Proton exchange membrane fuel cell low-platinum membrane electrode and preparation method thereof

Abstract

The invention belongs to the field of proton exchange membrane fuel cells, and particularly relates to a low-platinum membrane electrode of a proton exchange membrane fuel cell and a preparation method of the low-platinum membrane electrode, the low-platinum membrane electrode is characterized in that the loading capacity of a cathode catalyst layer is controlled to be 0.05 mg / cm < 2 >-0.07 mg / cm < 2 >, the loading capacity of an anode catalyst layer is controlled to be 0.01 mg / cm < 2 >-0.03 mg / cm < 2 >, and the loading capacity of the cathode catalyst layer is controlled to be 0.01 mg / cm < carbon nanotubes, carbon black, a polytetrafluoroethylene solution, a mixture of the carbon nanotubes and the carbon black, or a mixture of the carbon nanotubes, the carbon black and the polytetrafluoroethylene are introduced into a cathode catalyst layer, and the catalyst layer is prepared by changing the mixing and dispersing process of catalyst layer slurry; compared with the prior art, the invention provides the proton exchange membrane fuel cell with low platinum lt; according to the 0.1 mg / cm < 2 > membrane electrode and the preparation method of the cathode catalyst layer thereof, by adding a proper additive into the cathode catalyst layer and improving the preparation process of the cathode catalyst layer, dispersion of a catalyst can be improved, gas transmission of the catalyst layer is enhanced, and products are effectively discharged.

Description

[Technical Field]

[0001] The present invention belongs to the field of proton exchange membrane fuel cells, and particularly relates to a low-platinum membrane electrode for a proton exchange membrane fuel cell and a preparation method thereof. [Background Art]

[0002] As an environmentally friendly and efficient clean energy source, fuel cells have the characteristics of high energy density and low operating temperature, and have received extensive attention in recent years. During the energy conversion process, the slow cathode oxygen reduction reaction seriously hinders the efficiency of fuel cells. A large number of studies have shown that the cathode oxygen reduction reaction can be accelerated by a relatively high platinum loading. However, according to the report of the US Department of Energy (DOE), the platinum loading in the fuel cell cathode <0.1 mg / cm 2 is required to have market competitiveness. However, at present, the platinum loading in the cathodes of most commercial fuel cells is 0.4 - 0.6 mg / cm 2 , and the research by researchers shows that reducing the platinum loading in the fuel cell cathode <0.1 mg / cm 2 will lead to an increase in the concentration polarization loss of the membrane electrode and a decrease in performance.

[0003] To solve this problem, a large number of researchers have reported methods for replacing platinum catalysts by using alloy catalysts, core-shell nanostructure catalysts, etc.; Patent CN117352759A proposes to synthesize a ternary PtCoMn alloy catalyst by electrochemical deposition in one step to achieve catalyst characteristics such as uniform particle size and high dispersion. Its membrane electrode has a low platinum loading and high performance. However, the initial performance of the alloy catalyst is relatively high, and problems such as voltage decay, decrease in the electrochemically active area, and agglomeration of catalyst particles are caused by the dissolution of metal atoms; Patent CN109378482A discloses a catalyst with multiple active sites and a high specific surface area, which significantly improves the catalyst activity, reduces the use of platinum noble metals, and reduces the cost of fuel cells. However, this preparation method is complex and difficult to commercialize. In addition to developing new catalysts, improving the porous structure of the catalytic layer has also become one of the methods to solve the problem of reduced fuel cell performance. Patent CN201611177018 discloses adding carbon nanotubes or carbon fiber materials to the existing catalytic layer to improve the pore size distribution of the membrane electrode, reduce the oxygen transport resistance, and perform hydrophobic treatment on the gas diffusion layer to improve the diffusion and transport ability of the product. And the platinum loading in the cathode of the membrane electrode of this patent is 0.2 mg / cm 2 and the manufacturing process is complex.

