A method for constructing a high-performance ion membrane and catalyst layer interface

Abstract

A method for constructing an ion membrane and a catalytic layer interface, comprising: step 1: regulating the ion membrane to be in a specific state; step 2: preparing a cathode catalyst ink and an anode catalyst ink; step 3: setting the coating temperature to 20-60 DEG C, coating the cathode catalyst ink on one of the sides of the ion membrane in the specific state, in the last stage of the process, the coating temperature is raised to 61-80 DEG C until the coating is completed, forming a cathode catalytic layer; step 4: setting the temperature of the coating platform to 20-60 DEG C, coating the anode catalyst ink on the side of the ion membrane which has not been coated, in the last stage of the process, the coating temperature is raised to 61-80 DEG C until the coating is completed, forming an anode catalytic layer, the method makes the catalytic layer and the ion membrane combine more closely, optimizes the mass transfer path, reduces the interface impedance, forms a block of direct contact between the catalyst and the ionomer, and constructs a three-dimensional network structure.

Description

Technical Field

[0001] This invention relates to the field of membrane electrode technology for automotive fuel cells, and in particular to a method for constructing an interface between an ion exchange membrane and a catalyst layer. Background Technology

[0002] With global focus on clean energy and sustainable development, new energy vehicles are gradually becoming the development direction of the automotive industry. Fuel cell vehicles, with their advantages of high energy density and zero emissions, have attracted much attention. As their core power source, fuel cells are expected to replace traditional fossil fuels, and the performance of the membrane electrode assembly (MEA) directly affects the output power and efficiency of the fuel cell system, thus determining the performance and competitiveness of fuel cell vehicles. To date, MEA fabrication technology has gone through three generations. The first generation is called Gas Diffusion Electrode (GDE), which typically uses screen printing to prepare the catalyst layer onto the diffusion layer. The second generation is the Catalyst Coated Membrane (CCM) fabrication method, which prepares the catalyst layer onto the membrane, and is currently the mainstream MEA fabrication technology. Compared with the first generation method, this method reduces the proton transport resistance between the catalyst layer and the ion exchange membrane, improving the performance of the MEA and the utilization and durability of the catalyst to a certain extent. The third generation of MEAs is the ordered MEA. Given the high cost of fabricating ordered membrane electrodes, current development is limited to laboratories or miniaturization. Therefore, the most widely used, most applied, and most promising fabrication technology for commercialization remains CCM fabrication technology.

[0003] The core of CCM preparation technology lies in maximizing the optimal performance of each material. However, current coating processes directly coat the catalyst onto the ion exchange membrane, resulting in insufficient contact between the catalyst layer and the membrane. Furthermore, during coating, solvent evaporation creates numerous bubbles at the catalyst-membrane interface, affecting mass transfer and moisture management during operation, increasing the contact impedance of the membrane electrode, and ultimately hindering its full performance. Modifying the catalyst layer structure or improving the ion exchange membrane structure increases the preparation cost of the membrane electrode. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for constructing an interface between an ion exchange membrane and a catalyst layer, so as to solve the technical problem of insufficient contact between the ion exchange membrane and the catalyst layer.

[0005] To achieve the above objectives, the present invention provides a method for constructing an interface between an ion exchange membrane and a catalyst layer, comprising:

[0006] Step 1: Adjust the ion exchange membrane to a specific state, which is any one or more combinations of swelling, phase transition, and opening and closing of chemical bonds;

[0007] Step 2: Prepare cathode catalyst ink and anode catalyst ink;

[0008] Step 3: Set the coating temperature to 20-60℃ and coat the cathode catalyst ink on one of the sides of the ion membrane in a specific state. In the final stage of this process, raise the coating temperature to 61-80℃ until the coating is completed and the cathode catalyst layer is formed.

[0009] Step 4: Set the temperature of the coating platform to 20-60℃. Coat the anolyte catalyst ink on the side of the ion exchange membrane that has not yet been coated. In the final stage of this process, raise the coating temperature to 61-80℃ until the coating is completed and the anolyte catalyst layer is formed.

[0010] Optionally, both the cathode catalyst ink and the anode catalyst ink are prepared from a specific solvent A, a catalyst, and an ionomer. The specific solvent A is a mixed solution of water and isopropanol, and the I / C ratio of both the cathode catalyst ink and the anode catalyst ink is 0.5-1.

[0011] Optionally, both the cathode catalyst ink and the anode catalyst ink include catalyst ink B and catalyst ink C;

[0012] In step 2, catalyst ink B is prepared from a specific solvent A and a catalyst, and catalyst ink C is prepared from a specific solvent A, a catalyst, and an ionomer; the specific solvent A is a mixed solution of water and isopropanol.

[0013] In step 3, the temperature of the coating platform is set to 20-60℃. First, catalyst ink B is used to coat the X-axis and Y-axis serpentine channels in a cyclic manner for 1-20 minutes. Then, the temperature is increased to 61-80℃ until catalyst ink B is completely coated. Then, catalyst ink C is used to coat the X-axis and Y-axis serpentine channels in a cyclic manner until the coating is completed.

[0014] In step 4, the temperature of the coating platform is set to 20-60℃. First, catalyst ink B is used to coat the X-axis and Y-axis serpentine channels in a cyclic manner for 1-20 minutes. Then, the temperature is increased to 61-80℃ until catalyst ink B is completely coated. Then, catalyst ink C is used to coat the X-axis and Y-axis serpentine channels in a cyclic manner until the coating is completed.

[0015] Optionally, the I / C ratio of catalyst ink B is 0:1; and the I / C ratio of catalyst ink C is 0.5-1.

[0016] Optionally, after step 3 and before step 4, the ion membrane coated with the cathode catalyst layer is re-regulated to bring it back to a specific state.

[0017] Optionally, in step 1, the control method is to heat the ion membrane to 90-150°C, or to use a specific solvent, hereinafter referred to as specific solvent B, to perform a specific treatment on the ion membrane. The treatment method includes soaking, soaking while heating, spraying, spraying and etching, and spraying, etching and heating.

[0018] Optionally, the specific solvent B is water, or a combination of water with any one of an alcohol, acid or base, or a combination of an alcohol, acid and water, or a combination of an alcohol, base and water.

[0019] Optionally, during the control process, a specific solvent B is used for spraying treatment only on one side of the ion membrane, either the cathode side or the anode side, or a combination of spraying, etching, and heating treatment.

[0020] Optionally, when the alkaline ion exchange membrane is soaked in a specific acidic solvent B, or when the acidic ion exchange membrane is soaked in a specific alkaline solvent B, the alkaline or acidic ion exchange membrane needs to be soaked again in a solvent with the same acidity or alkalinity after the catalyst layer is sprayed.

[0021] Optionally, the catalyst is a platinum-carbon catalyst or a platinum-ruthenium catalyst, and the solid content of the catalyst in the catalyst ink is 2 mg / mL.

[0022] The beneficial effects of the principle of this invention are as follows: The membrane electrode prepared by the method of this invention utilizes the properties of the ion exchange membrane itself, and constructs a highly efficient ion and gas transport channel by inducing and regulating the swelling, phase transition, and reversible structural changes of the chemical bonds in the ion exchange membrane. This forms a barrier to direct contact between the catalyst and the ionomer, constructing a three-dimensional network structure, thereby improving the activity and stability of the membrane electrode; it reduces the interfacial separation phenomenon between the catalyst layer and the ion exchange membrane, making the catalyst layer and the ion exchange membrane more tightly bonded, simplifying the mass transport path, and reducing interfacial impedance; it reduces the microbubbles generated in the conventional coating process, which is beneficial for the water vapor management of the membrane electrode; and it reduces the hydrogen permeability of the membrane electrode due to the partial permeation of catalyst particles into the ion exchange membrane.

