High-stability water electrolysis hydrogen production membrane electrode with interface optimization structure

Abstract

The invention relates to the technical field of porous electrodes for hydrogen production by electrolysis of water, and particularly discloses a high-stability membrane electrode for hydrogen production by electrolysis of water with an interface optimization structure, elastic buffer layers are respectively arranged in an anode gas diffusion layer and a cathode gas diffusion layer, frames are added to two sides of a CCM, and gaps are reserved. Through the design of an asymmetric frame and an elastic buffer layer, the damage of a rigid gas diffusion layer (GDL) to a catalyst layer CCM under assembly pressure, cathode high pressure and CCM swelling stress is weakened, and an elastic layer absorbs pressure energy to slow down interface extrusion; the pore gradient GDL structure improves gas discharge and reduces mass transfer resistance energy loss, and the elastic layer maintains tight contact between the GDL and the CCM so as to reduce ohmic loss. Mechanical stability is improved, CCM structure damage is reduced, and the running performance stability of electrolyzed water and the stability of hydrogen in oxygen are guaranteed; the asymmetric frame, the buffer layer and the thickness-adjustable elastic structure cooperatively adapt to pressure fluctuation and stress change, and adapt to technical scenes of renewable energy coupling hydrogen production, off-grid high-pressure hydrogen storage and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of porous electrodes for hydrogen production by water electrolysis, and more particularly to a high-stability hydrogen production by water electrolysis membrane electrode with interface optimization structure. BACKGROUND

[0002] As an important way of clean energy conversion, the performance and stability of the core component membrane electrode (MEA) of hydrogen production by water electrolysis directly determine the efficiency and service life of the system. Direct storage of high-pressure hydrogen can match the charging demand of high-pressure hydrogen cylinders, save multi-stage compressor units, simplify the structure of the water electrolysis system and improve the system efficiency. Therefore, increasing the operating pressure on the cathode side has become an important development direction of the electrolyzer. However, high pressure on the cathode side will face severe problems of compression stress imbalance and hydrogen safety: Because the gas transport layer and its adjacent flow field are rigid structures, the pressure generated by the high pressure on the cathode side will be transmitted to the anode catalyst layer and the anode gas transport layer interface through the structure-soft catalyst coated membrane (CCM). The traditional symmetrical structure causes the anode side to bear an over-designed pressure, the anode catalyst layer structure is damaged, and even the membrane structure is damaged and the CCM is deformed, which reduces the performance of water electrolysis and increases the hydrogen content in oxygen related to operation safety. In addition, during operation, the CCM will also gradually increase in thickness, which will further exacerbate the extrusion deformation of the CCM, and thus cause performance degradation and an increase in hydrogen content in oxygen. SUMMARY

[0003] The present application aims to overcome at least one of the above-mentioned deficiencies of the prior art, and to provide a high-stability hydrogen production by water electrolysis membrane electrode with interface optimization structure, which improves the mechanical stability of the membrane electrode, slows down the deformation of the CCM, and improves the performance stability and oxygen hydrogen stability during the operation of water electrolysis.

[0004] The technical solution adopted by the present application is to provide a high-stability hydrogen production by water electrolysis membrane electrode with interface optimization structure, which comprises an anode gas diffusion layer, an anode frame, a catalyst coated membrane (CCM), a cathode frame and a cathode gas diffusion layer connected in sequence, the catalyst coated membrane comprises an anode catalyst layer, an anode hydrogen elimination layer, a proton exchange membrane and a cathode catalyst layer, the anode gas diffusion layer comprises an anode diffusion layer base layer and an anode buffer layer, the anode buffer layer is located on the side close to the anode catalyst layer, the cathode gas diffusion layer comprises a cathode diffusion layer base layer and a cathode buffer layer, the cathode buffer layer is located on the side close to the cathode catalyst layer, the anode frame and the cathode frame sandwich or enclose the catalyst coated membrane, the anode gas diffusion layer further comprises an anode elastic buffer layer between the anode diffusion layer base layer and the anode buffer layer, and the cathode gas diffusion layer further comprises a cathode elastic buffer layer between the cathode diffusion layer base layer and the cathode buffer layer.