[0004] Although the above different patents have achieved certain results in reducing the cost of the membrane electrode and improving the performance, whether the performance of a low-platinum <0.1 mg / cm 2 fuel cell can be improved through the optimization of the catalytic layer alone and whether the manufacturing process can be simplified are key technical problems that need to be solved urgently. [Summary of the Invention]

[0005] The object of the present invention is to solve the above deficiencies and provide a proton exchange membrane fuel cell with low platinum <0.1 mg / cm 2 membrane electrode and a preparation method for its cathode catalyst layer. By adding appropriate additives to the cathode catalyst layer and improving the preparation process of the cathode catalyst layer, the dispersion of the catalyst is improved, the gas transport in the catalyst layer is enhanced, and the products are effectively discharged.

[0006] To achieve the above object, a preparation method for a proton exchange membrane fuel cell with a low platinum membrane electrode is designed, including the following steps:

[0007] (1) Disperse perfluorosulfonic acid ionomer in a volatile solvent to obtain an ionomer dispersion;

[0008] (2) Mix carbon nanotubes, or carbon black, or polytetrafluoroethylene solution, or a mixture of carbon nanotubes and carbon black, or a mixture of carbon nanotubes, carbon black and polytetrafluoroethylene with the ionomer solution in step (1), perform high-speed shearing and ultrasonic oscillation, and then perform sufficient grinding to obtain a carbon nanotube solution, a carbon black solution, a polytetrafluoroethylene solution, a mixture solution of carbon nanotubes and carbon black, or a mixture solution of carbon nanotubes, carbon black and polytetrafluoroethylene;

[0009] (3) Add a platinum catalyst to the ionomer dispersion prepared in step (1), perform high-speed shearing and ultrasonic oscillation, and then perform high-speed grinding and low-temperature controlled dispersion to obtain a catalyst solution;

[0010] (4) Take a carbon nanotube solution, a carbon black solution, a polytetrafluoroethylene solution, a mixture solution of carbon nanotubes and carbon black, or a mixture solution of carbon nanotubes, carbon black and polytetrafluoroethylene, mix it with the catalyst solution, perform high-speed shearing and ultrasonic oscillation to obtain a cathode catalyst layer slurry;

[0011] (5) Use an extrusion coating process to coat the cathode catalyst layer slurry on one side of a polytetrafluoroethylene substrate, control the loading of the cathode catalyst layer at 0.05 - 0.07 mg / cm 2 , bake the coated cathode catalyst layer at 30 - 120 °C for 5 - 30 minutes to obtain a cathode catalyst layer;

[0012] (6) Add a platinum catalyst to the ionomer dispersion prepared in step (1), perform high-speed shearing and ultrasonic oscillation, and then perform sufficient grinding and mixing to obtain an anode catalyst layer slurry;

[0013] (7) Use an extrusion coating process to coat the anode catalyst layer slurry on one side of a polytetrafluoroethylene substrate, control the loading of the anode catalyst layer at 0.01 - 0.03 mg / cm 2, bake the coated anode catalyst layer at 30 - 120 °C for 2 - 30 minutes to obtain the anode catalyst layer;

[0014] (8) Attach the cathode catalyst layer and the anode catalyst layer to both sides of the proton exchange membrane by thermal transfer printing respectively to obtain a three-in-one membrane electrode;

[0015] (9) Cut two gas diffusion layers and attach them to the corresponding sides of the three-in-one membrane electrode prepared in step (8), and then perform edge sealing treatment to obtain a low-loading 0.05 - 0.1 mg / cm 2 membrane electrode with an additive in the cathode catalyst layer.

[0016] Furthermore, in step (1), the perfluorosulfonic acid ionomer uses a perfluorosulfonic acid ionomer stock solution; the mass fraction of the perfluorosulfonic acid ionomer is 20% - 50%, the dispersion time is 60 - 500 minutes; the dispersion method is at least one of mechanical stirring or magnetic stirring, and the stirring speed is 5000 - 30000 rpm; the mass fraction of the ionomer dispersion liquid is 4% - 20%.

