Carbon nanomaterial composite capable of achieving high dispersion stability and preparation method thereof

Abstract

The application relates to a carbon nanomaterial compound with high dispersion stability and a preparation method thereof, and belongs to the dispersion process field of carbon nanomaterials. Graphene, carbon nanotubes and conductive carbon black are first purified, then separately prepared into dispersion liquids, then mixed and ultrasonically dispersed, then heated and stirred until paste-shaped, vacuum dried, ground and dispersed again. The unique geometric structures of the graphene, the carbon nanotubes and the conductive carbon black are dispersed with each other, the carbon tubes connect the carbon tubes and the carbon tubes, the carbon tubes and the graphene, the wide gaps between the graphenes, the conductive carbon black is dispersed around and fills the remaining narrow gaps, and a stable three-dimensional network structure is formed, so that the high dispersion stability of the carbon nanomaterials is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of dispersion of carbon nanomaterials, and particularly relates to a carbon nanomaterial (graphene / carbon nanotube / conductive carbon black) composite capable of realizing high dispersion stability and a preparation method thereof. BACKGROUND

[0002] Carbon nanomaterials such as graphene have good mechanical, electrical and thermal properties, and are a good choice as a reinforcing body of metal matrix composites. However, carbon nanomaterials are prone to agglomeration during use, thereby limiting their application. Taking graphene as an example, the unique thin-layer two-dimensional structure of graphene makes it extremely easy to agglomerate in a natural state, and its unique mechanical properties and excellent thermal and electrical conductivity properties will rapidly decrease with the aggregation of the thin sheets.

[0003] In recent years, the methods for solving the dispersion of graphene mainly include the following:

[0004] 1) Physical dispersion method

[0005] The van der Waals force between the layers is broken by external force to achieve the effect of dispersion. Common methods include mechanical dispersion, ultrasonic and microwave irradiation.

[0006] 2) Chemical dispersion method

[0007] The graphene is usually dispersed into an aqueous solution or an organic solution containing a modifier, the surface of the graphene is embedded with a modified molecule, and the van der Waals force between the layers is overcome by electrostatic force or intermolecular force. The chemical dispersion method is divided into the following two types:

[0008] a) Covalent bond method

[0009] The edges of graphene oxide often have defects and can chemically react and combine with other functional groups, such as isocyanate modified graphene oxide, thereby improving the dispersibility.

[0010] b) Non-covalent bond method

[0011] The modifier is used to interact with graphene to modify the graphene without destroying its structure. Common methods include combining graphene with functional molecules through Π-Π bond, ionic bond, hydrogen bond or other non-covalent bonds.

[0012] Chinese invention patent (application number CN113200538A) discloses adding a dispersant, assisted by stirring, ball milling and other physical methods, to prepare a graphene aqueous dispersion, but it is difficult to remove the dispersant by centrifugation alone, and the ball milling method may damage the structure of graphene. Chinese invention patent (application number CN113184841A) discloses adding a small amount of organic solvent under relatively mild conditions to solve the dispersion problem of graphene, but the presence of organic solvent may affect the subsequent application of graphene dispersion. Chinese invention patent (application number CN213913491U) discloses a double-planetary stirring ultrasonic dispersion device for graphene slurry, which can effectively improve the stirring rate of the device and ensure uniform stirring, but the cost is high. Some carbon nanomaterial dispersions on the market exist in liquid form, and their solvents are mostly toxic liquids, which are not conducive to transportation and storage. In actual experiments and production, the dispersion process is required to be more simple, and the solvent is more common and safe and environmentally friendly. Therefore, there is an urgent need to develop a carbon nanomaterial dispersion method with good dispersibility and stability. SUMMARY

[0013] The technical purpose of the present application is mainly aimed at the current problems of poor dispersibility of carbon nanomaterials, difficult to guarantee dispersion stability, complex dispersion process, etc. A carbon nanomaterial dispersion method with good dispersibility and stability, without adding dispersant, and without damaging the structure, is developed. In the case of convenient transportation, the method can be used according to the instructions to realize a carbon nanomaterial composite powder with high dispersion stability. The powder can realize high dispersion stability in different solvents, and is suitable for various occasions that need to utilize the excellent mechanical, thermal and electrical properties of carbon nanomaterials, to realize high dispersion composite with other materials, and thus maximize the performance advantages of carbon nanomaterials.

