Preparation method of membrane electrode of proton exchange membrane fuel cell

Abstract

The present invention provides a method for preparing a membrane electrode of a proton exchange membrane fuel cell. The membrane electrode of the proton exchange membrane fuel cell includes a proton exchange membrane and a gas diffusion layer electrode. The gas diffusion layer electrode sequentially includes a resin thin layer, a catalyst layer, and a gas diffusion layer from top to bottom, which are adhered to the proton exchange membrane. The catalyst layer has an ordered straight pore structure, and the platinum loading of the gas diffusion layer electrode is 0.02 - 0.3 mg / cm<supgt;2< / supgt;. In the present invention, by constructing an ordered pore structure in the catalyst layer, the performance of the low-platinum-loading membrane electrode and the proton exchange membrane fuel cell under high current density conditions is significantly improved.

Description

Technical Field

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

[0002] Proton exchange membrane fuel cells (PEMFCs) use high-purity hydrogen and air as fuel and oxidant respectively, and directly convert the chemical energy in hydrogen into electrical energy through the electrochemical reaction between the fuel hydrogen and the oxidant air. It is not restricted by the Carnot cycle and has the advantages of high energy conversion efficiency, zero pollutant emissions, and environmental friendliness.

[0003] A proton exchange membrane fuel cell power generation system consists of multiple subsystems and components. Among them, the membrane electrode (MEA) is its core component and the place where the electrochemical reaction occurs. The membrane electrode usually consists of an electrolyte membrane and an anode and a cathode placed on both sides, and the three are in close contact. The anode consists of an anode diffusion layer and an anode catalyst layer, the cathode consists of a cathode diffusion layer and a cathode catalyst layer, and the cathode and anode catalyst layers are in contact with the electrolyte membrane. At the same time, both the anode diffusion layer and the cathode diffusion layer are composed of a carbon paper layer and a porous layer containing hydrophobic polytetrafluoroethylene. The thickness and structure of the carbon papers of the two are the same, and the thickness and structure of the porous layers can be the same or different.

[0004] At present, the electrolyte membrane and the diffusion layer have become commercial products. Since the catalyst layer composed of a catalyst and a perfluorosulfonic acid resin generally uses noble metal platinum, reducing the amount of noble metal catalyst in the catalyst is the key to controlling the cost of proton exchange membrane fuel cells. However, the performance of the low platinum loading membrane electrode has significantly decreased under high current density conditions, especially the oxygen reduction performance on the cathode side has decreased more significantly.

[0005] Based on this, it is necessary to provide a method for preparing a membrane electrode of a proton exchange membrane fuel cell to alleviate or solve the above problems. Summary of the Invention

[0006] Aiming at solving the technical problem of the performance degradation of the low platinum loading membrane electrode in the above-mentioned common technologies, the present invention provides a method for preparing a membrane electrode of a proton exchange membrane fuel cell, including the steps of:

[0007] Preparing a catalyst slurry, the catalyst slurry including a solvent, a resin, and a catalyst, and the mass ratio of the resin to the catalyst being 0.04 - 0.6;

[0008] Coating the catalyst slurry and a resin slurry on a gas diffusion layer and transferring it into a non-solvent bath to obtain a gas diffusion layer electrode;

[0009] Bond the gas diffusion layer electrode to the proton exchange membrane and obtain a membrane electrode through hot pressing. The membrane electrode includes a proton exchange membrane and a gas diffusion layer electrode. The gas diffusion layer electrode sequentially includes a resin thin layer, a catalyst layer, and a gas diffusion layer from top to bottom. The resin thin layer is bonded to the proton exchange membrane. The catalyst layer has an ordered straight pore structure. The platinum loading of the gas diffusion layer electrode is 0.02 - 0.3 mg / cm 2 .

[0010] Further, the preparation method of the catalyst slurry includes the steps of:

[0011] Mix the catalyst, the solvent, and the resin evenly, and obtain the catalyst slurry through pulverization treatment. The mass ratio of the solvent to the catalyst is 10 - 70:1.

[0012] Further, the catalyst includes one or more of a carbon-supported platinum catalyst with a low platinum loading, a carbon-supported platinum-based alloy catalyst with two or more elements.

[0013] Further, the preparation of the resin slurry includes the steps of:

[0014] Mix the solvent and the resin, and obtain the resin slurry through pulverization treatment. The mass proportion of the solvent in the resin slurry is 90% - 99.9%, and the mass proportion of the resin in the resin slurry is 0.1% - 10%.

