A thermally conductive composite material for high-strength, high-toughness, corrosion-resistant flow batteries and its preparation method

Abstract

The present invention discloses a thermally conductive composite material for high-strength, high-toughness, and corrosion-resistant liquid flow batteries and a preparation method thereof, the method comprising the following steps: S1, preparing modified carbon fibers; S2, preparing modified carbon fiber functional masterbatch; S3, preparing a thermally conductive composite material for high-strength, high-toughness, and corrosion-resistant liquid flow batteries. The thermally conductive composite material prepared by the present invention has a fishbone-like microstructure, and is constructed by the interpenetration of carbon fibers and graphene sheets, which improves the covalent bond bonding of the multiphase interface of the material, significantly reduces the interfacial thermal resistance, and helps to improve the thermal conductivity of the material. The process flow of the present invention is simple, the cost is controllable, and it is suitable for large-scale industrial production; the prepared composite material has excellent mechanical properties and chemical corrosion resistance, can meet the various high-performance requirements of liquid flow batteries for materials, and can be widely used in the manufacture of liquid flow batteries and other energy storage systems that require high thermal conductivity and corrosion resistance, meeting the various composite high-performance requirements of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of high-performance composite materials, and in particular to a high-strength, high-toughness, corrosion-resistant thermally conductive composite material for a flow battery and a preparation method thereof. Background Art

[0002] With the widespread application of energy storage systems and electronic devices, the demand for thermally conductive and corrosion-resistant composite materials is increasing. In energy storage systems, especially new energy devices such as flow batteries, thermal conductivity and corrosion resistance are key factors affecting system stability and life. The high temperature and corrosive electrolyte in flow batteries place stringent requirements on materials. Traditional polyethylene-based composite materials are difficult to meet such high-performance requirements due to their low thermal conductivity and insufficient corrosion resistance. In order to achieve efficient heat dissipation and long-term use, there is an urgent need for a composite material with high thermal conductivity, corrosion resistance and high strength and toughness to adapt to harsh working environments. However, how to effectively improve thermal conductivity and enhance corrosion resistance in a polymer matrix remains one of the difficulties in the field of composite material technology.

[0003] Carbon fiber, due to its high strength, high modulus, and corrosion resistance, is often used to enhance the mechanical properties of polymer composites. Graphene, with its excellent thermal conductivity, can significantly improve the thermal conductivity of composites. However, in a polymer matrix, carbon fiber and graphene exhibit poor interfacial compatibility and are prone to agglomeration, resulting in uneven filler dispersion within the matrix, increasing interfacial thermal resistance and weakening overall thermal conductivity. The current technological bottleneck in the field of thermally conductive composite materials is how to effectively disperse and synergize carbon fiber and graphene to fully leverage their reinforcing properties.

[0004] Currently, most composite materials use randomly distributed microstructures, which have significant limitations in terms of filler dispersion and interfacial bonding. Due to the lack of order in the arrangement of carbon fibers and graphene in the matrix, filler agglomeration and high interfacial thermal resistance often result, weakening the overall thermal conductivity of the material. Furthermore, the randomly distributed filler structure makes it difficult to achieve the desired enhancement effect in terms of mechanical properties, and the synergistic effect of carbon fibers and graphene cannot be fully utilized. Conventional processes make it difficult to precisely control the dispersion and interfacial bonding of fillers, resulting in limited improvements in the thermal conductivity, mechanical properties, and corrosion resistance of composite materials. Summary of the Invention

[0005] In response to the above-mentioned shortcomings, the present invention aims to provide a method for preparing a high-strength, high-toughness, corrosion-resistant thermally conductive composite material for liquid flow batteries. During the melt extrusion process, through flow orientation, shear rate, interface compatibility and dispersion control, carbon fiber and graphene form a fishbone-like structure along the flow direction, wherein the carbon fiber serves as the main skeleton to provide mechanical support, and the graphene sheets are arranged in parallel along both sides of the carbon fiber to form a scale-like distribution of thermal and electrical conductive paths, thereby making the prepared thermally conductive composite material have high thermal conductivity, mechanical properties and chemical corrosion resistance.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned object is:

