A material formulation for a flexible artificial graphene bipolar plate and a method for preparing the same

Abstract

This invention belongs to the field of fuel cell technology, and particularly relates to a material formulation and preparation method for a flexible artificial graphene bipolar plate. This invention provides a material formulation for a flexible artificial graphene bipolar plate that effectively improves the toughness and reduces the brittleness of the bipolar plate by adding nano-graphene powder and modified silicone resin. This invention also provides a preparation method for a flexible artificial graphene bipolar plate, which improves the electrical conductivity, thermal conductivity, and corrosion resistance of the flexible artificial graphene bipolar plate by sequentially stirring, drying, pressing, polishing, and processing flow channels. Furthermore, it utilizes a specially structured mixer to achieve thorough and rapid stirring.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fuel cells, and particularly relates to a material formula of a flexible artificial graphene bipolar plate and a preparation method thereof. BACKGROUND

[0002] The bipolar plate is an important component for conveying and distributing fuel. The existing bipolar plate raw materials include carbon materials, metal materials, and composite materials of metal and carbon. However, the bipolar plates made of the above raw materials have problems such as large weight, poor heat dissipation, short service life, etc., and are not suitable for mass production and use. Therefore, at present, graphene bipolar plates are usually used. The existing graphene bipolar plates include hard graphene bipolar plates and flexible graphene bipolar plates. The hard graphene has good electrical conductivity, thermal conductivity and corrosion resistance, but the brittleness of the hard graphene causes processing difficulties and high processing costs. The flexible graphene has good electrical conductivity, thermal conductivity and corrosion resistance, and also has certain toughness, and is suitable for the production of fuel cell bipolar plates.

[0003] However, the existing common graphene bipolar plates are relatively fragile and have poor toughness, and can be easily cracked by slight extrusion, increasing the processing difficulty and the processing cost.

[0004] Therefore, in view of the above, there is an urgent need for a flexible artificial graphene bipolar plate which has good electrical conductivity, thermal conductivity and corrosion resistance, good toughness, and does not increase the processing difficulty and the processing cost. SUMMARY

[0005] The present application provides a material formula of a flexible artificial graphene bipolar plate, which comprises artificial isostatic pressing graphite powder, nano graphene powder, natural graphite powder, polystyrene resin powder, modified silica gel resin, and granulating adhesive polyvinyl alcohol, and is combined with a specific structure of a stirrer to fully stir the above raw materials.

[0006] The present application also provides a preparation method of a flexible artificial graphene bipolar plate, which can effectively prepare a preformed material by adding artificial isostatic pressing graphite powder, nano graphene powder, natural graphite powder, polystyrene resin powder and modified silica gel resin, dissolving granulating adhesive polyvinyl alcohol in pure water, finally spraying the polyvinyl alcohol aqueous solution on the preformed material in a spraying manner to effectively prepare granulating powder, and then effectively preparing a sheet-shaped blank by pressing and heating the granulating powder, and effectively preparing a flexible artificial graphene bipolar plate by polishing and processing the flow channel of the blank.

[0007] comprising by weight:

[0008] 18-20 parts of artificial isostatic pressing graphite powder,

[0009] Nano-graphene powder 38-40 parts,

[0010] Natural graphite powder 12-15 parts,

[0011] Polyphenylacrylonitrile resin powder 10-12 parts,

[0012] Modified silica gel resin 6-8 parts,

[0013] Granulation binder polyvinyl alcohol 3-5 parts.

[0014] In the present application, the natural graphite powder has good heat transfer performance and electrical conductivity compared with the commonly used artificial graphite powder, and has good lubricity and plasticity.

[0015] The granulation binder polyvinyl alcohol is dissolved in water as an adhesive, so that the production process is simple, non-corrosive, and has good drying and molding effect.

[0016] In addition, the modified silica gel resin is a modified silica resin network structure copolymer. After the resin is formed, it has high hardness, strong adhesion and good transparency, and is a good temperature-resistant raw material. In high-temperature pressing, it prevents the deformation and rupture of flaky graphite materials.

