Diffusion layer and electrolytic bath

Abstract

The diffusion layer comprises a metal felt layer and a metal particle layer, and the metal particle layer is connected to one side of the metal felt layer in the thickness direction of the electrolytic bath, so that the metal felt layer can conveniently absorb electrolyte in a flow channel through the capillary phenomenon, the flowing of the electrolyte towards the interior of the diffusion layer is accelerated, and the diffusion effect of the electrolytic bath is improved. The gradient structure in the metal particles is matched to improve the use efficiency of the electrolytic cell; wherein the metal particle layers extend in the first direction x and are arranged at intervals in the second direction y, so that a channel is formed between every two adjacent metal particle layers, in the working process of the electrolytic cell, part of the electrolyte can flow in the channels, the pressure intensity in the channels is reduced, and therefore the pressure intensity difference exists between the metal particle layers and the channels; and the gas in the metal particle layer flows and gathers towards the channel through pressure difference, and flows out of the channel under the driving of the electrolyte, so that the gas is discharged by the diffusion layer, and the gas transmission capability of the diffusion layer is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electrolytic cells, and in particular to a diffusion layer and an electrolytic cell. Background Art

[0002] In the internal structure of the electrolyzer, the gas diffusion layer is one of the main components of the electrolyzer. One side of the gas diffusion layer contacts the membrane electrode, and the other side contacts the electrode plate to play the role of transmitting gas and water. During the operation of the electrolyzer, a catalyst is added to promote the reaction. In order to improve the utilization rate of the catalyst, the side of the gas diffusion layer in contact with the membrane electrode is usually made to have a lower roughness to reduce the contact resistance between the two and increase the contact area, thereby achieving an improvement in the utilization rate of the catalyst. However, the lower roughness also makes the pores on the surface of the gas diffusion layer smaller, which makes it difficult for the gas generated during the reaction to be discharged from the inside of the gas diffusion layer, making the gas diffusion layer less capable of transmitting gas. Utility Model Content

[0003] In view of this, the present application provides a diffusion layer and an electrolytic cell to solve the technical problem in the prior art that the gas diffusion layer with smaller surface pores has poor gas transmission capacity.

[0004] The present application provides a diffusion layer for an electrolytic cell, wherein the diffusion layer comprises a metal felt layer and a metal particle layer, wherein the metal particle layer is connected to one side of the metal felt layer along the thickness direction of the electrolytic cell; wherein the metal particle layer extends along a first direction x and is arranged at intervals along a second direction y so that a channel is provided between two adjacent metal particle layers.

[0005] In the embodiment of the present application, the metal particle layer is connected to one side of the metal felt layer along the thickness direction of the electrolytic cell to refine the pores on the surface of the diffusion layer and reduce the surface roughness of the diffusion layer, and the metal particle layer can extend along the first direction x and be arranged at intervals along the second direction y, so that the interval between two adjacent metal particle layers can form a channel. During the assembly of the electrolytic cell, along the thickness direction of the electrolytic cell, the metal felt layer of the diffusion layer can abut against the electrode plate of the electrolytic cell, and the metal particle layer can abut against the membrane electrode of the electrolytic cell, wherein electrolyte flows in the electrode plate, and part of the electrolyte can diffuse into the interior of the diffusion layer and generate gas at the membrane electrode. Specifically, during the operation of the electrolytic cell, the electrolyte can flow in the electrode plate along the first direction x, and part of the electrolyte can penetrate into the diffusion layer and flow in the channel along the first direction x, and generate gas through reaction during the flow. Since part of the electrolyte flows in the first direction x in the channel, the pressure in the channel is reduced, so that there is a pressure difference between the metal particle layer and the channel, and then the gas in the metal particle layer can flow into the channel and gather in the channel through the pressure difference between the metal particle layer and the channel, and flow out of the channel together under the drive of the electrolyte, thereby realizing the discharge of gas by the diffusion layer.

