A porous metal plate having a multi-peak hole structure and a method of manufacturing the same

Abstract

The application belongs to the field of catalytic device manufacturing and relates to a porous metal plate with a multi-peak pore structure, a porosity of 20% to 80%, a pore size distribution curve obtained by a mercury injection method having at least two peaks, a first peak P1 and a second peak P2 in the range of 1 mu m to 120 mu m, a valley bottom between the first peak P1 and the second peak P2, a pore size corresponding to the position of the valley bottom being X mu m, X being between 15 and 40, the first peak P1 being in the range of 1 mu m to X mu m, the second peak P2 being in the range of greater than X mu m and less than or equal to 120 mu m, the first peak P1 corresponding to small pores, the second peak P2 corresponding to large pores, a small pore pore size being 1 mu m to X mu m, a large pore pore size being greater than X mu m and less than or equal to 120 mu m, and a small pore to large pore volume ratio being 1:1.5 to 1:7. The porous metal plate has a multi-peak pore structure distribution, is suitable for hydrogen production by electrolysis of water, can realize efficient transmission of reactants, improve a contact area of the porous metal plate and a catalytic layer, reduce a contact resistance, and improve a utilization rate of a catalyst.

Description

Technical Field

[0001] This application relates to the field of catalytic device manufacturing, specifically to a porous metal plate with a multi-peak pore structure and its preparation method. Background Technology

[0002] Porous metallic sintered bodies obtained by sintering titanium-based, nickel-based, and stainless steel powders have long been used as filters. However, in recent years, they have also attracted much attention for applications such as substrates for electrode plates in nickel-metal hydride and lithium-ion batteries, biomaterials, catalyst substrates, fuel cells, and components for hydrogen production stacks. Among these, the porous transport layer is one of the key components in water electrolysis technology, playing roles in conductivity, gas-liquid transport, and support within the water electrolysis cell. Currently, it mainly includes two types: metal fiber felt and powder porous sintered bodies. The pore structure often exhibits a single peak dominated by a certain size. In the electrolyzer, gas and liquid transport in reverse through the transport layer. Within the pores, gas and liquid compete and influence each other, thus affecting impedance and transport efficiency.

[0003] Patent document CN105435305B discloses a porous titanium composite material and its preparation method, which is mainly used to solve the problems of long-term antibacterial effect and promotion of bone cell and tissue growth. The method forms micropores on the walls of macropores by adding a pore-forming agent and anodizing reaction. However, when it is used in an electrolytic cell, the surface oxide layer affects the conductivity and electrolytic performance.

[0004] Patent application CN1531470A discloses a method for manufacturing sintered titanium powder. The method involves sintering spherical powder particles of titanium or titanium alloy based on gas atomization to produce a sintered body with a porosity of 35% to 55%. If used in an electrolytic cell, the pore structure is unimodal.

[0005] Patent application CN1846835A discloses a method for manufacturing sintered titanium powder bodies. This method involves pressureless sintering of raw materials through sieving, achieving a gradual increase in pore size from one surface to another. However, when used in an electrolytic cell, this increases the thickness of the sintered body without improving its performance.

[0006] Patent document CN100457333C discloses a method for preparing a porous thin titanium plate. The method involves placing titanium powder in a mold box for vacuum sintering to obtain a sample with a porosity of 45% to 60% and a thickness of 0.2 to 0.8 mm. The sample is then used in an electrolytic cell, and the pore structure is relatively simple.

[0007] Patent application CN109897984A discloses a method for preparing titanium-based porous metal materials. The method involves the interconnected channels left at the contact points after the burn-off of polystyrene foam microspheres. Water vapor and hydrogen chloride gas are generated through the decomposition of calcium chloride dihydrate, and the volatilization of calcium chloride causes the product to expand and crack, forming a loose, porous structure. However, when used in an electrolytic cell, this method easily generates impurity ions, affecting the electrolytic cell's lifespan.

[0008] There are other methods for preparing gradient-pore porous materials, but these are often discontinuous and gradual, which still increases mass transfer resistance. Other methods enhance gas-liquid transport capabilities through hydrophilic / hydrophobic modification; however, the durability of hydrophilic / hydrophobic properties is prone to problems.

[0009] While some existing patents have achieved different pore size distributions, they suffer from problems such as pore size not being suitable for the electrolytic cell, disordered pore size distribution, and residual impurity ions in the transport layer affecting the electrolytic cell's lifespan. Summary of the Invention

[0010] To at least partially achieve the above-mentioned objectives, this application provides the following technical solutions:

[0011] This application provides a porous metal plate with a multi-peak pore structure. The porosity of the porous metal plate is 20% to 80%. The pore size distribution curve obtained by mercury intrusion porosimetry has at least two peaks in the range of 1 μm to 120 μm. The two peaks include a first peak P1 and a second peak P2. There is a valley between the first peak P1 and the second peak P2. The pore size corresponding to the valley is X μm, where X is between 15 and 40. The first peak P1 exists in the range of 1 μm to X μm, and the second peak P2 exists in the range of greater than X μm and less than or equal to 120 μm. The first peak P1 corresponds to a small pore, and the second peak P2 corresponds to a large pore. The pore size of the small pore is 1 μm to X μm, and the pore size of the large pore is greater than X μm and less than or equal to 120 μm. The volume ratio of the small pore to the large pore is 1:1.5 to 1:7.

