Catalytic layer of fuel cell, preparation method and application thereof

Abstract

The present application belongs to the field of fuel cell technology, and specifically discloses a fuel cell catalyst layer, a preparation method and an application thereof, wherein the catalyst layer includes multiple cathode catalyst layers and multiple anode catalyst layers; any of the anode catalyst layers and the cathode catalyst layer respectively include Pt / C catalyst, deionized water, PEDOT:PFSA solution, high-dielectric small molecule alcohol, nano rare earth metal oxide and pore-forming agent; the content of the pore-forming agent in the anode catalyst layer and the cathode catalyst layer respectively decreases in a gradient from near to far from the proton exchange membrane, thereby solving the current technical problems of low conductivity and severe ohmic polarization of the fuel cell catalyst layer, which lead to reduced fuel cell performance; the present invention also provides a method for preparing the catalyst layer of a fuel cell, which is simple to operate, does not require complex equipment or instruments, and is convenient for operators to implement.

Description

Technical Field

[0001] The present application belongs to the field of fuel cell technology, and specifically relates to a catalytic layer of a fuel cell, a preparation method and its application. Background Art

[0002] Due to the massive emission of greenhouse gases, global warming continues, and climate change is becoming increasingly serious. Currently, more and more companies are replacing traditional fossil fuels with low-carbon, clean, renewable energy. Among the many clean energy sources, hydrogen offers advantages such as cleanliness, high energy density per unit mass, and reproducibility. Many countries consider it the ultimate clean energy solution. Among the various hydrogen energy applications, proton exchange membrane fuel cells (PEMFCs) are currently trending due to their fast response time and high energy conversion efficiency. Conventional membrane electrode materials typically use perfluorosulfonic acid resin as a binder and provide proton transfer sites. However, the amount of perfluorosulfonic acid resin added to the catalyst layer significantly affects the efficiency of proton and electron transfer within the catalyst layer. Too little perfluorosulfonic acid resin provides insufficient proton transfer sites, resulting in a reduction in the three-phase interface area and decreased catalytic activity. Too much perfluorosulfonic acid resin, due to its extremely low electrical conductivity, hinders electron transfer within the catalyst layer, increasing the electrode's ohmic impedance and severely impacting fuel cell performance. Furthermore, during operation, high currents and high reaction rates can lead to flooding of the catalyst layer, hindering oxygen transfer and significantly reducing fuel cell performance. Summary of the Invention

[0003] The problem that this application aims to solve is to provide a fuel cell catalyst layer, a preparation method and its application, which solves the current technical problems of low conductivity and severe ohmic polarization of the fuel cell catalyst layer, which lead to reduced fuel cell performance.

[0004] In order to solve the above technical problems, this application adopts the following technical solutions:

[0005] In one aspect, the present invention provides a catalyst layer for a fuel cell, comprising a plurality of cathode catalyst layers and a plurality of anode catalyst layers; each of the anode catalyst layer and the cathode catalyst layer comprises a Pt / C catalyst, deionized water, a PEDOT:PFSA solution, a high dielectric small molecule alcohol, a nano rare earth metal oxide, and a pore-forming agent; the content of the pore-forming agent in the anode catalyst layer and the cathode catalyst layer decreases gradually from near to far from the proton exchange membrane; the PEDOT:PFSA solution comprises 3,4-ethylhexane; Ethylenedioxythiophene, perfluorosulfonic acid resin, deionized water, oxidant, high dielectric small molecule alcohol, the mass ratio of 3,4-ethylenedioxythiophene to perfluorosulfonic acid resin is 1:(1-4), the mass ratio of the mixture of 3,4-ethylenedioxythiophene and perfluorosulfonic acid resin to the oxidant is 1:(1.5-2), the mass ratio of the mixture of 3,4-ethylenedioxythiophene and perfluorosulfonic acid resin to deionized water is 1:(4.5-6), and the mass ratio of deionized water to high dielectric small molecule alcohol is (1-2):1.

[0006] The oxidant can be anhydrous ferric chloride; the monomer EDOT is oxidatively polymerized on the PFSA substrate to form a PEDOT:PFSA conductive polymer solution.

