Composite graphite-based material for bipolar plates and method for its production

Abstract

The application provides a composite graphite-based material for a bipolar plate and a preparation method thereof, the composite graphite-based material for the bipolar plate comprises the following raw materials in parts by weight: 80-100 parts of graphite, 8-15 parts of 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide, 5-10 parts of a conductive agent, and 10-30 parts of a resin. The composite graphite-based material for the bipolar plate has good conductivity, air tightness and mechanical strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bipolar plate materials of fuel cells, in particular to a composite graphite-based material for bipolar plates and a preparation method thereof. BACKGROUND

[0002] Fuel cells are key industries in the field of new energy and can be widely applied in the fields of automobiles, aerospace, military, various electronic intelligent terminals, etc. In fuel cells, bipolar plates are one of the core components, which mainly function to separate reaction gases, uniformly introduce reaction gases, collect and conduct electric current, support membrane electrodes, and realize rapid drainage and heat dissipation of fuel cell systems.

[0003] At present, the most widely used bipolar plate material is graphite bipolar plate, which specifically includes engraved hard graphite bipolar plate, flexible graphite bipolar plate, and composite graphite bipolar plate. Among them, the composite graphite bipolar plate has the advantages of one-time forming and simple process, and therefore has good prospects for large-scale industrial production.

[0004] The composite graphite-based material is obtained by hot pressing after mixing graphite powder and adhesive resin. The graphite powder has good electrical conductivity, but the mechanical strength of pure graphite plate is poor and it is difficult to meet the air tightness requirement of the bipolar plate, so adhesive resin needs to be added to improve the mechanical strength and air tightness. The high electrical conductivity of the bipolar plate requires increasing the content of graphite, but the air tightness and mechanical strength of the bipolar plate require increasing the content of resin.

[0005] Therefore, it is urgent to provide a composite graphite-based material for bipolar plates, which can better balance the electrical conductivity, air tightness and mechanical strength of the bipolar plate. SUMMARY

[0006] The purpose of the present application is to provide a composite graphite-based material for bipolar plates to solve the problem that the composite graphite-based material in the prior art cannot balance the electrical conductivity, air tightness and mechanical strength of the bipolar plate.

[0007] To solve the above technical problems, the technical solutions of the present application are as follows:

[0008] A composite graphite-based material for bipolar plates comprises the following raw materials by weight:

[0009] Graphite 80-100 parts, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide 8-15 parts, conductive agent 5-10 parts, and resin 10-30 parts.

[0010] Preferably, the resin is phenolic resin or a mixture of phenolic resin and epoxy resin.

[0011] Preferably, the conductive agent is polyaniline.

[0012] Preferably, the composite graphite-based material for bipolar plates further comprises 0.6-1.8 parts of an intercalation regulator; the intercalation regulator is one or more of 1-naphthyl ammonium bromide, 2-naphthyl ammonium bromide, and 1-(naphthoxy)acetic acid hydrazine.

[0013] Preferably, the intercalation regulator is a mixture of 1-naphthyl ammonium bromide and 1-(naphthoxy)acetic acid hydrazine in a weight ratio of 1:(3.2-3.8).

[0014] Preferably, the intercalation regulator is a mixture of 2-naphthyl ammonium bromide and 1-(naphthoxy)acetic acid hydrazine in a weight ratio of 1:(2.5-3.0).

[0015] Preferably, the composite graphite-based material for bipolar plates further comprises 1-3 parts of 1,4-diamino-2,3-dihydroanthraquinone.

[0016] The present application provides a preparation method of a composite graphite-based material for bipolar plates, comprising the following steps: uniformly mixing graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, a conductive agent, and a resin, and hot-pressing to form a product.

[0017] Preferably, the preparation method of the composite graphite-based material for bipolar plates comprises the following steps:

[0018] (1) uniformly mixing graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, and water to obtain a mixture;

[0019] (2) uniformly mixing a resin, a conductive agent, and a dispersant, and adding them to the mixture obtained in step (1) to obtain a mixed slurry;

[0020] (3) drying and hot-pressing the mixed slurry obtained in step (2) to obtain the product.

