Preparation of a patterned cathode acid-base catalytic membrane electrode

Abstract

This invention relates to the fabrication of a patterned cathode acid-base catalytic layer membrane electrode, belonging to the field of fuel cell technology. An acidic or alkaline ionomer is added to the slurry used to form the catalytic layer. The slurry is then sprayed onto the microporous side of the gas diffusion layer in a specific patterned manner to form an acidic or alkaline catalytic layer. The cathode-side catalytic layer includes both acidic and alkaline catalytic layers, while the anode-side catalytic layer is solely an acidic catalytic layer. The patterned acid-base catalytic layer membrane electrode is formed on both sides of a proton exchange membrane with symmetrically placed cathode and anode electrodes by hot pressing. This process is simple and easy to implement. The introduction of the patterned alkaline catalytic layer enhances the membrane electrode's self-water management capability, enabling stable and efficient operation at RH levels below 25%, reducing the fuel cell stack's dependence on a humidification system, lowering the complexity of the fuel cell system, and achieving cost reduction and efficiency improvement for the fuel cell stack.

Description

Technical Field

[0001] This invention relates to the field of fuel cells. Specifically, this invention relates to a method for fabricating a membrane electrode assembly (MEA) for a fuel cell. Background Technology

[0002] The membrane electrode assembly (MEA) is the heart of a fuel cell. Typically, in low humidity, proton exchange membrane fuel cells (PEMFCs) experience dehydration of the MEA, resulting in a lack of water molecules for hydrogen ion transport and reduced cell performance. This leads to decreased fuel efficiency and weakened mechanical strength of the MEA, hindering the further commercialization of PEMFCs. Therefore, solving the problem of high-power, stable operation of PEMFCs under low humidity conditions is urgently needed.

[0003] Generally, several common methods exist to meet the operating requirements of fuel cells in low humidity conditions. First, self-humidification of the membrane electrode assembly (MEA) typically requires modifications to the existing MEA structure or materials, such as adding humidifiers to the proton exchange membrane or catalyst layer, or optimizing the gas diffusion layer with hydrophobic agents. This makes the MEA manufacturing process more difficult. Second, internal circulation, where the reactant gas is repeatedly introduced into the reaction zone via a circulation pump or injector to increase humidity, or through a dead-end mode, but this requires extremely high control precision. Third, humidification using a humidifier, currently the most common solution for fuel cells, where the gas humidity is increased and stabilized through a humidification tank. However, this adds extra volume and cost; typically, the cost of the humidifier and water circulation route accounts for 8.75% of the fuel cell stack cost. New humidity solutions are urgently needed to achieve large-scale commercialization of fuel cells at low temperatures and reduce costs.

[0004] Acid-base hybrid fuel cells have emerged as a potential solution for low-temperature, low-humidity operation of fuel cells. Proton exchange membrane fuel cells (acidic fuel cells) produce water on the cathode side, while anion exchange membrane fuel cells (alkaline fuel cells) produce water on the anode side; the electrodes at which they experience flooding differ. The ions conducted in proton exchange membrane cells are H+ ions. + (Acidic), while anion exchange membrane cells conduct OH- - (Alkaline). When proton exchange membranes were used as the ion-conducting medium, and both the anode and cathode electrodes were alkaline, water was found to be generated at the interface of the acidic membrane / alkaline electrode. The battery could achieve a 97 mA cm⁻¹ at 0.6V under 0% RH conditions. -2 Proton exchange membrane fuel cells can only reach 59 mA cm⁻¹. -2 When using anionic and cationic ionomer composite membranes as the conductive medium, the anode electrode is typically an acidic electrode, and the cathode electrode is an alkaline electrode. The battery achieved a power output of 116 mW / cm² under dry gas conditions. -2Furthermore, it was discovered that water is generated in the middle of the composite membrane, and after optimization, the battery can operate at 369mW / cm² under dry gas conditions. -2 Similarly, Peng et al. hot-pressed a pretreated Nafion membrane with a quaternary ammonium salt polysulfone (QAPS) membrane to form a composite membrane, achieving a thickness of 327 mW / cm² under dry gas conditions at 323 K. -2 Subsequent theoretical studies have shown that the thickness and water absorption of the alkaline membrane in the composite membrane lead to differences in water management and performance of the fuel cell. In summary, when using a composite membrane as the conductive medium, the proportion of the alkaline membrane, the interfacial properties between the alkaline and acidic membranes, the catalyst, the ionomer content, and the device components all affect performance. We believe that fully or partially retaining the proton exchange membrane electrode will result in a high-power hybrid fuel cell device.