[0007] In some embodiments, in the anode catalyst layer, the solid-liquid mass ratio is 1-5%; wherein the mass ratio of deionized water to high dielectric small molecule alcohol is 1:(1-4), the pore-forming agent content is 1%-3% of the mass of the Pt / C catalyst, the mass of the nano rare earth metal oxide is 1%-5% of the mass of the Pt / C catalyst, the mass of the ionomer in the PEDOT:PFSA solution is 30%-80% of the mass of the carbon in the Pt / C catalyst, and the Pt loading is 0.1-0.3 mg / cm 2 .

[0008] In some embodiments, in the cathode catalyst layer, the solid-liquid mass ratio is 1-5%; wherein the mass ratio of deionized water to high dielectric small molecule alcohol is 1:(1-4), the pore-forming agent content is 1%-3% of the mass of the Pt / C catalyst, the mass of the nano rare earth metal oxide is 1%-5% of the mass of the Pt / C catalyst, the mass of the ionomer in the PEDOT:PFSA solution is 30%-80% of the mass of the carbon in the Pt / C catalyst, and the Pt loading is 0.3-0.7 mg / cm 2 .

[0009] In some embodiments, the anode catalyst layer and the cathode catalyst layer closest to the proton exchange membrane also include a hydrophobic substance, and the amount of the hydrophobic substance added is 0.5%-2% of the mass of the Pt / C catalyst. The hydrophobic substance includes at least one of polyvinylidene fluoride and polytetrafluoroethylene.

[0010] In some embodiments, the anode catalyst layer and the cathode catalyst layer farthest from the proton exchange membrane also include a hydrophilic substance, and the amount of the hydrophilic substance added is 0.5%-2% of the mass of the Pt / C catalyst. The hydrophilic substance includes at least one of styrene-butadiene rubber, silica, and polyethylene glycol.

[0011] In some embodiments, the high dielectric small molecule alcohol includes at least one of ethanol, ethylene glycol, n-propanol, and isopropanol.

[0012] In some embodiments, the pore forming agent comprises at least one of ammonium bicarbonate, ammonium carbonate, and ammonium oxalate.

[0013] In some embodiments, the nano rare earth metal oxide includes at least one of cerium oxide and zirconium oxide, and the particle size of the nano rare earth metal oxide is 20-40 nm.

[0014] In one aspect, the present invention provides a use of the above-mentioned fuel cell catalyst layer in preparing MEA of a fuel cell.

[0015] On the one hand, the present invention provides a method for preparing the catalyst layer of the above-mentioned fuel cell, comprising the following steps: S1, mixing 3,4-ethylenedioxythiophene, perfluorosulfonic acid resin, and deionized water to obtain an emulsion, adding an oxidant to the emulsion for oxidation, removing impurities, and then centrifuging, and dispersing with a high-dielectric small molecule alcohol after centrifugation to obtain a PEDOT:PFSA solution; S2, mixing a Pt / C catalyst, deionized water, a PEDOT:PFSA solution, a high-dielectric small molecule alcohol, a nano rare earth metal oxide, and a pore-forming agent, and then preparing them in descending order of the pore-forming agent content on one side of a proton exchange membrane to obtain a multilayer anode catalyst layer, wherein the thickness of each anode catalyst layer is 1-5 μm; S3, mixing a Pt / C catalyst, deionized water, a PEDOT:PFSA solution, a high-dielectric small molecule alcohol, a nano rare earth metal oxide, and a pore-forming agent, and then preparing them in descending order of the pore-forming agent content on the other side of the proton exchange membrane to obtain a multilayer cathode catalyst layer, wherein the thickness of each cathode catalyst layer is 1-5 μm.

[0016] In S1, the mixing time for obtaining the emulsion is approximately 2 hours, the oxidation time for adding the oxidant is approximately 24 hours, and the dispersion time for adding the high-dielectric small molecule alcohol is approximately 2 hours. Impurities are removed by filtration through a semipermeable membrane. The anode catalyst layer or cathode catalyst layer is sequentially prepared on both sides of the proton exchange membrane by spraying, screen printing, casting, or transfer printing. The raw materials in the cathode catalyst layer or anode catalyst layer are mixed by at least one of ultrasonication, high-speed shearing, ball milling, and high-pressure homogenization.