[0006] Therefore, the diffusion layer in the present application can increase the flow rate of the electrolyte and gas in the diffusion layer through the channel, thereby improving the ability of the diffusion layer to transmit gas. At the same time, the metal particle layer can refine the pores on the surface of the diffusion layer to reduce the surface roughness of the diffusion layer, thereby reducing the contact resistance between the diffusion layer and the membrane electrode, which is beneficial to improving the utilization rate of the catalyst at the membrane electrode, and then can improve the working efficiency of the electrolyzer and optimize the working performance of the electrolyzer.

[0007] In a possible implementation, the channel is in a straight line or a curve shape.

[0008] In a possible implementation manner, the channel includes an inlet and an outlet, and a flow cross-sectional area of ​​the inlet is smaller than a flow cross-sectional area of ​​the outlet.

[0009] In a possible implementation manner, each of the metal particle layers is evenly distributed along the second direction y.

[0010] In a possible implementation, the metal particle layer includes at least a first metal particle layer and a second metal particle layer, the first metal particle layer is composed of a plurality of first metal particles, the second metal particle layer is composed of a plurality of second metal particles, and along the thickness direction of the electrolytic cell, the first metal particle layer is located between the metal felt layer and the second metal particle layer;

[0011] There is a first gap between adjacent first metal particles, and there is a second gap between adjacent second metal particles, and the first gap is larger than the second gap.

[0012] In a possible implementation manner, the center distance between two adjacent second metal particles is L1, and L1 satisfies L1<15 μm, and the second gap is L2, and L2 satisfies L2<5 μm.

[0013] In a possible implementation manner, the diameter of the first metal particle is D1, and D1 satisfies 40 μm≤D1≤70 μm, and the diameter of the second metal particle is D2, and D2 satisfies 10 μm≤D2≤30 μm.

[0014] In a possible implementation manner, the thickness of the first metal particle layer is H1, and H1 satisfies 0.1 mm≤H1≤0.2 mm, and the thickness of the second metal particle layer is H2, and H2 satisfies 0.01 mm≤H2≤0.1 mm.

[0015] In a possible implementation manner, the metal felt layer has a third gap, the third gap is larger than the first gap, and the third gap gradually decreases along the thickness direction of the electrolytic cell.

[0016] In a possible implementation manner, the metal particle layer is formed on the metal felt layer by screen printing.

[0017] The present application also provides an electrolytic cell, which includes a membrane electrode, a diffusion layer and an electrode plate, wherein the diffusion layer is the diffusion layer described above, and the electrode plate has at least one flow channel; wherein, along the thickness direction of the electrolytic cell, the diffusion layer is located between the membrane electrode and the electrode plate, and the electrode plate is located on the side of the metal felt layer away from the membrane electrode.

[0018] In the embodiment of the present application, along the thickness direction of the electrolytic cell, the diffusion layer is located between the membrane electrode and the electrode plate, and the electrode plate is located on the side of the metal felt layer away from the membrane electrode, so that the metal felt layer can absorb the electrolyte in the flow channel through capillary phenomenon to accelerate the flow of the electrolyte to the inside of the diffusion layer, and cooperate with the gradient structure in the metal particle layer to improve the efficiency of the electrolytic cell. In addition, by arranging the metal particle layer and the channel on the surface of the metal felt layer, not only can the gas transmission capacity of the diffusion layer be improved, but also the compression of the diffusion layer by the membrane electrode and the electrode plate can be reduced, thereby improving the overall structural strength of the diffusion layer.

[0019] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 This is a schematic diagram of the diffusion layer and membrane electrode structure provided in this application;

[0022] Figure 2 for Figure 1 Schematic diagram of the structure of the middle diffusion layer;

[0023] Figure 3 This is a schematic structural diagram of the diffusion layer provided in the present application in the first embodiment;

[0024] Figure 4 This is a schematic structural diagram of the diffusion layer provided in the present application in the second embodiment;

[0025] Figure 5 This is a schematic structural diagram of the diffusion layer provided in the present application in the third embodiment.