[0021] Preferably, the preparation method of the composite graphite-based material for bipolar plates comprises the following steps:

[0022] (1) uniformly mixing graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, an intercalation regulator, and water to obtain a mixture;

[0023] (2) uniformly mixing a resin, a conductive agent, and a dispersant, and adding them to the mixture obtained in step (1) to obtain a mixed slurry;

[0024] (3) drying and hot-pressing the mixed slurry obtained in step (2) to obtain the product.

[0025] Preferably, in step (1), the water accounts for 10-15wt% of the mixture.

[0026] Preferably, step (1) is specifically as follows: taking graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, water, mixing uniformly, and ball-milling the obtained mixture at a rotating speed of 500-800 r / min for 30-90 min.

[0027] Preferably, in step (2), the dispersant is acetone; and the mass ratio of the acetone to the resin is (1.5-2.0):1.

[0028] Preferably, in step (3), the drying temperature is 60-70℃, and the time is 2-4 h.

[0029] Preferably, in step (3), the hot-pressing forming is performed at a pressure of 30-50 Mpa and a temperature of 160-180℃ for 30-60 min.

[0030] The above scheme of the present application at least includes the following beneficial effects:

[0031] (1) The composite graphite-based material for bipolar plate of the present application comprises the following raw materials by weight: graphite 80-100 parts, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide 8-15 parts, conductive agent 5-10 parts, and resin 10-30 parts. The composite graphite-based material for bipolar plate has good electrical conductivity, air tightness and mechanical strength.

[0032] The 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide as an intercalating agent has trimethyl ammonium ions, which can penetrate into the interlayer of the graphite through cation-π interaction, reduce the surface energy of the system, greatly improve the dispersibility of graphite in water, and reduce the agglomeration of graphite. Meanwhile, the naphthalene ring of the naphthoxy group is a fused ring aromatic hydrocarbon, which has a conjugated structure with the layered structure of graphite and has good interfacial bonding force with the interlayer of graphite, so that a relatively stable dispersion state can be maintained. Meanwhile, the 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide as a surfactant has good compatibility with the resin, improves the contact area of the graphite and the resin in the mixed slurry, so that the conductive path can be more fully formed after hot-pressing forming, and the electrical conductivity is improved.

[0033] Especially, when the resin is or contains phenolic resin, the long-chain decyloxy and naphthoxy of the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide can be close to the phenolic resin under the hydrophobic effect, so that the interface gap between the graphite and the resin is reduced, thereby reducing the interface resistance. In addition, the molecular structure of the phenolic resin is reticular, and a three-dimensional reticular structure with high cross-linking degree is formed between the molecules after molding, which has high mechanical strength and rigidity, strong stability, good heat resistance and chemical corrosion resistance, and no by-product is generated during curing. However, due to the presence of a large number of rigid benzene ring structures, the obtained bipolar plate has high brittleness. The 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide has a flexible long-chain alkyl group, which can form a cross-linked structure with the resin to effectively transfer stress and improve the toughness of the composite material, thereby greatly improving the mechanical properties of the bipolar plate.

[0034] In addition, the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide can effectively reduce the penetration channels of gas molecules by enhancing the interfacial bonding force between the graphite and the resin and adjusting the three-dimensional cross-linked structure formed by the resin, so as to improve the gas tightness.

[0035] (2) The composite graphite-based material for bipolar plates of the present application, wherein the conductive agent is polyaniline. The 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide located between the layers of the graphite can be combined with the polyaniline particles through electrostatic or hydrogen bonding due to the presence of quaternary ammonium salt molecules, so that the polyaniline is uniformly distributed on the surface of the graphite and fills the gaps between the graphite particles, thereby increasing the conductive contact points and forming a more continuous and compact conductive network. At the same time, the steric hindrance effect produced by the long-chain structure of the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide is beneficial to maintaining a certain distance between the polyaniline particles, so that they are uniformly dispersed.