[0015] Further, the solvent includes one or more of N-methyl-2-pyrrolidone, 2-butanone, dimethylformamide, dimethyl sulfoxide, dimethylacetamide, or ethanol;

[0016] The resin includes one or more of perfluorosulfonic acid resin, partially perfluorosulfonic acid resin, and non-fluorosulfonic acid resin.

[0017] Further, in the step of coating the catalyst slurry and the resin slurry on the gas diffusion layer and transferring it into a non-solvent bath to obtain the gas diffusion layer electrode, it includes:

[0018] Coat the catalyst slurry and the resin slurry on the gas diffusion layer in sequence to obtain a three-layer structure electrode of resin thin layer / catalyst layer / gas diffusion layer;

[0019] Transfer the three-layer structure electrode of resin thin layer / catalyst layer / gas diffusion layer into the non-solvent bath, and an exchange reaction occurs between the solvent and the non-solvent to obtain the gas diffusion layer electrode. The coating method includes brush coating, knife coating, or spraying.

[0020] Further, the duration of the exchange reaction is 10 s - 24 h.

[0021] Further, the step of obtaining the gas diffusion layer electrode by the exchange reaction between the solvent and the non-solvent further includes: taking out the three-layer structure electrode of the resin thin layer / catalyst layer / gas diffusion layer after the exchange reaction from the non-solvent bath, and drying it to obtain the gas diffusion electrode;

[0022] Among them, the atmosphere environment of the drying treatment is composed of one or more of air, nitrogen, and argon, and the duration of the drying treatment is 60 min to 7 d.

[0023] Further, the hot pressing temperature in the hot pressing treatment is 80 - 155 °C, the hot pressing pressure is 0.05 - 2 MPa, and the hot pressing duration is 90 s to 7 d.

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

[0025] In the common technologies, the common types of membrane electrodes are the second-generation catalyst-coated membrane (CCM) type and the first-generation gas diffusion electrode (GDE) type. Among them, the former is widely used and is currently the mainstream commercial preparation method of membrane electrodes. The catalyst layers of both configurations are randomly distributed, and the internal pore structure and catalyst particles are in a disordered state. The disordered internal pore structure increases the mass transfer resistance and will significantly reduce the performance of the membrane electrode with a low platinum loading under high current density conditions.

[0026] In contrast, the present invention provides a membrane electrode for a proton exchange membrane fuel cell, which constructs an ordered pore structure in the catalyst layer, including a nanoarray structure or other shaped ordered structures, can provide ordered proton, electron or mass transfer channels, reduce the mass transfer resistance, expand the three-phase interface of the chemical reaction, significantly improve the performance of the membrane electrode and the proton exchange membrane fuel cell under high current density conditions, and optimize the application effect of the membrane electrode with a low platinum loading (the platinum loading in the gas diffusion layer electrode is 0.02 - 0.3 mg / cm 2 ) in the proton exchange membrane fuel cell. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0028] Figure 1 It is a schematic structural diagram of the gas diffusion layer electrode prepared in Example 1 of the present invention; where 1-1 is the resin thin layer, 1-2 is the catalyst layer, and 1-3 is the gas diffusion layer;

[0029] Figure 2 Schematic diagram of the structure of a low-platinum-loading gas diffusion layer electrode prepared by the conventional method in Comparative Example 1 of the present invention; wherein 2-1 is a resin thin layer, 2-2 is a catalyst layer, and 2-3 is a gas diffusion layer;

[0030] Figure 3 Gas permeability curves in Examples 1-4 and Comparative Examples 1-2 of the present invention, where the ordinate represents the nitrogen permeation flux, with the unit of 10 5 Lm -2 h -1 , and the abscissa represents the pressure difference, with the unit of bar;

[0031] Figure 4 Pure water permeability curves in Examples 1-4 and Comparative Examples 1-2 of the present invention, where the ordinate represents the pure water permeation flux, with the unit of 10 4 kgm -2 h -1 , and the abscissa represents the pressure difference, with the unit of bar;

[0032] Figure 5 Power density curves in Examples 1-4 and Comparative Examples 1-2 of the present invention, where the ordinate represents the power density, with the unit of watts per square centimeter, and the abscissa represents the current density, with the unit of amperes per square centimeter. Detailed implementation manners

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] Moreover, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the premise that those of ordinary skill in the art can implement them. When the combination of technical solutions conflicts or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0035] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present invention, any of the two endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are the same as those understood by those of ordinary skill in the art in the prior art and the description of the present invention. Any methods, devices, and materials similar or equivalent to those in the embodiments of the present invention can also be used to implement the present invention.

