Gas diffusion layer and its manufacturing method

Abstract

The present invention discloses a gas diffusion layer and a manufacturing method thereof. The method includes the steps of: step S1, processing a long groove on one side of a metal sheet; step S2, cutting the metal sheet with the long groove into a desired shape; step S3, stacking the metal sheets cut into a few blocks, tightly connecting the adjacent metal sheets to form a metal block with a regular pore structure inside; step S4, cutting the metal block along its cross section, adjusting the cut thickness to the required thickness of the gas diffusion layer, and forming a sheet structure with regular micropores on the cut surface to form a gas diffusion layer. The present invention can solve the problems of the poor flow-guiding effect, low contact efficiency, and high resistance of the contact surface of the conventional titanium fiber felt plate.

Description

[Technical field]

[0001] The present invention relates to the field of water electrolysis hydrogen production, and more particularly to a gas diffusion layer and a method for manufacturing the same. [Background technology]

[0002] Electrolytic hydrogen production is considered a new energy storage method, and is also one of the methods that can process renewable energy on a large scale, and has been unanimously recognized worldwide. Electrolytic hydrogen production methods are mainly divided into traditional alkaline water electrolysis hydrogen production and the emerging solid electrolyte (SPE) water electrolysis hydrogen production, and SPE water electrolysis hydrogen production has the advantages of high efficiency, compact equipment, quick start-stop, no pollution, and high purity hydrogen production, and is therefore competitive in the scene of processing new energy power generation with extremely high variability. The main components of an SPE electrolyzer include bipolar plates, gas diffusion layers (cathode and anode), and membrane electrodes. The main functions of the gas diffusion layers are to support and protect the membrane electrodes, conduct electricity, and conduct gas and liquid. During the water electrolysis reaction process, strong oxidation occurs due to the anode oxygen generation reaction, so the gas diffusion layers and bipolar plates of SPE electrolyzers are often made of titanium metal material. Conventional gas diffusion layers for SPE electrolyzers mainly use titanium fiber felt plates, which have the following problems as gas diffusion layers: 1. Titanium fiber felt plate is made by stacking and connecting titanium fibers and then sintering them, which causes the internal voids to become disordered and results in poor flow guidance. 2. The surface microstructure of the titanium fiber felt plate is also disordered, and the contact efficiency at the interface with the membrane electrode is not high, and the resistance of the contact surface is large, which affects the efficiency of the electrolysis water reaction. To solve the above problems, a new gas diffusion layer with a flat surface and regular pores is needed to meet the requirements of contact efficiency and flow conducting efficiency. Summary of the Invention

[0003] The present invention provides a gas diffusion layer and a manufacturing method thereof, which solves the problems of the poor flow-guiding effect, low contact efficiency, and high contact surface resistance of the conventional titanium fiber felt plate. In order to achieve the above object, according to a first aspect, an embodiment of the present application provides the following technical means, and in a method for manufacturing a gas diffusion layer, Step S1: machining a long groove in a row on one side of a metal sheet; Step S2: cutting the elongated thin metal plate having the groove formed in step S1 into a desired shape; Step S3: overlapping the thin metal sheets cut in step S2 into some blocks, and tightly connecting the adjacent thin metal sheets to each other to form a metal block having a regular pore structure therein; Step S4 includes a step of cutting the metal block from step S3 along its cross section, adjusting the cut thickness to a required thickness of the gas diffusion layer, and forming a sheet structure having regularly spaced micropores on the cut surface to form a gas diffusion layer. Preferably, in step S1, Step S11, making a printing roll: A step of engraving grooves arranged in a horizontal row on a printing roll having a smooth surface; Step S12 includes a step of roll-pressing the metal sheet using the printing roll produced in step S11, and processing one side of the metal sheet into elongated grooves aligned in a horizontal row. Preferably, the grooves on the printing roll are arranged in a single horizontal row along the axial or circumferential direction of the printing roll. Preferably, in step S1, the elongated groove on the surface of the thin metal plate is formed by laser processing, etching processing, ultrasonic electric engraving processing, or electric discharge processing. Preferably, the metal sheet is made of titanium metal or a titanium alloy. Preferably, after step S4, the gas diffusion layer is subjected to a surface coating treatment, and the surface coating treatment further includes passivation antiseptic treatment and hydrophilic treatment. According to a second aspect, in an embodiment of the present application, the gas diffusion layer is obtained by manufacturing the gas diffusion layer according to the manufacturing method according to the first aspect. Compared with the prior art, the present invention has the following advantages: A completely new manufacturing method is used to manufacture a gas diffusion layer with high manufacturing efficiency, flat surface, and regularly arranged flow-through holes, which has better contact with the membrane electrode, reduces the resistance of the contact surface, and improves the electrolysis efficiency. The flow-through efficiency of gas and liquid can be maximized. Therefore, this application is an important innovation on the irregular internal pore structure of the gas diffusion layer for the conventional SPE electrolyzer, which greatly improves the flow-through effect of the gas diffusion layer to the fluid, and also improves the contact efficiency between the gas diffusion layer and the membrane electrode. [Brief description of the drawings]

