Method for constructing interface of high-performance ionic membrane and catalyst layer

Abstract

The invention discloses a method for constructing an ionic membrane and catalyst layer interface. The method comprises the following steps: 1, regulating an ionic membrane to be in a specific state; 2, preparing cathode catalyst ink and anode catalyst ink; 3, the coating temperature is set to be 20-60 DEG C, one of the side faces, in the specific state, of the ionic membrane is coated with cathode catalyst ink, in the final stage of the process, the coating temperature is increased to 61-80 DEG C till coating is completed, and a cathode catalyst layer is formed; 4, the temperature of the coating platform is set to be 20-60 DEG C, the side, not coated, of the ionic membrane is coated with anode catalyst ink, in the final stage of the process, the coating temperature is increased to 61-80 DEG C till coating is completed, and the anode catalyst layer is formed. According to the method, the catalyst layer and the ionic membrane are combined more tightly, the mass transmission path is optimized, and the service life of the catalyst layer is prolonged. The interface impedance is reduced, blocking of direct contact between the catalyst and the ionomer is formed, and a three-dimensional network structure is constructed.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile fuel cell membrane electrodes, in particular to a method for constructing an interface between an ion membrane and a catalyst layer. Background Art

[0002] With global attention focused on clean energy and sustainable development, new energy vehicles are gradually becoming the development direction of the automotive industry. Fuel cell vehicles (FCVs) are attracting much attention for their high energy density and zero emissions. Fuel cells, as their core power source, are expected to replace traditional fossil fuels. The performance of the membrane electrode assembly (MEA) directly affects the output power and efficiency of the fuel cell system, and thus determines the performance and competitiveness of FCVs. To date, MEA fabrication technology has evolved through three generations. The first generation, known as the gas diffusion membrane electrode (GDE), typically employs a screen-printing method to deposit a catalyst layer onto the diffusion layer. The second generation, the catalyst-coated membrane (CCM), deposits the catalyst layer onto the membrane and is currently the mainstream MEA fabrication technology. Compared to the first generation, this method reduces the proton transport resistance between the catalyst layer and the ion membrane, significantly improving MEA performance, catalyst utilization, and durability. The third generation MEA is characterized by an ordered MEA. Given that the cost of preparing ordered membrane electrodes is too high, it is currently limited to laboratory or miniaturized development. Therefore, the most widely used, most widely applied and most promising preparation technology for commercial development is still CCM preparation technology.

[0003] The core of CCM preparation technology lies in how to maximize the optimal performance of each material. However, with the current coating process, directly coating the catalyst on the ion membrane results in insufficient contact between the catalyst layer and the ion membrane. During the coating process, solvent volatilization creates a large number of bubbles at the interface between the catalyst layer and the ion membrane, affecting the mass transfer and water vapor management of the membrane electrode during operation, increasing the contact impedance of the membrane electrode, and resulting in the performance of the prepared membrane electrode not being fully utilized. Changing the catalyst layer structure or improving the ion membrane structure will increase the preparation cost of the membrane electrode. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for constructing the interface between the ion membrane and the catalytic layer, so as to solve the technical problem that the contact between the ion membrane and the catalytic layer is not close enough.

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

[0006] Step 1: regulating the ion membrane to be in a specific state of any one or more combinations of swelling, phase change and opening and closing of chemical bonds;

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

[0008] Step 3: Setting the coating temperature to 20-60°C, coating the cathode catalyst ink on one of the sides of the ion membrane in a specific state. In the final stage of the process, the coating temperature is increased to 61-80°C until the coating is completed to form a cathode catalyst layer.

[0009] Step 4: Set the temperature of the coating platform to 20-60°C, and apply the anode catalyst ink to the side of the ion membrane that has not been coated. In the final stage of the process, increase the coating temperature to 61-80°C until the coating is completed to form the anode catalyst layer.

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

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

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

[0013] In step 3, the temperature of the coating platform is set to 20-60°C. Catalyst ink B is first used to cyclically coat the X-axis and Y-axis serpentine flow channels for 1-20 minutes. The temperature is then raised to 61-80°C until the catalyst ink B is completely coated. Catalyst ink C is then used to cyclically coat the X-axis and Y-axis serpentine flow channels until the coating is complete.

[0014] In step 4, the temperature of the coating platform is set to 20-60°C, and catalyst ink B is first used to cycle through the X-axis and Y-axis serpentine flow channel coating for 1-20 minutes, and then the temperature is increased to 61-80°C until the catalyst ink B is coated; then catalyst ink C is used to cycle through the X-axis and Y-axis serpentine flow channel coating until the coating is completed.

[0015] Optionally, the I / C of catalyst ink B is 0:1; and the I / C 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 so that it is in a specific state again.

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

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

[0019] Optionally, during the control, only one of the cathode side or the anode side of the ion membrane is sprayed with a specific solvent B, or a combination of spraying, etching and heating is performed.

[0020] Optionally, when an acidic specific solvent B is used to soak an alkaline ion membrane, or an alkaline specific solvent B is used to soak an acidic ion membrane, after spraying the catalytic layer, the alkaline or acidic ion membrane needs to be soaked again in a solvent with the same acidity or alkalinity.

[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 the present invention are: the membrane electrode prepared by the method of the present invention utilizes the properties of the ion membrane itself, and constructs an efficient ion and gas transmission channel by inducing and regulating the swelling, phase change, and reversible structural changes of the ion membrane chemical bonds, forming a blockade of direct contact between the catalyst and the ionomer, constructing a three-dimensional network structure, and improving the activity and stability of the membrane electrode; reducing the interface separation phenomenon between the catalytic layer and the ion membrane, making the catalytic layer and the ion membrane more closely combined, simplifying the mass transfer path, and reducing the interface impedance; reducing the tiny bubbles generated in the conventional coating process, which is beneficial to the water vapor management of the membrane electrode; some catalyst particles penetrate into the ion membrane, reducing the hydrogen permeability of the membrane electrode.

