A diffusion layer for a differential pressure proton exchange membrane electrolyzer that prevents membrane electrode deformation

Abstract

The present invention relates to the technical field of hydrogen production by electrolysis of water, and specifically to a diffusion layer for a differential pressure proton exchange membrane electrolyzer that prevents deformation of a membrane electrode, including a diffusion layer substrate, a first gradient layer, and a second gradient layer. The gradient pore structure is used to improve the contact structure between the transmission layer and the bipolar plate, and effective support can be provided under the pressure difference formed by the cathode and anode of the membrane electrode, effectively solving the problem that the swelling of the membrane electrode will cause the membrane to enter the titanium fiber felt, while ensuring the transmission of steam and water, increasing the contact area between the membrane electrode and the surface of the titanium fiber felt, reducing the area of ​​the membrane electrode invading the titanium fiber felt, and preventing the membrane electrode from being severely deformed or even damaged. At the same time, a preparation method thereof is also provided, using a template agent as a method of controlling pores to prepare a gradient pore structure, the control of porosity is more precise, a titanium fiber felt that does not require a flow field is prepared, the fluid distribution is more uniform, and the supporting effect of the plate on the membrane electrode is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen production by electrolysis of water, and in particular to a diffusion layer for a differential pressure proton exchange membrane electrolyzer capable of preventing deformation of a membrane electrode. Background Art

[0002] PEM (proton exchange membrane) water electrolysis hydrogen production technology has become a suitable solution for water electrolysis hydrogen production due to its high operating current density, low energy consumption, high hydrogen production pressure and easy combination with renewable energy. It has developed rapidly in recent years. High-pressure PEM water electrolysis hydrogen production technology is usually divided into two categories: equal pressure type and differential pressure type. Among them, the differential pressure PEM electrolyzer has the advantages of high electrolysis efficiency and low cost; however, in differential pressure water electrolysis, the cathode side of the membrane electrode is in a high-pressure environment, and the anode side is in a normal pressure environment. Therefore, the membrane electrode needs to be able to withstand the pressure difference between the target hydrogen pressure and the anode side pressure, and is prone to deformation or even damage. This pressure resistance is supported by the porous diffusion layer and the bipolar plate, so it is necessary to improve the contact structure between the diffusion layer and the bipolar plate, which is of great significance. Summary of the invention

[0003] In view of the technical problems in the prior art, the purpose of the present invention is to provide a diffusion layer for a differential pressure proton exchange membrane electrolyzer that prevents the deformation of the membrane electrode, solves the problem that the membrane electrode in the differential pressure PEM electrolyzer is prone to large deformation, and the membrane electrode swelling is easy to invade the titanium fiber felt, ensuring the normal transmission of water vapor; at the same time, the electrolyzer is designed without flow field, and the fluid distribution is more uniform. At the same time, the present invention provides a preparation method thereof.

[0004] To achieve the above purpose, the technical solution provided by the present invention is:

[0005] On the one hand, the present invention provides a diffusion layer for a differential pressure proton exchange membrane electrolyzer that prevents membrane electrode deformation, comprising a diffusion layer substrate, a first gradient layer and a second gradient layer. The first gradient layer is provided on one side of the diffusion layer substrate, and the second gradient layer is provided on the other side. The first gradient layer includes at least one metal particle layer, and the second gradient layer includes at least one metal particle layer. A gradient pore structure is formed in sequence between the first gradient layer, the diffusion layer substrate and the second gradient layer.

[0006] The present invention provides a diffusion layer for a differential pressure proton exchange membrane electrolyzer that prevents membrane electrode deformation. The gradient pore structure is adopted to improve the contact structure between the transmission layer and the bipolar plate, and effective support can be provided under the pressure difference formed by the cathode and anode of the membrane electrode, thereby effectively solving the problem that the swelling of the membrane electrode will cause the membrane to enter the titanium fiber felt. While ensuring the transmission of steam and water, the contact area between the membrane electrode and the surface of the titanium fiber felt is increased, the area of ​​the membrane electrode invading the titanium fiber felt is reduced, and the membrane electrode is prevented from being severely deformed or even damaged.

[0007] Based on the above technical solution, the first gradient layer includes multiple metal particle layers arranged on the surface of the diffusion layer substrate from top to bottom, and the particle size of each layer of particles increases successively.

[0008] Based on the above technical solution, the first gradient layer includes a first particle layer and a second particle layer laid in sequence from top to bottom, and the particle size of the first particle layer is larger than that of the second particle layer; the second gradient layer includes a third particle layer, and the particle size of the third particle layer is larger than that of the second particle layer.

