Gas diffusion layer and electrode using same

Abstract

The utility model provides a gas diffusion layer and an electrode using the same. The gas diffusion layer comprises a metal particle layer, a metal fiber felt layer and a metal net layer which are sequentially arranged, the average aperture of the metal particle layer is 0.5-5 microns, the average aperture of the metal fiber felt layer is 5-700 microns, and the average aperture of the metal net layer is larger than that of the metal fiber felt layer. According to the gas diffusion layer provided by the utility model, the metal nets with different apertures, the metal fiber felt layer and the metal particle layer can play a synergistic role, so that the gas diffusion layer has low resistivity and excellent mass transfer capability.

Description

Technical Field

[0001] The utility model belongs to the technical field of AEM water electrolysis hydrogen production, and specifically relates to a gas diffusion layer and an electrode using the same. Background Art

[0002] Hydrogen production through water electrolysis is currently one of the most important methods for producing green hydrogen. Anion exchange membrane water electrolysis (AEMWE) combines the advantages of alkaline electrolyzer (ALK) and proton exchange membrane (PEM) hydrogen production technologies. It not only enables the use of non-precious metal catalysts in an alkaline operating environment but also effectively separates high-purity hydrogen and oxygen. Therefore, AEM hydrogen production can achieve low-cost, high-purity, and high-current density hydrogen production. AEM hydrogen production offers a novel solution to the challenges of renewable energy utilization.

[0003] The gas diffusion layer is one of the core components of the AEM water electrolysis hydrogen production membrane electrode assembly. Its main function is to transfer the gas / liquid phases between the bipolar plate flow field and the catalytic layer, and at the same time act as a current collector to conduct and collect electrons. Commercial electrolyzers mostly use metal porous materials such as sintered plates, metal fiber felt, foam metal, metal mesh materials, etc. as gas diffusion layers. Among them, metal fiber felt has the characteristics of high porosity, large surface area and good pressure resistance and is widely used as a gas diffusion layer. However, when metal fiber felt is used in the gas diffusion layer, the surface pore structure is random. Among them, the side of the metal fiber felt in contact with the bipolar plate flow field has the problem of smaller water channels and mass transfer loss due to the partial coverage of the pores. The side of the metal fiber felt in contact with the catalytic layer has the problem of small contact area and high contact resistance due to the uneven pore size distribution. Therefore, how to optimize the structure of the gas diffusion layer is a technical problem that technicians in this field urgently need to solve in their research. Utility Model Content

[0004] The purpose of the utility model is to provide a gas diffusion layer and an electrode using the same. The gas diffusion layer has a gradient pore structure, low resistivity and excellent mass transfer capability.

[0005] According to one aspect of the present invention, a gas diffusion layer is provided, comprising a metal particle layer, a metal fiber felt layer, and a metal mesh layer, arranged in sequence. The metal particle layer has an average pore size of 0.05 μm to 5 μm, the metal fiber felt layer has an average pore size of 5 μm to 700 μm, and the average pore size of the metal mesh layer is greater than the average pore size of the metal fiber felt layer. The average pore size of the metal particle layer can be 0.05 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc., but is not limited to the values ​​listed, and other values ​​not listed within this numerical range are also applicable. The average pore size of the metal fiber felt layer can be 5 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, etc., but is not limited to the values ​​listed, and other values ​​not listed within this numerical range are also applicable. The present invention provides a gas diffusion layer with a gradient pore structure. On the one hand, the metal mesh layer and metal fiber felt layer in the gas diffusion layer have relatively large pore sizes, which can provide a good mass transfer channel, reduce mass transfer resistance, and help improve the mechanical strength of the gas diffusion layer and prevent it from deformation. On the other hand, the metal particle layer in the gas diffusion layer has a relatively small pore size, which can fully increase the contact surface between the gas diffusion layer and the catalytic layer while ensuring the mass transfer effect of the gas diffusion layer, thereby reducing contact resistance and improving the conductivity of the gas diffusion layer. In summary, the metal fiber felt layer, metal particle layer, and metal mesh layer with different pore sizes in the gas diffusion layer provided by the present invention can play a synergistic role, so that the gas diffusion layer has low resistivity and excellent mass transfer capacity.