[0026] Description of reference numerals:

[0027] 1-Diffusion layer;

[0028] 11-metal felt layer;

[0029] 12-metal particle layer;

[0030] 121- first metal particle layer;

[0031] 121a-first metal particles;

[0032] 122- second metal particle layer;

[0033] 122a - second metal particles;

[0034] 13- channel;

[0035] 131-Import;

[0036] 132-Exit;

[0037] 2-Membrane electrode.

[0038] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. DETAILED DESCRIPTION

[0039] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0040] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0041] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0042] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0043] The embodiment of the present application provides a diffusion layer for an electrolytic cell, such as Figure 1 , Figure 2 and Figure 3 As shown, the diffusion layer 1 includes a metal felt layer 11 and a metal particle layer 12. Along the thickness direction of the electrolytic cell, the metal particle layer 12 is connected to one side of the metal felt layer 11. The metal particle layers 12 extend along a first direction x and are arranged at intervals along a second direction y, so that a channel 13 is provided between two adjacent metal particle layers 12.

[0044] In the embodiment of the present application, the metal particle layer 12 is connected to one side of the metal felt layer 11 along the thickness direction of the electrolytic cell to refine the pores on the surface of the diffusion layer 1 and reduce the surface roughness of the diffusion layer 1, and the metal particle layer 12 can extend along the first direction x and be arranged at intervals along the second direction y, so that the interval between two adjacent metal particle layers 12 can form a channel 13. During the assembly of the electrolytic cell, along the thickness direction of the electrolytic cell, the metal felt layer 11 of the diffusion layer 1 can abut against the electrode plate of the electrolytic cell, and the metal particle layer 12 can abut against the membrane electrode 2 of the electrolytic cell, wherein electrolyte flows in the electrode plate, and part of the electrolyte can diffuse into the inside of the diffusion layer 1 and generate gas at the membrane electrode 2. Specifically, during the operation of the electrolytic cell, the electrolyte can flow in the electrode plate along the first direction x, and part of the electrolyte can penetrate into the diffusion layer 1 and flow in the channel 13 along the first direction x, and generate gas through reaction during the flow. Since part of the electrolyte flows in the first direction x in the channel 13, the pressure in the channel 13 is reduced, so that there is a pressure difference between the metal particle layer 12 and the channel 13, and then the gas in the metal particle layer 12 can flow into the channel 13 and gather in the channel 13 through the pressure difference between the metal particle layer 12 and the channel 13, and flow out of the channel 13 together driven by the electrolyte, thereby realizing the gas discharge by the diffusion layer 1.

[0045] Therefore, the diffusion layer 1 in the present application can increase the flow rate of the electrolyte and gas in the diffusion layer 1 through the channel 13, thereby improving the gas transmission capacity of the diffusion layer 1. At the same time, the metal particle layer 12 can refine the pores on the surface of the diffusion layer 1 to reduce the surface roughness of the diffusion layer 1, thereby reducing the contact resistance between the diffusion layer 1 and the membrane electrode 2, which is beneficial to improving the utilization rate of the catalyst at the membrane electrode 2, and then can improve the working efficiency of the electrolytic cell and optimize the working performance of the electrolytic cell.

[0046] In a specific embodiment, Figure 3 and Figure 4 As shown, the shape of the channel 13 can be straight or curved.

[0047] In the embodiment of the present application, along the thickness direction of the electrolytic cell, the diffusion layer 1 is located between the electrode plate of the electrolytic cell and the membrane electrode 2 of the electrolytic cell. In order to further improve the flow effect of the fluid in the electrolytic cell, the shape of the channel 13 can be set to a straight line or a curve, that is, the shape of the channel 13 is the same as the shape of the electrode plate flow channel, so that during the assembly of the electrolytic cell, the projection of the channel 13 and the projection of the electrode plate flow channel can overlap along the thickness direction of the electrolytic cell.