[0036] (3) The composite graphite-based material for bipolar plates of the present application further comprises 0.5-1.8 parts of an intercalation regulator; the intercalation regulator is one or more of 1-naphthyl ammonium bromide, 2-naphthyl ammonium bromide, and 1-(naphthoxy)acetic acid hydrazine. When the intercalation regulator is 1-naphthyl ammonium bromide or 2-naphthyl ammonium bromide, due to its structure being smaller than that of the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide, it is easier to enter the narrow space between the graphite layers through cation-pi interaction, and cooperates with the long-chain structure of the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide, which can increase the intercalation uniformity of the graphite and improve the intercalation effect. When the intercalation regulator is 1-(naphthoxy)acetic acid hydrazine, due to the ball milling process causing more defects and edge sites of the graphite, and the hydrazine group has certain chemical activity and electron-donating ability, it is easy to combine with the defects and edge sites of the graphite, so that the originally relatively uniform charge distribution of the graphite forms a charge center, the interaction between the intercalation agents with charges is enhanced, the charge distribution on the surface of the graphite is changed, thereby guiding the intercalation agent to be closer to the surface of the graphite and diffuse between the layers. When the intercalation regulator is 1-naphthyl ammonium bromide, 1-(naphthoxy)acetic acid hydrazine, or 2-naphthyl ammonium bromide, 1-(naphthoxy)acetic acid hydrazine cooperates with the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide, which can improve the intercalation effect, optimize the electron transport channel, and the intercalation-treated graphite has better conductivity in the composite material formed with the resin.

[0037] (4) The preparation method of the composite graphite-based material for bipolar plates of the present application, step (1) is specifically as follows: taking graphite, 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide, and water, mixing uniformly, and ball milling the obtained mixture at a speed of 500-800 r / min for 30-90 min. The physical shearing force generated by the ball milling causes the graphite layers to slide, and further causes the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide to be more closely and fully combined with the layered structure of the graphite, so that the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide is uniformly intercalated between the layers of the graphite.

[0038] (1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide is uniformly intercalated between the layers of the graphite. DETAILED DESCRIPTION

[0039] Unless otherwise indicated, the various embodiments of the present application are practiced under conventional conditions or manufacturer's recommended conditions. Unless otherwise indicated, the reagents or instruments used are conventional products available on the market, and the use of raw materials of different manufacturers or models does not affect the implementation and technical effect of the technical solutions of the present application.

[0040] The 4-(1-naphthoxy-5-decoxy)butyltrimethylammonium bromide described in the following examples has the structure shown in formula (I):

[0041]

[0042] The 4-(1-naphthoxy-5-decyloxy)butyltrimethylammonium bromide is a product of existing technology and can also be prepared using existing technology. For example, it can be synthesized in the following manner:

[0043]

[0044] The structural formula of the 1,4-diamino-2,3-dihydroanthraquinone is as follows:

[0045]

[0046] The CAS number of the 2-naphthylammonium bromide is 148819-80-1; the CAS number of the 1-(naphthoxy)acetic acid hydrazine is 24310-15-4.

[0047] Example 1

[0048] The composite graphite-based material for the bipolar plate in this embodiment comprises the following raw materials in parts by weight:

[0049] 80 parts graphite, 8 parts 4-(1-naphthoxy-5-decoxy)butyltrimethylammonium bromide, 10 parts conductive agent, and 20 parts resin.

[0050] The resin is a phenolic resin. The conductive agent is polyaniline.

[0051] The method for preparing the composite graphite-based material for bipolar plates described in this embodiment includes the following steps:

[0052] (1) Take graphite, 4-(1-naphthoxy-5-decoxy)butyltrimethylammonium bromide and water, mix them evenly, and ball mill the resulting mixture at a speed of 600 r / min for 30 min;

[0053] The water accounts for 15 wt% of the mass percentage of the mixture.

[0054] (2) Take resin, conductive agent and dispersant, mix them evenly, add them to the mixture obtained in step (1), mix them evenly, and obtain a mixed slurry;

[0055] The dispersant is acetone; the mass ratio of acetone to resin is 1.5:1.

[0056] (3) The mixed slurry obtained in step (2) is dried and hot-pressed to form the final product.

[0057] The drying temperature is 65℃, and the time is 2h. The hot-pressing is performed at a pressure of 40Mpa and a temperature of 160℃ for 45min.