[0017] Furthermore, in step (1), the volatile solvent is one or more of distilled water, ethanol, or isopropanol, and the mass ratio of distilled water to ethanol or / and isopropanol is (2 - 10):1.

[0018] Furthermore, in step (2), magnetic stirring is used for high-speed shearing, the high-speed shearing rate is 8000 - 20000 rpm, and the high-speed shearing time is 30 - 100 minutes; the ultrasonic frequency is 5 - 10 mHz, and the ultrasonic time is 30 - 120 minutes; the solid content of the carbon nanotube solution, carbon black solution, or the mixture solution of carbon nanotube and carbon black is 3% - 30%.

[0019] Furthermore, in step (3), the Pt content of the platinum catalyst used is Pt / C with 50% - 60%; magnetic stirring is used for high-speed shearing, the shearing rate is 8000 - 30000 rpm, and the high-speed shearing time is 100 - 200 minutes; the ultrasonic frequency is 5 - 20 mHz, and the ultrasonic time is 100 - 200 minutes; the rotation speed of grinding and dispersion is 2000 - 3000 rpm, and the grinding time is 100 - 200 minutes; the temperature during the dispersion process is controlled at 0 - 10 °C; the solid content of the catalyst solution is 5% - 15%.

[0020] Furthermore, in step (4), magnetic stirring is used for high-speed shearing, the shearing rate is 8000 - 20000 rpm, and the high-speed shearing time is 30 - 300 minutes; the ultrasonic frequency is 5 - 20 mHz, and the ultrasonic time is 30 - 120 minutes.

[0021] Further, in step (6), the Pt content of the platinum catalyst is 30%-50%; magnetic stirring is used for high-speed shearing, the shearing rate is 8000-30000 rpm, the high-speed shearing time is 100-200 minutes; the ultrasonic frequency is 5-20 mHz, and the ultrasonic time is 100-200 minutes; the rotation speed of grinding and dispersion is 2000-3000 rpm, and the grinding time is 100-200 minutes; the temperature during the dispersion process is controlled at 0-10°C.

[0022] Further, in step (8), the thickness of the proton exchange membrane is 8-12 μm; the hot press transfer temperature is 100-200°C; the hot press transfer pressure is 150-300 kPa; the hot press transfer time is 200-400 minutes.

[0023] The present invention also provides a low-platinum membrane electrode for a proton exchange membrane fuel cell, which is prepared by the preparation method of the low-platinum membrane electrode for a proton exchange membrane fuel cell described in any one of the above.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The present invention directly adds carbon nanotubes, carbon black, polytetrafluoroethylene solution, a mixture of carbon nanotubes and carbon black, and a mixture of carbon nanotubes, carbon black and polytetrafluoroethylene to the cathode catalyst layer slurry to manufacture a low-platinum loading <0.1 mg / cm 2 membrane electrode. Introducing carbon black into the cathode catalyst layer can better disperse the catalyst, increase the platinum utilization rate, thereby improving the catalytic activity performance of the low-platinum <0.1 mg / cm 2 membrane electrode and reducing the activation polarization loss of the low-platinum <0.1 mg / cm 2 membrane electrode; introducing carbon nanotubes can further increase the thickness of the <0.1 mg / cm 2 membrane electrode catalyst layer and reduce the contact resistance of the membrane electrode, thereby reducing the ohmic polarization loss of the low-platinum <0.1 mg / cm 2 membrane electrode; adding PTFE can effectively reduce the oxygen transmission resistance, thereby reducing the concentration polarization loss of the low-platinum <0.1 mg / cm 2 membrane electrode;

[0026] (2) The cathode catalyst layer slurry and the anode catalyst layer slurry of the present invention adopt a dispersion method of simultaneous high-speed shearing and ultrasonic oscillation supplemented by grinding, which is beneficial to the full dispersion of catalyst particles, and the preparation method is simple and easy to implement and can be commercially applied;

[0027] (3) The low-platinum membrane electrode for a proton exchange membrane fuel cell and its cathode catalyst layer described in the present invention are low-cost and can be mass-produced;

