Preparation system and preparation method of microporous layer of PEM electrolytic cell metal diffusion layer for hydrogen production

Abstract

The invention relates to the technical field of PEM water electrolysis hydrogen production, and particularly discloses a preparation system and a preparation method of a microporous layer of a PEM electrolytic bath metal diffusion layer for hydrogen production, the preparation system comprises a spraying chamber, a shaping chamber and a conveying assembly, the spraying chamber comprises a plurality of spraying guns, a slurry mixed with a coating is atomized by the spray gun and then uniformly covers a metal fiber felt plate base material to form a microporous layer, the shaping chamber comprises a heating unit, and the heating unit is designed to dry a spraying layer used for forming the microporous layer on the metal fiber felt plate for shaping, so that the mass ratio of a solvent in the slurry of the spraying layer is 25-85%. The preparation method adopts the preparation system. The structure is reasonable, the microporous layer preparation efficiency is high, the cost is low, the microporous layer with the gradient aperture can be conveniently formed, the thickness uniformity is high, the thickness can be within 10% of the spraying thickness, and continuous production can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by PEM water electrolysis, and in particular to a system and method for preparing a microporous layer of a metal diffusion layer in a PEM electrolyzer for hydrogen production. Background Art

[0002] The combination of a metal diffusion layer and a microporous layer (MPL) has broad applications in various fields, particularly in energy, environmental protection, and chemical engineering. For example, in fuel cells, it can be used as a gas diffusion layer (GDL), water management layer, gas transport layer, and thermal management layer. In PEM water electrolysis for hydrogen production, it can be used as an electrode material, a diaphragm for gas-liquid separation, or a catalyst carrier. In hydrogen purification and filtration, it can be used for multi-stage filtration of impurities in hydrogen and as an adsorbent carrier. Microporous layers with gradient pore sizes offer significant advantages, particularly in PEM water electrolysis equipment, where they can be used as gas diffusion layers (GDLs).

[0003] In the prior art, metal diffusion layers typically utilize metal fiber felt sheets, onto which metal powder is applied as a coating to create a microporous layer. There are several methods for preparing microporous layers: plasma spraying, which includes atmospheric plasma spraying and vacuum plasma spraying. Atmospheric plasma spraying is performed in an atmospheric environment, where it is susceptible to oxidation by the oxygen in the air and the high-temperature spray gun. The resulting oxides affect the electrochemical properties of the microporous layer and reduce its conductivity. Vacuum plasma spraying, on the other hand, requires vacuum operation, resulting in expensive equipment and the need for repeated vacuuming, resulting in low production efficiency and significantly increased production costs. Furthermore, the uniformity of the microporous layer produced by the prior art plasma spraying method is poor, at only 10-20% of the sprayed thickness.

[0004] Another method is the scraping method, which is to evenly apply the slurry mixed with the coating on the base of the metal fiber felt board at room temperature and pressure, and form a microporous layer through subsequent processing. Although the oxidation of the coating can be avoided, the uniformity of the coating after coating is 3-10% of the coating thickness. However, the scraping area of ​​this method is limited, and the complete coverage scraping method will also cause the slurry to overflow and waste. In addition, the suspension of the coating in the slurry is poor, and only one microporous layer with one pore size can be formed by scraping once, which cannot be produced continuously. The production cycle of preparing a microporous layer with a gradient pore size is long and the cost is high. In addition, because the metal fiber felt board has The pore structure and good liquid diffusion ability of the fiber felt sheet during scraping make it easy for the dry fiber felt sheet to absorb a large amount of solution, resulting in an imbalance in the proportion of the scraped paint and an inability to complete a smooth scraped surface. In addition, if the fiber felt sheet is soaked for scraping, although the proportion of the scraped paint in the first half can be healthy and the scraping effect is good, in the second half, the solvent will accumulate as the scraper moves forward, resulting in excessive solvent in the second half, breaking the uniform distribution of the paint and causing poor uniformity of the scraped surface. The scraping width is limited, and if the width is increased, the scraping effect and uniformity will also decrease. Summary of the Invention The present invention discloses a system and method for preparing a microporous layer for a metal diffusion layer in a PEM electrolyzer for hydrogen production. This system solves the technical problems of easy oxidation, high cost, or low efficiency in existing microporous layer preparation processes. The system has a reasonable structure, high efficiency and low cost in preparing the microporous layer, facilitates the formation of a microporous layer with a gradient pore size, and enables continuous production. The technical solution employed is as follows: A preparation system for a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production, comprising a spraying chamber, a shaping chamber and a conveying assembly, wherein the spraying chamber and the shaping chamber are connected to form a conveying assembly. The conveying assembly is used to transport the metal fiber felt sheet along the forming channel, the spraying chamber includes several spray guns, and the slurry mixed with the coating is atomized by the spray guns and evenly covered on the metal fiber felt sheet substrate to form a microporous layer. A negative pressure environment is formed in the spraying chamber to prevent the slurry mixed with the coating from overflowing; the shaping chamber includes a heating unit, and the heating unit is designed to dry the spray layer used to form the microporous layer on the metal fiber felt sheet for shaping.