[0058] Example 2

[0059] The composite graphite-based material for bipolar plates in this example comprises the following raw materials by weight:

[0060] Graphite 100 parts, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide 10 parts, conductive agent 5 parts, resin 30 parts.

[0061] The resin is a mixture of phenolic resin and epoxy resin in a weight ratio of 1:1. The conductive agent is polyaniline.

[0062] The preparation method of the composite graphite-based material for bipolar plates in this example comprises the following steps:

[0063] (1) Take graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, and water, mix them evenly, and ball mill the obtained mixture at a speed of 800r / min for 90min;

[0064] The water accounts for 12wt% of the mass of the mixture.

[0065] (2) Take resin, conductive agent, and dispersant, mix them evenly, and add them to the mixture obtained in step (1), mix them evenly, and obtain a mixed slurry;

[0066] The dispersant is acetone, and the mass ratio of the acetone to the resin is 2.0:1.

[0067] (3) Dry and hot-press the mixed slurry obtained in step (2), and obtain the composite graphite-based material for bipolar plates.

[0068] The drying temperature is 70℃, and the time is 4h. The hot-pressing is performed at a pressure of 30Mpa and a temperature of 180℃ for 60min.

[0069] Example 3

[0070] The composite graphite-based material for bipolar plates in this example comprises the following raw materials by weight:

[0071] Graphite 90 parts, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide 15 parts, conductive agent 8 parts, resin 10 parts.

[0072] The resin is phenolic resin. The conductive agent is polyaniline.

[0073] The preparation method of the composite graphite-based material for bipolar plates comprises the following steps:

[0074] (1) Take graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, and water, mix uniformly, and mill the obtained mixed solution at a speed of 500 r / min for 60 min;

[0075] The water accounts for 10wt% of the mixed solution.

[0076] (2) Take resin, conductive agent, and dispersant, mix uniformly, and add to the mixed solution obtained in step (1), mix uniformly, and obtain a mixed slurry;

[0077] The dispersant is acetone, and the mass ratio of the acetone to the resin is 1.8:1.

[0078] (3) Dry and hot-press the mixed slurry obtained in step (2) to obtain the composite graphite-based material for bipolar plates.

[0079] The drying temperature is 60°C, and the drying time is 3h. The hot-pressing is performed at a pressure of 50Mpa and a temperature of 170°C for 30 min.

[0080] Example 4

[0081] The composite graphite-based material for bipolar plates in this example comprises the following raw materials by weight:

[0082] Graphite 100 parts, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide 12 parts, conductive agent 10 parts, and resin 20 parts.

[0083] The resin is phenolic resin, and the conductive agent is polyaniline.

[0084] The preparation method of the composite graphite-based material for bipolar plates comprises the following steps:

[0085] (1) Take graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, and water, mix uniformly, and mill the obtained mixed solution at a speed of 800 r / min for 90 min;

[0086] The water accounts for 15wt% of the mixed solution.

[0087] (2) Take resin, conductive agent, and dispersant, mix uniformly, and add to the mixed solution obtained in step (1), mix uniformly, and obtain a mixed slurry;

[0088] The dispersant is acetone, and the mass ratio of the acetone to the resin is 1.6:1.

[0089] (3) dry the mixed slurry obtained in step (2) and hot-press to form, to obtain.

[0090] The drying temperature is 70℃, and the drying time is 4h. The hot-pressing is performed at a pressure of 50Mpa and a temperature of 175℃ for 60min.

[0091] Example 5

[0092] The composite graphite-based material for bipolar plates in this embodiment comprises the following raw materials by weight:

[0093] Graphite 100 parts, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide 12 parts, conductive agent 10 parts, resin 20 parts, intercalation regulator 0.6 parts.

[0094] The resin is phenolic resin. The conductive agent is polyaniline. The intercalation regulator is 1-naphthyl ammonium bromide.

[0095] The preparation method of the composite graphite-based material for bipolar plates in this embodiment comprises the following steps:

[0096] (1) Take graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, intercalation regulator, and water, mix them uniformly, and ball mill the obtained mixed solution at a speed of 800r / min for 90min;

[0097] The water accounts for 15wt% of the mass percentage of the mixed solution.