[0007] A method for preparing a high-strength, high-toughness, corrosion-resistant thermally conductive composite material for a flow battery, characterized by comprising the following steps:

[0008] S1. Preparation of modified carbon fiber

[0009] After the continuous carbon fiber tow is cleaned by nitrogen purge, it is placed in an ultraviolet treatment chamber with a set oxygen concentration and irradiated for a set time. The oxygen-containing functional groups of hydroxyl, carboxyl and carbonyl are introduced on the surface of the carbon fiber through ultraviolet-induced atomic oxygen surface activation. The carbon fiber is then cut to a fixed length to prepare a modified carbon fiber.

[0010] S2. Preparation of modified carbon fiber functional masterbatch

[0011] The modified carbon fiber and graphene are dispersed in a peroxide compound aprotic solution of a set concentration according to a set ratio, taken out after immersion in the solution, heated and dried, and the peroxide compound is introduced onto the surface of the carbon fiber and graphene; the treated carbon fiber and graphene are then immersed in an ethylene monomer solution, and the initiator is activated by high temperature and high pressure to induce free radical polymerization of the ethylene monomer on the surface of the carbon fiber and graphene for a set time and discharge, thereby preparing a modified carbon fiber functional masterbatch;

[0012] S3. Preparation of high-strength, high-toughness, corrosion-resistant thermal conductive composite materials for flow batteries

[0013] The modified carbon fiber functional masterbatch in step S2 is introduced into the polyethylene resin in proportion. By regulating the shear rate and melt strength during the in-situ reaction and melt extrusion molding process, a fishbone-like support structure with fibers and graphene sheets interspersed is formed, and the multiphase interface of the composite material is covalently bonded to reduce the interfacial thermal resistance of the material, thereby preparing a thermally conductive composite material for liquid flow batteries with high thermal conductivity, mechanical properties and chemical corrosion resistance.

[0014] The carbon fiber tow is a 1K-48K polyacrylonitrile, asphalt-based, viscose-based or carbon fiber prepared by carbonizing waste fibers, with a diameter of 7-20 μm and a carbon content of ≥99wt%.

[0015] The wavelength range of the ultraviolet light source is 180-190 nm, the oxygen concentration is 21%-99%, the set irradiation time is 10-60 min, and the cutting length of the modified carbon fiber is 1-5 mm.

[0016] The mass ratio of carbon fiber to graphene in step S2 is 1:1~10; the peroxide compound is one or more combinations of benzoyl peroxide, diisopropyl benzene peroxide, di-tert-butyl peroxide, azobisisobutylonitrile, and cumene peroxide, and the aprotic solution is mainly one or more combinations of n-hexane, cyclohexane, petroleum ether, ethyl acetate, ethyl butyrate, benzene, toluene, and xylene.

[0017] In step S2, the concentration of the aprotic solution of the peroxide compound is set to 1-20 mg / mL, the high temperature is 200° C.-300° C., the high pressure is 1-3 MPa, and the polymerization time is 30-120 min.

[0018] The melt extrusion molding process parameters in step S3 include: heating temperature of 180-210° C., screw speed of 300-500 r / min, melt strength of 0.1-0.3 N, and shear rate of 300-800 s-1.

[0019] The ratio in step S3 is: 1 to 30 parts by mass of modified carbon fiber functional masterbatch and 70 to 99 parts by mass of polyethylene resin.