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

[0024] Alcoholic solvents can effectively improve the membrane's swelling and dissolution state. Acids or bases can convert the effective functional groups of the ionomer in the ion membrane into ionic forms. Heating and other methods can change the membrane's phase transition. These methods allow the catalyst ink to more easily penetrate the ion membrane, forming a more tightly integrated two-in-one structure of the catalyst layer and ion membrane, improving the gas-liquid-mass transport pathway. Furthermore, the dispersed catalyst can partially form a more dispersed three-dimensional network structure within the membrane, increasing the triple point and enhancing the catalyst's reactivity. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0027] Figure 3 The cathode and anode loadings in Example 1 and Comparative Example 1 are 0.4 and 0.1 mg Pt / cm, respectively. 2 High-load spray membrane electrode 1 and 25cm high-load conventional coating preparation 2 Comparison of polarization curves and power curves of membrane electrode 9 under hydrogen-air constant stoichiometric operation conditions;

[0028] Figure 4 The cathode and anode loadings in Example 2 and Comparative Example 2 are 0.4 and 0.1 mg Pt / cm, respectively. 2 High load immersion heating membrane electrode 2 and high load conventional coating preparation 25cm 2 Comparison of polarization curves and power curves of the membrane electrode 10 under hydrogen-air constant stoichiometric operation conditions;

[0029] Figure 5 The cathode and anode loadings in Example 3 and Comparative Example 3 are 0.05 and 0.05 mg Pt / cm, respectively. 2 Ultra-low load phase separation membrane electrode 3 and 25cm prepared by low load conventional coating 2 Comparison of polarization curves and power curves of membrane electrode 11 under hydrogen-air constant stoichiometric operation conditions;

[0030] Figure 6 The cathode and anode loadings in Example 4 and Comparative Example 3 are 0.05 and 0.05 mg Pt / cm, respectively. 2 Ultra-low-load etching membrane electrode 4 and low-load conventional coating preparation of 25cm 2 Comparison of polarization curves and power curves of membrane electrode 11 under hydrogen-air constant stoichiometric operation conditions;

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

[0032] Figure 8 Comparison of polarization curves and power curves of the membrane electrode 6 of Example 6 of the present invention and the membrane electrode 11 of Comparative Example 3 under hydrogen-air constant stoichiometric operation conditions;

[0033] Figure 9 Comparison of polarization curves and power curves of the membrane electrode 7 of Example 7 of the present invention and the membrane electrode 11 of Comparative Example 3 under hydrogen-air constant stoichiometric operation conditions;

[0034] Figure 10 In Example 9 of the present invention, the cathode and anode loadings are 0.2 mg PtRu / cm 2 and 0.2 mg Pt / cm 2 Alkaline wet spraying membrane electrode 8 and conventional coating prepared 5cm 2 Comparison of polarization curves and power curves of the membrane electrode 12 under constant hydrogen and oxygen ratio operating conditions. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0036] Example 1: Regulating one side of the ion membrane to be in a swollen state

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

[0038] First, the M778.12 acidic ion membrane is cut into 7×7 cm squares. The membrane is then regulated to a specific state, any one or more combinations of swelling, phase change, and chemical bond opening and closing. Different regulation methods result in different specific states. In this example, the regulation method involves using a specific solvent, hereinafter referred to as specific solvent B, to treat the membrane in a specific spraying method. Specifically, the regulation method involves placing the clean membrane on a coating platform and then spraying a small amount of specific solvent B onto the cathode side of the membrane. Specific solvent B is a mixed solvent of water and acid, specifically a 1% sulfuric acid solution, so that the cathode side of the membrane reaches and remains in a swollen state, while the other side remains essentially dry. In other embodiments, the acidic specific solvent B can also be sulfuric acid, hydrochloric acid, or nitric acid. Acidic solvents can maintain the protonation of the sulfonic acid groups of the acidic ion membrane for a long time, so the use of other acidic solvents can achieve the same effect as in this example. In addition, if the ion membrane is an alkaline ion membrane, the specific solvent B is a mixed solvent of water and alkali, which can also cause the ion membrane to be in a swollen state, and the final membrane electrode prepared has the same effect as in this embodiment. In addition to spraying, the control method can also be spraying and etching, and the effect is equivalent to that of this embodiment. In this example, the ion membrane can also be any type of ion membrane, that is, any commercial or homemade acidic ion membrane, and the effect is equivalent to that of this embodiment. It should be noted that when the acidic solvent corresponds to the acidic ion membrane or the alkaline solvent corresponds to the alkaline ion membrane, only the ion membrane is in a swollen state; when the alkaline solvent corresponds to the acidic ion membrane or the acidic solvent corresponds to the alkaline ion membrane, the ion membrane has two states: swelling and chemical bond opening and closing.

[0039] Then, using specific solvent A, catalyst and ionomer, cathode catalyst ink and anode catalyst ink were prepared respectively. In this example, the platinum loading of the prepared membrane electrode anode and cathode was 0.4 mg / cm 2 and 0.1 mg / cm 2 (Catalyst loading: 0.4 / 0.1mg Pt / cm 2 ), which requires the platinum loading of the cathode catalyst layer to be 0.4 mg / cm 2 The platinum loading of the anode catalyst layer is 0.1 mg / cm 2. Specifically, according to the platinum loading of the membrane electrode cathode, the corresponding mass of platinum-carbon catalyst (Pt / C catalyst) is weighed, and a mixed solution of water and isopropanol with a volume ratio of 1:4 is used as a specific solvent A, and the solid content of the platinum-carbon catalyst in the specific solvent A is maintained at 2 mg / mL; a certain amount of D520 ionomer (Ionomer: D520) is then added, and I / C (the ratio of carbon in the ionomer and the catalyst) is maintained at 0.5-1. In this example, it is preferred to maintain I / C at 0.5, and then ultrasonically dispersed uniformly, and used as cathode catalyst ink for standby use. According to the platinum loading of the membrane electrode anode, the corresponding mass of Pt / C catalyst is weighed, and a mixed solution of water and isopropanol with a volume ratio of 1:4 is used as a specific solvent A, and the solid content of the platinum-carbon catalyst in the specific solvent A is maintained at 2 mg / mL. Subsequently, a certain amount of D520 ionomer is added, and I / C is maintained at 0.5-1. In this example, it is preferred to maintain I / C at 0.5, and then ultrasonically dispersed uniformly, and used as anode catalyst ink for standby use.