[0023] The method of this invention does not require complicated steps, the preparation conditions are easy to control, and it effectively improves the performance of membrane electrodes at zero cost. It can achieve fine control of membrane electrodes in the laboratory and can achieve large-scale fully automated production of membrane electrodes in industrial production. It has broad application prospects in fuel cells.

[0024] Alcohol solvents can effectively improve the swelling and dissolution state of the membrane, while acids or bases can convert the effective functional groups of ionomers in the ion-exchange membrane into ionic forms. Heating and other methods can alter the phase transition of the ion-exchange membrane. These methods allow the catalyst ink to more easily penetrate into the ion-exchange membrane, forming a more tightly bound catalytic layer and ion-exchange membrane combined structure, thus improving the gas-liquid-mass transport channels. Furthermore, the dispersed catalyst can partially form a more dispersed three-dimensional network structure within the membrane, increasing the number of three-phase points and enhancing the catalyst's reactivity. Attached Figure Description

[0025] Figure 1 A schematic comparison diagram of the membrane electrode (b) prepared according to an embodiment of the present invention and the membrane electrode (a) prepared by a conventional method;

[0026] Figure 2 This refers to the serpentine flow channel coating step in Examples 1-9 of the present invention;

[0027] Figure 3 In Example 1 and Comparative Example 1 of the present invention, the anode and cathode loadings were 0.4 and 0.1 mg Pt / cm³, respectively. 2 High-load spray film electrode 1 and high-load conventional coating prepared 25cm 2 Comparison of polarization curves and power curves of membrane electrode 9 under constant hydrogen-air stoichiometric operating conditions;

[0028] Figure 4 In Example 2 and Comparative Example 2 of the present invention, the anode and cathode loadings were 0.4 and 0.1 mg Pt / cm³, respectively. 2 High-load immersion heating film electrode 2 and high-load conventional coating prepared 25cm 2 Comparison of polarization curves and power curves of membrane electrode 10 under constant hydrogen-air stoichiometric operating conditions;

[0029] Figure 5 In Example 3 and Comparative Example 3 of the present invention, the anode and cathode loadings were 0.05 and 0.05 mg Pt / cm³, respectively. 2 Ultra-low load phase separation membrane electrode 3 and 25cm low load conventional coating prepared 2 Comparison of polarization curves and power curves of membrane electrode 11 under constant hydrogen-air stoichiometric operating conditions;

[0030] Figure 6 In Example 4 and Comparative Example 3 of the present invention, the anode and cathode loadings were 0.05 and 0.05 mg Pt / cm³, respectively. 2 Ultra-low load etched film electrode 4 and 25cm low load conventional coating prepared 2 Comparison of polarization curves and power curves of membrane electrode 11 under constant hydrogen-air stoichiometric operating conditions;

[0031] Figure 7In Example 5 and Comparative Example 3 of the present invention, the anode and cathode loadings were 0.05 and 0.05 mg Pt / cm³, respectively. 2 Ultra-low grade wet spray film electrode 5 and 25cm low load conventional coating prepared by conventional coating 2 Comparison of polarization curves and power curves of membrane electrode 11 under constant hydrogen-air stoichiometric operating conditions;

[0032] Figure 8 This is a comparison of the polarization curves and power curves of the membrane electrode 6 of Embodiment 6 and the membrane electrode 11 of Comparative Example 3 under constant hydrogen-air ratio operating conditions.

[0033] Figure 9 This is a comparison of the polarization curves and power curves of the membrane electrode 7 of Embodiment 7 and the membrane electrode 11 of Comparative Example 3 under constant hydrogen-air ratio operating conditions.

[0034] Figure 10 In Example 9 of this invention, the anode and cathode loadings were 0.2 mg PtRu / cm³. 2 and 0.2 mg Pt / cm 2 Alkaline wet-spray coated film electrode 8 and conventionally coated 5cm 2 Comparison of polarization curves and power curves of membrane electrode 12 under constant hydrogen-oxygen ratio operating conditions. Detailed Implementation

[0035] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0036] Example 1: One side of the ion exchange membrane is swollen.

[0037] This embodiment uses a method for constructing an interface between an ion exchange membrane and a catalytic layer to prepare a 25cm... 2 Membrane electrode 1, the specific method steps include:

[0038] First, the M778.12 acidic ion-exchange membrane is cut into a 7×7cm square. The ion-exchange membrane is then regulated to a specific state, involving any combination of swelling, phase transition, and the opening and closing of chemical bonds. Different regulation methods result in different specific states of the ion-exchange membrane. In this example, the regulation method involves using a specific solvent, hereinafter referred to as specific solvent B, to perform a specific treatment on the ion-exchange membrane. This treatment method is spraying. Specifically, the clean ion-exchange membrane is placed on a coating platform, and then a small amount of specific solvent B is sprayed onto the cathode side surface of the ion-exchange membrane. Specific solvent B is a mixed solvent of water and acid, specifically a 1% sulfuric acid solution. This causes the cathode side of the ion-exchange membrane to reach and be in a swollen state, while the other side remains essentially dry. In other embodiments, the specific acidic solvent B can also be sulfuric acid, hydrochloric acid, or nitric acid. Acidic solvents can maintain the protonation of the sulfonic acid groups in the acidic ion-exchange membrane for a long time, so using other acidic solvents can achieve the same effect as in this example. Alternatively, if the ion-exchange membrane is alkaline, the specific solvent B can be a mixture of water and alkali, which can also keep the ion-exchange membrane in a swollen state, resulting in a membrane electrode with the same effect as in this embodiment. Besides spraying, the control method can also be spraying and etching, with the same effect as in this embodiment. In this example, the ion-exchange membrane can also be any type of ion-exchange membrane, i.e., any commercially available or self-made acidic ion-exchange membrane, with the same effect as in this embodiment. It should be noted that when an acidic solvent corresponds to an acidic ion-exchange membrane or an alkaline solvent corresponds to an alkaline ion-exchange membrane, only the ion-exchange membrane is in a swollen state; when an alkaline solvent corresponds to an acidic ion-exchange membrane or an acidic solvent corresponds to an alkaline ion-exchange membrane, the ion-exchange membrane has both swollen and chemically bonded states.

[0039] Then, using a specific solvent A, catalyst, and ionomer, cathode catalyst ink and anode catalyst ink were prepared, respectively. In this example, the platinum loadings of the prepared membrane electrode anode and cathode were 0.4 mg / cm³, respectively. 2 and 0.1 mg / cm 2 (Catalystloading: 0.4 / 0.1mg) Pt / cm 2 This means that the platinum loading of the cathode catalyst layer is required to be 0.4 mg / cm³. 2 The platinum loading of the anode catalyst layer is 0.1 mg / cm³. 2Specifically, according to the platinum loading at the membrane electrode cathode, a corresponding mass of platinum-carbon catalyst (Pt / C catalyst) is weighed out. A mixed solution of water and isopropanol in a volume ratio of 1:4 is used as specific solvent A, maintaining the solid content of the platinum-carbon catalyst in specific solvent A at 2 mg / mL. Then, a certain amount of D520 ionomer (ionomer:D520) is added, maintaining the I / C ratio (the ratio of carbon in the ionomer to the catalyst) at 0.5-1. In this example, maintaining the I / C ratio at 0.5 is preferred. The solution is then ultrasonically dispersed uniformly and used as the cathode catalyst ink. Similarly, according to the platinum loading at the membrane electrode anode, a corresponding mass of Pt / C catalyst is weighed out. A mixed solution of water and isopropanol in a volume ratio of 1:4 is used as specific solvent A, maintaining the solid content of the platinum-carbon catalyst in specific solvent A at 2 mg / mL. Then, a certain amount of D520 ionomer is added, maintaining the I / C ratio at 0.5-1. In this example, maintaining the I / C ratio at 0.5 is preferred. The solution is then ultrasonically dispersed uniformly and used as the anode catalyst ink.