[0020] A high-strength, high-toughness, corrosion-resistant thermally conductive composite material for liquid flow batteries is prepared using the aforementioned method; the carbon fibers and graphene in the composite material form a fishbone-like structure along the flow direction, wherein the carbon fibers serve as the main skeleton to provide mechanical support, and the graphene sheets are arranged in parallel along both sides of the carbon fibers to form a scale-like distribution of thermal and electrical conductive paths. Thus, a microscopic skeleton of the fishbone structure is constructed in the polymer matrix. Through the arrangement of the carbon fibers and graphene, an efficient thermal conductive channel is formed, thereby reducing the interfacial thermal resistance.

[0021] The high-strength, high-toughness, corrosion-resistant thermal conductive composite material for liquid flow batteries and its preparation method provided by the present invention have the following beneficial effects:

[0022] 1. This invention, through the coordinated design of the preparation process, components, ratios, and raw material structure, constructs a fishbone-like microstructure within the polymer matrix. This improves the interfacial bonding strength and thermal conductivity efficiency between fillers, significantly enhancing the thermal conductivity, mechanical strength, and corrosion resistance of the composite material. The rational arrangement of carbon fiber and graphene creates efficient heat conduction channels, reduces interfacial thermal resistance, and significantly improves the thermal conductivity efficiency of the material, meeting the high-performance requirements of various composite applications, such as large-scale energy storage systems.

[0023] 2. The fishbone-like microstructure constructed by the present invention is mainly formed by controlling flow orientation, shear rate, interface compatibility and dispersion during the melt extrusion process, so that carbon fiber and graphene form a fishbone-like structure along the flow direction. The carbon fiber serves as the main skeleton to provide mechanical support, while the graphene sheets are arranged in parallel along both sides of the carbon fiber to form a scale-like distribution of thermal and electrical conductive paths. The prepared thermal conductive composite material has high thermal conductivity, mechanical properties and chemical corrosion resistance.

[0024] 3. The present invention utilizes an in-situ reactive polymerization process to surface-modify carbon fibers, achieving uniform distribution of graphene across the carbon fiber surface. Utilizing melt extrusion molding, the carbon fibers and graphene sheets form a stable fishbone-like structure within the matrix, creating a continuous thermal pathway in multiple dimensions. The microscopic design of the fishbone-like structure increases the interfacial contact area between fillers and significantly reduces interfacial thermal resistance. This allows the composite material to meet thermal conductivity requirements while also possessing excellent chemical resistance and high strength and toughness, satisfying the comprehensive performance requirements of energy storage systems such as flow batteries.

[0025] 4. The process flow of the present invention is simple, the cost is controllable, and it is suitable for large-scale industrial production. It is expected to be promoted and applied in high-performance demanding fields such as large-scale energy storage, electrical and electronic engineering, and thermal management.

[0026] The above is an overview of the technical solution of the invention. The present invention will be further described below in conjunction with specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an SEM image of the modified carbon fiber used to prepare the composite material according to the embodiment of the present invention;

[0028] Figure 2 This is an SEM image of the modified carbon fiber functional masterbatch used to prepare the composite material according to the embodiment of the present invention;

[0029] Figure 3 This is a SEM image of the thermally conductive composite material prepared in an embodiment of the present invention;

[0030] Figure 4 Schematic diagram of the three-dimensional structure of the fishbone-like heat conduction path in the composite material prepared according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose, the specific implementation methods of the present invention are described in detail below in conjunction with preferred embodiments.

[0032] Basic Example

[0033] See attached Figure 1-4The method for preparing the high-strength, high-toughness, corrosion-resistant thermally conductive composite material for liquid flow batteries provided by the present invention comprises the following steps:

[0034] Step S1: preparing modified carbon fiber

[0035] After the continuous carbon fiber tow is cleaned by nitrogen purge, it is placed in a UV treatment chamber with a set oxygen concentration and irradiated for a set time. Through UV-induced atomic oxygen surface activation, oxygen-containing functional groups such as hydroxyl, carboxyl and carbonyl are introduced on the surface of the carbon fiber. After being cut to a fixed length, the modified carbon fiber can be prepared;