[0040] In some other embodiments of the present invention, the catalyst can also be a precious metal catalyst or a non-precious metal catalyst, or any combination of precious metal catalysts and / or non-precious metal catalysts, wherein precious metal catalysts are such as palladium catalysts, rhodium catalysts, etc., and non-precious metal catalysts are such as iron-based catalysts, cobalt-based catalysts, etc., and their usage is referred to this embodiment, and can achieve the same or similar effects as the embodiments recorded in this application.

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

[0042] Open the coating platform, set the temperature of the coating platform to 20-60°C, and on one side of the ion membrane in a specific state, cycle through the X-axis serpentine flow channel to coat the cathode catalyst ink, and the Y-axis serpentine flow channel to coat the cathode catalyst ink, and coat for 1-20 minutes, then increase the temperature to 61-80°C until the coating is completed to form a cathode catalyst layer; in this example, set the temperature to 20°C and coat for 20 minutes to achieve good contact between the cathode catalyst layer and the ion membrane interface, reduce the phase separation state, achieve the effect of three-dimensional dispersion of the catalyst, and achieve performance improvement of the membrane electrode 1. In some other embodiments, first set the temperature to 20-60°C, which is similar to the effect of this embodiment; then increase the temperature to 80°C until the coating is completed to form a cathode catalyst layer. Raising the temperature of the coating platform is to quickly dry the ion membrane, so the effect of heating to any temperature between 61-80°C is the same. Among them, the X-axis serpentine flow channel coating and the Y-axis serpentine flow channel coating are as follows: Figure 2 shown.

[0043] The ion membrane coated with the cathode side catalytic layer is turned over 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 X-axis serpentine flow channel is used to coat the anode catalyst ink, and the Y-axis serpentine flow channel is used to coat the anode catalyst ink in a cycle until the coating is completed to form the anode catalyst layer.

[0044] Cutting area is 5×5cm 2 The gas diffusion layer is subjected to hot pressing to form a membrane electrode 1, such as Figure 1 (b) shown.

[0045] Under the operating conditions of H2 / Air (hydrogen / air) as the reaction gas and a H2 / Air stoichiometric ratio of 2:2, the membrane electrode 1 was tested using a fuel cell test system. The results are as follows: Figure 3 As shown. The left vertical axis represents E / V, which represents voltage; the right vertical axis represents P / W, which represents power density; and the horizontal axis represents j / A, which represents current density. The peak power density of membrane electrode 1 is 1.61W cm -2 , the maximum current density is 3.36Acm -2 The peak power density of the membrane electrode 9 in comparative example 1 is 1.45 W cm -2 , the maximum current density is 2.71Acm -2 , are lower than the membrane electrode 1. The anode of the membrane electrode 1 of this embodiment is sprayed in the same manner as the anode of the membrane electrode 9 of comparative example 1, indicating that on the same basis as the anode side, the cathode spray membrane electrode 1 is prepared by applying the spraying method to allow the ion membrane to be in a unilateral swelling state. After swelling by water and acid spraying, the pores of the acidic ion membrane become larger, and the membrane saturated with liquid allows the cathode catalyst ink to enter the acidic ion membrane more easily, allowing the cathode catalyst layer interface and the proton membrane interface to blend with each other, forming a three-dimensional catalyst network structure. In addition, the cathode catalyst layer and the anode catalyst layer of the membrane electrode 1 prepared by this embodiment are tightly combined without the formation of obvious pore structures, reducing the state of phase separation, and therefore has good performance. However, during the spraying process of the membrane electrode 9 of comparative example 1, since the liquid phase ink directly contacts the solid phase dried membrane, the two phases cannot completely overlap, so the small ink particles will bounce on the surface of the dry membrane, resulting in the formation of dense mesopores at the interface (such as Figure 1 (a) This leads to increased contact impedance and disrupted water vapor management, which in turn causes performance degradation. Furthermore, due to the differences in catalytic reactions and catalyst types between the anode and cathode of acidic and alkaline fuel cells, using a spraying method rather than an immersion method to control the ion-exchange membrane's unilateral swelling facilitates the study of the interface between the catalyst layer and the ion-exchange membrane on a single side.

[0046] Example 2: Regulating the ion membrane in a swelling and phase change state

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

[0048] Cut the M778.12 ion membrane into a 7×7 cm square. Soak the clean membrane in water (specifically, solvent B). Heat the membrane to 95°C to achieve both swelling and phase transition. Store for future use. Heating the membrane to 90-150°C can induce a phase transition, and heating to 90-150°C has essentially the same effect as heating to 95°C. Soaking the membrane also swells the membrane. This method allows the catalyst ink to more easily penetrate the membrane, forming a more tightly integrated catalyst layer and membrane structure, improving the gas-liquid-mass transfer pathway. In other embodiments, the specific solvent B can also be a combination of water and an acid or base. The acidic solvent corresponds to the acidic ion membrane, and the alkaline solvent corresponds to the alkaline ion membrane. The effect of using water mixed with an acidic or alkaline solvent will be better than water, because the ion membrane is placed in the corresponding acid or alkaline solution, that is, the acidic ion membrane is in an acidic environment and the alkaline ion membrane is in an alkaline environment. The effective functional groups of the ion membrane can be in a group mode for a long time, and long-term exposure to water will cause the functional groups of the ion membrane to gradually transform into ionic form, which is not conducive to the transmission of ions in the membrane electrode. In other embodiments, the ion membrane can be sprayed with water while heating to 90-150 ° C to control the ion membrane to be in a swelling and phase change state, achieving an effect similar to that of this embodiment.

[0049] In this embodiment, the platinum loading of the prepared membrane electrode anode and cathode is 0.4 mg / cm 2 and 0.1 mg / cm 2 According to the platinum loading of the membrane electrode cathode, the corresponding mass of Pt / C catalyst was weighed, and a mixed solution of water and isopropanol with a volume ratio of 1:4 was used as the specific solvent A. The solid content of the platinum carbon catalyst in the specific solvent A was maintained at 2 mg / mL. Subsequently, a certain amount of D520 ionomer was added, maintaining the I / C ratio at 1. The mixture was then ultrasonically dispersed to form a cathode catalyst ink for later use. According to the platinum loading of the membrane electrode anode, the corresponding mass of Pt / C catalyst was weighed, and water and isopropanol were used as the specific solvent A. The solid content of the platinum carbon catalyst in the specific solvent A was maintained at 2 mg / mL. Subsequently, a certain amount of D520 ionomer was added, maintaining the I / C ratio at 1. The mixture was then ultrasonically dispersed to form a anode catalyst ink for later use.