[0048] Specifically, when the channel 13 overlaps with the electrode plate flow channel in the thickness direction of the electrolytic cell, it is convenient for the electrolyte in the electrode plate flow channel to flow into the channel 13, reducing the process of the electrolyte flowing from the electrode plate flow channel into the metal particle layer 12 and then flowing from the metal particle layer 12 to the channel 13, which is conducive to improving the flow efficiency and reaction efficiency of the electrolyte, so that the gas can be generated and discharged from the diffusion layer 1 faster, so that the diffusion layer 1 has a better gas transmission capacity. Among them, when the shape of the channel 13 is a straight line, the uniformity of the fluid flowing in the channel 13 is high, which is conducive to improving the flow speed of the fluid; when the shape of the channel 13 is a curve, the pressure drop of the channel 13 is small, which is conducive to the rapid discharge of the gas and improves the gas transmission capacity of the diffusion layer 1. At the same time, the curved channel 13 also allows the electrolyte to have a longer flow distance and a longer flow time, so that the electrolyte can fully react, which is conducive to improving the working efficiency of the electrolytic cell.

[0049] In a specific embodiment, Figure 5 As shown, the channel 13 includes an inlet 131 and an outlet 132 , and the flow cross-sectional area of ​​the inlet 131 is smaller than the flow cross-sectional area of ​​the outlet 132 .

[0050] In the embodiment of the present application, along the first direction x (i.e., along the direction from the inlet 131 toward the outlet 132), the flow cross-sectional area of ​​the channel 13 can be gradually increased, so that after the electrolyte flows into the channel 13, the flow velocity of the electrolyte can be reduced, so as to increase the flow time of the electrolyte in the channel 13, so that the reaction is more complete. At the same time, the sufficient reaction of the electrolyte will also increase the amount of gas generated, and the outlet 132 with a larger flow cross-sectional area can facilitate the discharge of a large amount of gas, which is beneficial to improving the exhaust efficiency of the diffusion layer 1, thereby further improving the working efficiency of the electrolytic cell.

[0051] In a specific embodiment, Figure 1 and Figure 3 As shown, each metal particle layer 12 is evenly distributed along the second direction y.

[0052] In the embodiment of the present application, since a channel 13 is formed between two adjacent metal particle layers 12, the uniform distribution of each metal particle layer 12 along the second direction y can make the space size in each channel 13 equal, and each channel 13 is parallel to each other along the second direction y, so that the distribution of the electrolyte at the inlet 131 of each channel 13 is more uniform, which is beneficial to improving the uniformity of the reaction and reducing the difference in gas content between different channels 13, thereby allowing the diffusion layer 1 to discharge the gas more smoothly.

[0053] In a specific embodiment, Figure 1 and Figure 2As shown, the metal particle layer 12 at least includes a first metal particle layer 121 and a second metal particle layer 122 . The first metal particle layer 121 is composed of a plurality of first metal particles 121 a , and the second metal particle layer 122 is composed of a plurality of second metal particles 122 a .

[0054] In the embodiment of the present application, in the metal particle layer 12, adjacent metal particles are partially abutted so that there are gaps between adjacent metal particles, thereby ensuring the smoothness of gas flow in each metal particle layer 12, reducing the possibility that the diffusion layer 1 has a weak gas transmission capacity, and at the same time improving the strength of each metal particle layer 12. Specifically, the first metal particle 121a and the second metal particle 122a can both be spherical. When a plurality of metal particles are connected together, compared with metal particles of other shapes, the phenomenon of gap disappearance caused by close fit between adjacent metal particles can be avoided, ensuring that gas can flow in the metal particle layer 12, and reducing the risk of too low gas transmission capacity of the diffusion layer 1 due to the disappearance of gaps.