[0005] Based on the above technical solution, the heating unit is designed to dry the spray coating layer for forming the microporous layer on the metal fiber felt board to shape it so that the mass ratio of the solvent in the slurry of the spray coating layer is 25-85%.

[0006] Based on the above technical solution, the plurality of spray guns are divided into multiple groups, and the multiple groups of spray guns are arranged in front and behind along the forming channel to spray to form a spray layer of a predetermined thickness or to form a stack of multiple spray layers. Preferably, the inner diameter of the spray gun muzzle is 1-3 mm to achieve the effect of smoothly spraying metal particles of various particle sizes.

[0007] On the basis of the above technical solution, it also includes a dust removal chamber arranged in parallel with the spraying chamber and the shaping chamber, the molding channel extends and passes through the dust removal chamber, and the conveying assembly transports the fiber felt board through the dust removal chamber and then into the spraying chamber and the shaping chamber.

[0008] On the basis of the above technical solution, the forming modules formed by the spraying chamber and the shaping chamber are arranged in multiple groups in parallel along the forming channel.

[0009] Based on the above technical solution, the spraying room is provided with water curtains on both sides of the conveying assembly, and two water tanks for receiving the water curtains are provided under the spraying room. The floor of the water tank has an inclined angle to facilitate the collection of slurry.

[0010] On the basis of the above technical solution, the heating unit includes a plurality of heating resistance wires, and the plurality of electric heating wires are centrally arranged in the middle area of ​​the shaping chamber. The heating unit is electrically connected to an external controller to automatically control the drying conditions.

[0011] On the basis of the above technical solution, the dust removal chamber includes a dust removal inlet and a dust removal outlet, which are horizontally long and narrow for the conveying component to pass through; the spraying chamber includes a spraying inlet and a spraying outlet, which are horizontally long and narrow for accommodating the conveying component to pass through; the shaping chamber includes a shaping inlet and a shaping outlet, which are horizontally long and narrow for the conveying component to pass through, so that the dust removal chamber, the spraying chamber and the shaping chamber are relatively isolated from the outside world.

[0012] A method for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production, using the above-mentioned preparation system, is characterized by comprising the following steps: S1. Under the action of the conveying assembly, the metal fiber felt substrate enters the spraying chamber along the forming channel; S2, after the metal fiber felt substrate enters the spraying chamber, it continues to be transported forward along the forming channel, and the slurry mixed with the coating is atomized by the spray gun and evenly covers the metal fiber felt substrate to form a microporous layer; S3. Under the action of the conveying assembly, the metal fiber felt substrate enters the shaping chamber along the shaping channel, and the heating unit heats the metal fiber felt substrate to dry and shape the spray layer; S4. Under the action of the conveying assembly, the metal fiber felt substrate is continuously transported forward along the forming channel to enter the next process.

[0013] Based on the above technical solution, several of the spray guns are divided into multiple groups, and multiple spray gun groups are arranged front and back along the forming channel to spray to form a spray layer of a set thickness or to form a stacked effect of multiple spray layers, and the spray thickness of each spray gun group is 0.01~2mm.

[0014] A metal plate is produced by adopting the above-mentioned method for preparing a microporous layer of a metal fiber felt plate.