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

[0051] Open the coating platform and set the temperature of the coating platform to 60°C. On the side of the ion membrane in the swelling and phase change state, cycle through the X-axis serpentine flow channel to coat the cathode catalyst ink, and the Y-axis serpentine flow channel to coat the cathode catalyst ink. Coating takes 20 minutes. The ion membrane and the spray are at the same temperature to achieve further contact between the catalytic layer and the ion membrane interface, further reducing the phase separation state, improving the three-dimensional dispersion of the catalyst, and constructing an efficient ion and gas transmission channel to achieve a significant improvement in the performance of the membrane electrode 2. Then increase the temperature to 80°C until the coating is completed to form a cathode catalyst layer.

[0052] The ion membrane coated with the cathode side catalytic layer is turned over 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 X-axis serpentine flow channel is used to coat the anode catalyst ink, and the Y-axis serpentine flow channel is used to coat the anode catalyst ink in a cycle. The coating is carried out for 20 minutes, and then the temperature is increased to 80°C until the coating is completed to form the anode catalyst layer.

[0053] The gas diffusion layer is cut into pieces with an area of ​​5×5 cm and subjected to hot pressing to form the membrane electrode 2.

[0054] Under the operating conditions of H2 / Air as the reaction gas and a reaction gas stoichiometric ratio of 2:2, the membrane electrode 2 was tested using a fuel cell test system. The results are as follows: Figure 4 As shown. The left vertical axis represents E / V, which represents voltage; the right vertical axis represents P / W, which represents power density; and the horizontal axis represents j / A, which represents current density. The peak power density of membrane electrode 2 is 1.80W cm -2 , the maximum current density is 3.61Acm -2 The peak power density of the membrane electrode 10 in comparative example 2 is 1.33 W cm -2 , the maximum current density is 2.59Acm -2 . Both are lower than membrane electrode 2. In the process of preparing the membrane electrode 2 of this embodiment, swelling allows the ion membrane to be in a solid-liquid mixed phase state saturated with liquid, and the ion membrane is placed in an α-transformation phase change state by heating, so that the ion clusters of the ionomer in the ion membrane are thermally transformed from a tightly associated state to a weakened interaction state. Under the dual effects of swelling and phase separation, the state of mutual interlocking between the catalytic layer and the ionomer is further increased, allowing more catalysts to penetrate into the ion membrane, the phase separation is further weakened, and a complete ion transmission channel is obtained. Although the poisoning of the catalyst by the ionomer may be increased because the anode I / C is 1, the overall performance of the membrane electrode 2 is further enhanced. As for the membrane electrode 10 of comparative example 2 which is conventionally sprayed, its performance is lower than that of the comparative membrane electrode 10 due to the increased I / C.

[0055] Example 3: Regulating the ion membrane in a swelling and chemical bond opening and closing state

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

[0057] Cut the M778.12 acidic ion-exchange membrane into squares larger than 7 x 7 cm. Soak the clean membrane in a mixture of water, alcohol, and alkali. Specifically, solvent B is a mixture of water, alcohol, and alkali. In this example, the alcohol is ethanol and the alkali is potassium hydroxide. The ratio of water, ethanol, and potassium hydroxide is 20:1:5, ensuring that the membrane swells and chemical bonds open simultaneously. Store the membrane for future use. Besides ethanol, other alcohols can be methanol, isopropanol, n-propanol, cyclohexanol, ethylene glycol, glycerol, propylene glycol, and other alcoholic solvents. Polar alcohols, due to their dielectric properties and solvation capacity, expose the sulfonic acid groups, the effective polar functional groups of the ionomer, while the nonpolar PTFE backbone curls up. Therefore, replacing the ethanol in this example with any of the aforementioned alcohols will achieve similar results. In addition to potassium hydroxide, the alkali can also be sodium hydroxide, calcium hydroxide, ferric hydroxide, ammonia water, sodium carbonate, sodium bicarbonate and other alkaline solvents. The alkaline solvent acts on the ion membrane to convert the exposed polar functional group sulfonic acid group into the sulfonate form, so replacing potassium hydroxide with the above alkaline solvents can achieve similar effects as in this example; in other embodiments, for alkaline ion membranes, the alkaline solvent in this example can be replaced with an acidic solvent, and the effect is the same as in this example. In addition to soaking, spraying or a combination of etching and spraying can also be used to achieve the same effect as in this example. Soaking, etching or spraying the acidic ion membrane with a mixed solvent of water, alkali and alcohol can open and close the chemical bonds of the ion membrane and cause it to swell. Soaking, etching or spraying the alkaline ion membrane with a mixed solvent of water, acid and alcohol can open and close the chemical bonds of the ion membrane and cause it to swell. Alcohol solvents can effectively improve the swelling and dissolution state of the membrane, and acid or alkaline solvents can change the effective functional groups of the ionomer in the ion membrane into ionic form. Through the above method, the catalyst ink can penetrate into the ion membrane more easily, forming a more tightly combined catalytic layer and ion membrane two-in-one structure, thereby improving the gas-liquid mass transmission channel.

[0058] In this embodiment, the platinum loading of the prepared membrane electrode and the cathode is 0.05 mg / cm 2 and 0.05 mg / cm 2 According to the platinum loading of the membrane electrode cathode and anode, the corresponding mass of Pt / C catalyst, water and isopropanol as the specific solvent A were weighed, and the solid content of the platinum carbon catalyst in the specific solvent A was maintained at 2 mg / mL. Then, a certain amount of ionomer was added to maintain the I / C ratio at 0.5. The mixture was then ultrasonically dispersed to obtain cathode catalyst ink and anode catalyst ink for use.

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

[0060] Turn on the coating platform and set the temperature of the coating platform to 45°C. On one side of the ion membrane, cycle through the X-axis serpentine flow channel to coat the cathode catalyst ink, and then cycle through the Y-axis serpentine flow channel to coat the cathode catalyst ink. The coating process lasts for 5 minutes to form a barrier to direct contact with the catalyst, thereby constructing efficient ion and gas transmission channels, a three-dimensional network structure, and improving the activity and stability of the membrane electrode 3. The temperature is then raised to 80°C until the coating is completed to form a cathode catalyst layer.