[0012] Preferably, the small holes and the large holes are arranged alternately.

[0013] Preferably, the volume ratio of the small hole to the large hole is 1:1.5-1:6, and the volume ratio can also be specifically 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.5, 1:2.7, 1:3.0, 1:3.2, 1:3.5, 1:4.0, 1:4.5, 1:5.0, 1:5.5, etc.

[0014] Preferably, the intrinsic contact resistance of the porous metal plate is 0.5–1.2 mΩ·cm. 2@2MPa, the intrinsic contact resistance can specifically be 0.6mΩ·cm. 2 @2MPa, 0.7mΩ·cm 2 @2MPa, 0.8mΩ·cm 2 @2MPa, 0.9mΩ·cm 2 @2MPa, 1.0mΩ·cm 2 @2MPa, 1.1mΩ·cm 2 @2MPa, etc.

[0015] Preferably, the porosity of the porous metal plate is 25% to 75%.

[0016] Preferably, the thickness of the porous metal plate is 0.01-10 mm, more preferably 0.05-5 mm, and can also be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 2 mm, 3 mm, 4 mm, etc.

[0017] Preferably, the porous metal plate is made of titanium, nickel, titanium alloy, nickel alloy, or stainless steel.

[0018] Preferably, the titanium alloy is Ti-6Al-4V, Ti-5Al-2.5Sn, Ti-6Al-7Nb, Ti-3Al-2.5V, Ti-2Al-2.5Zr, Ti-8Mn, Ti-6Al-6V-2Sn, Ti-6Al-2Sn-4Zr-6Mo, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-2Sn-2Zr-2Mo, Ti-3Al- The nickel alloys are 5Mo-4.5V, Ti-6Al-2Sn-4Zr-2Mo, Ti-5Mo-5V-8Cr-3Al, Ti-13V-11Cr-3Al, Ti-2.25Al-11Sn-5Zr-1Mo-0.2Si, Ti-6Al-2Zr-1Mo-1V, Ti-15V-3Cr-3Sn-3Al, or Ti-8Al-1Mo-1V; the nickel alloys are Inconel 600, Inconel 601, Inconel 625, Inconel 690, Inconel 718, Inconel 800, Inconel 825, Inconel 901, Hastelloy B, Hastelloy C, Hastelloy X, Hastelloy R, or Hastelloy G.

[0019] This application also provides a method for preparing a porous metal plate, comprising:

[0020] Metal fine powder with a particle size of D10 in the range of 3μm-60μm and a difference between D10 and D90 within 10μm is mixed with an appropriate amount of binder and granulated, and then passed through a 60μm-150μm sieve to obtain powder A.

[0021] Powder A, coarse metal powder with a particle size D10 of 60μm-200μm and a difference between D10 and D90 within 10μm, and an appropriate amount of binder are mixed and granulated, and then passed through a 180μm-300μm sieve to obtain powder B.

[0022] The powder B is formed into a metal plate blank, and then the binder is removed and sintered to obtain the porous metal plate.

[0023] Preferably, the binder is one or more of the following: polyvinyl alcohol, ethanol, stearic acid, zinc stearate, pentaerythritol stearate, ethylene bis-stearamide, paraffin wax, microcrystalline wax, carnauba wax, Fischer-Tropsch wax, polyethylene wax, polyoxymethylene, ethylene-vinyl acetate copolymer, polypropylene, or polyethylene solution.

[0024] Based on the above technical solution, it can be seen that the porous metal plate and its preparation method of this application have at least one of the following beneficial effects compared with the prior art:

[0025] (1) The porous metal plate of this application has a multi-peak pore structure with a distribution of large and small pores, which is used as the transport layer of the electrolytic hydrogen production device, especially the anode transport layer. The small pores are conducive to the transport of water, and the large pores are conducive to the transport of gas. The ratio of large and small pores can realize the efficient transport of reactants and the generated gas can be quickly discharged. At the same time, the transport layer is located between the anode side plate and the membrane electrode, and is in contact with both the plate and the anode catalyst of the membrane electrode. The multi-peak structure porous metal plate constructed by this method can increase the contact area, thereby reducing the contact resistance and improving the utilization rate of the catalyst.

[0026] (2) Compared with other preparation processes such as adding pore-forming agents or chemical modification, this application uses fewer types of raw materials and has a simple preparation method. During the preparation process, no impurity elements that affect the life and service stability of the electrolytic cell will be introduced. Attached Figure Description

[0027] The following description, in conjunction with the accompanying drawings and tables, further illustrates this application:

[0028] Figure 1 This is a schematic diagram of an electrolytic reactor device;

[0029] Figure 2a , 2b This is a photograph of the microstructure of the porous metal plate prepared in Example 1.

[0030] Figure 2c , 2d A microscopic image of a commercial titanium felt.