[0005] In the process of hydrogen production by water electrolysis, the stress generated by the cathode side pressure and the CCM swelling acts on the gas diffusion layer, especially the anode gas diffusion layer, and the rigid structure of the existing gas diffusion layer is the key factor leading to the extrusion damage of the interface between the gas diffusion layer and the CCM. In order to cope with the above-mentioned force, an anode elastic buffer layer is added between the anode diffusion layer base layer and the anode buffer layer. When the cathode is operated at high pressure, the anode elastic buffer layer can absorb part of the cathode side pressure and the CCM swelling stress, and slow down the extrusion deformation of the interface between the anode gas diffusion layer and the CCM; when the cathode is operated at normal pressure or reduced pressure, the elastic buffer layer can push the anode buffer layer to tightly contact with the anode catalyst layer interface, thereby ensuring the performance stability of water electrolysis.

[0006] Further, the material of the anode elastic buffer layer is one of metal-based elastic porous material, conductive polymer composite material and ceramic-metal composite porous body.

[0007] Further, the thickness of the anode elastic buffer layer is 0.005-1 mm.

[0008] Further, the material of the cathode elastic buffer layer is one of carbon-based elastic porous material, metal-based elastic porous material, conductive polymer composite material and ceramic-metal composite porous body.

[0009] Further, the thickness of the cathode elastic buffer layer is 0.005-1 mm.

[0010] Further, the middle of the anode frame is reserved with a first gap, and the first gap is located between the anode gas diffusion layer and the catalyst coated membrane; the middle of the cathode frame is reserved with a second gap, and the second gap is located between the cathode gas diffusion layer and the catalyst coated membrane. Because the cathode side pressure and the CCM swelling stress make the cathode gas diffusion layer and the CCM both produce deformation towards the anode gas diffusion layer, the first gap and the second gap are set, which avoids the contact after deformation being too tight when the cathode is operated at high pressure, and helps to reduce the mechanical damage caused by deformation extrusion, thereby ensuring the performance stability of water electrolysis. In addition, as mentioned above, when the cathode is operated at normal pressure or reduced pressure, the elastic buffer layer can push the anode buffer layer to tightly contact with the anode catalyst layer interface, thereby ensuring the performance stability of water electrolysis.

[0011] Further, the anode buffer layer is a multi-layer structure, and the porosity or pore size of the multi-layer structure increases layer by layer from the side close to the CCM to the side far from the CCM. The porosity of the first buffer layer is 10%-70%, and the porosity of the base layer is 20-90%. In the anode gas diffusion layer, the anode diffusion layer base layer provides mechanical support; the anode buffer layer is designed to have a smoother surface structure and is placed at the interface in contact with the anode catalyst layer to minimize the mechanical compression effect of the cathode side pressure and CCM swelling on the anode. In order to optimize the interface structure, the anode buffer layer is designed to have a multi-layer gradient pore size or porosity distribution structure. The first buffer layer closest to the CCM has a small porosity or small pore size in order to meet the smoothness of the surface; and a second buffer layer with a higher porosity or a larger pore size and a third buffer layer with an increasing porosity or pore size can be added to meet the gas transmission needs.

[0012] Further, the cathode buffer layer is a multi-layer structure, and the porosity or pore size of the multi-layer structure increases layer by layer from the side close to the CCM to the side far from the CCM. The first buffer layer in contact with the cathode catalyst layer has a smoother surface, which can reduce the extrusion damage of the cathode gas diffusion layer to the cathode catalyst layer under the action of the assembly force; the gradient design of the increasing porosity from the cathode catalyst layer to the cathode gas diffusion layer base layer can also help to quickly discharge hydrogen and strengthen the mass transfer effect; the design of the elastic buffer layer can also make the membrane electrode suitable for operation under different operating pressures and ensure the contact between the cathode gas diffusion layer and the CCM.

