Preparation method of carbon / carbon thermal field composite material, carbon / carbon thermal field composite material and application thereof

Abstract

The present application relates to the technical field of carbon / carbon composite material, in particular to a preparation method of carbon / carbon thermal field composite material, carbon / carbon thermal field composite material and application thereof.The preparation method of carbon / carbon thermal field composite material comprises the following steps: mixing carbon fiber powder, carbonization material, liquid binder and organic solvent to prepare a mixture, wherein the mixture comprises 5-30% of carbon fiber powder, 30-60% of carbonization material, 10-30% of liquid binder and 1-5% of organic solvent by mass percentage; and performing cold pressing forming, curing treatment and carbonization treatment on the mixture to prepare the carbon / carbon thermal field composite material.The preparation method is simple in process, and the prepared carbon / carbon thermal field composite material has the advantages of low density, high compressive strength, good thermal conductivity and long service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon / carbon composite materials, in particular to a preparation method of carbon / carbon thermal field composite material, the carbon / carbon thermal field composite material and application thereof. BACKGROUND

[0002] In a high-temperature thermal field environment of a lithium negative electrode material, the high-temperature resistant composite material is used as a main container in the production process of the graphitized furnace of the negative electrode material, and bears the tasks of bearing, heat conduction and isolating mixed materials in the graphitization production. As a high-temperature resistant composite material, the material is required to have high compressive and bending strength, strong high-temperature ablation resistance and excellent heat preservation performance.

[0003] The commonly used lithium electric thermal field material in the industry is mainly graphite material and petroleum coke material, wherein the graphite material is expensive and has large processing loss; and the petroleum coke material has low strength, short service life and large loss in the transportation and use process. Therefore, how to improve the strength of the material, reduce the loss of the material and improve the service life of the material has become a technical problem focused in the technical field. SUMMARY

[0004] In order to solve the above problems, the present application provides a preparation method of carbon / carbon thermal field composite material, which has the advantages of simple process, low density, high compressive strength, good heat conduction performance and long service life of the prepared carbon / carbon thermal field composite material.

[0005] The specific technical scheme of the present application is as follows:

[0006] A preparation method of carbon / carbon thermal field composite material, comprising the following steps:

[0007] Mixing carbon fiber powder, carbonization material, liquid binder and organic solvent to prepare a mixture, wherein the mixture comprises 5% to 30% of carbon fiber powder, 30% to 60% of carbonization material, 10% to 30% of liquid binder and 1% to 5% of organic solvent by mass percentage;

[0008] Cold pressing, curing treatment and carbonization treatment are performed on the mixture to prepare the carbon / carbon thermal field composite material;

[0009] The carbonization treatment comprises first-stage carbonization and second-stage carbonization.

[0010] The heating rate of the first-stage carbonization is 5℃ / h to 30℃ / h; the heating rate of the second-stage carbonization is 40℃ / h to 80℃ / h; and the second-stage carbonization temperature is higher than the first-stage carbonization temperature.

[0011] In some embodiments, the carbonization temperature of the first-stage carbonization is 600℃ to 750℃; and the holding time is 2h to 5h.

[0012] In some embodiments, the carbonization temperature of the second stage carbonization is 800-1500℃, and the holding time is 1-20h.

[0013] In some embodiments, the average particle size of the carbon fiber powder is 25-800μm.

[0014] In some embodiments, the carbonization material comprises one or more of carbon black, graphite powder and petroleum coke.

[0015] In some embodiments, the average particle size of the carbonization material is 150-2000μm.

[0016] In some embodiments, the carbon content of the carbonization material is greater than 99%.

[0017] In some embodiments, the sulfur content of the carbonization material is less than 0.5%.

[0018] In some embodiments, the cold-pressing pressure of the cold-pressing is 50-300MPa.

[0019] In some embodiments, the cold-pressing time of the cold-pressing is 60-180s.

[0020] In some embodiments, the heating rate of the curing treatment is 4-8℃ / min.

[0021] In some embodiments, the temperature of the curing treatment is 120-300℃, and the holding time is 1-5h.

[0022] In some embodiments, the liquid binder comprises one or more of phenolic resin, epoxy resin, unsaturated resin and asphalt glue.

[0023] In some embodiments, the organic solvent comprises one or more of methanol, ethanol, furfuryl alcohol, ethyl acetate, toluene and chloroform.

[0024] A carbon / carbon thermal field composite material prepared by the method of any of the above embodiments.