[0017] Finally, the nano-graphene powder is one of the materials with the highest known strength, and also has good toughness and can be bent, effectively improving the toughness of the flexible graphene bipolar plate texture, and showing good solubility in non-polar solvents, which is conducive to the full mixing with other raw materials.

[0018] Further preferred technical solutions are that the particle size of the artificial isostatic pressing graphite powder is 25-30 microns, the particle size of the nano-graphene powder is 10-100 nanometers, the particle size of the natural graphite powder is 45-50 microns, and the particle size of the polyphenylacrylonitrile resin powder is 5-10 microns.

[0019] In the present application, the above-mentioned various raw materials can improve the toughness and texture of the flexible graphene bipolar plate, and achieve the effect of being hard and not easy to break.

[0020] Further preferred technical solutions are that the purity of the natural graphite powder is 99.95%.

[0021] In the present application, the high-purity natural graphite powder has good lubricity and plasticity, which is of great help to the production of flexible graphene bipolar plates and effectively improves the mixing degree of various raw materials.

[0022] A preparation method of a flexible artificial graphene bipolar plate, comprising the following steps in sequence:

[0023] S1, add artificial isostatic graphite powder, nano graphene powder, natural graphite powder, polystyrene phenyl resin powder and modified silica gel resin, stirring machine stirring 40-50 min, get preform material;

[0024] S2, the granulating binder polyvinyl alcohol is added to the pure water and dissolved by heating, to obtain a polyvinyl alcohol aqueous solution, then the polyvinyl alcohol aqueous solution is sprayed onto the preform material, dried, agglomerated to obtain the final granulation powder;

[0025] S3, the granulation powder is added to the isostatic press, and the polyphenyl polystyrene is heated and melted to bond with other materials and combine into a whole sheet shape;

[0026] S4, the blank is taken out, the surface flatness is processed by the grinding machine, and the runner is processed by the machining center.

[0027] In the application, polyvinyl alcohol is dissolved in water, and the polyvinyl alcohol aqueous solution is used as a common adhesive for dry forming granulation, which has sufficient viscosity to ensure good formability of the granulation powder, and the production process is simple.

[0028] Further preferred technical solutions are that in S1, the stirring machine comprises a stirring machine body, a stirring unit arranged in the stirring machine body, a guide unit arranged in the stirring unit, and a flow guide unit arranged on the stirring unit.

[0029] Further preferred technical solutions are that the stirring unit comprises a driving motor, a stirring shaft rotating under the driving of the driving motor, and a stirring paddle fixedly arranged on the stirring shaft.

[0030] Further preferred technical solutions are that the guide unit comprises a fixed shaft arranged in the stirring shaft, and a shafted auger arranged in the fixed shaft, the shafted auger rotates under the driving of the driving motor, and the outer side of the shafted auger is in close contact with the inner wall of the fixed shaft.

[0031] In the application, the powder at the bottom of the stirring machine body is circulated and delivered from bottom to top by the shafted auger, so that the powder can be more fully stirred, and the powder accumulation at the bottom of the stirring machine body is prevented, which affects the quality ratio of the required powder.

[0032] Further preferred technical solutions are that the flow guide unit comprises a plurality of through holes a opened in the stirring shaft, a plurality of through holes b opened in the fixed shaft, and a flow guide plate fixedly arranged below the through holes a, the flow guide plate is inclinedly arranged on the stirring shaft, and the through holes a and the through holes b cooperate.

[0033] In the present application, since the powder in the fixed shaft needs to flow out of the through hole a and the through hole b under the action of the shaft auger, a guide plate is needed to guide the powder into the mixer body, accelerate the flow speed of the powder and improve the stirring efficiency.

[0034] Further preferred technical solutions are that in S2, the mass ratio of the granulating binder polyvinyl alcohol to pure water is 1:25-30, and the heating temperature is 65-75 DEG C.

[0035] In the present application, since the preparation of the polyvinyl alcohol aqueous solution needs to dissolve polyvinyl alcohol in water, in order to completely dissolve the polyvinyl alcohol in pure water, it is generally heated to 65-75 DEG C to achieve the effect of rapid and sufficient dissolution.

[0036] Further preferred technical solutions are that in S3, the pressing pressure is controlled between 2.5t-3t, the pressing time is 40s, and the heating temperature is 250 DEG C.