[0006] Preferably, the metal fiber felt layer includes a first metal fiber felt layer and a second metal fiber felt layer, with the second metal fiber felt layer and the first metal fiber felt layer being arranged sequentially in a direction away from the metal particle layer; the average pore size of the second metal fiber felt layer is smaller than the average pore size of the first metal fiber felt layer. A gas diffusion layer composed of a metal mesh layer, a first metal fiber felt layer, a second metal fiber felt layer, and a metal particle layer, each having a decreasing pore size gradient, exhibits superior mass transfer capability.

[0007] Preferably, the average pore size of the first metal fiber felt layer is 100 μm to 700 μm, and the average pore size of the second metal fiber felt layer is 5 μm to 100 μm. The average pore size of the first metal fiber felt layer can be 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, etc., but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable. The average pore size of the second metal fiber felt layer can be 5 μm, 20 μm, 35 μm, 50 μm, 65 μm, 70 μm, 85 μm, 100 μm, etc., but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0008] Preferably, the first metal fiber felt layer includes first metal fibers having a diameter of 15 μm to 50 μm; the second metal fiber felt layer includes second metal fibers having a diameter of 2 μm to 15 μm. The first and second metal fibers having these diameters can form first and second metal fiber felt layers with suitable pore sizes and excellent mechanical strength, thereby supporting the gas diffusion layer.

[0009] Preferably, the thickness of the metal fiber felt layer is 0.2 mm to 0.8 mm. The thickness of the metal fiber felt layer can be 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, etc., but is not limited to the listed values. Other values ​​not listed in the range are also applicable.

[0010] Preferably, the thickness of the metal particle layer is 0.02 mm to 0.2 mm. The thickness of the metal particle layer can be 0.02 mm, 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, etc., but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable. By controlling the thickness of the metal fiber felt layer and the metal particle layer, it is beneficial to reduce the mass transfer resistance of the gas diffusion layer while ensuring the excellent mechanical strength of the gas diffusion layer, thereby improving the mass transfer efficiency of the gas diffusion layer.

[0011] The thickness of the first metal fiber felt layer is 0.1 mm to 0.4 mm, and the thickness of the second metal fiber felt layer is 0.1 mm to 0.4 mm. The thickness of the first metal fiber felt layer can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable. The thickness of the second metal fiber felt layer can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0012] Preferably, the metal particle layer comprises metal particles having a diameter of 5 μm to 30 μm. Metal particles of the above diameter can form a dense metal particle layer, thereby increasing the contact area between the metal particle layer and the catalyst layer and reducing the resistivity of the gas diffusion layer.

[0013] Preferably, the mesh size of the metal mesh layer is 20 to 80 meshes, and the average pore size of the metal mesh layer is 180 μm to 830 μm. The average pore size of the metal mesh layer is 180 μm, 280 μm, 380 μm, 480 μm, 580 μm, 680 μm, 780 μm, 830 μm, etc., but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0014] Preferably, the metal mesh layer comprises a metal mesh having a wire diameter of 0.1 mm to 0.5 mm. The metal mesh having the above wire diameter can form a metal mesh layer with high mechanical strength and resistance to deformation.

[0015] Preferably, in the gas diffusion layer, the metal mesh layer, the metal fiber felt layer, and the metal particle layer contain metals such as nickel, stainless steel, titanium, nickel-molybdenum alloy, or chromium-nickel-inconel alloy.

[0016] According to another aspect of the present invention, an electrode is provided, comprising a catalytic layer and the above-mentioned gas diffusion layer, wherein the catalytic layer is composited with the metal particle layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagrams of the structures of gas diffusion layers prepared in Examples 1-2, Examples 5-8, and Comparative Examples 2-4.