[0031] Figure 3 The aperture distribution curve corresponding to the aperture size in Example 1;

[0032] Figure 4 The cumulative mercury ingress volume distribution curve is for the corresponding aperture in Example 1;

[0033] Figure 5 The aperture distribution curve corresponding to the aperture size in Example 2;

[0034] Figure 6 The cumulative mercury ingress volume distribution curve is for the corresponding aperture in Example 2;

[0035] Figure 7 The aperture distribution curve corresponding to the aperture size in Example 3;

[0036] Figure 8 The cumulative mercury ingress volume distribution curve is for the corresponding aperture in Example 3;

[0037] Figure 9 The aperture distribution curve corresponding to the aperture size in Example 4;

[0038] Figure 10 The cumulative mercury ingress volume distribution curve is shown for the corresponding aperture in Example 4;

[0039] Figure 11 The pore size distribution curves for commercial titanium felt with corresponding pore sizes;

[0040] Figure 12 The cumulative mercury ingress volume distribution curve for the corresponding pore size of commercial titanium felt;

[0041] Figure 13 This is a comparison of the single-cell test performance of Examples 1-4 with that of commercial titanium felt; Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments.

[0043] To address the shortcomings of existing technologies, this application proposes a porous metal plate with a multi-peak pore structure. The peaks of the multi-peak pores refer to the peaks on the pore size distribution curve obtained using mercury intrusion porosimetry (MIP). In existing technologies, single-peak pores, for example, refer to pore size distribution ranges with intervals within 10 μm, and the pore size distribution curve obtained by MIP has only one peak in the 1 μm-120 μm range. The porous metal plate provided in this application has a porosity of 20%–80%, and the pore size distribution curve obtained by MIP has at least two peaks in the 1 μm-120 μm range, namely the first peak P1 and the second peak P2. There can be two peaks, or more than two peaks, such as three or four peaks. The first peak P1 corresponds to a small pore, and the second peak P2 corresponds to a large pore. The inventors have discovered that the simultaneous presence of small and large pores in the porous metal plate solves the aforementioned technical problems.

[0044] In a preferred embodiment, the pore size distribution curve is preferably 2.5μm-118.0μm in the range of 1μm-120μm, more preferably 2.9μm-115.0μm, and can also be 3.5μm-113.0μm, 4.8μm-112.0μm, or 5.8μm-101.0μm.

[0045] In this application, the mercury porosimetry method uses a mercury porosimeter to test the pore size distribution curve of a porous metal plate. The principle is based on the non-wetting property of mercury on most material surfaces; increasing pressure forces mercury into the internal pores of the material. The greater the external pressure, the smaller the radius of the pore that mercury can enter. By measuring the amount of mercury entering the pore under different external pressures, the pore volume corresponding to the pore size can be determined.

[0046] In this application, the dividing point between the volume values ​​of macropores and micropores is the valley between the first peak P1 and the second peak P2. The pore diameter value corresponding to the valley is X μm, where X is between 15 and 40 to ensure a suitable volume ratio between micropores and macropores.

[0047] In a preferred embodiment, X is preferably between 16 and 38, and may specifically be 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, etc.

[0048] In this application, the first peak P1 is in the range of 1μm-Xμm, which means that in the cumulative mercury volume distribution curve of the corresponding pore size, the pore size value corresponding to the first peak P1 is greater than or equal to 1μm and less than or equal to Xμm. The second peak P2 is in the range of greater than Xμm and less than or equal to 120μm, which means that in the cumulative mercury volume distribution curve of the corresponding pore size, the pore size corresponding to the second peak P2 is greater than Xμm and less than or equal to 120μm. The pore size of the micropore is 1μm-Xμm, and the pore size of the macropore is greater than Xμm and less than or equal to 120μm.

[0049] In a preferred embodiment, the large and small holes are arranged alternately. The alternate arrangement means that when observed with SEM, there are both large and small holes in the area, and the large and small holes are arranged adjacent to each other.

[0050] The porous metal plate provided in this application is prepared by a sintering process and is preferably used as a transport layer for hydrogen production through water electrolysis and as a transport layer for fuel cells.

[0051] The electrolysis device described in this application is a water electrolysis hydrogen production device, and its typical structure is a multi-layer component stack. The transport layer provided in this application is located between the anode side plate and the membrane electrode, and is in contact with both the plate and the anode catalyst of the membrane electrode.

[0052] like Figure 1 The diagram shows a schematic of a water electrolysis hydrogen production device using the transport layer prepared in this application and a commercially available titanium felt. In this application, the transport layer makes point contact with the anode, cathode plate, and membrane electrode, resulting in a large contact area and therefore low contact resistance. In contrast, the commercially available titanium felt makes line contact, resulting in a smaller contact area and therefore higher contact resistance.

[0053] In a preferred embodiment, the first peak P1 is distributed in the range of 2μm-28μm, preferably in the range of 3μm-26μm, more preferably in the range of 4μm-25μm, particularly preferably in the range of 5μm-23μm, and most preferably in the range of 6μm-20μm; the second peak P2 is preferably distributed in the range of 32μm-110μm, more preferably in the range of 35μm-100μm, particularly preferably in the range of 40μm-90μm, and most preferably in the range of 50μm-70μm, especially most preferably in the range of 55μm-65μm.

[0054] In a preferred embodiment, multiple peaks may be distributed in the 1-18 μm range, such as two peaks; a third peak may be distributed in the 1-10 μm range; and a fourth peak may be distributed in the 10-18 μm range. Multiple peaks may be distributed in the 30-90 μm range, such as two, three, four, five, or more peaks, for example, a fifth peak may be distributed in the 30-40 μm range; and a sixth peak may be distributed in the 80-90 μm range.

[0055] In a preferred embodiment, the overall porosity of the porous metal plate is preferably 30% to 70%, more preferably 40% to 60%, and can also be 45%, 50%, 55%, etc.