[0037] In the present application, since the granulating powder needs to be formed, the granulating powder is pressed into a sheet under high pressure and high temperature conditions to improve the toughness and hard texture of the bipolar plate and avoid breaking during the pressing process.

[0038] The present application has the following advantages.

[0039] First, the newly added nano graphene powder and modified silica gel resin in the preparation of the flexible artificial graphene bipolar plate can effectively improve the toughness of the bipolar plate and reduce the brittleness of the bipolar plate.

[0040] Second, the mixer can transport the powder at the bottom of the mixer body from bottom to top under the guidance of the shaft auger, and then output to the mixer body through the through hole a and the through hole b for stirring. Through the multiple circulation and reciprocating stirring mode, the powder can be fully stirred and mixed to provide the fusion degree of the powder.

[0041] Third, the mixer can also improve the falling speed of the powder under the guiding action of the guide plate, accelerate the stirring speed and improve the stirring efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The performance test results of the flexible artificial graphene bipolar plate in the three embodiments of the present application.

[0043] Figure 2 The structure diagram of the mixer in the present application.

[0044] Figure 3 The structure diagram of the stirring unit and the guide unit in the present application.

[0045] Figure 4A structure diagram of the guide unit in the application.

[0046] Figure 5 A use diagram of the powder circulating and stirring in the body of the mixer.

[0047] In the drawings, the components represented by the respective reference numerals are as follows: the body of the mixer 1, the stirring unit 2, the guide unit 3, the guide unit 4, the driving motor 21, the stirring shaft 22, the stirring paddle 23, the fixed shaft 31, the shafted screw 32, the through hole a 41, the through hole b 42, and the guide plate 43. DETAILED DESCRIPTION

[0048] The following description is merely exemplary of the application and is not intended to limit the application.

[0049] Example 1

[0050] As shown in the accompanying drawings, Figures 1-5 A material formula of a flexible artificial graphene bipolar plate, comprising the following components by weight: 18 parts of artificial isostatic pressing graphite powder, 38 parts of nano graphene powder, 14 parts of natural graphite powder, 11 parts of polystyrene resin powder, 7 parts of modified silica gel resin, and 5 parts of granulating adhesive polyvinyl alcohol.

[0051] The preparation method of the flexible artificial graphene bipolar plate comprises the following steps in sequence:

[0052] S1, add artificial isostatic pressing graphite powder, nano graphene powder, natural graphite powder, polystyrene resin powder, and modified silica gel resin, and stir for 35 minutes by a mixer to obtain a pre-prepared material, wherein the stirring rate is 200 r / min.

[0053] S2, add the granulating adhesive polyvinyl alcohol into pure water and heat to dissolve, and dissolve for 30 minutes to obtain a polyvinyl alcohol aqueous solution, wherein the mass ratio of polyvinyl alcohol to pure water is 1:20, and the heating temperature is 65°C. Then, the polyvinyl alcohol aqueous solution is sprayed onto the pre-prepared material, and after drying and agglomeration, a granulating powder is obtained;

[0054] S3, add the granulating powder into an isostatic pressing machine, heat and melt the polystyrene to bond and combine with other materials into an integral sheet, wherein the pressing pressure is controlled at 2.5 t, the pressing time is 20 s, and the heating temperature is 220°C.

[0055] In S1, the mixer comprises a mixer body 1, a stirring unit 2 arranged in the mixer body 1, a guide unit 3 arranged in the stirring unit 2, and a guide unit 4 arranged on the stirring unit 2.

[0056] The stirring unit 2 comprises a driving motor 21, a stirring shaft 22 rotating under the driving of the driving motor 21, and a stirring paddle 23 fixedly arranged on the stirring shaft 22.

[0057] The guide unit 3 includes a fixed shaft 31 disposed within the stirring shaft 22, and a shafted auger 32 disposed within the fixed shaft 31. The shafted auger 32 rotates under the drive of the drive motor 21, and the outer side of the shafted auger 32 is in contact with the inner wall of the fixed shaft 31.