[0036] Step S2: preparing modified carbon fiber functional masterbatch

[0037] The modified carbon fiber and graphene are dispersed in a non-proton solution of a peroxide compound at a set concentration in a set ratio. After immersion in the solution, the peroxide compound is taken out and heated and dried to introduce the peroxide compound onto the surface of the carbon fiber and graphene. The treated carbon fiber and graphene are immersed in a solution of ethylene monomer, and the initiator is activated by high temperature and high pressure to induce free radical polymerization of ethylene monomer on the surface of the carbon fiber and graphene for a set time and discharge, thereby preparing the modified carbon fiber functional masterbatch.

[0038] Step S3: Preparation of high-strength, high-toughness, corrosion-resistant thermally conductive composite material for flow batteries

[0039] The modified carbon fiber functional masterbatch in S2 is introduced into the polyethylene resin. By regulating the shear rate and melt strength during the in-situ reaction and melt extrusion molding process, a fishbone-like support structure with fibers and graphene sheets interspersed is formed. This is conducive to achieving covalent bonding at the multiphase interface of the composite material and reducing the interfacial thermal resistance of the material. The prepared thermally conductive composite material has high thermal conductivity, mechanical properties and chemical corrosion resistance.

[0040] The carbon fiber tow is 1K-48K polyacrylonitrile, asphalt-based, viscose-based or carbon fiber prepared by carbonization treatment of waste fibers, with a diameter of 7-20 μm and a carbon content of ≥99wt%.

[0041] The wavelength range of the ultraviolet light source is 180-190 nm, the oxygen concentration is 21%-99%, the irradiation time is 10-60 min, and the cutting length of the modified carbon fiber is 1-5 mm.

[0042] The mass ratio of the carbon fiber to the graphene is 1:1-10, the peroxide compound is mainly one or more combinations of benzoyl peroxide, diisopropyl benzene peroxide, di-tert-butyl peroxide, azobisisobutylonitrile, and cumene peroxide, the aprotic solution is mainly one or more combinations of n-hexane, cyclohexane, petroleum ether, ethyl acetate, ethyl butyrate, benzene, toluene, and xylene, the concentration is 1-20 mg / mL, the high temperature is 200° C.-300° C., the high pressure is 1-3 MPa, and the polymerization time is 30-120 min.

[0043] The melt extrusion molding process parameters include a heating temperature of 180-210°C, a screw speed of 300-500 r / min, a melt strength of 0.1-0.3N, and a shear rate of 300-800s. -1 .

[0044] The modified carbon fiber functional masterbatch is 1 to 30 parts by mass; and the polyethylene is 70 to 99 parts by mass.

[0045] The fishbone-like structure is mainly achieved by controlling flow orientation, shear rate, interface compatibility and dispersion during the melt extrusion process, so that carbon fiber and graphene form a fishbone-like structure along the flow direction. The carbon fiber serves as the main skeleton to provide mechanical support, while the graphene sheets are arranged in parallel along both sides of the carbon fiber to form a scale-like distribution of thermal and electrical conductive paths. The prepared thermally conductive composite material has high thermal conductivity, mechanical properties and chemical corrosion resistance.

[0046] A high-strength, high-toughness, corrosion-resistant thermally conductive composite material for liquid flow batteries is prepared using the aforementioned method. The carbon fibers and graphene in the composite material form a fishbone-like structure along the flow direction, wherein the carbon fibers serve as the main skeleton to provide mechanical support, and the graphene sheets are arranged in parallel along both sides of the carbon fibers to form a scale-like distribution of thermal and electrical conductive paths. In this way, a microscopic skeleton of a fishbone-like structure is constructed in the polymer matrix. Through the arrangement of the carbon fibers and graphene, an efficient thermal conductive channel is formed, thereby reducing the interfacial thermal resistance.

[0047] The following is a detailed description through four specific embodiments.