[0040] In other embodiments of the present invention, the catalyst may be a noble metal catalyst or a non-noble metal catalyst, or any combination of noble metal catalysts and / or non-noble metal catalysts, wherein the noble metal catalyst is such as palladium catalyst, rhodium catalyst, etc., and the non-noble metal catalyst is such as iron-based catalyst, cobalt-based catalyst, etc. The amount of the catalyst used is as described in this embodiment, and the same or similar effects as those described in the embodiments of this application can be achieved.

[0041] Next, a 5×5cm serpentine flow channel coating area is set in the center of the ion exchange membrane, and the cathode catalyst ink is placed in the coating equipment.

[0042] The coating platform is opened, and its temperature is set to 20-60℃. On one side of the ion-exchange membrane in a specific state, the cathode catalyst ink is sequentially coated using an X-axis serpentine flow channel and then a Y-axis serpentine flow channel for 1-20 minutes. The temperature is then increased to 61-80℃ until coating is complete, forming the cathode catalyst layer. In this example, the temperature is set to 20℃ and the coating time is 20 minutes to achieve good contact between the cathode catalyst layer and the ion-exchange membrane interface, reducing phase separation and achieving three-dimensional dispersion of the catalyst, thus improving the performance of membrane electrode 1. In some other embodiments, the initial temperature is set to 20-60℃, with similar effects to this embodiment; then the temperature is increased to 80℃ until coating is complete, forming the cathode catalyst layer. Increasing the coating platform temperature is for rapid drying of the ion-exchange membrane, so heating to any temperature within 61-80℃ has the same effect. The X-axis and Y-axis serpentine flow channel coating methods are as follows: Figure 2 As shown.

[0043] The ion membrane coated with the cathode-side catalyst layer is flipped and attached to the coating platform and fixed. The anode catalyst ink is placed in the coating equipment, and the temperature of the coating platform is set to 80°C. On the other side of the ion membrane coated with the cathode catalyst layer, the anode catalyst ink is coated in the X-axis serpentine flow channel and the anode catalyst ink is coated in the Y-axis serpentine flow channel in sequence until the coating is completed and the anode catalyst layer is formed.

[0044] The cutting area is 5×5cm 2 The gas diffusion layer is hot-pressed to form the film electrode 1, such as... Figure 1 As shown in (b).

[0045] Under the operating conditions of H2 / Air (hydrogen / air) reactant gases and a H2 / Air stoichiometric ratio of 2:2, the membrane electrode 1 was tested using a fuel cell testing system, and the results are as follows: Figure 3 As shown in the figure. The left vertical axis represents E / V (voltage), the right vertical axis represents P / W (power density), and the horizontal axis represents j / A (current density). The peak power density of membrane electrode 1 is 1.61 W / cm². -2 The maximum current density is 3.36 Acm. -2 The peak power density of the membrane electrode 9, used in Comparative Example 1, was 1.45 W / cm². -2 The maximum current density is 2.71 Acm. -2 The values ​​are all lower than those of membrane electrode 1. In this embodiment, the anode of membrane electrode 1 is coated using the same spraying method as the anode of membrane electrode 9 in Comparative Example 1. This indicates that, based on the same anode side, the cathode sprayed membrane electrode 1, prepared by spraying to allow the ion membrane to swell on one side, exhibits increased porosity in the acidic ion membrane after water and acid spraying and swelling. Furthermore, the liquid-saturated membrane allows the cathode catalyst ink to more easily enter the acidic ion membrane, causing the cathode catalyst layer interface and the proton exchange membrane interface to interweave, forming a three-dimensional catalyst network structure. In addition, the cathode catalyst layer and anode catalyst layer of the membrane electrode 1 prepared in this embodiment are tightly bonded without the formation of obvious pore structures, reducing phase separation and thus exhibiting excellent performance. In contrast, during the spraying process of membrane electrode 9 in Comparative Example 1, because the liquid ink directly contacts the dry solid membrane, the two phases cannot completely overlap. Therefore, small ink particles bounce on the dry membrane surface, resulting in the formation of dense mesopores (such as...) at the interface. Figure 1 (a) shows that the disruption of water vapor management leads to an increase in contact resistance, which in turn causes a decrease in performance. In addition, due to the differences in the catalytic reactions and catalyst types at the anode and cathode of acid and alkaline fuel cells, using a spraying method rather than soaking to control the ion membrane to be in a unilateral swelling state is beneficial for studying the unilateral catalyst layer and ion membrane interface.

[0046] Example 2: Controlling the swelling and phase transition state of the ion exchange membrane

[0047] This embodiment uses a method for constructing an interface between an ion exchange membrane and a catalytic layer to prepare a 25cm... 2 Membrane electrode 2, the specific method steps include:

[0048] Cut the M778.12 ion exchange membrane into 7×7cm squares. Immerse the clean ion exchange membrane in water (corresponding to specific solvent B) and simultaneously heat the membrane to 95°C to achieve both swelling and phase transition. Store for later use. Heating to 90-150°C induces a phase transition in the ion exchange membrane; heating to 90-150°C has essentially the same effect as heating to 95°C, while immersion induces swelling. This method allows the catalyst ink to more easily penetrate the ion exchange membrane, forming a more tightly integrated catalytic layer and ion exchange membrane structure, thus improving the gas-liquid-mass transport channel. In other embodiments, the specific solvent B can also be a combination of water and an acid or base. Acidic solvents correspond to acidic ion exchange membranes, and basic solvents correspond to basic ion exchange membranes. Using a mixture of water and an acidic or basic solvent is more effective than using water alone because placing the ion exchange membrane in the corresponding acid or base solution—that is, placing the acidic ion exchange membrane in an acidic environment and the basic ion exchange membrane in a basic environment—allows the effective functional groups of the ion exchange membrane to remain in a functional group mode for a longer period. However, prolonged exposure to water causes the functional groups of the ion exchange membrane to gradually transform into ionic forms, which is detrimental to ion transport in the membrane electrode assembly. In other embodiments, the ion exchange membrane can also be controlled to be in a swelling and phase transition state by spraying water onto it while heating it to 90-150°C, achieving similar effects to this embodiment.

[0049] In this embodiment, the platinum loading of the anode and cathode of the prepared membrane electrode is 0.4 mg / cm³, respectively. 2 and 0.1 mg / cm 2 According to the platinum loading at the membrane electrode cathode, a corresponding mass of Pt / C catalyst was weighed. A mixed solution of water and isopropanol in a volume ratio of 1:4 was used as specific solvent A. The solid content of the platinum-carbon catalyst in specific solvent A was maintained at 2 mg / mL. Then, a certain amount of D520 ionomer was added to maintain an I / C ratio of 1. After ultrasonic dispersion, the solution was prepared as the cathode catalyst ink for later use. According to the platinum loading at the membrane electrode anode, a corresponding mass of Pt / C catalyst was weighed. Water and isopropanol were used as specific solvent A. The solid content of the platinum-carbon catalyst in specific solvent A was maintained at 2 mg / mL. Then, a certain amount of D520 ionomer was added to maintain an I / C ratio of 1. After ultrasonic dispersion, the solution was prepared as the anode catalyst ink for later use.

