A proton exchange membrane fuel cell membrane electrode catalyst slurry and its dispersion process

Abstract

This invention belongs to the field of fuel cell technology, specifically relating to a proton exchange membrane fuel cell membrane electrode catalyst slurry and its dispersion process. The proton exchange membrane fuel cell membrane electrode catalyst slurry of this invention comprises a catalyst, a perfluorosulfonic acid resin solution, ultrapure water, isopropanol, and ethanol. The catalyst is one or more of a platinum-carbon catalyst, a platinum-cobalt alloy catalyst, and a ternary alloy catalyst, with a platinum loading of 40%-70%. This invention achieves precise control of the slurry viscosity by adjusting the ratio of various alcohols to water in the catalyst slurry and cleverly increasing the temperature of the catalyst slurry during dispersion, thereby ensuring that the slurry achieves ideal rheological properties during dispersion. This control strategy of adjusting the ratio of alcohol to water and optimizing the dispersion temperature not only promotes uniform dispersion of the slurry but also significantly improves the dispersion efficiency, without introducing non-volatile substances, providing a solid foundation for the preparation of a high-performance catalyst layer.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, and specifically relates to a proton exchange membrane fuel cell membrane electrode catalyst slurry and its dispersion process. Background Technology

[0002] PEMFC generates electricity through the electrochemical reaction of hydrogen and oxygen, making it highly efficient and environmentally friendly. Its core structure includes an anode, a cathode, and a proton exchange membrane. The catalyst accelerates the electrochemical reaction, while the proton exchange membrane allows protons to pass through but prevents direct electron transfer, thereby generating an electric current.

[0003] While fuel cell technology has applications in aerospace and other fields, its wider application is limited by factors such as cost, power density, and lifespan. Currently, reducing the production cost of fuel cell stacks is key to promoting the large-scale application of fuel cells, and the performance and manufacturing process of the membrane electrode assembly (MEA) catalyst layer are crucial to the overall performance of the battery. However, challenges in MEA preparation, such as difficulty in dispersing catalyst slurry, high internal resistance of the catalyst layer, and susceptibility to cracking, limit the industrialization of fuel cells.

[0004] To address issues such as difficulty in dispersing catalyst slurry, high internal resistance of the catalyst layer, and easy cracking during membrane electrode preparation, conventional methods include lowering the dispersion temperature of the catalyst slurry and adding substances such as anti-cracking agents, thickeners, and conductive carbon nanotubes. However, low-temperature dispersion is not conducive to uniform resin dispersion, and external additives can affect catalyst performance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a proton exchange membrane fuel cell membrane electrode catalyst slurry and its dispersion process. This invention achieves precise control of the catalyst slurry viscosity by adjusting the ratio of various alcohols to water in the slurry and cleverly increasing the temperature during dispersion, thereby ensuring that the slurry achieves ideal rheological properties during dispersion. This strategy of adjusting the alcohol-to-water ratio and optimizing the dispersion temperature not only promotes uniform dispersion of the catalyst slurry but also significantly improves dispersion efficiency without introducing non-volatile substances, providing a solid foundation for the preparation of a high-performance catalyst layer. Through this method, we can ensure that the catalyst in each drop of slurry is fully dispersed, avoiding localized concentration unevenness, thus providing a more uniform reaction environment for subsequent coating processes. This precise control of the dispersion process is a key step in achieving high-efficiency catalytic performance and is the core of the technological innovation of this invention.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] In a first aspect, embodiments of the present invention provide a proton exchange membrane fuel cell membrane electrode catalyst slurry, comprising a catalyst, a perfluorosulfonic acid resin solution, ultrapure water, isopropanol and ethanol, wherein the catalyst is one or more of a platinum-carbon catalyst, a platinum-cobalt alloy catalyst and a ternary alloy catalyst, and the platinum loading is 40%-70%.

[0008] In a second aspect, embodiments of the present invention provide a dispersion process for the proton exchange membrane fuel cell membrane electrode catalyst slurry described in the first aspect, comprising the following steps:

[0009] (1) Weigh a certain amount of catalyst, ultrapure water, isopropanol, ethanol and perfluorosulfonic acid resin solution and add them to a jacketed glass cup;

[0010] (2) Stir the mixture from step (1) using a cantilever stirrer or a magnetic stirrer. During the stirring process, warm water is introduced into the jacket of the glass cup to keep it warm.

[0011] (3) The catalyst mixture obtained in step (2) is subjected to high-speed shear dispersion. During the dispersion process, warm water is introduced into the jacket of the glass cup for heat preservation.

[0012] (4) Stir the catalyst slurry obtained in step (3). During the stirring process, warm water is introduced into the jacket of the glass cup to keep it warm.

