Preparation method of low-platinum gradient fiber arrangement catalyst layer for fuel cell cathode
The low-platinum gradient fiber arrangement catalytic layer was prepared through electrospinning technology, which solved the problem of poor performance of the cathode catalytic layer of the fuel cell under low platinum load, and achieved higher fuel cell performance and durability.
Patent Information
- Application Number
- CN202510194033.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-21
- Publication Date
- 2025-05-23
AI Technical Summary
In the existing proton exchange membrane fuel cells, the cathode catalytic layer under low platinum load has problems such as large oxygen transmission resistance, low platinum utilization rate, and poor durability, resulting in poor fuel cell performance.
Electrospinning technology is used to prepare a low-platinum gradient fiber arrangement catalytic layer. By adjusting the catalyst density and the gradient of pore structure, the water management capacity and oxygen transmission efficiency of the catalytic layer are improved.
The catalytic layer performance under low platinum load is significantly improved, the peak power density and durability of the fuel cell are improved, and oxygen transmission resistance and mass transfer loss are reduced.
Smart Images
Figure CN120033252A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of electrochemical fuel cells, and in particular relates to a method for preparing a gradient fiber arrangement catalytic layer for a fuel cell cathode. Background Art
[0002] Proton exchange membrane fuel cell (PEMFC) is an energy conversion device that directly converts chemical energy in fuel into electrical energy. It has significant advantages such as high efficiency, no pollution, no noise, and low operating temperature. Proton exchange membrane fuel cells are generally composed of current collectors, flow field plates, and membrane electrodes. Among them, the membrane electrode, as the core component of proton exchange membrane fuel cells, is the key to affecting battery output performance and reducing costs. The membrane electrode is usually a seven-in-one symmetrical structure consisting of anode and cathode gas diffusion layers, cathode and cathode microporous layers, cathode and cathode catalyst layers, and proton exchange membranes. The catalyst layer is composed of a catalyst, a catalyst carrier, and an ionomer, and is a core component of the fuel cell. The catalyst used in the catalyst layer is mainly the precious metal platinum, which has a high cost and due to the slow oxygen reduction reaction at the cathode, its loading in the fuel cell remains high. Therefore, reducing the platinum loading, especially reducing the platinum loading of the cathode catalyst layer, has always been the focus of fuel cell research and development.
[0003] At present, in proton exchange membrane fuel cells, the catalyst layer is generally a particle stacking type, mainly composed of catalysts and ionomers. When the platinum loading, especially the cathode platinum loading, is low, the fuel cell will face problems such as large oxygen transmission resistance, low platinum utilization, and poor durability. Therefore, improving the performance of the catalyst layer under low platinum loading is of great significance to improving the performance of low-platinum fuel cells, reducing fuel cell costs, and promoting the commercialization of fuel cells. Summary of the invention
[0004] The purpose of the present invention is to propose a method for preparing a low-platinum gradient fiber-arranged catalyst layer for a fuel cell cathode, by optimizing the cathode catalyst layer preparation process, improving the material transport within the cathode catalyst layer, improving the platinum utilization rate and the output performance of the catalyst layer, so as to improve the poor performance of proton exchange membrane fuel cells at low platinum loadings and effectively reduce the cost of fuel cells.
[0005] The present invention focuses on the microstructure of the catalyst layer of a proton exchange membrane fuel cell, and provides an important method for improving the performance of low-platinum fuel cells and reducing the cost of fuel cells by optimizing the structure and preparation process of the cathode catalyst layer.
[0006] The technical principle and structural scheme of the present invention are described below:
[0007] The method for preparing a low-platinum gradient fiber-arranged catalyst layer for a fuel cell cathode is centered on a proton exchange membrane, and an anode catalyst layer and a cathode catalyst layer are coated on both sides respectively. The proton exchange membrane, the cathode catalyst layer, the cathode microporous layer, and the cathode gas diffusion layer together constitute the fuel cell membrane electrode. The anode catalyst layer is prepared by ultrasonic spraying, or slit coating, or electrostatic spraying, or electrochemical deposition. The cathode catalyst layer adopts a low-platinum gradient fiber-arranged catalyst layer prepared based on electrospinning technology, and the catalyst density of the cathode catalyst layer gradually decreases and the pores gradually increase from the inside (close to the proton exchange membrane side) to the outside.