[0056] In a preferred embodiment, the porous metal plate is made of titanium, nickel, titanium alloy, nickel alloy, or stainless steel.

[0057] In a preferred embodiment, the titanium alloy is, for example, Ti-6Al-4V, Ti-5Al-2.5Sn, Ti-6Al-7Nb, Ti-3Al-2.5V, Ti-2Al-2.5Zr, Ti-8Mn, Ti-6Al-6V-2Sn, Ti-6Al-2Sn-4Zr-6Mo, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-2Sn-2Zr-2Mo, Ti-3Al-5Mo-4.5V, Ti-5Mo-5V-8Cr-3Al, Ti-13V-11Cr-3Al, Ti-2.25Al-11Sn-5Zr-1Mo-0.2Si, Ti-6Al-2Zr-1Mo-1V, Ti-15V-3Cr-3Sn-3Al, or Ti-8Al-1Mo-1V, etc.; the nickel alloy is, for example, Inconel. 600, Inconel 601, Inconel 625, Inconel 690, Inconel 718, Inconel 800, Inconel 825, Inconel 901, Hastelloy B, Hastelloy C, Hastelloy X, Hastelloy R or Hastelloy G, etc.

[0058] The method for preparing the porous metal plate in this application includes: mixing and granulating fine metal powder with a particle size D10 of 3μm-60μm and a difference between D10 and D90 within 10μm with an appropriate amount of binder, and passing the granules through a 60μm-150μm sieve to obtain powder A; mixing and granulating powder A, coarse metal powder with a particle size D10 of 60μm-200μm and a difference between D10 and D90 within 10μm with an appropriate amount of binder, and passing the granules through a 180μm-300μm sieve to obtain powder B; forming powder B into a metal plate blank, and then removing the binder and sintering to obtain the porous metal plate.

[0059] In a preferred embodiment, the particle size D10 of the fine metal powder is 5-50 μm, and can also be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, or 45 μm; the particle size D10 of the coarse metal powder is 70-190 μm, and can also be 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, or 180 μm, etc., and the difference between the particle size D10 and D90 of the above metal powders is within 10 μm, specifically 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or 9 μm.

[0060] In a preferred embodiment, the mass ratio of fine metal powder to coarse metal powder is 1:1 to 1:5, and can be specifically 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, etc.

[0061] In a preferred embodiment, the fine metal powder is titanium powder, titanium alloy powder, nickel powder, nickel alloy powder, or stainless steel powder, etc.; the coarse metal powder is titanium powder, titanium alloy powder, nickel powder, nickel alloy powder, or stainless steel powder, etc.

[0062] In a preferred embodiment, the binder is one or more of the following: polyvinyl alcohol, ethanol, stearic acid, zinc stearate, pentaerythritol stearate, ethylene bis-stearamide, paraffin wax, microcrystalline wax, carnauba wax, Fischer-Tropsch wax, polyethylene wax, polyoxymethylene, ethylene-vinyl acetate copolymer, polypropylene, or polyethylene solution.

[0063] In a preferred embodiment, the sieve used to obtain powder A has a mesh size of 70-120 μm, preferably 80-110 μm, 90-100 μm, etc. In a preferred embodiment, the sieve used to obtain powder B has a mesh size of 200-290 μm, and can also be 220-280 μm, 230-270 μm, 240-260 μm, etc.

[0064] In a preferred embodiment, granulation can be carried out by stirring in equipment such as a mortar, crucible, ribbon mixer, plow mixer, or spiral cone mixer; stirring can be carried out in a single direction or alternately in different directions, preferably in a single direction; spray granulation can also be used, and this application does not have any particular limitation on this.

[0065] In a preferred embodiment, when the powder B is formed into a metal plate blank, it can be done by scraping, dip coating, mold coating, bar coating, screen printing, offset printing, gravure printing, inkjet printing, spraying, dispensing, spin coating, casting, etc.

[0066] In a preferred embodiment, the debinding is performed in a sintering apparatus by heating at a rate of 0.1-50°C / min, preferably 0.5-30°C / min, more preferably 0.8-10°C / min, and most preferably 1-5°C / min, and holding at 350-700°C, preferably 400-600°C, for 0.5-3 hours, preferably 0.5-2 hours, and more preferably 1-1.5 hours.

[0067] In a preferred embodiment, the sintering process involves, after debinding, heating at a rate of 0.1-50°C / min, preferably 0.5-30°C / min, more preferably 0.8-10°C / min, and most preferably 1-5°C / min under an inert atmosphere or vacuum, and holding at 800-1200°C, preferably 850-1100°C, and most preferably 900-1000°C for 0.5-3 hours, preferably 0.5-2 hours, and more preferably 1-1.5 hours, followed by natural cooling. In a preferred embodiment, the sintering can be performed using pressureless sintering, hot pressing sintering, tape casting sintering, or rolling sintering, etc.