[0015] Beneficial effects The present invention is cleverly designed and comprises a conveying assembly and a spray chamber and a shaping chamber arranged in sequence. During the process of the conveying assembly transporting the metal fiber felt substrate forward through the spray chamber, the spray gun can evenly apply a slurry containing powder coating of a set particle size with good uniformity. Afterwards, preliminary shaping can be performed in the shaping chamber so that the coating powder in the spray layer is not dispersed and has a certain cohesive force. Even if multiple spray layers are superimposed, they can still have a stable state, which is convenient for subsequent sintering processes. In addition, there are multiple groups of spray guns, so that multiple spray layers can be formed, and finally a microporous layer with gradient or other forms of pore size changes is formed, which well realizes the preparation of gradient pore size under normal temperature conditions. The process is simple, efficient and low-cost, avoids the problem of powder oxidation in the coating that exists in high-temperature spraying, and can be produced continuously, overcoming the problems of low efficiency and long production cycle in the scraping method.

[0016] In the present invention, a spray gun in a spray chamber atomizes the slurry before spraying, resulting in better spray uniformity and reducing the uniformity of the resulting microporous layer to approximately 5% of the spray thickness. Furthermore, the spray chamber is flexible and can be adapted to spray a variety of coatings to meet various process requirements by adjusting the spray gun's spray speed and flow rate. Furthermore, the spray chamber is in a negative pressure state, forming a top-down airflow. This, on the one hand, guides the slurry mixed with the coating downward to contact the metal fiber felt substrate, and on the other hand, reduces slurry overflow or splashing, thereby reducing the disturbance of the spray area by the overflow or splashing slurry, thereby facilitating the slurry to fall along a predetermined path and further improving spray uniformity. Furthermore, the atomized spraying method exerts less physical impact on the substrate and the pre-formed coating, resulting in stable and uniform thickness growth. A water curtain is also provided in the spray chamber to prevent slurry from splashing onto the side walls of the spray chamber, thereby affecting subsequent spraying operations, and to facilitate the recycling of slurry splashed to both sides, thereby reducing waste.

[0017] In the present invention, the heating resistance wires in the shaping chamber are centrally arranged in the middle area of ​​the shaping chamber, so that the temperature in the shaping chamber is first heated up and then cooled down along the conveying direction of the fiber mat substrate. On the one hand, the spray layer is gradually shaped with a good shaping effect, and on the other hand, the impact on adjacent spray chambers is reduced; the paint in the dried spray layer has adhesion, and the formed pore structure is stable, avoiding collapse and the like.

[0018] In the present invention, the dust removal chamber, spray chamber, and sizing chamber are all equipped with horizontally narrow inlets and outlets, making them relatively isolated from the external environment and reducing contamination of the spray coating or metal fiber felt substrate during the preparation process. In addition, the spray chamber and sizing chamber are close together or externally covered by a shell, which reduces contact with the external environment and reduces contamination, thereby improving the quality of the finished microporous layer of the metal fiber felt.

[0019] In the present invention, the forming modules formed by the spraying chamber and the shaping chamber are arranged in multiple groups along the forming channel. After a spray layer is formed, it is dried and shaped, so that multiple spray layers can be formed. The stacked structure of the multiple spray layers is stable and not easy to collapse, which provides conditions for forming a microporous layer with a larger thickness and good adaptability.

[0020] The metal plate of the present invention is prepared by the preparation method as described above, which not only has good pore size quality on the microporous layer, but also has good finished product quality, simple process and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only one embodiment of the present invention. Those skilled in the art can also derive other implementation drawings based on the provided drawings without inventive effort.

[0022] Figure 1 : A schematic structural diagram of the present invention in Example 1; Figure 2 : A schematic structural diagram of the spray chamber elevation in Example 1; Figure 3 : A schematic structural diagram of a top view of the shaping chamber in Example 1; Figure 4 : Schematic diagram of the structure of the microporous layer prepared by the preparation system in Example 1; Figure 5 : A schematic structural diagram of the present invention in Example 2; DETAILED DESCRIPTION The following description and accompanying drawings sufficiently illustrate the specific embodiments herein to enable those skilled in the art to practice them. Portions and features of some embodiments may be included in or substituted for portions and features of other embodiments. The scope of the embodiments herein includes the entire scope of the claims, including all available equivalents thereof. Herein, the terms "first," "second," and the like are used solely to distinguish one element from another and do not require or imply any actual relationship or order between these elements. In practice, the first element can also be referred to as the second element, and vice versa. Furthermore, the terms "comprise," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a structure, device, or apparatus comprising a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such structure, device, or apparatus. Without further limitation, an element defined by the phrase "comprising a..." does not preclude the presence of other identical elements in the structure, device, or apparatus comprising the element. The various embodiments herein are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Similar or identical parts between the various embodiments can be referenced to each other.