[0058] In this embodiment, by using a shafted auger 32 to circulate and transport the powder from the bottom of the mixer body 1 to the top, the powder can be mixed more thoroughly. This speeds up the mixing process and prevents the powder from accumulating at the bottom of the mixer body 1, thus affecting the required powder mass ratio for production.

[0059] The flow guiding unit 4 includes several through holes a41 formed on the stirring shaft 22, several through holes b42 formed on the fixed shaft 31, and a flow guiding plate 43 fixedly arranged below the through holes a41. The flow guiding plate 43 is inclinedly arranged on the stirring shaft 22, and the through holes a41 and through holes b42 cooperate with each other.

[0060] In this embodiment, since the powder in the fixed shaft 31 needs to flow out from the through hole a41 and through hole b42 under the action of the shaft auger 32, the guide plate 43 is needed to guide the powder into the mixer body 1 to speed up the flow of the powder and improve the mixing efficiency.

[0061] Finally, the flexible artificial graphene bipolar plate obtained in this embodiment was subjected to performance tests, including impact strength, compressive strength, and flexural strength. The test results are attached. Figure 1 .

[0062] Example 2

[0063] As attached Figures 1-5 As shown, the only difference from Example 1 is the material composition of the following flexible artificial graphene bipolar plate and the working parameters of the pressing process.

[0064] A material formulation for a flexible artificial graphene bipolar plate includes the following components by weight: 20 parts of artificial isostatic graphite powder, 39 parts of nano-graphene powder, 14 parts of natural graphite powder, 11 parts of polystyrene-propylene resin powder, 7 parts of modified silicone resin, and 5 parts of granulation binder polyvinyl alcohol.

[0065] The preparation method of this flexible artificial graphene bipolar plate includes the following steps in sequence:

[0066] S1. Add artificial isostatic graphite powder, nano graphene powder, natural graphite powder, polystyrene-propylene resin powder, and modified silicone resin, and stir in a mixer for 40 minutes to obtain the preformed material, wherein the stirring speed is 300 r / min.

[0067] S2. Add the granulation binder polyvinyl alcohol to pure water and heat to dissolve. Dissolve for 40 minutes to obtain a polyvinyl alcohol aqueous solution. The mass ratio of polyvinyl alcohol to pure water is 1:25. The heating temperature is 70℃. Then spray the polyvinyl alcohol aqueous solution onto the preformed material, and after drying and agglomeration, obtain granulated powder.

[0068] S3. Add the granulated powder to an isostatic press, heat and melt the polystyrene-propylene to bond it with other materials and combine it into a whole sheet, wherein the pressure is controlled at 2.8t, the pressing time is 30s, and the heating temperature is 230℃.

[0069] Finally, the flexible artificial graphene bipolar plate obtained in this embodiment was subjected to performance tests, including impact strength, compressive strength, and flexural strength. The test results are attached. Figure 1 .

[0070] Example 3

[0071] As attached Figures 1-5 As shown, the only difference from Example 1 is the material composition of the following flexible artificial graphene bipolar plate and the working parameters of the pressing process.

[0072] A material formulation for a flexible artificial graphene bipolar plate includes the following components by weight: 20 parts of artificial isostatic graphite powder, 40 parts of nano-graphene powder, 15 parts of natural graphite powder, 12 parts of polystyrene-propylene resin powder, 8 parts of modified silicone resin, and 5 parts of granulation binder polyvinyl alcohol.

[0073] The preparation method of this flexible artificial graphene bipolar plate includes the following steps in sequence:

[0074] S1. Add artificial isostatic graphite powder, nano-graphene powder, natural graphite powder, polystyrene-propylene resin powder, and modified silicone resin, and stir in a mixer for 45 minutes to obtain the preformed material, wherein the stirring speed is 400 r / min.

[0075] S2. Add the granulation binder polyvinyl alcohol to pure water and heat to dissolve. Dissolve for 45 minutes to obtain a polyvinyl alcohol aqueous solution. The mass ratio of polyvinyl alcohol to pure water is 1:30. The heating temperature is 75℃. Then spray the polyvinyl alcohol aqueous solution onto the preformed material, and after drying and agglomeration, obtain granulated powder.