[0050] A 5×5cm serpentine flow channel coating area is set in the center of the ion exchange membrane. The wet ion exchange membrane in a swollen state is directly attached to the coating device and fixed. The cathode catalyst ink is placed in the coating equipment.

[0051] The coating platform was opened and the temperature was set to 60°C. On the side of the ion membrane in the swollen and phase-change state, the cathode catalyst ink was coated in an X-axis serpentine flow channel and then in a Y-axis serpentine flow channel for 20 minutes. The ion membrane and the coating were at the same temperature to achieve further contact between the catalyst layer and the ion membrane interface, further reducing the phase separation state and improving the three-dimensional dispersion of the catalyst. This constructed a highly efficient ion and gas transport channel, resulting in a significant improvement in the performance of the membrane electrode 2. The temperature was then increased to 80°C until the coating was completed, forming the cathode catalyst layer.

[0052] The ion membrane coated with the cathode-side catalyst layer is flipped and attached to the coating platform and fixed. The anode catalyst ink is placed in the coating equipment, and the temperature of the coating platform is set to 60°C. On the other side of the ion membrane coated with the cathode catalyst layer, the anode catalyst ink is coated in the X-axis serpentine flow channel and then coated in the Y-axis serpentine flow channel in sequence for 20 minutes. Then the temperature is increased to 80°C until the coating is completed, forming the anode catalyst layer.

[0053] A gas diffusion layer with a cutting area of ​​5×5cm is formed into a membrane electrode 2 by hot pressing.

[0054] Under operating conditions where the reactant gases are H2 / Air and the gas stoichiometry ratio is 2:2, the membrane electrode 2 was tested using a fuel cell testing system, and the results are as follows: Figure 4 As shown in the figure. The left vertical axis represents E / V (voltage), the right vertical axis represents P / W (power density), and the horizontal axis represents j / A (current density). The membrane electrode 2 has a peak power density of 1.80 W / cm². -2 The maximum current density is 3.61 Acm. -2 The peak power density of the membrane electrode 10, used in Comparative Example 2, is 1.33 W / cm². -2 The maximum current density is 2.59 Acm. -2 Both are lower than those of membrane electrode 2. In the preparation of membrane electrode 2 in this embodiment, swelling places the ion exchange membrane in a solid-liquid mixed phase state saturated with liquid. Heating induces an α-transition phase change in the ion exchange membrane, causing the ion clusters of ionomers in the membrane to undergo a thermal transition from a tightly associated state to a weakened interaction state. The combined effects of swelling and phase separation further enhance the intercalation between the catalyst layer and the ionomers, allowing more catalyst to penetrate into the ion exchange membrane. Phase separation is further reduced, resulting in a complete ion transport channel. Although the anolyte I / C ratio of 1 may increase the poisoning of the catalyst by the ionomers, the overall performance of membrane electrode 2 is further enhanced. In contrast, the membrane electrode 10 of Comparative Example 2, which uses conventional spraying, exhibits lower performance than the comparative sample membrane electrode 10 due to the increased I / C ratio.

[0055] Example 3: Controlling the swelling and chemical bond opening / closing state of the ion exchange membrane

[0056] This embodiment uses a method for constructing an interface between an ion exchange membrane and a catalytic layer to prepare a 25cm... 2 Membrane electrode 3, the specific method steps include:

[0057] Cut the M778.12 acidic ion-exchange membrane into a square larger than 7×7cm. Immerse the clean ion-exchange membrane in a mixed solution of water, alcohol, and alkali. Specifically, solvent B is a mixture of water, alcohol, and alkali. In this example, the alcohol is ethanol, the alkali is potassium hydroxide, and the ratio of water, ethanol, and potassium hydroxide is 20:1:5. This achieves a state where the ion-exchange membrane swells and chemical bonds open simultaneously. Store for later use. Besides ethanol, other alcohol solvents such as methanol, isopropanol, n-propanol, cyclohexanol, ethylene glycol, glycerol, and propylene glycol can be used. Polar alcohol solvents, due to their dielectric properties and solvation capabilities, allow the effective polar functional groups (sulfonic acid groups) of the ionomer to be exposed, while the non-polar PTFE backbone remains trapped inside. Therefore, replacing ethanol with any of the above-mentioned alcohol solvents in this example can achieve similar results. Besides potassium hydroxide, other alkaline solvents such as sodium hydroxide, calcium hydroxide, iron hydroxide, ammonia, sodium carbonate, and sodium bicarbonate can be used. Alkaline solvents acting on the ion-exchange membrane can convert exposed polar functional groups (sulfonic acid groups) into sulfonate groups. Therefore, replacing potassium hydroxide with the aforementioned alkaline solvents can achieve similar effects to this example. In other embodiments, for alkaline ion-exchange membranes, the alkaline solvent in this example can be replaced with an acidic solvent, with the same effect. Besides immersion, spraying or a combination of etching and spraying can also achieve the same effect as in this example. Immersing, etching, or spraying an acidic ion-exchange membrane with a solvent mixture of water, alkali, and alcohol can induce the opening and closing of chemical bonds and swelling of the ion-exchange membrane. Immersing, etching, or spraying an alkaline ion-exchange membrane with a solvent mixture of water, acid, and alcohol can induce the opening and closing of chemical bonds and swelling of the ion-exchange membrane. Alcohol solvents can effectively improve the swelling and dissolution state of the membrane, while acid or base solvents can change the effective functional groups of the ionomer in the ion membrane into ionic form. Through the above methods, the catalyst ink can more easily penetrate into the ion membrane, forming a more tightly bound catalytic layer and ion membrane combined structure, thus improving the gas-liquid-mass transport channel.

[0058] In this embodiment, the platinum loading of the anode and cathode of the prepared membrane electrode is 0.05 mg / cm³, respectively. 2 and 0.05 mg / cm 2 According to the platinum loading of the membrane electrode anode and cathode, the corresponding mass of Pt / C catalyst was weighed out. Water and isopropanol were used as specific solvent A to maintain the solid content of platinum-carbon catalyst in specific solvent A at 2 mg / mL. Then, a certain amount of ionomer was added to maintain the I / C ratio at 0.5. After ultrasonic dispersion, the cathode catalyst ink and anode catalyst ink were obtained for later use.

[0059] A 5×5cm serpentine flow channel coating area is set in the center of the ion exchange membrane. The wet ion exchange membrane, which is in a state of swelling and chemical bond opening and closing, is directly attached to the coating device and fixed. The cathode catalyst ink is placed in the coating device.

[0060] The coating platform was opened and the temperature was set to 45°C. On one side of the ion membrane, the cathode catalyst ink was coated in an X-axis serpentine flow channel and then in a Y-axis serpentine flow channel for 5 minutes. This formed a barrier to direct contact between the catalyst and the cathode, thereby constructing a highly efficient ion and gas transport channel and a three-dimensional network structure to improve the activity and stability of the membrane electrode 3. The temperature was then increased to 80°C until the coating was completed, forming the cathode catalyst layer.