[0013] (5) Stir the catalyst slurry obtained in step (4) and cool it to 15-20℃ for later use.

[0014] Further, in step (1), the mass ratio of ethanol to isopropanol is 1:10-200, and the mass ratio of the total mass of ethanol and isopropanol to the mass of ultrapure water is 1-4:1.

[0015] Furthermore, the water temperature of the warm water mentioned in steps (2), (3) and (4) is controlled at 30-50℃;

[0016] The stirring speed in steps (2) and (4) is controlled at 200-350 rpm, and the stirring speed in step (3) is controlled at 8000-15000 rpm.

[0017] Furthermore, when using a magnetic stirrer for stirring in step (2), a suitable magnet is placed in the jacketed glass cup in advance.

[0018] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows:

[0019] This invention enables perfluorosulfonic acid resin to be well dispersed in the solvent by precisely controlling the temperature (30℃-50℃) of the catalyst slurry during the dispersion process, thereby forming a uniform coating on the catalyst. At the same time, it optimizes the rheological properties of the catalyst slurry, achieves precise viscosity control, significantly improves the uniformity of the catalyst slurry dispersion, and improves the dispersion efficiency, providing a solid foundation for the preparation of high-performance catalyst layers.

[0020] This precise temperature control ensures the catalyst in the slurry is fully dispersed, effectively preventing localized concentration imbalances and creating a uniform reaction environment for the coating process. Furthermore, this method effectively reduces the internal resistance of the catalyst layer without increasing production costs, significantly improving membrane electrode performance and extending its service life.

[0021] The innovation of this invention lies in the precise control of the dispersion process, which improves the microstructure of the catalyst layer, enhances the performance and efficiency of the fuel cell, and strengthens its durability and reliability, thus providing technical support for the commercialization and large-scale application of fuel cell technology. Attached Figure Description

[0022] Figure 1 This is a performance comparison of the membrane electrodes prepared from the catalyst slurry in Example 1 and Comparative Example 1 of the present invention.

[0023] Figure 2 This is a performance comparison of the membrane electrodes prepared from the catalyst slurry in Example 2 and Comparative Example 1 of the present invention.

[0024] Figure 3 This describes the performance of the membrane electrode prepared from the catalyst slurry in Comparative Example 2 of this invention.

[0025] Figure 4 This is a comparison of the rheological curves of the membrane electrode performance prepared by the catalyst slurry in Example 1 and Comparative Example 1 of the present invention.

[0026] Figure 5 This is a performance comparison of the membrane electrodes prepared from the catalyst slurry in Examples 1 and 3 of this invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0028] Example 1

[0029] A dispersion process for a proton exchange membrane fuel cell membrane electrode catalyst slurry includes the following steps:

[0030] (1) Weigh 5 grams of catalyst (50% platinum-loaded platinum carbon catalyst) and place it in a jacketed glass cup. Add 500 mL of deionized water, 5 mL of ethanol, 500 mL of isopropanol and 12.5 mL of D2020 perfluorosulfonic acid resin solution. Stir the mixture with a cantilever stirrer at a speed of 300 rpm. Pass 40°C constant temperature water into the jacket and stir for 30 min. Then, use a homogenizer to forcibly disperse the mixture for 30 min at a speed of 10000 rpm.

[0031] (2) Use a cantilever stirrer to stir the dispersion in the jacketed glass cup at a speed of 300 rpm and introduce constant temperature water at 40°C into the jacket to fully stir and disperse the mixture to form a uniform catalyst slurry. Stir the prepared catalyst slurry and cool it to 15°C-20°C to prevent sedimentation.

[0032] The catalyst slurry was sprayed onto both sides of a proton exchange membrane with an area of ​​130 mm × 280 mm (the sprayed catalyst layer was tested with XRF, and the anode loading was controlled at 0.06 mg / cm³). 2 Cathode loading: 0.5 mg / cm³ 2 After drying, the CCM is sealed with a frame, and the GDL is attached to form an MEA. It is then placed in a battery fixture for performance and lifespan testing. The performance curves are shown in the figure below. Figure 1 .

[0033] Example 2

[0034] A dispersion process for a proton exchange membrane fuel cell membrane electrode catalyst slurry includes the following steps:

[0035] (1) Weigh 5 grams of catalyst (50% platinum-loaded platinum carbon catalyst) and place it in a jacketed glass cup. Add 500 mL of deionized water, 50 mL of ethanol, 500 mL of isopropanol and 12.5 mL of D2020 perfluorosulfonic acid resin solution. Stir the mixture with a cantilever stirrer at a speed of 300 rpm. Pass 50°C constant temperature water into the jacket and stir for 30 min. Then, use a homogenizer to forcibly disperse the mixture for 30 min at a speed of 10000 rpm.