[0009] Based on the above technical solution, the particle size ranges of the first particle layer, the second particle layer and the third particle layer are 20-50nm, 50-60nm and 200-500nm respectively.

[0010] Based on the above technical solution, the porosity of the first particle layer, the second particle layer and the third particle layer are 30%-40%, 50%-60% and 70%-80% respectively.

[0011] By arranging the first gradient layer and the second gradient layer on both sides of the diffusion layer substrate, the corresponding gradient layer is paved with one or more layers of metal particle layers. From top to bottom, a gradient pore structure with small top and large bottom is formed between the metal particle layer in the first gradient layer, the diffusion layer substrate, and the metal particle layer in the second gradient layer, that is, the porosity also gradually increases from top to bottom, thereby increasing the contact area between the membrane electrode and the surface of the titanium fiber felt, reducing the area of ​​the membrane electrode invading the titanium fiber felt, improving the deformation problem of the membrane electrode, and not affecting the normal use of the membrane electrode under the action of pressure difference.

[0012] Specifically, titanium fiber felts with different porosities are prepared in the present application to form a gradient pore structure. At the same time, a template is used to control the pore size, which effectively ensures the formation and maintenance of the gradient pore structure and has a longer service life. On one side of the diffusion layer substrate, i.e., the preferred titanium fiber felt, titanium metal particles with a particle size of 50-60nm are covered on the surface of the titanium fiber felt to form a second particle layer with a porosity of 50%-60%; polystyrene is used as a template to cover the second particle layer with a layer of titanium metal particles with a particle size of 20-50nm to form a first particle layer with a porosity of 30%-40%. On the other side of the titanium fiber felt, a layer of titanium metal particles with a particle size of 200-500nm is covered on the titanium fiber felt to form a third particle layer with a porosity of 70%-80%. It should also be noted that the number of particle layers contained in the first gradient layer and the second gradient layer can be designed according to the membrane electrode structure and requirements of the actual differential pressure electrolyzer. The above only gives the preferred structure.

[0013] Based on the above technical solution, an expanded titanium mesh is arranged on the outer side of the second gradient layer.

[0014] By sintering a layer of expanded titanium mesh on the outside of the second gradient layer, a porous diffusion layer structure that does not require a flow channel, namely, de-flow fielding, is obtained. This can make the fluid distribution more uniform, make the membrane electrode more evenly stressed under the action of differential pressure, enhance the supporting effect of the electrode plate on the membrane electrode, and avoid large deformation of the membrane electrode during use, which may cause damage and affect normal operation.

[0015] Based on the above technical solution, the metal particles filled in the first gradient layer and the second gradient layer are made of the same material as the diffusion layer substrate.

[0016] Based on the above technical solution, the diffusion layer substrate is made of titanium fiber felt, and the metal particles are made of titanium metal particles.

[0017] Preferably, titanium metal particles are used in this application, which have better performance for PEM electrolyzers. Iron, copper and other metal particles are more easily corroded, resulting in metal ions appearing in the water, which will poison the membrane electrode and aggravate the performance degradation of the electrolytic stack.

[0018] On the other hand, the present invention also provides a method for preparing a diffusion layer for a differential pressure proton exchange membrane electrolyzer that prevents membrane electrode deformation, comprising the following steps:

[0019] Step 1: Covering one side of the diffusion layer substrate with a layer of metal particles having a particle size of 50-60 nm to form a second particle layer having a porosity of 50%-60%;

[0020] Step 2: The surface of the second particle layer obtained in step 1 is coated with a layer of metal particles with a particle size of 20-50 nm using polystyrene as a template to form a first particle layer with a porosity of 30%-40%; the first gradient layer is prepared on one side of the diffusion layer substrate;

[0021] Step 3: calcine the structure obtained in step 2 at 200-300°C for 1 hour, and then calcine at 500-600°C for 1 hour to remove the template in step 2.

[0022] Step 4: Coat a layer of metal particles with a particle size of 200-500nm on the other side of the diffusion layer substrate to form a third particle layer with a porosity of 70%-80%; complete the preparation of the second gradient layer on the other side of the diffusion layer substrate; and obtain a diffusion layer structure with gradient pores.

