Preparation method of graphite composite bipolar plate and graphite composite bipolar plate

Abstract

The invention specifically discloses a graphite composite bipolar plate preparation method and a graphite composite bipolar plate thereof, and the method comprises the following steps: S100, fully mixing a resin material and a graphite material according to a first preset proportion at a preset temperature to obtain a uniform mixed material, the resin material is organic silicon resin or organic silicon resin and phenolic resin in a second preset proportion, and the graphite material comprises hydroxylated graphene and at least one of expanded graphite, crystalline flake graphite and spherical graphite; and S200, carrying out mold pressing curing on the mixed material to obtain the graphite composite bipolar plate. In the application, the organic silicon resin can react with the phenolic resin or / and hydroxyl groups on hydroxylated graphene molecules, so that a resin phase and a graphite phase have better compatibility, and pores between the resin phase and the graphite phase are reduced, and therefore, the prepared graphite composite bipolar plate not only has good strength and electrical properties, but also has good corrosion resistance and corrosion resistance. And meanwhile, excellent air tightness is achieved.

Description

Technical Field

[0001] The present application belongs to the field of fuel cell technology, and in particular, relates to a method for preparing a graphite composite bipolar plate and a graphite composite bipolar plate. Background Art

[0002] Hydrogen fuel cells have the characteristics of high power and environmental friendliness, and are widely used in new energy vehicles and fixed power sources. Therefore, hydrogen fuel cells have broad application prospects. However, due to the high production cost of hydrogen fuel cells, their application is greatly limited. Therefore, how to reduce the production cost of hydrogen fuel cells and create more commercial value has become an important goal at present.

[0003] As one of the key components of hydrogen fuel cells, bipolar plates need to have good electrical and thermal conductivity, good mechanical strength to provide structural support for the unit, and good airtightness to prevent interaction between gases. Bipolar plates are one of the most important components in fuel cells. Their main function is to connect adjacent cells. In addition, due to the special working environment of fuel cells, corrosion resistance is also an important characteristic of bipolar plate materials.

[0004] Therefore, the selection of bipolar plate materials is crucial. Traditional metal bipolar plates have high conductivity, but poor corrosion resistance. Usually, they need to be coated with a layer of anti-corrosion coating to meet the use requirements. Graphite bipolar plates have significant advantages in corrosion resistance, but due to the porosity and brittleness of graphite itself, the mechanical properties and air tightness of graphite bipolar plates are poor. In recent years, resin-graphite composite bipolar plates have attracted widespread attention due to their good corrosion resistance and easy processing. Resin-graphite composite bipolar plates usually use resin as a binder and graphite as a conductive agent. The two are mixed to obtain a powder, and then a composite bipolar plate is obtained by molding. How to adjust the ratio between the two to balance the conductivity and mechanical strength becomes a crucial point. At the same time, because the resin and graphite are physically combined together, there are usually a large number of pores, resulting in unqualified air tightness and contact resistance. Summary of the invention

[0005] This application is made in view of the above technical problems. In order to solve the above technical problems, this application provides a method for preparing a graphite composite bipolar plate, the method comprising the following steps:

[0006] S100, fully mixing a resin material and a graphite material in a first preset ratio at a preset temperature to obtain a uniform mixed material, wherein the resin material is an organic silicone resin or an organic silicone resin and a phenolic resin in a second preset ratio, and the graphite material includes hydroxylated graphene and at least one of expanded graphite, flake graphite, spherical graphite, graphene, carbon nanotubes, and artificial graphite;

[0007] S200, molding and curing the mixed material to obtain a graphite composite bipolar plate.

[0008] In some embodiments, in step S100, the second preset ratio of the silicone resin to the phenolic resin is 5-1:1 or 1:1-5, and the preset temperature is 50-80°C.

[0009] In some embodiments, in step S100, the mixing method is one of physical mixing, solvent mixing, and grinding mixing.

[0010] In some embodiments, in step S100, the resin material and the graphite material are calculated by weight, with the graphite material accounting for 80-95 parts and the resin material accounting for 5-20 parts.

[0011] In some embodiments, in step S200, the molding temperature is 130-180° C., the molding pressure is 10-140 MPa, and the molding time is 30-300 s.

