loading catalyst on one side of the sheet through ultrasonic spraying or doctor blade coating; S3, then drying by using a vacuum adsorption flat plate oven; S4, placing the obtained proton exchange membrane sheet with catalyst loaded on one side in the constant-temperature and constant-humidity cabinet again for 2-20 hours; S5, taking out the sheet and loading catalyst on the other side of the proton exchange membrane through ultrasonic spraying or doctor blade coating; and S6, then drying by using a vacuum adsorption flat plate oven. Compared with the prior art, the application can prevent swelling caused by absorbing a large amount of water in catalyst slurry during the manufacturing process of the membrane electrode, the operation is simple, and the obtained membrane electrode has stable performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fuel cell technology, in particular to a manufacturing process of a fuel cell membrane electrode. BACKGROUND

[0002] Fuel cell is an energy conversion device that can convert chemical energy stored in fuel and oxidant into electrical energy through electrochemical reaction, which has the advantages of environmental friendliness, high energy density, fast start-up at room temperature and high reliability. Fuel cells include proton exchange membrane fuel cell (PEMFC), alkaline fuel cell (AFC), molten carbonate fuel cell (MCFC), phosphoric acid fuel cell (PAFC) and solid oxide fuel cell (SOFC) etc. Compared with other types of fuel cells, proton exchange membrane fuel cell has relatively low working temperature, which is suitable for use as electric vehicle and portable power source. Membrane electrode is the core component of proton exchange membrane fuel cell, which determines the performance, life and cost of proton exchange membrane fuel cell. Membrane electrode includes catalyst layer, diffusion layer and proton exchange membrane, which provides continuous channels for protons, electrons, reaction gas and water for electrochemical reaction of proton exchange membrane fuel cell.

[0003] A conventional manufacturing process of membrane electrode is to directly spray the catalyst slurry prepared by dispersion with ultrasonic wave on the proton exchange membrane. After spraying the positive electrode, the negative electrode is sprayed. Another manufacturing process is to coat the catalyst slurry prepared by dispersion on the sheet of proton exchange membrane with a doctor blade. After coating the positive electrode, the negative electrode is coated on the other side after drying. The disadvantages of the two technical solutions are that the catalyst slurry contains a large amount of water. After the proton exchange membrane roll is cut into a sheet, the sheet is directly used for ultrasonic wave spraying or doctor blade coating. Under certain temperature conditions, such as 80-120℃ and normal indoor humidity (50% relative humidity), the membrane electrode (CCM) will swell and deform due to the effect of water in the catalyst slurry after ultrasonic wave spraying or doctor blade coating and drying. If the next step of frame bonding of the membrane electrode is performed, great troubles and troubles will be caused.

[0004] Patent application CN201911001264.8 discloses a kind of preparation methods of membrane electrode, comprising the following operations: coating first active material catalyst slurry on one side of proton exchange membrane, drying, to obtain first active material catalyst layer;Proton exchange membrane is adsorbed to vacuum platform on the side of which first active material catalyst layer is coated, and there is also porous membrane between proton exchange membrane and vacuum platform;Coating second active material catalyst slurry on the opposite side of proton exchange membrane, drying, to obtain second active material catalyst layer;Frame is pasted around first active material catalyst layer and second active material catalyst layer, and carbon paper is covered on the surface of first active material catalyst layer and second active material catalyst layer.The method mainly utilizes the pressure difference formed by vacuum acting on both sides of proton exchange membrane, when coating second active material catalyst slurry, the wrinkles generated by swelling of proton exchange membrane can be pressed tightly on porous membrane by atmospheric pressure, and proton exchange membrane will not bulge, so that the smoothness of the coated surface during the process is ensured, the swelling problem of proton exchange membrane caused by contact with solvent during coating is solved, the obtained membrane electrode has smooth surface, high uniformity and excellent electrochemical performance.The patent technology mainly uses vacuum adsorption to avoid the swelling and wrinkling of proton exchange membrane, but the method is complex to operate, and the control requirement of vacuum degree is relatively high.Different proton exchange membranes use different vacuum degrees, and proton exchange membrane is easily broken due to uneven stress. SUMMARY

[0005] The purpose of the present application is to overcome the defects of the prior art and provide a fuel cell membrane electrode manufacturing process that is simple to operate and efficient, and can better prevent the swelling caused by the large amount of water contained in the catalyst slurry absorbed by the membrane electrode.