[0028] In summary, the present invention proposes a low-platinum <0.1 mg / cm for a proton exchange membrane fuel cell2 Membrane electrode and preparation method of its cathode catalyst layer. By adding appropriate additives to the cathode catalyst layer and improving the preparation process of the cathode catalyst layer, the dispersion of the catalyst can be improved, the gas transport in the catalyst layer can be enhanced, and the products can be effectively discharged. [Description of the Drawings]

[0029] Figure 1 It is a performance comparison diagram of Example 1 to Example 5 and the comparative example of the present invention. [Detailed Embodiments]

[0030] The present invention provides a proton exchange membrane fuel cell with low platinum <0.1mg / cm 2 Membrane electrode and preparation method of its cathode catalyst layer, including the following steps:

[0031] (1) Disperse perfluorosulfonic acid ionomer in a volatile solvent to obtain an ionomer dispersion;

[0032] (2) Mix carbon nanotubes, or carbon black, or polytetrafluoroethylene solution, or a mixture of carbon nanotubes and carbon black, or a mixture of carbon nanotubes, carbon black and polytetrafluoroethylene with the ionomer solution in step (1), perform high-speed shearing and ultrasonic oscillation, and then perform sufficient grinding to obtain a carbon nanotube solution, a carbon black solution or a mixture solution of carbon nanotubes and carbon black;

[0033] (3) Add a platinum catalyst to the ionomer dispersion, perform high-speed shearing and ultrasonic oscillation, and then perform high-speed grinding and low-temperature controlled dispersion to obtain a catalyst solution;

[0034] (4) Take the carbon nanotube solution, carbon black solution, polytetrafluoroethylene solution, mixture solution of carbon nanotubes and carbon black, or mixture solution of carbon nanotubes, carbon black and polytetrafluoroethylene, mix it with the catalyst solution, perform high-speed shearing and ultrasonic oscillation to obtain a cathode catalyst layer slurry;

[0035] (5) Use the extrusion coating process to coat the cathode catalyst layer slurry on one side of a polytetrafluoroethylene substrate, and control the loading of the cathode catalyst layer at 0.05mg / cm 2 -0.07mg / cm 2 , bake the coated cathode catalyst layer at 30°C - 120°C for 5 - 30 minutes to obtain the cathode catalyst layer;

[0036] (6) Add a platinum catalyst to the ionomer dispersion prepared in step (1), perform high-speed shearing and ultrasonic oscillation, and then perform sufficient grinding and mixing to obtain an anode catalyst layer slurry;

[0037] (7) The anode catalyst layer slurry is fluorinated and coated on one side of the polytetrafluoroethylene substrate by an extrusion coating process, and the loading of the anode catalyst layer is controlled at 0.01 mg / cm 2 -0.03 mg / cm 2 , and the coated anode catalyst layer is baked at 30°C - 120°C for 2 - 30 minutes to obtain the anode catalyst layer;

[0038] (8) The cathode catalyst layer and the anode catalyst layer are respectively laminated on both sides of the proton exchange membrane by means of hot press transfer or the like to obtain a three-in-one membrane electrode;

[0039] (9) Cut two gas diffusion layers and laminate them on the corresponding sides of the three-in-one membrane electrode prepared in step (8), and then perform edge sealing treatment to obtain a low-loading 0.05 mg / cm cathode catalyst layer containing additives 2 -0.07 mg / cm 2 membrane electrode.

[0040] A low-platinum <0.1 mg / cm proton exchange membrane fuel cell 2 membrane electrode and a preparation method for its cathode catalyst layer. The low-platinum membrane electrode controls the loading of the cathode catalyst layer at 0.05 mg / cm 2 -0.07 mg / cm 2 , the loading of the anode catalyst layer at 0.01 mg / cm 2 -0.03 mg / cm 2 , and carbon nanotubes, carbon black, polytetrafluoroethylene solution, a mixture of carbon nanotubes and carbon black, or a mixture of carbon nanotubes, carbon black and polytetrafluoroethylene are introduced into the cathode catalyst layer, and are prepared by changing the mixing and dispersion process of the catalyst layer slurry.