[0023] The terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used herein to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are intended only to facilitate the description of this document and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention. In the description herein, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, they can be mechanical or electrical connections, or they can be internal connections between two elements, they can be directly connected, or they can be indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0024] As used herein, unless otherwise specified, the term "plurality" means two or more.

[0025] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0026] In this article, the term "and / or" is used to describe the association relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or, A and B.

[0027] Example 1 like Figure 1 The system for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production shown includes a conveying component 4, a dust removal chamber 1, a spraying chamber 2 and a forming chamber 3.

[0028] The conveying assembly 4 is in the prior art. In the present application, the conveying assembly 4 includes a conveyor belt and a conveying drive. The conveying drive includes a conveying motor, a conveying driving wheel, a conveying passive wheel and a plurality of tensioning wheels. The conveyor belt is sleeved outside the conveying driving wheel and the conveying passive wheel. The conveying motor can transmit the rotational motion to the conveying driving wheel. The metal fiber felt board is transported forward as a substrate by the conveyor belt. In other embodiments of the present application, the conveying assembly 4 includes multiple length segments connected end to end. The multiple length segments correspond to the dust removal chamber 1, the spraying chamber 2 and the shaping chamber 3 respectively. The multiple length segments can be driven by different motors respectively to accurately control the speed at which the metal fiber felt board substrate is transported forward along the forming channel to match the different speed requirements for the forward transportation of the substrate in the spraying chamber 2 or the shaping chamber 3.

[0029] The inner cavities of the dust removal chamber 1, the spraying chamber 2 and the shaping chamber 3 are connected to form a shaping channel for the conveying component 4 to pass through. The conveying component 4 transports the fiber mat board through the dust removal chamber 1 and then into the spraying chamber 2 and the shaping chamber 3.

[0030] The dust removal chamber 1 is a prior art system that filters air containing dust or other particles through air flow, and the clean air after filtration is then discharged back into the environment. In this embodiment, the dust removal chamber 1 is designed to achieve a cleanliness level below Class 1000. In other embodiments of the present invention, the cleanliness level of the dust removal chamber 11 can also be slightly lower or higher to reduce the contact between external dust or particles and the metal fiber felt substrate. In this embodiment, the dust removal chamber 1 includes a dust removal fan, a dust removal air inlet, a dust removal air outlet, and a dust removal filter unit. The dust removal air inlet is located at the top of the dust removal chamber 1, and the dust removal air outlet is located at the bottom of the dust removal chamber 1. The dust removal fan is located at the dust removal air inlet. The dust removal filter unit is a prior art system that can be selected by those skilled in the art as needed. Under the action of the dust removal fan, the air flow introduced through the dust removal air inlet flows through the dust removal filter unit and is then discharged. This not only forms a purified circulating air in the dust removal chamber 1, but also sweeps away dust or other particles on the fiber felt substrate to achieve a dust removal effect, facilitating the subsequent application of the slurry mixed with the coating on the substrate.

[0031] like Figure 2As shown, the spray chamber 2 includes a plurality of spray guns 5. The slurry mixed with the coating is atomized by the spray gun 5 and evenly covered on the metal fiber felt board substrate to form a microporous layer. In this embodiment, the coating is metal powder, such as titanium, stainless steel, nickel, copper powder, etc., and the solvent is water. The metal powder and water are mixed to form a slurry. In other embodiments of the present application, the coating can also be selected from other metal powders or non-metallic powders, and the solvent can be appropriately selected. This is the prior art and will not be repeated here. In this embodiment, the spraying area formed by the nozzle of the spray gun 5 spans the width of the conveyor belt, so that the metal fiber felt board substrate can be completely sprayed.