[0018] Figure 2 Schematic diagram of the structure of the gas diffusion layer prepared in Example 3.

[0019] Figure 3 Schematic diagram of the structure of the gas diffusion layer prepared in Example 4.

[0020] Figure 4 Schematic diagram of the structure of the gas diffusion layer prepared in Comparative Example 1.

[0021] In the above drawings, the correspondence between the technical features and the drawing marks is: 1 metal mesh layer, 2 first metal fiber felt layer, 3 second metal fiber felt layer, 4 metal particle layer. DETAILED DESCRIPTION

[0022] The following is a further clear and complete description of the technical features of the technical solution provided by the present invention in conjunction with specific embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] Example 1

[0024] This embodiment provides a gas diffusion layer, the preparation method of which includes the following steps:

[0025] 1. Prepare a metal fiber felt layer (the metal fiber felt layer includes a first metal fiber felt layer 2 and a second metal fiber felt layer 3):

[0026] The first metal fiber felt layer 2 is formed by stacking stainless steel metal fibers with a diameter of 15 μm and vacuum compacting and sintering. The average pore size of the first metal fiber felt layer 2 is about 30 μm and the thickness is about 0.3 mm.

[0027] The second metal fiber felt layer 3 is formed by stacking and vacuum compacting stainless steel metal fibers with a diameter of 4 μm. The second metal fiber felt layer 3 has an average pore size of about 10 μm and a thickness of about 0.1 mm.

[0028] 2. The metal mesh layer 1, the first metal fiber felt layer 2, and the second metal fiber felt layer 3 are stacked in this order and vacuum sintered. After sintering, they are roll-pressed and then cleaned with anhydrous ethanol, acetone, and deionized water, followed by drying. The metal mesh layer 1 is composed of a stainless steel mesh with a wire diameter of 0.4 mm, a mesh size of 30, and an average pore size of approximately 0.6 mm.

[0029] 3. Use atmospheric plasma (Ar as carrier gas, flow rate is 2000L / h; H2 as protective gas, flow rate is 30L / h) to spray 316L stainless steel metal powder particles with a diameter of 8μm, so that the metal powder particles are deposited on the top of the second metal fiber felt layer 3 to form a metal particle layer 4. The average pore size of the metal particle layer 4 is 3μm, and the thickness of the metal particle layer 4 is 0.05mm.

[0030] This example prepared Figure 1 The structure of the gas diffusion layer shown in the figure comprises a metal mesh layer 1, a first metal fiber felt layer 2, a second metal fiber felt layer 3, and a metal particle layer 4 in sequence in the thickness direction.

[0031] Example 2

[0032] This embodiment prepared a gas diffusion layer with reference to Example 1. The difference between this embodiment and Example 1 is that during the preparation of the gas diffusion layer, stainless steel fibers with a diameter of 15 μm were used instead of the 4 μm stainless steel fibers in Example 1 to prepare the second metal fiber felt layer 3, resulting in an average pore size of approximately 30 μm (pore size of the first metal fiber felt layer 2 = pore size of the second metal fiber felt layer 3). Aside from these differences, the materials and process used in this embodiment were strictly consistent with those in Example 1.

[0033] Example 3

[0034] This embodiment prepares a gas diffusion layer with reference to Example 1. The difference between this embodiment and Example 1 is that the gas diffusion layer in this embodiment does not include the first metal fiber felt layer 2. Apart from the above differences, the materials and process operations used in this embodiment are strictly consistent with those in Example 1.

[0035] This example prepared Figure 2 The structure of the gas diffusion layer shown in the figure comprises a metal mesh layer 1, a second metal fiber felt layer 3, and a metal particle layer 4 in sequence in the thickness direction.