[0041] The present invention also provides a low-platinum membrane electrode for a proton exchange membrane fuel cell, which is prepared by the preparation method of the low-platinum membrane electrode for a proton exchange membrane fuel cell described above.

[0042] In some embodiments, in step (1), the perfluorosulfonic acid ionomer uses a perfluorosulfonic acid ionomer stock solution; the mass fraction of the perfluorosulfonic acid ionomer is about 20% - 50%, and the dispersion time is 60 minutes - 500 minutes; and / or, the dispersion method includes at least one of mechanical stirring or magnetic stirring, and the stirring speed is 5000 rpm - 30000 rpm; and / or, the mass fraction of the ionomer dispersion liquid is 4% - 20%.

[0043] In some embodiments, in step (1), the volatile solvent is one or more of distilled water, ethanol or isopropanol, and the mass ratio of distilled water to isopropanol is (2 - 10):1.

[0044] In some embodiments, in step (2), magnetic stirring is used for high-speed shearing, the high-speed shearing rate is 8000 - 20000 rpm, and the high-speed shearing time is 30 - 100 minutes; and / or, the ultrasonic frequency is 5 - 10 mHz, and the ultrasonic time is 30 - 120 minutes; and / or, the solid content of the carbon nanotube solution, carbon black solution, or the mixture solution of carbon nanotubes and carbon black is 3% - 30%.

[0045] In some embodiments, in step (3), the Pt content of the platinum catalyst used is 50% - 60% Pt / C; and / or, magnetic stirring is used for high-speed shearing, the shearing rate is 8000 - 30000 rpm, and the high-speed shearing time is 100 - 200 minutes; and / or, the ultrasonic frequency is 5 - 20 mHz, and the ultrasonic time is 100 - 200 minutes; and / or, the rotation speed of grinding and dispersion is 2000 - 3000 rpm, and the grinding time is 100 - 200 minutes; and / or, the temperature during the dispersion process in step (3) is controlled at 0 - 10°C; and / or, the solid content of the catalyst solution is 5% - 15%.

[0046] In some embodiments, in dispersion step (4), the catalyst solution is mixed with carbon nanotubes, carbon black, polytetrafluoroethylene solution, the mixture of carbon nanotubes and carbon black, or the mixture of carbon nanotubes, carbon black and polytetrafluoroethylene; and / or, magnetic stirring is used for high-speed shearing, the shearing rate is 8000 - 20000 rpm, and the high-speed shearing time is 30 - 300 minutes; and / or, the ultrasonic frequency is 5 - 20 mHz, and the ultrasonic time is 30 - 120 minutes.

[0047] In some embodiments, the Pt content of the platinum catalyst in step (6) is 30% - 50%; and / or, the dispersion method and dispersion time in step (6) are exactly the same as those in step (3).

[0048] In some embodiments, the thickness of the proton exchange membrane in step (8) is 8 - 12 μm; and / or, the hot embossing temperature is 100 - 200°C; the hot embossing pressure is 150 - 300 kPa; and the hot embossing time is 200 - 400 minutes.

[0049] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0050] Example 1

[0051] In the first step, perfluorosulfonic acid polymer, distilled water, and isopropanol were weighed in a mass ratio of 1:4:6 in a 50 mL beaker, a magnetic stir bar with a diameter of 2 - 3 cm was placed, and magnetic stirring was carried out for 60 min at a stirring speed of 5000 rpm to obtain a uniformly mixed ionomer solution;

[0052] Step 2: Weigh carbon nanotubes and ionomer solution at a mass ratio of 0.5:14 into a 50 mL beaker. Place a magnetic stir bar with a diameter of 2 - 3 cm and stir magnetically for 60 min at a stirring speed of 8000 rpm / min. Start ultrasonic oscillation simultaneously while magnetic stirring. The ultrasonic frequency is 5 mHz and the ultrasonic oscillation lasts for 60 min to obtain a preliminarily mixed carbon nanotube solution. Then transfer the carbon nanotube solution to a ball milling tank and grind it thoroughly. The grinding speed is 3000 rpm / min and the grinding time is 60 min to obtain a uniformly mixed carbon nanotube solution;