[0008] The specific steps of the method for preparing a low platinum gradient fiber arrangement catalyst layer for a fuel cell cathode are as follows:
[0009] (1) Preparation of slurry
[0010] Take the polymer and dissolve it in isopropanol solvent for later use. Weigh the catalyst with a balance, pour it into a reagent bottle, place the reagent bottle on the balance and weigh it and remove the weight of the bottle, add pure water to wet the catalyst and weigh it again and remove the weight of the bottle. Add the ionomer dispersion drop by drop, mix it with the prepared polymer solution, and homogenize the mixed solution at low temperature.
[0011] (2) Preparation of cathode catalyst layer based on electrospinning
[0012] The injector is loaded with the slurry prepared in step (1), and the slurry is sprayed onto the drum collector through the nozzle at the front end of the injector, and voltage is applied to the injector and the collector respectively, and the slurry is received by the proton exchange membrane. The electrostatic spinning is performed by setting and adjusting the feed rate, voltage, distance between the injector and the collector, ambient humidity, horizontal swing speed of the injector and rotation speed of the collector. According to the set platinum loading ratio, the horizontal swing speed of the injector and the rotation speed of the collector drum are adjusted, and the rotation speed of the collector is gradually reduced from the inside (close to the proton exchange membrane side) to the outside, and the horizontal swing speed of the injector is gradually increased, and the cathode catalyst layer is prepared layer by layer.
[0013] (3) Drying
[0014] The proton exchange membrane, on both sides of which are respectively coated with a cathode catalyst layer prepared by electrostatic spinning and an anode catalyst layer prepared by the ultrasonic spraying method, is dried to remove impurities and moisture.
[0015] (4) Membrane electrode assembly
[0016] The proton exchange membrane, the cathode catalyst layer prepared by electrostatic spinning and the anode catalyst layer prepared by ultrasonic spraying are respectively coated on both sides, the anode microporous layer and the cathode gas diffusion layer are stacked and combined into one.
[0017] The characteristics and benefits of the present invention are that the cathode catalyst layer with low platinum gradient fiber arrangement significantly improves the problems of poor water management, slow oxygen transfer and poor durability faced by the catalyst layer at low platinum loading compared with the conventional cathode catalyst layer. On the one hand, the developed pore structure and the gradient of pore and catalyst density prepared by adjusting the receiving speed enable it to show good water management ability and significantly reduce oxygen transfer resistance and mass transfer loss. The peak power density of the electrospun membrane electrode assembled with the gradient fiber arrangement catalyst layer reached 1.0189W cm -2 , while the peak power density of conventional membrane electrode assembled with conventional cathode catalyst layer is only 0.8702W cm -2 , increased by 17%, and the cathode platinum loading dropped to 0.098 g Pt kW -1 On the other hand, due to the effect of electrostatic force, the distribution of catalysts and ionomers is more uniform, which makes the catalyst layer have significant advantages in durability. After 5000 square wave voltage durability cycles, the peak power density of the electrospun membrane electrode assembled with gradient fiber arrangement catalyst layer only decreased by 11%, while the peak power density of the conventional membrane electrode assembled with conventional cathode catalyst layer decreased by 17%. This shows that the electrospun membrane electrode has better durability, which helps to guide the improvement of the performance of proton exchange membrane fuel cells at low platinum loading, and is of great significance for promoting the cost reduction and commercialization of proton exchange membrane fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Attached Figure 1 Schematic diagram of the principle structure of the electrospun membrane electrode of a proton exchange membrane fuel cell with a low platinum gradient fiber-arranged catalytic layer as the cathode.
[0019] Attached Figure 2-1 This is a two-dimensional image of a conventional catalyst layer taken using a focused ion beam scanning electron microscope.
[0020] Attached Figure 2-2 This is a two-dimensional image of the gradient fiber arrangement catalytic layer taken using a focused ion beam scanning electron microscope.
[0021] Attached Figure 3-1 A 3D image of a conventional catalyst layer taken using computed tomography.
[0022] Attached Figure 3-2 A three-dimensional image of a gradient fiber-arranged catalytic layer taken using computed tomography.
[0023] Attached Figure 4 The figure is a performance comparison diagram of two embodiments of the electrospinning membrane electrode of the present invention and a conventional membrane electrode.
[0024] Attached Figure 5The figure is a performance comparison diagram of two embodiments of the electrospun membrane electrode of the present invention and the conventional membrane electrode before and after decay. DETAILED DESCRIPTION
[0025] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that this embodiment is descriptive rather than restrictive, and does not limit the protection scope of the present invention.