[0061] The ion exchange membrane coated with the cathode catalyst layer was immersed in a specific solvent B containing water, ethanol, and potassium hydroxide in a ratio of 20:1:5 for 10 minutes to allow the ion exchange membrane to swell and open and close its chemical bonds. Then, the anode side without the catalyst layer was attached to the platform and fixed. The anode catalyst ink was placed in the coating equipment, and the anode catalyst ink was coated in the X-axis serpentine flow channel and the Y-axis serpentine flow channel in sequence for 5 minutes. Then, the temperature was increased to 80°C until the coating was completed, forming the anode catalyst layer.

[0062] The acidic ion exchange membrane coated with the catalyst layer was immersed in a 5% sulfuric acid solution for 30 minutes. Because the previous process converted the sulfonic acid groups to sulfonate groups, this second immersion in acid further transformed the ion exchange membrane from sulfonate to sulfonic acid group form. Immersion also removed excess alkali, which is detrimental to acidic ion exchange membranes (as it alters effective functional groups). Subsequently, a gas diffusion layer with an area of ​​5×5 cm was cut and hot-pressed to form the membrane electrode 3.

[0063] It should be noted that in some other embodiments of the present invention, when a non-neutral ion exchange membrane is soaked in a specific solvent B with a non-neutral pH value not equal to 7, the alkaline or acidic ion exchange membrane needs to be soaked again in a solvent with the same acidity or alkalinity after the catalyst layer is sprayed. Specifically, when an alkaline ion exchange membrane is soaked in an acidic specific solvent B, the alkaline ion exchange membrane is soaked again in an alkaline solvent after the catalyst layer is sprayed; when an acidic ion exchange membrane is soaked in an alkaline specific solvent B, the acidic ion exchange membrane is soaked again in an acidic solvent after the catalyst layer is sprayed.

[0064] Under operating conditions where the reactant gases are H2 / Air and the gas stoichiometry ratio is 2:2, the membrane electrode 3 was tested using a fuel cell testing system, and the results are as follows: Figure 5As shown in the figure. The left vertical axis represents E / V (voltage), the right vertical axis represents P / W (power density), and the horizontal axis represents j / A (current density). The peak power density of membrane electrode 3 is 0.96 W / cm². -2 The maximum current density is 2.40 Acm. -2 Meanwhile, the membrane electrode 11, used in Comparative Example 3, achieved a peak power density of 0.72 W / cm². -2 The maximum current density is 1.81 Acm. -2 The values ​​were all lower than those of membrane electrode 3. When the ion-exchange membrane is in a swollen state, it is filled with liquid, forming a solid-liquid mixture. The effective functional groups of the ion-exchange membrane are in a state of chemical bond opening and closing through alcohol and base, similar to the ionomers in the catalyst ink. At the microscopic level, the ionomers are all water-in-oil structures, that is, the exposed polar functional groups sulfonic acid groups are on the outside, and the non-polar FTFE is on the inside. According to the principle of like dissolves like, the catalyst ink in this state will be more compatible with the acidic ion-exchange membrane, forming a dispersed catalyst in the acidic ion-exchange membrane, constructing a three-dimensional catalyst network and interconnected ion transport channels, effectively reducing the mass transfer impedance caused by membrane swelling and the charge transfer impedance caused by chemical bond opening and closing. In addition, under the conditions of reducing the catalyst loading of the anode and cathode to 8 times and 2 times that of Example 1, respectively, membrane electrode 3 still showed good performance, indicating that the application of swelling and chemical bond opening and closing is more suitable for membrane electrodes prepared with low catalyst loading. Furthermore, after completing the coating on one side, the other side was also treated with different states, realizing the control of both sides of the membrane. This embodiment provides guidance for achieving cost reduction and efficiency improvement in membrane electrodes. Correspondingly, the membrane electrode 11 of Comparative Example 3 exhibits the same behavior as the membrane electrode 9 of Comparative Example 1 with high loading, showing obvious disordered pore structure at the interface, which hinders water vapor management and ion transport, resulting in poor performance.

[0065] Example 4: Controlling the swelling and chemical bond opening / closing state of the ion exchange membrane

[0066] This embodiment uses a method for constructing an interface between an ion exchange membrane and a catalytic layer to prepare a 25cm... 2 Membrane electrode 4, the specific method steps include:

[0067] Cut the M778.12 ion exchange membrane into 7×7cm squares. Attach the clean ion exchange membrane to a coating platform. Apply a stainless steel mesh with a grid spacing of 0.5cm to the ion exchange membrane surface. Mix water, isopropanol, and ethanol in a 20:1:1 ratio using a specific solvent B. Spray solvent B onto the blank spaces of the stainless steel mesh to etch the ion exchange membrane for 10 minutes, allowing it to swell and partially open / close chemical bonds. Then store it for later use. It should be noted that the "jia" in this paragraph...

[0068] In this embodiment, the platinum loading of the anode and cathode of the prepared membrane electrode is 0.05 mg / cm³, respectively. 2 and 0.05 mg / cm 2 According to the platinum loading of the membrane electrode anode and cathode, the corresponding mass of Pt / C catalyst was weighed out. Water and isopropanol were used as specific solvent A to maintain the solid content of platinum-carbon catalyst in specific solvent A at 2 mg / mL. Then, a certain amount of ionomer was added to maintain the I / C ratio at 0.5. After ultrasonic dispersion, the cathode catalyst ink and anode catalyst ink were obtained for later use.

[0069] A 5×5cm serpentine flow channel coating area is set in the center of the ion exchange membrane. The wet ion exchange membrane, which is in a state of swelling and chemical bond opening and closing, is directly attached to the coating device and fixed. The cathode catalyst ink is placed in the coating device.

[0070] Turn on the coating platform and set its temperature to 45°C. On one side of the ion exchange membrane, sequentially perform X-axis serpentine flow channel coating of cathode catalyst ink and Y-axis serpentine flow channel coating of cathode catalyst ink for 5 minutes to construct a three-dimensional ordered and tightly bonded interface between the catalyst layer and the ion exchange membrane, thereby constructing a three-dimensional network structure of the catalyst and improving the activity and stability of the membrane electrode. Then, raise the temperature to 80°C until coating is complete, forming the cathode catalyst layer.

[0071] The ion membrane with the cathode-side catalyst layer coated is flipped and attached to the coating platform and fixed. The anode catalyst ink is placed in the coating equipment, and the temperature of the coating platform is set to 45°C. On the other side of the ion membrane, the cathode catalyst ink is coated in the X-axis serpentine flow channel and the cathode catalyst ink is coated in the Y-axis serpentine flow channel in sequence for 5 minutes. Then the temperature is increased to 80°C until the coating is completed, forming the anode catalyst layer.

[0072] A gas diffusion layer with a cutting area of ​​5×5cm is cut and then subjected to hot pressing treatment of the film electrode 4.