[0005] In summary, membrane electrodes prepared using existing acid-base mixing methods still suffer from low performance, with reported performance typically not exceeding 500 mW / cm². -2 This may be because when a purely alkaline catalyst layer is used as the cathode or anode electrode, water generated at the interface hinders further reaction. A similar problem arises when using composite membranes, as water generated at the acid-base interface. Developing polymer membrane electrodes suitable for low humidity conditions while leveraging the advantages of both acid and alkaline fuel cells remains a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] This invention aims to solve the problem of high-power operation of membrane electrode assemblies in low-humidity environments. To this end, this invention proposes a method for preparing a membrane electrode with a cathode patterned acid-base catalytic layer.

[0007] The above-mentioned objectives of the present invention are achieved through the following technical solutions:

[0008] A cathode patterned acid-base catalytic membrane electrode includes a proton exchange membrane body, a cathode electrode and an anode electrode disposed on both sides of the proton exchange membrane body. The electrode comprises a catalytic layer and a gas diffusion layer.

[0009] The catalytic layer in the cathode electrode is a patterned acid-base mixed catalytic layer.

[0010] The catalyst layer in the anode electrode is only an acidic catalyst layer.

[0011] This invention proposes a method for preparing a patterned acid-base catalytic membrane electrode for fuel cells, characterized by comprising the following steps:

[0012] (1) Preparation of catalyst layer slurry. Anode catalyst, acidic ionomer and solvent are mixed and ultrasonicated to obtain anode catalyst layer slurry; cathode catalyst, acidic ionomer and solvent are mixed and ultrasonicated to obtain cathode acidic catalyst layer slurry; cathode catalyst, basic ionomer and solvent are mixed and ultrasonicated to obtain cathode basic catalyst layer slurry;

[0013] (2) Preparation of the anode electrode. The anode electrode is obtained by ultrasonically spraying an anode catalyst slurry onto a gas diffusion layer with a microporous layer;

[0014] (3) Preparation of cathode electrode. A cathode alkaline catalyst layer slurry is ultrasonically sprayed onto a gas diffusion layer with a microporous layer according to a designed pattern. The remaining area is sprayed with a cathode acidic catalyst layer slurry to obtain a patterned acid-base catalyst layer cathode electrode. This allows oxygen-containing gas to travel through the patterned cathode channels, with the path corresponding to alternating connections between the cathode acidic catalyst layer and the cathode alkaline catalyst layer, ultimately entering from the cathode acidic catalyst layer and exiting from the cathode alkaline catalyst layer. Preferably, the cathode alkaline catalyst layer slurry is first applied to one side of the gas diffusion layer surface, and the cathode acidic catalyst layer slurry is applied to the other side. Then, zigzag cathode channels are etched onto the obtained acid-base catalyst layer, with the cathode channels alternating between the cathode acidic catalyst layer and the cathode alkaline catalyst layer multiple times.

[0015] The joint between the alkaline catalytic layer and the acidic catalytic layer of the cathode can be straight or curved as needed, so as to adjust the ratio of the acidic catalytic layer flow and the alkaline catalytic layer flow during the process.

[0016] (4) Cathode electrode treatment; The alkaline cathode catalyst layer in the cathode patterned acid-base catalyst layer electrode prepared in step (3) needs to be ion exchanged with KOH solution and then washed with deionized water to obtain the acid-base mixed cathode electrode.

[0017] (5) The dried anode electrode and acid-base mixed cathode electrode after steps (1) and (4) are symmetrically stacked on both sides of the proton exchange membrane with the catalytic layers facing each other, and then processed by a hot press to generate a patterned acid-base catalytic membrane electrode.

[0018] The initial catalyst slurry used in step (1) includes: catalyst, ionomer, and dispersion solvent, with the mass ratio of the three components being 1:(2-4):(50-150).

[0019] The dispersion solvent used in the catalyst slurry is at least one of isopropanol, deionized water, ethanol, and ethyl acetate. The catalyst slurry is uniformly dispersed by ultrasonic ice bath for a dispersion time of 0.5 h to 8 h.