[0053] Step 3: Weigh platinum catalyst (60% Pt / C) and ionomer solution at a mass ratio of 1.5:20 into a 50 mL beaker. Place a magnetic stir bar with a diameter of 2 - 3 cm and stir magnetically for 60 min at a stirring speed of 8000 rpm / min. Start ultrasonic oscillation simultaneously while magnetic stirring. The ultrasonic frequency is 5 mHz and the ultrasonic oscillation lasts for 60 min to obtain a preliminarily mixed catalyst solution. Then transfer the catalyst solution to a ball milling tank and grind it thoroughly. The grinding speed is 3000 rpm / min and the grinding time is 60 min. During the processes of shearing, ultrasonic treatment, and grinding, the solution temperature is maintained at 0 - 10 °C to obtain a uniformly mixed catalyst solution;

[0054] Step 4: Weigh the catalyst solution and carbon nanotube solution at a mass ratio of 7:3 into a 25 mL beaker. Place a magnetic stir bar with a diameter of 1 - 2 cm and stir magnetically for 30 min at a stirring speed of 8000 rpm / min. Start ultrasonic oscillation simultaneously while magnetic stirring. The ultrasonic frequency is 5 mHz and the ultrasonic oscillation lasts for 30 min. During the processes of shearing and ultrasonic treatment, the slurry temperature is maintained at 0 - 10 °C to obtain a uniformly mixed cathode catalyst layer slurry;

[0055] Step 5: Uniformly coat it on one side of a polytetrafluoroethylene substrate through an extrusion coating process and dry it in a forced-air drying oven at a temperature of 50 °C for 10 min to prepare the cathode catalyst layer, where the loading of the cathode catalyst layer is 0.05 mg / cm 2 -0.07 mg / cm 2 ;

[0056] Step 6: Weigh the platinum catalyst (30% Pt / C) and the ionomer solution at a mass ratio of 1:19 into a 50 mL beaker, place a magnetic stir bar with a diameter of 2 - 3 cm, stir magnetically for 60 min at a stirring speed of 8000 rpm / min. While stirring magnetically, start ultrasonic oscillation at an ultrasonic frequency of 5 mHz for 60 min to obtain a preliminarily mixed anode catalyst layer slurry. Then transfer the anode catalyst layer slurry to a ball mill tank for sufficient grinding at a grinding speed of 3000 rpm / min for 60 min. During the shearing, ultrasonic, and grinding processes, the solution temperature is maintained at 0 - 10 °C to obtain a uniformly mixed anode catalyst layer slurry.

[0057] Step 7: Uniformly coat it on one side of the polytetrafluoroethylene substrate through an extrusion coating process, and dry it in a forced-air drying oven at a temperature of 50 °C for 6 min to prepare the anode catalyst layer, where the anode catalyst layer loading is 0.01 mg / cm 2 - 0.03 mg / cm 2 ;

[0058] Step 8: Place the cathode catalyst layer (0.05 mg / cm 2 - 0.07 mg / cm 2 ) and the anode catalyst layer (0.01 mg / cm 2 - 0.03 mg / cm 2 ) on both sides of the proton exchange membrane. After hot pressing and transfer printing, bond the gas diffusion layers on both sides and frame it to obtain the membrane electrode.

[0059] Step 9: Place the membrane electrode prepared in Step 8 in a test fixture and test the I - V performance under the same working conditions.

[0060] Example 2

[0061] The preparation method is the same as that of Example 1, except that in Step 2, carbon black and the ionomer solution are weighed into a 50 mL beaker at a mass ratio of 0.5:14.

[0062] Example 3

[0063] The preparation method is the same as that of Example 1, except that in Step 2, a mixture of carbon black and carbon nanotubes and the ionomer solution are weighed into a 50 mL beaker at a mass ratio of 0.5:14.