[0025] Use of the above carbon / carbon thermal field composite material in lithium battery high-temperature thermal field materials.

[0026] The present application has the following advantages:

[0027] The present application mixes carbon fiber powder, carbonization material, liquid binder and organic solvent according to specific proportions by wet mixing, wherein the carbon fiber powder can effectively disperse the carbon fiber, the product is more uniform and better in quality; the wet mixing of the liquid binder makes the mixing of the raw materials more uniform and sufficient, and the working environment is friendly; the cold pressing forming method is used instead of the traditional mechanical processing graphite product and hot pressing forming, and the cold pressing forming has lower cost and higher efficiency; the two-stage carbonization process can prevent the product from cracking during carbonization and reduce cost and energy consumption. In summary, the present application mixes by wet mixing according to specific proportions, and then carries out solidification treatment and two-stage carbonization treatment after cold pressing forming, which greatly improves the product preparation efficiency. The carbon / carbon thermal field composite material prepared by the present application has high compressive and bending strength, excellent heat preservation performance, and strong high-temperature ablation resistance, and has a service life of more than half a year in a vacuum or protective atmosphere above 3000℃, which is much longer than the service life of traditional high-temperature graphite materials. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 Metallographic microstructure of the carbon / carbon thermal field composite material synthesized for Example 1;

[0029] Figure 2 Metallographic microstructure of the carbon / carbon thermal field composite material synthesized for Example 2. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] At present, among all composite material reinforcement technologies, the effect of fiber reinforcement technology is one of the best technologies. Carbon fiber is the best choice for reinforcement material because of its ultra-high physical strength, good electrical conductivity and thermal conductivity, and excellent ablation resistance. Carbon fiber reinforced carbon / carbon composite material greatly improves the compressive and bending strength of the material and prolongs the service life of the material, which is an ideal carbon / carbon high-temperature thermal field composite material.

[0033] Many researchers have studied this, for example, some researchers spray silicon carbide slurry on the surface of carbon fiber felt and carbon fiber cloth, after alternating layering, needling, drying and warm pressure curing, a composite blank is obtained; then the composite blank is carbonized, pyrolytic carbon and silicon carbide interface phase are alternately deposited, finally pyrolytic carbon deposition and densification treatment are carried out, a carbon fiber reinforced silicon carbide ceramic matrix composite material is obtained, since silicon carbide will decompose above 2400℃, the composite material with silicon carbide ceramic as the matrix in this scheme is not suitable for high temperature thermal field. For example, a short carbon fiber reinforced phenolic resin matrix composite material has been reported, short carbon fiber bundles coated with a phenolic resin layer are prepared, the short carbon fiber bundles coated with a phenolic resin layer are mixed with phenolic resin powder, and then cold pressing and hot pressing are carried out to obtain the composite material, the use and processing cost of the fiber in this scheme are very high, and the above-mentioned material has not been subjected to high temperature carbonization treatment, and therefore cannot be applied to high temperature thermal field. In the present application, carbon fiber powder is used as the reinforcing phase, carbonization material is used as the matrix, adhesive is used as the forming agent, and other additives are used as auxiliary materials, and a high temperature thermal field composite material is prepared through mixing, cold pressing, drying and high temperature carbonization.

[0034] The specific technical solutions are as follows:

[0035] A preparation method of a carbon / carbon thermal field composite material, comprising the following steps:

[0036] S110: mixing carbon fiber powder, carbonization material, liquid adhesive and organic solvent to prepare a mixture, wherein the mixture comprises 5% to 30% of carbon fiber powder, 30% to 60% of carbonization material, 10% to 30% of liquid adhesive and 1% to 5% of organic solvent in terms of mass percentage.

[0037] In some examples, the average particle size of the carbon fiber powder is 25 μm to 850 μm.

[0038] In the present application, if the particle size of the carbon fiber powder is too large, the mixing process may be uneven, the strength and modulus of the composite material may be reduced, the transmission of internal stress of the composite material may be hindered, the fracture toughness of the material may be reduced, and the specific surface area of the carbon fiber powder may be small, the heat transfer path may be reduced, and the thermal conductivity may be reduced. If the particle size of the carbon fiber powder is too small, the strength of the carbon fiber may be reduced, the overall strength of the product may be reduced, the preparation may be difficult, and the cost may be increased.

[0039] In some examples, the carbonization material comprises one or more of carbon black, graphite powder and petroleum coke.

[0040] In some examples, the average particle size of the carbonization material is 150 μm to 2000 μm.