[0006] The purpose of the present application can be achieved by the following technical solution: a fuel cell membrane electrode manufacturing process, characterized by comprising the following steps:

[0007] S1, cut the proton exchange membrane roll into a sheet and place it in a constant temperature and humidity cabinet for 2-20 hours;

[0008] S2, take out the proton exchange membrane sheet and load catalyst on one side by ultrasonic spraying or doctor blade coating;

[0009] S3, then use a vacuum adsorption flat plate oven to dry;

[0010] S4, place the proton exchange membrane sheet with catalyst loaded on one side again in a constant temperature and humidity cabinet for 2-20 hours;

[0011] S5, take out and load catalyst on the other side of the proton exchange membrane by ultrasonic spraying or doctor blade coating;

[0012] S6, then using vacuum adsorption oven flat drying.

[0013] The temperature and humidity of the constant temperature and humidity cabinet are consistent with the temperature and humidity of the membrane electrode ultrasonic spraying or doctor blade coating under the temperature and humidity operating conditions.

[0014] The temperature of the constant temperature and humidity cabinet is 60-100 DEG C, and the humidity is 80%-100% relative humidity.

[0015] The ultrasonic spraying is to place the proton exchange membrane in an ultrasonic precision spraying machine, the ultrasonic wave is 40 KHZ, the spraying amount of the spraying device is controlled to be 2-20 ml / min per second, and the gas pressure of the spraying nozzle is 2 KPa.

[0016] The coating speed of the doctor blade coating is (1-6) m / min.

[0017] The vacuum adsorption flat oven is connected with a vacuum pumping device, and when drying operation is carried out, the vacuum degree is 30-60 mmHg, and the temperature is 110-120 DEG C.

[0018] The catalyst is a commercially available Pt / C catalyst.

[0019] When the spraying process is used, the commercially available Pt / C catalyst is dispersed in ethanol to configure a suspension with a solid content of 2-10%.

[0020] When the doctor blade coating process is used, the commercially available Pt / C catalyst is dispersed in ethanol to configure a slurry with a solid content of 2-10%.

[0021] After the catalyst is loaded on both sides of the proton exchange membrane, one carbon paper is pasted on each side surface, then the frame is pasted and frame pressing operation is carried out, and a three-in-one electrode is obtained.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] The proton exchange membrane sheet is cut from the roll into a sheet, and then placed in a constant temperature and humidity cabinet. The temperature and humidity of the constant temperature and humidity cabinet are consistent with the temperature and humidity of the operating conditions of the membrane electrode ultrasonic spraying or doctor blade coating. For example, the temperature of the constant temperature and humidity cabinet is adjusted to 80℃, and the humidity is 80%-100% relative humidity. The proton exchange membrane sheet is stored under such conditions for 2-20 hours, so that the water content in the proton exchange membrane sheet reaches a sufficient (1-10%) water content, and the temperature reaches 80℃. The proton exchange membrane sheet can be taken out for ultrasonic spraying or doctor blade coating. The catalyst is not easy to swell on the surface of the proton exchange membrane under such temperature and humidity conditions. Then, the proton exchange membrane sheet is slowly dried in a vacuum adsorption flat plate oven, so that the membrane electrode (CCM) is not easy to distort and deform. When the other side (the reverse side) is sprayed or coated, the proton exchange membrane sheet can also be placed in the constant temperature and humidity cabinet for 2-20 hours, and then taken out for ultrasonic spraying or doctor blade coating. After the spraying or coating is completed, the proton exchange membrane sheet is placed in the vacuum adsorption flat plate oven for drying. The membrane electrode (CCM) produced in this way is relatively flat and will not distort and deform. Then, the membrane electrode (CCM) is processed by attaching a frame. During the pressing process of the frame, a carbon paper is placed on the surface of the sprayed or coated catalyst on the front side and the back side, and the frame is pressed. During the entire operation process, the membrane electrode will not deform, and the process defects of the previous membrane electrode (CCM) that are prone to deformation are overcome. DETAILED DESCRIPTION

[0024] In order to make the technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below in combination with specific examples. Obviously, the described examples are only part of the examples of the present application, rather than all the examples. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] The equipment used in the present application is commonly used in the art, for example, the ultrasonic precision spraying machine can be a commercially available UC340 nanometer thin film precision spraying machine.