[0012] In some embodiments, in step S200, the curing temperature is 180-250° C., and the curing time is 3-8 hours.

[0013] The present application also provides a graphite composite bipolar plate, which is prepared by the above-mentioned graphite composite bipolar plate preparation method.

[0014] Compared with the prior art, the graphite composite bipolar plate preparation method provided in the present application has a resin material that can generate a large skeleton structure to provide better strength for the graphite composite bipolar plate, and the hydroxyl groups on the hydroxylated graphene can react with the silicone resin, so that the resin phase and the graphite phase are chemically bonded, thereby having better compatibility and greatly reducing the pores between the resin phase and the graphite phase. Therefore, the graphite composite bipolar plate prepared in the present application is formed by both physical action and chemical bonds between the resins and between the resin and the graphite material, and not only has good strength and electrical properties, but also has better air tightness.

[0015] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a flow chart of the method for preparing graphite composite bipolar plates in some embodiments of the present application. DETAILED DESCRIPTION

[0018] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60-120 and 80-110 is listed for a particular parameter, it is understood that the range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the resin range "ab" represents an abbreviation of any real number combination between a and b, wherein a and b are both real numbers. For example, the resin range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these resin combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0019] If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0020] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0021] refer to Figure 1As shown, the embodiment of the present application provides a method for preparing a graphite composite bipolar plate, the method comprising the following steps:

[0022] S100, fully mixing a resin material and a graphite material in a first preset ratio at a preset temperature to obtain a uniform mixed material, wherein the resin material is an organic silicone resin or an organic silicone resin and a phenolic resin in a second preset ratio, and the graphite material includes hydroxylated graphene and at least one of expanded graphite, flake graphite, spherical graphite, graphene, carbon nanotubes, and artificial graphite;

[0023] S200, molding and curing the mixed material to obtain a graphite composite bipolar plate.

[0024] In the embodiment of the present application, the resin material can generate a large skeleton structure to provide better strength for the graphite composite bipolar plate, and the hydroxyl groups on the hydroxylated graphene can react with the silicone resin, so that the resin phase and the graphite phase are chemically bonded, thereby having better compatibility, and greatly reducing the pores between the resin phase and the graphite phase. Therefore, the graphite composite bipolar plate prepared in the present application is formed by both physical action and chemical bonds between the resins and between the resin and the graphite material, and not only has good strength and electrical properties, but also has better air tightness.

[0025] In the embodiment of the present application, the graphite material includes hydroxylated graphene and at least one of expanded graphite, flake graphite, spherical graphite, graphene, carbon nanotubes, and artificial graphite, that is, the graphite material should include at least one of hydroxylated graphene and other graphite materials. Specifically, the graphite material can be a mixture of hydroxylated graphene and expanded graphite, a mixture of hydroxylated graphene and flake graphite, a mixture of hydroxylated graphene and spherical graphite, a mixture of hydroxylated graphene, expanded graphite and flake graphite, a mixture of hydroxylated graphene, expanded graphite and spherical graphite, a mixture of hydroxylated graphene, flake graphite and spherical graphite, The mixture of graphite can be a mixture of hydroxylated graphene, expanded graphite, flake graphite and spherical graphite, wherein the first preset ratio of the graphite material to the resin material is 80-95 parts by weight and 5-20 parts by weight of the resin material, that is, the graphite material can take any value between 80 and 95 parts, illustratively, it can take 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95 parts, etc. The weight of the graphite material should correspond to the weight of the resin material. In other words, when the graphite material is 88 parts by weight, the weight of the resin material should be 12 parts.

[0026] In the embodiment of the present application, the resin material can be either silicone resin alone or a mixed resin of silicone resin and phenolic resin according to a second preset ratio, wherein the second preset ratio is any value between 5-1:1 or 1:1-5. For example, the second preset ratio can be 5:1, 4:1, 3:1, 2:1, 1:1, etc., or the second preset ratio can also be 1:1, 1:2, 1:3, 1:4, 1:5, etc.