[0017] This application has the following beneficial effects:

[0018] 1. The membrane electrode with a gradient pore structure catalyst layer in this application is better than the membrane electrode with a traditional catalyst layer:

[0019] (1) It is more conducive to the discharge of water and avoids membrane swelling;

[0020] (2) It helps the gas reach the three-phase interface more smoothly, thereby improving the electrochemical performance;

[0021] (3) The voltage drop in the activation polarization region is smaller, resulting in more superior ORR kinetics.

[0022] 2. Nano-rare earth metal oxides have a high thermodynamic affinity for oxygen and possess excellent catalytic properties. Using nano-rare earth metal oxides can effectively improve electrical conductivity, significantly enhance ORR activity, and significantly reduce H2O2 generation.

[0023] 3. Adding hydrophobic substances to the anode catalyst slurry and cathode catalyst slurry close to the proton exchange membrane; adding hydrophilic substances to the anode catalyst slurry and cathode catalyst slurry away from the proton exchange membrane is more conducive to water discharge and avoids membrane swelling.

[0024] 4. Using proton-conducting polymers compared to traditional proton-conducting polymers:

[0025] (1) Without losing the proton transfer sites, the electron transfer resistance is greatly reduced, and the ohmic impedance of the catalytic layer is reduced.

[0026] (2) It is easier to disperse, which is beneficial to improving the stability of the catalytic layer slurry, the film forming properties of the membrane layer, and the consistency of the membrane layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a test diagram of the electrochemical performance of each catalytic layer in Experimental Example 1 of the present invention;

[0028] Figure 2 This is the impedance spectrum of each catalytic layer in Experimental Example 2 of the present invention. DETAILED DESCRIPTION

[0029] The following is a clear and complete description of the technical solutions in some embodiments of the present application. Obviously, the embodiments described are only some of the embodiments of the present application, not all of them. Based on the embodiments provided in this application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0030] In the following, the terms "first," "second," etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the quantity of the technical features indicated. Therefore, a feature specified as "first," "second," etc. may explicitly or implicitly include one or more of the features.

[0031] When describing some embodiments, the expression "A and / or B" may be used. It is easy to understand that "A and / or B" includes the following three combinations: only A, only B, and a combination of A and B.

[0032] When describing some embodiments, the expressions "at least one of A, B and C" and "at least one of A, B or C" may be used, both of which have the same meaning and include the following combinations of A, B and C: only A, only B, only C, the combination of A and B, the combination of A and C, the combination of B and C, and the combination of A, B and C.

[0033] The Pt / C catalyst, deionized water, ionomer solution, 3,4-ethylenedioxythiophene, high dielectric small molecule alcohol, nano rare earth metal oxide and pore-forming agent reagent used in this example and comparative example were purchased from Aladdin Reagent.

[0034] Example 1

[0035] S1. Using high-speed shearing, prepare anode catalyst slurries and cathode catalyst slurries with 3%, 1.5%, and 1% pore-forming agent contents: Pt / C catalyst, deionized water, 5% mass fraction Nafion solution, isopropanol, gadolinium-doped cerium oxide (20 nm), and ammonium bicarbonate to form a uniform catalyst slurry with a solid content of 1%. The proportions of the components in the anode catalyst slurry and cathode catalyst slurry are as follows:

[0036] Anode catalyst slurry: The mass of the active component of the ionomer is 30% of the mass of the carbon in the Pt / C catalyst, the mass ratio of water and high dielectric small molecule alcohol is 1:1, and the Pt loading is 0.2 mg / cm 2 The mass of gadolinium-doped cerium oxide (20 nm) is 1% of the mass of the Pt / C catalyst. Polyvinylidene fluoride (PVDF) is added to the anode catalyst slurry with a 3% pore-forming agent content, which is 0.5% of the mass of the Pt / C catalyst. Styrene-butadiene rubber (SBR) is added to the anode catalyst slurry with a 1% pore-forming agent content, which is 0.5% of the mass of the Pt / C catalyst.