[0013] The cathode gas diffusion layer can be an integrated structure or a combination of the base layer and the buffer layers. Further, the material of the anode diffusion layer base layer and the cathode diffusion layer base layer is one of a titanium felt, a sintered titanium plate, and a porous titanium plate. Further, the material of the anode buffer layer and the cathode buffer layer is at least one of a titanium felt, a sintered titanium plate, a porous titanium plate, a titanium fiber sintered material, a titanium powder sintered material, an Ir / Ta alloy material, a Pt / TiN nanowire material, fluorine-doped tin oxide (FTO), a TiC titanium-based material, a noble metal modified material, and a non-noble metal corrosion-resistant material.

[0014] Further, the root mean square deviation (Sq) of the surface roughness of the anode buffer layer and the cathode buffer layer is 0.1-50µm. A suitable roughness can increase the specific surface area of the electrode, provide more reaction sites, improve the electrochemical activity, promote the diffusion of electrolyte ions, reduce the ion transmission resistance, and improve the performance of the membrane electrode.

[0015] Further, the cathode and anode frame are divided into frame base material and adhesive; the frame base material is one of PEN, PPS and PTFE; one side of the frame base material is provided with adhesive, used for being attached to CCM, proton exchange membrane or another side provided with adhesive frame; the adhesive is at least one of epoxy resin, polyolefin material, acrylate and acrylic.

[0016] Further, the thickness of the cathode frame is 0.01-0.15 mm. The thickness of the cathode frame is not more than the thickness of the anode frame. The ratio of the thickness of the cathode frame to the thickness of the catalyst coated membrane is 0.05-10. The thickness of the frame of the cathode and the anode is closely related to the swelling of CCM and the back pressure of the cathode: suitable frame thickness can provide sufficient space for the swelling of CCM during operation, preventing excessive compression of the gas diffusion layer to the cathode and anode catalyst layer; due to the high pressure on the cathode side, the CCM is pressed to the anode gas diffusion layer, in order to better adapt to the high pressure operation of the cathode, it is preferred that the frame of the anode and the cathode is designed as an asymmetric structure, that is, the thickness of the anode frame is greater than the thickness of the cathode frame, so that more space is reserved for the anode side, thereby reducing the extrusion deformation of the CCM by the anode gas diffusion layer. However, too thick anode frame will cause excessive tension on the CCM, resulting in damage to the membrane, and will affect the contact between the gas diffusion layer and the CCM, resulting in a decrease in the performance of electrolytic water.

[0017] Preferably, the ratio of the thickness of the anode frame to the thickness of the cathode frame is 1-10.

[0018] Compared with the prior art, the present application has the following beneficial effects: (1) Improved mechanical stability: the asymmetric frame design combined with the gas diffusion layer buffer layer design can reduce the damage of the rigid gas diffusion layer to the CCM structure under the action of assembly pressure, cathode high pressure and CCM swelling stress; the elastic buffer layer can help the CCM to absorb part of the pressure energy and reduce the extrusion effect of the gas diffusion layer and the CCM interface.

[0019] (2) Optimized electrochemical performance: the pore gradient gas diffusion layer structure design can improve the exhaust of gas and reduce the energy loss caused by mass transfer resistance; the elastic buffer layer can always ensure the close contact between the gas diffusion layer and the CCM, reducing the ohmic loss.

[0020] (3) Improved durability and safety: the improvement of mechanical stability means less damage to the CCM structure, which helps to improve the performance stability and oxygen hydrogen stability during electrolytic water operation. (4) Wide working condition adaptability expansion: the asymmetric frame design combined with the gas diffusion layer buffer layer design and the elastic buffer layer structure with thickness adjustment function can well adapt to the stress change under the pressure fluctuation condition, and is especially suitable for the front scene of renewable energy coupling hydrogen production, off-grid high-pressure hydrogen storage and the like, and has significant technical advancement and market competitiveness. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a schematic diagram of the membrane electrode structure of the application.