[0026] A method for preparing a low-platinum gradient fiber-arranged catalyst layer for a fuel cell cathode has a principle structure as follows: the cathode catalyst layer adopts a low-platinum gradient fiber-arranged catalyst layer prepared based on electrospinning technology, and the catalyst density of the cathode catalyst layer gradually decreases and the pores gradually increase from the inside (close to the proton exchange membrane side) to the outside.
[0027] The specific steps of the method for preparing a low platinum gradient fiber arrangement catalyst layer for a fuel cell cathode are as follows:
[0028] (1) Preparation of slurry
[0029] Dissolve the polymer in isopropanol solvent for later use. Weigh the catalyst on a scale, pour it into a reagent bottle, place the reagent bottle on a scale and weigh it, subtract the weight of the bottle, add pure water to wet the catalyst and weigh it again, subtract the weight of the bottle. Add the ionomer dispersion drop by drop, mix it with the prepared polymer solution, and homogenize the mixed solution at low temperature.
[0030] (2) Preparation of cathode catalyst layer based on electrospinning
[0031] The injector is loaded with the slurry prepared in step (1), and the slurry is sprayed onto a drum collector (the drum collector is referred to as the collector, the same below) through a nozzle at the front end of the injector, and voltage is applied to the injector and the collector respectively, and the proton exchange membrane is used to receive the slurry. Electrospinning is performed by setting and adjusting the feed rate, voltage, the distance between the injector and the collector, the ambient humidity, the horizontal swing speed of the injector, and the rotation speed of the collector. According to the set platinum loading ratio, the horizontal swing speed of the injector and the rotation speed of the collector drum are adjusted, and the rotation speed of the collector is gradually reduced from the inside (close to the proton exchange membrane side) to the outside, and the horizontal swing speed of the injector is gradually increased, and the cathode catalyst layer is prepared layer by layer.
[0032] (3) Drying
[0033] The proton exchange membrane, on both sides of which are respectively coated with a cathode catalyst layer prepared by electrostatic spinning and an anode catalyst layer prepared by the ultrasonic spraying method, is dried to remove impurities and moisture.
[0034] (4) Membrane electrode assembly
[0035] The proton exchange membrane, the cathode catalyst layer prepared by electrostatic spinning and the anode catalyst layer prepared by ultrasonic spraying are respectively coated on both sides, the anode microporous layer and the cathode gas diffusion layer are stacked and combined into one.
[0036] The high molecular polymer in step (1) is polyacrylonitrile, polyethylene oxide, polyacrylic acid, polyvinyl alcohol, or a combination of the above high molecular polymers.
[0037] The catalyst in step (1) is a platinum-carbon catalyst, a platinum-iron-carbon catalyst, a platinum-cobalt-carbon catalyst, a platinum-palladium-carbon catalyst, a platinum-nickel-carbon catalyst, or a combination of the above catalysts. The ionomer dispersion is a Nafion solution with a concentration of 5% to 25%. The solvent used to disperse the high molecular polymer is isopropanol or anhydrous ethanol. The low temperature is 10-15° C., and the homogenization method adopts ultrasonic vibration or magnetic stirring.
[0038] The distance between the nozzle of the injector and the collector is 10-15 cm. The feed rate in step (2) is 0.5-1 ml h -1 . A voltage of 8 to 14 kV is applied to the nozzle, and a voltage of 1 to 5 kV is applied to the drum collector. The ambient humidity is controlled at 25 to 35% by adjusting the temperature. The platinum loading ratio of the cathode catalyst layer gradually increases from the inside (close to the proton exchange membrane side) to the outside layers, and the receiving speed of the cathode catalyst layer from the inside (close to the proton exchange membrane side) to the outside layers gradually decreases from 3000 rpm to 50 rpm; the horizontal swing speed of the nozzle of the cathode catalyst layer from the inside (close to the proton exchange membrane side) to the outside layers is increased from 1 mms -1 Incremental up to 30 mm s -1 .
[0039] The drying method in step (3) is vacuum drying or air drying. Specific embodiment 1:
[0041] (1) Preparation of conventional slurry
[0042] Weigh 40% of the platinum-carbon catalyst using a 1 / 100,000 (accuracy) analytical balance, place it in a 100 ml centrifuge tube, place the centrifuge tube on the balance and remove the tare. Use a rubber-tipped dropper to drip a small amount of pure water to wet the catalyst, and place it on the balance again to remove the tare. Use a rubber-tipped dropper to drop 5% Nafion solution and analytical grade isopropanol (the ratio of Nafion to carbon in the catalyst is 0.6, and the ratio of alcohol to water is 9), then seal the centrifuge tube and place it in a low-temperature water bath at 10°C and ultrasonically vibrate at a frequency of 57kHz for 30 minutes. Take out the centrifuge tube, use an emulsifier to shear at a low temperature of 10°C at a speed of 15,000 rpm for 45 minutes, and shear at a speed of 3,000 rpm before use.
