Method of making a preform, method of making a membrane electrode, system and preform

Abstract

The application provides a preparation method of a membrane electrode preform, a membrane electrode preparation method, a system and the preform, and the preparation method comprises the following steps: positioning two gas diffusion sheets symmetrically in two positioning cavities of an injection mold; injecting glue into the periphery of the two positioning cavities to form a frame with a sealing structure and connect the two gas diffusion sheets together; and obtaining the membrane electrode preform. According to the preparation method of the membrane electrode preform, the gas diffusion sheets are positioned in the positioning cavities first, and then the glue is injected into the mold cavity, so that the membrane electrode preform is prepared, and the preparation process is simplified, and the product qualification rate is improved.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a method for preparing a preform of a membrane electrode assembly (MEA). Furthermore, this invention also relates to a MEA preparation method, a preform preparation system, and the preform itself. Background Technology

[0002] The seal between the membrane electrode assembly (MEA) and the bipolar plates is a crucial component of the proton exchange membrane fuel cell stack, primarily serving a sealing function within the hydrogen fuel cell stack. Poor sealing of this component in a hydrogen fuel cell can lead to leaks of gas and coolant, affecting the normal operation of the fuel cell and, in severe cases, causing safety issues.

[0003] Currently, the molding location of seals mainly falls into two categories: one is molding the seal on the bipolar plate, and the other is setting the seal on the preform of the membrane electrode assembly (MEA). The preform refers to the state of the MEA before the CCM membrane (catalyst-coated membrane) is bonded to it. The molding processes for seals currently mainly include dispensing, screen printing, and injection molding. Regarding the current mainstream approach of injection molding seals on the MEA preform or bipolar plate, the following problems exist during the injection molding process:

[0004] In the injection molding process for forming seals on membrane electrode preforms, the proton exchange membrane tends to shrink due to heat during the injection and heating process, causing changes in the dimensions or flatness of the injection site and resulting in poor seal formation. Simultaneously, the volatilization of the primer during injection and heating can easily poison the catalyst within the membrane electrode preform. Furthermore, the membrane electrode preform itself is costly, and defective products render the membrane electrode unusable, leading to waste.

[0005] In the process of forming a sealant by injection molding onto a bipolar plate, the uniformity of the bipolar plate's thickness and its flatness result in low molding precision. Since a bipolar plate is composed of two monopolar plates, it's impossible to completely eliminate dimensional tolerances and flatness errors introduced during the bipolar plate assembly process. Therefore, efforts can only be made to improve the dimensional accuracy and flatness of the prepared bipolar plate to reduce the impact of the bipolar plate's dimensions on the sealing precision. Summary of the Invention

[0006] In view of this, the present invention aims to provide a method for preparing a preform of a membrane electrode, so as to facilitate the preparation of the preform of the membrane electrode and improve the yield rate.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] A method for preparing a preform of a membrane electrode, the method comprising:

[0009] Two gas diffusers are symmetrically positioned within the two positioning cavities of the injection mold;

[0010] A colloid is injected into the outer periphery of the two positioning cavities to form a frame with a sealed structure, and the two gas diffuser sheets are connected together through the frame to obtain the preform.

[0011] Furthermore, the injection of colloid into the outer periphery of the two positioning cavities to form a frame connecting the two gas diffusers together includes:

[0012] The colloid is injected and then heated to form the frame, and the heating temperature T satisfies: 80℃≤T≤120℃.

[0013] Furthermore, the gas diffuser sheet is carbon paper or carbon cloth, and the colloid is injection-molded silicone or injection-molded silicone rubber.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] The method for preparing the preform of the membrane electrode described in this invention involves first positioning the gas diffuser sheet in the positioning cavity, and then injecting colloid into the mold cavity. This allows for the formation of a frame with a sealing structure on the gas diffuser layer, making it easier to obtain the preform. Compared to the traditional method of forming a sealing structure on the membrane electrode preform and bipolar plate, this method not only simplifies the preform preparation process but also avoids the problems caused by forming a sealing structure on the membrane electrode preform and bipolar plate, thereby improving the yield of the membrane electrode. Furthermore, the high connection strength between the colloid and the gas diffuser layer, as well as between the sealing structure and the frame, contributes to improving the performance of the membrane electrode.