[0048] Example 1

[0049] See attached Figure 1-2 The method for preparing a high-strength, high-toughness, corrosion-resistant thermally conductive composite material for a flow battery provided by an embodiment of the present invention comprises the following steps:

[0050] S1. Preparation of modified carbon fibers

[0051] A 12K polyacrylonitrile carbon fiber tow with a diameter of 7 μm was cleaned by nitrogen purge and then placed in a 180 nm wavelength ultraviolet treatment chamber with an oxygen concentration of 21% for 10 minutes. After cutting, a modified carbon fiber with a length of 1 mm was prepared.

[0052] S2. Preparation of modified carbon fiber functional masterbatch

[0053] The modified carbon fiber and graphene powder were dispersed in a 1 mg / mL benzoyl peroxide n-hexane solution at a ratio of 1:1. After being immersed in the solution, the mixture was taken out and heated and dried, and then immersed in an ethylene monomer solution. The polyethylene was subjected to free radical polymerization in a high temperature and high pressure environment (temperature 200°C, pressure 1 MPa) for 30 minutes, and then the material was discharged to prepare a modified carbon fiber functional masterbatch.

[0054] S3. Preparation of high-strength, high-toughness, and corrosion-resistant thermally conductive composite materials for flow batteries

[0055] The modified carbon fiber functional masterbatch prepared in step S2 was introduced into the polyethylene resin, and the heating temperature was set to 180-200 °C, the screw speed was 300 r / min, the melt strength was 0.1 N, and the shear rate was 300 s -1 High-strength, high-toughness, and corrosion-resistant thermal conductive composite pipes for liquid flow batteries are prepared by melt extrusion blending, with the modified carbon fiber functional masterbatch accounting for 1% by mass and the polyethylene matrix accounting for 99% by mass.

[0056] Figure 1 is the SEM picture of modified carbon fiber; Figure 1 It can be seen that the surface of the carbon fiber is full of grooves, which significantly improves the surface roughness and interface compatibility of the fiber.

[0057] Figure 2 is the SEM picture of modified carbon fiber functional masterbatch; Figure 2 The interpenetration of graphene sheets and carbon fibers prevents filler aggregation and promotes its dispersion within the resin matrix, forming a stable structure with multiphase interfaces. The ordered nature of the fishbone structure enhances the material's uniformity and helps maintain deformation stability under external stress.

[0058] Figure 3 This is an SEM image of a thermally conductive composite material for high-strength, high-toughness, and corrosion-resistant flow batteries. Figure 3It can be seen that the two-dimensional structure of graphene is laid flat around the carbon fiber, forming parallel heat conduction paths and providing in-plane thermal conductivity. The high thermal conductivity of graphene combined with carbon fiber creates a multi-directional heat conduction path, reducing interfacial thermal resistance and optimizing the overall thermal conduction of the material. The fishbone structure maximizes the properties of carbon fiber and graphene, combining the high strength of carbon fiber with the high thermal conductivity of graphene. The resulting composite material has excellent thermal conductivity, mechanical strength, and corrosion resistance.

[0059] Figure 4 Schematic diagram of the three-dimensional structure of the three-dimensional heat conduction path of the composite material according to the embodiment of the present invention. Figure 4 It can be seen that the modified carbon fibers and graphene sheets are distributed in an orderly manner, the interface compatibility between filler-filler and filler-resin is good, a continuous heat conduction path is formed in the three-dimensional direction, and the phonon transmission and scattering phenomenon is effectively suppressed, which is conducive to the effective improvement of the thermal conductivity of the composite material.

[0060] The embodiments of the present invention construct a fishbone-like micro-skeleton in the polymer matrix through the coordinated design of the preparation process and components, ratios and raw material structures, thereby improving the interfacial bonding strength and thermal conduction efficiency between fillers and significantly enhancing the thermal conductivity, mechanical strength and corrosion resistance of the composite material.