[0055] Among them, along the thickness direction of the electrolytic cell, the first metal particle layer 121 is located between the metal felt layer 11 and the second metal particle layer 122, there is a first gap between adjacent first metal particles 121a, there is a second gap between adjacent second metal particles 122a, and the first gap is larger than the second gap. In the process of preparing the metal particle layer 12, along the thickness direction of the electrolytic cell, the first metal particle layer 121 covers the side of the metal felt layer 11 facing the membrane electrode 2, and the second metal particle layer 122 covers the side of the first metal particle layer 121 away from the metal felt layer 11, so that the surface pores of the metal felt layer 11 are refined by the metal particle layer 12, and in the direction from the first metal particle layer 121 to the second metal particle layer 122, the overall pores of the metal particle layer 12 are gradually reduced, so as to improve the efficiency of the electrolyte diffusion into the diffusion layer 1 through the capillary phenomenon, thereby facilitating the diffusion layer 1 to absorb the electrolyte.

[0056] In a specific embodiment, Figure 2 As shown, the center distance between two adjacent second metal particles 122 a is L1, and L1 satisfies L1<15 μm, and the second gap is L2, and L2 satisfies L2<5 μm.

[0057] In the embodiment of the present application, the center distance L1 between two adjacent second metal particles 122a can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, etc.

[0058] When the center distance between two adjacent second metal particles 122a is too large (for example, L1 is greater than 15μm), the flatness of the surface of the second metal particle layer 122 is low, which makes the surface roughness of the diffusion layer 1 high, easily resulting in a reduction in the contact area between the diffusion layer 1 and the membrane electrode 2, thereby reducing the stability and reliability of the connection between the two.

[0059] Therefore, when the center distance between two adjacent second metal particles 122a satisfies L1<15μm, the center distance between two adjacent second metal particles 122a is moderate, and the surface of the second metal particle layer 122 is relatively flat, so that the surface roughness of the diffusion layer 1 is low, which is beneficial to increase the contact area between the diffusion layer 1 and the membrane electrode 2, thereby improving the utilization rate of the catalyst on the membrane electrode 2.

[0060] Meanwhile, the second gap L2 may specifically be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 4.9 μm, etc.

[0061] When the second gap is too large (eg L2 is greater than 5 μm), the pores of the second metal particle layer 122 are too large, resulting in poor filtering performance of the diffusion layer 1, which may easily cause external impurities to be transmitted along with the gas, thus causing negative impacts on the inside of the electrolytic cell.

[0062] Therefore, when the second gap satisfies L2<5 μm, the pores of the second metal particle layer 122 are smaller, so as to solve the negative impact caused by the invasion of external impurities into the electrolytic cell.

[0063] In a specific embodiment, Figure 2 As shown, the diameter of the first metal particle 121 a is D1, and D1 satisfies 40 μm≤D1≤70 μm, and the diameter of the second metal particle 122 a is D2, and D2 satisfies 10 μm≤D2≤30 μm.

[0064] In the embodiment of the present application, the diameter D1 of the first metal particle 121a can be 40μm, 43μm, 45μm, 47μm, 50μm, 53μm, 55μm, 57μm, 60μm, 63μm, 65μm, 67μm, 70μm, etc.

[0065] When the diameter of the first metal particle 121a is too small (for example, D1 is less than 40 μm), after multiple first metal particles 121a abut against each other, the first gap of the first metal particle layer 121 is too small, which is not conducive to the flow of gas, and the first metal particles 121a with too small diameter are not easy to adhere to the metal felt layer 11, so that the first metal particles 121a are at risk of falling into the metal felt layer 11, thereby causing the second metal particles 122a to fail to form smoothly on the first metal particle layer 121.

[0066] When the diameter of the first metal particle 121a is too large (for example, D1 is greater than 70 μm), after multiple first metal particles 121a abut against each other, the first gap of the first metal particle layer 121 is too large, making it impossible to form an effective capillary phenomenon between the first metal particles 121a and the metal felt layer 11, resulting in a low absorption efficiency of the diffusion layer 1 for the electrolyte.