[0023] The present invention also provides a method for preparing the above-mentioned diffusion layer. In the process of preparing the gradient pore structure, a template agent is used as a method of controlling the pores to prepare a titanium fiber felt with gradient pores, which has more precise control over the pores and is particularly suitable for differential pressure PEM electrolyzers to protect the membrane electrode. Accordingly, the first gradient layer and the second gradient layer are prepared in sequence according to the number of particle layers set in the first gradient layer and the second gradient layer.

[0024] Based on the above technical solution, it also includes step five, sintering an expanded titanium mesh on the outside of the second gradient layer to obtain the final gradient pore and flow field-free diffusion layer structure.

[0025] Preferably, an expanded titanium mesh is arranged on the outside of the second gradient layer by sintering, which can form a titanium fiber felt that does not require a flow field, making the fluid distribution more uniform, improving the water vapor diffusion effect and efficiency, and at the same time enhancing the supporting effect of the electrode plate on the membrane electrode and preventing large deformation of the membrane electrode.

[0026] The beneficial effects of the technical solution provided by the present invention are:

[0027] 1. The present invention provides a diffusion layer for a differential pressure proton exchange membrane electrolyzer that prevents membrane electrode deformation. The gradient pore structure is adopted to improve the contact structure between the transmission layer and the bipolar plate, and can provide effective support under the pressure difference formed by the cathode and anode of the membrane electrode, effectively solving the problem that the swelling of the membrane electrode will cause the membrane to enter the titanium fiber felt. While ensuring the transmission of steam and water, the contact area between the membrane electrode and the surface of the titanium fiber felt is increased, the area of ​​the membrane electrode invading the titanium fiber felt is reduced, and the membrane electrode is prevented from being severely deformed or even damaged.

[0028] 2. By sintering a layer of expanded titanium mesh on the outside of the second gradient layer, a porous diffusion layer structure that does not require a flow channel, namely, de-flow fielding, is obtained. This can make the fluid distribution more uniform, make the membrane electrode more evenly stressed under the action of differential pressure, enhance the supporting effect of the electrode plate on the membrane electrode, and avoid large deformation of the membrane electrode during use, causing damage that affects normal operation.

[0029] 3. The present invention also provides a method for preparing the above-mentioned diffusion layer. In the process of preparing the gradient pore structure, a template is used as a method to control the pores to prepare a titanium fiber felt with gradient pores. The pore control is more precise and is particularly suitable for differential pressure PEM electrolyzers to play a role in protecting the membrane electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic diagram of the structure of Embodiment 1 or Embodiment 3 of the present invention;

[0031] Figure 2 is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0032] Figure 3 It is a schematic diagram of the structure in Comparative Example 1 of the present invention;

[0033] Figure 4 It is a schematic diagram of the structure in Comparative Example 2 of the present invention; DETAILED DESCRIPTION

[0034] The following will combine the contents in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not used to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more related listed items. It should be understood that, unless otherwise specified, various raw materials in the present invention can be obtained commercially.

[0036] Example 1

[0037] The present invention provides a diffusion layer for a differential pressure proton exchange membrane electrolyzer that prevents membrane electrode deformation, comprising a diffusion layer substrate 1, a first gradient layer and a second gradient layer, wherein the first gradient layer is provided on one side of the diffusion layer substrate 1, and the second gradient layer is provided on the other side; wherein the first gradient layer comprises a first particle layer 2 and a second particle layer 3 laid out sequentially from top to bottom, and the second gradient layer comprises a third particle layer 4, and a gradient pore structure is formed sequentially between the first gradient layer, the diffusion layer substrate 1 and the second gradient layer. The particle size ranges of the first particle layer 2, the second particle layer 3 and the third particle layer 4 are 20nm, 50nm and 200nm, respectively. The porosity of the first particle layer 2, the second particle layer 3 and the third particle layer 4 are 30%, 50% and 70%, respectively. Specifically, Figure 1 shown.

[0038] The present invention provides a method for preparing a diffusion layer for a differential pressure proton exchange membrane electrolyzer for preventing membrane electrode deformation, comprising the following steps:

[0039] Step 1: Cover one side of the diffusion layer substrate 1 with a layer of metal particles with a particle size of 50 nm to form a second particle layer 3 with a porosity of 50%;

[0040] Step 2: The surface of the second particle layer 3 obtained in step 1 is coated with a layer of metal particles with a particle size of 20 nm using polystyrene 6 as a template to form a first particle layer 2 with a porosity of 30%; the first gradient layer is prepared on one side of the diffusion layer substrate 1;

[0041] Step 3: calcining the structure obtained in step 2 at 200-300°C for 1 hour, and then calcining at 500-600°C for 1 hour to remove the template in step 2;

[0042] Step 4: coating a layer of metal particles with a particle size of 200 nm on the other side of the diffusion layer substrate 1 to form a third particle layer 4 with a porosity of 70%; completing the preparation of the second gradient layer on the other side of the diffusion layer substrate; obtaining a diffusion layer structure with gradient pores;

[0043] Step 5: Sinter an expanded titanium mesh 5 on the outside of the second gradient layer to obtain the final gradient pore and flow field-free diffusion layer structure.

