Composite resin for fuel cell packaging and preparation method thereof

Abstract

The invention discloses a composite resin material for packaging a fuel cell and a preparation method of the composite resin material. The composite resin comprises bisphenol F type epoxy resin, alicyclic epoxy resin, acrylate resin, a toughening agent, nano silicon dioxide particles, a long-chain aliphatic amine curing agent, an imidazole accelerant and graphene coating carbon fibers. Bisphenol F and alicyclic epoxy resin are compounded, acrylate resin is combined to form a rigid-flexible three-dimensional network matrix, nano-silica treated by a silane coupling agent is introduced to improve moisture resistance, and graphene coating carbon fibers with oxygen-containing groups on the surface are utilized to enhance interface bonding force. And a cross-linked network is regulated and controlled through the coordination of the long-chain fatty amine curing agent and the imidazole accelerant. The obtained composite resin has excellent temperature resistance, moisture resistance, mechanical properties and interface bonding strength, effectively solves the problem of performance degradation of a traditional packaging material in high-temperature, high-humidity and corrosive environments, and meets the strict use requirements of fuel cells.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cell packaging materials, and in particular relates to a composite resin for fuel cell packaging and a preparation method thereof. Background Art

[0002] Fuel cells, as efficient and clean energy conversion devices, hold broad application prospects in the new energy sector. Proton exchange membrane fuel cells (PEMFCs) have attracted significant attention in applications such as electric vehicles and portable power sources due to their low operating temperature, fast startup, and high power density. However, the long-term stable operation of fuel cells faces numerous challenges, with the performance of the packaging material being a key factor.

[0003] Packaging plays a crucial role in fuel cells. It not only tightly binds the various components of a cell together to form a complete electrochemical reaction system, but also provides sealing, insulation, and protection, preventing gas leakage, electrolyte penetration, and environmental influences on the cell's interior. Currently, commonly used fuel cell packaging materials primarily include polymer-based composites such as epoxy resins, polyamide resins, and polyurethanes. While these materials offer good processing properties and a certain degree of heat resistance, they still have limitations in high-temperature, high-humidity, and corrosive environments. For example, traditional epoxy resins are prone to crosslinking and structural breakdown under long-term high-temperature conditions, resulting in a decrease in mechanical properties. Polyamide resins, on the other hand, tend to absorb moisture and expand in humid environments, affecting the dimensional stability of the packaging structure. Furthermore, while carbon fiber-reinforced composites offer high strength and lightweight properties, their interfacial bonding is weak, making them prone to debonding or crack propagation over long periods of service, thus impacting the overall performance of the packaging structure.

[0004] To address these issues, some existing research has attempted to improve the overall performance of composite materials by introducing functional fillers or optimizing the resin matrix composition. For example, some patents propose improving the density and moisture resistance of the resin matrix by adding nano-sized silica or alumina fillers, while others attempt to employ novel curing agent systems to manipulate the cross-linked network structure and enhance the toughness and fatigue resistance of the material. However, while existing technologies improve the overall performance of the materials, they often struggle to balance processing performance and cost control, limiting their practical application in the fuel cell packaging field.

[0005] Furthermore, the harsh operating environment within fuel cells, characterized by the presence of electrolyte solutions, high temperatures, high humidity, and corrosive gases, places high demands on the chemical resistance of packaging materials. Existing packaging materials are susceptible to corrosion from these factors over long-term use, leading to degradation of material performance and, in turn, impacting the lifespan and reliability of fuel cells.

[0006] Therefore, developing a composite resin material that combines high strength, high temperature resistance, excellent moisture resistance, and good chemical stability, and optimizing its preparation process to achieve large-scale production, has become a key research direction for fuel cell packaging materials. This invention addresses these technical requirements and proposes a novel composite resin material and its preparation method to address the performance degradation of existing technologies in high-temperature, high-humidity, and corrosive environments, further improving the reliability and service life of fuel cell packaging structures. Summary of the Invention

[0007] The present invention aims to provide a high-performance composite resin material suitable for fuel cell packaging and its preparation method, addressing the performance degradation of existing packaging materials in high-temperature, high-humidity, and corrosive environments. By optimizing the resin matrix composition and introducing functional additives, this composite resin material significantly enhances its temperature resistance, moisture resistance, and chemical stability, thus meeting the stringent requirements of fuel cell packaging.