[0061] Example 2

[0062] The preparation method of the high-strength, high-toughness, corrosion-resistant thermally conductive composite material for liquid flow batteries provided by the present invention is substantially the same as that of Example 1, except that the preparation method comprises the following steps:

[0063] S1. Preparation of modified carbon fibers

[0064] A 10 μm diameter, 24K viscose-based carbon fiber tow was cleaned by nitrogen purge and then placed in a 40% oxygen concentration, 182 nm wavelength UV treatment chamber for 25 minutes. After cutting, a modified carbon fiber with a length of 3 mm was prepared.

[0065] S2. Preparation of modified carbon fiber functional masterbatch

[0066] The modified carbon fiber and graphene powder were dispersed in a 10 mg / mL di-tert-butyl peroxide n-hexane solution at a ratio of 1:3. After being immersed in the solution, the mixture was taken out and heated and dried, and then immersed in an ethylene monomer solution. The polyethylene was subjected to free radical polymerization in a high temperature and high pressure environment (temperature 220°C, pressure 1.5 MPa) for 20 minutes, and then the material was discharged to prepare a modified carbon fiber functional masterbatch.

[0067] S3. Preparation of high-strength, high-toughness, and corrosion-resistant thermally conductive composite materials for flow batteries

[0068] The modified carbon fiber functional masterbatch prepared in step S2 was introduced into the polyethylene resin, and the heating temperature was set to 180-200 °C, the screw speed was 350 r / min, the melt strength was 0.2 N, and the shear rate was 400 s -1 High-strength, high-toughness, and corrosion-resistant thermal conductive composite pipes for liquid flow batteries are prepared by melt extrusion blending, with the modified carbon fiber functional masterbatch accounting for 10% by mass and the polyethylene matrix accounting for 90% by mass.

[0069] Example 3

[0070] The preparation method of the high-strength, high-toughness, corrosion-resistant thermally conductive composite material for liquid flow batteries provided by the present invention is substantially the same as that of Examples 1-2, except that the preparation method comprises the following steps:

[0071] S1. Preparation of modified carbon fibers

[0072] A 12 μm diameter, 36K pitch-based carbon fiber tow was cleaned by nitrogen purge and then placed in a 188 nm wavelength UV treatment chamber with 75% oxygen concentration for 40 minutes. After cutting, a modified carbon fiber with a length of 4 mm was prepared.

[0073] S2. Preparation of modified carbon fiber functional masterbatch

[0074] The modified carbon fiber and graphene powder were dispersed in a 15 mg / mL azobisisobutyronitrile benzene solution at a ratio of 1:8. After being immersed in the solution, the mixture was taken out and heated and dried, and then immersed in an ethylene monomer solution. The polyethylene was subjected to free radical polymerization in a high temperature and high pressure environment (temperature 220°C, pressure 2.5 MPa) for 80 minutes, and then the material was discharged to prepare a modified carbon fiber functional masterbatch.

[0075] S3. Preparation of high-strength, high-toughness, and corrosion-resistant thermally conductive composite materials for flow batteries

[0076] The modified carbon fiber functional masterbatch prepared in step S2 was introduced into the polyethylene resin, and the heating temperature was set to 180-200 °C, the screw speed was 400 r / min, the melt strength was 0.2 N, and the shear rate was 600 s -1 High-strength, high-toughness, and corrosion-resistant thermal conductive composite pipes for liquid flow batteries are prepared by melt extrusion blending, with the modified carbon fiber functional masterbatch accounting for 20% by mass and the polyethylene matrix accounting for 80% by mass.

[0077] Example 4

[0078] The preparation method of the high-strength, high-toughness, corrosion-resistant thermally conductive composite material for liquid flow batteries provided by the present invention is substantially the same as that of Examples 1-3, except that the preparation method comprises the following steps:

[0079] S1. Preparation of modified carbon fibers

[0080] A 20 μm diameter, 48K pitch-based carbon fiber tow was cleaned by nitrogen purge and then placed in a 190 nm wavelength UV treatment chamber with 99% oxygen concentration for 60 minutes. After cutting, a modified carbon fiber with a length of 5 mm was prepared.