[0020] The anode catalyst is one or more of Pt catalysts or Pt alloy catalysts.

[0021] The cathode catalyst includes one or more of Pt catalysts, Pt alloy catalysts, or non-precious metal catalysts.

[0022] When the catalyst in the above slurry is a Pt alloy catalyst, the other metals in the Pt alloy are selected from at least one of Ni, Pd, Ru, Rh, Sn, W, Mo, and Os.

[0023] If the catalyst in the above slurry requires a carbon support, the carbon support used shall be selected from at least one of nano carbon black, carbon nanotubes, graphene, and fullerene.

[0024] When the cathode catalyst in the above slurry is a non-precious metal catalyst, the non-precious metal is selected from at least one of Ag, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn.

[0025] The ionomer in the aforementioned anode catalyst slurry is selected from at least one of perfluorosulfonic acid, partially fluorinated sulfonic acid, and non-fluorosulfonic acid solution. Its function is to effectively bind catalyst particles and conduct protons.

[0026] The ionomer in the catalyst slurry used in the above-mentioned cathode acidic catalyst layer is a cation exchange ionomer, selected from at least one of perfluorosulfonic acid, partially fluorinated sulfonic acid, and non-fluorosulfonic acid solution.

[0027] The ionomer in the catalyst slurry used in the above-mentioned cathode alkaline catalyst layer is an anion exchange ionomer, and the type is selected from at least one of quaternary ammonium type, imidazolide type, guanidine type and quaternary phosphorus type ionomers.

[0028] In step (1) of this invention, the ionomer in the catalyst layer slurry accounts for 5%-45% of the dry weight of the catalyst layer.

[0029] In step (3) of this invention, the alkaline catalyst layer occupies 1%-99% of the area of ​​the cathode catalyst layer.

[0030] In step (4) of this invention, the electrode with the alkaline catalyst layer needs to undergo ion exchange with KOH solution, with a solution concentration of 0.1-10 mol / L.

[0031] In step (5) of this invention, the hot pressing pressure is 50-1000 psi, the hot pressing temperature is 30-130℃, and the hot pressing time is 1-20 min; after hot pressing, the membrane electrode is prepared.

[0032] The fuel cell obtained by this invention operates under gas conditions with a relative humidity of less than 25%.

[0033] The mechanism of the cathode acid-base mixed catalytic membrane electrode is as follows (see appendix). Figure 1① During the reaction at the cathode side of the membrane electrode, low-humidity oxygen / air passes through the acidic catalyst layer to generate water; ② Water-containing gas is carried to the catalyst layer containing alkaline ionomers, where oxygen / air reacts with water to generate hydroxide ions; ③ Hydroxide ions are transported to the vicinity of the membrane through the alkaline ionomer crosslinking network, where they react with hydrated hydrogen ions from the anode to generate a large amount of water. This water is used to replenish the proton exchange membrane reaction, increase the overall humidity of the cathode catalyst layer, and prevent water shortage in the membrane under low humidity conditions, which would lead to performance degradation.

[0034] The beneficial effects of this invention are:

[0035] (1) The present invention does not require a complicated preparation process to obtain an acid-base mixed catalytic layer membrane electrode for use in proton exchange membrane batteries with a wide humidity range. The membrane electrode has stable performance, which helps to reduce dependence on gas humidification systems and reduce equipment costs.

[0036] (2) In this invention, the range of ionomers required for the preparation of alkaline catalyst layer is wide, and suitable ionomers can be selected from multiple perspectives such as performance, economy and working conditions, thereby improving the robustness of the solution.

[0037] (3) In this invention, the alkaline catalyst layer is directly deposited on the gas diffusion layer electrode to form a tight gas diffusion layer / catalyst layer interface, which facilitates the transport of reactants such as water and improves water management capabilities.

[0038] (4) In this invention, the proportion of alkaline catalyst layer is adjustable. A suitable proportion can be selected according to specific humidity requirements to achieve the performance and lifespan of the membrane electrode to meet actual needs. Attached Figure Description

[0039] Figure 1 This is a schematic diagram illustrating the operating principle of a patterned acid-base catalytic membrane electrode.