[0022] Figure 2 It is a hydrogen-in-oxygen comparison chart of Example 1 and Comparative Example 1 of the application under voltage fluctuation conditions.

[0023] Figure 3 It is a hydrogen-in-oxygen comparison chart of Example 1 and Comparative Example 2 of the application under voltage fluctuation conditions.

[0024] Figure 4 It is a hydrogen-in-oxygen comparison chart of Example 1 and Comparative Example 3 of the application under voltage fluctuation conditions.

[0025] Figure 5 It is a current density comparison chart of Example 1 of the application under voltage fluctuation conditions.

[0026] Figure 6 It is a current density comparison chart of Comparative Example 2 of the application under voltage fluctuation conditions.

[0027] Figure 7 It is a current density comparison chart of Comparative Example 3 of the application under voltage fluctuation conditions.

[0028] In the figure: 1, anode gas diffusion layer base layer; 2, anode gas diffusion layer elastic buffer layer; 3, anode gas diffusion layer buffer layer; 4, anode frame substrate; 5, anode frame adhesive; 6, anode catalytic layer; 7, anode hydrogen elimination layer; 8, proton exchange membrane; 9, cathode catalytic layer; 10, cathode frame adhesive; 11, cathode frame substrate; 12, cathode gas diffusion layer buffer layer; 13, cathode gas diffusion layer elastic buffer layer; 14, cathode gas diffusion layer base layer. DETAILED DESCRIPTION

[0029] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] The present invention will now be further illustrated with specific examples. The following embodiments are only for explaining the present invention and do not constitute a limitation thereof. If the specific experimental conditions are not specified in the embodiments, they should be understood according to conventional conditions or conditions recommended by the reagent company; unless otherwise specified, the reagents, consumables, etc. used in the following embodiments can be obtained commercially.

[0032] Example 1 like Figure 1 As shown, the membrane electrode structure, from top to bottom, consists of: anode gas diffusion layer substrate 1, anode gas diffusion layer elastic buffer layer 2, anode gas diffusion layer buffer layer 3, anode frame substrate 4, anode frame adhesive 5, anode catalyst layer 6, anode hydrogen removal layer 7, proton exchange membrane 8, cathode catalyst layer 9, cathode frame adhesive 10, cathode frame substrate 11, cathode gas diffusion layer buffer layer 12, cathode gas diffusion layer elastic buffer layer 13, and cathode gas diffusion layer substrate 14. The anode catalyst layer 6, anode hydrogen removal layer 7, proton exchange membrane 8, and cathode catalyst layer 9 constitute the cathode membrane diffusion layer (CCM). The cathode and anode gas diffusion layers are divided into a substrate layer and a buffer layer, with the substrate layer primarily providing mechanical support. In this embodiment, both the cathode and anode gas diffusion layers employ a buffer layer structure design. This buffer layer has a smoother surface structure than the substrate layer, used to minimize the mechanical compression effects of assembly pressure, cathode side pressure, and CCM swelling on the cathode and anode. The anode gas diffusion layer base layer 1 is made of titanium felt with a thickness of 0.3 mm and a porosity of 70%. The anode gas diffusion layer buffer layer 3 is made of sintered titanium powder with a thickness of 0.08 mm and a porosity of 30%. The cathode gas diffusion layer base layer 14 is made of carbon paper with a thickness of 0.2 mm and a porosity of 80%. The cathode gas diffusion layer buffer layer 12 is made of carbon powder with a thickness of 0.08 mm and a porosity of 25%. In this embodiment, an elastic buffer layer is also provided between the cathode and anode diffusion layer base layers and buffer layers to adjust the thickness of the gas diffusion layer. The anode elastic buffer layer is made of titanium fiber elastic porous material with a thickness of 0.1 mm, and the cathode elastic buffer layer is made of carbon fiber elastic porous material with a thickness of 0.1 mm. The cathode and anode gas diffusion layer base layers, elastic buffer layers, and buffer layers are integrated structures. In this embodiment, the cathode and anode frames adopt an asymmetrical structure, with the cathode frame thickness of 0.05 mm and the anode frame thickness of 0.1 mm.