[0073] Under operating conditions where the reactant gases are H2 / Air and the gas stoichiometry ratio is 2:2, the membrane electrode 4 was tested using a fuel cell testing system, and the results are as follows: Figure 6 As shown in the figure. The left vertical axis represents E / V (voltage), the right vertical axis represents P / W (power density), and the horizontal axis represents j / A (current density). The peak power density of membrane electrode 4 is 1.07 W / cm². -2 The maximum current density is 2.42 Acm. -2 Meanwhile, the membrane electrode 11, used in Comparative Example 3, achieved a peak power density of 0.72 W / cm². -2 The maximum current density is 1.81 Acm. -2The performance of the membrane electrode 4 was lower than that of the membrane electrode 4. The ion exchange membrane was swollen on one side by spraying solvent, and alcohols were used to cause microstructural deformation of some ionomers. Without the stainless steel mesh, local swelling and chemical bond opening and closing occurred, forming a solution-saturated state with exposed polar functional groups (sulfonic acid groups), while the areas with the stainless steel mesh remained in their original state, with the polar functional groups (sulfonic acid groups) hidden. In this state, the surface of the ion exchange membrane was uneven, increasing its surface area. The contact area between the ion exchange membrane and the catalyst layer was increased by spraying catalyst ink onto its surface. While some mesoporous structures may form in the areas covered by the stainless steel mesh, the ordered pore structure is actually beneficial for water vapor management. Water drains away through the formed pores, while gas is transported in the swollen and chemical bond opening and closing areas, thus further improving mass transfer and resulting in higher power of the membrane electrode at high current densities. In contrast, the membrane electrode 11 of Comparative Example 3 had a dense pore structure and disordered water vapor management, leading to poor membrane electrode performance.

[0074] Example 5: Controlling the swelling state of the ion exchange membrane

[0075] This embodiment uses a method for constructing an interface between an ion exchange membrane and a catalytic layer to prepare a 25cm... 2 The specific steps for membrane electrode 5 include:

[0076] Cut the acidic ion exchange membrane into 7×7cm squares, immerse the clean ion exchange membrane in a 0.5% sulfuric acid solution until the membrane swells, and then store it for later use.

[0077] In this embodiment, the total platinum loading of the anode and cathode of the prepared membrane electrode is 0.05 mg / cm³. 2 and 0.05 mg / cm 2 Both the cathode catalyst ink and the anode catalyst ink comprise catalyst ink B and catalyst ink C. First, the platinum loading of both the anode and cathode catalysts is 0.015 mg / cm³. 2 A certain amount of Pt / C catalyst was weighed, and water and isopropanol were used as specific solvent A. The solid content of the platinum-carbon catalyst in specific solvent A was kept at 2 mg / mL. No ionomer was added, and the catalyst was dispersed evenly to obtain catalyst ink B. The platinum loading of both the anode and cathode catalysts was 0.035 mg / mL. 2 A certain amount of Pt / C catalyst was weighed, and water and isopropanol were used as specific solvent A. The solid content of the platinum-carbon catalyst in specific solvent A was kept at 2 mg / mL. Then a certain amount of ionomer was added to maintain the I / C ratio at 0.5. The catalyst ink C was obtained by uniform dispersion.

[0078] A 5×5cm serpentine flow channel coating area is set in the center of the ion exchange membrane. The swollen and wet ion exchange membrane is directly attached to the coating device and fixed. The catalyst ink B is placed in the coating device.

[0079] The coating platform was opened and the temperature was set to 45°C. On one side of the ion exchange membrane, catalyst ink B was coated sequentially using an X-axis serpentine flow channel and then a Y-axis serpentine flow channel for 5 minutes. High-performance output of membrane electrode 5 was achieved without the use of ionomers, indicating that the catalyst layer and the ion exchange membrane interface had good contact. The catalyst utilized the ionomers in the ion exchange membrane as ion transport channels, constructing a highly efficient ion and gas transport channel. The temperature was then increased to 80°C until catalyst ink B was completely coated. Catalyst ink C was placed in the coating equipment at 80°C, and coated sequentially using X-axis and Y-axis serpentine flow channels to form the cathode catalyst layer.

[0080] To regulate the swelling state of the ion exchange membrane coated with the cathode catalyst layer, the membrane was immersed in a 0.5% sulfuric acid solution for 10 minutes to allow it to swell again. The uncoated anode side was then attached to and fixed to the coating platform. Catalyst ink B was placed in the coating equipment, and the coating platform temperature was set to 45°C. On the other side of the ion exchange membrane, catalyst ink B was coated sequentially using an X-axis serpentine flow channel and then a Y-axis serpentine flow channel for 5 minutes each. The temperature was then increased to 80°C until catalyst ink B was completely coated. Catalyst ink C was then placed in the coating equipment at 80°C, first coated along the X-axis, then coated along the Y-axis serpentine flow channel to form the anode catalyst layer.

[0081] A gas diffusion layer with a cutting area of ​​5×5cm is formed into a film electrode 5 by hot pressing.

[0082] In existing technologies, catalyst layers without ionomers do not exhibit good performance. However, in this example, even without ionomers in the catalyst ink B, which is in direct contact with the ion exchange membrane, the membrane electrode 5 still demonstrates excellent performance. This indicates that the catalyst layer and the ion exchange membrane of the membrane electrode prepared in this invention have excellent contact, and the catalyst permeates into the ion exchange membrane, forming a three-dimensional network structure. Since the ion exchange membrane itself is also composed of ionomers, the catalyst utilizes the ionomers in the ion exchange membrane as ion transport channels, further proving the excellent contact between the catalyst layer and the ion exchange membrane.

[0083] Under operating conditions where the reactant gases are H2 / Air and the gas stoichiometry ratio is 2:2, the membrane electrode 5 was tested using a fuel cell testing system, and the results are as follows: Figure 7 As shown. The peak power density of membrane electrode 5 is 1.22 W / cm². -2 The maximum current density is 2.92 Acm.-2 Meanwhile, the membrane electrode 11, used in Comparative Example 3, achieved a peak power density of 0.72 W / cm². -2 The maximum current density is 1.81 Acm. -2 The ionic impedance values ​​were all lower than those of membrane electrode 5. This indicates that the performance of the membrane electrode was improved by the immersion and graded spraying methods. The ionic impedance of the membrane electrode prepared using this method is lower, at only 1.37 mΩ, while that of membrane electrode 11 is 3.08 mΩ, indicating that the presence of water creates a barrier to direct contact. Under low humidity, the ionic impedance of membrane electrode 5 increased to 6.06 mΩ, while that of membrane electrode 11 was 29.84 mΩ. This shows that the swelling caused by immersion and the graded spraying method effectively improved the integrity of the ion transport channels of the membrane electrode, proving that the catalyst layer utilizes some of the ionomers from the ion-exchange membrane as catalyst ionomers. The graded spraying method can reduce the potential catalyst poisoning caused by excessive ionomers in the catalyst layer, as seen in Examples 1-4, and optimizes the proportion of ionomers in the catalyst layer, effectively improving the performance of the membrane electrode.

[0084] Example 6: Controlling the ion exchange membrane in a state of swelling, phase transition, and chemical bond opening and closing.

[0085] This embodiment uses a method for constructing the interface between the ion exchange membrane and the catalyst layer to prepare the membrane electrode 6. The alkaline ion exchange membrane is cut into a 7×7cm square. The clean ion exchange membrane is immersed in a mixed solution of water, sulfuric acid and ethanol in a ratio of 20:1:5 and heated to 95°C to achieve membrane swelling, chemical bond opening and closing, and phase transition. Then it is stored for later use.

[0086] The subsequent steps for preparing the catalyst ink and coating are the same as in Example 3.

[0087] Under operating conditions where the reactant gases are H2 / Air and the gas stoichiometry ratio is 2:2, the membrane electrode 6 was tested using a fuel cell testing system, and the results are as follows: Figure 8 As shown. The peak power density of membrane electrode 6 is 1.32 W / cm². -2 The maximum current density is 2.96 A cm⁻¹. -2 Meanwhile, the membrane electrode 11, used in Comparative Example 3, achieved a peak power density of 0.72 W / cm². -2 The maximum current density is 1.81 A cm⁻¹. -2 The values ​​are all lower than those of the membrane electrode 6. This indicates that simultaneously controlling the ion exchange membrane to be in a state of swelling, phase transition, and chemical bond opening and closing also has a certain improvement on the membrane electrode. Since simultaneously controlling all three requires more parameter settings, the improvement on the membrane electrode in this embodiment is limited, but it does not prevent the effectiveness of improving the membrane electrode by simultaneously controlling all three in this embodiment.