[0016] Furthermore, setting the colloid heating temperature helps improve the molding effect and efficiency of preforms. Carbon paper and carbon cloth are low-cost and easy to implement, while injection molding silicone and injection molding silicone rubber both have good molding effects, which helps ensure the performance of the frame and sealing structure.

[0017] In addition, another object of the present invention is to provide a method for preparing a membrane electrode, including the method for preparing the preform as described above; further comprising:

[0018] The CCM membrane is attached to one of the gas diffusion sheets, and then the preform is folded in half;

[0019] The preform is compacted to seal the CCM membrane between the two gas diffusers, thereby obtaining a membrane electrode.

[0020] Furthermore, the step of symmetrically positioning the two gas diffusers in the positioning cavity of the injection mold includes: the two gas diffusers in the positioning cavity are on the same plane; the edges of each gas diffuser in the positioning cavity extend outward to the mold cavity on the outer periphery of the positioning cavity, and the colloid is injected into the mold cavity.

[0021] Furthermore, the compaction of the preform to seal the CCM membrane between the two gas diffusers includes: compacting the preform by rolling the bonding area between the CCM membrane and the two gas diffusers with a roller.

[0022] The membrane electrode preparation method of the present invention facilitates the preparation of membrane electrodes and improves preparation efficiency by bonding the CCM membrane to the gas diffuser, folding the preform in half, and compacting it.

[0023] Furthermore, the two gas diffusers within the positioning cavity are on the same plane, which improves the performance of the membrane electrode. The edges of the gas diffusers extend outward into the mold cavity, increasing the connection area between them and further enhancing the connection strength between the gas diffusers and the frame. Positioning is achieved through the cooperation of the flow channel holes and positioning posts on the frame, facilitating operation and ensuring good positioning results. Rolling the CCM membrane around its perimeter and the bonding area between the two gas diffusers with a roller improves the sealing effect of the CCM membrane between the two gas diffusers.

[0024] In addition, another object of the present invention is to provide a preparation system for performing the preform preparation method as described above, the preform preparation system including an injection mold;

[0025] The injection mold includes an upper mold body and a lower mold body that are fastened together, forming two positioning cavities and a mold cavity located on the outer periphery of the positioning cavity (100). Each positioning cavity is connected to the mold cavity, and the mold cavity includes a frame cavity for forming the frame and a sealing cavity for forming the sealing structure. The height of the sealing cavity is greater than the height of the frame cavity.

[0026] Furthermore, the upper mold is provided with a partition protrusion located above each of the supporting surfaces and protruding outward along the circumference of the supporting surfaces. The partition protrusion can press the periphery of the gas diffuser onto the supporting surface, thereby separating the positioning cavity and the mold cavity.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] The preform preparation system of the present invention forms a positioning cavity and a mold cavity by fastening the upper mold body and the lower mold body in the injection mold. The positioning cavity and the mold cavity are connected and arranged, and the height of the frame cavity in the mold cavity is less than the height of the sealing cavity, which is beneficial to the preparation of preforms and improves the production efficiency of preforms.

[0029] Furthermore, the multiple adsorption holes on the support surface facilitate the adsorption of the gas diffuser onto the support surface, thereby ensuring the positioning effect of the gas diffuser. The internal partition structure within the extended portion of the frame cavity also facilitates the integral formation of multiple flow channel holes on the frame, further improving the processing efficiency of the membrane electrode. The separation protrusions effectively separate the positioning cavity and the mold cavity, preventing colloid from seeping into the interior of the gas diffuser layer and affecting its performance.

[0030] Furthermore, the present invention also proposes a preform, which is prepared by the preform preparation method described above, and the preform includes a frame with a sealing structure and two gas diffusers symmetrically disposed within the frame, wherein the sealing structure is arranged circumferentially along at least one of the gas diffusers.

