A method for preparing a three-dimensionally ordered structure membrane electrode

Abstract

The application relates to the technical field of batteries, in particular to a preparation method of a three-dimensional ordered structure membrane electrode, which comprises the following steps: self-assembling a hydroxylated carbon-based substrate after mixing double templates, drying to obtain a three-dimensional ordered substrate; performing plasma treatment on the substrate to generate active hydroxyl groups; mixing a catalyst, anion exchange resin with double cross-linking groups and the like to prepare a functionalized catalyst slurry through ultrasonic treatment; coating the slurry through inkjet printing to form a gradient-pore catalyst layer through multiple layers, and drying to obtain a gas diffusion electrode; modifying an anion exchange membrane through silane coupling agent treatment; immersing the modified membrane and the electrode into an alkaline solution for constant-temperature soaking, and then drying in nitrogen; cross-linking by step-by-step pressurizing the modified membrane clamped between two electrodes; demolding the templates with acid liquid and organic solvent, and then drying after performing perfluorosulfonic acid treatment. The method greatly improves the interlayer bonding force of the membrane electrode through the core-shell three-dimensional ordered structure and click cross-linking, effectively prevents delamination, optimizes the mass transfer path through gradient-pore design, enhances the mass transfer efficiency, and reduces the battery internal resistance.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a method for preparing a three-dimensional ordered structure film electrode. Background Technology

[0002] With the gradual depletion of fossil fuels and the increasing severity of the greenhouse effect, the exploration of clean and efficient energy technologies is urgently needed. Fuel cells, due to their ability to utilize clean energy and their high energy efficiency, have become an important research direction in the energy field. Among them, ion exchange membrane fuel cells, as low-temperature batteries, are regarded as a new generation of energy engines due to their simple structure and low operating temperature. Although proton exchange membrane fuel cells (PEMFCs) have received close attention and some development from the academic community in the past decade, the high cost of the ion exchange membranes and catalysts they use has greatly limited their large-scale promotion.

[0003] Against this backdrop, alkaline fuel cells (AEMFCs) utilize OH- as the conductive ion. - This allows for the use of non-precious metals as catalysts, significantly reducing costs and gradually becoming a potential alternative to PEMFCs. However, OH... - The ion migration rate is only H + One-third of the energy density of AEMFC results in a lower energy density than PEMFC, thus reducing battery internal resistance and increasing OH-. - The conductivity rate in ion exchange membranes has become a core requirement for improving the performance of AEMFC.

[0004] As a key component of AEMFC (Automatic Electrode Fuel Cell), the membrane electrode assembly (MEA) is the core site of the battery reaction. It must perform both ion transport and electron conduction, and its performance directly affects the overall performance of the AEMFC. The quality of the interfacial contact between the ion exchange membrane and the catalyst layer is particularly critical. Currently, although some technologies have attempted to improve MEA fabrication, such as the membrane / catalyst interlocking interface preparation method reported in the German journal *Advanced Materials*, which involves creating micropatterns on the surface of sulfonated polyethersulfone (SPAES) membranes and using the Nafion layer to form an interlocking interface similar to Lego bricks to improve adhesion, this method relies on physical bonding. Furthermore, the SPAES and Nafion layers have poor compatibility, posing a risk of detachment. Additionally, it results in slow ion transport and high mass transfer resistance, failing to effectively improve fuel cell performance.

[0005] Furthermore, in existing AEMFC membrane electrode fabrication, even with the use of crosslinking techniques to enhance interfacial bonding, there is often a lack of three-dimensional ordered structural design, resulting in disordered internal pores and making it difficult to solve the delamination problem at the structural level; the disordered pore structure also hinders OH... -The transport of reactant gases reduces mass transfer efficiency, failing to meet the high performance and high stability requirements of AEMFC. Therefore, developing a preparation method that can effectively prevent membrane electrode delamination and enhance mass transfer has become the key to promoting the development of AEMFC. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides a method for preparing a three-dimensional ordered structure membrane electrode.

[0008] (II) Technical Solution

[0009] A method for fabricating a three-dimensional ordered membrane electrode includes the following steps:

[0010] S1, the first template agent and the second template agent are mixed in proportion, and a core-shell three-dimensional ordered array is formed on the hydroxylated carbon-based substrate by self-assembly. After drying, a three-dimensional ordered substrate is obtained.

[0011] S2, a three-dimensional ordered substrate is placed in a plasma processor and treated with a mixed gas to generate active hydroxyl groups on the substrate surface;

[0012] S3, the catalyst, anion exchange resin with double cross-linking groups, mixed solvent and dispersing agent are mixed and ultrasonically dispersed to obtain functionalized catalyst slurry;

[0013] S4. The catalyst slurry is coated on the pre-activated substrate in multiple layers using inkjet printing technology. After drying, a gradient porous catalyst layer is formed, resulting in a three-dimensional ordered gas diffusion electrode.

[0014] S5, the anion exchange membrane is immersed in a silane coupling agent solution for treatment, rinsed and dried to obtain a modified anion exchange membrane;

[0015] S6. The modified membrane and the gas diffusion electrode are immersed in an alkaline solution under constant temperature and vibration, and then dried under nitrogen protection.

[0016] S7, the modified membrane is sandwiched between two gas diffusion electrodes, pressurized stepwise, and then heated and kept warm in a closed environment to cause the membrane and the catalyst layer to undergo click crosslinking;

[0017] S8, the dual template is removed sequentially with acid solution and organic solvent, then treated with perfluorosulfonic acid solution and dried to obtain a three-dimensional ordered structure membrane electrode. This membrane electrode prevents delamination through core-shell three-dimensional channels and enhances mass transfer through gradient pores.