[0036] In common technologies, such asFigure 2 As shown, the internal pore structure of the membrane electrode is disordered, and the electrochemical performance of the membrane electrode is insufficient under high current density conditions, especially the oxygen reduction performance on the cathode side decreases more significantly. For example, in the second-generation catalyst-coated membrane (CCM) type and the first-generation gas diffusion electrode (GDE) type, the catalyst layers of both configurations are randomly distributed, and the internal pore structure and catalyst particles are in a disordered state. The disordered internal pore structure increases the mass transfer resistance and will significantly reduce the performance of the membrane electrode under high current density conditions.

[0037] Moreover, with the decrease of the platinum loading, the mass transfer resistance further increases, and the reasons are as follows:

[0038] The decrease of platinum loading leads to an increase in oxygen transport resistance: with the decrease of platinum loading, the platinum active sites in the catalyst layer decrease, resulting in more oxygen being required to be distributed on fewer platinum surfaces for the reduction reaction. This will increase the transport path length of oxygen in the catalyst layer, thereby increasing the oxygen transport resistance. In addition, the low platinum loading may also lead to changes in the structure of the catalyst layer, such as a decrease in porosity and a more complex pore structure, which will further increase the difficulty of oxygen transport and thus affect the electrochemical performance under high current density conditions.

[0039] Specifically, the mass transfer resistance in the catalyst layer directly affects the efficiency of oxygen (or other reaction gases) transporting from the gas diffusion layer to the catalyst surface. The increase of mass transfer resistance will lead to limited oxygen transport, thereby reducing the performance of the fuel cell under high current density. This is manifested as a decrease in the limiting current density, that is, the maximum current that the fuel cell can output under specific conditions decreases, thus affecting its power output.

[0040] Therefore, designing and fabricating a low-platinum-loading membrane electrode with low mass transfer resistance is the key to improving the proton exchange membrane fuel cell under high current density conditions.

[0041] To solve the technical problems faced in the above-mentioned common technologies, the present invention provides a membrane electrode for a proton exchange membrane fuel cell, including a proton exchange membrane and a gas diffusion layer electrode. The gas diffusion layer electrode sequentially includes a resin thin layer, a catalyst layer, and a gas diffusion layer from top to bottom. The gas diffusion layer has an ordered straight pore structure, and the platinum loading of the gas diffusion layer electrode is 0.02 - 0.3 mg / cm 2 .

[0042] Exemplarily, the platinum loading of the gas diffusion layer electrode can be 0.1 mg / cm 2 .

[0043] Wherein the structure of the gas diffusion layer electrode is as Figure 1 shown.

[0044] The catalyst layer constructs an ordered pore structure, including a nanoarray structure or an ordered structure of other shapes, which can provide ordered proton, electron or mass transfer channels, reduce mass transfer resistance, expand the three-phase interface of chemical reactions, and improve the performance of low- platinum-loading membrane electrodes and proton exchange membrane fuel cells under high current density conditions.

[0045] Specifically, the ordered pore structure provides a fast channel for the transport of gases and liquids, accelerating the diffusion of reactants to the catalyst surface and the discharge of products from the catalyst surface. This helps to reduce mass transfer limitations and increase the reaction rate.

[0046] In addition, by optimizing the mass transfer performance, the ordered pore structure can reduce the performance loss caused by mass transfer polarization, thereby improving the overall performance of the membrane electrode.

[0047] The present invention provides a method for preparing a membrane electrode of a proton exchange membrane fuel cell, including the steps of:

[0048] S1. Prepare a catalyst slurry, the catalyst slurry includes a solvent, a resin and a catalyst, and the mass ratio of the resin to the catalyst is 0.04 - 0.6.

[0049] Exemplarily, the mass ratio of the resin to the catalyst can be 0.1 - 0.5:1.

[0050] The preparation method of the catalyst slurry includes the steps of:

[0051] Mix the catalyst, the solvent and the resin evenly, and obtain the catalyst slurry through pulverization treatment. The mass ratio of the solvent to the catalyst is 10 - 70:1.