[0061] The ion membrane coated with the cathode catalyst layer is placed in a specific solvent B with a ratio of water, ethanol and potassium hydroxide of 20:1:5 and soaked for 10 minutes to make the ion membrane swollen and the chemical bonds open and close. Then, the anode side not coated with the catalytic layer is attached to the platform and fixed. The anode catalyst ink is placed in the coating equipment, and the X-axis serpentine flow channel is used to coat the anode catalyst ink, and the Y-axis serpentine flow channel is used to coat the anode catalyst ink in turn. The coating is carried out for 5 minutes, and then the temperature is raised to 80°C until the coating is completed to form the anode catalyst layer.

[0062] The acidic ion-exchange membrane, sprayed with a catalytic layer, was immersed in a 5% sulfuric acid solution for 30 minutes. This solution converts the sulfonic acid groups into sulfonate radicals. This further acid immersion converts the sulfonate radicals into sulfonic acid groups. This immersion also removes excess alkali, which is detrimental to acidic ion-exchange membranes (because it can alter the effective functional groups). The gas diffusion layer was then cut into 5×5 cm sections 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 (pH value is not equal to 7) specific solvent B is used to soak a non-neutral ion membrane, after the catalytic layer is sprayed, the alkaline or acidic ion membrane needs to be soaked again in a solvent with the same acidity and alkalinity; specifically, when an acidic specific solvent B is used to soak an alkaline ion membrane, after the catalytic layer is sprayed, the alkaline ion membrane is soaked again in an alkaline solvent; when an alkaline specific solvent B is used to soak an acidic ion membrane, after the catalytic layer is sprayed, the acidic ion membrane is soaked again in an acidic solvent.

[0064] Under the operating conditions of H2 / Air as the reaction gas and a reaction gas stoichiometric ratio of 2:2, the membrane electrode 3 was tested using a fuel cell test system. The results are as follows: Figure 5As shown. The left vertical axis represents E / V, which represents voltage; the right vertical axis represents P / W, which represents power density; and the horizontal axis represents j / A, which represents current density. The peak power density of membrane electrode 3 is 0.96W cm -2 , the maximum current density is 2.40Acm -2 The peak power density of the membrane electrode 11 in comparative example 3 is 0.72 W cm -2 , the maximum current density is 1.81Acm -2 , are lower than membrane electrode 3. When the ion membrane is in a swollen state, the membrane is filled with liquid to form a solid-liquid mixed form, and the effective functional groups of the ion membrane are in a state of chemical bond opening and closing through alcohol and alkali, which is similar to the ionomer in the catalyst ink. Under the microscopic state, the ionomer is an oil-in-water structure, that is, the exposed polar functional group sulfonic acid group is 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 membrane, forming a dispersed catalyst in the acidic ion membrane, constructing a three-dimensional catalyst network and a through ion transmission channel, 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 cathode and anode catalyst loading to 8 times and 2 times that of Example 1, membrane electrode 3 still shows good performance, indicating that the application of swelling and chemical bond opening and closing can be more suitable for membrane electrodes prepared with low-loaded catalysts. And after completing the spraying on one side, the other side was also treated in different states to achieve regulation on both sides of the membrane. This example provides guidance for achieving cost reduction and efficiency improvement in membrane electrode production. Accordingly, the membrane electrode 11 of Comparative Example 3 exhibited the same performance as the membrane electrode 9 of the high-load Comparative Example 1, with a noticeable and chaotic pore structure at the interface, hindering water vapor management and ion transport, resulting in poor performance.

[0065] Example 4: Regulating the ion membrane in a swollen and chemical bond opening and closing state

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

[0067] Cut the M778.12 ion membrane into a 7×7 cm square, attach the clean ion membrane to the coating platform, and apply a stainless steel metal mesh with a mesh spacing of 0.5 cm to the ion membrane surface. Spray the specific solvent B with a mixture ratio of 20:1:1 of water, isopropyl alcohol, and ethanol on the blank spaces of the stainless steel mesh. Etch the ion membrane for 10 minutes to allow the ion membrane to swell and the local chemical bonds to open and close. Then store it for future use. It should be noted that the jia in this paragraph

[0068] In this embodiment, the platinum loading of the prepared membrane electrode and the cathode is 0.05 mg / cm 2 and 0.05 mg / cm 2 According to the platinum loading of the membrane electrode cathode and anode, the corresponding mass of Pt / C catalyst, water and isopropanol as the specific solvent A were weighed, and the solid content of the platinum carbon catalyst in the specific solvent A was maintained at 2 mg / mL. Then, a certain amount of ionomer was added to maintain the I / C ratio at 0.5. The mixture was then ultrasonically dispersed to obtain cathode catalyst ink and anode catalyst ink for use.

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

[0070] Turn on the coating platform and set the temperature of the coating platform to 45°C. On one side of the ion membrane, cycle through the X-axis serpentine flow channel to coat the cathode catalyst ink, and then cycle through the Y-axis serpentine flow channel to coat the cathode catalyst ink for 5 minutes to build a three-dimensional, ordered, and tightly bonded interface between the catalytic layer and the ion membrane, build a three-dimensional network structure of the catalyst, and enhance the activity and stability of the membrane electrode. Then, raise the temperature to 80°C until the coating is completed to form a cathode catalyst layer.

[0071] The ion membrane coated with the cathode side catalytic layer is turned over 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 turn. The coating is carried out for 5 minutes, and then the temperature is increased to 80°C until the coating is completed to form the anode catalyst layer.

[0072] The gas diffusion layer is cut into pieces with an area of ​​5×5 cm and subjected to hot pressing to form a membrane electrode 4.