[0018] Preferably, in step S1, the first template agent is silica nanospheres with a particle size of 200-400 nm, and the second template agent is polystyrene nanospheres with a particle size of 50-150 nm, with a mass ratio of (1-3):1; self-assembly is performed using a vertical deposition method, and the drying conditions are drying at 80-100℃ for 2-4 h; the carbon-based substrate is Toray TGP-H-060 carbon paper, and the hydroxylation treatment is performed by immersing the carbon paper in a 5-10% hydrogen peroxide solution, stirring at 60-70℃ for 2-3 h, rinsing and drying until the surface hydroxyl content is 1.5-2.5 mmol / g.

[0019] Preferably, the catalyst in step S3 is a PtNi alloy / C catalyst with a loading of 20-40 wt%, which is prepared by dissolving H2PtCl6·6H2O and Ni(NO3)2·6H2O in ethylene glycol at a molar ratio of (1-2):1, adding a carbon support, refluxing at 120-150℃ for 4-6 h under nitrogen protection, centrifuging, washing and drying; the anion exchange resin is an imidazole resin with alkyne and azide groups, and the mass ratio of catalyst, resin, mixed solvent and dispersant is (60-85):(10-30):(100-150):(1-5).

[0020] Preferably, in step S5, the silane coupling agent solution is a 0.1-0.3 mol / L 3-glycidyl etheroxypropyltrimethoxysilane ethanol solution, and the treatment conditions are constant temperature stirring at 40-50℃ for 4-6 h; the siloxane grafting rate of the modified membrane is controlled at 5-10 wt%.

[0021] Preferably, in step S6, the alkaline solution is a 1.0-1.5 mol / L potassium hydroxide solution, the constant temperature oscillation temperature is 30-40℃, the oscillation rate is 150-200 r / min, and the soaking time is 10-14 h; the nitrogen-protected drying conditions are 50-60℃ for 6-8 h.

[0022] Preferably, the step-by-step pressurization in step S7 is as follows: first, pre-pressurize at 0.6-0.8 MPa for 30-60 s, then heat to 50-60℃, pressurize to 1.2-1.4 MPa and hold for 120-180 s; the crosslinking environment is a closed reactor that has been purged with nitrogen 3-5 times, the crosslinking temperature is 75-85℃, the pressure is 0.1-0.2 MPa, the holding time is 12-18 h, the heating rate is 2-3℃ / min, and the cooling rate is 1-2℃ / min.

[0023] Preferably, in step S8, the acid solution is a 10-15% hydrofluoric acid solution, soaked at 25-35℃ for 2-3 hours to remove the silica template; the organic solvent is a 5-8% tetrahydrofuran solution, soaked at 40-50℃ for 1-2 hours to remove the polystyrene template; the total pore volume of the membrane electrode is controlled at 0.8-1.2 cm³ / g, with mesopores (2-50 nm) accounting for 10-20% and macropores (50-500 nm) accounting for 80-90%.

[0024] Preferably, in step S3, the mixed solvent is isopropanol and N,N-dimethylformamide mixed at a volume ratio of (3-5):1, and the dispersant is polyethylene glycol 400; the viscosity of the catalyst slurry is controlled at 200-500 mPa·s and tested by a rotational viscometer at 25°C and 60 r / min.

[0025] Preferably, the inkjet printing parameters in step S4 are: printhead moving speed 5-10 mm / s, inkjet frequency 200-300 Hz, and droplet volume 10-20 pL; coating in 3-5 layers, each layer with a thickness of 5-10 μm, and drying under vacuum at 50-60℃ for 1-2 h; the catalyst layer surface pore size is 80-120 nm, the bottom layer pore size is 200-300 nm, and the porosity is 35-55%.

[0026] Preferably, in step S8, the concentration of the perfluorosulfonic acid solution is 0.05-0.1 mol / L, and the treatment conditions are soaking at 25-30℃ for 3-5 hours; the sulfonic acid group loading on the membrane electrode surface is 0.5-1.0 mmol / g.

[0027] (iii) Beneficial technical effects

[0028] Compared with existing technologies, the beneficial effects of this invention are:

[0029] 1. By constructing a core-shell three-dimensional ordered structure through dual template collaboration and combining it with click crosslinking technology, the anion exchange membrane and the catalyst layer form a stable integrated structure. Compared with the physical interlocking interface bonding method in the existing technology, this solves the problem of interlayer delamination caused by poor compatibility. The interlayer bonding force of the membrane electrode is significantly enhanced, and the structural stability during long-term use is greatly improved, effectively avoiding the negative impact of delamination on battery performance.

[0030] 2. By employing a gradient porous catalyst layer and a three-dimensional ordered pore structure, the mass transfer pathway within the membrane electrode was optimized, significantly shortening the OH phase transition time. - The reduced transport distance with the reactant gas lowers transport resistance, resulting in significantly improved mass transfer efficiency compared to existing membrane electrodes with disordered pore structures. This effectively reduces the battery's internal resistance and alleviates the problem of OH-induced mass transfer in AEMFCs. - The low migration rate, which leads to insufficient energy density, lays a key foundation for improving battery performance.