[0040] Figure 2 This is a schematic diagram of a patterned acid-base catalytic membrane electrode and a single cell assembly.

[0041] Figure 3 These are scanning electron microscope (SEM) images of the acidic and basic catalyst layers.

[0042] Figure 4 The power density curves of the membrane electrodes of Examples 1, 2, 3, and 4 are shown at 10% relative humidity.

[0043] Figure 5 The power density curves of the membrane electrodes of Examples 1, 2, 3, and 4 at 25% relative humidity are shown. Detailed Implementation

[0044] Specific embodiments are provided to illustrate the present invention. It should be noted that the embodiments are for illustrative purposes only and should not be construed as limiting the present invention in any way.

[0045] The anode catalyst layer and cathode acidic catalyst layer slurry used in the embodiments and comparative examples of this invention were prepared by the following method: 20 mg of 60% Pt / C catalyst was taken, 865 μL of deionized water was added to wet the catalyst, then 1867 μL of isopropanol was added, and acidic ionomer (perfluorosulfonic acid type ionomer, Nafion-D521) was added so that the ionomer accounted for 25% of the dry weight of the slurry. The catalyst was placed in an ice bath and sonicated for 0.5 h to make the ionomer evenly adhere to the catalyst particles. Then, 3863 μL of isopropanol was added, and sonication in an ice bath was continued for 6 h.

[0046] The cathode alkaline catalyst slurry used in the embodiments and comparative examples of this invention was prepared by the following method: 20 mg of 60% Pt / C catalyst was taken, 865 μL of deionized water was added to wet the catalyst, then 2000 μL of isopropanol was added, and an alkaline ionomer (quaternary ammonium ionomer, Piperion TP-100) was added so that the ionomer accounted for 30% of the dry weight of the slurry. The catalyst was placed in an ice bath and sonicated for 0.5 h to make the ionomer adhere evenly to the catalyst particles. Then, 4515 μL of isopropanol was added, and sonication in an ice bath was continued for 6 h.

[0047] In the embodiments and comparative examples of this invention, the anode electrodes were prepared using the following method: An acidic catalyst slurry was sprayed onto the microporous side of a 5cm*5cm commercial gas diffusion layer SGL-29BC using a 1.8W ultrasonic nozzle, resulting in an anode Pt loading of 0.2 mg / cm³. 2 .

[0048] Example 1

[0049] (1) The area of ​​the catalyst layer in the cathode electrode used in Example 1 is 5cm*5cm, of which the area of ​​the acidic catalyst layer is 5cm*3.75cm and the area of ​​the alkaline catalyst layer is 5cm*1.25cm, as shown in the schematic diagram. Figure 2 As shown.

[0050] (2) Using an ultrasonic nozzle with an ultrasonic power of 1.8W, an alkaline catalyst layer slurry was sprayed onto the microporous side of the commercial gas diffusion layer SGL-29BC, followed by the spraying of an acidic catalyst layer slurry to form a catalyst layer with the area shown in step (1), wherein the cathode Pt loading is 0.4 mg / cm². 2 The alkaline catalyst layer needs to be immersed in a 1 mol / L KOH solution for ion exchange, and then washed with deionized water to obtain the cathode electrode of Example 1.

[0051] (3) The cathode electrode of Example 1 and the prepared anode electrode were placed symmetrically on both sides of the commercial proton exchange membrane N211 with the catalytic layer as the opposite side. After being subjected to pressure treatment in a hot press at a temperature of 45°C, a pressure of 500 psi, and a time of 5 min, the membrane electrode of Example 1 was obtained.

[0052] Example 2

[0053] (1) The area of ​​the catalyst layer in the cathode electrode used in Example 2 is 5cm*5cm, of which the area of ​​the acidic catalyst layer is 5cm*2.5cm and the area of ​​the alkaline catalyst layer is 5cm*2.5cm, as shown in the schematic diagram. Figure 2 As shown.

[0054] (2) Using an ultrasonic nozzle with an ultrasonic power of 1.8W, an alkaline catalyst slurry was sprayed onto the microporous side of the commercial gas diffusion layer SGL-29BC to obtain a catalyst layer with dimensions of 5cm*2.5cm. Subsequently, an acidic catalyst slurry was sprayed to form a catalyst layer with the area shown in step (1), wherein the cathode Pt loading was 0.4mg / cm². 2 The alkaline catalyst layer needs to be immersed in a 1 mol / L KOH solution for ion exchange, and then washed with deionized water to obtain the cathode electrode of Example 2.