[0008] In order to achieve the above object, the present invention provides a composite resin material for fuel cell packaging, characterized in that it includes the following components in percentage by mass:

[0009] Bisphenol F epoxy resin: 15%–35%;

[0010] Cycloaliphatic epoxy resin: 10%–30%;

[0011] Acrylate resin: 10%–30%;

[0012] Toughener: 1%–5%;

[0013] Nanosilica particles: 5%–10%;

[0014] Long-chain fatty amine curing agent: 8%–15%;

[0015] Imidazole accelerator: 2%–8%;

[0016] Graphene-coated carbon fiber: 10%–20%.

[0017] Furthermore, the bisphenol F epoxy resin is selected from Epon 862 or Epon 828, and the alicyclic epoxy resin is selected from CY184 or Epon C1571.

[0018] Furthermore, the composite resin also contains auxiliary components and diluent solvents, which may be organic solvents such as acetone and toluene.

[0019] Furthermore, the nano-silica particles have a particle size of 20–100 nm, and the surface is treated with a silane coupling agent; the silane coupling agent is one or both of γ-aminopropyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane. In order to further improve the density and interfacial bonding strength of the composite resin material, the present invention introduces nano-silica particles as functional fillers. Nano-silica has an extremely high specific surface area and surface activity, and can be evenly dispersed in the resin matrix, filling microscopic gaps and reducing porosity, thereby improving the air tightness and impermeability of the material. In addition, the surface of the silica particles is rich in silanol (Si-OH), which can chemically bond with the epoxy resin, enhance the interaction between the filler and the matrix, and improve the interfacial bonding strength of the composite material. This enhancement effect not only improves the mechanical properties of the material, but also effectively inhibits crack propagation, improving the durability and fatigue resistance of the material.

[0020] Furthermore, the acrylic resin is one or more of methyl methacrylate-ethyl acrylate copolymer and methyl methacrylate-butyl acrylate copolymer; the toughening agent is one or more of carboxyl-terminated nitrile rubber, epoxy-terminated polybutadiene, epoxy-modified silicone rubber, and hydrogenated styrene-butadiene-styrene block copolymer.

[0021] Furthermore, a long-chain fatty amine curing agent and an imidazole accelerator were combined in a mass ratio of 5:1–8:1 to effectively control the resin crosslinking network. Long-chain fatty amine curing agents have a long molecular chain structure, forming a relatively flexible crosslinking network, thereby improving the toughness and fatigue resistance of the composite material. Furthermore, their low reaction exotherm helps reduce internal stress accumulation during the molding process, lowering the risk of material cracking. The imidazole accelerator accelerates the reaction between the epoxy groups and the amine curing agent, improving curing efficiency and regulating the crosslinking density, ensuring that the material maintains high mechanical strength while also exhibiting good durability. The synergistic effect of these two accelerators enables the composite resin to fully cure over a wide temperature range, enhancing the material's applicability and processing flexibility.

[0022] Furthermore, the mass ratio of bisphenol F epoxy resin and alicyclic epoxy resin is 2:3-3:2; the composite system consisting of bisphenol F epoxy resin and alicyclic epoxy resin is used as the main resin matrix. Bisphenol F epoxy resin has low viscosity and high reactivity, which makes it easy to flow and impregnate carbon fibers during processing, thereby improving the uniformity of the composite material. In addition, its molecular structure contains long methylene segments, which give the material a certain flexibility and help improve impact resistance. On the other hand, alicyclic epoxy resin has excellent heat resistance and low moisture absorption rate, and can maintain a stable chemical structure under high temperature and high humidity environments. The combination of the two not only improves the comprehensive performance of the resin matrix, but also optimizes the glass transition temperature (Tg) and thermal stability of the material by adjusting the ratio, making it more adaptable to the extreme conditions during fuel cell operation.

[0023] Furthermore, the graphene layer coated on the surface of the graphene-coated carbon fiber has a thickness of 30-100nm, and the graphene coating surface has oxygen-containing groups. Carbon fiber is used as the main reinforcement phase, and the graphene layer is coated on the surface of the carbon fiber to enhance the interfacial bonding between the fiber and the resin matrix. Graphene is a two-dimensional material with excellent mechanical properties and conductivity. Its ultra-thin structure can be tightly attached to the surface of the carbon fiber, increasing the contact area between the fiber and the matrix. In addition, the abundant oxygen-containing functional groups (such as carboxyl and hydroxyl groups) on the graphene surface can chemically react with the epoxy resin to form a stronger interfacial bond, thereby improving the load-bearing capacity and fracture toughness of the composite material.