[0037] Cathode catalyst slurry: The content of the active ingredient of the ionomer is 30% of the mass of the carbon in the Pt / C catalyst, the mass ratio of water and high dielectric small molecule alcohol is 1:1, and the Pt loading is 0.5 mg / cm 2 The mass of gadolinium-doped cerium oxide (20 nm) was 1% of the mass of the Pt / C catalyst. Polytetrafluoroethylene (PTFE) was added to the cathode catalyst slurry with a 3% pore-forming agent content, which was 0.5% of the mass of the Pt / C catalyst. Polyethylene glycol (PEG) was added to the cathode catalyst slurry with a 1% pore-forming agent content, which was 0.5% of the mass of the Pt / C catalyst.

[0038] S2. Spray the dispersed anode catalyst slurry onto one side of the proton exchange membrane in descending order of pore-forming agent content; control the spraying time to ensure that the thickness of the prepared membrane layer of the slurry is approximately 1 μm, 2 μm, and 5 μm, respectively.

[0039] S3. Spray the dispersed cathode catalyst slurry onto one side of the proton exchange membrane in descending order of pore-forming agent content; control the spraying time to ensure that the thickness of the prepared membrane layer of the slurry is approximately 1 μm, 2 μm, and 5 μm, respectively.

[0040] Example 2

[0041] S1. Using high-speed shearing, prepare anode catalyst slurries and cathode catalyst slurries with 3%, 2%, and 1.5% pore-forming agent contents: Pt / C catalyst, deionized water, 5% mass fraction Nafion solution, n-propanol, scandium-doped cerium oxide (30 nm), and ammonium oxalate to form a uniform catalyst slurry with a solid content of 1%. The proportions of the components in the anode catalyst slurry and cathode catalyst slurry are as follows:

[0042] Anode catalyst slurry: The mass of the active component of the ionomer is 50% of the mass of the carbon in the Pt / C catalyst, the mass ratio of water and high dielectric small molecule alcohol is 1:2, and the Pt loading is 0.1 mg / cm 2 The mass of gadolinium-doped cerium oxide (30 nm) is 1% of the mass of the Pt / C catalyst; wherein, the anode catalyst slurry with a 3% pore-forming agent content is added with 1% of the mass of the Pt / C catalyst in polyvinylidene fluoride; the anode catalyst slurry with a 1% pore-forming agent content is added with 0.5% of the mass of the Pt / C catalyst in styrene-butadiene rubber;

[0043] Cathode catalyst slurry: The content of the active ingredient of the ionomer is 30% of the mass of the carbon in the Pt / C catalyst, the mass ratio of water and high dielectric small molecule alcohol is 1:4, and the Pt loading is 0.3 mg / cm 2 The mass of gadolinium-doped cerium oxide (30 nm) was 1% of the mass of the Pt / C catalyst. Polytetrafluoroethylene (PTFE) was added to the cathode catalyst slurry with a 3% pore-forming agent content, which was 1% of the mass of the Pt / C catalyst. Polyethylene glycol (PEG) was added to the cathode catalyst slurry with a 1% pore-forming agent content, which was 2% of the mass of the Pt / C catalyst.

[0044] S2. Spray the dispersed anode catalyst slurry onto one side of the proton exchange membrane in the order of pore-forming agent content from high to low; control the spraying time to ensure that the thickness of the prepared membrane layer of the slurry is approximately 1 μm, 3 μm, and 3 μm, respectively.

[0045] S3. Spray the dispersed cathode catalyst slurry onto one side of the proton exchange membrane in descending order of pore-forming agent content; control the spraying time to ensure that the thickness of the prepared membrane layer of the slurry is approximately 1 μm, 3 μm, and 3 μm, respectively.

[0046] Example 3

[0047] S1. Prepare a 10% mass fraction of PEDOT:PFSA proton conduction-conductive polymer: Use high-speed shearing to mix the perfluorosulfonic acid resin solution, conductive polymer monomer, and deionized water into a uniform emulsion. Add an oxidant, allow to fully react and disperse, and remove impurities using a semipermeable membrane. After centrifugation, use a high-dielectric small molecule spring to evenly disperse the conductive polymer. The proportions of the components in the emulsion are as follows:

[0048] The mass ratio of the conductive polymer to the perfluorosulfonic acid resin solid matter is 1:1, the mass of the mixed solid matter is 10% of the total mass of the emulsion, the amount of the oxidant added is 1.5 times that of the mixed solid matter, and the ratio of the amount of the high dielectric small molecule alcohol added to the amount of deionized water added is 1:2;

