Coated catalyst composite pem electrolyser gas diffusion layer and method of making

Abstract

This invention discloses a coated catalyst composite PEM electrolyzer gas diffusion layer and its preparation method, belonging to the field of water electrolysis for hydrogen production technology. The gas diffusion layer sequentially comprises a metal fiber felt, a coarse powder layer, a fine powder layer, a catalyst layer, and a catalyst porous layer. The preparation method includes: mixing metal spherical powder with resin adhesive to form metal spherical powder of different diameters on the surface of the metal fiber felt to obtain a coarse powder layer and a fine powder layer; uniformly spraying a composite catalyst onto the surface of the fine powder layer; and then placing both layers in a vacuum heat treatment furnace for high-temperature sintering to obtain the coated catalyst composite PEM electrolyzer gas diffusion layer. This invention transfers the catalyst from the proton exchange membrane to the gas diffusion layer, improving the catalyst utilization rate during repeated disassembly and reassembly. The powder layer achieves metallurgical bonding between the catalyst and the gas diffusion layer through high-temperature sintering. After high-temperature sintering, the composite catalyst forms gas overflow channels, improving reaction efficiency and enhancing the performance of the PEM electrolyzer.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis for hydrogen production technology, specifically relating to a coated catalyst composite PEM electrolyzer gas diffusion layer and its preparation method. Background Technology

[0002] In recent years, hydrogen energy has been increasingly mentioned as a clean energy source. Electrolyzers, as a crucial step in hydrogen production, are widely considered an important source of green hydrogen. PEM electrolyzers, with their advantages of high efficiency, compactness, fast response, and adaptability to fluctuating power supplies, are widely used in hydrogen production scenarios from renewable energy sources such as wind and solar power. Traditional PEM electrolyzers mainly consist of three components: electrodes, membrane electrode assemblies (MEAs), and a gas diffusion layer. The MEA primarily serves as the catalyst carrier. Because the proton exchange membrane in the MEA is relatively flexible, it may experience punctures, wrinkles, or damage during use due to the influence of metal components in the stack. Replacement requires replacing the entire MEA. Since the catalyst on the MEA is mostly composed of precious or rare metal oxides, maintenance costs are relatively high.

[0003] Traditional PEM electrolyzers typically use carbon paper, carbon cloth, or titanium mesh as the gas diffusion layer. Carbon-based materials are prone to corrosion and peeling under acidic and high-potential conditions, leading to catalyst layer detachment and increased ohmic impedance. While titanium mesh diffusion layers are corrosion-resistant, their surface roughness is uncontrollable and their pore distribution is uneven, making it difficult to form a stable capillary water transport structure and prone to localized flooding or gas stagnation. Currently, membrane electrode catalytic layers are often loaded onto the proton exchange membrane surface using methods such as spraying, transfer printing, or coating. During stack disassembly and assembly, the membrane is easily torn, and the catalyst cannot be recovered when the membrane is discarded, resulting in a precious metal loss rate as high as 30%–60%, significantly increasing maintenance costs. Furthermore, traditional catalytic layers lack directional gas channels, causing the generated O2 / H2 to easily accumulate at the interface, forming a high-concentration overpotential region, reducing electrolysis efficiency and stability. In addition, conventional gas diffusion layers and catalytic layers are only physically bonded, resulting in weak interfacial adhesion. Long-term operation easily leads to delamination and powder shedding, resulting in insufficient stack durability.