[0041] In some examples, the carbon content of the carbonization material is greater than 99%.

[0042] In some examples, the sulfur content of the carbonization material is less than 0.5%.

[0043] In the present invention, selecting the appropriate particle size range of the carbonization material helps to ensure uniform dispersion of the carbonization material and avoid the formation of agglomerates that can affect the thermal conductivity, mechanical properties, and other properties of the material. The carbon content can affect the thermal conductivity of the carbon / carbon composite material. As the carbon content increases, the thermal conductivity of the material will also increase. Within a certain range, the mechanical properties such as strength and toughness of the material will also increase. However, when the carbon content is too high, the brittleness of the material will increase, leading to a decrease in mechanical properties. Therefore, in order to achieve the best mechanical properties, it is necessary to control the carbon content. Sulfur can have a negative impact on the performance of the material, such as the reaction of sulfur elements with other elements in the carbon / carbon composite material at high temperatures, which can cause corrosion and degradation of the material. This corrosion phenomenon is particularly severe in high-temperature environments, therefore, reducing the sulfur content helps to improve the high-temperature stability of the carbon / carbon composite material.

[0044] In some examples, the liquid binder includes one or more of phenolic resin, epoxy resin, unsaturated resin, and asphalt glue.

[0045] In some specific examples, the solid content of the phenolic resin is > 70%.

[0046] In some specific examples, the carbon residue rate of the phenolic resin is > 40%.

[0047] In some specific examples, the viscosity of the phenolic resin is 2000 mPa·s ~ 22000 mPa·s.

[0048] In some specific examples, the solid content of the epoxy resin is > 70%.

[0049] In some specific examples, the carbon residue rate of the epoxy resin is > 40%.

[0050] In some specific examples, the viscosity of the epoxy resin is 2000 mPa·s ~ 22000 mPa·s.

[0051] In some specific examples, the solid content of the unsaturated resin is > 70%.

[0052] In some specific examples, the carbon residue rate of the unsaturated resin is > 40%.

[0053] In some specific examples, the viscosity of the unsaturated resin is 2000 mPa·s~22000 mPa·s.

[0054] In some specific examples, the residual carbon rate of the pitch glue is >50%.

[0055] In some specific examples, the solid content of the pitch glue is >80%.

[0056] In some examples, the organic solvent includes one or more of methanol, ethanol, furfuryl alcohol, ethyl acetate, toluene, and chloroform, but is not limited thereto.

[0057] The present application adopts a liquid binder wet mixing method, which makes the mixing between raw materials more uniform and sufficient, reduces the dust pollution of carbon fiber powder, and makes the working environment friendly.

[0058] S210: cold pressing, drying treatment and carbonization treatment are performed on the mixture to prepare the carbon / carbon thermal field composite material;

[0059] The carbonization treatment includes first-stage carbonization and second-stage carbonization.

[0060] The heating rate of the first-stage carbonization is 5℃ / h~30℃ / h, the heating rate of the second-stage carbonization is 40℃ / h~80℃ / h, and the second-stage carbonization temperature is higher than the first-stage carbonization temperature.

[0061] In some examples, the carbonization temperature of the first-stage carbonization is 600℃~750℃, and the holding time is 2h~5h.

[0062] In some examples, the carbonization temperature of the second-stage carbonization is 800℃~1500℃, and the holding time is 1h~20h.

[0063] In the carbonization treatment of the present application, the first-stage carbonization at a low heating rate is performed due to the large amount of volatile gas of the resin glue, which can prevent the product from cracking during the carbonization process; the second-stage carbonization at a high heating rate is performed due to the small amount of exhaust gas, which can reduce the cost and energy consumption.

[0064] After the short-time cold pressing forming treatment, the drying treatment and the carbonization treatment can be concentrated in the carbonization furnace, compared with the traditional process which needs to be in the pressure container for a long time for solidification forming process and then high-temperature carbonization treatment, the preparation process of the present application is simpler, which greatly improves the product preparation efficiency and effectively reduces the cost.

[0065] In some examples, the cold pressing pressure of the cold pressing forming is 50MPa~300MPa.

[0066] In some examples, the cold-pressing time of the cold-pressing forming is 60s-180s.

[0067] In some examples, the cold-pressing forming of the application can be one-time cold-pressing forming or segmented cold-pressing forming; optionally, the cold-pressing forming of the application is one-time cold-pressing forming.