[0049] S2. Using high-speed shearing, prepare anode catalyst slurries and cathode catalyst slurries with 2%, 1.5%, and 1% pore-forming agent contents: Pt / C catalyst, deionized water, 10% PEDOT:PFSA solution, isopropyl alcohol, yttrium-doped zirconium oxide (40 nm), and ammonium carbonate to form a uniform catalyst slurry with a solid content of 1%. The proportions of the components in the anode catalyst slurry and cathode catalyst slurry are as follows:

[0050] Anode catalyst slurry: The mass of the active component of the ionomer is 80% of the mass of the carbon in the Pt / C catalyst, the mass ratio of water and high dielectric small molecule alcohol is 1:1, and the Pt loading is 0.3 mg / cm 2 The mass of yttrium-doped zirconia (20 nm) is 1% of the mass of the Pt / C catalyst. Polyvinylidene fluoride (PVDF) is added to the anode catalyst slurry with a 3% pore-forming agent content, which is 2% of the mass of the Pt / C catalyst. Styrene-butadiene rubber (SBR) is added to the anode catalyst slurry with a 1% pore-forming agent content, which is 0.5% of the mass of the Pt / C catalyst.

[0051] Cathode catalyst slurry: The content of the active ingredient of the ionomer is 30% of the mass of the carbon in the Pt / C catalyst, the mass ratio of water and high dielectric small molecule alcohol is 1:3, and the Pt loading is 0.7 mg / cm 2The mass of yttrium-doped zirconia (20 nm) was 1% of the mass of the Pt / C catalyst. Polytetrafluoroethylene (PTFE) was added to the cathode catalyst slurry with a 3% pore-forming agent content, which was 2% of the mass of the Pt / C catalyst. Silicon dioxide (SiO2) was added to the cathode catalyst slurry with a 1% pore-forming agent content, which was 1% of the mass of the Pt / C catalyst.

[0052] S3. Spray the dispersed anode catalyst slurry onto one side of the proton exchange membrane in descending order of pore-forming agent content; control the spraying time to ensure that the thickness of the prepared membrane layer of the slurry is approximately 1 μm, 3 μm, and 3 μm, respectively.

[0053] S4. Spray the dispersed cathode catalyst slurry onto one side of the proton exchange membrane in descending order of pore-forming agent content; control the spraying time to ensure that the thickness of the prepared membrane layer of the slurry is approximately 1 μm, 3 μm, and 3 μm, respectively.

[0054] Example 4

[0055] S1. Using high-speed shearing, prepare anode catalyst slurries and cathode catalyst slurries with 2%, 1%, and 1% pore-forming agent contents: Pt / C catalyst, deionized water, 5% mass fraction Nafion solution, ethanol, yttrium-doped zirconium oxide (40nm), and ammonium carbonate to form a uniform catalyst slurry with a solid content of 1%. The proportions of the components in the anode catalyst slurry and cathode catalyst slurry are as follows:

[0056] Anode catalyst slurry: The mass of the active component of the ionomer is 80% of the mass of the carbon in the Pt / C catalyst, the mass ratio of water and high dielectric small molecule alcohol is 1:1, and the Pt loading is 0.2 mg / cm 2 The mass of scandium-doped zirconium oxide (30 nm) is 5% of the mass of the Pt / C catalyst; wherein, the anode catalyst slurry with a 3% pore-forming agent content is added with 1% of the mass of the Pt / C catalyst in polyvinylidene fluoride; the anode catalyst slurry with a 1% pore-forming agent content is added with 1% of the mass of the Pt / C catalyst in styrene-butadiene rubber;

[0057] Cathode catalyst slurry: The content of the active ingredient of the ionomer is 30% of the mass of the carbon in the Pt / C catalyst, the mass ratio of water and high dielectric small molecule alcohol is 1:3, and the Pt loading is 0.4 mg / cm 2 The mass of scandium-doped zirconium oxide (30 nm) is 5% of the mass of the Pt / C catalyst; wherein, the cathode catalyst slurry with a 3% pore-forming agent content is added with 1% polytetrafluoroethylene of the mass of the Pt / C catalyst; and the cathode catalyst slurry with a 1% pore-forming agent content is added with 1.5% silica of the mass of the Pt / C catalyst;

[0058] S2. Spray the dispersed anode catalyst slurry onto one side of the proton exchange membrane in descending order of pore-forming agent content; control the spraying time to ensure that the thickness of the prepared membrane layer of the slurry is approximately 1 μm, 2 μm, and 5 μm, respectively.