[0014] A carbon nanomaterial composite with high dispersion stability and its preparation method are realized by the following technical solutions. The steps are as follows:

[0015] 1) impurity removal; 2) dispersion; 3) drying; 4) use.

[0016] Specifically as follows:

[0017] 1) impurity removal: carbon nanomaterials graphene, carbon nanotubes and conductive carbon black are respectively cleaned with deionized water by centrifugation to neutral, centrifuged, and dried in a vacuum oven, and the obtained carbon nanomaterial powders are annealed in an inert atmosphere;

[0018] 2) dispersion: carbon nanomaterial graphene, carbon nanotube, conductive carbon black are respectively placed in a certain solvent for first stage ultrasonic dispersion, and intermittent mechanical stirring is carried out, to obtain graphene, carbon nanotube, conductive carbon black dispersion liquid; then, graphene dispersion liquid, carbon nanotube dispersion liquid, conductive carbon black dispersion liquid are mixed according to the mass ratio of graphene / carbon nanotube / conductive carbon black (1-15):1:(0-5), and then second stage ultrasonic dispersion treatment is carried out, and intermittent mechanical stirring is carried out;

[0019] 3) drying: the obtained dispersion liquid is placed in a water bath at a certain temperature and heated with magnetic stirring until it is paste, and then it is placed in a vacuum oven for drying, the obtained compound is ground into powder and vacuum sealed for preservation;

[0020] 4) use: the compound is ultrasonically dispersed in a target solvent (deionized water, one or several of alcohol, ketone, ester, amine and other organic solvents, or containing solute) at a certain concentration to obtain a carbon nanomaterial system with high dispersion stability.

[0021] In step (1), the size of graphene is 6-100 μm, the number of layers is <10, the thickness is 1-3 nm, and the purity is >95%; the carbon nanotube is a single-walled, double-walled or multi-walled carbon nanotube without functional groups, the length is 0.5-10 μm, the diameter is 4-100 nm, and the purity is >95%; the particle size of conductive carbon black is 30-40 nm;

[0022] Further, in the impurity removal process of step 1), the centrifugal rate is 4000-8000 r / min -1 ; the oven drying temperature is 60-100℃; in the impurity removal process, the annealing atmosphere is N2 or Ar, the annealing temperature is 300-600℃, and the annealing treatment time is 2-4h.

[0023] Further, in the ultrasonic dispersion process of step (2), the solvent used is deionized water or ethanol, the concentration of carbon nanomaterial in the solvent is 1g / (2000-10000)ml, the ultrasonic power for ultrasonic dispersion treatment is 200-600W, and the solution temperature is controlled at 20-30℃; the first stage ultrasonic time is 5-15min, and the time interval of intermittent mechanical stirring is 2-5min; the second stage ultrasonic time is 35-100min, and the time interval of intermittent mechanical stirring is 5-10min.

[0024] In step 2), the size S of graphene and the diameter OD of carbon nanotube should be kept at S / OD=1±0.6, and when S≤50 μm, the mass ratio of graphene / carbon nanotube / conductive carbon black is (9-15):1:(0-3); when S>50 μm, the mass ratio of graphene / carbon nanotube / conductive carbon black is (1-9):1:(3-5).

[0025] Further step 3), during the drying process, the temperature t of the water bath is 60-100℃, the magnetic stirring speed v is 500-2500 r / min, and during the process, the temperature of the water bath is set according to the evaporation degree of the solution, and the magnetic stirring speed satisfies the following relationship: v=-50t+5000;

[0026] Step 3) During the drying process, the initial temperature of the vacuum oven is consistent with the final temperature of the water bath, and the oven temperature is reduced by 5-10℃ for every 1h of the drying process;

[0027] Step 4) During use, the target solvent can be selected according to the actual application, the concentration of the carbon nanomaterial composite in the target solvent is 1g / (1000-5000)ml, the ultrasonic power for the carbon nanomaterial composite is 200-600W, the ultrasonic time is 10-30min, and after the obtained dispersion liquid is placed for 30 days, the ultraviolet absorbance of the dispersion liquid is reduced by not more than 20% compared with that before placement.