[0032] The spray guns 5 are arranged in multiple groups, each positioned front and back, along the axial direction of the forming channel, to spray a coating of a predetermined thickness or to form multiple layers of spray coatings. In this embodiment, the spray gun 5 has a muzzle inner diameter of 1 to 3 mm to facilitate the smooth spraying of metal particles of varying particle sizes. Specifically, when the multiple spray guns 5 are spraying a single particle size of coating, the muzzle inner diameters of the different groups of spray guns 5 remain consistent, and the conveyor belt simultaneously transports the metal fiber felt substrate forward, thereby forming a spray coating of a predetermined thickness and ensuring spray uniformity. When the multiple spray guns 5 are blasting coatings of varying particle sizes, the different groups of spray guns 5 can be configured with different muzzle inner diameters.

[0033] Multiple groups of spray guns 5 work simultaneously, and can gradually form different spray layers with set thicknesses, with better spray uniformity, so that the pore size uniformity of the obtained microporous layer is better. When multiple groups of spray guns 5 spray coatings of different particle sizes, spray layers with different pore sizes can be formed. In this embodiment, the metal fiber felt substrate uses a titanium fiber felt substrate with a surface pore size of 30um as the substrate. The spray guns 5 are divided into three groups. The first spray gun group 5 close to the dust removal chamber sprays a slurry mixed with 50um particle size titanium powder coating, and sprays a bottom spray layer with a thickness of 0.1mm. The second spray gun group 5 in the middle sprays a slurry mixed with 30um particle size titanium powder coating, and sprays a middle spray layer with a thickness of 0.1mm. The third spray gun group 5 close to the shaping chamber 3 sprays a slurry mixed with 10um particle size titanium powder coating, and sprays a top spray layer with a thickness of 0.1. In this way, the obtained microporous layer has a gradient pore size change as a whole, such as Figure 4 In other embodiments of the present invention, two or more layers of spray coatings with different particle sizes can be provided, and the thickness of the spray coating of each particle size is 0.01-2 mm. The particle sizes of the multiple spray coatings can also be flexibly adjusted.

[0034] In this embodiment, the spray guns 5 are disposed within the spray chamber 2 in an adjustable manner, both vertically and at an adjustable angle. Specifically, each set of spray guns 5 is connected to a telescopic rod 6. Adjusting the telescopic rod 6 adjusts the distance between the spray guns 5 and the conveyor belt, thereby accommodating the spraying of paint of various particle sizes. Furthermore, the heads of the spray guns 5 are upwardly connected via joints (not shown), which allow for adjustment of the spraying direction of the spray guns 5, thereby providing greater flexibility. The joints are conventional and will not be described in detail here.

[0035] The inlet end of the spray gun 5 is connected to a diaphragm pump via a pipeline, and the slurry mixed with the coating is supplied to the spray gun 5 via the diaphragm pump. A regulating unit is provided on the pipeline for adjusting the speed and flow rate of the slurry sprayed by the spray gun 5. The regulating unit is conventional and can be selected by those skilled in the art as needed, and will not be described in detail here.

[0036] like Figure 2 As shown, a negative pressure environment is created within the spray chamber 2 to prevent the slurry mixed with the paint from overflowing. In this embodiment, a plurality of fan-shaped sweep nozzles are provided at the top of the spray chamber 2. The airflow formed within the spray chamber 2 flows downward from top to bottom, creating a negative pressure environment. On the one hand, this guides the slurry mixed with the paint downward to contact the metal fiber felt substrate. On the other hand, it reduces the possibility of slurry overflow or splashing, thereby reducing the disturbance of the spraying area caused by the overflowing or splashing slurry. This helps the slurry fall along a predetermined path and improves the uniformity of the spraying.

[0037] like Figure 2 As shown, the spray chamber 2 is equipped with water curtains 7, located on either side of the conveyor assembly. Specifically, two narrow water outlet lines are provided on the top surface of the spray chamber 2. The water outlet lines extend along the axis of the conveyor assembly 4 and are slightly higher than the spray gun 5. Two water troughs 8 are located below the spray chamber 2 to receive the water curtains 7 and collect the slurry and water mixture. The bottom surface of the water troughs 8 is inclined, and the drain outlet of the water troughs 8 is located at a lower position to guide the collected water mixed with slurry into the water collection tank, allowing the paint to be recycled and reducing waste.