[0076] S3. Add the granulated powder to an isostatic press, heat and melt the polystyrene-propylene to bond it with other materials and combine it into a whole sheet, wherein the pressure is controlled at 3t, the pressing time is 40s, and the heating temperature is 250℃.

[0077] Finally, the performance of the flexible artificial graphene bipolar plates finally obtained in the embodiment is tested, and the test items include impact strength, compressive strength and bending strength, and the test results are shown in the attached Figure 1 .

[0078] From the detection data in the attached Figure 1 , the following conclusions can be drawn.

[0079] First, the three groups of flexible artificial graphene bipolar plates in the embodiment have the advantages of good toughness, low brittleness and not easy to break.

[0080] Second, the three groups of flexible artificial graphene bipolar plates in the embodiment have the advantages of good compressive resistance and large overall strength.

[0081] The embodiments of the application are described in detail above in combination with the drawings, but the application is not limited to the above-mentioned embodiments, and various modifications can be made within the knowledge of those skilled in the art in the technical field without departing from the purpose of the application. These are all non-creative modifications, and as long as they are within the scope of the claims of the application, they are protected by the patent law.

Claims

1. A method of making a flexible artificial graphene bipolar plate, characterized by, The composition includes the following components by weight: 18-20 parts of artificial isostatic graphite powder, 38-40 parts of nano graphene powder, 12-15 parts of natural graphite powder, 10-12 parts of polystyrene resin powder, 6-8 parts of modified silica gel resin, and 3-5 parts of granulation binder polyvinyl alcohol; the particle size of the artificial isostatic graphite powder is 25-30 microns, the particle size of the nano graphene powder is 10-100 nanometers, the particle size of the natural graphite powder is 45-50 microns, and the particle size of the polystyrene resin powder is 5-10 microns; the purity of the natural graphite powder is 99.95%; sequentially comprising the following steps: S1, adding artificial isostatic graphite powder, nano graphene powder, natural graphite powder, polystyrene resin powder and modified silica gel resin, stirring by a stirrer for 40-50 min to obtain a preform material; S2, dissolving the granulation binder polyvinyl alcohol in pure water by heating to obtain a polyvinyl alcohol aqueous solution, then spraying the polyvinyl alcohol aqueous solution onto the preform material, drying and agglomerating to obtain the final granulation powder; S3, adding the granulation powder into an isostatic press, heating and melting the polystyrene to bond with other materials and form a monolithic sheet; S4, taking out the blank, processing the surface flatness by a grinding machine and processing the runner by a machining center.

2. The method of claim 1, wherein the method further comprises: In S1, the stirrer comprises a stirrer body (1), a stirring unit (2) arranged in the stirrer body (1), a guide unit (3) arranged in the stirring unit (2), and a flow guide unit (4) arranged on the stirring unit (2).

3. The method of claim 2, wherein the method further comprises: The stirring unit (2) comprises a driving motor (21), a stirring shaft (22) rotating under the driving of the driving motor (21), and a stirring paddle (23) fixedly arranged on the stirring shaft (22).

4. The method of claim 2, wherein the method further comprises: The guide unit (3) comprises a fixed shaft (31) arranged in the stirring shaft (22), and a shafted auger (32) arranged in the fixed shaft (31), the shafted auger (32) rotating under the driving of the driving motor (21), and the outer side of the shafted auger (32) being fitted with the inner wall of the fixed shaft (31).

5. The method of claim 2, wherein the method further comprises: The flow guide unit (4) comprises a plurality of through holes a (41) opened on the stirring shaft (22), a plurality of through holes b (42) opened on the fixed shaft (31), and a flow guide plate (43) fixedly arranged below the through holes a (41), the flow guide plate (43) being obliquely arranged on the stirring shaft (22), and the through holes a (41) and the through holes b (42) being matched.

6. The method of claim 1, wherein: In S2, the mass ratio of the granulation binder polyvinyl alcohol to pure water is 1:25-30, and the heating temperature is 65-75°C.

7. The method of claim 1, wherein the method further comprises: In S3, the pressing pressure is controlled between 2.5t and 3t, the pressing time is 40s, and the heating temperature is 250°C.

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