[0043] (2) Preparation of catalytic layer based on conventional methods
[0044] The comparative example uses the conventional slurry prepared above to prepare a conventional catalyst layer using an ultrasonic spraying method. The exhaust is turned on to maintain negative pressure in the ultrasonic sprayer, and then the equipment and the control host are turned on, the ultrasonic spraying power is set to 3W, and the nozzle height is set to 7cm. A 99.99% high-purity nitrogen gas flow is used at the nozzle outlet to restrain the slurry, and the nitrogen flow rate is set to 1.8SLPM. The spraying path is changed to a serpentine path through the program, and the spraying area is adjusted to an area of 64cm 2 The cutting area is 36cm 2 Place the proton exchange membrane on a heating table at 70°C or above and start vacuum adsorption to fix the proton exchange membrane. Then take 25 ml of the conventional slurry prepared above and place it in the injector. Adjust the injection speed of the injection pump to 0.15 ml min. -1 Spraying is performed according to the set nitrogen flow rate, ultrasonic power, etc. After one spraying cycle (the nozzle starts from the starting point and returns to the starting point according to the set serpentine path, which is considered a cycle), the platinum loading of one cycle is calibrated using an X-ray fluorescence spectrometer (precisely calibrated by an inductively coupled plasma emission spectrometer). Then the number of cycles required to reach the target platinum loading is determined, and finally a catalyst layer with the target platinum loading is obtained.
[0045] (3) Membrane electrode assembly
[0046] The conventional membrane electrode is composed of a proton exchange membrane, anode and cathode catalyst layers prepared by conventional methods, cathode and cathode microporous layers, and cathode and cathode gas diffusion layers. The proton exchange membrane fuel cell is assembled using a polytetrafluoroethylene gasket with an 80% compression rate of the diffusion layer and a torque of 5 N m. Specific embodiment 2:
[0048] The specific preparation steps of the electrospun membrane electrode (the present invention) assembled with a gradient fiber arrangement cathode catalyst layer are as follows:
[0049] (1) Slurry preparation
[0050] Use a one-hundred-thousandth (precision) analytical balance to weigh polyacrylic acid with a molecular weight of 450,000, dissolve it in analytical grade isopropanol, use a magnetic stirrer to stir at a speed of 500rpm for 12 hours, and set aside. Then use a balance to weigh 40% platinum carbon catalyst and pour it into a reagent bottle. Place the reagent bottle on a balance to remove the tare, then add a small amount of pure water dropwise to wet the catalyst, and then remove the tare on the balance again. Add 5% Nafion dispersion dropwise (the ratio of Nafion to carbon in the catalyst is 0.6), and then seal the reagent bottle. Place it in a low-temperature water bath at 10°C and ultrasonically vibrate at a frequency of 57kHz for 30 minutes, then use a magnetic stirrer to stir at a speed of 500rpm for 10 minutes, alternately three times. Add the previously prepared polyacrylic acid solution according to the mass ratio of alcohol water to 2 (alcohol water refers to a mixture of isopropanol and pure water), finally seal the reagent bottle, and use a magnetic stirrer to stir at a speed of 500rpm for 48 hours.
[0051] (2) Preparation of cathode catalyst layer
[0052] Electrospinning technology was used to prepare the cathode catalyst layer with low platinum gradient fiber arrangement. The cathode catalyst layer was prepared using the slurry prepared in the previous step (slurry preparation). The exhaust was turned on to maintain negative pressure in the electrospinning machine, and the humidity in the electrospinning machine was adjusted to 30%. The slurry was loaded using a 5ml injector, the inner diameter of the nozzle was 0.4mm, and the material was stainless steel. The proton exchange membrane was placed on a cylindrical drum collector, and the distance between the nozzle and the collector was adjusted to 11cm. A high voltage of 12kV was applied to the nozzle, and a voltage of 2kV was applied to the drum at a rate of 1ml h -1 Electrospinning was started at a pushing speed of . During this period, three catalytic layers were prepared layer by layer on the proton exchange membrane. The platinum loading ratio of the three layers was 1:2:3, and the drum speed was reduced from 3000 rpm to 50 rpm. The injector moving speed was increased from 1 mm s -1 Incremental up to 30 mm s -1 During the calibration, the platinum loading of the injector after a certain distance was calibrated using an X-ray fluorescence spectrometer (precisely calibrated by an inductively coupled plasma emission spectrometer), and then the required injection distance to reach the target platinum loading was determined, and finally the platinum loading was 0.1 mg. Pt cm -2 cathode catalyst layer.