[0027] In an embodiment of the present application, the molding temperature of the mixed material is any value between 130-180°C, and for example, it can be 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, etc.; the molding pressure is any value between 10-140MPa, and for example, it can be 10MPa, 30MPa, 50MPa, 70MPa, 90MPa, 110MPa, 130MPa, 140MPa, etc.; the molding time is any value between 30-300s, and for example, it can be 30s, 60s, 90s, 120s, 150s, 180s, 210s, 240s, 270s, 300s, etc.

[0028] In an embodiment of the present application, the curing temperature is any value between 180-250°C, and for example, it can be 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 240°C, 250°C, etc.; the curing time is any value between 3-8h, and for example, it can be 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, etc.

[0029] In the above embodiment, the graphite material and the resin material are mixed. Since the graphite material contains hydroxylated graphene, the silicone resin can chemically react with the hydroxyl groups in the hydroxylated graphene, so that the resin phase and the graphite phase have better compatibility, which greatly reduces the gap between the resin phase and the graphite phase, and the prepared graphite composite bipolar plate has better air tightness.

[0030] The embodiment of the present application further provides a graphite composite bipolar plate, which is prepared by the graphite composite bipolar plate preparation method described above.

[0031] Based on the description of the beneficial technical effects of the above-mentioned method for preparing a graphite composite bipolar plate, the graphite composite bipolar plate prepared by this method has the same beneficial technical effects, which will not be repeated here.

[0032] The following examples describe the disclosure of the present application in more detail, and these examples are merely illustrative, as it will be apparent to those skilled in the art that various modifications and variations within the scope of the disclosure of the present application are possible. Unless otherwise stated, all reagents and raw materials used in the examples are commercially available or synthesized according to conventional methods, and the instruments and equipment used in the examples are commercially available.

[0033] Example 1

[0034] (1) at a preset temperature of 60° C., 90 parts by weight of a graphite material and 10 parts by weight of a resin material are mixed by physical mixing to obtain a mixed material, wherein the resin material is a 1:1 ratio of an organic silicone resin and a phenolic resin, and the graphite material is a 1:1 ratio of hydroxylated graphene and expanded graphite;

[0035] (2) The mixed material is molded at a molding temperature of 150° C., a molding pressure of 35 MPa, and a molding time of 100 s, and then the molded mixed material is cured at a curing temperature of 220° C. and a curing time of 6 h to obtain a graphite composite bipolar plate.

[0036] Example 2

[0037] (1) Under a preset temperature of 50° C., 85 parts by weight of a graphite material and 15 parts by weight of a resin material are physically mixed to obtain a mixed material, wherein the resin material is a 2:1 ratio of a silicone resin and a phenolic resin, and the graphite material is a 3:1 ratio of hydroxylated graphene and flake graphite;

[0038] (2) The mixed material is molded at a molding temperature of 130° C., a molding pressure of 10 MPa, and a molding time of 120 s, and then the molded mixed material is cured at a curing temperature of 200° C. and a curing time of 8 h to obtain a graphite composite bipolar plate.

[0039] Example 3

[0040] (1) physically mixing 80 parts by weight of a graphite material and 20 parts by weight of a resin material at a preset temperature of 80° C. to obtain a mixed material, wherein the resin material is a 2:1 ratio of an organic silicone resin and a phenolic resin, and the graphite material is a 2:1 ratio of hydroxylated graphene and expanded graphite;

[0041] (2) The mixed material is molded at a molding temperature of 180° C., a molding pressure of 45 MPa, and a molding time of 30 seconds, and then the molded mixed material is cured at a curing temperature of 250° C. and a curing time of 3 hours to obtain a graphite composite bipolar plate.

[0042] Comparative Example 1

[0043] The difference between Comparative Example 1 and Example 1 is that no phenolic resin is added in Comparative Example 1, and the subsequent steps are the same as those in Example 1.

[0044] Comparative Example 2

[0045] The difference between Comparative Example 2 and Example 2 is that hydroxylated graphene is not added in Comparative Example 2, and the subsequent steps are the same as those in Example 2.

[0046] Comparative Example 3

[0047] The difference between Comparative Example 3 and Example 3 is that no phenolic resin and hydroxylated graphene are added in Comparative Example 3, and the subsequent steps are the same as those in Example 3.