[0052] Exemplarily, the mass ratio of the solvent to the catalyst can be 20 - 40:1.

[0053] In some embodiments, the catalyst can be mixed evenly with the solvent and resin particles, and the catalyst slurry can be obtained by ball milling at 0 - 80°C for more than 10 minutes.

[0054] The solvent includes one or more of N-methyl-2-pyrrolidone, 2-butanone, dimethylformamide, dimethyl sulfoxide, dimethylacetamide or ethanol;

[0055] The resin includes one or more of perfluorosulfonic acid resin, partially perfluorosulfonic acid resin and non-fluorosulfonic acid resin.

[0056] The catalyst includes one or more of a low-platinum-loading platinum-on-carbon catalyst, a carbon-supported platinum-based alloy catalyst with two or more components.

[0057] One or a mixture of several kinds of carbon-supported binary or higher platinum alloy catalysts, including carbon-supported binary / ternary / quaternary / quinary or higher platinum alloy catalysts.

[0058] Carbon-supported binary or higher platinum alloy catalysts refer to composite materials formed by alloying platinum (Pt) with at least one other metal element (usually transition metals such as nickel, chromium, cobalt, vanadium, iron, etc.) and loading this alloy on a carbon material with a high specific surface area. Using common metals to represent precious metal platinum can reduce costs and platinum consumption.

[0059] In some embodiments, the mass concentration of platinum in the catalyst can be 20% - 30%.

[0060] Exemplarily, the solvents and resin types in the catalyst slurry and resin slurry can be the same respectively.

[0061] S2. Coating the catalyst slurry and the resin slurry on the gas diffusion layer and transferring it into a non-solvent bath to obtain a gas diffusion layer electrode.

[0062] Exemplarily, the catalyst slurry and the resin slurry can be coated on the gas diffusion layer in one step.

[0063] The preparation of the resin slurry includes the steps:

[0064] Mixing the solvent and the resin, and obtaining the resin slurry through pulverization treatment. The mass ratio of the solvent in the resin slurry is 90% - 99.9%, and the mass ratio of the resin in the resin slurry is 0.1% - 10%.

[0065] In some embodiments, the solvent and resin particles can be mixed evenly and ball-milled at 0 - 80 °C for more than 10 minutes to obtain the resin slurry.

[0066] The solvent includes one or more of N-methyl-2-pyrrolidone, 2-butanone, dimethylformamide, dimethyl sulfoxide, dimethylacetamide, or ethanol;

[0067] The resin includes one or more of perfluorosulfonic acid resin, partially perfluorosulfonic acid resin, and non-fluorosulfonic acid resin.

[0068] In the step S2, it includes:

[0069] S21. Coating the catalyst slurry and the resin slurry on the gas diffusion layer in sequence to obtain a three-layer structure electrode of resin thin layer / catalyst layer / gas diffusion layer;

[0070] S22. Transfer the resin thin layer / catalyst layer / gas diffusion layer three-layer structure electrode into the non-solvent bath, where the solvent and the non-solvent undergo an exchange reaction to obtain the gas diffusion layer electrode. The coating methods include brush coating, knife coating, or spraying.

[0071] In some embodiments, the duration of the exchange reaction is 10 s to 24 h.

[0072] In some other embodiments, take out the resin thin layer / catalyst layer / gas diffusion layer three-layer structure electrode after the exchange reaction from the non-solvent bath, and obtain the gas diffusion electrode after drying treatment;

[0073] Among them, the atmosphere environment for the drying treatment is composed of one or more of air, nitrogen, and argon, and the duration of the drying treatment is 60 min to 7 d.

[0074] The non-solvent is a solution formed by water, alcohols, esters, or a mixture of several kinds.

[0075] In some embodiments, the blade heights of the catalyst slurry and the resin slurry can both be set at 0.005 - 2 mm.

[0076] In some specific embodiments, step S2 includes: preparing the catalyst slurry on the gas diffusion layer by brush coating, knife coating, or spraying to obtain a wet gas diffusion layer electrode; then preparing the prepared resin slurry on the wet gas diffusion layer electrode obtained in the previous step by brush coating, knife coating, or spraying to obtain a resin thin layer / catalyst layer / gas diffusion layer three-layer structure electrode; transferring this three-layer structure electrode into a non-solvent bath to undergo an exchange reaction between the solvent and the non-solvent to obtain a gas diffusion layer electrode with an ordered straight pore structure with a resin thin layer. The exchange time is 10 seconds to 24 hours, and then take it out from the non-solvent bath and dry it in air, nitrogen, argon, or a mixture of several gases for 60 minutes to one week until it is completely dry. The non-solvent is a solution formed by water, alcohols, esters, or a mixture of several kinds.