[0068] According to this application, after granulation and preforming using metal fine powder and metal coarse powder of different particle sizes, the sintering kinetics differ due to the size difference between the two powders during sintering. Larger particles form a porous framework with a small contact area between particles, resulting in a long atomic diffusion path in the early stages of sintering, making it difficult to form a continuous metallurgical bond. During sintering, only surface atomic diffusion forms localized necking, and the interparticle gaps cannot be completely closed, ultimately retaining large pores larger than 30 μm. Conversely, smaller particles fill the gaps between larger particles, resulting in a large contact area between particles, a short atomic diffusion distance, and rapid formation and expansion of sintering necks. Under the same temperature, the porous metal plate prepared in this application is more likely to achieve densification, forming dense regions and leaving isolated micropores, resulting in a reduction of interparticle porosity to below 30 μm. From a thermodynamic perspective, the system tends to reduce surface energy. Macropores, due to their large volume and high surface energy, preferentially shrink, but the weak bonding force between large-diameter particles hinders shrinkage, leading to macropore residue. Micropores, on the other hand, have low surface energy and high stability, making them less prone to closure. From a kinetic perspective, large-diameter particles require higher activation energy for sintering and have low diffusion rates at low temperatures, hindering effective densification. Small-diameter particles, however, have fast diffusion rates, rapidly forming micropore structures in the early stages of sintering. In summary, the meticulous design from raw material processing to the sintering preparation process results in a unique multi-peak pore structure characteristic in the porous metal plate prepared in this application when tested using mercury intrusion porosimetry.

[0069] The test data in this application were obtained using the following method:

[0070] The pore size distribution and porosity of the metal plate were determined using the mercury porosimetry method, in accordance with the specifications of GB / T21650.1-2008 "Determination of Porosity and Pore Size Distribution of Solid Materials by Mercury Porosimetry and Gas Adsorption Methods - Part 1: Mercury Porosimetry Test". A fully automated mercury porosimetry instrument was used. In this application, the mercury ingress starting point was selected as 101.0 μm (the first measurement point for mercury porosimetry instruments with a diameter below 120.0 μm; pores larger than 120.0 μm are due to errors from the sample edge), and the mercury ingress endpoint was selected as the maximum cumulative mercury ingress value (the first measurement point where the cumulative mercury ingress value begins to remain constant). The principle of mercury porosimetry for pore size distribution testing utilizes the non-wetting property of mercury on most material surfaces. Increasing the pressure forces mercury into the pores within the material; the greater the external pressure, the smaller the radius of the pore that mercury can enter. By measuring the amount of mercury entering the pore under different external pressures, the pore volume corresponding to the pore size can be determined. The dividing point between the volumes of large and small pores is the "valley" position between the two peaks.

[0071] Because the mercury injection rate is hydraulically controlled and the sensor accuracy is within 0.1% to 0.2% of full scale, the pore size corresponding to the test results is discontinuous. The measurable points in this application include 2.5μm, 2.9μm, 3.5μm, 4.8μm, 5.4μm, 5.6μm, 6.0μm, 6.6μm, 7.2μm, 8.1μm, 9.1μm, 10.1μm, 11.3μm, 12.5μm, 14.0μm, 15.5μm, 17.3μm, 19.1μm, 21.4μm, and 24.2μm. Data points such as 26.0μm, 27.9μm, 30.3μm, 36.4μm, 45.5μm, 52.0μm, 60.7μm, 72.8μm, 90.3μm, 101.0μm, and 120.7μm were obtained. After extensive experiments, it was confirmed that the porous metal plate prepared in this application has a first peak P1 in the range of 1-Xμm and a second peak P2 in the range of Xμm-120.0μm. The volume of pores smaller than 1μm can be ignored, and the pores larger than 120μm are errors caused by the edge of the test sample.

[0072] Powder particle size was tested using a laser particle size analyzer. The laser particle size analyzer determines the size and distribution of particles by analyzing the spatial distribution of scattered light based on the scattering and diffraction phenomena generated by the interaction between laser and particles. The core of the method is to measure the intensity of scattered light at different angles and perform mathematical inversion by combining Mie scattering theory or Fraunhofer diffraction theory to finally obtain particle size distribution data.

[0073] Contact resistance testing employed the four-probe method using a bipolar plate four-probe resistance meter; single-cell performance testing utilized a commercial PEM water electrolysis testing fixture with an active area of ​​25 cm². 2 The temperature was 60℃. During the test, only the porous metal plate and commercial titanium felt prepared in this application were replaced, while other accessories remained the same.

[0074] The following, in conjunction with specific embodiments, further illustrates the preparation method of the porous metal plate of this application. Those skilled in the art can refer to the content of this application and appropriately improve the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the scope of this application. The methods and applications of this application have been described through preferred embodiments. Those skilled in the art can obviously modify or appropriately change and combine the methods and applications described in this application without departing from the content, spirit, and scope of this application to realize and apply the technology of this application.

[0075] Example 1

[0076] (1) Prepare fine titanium powder with D10 of 30μm and D90 of 40μm and coarse titanium powder with D10 of 50μm and D90 of 60μm;

[0077] (2) Pour fine titanium powder into a mortar, then pour in an appropriate amount of 5% PVA aqueous solution, and gently stir in one direction with the mortar until the fine powder clumps together and forms granules. Pass it through a 90μm sieve to obtain powder A.

[0078] (3) Place powder A and coarse titanium powder in a mortar at a mass ratio of 1:4.5, then pour in an appropriate amount of 5% PVA aqueous solution, and gently stir in one direction with the mortar until the coarse powder and powder A are bonded together and form granules. Pass through a 210μm sieve to obtain powder B.

[0079] (4) Then pour an appropriate amount of powder B into the mold, scrape it flat with a scraper, and then put it into the furnace. Heat it at a rate of 3℃ / minute and keep it at 550℃ for 1 hour to remove the glue. Then continue to heat it at a rate of 3℃ / minute and keep it at 1000℃ for 2 hours. Then cool it down naturally to obtain a metal plate.