[0036] Example 4

[0037] This embodiment prepares a gas diffusion layer with reference to Example 1. The difference between this embodiment and Example 1 is that the gas diffusion layer in this embodiment does not include the second metal fiber felt layer 3. Apart from the above difference, the materials and process operations used in this embodiment are strictly consistent with those in Example 1.

[0038] This example prepared Figure 3 The structure of the gas diffusion layer shown in the figure comprises a metal mesh layer 1, a first metal fiber felt layer 2, and a metal particle layer 4 in sequence in the thickness direction.

[0039] Example 5

[0040] This embodiment uses the same method as Example 1 to prepare a gas diffusion layer. The difference between this embodiment and Example 1 is that the thickness of the metal fiber felt layer in this embodiment is approximately 0.1 mm (the thickness of the first metal fiber felt layer 2 is 0.05 mm, and the thickness of the second metal fiber felt layer 3 is 0.05 mm). Apart from these differences, the materials and process operations used in this embodiment are strictly consistent with those in Example 1.

[0041] Example 6

[0042] This embodiment uses the same method as Example 1 to prepare a gas diffusion layer. The difference between this embodiment and Example 1 is that the thickness of the metal fiber felt layer in this embodiment is approximately 1 mm (the thickness of the first metal fiber felt layer 2 is 0.5 mm, and the thickness of the second metal fiber felt layer 3 is 0.5 mm). Apart from these differences, the materials and process operations used in this embodiment are strictly consistent with those in Example 1.

[0043] Example 7

[0044] This embodiment prepares a gas diffusion layer with reference to Example 1. The difference between this embodiment and Example 1 is that the thickness of the metal particle layer 4 in this embodiment is about 0.01 mm. Apart from the above difference, the materials and process operations used in this embodiment are strictly consistent with those in Example 1.

[0045] Example 8

[0046] This embodiment prepares a gas diffusion layer with reference to Example 1. The difference between this embodiment and Example 1 is that the thickness of the metal particle layer 4 in this embodiment is about 0.3 mm. Apart from the above difference, the materials and process operations used in this embodiment are strictly consistent with those in Example 1.

[0047] Comparative Example 1

[0048] This comparative example prepares a gas diffusion layer with reference to Example 1. The difference between this comparative example and Example 1 is that the gas diffusion layer in this comparative example does not include the metal particle layer 4. Apart from the above difference, the materials and process operations used in this comparative example are strictly consistent with those in Example 1.

[0049] The comparative example is Figure 4 The structure of the gas diffusion layer shown in the figure comprises a metal mesh layer 1, a first metal fiber felt layer 2, and a second metal fiber felt layer 3 in sequence in the thickness direction.

[0050] Comparative Example 2

[0051] In this comparative example, a gas diffusion layer was prepared with reference to Example 1. The difference between this comparative example and Example 1 is that the average pore size of the first metal fiber felt layer 2 in this comparative example is approximately 5 μm, and the average pore size of the second metal fiber felt layer 3 is approximately 3.5 μm. Aside from these differences, the materials and process used in this comparative example are strictly consistent with those in Example 1.

[0052] Comparative Example 3

[0053] This comparative example uses Example 1 to prepare a gas diffusion layer. The difference between this comparative example and Example 1 is that the average pore size of the metal particle layer 4 in this comparative example is approximately 0.1 μm. Apart from the above difference, the materials and process used in this comparative example are strictly consistent with those in Example 1.

[0054] Comparative Example 4

[0055] This comparative example prepared a gas diffusion layer with reference to Example 1. The difference between this comparative example and Example 1 is that the average pore size of the metal particle layer 4 in this comparative example is about 30 μm. Apart from the above difference, the materials and process used in this comparative example are strictly consistent with those in Example 1.

[0056] Test Example 1

[0057] 1. Participants:

[0058] The gas diffusion layers and water electrolysis cells prepared in Examples 1 to 8 and Comparative Examples 1 to 4 were used as parameter objects.