[0077] S3. Bond the gas diffusion layer electrode to the proton exchange membrane and obtain a membrane electrode after hot pressing treatment.

[0078] The hot pressing temperature in the hot pressing treatment is 80 - 155 °C, the hot pressing pressure is 0.05 - 2 MPa, and the hot pressing duration is 90 s to 7 d.

[0079] Among them, the resin thin layer of the gas diffusion layer is closely bonded to the proton exchange membrane.

[0080] In some embodiments, the effectively sized membrane electrode obtained by hot pressing is 10 - 50 cm 2

[0081] The beneficial technical effects of the present invention:

[0082] The present invention controls the platinum loading of the gas diffusion layer electrode within the range of 0.02 - 0.3 mg / cm 2 , achieving cost reduction while ensuring the application effect of the proton exchange membrane fuel cell.

[0083] In the present invention, by regulating the exchange rate of the solvent in the catalyst slurry with the non-solvent in the non-solvent bath, the technical prejudice of the pore structure complexity of the catalyst layer of the membrane electrode with low platinum loading is overcome. An ordered pore structure is efficiently constructed in the catalyst layer, and then a straight pore channel with low resistance is provided for mass transfer, effectively reducing the mass transfer resistance within the catalyst layer, and achieving the purpose of improving the performance of the membrane electrode and the electrochemical performance of the proton exchange fuel cell.

[0084] In the present invention, introducing a resin thin layer can enhance the thermal matching performance and hot pressing molding uniformity between the catalyst layer and the proton exchange membrane, and improve the yield of the membrane electrode.

[0085] In the present invention, the resin thin layer matching the proton exchange membrane and the catalyst layer are obtained by one-step molding, reducing the manufacturing process flow and steps of the membrane electrode, and effectively reducing the fixed investment and the manufacturing cost of the membrane electrode.

[0086] For the convenience of those skilled in the art to further understand the present invention, the following is an example for illustration:

[0087] Example 1

[0088] 1) Preparation of the catalyst slurry: Using Premetek 30% platinum-carbon catalyst (Vulcan XC-72 support) as the catalyst, perfluorosulfonic acid resin particles as the resin raw material, and N-methyl-2-pyrrolidone as the solvent, where the mass ratio of the solvent to the catalyst is 30:1, and the mass ratio of the catalyst to the resin is 1:0.5, to prepare a mixed emulsion with a certain viscosity.

[0089] 2) Preparation of the resin slurry: Using perfluorosulfonic acid resin particles as the resin raw material and N-methyl-2-pyrrolidone as the solvent, and preparing a resin slurry with a certain viscosity according to the mass ratio of the solvent to the resin of 40:1.

[0090] 3) Preparation of the gas diffusion layer electrode with an ordered straight pore structure with a resin thin layer: Using a double-layer doctor blade, the gas diffusion layer electrode with an ordered straight pore structure with a resin thin layer is prepared by a doctor blade coating method in one step. The doctor blade heights of the catalyst slurry and the resin slurry are 0.3 mm and 0.05 mm respectively. The prepared electrode has a thickness of 0.15 mm, is placed in water for exchange for 1 day, taken out and dried for one week, and the catalyst platinum loading is 0.1 mg / cm 2 .

[0091] 4) Preparation of the membrane electrode: Bond the above gas diffusion layer electrode to the proton exchange membrane and hot press to obtain an effective area of 4 cm2 The membrane electrode. The hot pressing temperature is 120 °C, the hot pressing pressure is 0.5 MPa, and the hot pressing time is 1 hour.

[0092] 5) Evaluation of the electrode permeation performance: Cut a circular ordered straight pore structure gas diffusion layer electrode with a resin thin layer and an effective area of 1 cm 2 Place it on a membrane integrity tester, adjust the pressure difference on both sides of the electrode by introducing N2, and study the N2 permeation flux in the range of 0 - 0.5 bar pressure difference; introduce pure water on one side of the electrode, use N2 to extrude the pure water, and test the pure water permeation flux of the electrode under the condition of 0 - 2.5 MPa pressure difference. It is used to evaluate the mass transfer resistance of the membrane. The larger the permeation flux, the smaller the mass transfer resistance.