[0031] The preforms described in this invention are prepared by the preform preparation method described above, which helps to improve the production efficiency of preforms and has good practicality. Attached Figure Description

[0032] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0033] Figure 1 This is a flowchart of the preform preparation method described in Embodiment 1 of the present invention;

[0034] Figure 2 This is a schematic diagram of the gas diffuser sheet described in Embodiment 1 of the present invention;

[0035] Figure 3 This is a schematic diagram of the positioning cavity and mold cavity described in Embodiment 1 of the present invention;

[0036] Figure 4 This is a schematic diagram of the reverse side structure of the preform described in Embodiment 1 of the present invention;

[0037] Figure 5 This is a schematic diagram of the front side of the preform and the structure of the CCM membrane described in Embodiment 1 of the present invention;

[0038] Figure 6 This is a schematic diagram of the structure of the prefabricated component described in Embodiment 2 of the present invention;

[0039] Figure 7This is a schematic diagram of the auxiliary tooling described in Embodiment 3 of the present invention;

[0040] Figure 8 This is a schematic diagram of the pressure plate described in Embodiment 3 of the present invention.

[0041] Explanation of reference numerals in the attached figures:

[0042] 1. Gas diffuser; 100. Positioning cavity;

[0043] 2. Frame; 200. Mold cavity; 201. First sealing part; 202. Flow channel hole; 203. Second sealing part;

[0044] 3. CCM membrane;

[0045] 4. Auxiliary tooling; 401, guide hole;

[0046] 5. Pressure plate; 501. Pressing protrusion. Detailed Implementation

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0048] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] Furthermore, in the description of this invention, unless otherwise explicitly defined, the terms "installation," "connection," "linking," and "connector" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0050] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0051] Example 1

[0052] This embodiment relates to a method for preparing a preform of a membrane electrode, which simplifies the preparation process of the preform and improves the production efficiency of the preform.

[0053] Overall, such as Figure 1 As shown, the method for preparing the preform includes the following steps:

[0054] Two gas diffuser plates 1 are symmetrically positioned within the two positioning cavities 100 of the injection mold;

[0055] Colloid is injected into the outer periphery of the two positioning cavities 100 to form a frame 2 with a sealed structure. The two gas diffuser sheets 1 are connected together through the frame to obtain the preform.

[0056] The preform preparation method of this embodiment involves first positioning the gas diffuser 1 within the positioning cavity 100, and then injecting colloid into the mold cavity 200. This allows for the formation of a frame 2 with a sealing structure on the gas diffuser layer, facilitating the preparation of the preform. Compared to the traditional method of forming a sealing structure on the membrane electrode preform and bipolar plate, this method not only simplifies the preparation process of the membrane electrode preform but also avoids problems caused by forming a sealing structure on the membrane electrode preform and bipolar plate, thereby improving the yield rate of the membrane electrode. Furthermore, the high connection strength between the colloid and the gas diffuser layer, as well as between the sealing structure and the frame 2, contributes to improved performance of the preform.

[0057] Specifically, as a preferred embodiment, the gas diffuser 1 in this embodiment can be made of carbon paper. Before symmetrically positioning the two gas diffusers 1 within the two positioning cavities 100 of the injection mold, the carbon paper is first cut into two identical rectangles. Of course, the shape and specifications of the gas diffuser 1 can be adapted to meet usage requirements. In addition to being made of carbon paper, the gas diffuser 1 can also be made of carbon cloth.

[0058] like Figure 2 and Figure 3 As shown, each positioning cavity 100 is adapted to the shape of the gas diffuser 1, and the two positioning cavities 100 are arranged at intervals and parallel to each other. The mold cavity 200 is adapted to the shape of the frame 2, and the mold cavity 200 is arranged along the circumference of each positioning cavity 100 and can connect two positioning cavities 100. After the colloid is injected into the mold cavity 200 and cured, the edge of the gas diffuser 1 is bonded to the frame 2.

[0059] In a preferred embodiment, symmetrically positioning two gas diffuser sheets 1 within the positioning cavity 100 of the injection mold includes: the two gas diffuser sheets 1 within the positioning cavity 100 are on the same plane, and the edges of each gas diffuser sheet 1 within the positioning cavity 100 extend outward into the mold cavity 200 on the outer periphery of the positioning cavity 100, and the aforementioned colloid is injected into the mold cavity 200.