[0024] Furthermore, a gradient blending system of epoxy and acrylate resins was employed, with the combined mass ratio of bisphenol F epoxy resin and alicyclic epoxy resin to acrylate resin at a ratio of 1:1–2:1. By precisely controlling the mass ratio of the two resins, a three-dimensional network composite matrix with both rigidity and flexibility was constructed. The epoxy resin serves as the rigid skeleton component, and the epoxy groups on its molecular chains form a highly cross-linked, dense network during the curing process, endowing the material with excellent mechanical strength and high-temperature resistance. This cross-linked network effectively resists the thermal stress and mechanical vibrations associated with fuel cell operation, preventing matrix cracking due to stress concentration. Acrylate resin is used as a flexible modification component. The long-chain alkyl ester groups on its molecular chain (such as ethyl acrylate and butyl acrylate groups) are embedded in the epoxy resin network in a molecularly dispersed state to form an "island-type" two-phase structure; the ester polar groups form hydrogen bonds with the ether bonds of the epoxy resin, which reduces the interfacial tension of the two phases, achieves nano-level compatibility, and avoids the phase separation problem of traditional blending systems; the flexible ester chain segments act as "molecular springs" and undergo reversible stretching when the material is impacted, converting the impact energy into conformational change energy of the molecular chain, thereby increasing the impact strength and effectively inhibiting the initiation and expansion of cracks.

[0025] Another aspect of the present invention provides a method for preparing the composite resin for fuel cell encapsulation, characterized in that it comprises the following steps:

[0026] (1) adding bisphenol F epoxy resin, alicyclic epoxy resin, acrylate resin, toughening agent and solvent into a reaction kettle, heating to 60–80°C, and stirring uniformly to obtain a mixed resin solution;

[0027] (2) Add nano-silica and graphene-coated carbon fiber to the mixed resin solution and continue stirring for 30-60 minutes to fully disperse the components;

[0028] (3) cooling to 40–50°C, adding a long-chain fatty amine curing agent and an imidazole accelerator, and stirring evenly to obtain a composite resin prepolymer;

[0029] (4) Degassing the composite resin prepolymer at a vacuum degree of -0.08 to -0.1 MPa for 10 to 20 minutes to obtain the composite resin for fuel cell packaging.

[0030] Furthermore, the graphene-coated carbon fiber is obtained by depositing the graphene on the carbon fiber surface using a CVD method in an atmosphere containing a small amount of oxygen or water vapor; and the nano-silicon dioxide surface is obtained by treating it with a silane coupling agent.

[0031] The composite resin material proposed by the present invention has the following technical effects:

[0032] Excellent temperature resistance: By compounding epoxy resin and acrylate resin, the high mechanical strength and high temperature resistance of epoxy resin are combined with the flexibility and weather resistance of acrylate resin, so that the composite resin has good comprehensive performance; the compounding system of bisphenol F epoxy resin and alicyclic epoxy resin is improved, so that the material's glass transition temperature (Tg) can still maintain stable mechanical properties in high temperature environment.

[0033] Good moisture resistance: The introduction of nano-silica particles reduces the porosity of the resin matrix, reduces moisture penetration, and improves the moisture resistance and long-term stability of the material.

[0034] Enhanced interfacial bonding: The surface modification of graphene-coated carbon fibers enhances the interfacial bonding between the fibers and the resin matrix, improving the material's load-bearing capacity and fracture toughness.

[0035] Controllable processing performance: By optimizing the curing agent system and adjusting the cross-linking network structure, the material can be fully cured in different temperature ranges, thereby improving its processing adaptability. DETAILED DESCRIPTION

[0036] The present invention will be described in detail below with reference to specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art to the present invention based on the contents of the present invention still fall within the scope of protection of the present invention.