[0028] The carbon nanomaterial composite provided by the application has the following advantages:

[0029] The application utilizes the advantages of graphene / carbon nanotube / conductive carbon black in different size dimensions, builds a stable low-dimensional multi-scale three-dimensional structure, and disperses the carbon nanomaterials from each other without adding any dispersant and under mild operating conditions, thereby ensuring the structural integrity of the carbon nanomaterials. The obtained carbon nanomaterial composite is a powder material, which is convenient for transportation and can be used in various occasions requiring the excellent performance of carbon nanomaterials. Under the premise of ensuring the dispersion stability, the advantages of carbon nanomaterials are fully utilized, thereby further expanding the application field of carbon nanomaterials. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 (a) is a macro photograph of the graphene / carbon nanotube / conductive carbon black dispersion liquid prepared in Example 4 and placed at room temperature for 30 days. Figure 1 (b) is a macro photograph of the graphene / carbon nanotube / conductive carbon black dispersion liquid prepared in Example 4 and placed at room temperature for 30 days and centrifuged for 30min.

[0031] Figure 2 (a) is a transmission electron microscope image and a macro photograph of the graphene dispersion liquid placed for 30 days in Example 4. Figure 2 (b) is a transmission electron microscope image and a macro photograph of the carbon nanotube dispersion liquid placed for 30 days in Example 4. Figure 2 (c) is a transmission electron microscope image and a macro photograph of the carbon black dispersion liquid placed for 30 days in Example 4. Figure 2(d) is the transmission electron microscopy image and macroscopic photograph of the graphene / carbon nanotube / conductive carbon black dispersion liquid in Example 4 after standing for 30 days.

[0032] Figure 3 is the ultraviolet spectrum of the graphene / carbon nanotube / conductive carbon black dispersion liquid in Example 4 after standing for 0 days and 30 days. DETAILED DESCRIPTION

[0033] The application is further illustrated below with examples, but the application is not limited to the following examples.

[0034] Example 1:

[0035] 1) Impurity removal: carbon nanomaterials (graphene, carbon nanotubes, conductive carbon black, wherein the graphene has a size of 6 μm, a layer number of <10, a thickness of 1-3 nm, and a purity of >95%; the carbon nanotubes are single-walled, double-walled or multi-walled carbon nanotubes without functional groups, have a length of 0.5 μm, a diameter of 4 nm, and a purity of >95%; the conductive carbon black has a particle size of 30-40 nm) are respectively washed to neutral by centrifugation with deionized water at a centrifugal rate of 4000 r / min -1 , and dried in a vacuum oven (temperature of 60°C). The obtained carbon nanomaterial powders are respectively placed in an N2inert atmosphere and subjected to annealing treatment at a temperature of 300°C for 4 h.

[0036] 2) Dispersion: the carbon nanomaterials are respectively placed in deionized water at a concentration of 1 g / 2000 ml, subjected to first-stage ultrasonic dispersion treatment at a power of 600 W and a solution temperature of 20°C, and intermittently subjected to mechanical stirring, with an ultrasonic time of 5 min and an interval of 2 min for intermittent mechanical stirring. Subsequently, the carbon nanomaterials are mixed according to a mass ratio of graphene / carbon nanotube / conductive carbon black of 15:1:1 to form a dispersion liquid, and subjected to second-stage ultrasonic dispersion treatment and intermittent mechanical stirring, with an ultrasonic time of 100 min and an interval of 5 min for intermittent mechanical stirring.

[0037] 3) Drying: the obtained dispersion liquid is heated in a water bath at a temperature of 60°C with a magnetic stirring at a speed of 2000 r / min until a paste is formed, and then dried in a vacuum oven, with an initial temperature consistent with the final temperature of the water bath, until the solution is dried. During the drying process, the temperature of the oven is reduced by 5°C for every 1 h of extension, and then the obtained compound is ground into a powder and stored in a vacuum-sealed manner.

[0038] 4) Use: the compound is mixed in deionized water at a concentration of 1 g / 1000 ml and subjected to ultrasonic dispersion (ultrasonic power of 600 W and ultrasonic time of 30 min) to obtain a dispersion liquid, which has an ultraviolet absorbance of 2.598 at 0 day. After standing for 30 days, the ultraviolet absorbance of the obtained dispersion liquid is 2.133, which is reduced by 17.9% compared with the ultraviolet absorbance of the dispersion liquid before standing.