[0038] The shaping chamber 3 includes a heating unit, and the heating unit is designed to dry the spray layer on the metal fiber felt board for shaping. In this embodiment, the shaping chamber 3 includes an insulation layer to reduce heat exchange with the outside, reduce energy consumption, and reduce the impact on the spray chamber 2. The heating unit 10 includes a plurality of heating resistance wires, and the heating unit 10 is electrically connected to an external controller to automatically control the drying conditions, such as drying time, drying temperature, etc. In this embodiment, the drying conditions are designed to have a temperature of 60 degrees Celsius in the center area of ​​the shaping chamber, and evaporate and dry the solvent in the slurry with a mass ratio of 70% to 40%, so that the coating in the slurry does not disperse and has a certain cohesive force. In other embodiments of the present invention, the drying conditions are designed to evaporate and dry the solvent in the slurry to a mass ratio of 25~85%.

[0039] In this embodiment, Figure 3As shown, the heating resistance wires are centrally arranged in the middle area of ​​the shaping chamber 3, so that the temperature in the shaping chamber is first heated up and then cooled down along the conveying direction of the fiber mat substrate. On the one hand, the spray layer is gradually shaped, and the shaping effect is good. On the other hand, the impact on the adjacent spraying chamber is reduced. In addition, the shaping chamber 3 is also provided with a shaping fan, a shaping air inlet, a shaping air outlet and a shaping filter unit. The shaping filter unit is arranged at the shaping air outlet and the air inlet, and the shaping fan is arranged at the shaping air outlet. Under the action of the fan, a larger air flow is formed in the shaping chamber to accelerate the drying process.

[0040] In this embodiment, Figure 1 As shown, in order to relatively isolate the dust removal chamber 1, the spraying chamber 2 and the shaping chamber 3 from the external environment, the dust removal chamber 1 includes a dust removal inlet 11 and a dust removal outlet 12, and the dust removal inlet 11 and the dust removal outlet 12 are horizontally long and narrow for the conveying component 4 to pass through; the spraying chamber 2 includes a spraying inlet 21 and a spraying outlet 22, and the spraying inlet 21 and the spraying outlet 22 are horizontally long and narrow to accommodate the conveying component 4 to pass through, so as to well isolate the spraying chamber 2 from the external environment; the shaping chamber 3 includes a shaping inlet 21 and a shaping outlet 22, and the shaping inlet 21 and the shaping outlet 22 are horizontally long and narrow for the conveying component 4 to pass through, so as to well isolate the shaping chamber 3 from the outside world.

[0041] In addition, the dust removal chamber 1, the spraying chamber 2 and the shaping chamber 3 are arranged in pairs and the inner cavities are connected, which can avoid contact with the external environment during the spraying and shaping process, which is beneficial to improving the quality of the finished product after sintering.

[0042] A method for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production, using the above-mentioned preparation system, is characterized by comprising the following steps: S1. Under the action of the conveying component 4, the metal fiber felt board substrate enters the spraying chamber 2 along the forming channel; wherein, the metal fiber felt board substrate adopts a titanium fiber felt board with a surface pore size of 30 μm.

[0043] S2. After the metal fiber felt substrate enters the spraying chamber 2, it continues to be transported forward along the forming channel. In this embodiment, the spray guns 5 are divided into three groups. The spraying range of the three spray gun groups covers the width of the metal fiber felt substrate. The three spray gun groups are arranged front and back along the forming channel. The first spray gun group 5 close to the dust removal chamber 1 sprays a slurry mixed with 50um titanium powder coating, and sprays a bottom spray layer with a thickness of 0.1mm. The second spray gun group 5 in the middle sprays a slurry mixed with 30um titanium powder coating, and sprays a middle spray layer with a thickness of 0.1mm. The third spray gun group 5 close to the shaping chamber 3 sprays a slurry mixed with 10um titanium powder coating, and sprays an upper spray layer with a thickness of 0.1. In this way, the subsequently obtained microporous layer has a gradient pore size change as a whole, such as Figure 4In other embodiments of the present invention, the spray coating layer with coating materials of different particle sizes may be provided in two or more layers; in other embodiments of the present invention, the spraying thickness of each of the spray gun groups is 0.01-2 mm.