[0037] Example 1:

[0038] Components (mass percentage):

[0039] Bisphenol F epoxy resin (Epon 862): 25%;

[0040] Cycloaliphatic epoxy resin (CY184): 15%;

[0041] Acrylate resin (methyl methacrylate-butyl acrylate copolymer): 25%;

[0042] Toughening agent (carboxyl-terminated nitrile rubber): 3%;

[0043] Nanosilica (50 nm, treated with γ-aminopropyltriethoxysilane): 5%;

[0044] Long-chain fatty amine curing agent (hexamethylenediamine): 10%;

[0045] Imidazole accelerator (2-ethyl-4-methylimidazole): 2%;

[0046] Graphene-coated carbon fiber (coating thickness 50 nm, coating with oxygen-containing groups): 15%; the graphene-coated carbon fiber is obtained by depositing on the surface of the carbon fiber by CVD in an atmosphere containing a small amount of oxygen or water vapor.

[0047] The specific preparation method is:

[0048] (1) adding bisphenol F epoxy resin Epon 862, alicyclic epoxy resin CY184, acrylic resin methyl methacrylate-butyl acrylate copolymer, toughening agent carboxyl-terminated nitrile rubber and solvent into a reaction kettle, heating to 70° C., stirring uniformly to obtain a mixed resin solution;

[0049] (2) Add nano-silica and graphene-coated carbon fiber to the mixed resin solution and continue stirring for 40 minutes to fully disperse the components;

[0050] (3) cooling to 40° C., adding hexamethylenediamine, a long-chain fatty amine curing agent, and 2-ethyl-4-methylimidazole, an imidazole accelerator, and stirring uniformly to obtain a composite resin prepolymer;

[0051] (4) Degas the composite resin prepolymer at a vacuum degree of -0.1 MPa for 15 minutes to obtain the composite resin for fuel cell packaging.

[0052] Example 2:

[0053] The amounts of bisphenol F epoxy resin and alicyclic epoxy resin were changed to a mass ratio of 4:1, and the remaining components were the same as in Example 1.

[0054] Example 3:

[0055] The amounts of bisphenol F epoxy resin and alicyclic epoxy resin were changed to a mass ratio of 1:3, and the remaining components were the same as in Example 1.

[0056] Example 4:

[0057] The amounts of epoxy resin and acrylate resin were changed to a mass ratio of 0.5:1, and the remaining components were the same as in Example 1.

[0058] Example 5:

[0059] The amounts of epoxy resin and acrylate resin were changed to a mass ratio of 3:1, and the remaining components were the same as in Example 1.

[0060] Example 6:

[0061] The nano-silica was not treated with a silane coupling agent, and the other components were the same as those in Example 1.

[0062] Example 7:

[0063] The graphene surface in the graphene-coated carbon fiber has no oxygen-containing groups, and the remaining components are the same as those in Example 1.

[0064] Comparative Example 1:

[0065] The carbon fiber has no graphene coating, and the other components are the same as those in Example 1.

[0066] Comparative Example 2:

[0067] Without nano-silicon dioxide, the other components are the same as those in Example 1.

[0068] Comparative Example 3:

[0069] Without acrylate resin, the other components are the same as those in Example 1.

[0070] Comparative Example 4:

[0071] The curing agent is changed to hexamethylenediamine, without imidazole accelerator, and the other components are the same as those in Example 1.

[0072] Performance test indicators and results

[0073] Test Method

[0074] Tensile strength: GB / T1447-2005, universal material testing machine (5mm / min).

[0075] Bending strength: GB / T1449-2005, span 32mm.

[0076] Glass transition temperature (Tg): DSC differential scanning calorimeter (heating rate 10°C / min, N2 atmosphere).

[0077] Water absorption: GB / T1034-2021, soaked in water at 25°C for 48 hours.

[0078] Hygrothermal aging performance: aging at 85℃ / 85%RH for 1000h, testing the tensile strength retention rate.

[0079] Interfacial shear strength (IFSS): single-filament pull-out method, carbon fiber single filament is embedded in the resin matrix and pulled out using a micromechanical tester.