[0048] Based on GB / T 20042.6-2024, the graphite composite bipolar plates obtained in Examples 1-3 and Comparative Examples 1-3 were tested for flexural strength, electrical properties, and air tightness. The test results are shown in Table 1.

[0049] Table 1 Test results of graphite composite bipolar plates obtained in Examples 1-3 and Comparative Examples 1-3

[0050]

[0051] It can be seen from Table 1 that the graphite composite bipolar plates obtained in Examples 1-3 all have excellent flexural strength, electrical properties and air tightness, while the flexural strength of the graphite composite bipolar plate obtained in Comparative Example 1 is lower than that in Example 1, the flexural strength, electrical properties and air tightness of the graphite composite bipolar plate obtained in Comparative Example 2 are all lower than those in Example 2, and the flexural strength, electrical properties and air tightness of the graphite composite bipolar plate obtained in Comparative Example 3 are all lower than those in Example 3.

[0052] Since no phenolic resin is added in Comparative Example 1, and the phenolic resin can form a large skeleton structure with the silicone resin, based on the large skeleton structure, the graphite composite bipolar plate can provide higher strength. Therefore, although the electrical properties and air tightness of the graphite composite bipolar plate obtained in Comparative Example 1 are not much different from those of Example 1, its flexural strength is less than that of Example 1.

[0053] Since no hydroxylated graphene is added in Comparative Example 2, and the hydroxyl groups on the hydroxylated graphene molecules can react with the silicone resin, so that the resin phase and the graphite phase can be combined by chemical bonds, thereby providing the prepared graphite composite bipolar plate with better flexural strength, electrical properties and air tightness, therefore, the flexural strength, electrical properties and air tightness of the graphite composite bipolar plate obtained in Comparative Example 2 are not as good as those in Example 2;

[0054] Since Comparative Example 3 neither adds phenolic resin that forms a large skeleton structure with the silicone resin nor adds hydroxylated graphene that reacts with the silicone resin to chemically bond the resin phase and the graphite phase, the flexural strength, electrical properties and air tightness of the graphite composite bipolar plate obtained in Comparative Example 3 are inferior to those in Example 3.

[0055] The above is a detailed introduction to a method for preparing a graphite composite bipolar plate and a graphite composite bipolar plate provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the core idea of ​​the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A method for preparing a graphite composite bipolar plate, characterized in that: The method comprises the following steps: S100, fully mixing a resin material and a graphite material in a first preset ratio at a preset temperature to obtain a uniform mixed material, wherein the resin material is an organic silicone resin or an organic silicone resin and a phenolic resin in a second preset ratio, and the graphite material includes hydroxylated graphene and at least one of expanded graphite, flake graphite, spherical graphite, graphene, carbon nanotubes, and artificial graphite; S200, molding and curing the mixed material to obtain a graphite composite bipolar plate.

2. The method for preparing a graphite composite bipolar plate according to claim 1, characterized in that: In the step S100, the second preset ratio of the silicone resin to the phenolic resin is 5-1:1 or 1:1-5, and the preset temperature is 50-80°C.

3. The method for preparing a graphite composite bipolar plate according to claim 2, characterized in that: In the step S100, the resin material and the graphite material are mixed in a manner including physical mixing, solvent mixing, and grinding mixing.

4. The method for preparing a graphite composite bipolar plate according to claim 3, characterized in that: In the step S100, the resin material and the graphite material are calculated by weight, with the graphite material accounting for 80-95 parts and the resin material accounting for 5-20 parts.

5. The method for preparing a graphite composite bipolar plate according to claim 4, characterized in that: In the step S200, the molding temperature is 130-180°C, the molding pressure is 10-140 MPa, and the molding time is 30-300 seconds.

6. The method for preparing a graphite composite bipolar plate according to claim 5, characterized in that: In the step S200, the curing temperature is 180-250° C. and the curing time is 3-8 hours.

7. A graphite composite bipolar plate, characterized in that: The graphite composite bipolar plate is prepared by the graphite composite bipolar plate preparation method according to any one of claims 1 to 6.

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