[0067] Therefore, when the diameter of the first metal particle 121a satisfies 40μm≤D1≤70μm, the diameter of the first metal particle 121a is moderate, the size of the pores of the first metal particle layer 121 is moderate, and in the process of preparing the first metal particle layer 121, the first metal particle layer 121 can be formed on the surface of the metal felt layer 11 to refine the pores on the surface of the metal felt layer 11.

[0068] Meanwhile, the diameter D2 of the second metal particles 122 a may be 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, etc.

[0069] When the diameter of the second metal particle 122a is too small (for example, D2 is less than 10 μm), after multiple second metal particles 122a abut against each other, the second gap of the second metal particle layer 122 is too small, making it difficult for the gas to flow in the second metal particle layer 122, resulting in poor gas transmission ability of the diffusion layer 1.

[0070] When the diameter of the second metal particle 122a is too large (for example, D2 is greater than 30 μm), after multiple second metal particles 122a abut against each other, the second gap of the second metal particle layer 122 is too large, resulting in poor filtering performance of the diffusion layer 1, which can easily cause external impurities to be transmitted along with the gas, thereby causing negative impacts on the inside of the electrolytic cell.

[0071] Therefore, when the diameter of the second metal particle 122a satisfies 10μm≤D2≤30μm, the diameter of the second metal particle 122a is moderate and the size of the pores in the second metal particle layer 122 is moderate, so that the diffusion layer 1 has a better gas transmission capability while avoiding the possibility of negative impact caused by external impurities invading the interior of the electrolytic cell.

[0072] In a specific embodiment, Figure 2 As shown, the thickness of the first metal particle layer 121 is H1, and H1 satisfies 0.1 mm≤H1≤0.2 mm, and the thickness of the second metal particle layer 122 is H2, and H2 satisfies 0.01 mm≤H2≤0.1 mm.

[0073] In the embodiment of the present application, the thickness H1 of the first metal particle layer 121 can be 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, etc.

[0074] When the thickness of the first metal particle layer 121 is too small (for example, H1 is less than 0.1 mm), the first metal particle layer 121 is too thin, so that the mechanical strength of the first metal particle layer 121 is low and it is easy to be damaged.

[0075] When the thickness of the first metal particle layer 121 is too large (for example, H1 is greater than 0.2 mm), the first metal particle layer 121 is too thick, so that the thickness of the entire metal particle layer 12 increases, which is not conducive to the flow of gas in the diffusion layer 1 .

[0076] Therefore, when the thickness of the first metal particle layer 121 satisfies 0.1mm≤H1≤0.2mm, the thickness of the first metal particle layer 121 is moderate, so that the first metal particle layer 121 has good mechanical strength, and the diffusion layer 1 has good transmission capability. At the same time, it can form a gradient gap with the metal felt layer 11 along the thickness direction of the electrolytic cell, which is beneficial to further improve the transmission efficiency of the electrolyte and gas in the diffusion layer 1.

[0077] Meanwhile, the thickness H2 of the second metal particle layer 122 may be 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, etc.

[0078] When the thickness of the second metal particle layer 122 is too small (for example, H2 is less than 0.01 mm), the second metal particle layer 122 is too thin, so that the mechanical strength of the second metal particle layer 122 is low and it is easy to be damaged.

[0079] When the thickness of the second metal particle layer 122 is too large (for example, H2 is greater than 0.1 mm), the second metal particle layer 122 is too thick, so that the thickness of the entire metal particle layer 12 increases, which is not conducive to the flow of gas in the diffusion layer 1 .

[0080] Therefore, when the thickness of the second metal particle layer 122 satisfies 0.01mm≤H2≤0.1mm, the thickness of the second metal particle layer 122 is moderate, so that the second metal particle layer 122 has good mechanical strength, and the diffusion layer 1 has good transmission capability. At the same time, it can form a gradient gap with the first metal particle layer 121 along the thickness direction of the electrolytic cell, which is beneficial to further improve the transmission efficiency of the electrolyte and gas in the diffusion layer 1.