[0031] 3. By modifying the anion exchange membrane with silane coupling agents and matching the functionalized resin in the catalyst layer, the electrochemical reactivity of the membrane electrode was further improved. The stepwise compaction process ensured the integrity of the three-dimensional ordered structure, while the pore modification treatment optimized the surface properties and alkali resistance of the membrane electrode. As a result, the membrane electrode outperformed products prepared by existing methods in terms of mechanical strength, electrochemical performance, and long-term stability. It can better meet the high performance and high reliability requirements of AEMFC and provides strong technical support for the large-scale application of alkaline fuel cells. Attached Figure Description

[0032] Figure 1 This is a flowchart of a method for preparing a three-dimensional ordered membrane electrode disclosed in this invention;

[0033] Figure 2 The interlayer peel strength and OH of the examples and comparative examples - Conduction rate histogram comparison;

[0034] Figure 3 This is a line graph comparing the tensile strength and elongation at break of the embodiments and comparative examples;

[0035] Figure 4 This is a radar comparison chart created by standardizing the dimensions of the performance comparison data of the examples and comparative examples. Detailed Implementation

[0036] according to Figures 1 to 4 The specific embodiments of the present invention are as follows:

[0037] The technical solution of the present invention will be described in detail below with reference to specific embodiments, so that those skilled in the art can clearly understand and repeat the present invention. The raw materials and instruments mentioned are all commercially available conventional products, and the process conditions not specifically mentioned are all conventional laboratory operating conditions.

[0038] Example 1

[0039] S1. Carbon paper with a thickness of 0.2 mm and a porosity of 75% was selected as the carbon-based substrate and subjected to hydroxylation treatment. 500 mL of 5% hydrogen peroxide solution was poured into a beaker, and the carbon paper, cut to 10 cm × 10 cm, was completely immersed in the solution. The beaker was placed in a 60°C constant temperature water bath and stirred at 200 rpm for 2 hours. The carbon paper was then removed and repeatedly rinsed with deionized water until the washing solution was neutral. The carbon paper was then dried in an 80°C forced-air drying oven for 4 hours. The hydroxyl content on the substrate surface was determined to be 1.5 mmol / g by potentiometric titration.

[0040] Silica nanospheres with a particle size of 200 nm were selected as the first template agent, and polystyrene nanospheres with a particle size of 50 nm were selected as the second template agent. 10 g of each was weighed at a mass ratio of 1:1 and added together to 200 mL of deionized water. The mixture was ultrasonically dispersed for 30 min until it was homogeneous and free of precipitate, resulting in a dual-template dispersion. Using a vertical deposition self-assembly method, hydroxylated carbon paper was vertically inserted into the dual-template dispersion, with the liquid level descent rate controlled at 0.5 mm / h. After the liquid level completely detached from the carbon paper surface, the carbon paper was transferred to an 80℃ drying oven and dried for 4 h. A uniform core-shell three-dimensional ordered array formed on the carbon paper surface, resulting in a three-dimensional ordered substrate.

[0041] S2. Place the three-dimensional ordered substrate into the plasma treatment instrument. After closing the chamber door, introduce a mixture of argon and oxygen gas with a volume ratio of 5:1. Adjust the instrument power to 150W and the chamber pressure to 0.05MPa. Maintain these conditions for 10 minutes to generate active hydroxyl groups on the substrate surface. After treatment, allow it to cool naturally to room temperature for later use.

[0042] S3. First, the PtNi alloy / C catalyst was prepared. 0.5 mmol of H₂PtCl₆·6H₂O and 0.5 mmol of Ni(NO₃)₂·6H₂O were weighed at a molar ratio of 1:1 and dissolved in 100 mL of ethylene glycol. The solution was magnetically stirred for 30 min until completely dissolved. Then, 5 g of Vulcan XC-72 carbon support was added, and the mixture was transferred to a three-necked flask. Nitrogen gas was bubbled into the three-necked flask three times to purge it. Under nitrogen protection, the three-necked flask was refluxed in a 120℃ oil bath for 4 h. After the reaction was complete, the mixture was cooled to room temperature, transferred to a centrifuge tube, and centrifuged at 8000 r / min for 10 min. The precipitate at the bottom was collected. The precipitate was repeatedly washed with deionized water until no chloride ions were detected in the washings and no white precipitate formed when tested with silver nitrate solution. The precipitate was then dried in an 80℃ vacuum drying oven for 6 h to obtain a 20 wt% PtNi alloy / C catalyst.

[0043] Weigh out 6g of the prepared PtNi alloy / C catalyst, 1g of imidazole anion exchange resin with alkynyl and azido groups, 100g of mixed solvent, and 0.1g of polyethylene glycol 400 according to a mass ratio of 60:10:100:1. The mixed solvent is a mixture of isopropanol and N,N-dimethylformamide in a volume ratio of 3:1. Add the above raw materials sequentially to an agate grinding jar, grind manually for 30 minutes, then transfer to an ultrasonic disperser and ultrasonically disperse at 300W for 90 minutes. The viscosity of the slurry was measured at 25℃ and 60r / min using a rotational viscometer, and the viscosity was 200mPa·s, yielding a uniform, non-agglomerated functionalized catalyst slurry.

[0044] S4. Using an inkjet printer with adjustable droplet volume, the functionalized catalyst slurry was loaded into the printer's ink cartridge. Printing parameters were set as follows: printhead movement speed 5 mm / s, inkjet frequency 200 Hz, and droplet volume 10 pL. The pre-activated three-dimensional ordered substrate was fixed on the printing platform, and the printer was started to coat the catalyst slurry in three layers. After each layer was coated, the substrate was immediately placed in a 50°C vacuum drying oven for 1 hour. The coating thickness was monitored in real time using a laser thickness gauge, and each layer was controlled to a thickness of 5 μm. After coating and drying, a gradient porous catalyst layer with a surface pore size of 80 nm, a bottom pore size of 200 nm, and a porosity of 35% was formed. Three-dimensional ordered gas diffusion electrodes were then prepared for the cathode and anode, respectively.