[0088] Example 7: Controlling the ion exchange membrane to a phase transition state

[0089] This embodiment uses a method for constructing an interface between an ion exchange membrane and a catalytic layer to prepare a 25cm... 2 The membrane electrode 7 is prepared by cutting the ion exchange membrane into a 7×7cm square, etching it to induce a phase transition, such as laser etching to produce a localized phase transition, or other existing methods to induce a phase transition, such as high-temperature heating to 90-150°C in an air or nitrogen atmosphere, followed by storage for later use. Subsequent steps, including preparing the catalyst ink and coating, are the same as in Example 3.

[0090] Under operating conditions where the reactant gases are H2 / Air and the gas stoichiometry ratio is 2:2, the membrane electrode 7 was tested using a fuel cell testing system, and the results are as follows: Figure 9 As shown. The peak power density of membrane electrode 8 is 0.91 W / cm². -2 The maximum current density is 1.88 A cm⁻¹. -2 Meanwhile, the membrane electrode 11, used in Comparative Example 3, achieved a peak power density of 0.72 W / cm². -2 The maximum current density is 1.81 A cm⁻¹. -2 The values ​​were all lower than those of the membrane electrode 7. This indicates that by altering the phase transition of the ion exchange membrane, the ionomers in the membrane undergo a transformation from a compact structure to a loose structure. This allows the catalyst ink to easily enter the ion exchange membrane and combine with it to form an integrated structure, reducing phase separation between the ion exchange membrane and the catalyst ink, and decreasing the number of local pores. This has a certain effect on improving the performance of the membrane electrode.

[0091] Example 8: Controlling the ion exchange membrane to be in a chemical bond open / closed state

[0092] This embodiment uses a method for constructing an interface between an ion exchange membrane and a catalytic layer to prepare a 25cm... 2 The membrane electrode assembly is prepared by cutting the ion exchange membrane into a 7×7cm square, using existing methods to bring the ion exchange membrane into a state of open and closed chemical bonds, and then storing it for later use. Subsequent steps, such as preparing the catalyst ink and coating, are the same as in Example 3.

[0093] Example 9

[0094] This embodiment uses a method for constructing an interface between an ion exchange membrane and a catalyst layer to prepare a 5cm... 2 The alkaline membrane electrode 8, the specific method steps include:

[0095] Cut the A20 alkaline membrane into a 5×5cm square, immerse the clean alkaline membrane in a 1 molar potassium hydroxide solution to make the ion-exchange membrane swell, and store it for later use.

[0096] In this embodiment, the anode and cathode loadings of the prepared membrane electrode are 0.2 mg and 0.2 mg, respectively.PtRu / cm 2 and 0.2mg Pt / cm 2 A certain amount of PtRu / C catalyst (platinum-ruthenium catalyst) was weighed out, and water and isopropanol were used as specific solvent A to maintain the solid content of the catalyst in specific solvent A at 2 mg / mL. Then, a certain amount of ionomer was added to maintain the I / C ratio at 0.25, and the catalyst was dispersed evenly to prepare it as an anode catalyst. A certain amount of Pt / C catalyst was weighed out, and water and isopropanol were used as specific solvent A to maintain the solid content of the catalyst in specific solvent A at 2 mg / mL. Then, a certain amount of ionomer was added to maintain the I / C ratio at 0.25, and the catalyst was dispersed evenly to prepare it as a cathode catalyst.

[0097] Set a 5cm diameter in the exact center of the ion exchange membrane. 2 The serpentine flow channel coating area involves directly attaching and fixing an alkaline ion exchange membrane immersed in potassium hydroxide to the coating device, and placing the cathode catalyst ink in the coating equipment.

[0098] Turn on the coating platform, set the temperature to 60℃, and sequentially perform X-axis serpentine flow channel coating of cathode catalyst ink and Y-axis serpentine flow channel coating of cathode catalyst ink for 5 minutes; then raise the temperature to 80℃ until coating is completed to form a cathode catalyst layer.

[0099] The ion membrane coated with the cathode catalyst layer was placed in water and soaked for 10 minutes. Then, the anode side without the catalyst layer was attached to the coating platform and fixed. The anode catalyst ink was placed in the coating equipment and the temperature was set to 60°C. The anode catalyst ink was coated in the X-axis serpentine flow channel and the anode catalyst ink was coated in the Y-axis serpentine flow channel in sequence for 5 minutes. Then the temperature was increased to 80°C until the coating was completed and the anode catalyst layer was formed.

[0100] The cutting area is 5cm 2 The gas diffusion layer is assembled into an alkaline wet-coated membrane electrode 8.

[0101] Meanwhile, a conventional alkaline membrane electrode 12 was prepared as a comparative example 4 using conventional methods (such as comparative example 3, but with the same anode and cathode loading as membrane electrode 8).

[0102] Under the operating conditions of H2 / O2 reactant gases and a flow rate of 0.5 L / min for both reactant gases, the membrane electrode 8 and membrane electrode 12 were tested using a fuel cell testing system. The results are as follows: Figure 10 As shown in the figure. The left vertical axis represents E / V (voltage), the right vertical axis represents P / W (power density), and the horizontal axis represents j / A (current density). The peak power density of membrane electrode 8 is 1.06 W / cm². -2 The maximum current density is 2.40 Acm. -2Meanwhile, the membrane electrode 12, used as a comparison sample, had a peak power density of 0.55 W / cm². -2 The maximum current density is 1.41 Acm. -2 The values ​​are all lower than those of the membrane electrode 8. This indicates that even under alkaline conditions, by treating the alkaline membrane using the method claimed in this patent, allowing the alkaline ion membrane to be in a certain swollen state, the phase separation can be effectively changed, constructing a highly efficient interface between the ion membrane and the catalyst layer, and effectively improving the performance of the membrane electrode.

[0103] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

[0104] Comparative Example 1

[0105] This comparative example prepared 25cm 2 The standard membrane electrode 9 is cut into 7×7cm squares from the M778.12 ion exchange membrane and stored for later use without further processing.

[0106] In this embodiment, the platinum loading of the anode and cathode of the prepared membrane electrode is 0.4 mg / cm³, respectively. 2 and 0.1 mg / cm 2 According to the platinum loading of the anode and cathode, the corresponding mass of Pt / C catalyst was weighed. Water and isopropanol were used as solvents to maintain the solid content of the catalyst in the solvent at 2 mg / mL. Then, a certain amount of ionomer was added to maintain the I / C ratio at 0.5. The catalysts were then ultrasonically dispersed to obtain the cathode catalyst ink and anode catalyst ink, respectively.

[0107] A 5×5cm serpentine flow channel coating area is set in the center of the ion exchange membrane. The ion exchange membrane is directly attached to the coating device and fixed. The cathode catalyst ink is placed in the coating equipment.

[0108] Open the coating platform, set the temperature to 80℃, and perform serpentine flow channel coating until the coating is completed, forming the cathode catalyst layer.

[0109] The ion membrane coated with the cathode side catalyst layer is flipped and attached to the coating platform and fixed. The anode catalyst ink is placed in the coating equipment and the temperature is set to 80°C until the coating is completed, forming the anode catalyst layer.