[0055] (3) The cathode electrode of Example 2 and the prepared anode electrode were placed symmetrically on both sides of the commercial proton exchange membrane N211 with the catalytic layer as the opposite side. After being treated by a hot press at a temperature of 45°C, a pressure of 500 psi, and a time of 5 min, the membrane electrode of Example 2 was obtained.

[0056] Example 3

[0057] (1) The area of ​​the catalyst layer in the cathode electrode used in Example 3 is 5cm*5cm, of which the area of ​​the acidic catalyst layer is 5cm*4.375cm and the area of ​​the alkaline catalyst layer is 5cm*0.625cm, as shown in the schematic diagram. Figure 2 As shown.

[0058] (2) Using an ultrasonic nozzle with an ultrasonic power of 1.8W, an alkaline catalyst slurry was sprayed onto the microporous side of the commercial gas diffusion layer SGL-29BC to obtain a catalyst layer with dimensions of 5cm*0.625cm. Subsequently, an acidic catalyst slurry was sprayed to form a catalyst layer with the area shown in step (1), wherein the cathode Pt loading was 0.4mg / cm². 2 The alkaline catalyst layer needs to be immersed in a 1 mol / L KOH solution for ion exchange, and then washed with deionized water to obtain the cathode electrode of Example 3.

[0059] (3) The cathode electrode of Example 3 and the prepared anode electrode were placed symmetrically on both sides of the commercial proton exchange membrane N211 with the catalytic layer as the opposite side. After being subjected to pressure treatment in a hot press at a temperature of 45°C, a pressure of 500 psi, and a time of 5 min, the membrane electrode of Example 3 was obtained.

[0060] Comparative Example 4

[0061] (1) The area of ​​the catalyst layer in the cathode electrode used in Comparative Example 4 is 5cm*5cm, of which the area of ​​the acidic catalyst layer is 5cm*5cm and there is no alkaline catalyst layer.

[0062] (2) An acidic catalyst slurry was sprayed onto the microporous side of the commercial gas diffusion layer SGL-29BC using an ultrasonic nozzle with an ultrasonic power of 1.8W, resulting in a catalyst layer with dimensions of 5cm*5cm, wherein the cathode Pt loading was 0.4mg / cm². 2 Based on this, the cathode electrode of Comparative Example 4 was obtained.

[0063] (3) The cathode electrode of Comparative Example 4 and the prepared anode electrode were symmetrically placed on both sides of a commercial proton exchange membrane N211 with the catalytic layer facing each other. After pressure treatment in a hot press at 45°C, 500 psi, and 5 min, the membrane electrode of Comparative Example 4 was obtained. It should be noted that the cathode electrodes of the membrane electrodes of Examples 1, 2, and 3 all contain an alkaline catalytic layer, wherein the area ratio of the acidic catalytic layer to the alkaline catalytic layer is as follows: Example 1 (75%:25%), Example 2 (50%:50%), and Example 3 (87.5%:12.5%), respectively. Scanning electron microscope images of the acidic and alkaline catalytic layers are shown below. Figure 3 In contrast, the cathode electrode of Comparative Example 4 does not contain an alkaline catalytic layer; its catalytic layer is entirely acidic.

[0064] The membrane electrode assemblies prepared in Examples 1, 2, 3, and Comparative Example 4 were tested in a hydrogen-oxygen fuel cell. Each example and comparative example required three repeated experiments. The testing procedures and environment were as follows: the active area of ​​the fuel cell test fixture was 25 cm². 2 The battery temperature is 80℃, the gas inlet flow rate (H2 / O2) is 0.8L / min, the dew point temperature is adjusted according to the humidity required for the experiment, and there is no back pressure.

[0065] The test results of the above-mentioned membrane electrode fuel cell under gas conditions with a relative humidity of 10% are as follows: Figure 4 The power densities corresponding to Examples 1, 2, and 3 are 918.71, 816.25, and 839.97 mW / cm², respectively. -2 The power density corresponding to Comparative Example 4 is 770.84 mW / cm³. -2Examples 1, 2, and 3 all outperformed Comparative Example 4. At 10% relative humidity, Example 1 exhibited a 19.18% higher peak power density compared to Comparative Example 4.