[0045] S5, weigh 0.02 mol of 3-glycidyl etheroxypropyltrimethoxysilane, dissolve it in 100 mL of anhydrous ethanol, and stir magnetically for 15 min until completely dissolved to obtain a 0.2 mol / L silane coupling agent solution. Select an anion exchange membrane with a thickness of 30 μm and an ion exchange capacity of 1.2 mmol / g, cut it to a size of 10 cm × 10 cm, and immerse it in the above silane coupling agent solution. Place the beaker in a 40℃ constant temperature water bath and stir at a rate of 150 r / min for 4 h. Remove the anion exchange membrane, rinse it three times with anhydrous ethanol, each rinse lasting 5 min, and dry it in a 60℃ forced-air drying oven for 4 h.

[0046] S6. Prepare 500 mL of a 1.0 mol / L potassium hydroxide solution and pour it into a container equipped with a constant-temperature shaking function. Immerse the modified anion exchange membrane, cathode gas diffusion electrode, and anode gas diffusion electrode together in the solution. Set the shaking temperature of the container to 30℃, the shaking rate to 150 r / min, and the soaking time to 10 h. After soaking, remove the components, rinse the surface with deionized water to remove any residual alkaline solution, and transfer them to a nitrogen-protected drying oven to dry at 50℃ for 6 h.

[0047] S7. The pretreated modified anion exchange membrane is sandwiched between the cathode gas diffusion electrode and the anode gas diffusion electrode, ensuring that the catalyst layer faces the anion exchange membrane. The assembled component is then placed in a hot press molding machine. A pressure of 0.6 MPa is applied for pre-compression for 30 seconds, followed by a temperature increase to 50°C at a rate of 2°C / min, while simultaneously increasing the pressure to 1.2 MPa. This pressure and temperature are maintained for 120 seconds. The component is then removed and placed in a sealed reactor. Nitrogen gas is introduced into the reactor three times to purge it, the outlet is closed, and the temperature inside the reactor is adjusted to 75°C and the pressure to 0.1 MPa. The reactor is held at this temperature for 12 hours to initiate the click crosslinking reaction. After the reaction, the temperature is lowered to room temperature at a rate of 1°C / min, and the reactor is opened to remove the component.

[0048] S8. Prepare 200 mL of a 10% hydrofluoric acid solution. Immerse the cross-linked component in the solution and soak it at a constant temperature of 25℃ for 2 hours to remove the silica template. Remove the component and rinse it three times with deionized water for 5 minutes each time. Then immerse it in a 5% tetrahydrofuran solution and soak it at 40℃ for 1 hour to remove the polystyrene template. Prepare 100 mL of a 0.05 mol / L perfluorosulfonic acid solution. Immerse the component in the solution and let it stand at 25℃ for 3 hours. Remove the component and dry it in a vacuum drying oven at 60℃ for 4 hours. The loading of sulfonic acid groups on the membrane electrode surface was determined to be 0.5 mmol / g by potentiometric titration, finally obtaining a three-dimensional ordered membrane electrode structure.

[0049] Example 2

[0050] S1. Carbon paper with a thickness of 0.2 mm and a porosity of 75% was selected as the carbon-based substrate and subjected to hydroxylation treatment. 500 mL of 8% hydrogen peroxide solution was measured, and carbon paper cut to 10 cm × 10 cm was immersed in the solution. The solution was placed in a 65℃ constant temperature water bath and stirred at 250 r / min for 2.5 h. The carbon paper was then removed, rinsed with deionized water until neutral, and dried in a 90℃ forced-air drying oven for 3 h. The hydroxyl content on the substrate surface was determined to be 2.0 mmol / g by potentiometric titration.

[0051] The first template agent was silica nanospheres with a particle size of 300 nm, and the second template agent was polystyrene nanospheres with a particle size of 100 nm. 10 g of silica nanospheres and 5 g of polystyrene nanospheres were weighed at a mass ratio of 2:1 and added to 200 mL of deionized water. The mixture was ultrasonically dispersed for 30 min until homogeneous, resulting in a dual-template dispersion. A vertical deposition self-assembly method was used, in which hydroxylated carbon paper was vertically inserted into the dispersion, with the liquid level descent rate controlled at 0.8 mm / h. After deposition, the carbon paper was transferred to a 90℃ drying oven and dried for 3 h. A core-shell three-dimensional ordered array formed on the surface of the carbon paper, resulting in a three-dimensional ordered substrate.

[0052] S2. Place the three-dimensional ordered substrate into the plasma treatment instrument and introduce a mixture of argon and oxygen in a volume ratio of 6:1. Adjust the instrument power to 200W and the chamber pressure to 0.08MPa, and maintain these conditions for 15 minutes to generate active hydroxyl groups on the substrate surface. After treatment, allow it to cool naturally to room temperature for later use.

[0053] S3: Weigh 0.75 mmol of H₂PtCl₆·6H₂O and 0.5 mmol of Ni(NO₃)₂·6H₂O at a molar ratio of 1.5:1, dissolve them in 100 mL of ethylene glycol, stir until completely dissolved, then add 5 g of Vulcan XC-72 carbon support and transfer to a three-necked flask. Purge the three-necked flask with nitrogen three times, and reflux in an oil bath at 135 °C for 5 h under nitrogen protection. After the reaction is complete, cool to room temperature, transfer the mixture to a centrifuge tube, centrifuge at 8000 r / min for 10 min, collect the precipitate, wash with water until no chloride ions are present, and dry in a vacuum drying oven at 90 °C for 5 h to obtain a 30 wt% PtNi alloy / C catalyst.

[0054] Weigh out 7g of the above PtNi alloy / C catalyst, 2g of imidazole anion exchange resin with alkynyl and azido groups, 120g of mixed solvent, and 0.3g of polyethylene glycol 400 according to a mass ratio of 70:20:120:3. The mixed solvent is a mixture of isopropanol and N,N-dimethylformamide in a volume ratio of 4:1. Add the raw materials sequentially to an agate grinding jar, grind for 30 minutes, and then transfer to an ultrasonic disperser. Disperse the mixture at 300W for 120 minutes. The viscosity of the slurry was measured by a rotational viscometer at 25℃ and 60r / min, and the viscosity was 350mPa·s, yielding a uniform functionalized catalyst slurry.