[0004] FIG. 1 is a flow chart of the manufacturing method of the present invention. FIG. 2 is a diagram showing the overlapping of metal thin plates in step S3 in the manufacturing method of the present invention. FIG. 3 is a diagram showing the metal block formed in step S3 in the manufacturing method of the present invention. FIG. 4 is a schematic diagram of an embodiment of the gas diffusion layer of the present invention. FIG. 5 is a schematic diagram showing the configuration of another embodiment of the gas diffusion layer of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] Hereinafter, the technical means in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention. In order to achieve the above object, the present invention solves the problems of the poor current conducting effect, low contact efficiency, and high contact surface resistance of the conventional titanium fiber felt plate. The present invention provides the following technical means: EXAMPLES

[0006] As shown in FIG. 1, in the method for producing a gas diffusion layer, Step S1: process a horizontal row of elongated grooves on one side of a metal sheet, the elongated grooves are used to form micropores on the gas diffusion layer, the gas diffusion layer has an important index, namely porosity, that is, the ratio of the area of ​​micropores to the area of ​​the gas diffusion layer, the dimensions of the elongated grooves and the thickness of the metal sheet both affect the porosity of the gas diffusion layer, the depth of the elongated groove is a, the width of the elongated groove is b, the distance between adjacent elongated grooves is c, and the total thickness of the metal sheet is d, and by setting the ratio of these four parameters, a gas diffusion layer with a certain porosity can be obtained, for example, when a:b:c:d=1:1:1:2, the final porosity of the gas diffusion layer is 25%. The four parameters can also be set as a:b:c:d=1:2:2:4, and the final porosity of the gas diffusion layer is 12.5%. Furthermore, when the four parameters are set to a:b:c:d=1:1:2:2, the gas diffusion layer has a final porosity of 12.5%. In this embodiment, the cross-sectional shape of the elongated groove has various options, and can be preferably designed to be rectangular or square, or to be semicircular, triangular, trapezoidal, etc. Those skilled in the art can select different shapes of the elongated groove according to the specific application requirements of the gas diffusion layer. In this embodiment, the present application provides a highly efficient method for forming long grooves, specifically, first, grooves arranged in a row are engraved on a plate roll with a smooth surface, and then a metal sheet is roll-pressed using the plate roll that has been manufactured to process long grooves arranged in a row on one side of the metal sheet. Here, the grooves on the plate roll are for forming beams between the long grooves, and by attaching a plate roll that engraves a pattern on the surface to a press roll machine, the metal sheet is roll-pressed to complete the formation of many long grooves at one time. Here, the grooves on the printing roll are arranged in a single horizontal row along the axial or circumferential direction of the printing roll, and in either case, the formation of the long grooves can be completed by roll pressing. Of course, in the actual process of use, there are still many ways to form a long groove on a metal sheet, such as laser processing, etching processing, ultrasonic electric engraving processing, or electric discharge processing, and those skilled in the art can choose one according to their needs. In this embodiment, the metal sheet is preferably made of titanium metal or titanium alloy, although those skilled in the art may use other metal materials or alloy materials with good corrosion resistance. In step S2, the metal sheet having the long groove formed in step S1 is cut into a desired shape, for example, a rectangle having a size of 200 mm x 500 mm, and there are many methods for cutting, for example, punching with an edge trimmer or using wire cutting. In step S3, as shown in FIG. 2-FIG. 3, the metal sheets cut in step S2 are overlapped into a few blocks, and the number of overlapping metal sheets can be adjusted according to the requirements of the gas diffusion layer. Adjacent metal sheets are tightly attached to each other to connect them firmly, specifically, the beam with the long groove formed in the lower metal sheet and the smooth back surface of the upper metal sheet are tightly attached to each other, and the metal sheets are tightly connected together using a high-temperature welding process. A metal block having a regular pore structure therein, for example, a metal block having a size of 200mm×500mm×500mm, is formed. Of course, in the actual use process, the metal sheets may be connected using other methods, for example, ultrasonic welding, resistance welding, and laser welding. In step S4, the metal block from step S3 is cut along its cross section, and the cut thickness is adjusted to the required thickness of the gas diffusion layer, for example, 0.5 mm, and a sheet structure is formed on the cut surface with regularly spaced micropores to form a gas diffusion layer. When a 200 mm x 500 mm x 500 mm metal block is cut, hundreds of gas diffusion layers with a standard size of 500 mm x 500 mm x 0.5 mm can be obtained, and the formed gas diffusion layer can have a micropore density of millions to billions per square meter, and has excellent flow-directing effect on the fluid. After step S4, step S5 may be added. Specifically, the gas diffusion layer is subjected to a surface coating treatment, which mainly includes a passivation antiseptic treatment and a hydrophilic treatment. EXAMPLES