[0004] In summary, the existing technology has not disclosed a composite structure that integrates titanium fiber felt, gradient powder layer and pore-forming catalyst layer through vacuum metallurgical sintering, which cannot simultaneously meet the industrial requirements of corrosion resistance, high bonding strength, efficient mass transfer, low loss and easy maintenance. Summary of the Invention

[0005] To overcome the high maintenance costs of traditional PEM electrolyzers due to repeated catalyst disassembly and reassembly, the main objective of this invention is to provide a method for preparing a coated catalyst composite PEM electrolyzer gas diffusion layer. This method transfers the catalyst from the proton exchange membrane to the gas diffusion layer, improving catalyst utilization during repeated disassembly and reassembly. The powder layers of the catalyst composite gas diffusion layer are bonded together through high-temperature sintering, achieving a metallurgical bond between the catalyst and the gas diffusion layer, increasing bonding strength and extending service life. A nano-pore-forming agent is added to the catalyst during manufacturing; after high-temperature sintering, the pore-forming agent volatilizes, but the pores remain, forming gas overflow channels, improving reaction efficiency and enhancing electrolyzer performance. This invention aims to solve the following technical problems: 1) In traditional PEM electrolyzers, the catalyst is supported on the proton exchange membrane, which is easily damaged during disassembly and assembly, resulting in low catalyst utilization and high replacement costs; 2) The gas diffusion layer and the catalyst layer are physically bonded, but the bonding strength is low and they are prone to detachment during long-term operation; 3) The diffusion layer has a simple pore structure, insufficient capillary water transport and gas overflow capacity, and is prone to water flooding and gas blockage; 4) The catalyst layer has no controllable nanopores, resulting in high mass transfer impedance and poor electrolysis efficiency and voltage performance; 5) During high-temperature sintering, workpieces are prone to sticking together, resulting in low yield and difficulty in mass production.

[0006] Another object of the present invention is to provide a coated catalyst composite PEM electrolyzer gas diffusion layer, which is prepared by the above-described method for preparing a coated catalyst composite PEM electrolyzer gas diffusion layer.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a coated catalyst composite PEM electrolyzer gas diffusion layer, comprising, in sequence, a metal fiber felt, a coarse powder layer, a fine powder layer, a catalyst layer, and a catalyst pore layer; The metal fiber felt is made of titanium fiber and has a thickness of 0.1-0.4 mm. The thickness of the coarse powder layer is 0.1-0.15 mm; The thickness of the fine powder layer is 0.03-0.05 mm; The thickness of the catalyst layer is 5-20 μm.

[0008] Preferably, the metal fiber felt is a three-dimensional mesh titanium fiber felt with a porosity of 60%-85% and a fiber diameter of 8-25μm. It has high air permeability, high corrosion resistance and structural support, providing mechanical strength and fluid channels for the overall diffusion layer.

[0009] Preferably, the coarse powder layer uses spherical titanium powder with a diameter of 40-60μm and a sphericity of ≥95%. It has good fluidity, uniform coating, and forms micron-sized pores, serving as a primary water transport and buffer layer to reduce fluid resistance.

[0010] Preferably, the fine powder layer uses spherical titanium powder with a diameter of 20-30μm to fill the gaps between the coarse powder, forming a mesoporous transition layer with a smooth and dense surface, thus avoiding the catalytic slurry from seeping into the bottom layer and causing waste.

[0011] Preferably, the catalyst pore layer has a pore size of 20-30 nm, a porosity of 20%-40%, and uniform pore flow, which can significantly improve gas overflow efficiency.

[0012] A second aspect of the present invention provides a method for preparing the gas diffusion layer of the coated catalyst composite PEM electrolyzer, comprising the following steps: (1) By mixing metal spherical powder with resin, metal spherical powder of different diameters is formed on the surface of metal fiber felt to form coarse powder layer and fine powder layer respectively; (2) The composite catalyst is uniformly sprayed onto the surface of the fine powder layer by spraying. (3) Place the overall structure obtained in step (2) together in a vacuum heat treatment furnace for high-temperature sintering. The sintering temperature is 1000-1200℃ and the sintering time is 2-4 hours to obtain the coated catalyst composite PEM electrolytic cell gas diffusion layer.