[0098] (2) Take resin, conductive agent, and dispersant, mix them uniformly, and add them to the mixed solution obtained in step (1), mix them uniformly, to obtain a mixed slurry;

[0099] The dispersant is acetone. The mass ratio of the acetone to the resin is 1.6:1.

[0100] (3) Dry the mixed slurry obtained in step (2) and hot-press to form, to obtain.

[0101] The drying temperature is 70℃, and the drying time is 4h. The hot-pressing is performed at a pressure of 50Mpa and a temperature of 175℃ for 60min.

[0102] Example 6

[0103] The composite graphite-based material for bipolar plates in this embodiment comprises the following raw materials by weight:

[0104] Graphite 100 parts, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide 12 parts, conductive agent 10 parts, resin 20 parts, intercalation regulator 1.2 parts.

[0105] The resin is phenolic resin. The conductive agent is polyaniline. The intercalation regulator is 2-naphthyl ammonium bromide.

[0106] The preparation method of the composite graphite-based material for bipolar plates comprises the following steps:

[0107] (1) Take graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, intercalation regulator, and water, mix them evenly, and then ball mill the obtained mixture at a speed of 800 r / min for 90 min;

[0108] The water accounts for 15 wt% of the mixture.

[0109] (2) Take resin, conductive agent, and dispersant, mix them evenly, and then add them to the mixture obtained in step (1) to obtain a mixed slurry;

[0110] The dispersant is acetone, and the mass ratio of the acetone to the resin is 1.6:1.

[0111] (3) Dry and hot-press the mixed slurry obtained in step (2) to obtain the composite graphite-based material for bipolar plates.

[0112] The drying temperature is 70°C, and the drying time is 4 h. The hot-pressing is performed at a pressure of 50 Mpa and a temperature of 175°C for 60 min.

[0113] Example 7

[0114] The composite graphite-based material for bipolar plates comprises the following raw materials by weight:

[0115] Graphite 100 parts, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide 12 parts, conductive agent 10 parts, resin 20 parts, and intercalation regulator 1.8 parts.

[0116] The resin is phenolic resin. The conductive agent is polyaniline. The intercalation regulator is 1-(naphthoxy) hydrazine acetate.

[0117] The preparation method of the composite graphite-based material for bipolar plates comprises the following steps:

[0118] (1) Take graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, intercalation regulator, and water, mix them evenly, and then ball mill the obtained mixture at a speed of 800 r / min for 90 min;

[0119] The water accounts for 15 wt% of the mixture.

[0120] (2) Take resin, conductive agent, dispersing agent, mix evenly, add to the mixed solution obtained in step (1), mix evenly, obtain mixed slurry;

[0121] Among them, the dispersing agent is acetone; the mass ratio of the acetone to the resin is 1.6:1.

[0122] (3) The mixed slurry obtained in step (2) is dried and hot-pressed to obtain.

[0123] The drying temperature is 70℃, and the time is 4h. The hot-pressing is under the pressure of 50Mpa and the temperature of 175℃, and the holding time is 60min.

[0124] Example 8

[0125] The composite graphite-based material for bipolar plate in this embodiment comprises the following raw materials by weight:

[0126] Graphite 100 parts, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide 12 parts, conductive agent 10 parts, resin 20 parts, intercalation modifier 1.2 parts.

[0127] Among them, the resin is phenolic resin. The conductive agent is polyaniline. The intercalation modifier is a mixture of 1-naphthyl ammonium bromide and 1-(naphthoxy) hydrazine acetate in a weight ratio of 1:3.5.

[0128] The preparation method of the composite graphite-based material for bipolar plate described in this embodiment comprises the following steps:

[0129] (1) Take graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, intercalation modifier, water, mix evenly, and mill the obtained mixed solution at a speed of 800r / min for 90min;

[0130] Among them, the water accounts for 15wt% of the mass percentage of the mixed solution.

[0131] (2) Take resin, conductive agent, dispersing agent, mix evenly, add to the mixed solution obtained in step (1), mix evenly, obtain mixed slurry;

[0132] Among them, the dispersing agent is acetone; the mass ratio of the acetone to the resin is 1.6:1.