[0080] SEM observation results of the metal plate are as follows Figure 2a , Figure 2b As shown, it can be clearly seen that the large and small pores are arranged in a roughly alternating pattern, that is, the large and small pores are arranged adjacent to each other. After measuring the pore size using the mercury porosimetry method, the pore size distribution curves corresponding to the pore sizes are obtained as shown in the figure. Figure 3 As shown, the cumulative mercury ingress volume distribution curve for the corresponding aperture is obtained as follows. Figure 4 As shown.

[0081] from Figure 3 It can be seen that two peaks appear in the range of approximately 5.4 μm to 101.0 μm. The first peak, P1, is located at 24.2 μm; the second peak, P2, is located at 51.9 μm. The valley between the two peaks is located at 30.3 μm. Figure 4It can be seen that the cumulative mercury ingress volume corresponding to a pore size of 101.0 μm is 0.048 mL / g, the cumulative mercury ingress volume corresponding to a pore size of 30.3 μm is 0.281 mL / g, and the cumulative mercury ingress volume corresponding to a pore size of 5.4 μm is 0.438 mL / g. Therefore, according to... Figure 4 The test results show that the pores are distributed between 5.4 μm and 101.0 μm. Among them, the volume of the micropores between 5.4 and 30.3 μm is 0.157 mL / g, and the volume of the macropores between 30.3 and 101.0 μm is 0.233 mL / g. It can be concluded that the micropore volume accounts for 40% and the macropore volume accounts for 60%.

[0082] The contact resistance of the porous metal plate was tested and is listed in Table 1. The contact resistance of Example 1 was measured to be 1.1 mΩ·cm. 2 @2MPa, with good electrical conductivity.

[0083] Example 2

[0084] (1) Prepare fine titanium powder with D10 of 20μm and D90 of 30μm and coarse titanium powder with D10 of 80μm and D90 of 90μm;

[0085] (2) Pour fine titanium powder into a mortar, then pour in an appropriate amount of 5% PVA aqueous solution, and gently stir in one direction with the mortar until the fine powder clumps together and forms granules. Pass it through a 120μm diameter sieve to obtain powder A.

[0086] (3) Place powder A and coarse titanium powder in a mortar at a mass ratio of 1:3.5, then pour in an appropriate amount of 5% PVA aqueous solution, and gently stir in one direction with the mortar until the coarse powder and powder A are bonded together and form granules. Pass through a 280μm diameter sieve to obtain powder B.

[0087] (4) Then pour an appropriate amount of powder B into the mold, scrape it flat with a scraper, and then put it into the furnace. Heat it at a rate of 3℃ / minute and keep it at 550℃ for 1 hour to remove the glue. Then continue to heat it at a rate of 3℃ / minute and keep it at 1000℃ for 1 hour. Then cool it down naturally to obtain a metal plate.

[0088] The pore size of the metal plate prepared in Example 2 was tested using the mercury intrusion porosimetry method, and the pore size distribution curves corresponding to the pore sizes were obtained as follows: Figure 5 As shown, the cumulative mercury ingress volume distribution curve for the corresponding aperture is obtained as follows. Figure 6 As shown. From Figure 5 It can be seen that two peaks appear in the range of approximately 2.5 μm to 101.0 μm. The first peak, P1, is located at 6.0 μm, and the second peak, P2, is located at 45.4 μm. The valley between the two peaks is located at 19.1 μm. Figure 6It can be seen that the cumulative mercury ingress volume corresponding to a pore size of 101.0 μm is 0.022 mL / g, the cumulative mercury ingress volume corresponding to a pore size of 19.1 μm is 0.361 mL / g, and the cumulative mercury ingress volume corresponding to a pore size of 2.5 μm is 0.411 mL / g. Therefore, according to... Figure 6 The test results show that the pores are distributed between 2.5 μm and 101.0 μm. Among them, the volume of the micropores between 2.5 and 19.1 μm is 0.050 mL / g, and the volume of the macropores between 19.1 and 101.0 μm is 0.339 mL / g. The micropore volume accounts for 13% and the macropore volume accounts for 87%.

[0089] The contact resistance of the porous metal plate was tested and is listed in Table 1. The contact resistance of Example 2 was measured to be 0.8 mΩ·cm. 2 @2MPa, with good electrical conductivity.

[0090] Example 3

[0091] A method for preparing a porous metal plate with a multi-peak pore structure, the method comprising the following steps:

[0092] (1) Prepare fine titanium powder with D10 of 20μm and D90 of 30μm and coarse titanium powder with D10 of 80μm and D90 of 90μm;

[0093] (2) Pour fine titanium powder into a mortar, then pour in an appropriate amount of 5% PVA aqueous solution, and gently stir in one direction with the mortar until the fine powder clumps together and forms granules. Pass it through a 60μm diameter sieve to obtain powder A.

[0094] (3) Place powder A and coarse titanium powder in a mortar at a mass ratio of 1:4.5, then pour in an appropriate amount of 5% PVA aqueous solution, and gently stir in one direction with the mortar until the coarse powder and powder A are bonded together and form granules. Pass through a 200μm diameter sieve to obtain powder B.