[0073] Under the operating conditions of H2 / Air as the reaction gas and a reaction gas stoichiometric ratio of 2:2, the membrane electrode 4 was tested using a fuel cell test system. The results are as follows: Figure 6 As shown. The left vertical axis represents E / V, which represents voltage; the right vertical axis represents P / W, which represents power density; and the horizontal axis represents j / A, which represents current density. The peak power density of membrane electrode 4 is 1.07W cm -2 , the maximum current density is 2.42Acm -2 The peak power density of the membrane electrode 11 in comparative example 3 is 0.72 W cm -2 , the maximum current density is 1.81Acm -2, both lower than membrane electrode 4. By spraying the solvent, the ion membrane is unilaterally swollen, and alcohols are used to deform the microstructure of some ionomers. The form of not using a stainless steel mesh allows local swelling and chemical bond opening and closing, that is, the ion membrane is locally saturated with solution, with the polar functional group sulfonic acid groups exposed to the outside, while the area where the stainless steel mesh is used maintains its original state, that is, the polar functional group sulfonic acid groups are hidden inside. In this state, the surface of the ion membrane is uneven, increasing the surface area of ​​the ion membrane. By spraying the catalyst ink on its surface, the contact area between the ion membrane and the catalytic layer is increased. Some mesoporous pore structures may form in the area covered by the stainless steel mesh, but the ordered pore structure is actually beneficial for water vapor management. Water is discharged in the formed pores, while gas is transported in the area of ​​swelling and chemical bond opening and closing, so mass transfer is further improved, and the membrane electrode has higher power at high current density. However, the membrane electrode 11 of comparative example 3 has a dense pore structure and disordered water vapor management, resulting in poor membrane electrode performance.

[0074] Example 5: Regulating the ion membrane to be in a swollen state

[0075] This example uses a method for constructing the interface between the ion membrane and the catalyst layer to prepare a 25cm 2 Membrane electrode 5, the specific method steps include:

[0076] Cut the acidic ion membrane into 7×7 cm squares, soak the clean ion membrane in 0.5% sulfuric acid solution until the membrane is swollen, and then store it for future use.

[0077] In this embodiment, the total platinum loading of the prepared membrane electrode anode and cathode is 0.05 mg / cm 2 and 0.05 mg / cm 2 The cathode catalyst ink and the anode catalyst ink both include catalyst ink B and catalyst ink C. First, the platinum loading of the cathode and anode catalysts is 0.015 mg / cm 2 A certain amount of Pt / C catalyst was weighed, water and isopropanol were used as specific solvent A, the solid content of the platinum carbon catalyst in the specific solvent A was kept at 2 mg / mL, no ionomer was added, and the catalyst ink B was obtained by uniform dispersion; the platinum loading of the cathode and anode catalysts was 0.035 mg / cm 2 A certain amount of Pt / C catalyst, water and isopropanol as specific solvent A were weighed, and the solid content of the platinum carbon catalyst in the specific solvent A was maintained at 2 mg / mL. Subsequently, a certain amount of ionomer was added, maintaining I / C at 0.5, and the catalyst ink C was uniformly dispersed.

[0078] A 5×5 cm serpentine flow channel coating area was set in the middle of the ion membrane. The wet ion membrane in a swollen state was directly attached to the coating device and fixed. Catalyst ink B was placed in the coating equipment.

[0079] The coating platform was turned on and the temperature of the coating platform was set to 45°C. On one side of the ion membrane, catalyst ink B was coated in an X-axis serpentine flow channel and catalyst ink B was coated in a Y-axis serpentine flow channel in a cycle for 5 minutes. High-performance output of the membrane electrode 5 was achieved without using an ionomer, indicating that the catalytic layer had good contact with the ion membrane interface. The catalyst used the ionomer in the ion membrane as an ion transport channel to construct an efficient ion and gas transport channel. The temperature was then raised to 80°C until catalyst ink B was coated. Catalyst ink C was placed in the coating equipment at a temperature of 80°C, and the X-axis and Y-axis serpentine flow channel coatings were cycled in sequence to form a cathode catalyst layer.

[0080] The ion membrane coated with the cathode catalyst layer is regulated to be in a swollen state. Specifically, the ion membrane coated with the cathode catalyst layer is placed in a 0.5% sulfuric acid solution and soaked for 10 minutes to allow the ion membrane to be in a swollen state again. Then, the anode side not coated with the catalyst layer is attached to the coating platform and fixed. Catalyst ink B is placed in a coating device, and the temperature of the coating platform is set to 45°C. On the other side of the ion membrane, the X-axis serpentine flow channel is coated with catalyst ink B, and the Y-axis serpentine flow channel is coated with catalyst ink B in sequence. The coating is 5 minutes; then the temperature is increased to 80°C until the catalyst ink B is coated; catalyst ink C is placed in a coating device at a temperature of 80°C, first coated on the X-axis, and then coated on the Y-axis serpentine flow channel to form an anode catalyst layer.

[0081] The gas diffusion layer is cut into pieces with an area of ​​5×5 cm and subjected to hot pressing to form the membrane electrode 5 .

[0082] In the prior art, performance is poor without the addition of an ionomer to the catalyst layer. However, in this example, even without the addition of an ionomer to catalyst ink B, which directly contacts the ion membrane, the membrane electrode 5 still exhibits excellent performance. This demonstrates that the catalyst layer and the ion membrane of the membrane electrode prepared in this invention are in good contact, and that the catalyst penetrates the membrane, forming a three-dimensional network structure. Since the ion membrane itself is also composed of ionomers, the catalyst utilizes the ionomers in the membrane as ion transport channels, demonstrating good contact between the catalyst layer and the membrane.

[0083] Under the operating conditions of H2 / Air as the reaction gas and a reaction gas stoichiometric ratio of 2:2, the membrane electrode 5 was tested using a fuel cell test system. The results are as follows: Figure 7 As shown. Among them, the peak power density of membrane electrode 5 is 1.22W cm -2 , the maximum current density is 2.92Acm-2 The peak power density of the membrane electrode 11 in comparative example 3 is 0.72 W cm -2 , the maximum current density is 1.81Acm -2 , which are lower than membrane electrode 5. It shows that the performance of the membrane electrode is improved by the method of immersion and graded spraying. It can be seen from the ionic impedance of the membrane electrode that the ionic impedance of the membrane electrode prepared by this method is small, only 1.37mΩ, while the ionic impedance of membrane electrode 11 is 3.08mΩ, indicating that a direct contact blockage is formed due to the presence of water. Under low humidity, the ionic impedance of membrane electrode 5 increases to 6.06mΩ, while the ionic impedance of membrane electrode 11 is 29.84mΩ, indicating that the swelling caused by immersion and the graded spraying method can effectively improve the integrity of the membrane electrode ion transmission channel, proving that the catalytic layer uses part of the ionomer in the ion membrane as the ionomer of the catalyst. The application of the graded spraying method can reduce the situation where too much ionomer in the catalytic layer of Examples 1-4 may cause catalyst poisoning, adapt the ionomer ratio in the catalytic layer, and effectively improve the performance expression of the membrane electrode.