[0110] A gas diffusion layer with a cutting area of ​​5×5cm was cut and then hot-pressed to form a membrane electrode 9 prepared by a conventional method.

[0111] Under operating conditions where the reactant gases are H2 / Air and the gas stoichiometry ratio is 2:2, the membrane electrode 9 was tested using a fuel cell testing system, and the results are as follows: Figure 3 As shown. The peak power density of membrane electrode 9 is 1.45 W / cm². -2 The maximum current density is 2.71 Acm. -2 The performance of the membrane electrodes prepared in Examples 1 and 2 was lower than that of the membrane electrodes prepared in Examples 1 and 2. This indicates that the membrane electrode prepared in Example 1 with a high catalyst loading has a good gas-liquid transport channel, significantly reduces interfacial phase separation, and greatly improves performance.

[0112] Comparative Example 2

[0113] This comparative example prepared 25cm 2 The ultra-low load conventional membrane electrode 10 is identical to Comparative Example 1 except for the I / C ratio. The I / C ratio of this comparative example is 1.

[0114] Comparative Example 3

[0115] This comparative example prepared 25cm 2 The ultra-low load conventional membrane electrode 11 was cut into 7×7cm squares from the M778.12 ion exchange membrane and stored for later use without further processing.

[0116] In this embodiment, the anode and cathode loadings of the prepared membrane electrode are 0.05 mg / cm³. 2 and 0.05 mg / cm 2 According to the platinum loading of the anode and cathode, the corresponding mass of Pt / C catalyst was weighed. Water and isopropanol were used as solvents to maintain the solid content of the catalyst in the solvent at 2 mg / mL. Then, a certain amount of ionomer was added to maintain the I / C ratio at 0.5. The catalysts were then ultrasonically dispersed in catalyst ink and used as cathode catalyst ink and anode catalyst ink, respectively.

[0117] A 5×5cm serpentine flow channel coating area is set in the center of the ion exchange membrane. The ion exchange membrane is directly attached to the coating device and fixed. The cathode catalyst ink is placed in the coating equipment.

[0118] Open the coating platform, set the temperature to 80℃, and perform serpentine flow channel coating until the coating is completed, forming the cathode catalyst layer.

[0119] The ion membrane coated with the cathode-side catalyst layer is flipped and attached to the coating platform and fixed. The anode catalyst ink is placed in the coating equipment, the temperature is set to 80℃, and serpentine flow channel coating is performed until the coating is completed, forming the anode catalyst layer.

[0120] A gas diffusion layer with a cutting area of ​​5×5cm is formed into a film electrode 11 by hot pressing.

[0121] Under operating conditions where the reactant gases are H2 / Air and the gas stoichiometry ratio is 2:2, the membrane electrode 7 was tested using a fuel cell testing system, and the results are as follows: Figures 5-9 As shown in the figure. The left vertical axis represents E / V (voltage), the right vertical axis represents P / W (power density), and the horizontal axis represents j / A (current density). The membrane electrode 7 operates at a peak power density of 0.72 W / cm². -2 The maximum current density is 1.81 Acm. -2 The values ​​were all lower than those of the membrane electrodes prepared in Examples 5-9. This indicates that, even with low catalyst loading, the membrane electrodes prepared in Examples 5-9 show a more significant improvement over conventional membrane electrodes, with stronger interfacial bonding, a more pronounced three-phase catalyst interface structure, and a three-dimensional network that enables excellent water and gas management in the membrane electrode.

Claims

1. A method for constructing an interface between an ion exchange membrane and a catalyst layer, characterized in that, include: Step 1: Adjust the ion exchange membrane to a specific state, including a swollen state, a swollen and phase transition state, or a swollen and chemical bond opening and closing state; The control method involves using a specific solvent, hereinafter referred to as specific solvent B, to perform a specific treatment on the ion exchange membrane. When the specific state is a swollen state, the treatment method is immersion or spraying; when the specific state is a swollen and phase-change state, the treatment method is immersion with heating or spraying with heating; when the specific state is a swollen and chemical bond opening and closing state, the treatment method is immersion or spraying. When the specific state is a swollen state, or a swollen and phase-change state, if the ion-exchange membrane is acidic, then the specific solvent B is water, or a combination of water and acid; if the ion-exchange membrane is alkaline, then the specific solvent B is water, or a combination of water and alkali. When the specific state is a swollen and chemically bonded state, if the ion-exchange membrane is acidic, then the specific solvent B is water and alcohol, or a combination of alcohol, base and water; if the ion-exchange membrane is alkaline, then the specific solvent B is water and alcohol, or a combination of alcohol, acid and water. Step 2: Prepare cathode catalyst ink and anode catalyst ink; Step 3: Set the coating temperature to 20-60℃ and coat the cathode catalyst ink on one of the sides of the ion membrane in a specific state. In the final stage of this process, raise the coating temperature to 61-80℃ until the coating is completed and the cathode catalyst layer is formed. The ion membrane coated with the cathode catalyst layer is further regulated to bring it back to the specific state. Step 4: Set the temperature of the coating platform to 20-60℃. Coat the anolyte catalyst ink on the side of the ion exchange membrane that has not yet been coated. In the final stage of this process, raise the coating temperature to 61-80℃ until the coating is completed and the anolyte catalyst layer is formed. Both the cathode catalyst ink and the anode catalyst ink include catalyst ink B and catalyst ink C; In step 2, catalyst ink B is prepared from a specific solvent A and a catalyst, and catalyst ink C is prepared from a specific solvent A, a catalyst, and an ionomer; the specific solvent A is a mixed solution of water and isopropanol. In step 3, the temperature of the coating platform is set to 20-60℃. First, catalyst ink B is used to coat the X-axis and Y-axis serpentine channels in a cyclic manner for 1-20 minutes. Then, the temperature is increased to 61-80℃ until catalyst ink B is completely coated. Then, catalyst ink C is used to coat the X-axis and Y-axis serpentine channels in a cyclic manner until the coating is completed. In step 4, the temperature of the coating platform is set to 20-60℃. First, catalyst ink B is used to coat the X-axis and Y-axis serpentine channels in a cyclic manner for 1-20 minutes. Then, the temperature is increased to 61-80℃ until catalyst ink B is completely coated. Then, catalyst ink C is used to coat the X-axis and Y-axis serpentine channels in a cyclic manner until the coating is completed.

2. The method according to claim 1, characterized in that, Both the cathode catalyst ink and the anode catalyst ink are prepared from a specific solvent A, a catalyst, and an ionomer. The specific solvent A is a mixed solution of water and isopropanol. The I / C ratio of both the cathode catalyst ink and the anode catalyst ink is 0.5-1.

3. The method according to claim 2, characterized in that, The I / C ratio of catalyst ink B is 0:1; the I / C ratio of catalyst ink C is 0.5-1.

4. The method according to claim 1, characterized in that, During the control process, a specific solvent B is used for spraying treatment only on one side of the ion membrane, either the cathode side or the anode side, or a combination of spraying, etching, and heating treatment.

5. The method according to claim 1, characterized in that, When an alkaline ion exchange membrane is soaked in a specific acidic solvent B, or an acidic ion exchange membrane is soaked in a specific alkaline solvent B, the alkaline or acidic ion exchange membrane must be soaked again in a solvent with the same acidity or alkalinity after the catalyst layer is sprayed.

6. The method according to claim 1, characterized in that, The catalyst is a platinum-carbon catalyst or a platinum-ruthenium catalyst, and the solid content of the catalyst in the catalyst ink is 2 mg / mL.

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