[0093] 6) Evaluation of the electrode electrochemical performance: Assemble the prepared membrane electrode into a proton exchange membrane fuel cell, place it on a proton exchange membrane fuel cell test platform, test the current-voltage relationship of the cell, obtain the current-power density relationship curve of the cell, and the test conditions are: test temperature: 65 °C, hydrogen gas flow rate: 0.1 L / min, air flow rate: 1 L / min.

[0094] Example 2

[0095] In step 1), the mass ratio of the catalyst to the resin is 10:1, and the rest is the same as in Example 1.

[0096] Example 3

[0097] In step 4), the hot pressing temperature is 140 °C, the hot pressing pressure is 1.0 MPa, and the hot pressing time is 2 hours, and the rest is the same as in Example 1.

[0098] Example 4

[0099] In step 1), Premetek 20% platinum-carbon catalyst (Vulcan XC-72 support) is used as the catalyst. In step 3), the height of the catalyst slurry blade is 0.4 mm, and the rest is the same as in Example 1. It can be seen that although the thickness increases, the permeation performance decreases and the cell performance decreases, but it is still higher than the traditional membrane electrode.

[0100] In the comparative sample membrane electrode, the catalyst layer has a disordered pore structure and is prepared by the spraying method. The specific preparation process is as follows:

[0101] Comparative Example 1

[0102] 1) Preparation of the catalyst slurry: Using Premetek 30% platinum-carbon catalyst (Vulcan XC-72 support) as the catalyst, 5% Nafion solution as the resin raw material, and isopropyl alcohol as the solvent, where the mass ratio of the solvent to the catalyst is 30:1, and the mass ratio of the catalyst to the resin is 1:0.5, and a mixed emulsion with a certain viscosity is prepared.

[0103] 2) Preparation of the resin slurry: Isopropyl alcohol was used as the solvent and 5% Nafion solution was used as the resin solution. The resin mass ratio was adjusted to 40:1 to prepare a resin slurry with a certain viscosity.

[0104] 3) Preparation of the gas diffusion layer electrode: The catalyst slurry was sprayed onto the gas diffusion layer using the spraying method. After drying, the resin slurry was sprayed onto the surface of the catalyst slurry. After drying, a gas diffusion electrode was formed, and the catalyst loading was 0.1 mg / cm 2 .

[0105] 4) Preparation of the membrane electrode: The above gas diffusion layer electrode was laminated with a proton exchange membrane, and a membrane electrode with an effective area of 4 cm 2 was obtained by hot pressing. The hot pressing temperature was 120 °C, the hot pressing pressure was 0.5 MPa, and the hot pressing time was 1 hour.

[0106] 5) Evaluation of the electrode permeation performance: A circular gas diffusion layer electrode with an effective area of 1 cm 2 was cut and placed on a membrane integrity tester. The pressure difference between the two sides of the electrode was adjusted by introducing N2 to study the N2 permeation flux in the range of 0 - 0.5 bar pressure difference; pure water was introduced on one side of the electrode, and N2 was used to extrude the pure water to test the pure water permeation flux of the electrode under the condition of 0 - 2.5 MPa pressure difference. It was used to evaluate the mass transfer resistance of the membrane. The greater the permeation flux, the smaller the mass transfer resistance.

[0107] 6) Evaluation of the electrode electrochemical performance: The prepared membrane electrode was assembled into a proton exchange membrane fuel cell and placed on a proton exchange membrane fuel cell test platform to test the current-voltage relationship of the cell and obtain the current-power density relationship curve of the cell. The test conditions were: test temperature: 65 °C, hydrogen flow rate: 0.1 L / min, air flow rate: 1 L / min.

[0108] Comparative Example 2

[0109] In step 1), Premetek 20% platinum-carbon catalyst (Vulcan XC-72 support) was used as the catalyst. In step 4), the hot pressing temperature was 140 °C, the hot pressing pressure was 1.0 MPa, and the hot pressing time was 2 hours. The rest was the same as Comparative Example 1.