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

[0085] This embodiment uses a method for constructing the interface between the ion membrane and the catalyst layer to prepare the membrane electrode 6. The alkaline ion membrane is cut into a square of 7×7 cm. The clean ion 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 a state of membrane swelling, chemical bond opening and closing, and phase change, and then stored for future use.

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

[0087] Under the operating conditions of H2 / Air as the reaction gas and a reaction gas stoichiometric ratio of 2:2, the membrane electrode 6 was tested using a fuel cell test system. The results are as follows: Figure 8 As shown. Among them, the peak power density of membrane electrode 6 is 1.32W cm -2 , the maximum current density is 2.96 A cm -2 The peak power density of the membrane electrode 11 in comparative example 3 is 0.72 W cm -2 , the maximum current density is 1.81 A cm -2 , which are all lower than the membrane electrode performance of 6. This shows that the simultaneous regulation of the ion membrane in the swelling, phase change, and chemical bond opening and closing states also has a certain improvement on the membrane electrode. Since the simultaneous regulation of the three requires more parameter settings, the improvement of the membrane electrode in this embodiment is limited, but it does not hinder the improvement of the effectiveness of the membrane electrode after the simultaneous regulation of the three in this embodiment.

[0088] Example 7 Regulating the ion membrane in a phase change state

[0089] This example uses a method for constructing the interface between the ion membrane and the catalyst layer to prepare a 25cm 2 Membrane electrode 7: The specific method steps include cutting the ion membrane into a 7×7 cm square, etching the ion membrane to a phase transition state, such as laser etching to produce a local phase transition, or other existing methods to induce a phase transition state, such as high-temperature heating to 90-150°C, in an air or nitrogen atmosphere to induce a phase transition, and then storing it for future use. Subsequent steps such as preparing the catalyst ink and coating are the same as those in Example 3.

[0090] Under the operating conditions of H2 / Air as the reaction gas and a reaction gas stoichiometric ratio of 2:2, the membrane electrode 7 was tested using a fuel cell test system. The results are as follows: Figure 9 As shown. Among them, the peak power density of membrane electrode 8 is 0.91W cm -2 , the maximum current density is 1.88 A cm -2 The peak power density of the membrane electrode 11 in comparative example 3 is 0.72 W cm -2 , the maximum current density is 1.81 A cm -2 , which are both lower than that of membrane electrode 7. This shows that the ion membrane undergoes phase change, and the ionomer in the ion membrane changes from a compact structure to a loose structure. The catalyst ink can easily enter the ion membrane and combine with the ion membrane to form an integrated structure, which weakens the phase separation between the ion membrane and the catalyst ink and reduces the number of local pores, which has a certain effect on improving the performance of the membrane electrode.

[0091] Example 8: Regulating the ion membrane in a chemical bond opening and closing state

[0092] This example uses a method for constructing the interface between the ion membrane and the catalyst layer to prepare a 25cm 2 The membrane electrode is formed by cutting the ion membrane into a 7×7 cm square, using existing methods to make the ion membrane chemically open and close, and then storing it for future use. The subsequent steps of preparing the catalyst ink and coating are the same as those in Example 3.

[0093] Example 9

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

[0095] Cut the A20 alkaline membrane into 5×5 cm squares, soak the clean alkaline membrane in 1 molar potassium hydroxide solution to make the ion membrane swell, and store it for future use.

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

[0097] Set a 5cm gap in the middle of the ion membrane 2 The serpentine flow channel is coated on the area, the alkaline ion membrane soaked in potassium hydroxide is directly attached to the coating device and fixed, and the cathode catalyst ink is placed on the coating device.

[0098] Turn on the coating platform, set the temperature to 60°C, and cycle through the X-axis serpentine channel to coat the cathode catalyst ink, and then the Y-axis serpentine channel to coat the cathode catalyst ink, for 5 minutes; then raise the temperature to 80°C until the coating is completed to form a cathode catalyst layer.

[0099] Place the ion membrane coated with the cathode catalyst layer in water and soak it for 10 minutes. Then, attach the anode side that is not coated with the catalyst layer to the coating platform and fix it. Place the anode catalyst ink in the coating equipment and set the temperature to 60°C. Cycle the X-axis serpentine flow channel to coat the anode catalyst ink and the Y-axis serpentine flow channel to coat the anode catalyst ink in turn. The coating lasts for 5 minutes. Then increase the temperature to 80°C until the coating is completed to form the anode catalyst layer.

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

[0101] At the same time, a conventional alkaline membrane electrode 12 was prepared as Comparative Example 4 by using a conventional method (such as Comparative Example 3, but the anode and cathode loadings were the same as those of the membrane electrode 8).

[0102] Under the operating conditions of H2 / O2 as the reaction gas and 0.5L / min as the reaction gas flow rate, the membrane electrode 8 and membrane electrode 12 were tested using the fuel cell test system. The results are as follows: Figure 10 As shown. The left vertical axis represents E / V, which represents voltage; the right vertical axis represents P / W, which represents power density; and the horizontal axis represents j / A, which represents current density. The peak power density of membrane electrode 8 is 1.06Wcm -2 , the maximum current density is 2.40Acm -2The peak power density of the membrane electrode 12 as a comparison sample is 0.55W cm -2 , the maximum current density is 1.41Acm -2 , which are all lower than membrane electrode 8. This shows that even under alkaline conditions, by treating the alkaline membrane with the method required by this patent, the alkaline ion membrane is kept in a certain swelling state, which can effectively change the phase separation, build an efficient interface between the ion membrane and the catalytic layer, and effectively improve 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 present invention. Anyone skilled in the art may 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 one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

[0104] Comparative Example 1

[0105] This comparative example prepared 25cm 2 Conventional membrane electrode 9, cut M778.12 ion membrane into 7×7 cm squares and store them for future use without processing.