[0013] Preferably, in step (1), metal spherical powder with a powder diameter of 40-60 μm is first mixed with resin adhesive, stirred and defoamed in a stirring defoamer, and then coated onto the surface of metal fiber felt and dried in an oven at 120°C for 5 minutes, wherein the proportion of metal spherical powder is 50%-70%, forming a coarse powder layer; then metal spherical powder with a powder diameter of 20-30 μm is mixed with resin adhesive, stirred and defoamed in a stirring defoamer, and then coated onto the surface of metal spherical powder and dried in an oven at 120°C for 5 minutes, wherein the proportion of metal spherical powder is 40%-60%, forming a fine powder layer.

[0014] Preferably, in step (2), the catalytic components of the composite catalyst are yttrium oxide and niobium oxide, isopropanol is used as the solvent, and nano-polyvinyl alcohol particles with a size of 20-30 nm are added as pore-forming agents.

[0015] As a better alternative, in step (2), the molar ratio of yttrium oxide to niobium oxide is 3:1, and the solvent is a mixture of isopropanol and deionized water with a mass ratio of 7:3, which adjusts the viscosity of the slurry and the atomization effect to suit the spraying process; the addition of nano-polyvinyl alcohol particles serves as a pore-forming agent, which is completely pyrolyzed and volatilized after high-temperature sintering, leaving uniform and interconnected nanopores, enabling rapid gas overflow and inhibiting the aggregation of interfacial bubbles.

[0016] Preferably, in step (3), the vacuum degree of the high-temperature sintering is ≤10. -2 Pa, heating rate of 5-10℃ / min, holding temperature of 1000-1200℃, holding time of 2-4 h, and then cooling to below -200℃ in the furnace to ensure that the resin glue is fully decomposed, the metal powder is metallurgically bonded, the catalytic layer crystal form is stable and the pore structure is intact.

[0017] Preferably, step (3) further includes using zirconia ceramic as a separator between different coated catalyst composite PEM electrolyzer gas diffusion layers, which can prevent the coated catalyst composite PEM electrolyzer gas diffusion layers from sticking together.

[0018] A third aspect of the present invention provides a PEM electrolyzer comprising the coated catalyst composite PEM electrolyzer gas diffusion layer.

[0019] Compared with existing technologies, this invention forms a composite gas diffusion layer using metal powder and fiber felt, supports the catalyst on the surface, and utilizes the capillary structure of the fiber felt and powder to guide the reaction water to the catalyst layer. Gas is generated in the catalyst layer and overflows through pores created by a pore-forming agent, thus improving reaction efficiency. The beneficial effects include at least the following: I. Based on the combination of powder layer and metal fiber felt, this invention prepares a catalyst layer containing pore-forming agent on the surface of the powder layer, and puts them together into a vacuum heat treatment furnace for high-temperature sintering to achieve metallurgy of fiber and metal powder, metal powder and catalyst. This improves the service life of the catalyst and enhances gas transport efficiency through nanopores on the catalyst.

[0020] Second, the present invention prepares a coarse powder layer and a fine powder layer on the surface of the fiber felt, which can refine the pores through the gaps between the powders, generate capillary action to facilitate the upward movement of reaction water, and form nanoscale pores on the fine powder layer to prevent the catalyst from leaking into the pores and affecting the catalytic efficiency.

[0021] Third, the catalyst contains a pore-forming agent. After volatilization at high temperature, the pores formed are approximately 20-30 nm in size and are uniformly formed on the surface of the composite gas diffusion layer. They come into contact with the proton exchange membrane to improve reaction efficiency. The nanopores on the catalyst facilitate the overflow of generated gas, reduce local gas accumulation, and improve catalytic efficiency.

[0022] Fourth, this invention places the catalyst on the surface of the gas diffusion layer, reducing the cost of replacing the catalyst along with the proton exchange membrane due to damage, and lowering maintenance costs.

[0023] Fifth, this invention uses sintering to achieve metallurgical bonding between metal fibers and metal powder, between metal powders, and between metal powders and catalysts, resulting in high bonding strength.