[0080] Table 1 is the test results of the above embodiment and comparative example:

[0081] Table 1

[0082]

[0083] The experimental results of Examples 1–3 in Table 1 show that in Example 2, the bisphenol F to alicyclic epoxy resin mass ratio of 4:1 exceeds the upper limit of the 2:3–3:2 mass ratio. Compared to Example 1, the tensile and flexural strengths decrease, and the Tg decreases. This is due to insufficient crosslinking density caused by the excessively high bisphenol F ratio. In Example 3, the bisphenol F to alicyclic epoxy resin mass ratio of 1:3 falls below the lower limit of the 2:3–3:2 mass ratio. Compared to Example 1, while the Tg increases, reflecting the high-temperature resistance advantage of the alicyclic epoxy resin, the strength is slightly lower than in Example 1 due to the alicyclic epoxy resin's insufficient flexibility. The optimal balance of rigidity and flexibility is achieved only when the ratio is between 2:3 and 3:2; exceeding this range results in decreased high-temperature resistance or toughness.

[0084] By the experimental results of Example 1, 4-5 in Table 1, it can be seen that in Example 4, the epoxy resin and acrylate resin ratio is 0.5: 1, which is lower than the mass ratio 1: 1-2: 1 lower limit of the two. Compared with Example 1, the acrylate ratio is too high, the resin matrix crosslinking density is insufficient, the tensile and flexural strengths decrease, and the water absorption rate significantly increases, and the porosity increases due to too much flexible phase. In Example 5, the epoxy resin and acrylate resin ratio is 3: 1, which exceeds the mass ratio 1: 1-2: 1 upper limit of the two. The epoxy resin ratio is too high, the acrylate flexible phase is insufficient, Tg decreases, and the cross-linked network rigidity is too strong to cause abnormal glass transition temperature, and the wet heat aging retention rate decreases. It can be seen that the ratio needs to be strictly controlled at 1: 1-2: 1 to ensure a rigid and flexible network structure to avoid phase separation or insufficient crosslinking.

[0085] The experimental results of Examples 1 and 6 show that in Example 1, the nano-silica was treated with a silane coupling agent: the water absorption rate was 0.9%, the wet heat aging retention rate was 90%, and the interfacial bonding force was strong (IFSS = 62 MPa). Example 6 (untreated): the water absorption rate increased to 2.0%, the wet heat aging retention rate decreased, and the strength decreased. Reason: The surface of the untreated silica is hydrophilic, easy to agglomerate, and has weak interfacial bonding with the resin, resulting in an increase in the water penetration path. It can be seen that the silane coupling agent treatment improves the interfacial compatibility through chemical bonding (Si-OH reacts with epoxy groups), significantly improving moisture resistance and mechanical properties.

[0086] From the experimental results of Example 1, Example 7 and Comparative Example 1, it can be seen that Example 1 (oxygen-containing groups): IFSS=62MPa, tensile strength 120MPa. Example 7 (oxygen-free groups): IFSS dropped sharply to 50MPa, and the strength dropped by 12.5%. Oxygen-containing groups (such as carboxyl and hydroxyl) form covalent bonds with epoxy resins, while oxygen-free groups rely only on physical adsorption, and the interfacial bonding force is greatly weakened. It can be seen that oxygen-containing groups are the key to achieving chemical cross-linking of graphene and resin, which directly affects the load-bearing capacity and crack propagation resistance of the composite material. Comparative Example 1 (no graphene coating), IFSS is only 45MPa (a decrease of 27.4% compared with Example 1), and the wet heat aging retention rate is 70% (a decrease of 22.2%). It is proved that the graphene coating significantly improves the interfacial strength and durability by increasing the fiber-resin contact area and chemical cross-linking.

[0087] The experimental results of Example 1 and Comparative Example 2 show that Comparative Example 2 (without nanosilica) has a water absorption rate of 2.5% (a 178% increase compared to Example 1) and a hygrothermal aging retention rate of 65% (a 27.8% decrease compared to Example 1). This indicates that nanosilica is a core filler that reduces porosity and hinders water penetration.

[0088] The experimental results of Example 1 and Comparative Example 3 show that without acrylate resin, the Tg rises to 170°C (due to excessive epoxy resin content), but the flexural strength drops to 145 MPa (a 19.4% decrease), and the water absorption rate is 1.5% (higher than Example 1). This indicates that the flexible segments of the acrylate resin are crucial for alleviating internal stress and improving toughness.

[0089] From the experimental results of Example 1 and Comparative Example 4, it can be seen that when hexamethylenediamine is used without an imidazole accelerator, Tg drops to 145°C (insufficient cross-linking density) and IFSS drops to 52 MPa (a decrease of 16.1%). This is because the use of only hexamethylenediamine curing agent cannot form a cross-linked network with a balanced rigidity and flexibility, resulting in a decrease in high temperature resistance and interfacial bonding strength.