[0044] Example 2

[0045] The present invention provides a diffusion layer for a differential pressure PEM electrolyzer, comprising a diffusion layer substrate 1, a first gradient layer and a second gradient layer, wherein the first gradient layer is provided on one side of the diffusion layer substrate 1, and the second gradient layer is provided on the other side; wherein the first gradient layer comprises a first particle layer 2 and a second particle layer 3 laid out sequentially from top to bottom, and the second gradient layer comprises a third particle layer 4, and a gradient pore structure is formed sequentially between the first gradient layer, the diffusion layer substrate 1 and the second gradient layer. The particle size ranges of the first particle layer 2, the second particle layer 3 and the third particle layer 4 are 30nm, 55nm and 350nm, respectively. The porosity of the first particle layer 2, the second particle layer 3 and the third particle layer 4 are 35%, 55% and 75%, respectively. Specifically, Figure 2 shown.

[0046] The present invention provides a method for preparing a diffusion layer for a differential pressure proton exchange membrane electrolyzer for preventing membrane electrode deformation, comprising the following steps:

[0047] Step 1: Cover one side of the diffusion layer substrate 1 with a layer of metal particles with a particle size of 55 nm to form a second particle layer 3 with a porosity of 55%;

[0048] Step 2: The surface of the second particle layer 3 obtained in step 1 is coated with a layer of metal particles with a particle size of 30 nm using polystyrene 6 as a template to form a first particle layer 2 with a porosity of 35%; the first gradient layer is prepared on one side of the diffusion layer substrate 1;

[0049] Step 3: calcining the structure obtained in step 2 at 200-300°C for 1 hour, and then calcining at 500-600°C for 1 hour to remove the template in step 2;

[0050] Step 4: coating a layer of metal particles with a particle size of 350 nm on the other side of the diffusion layer substrate 1 to form a third particle layer 4 with a porosity of 75%; completing the preparation of the second gradient layer on the other side of the diffusion layer substrate; obtaining a diffusion layer structure with gradient pores;

[0051] Unlike Example 1, a plate with a flow channel is used in this embodiment. Compared with Example 1 of the present application, the design of the flow channel is difficult and needs to consider multiple parameters such as the gas-liquid flow in the flow channel; the manufacturing cost is high, and the bipolar plate with a flow channel needs to be manufactured using a precise processing technology, which is difficult to process; the maintenance cost is high, and regular cleaning and maintenance are required to prevent blockage and corrosion of the flow channel. A diffusion layer for a differential pressure proton exchange membrane electrolyzer that prevents deformation of the membrane electrode provided in the present application does not require a porous diffusion layer structure of a flow channel, i.e., de-flow fielding, which can make the fluid distribution more uniform, make the membrane electrode more evenly stressed under the action of the differential pressure, enhance the supporting role of the plate for the membrane electrode, and avoid large deformation of the membrane electrode during use, causing damage that affects normal operation.

[0052] Example 3

[0053] The present invention provides a diffusion layer for a differential pressure proton exchange membrane electrolyzer that prevents membrane electrode deformation, comprising a diffusion layer substrate 1, a first gradient layer and a second gradient layer, wherein the first gradient layer is provided on one side of the diffusion layer substrate 1 and the second gradient layer is provided on the other side; wherein the first gradient layer comprises a first particle layer 2 and a second particle layer 3 laid out sequentially from top to bottom, and the second gradient layer comprises a third particle layer 4, and a gradient pore structure is formed sequentially between the first gradient layer, the diffusion layer substrate 1 and the second gradient layer. The particle size ranges of the first particle layer 2, the second particle layer 3 and the third particle layer 4 are 50nm, 60nm and 500nm respectively. The porosity of the first particle layer 2, the second particle layer 3 and the third particle layer 4 are 40%, 60% and 80% respectively. Specifically, Figure 1 shown.