[0095] (4) Then pour an appropriate amount of powder B into the mold, scrape it flat with a scraper, and then put it into the furnace. Heat it at a rate of 3℃ / minute and keep it at 550℃ for 1 hour to remove the glue. Then continue to heat it at a rate of 3℃ / minute and keep it at 1000℃ for 1 hour. Then cool it down naturally to obtain the final product.

[0096] The pore size of the metal plate prepared in Example 3 was tested using the mercury intrusion porosimetry method, and the pore size distribution curves corresponding to the pore sizes were obtained as follows: Figure 7 As shown, the cumulative mercury ingress volume distribution curve for the corresponding aperture is obtained as follows. Figure 8 As shown. From Figure 7It can be seen that two peaks appear in the range of approximately 3.9 μm to 101.0 μm. The first peak, P1, is located at 10.1 μm, and the second peak, P2, is located at 60.7 μm. The valley between the two peaks is located at 24.1 μm. Figure 8 It can be seen that the cumulative mercury ingress volume corresponding to a pore size of 101.0 μm is 0.022 mL / g, the cumulative mercury ingress volume corresponding to a pore size of 24.1 μm is 0.180 mL / g, and the cumulative mercury ingress volume corresponding to a pore size of 3.9 μm is 0.247 mL / g. Therefore, according to... Figure 8 The test results showed that the pore size ranged from 3.9 μm to 101.0 μm. Specifically, the volume of the micropores (3.9-24.1 μm) was 0.067 mL / g, and the volume of the macropores (24.1-101.0 μm) was 0.158 mL / g. This indicates that the micropore volume accounted for 30% and the macropore volume accounted for 70%. The contact resistance of the porous metal plate was tested and is listed in Table 1. The contact resistance of Example 3 was measured to be 0.6 mΩ·cm. 2 @2MPa, with good electrical conductivity.

[0097] Example 4

[0098] A method for preparing a porous metal plate with a multi-peak pore structure, the method comprising the following steps:

[0099] (1) Prepare fine titanium powder with D10 of 10μm and D90 of 20μm and coarse titanium powder with D10 of 80μm and D90 of 90μm;

[0100] (2) Pour fine titanium powder into a mortar, then pour in an appropriate amount of 5% PVA aqueous solution, and gently stir in one direction with the mortar to obtain a uniformly mixed slurry. Use spray granulation technology to obtain powder A.

[0101] (3) Mix powder A and coarse titanium powder at a mass ratio of 1:4.5 to obtain powder B;

[0102] (4) Then pour an appropriate amount of powder B into the mold, dry press it into shape, and then put it into the furnace. Heat it at a rate of 3℃ / minute and keep it at 550℃ for 1 hour to remove the glue. Then continue to heat it at a rate of 3℃ / minute and keep it at 1000℃ for 1 hour. Then cool it down naturally to obtain the final product.

[0103] The pore size of the metal plate prepared in Example 4 was tested using the mercury intrusion porosimetry method, and the pore size distribution curves corresponding to the pore sizes were obtained as follows: Figure 9 As shown, the cumulative mercury ingress volume distribution curve for the corresponding aperture is obtained as follows. Figure 10 As shown. From Figure 9It can be seen that two peaks appear in the range of approximately 2.9 μm to 101.0 μm. The first peak, P1, is located at 18.1 μm, and the second peak, P2, is located at 52.0 μm. The valley between the two peaks is located at 30.3 μm. From Figure 10 It can be seen that the cumulative mercury ingress volume corresponding to a pore size of 101.0 μm is 0.019 mL / g, the cumulative mercury ingress volume corresponding to a pore size of 30.3 μm is 0.169 mL / g, and the cumulative mercury ingress volume corresponding to a pore size of 3.8 μm is 0.250 mL / g. Therefore, according to... Figure 10 The test results showed that the pore size ranged from 3.8 μm to 101.0 μm. Specifically, the volume of the small pores (3.8-30.3 μm) was 0.081 mL / g, and the volume of the large pores (30.3-101.0 μm) was 0.150 mL / g. This indicates that the small pore volume accounted for 35% and the large pore volume accounted for 65%. The contact resistance of the porous metal plate was tested and is listed in Table 1. The contact resistance of Example 4 was measured to be 0.5 mΩ·cm. 2 @2MPa, with good electrical conductivity.

[0104] For comparison, the pore size of commercial titanium felt (Bekaert-2GDL10-0.25) was determined using mercury intrusion porosimetry. The microstructure is shown in the image below. Figure 2c and Figure 2d As shown, the pore size distribution curves corresponding to the pore size are obtained as follows: Figure 11 As shown, there is only one single peak, and the cumulative mercury volume distribution curve corresponding to the aperture size is as follows. Figure 12 As shown.

[0105] Contact resistance and single-cell performance were tested for Examples 1-4 and commercial titanium felt, respectively. The results are shown in Table 1 and 2. Figure 13 As shown, the contact resistance of the porous metal plate prepared in this application is superior to that of commercial titanium felt, and its single-cell test performance is also superior to that of commercial titanium felt, at 2A / cm. 2 Its performance at current densities is superior to that of commercial titanium felt by 4-11 mV.