[0064] Example 4

[0065] The preparation method is the same as that of Example 1, except that in Step 2, the polytetrafluoroethylene solution and the ionomer solution are weighed into a 50 mL beaker at a mass ratio of 0.5:14.

[0066] Example 5

[0067] The preparation method is the same as that of Example 1, except that in the second step, carbon black, carbon nanotubes, and a polytetrafluoroethylene mixture and an ionomer solution are weighed at a mass ratio of 0.5:14 and placed in a 50 mL beaker.

[0068] Comparative Example

[0069] The preparation method is the same as that of Example 1, except that the second and fourth steps are omitted to obtain a catalyst slurry.

[0070] Combining the above Examples 1 to 5 and the Comparative Example, it can be seen that the present invention provides a proton exchange membrane fuel cell with low platinum <0.1 mg / cm 2 membrane electrode and a preparation method for its cathode catalyst layer. The low-platinum membrane electrode controls the loading of the cathode catalyst layer at 0.05 mg / cm 2 -0.07 mg / cm 2 , the loading of the anode catalyst layer at 0.01 mg / cm 2 -0.03 mg / cm 2 , and carbon nanotubes, carbon black, a polytetrafluoroethylene solution, a mixture of carbon nanotubes and carbon black, or a mixture of carbon nanotubes, carbon black, and polytetrafluoroethylene are introduced into the cathode catalyst layer. It is prepared by changing the mixing and dispersion process of the catalyst layer slurry, that is, a low-loading 0.05 mg / cm 2 -0.1 mg / cm 2 membrane electrode with additives in the cathode catalyst layer is obtained.

[0071] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art. The standard parts used can be purchased from the market. The special-shaped parts can be customized according to the records in the specification and the drawings. The specific connection methods of each part all adopt conventional means such as bolts, rivets, and welding in the prior art. The machines, parts, and equipment all adopt conventional models in the prior art, and the circuit connections adopt conventional connection methods in the prior art, which will not be elaborated here.

[0072] The present invention is not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for preparing a low-platinum membrane electrode of a proton exchange membrane fuel cell, characterized in that, It includes the following steps: (1) Disperse perfluorosulfonic acid ionomer in a volatile solvent to obtain an ionomer dispersion; (2) Mix carbon nanotubes, or carbon black, or polytetrafluoroethylene solution, or a mixture of carbon nanotubes and carbon black, or a mixture of carbon nanotubes, carbon black and polytetrafluoroethylene with the ionomer solution in step (1), carry out high-speed shearing and ultrasonic oscillation, and then carry out sufficient grinding to obtain a carbon nanotube solution, a carbon black solution, a polytetrafluoroethylene solution, a mixture solution of carbon nanotubes and carbon black, or a mixture solution of carbon nanotubes, carbon black and polytetrafluoroethylene; (3) Add a platinum catalyst to the ionomer dispersion prepared in step (1), carry out high-speed shearing and ultrasonic oscillation, and then carry out high-speed grinding and low-temperature controlled dispersion to obtain a catalyst solution; (4) Take a carbon nanotube solution, a carbon black solution, a polytetrafluoroethylene solution, a mixture solution of carbon nanotubes and carbon black, or a mixture solution of carbon nanotubes, carbon black and polytetrafluoroethylene, mix it with the catalyst solution, and carry out high-speed shearing and ultrasonic oscillation to obtain a cathode catalyst layer slurry; (5) The cathode catalyst layer slurry is coated with fluorine on one side of the polytetrafluoroethylene substrate by an extrusion coating process, and the loading of the cathode catalyst layer is controlled at 0.05 - 0.07 mg / cm 2 , and the coated cathode catalyst layer is baked at 30 - 120 °C for 5 - 30 minutes to obtain the cathode catalyst layer; (6) Add a platinum catalyst to the ionomer dispersion prepared in step (1), carry out high-speed shearing and ultrasonic oscillation, and then carry out sufficient grinding and mixing to obtain an anode catalyst layer slurry; (7) The anode catalyst layer slurry is coated with fluorine on one side of the polytetrafluoroethylene substrate by an extrusion coating process, and the loading of the anode catalyst layer is controlled at 0.01 - 0.03 mg / cm 2 , and the coated anode catalyst layer is baked at 30 - 120 °C for 2 - 30 minutes to obtain the anode catalyst layer; (8) Attach the cathode catalyst layer and the anode catalyst layer to both sides of the proton exchange membrane by thermal transfer printing to obtain a three-in-one membrane electrode; (9) Cut two gas diffusion layers and respectively bond them to the corresponding sides of the three-in-one membrane electrode prepared in step (8), and then perform edge sealing treatment to obtain a membrane electrode with a low loading of 0.05-0.1 mg / cm 2 of the cathode catalyst layer containing the additive.