[0090] In general, bisphenol F type (flexibility) and alicyclic (high temperature resistance) are compounded in a ratio of 2:3-3:2, combined with the "island toughening" of acrylic resin to ensure Tg ≥ 160 ° C and tensile strength ≥ 120 MPa, taking into account both rigidity and toughness. Nano-silica is treated with silane to reduce water absorption and improve the retention rate of wet heat aging, and improve moisture resistance by filling pores and interfacial chemical bonding. Graphene-coated carbon fiber, the graphene surface has oxygen-containing groups that increase IFSS and significantly enhance mechanical properties, proving the decisive role of interface modification in the overall performance of composite materials. Long-chain fatty amines (flexible cross-linking) and imidazole accelerators (accelerated cross-linking) work synergistically to avoid insufficient cross-linking or internal stress problems caused by traditional curing agents, ensuring a stable network structure after curing.

[0091] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A composite resin material for fuel cell packaging, characterized in that: The following components are included in mass percentage: Bisphenol F epoxy resin: 15%–35%; Cycloaliphatic epoxy resin: 10%–30%; Acrylate resin: 10%–30%; Toughener: 1%–5%; Nanosilica particles: 5%–10%; Long-chain fatty amine curing agent: 8%–15%; Imidazole accelerator: 2%–8%; Graphene-coated carbon fiber: 10%–20%.

2. The composite resin material for fuel cell packaging according to claim 1, characterized in that The bisphenol F epoxy resin is selected from Epon 862 or Epon 828, and the alicyclic epoxy resin is selected from CY184 or Epon C1571.

3. The composite resin material for fuel cell packaging according to claim 1, wherein The nano-silica particles have a particle size of 20-100 nm, and the surface is treated with a silane coupling agent; the silane coupling agent is one or both of γ-aminopropyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane.

4. The composite resin material for fuel cell packaging according to claim 1, wherein The acrylic resin is one or more of methyl methacrylate-ethyl acrylate copolymer and methyl methacrylate-butyl acrylate copolymer; the toughening agent is one or more of carboxyl-terminated nitrile rubber, epoxy-terminated polybutadiene, epoxy-modified silicone rubber, and hydrogenated styrene-butadiene-styrene block copolymer.

5. The composite resin material for fuel cell packaging according to claim 1, wherein The mass ratio of long-chain fatty amine curing agent to imidazole accelerator is 5:1–8:

1.

6. The composite resin material for fuel cell packaging according to claim 1, wherein The mass ratio of bisphenol F epoxy resin to alicyclic epoxy resin is 2:3–3:

2.

7. The composite resin material for fuel cell packaging according to claim 1, wherein The graphene layer coated on the surface of the graphene-coated carbon fiber has a thickness of 30-100 nm, and the surface of the graphene coating has oxygen-containing groups.

8. The composite resin material for fuel cell packaging according to claim 1, wherein The mass ratio of the sum of the mass of the bisphenol F epoxy resin and the alicyclic epoxy resin to the mass of the acrylate resin is 1:1–2:

1.

9. A method for preparing a composite resin for fuel cell packaging according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) adding bisphenol F epoxy resin, alicyclic epoxy resin, acrylate resin, toughening agent and solvent into a reaction kettle, heating to 60-80° C., and stirring uniformly to obtain a mixed resin solution; (2) Add nano-silica and graphene-coated carbon fiber to the mixed resin solution and continue stirring for 30-60 minutes to fully disperse the components; (3) cooling to 40-50° C., adding a long-chain fatty amine curing agent and an imidazole accelerator, and stirring evenly to obtain a composite resin prepolymer; (4) Degas the composite resin prepolymer at a vacuum degree of -0.08 to -0.1 MPa for 10 to 20 minutes to obtain the composite resin for fuel cell packaging.

10. The preparation method according to claim 1, characterized in that The graphene-coated carbon fiber is obtained by depositing it on the surface of the carbon fiber using a CVD method in an atmosphere containing a small amount of oxygen or water vapor; and the surface of the nano-silicon dioxide is obtained by treating it with a silane coupling agent.

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