[0081] S2. Preparation of modified carbon fiber functional masterbatch

[0082] The modified carbon fiber and graphene powder were dispersed in a 20 mg / mL benzoyl peroxide n-hexane solution at a ratio of 1:10. After being immersed in the solution, the mixture was taken out and heated and dried, and then immersed in an ethylene monomer solution. The polyethylene was subjected to free radical polymerization in a high temperature and high pressure environment (temperature 300°C, pressure 3MPa) for 120 minutes, and then the material was discharged to prepare a modified carbon fiber functional masterbatch.

[0083] S3. Preparation of high-strength, high-toughness, and corrosion-resistant thermally conductive composite materials for flow batteries

[0084] The modified carbon fiber functional masterbatch prepared in step S2 was introduced into the polyethylene resin, and the heating temperature was set to 190-210 °C, the screw speed was 500 r / min, the melt strength was 0.3 N, and the shear rate was 800 s -1 High-strength, high-toughness, and corrosion-resistant thermal conductive composite pipes for liquid flow batteries are prepared by melt extrusion blending, with the modified carbon fiber functional masterbatch accounting for 30% by mass and the polyethylene matrix accounting for 70% by mass.

[0085] Application Example 1

[0086] The thermal conductivity, tensile strength and corrosion resistance of the high-strength, high-toughness, corrosion-resistant and thermally conductive composite materials prepared in Examples 1 to 4 were tested, and the results are shown in the following table.

[0087]

[0088] As can be seen from the above table, the high-strength, high-toughness, corrosion-resistant and thermally conductive composite materials prepared in Examples 1 to 4 of the present invention, the preparation method and composite material of the present invention, through flow orientation, shear rate, interface compatibility and dispersion control, make the carbon fiber and graphene form a fishbone-like structure along the flow direction, wherein the carbon fiber serves as the main skeleton to provide mechanical support, and the graphene sheets are arranged in parallel along both sides of the carbon fiber to form a scale-like distribution of thermal and electrical conductive paths, thereby making the prepared thermally conductive composite material have high thermal conductivity, mechanical properties and chemical corrosion resistance.

[0089] The composite materials provided by the above-mentioned embodiments of the present invention have a fishbone-like microstructure constructed by the interpenetration of carbon fibers and graphene sheets, which improves the covalent bonding of the multiphase interface of the material, significantly reduces the interfacial thermal resistance, and helps to improve the thermal conductivity of the material. In addition, the composite material can simultaneously possess excellent mechanical properties and chemical corrosion resistance, and can meet the performance requirements of liquid flow batteries for materials. The preparation process of the present invention is simple and cost-controlled, and is suitable for large-scale industrial production. It can meet the needs of high-performance technical fields such as large-scale energy storage, electrical and electronic engineering, and thermal management, and can be widely used in the manufacture of liquid flow batteries and other energy storage systems that require high thermal conductivity and corrosion resistance.

[0090] In addition, it should be noted that within the scope of the above-described invention, other implementation plans obtained by selecting other preparation processes, components and their proportions can achieve the technical effects described in the invention, so they will not be listed one by one.