[0081] In a specific embodiment, Figure 1 and Figure 2 As shown, the metal felt layer 11 has a third gap, which is larger than the first gap, and the third gap gradually decreases along the thickness direction of the electrolytic cell.

[0082] In the embodiment of the present application, the third gap of the metal felt layer 11 is larger than the first gap of the first metal particle layer 121, that is, the gap inside the metal felt layer 11 is larger than the gap between adjacent metal particles in the metal particle layer 12, so that the electrolyte can diffuse along the metal felt layer 11 toward the metal particle layer 12 under the action of capillary phenomenon. And because the gap inside the metal felt layer 11 is larger than the gap between adjacent metal particles in the metal particle layer 12, the ions generated after the electrolyte reaction can increase the flow speed of the ions at the junction of the metal felt layer 11 and the metal particle layer 12, thereby promoting the efficiency of ions generating gas at the membrane electrode 2.

[0083] Specifically, along the direction from the metal felt layer 11 to the metal particle layer 12, the third gap of the metal felt layer 11 gradually decreases, so that the interior of the diffusion layer 1 forms a gradient structure along the thickness direction of the electrolytic cell, further promoting the effect of capillary phenomenon, improving the efficiency of electrolyte transmission into the diffusion layer 1, and improving the diffusion layer 1's electrolyte transportation efficiency and gas discharge efficiency.

[0084] In a specific embodiment, the metal particle layer 12 is formed on the metal felt layer 11 by screen printing.

[0085] In the embodiment of the present application, screen printing has the characteristic of easy configuration, and the screen printing method is not limited by the size and shape of the substrate, which reduces the difficulty of preparing the metal particle layer 12 on the metal felt layer 11, thereby facilitating the improvement of the preparation efficiency of the metal particle layer 12, and further improving the production efficiency of the diffusion layer 1. At the same time, the screen in screen printing is soft and elastic, which can reduce the damage to the metal felt layer 11 during the printing process, so as to improve the yield of the production diffusion layer 1. In addition, the cost of screen printing is low and easy to control, which is more in line with actual usage requirements.

[0086] Specifically, in the process of preparing the metal particle layer 12, the first metal particles 121a are first mixed with a slurry to form a first mixture, and then the first mixture is printed on one side of the metal felt layer 11 through a printing screen so that the first mixture adheres to the surface of the metal felt layer 11, and then the moisture in the first mixture is removed by drying. At this time, the multiple first metal particles 121a in the first mixture are bonded together by glue, and the volume of the glue accounts for 30%-40% of the first mixture.

[0087] Secondly, the second metal particles 122a are mixed with the slurry to form a second mixture, and then the second mixture is printed on the side of the first mixture away from the metal felt layer 11 through a printing screen so that the second mixture adheres to the surface of the first mixture, and then the moisture in the second mixture is removed by drying. At this time, the multiple second metal particles 122a in the second mixture are bonded together by glue, and the volume of the glue accounts for 40%-50% of the second mixture.

[0088] Finally, the glue in the first mixture and the second mixture is removed by high-temperature sintering to ensure that the multiple first metal particles 121a are solid-phase connected, the multiple second metal particles 122a are solid-phase connected, and the first metal particle layer 121 and the second metal particle layer 122 are solid-phase connected, thereby forming a metal particle layer 12, completing the preparation of the metal particle layer 12 on the metal felt layer 11.

[0089] Therefore, through the preparation method of screen printing, the metal particles can be attached to the surface of the metal felt layer 11 more conveniently and quickly, and the attached metal particles can present a preset structure and have a higher structural stability, which effectively reduces the difficulty in shaping the metal particles and makes it easier to form the metal particle layer 12 through subsequent sintering.