[0110] Performance comparison and analysis:

[0111] 1. The low-platinum-loading membrane electrode prepared by the present invention has obvious mass transfer advantages. As Figure 3 and Figure 4 shown, Examples 1 - 4 have a higher increase in nitrogen flux and pure water permeation flux than Comparative Examples 1 - 2;

[0112] 2. The low-platinum-loading membrane electrode prepared by the present invention has obvious advantages in electrochemical performance. For example, Figure 5 as shown, Examples 1 to 4 have a higher improvement in electrochemical performance compared to Comparative Examples 1 to 2;

[0113] The low-platinum-loading membrane electrode prepared by the present invention can significantly enhance the mass transfer ability within the membrane electrode, and can effectively solve the problem of significant decline in the performance of proton exchange membrane fuel cells under the conditions of low platinum loading and high current density. In the above technical solutions of the present invention, the above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention under the technical concept of the present invention, or direct / indirect application in other related technical fields is included in the patent protection scope of the present invention.

Claims

1. A method for preparing a membrane electrode for a proton exchange membrane fuel cell, characterized in that: Includes steps: preparing a catalyst slurry, wherein the catalyst slurry comprises a solvent, a resin and a catalyst, wherein the mass ratio of the resin to the catalyst is 0.04-0.6; the solvent comprises one or more of N-methyl-2-pyrrolidone, 2-butanone, dimethylformamide, dimethyl sulfoxide, dimethylacetamide or ethanol; The catalyst slurry and the resin slurry are coated on the gas diffusion layer and moved into a non-solvent bath, and the solvent and the non-solvent undergo an exchange reaction to obtain an ordered straight pore structure gas diffusion layer electrode with a resin thin layer; the non-solvent in the non-solvent bath includes water; The gas diffusion layer electrode is laminated with a proton exchange membrane, and a membrane electrode is obtained by hot pressing. The membrane electrode includes a proton exchange membrane and a gas diffusion layer electrode. The gas diffusion layer electrode includes a resin thin layer, a catalyst layer and a gas diffusion layer from top to bottom. The resin thin layer is laminated with the proton exchange membrane, and the catalyst layer has an ordered straight pore structure. The platinum loading of the gas diffusion layer electrode is 0.02-0.3 mg / cm 2 .

2. The preparation method according to claim 1, characterized in that: The method for preparing the catalyst slurry comprises the steps of: The catalyst, the solvent and the resin are uniformly mixed and crushed to obtain the catalyst slurry, wherein the mass ratio of the solvent to the catalyst is 10-70:

1.

3. The preparation method according to claim 1, characterized in that: The catalyst comprises one or more of a carbon-supported platinum catalyst with a low platinum loading and a carbon-supported binary or higher platinum alloy catalyst.

4. The preparation method according to claim 2, characterized in that: The preparation of the resin slurry comprises the steps of: The solvent is mixed with the resin, and the resin slurry is obtained by pulverizing the mixture, wherein the mass proportion of the solvent in the resin slurry is 90%-99.9%, and the mass proportion of the resin in the resin slurry is 0.1%-10%.

5. The preparation method according to claim 4, characterized in that: The resin includes one or more of perfluorosulfonic acid resin, partially perfluorosulfonic acid resin and fluorine-free sulfonic acid resin.

6. The preparation method according to claim 1, characterized in that: The step of applying the catalyst slurry and the resin slurry on the gas diffusion layer and moving them into a non-solvent bath to obtain the gas diffusion layer electrode includes: Applying the catalyst slurry and the resin slurry to the gas diffusion layer in sequence to obtain a three-layer structure electrode of resin thin layer / catalyst layer / gas diffusion layer; The three-layer structure electrode of the resin thin layer / catalyst layer / gas diffusion layer is moved into the non-solvent bath, and the solvent and the non-solvent undergo an exchange reaction to obtain the gas diffusion layer electrode. The coating method includes brushing, scraping or spraying.

7. The preparation method according to claim 6, characterized in that: The exchange reaction lasts for 10 s to 24 h.

8. The preparation method according to claim 6, characterized in that: The step of obtaining the gas diffusion layer electrode by the exchange reaction between the solvent and the non-solvent further includes: taking out the resin thin layer / catalyst layer / gas diffusion layer three-layer structure electrode after the exchange reaction from the non-solvent bath, and obtaining the gas diffusion layer electrode by drying; The atmosphere of the drying treatment is composed of one or more of air, nitrogen and argon, and the duration of the drying treatment is 60 minutes to 7 days.

9. The preparation method according to claim 1, characterized in that: The hot pressing temperature in the hot pressing treatment is 80-155° C., the hot pressing pressure is 0.05-2 MPa, and the hot pressing time is 90 s to 7 d.

Images