[0106] Table 1. Test results of examples and commercial titanium felt

[0107]

[0108] When the porous metal plate provided in this application is used in a PEM water electrolysis device, the porous metal plate with a multi-peak pore structure can optimize the gas-liquid transport process during the reaction and improve the contact with the bipolar plate and membrane electrode, thereby improving the performance and stability of water electrolysis. Specifically: the gas experiences less flow resistance in the low-curvature large pores, allowing the gas to be quickly discharged from the anode, reducing bubble coverage on the electrode surface, avoiding blockage of reactive sites, reducing concentration polarization, and increasing the reaction rate. Therefore, the larger pore size promotes gas-liquid transport and gas-liquid separation, which is beneficial to the electrochemical reaction of water electrolysis. However, it reduces the contact area between the transport layer and the membrane electrode, thereby increasing the contact resistance and hindering the electrochemical reaction of PEM water electrolysis. The small pores generate high capillary pressure to actively "pump" liquid water to the catalyst layer-membrane interface, ensuring that the proton exchange membrane (PEM) is fully hydrated and maintaining high proton conductivity. At the same time, the small pore area forms a dense micro-bump structure, increasing the microscopic contact points between the PTL and the catalyst layer, thereby reducing the contact resistance.

[0109] The multi-peaked pore structure solves three major contradictions simultaneously through the spatial division of labor between large pores for gas conduction and small pores for liquid conduction, as well as the synergistic mechanism of small pores enhancing interfacial contact: the low-resistance gas exhaust from large pores and the capillary water supply from small pores can optimize the gas-liquid transport conflict; the large pores ensure gas channels and the small pores increase contact point density, which can optimize the interfacial resistance and mass transfer balance; and the synergistic maintenance of uniform water / heat distribution by multiple pore structures can improve the stability of the water electrolysis reaction.

[0110] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A porous metal plate with a multi-peak pore structure, characterized in that, The porous metal plate has a porosity of 20% to 80%. Its pore size distribution curve obtained by mercury intrusion porosimetry shows at least two peaks in the range of 1 μm to 120 μm. These two peaks include a first peak P1 and a second peak P2. A valley exists between the first peak P1 and the second peak P2, and the pore size corresponding to the valley is X μm, where X is between 15 and 40. The first peak P1 exists in the range of 1 μm to X μm, and the second peak P2 exists in the range greater than X μm and less than or equal to 120 μm. The first peak P1 corresponds to a small hole, and the second peak P2 corresponds to a large hole. The diameter of the small hole is 1μm-Xμm, and the diameter of the large hole is greater than Xμm and less than or equal to 120μm. The volume ratio of the small hole to the large hole is 1:1.5-1:

7. The large holes and the small holes are arranged alternately. The alternate arrangement means that when observed with SEM, both the large holes and the small holes are present in the entire area, and the large holes and the small holes are arranged adjacent to each other. The porous metal plate is made of titanium, nickel, titanium alloy, nickel alloy, or stainless steel.

2. The porous metal plate according to claim 1, characterized in that, The volume ratio of the small hole to the large hole is 1:1.5-1:

6.

3. The porous metal plate according to claim 2, characterized in that, The volume ratio of the small hole to the large hole is 1:2 to 1:

5.

4. The porous metal plate according to claim 3, characterized in that, The intrinsic contact resistance of the porous metal plate is 0.5–1.2 mΩ·cm. 2 @2MPa.

5. The porous metal plate according to claim 4, characterized in that, The porosity of the porous metal plate is 25% to 75%.

6. The porous metal plate according to claim 1, characterized in that, The titanium alloy is Ti-6Al-4V, Ti-5Al-2.5Sn, Ti-6Al-7Nb, Ti-3Al-2.5V, Ti-2Al-2.5Zr, Ti-8Mn, Ti-6Al-6V-2Sn, Ti-6Al-2Sn-4Zr-6Mo, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-2Sn-2Zr-2Mo, Ti-3Al-5Mo-4.5V, Ti-5Mo-5V-8Cr-3Al, Ti-13V-11Cr-3Al, Ti-2.25Al-11Sn-5Zr-1Mo-0.2Si, Ti-6Al-2Zr-1Mo-1V, Ti-15V-3Cr-3Sn-3Al, or Ti-8Al-1Mo-1V; the nickel alloy is Inconel 600, Inconel 601, Inconel 625, Inconel 690, Inconel 718, Inconel 800, Inconel 825, Inconel 901, Hastelloy B, Hastelloy C, Hastelloy X, Hastelloy R or Hastelloy G.

7. A method for preparing a porous metal plate as described in any one of claims 1-6, characterized in that, The preparation method includes: Metal fine powder with a particle size of D10 in the range of 3μm-60μm and a difference between D10 and D90 within 10μm is mixed with an appropriate amount of binder and granulated, and then passed through a 60μm-150μm sieve to obtain powder A. Powder A, coarse metal powder with a particle size D10 of 60μm-200μm and a difference between D10 and D90 within 10μm, and an appropriate amount of binder are mixed and granulated, and then passed through a 180μm-300μm sieve to obtain powder B. The powder B is formed into a metal plate blank, and then the binder is removed and sintered to obtain the porous metal plate.

8. The method for preparing a porous metal plate according to claim 7, characterized in that, The binder is one or more of the following: polyvinyl alcohol, ethanol, stearic acid, zinc stearate, pentaerythritol stearate, ethylene bis-stearamide, paraffin wax, microcrystalline wax, carnauba wax, Fischer-Tropsch wax, polyethylene wax, polyoxymethylene, ethylene-vinyl acetate copolymer, polypropylene, or polyethylene solution.

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