[0044] S3. Under the action of the conveying assembly, the metal fiber felt substrate enters the shaping chamber 3 along the shaping channel. Under the action of the heating unit, the temperature in the shaping chamber 3 is high in the middle and low at both ends. In this way, the metal fiber felt substrate is gradually heated and dried during the process of passing through the shaping chamber 3 and does not reach a high temperature after leaving the shaping chamber 3. This can better dry and shape the spray layer. S4. Under the action of the conveying assembly, the metal fiber felt substrate is continuously transported forward along the forming channel to enter the next process.

[0045] A metal plate is prepared by adopting the above-mentioned method for preparing a microporous layer of a metal fiber felt plate. The microporous layer has good void quality and low cost.

[0046] Example 2 The difference between the preparation system in Example 2 and Example 1 is that Figure 5 As shown, the spray chamber 2 and the shaping chamber 3 are spaced apart, forming three parallel groups of molding modules, with the shaping channel running through the three groups. The spacing between the spray chamber 2 and the shaping chamber 3 reduces interference between them and better matches the different processing rhythms of the spray chamber 2 and the shaping chamber 3. For example, when a substrate is transported between the spray chamber 2 and the shaping chamber 3, the waiting time between the substrates entering the shaping chamber 3 provides conditions for the previous substrate to be effectively dried in the shaping chamber 3. Along the conveying direction of the conveying component 4, three groups of forming modules are arranged in sequence, and three groups of spray guns 5 are respectively arranged in three spraying chambers 2, that is, the first spray gun group 5 sprays a slurry mixed with 50um titanium powder coating, sprays a bottom spray layer with a thickness of 0.1mm, and then enters the adjacent shaping chamber 3 for drying and shaping; then the second spray gun group 5 sprays a slurry mixed with 30um titanium powder coating, sprays a middle spray layer with a thickness of 0.1mm, and then enters the adjacent shaping chamber 3 for drying and shaping; then the third spray gun group 5 sprays a slurry mixed with 10um titanium powder coating, sprays an upper spray layer with a thickness of 0.1mm, and then enters the adjacent shaping chamber 3 for drying and shaping. In this way, each layer of spray coating is sprayed and dried and shaped respectively, the shaping effect is good, the metal fiber felt board and the spray coating structure are more stable, and it is convenient for subsequent sintering, such as Figure 4 Or three spray gun groups spray slurry mixed with the same particle size coating to form a spray layer with a set thickness, which is then dried and shaped. This provides conditions for forming a thicker microporous layer and ensures a good pore size state.

[0047] In this embodiment, to further reduce the contamination of the metal fiber felt substrate by the external environment, at least the outer covers of the spray chamber 2 and the shaping chamber 3 are provided with a shell 9. The inner cavity of the shell 9 is relatively independent of the external environment and is connected to the dust removal chamber 1. The conveying assembly 4 transports the fiber felt through the dust removal chamber 1 and then enters the spray chamber 2 and the shaping chamber 3. In this embodiment, the inner cavity of the shell 9 can achieve a cleanliness level below Class 1000, reducing contamination of the metal fiber felt substrate or the spray layer. The inner cavity of the shell 9 includes a shell fan, a shell air inlet, and a shell filter unit to purify the air flowing through. Specifically, the shell air inlet is provided at the top of the shell, the shell fan is provided at the shell air inlet, and the shell filter unit is a prior art that can be selected by those skilled in the art according to their needs. The shell filter unit is provided at the shell air inlet. Under the action of the shell fan, the air flow introduced through the shell air inlet is filtered by the shell filter unit and then discharged, forming a purified circulating air in the shell.