[0091] The above description is merely a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any technical features that are the same or similar to those of the above embodiments of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength, high-toughness, corrosion-resistant thermally conductive composite material for a flow battery, characterized in that: The following steps are involved: S1. Preparation of modified carbon fiber After the continuous carbon fiber tow is cleaned by nitrogen purge, it is placed in an ultraviolet treatment chamber with a set oxygen concentration and irradiated for a set time. The oxygen-containing functional groups of hydroxyl, carboxyl and carbonyl are introduced on the surface of the carbon fiber through ultraviolet-induced atomic oxygen surface activation. The carbon fiber is then cut to a fixed length to prepare a modified carbon fiber. S2. Preparation of modified carbon fiber functional masterbatch The modified carbon fiber and graphene are dispersed in a peroxide compound aprotic solution of a set concentration according to a set ratio, taken out after immersion in the solution, heated and dried, and the peroxide compound is introduced onto the surface of the carbon fiber and graphene; the treated carbon fiber and graphene are then immersed in an ethylene monomer solution, and the initiator is activated by high temperature and high pressure to induce free radical polymerization of the ethylene monomer on the surface of the carbon fiber and graphene for a set time and discharge, thereby preparing a modified carbon fiber functional masterbatch; The concentration of the aprotic solution of the peroxide compound is set to 1-20 mg / mL, the high temperature is 200°C-300°C, the high pressure is 1-3 MPa, and the polymerization time is 30-120 min. S3. Preparation of high-strength, high-toughness, corrosion-resistant thermal conductive composite materials for flow batteries The modified carbon fiber functional masterbatch in step S2 is introduced into the polyethylene resin in proportion, and the shear rate and melt strength are controlled during the in-situ reaction and melt extrusion molding process to form a fishbone-like support structure in which the fibers and graphene sheets are interspersed. The multiphase interface of the composite material is covalently bonded to reduce the interfacial thermal resistance of the material, thereby preparing a thermally conductive composite material for liquid flow batteries with high thermal conductivity, mechanical properties, and chemical corrosion resistance. The ratio of modified carbon fiber functional masterbatch to polyethylene resin is: 1 to 30 parts by mass of modified carbon fiber functional masterbatch and 70 to 99 parts by mass of polyethylene resin; Melt extrusion molding process parameters include: heating temperature 180~210℃, screw speed 300~500r / min, melt strength 0.1~0.3N, shear rate 300~800s -1 .

2. The method for preparing a thermally conductive composite material for a high-strength, high-toughness, corrosion-resistant flow battery according to claim 1, characterized in that: The carbon fiber tow is a 1K-48K polyacrylonitrile, asphalt-based, viscose-based or carbon fiber prepared by carbonizing waste fibers, with a diameter of 7-20 μm and a carbon content of ≥99wt%.

3. The method for preparing a thermally conductive composite material for a high-strength, high-toughness, corrosion-resistant flow battery according to claim 1, wherein: The wavelength range of the ultraviolet light source is 180-190 nm, the oxygen concentration is 21%-99%, the set irradiation time is 10-60 min, and the cutting length of the modified carbon fiber is 1-5 mm.

4. The method for preparing a thermally conductive composite material for a high-strength, high-toughness, corrosion-resistant flow battery according to claim 1, wherein: The mass ratio of carbon fiber to graphene in step S2 is 1:1~10; the peroxide compound is one or more combinations of benzoyl peroxide, diisopropyl benzene peroxide, di-tert-butyl peroxide, azobisisobutylonitrile, and cumene peroxide, and the aprotic solution is one or more combinations of n-hexane, cyclohexane, petroleum ether, ethyl acetate, ethyl butyrate, benzene, toluene, and xylene.

5. A thermally conductive composite material for high-strength, high-toughness, corrosion-resistant liquid flow battery, characterized in that: The invention relates to a novel cellulose acetate resin, which is prepared according to the method according to any one of claims 1 to 4.

6. The thermally conductive composite material for high-strength, high-toughness, corrosion-resistant liquid flow battery according to claim 5, characterized in that: The carbon fibers and graphene in this composite material form a fishbone-like structure along the flow direction, in which the carbon fibers serve as the main skeleton to provide mechanical support, and the graphene sheets are arranged in parallel along both sides of the carbon fibers to form a scale-like distribution of thermal and electrical conductive pathways. This constructs a fishbone-like microscopic skeleton in the polymer matrix. Through the arrangement of carbon fibers and graphene, an efficient thermal conductive channel is formed to reduce the interfacial thermal resistance.

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