[0068] The application adopts one-time cold-pressing forming mode, only needs to perform pressure maintaining treatment under a certain pressure for a short time, and has lower cost and higher efficiency compared with traditional mechanical processing graphite products and hot-pressing forming process.

[0069] In some examples, the heating rate during the curing treatment is 4℃ / min-8℃ / min.

[0070] In some examples, the curing treatment temperature is 120℃-300℃, and the holding time is 1h-5h.

[0071] The application further comprises a process of pretreating the carbon fibers to prepare carbon fiber powder before the step S110.

[0072] In some examples, the carbon fibers include one or more of carbon fiber prepreg corner scraps, waste carbon fiber cloth and carbon fiber web, but are not limited thereto.

[0073] In one example, the pretreatment includes washing, shearing and crushing and grinding the recycled carbon fibers to prepare the carbon fiber powder.

[0074] The carbon fiber raw material of the application can recycle the recycled carbon fibers, effectively saves the cost, reduces the emission of carbon waste, effectively reduces the waste of resources and the pollution of the environment; further, the carbon fibers are effectively dispersed in the mixing process by preparing the carbon fiber powder through the pretreatment, the raw materials are more uniformly mixed, and the quality is better.

[0075] A carbon / carbon thermal field composite material is prepared by the preparation method of any one of the above examples.

[0076] In some examples, the density of the carbon / carbon thermal field composite material is 1.4 g / cm 3 -1.7g / cm 3 .

[0077] In some examples, the thermal conductivity of the carbon / carbon thermal field composite material is 40 W / (m·K)-80 W / (m·K).

[0078] In some examples, the bending strength of the carbon / carbon thermal field composite material is 50 MPa-80MPa.

[0079] In some examples, the carbon / carbon thermal field composite has a compressive strength of 100 MPa to 200 MPa.

[0080] In some examples, the carbon / carbon thermal field composite has a resistivity of 15 μΩ·m to 20 μΩ·m.

[0081] Use of the carbon / carbon thermal field composite in a lithium battery high-temperature thermal field material.

[0082] In some examples, the carbon / carbon thermal field composite can be used in a carbon / carbon anode, a carbon / carbon crucible, a carbon / carbon box plate, a carbon / carbon column, and other lithium battery thermal field products.

[0083] Embodiments of the present application will be described in detail below with reference to examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application. In the following examples, the experimental methods are not specified, and the priority is given to the instructions given in the present application. The experimental methods can also be performed according to the experimental manuals or conventional conditions in the art, or according to the conditions suggested by the manufacturers, or according to the known experimental methods in the art.

[0084] In the following specific examples, the measurement parameters of the raw material components may, without specific instructions, have slight deviations within the weighing accuracy range. The temperature and time parameters allow for acceptable deviations caused by instrument testing accuracy or operation accuracy.

[0085] The raw material reagent information used in the following examples and comparative examples is as follows:

[0086] Phenolic resin, PF4070;

[0087] Calcined petroleum coke, particle size 0 mm to 2 mm, sulfur content <0.5%;

[0088] Carbon black, particle size <800 μm;

[0089] Asphalt, medium-temperature asphalt;

[0090] Carbon fiber, T300.

[0091] Example 1

[0092] Carbon fiber pretreatment: The recycled carbon fiber prepreg scraps are ground by a grinding machine. The carbon fiber powder below the 50-mesh screen is collected.

[0093] Mixing: The calcined petroleum coke is used as the carbonation material, the phenolic resin is used as the binder, and the ethanol is used as the organic solvent. 20% of the carbon fiber powder, 60% of the petroleum coke, 15% of the phenolic resin, and 5% of the ethanol are mixed uniformly.

[0094] Cold pressing: Put the above mixture into a customized mold, and press under the condition of cold pressing pressure of 100 MPa and cold pressing time of 60 s.

[0095] Curing: The material obtained by cold pressing is heated from room temperature to 220 °C in 30 min, and is kept at 220 °C for 5 h.

[0096] High-temperature carbonization: The dried material is continuously subjected to high-temperature carbonization treatment, specifically: the carbonization furnace is heated from 220 °C to 600 °C in 40 h, kept at 600 °C for 5 h, and subjected to the first-stage carbonization; then the carbonization furnace is heated from 600 °C to 950 °C in 5 h, kept at 950 °C for 10 h, and subjected to the first-stage carbonization.

[0097] The material after high-temperature carbonization is cut into standard samples for performance testing.

[0098] Figure 1 The metallographic microstructure of the carbon / carbon thermal field composite material synthesized in Example 1 is shown in FIG. 1. Figure 1 It can be seen that a large number of fibers are distributed on the surface of the composite material, and the fibers are uniformly distributed and well combined with the matrix.