[0060] Here, in the positioning state, the two gas diffuser sheets 1 are on the same plane, which is beneficial to improving the product performance of the preform. The edge of the gas diffuser sheet 1 extends outward into the mold cavity 200, which is beneficial to increasing the connection area between the gas diffuser sheets 1, and further improving the connection between the gas diffuser sheet 1 and the frame 2.

[0061] In this embodiment, in the step of injecting colloid into the mold cavity 200 to form the frame 2 structure connecting the two gas diffuser sheets 1 together, the colloid is cured by heating after injection to form the frame 2, and the heating temperature T satisfies: 80℃≤T≤120℃. For example, the heating temperature T can be 80℃, 90℃, 100℃, 110℃, or 120℃. Heating temperatures within this range are beneficial for improving the curing and molding effect of the colloid. Of course, in specific implementations, the heating temperature can be set according to the characteristics of the colloid, as long as it meets the usage requirements.

[0062] Preferably, the colloid in this embodiment is injection-molded silicone or injection-molded silicone rubber, which makes the molded frame 2 have good elasticity, which not only facilitates the folding of the preform, but also facilitates the adhesion of the upper and lower frame 2 after folding to form a sealed space between the two frame 2, thereby further improving the sealing effect of the CCM film 3.

[0063] The structure of the prefabricated component in this embodiment is as follows: Figure 3 and Figure 4 As shown, the frame 2 has two frame sections corresponding to each gas diffuser 1, with three flow channel holes 202 formed at each end of one frame section. For ease of description below, one side of the preform will be referred to as the front side, and the other side as the back side. Figure 4 As shown, the sealing structure in this embodiment includes a first sealing portion 201 disposed on the front side of the frame 2 and protruding circumferentially along the two gas diffuser plates 1, and a plurality of second sealing portions 203 disposed on the front and back sides of the frame 2 and protruding circumferentially along each flow channel hole 202.

[0064] In this embodiment, during the formation of the frame 2, a first sealing portion 201 and a second sealing portion 203 are simultaneously formed on the frame 2. At the same time, the frame 2 is also tightly connected to each gas diffuser 1, thus achieving good forming efficiency and structural robustness. It should be noted that the first sealing portion 201 can also be provided only along the circumference of one of the gas diffusers 1, in which case the first sealing portion 201 can also meet the sealing requirements of the membrane electrode during use.

[0065] Specifically, because the gas diffuser 1 has a porous structure, the colloid in the mold cavity 200 can penetrate into the periphery of the gas diffuser 1. As the colloid cures, the frame 2 can be tightly bonded to the periphery of the two gas diffusers 1. At this time, there is no need to apply glue between the gas diffuser 1 and the frame 2 to increase the connection strength between them.

[0066] Example 2

[0067] This embodiment relates to a method for preparing a membrane electrode, including the method for preparing the preform in Embodiment 1, and further including: connecting a CCM membrane 3 to one of its gas diffusers 1, and then folding the preform in half; compacting the preform to seal the CCM membrane 3 between the two gas diffusers 1, thereby obtaining a membrane electrode.

[0068] In this process, the CCM membrane 3 is connected to a gas diffuser 1, and then the preform is folded in half to position the preform at a preset position on the positioning fixture. The positioning fixture has multiple positioning posts and multiple flow channel holes 202 formed on the frame 2;

[0069] In this embodiment, as Figure 5 As shown, in the step of bonding the CCM membrane 3 to one of its gas diffuser sheets 1 and then folding the preform, the four edges of the CCM membrane 3 are bonded to the reverse side of one of its gas diffuser sheets 1. After folding the preform along the symmetry line of the two gas diffuser sheets 1, the four edges of the CCM membrane 3 are bonded to the reverse side of the other gas diffuser sheet 1. The four edges of the CCM membrane 3 are bonded to each gas diffuser sheet 1 through an adhesive layer, which seals the CCM membrane 3 between the two gas diffuser sheets 1.