[0066] The test results of the above-mentioned membrane electrode fuel cell under gas conditions with a relative humidity of 25% are as follows: Figure 5 The power densities corresponding to Examples 1, 2, and 3 are 960.90, 851.85, and 900.42 mW / cm², respectively. -2 The power density corresponding to Comparative Example 4 is 840.07 mW / cm³. -2 At 25% relative humidity, the peak power density of Example 1 was increased by 14.38% compared to Comparative Example 4.

[0067] A comparison of Examples 1 with Examples 2 and 3 shows that, under the conditions of membrane electrode size, catalyst type, catalyst mass, ionomer type, and dry weight ratio of ionomer to catalyst, the alkaline catalyst layer area ratio relative to the overall catalyst layer is 25%, and the performance is best at 10% and 25% relative humidity.

[0068] As can be seen from the comparison between the examples and Comparative Example 4, regardless of the area ratio of the alkaline catalyst layer added to the cathode catalyst layer, the performance of the fuel cell under low humidity conditions is improved to a certain extent.

[0069] Traditional acid-base hybrid fuel cells typically employ a 100% alkaline catalyst layer at the cathode or anode electrode, or an acid-base composite membrane. This often results in water generation at the interface, limiting the fuel cell's performance under low humidity conditions; reported values ​​are typically around 500 mW / cm². -2 Within this range. In this example, Example 1 achieved a performance of 918.71 mW cm⁻¹ at 10% relative humidity. -2 This is one of the highest values ​​reported so far.

[0070] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Minor changes, such as the position and form of the alkaline catalyst layer in the cathode catalyst layer (e.g., multi-regional dispersion), are all within the scope of protection of the present invention.

[0071] Any modifications, variations, substitutions, and alterations made by those skilled in the art without changing the principles and spirit of this invention are within the scope of protection of this invention.

Claims

1. A method for preparing a patterned acid-base catalytic membrane electrode for a fuel cell, characterized in that, The patterned acid-base catalytic membrane electrode includes a proton exchange membrane body, a cathode electrode and an anode electrode disposed on both sides of the proton exchange membrane body; the electrode includes a catalytic layer and a gas diffusion layer; The catalytic layer in the cathode electrode is a patterned acid-base mixed catalytic layer; so that when oxygen-containing gas runs in the patterned cathode flow channel, the path it takes corresponds to the alternating connection of the cathode acidic catalytic layer and the cathode alkaline catalytic layer, and finally the gas enters from the cathode acidic catalytic layer and exits from the cathode alkaline catalytic layer. The catalyst layer in the anode electrode is only an acidic catalyst layer; Includes the following steps: (1) Preparation of catalyst layer slurry; Anode catalyst, acidic ionomer and solvent are mixed and ultrasonically mixed to obtain anode catalyst layer slurry; Cathode catalyst, acidic ionomer and solvent are mixed and ultrasonically mixed to obtain cathode acidic catalyst layer slurry; Cathode catalyst, basic ionomer and solvent are mixed and ultrasonically mixed to obtain cathode basic catalyst layer slurry; (2) Preparation of the anode electrode: The anode electrode is obtained by ultrasonically spraying the anode catalyst slurry onto the gas diffusion layer with a microporous layer; (3) Preparation of cathode electrode; The cathode alkaline catalyst layer slurry is ultrasonically sprayed onto the gas diffusion layer with microporous layer according to the designed pattern, and the remaining area is sprayed with cathode acidic catalyst layer slurry to obtain a patterned acid-base catalyst layer cathode electrode. When the oxygen-containing gas runs in the patterned cathode channel, the path it takes corresponds to the alternating connection of the cathode acidic catalyst layer and the cathode alkaline catalyst layer. Finally, the gas enters from the cathode acidic catalyst layer and exits from the cathode alkaline catalyst layer. The cathode alkaline catalyst layer slurry is first applied to one side of the gas diffusion layer surface and the cathode acidic catalyst layer slurry is applied to the other side. Then, zigzag cathode channels are etched on the patterned acid-base catalyst layer obtained above. The cathode channels alternately pass through the cathode acidic catalyst layer and the cathode alkaline catalyst layer in sequence, after multiple alternations. The joint between the alkaline catalytic layer and the acidic catalytic layer of the cathode can be straight or curved as needed, so as to adjust the ratio of the acidic catalytic layer flow and the alkaline catalytic layer flow during the process. (4) Cathode electrode treatment; The alkaline cathode catalyst layer in the cathode patterned acid-base catalyst layer electrode prepared in step (3) needs to be ion exchanged with KOH solution and then washed with deionized water to obtain the acid-base mixed cathode electrode. (5) The anode electrode and the acid-base mixed cathode electrode after being dried in steps (1) and (4) are symmetrically stacked on both sides of the proton exchange membrane with the catalytic layers facing each other, and then processed by a hot press to generate a patterned acid-base catalytic membrane electrode. The catalyst slurry in step (1) includes: catalyst, ionomer, and solvent, and the mass ratio of these three components is: 1:(2-4):(50-150).