[0036] (2) Use a cantilever stirrer to stir the dispersion in the jacketed glass cup at a speed of 300 rpm and introduce 50°C constant temperature water into the jacket to fully stir and disperse the mixture to form a uniform catalyst slurry. Stir the prepared catalyst slurry and cool it to 15-20°C to prevent sedimentation.

[0037] The catalyst slurry was sprayed onto both sides of a proton exchange membrane with an area of ​​130 mm × 280 mm (the sprayed catalyst layer was tested with XRF, and the anode loading was controlled at 0.06 mg / cm³). 2 Cathode loading: 0.5 mg / cm³ 2 After drying, the CCM is sealed with a frame, and the GDL is attached to form an MEA. It is then placed in a battery fixture for performance and lifespan testing. The performance curves are shown in the figure below. Figure 2 .

[0038] Example 3

[0039] A dispersion process for a proton exchange membrane fuel cell membrane electrode catalyst slurry includes the following steps:

[0040] (1) Weigh 5 grams of catalyst (50% platinum-loaded platinum carbon catalyst) and place it in a jacketed glass cup. Add 500 mL of deionized water, 10 mL of ethanol, 600 mL of isopropanol and 12.5 mL of D2020 perfluorosulfonic acid resin solution. Stir the mixture with a cantilever stirrer at a speed of 300 rpm. Pass 40°C constant temperature water into the jacket and stir for 30 min. Then, use a homogenizer to forcibly disperse the mixture for 30 min at a speed of 10000 rpm.

[0041] (2) Use a cantilever stirrer to stir the dispersion in the jacketed glass cup at a speed of 300 rpm and introduce constant temperature water at 40°C into the jacket to fully stir and disperse the mixture to form a uniform catalyst slurry. Stir the prepared catalyst slurry and cool it to 15°C-20°C to prevent sedimentation.

[0042] The catalyst slurry was sprayed onto both sides of a proton exchange membrane with an area of ​​130 mm × 280 mm (the sprayed catalyst layer was tested with XRF, and the anode loading was controlled at 0.06 mg / cm³). 2 Cathode loading: 0.5 mg / cm³ 2 After drying, the CCM is sealed with a frame, and the GDL is attached to form an MEA. It is then placed in a battery fixture for performance and lifespan testing. The performance curves are shown in the figure below. Figure 5 .

[0043] Comparative Example 1

[0044] A dispersion process for a proton exchange membrane fuel cell membrane electrode catalyst slurry includes the following steps:

[0045] (1) Weigh 5 grams of catalyst (50% platinum-loaded platinum carbon catalyst) and place it in a jacketed glass cup. Add 500 mL of deionized water, 5 mL of ethanol, 500 mL of isopropanol and 12.5 mL of D2020 perfluorosulfonic acid resin solution. Stir the mixture with a cantilever stirrer at a speed of 300 rpm. Pass 25°C constant temperature water into the jacket and stir for 30 min. Then, use a homogenizer to forcibly disperse the mixture for 30 min at a speed of 10000 rpm.

[0046] (2) Use a cantilevered stirrer to stir the dispersion in the jacketed glass cup at a speed of 300 rpm, and introduce constant temperature water at 25°C into the jacket to fully stir and disperse the mixture to form a uniform catalyst slurry.

[0047] The catalyst slurry was sprayed onto both sides of a proton exchange membrane with an area of ​​130 mm × 280 mm (the sprayed catalyst layer was tested with XRF, and the anode loading was controlled at 0.06 mg / cm³). 2 Cathode loading: 0.5 mg / cm³ 2 (Drying). Seal the CCM frame, attach the GDL to form an MEA, place it in the battery fixture, and conduct performance and lifespan tests. The performance curve is shown in the figure. Figure 1 and Figure 2 .

[0048] Comparative Example 2

[0049] A dispersion process for a proton exchange membrane fuel cell membrane electrode catalyst slurry includes the following steps:

[0050] (1) Weigh 5 grams of catalyst (50% platinum-loaded platinum carbon catalyst) and place it in a jacketed glass cup. Add 500 mL of deionized water, 50 mL of ethanol, 500 mL of isopropanol and 12.5 mL of D2020 perfluorosulfonic acid resin solution. Stir the mixture with a cantilever stirrer at a speed of 300 rpm. Pass 5°C constant temperature water into the jacket and stir for 30 min. Then, use a homogenizer to forcibly disperse the mixture for 30 min at a speed of 10000 rpm.

[0051] (2) Use a cantilever stirrer to stir the dispersion in the jacketed glass cup at a speed of 300 rpm and introduce 5°C constant temperature water into the jacket to fully stir and disperse the mixture to form a uniform catalyst slurry. Stir the prepared catalyst slurry and cool it to 15-20°C to prevent sedimentation.