[0070] In practice, the adhesive layer is a pressure-sensitive adhesive, which helps to improve the adhesion between the CCM membrane 3 and the two gas diffuser sheets 1. Of course, in addition to pressure-sensitive adhesive, other products with adhesive properties can also be used for the adhesive layer.

[0071] As a preferred embodiment, the folded prefabricated component, such as Figure 6 As shown in the diagram. In the step of compacting the preform to seal the CCM membrane 3 between the two gas diffusers 1, the preform is compacted by rolling the bonding area between the CCM membrane 3 and the two gas diffusers 1 with a roller. Here, rolling the bonding area between the CCM membrane 3 and the two gas diffusers 1 with a roller helps to improve the sealing effect of the CCM membrane 3 between the two gas diffusers 1.

[0072] In addition, before folding the prefabricated component, it can be positioned in a preset location. This step includes: the prefabricated component is positioned in the preset location by fitting it onto multiple positioning posts through multiple flow channel holes 202. Here, the prefabricated component is positioned in the preset location by the cooperation of the flow channel holes 202 on the frame 2 and the positioning posts, which is easy to operate and has a good positioning effect. Specifically, the number of positioning posts is preferably matched with the number of flow channel holes 202 to achieve a better positioning effect.

[0073] The membrane electrode preparation method in this embodiment, by optimizing each step, facilitates the forming of the frame 2 and the sealing structure, which not only facilitates the preparation of the membrane electrode but also improves the yield rate of the membrane electrode preparation.

[0074] Example 3

[0075] This embodiment relates to a preform preparation system, which is used to perform the preform preparation method in Embodiment 1.

[0076] In terms of overall structure, the preform preparation system in this embodiment includes an injection mold. The injection mold includes an upper mold body and a lower mold body that are fastened together, forming two positioning cavities 100 and a mold cavity 200 located on the outer periphery of the positioning cavities 100. Each positioning cavity 100 is connected to the mold cavity 200, and the mold cavity 200 includes a frame cavity for forming a frame 2 and a sealing cavity for forming a sealing structure. The height of the sealing cavity is greater than the height of the frame cavity.

[0077] The preform preparation system of this embodiment forms a positioning cavity 100 and a mold cavity 200 by fastening the upper mold body and the lower mold body in the injection mold. The positioning cavity 100 and the mold cavity 200 are connected and arranged in a manner that is not as high as the height of the sealing cavity in the mold cavity 200. This is beneficial for the preparation of preforms and for improving the production efficiency of preforms.

[0078] In this embodiment, both the upper and lower mold bodies are provided with cavities. When the upper and lower mold bodies are fastened together, the two cavities cooperate to form the aforementioned positioning cavity 100 and mold cavity 200. In the fastened state, the gas diffuser 2 is positioned in the middle of the entire thickness direction of the mold cavity 200, so that the supported membrane electrode has a better performance.

[0079] In a preferred embodiment, the frame cavity includes two sub-cavities respectively corresponding to each gas diffuser 1, and one of the sub-cavities has an extension portion with both ends protruding outwards. The upper mold body and the lower mold body are fastened together to form a plurality of partition structures located within the extension portion. The partition structures are used to form flow channel holes 202. By setting the partition structures within the extension portion of the frame cavity, it is also beneficial to integrally form a plurality of flow channel holes 202 on the frame 2, thereby further improving the processing efficiency of the preform.

[0080] Specifically, the partition structure includes three protrusions on one of the upper mold body and the lower mold body corresponding to each extension, and a groove on the other for each protrusion to be inserted. The insertion of the protrusions into the corresponding grooves prevents the colloid from forming at that location, thereby facilitating the formation of three flow channel holes 202 on the frame 2 at both ends of one of the gas diffuser sheets 1 on the frame 2.

[0081] In a preferred embodiment, the lower mold body in this example is provided with a support surface for forming the bottom of the positioning cavity 100, and a plurality of adsorption holes penetrating the support surface. The plurality of adsorption holes are connected to an external vacuum unit to adsorb the gas diffuser 1. Here, the arrangement of the plurality of adsorption holes on the support surface facilitates the adsorption of the gas diffuser 1 onto the support surface, thereby ensuring the positioning effect of the gas diffuser 1.