[0026] Example 1

[0027] A fuel cell membrane electrode manufacturing process, comprising the following steps:

[0028] S1, cutting the proton exchange membrane roll into a sheet, and placing it in a constant temperature and humidity cabinet for 12 hours; the temperature and humidity of the constant temperature and humidity cabinet are consistent with the temperature and humidity of the operating conditions of the membrane electrode ultrasonic spraying; in this embodiment, the temperature is 80℃, and the humidity is 80% relative humidity;

[0029] S2, take out the proton exchange membrane sheet, load catalyst on one side thereof by ultrasonic spraying; the catalyst is a commercially available Pt / C catalyst, which is dispersed in ethanol to prepare a suspension with a solid content of 5% before spraying; the spraying is performed in an ultrasonic precision spraying machine with a spraying flow rate of 2 ml / min.

[0030] S3, then dry in a vacuum adsorption flat plate oven; the flat plate is connected to a vacuum device, and the vacuum degree is 50 mmHg and the temperature is 120°C during the drying operation.

[0031] S4, place the obtained proton exchange membrane sheet loaded with catalyst on one side in a constant temperature and humidity cabinet for 2 h again;

[0032] S5, take out and load catalyst on the other side of the proton exchange membrane by ultrasonic spraying (the process steps and parameters are the same as those in S2);

[0033] S6, then dry in a vacuum adsorption flat plate oven (the process steps and parameters are the same as those in S3).

[0034] S7, after loading catalyst on both sides of the proton exchange membrane, pad one carbon paper on each side, then fit the frame, and perform the frame pressing operation to obtain a three-in-one electrode.

[0035] Example 2

[0036] A manufacturing process of a fuel cell membrane electrode, comprising the following steps:

[0037] S1, cut the proton exchange membrane roll into a sheet, and place it in a constant temperature and humidity cabinet for 12 h; the temperature and humidity of the constant temperature and humidity cabinet are consistent with the temperature and humidity of the membrane electrode doctor blade coating operation; in this embodiment, the temperature is 80°C and the humidity is 80% relative humidity;

[0038] S2, take out the proton exchange membrane sheet, and load catalyst on one side thereof by doctor blade coating; the catalyst is a commercially available Pt / C catalyst, which is dispersed in ethanol to prepare a slurry with a solid content of 7% before coating; the coating speed of the doctor blade coating is 3 m / min.

[0039] S3, then dry in a vacuum adsorption flat plate oven; the oven is connected to a vacuum device, and the vacuum degree is 40 mmHg and the temperature is 120°C during the drying operation.

[0040] S4, place the obtained proton exchange membrane sheet loaded with catalyst on one side in a constant temperature and humidity cabinet for 12 h again;

[0041] S5, take out and load catalyst on the other side of the proton exchange membrane by doctor blade coating (the process steps and parameters are the same as those in S2);

[0042] S6, then vacuum adsorption flat plate oven drying (process steps and parameters with S3).

[0043] S7, proton exchange membrane both sides load catalyst, both sides of the mat a carbon paper, then fit the frame, frame operation, get three-in-one electrode.

[0044] Comparative Example 1

[0045] A fuel cell membrane electrode manufacturing process, comprising the following steps:

[0046] S1, the proton exchange membrane roll cutting into sheet;

[0047] S2, take out the proton exchange membrane sheet, by ultrasonic spray on its one side load catalyst; catalyst for commercially available Pt / C catalyst, spray, commercially available Pt / C catalyst dispersed in ethanol, configured into a solid solution of 2% suspension; placed in a sealed ultrasonic container, placed in the ultrasonic precision spraying machine, control the flow rate of 3ml / min.

[0048] S3, then vacuum adsorption flat plate oven drying; vacuum adsorption flat plate oven, the flat plate connected to the vacuum device, drying operation, vacuum degree is 40mmHg, temperature is 120 DEG C.

[0049] S4, take out the other side of the proton exchange membrane by ultrasonic spray load catalyst (process steps and parameters with S2);

[0050] S5, then vacuum adsorption flat plate oven drying (process steps and parameters with S3).

[0051] S6, proton exchange membrane both sides load catalyst, both sides of the mat a carbon paper, then fit the frame, frame operation, get three-in-one electrode.