[0053] (3) Drying
[0054] The proton exchange membrane coated with a conventional anode catalyst layer and a cathode catalyst layer with a gradient fiber arrangement is dried to thoroughly remove impurities and moisture. The drying method used in this embodiment is to place the proton exchange membrane coated with the anode and cathode catalyst layers in a muffle furnace, heat it to 110 °C at a heating rate of 3 °C per minute in an air atmosphere, hold for 1 hour, then naturally cool to room temperature, and then place it in a vacuum drying oven at 60 °C for 6 hours to thoroughly remove impurities and moisture.
[0055] (4) Membrane electrode assembly
[0056] The electrospun membrane electrode consists of a proton exchange membrane, an anode catalyst layer prepared by a conventional method, a cathode catalyst layer with a gradient fiber arrangement, anode and cathode microporous layers, and anode and cathode gas diffusion layers. The proton exchange membrane fuel cell is assembled using a polytetrafluoroethylene gasket at a diffusion layer compression rate of 80% with a torque of 5 N m.
[0057] In the embodiment of the present invention, two groups of controls are set up in the experiment of the cathode catalyst layer. After assembling into a membrane electrode, they are respectively called a conventional membrane electrode and an electrospun membrane electrode. The anode uses a catalyst layer with a platinum loading of 0.05 mg Pt cm -2 prepared by a conventional method. The conventional membrane electrode uses a conventional cathode catalyst layer, and the electrospun membrane electrode uses a cathode catalyst layer with a gradient fiber arrangement, with a platinum loading of 0.1 mg Pt cm -2 . The two-dimensional and three-dimensional morphologies of the two cathodes are compared as Figure 2-1 、 2-2 and Figure 3-1 、 3-2 shown, and the performance comparison is as Figure 4 and Figure 5 shown.
[0058] Figure 2-1 、 2-2 respectively give the two-dimensional images of two embodiments of the conventional catalyst layer and the catalyst layer with a gradient fiber arrangement taken by a focused ion beam scanning electron microscope. It can be seen from the figure that the conventional catalyst layer is mainly composed of stacked catalyst particles, while the fiber arrangement catalyst layer is composed of overlapping fibers and has a more developed pore structure, which is more conducive to mass transfer.
[0059] Figure 3-1 、 3-2The three-dimensional images of two embodiments, a conventional catalyst layer and a gradient fiber arrangement catalyst layer, taken using computer tomography, are respectively given. It can be seen from the figure that the conventional catalyst layer is mainly composed of catalyst particles, with small pores and a uniform pore structure, while the gradient fiber arrangement catalyst layer is composed of overlapping fibers, with larger pores and a characteristic of gradually decreasing catalyst density and gradually increasing pores from the proton exchange membrane side to the outside. Therefore, it has a more reasonable catalyst distribution and a more developed pore structure.
[0060] Figure 4 The performance comparison diagram of the conventional membrane electrode and the electrospun membrane electrode of the embodiment of the present invention is given. The highest power density of the electrospun membrane electrode reached 1.0189W cm -2 , while the maximum power density of conventional membrane electrodes is only 0.8702Wcm -2 , which is about 17% higher than the original. This is due to the cathode catalyst layer being prepared by electrospinning, a more developed pore structure, and a gradient of pore and catalyst density prepared by adjusting the receiving rotation speed. This catalyst layer has optimized impedance, exhibits excellent water management capabilities, and significantly reduces oxygen transmission resistance and mass transfer losses.
[0061] Figure 5 The performance comparison diagram of the conventional membrane electrode and the electrospun membrane electrode before and after the decay of the embodiment of the present invention is given. It can be seen from the figure that the peak power density of the electrospun membrane electrode decays by 11%, while the peak power density of the conventional membrane electrode decays by 17%. The electrospun membrane electrode has better durability, mainly due to the effect of electrostatic force, and the distribution of catalyst and ionomer is more uniform. This is of great significance for promoting the cost reduction and commercialization of proton exchange membrane fuel cells.