[0082] Furthermore, such as Figure 7 As shown, the injection mold in this embodiment also includes an auxiliary tooling 4 that can be positioned on the lower mold body. The auxiliary tooling 4 has a guide hole 401 located above the support surface. The guide hole 401 is shaped to conform to the gas diffuser 1 to guide the gas diffuser 1 to fall onto the target position on the support surface. With this configuration, the guide hole 401 on the auxiliary tooling 4 conforms to the gas diffuser 1, which facilitates guiding the gas diffuser 1 to fall onto the target position on the support surface. Furthermore, the auxiliary tooling 4 has a simple structure and is easy to arrange and implement.

[0083] In addition, in this embodiment, the upper mold is provided with dividing protrusions located above each supporting surface and protruding outward along the circumference of the supporting surface. The dividing protrusions can press the gas diffuser 1 tightly against the supporting surface, thus separating the positioning cavity 100 and the mold cavity 200. Here, the dividing protrusions facilitate the separation of the positioning cavity 100 and the mold cavity 200, thereby preventing the colloid from penetrating into the interior of the gas diffuser layer and affecting the performance of the gas diffuser layer.

[0084] To improve the compaction of precast components, the precast component preparation system in this embodiment also includes a pressure plate 5, such as... Figure 8 As shown, the pressure plate 5 is positioned above the folded preform, and the side of the pressure plate 5 facing the preform has a pressing protrusion 501 corresponding to the bonding area between the CCM film 3 and the two gas diffuser sheets 1. The roller mentioned in Embodiment 1 specifically rolls onto the top surface of the pressure plate 5 and presses it firmly against the bonding area between the CCM film 3 and the two gas diffuser sheets 1 through the pressing protrusion 501. The pressing protrusion 501 further enhances the bonding strength between the CCM film 3 and the two gas diffuser sheets 1, thereby improving the sealing effect of the CCM film 3 between the two gas diffuser sheets 1.

[0085] To facilitate the positioning of the preform, the preform preparation system also includes a positioning fixture with a positioning surface. Multiple positioning posts, as described in one embodiment, are disposed on the positioning fixture to position the preform on the positioning surface. Furthermore, the positioning fixture may also be provided with adsorption holes to improve the positioning effect of the preformed electrode film on the positioning surface through vacuum adsorption.

[0086] In preparing the preformed electrode film, two gas diffuser sheets 1 are first dropped onto the corresponding support surface through the guide holes 401 on the auxiliary tooling 4. Then, each gas diffuser sheet 1 is adsorbed through the adsorption holes, so that each gas diffuser sheet 1 is positioned on the support surface. Next, the upper mold body and the lower mold body are fastened together, and then the adhesive is injected into the mold cavity 200 through the liquid inlet channel and heated until the adhesive solidifies and cools to obtain the preformed electrode film.

[0087] The preform is positioned on the positioning surface of the positioning fixture, and the CCM membrane 3 is bonded to one of its gas diffusers 1. The preform is then folded in half so that the CCM membrane 3 is bonded to both gas diffusers 1.

[0088] Next, a pressure plate 5 is placed on top of the folded preform, and the pressure plate 5 is pressed by a roller. The preform is compacted by the downward pressing protrusion 501 on the pressure plate 5 to seal the CCM membrane 3 between the two gas diffuser sheets 1, thereby obtaining the membrane electrode.

[0089] The preform preparation system in this embodiment has a simple structure and is easy to implement, which is conducive to realizing the membrane electrode preparation method of Embodiment 1 and improving the processing efficiency and yield of membrane electrodes.