[0133] (3) The mixed slurry obtained in step (2) is dried and hot-pressed to obtain.

[0134] The drying temperature is 70℃, and the time is 4h. The hot-pressing is under the pressure of 50Mpa and the temperature of 175℃, and the holding time is 60min.

[0135] Example 9

[0136] The composite graphite-based material for bipolar plates in this embodiment comprises the following raw materials by weight:

[0137] Graphite 100 parts, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide 12 parts, conductive agent 10 parts, resin 20 parts, intercalation regulator 0.6 parts.

[0138] The resin is phenolic resin. The conductive agent is polyaniline. The intercalation regulator is a mixture of 2-naphthyl ammonium bromide and 1-(naphthoxy) acetic acid hydrazine in a weight ratio of 1:2.6.

[0139] The preparation method of the composite graphite-based material for bipolar plates described in this embodiment comprises the following steps:

[0140] (1) Take graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, intercalation regulator, and water, mix them evenly, and ball mill the obtained mixture at a speed of 800 r / min for 90 min;

[0141] The water accounts for 15wt% of the mass percentage of the mixture.

[0142] (2) Take resin, conductive agent, and dispersant, mix them evenly, and add them to the mixture obtained in step (1), mix them evenly, and obtain a mixed slurry;

[0143] The dispersant is acetone, and the mass ratio of the acetone to the resin is 1.6:1.

[0144] (3) Dry and hot-press the mixed slurry obtained in step (2) to obtain the composite graphite-based material for bipolar plates.

[0145] The drying temperature is 70℃, and the time is 4h. The hot-pressing is performed at a pressure of 50Mpa and a temperature of 175℃ for 60min.

[0146] Example 10

[0147] The composite graphite-based material for bipolar plates in this embodiment comprises the following raw materials by weight:

[0148] Graphite 100 parts, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide 12 parts, conductive agent 10 parts, resin 20 parts, intercalation regulator 0.6 parts, 1,4-diamino-2,3-dihydroanthraquinone 2 parts.

[0149] The resin is phenolic resin. The conductive agent is polyaniline. The intercalation regulator is a mixture of 2-naphthyl ammonium bromide and 1-(naphthoxy) acetic acid hydrazine in a weight ratio of 1:2.6.

[0150] The preparation method of the composite graphite-based material for bipolar plates described in the embodiment comprises the following steps:

[0151] (1) Take graphite, 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide, intercalation regulator, 1,4-diamino-2,3-dihydroanthraquinone, and water, mix them uniformly, and mill the obtained mixed solution at a speed of 800 r / min for 90 min;

[0152] The water accounts for 15wt% of the mixed solution.

[0153] (2) Take resin, conductive agent, and dispersant, mix them uniformly, and add them to the mixed solution obtained in step (1), mix them uniformly, and obtain a mixed slurry;

[0154] The dispersant is acetone, and the mass ratio of the acetone to the resin is 1.6:1.

[0155] (3) Dry and hot-press the mixed slurry obtained in step (2) to obtain the composite graphite-based material for bipolar plates.

[0156] The drying temperature is 70℃, and the drying time is 4h. The hot-pressing is performed at a pressure of 50Mpa and a temperature of 175℃ for 60 min.

[0157] Comparative Example 1

[0158] The composite graphite-based material for bipolar plates in this comparative example is the same as that in Example 4, and is prepared by the same method, with the only difference being that the 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide is not contained.

[0159] Comparative Example 2

[0160] The composite graphite-based material for bipolar plates in this comparative example is the same as that in Example 4, and is prepared by the same method, with the only difference being that the 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide is replaced by 4-(1-naphthoxy-5-octyloxy) butyl trimethyl ammonium bromide.

[0161] The 4-(1-naphthoxy-5-octyloxy) butyl trimethyl ammonium bromide has the following structural formula:

[0162]

[0163] Comparative Example 3

[0164] The composite graphite-based material for bipolar plates in this comparative example is the same as that in Example 4, and is prepared by the same method, with the only difference being that the conductive agent is not contained.