[0052] Comparative Example 2

[0053] A fuel cell membrane electrode manufacturing process, comprising the following steps:

[0054] S1, the proton exchange membrane roll cutting into sheet;

[0055] S2, take out the proton exchange membrane sheet, by doctor blade coating on its one side load catalyst; catalyst for commercially available Pt / C catalyst, spray, commercially available Pt / C catalyst dissolved in ethanol, configured into a solid solution of 7% slurry; doctor blade coating speed of 3m / min.

[0056] S3, then vacuum adsorption flat plate oven drying; vacuum adsorption flat plate oven, the flat plate connected to the vacuum device, drying operation, vacuum degree is 50mmHg, temperature is 120 DEG C.

[0057] S4, after taking out, the other side of the proton exchange membrane is coated with catalyst by a doctor blade (the process steps and parameters are the same as S2);

[0058] S5, then the vacuum adsorption flat plate oven is dried (the process steps and parameters are the same as S3).

[0059] S6, after loading catalyst on both sides of the proton exchange membrane, one carbon paper is placed on each side, then the frame is attached, and the frame is pressed to obtain a three-in-one electrode.

[0060] In the comparative examples, wrinkles are generated in different degrees during the process of preparing the membrane electrode, and the power generation performance is reduced during the test. The fuel cells prepared in Examples 1-2 and Comparative Examples 1-2 are tested for the following performances:

[0061] Electrochemical performance test: 50 cm 2 The membrane electrodes prepared in Examples 1-2 are tested for the voltage V1 and V2 under the conditions of a current density of 1 A / cm 2 and 2.0 A / cm 2 at 75℃, a cathode pressure of 70 KPa, and an anode pressure of 80 KPa.

[0062] The test results are shown in Table 1.

[0063] V1(V) V2(V) Example 1 0.793 0.655 Example 2 0.789 0.647 Comparative Example 1 0.715 0.604 Comparative Example 2 0.708 0.603

[0064] As shown in the above table, the membrane electrode prepared by the method of the present application has better performance.

Claims

1. A process for making a fuel cell membrane electrode, characterized by, The method comprises the following steps: S1, cutting the proton exchange membrane roll into a sheet and placing it in a constant temperature and humidity cabinet for 2-20 hours; the temperature and humidity of the constant temperature and humidity cabinet are consistent with the temperature and humidity of the operation conditions of the membrane electrode ultrasonic spraying or doctor blade coating; the temperature of the constant temperature and humidity cabinet is 60-100℃, and the humidity is 80%-100% relative humidity; S2, taking out the proton exchange membrane sheet and loading catalyst on one side thereof by ultrasonic spraying or doctor blade coating; S3, then drying by using a vacuum adsorption flat plate oven; S4, placing the obtained proton exchange membrane sheet with catalyst loaded on one side again in a constant temperature and humidity cabinet for 2-20 hours; S5, taking out and loading catalyst on the other side of the proton exchange membrane by ultrasonic spraying or doctor blade coating; S6, then drying by using a vacuum adsorption flat plate oven; The vacuum adsorption flat plate oven is connected with a vacuum device, and the vacuum degree is 30-60mmHg and the temperature is 110-120℃ during drying operation.

2. The process for making a fuel cell membrane electrode according to claim 1, wherein The ultrasonic spraying is placing the proton exchange membrane in an ultrasonic precision spraying machine, the ultrasonic wave is 40KHZ, the spraying amount of the spraying device is controlled to be 2-20ml / min per second, and the gas pressure of the spraying nozzle is 2KPa.

3. The process for making a fuel cell membrane electrode of claim 1, wherein The coating speed of the doctor blade coating is (1-6)m / min.

4. The process for making a fuel cell membrane electrode of claim 1, wherein The catalyst is a commercially available Pt / C catalyst.

5. The process for making a fuel cell membrane electrode according to claim 1 or 4, wherein When the spraying process is used, the commercially available Pt / C catalyst is dispersed in ethanol to prepare a suspension with a solid content of 2-10%.

6. The process for making a fuel cell membrane electrode according to claim 1 or 4, wherein When the doctor blade coating process is used, the commercially available Pt / C catalyst is dispersed in ethanol to prepare a slurry with a solid content of 2-10%.

7. The process for making a fuel cell membrane electrode of claim 1 wherein, After loading the catalyst on both sides of the proton exchange membrane, one carbon paper is placed on each side, then the frame is attached, and the frame is pressed to obtain a three-in-one electrode.