[0052] The catalyst slurry was sprayed onto both sides of a proton exchange membrane with an area of ​​130 mm × 280 mm (the sprayed catalyst layer was tested with XRF, and the anode loading was controlled at 0.06 mg / cm³).2 Cathode loading: 0.5 mg / cm³ 2 (Drying). Seal the CCM frame, attach the GDL to form an MEA, place it in the battery fixture, and conduct performance and lifespan tests. The performance curve is shown in the figure. Figure 3 .

[0053] Examples 1-2 investigated the effect of slurry dispersion temperatures of 40℃ and 50℃ on the performance of the prepared membrane electrodes, while Comparative Examples 1-2 investigated the effect of slurry dispersion temperatures of 25℃ and 5℃ on the performance of the prepared membrane electrodes. The performance of the membrane electrodes prepared from the catalyst slurries in Examples 1 and Comparative Examples 1 was compared. Figure 1 As shown; a performance comparison of the membrane electrodes prepared from the catalyst slurry in Example 2 and Comparative Example 1 is shown in the figure. Figure 2 As shown, the performance comparison of the membrane electrode prepared from the catalyst slurry in Comparative Example 2 is shown in [reference needed]. Figure 3 As shown. From Figure 1 , Figure 2 and Figure 3 The comparison shows that the membrane electrode prepared from the catalyst slurry in Examples 1 and 2 can effectively reduce the internal resistance of the membrane electrode catalyst layer and improve the membrane electrode performance.

[0054] Figure 4 A comparison of the rheological curves of the membrane electrodes prepared by dispersing the slurry at 40℃ in Example 1 and at room temperature in Comparative Example 1 shows that the shear viscosity of the catalyst slurry prepared in Example 1 is higher than that of the catalyst slurry in Comparative Example 1. This indicates that the dispersion process in Example 1 can improve the shear viscosity of the catalyst slurry. The higher the shear viscosity, the more stable the catalyst slurry and the less prone it is to sedimentation. Furthermore, the change in shear viscosity with the change of shear rate is not significant, indicating that the prepared catalyst slurry has good rheological properties.

[0055] Figure 5 This is a comparison of the performance of membrane electrodes prepared by catalyst slurry in Examples 1 and 3 of the present invention. As can be seen from the figure, the ratio of ethanol to isopropanol and the ratio of the total mass of ethanol and isopropanol to ultrapure water also have a certain influence on the performance of the prepared membrane electrodes.

[0056] The catalyst slurry dispersion process of this invention optimizes the viscosity of the catalyst slurry by precisely adjusting the dispersion temperature, ensuring uniform dispersion, improving dispersion efficiency, providing a foundation for the preparation of a high-performance catalyst layer, reducing the internal resistance of the catalyst layer, improving the performance of the membrane electrode, and extending its service life, thus providing technical advantages for the commercial application of fuel cells.

[0057] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A dispersion process for a proton exchange membrane fuel cell membrane electrode catalyst slurry, characterized in that, The catalyst slurry includes a catalyst, a perfluorosulfonic acid resin solution, ultrapure water, isopropanol, and ethanol. The catalyst is one or more of a platinum-carbon catalyst, a platinum-cobalt alloy catalyst, and a ternary alloy catalyst, with a platinum loading of 40%-70%. The dispersion process includes the following steps: (1) Weigh a certain amount of catalyst, ultrapure water, isopropanol, ethanol and perfluorosulfonic acid resin solution and add them to a jacketed glass cup; (2) Stir the mixture from step (1) using a cantilever stirrer or a magnetic stirrer. During the stirring process, warm water is introduced into the jacket of the glass cup to keep it warm. (3) The catalyst mixture obtained in step (2) is subjected to high-speed shear dispersion. During the dispersion process, warm water is introduced into the jacket of the glass cup for heat preservation. (4) Stir the catalyst slurry obtained in step (3). During the stirring process, warm water is introduced into the jacket of the glass cup to keep it warm. (5) Stir the catalyst slurry obtained in step (4) and cool it to 15-20℃ for later use; In step (1), the mass ratio of ethanol to isopropanol is 1:10-200, and the mass ratio of the total mass of ethanol and isopropanol to the mass of ultrapure water is 1-4:

1. The water temperature in steps (2), (3) and (4) is controlled at 30-50℃; The stirring speed in steps (2) and (4) is controlled at 200-350 rpm, and the stirring speed in step (3) is controlled at 8000-15000 rpm.

2. The dispersion process of the proton exchange membrane fuel cell membrane electrode catalyst slurry according to claim 1, characterized in that, When using a magnetic stirrer in step (2), a suitable magnet should be placed in the jacketed glass beforehand.

Images