[0048] The present invention is described above by way of examples, but the present invention is not limited to the above specific embodiments. Any changes or modifications based on the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A system for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production, characterized in that: The invention comprises a spraying chamber (2), a shaping chamber (3) and a conveying assembly (4), wherein the spraying chamber (2) and the shaping chamber (3) are connected to form a shaping channel for the conveying assembly (4) to pass through, and the conveying assembly (4) is used to transport the metal fiber felt along the shaping channel, and the spraying chamber (2) comprises a plurality of spray guns (5), and the slurry mixed with the coating is atomized by the spray guns (5) and evenly covered on the metal fiber felt substrate to form a microporous layer, and a negative pressure environment is formed in the spraying chamber (2) to prevent the slurry mixed with the coating from overflowing; the shaping chamber (5) comprises a heating unit, and the heating unit (10) is designed to dry the spray layer on the metal fiber felt for forming the microporous layer to shape it.

2. The system for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production according to claim 1, characterized in that: The heating unit is designed to dry the spray coating layer for forming the microporous layer on the metal fiber felt board to set the spray coating layer so that the mass ratio of the solvent in the slurry of the spray coating layer is 25-85%.

3. The system for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production according to claim 1, characterized in that: The spray guns are divided into multiple groups, and the multiple groups of spray guns are arranged front and back along the forming channel to spray to form a spray layer of set thickness or to form a stacked effect of multiple spray layers.

4. The system for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production according to claim 1, characterized in that: It also includes a dust removal chamber (1) arranged in parallel with the spraying chamber (2) and the shaping chamber (3), the shaping channel extends and passes through the dust removal chamber (1), and the conveying assembly (4) transports the fiber mat board through the dust removal chamber (1) and then into the spraying chamber (2) and the shaping chamber (3).

5. The system for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production according to claim 4, characterized in that: The molding modules formed by the spraying chamber (2) and the molding chamber (3) are arranged in multiple groups in parallel along the molding channel.

6. The system for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production according to any one of claims 1 to 5, characterized in that: The spraying room (2) is provided with water curtains (7) arranged on both sides of the conveying assembly (4), and two water tanks (8) for receiving the water curtains (7) are provided below the spraying room (2). The floor of the water tank has an inclined angle to facilitate the collection of slurry.

7. The system for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production according to claim 6, characterized in that: The heating unit (10) comprises a plurality of heating resistance wires, and the plurality of electric heating wires are centrally arranged in the middle area of ​​the shaping chamber (3). The heating unit (10) is electrically connected to an external controller to automatically control drying conditions.

8. The system for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production according to claim 6, characterized in that: The dust removal chamber (1) includes a dust removal inlet (11) and a dust removal outlet (12), and the dust removal inlet (11) and the dust removal outlet (12) are horizontally long and narrow for the conveying component (4) to pass through; the spraying chamber (2) includes a spraying inlet (21) and a spraying outlet (22), and the spraying inlet (21) and the spraying outlet (22) are horizontally long and narrow for accommodating the conveying component (4) to pass through; the shaping chamber (3) includes a shaping inlet (21) and a shaping outlet (22), and the shaping inlet (21) and the shaping outlet (22) are horizontally long and narrow for the conveying component (4) to pass through, so that the dust removal chamber (1), the spraying chamber (2) and the shaping chamber (3) are relatively isolated from the outside world.

9. A method for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production, using the preparation system according to any one of claims 1 to 5, 7, and 8, characterized in that: The steps include: S1, under the action of the conveying component (4), the metal fiber felt substrate enters the spraying chamber (2) along the forming channel; S2, after the metal fiber felt substrate enters the spraying chamber (2), it continues to be transported forward along the forming channel, and the slurry mixed with the coating is atomized by the spray gun (5) and evenly covers the metal fiber felt substrate to form a microporous layer; S3, under the action of the conveying component (4), the metal fiber felt substrate enters the shaping chamber (3) along the shaping channel, and the heating unit heats the metal fiber felt substrate to dry and shape the spray layer; S4. Under the action of the conveying assembly (4), the metal fiber felt substrate is continuously transported forward along the forming channel to enter the next process.

10. The method for preparing a microporous layer of a metal diffusion layer of a PEM electrolyzer for hydrogen production according to claim 9, characterized in that: The spray guns are divided into multiple groups, and the multiple spray gun groups are arranged front and back along the forming channel to spray to form a spray layer of set thickness or to form a stacked effect of multiple spray layers, and the spray thickness of each spray gun group is 0.01~2mm.

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