[0059] S3. Spray the dispersed cathode catalyst slurry onto one side of the proton exchange membrane in descending order of pore-forming agent content; control the spraying time to ensure that the thickness of the prepared membrane layer of the slurry is approximately 1 μm, 2 μm, and 5 μm, respectively.

[0060] Comparative Example

[0061] S1. Prepare anode catalyst slurry and cathode catalyst slurry by high-speed shearing: Pt / C catalyst, deionized water, 5% mass fraction Nafion solution, and isopropanol are mixed into a uniform catalyst slurry with a solid content of 1%; wherein, the proportions of the components in the anode catalyst slurry and cathode catalyst slurry are as follows:

[0062] Anode catalyst slurry: The mass of the active component of the ionomer is 80% of the mass of the carbon in the Pt / C catalyst, the mass ratio of water and high dielectric small molecule alcohol is 1:1, and the Pt loading is 0.3 mg / cm 2 ;

[0063] Cathode catalyst slurry: The content of the active ingredient of the ionomer is 30% of the mass of the carbon in the Pt / C catalyst, the mass ratio of water and high dielectric small molecule alcohol is 1:3, and the Pt loading is 0.7 mg / cm 2 ;

[0064] S2. The dispersed anode catalyst slurry is sprayed on one side of the proton exchange membrane in sequence by spraying; the membrane layer thickness is about 7 μm.

[0065] S3. Spray the dispersed cathode catalyst slurry onto the other side of the proton exchange membrane in sequence; the prepared membrane layer has a thickness of about 7 μm.

[0066] Experimental Example 1

[0067] The CCM sprayed in the above examples 1-4 and the comparative example was prepared into a single cell for electrochemical performance testing. The experimental conditions were: pH2 = Pair = 0.1 MPa, humidification RH = 100% on both sides of hydrogen and air, humidification temperature T = 75°C, cell temperature Tcell = 60 ± 5°C, and the membrane electrode active area of ​​the single cell test was 35 cm 2 The electrochemical performance of the film-forming electrode was tested. For details, see the attached Figure 1 , according to the attached Figure 1(Step from open circuit potential to 0 V, 50 mV each time, for 30 s, record voltage-current curve, power test is continuous discharge at 0.65 V) and Figure 2 (The test conditions are a discharge voltage of 0.65 V, an interference current amplitude of 200 mA, a test frequency range of 10 kHz-50 kHz, and a voltage amplitude of 50 mV.) It can be seen that the membrane electrode prepared using this scheme has a smaller voltage drop in the activated polarization region, obtains more superior ORR kinetics, and has better electrical performance.

[0068] The above description is merely a preferred embodiment of the present application. It should be understood that the present application is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Instead, the present application can be used in various other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in related fields. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present application should be protected by the claims appended hereto.

Claims

1. A catalyst layer of a fuel cell, characterized in that: The method comprises a plurality of cathode catalyst layers and a plurality of anode catalyst layers; the slurries in the manufacturing process of any of the anode catalyst layers and the cathode catalyst layers respectively comprise Pt / C catalyst, deionized water, PEDOT:PFSA solution, high dielectric small molecule alcohol, nano rare earth metal oxide and pore-forming agent; The contents of the pore former in the slurry of the anode catalyst layer and the slurry of the cathode catalyst layer are gradually reduced in the order from near to far from the proton exchange membrane; The PEDOT:PFSA solution includes 3,4-ethylenedioxythiophene, perfluorosulfonic acid resin, deionized water, an oxidant, and a high-dielectric small molecule alcohol, wherein the mass ratio of the 3,4-ethylenedioxythiophene to the perfluorosulfonic acid resin is 1:(1-4), the mass ratio of the mixture of the 3,4-ethylenedioxythiophene and the perfluorosulfonic acid resin to the oxidant is 1:(1.5-2), the mass ratio of the mixture of the 3,4-ethylenedioxythiophene and the perfluorosulfonic acid resin to the deionized water is 1:(4.5-6), and the mass ratio of the deionized water to the high-dielectric small molecule alcohol is (1-2):1; The mass of the nano rare earth metal oxide is 1%-5% of the mass of the Pt / C catalyst; The slurry of the anode catalyst layer and the slurry of the cathode catalyst layer closest to the proton exchange membrane also include a hydrophobic substance respectively; The slurry of the anode catalyst layer and the slurry of the cathode catalyst layer, which are farthest from the proton exchange membrane, also include hydrophilic substances.