[0055] S4. Using an inkjet printer with adjustable droplet volume, the functionalized catalyst slurry was loaded into the ink cartridge, and the printing parameters were set as follows: printhead movement speed 8 mm / s, inkjet frequency 250 Hz, and droplet volume 15 pL. The pre-activated three-dimensional ordered substrate was fixed on the printing platform, and the catalyst slurry was coated in four layers. After each layer was coated, it was placed in a vacuum drying oven at 55°C for 1.5 h. The thickness of each coating layer was controlled to 8 μm by real-time monitoring with a laser thickness gauge. Finally, a gradient porous catalyst layer with a surface pore size of 100 nm, a bottom pore size of 250 nm, and a porosity of 45% was formed, and three-dimensional ordered gas diffusion electrodes corresponding to the cathode and anode were prepared respectively.

[0056] S5. Weigh 0.02 mol of 3-glycidyl etheroxypropyltrimethoxysilane and dissolve it in 100 mL of anhydrous ethanol. Stir until homogeneous to obtain a 0.2 mol / L silane coupling agent solution. Select an anion exchange membrane with a thickness of 30 μm and an ion exchange capacity of 1.2 mmol / g, cut it into 10 cm × 10 cm pieces, immerse it in the solution, and place it in a 45℃ constant temperature water bath. Stir at a rate of 150 r / min for 5 h. Remove the exchange membrane and rinse it four times with anhydrous ethanol for 5 min each time. Dry it in a 65℃ forced-air drying oven for 3 h. S6. Prepare 500 mL of 1.2 mol / L potassium hydroxide solution and pour it into a constant temperature shaking container. Immerse the modified anion exchange membrane, cathode gas diffusion electrode, and anolyte gas diffusion electrode together in the solution. Set the shaking temperature to 35℃, the shaking rate to 180 r / min, and the immersion time to 12 h. After soaking, remove the components, rinse the surface with deionized water to remove any residual solution, and transfer them to a nitrogen-protected drying oven to dry at 55°C for 7 hours.

[0057] S7. The modified anion exchange membrane is sandwiched between the cathode and anode gas diffusion electrodes, with the catalyst layer facing the membrane side, and placed in a hot press molding machine. A pre-compression of 0.7 MPa is applied for 30 seconds, followed by a temperature increase to 55°C at a rate of 2.5°C / min, while simultaneously increasing the pressure to 1.3 MPa and holding the pressure for 150 seconds. The module is then removed and placed in a sealed reactor, purged with nitrogen four times, and the reactor temperature is adjusted to 80°C and the pressure to 0.15 MPa. The reactor is held at this temperature for 15 hours to initiate the click crosslinking reaction. After the reaction, the module is cooled to room temperature at a rate of 1.5°C / min and then removed.

[0058] S8. Prepare 200 mL of a 12% hydrofluoric acid solution. Immerse the cross-linked component in the solution and soak it at a constant temperature of 30℃ for 2.5 h to remove the silica template. Remove the component and rinse it three times with deionized water. Then immerse it in a 7% tetrahydrofuran solution and soak it at 45℃ for 1.5 h to remove the polystyrene template. Prepare 100 mL of a 0.08 mol / L perfluorosulfonic acid solution. Immerse the component in the solution and let it stand at 28℃ for 4 h. After removal, dry it in a vacuum drying oven at 65℃ for 3 h. The loading of sulfonic acid groups on the membrane electrode surface was determined to be 0.8 mmol / g by potentiometric titration, thus obtaining a three-dimensional ordered membrane electrode structure.

[0059] Example 3

[0060] S1. Carbon paper with a thickness of 0.2 mm and a porosity of 75% was selected as the carbon-based substrate and subjected to hydroxylation treatment. 500 mL of a 10% (w / w) hydrogen peroxide solution was measured, and carbon paper cut to 10 cm × 10 cm was immersed in the solution. The solution was then placed in a 70°C constant temperature water bath and stirred at 300 rpm for 3 hours. The carbon paper was removed, rinsed with deionized water until neutral, and dried in a 90°C forced-air drying oven for 4 hours. The hydroxyl content on the substrate surface was determined to be 2.5 mmol / g by potentiometric titration.

[0061] The first template agent was silica nanospheres with a particle size of 400 nm, and the second template agent was polystyrene nanospheres with a particle size of 150 nm. 15 g of silica nanospheres and 5 g of polystyrene nanospheres were weighed at a mass ratio of 3:1 and added to 200 mL of deionized water. The mixture was ultrasonically dispersed for 30 min until homogeneous, yielding a dual-template dispersion. A vertical deposition self-assembly method was used, in which hydroxylated carbon paper was vertically inserted into the dispersion, with the liquid level descent rate controlled at 1 mm / h. After deposition, the carbon paper was transferred to a 100℃ drying oven and dried for 2 h. A core-shell three-dimensional ordered array formed on the surface of the carbon paper, resulting in a three-dimensional ordered substrate.

[0062] S2. Place the three-dimensional ordered substrate into a plasma treatment instrument and introduce a mixture of argon and oxygen in a volume ratio of 8:1. Adjust the instrument power to 250W and the chamber pressure to 0.1MPa, and maintain these conditions for 20 minutes to generate active hydroxyl groups on the substrate surface. After treatment, allow it to cool naturally to room temperature for later use.