[0033] Comparative Example 1 Comparative Example 1 Other steps are the same as Example 1, except that in this comparative example, the cathode and anode frame adopt a symmetrical structure, the thickness of the cathode frame is 0.05 mm, and the thickness of the anode frame is 0.05 mm.

[0034] Comparative Example 2 Comparative Example 2 Other steps are the same as Example 1, except that the cathode and anode gas diffusion layers only have a base layer, and the base layer is in direct contact with the cathode and anode catalyst layers 6, without a buffer layer and an elastic buffer layer. In this comparative example, the cathode and anode frame adopt a symmetrical structure, the thickness of the cathode frame is 0.05 mm, and the thickness of the anode frame is 0.05 mm.

[0035] Comparative Example 3 Comparative Example 3 Other steps are the same as Example 1, except that the cathode and anode gas diffusion layers only have a base layer and a buffer layer, without an elastic buffer layer.

[0036] Figure 2 The graph is a comparison of the long-term oxygen-in-hydrogen content of Example 1 and Comparative Example 1 under voltage fluctuation conditions (1.45-2.0 V). It can be seen that Example 1 with an asymmetric frame structure has lower oxygen-in-hydrogen content and more stable oxygen-in-hydrogen content changes, which will help improve safety during operation. Under a cathode back pressure of 3 MPa, the high pressure on the cathode side will press the CCM towards the anode gas diffusion layer, and Example 1 with an asymmetric frame structure can reserve more space for the anode side, thereby reducing the deformation of the anode gas diffusion layer on the CCM, so that Example 1 has lower and more stable oxygen-in-hydrogen content.

[0037] Figure 3 The graph is a comparison of the long-term oxygen-in-hydrogen content of Example 1 and Comparative Example 2 under voltage fluctuation conditions. It can be seen that Example 1 with an asymmetric frame design combined with a gas diffusion layer buffer layer design and an elastic buffer layer structure with thickness adjustment function has lower oxygen-in-hydrogen content and more stable oxygen-in-hydrogen content changes. Figure 4The long-term oxygen in hydrogen content comparison chart of Example 1 and Comparative Example 3 under voltage fluctuation condition. It can be seen that, although the remaining conditions are the same, Example 1 with the elastic buffer layer still has a lower oxygen in hydrogen content and a more stable oxygen in hydrogen content change, indicating the necessity of the elastic buffer layer. Example 1 can minimize the mechanical compression effect of the assembly pressure, the cathode side pressure and the CCM swelling on the cathode and anode interface by introducing a buffer layer with a more smooth surface structure between the gas diffusion layer base layer and the catalytic layer; the elastic buffer layer between the base layer and the buffer layer can absorb part of the assembly pressure, the cathode side pressure and the CCM swelling stress when the cathode is running at high pressure, and slow down the extrusion deformation of the gas transfer layer and the catalytic layer interface; the design of the asymmetric frame structure will also further reduce the extrusion deformation of the anode gas diffusion layer to the CCM; in combination of the above factors, Example 1 has a lower and more stable oxygen in hydrogen content.