[0007] In the embodiment of the present application, the present application provides a gas diffusion layer, which is obtained by the manufacturing method in the embodiment 1 as shown in Fig. 4, and the specific structure includes a thin plate body, on which a number of micropores penetrating the thin plate body are regularly arranged, and the thickness of the thin plate body is preferably 200-800 microns. As shown in Fig. 4, the micropores may be arranged using a rectangular array, and as shown in Fig. 5, the micropores may be arranged to present a number of rows, and the micropores of adjacent rows may be arranged to present a positional shift, so that the micropores can be made more uniform, and the area utilization rate can be increased for the irregularly shaped thin plate body. The present application uses a completely new manufacturing method to manufacture a gas diffusion layer with high manufacturing efficiency, flat surface, and regularly arranged flow-through holes, which has better contact with the membrane electrode, reduces the resistance of the contact surface, and improves the electrolysis efficiency. The flow-through efficiency of gas and liquid can be maximized. Therefore, the present application is an important innovation on the irregular internal pore structure of the gas diffusion layer for the conventional SPE electrolyzer, which greatly improves the flow-through effect of the gas diffusion layer to the fluid, and also improves the contact efficiency between the gas diffusion layer and the membrane electrode. In addition, the gas diffusion layer manufactured by the method of the present application may be used in fields including, but not limited to, physicochemical reaction fields where fluids need to be sufficiently dispersed or collected, such as fuel cells, and it should be noted that the performance advantages of the gas diffusion layer of the present application can be concretely demonstrated even when used in these fields. It should be noted that all directional indications in the embodiments of the present invention (e.g., up, down, left, right, front, back, etc.) are used only to interpret the relative positional relationships, movement conditions, etc. between each member in a certain specific posture (as shown in the figures), and when that specific posture changes, the directional indications also change accordingly. Moreover, in the present invention, references to "first", "second", etc., are merely for explanatory purposes and should not be understood as indicating or implying the relative importance thereof, or as concealing and revealing the number of technical features indicated. Thus, a feature that is qualified with "first" or "second" may explicitly or implicitly include at least one of the feature. In the present description, the meaning of "plurality" is at least two, e.g., two, three, etc., unless otherwise clearly limited. In the present invention, unless otherwise clearly specified and limited, the terms "connected", "fixed", etc. should be understood in a broad sense, for example, "fixed" may mean fixed connection, detachable connection, integral, mechanical connection, electrical connection, direct connection, indirect connection via an intermediate medium, and unless otherwise clearly limited, may mean internal communication between two elements or an interactive relationship between two elements. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific situation. In addition, the technical solutions in each embodiment of the present invention can be combined with each other, which is feasible for a person skilled in the art. If the combination of the technical solutions is not mutually contradictory or cannot be realized, it should be considered that such combination of the technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. In the method for producing a gas diffusion layer, Step S1: machining a long groove in a horizontal row on one surface of a metal sheet; Step S2: cutting the elongated thin metal plate having the groove formed in step S1 into a desired shape; Step S3: overlapping the thin metal sheets cut in step S2 into some blocks, and tightly connecting the adjacent thin metal sheets to form a metal block having a regular pore structure therein; Step S4: cutting the metal block obtained in Step S3 along its cross section, adjusting the cut thickness to a required thickness of the gas diffusion layer, and forming a sheet structure having regularly spaced micropores on the cut surface to form the gas diffusion layer.

2. In step S1, Step S11: Manufacturing a printing roll: A step of engraving grooves arranged in a horizontal row on a printing roll having a smooth surface; 2. The method for manufacturing a gas diffusion layer according to claim 1, further comprising: step S12: roll-pressing the thin metal plate using the printing roll produced in step S11, to form elongated grooves arranged in a horizontal row on one side of the thin metal plate.

3. 3. The method for manufacturing a gas diffusion layer according to claim 2, wherein the grooves on the printing roll are arranged in a single horizontal row along the axial or circumferential direction of the printing roll.

4. 2. The method for manufacturing a gas diffusion layer according to claim 1, wherein in step S1, the elongated groove on the surface of the thin metal plate is formed by laser processing, etching processing, ultrasonic electric engraving processing, or electric discharge processing.

5. 2. The method for manufacturing a gas diffusion layer according to claim 1, wherein the thin metal plate is made of titanium metal or a titanium alloy.

6. 2. The method of claim 1, further comprising: performing a surface coating treatment on the gas diffusion layer after step S4, the surface coating treatment being a passivation antiseptic treatment and a hydrophilic treatment.

7. A gas diffusion layer, which is obtained by the method according to any one of claims 1 to 6.

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