[0063] S3: Weigh 1.0 mmol of H2PtCl6·6H2O and 0.5 mmol of Ni(NO3)2·6H2O at a molar ratio of 2:1, dissolve in 100 mL of ethylene glycol, stir until completely dissolved, then add 5 g of Vulcan XC-72 carbon support and transfer to a three-necked flask. Purge the three-necked flask with nitrogen three times, and reflux in an oil bath at 150 °C for 6 h under nitrogen protection. After the reaction is complete, cool to room temperature, transfer the mixture to a centrifuge tube, centrifuge at 8000 r / min for 10 min, collect the precipitate, wash with water until no chloride ions are present, and dry in a vacuum drying oven at 100 °C for 4 h to obtain a 40 wt% PtNi alloy / C catalyst.

[0064] Weigh out 8.5g of the above PtNi alloy / C catalyst, 3g of imidazole anion exchange resin with alkynyl and azido groups, 150g of mixed solvent, and 0.5g of polyethylene glycol 400 according to a mass ratio of 85:30:150:5. The mixed solvent is a mixture of isopropanol and N,N-dimethylformamide in a volume ratio of 5:1. Add the raw materials sequentially to an agate grinding jar, grind for 30 minutes, and then transfer to an ultrasonic disperser. Disperse the mixture at 300W for 150 minutes. The viscosity of the slurry was measured using a rotational viscometer at 25℃ and 60r / min, and the viscosity was 500mPa·s, yielding a uniform functionalized catalyst slurry.

[0065] S4. Using an inkjet printer with adjustable droplet volume, the functionalized catalyst slurry was loaded into the ink cartridge, and the printing parameters were set as follows: printhead movement speed 10 mm / s, inkjet frequency 300 Hz, and droplet volume 20 pL. The pre-activated three-dimensional ordered substrate was fixed on the printing platform, and the catalyst slurry was coated in 5 layers. After each layer was coated, it was placed in a 60℃ vacuum drying oven for 2 hours. The thickness of each coating layer was controlled to 10 μm by real-time monitoring with a laser thickness gauge. Finally, a gradient pore catalyst layer with a surface pore size of 120 nm, a bottom pore size of 300 nm, and a porosity of 55% was formed, and three-dimensional ordered gas diffusion electrodes corresponding to the cathode and anode were prepared respectively.

[0066] S5, weigh 0.03 mol of 3-glycidyl etheroxypropyltrimethoxysilane, dissolve it in 100 mL of anhydrous ethanol, and stir until homogeneous to obtain a 0.3 mol / L silane coupling agent solution. Select an anion exchange membrane with a thickness of 30 μm and an ion exchange capacity of 1.2 mmol / g, cut it into 10 cm × 10 cm pieces, immerse it in the solution, and place it in a 50℃ constant temperature water bath. Stir at a rate of 150 r / min for 6 h. Remove the exchange membrane, rinse it 5 times with anhydrous ethanol for 5 min each time, and dry it in a 70℃ forced-air drying oven for 2 h.

[0067] S6. Prepare 500 mL of a 1.5 mol / L potassium hydroxide solution and pour it into a constant-temperature shaking container. Immerse the modified anion exchange membrane, cathode gas diffusion electrode, and anode gas diffusion electrode together in the solution. Set the shaking temperature to 40℃, the shaking rate to 200 r / min, and the soaking time to 14 h. After soaking, remove the components, rinse the surface with deionized water to remove any residual solution, and transfer them to a nitrogen-protected drying oven to dry at 60℃ for 8 h.

[0068] S7. The modified anion exchange membrane is sandwiched between the cathode and anode gas diffusion electrodes, with the catalyst layer facing the membrane side, and placed in a hot press molding machine. A pre-compression of 0.8 MPa is applied for 60 seconds, followed by a temperature increase to 60°C at a rate of 3°C / min, while simultaneously increasing the pressure to 1.4 MPa, and holding at that pressure for 180 seconds. The module is then removed and placed in a sealed reactor, purged with nitrogen five times, and the reactor temperature is adjusted to 85°C and the pressure to 0.2 MPa. The reactor is held at this temperature for 18 hours to initiate the click crosslinking reaction. After the reaction, the module is cooled to room temperature at a rate of 2°C / min and then removed.

[0069] S8. Prepare 200 mL of a 15% hydrofluoric acid solution. Immerse the cross-linked component in the solution and soak it at a constant temperature of 35℃ for 3 hours to remove the silica template. Remove the component and rinse it three times with deionized water. Then immerse it in an 8% tetrahydrofuran solution and soak it at 50℃ for 2 hours to remove the polystyrene template. Prepare 100 mL of a 0.1 mol / L perfluorosulfonic acid solution. Immerse the component in the solution and let it stand at 30℃ for 5 hours. After removal, dry it in a vacuum drying oven at 70℃ for 2 hours. The loading of sulfonic acid groups on the membrane electrode surface was determined to be 1.0 mmol / g by potentiometric titration, thus obtaining a three-dimensional ordered membrane electrode structure.

[0070] Comparative Example 1

[0071] Step 1: Weigh 10g of commercial anion exchange resin with an ion exchange capacity of 1.0 mmol / g, add 50mL of isopropanol, seal, and magnetically stir for 2 hours until the resin is completely dissolved to prepare an anion exchange resin solution. Weigh 1g of Pt / C catalyst and add it to the above anion exchange resin solution. Place the solution in an ultrasonic disperser and ultrasonically disperse for 1 hour to form a catalyst-resin mass ratio of 1:10 for the anode and cathode catalyst precursor slurry.

[0072] Step 2: Select a commercially available anion exchange resin membrane with a thickness of 28 μm, cut it to a size of 10 cm × 10 cm, and uniformly spray the catalyst precursor slurry prepared above onto both sides of the resin membrane, controlling the Pt loading to be 0.4 mg / cm². Place the sprayed resin membrane in a room temperature environment to air dry naturally until the solvent completely evaporates, obtaining the catalyst-coated electrode.