2. The catalyst layer of the fuel cell according to claim 1, characterized in that In the slurry of the anode catalyst layer, the solid-liquid mass ratio is 1-5%; wherein the mass ratio of the deionized water to the high dielectric small molecule alcohol is 1:(1-4), the content of the pore-forming agent is 1%-3% of the mass of the Pt / C catalyst, the mass of the ionomer in the PEDOT:PFSA solution is 30%-80% of the mass of the carbon in the Pt / C catalyst, and the Pt loading is 0.1-0.3 mg / cm 2 .

3. The catalyst layer of the fuel cell according to claim 1, characterized in that In the slurry of the cathode catalyst layer, the solid-liquid mass ratio is 1-5%; wherein the mass ratio of the deionized water to the high dielectric small molecule alcohol is 1:(1-4), the content of the pore-forming agent is 1%-3% of the mass of the Pt / C catalyst, the mass of the nano rare earth metal oxide is 1%-5% of the mass of the Pt / C catalyst, the mass of the ionomer in the PEDOT:PFSA solution is 30%-80% of the mass of the carbon in the Pt / C catalyst, and the Pt loading is 0.3-0.7 mg / cm 2 .

4. The catalyst layer of the fuel cell according to claim 1, characterized in that The amount of the hydrophobic substance added is 0.5%-2% of the mass of the Pt / C catalyst, and the hydrophobic substance includes at least one of polyvinylidene fluoride and polytetrafluoroethylene.

5. The catalyst layer of the fuel cell according to claim 1, characterized in that The added amount of the hydrophilic substance is 0.5%-2% of the mass of the Pt / C catalyst, and the hydrophilic substance includes at least one of styrene-butadiene rubber, silicon dioxide, and polyethylene glycol.

6. The catalyst layer of the fuel cell according to claim 1, characterized in that The high dielectric small molecule alcohol includes at least one of ethanol, ethylene glycol, n-propanol, and isopropanol.

7. The catalyst layer of the fuel cell according to claim 1, characterized in that The pore-forming agent includes at least one of ammonium bicarbonate, ammonium carbonate and ammonium oxalate.

8. The catalyst layer of the fuel cell according to claim 1, characterized in that The nano rare earth metal oxide includes at least one of cerium oxide and zirconium oxide, and the particle size of the nano rare earth metal oxide is 20-40 nm.

9. Use of the catalyst layer of a fuel cell according to any one of claims 1 to 8 in preparing MEA of a fuel cell.

10. A method for preparing a catalyst layer of a fuel cell according to any one of claims 1 to 8, characterized in that: The steps include: S1. 3,4-ethylenedioxythiophene, perfluorosulfonic acid resin, and deionized water are mixed to obtain an emulsion, an oxidant is added to the emulsion for oxidation, impurities are removed, and the emulsion is centrifuged. After centrifugation, the emulsion is dispersed with a high dielectric small molecule alcohol to obtain the PEDOT:PFSA solution; S2, mixing Pt / C catalyst, deionized water, PEDOT:PFSA solution, high dielectric small molecule alcohol, nano rare earth metal oxide and pore-forming agent, and sequentially preparing them on one side of the proton exchange membrane in descending order of pore-forming agent content to obtain a multi-layer anode catalyst layer, wherein the thickness of each anode catalyst layer is 1-5 μm; S3. Pt / C catalyst, deionized water, PEDOT:PFSA solution, high dielectric small molecule alcohol, nano rare earth metal oxide and pore-forming agent are mixed and prepared in descending order of pore-forming agent content on the other side of the proton exchange membrane to obtain a multilayer cathode catalyst layer, each cathode catalyst layer having a thickness of 1-5 μm.

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