[0099] Example 2

[0100] Carbon fiber pretreatment: The edge and corner scraps of the recycled carbon fiber preform are ground by a grinding machine. The carbon fiber powder below 100 mesh is collected after passing through a 100-mesh screen.

[0101] Mixing: Carbon black is used as a carbonation material, a mixture of phenolic resin: liquid pitch = 2:1 (mass ratio) is used as a binder, and methanol is used as an organic solvent. In mass percentage, 25% of carbon fiber powder, 50% of carbon black, 20% of binder and 5% of methanol are uniformly mixed.

[0102] Cold pressing: Put the above mixture into a customized mold, and press under the condition of cold pressing pressure of 300 MPa and cold pressing time of 120 s.

[0103] Drying: The material obtained by cold pressing is heated from room temperature to 280 °C in 30 min, and is kept at 280 °C for 5 h.

[0104] High-temperature carbonization: The dried material is continuously subjected to high-temperature carbonization treatment, specifically: the carbonization furnace is heated from 220 °C to 600 °C in 35 h, kept at 600 °C for 2 h, and subjected to the first-stage carbonization; then the carbonization furnace is heated from 600 °C to 1100 °C in 10 h, kept at 1100 °C for 20 h.

[0105] The material after high-temperature carbonization is cut into standard samples for performance testing.

[0106] Figure 2The metallographic microstructure of the carbon / carbon thermal field composite material synthesized in Example 2 is shown in Figure 2. It can be seen that the fibers in various directions are distributed on the surface of the composite material, and are combined more tightly. Figure 2

[0107] Example 3

[0108] The preparation method of Example 3 is basically the same as that of Example 1, except that the proportions of the raw materials in the mixing step are different. In Example 3, 30% of carbon fiber powder, 45% of petroleum coke, 20% of phenolic resin and 5% of ethanol are uniformly mixed in terms of mass percentage.

[0109] Example 4

[0110] The preparation method of Example 4 is basically the same as that of Example 2, except that the proportions of the raw materials in the mixing step are different. In Example 4, 30% of carbon fiber powder, 50% of carbon black, 18% of binder and 2% of methanol are uniformly mixed in terms of mass percentage.

[0111] Example 5

[0112] The preparation method of Example 5 is basically the same as that of Example 1, except that the cold pressing forming process is different. In Example 5, the cold pressing forming process is as follows: the pressure is increased to 100 MPa after being kept at 80 MPa for 60 s.

[0113] Comparative Example 1

[0114] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that the carbonization process is different. In Example 6, the first-stage carbonization process is as follows: the carbonization furnace is heated from 220°C to 600°C in 10 h, and kept at 600°C for 5 h for the first-stage carbonization; then the carbonization furnace is heated from 600°C to 950°C in 10 h, and kept at 950°C for 5 h for the second-stage carbonization. The product of Comparative Example 1 cracks during the carbonization process, and the thermodynamic performance fails.

[0115] Comparative Example 2

[0116] The preparation method of Comparative Example 2 is basically the same as that of Example 1, except that the carbonization process is different. In Example 7, the carbonization process is as follows: the carbonization furnace is directly heated from 220°C to 950°C in 20 h, and kept at 950°C for 10 h. The product of Comparative Example 2 also cracks during the carbonization process, and the thermodynamic performance fails.

[0117] Comparative Example 3

[0118] The preparation method of Comparative Example 3 is basically the same as that of Example 1, except that the mixing ratio is different. In Comparative Example 3, 2% of carbon fiber powder, 78% of petroleum coke, 15% of phenolic resin and 5% of ethanol are uniformly mixed in terms of mass percentage.​

[0119] Comparative Example 4

[0120] Comparative Example 4 is basically the same as the preparation method of Example 1, except that the mixing ratio is different. Comparative Example 4 is: 20% carbon fiber powder, 35% petroleum coke, 40% phenolic resin and 5% ethanol are mixed uniformly in mass percentage.

[0121] Comparative Example 5

[0122] Comparative Example 5 is basically the same as the preparation method of Example 1, except that the binder used in the mixing is different. Comparative Example 5 uses powdered phenolic resin as the binder, and the raw material ratio and experimental conditions are consistent. The results show that Comparative Example 5 cannot achieve cold pressing, and the pressed material cannot be shaped.