[0073] Step 3: Weigh activated carbon powder XC-72 and PTFE solution at a mass ratio of 1:5, add an appropriate amount of ethanol, and ultrasonically disperse in an ultrasonic disperser for 0.5 hours to form a uniform cathode microporous layer precursor slurry. Coat the slurry onto a 0.2 mm thick carbon paper using a scraping method. Calcine the coated carbon paper in a nitrogen atmosphere at 240°C for 1 hour, and after natural cooling, obtain the cathode gas diffusion layer. The carbon powder carrying capacity is 1 mg / cm².

[0074] Activated carbon powder XC-72 and PTFE solution were weighed at a mass ratio of 1:10, and an appropriate amount of ethanol was added. The mixture was ultrasonically dispersed for 0.5 hours to form a uniform anode microporous layer precursor slurry. A 0.2 mm thick carbon paper was immersed in the PTFE solution for hydrophobication treatment, resulting in a PTFE mass fraction of 5%. The carbon paper was then calcined in an argon atmosphere at 360°C for 2 hours and allowed to cool naturally to obtain a hydrophobic support layer. The anode microporous layer precursor slurry was coated onto the hydrophobic support layer using a blade coating method. The mixture was then calcined in a nitrogen atmosphere at 300°C for 1 hour and allowed to cool naturally to obtain an anode gas diffusion layer with a carbon powder carrying capacity of 1.5 mg / cm².

[0075] Step 4: The catalyst-coated electrode prepared above is sandwiched between the cathode gas diffusion layer and the anode gas diffusion layer and placed in a hot press for pressing. The hot pressing conditions are as follows: first, pre-press at 60°C with low pressure for 60s, then increase the pressure to 1MPa and maintain this pressure for 120s. After hot pressing, it is naturally cooled to room temperature to obtain a membrane electrode with a conventional structure.

[0076] As shown in Table 1:

[0077] Table 1 Comparison of basic membrane electrode performance between the examples and comparative examples

[0078]

[0079] As shown in Table 2:

[0080] Table 2 Comparison of the electrochemical performance and stability of the membrane electrodes in the examples and comparative examples.

[0081]

[0082] Compared to Comparative Example 1, which employs a traditional spray-coating-hot-pressing process and lacks a three-dimensional ordered structure design, this invention solves the problems of easy interlayer detachment and OH residues in traditional membrane electrodes through the innovation of "dual-template self-assembly to construct three-dimensional ordered channels + click crosslinking to enhance interfacial bonding + gradient pore optimization for mass transfer". - Addressing the core pain points of "slow conduction, low mass transfer efficiency, and poor stability," this study achieves a dual improvement in the structural stability and electrochemical performance of membrane electrodes.

[0083] The embodiment utilizes a core-shell three-dimensional ordered array formed by dual-template self-assembly, combined with click crosslinking technology, to achieve a stable chemical bond between the membrane and the catalyst layer, with an interlayer peel strength of 12.5-18.3 N / cm, thus solving the risk of detachment associated with traditional physical bonding. The three-dimensional ordered channel and gradient pore design increases the porosity of the catalyst layer, enhancing OH... -With a conduction rate of 0.085-0.105 S / cm, it shortens the ion-gas transport distance and reduces mass transfer resistance; with tensile strength of 28.6-36.8 MPa and elongation at break of 8.2%-11.3%, it surpasses the comparative ratio, demonstrating the strengthening effect of three-dimensional structure on mechanical properties.

[0084] The embodiment features a maximum power density of 395-518 mW / cm², an internal resistance of 61-85 mΩ·cm², and an open-circuit voltage of 1.02-1.05 V, demonstrating superior core performance. This superior performance stems from the synergistic effect of three-dimensional ordered channels and gradient pores, which ensures both high OH... - Rapid conduction also promotes the diffusion of reactive gases; after 500 cycles, the power retention rate is 88%-95%, the continuous operating time at 0.5V is 320-580 h, and the alkali resistance stability in 1mol / L KOH is 85%-93% after 1000 h, which confirms the interfacial stability of click crosslinking and the alkali resistance optimization effect of silane coupling agent modification, avoiding interlayer delamination and interfacial side reactions.

[0085] Example 3 exhibits the best overall performance, with a three-dimensional channel order of 97% and OH - With a conductivity of 0.105 S / cm, a maximum power density of 518 mW / cm², and a cycle retention rate of 95%, it fully demonstrates the synergistic optimization effect of "template ratio-catalyst loading-pore structure". In contrast, Comparative Example 1, due to the lack of three-dimensional ordered design and chemical cross-linking, has disordered pores and weak interface bonding, resulting in low mass transfer efficiency, easy delamination, and significantly inferior performance in all aspects.

[0086] In summary, this invention solves the mass transfer problem through three-dimensional ordered structure design, enhances interface stability through click crosslinking, and improves reactivity and alkali resistance through silane modification and gradient pore optimization. The three aspects work together to achieve a unified performance of "high binding strength, high ion conduction, high mass transfer efficiency, and high stability", breaking through the technical bottleneck of traditional membrane electrode assemblies and providing core technical support for the low-cost and large-scale application of alkaline fuel cells.