[0090] The present application also provides an electrolytic cell, which includes a diffusion layer 1, a membrane electrode 2 and a plate. The plate has at least one flow channel for circulating electrolyte. Along the thickness direction of the electrolytic cell, the diffusion layer 1 is located between the membrane electrode 2 and the plate, and the plate is located on the side of the metal felt layer 11 away from the membrane electrode 2, so that the metal felt layer 11 can absorb the electrolyte in the flow channel through capillary phenomenon to accelerate the flow of electrolyte to the inside of the diffusion layer 1, and cooperate with the gradient structure in the metal particle layer 12 to improve the efficiency of the electrolytic cell. In addition, by arranging the metal particle layer 12 and the channel 13 on the surface of the metal felt layer 11, not only can the gas transmission capacity of the diffusion layer 1 be improved, but also the compression of the diffusion layer 1 by the membrane electrode 2 and the plate can be reduced, thereby improving the overall structural strength of the diffusion layer 1.

[0091] The above describes in detail the structure, features and effects of the present application based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present application, but the present application does not limit the scope of implementation to what is shown in the drawings. Any changes made in accordance with the concept of the present application, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the protection scope of the present application.

Claims

1. A diffusion layer for an electrolytic cell, characterized in that: The diffusion layer (1) comprises a metal felt layer (11) and a metal particle layer (12), and along the thickness direction of the electrolytic cell, the metal particle layer (12) is connected to one side of the metal felt layer (11); The metal particle layers (12) extend along a first direction x and are arranged at intervals along a second direction y, so that a channel (13) is provided between two adjacent metal particle layers (12).

2. The diffusion layer according to claim 1, characterized in that The shape of the channel (13) is straight or curved.

3. The diffusion layer according to claim 1, characterized in that The channel (13) comprises an inlet (131) and an outlet (132), and a flow cross-sectional area of ​​the inlet (131) is smaller than a flow cross-sectional area of ​​the outlet (132).

4. The diffusion layer according to claim 1, characterized in that Each of the metal particle layers (12) is evenly distributed along the second direction y.

5. The diffusion layer according to any one of claims 1 to 4, characterized in that: The metal particle layer (12) comprises at least a first metal particle layer (121) and a second metal particle layer (122), wherein the first metal particle layer (121) is composed of a plurality of first metal particles (121a), and the second metal particle layer (122) is composed of a plurality of second metal particles (122a), and along the thickness direction of the electrolytic cell, the first metal particle layer (121) is located between the metal felt layer (11) and the second metal particle layer (122); There is a first gap between adjacent first metal particles (121a), and there is a second gap between adjacent second metal particles (122a), and the first gap is larger than the second gap.

6. The diffusion layer according to claim 5, characterized in that The center distance between two adjacent second metal particles (122a) is L1, and L1 satisfies L1<15μm, and the second gap is L2, and L2 satisfies L2<5μm.

7. The diffusion layer according to claim 5, characterized in that The diameter of the first metal particle (121a) is D1, and D1 satisfies 40μm≤D1≤70μm, and the diameter of the second metal particle (122a) is D2, and D2 satisfies 10μm≤D2≤30μm.

8. The diffusion layer according to claim 5, characterized in that The thickness of the first metal particle layer (121) is H1, and H1 satisfies 0.1 mm≤H1≤0.2 mm; the thickness of the second metal particle layer (122) is H2, and H2 satisfies 0.01 mm≤H2≤0.1 mm.

9. The diffusion layer according to claim 5, characterized in that: The metal felt layer (11) has a third gap, the third gap is larger than the first gap, and the third gap gradually decreases along the thickness direction of the electrolytic cell.

10. The diffusion layer according to claim 5, characterized in that The metal particle layer (12) is formed on the metal felt layer (11) by screen printing.

11. An electrolytic cell, characterized in that: The electrolytic cell comprises: Membrane electrode (2); A diffusion layer (1), wherein the diffusion layer (1) is the diffusion layer (1) according to any one of claims 1 to 10; A plate having at least one flow channel; Wherein, along the thickness direction of the electrolytic cell, the diffusion layer (1) is located between the membrane electrode (2) and the electrode plate, and the electrode plate is located on the side of the metal felt layer (11) away from the membrane electrode (2).

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