[0165] Comparative Example 4

[0166] The comparative example is the same as the composite graphite-based material for bipolar plates of Example 4, and is prepared by the same method, with the only difference being that the polyaniline conductive agent is replaced by conductive carbon black.

[0167] Comparative Example 5

[0168] The comparative example is the same as the composite graphite-based material for bipolar plates of Example 4, and is prepared by the same method, with the only difference being that the amount of 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide is 6 parts.

[0169] Comparative Example 6

[0170] The comparative example is the same as the composite graphite-based material for bipolar plates of Example 4, and is prepared by the same method, with the only difference being that the amount of 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide is 20 parts.

[0171] Comparative Example 7

[0172] The comparative example is the same as the composite graphite-based material for bipolar plates of Example 4, and is prepared by the same method, with the only difference being that the 4-(1-naphthoxy-5-decyloxy) butyl trimethyl ammonium bromide is replaced by dodecyl trimethyl ammonium bromide.

[0173] Comparative Example 8

[0174] The comparative example is the same as the composite graphite-based material for bipolar plates of Example 10, and is prepared by the same method, with the only difference being that the intercalation modifier is not included.

[0175] Effect Experimental Example

[0176] In order to verify the technical effect of the composite graphite-based material for bipolar plates of the present application, the following tests were carried out:

[0177] The composite graphite-based materials for bipolar plates prepared in Examples 1-10 and Comparative Examples 1-8 were formed into plates with a thickness of 1.2 mm as samples, and the electrical conductivity was measured using an electrical conductivity tester, the bending strength was measured using an electronic universal testing machine, the hydrogen permeation rate was measured using a permeation cell and a gas chromatograph, and the heat distortion temperature of the sample was tested by the method in GB / T1634.1-2004 Determination of Heat Distortion Temperature of Plastics under Load.

[0178] Through experiments, the results were as follows:

[0179]

[0180] According to the results of examples 1-4 and comparative examples 1-6, the composite graphite-based material for bipolar plates has good electrical conductivity, mechanical properties, and gas tightness, and thermal stability.

[0181] According to the results of example 4, comparative examples 1, 5, and 6, the addition of the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide has a significant effect on the electrical conductivity, bending strength, and hydrogen permeation rate of the material. If the amount of the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide is too small, the effect of improving the electrical conductivity, bending strength, and gas tightness of the material is not significant enough. If the amount of the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide is too large, the electrical conductivity, bending strength, and gas tightness of the material will be reduced to some extent, especially the electrical conductivity.

[0182] According to the results of example 4 and comparative example 2, replacing the 4-(1-naphthoxy-5-decyloxy)butyl trimethyl ammonium bromide with 4-(1-naphthoxy-5-octyloxy)butyl trimethyl ammonium bromide, i.e., reducing the length of the long chain, will result in a decrease in the comprehensive performance of the bipolar plate, which may be caused by the differences in the steric hindrance and interface interaction sites provided by different lengths of alkyl chains.

[0183] According to the results of example 4 and comparative examples 3 and 4, using the polyaniline as the conductive agent will not only have a significant effect on the electrical conductivity of the material, but also have some effect on the mechanical properties and gas tightness of the material.

[0184] According to the results of example 4 and examples 5-9, the addition of the intercalation regulator has little effect on the gas tightness and thermal stability of the material. Although the mechanical properties of the obtained material are reduced to some extent, the electrical conductivity is significantly improved. In particular, in examples 8-9, the intercalation regulator is 2-naphthyl ammonium bromide and 1-(naphthoxy)acetic acid hydrazine or a mixture of 1-naphthyl ammonium bromide and 1-(naphthoxy)acetic acid hydrazine, and the effect of improving the electrical conductivity is significant.