[0087] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for fabricating a three-dimensional ordered membrane electrode, characterized in that, Includes the following steps: S1, the first template agent and the second template agent are mixed in proportion, and a core-shell three-dimensional ordered array is formed on the hydroxylated carbon-based substrate by self-assembly. After drying, a three-dimensional ordered substrate is obtained. S2, a three-dimensional ordered substrate is placed in a plasma processor and treated with a mixed gas to generate active hydroxyl groups on the substrate surface; S3, the catalyst, anion exchange resin with double cross-linking groups, mixed solvent and dispersing agent are mixed and ultrasonically dispersed to obtain functionalized catalyst slurry; S4. The catalyst slurry is coated on the pre-activated substrate in multiple layers using inkjet printing technology. After drying, a gradient porous catalyst layer is formed, resulting in a three-dimensional ordered gas diffusion electrode. S5, the anion exchange membrane is immersed in a silane coupling agent solution for treatment, rinsed and dried to obtain a modified anion exchange membrane; S6. The modified anion exchange membrane and the gas diffusion electrode are immersed in an alkaline solution under constant temperature oscillation, and then dried under nitrogen protection. S7, the modified anion exchange membrane is sandwiched between two gas diffusion electrodes, pressurized stepwise, and then heated and kept warm in a closed environment to cause the membrane and the catalyst layer to undergo click crosslinking. S8, the dual template is removed sequentially with acid solution and organic solvent, then treated with perfluorosulfonic acid solution and dried to obtain a three-dimensional ordered structure membrane electrode. This membrane electrode prevents delamination through core-shell three-dimensional channels and enhances mass transfer through gradient pores.

2. The method for preparing a three-dimensional ordered membrane electrode according to claim 1, characterized in that, In step S1, the first template agent is silica nanospheres with a particle size of 200-400 nm, and the second template agent is polystyrene nanospheres with a particle size of 50-150 nm, with a mass ratio of (1-3):1; self-assembly is performed using a vertical deposition method, and the drying conditions are drying at 80-100℃ for 2-4 h; the carbon-based substrate is Toray TGP-H-060 carbon paper, and the hydroxylation treatment is as follows: the carbon paper is immersed in a 5-10% hydrogen peroxide solution, stirred at 60-70℃ for 2-3 h, rinsed and dried until the surface hydroxyl content is 1.5-2.5 mmol / g.

3. The method for preparing a three-dimensional ordered structure film electrode according to claim 1, characterized in that, In step S3, the catalyst is a 20-40 wt% loaded PtNi alloy / C catalyst, which is prepared by dissolving H2PtCl6·6H2O and Ni(NO3)2·6H2O in ethylene glycol at a molar ratio of (1-2):1, adding a carbon support, refluxing at 120-150℃ for 4-6 h under nitrogen protection, centrifuging, washing and drying to obtain the catalyst. The anion exchange resin is an imidazole resin with alkyne and azide groups, and the mass ratio of catalyst, resin, mixed solvent and dispersant is (60-85):(10-30):(100-150):(1-5).

4. The method for preparing a three-dimensional ordered membrane electrode according to claim 1, characterized in that, In step S5, the silane coupling agent solution is a 0.1-0.3 mol / L 3-glycidyl etheroxypropyltrimethoxysilane ethanol solution, and the treatment conditions are constant temperature stirring at 40-50℃ for 4-6 h; the siloxane grafting rate of the modified anion exchange membrane is controlled at 5-10 wt%.

5. The method for preparing a three-dimensional ordered membrane electrode according to claim 1, characterized in that, In step S6, the alkaline solution is a 1.0-1.5 mol / L potassium hydroxide solution, the constant temperature oscillation temperature is 30-40℃, the oscillation rate is 150-200 r / min, and the soaking time is 10-14 h; the nitrogen-protected drying conditions are 50-60℃ for 6-8 h.

6. The method for preparing a three-dimensional ordered membrane electrode according to claim 1, characterized in that, The step-by-step pressurization in step S7 is as follows: first, pre-pressurize at 0.6-0.8 MPa for 30-60 s, then heat to 50-60℃, pressurize to 1.2-1.4 MPa and hold for 120-180 s; the crosslinking environment is a closed reactor that has been purged with nitrogen 3-5 times, the crosslinking temperature is 75-85℃, the pressure is 0.1-0.2 MPa, the holding time is 12-18 h, the heating rate is 2-3℃ / min, and the cooling rate is 1-2℃ / min.

7. The method for preparing a three-dimensional ordered structure film electrode according to claim 1, characterized in that, In step S8, the acid solution is a 10-15% hydrofluoric acid solution, which is soaked at 25-35℃ for 2-3 hours to remove the silica template; the organic solvent is a 5-8% tetrahydrofuran solution, which is soaked at 40-50℃ for 1-2 hours to remove the polystyrene template; the total pore volume of the membrane electrode is controlled at 0.8-1.2 cm³ / g, with mesopores (2-50 nm) accounting for 10-20% and macropores (50-500 nm) accounting for 80-90%.

8. The method for preparing a three-dimensional ordered structure film electrode according to claim 3, characterized in that, In step S3, the mixed solvent is isopropanol and N,N-dimethylformamide mixed at a volume ratio of (3-5):1, and the dispersant is polyethylene glycol 400; the viscosity of the catalyst slurry is controlled at 200-500 mPa·s and tested by a rotational viscometer at 25℃ and 60 r / min.

9. The method for preparing a three-dimensional ordered membrane electrode according to claim 1, characterized in that, In step S4, the inkjet printing parameters are as follows: printhead movement speed 5-10 mm / s, inkjet frequency 200-300 Hz, droplet volume 10-20 pL; coating in 3-5 layers, each layer thickness 5-10 μm, drying conditions are 50-60℃ vacuum drying for 1-2 h; catalyst layer surface pore size 80-120 nm, bottom layer pore size 200-300 nm, porosity 35-55%.

10. The method for preparing a three-dimensional ordered structure film electrode according to claim 1, characterized in that, In step S8, the concentration of perfluorosulfonic acid solution is 0.05-0.1 mol / L, and the treatment conditions are soaking at 25-30℃ for 3-5 hours; the sulfonic acid group loading on the membrane electrode surface is 0.5-1.0 mmol / g.

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