[0059] The preparation method of the water electrolysis cell is as follows: according to the end plate, current collector, cathode flow field, cathode gas diffusion layer, CCM electrode (the catalyst on the cathode side is loaded with 0.5 mg / cm 2 The Pt / C anode catalyst has a loading of 2 mg / cm 2 The water electrolysis single cell device is assembled in the order of IrO2), anode gas diffusion layer (the gas diffusion layer prepared in Examples 1 to 9 and Comparative Examples 1 to 4 is used as the anode gas diffusion layer of the AEM water electrolysis single cell), anode flow field, current collector, and anode end plate.

[0060] 2. Test items:

[0061] (1) Tensile strength: The GDL was tested according to the method described in GB / T 228.1-2021 Metallic materials tensile test Part 1: Room temperature test method. m To express.

[0062] (2) Contact resistance: The test device is an electrochemical workstation. The AC impedance of the test water electrolysis cell is measured at open circuit potential, with a frequency setting of 1 to 100,000 Hz and an amplitude of 10 mV. The HFR value of the fitting test results is recorded to reflect the contact resistance.

[0063] (3) CP voltage: The test device is an electrochemical workstation, the test is stable at 60 ° C, and the current density is set to 0~1A / cm according to the ten current steps. 2 Each current step was tested for 10 seconds, with a voltage value recorded every second. The average voltage at each current step was recorded. The CP voltage = the sum of the voltage values ​​at the ten current steps / 10. The larger the CP voltage, the poorer the mass transfer capacity of the water electrolysis cell.

[0064] 3. Test results:

[0065] Table 1 Performance test results of Examples 1 to 8 and Comparative Examples 1 to 4

[0066]

[0067] The test results are shown in Table 1. Comparing the performance test results corresponding to Example 1 and Comparative Example 1, it can be found that the contact resistance and CP voltage of the water electrolysis cell prepared in Comparative Example 1 are higher than those in Example 1, and the tensile strength is lower than that in Example 1. The reason is that the gas diffusion layer in Comparative Example 1 does not include a metal particle layer, and the metal fiber felt layer with a larger pore size in the gas diffusion layer is composited with the catalytic layer, resulting in a decrease in the contact area between the gas diffusion layer and the catalytic layer, an increase in the contact resistance, and a deterioration in the mass transfer effect of the water electrolysis cell prepared thereby.

[0068] Comparing the performance test results of Example 1 with those of Comparative Examples 3-4, it can be found that the contact resistance and CP voltage of the water electrolysis cells prepared in Comparative Examples 3-4 are higher than those in Example 1. This is because the pore size of the metal particle layer in Comparative Example 3 is too small, making it difficult to ensure the mass transfer effect of the gas diffusion layer; while the pore size of the metal particle layer in Comparative Example 4 is too large, which reduces the contact area between the gas diffusion layer and the catalytic layer and increases the contact resistance, thereby increasing the resistivity of the water electrolysis cell prepared thereby and deteriorating the mass transfer effect.

[0069] Comparing the performance test results corresponding to Example 1 and Comparative Example 2, it can be found that the contact resistance and CP voltage of the water electrolysis cell prepared in Comparative Example 1 are higher than those in Example 1. The reason is that the average pore size of the metal fiber felt layer in the gas diffusion layer in Comparative Example 1 is less than 5 μm, which makes it difficult to provide a good mass transfer channel for the gas diffusion layer, resulting in a deterioration in the mass transfer effect of the cell prepared thereby.