[0024] In summary, this invention, based on the combination of a powder layer and a metal fiber felt, prepares a catalyst layer containing a pore-forming agent on the surface of the powder layer. These layers are then placed together in a vacuum heat treatment furnace for high-temperature sintering to achieve metallurgical integration of the fiber and metal powder, and the metal powder and catalyst. This improves the catalyst's lifespan while enhancing gas transport efficiency through nanopores on the catalyst. Secondly, coarse and fine powder layers are prepared on the surface of the fiber felt. This refines the pores through the gaps between the powder particles, creating capillary action that facilitates the upward movement of reacting water. Furthermore, nanoscale pores are formed in the fine powder layer, preventing catalyst leakage into the voids and affecting catalytic efficiency. Thirdly, the catalyst contains a pore-forming agent. After high-temperature volatilization, the resulting pores are uniformly formed on the surface of the composite gas diffusion layer, contacting the proton exchange membrane and improving reaction efficiency. The nanopores facilitate the overflow of generated gas, reducing local gas accumulation and further enhancing catalytic efficiency. Fourthly, placing the catalyst on the surface of the gas diffusion layer reduces the cost of replacing the catalyst along with the proton exchange membrane due to damage, thus lowering maintenance costs. Finally, sintering is used to achieve metallurgical bonding between metal fibers and metal powder, between metal powders, and between metal powders and catalysts, resulting in high bonding strength. Attached Figure Description

[0025] Figure 1 The diagram below shows the gas diffusion layer structure of the coated catalyst composite PEM electrolyzer in the embodiment; 1. Metal fiber felt; 2. Coarse powder layer; 3. Fine powder layer; 4. Catalyst layer; 5. Catalyst pore layer.

[0026] Figure 2 The results show the test results of the stacking current and voltage performance of the electrolyzer prepared with different catalysts.

[0027] Figure 3 The results show the performance test results of the gas diffusion layer of the coated catalyst composite PEM electrolyzer in the examples. Detailed Implementation

[0028] To more fully understand and demonstrate the technical solutions, objectives, and advantages of the present invention, the technical effects produced by the present invention will be further described in detail and completely below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. It should be noted that other embodiments obtained by those skilled in the art without departing from the concept of the present invention are all within the protection scope of the present invention.

[0029] The gas diffusion layer structure of the coated catalyst composite PEM electrolyzer is as follows: Figure 1 As shown, preparing coarse and fine powder layers on the surface of the fiber felt not only refines the pores through the gaps between the powders, generating capillary action that facilitates the upward movement of reacting water, but also forms nanoscale pores on the fine powder layer, preventing catalyst leakage into the pores and affecting catalytic efficiency. The catalyst contains a pore-forming agent; after high-temperature volatilization, the resulting pores are uniformly sized and formed on the surface of the composite gas diffusion layer, contacting the proton exchange membrane to improve reaction efficiency. The nanopores on this layer facilitate the escape of generated gas, reducing the probability of local gas accumulation and further improving catalytic efficiency.

[0030] Example 1 Using a 0.25 mm thick fiber felt as a substrate, firstly, granular powder with a diameter of 40-60 μm is mixed with resin adhesive, stirred and defoamed in a stirrer, and then coated onto the surface of the metal fiber felt. It is then dried in a 120℃ oven for 5 minutes, with the metal spherical powder comprising 70%, forming a coarse powder layer. Next, granular metal powder with a diameter of 20-30 μm is mixed with resin adhesive, stirred and defoamed in a stirrer, and then coated onto the surface of the granular metal powder. It is then dried in a 120℃ oven for 5 minutes, with the metal spherical powder comprising 60%, forming a fine powder layer. Finally, the catalytic components of the composite catalyst are yttrium oxide and niobium oxide, and isopropanol is used as a solvent. Granular powder with a diameter of 20-30 μm is added... Nano-sized polyvinyl alcohol particles (nm) were used as pore-forming agents, accounting for 10% of the total volume. Zirconia ceramic sheets were used as spacers to separate the prepared diffusion layers. These layers were then stacked and vacuum sintered at 1100℃ for 3 hours. After cooling, a coated catalyst composite PEM electrolyzer gas diffusion layer was obtained. Performance test results were obtained under the following conditions: temperature 75℃, flow rate 50 stoichiometric ratio @ 2 electrical density (< 2 electrical density), and gas pressure 2 MPa. Figure 3 As shown.