[0106] In this embodiment, the platinum loading of the prepared membrane electrode anode and cathode is 0.4 mg / cm 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 respectively, and water and isopropanol were used as solvents to keep 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 at 0.5. They were uniformly dispersed by ultrasonication and used as cathode catalyst ink and anode catalyst ink respectively.

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

[0108] The coating platform was turned on, the temperature was set to 80° C., and serpentine flow channel coating was performed until the coating was completed to form a cathode catalyst layer.

[0109] The ion membrane coated with the cathode side catalyst layer is turned over 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 to form the anode catalyst layer.

[0110] The gas diffusion layer is cut into pieces with an area of ​​5×5 cm and subjected to hot pressing to form a membrane electrode 9 prepared by a conventional method.

[0111] Under the operating conditions of H2 / Air as the reaction gas and a reaction gas stoichiometric ratio of 2:2, the membrane electrode 9 was tested using a fuel cell test system. The results are as follows: Figure 3 The peak power density of membrane electrode 9 is 1.45W cm -2 , the maximum current density is 2.71Acm -2 , which are lower than the performance of the membrane electrodes prepared in Examples 1 and 2. This shows that the membrane electrode prepared in Example 1 with a higher catalyst loading has a good gas-liquid transmission channel, the interface phase separation is greatly reduced, and the performance is greatly improved.

[0112] Comparative Example 2

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

[0114] Comparative Example 3

[0115] This comparative example prepared 25cm 2 Ultra-low-load conventional membrane electrode 11, cut the M778.12 ion membrane into 7×7 cm squares and store them for future use without processing.

[0116] In this embodiment, the cathode and anode loadings of the prepared membrane electrode are 0.05 mg / cm 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 respectively, and water and isopropanol were used as solvents to keep the solid content of the catalyst in the solvent at 2 mg / mL. Then a certain amount of ionomer was added to maintain I / C at 0.5. The catalyst inks were ultrasonically dispersed uniformly and used as cathode catalyst ink and anode catalyst ink respectively.

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

[0118] The coating platform was turned on, the temperature was set to 80° C., and serpentine flow channel coating was performed until the coating was completed to form a cathode catalyst layer.

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

[0120] The gas diffusion layer is cut into pieces with an area of ​​5×5 cm and subjected to a hot pressing process to form a membrane electrode 11 .

[0121] Under the operating conditions of H2 / Air as the reaction gas and a reaction gas stoichiometric ratio of 2:2, the membrane electrode 7 was tested using a fuel cell test system. The results are as follows: Figure 5-9 As shown. The left vertical axis represents E / V, which represents voltage; the right vertical axis represents P / W, which represents power density; the horizontal axis represents j / A, which represents current density. The peak power density of membrane electrode 7 is 0.72W cm -2 , the maximum current density is 1.81Acm -2 , which are lower than those of the membrane electrodes prepared in Examples 5-9. This shows that under the condition of low catalyst loading, the membrane electrodes prepared in Examples 5-9 have a more significant improvement compared to traditional membrane electrodes, with stronger interfacial bonding ability, significant catalyst three-phase interface construction, and the formed three-dimensional network for excellent water vapor management of the membrane electrode.

Claims

1. A method for constructing an interface between an ion membrane and a catalyst layer, characterized in that: include: Step 1: regulating the ion membrane to be in a specific state of any one or more combinations of swelling, phase change and opening and closing of chemical bonds; Step 2: preparing cathode catalyst ink and anode catalyst ink; Step 3: Setting the coating temperature to 20-60°C, coating the cathode catalyst ink on one of the sides of the ion membrane in a specific state. In the final stage of the process, the coating temperature is increased to 61-80°C until the coating is completed to form a cathode catalyst layer. Step 4: Set the temperature of the coating platform to 20-60°C, and apply the anode catalyst ink to the side of the ion membrane that has not been coated. In the final stage of the process, increase the coating temperature to 61-80°C until the coating is completed to form the anode catalyst layer.

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

3. The method according to claim 1, characterized in that The cathode catalyst ink and the anode catalyst ink both include catalyst ink B and catalyst ink C; In step 2, catalyst ink B is prepared from specific solvent A and a catalyst, and catalyst ink C is prepared from specific solvent A, a catalyst, and an ionomer; specific solvent A is a mixed solution of water and isopropyl alcohol; In step 3, the temperature of the coating platform is set to 20-60°C. Catalyst ink B is first used to cyclically coat the X-axis and Y-axis serpentine flow channels for 1-20 minutes. The temperature is then raised to 61-80°C until the catalyst ink B is completely coated. Catalyst ink C is then used to cyclically coat the X-axis and Y-axis serpentine flow channels until the coating is complete. In step 4, the temperature of the coating platform is set to 20-60°C, and catalyst ink B is first used to cycle through the X-axis and Y-axis serpentine flow channel coating for 1-20 minutes, and then the temperature is increased to 61-80°C until the catalyst ink B is coated; then catalyst ink C is used to cycle through the X-axis and Y-axis serpentine flow channel coating until the coating is completed.

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

5. The method according to any one of claims 1 to 4, characterized in that After step 3 and before step 4, the ion membrane coated with the cathode catalyst layer is re-regulated so that it is in a specific state again.

6. The method according to claim 1, characterized in that In step 1, the regulation method is to heat the ion membrane to 90-150°C, or use a specific solvent, hereinafter referred to as specific solvent B, to perform a specific treatment method on the ion membrane, the treatment method including soaking, heating while soaking, spraying, heating to 90-150°C while spraying, spraying and etching, spraying and etching and heating to 90-150°C.

7. The method according to claim 6, characterized in that The specific solvent B is water, or a combination of water and any one of an alcohol, an acid, or a base, or a combination of an alcohol, an acid, and water, or a combination of an alcohol, a base, and water.

8. The method according to claim 6, characterized in that During the control, only one of the cathode side or the anode side of the ion membrane is sprayed with a specific solvent B, or a combination of spraying, etching and heating is performed.

9. The method according to claim 6, characterized in that When using an acidic specific solvent B to soak an alkaline ion membrane, or using an alkaline specific solvent B to soak an acidic ion membrane, after spraying the catalytic layer, the alkaline or acidic ion membrane needs to be soaked again in a solvent with the same acidity or alkalinity.

10. 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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