[0123] Comparative Example 6

[0124] Comparative Example 6 is basically the same as the preparation method of Example 1, except that the pressing method is different. Comparative Example 6 uses hot pressing instead of cold pressing, and the hot pressing temperature is 150°C. The results show that the material pressed in Comparative Example 6 also cannot be shaped.

[0125] The thermal field composite materials prepared in the above examples and comparative examples are tested for performance. The bending strength is tested by ETM504C microcomputer-controlled electronic universal testing machine, according to GB / T 40398.2; the compressive strength is tested by ETM504C microcomputer-controlled electronic universal testing machine, according to GB / T 1431; the resistivity is tested by WDT carbon material resistivity tester, according to GB / T 24521-2018; the thermal conductivity difference is tested by DRPL-I thermal conductivity tester, according to GB / T 8722-2019; and the density is tested by the drainage method. The test results are shown in Table 1 below.

[0126] Table 1

[0127]

[0128] From Table 1 above, it can be seen that the carbon / carbon thermal field composite materials prepared by the technical solutions of Examples 1-5 have high compressive and bending strength, excellent heat preservation performance, and strong high-temperature ablation resistance. They have a service life of more than half a year in a vacuum or protective atmosphere at 3000°C or above, far exceeding the service life of traditional high-temperature graphite materials. The carbon fiber raw material involved in the present case comes from recycled carbon fiber, effectively saving costs and reducing resource waste.

[0129] Any combination of the technical features in the above-described embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, as long as the combination of the technical features does not exist in contradiction, it shall be considered within the scope of the present disclosure.

[0130] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it shall not be understood as a limitation on the patent scope of the present application. It shall be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these shall be within the protection scope of the present application. Therefore, the protection scope of the present application patent shall be subject to the appended claims.

Claims

1. A method for preparing a carbon / carbon thermal field composite material, characterized in that, Includes the following steps: A mixture is prepared by mixing carbon fiber powder, carbon refining material, liquid binder and organic solvent. The mixture comprises 5% to 30% carbon fiber powder, 30% to 60% carbon refining material, 10% to 30% liquid binder and 1% to 5% organic solvent by mass percentage. The mixture is subjected to cold pressing, curing and carbonization to prepare the carbon / carbon thermal field composite material; The carbonization process includes a first-stage carbonization and a second-stage carbonization. The heating rate for the first stage of carbonization is 5℃ / h to 30℃ / h; the heating rate for the second stage of carbonization is 40℃ / h to 80℃ / h; the carbonization temperature for the second stage is higher than that for the first stage. The carbonization temperature for the first stage of carbonization is 600℃~750℃; the holding time is 2h~5h. The carbonization temperature for the second stage of carbonization is 800℃~1500℃; the holding time is 1h~20h.

2. The method for preparing the carbon / carbon thermal field composite material as described in claim 1, characterized in that, The average particle size of the carbon fiber powder is 25μm~800μm.

3. The method for preparing the carbon / carbon thermal field composite material as described in claim 1, characterized in that, The carbon-enhancing material includes one or more of carbon black, graphite powder, and petroleum coke.

4. The method for preparing the carbon / carbon thermal field composite material as described in claim 3, characterized in that, The carbon-enhancing material satisfies one or more of the following (1) to (3): (1) The average particle size is 150 μm to 2000 μm; (2) Carbon content greater than 99%; (3) Sulfur content is less than 0.5%.

5. The method for preparing the carbon / carbon thermal field composite material according to any one of claims 1 to 4, characterized in that, The conditions for cold pressing include one or more of the following (1) to (2): (1) The cold pressing pressure is 50MPa~300MPa; (2) The cold pressing time is 60s~180s.

6. The method for preparing the carbon / carbon thermal field composite material according to any one of claims 1 to 4, characterized in that, The curing conditions include one or more of the following (1) to (2): (1) The heating rate is 4℃ / min to 8℃ / min; (2) The curing temperature is 120℃~300℃ and the heat preservation time is 1h~5h.

7. The method for preparing the carbon / carbon thermal field composite material according to any one of claims 1 to 4, characterized in that, Satisfy one or more of the following (1)~(2): (1) The liquid binder includes one or more of phenolic resin, epoxy resin, unsaturated resin and asphalt adhesive; (2) The organic solvent includes one or more of methanol, ethanol, furfuryl alcohol, ethyl acetate, toluene and chloroform.

8. A carbon / carbon thermal field composite material, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the carbon / carbon thermal field composite material according to claim 8 in high-temperature thermal field materials for lithium batteries.

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