[0031] like Figure 2 As shown, the coated catalyst composite PEM electrolyzer gas diffusion layer in Example 1 and the conventional method (the membrane electrode provided by Masuzu Co., Ltd., named PEM electrolysis water CCM, batch number PD20250926003) were used. A comparison of the current and voltage performance of the membrane electrode assembly under the conditions of 70℃, flow rate of 50m³ @ 2m³ (< 2m³) and 50m³ @ Xm³ (≥ 2m³), and gas pressure of 3MPa shows that the lower resistance between the catalyst and the gas diffusion layer due to the solid-phase connection method results in a lower voltage only under different test currents, indicating better electrolyzer performance.

[0032] Example 2 Using a 0.1 mm thick fiber felt as a substrate, firstly, granular powder with a diameter of 40-60 μm is mixed with resin adhesive, stirred and defoamed in a stirrer, and then coated onto the surface of the metal fiber felt. It is then dried in a 120℃ oven for 5 minutes, with the metal spherical powder comprising 50%, forming a coarse powder layer. Next, granular metal powder with a diameter of 20-30 μm is mixed with resin adhesive, stirred and defoamed in a stirrer, and then coated onto the surface of the granular metal powder. It is then dried in a 120℃ oven for 5 minutes, with the metal spherical powder comprising 40%, forming a fine powder layer. Finally, the catalytic components of the composite catalyst, yttrium oxide and niobium oxide, are added using isopropanol as a solvent, along with granular powder with a diameter of 20-30 μm. Nano-sized polyvinyl alcohol particles (nm) were used as pore-forming agents, with the pore-forming agent accounting for 5%. Zirconia ceramic sheets were used as spacers to separate the prepared diffusion layers. These layers were then stacked one by one and vacuum sintered at 1100℃ for 3 hours. After cooling, a coated catalyst composite PEM electrolyzer gas diffusion layer was obtained. Performance test results were obtained under the following conditions: temperature 75℃, flow rate 50 stoichiometric ratio @ 2 electrical density (< 2 electrical density), and gas pressure 2 MPa. Figure 3 As shown.

[0033] Example 3 Using a 0.4mm thick fiber felt as a substrate, firstly, granular powder with a diameter of 40-60 μm is mixed with resin adhesive, stirred and defoamed in a stirrer, and then coated onto the surface of the metal fiber felt. It is then dried in a 120℃ oven for 5 minutes, with the metal spherical powder comprising 60%, forming a coarse powder layer. Next, granular metal powder with a diameter of 20-30 μm is mixed with resin adhesive, stirred and defoamed in a stirrer, and then coated onto the surface of the granular metal powder. It is then dried in a 120℃ oven for 5 minutes, with the metal spherical powder comprising 50%, forming a fine powder layer. Finally, the catalytic components of the composite catalyst, yttrium oxide and niobium oxide, are added using isopropanol as a solvent, along with granular powder with a diameter of 20-30 μm. Nano-sized polyvinyl alcohol particles (nm) were used as pore-forming agents, with the pore-forming agent accounting for 15%. Zirconia ceramic sheets were used as spacers to separate the prepared diffusion layers. These layers were then stacked one by one and vacuum sintered at 1100℃ for 3 hours. After cooling, a coated catalyst composite PEM electrolyzer gas diffusion layer was obtained. Performance test results were obtained under the following conditions: temperature 75℃, flow rate 50 stoichiometric ratio @ 2 electrical density (< 2 electrical density), and gas pressure 2 MPa. Figure 3 As shown.