[0038] Figure 5 、 Figure 6 and Figure 7 are the long-term current density comparison charts of Example 1, Comparative Example 2 and Comparative Example 3 under voltage fluctuation condition. It can be seen that the current density of Example 1 does not decay over time, while the current density of Comparative Example 2 and Comparative Example 3 gradually decreases over time, and the current density of Comparative Example 2 decreases faster, indicating that the CCM structure of the membrane electrode of Comparative Example 2 and Comparative Example 3 is damaged during operation, and the damage of Comparative Example 2 is more serious, resulting in performance degradation during operation. Under voltage fluctuation condition, the stress inside the membrane electrode is also changing, and the elastic buffer layer structure with thickness adjustment function of Example 1 can maintain the close contact of the gas diffusion layer and the catalytic layer interface at all times, thereby ensuring the performance stability of water electrolysis.

[0039] Obviously, the above embodiments of the present application are only examples for clearly illustrating the technical solutions of the present application, and are not intended to limit the specific embodiments of the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-stability electrolytic water hydrogen production membrane electrode with an interface-optimized structure, comprising an anode gas diffusion layer, an anode frame, a catalyst-coated membrane, a cathode frame and a cathode gas diffusion layer connected in sequence, the catalyst-coated membrane comprising an anode catalytic layer, an anode hydrogen elimination layer, a proton exchange membrane and a cathode catalytic layer, the anode gas diffusion layer comprising an anode diffusion layer base layer and an anode buffer layer, the anode buffer layer being located on the side close to the anode catalytic layer, the cathode gas diffusion layer comprising a cathode diffusion layer base layer and a cathode buffer layer, the cathode buffer layer being located on the side close to the cathode catalytic layer, the anode gas diffusion layer further comprising an anode elastic buffer layer between the anode diffusion layer base layer and the anode buffer layer, and the cathode gas diffusion layer further comprising a cathode elastic buffer layer between the cathode diffusion layer base layer and the cathode buffer layer. characterized in that The material of the anode elastic buffer layer is one of a metal-based elastic porous material, a conductive polymer composite material and a ceramic-metal composite porous body.

2. The high-stability water electrolysis hydrogen production membrane electrode with an interface-optimized structure according to claim 1, characterized in that, The thickness of the anode elastic buffer layer is 0.005-1 mm.

3. The high-stability water electrolysis hydrogen production membrane electrode with an interface-optimized structure according to claim 1, characterized in that, The material of the cathode elastic buffer layer is one of a carbon-based elastic porous material, a metal-based elastic porous material, a conductive polymer composite material and a ceramic-metal composite porous body.

4. The high-stability water electrolysis hydrogen production membrane electrode with an interface-optimized structure according to claim 1, characterized in that, The thickness of the cathode elastic buffer layer is 0.005-1 mm.

5. The high-stability water electrolysis hydrogen production membrane electrode with interface-optimized structure according to claim 1, characterized in that, A first gap is reserved in the middle of the anode frame, and the first gap is located between the anode gas diffusion layer and the catalyst-coated membrane; a second gap is reserved in the middle of the cathode frame, and the second gap is located between the cathode gas diffusion layer and the catalyst-coated membrane.

6. The high-stability water electrolysis hydrogen production membrane electrode with an interface-optimized structure according to any one of claims 1-5, characterized in that, The thickness of the cathode frame is 0.01-0.15 mm.

7. The high-stability water electrolysis hydrogen production membrane electrode with an interface-optimized structure according to any one of claims 1-5, characterized in that, The thickness of the cathode frame is not more than the thickness of the anode frame.

8. The high-stability water electrolysis hydrogen production membrane electrode with an interface-optimized structure according to any one of claims 1-5, characterized in that, The ratio of the thickness of the cathode frame to the thickness of the catalyst-coated membrane is 0.05-10.

9. The high-stability water electrolysis hydrogen production membrane electrode with an interface-optimized structure according to any one of claims 1-5, characterized in that, The root mean square deviation of the surface roughness of the anode buffer layer and the cathode buffer layer is 0.1-50 µm.

10. The high-stability water electrolysis hydrogen production membrane electrode with an interface-optimized structure according to any one of claims 1-5, characterized in that, ​

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