2. The preparation method according to claim 1, characterized in that: In step (1), the perfluorosulfonic acid ionomer uses a perfluorosulfonic acid ionomer stock solution; the mass fraction of the perfluorosulfonic acid ionomer is 20%-50%, the dispersion time is 60-500 minutes; the dispersion method is at least one of mechanical stirring or magnetic stirring, and the stirring speed is 5000-30000 rpm; the mass fraction of the ionomer dispersion is 4%-20%.

3. The preparation method according to claim 1, characterized in that: In step (1), the volatile solvent is one or more of distilled water, ethanol or isopropanol, and the mass ratio of distilled water to ethanol or / and isopropanol is (2-10):

1.

4. The preparation method according to claim 1, characterized in that: In step (2), magnetic stirring is used for high-speed shearing, the high-speed shearing rate is 8000-20000 rpm, and the high-speed shearing time is 30-100 minutes; the ultrasonic frequency is 5-10 mHz, and the ultrasonic time is 30-120 minutes; the solid content of the carbon nanotube solution, the carbon black solution or the mixture solution of carbon nanotubes and carbon black is 3%-30%.

5. The preparation method according to claim 1, characterized in that: In step (3), the Pt content of the platinum catalyst used is 50%-60% Pt / C; magnetic stirring is used for high-speed shearing, the shearing rate is 8000-30000 rpm, and the high-speed shearing time is 100-200 minutes; the ultrasonic frequency is 5-20 mHz, and the ultrasonic time is 100-200 minutes; the rotation speed of grinding and dispersion is 2000-3000 rpm, and the grinding time is 100-200 minutes; the temperature during the dispersion process is controlled at 0-10°C; the solid content of the catalyst solution is 5%-15%.

6. The preparation method according to claim 1, characterized in that: In step (4), magnetic stirring is used for high-speed shearing, the shearing rate is 8000 - 20000 rpm, and the high-speed shearing time is 30 - 300 minutes; the ultrasonic frequency is 5 - 20 mHz, and the ultrasonic time is 30 - 120 minutes.

7. The preparation method according to claim 1, characterized in that: In step (6), the Pt content of the platinum catalyst is 30% - 50%; magnetic stirring is used for high-speed shearing, the shearing rate is 8000 - 30000 rpm, and the high-speed shearing time is 100 - 200 minutes; the ultrasonic frequency is 5 - 20 mHz, and the ultrasonic time is 100 - 200 minutes; the rotation speed for grinding and dispersion is 2000 - 3000 rpm, and the grinding time is 100 - 200 minutes; the temperature during the dispersion process is controlled at 0 - 10 °C.

8. The preparation method according to claim 1, characterized in that: In step (8), the thickness of the proton exchange membrane is 8 - 12 μm; the hot embossing temperature is 100 - 200 °C; the hot embossing pressure is 150 - 300 kPa; the hot embossing time is 200 - 400 minutes.

9. A low-platinum membrane electrode assembly for a proton exchange membrane fuel cell, characterized in that: Prepared by the method for preparing a low-platinum membrane electrode of a proton exchange membrane fuel cell according to any one of claims 1 to 8.

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