Claims
1. A method for preparing a low-platinum gradient fiber arrangement catalyst layer for a fuel cell cathode, with a proton exchange membrane as the center, and an anode catalyst layer and a cathode catalyst layer coated on both sides respectively, the proton exchange membrane coated with the anode and cathode catalyst layers and the anode and cathode microporous layers and the anode and cathode gas diffusion layers together form a fuel cell membrane electrode, the anode catalyst layer is prepared by ultrasonic spraying, or slit coating, or electrostatic spraying, or electrochemical deposition, and is characterized by: The cathode catalyst layer is arranged using low-platinum gradient fibers prepared based on electrospinning technology, and the catalyst density of the cathode catalyst layer gradually decreases and the pores gradually increase from the side close to the proton exchange membrane to the outside.
2. The method for preparing a low platinum gradient fiber arrangement catalyst layer for a fuel cell cathode according to claim 1, characterized in that: The specific steps are as follows: (1) Preparation of slurry Take the polymer and dissolve it in isopropanol solvent for later use. Weigh the catalyst with a balance, pour it into a reagent bottle, put the reagent bottle on the balance to weigh and remove the weight of the bottle, add pure water to wet the catalyst and weigh it again and remove the weight of the bottle, add the ionomer dispersion drop by drop, mix it with the prepared polymer solution, and homogenize the mixed solution at low temperature; (2) Preparation of cathode catalyst layer based on electrospinning The injector is loaded with the slurry prepared as in step (1), and the slurry is sprayed onto the drum collector through the nozzle at the front end of the injector, and voltage is applied to the injector and the drum collector respectively, and the proton exchange membrane is used to receive the slurry. The electrostatic spinning is performed by adjusting the feed rate, voltage, distance between the injector and the collector, ambient humidity, horizontal swing speed of the injector, and rotation speed of the drum collector. According to the set platinum loading ratio, the horizontal swing speed of the injector and the rotation speed of the collector drum are adjusted, and the rotation speed of the drum collector is gradually reduced from the side close to the proton exchange membrane to the outside, and the horizontal swing speed of the injector is gradually increased, and the cathode catalyst layer is prepared layer by layer; (3) Drying Drying the proton exchange membrane on both sides of which are coated with a cathode catalyst layer prepared by electrospinning and an anode catalyst layer prepared by the ultrasonic spraying method to remove impurities and moisture; (4) Membrane electrode assembly The proton exchange membrane, the cathode catalyst layer prepared by electrostatic spinning and the anode catalyst layer prepared by ultrasonic spraying are respectively coated on both sides, the anode microporous layer and the cathode gas diffusion layer are stacked and combined into one.
3. The method for preparing a low platinum gradient fiber arrangement catalyst layer for a fuel cell cathode according to claim 1 or 2, characterized in that: The high molecular polymer in step (1) is polyacrylonitrile, polyethylene oxide, polyacrylic acid, polyvinyl alcohol, or a combination of the above high molecular polymers.
4. The method for preparing a low-platinum gradient fiber arrangement catalyst layer for a fuel cell cathode according to claim 1 or 2, characterized in that: The catalyst in step (1) is a platinum-carbon catalyst, or a platinum-iron-carbon catalyst, or a platinum-cobalt-carbon catalyst, or a platinum-palladium-carbon catalyst, or a platinum-nickel-carbon catalyst, or a combination of the above catalysts; the ionomer dispersion is a Nafion solution with a concentration of 5% to 25%; the solvent used to disperse the high molecular polymer is isopropanol or anhydrous ethanol; the low temperature is 10-15°C, and the homogenization method adopts ultrasonic vibration or magnetic stirring.
5. The method for preparing a low platinum gradient fiber arrangement catalyst layer for a fuel cell cathode according to claim 2, characterized in that: The distance between the injector nozzle and the drum collector is 10-15 cm, and the feed rate in step (2) is 0.5-1 ml h -1 , a voltage of 8 to 14 kV is applied to the nozzle, a voltage of 1 to 5 kV is applied to the drum collector, the ambient humidity is controlled at 25 to 35% by adjusting the temperature, the platinum loading ratio of the cathode catalyst layer gradually increases from the side close to the proton exchange membrane to the outer layers, the receiving speed of the cathode catalyst layer from the inner side to the outer layers is gradually reduced from 3000 rpm to 50 rpm, and the horizontal swing speed of the nozzle of the cathode catalyst layer from the inner side to the outer layers is increased from 1 mm s -1 Incremental up to 30 mm s -1 .
6. The method for preparing a low platinum gradient fiber arrangement catalyst layer for a fuel cell cathode according to claim 2, characterized in that: The drying method in step (3) is vacuum drying or air drying.