[0070] The performance test results of Example 1 were compared with those of Examples 2 to 4. As shown in Table 1, under the same conditions as for other materials and operations used to prepare the single cell, the average pore size of the first metal fiber felt layer in Example 2 was equal to the average pore size of the second metal fiber felt layer, and the contact resistance and CP voltage of the water electrolysis single cell prepared thereby were slightly higher than those of Example 1. In Examples 3 and 4, the gas diffusion layers did not include the first metal fiber felt layer and the second metal fiber felt layer, respectively, and the contact resistance and CP voltage of the water electrolysis single cells prepared thereby were slightly higher than those of Example 1, and the tensile strength was slightly lower than that of Example 1. This shows that, compared with Examples 2 to 4, Example 1, by using the first metal fiber felt layer and the second metal fiber felt layer with a decreasing pore size gradient as the metal fiber felt layer, can make the gas diffusion layer have a better mass transfer effect and mechanical strength.

[0071] The performance test results of Example 1 were compared with those of Examples 5 to 8. As shown in Table 1, under the same other material and operating conditions for preparing the water electrolysis cell, the thickness of the metal fiber felt layer in Example 5 was less than 0.2 mm, the thickness of the metal fiber felt layer in Example 6 was greater than 0.8 mm, the thickness of the metal particle layer in Example 7 was less than 0.02 mm, and the thickness of the metal particle layer in Example 8 was greater than 0.2 mm. The contact resistance and CP voltage of the water electrolysis cell thus prepared were slightly higher than those of Example 1. This demonstrates that, compared to Examples 5 to 8, Example 1, by controlling the thickness of the metal fiber felt layer and the metal particle layer, can reduce the mass transfer resistance between the gas diffusion layer and the catalytic layer while maintaining the mechanical strength of the gas diffusion layer, thereby optimizing the mass transfer efficiency of the gas diffusion layer.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the technical solutions of the present invention can be modified or replaced by equivalents, but these modifications or replacements are all within the scope of protection of the present invention.

Claims

1. A gas diffusion layer, characterized in that: The gas diffusion layer comprises a metal particle layer, a metal fiber felt layer and a metal mesh layer arranged in sequence; The average pore size of the metal particle layer is 0.5 μm to 5 μm, the average pore size of the metal fiber felt layer is 5 μm to 700 μm, and the average pore size of the metal mesh layer is greater than the average pore size of the metal fiber felt layer.

2. The gas diffusion layer according to claim 1, wherein: The metal fiber felt layer comprises a first metal fiber felt layer and a second metal fiber felt layer, and the second metal fiber felt layer and the first metal fiber felt layer are sequentially arranged in a direction away from the metal particle layer; The average pore size of the second metal fiber felt layer is smaller than the average pore size of the first metal fiber felt layer.

3. The gas diffusion layer according to claim 2, wherein: The average pore size of the first metal fiber felt layer is 100 μm to 700 μm, and the average pore size of the second metal fiber felt layer is 5 μm to 100 μm.

4. The gas diffusion layer according to claim 3, wherein: The first metal fiber felt layer includes first metal fibers, and the diameter of the first metal fibers is 15 μm to 50 μm; The second metal fiber felt layer includes second metal fibers, and the diameter of the second metal fibers is 2 μm to 15 μm.

5. The gas diffusion layer according to claim 1, wherein: The thickness of the metal fiber felt layer is 0.2 mm to 0.8 mm.

6. The gas diffusion layer according to claim 5, characterized in that: The thickness of the metal particle layer is 0.02 mm to 0.2 mm.

7. The gas diffusion layer according to claim 1, wherein: The metal particle layer includes metal particles, and the diameter of the metal particles is 5 μm to 30 μm.

8. The gas diffusion layer according to claim 1, wherein: The mesh number of the metal mesh layer is 20 to 80 meshes, and the average pore size of the metal mesh layer is 180 μm to 830 μm.

9. The gas diffusion layer according to any one of claims 1 to 8, characterized in that: The metal contained in the metal mesh layer, the metal fiber felt layer and the metal particle layer is nickel, stainless steel, titanium, nickel-molybdenum alloy or chromium-nickel-inconel alloy.

10. An electrode, characterized in that: The invention comprises a catalytic layer and the gas diffusion layer according to any one of claims 1 to 9, wherein the catalytic layer is composited with the metal particle layer.

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