[0034] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A coated catalyst composite PEM electrolyzer gas diffusion layer, characterized in that, It consists of, in sequence, a metal fiber felt, a coarse powder layer, a fine powder layer, a catalyst layer, and a catalyst pore layer; The metal fiber felt is made of titanium fiber and has a thickness of 0.1-0.4 mm; The thickness of the coarse powder layer is 0.1-0.15 mm; The thickness of the fine powder layer is 0.03-0.05 mm; The thickness of the catalyst layer is 5-20 μm.

2. The coated catalyst composite PEM electrolyzer gas diffusion layer according to claim 1, characterized in that, The metal fiber felt is a three-dimensional mesh titanium fiber felt with a porosity of 60%-85% and a fiber diameter of 8-25μm; And / or the coarse powder layer uses spherical titanium powder with a diameter of 40-60 μm and a sphericity ≥95%; And / or the fine powder layer uses spherical titanium powder with a diameter of 20-30 μm; And / or the pore size of the catalyst pore layer is 20-30 nm, and the porosity is 20%-40%.

3. The method for preparing the gas diffusion layer of the coated catalyst composite PEM electrolyzer according to claim 1 or 2, characterized in that, Includes the following steps: (1) By mixing metal spherical powder with resin, metal spherical powder of different diameters is formed on the surface of metal fiber felt, forming a coarse powder layer and a fine powder layer in sequence; (2) The composite catalyst is uniformly sprayed onto the surface of the fine powder layer by spraying. (3) Place the overall structure obtained in step (2) together in a vacuum heat treatment furnace for high-temperature sintering. The sintering temperature is 1000-1200℃ and the sintering time is 2-4 hours to obtain the coated catalyst composite PEM electrolytic cell gas diffusion layer.

4. The method for preparing the gas diffusion layer of the coated catalyst composite PEM electrolyzer according to claim 3, characterized in that, In step (1), metal spherical powder with a diameter of 40-60 μm is mixed with resin glue, stirred and defoamed in a stirrer, and then coated onto the surface of metal fiber felt. It is then placed in an oven at 120°C and dried for 5 minutes. The metal spherical powder accounts for 50%-70% of the total powder, forming a coarse powder layer.

5. The method for preparing the gas diffusion layer of the coated catalyst composite PEM electrolyzer according to claim 3, characterized in that, In step (1), metal spherical powder with a diameter of 20-30 μm is mixed with resin glue, stirred and defoamed in a stirrer, and then coated onto the surface of the coarse powder layer. The mixture is then placed in a 120°C oven and dried for 5 minutes. The metal spherical powder accounts for 40%-60% of the total powder, forming a fine powder layer.

6. The method for preparing the gas diffusion layer of the coated catalyst composite PEM electrolyzer according to claim 3, characterized in that, In step (2), the catalytic components of the composite catalyst are yttrium oxide and niobium oxide, isopropanol is used as a solvent, and nano-polyvinyl alcohol particles with a size of 20-30 nm are added as pore-forming agents.

7. The method for preparing the gas diffusion layer of the coated catalyst composite PEM electrolyzer according to claim 6, characterized in that, In step (2), the molar ratio of yttrium oxide to niobium oxide is 3:1; the solvent is a mixture of isopropanol and deionized water with a mass ratio of 7:

3.

8. The method for preparing the gas diffusion layer of the coated catalyst composite PEM electrolyzer according to claim 3, characterized in that, Step (3) also includes using zirconia ceramic as a separator between the gas diffusion layers of different coated catalyst composite PEM electrolyzers.

9. A PEM electrolyzer comprising the coated catalyst composite PEM electrolyzer gas diffusion layer as described in claim 1 or 2.

Images