2. The method according to claim 1, characterized in that, The dispersion solvent used in the catalyst slurry is at least one of isopropanol, deionized water, ethanol, and ethyl acetate. The catalyst slurry is uniformly dispersed by an ultrasonic ice bath.

3. The method according to claim 1, characterized in that, The anode catalyst is one or more of Pt catalysts or Pt alloy catalysts; The cathode catalyst includes one or more of Pt catalysts, Pt alloy catalysts, or non-precious metal catalysts. When the catalyst in the above slurry is a Pt alloy catalyst, the other metals in the Pt alloy are selected from at least one of Ni, Pd, Ru, Rh, Sn, W, Mo, and Os. If the catalyst in the above slurry requires a carbon support, the carbon support used shall be selected from at least one of nano carbon black, carbon nanotubes, graphene, and fullerene. When the cathode catalyst in the above slurry is a non-precious metal catalyst, the non-precious metal is selected from at least one of Ag, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn.

4. The method according to claim 1, characterized in that, The ionomer in the anode catalyst layer slurry is selected from at least one of perfluorosulfonic acid, partially fluorinated sulfonic acid, and non-fluorosulfonic acid solution. Its function is to effectively bind the catalyst particles and conduct protons. The ionomer in the above-mentioned cathode acidic catalyst layer slurry is a cation exchange ionomer, selected from at least one of perfluorosulfonic acid, partially fluorinated sulfonic acid, and non-fluorosulfonic acid solution; The ionomer in the above-mentioned cathode alkaline catalyst slurry is an anion exchange ionomer, and its type is selected from at least one of quaternary ammonium type, imidazolide type, guanidine type and quaternary phosphorus type ionomers; Step (1) The ratio of ionomers in the catalyst layer slurry to the dry weight of the catalyst layer is 5%-45% by mass.

5. The method according to claim 1, characterized in that, In step (3), the alkaline catalyst layer occupies 1%-99% of the area of ​​the cathode catalyst layer.

6. The method according to claim 1, characterized in that, In step (4), the electrode with the alkaline catalyst layer needs to undergo ion exchange with KOH solution, with a solution concentration of 0.1-10 mol / L.

7. The method according to claim 1, characterized in that, In step (5), the hot pressing pressure is 50-1000 psi, the hot pressing temperature is 30-130℃, and the hot pressing time is 1-20 min; after hot pressing, the membrane electrode is prepared.

8. The method according to claim 1, characterized in that, The working mode of the cathode acid-base mixed catalytic layer membrane electrode is as follows: ① When the membrane electrode reacts on the cathode side, low-humidity oxygen / air passes through the acidic catalytic layer to generate water; ② Water-containing gas is carried to the catalytic layer containing alkaline ionomers, where oxygen / air reacts with water to generate hydroxide ions; ③ Hydroxide ions are transported to the vicinity of the membrane through the alkaline ionomer crosslinking network, where they react with hydrated hydrogen ions from the anode to generate a large amount of water, which is used to replenish the proton exchange membrane reaction, increase the overall humidity of the cathode catalytic layer, and avoid performance degradation due to water shortage in the membrane under low humidity.

9. The method according to claim 1, characterized in that, The resulting fuel cell operates under gaseous conditions with a relative humidity of less than 25%.

10. A patterned acid-base catalytic membrane electrode for a fuel cell prepared by the method according to any one of claims 1-9.

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