[0090] Example 4

[0091] This embodiment also relates to a preform, which is manufactured using the preform preparation method described in Embodiment 1. The preform includes a frame with a sealing structure and two gas diffuser sheets 1 symmetrically disposed within the frame 2. The sealing structure is arranged circumferentially along at least one of the gas diffuser sheets 1. The preform in this embodiment is manufactured using the preform preparation method described above, which helps to improve production efficiency and has good practicality.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a preform of a membrane electrode, characterized in that, The method for preparing the preform includes: Two gas diffuser plates (1) are symmetrically positioned in the two positioning cavities (100) of the injection mold; A colloid is injected into the outer periphery of the two positioning cavities (100) to form a frame (2) with a sealing structure, and the two gas diffuser sheets (1) are connected together through the frame to obtain the preform; The step of symmetrically positioning the two gas diffuser plates (1) within the positioning cavity (100) of the injection mold includes: The two gas diffusers (1) inside the positioning cavity (100) are on the same plane; The edges of each gas diffuser (1) in the positioning cavity (100) extend outward into the mold cavity (200) on the outer periphery of the positioning cavity (100); The injection of colloid into the outer periphery of the two positioning cavities (100) to form a frame (2) connecting the two gas diffuser sheets (1) together includes: The colloid is injected into the mold cavity (200), and the colloid is heated and cured to form the frame (2) after injection, and the heating temperature T satisfies: 80℃≤T≤120℃; The gas diffuser sheet (1) is carbon paper or carbon cloth, and the colloid is injection-molded silicone or injection-molded silicone rubber; The frame (2) has two frame segments corresponding to each of the gas diffuser plates (1). Three flow channel holes (202) are formed at both ends of one of the frame segments. One side of the preform is the front side and the other side is the back side. The sealing structure includes a first sealing part (201) provided on the front side of the frame (2) and protruding along the circumference of the two gas diffuser plates (1), and a plurality of second sealing parts (203) provided on the front and back sides of the frame (2) and protruding along the circumference of each of the flow channel holes (202). During the formation of the frame (2), the first sealing part (201) and the second sealing part (203) are formed on the frame (2) at the same time.

2. A method for preparing a membrane electrode, characterized in that: The method for preparing the preform as described in claim 1; further comprising: The CCM membrane (3) is attached to one of the gas diffuser sheets (1), and then the preform is folded in half; The preform is compacted to seal the CCM membrane (3) between the two gas diffusers (1) to obtain a membrane electrode.

3. The method for preparing a membrane electrode according to claim 2, characterized in that: The compaction of the preform to seal the CCM membrane (3) between the two gas diffuser sheets (1) includes: The preform is compacted by rolling the bonding area between the CCM membrane (3) and the two gas diffuser sheets (1) with a roller.

4. A preform preparation system, characterized in that: The preparation system is used to perform the preform preparation method according to claim 1, and the preform preparation system includes an injection mold; The injection mold includes an upper mold body and a lower mold body that are fastened together, which together form two positioning cavities (100) and a mold cavity (200) located on the outer periphery of the positioning cavities (100). Each positioning cavity (100) is connected to the mold cavity (200), and the mold cavity (200) includes a frame cavity for forming the frame (2) and a sealing cavity for forming the sealing structure. The height of the sealing cavity is greater than the height of the frame cavity.

5. The preform preparation system according to claim 4, characterized in that: The lower mold body is provided with a support surface for forming the bottom of the positioning cavity (100), and a plurality of adsorption holes are provided through the support surface. The plurality of adsorption holes are connected to an external vacuum unit to adsorb the gas diffuser (1); and / or, The frame cavity includes two sub-cavities respectively corresponding to each of the gas diffuser sheets (1), and one of the sub-cavities has an extension portion with both ends protruding outward. The upper mold body and the lower mold body are fastened together to form a plurality of partition structures located in the extension portion. The partition structure is used to form flow channel holes (202).

6. The preform preparation system according to claim 5, characterized in that: The upper mold body is provided with a partition protrusion located above each of the supporting surfaces and protruding outward along the circumference of the supporting surfaces. The partition protrusion can press the gas diffuser (1) around its periphery onto the supporting surface, thereby separating the positioning cavity (100) and the mold cavity (200).

7. A precast component, characterized in that: The preform is prepared by the preform preparation method of claim 1, and the preform includes a frame with a sealing structure and two gas diffusers (1) symmetrically disposed within the frame (2), the sealing structure being arranged circumferentially along at least one of the gas diffusers (1).

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