[0054] The present invention provides a method for preparing a diffusion layer for a differential pressure proton exchange membrane electrolyzer for preventing membrane electrode deformation, comprising the following steps:

[0055] Step 1: Cover one side of the diffusion layer substrate 1 with a layer of metal particles with a particle size of 60 nm to form a second particle layer 3 with a porosity of 60%;

[0056] Step 2: The surface of the second particle layer 3 obtained in step 1 is coated with a layer of metal particles with a particle size of 50 nm using polystyrene 6 as a template to form a first particle layer 2 with a porosity of 40%; the first gradient layer is prepared on one side of the diffusion layer substrate 1;

[0057] Step 3: calcining the structure obtained in step 2 at 200-300°C for 1 hour, and then calcining at 500-600°C for 1 hour to remove the template in step 2;

[0058] Step 4: coating a layer of metal particles with a particle size of 500 nm on the other side of the diffusion layer substrate 1 to form a third particle layer 4 with a porosity of 80%; completing the preparation of the second gradient layer on the other side of the diffusion layer substrate; obtaining a diffusion layer structure with gradient pores;

[0059] Step 5: Sinter an expanded titanium mesh 5 on the outside of the second gradient layer to obtain the final gradient pore and flow field-free diffusion layer structure.

[0060] Comparative Example 1

[0061] like Figure 3 As shown, in this comparative example, a single layer of titanium particles is sprayed. This method does not use a template, which will cause uneven porosity control and increase mass transfer resistance. Since the pores are controlled by particle diameter, small titanium metal particles are required to obtain small pores. Small titanium metal particles may block the gaps between titanium fibers, affecting gas-liquid transmission and increasing mass transfer resistance. At the same time, expanded titanium mesh is not used, and it needs to be used with a bipolar plate with a flow channel.

[0062] Comparative Example 2

[0063] like Figure 4 As shown, in this comparative example, a simple titanium fiber felt structure is used, compared with the titanium fiber felt mentioned in the present invention, Figure 4 The titanium fiber felt shown in the figure has a large contact resistance when used, which causes performance degradation, titanium fiber intrusion into the membrane electrode, causing damage to the membrane electrode, and uneven gas-liquid transmission, causing increased mass transfer resistance. At the same time, the expanded titanium mesh is not used, and it needs to be used with a bipolar plate with a flow channel.

[0064] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0065] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A diffusion layer for a differential pressure proton exchange membrane electrolyzer for preventing membrane electrode deformation, characterized in that: It comprises a diffusion layer substrate, a first gradient layer, a second gradient layer and an expanded titanium mesh, wherein the first gradient layer is arranged on one side of the diffusion layer substrate and the second gradient layer is arranged on the other side, the first gradient layer comprises at least one metal particle layer, the second gradient layer comprises at least one metal particle layer, a gradient pore structure is formed in sequence between the first gradient layer, the diffusion layer substrate and the second gradient layer, and the expanded titanium mesh is sintered on the outside of the second gradient layer; The first gradient layer includes multiple metal particle layers arranged on the surface of the diffusion layer substrate from top to bottom, and the particle size of each layer of particles increases successively; The multi-layer metal particle layer comprises a first particle layer and a second particle layer sequentially laid from top to bottom, and the particle size of the first particle layer is larger than that of the second particle layer; the second gradient layer comprises a third particle layer, and the particle size of the third particle layer is larger than that of the second particle layer; The porosity of the first particle layer, the second particle layer and the third particle layer are 30%-40%, 50%-60% and 70%-80% respectively.

2. The diffusion layer for a differential pressure proton exchange membrane electrolyzer for preventing membrane electrode deformation according to claim 1, characterized in that: The particle sizes of the first particle layer, the second particle layer and the third particle layer are in the range of 20-50nm, 50-60nm and 200-500nm respectively.

3. The diffusion layer for a differential pressure proton exchange membrane electrolyzer for preventing membrane electrode deformation according to claim 1, characterized in that: An expanded titanium mesh is arranged on the outer side of the second gradient layer.

4. The diffusion layer for a differential pressure proton exchange membrane electrolyzer for preventing membrane electrode deformation according to claim 1, characterized in that: The metal particles filled in the first gradient layer and the second gradient layer are made of the same material as the diffusion layer substrate.

5. The diffusion layer for a differential pressure proton exchange membrane electrolyzer for preventing membrane electrode deformation according to claim 4, characterized in that: The diffusion layer substrate is made of titanium fiber felt, and the metal particles are made of titanium metal particles.

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