[0185] According to the results of Example 4 and Example 9, 10, Comparative Example 8, it can be seen that, when the intercalation regulator and the 1,4-diamino-2,3-dihydroanthraquinone are added (Example 10), not only can the bending strength of the material be greatly improved without affecting the conductive properties of the material, but the problem of the mechanical properties of the material being reduced due to the intercalation regulator is solved, and the thermal stability of the material is also significantly improved. When only the 1,4-diamino-2,3-dihydroanthraquinone is added without the intercalation regulator (Comparative Example 8), the conductive properties and bending strength of the material are significantly reduced, which is almost the same as Example 4 without the 1,4-diamino-2,3-dihydroanthraquinone and the intercalation regulator. This may be due to the fact that although the intercalation regulator can improve the conductive properties, its binding force with the resin is relatively weak, which can lead to a decrease in the mechanical properties of the material, and the 1,4-diamino-2,3-dihydroanthraquinone can play a "bridging" role by combining with the phenolic resin through the amino group, and at the same time, its anthraquinone planar conjugated system has good interfacial bonding properties with the naphthyl and naphthoxy groups of the intercalation regulator, which can synergistically optimize the cross-linked network formed with the resin to improve the comprehensive performance of the material. However, without the intercalation regulator, the 1,4-diamino-2,3-dihydroanthraquinone can also have a certain effect on the bending strength of the material, but it cannot significantly improve the bending strength of the material.

[0186] From the common general knowledge, the application can be implemented by other embodiments which do not depart from the spirit or essential characteristics of the application. Therefore, the above disclosed embodiments are merely illustrative in all aspects and are not the only ones. All changes within the scope of the application or within the scope equivalent to the application are embraced by the application.

Claims

1. A composite graphite-based material for bipolar plates, characterized in that, The ingredients include the following parts by weight: 80-100 parts graphite, 8-15 parts 4-(1-naphthoxy-5-decoxy)butyltrimethylammonium bromide, 5-10 parts conductive agent, 10-30 parts resin, and 0.6-1.8 parts intercalation modifier; The intercalation regulator is a mixture of 1-naphthylammonium bromide and 1-(naphthoxy)acetic acid hydrazine in a weight ratio of 1:(3.2-3.8); or, The intercalation regulator is a mixture of 2-naphthylammonium bromide and 1-(naphthoxy)acetic acid hydrazine in a weight ratio of 1:(2.5-3.0).

2. The composite graphite-based material for bipolar plates according to claim 1, characterized in that, The resin is phenolic resin or a mixture of phenolic resin and epoxy resin.

3. The composite graphite-based material for bipolar plates according to claim 2, characterized in that, The conductive agent is polyaniline.

4. A method for preparing a composite graphite-based material for bipolar plates as described in any one of claims 1-3, characterized in that, The process includes the following steps: mixing graphite, 4-(1-naphthoxy-5-decoxy)butyltrimethylammonium bromide, conductive agent, resin, and intercalation modifier evenly, and then hot-pressing to form the product.

5. The method for preparing the composite graphite-based material for bipolar plates according to claim 4, characterized in that, Includes the following steps: (1) Take graphite, 4-(1-naphthoxy-5-decoxy)butyltrimethylammonium bromide, intercalation regulator and water, mix them evenly to obtain a mixture; (2) Take resin, conductive agent and dispersant, mix them evenly, add them to the mixture obtained in step (1), mix them evenly, and obtain a mixed slurry; (3) The mixed slurry obtained in step (2) is dried and hot-pressed to form the final product.

6. The method for preparing the composite graphite-based material for bipolar plates according to claim 5, characterized in that, In step (1), the water accounts for 10-15 wt% of the mass of the mixture.

7. The method for preparing the composite graphite-based material for bipolar plates according to claim 5, characterized in that, Step (1) is as follows: Take graphite, 4-(1-naphthoxy-5-decoxy)butyltrimethylammonium bromide and water, mix them evenly, and ball mill the resulting mixture at a speed of 500-800 r / min for 30-90 min.

8. The method for preparing the composite graphite-based material for bipolar plates according to claim 5, characterized in that, In step (2), the dispersant is acetone; the mass ratio of acetone to resin is (1.5-2.0):

1.

9. The method for preparing the composite graphite-based material for bipolar plates according to claim 5, characterized in that, In step (3), the drying temperature is 60-70℃ and the time is 2-4h.

10. The method for preparing the composite graphite-based material for bipolar plates according to claim 5, characterized in that, In step (3), the hot pressing is carried out at a pressure of 30-50 MPa and a temperature of 160-180°C for 30-60 minutes.

Images