[0039] Example 2:

[0040] 1) Purification: Carbon nanomaterials (graphene, carbon nanotube, conductive carbon black, wherein the graphene size is 30 pm, the layer number is <10, the thickness is 1-3 nm, and the purity is >95%; the carbon nanotube is a single-walled, double-walled or multi-walled carbon nanotube without functional groups, the length is 0.5 pm, the diameter is 40 nm, and the purity is >95%; the conductive carbon black particle size is 30-40 nm) are respectively cleaned to neutral by centrifugation with deionized water, and the centrifugal rate is 5000 r / min -1 , and dried in a vacuum oven (temperature is 70°C). The obtained carbon nanomaterial powder is placed in an N2inert atmosphere and subjected to an annealing treatment at a temperature of 400°C for 4h;

[0041] 2) Dispersion: The carbon nanomaterials are respectively placed in deionized water at a concentration of 1 g / 4000 ml, and subjected to a first-stage ultrasonic dispersion treatment at a power of 500 W and a solution temperature of 25°C, and intermittent mechanical stirring, the ultrasonic time is 8 min, and the time interval of intermittent mechanical stirring is 2 min. Subsequently, the carbon nanomaterials are mixed according to a mass ratio of graphene / carbon nanotube / conductive carbon black of 11:1:2 to form a dispersion liquid, and subjected to a second-stage ultrasonic dispersion treatment and intermittent mechanical stirring, the ultrasonic time is 80 min, and the time interval of intermittent mechanical stirring is 6 min;

[0042] 3) Drying: The obtained dispersion liquid is heated in a water bath at a temperature of 60°C with a magnetic stirring at a speed of 2000 r / min until a paste is formed, and then dried in a vacuum oven, the initial temperature is consistent with the final temperature of the water bath, and the temperature of the oven is reduced by 6°C every 1h until the solution is dried. The obtained compound is ground into powder and stored in a vacuum sealed container;

[0043] 4) Use: The compound is mixed in isopropyl alcohol at a concentration of 1 g / 2000 ml and subjected to ultrasonic dispersion (ultrasonic power is 500 W, ultrasonic time is 25 min) to obtain a dispersion liquid, and the ultraviolet absorbance of the dispersion liquid is 2.673 at 0 day. After the obtained dispersion liquid is placed for 30 days, the ultraviolet absorbance is 2.213, which is reduced by 17.2% compared with the ultraviolet absorbance of the dispersion liquid before placement.

[0044] Example 3:

[0045] 1) Purification: Carbon nanomaterials (graphene, carbon nanotube, conductive carbon black, wherein the graphene size is 50 pm, the layer number is <10, the thickness is 1-3 nm, and the purity is >95%; the carbon nanotube is a single-walled, double-walled or multi-walled carbon nanotube without functional groups, the length is 0.5 pm, the diameter is 50 nm, and the purity is >95%; the conductive carbon black particle size is 30-40 nm) are respectively cleaned to neutral by centrifugation with anhydrous ethanol, and the centrifugal rate is 6000 r / min-1 and dried in a vacuum oven (temperature 80°C), the obtained carbon nanomaterial powders were respectively placed in Ar inert atmosphere and annealed at 450°C for 3h;

[0046] 2) dispersion: carbon nanomaterials were respectively placed in deionized water with a concentration of 1g / 6000ml, and subjected to first-stage ultrasonic dispersion treatment at a power of 400W and a solution temperature of 25°C, with intermittent mechanical stirring, ultrasonic time of 10min, and intermittent mechanical stirring time interval of 2min, then, after mixing the dispersion liquid according to a mass ratio of graphene / carbon nanotube / conductive carbon black of 9:1:3, the second-stage ultrasonic dispersion treatment was carried out with intermittent mechanical stirring, ultrasonic time of 60min, and intermittent mechanical stirring time interval of 7min;

[0047] 3) drying: the obtained dispersion liquid was heated in a water bath at a temperature of 70°C with magnetic stirring at 1500r / min until it became a paste, then dried in a vacuum oven, with the initial temperature consistent with the final temperature of the water bath, until the solution was dried, and the oven temperature was reduced by 7°C for every 1h of drying, then the obtained compound was ground into powder and stored in a vacuum sealed container;

[0048] 4) use: the compound was mixed in a sodium dodecylbenzene sulfate aqueous solution (concentration of 4x10 -3 mol / L) at a concentration of 1g / 3000ml and subjected to ultrasonic dispersion (ultrasonic power of 400W, ultrasonic time of 20min) to obtain a dispersion liquid, the ultraviolet absorbance of which was 2.696 at 0 day. After the obtained dispersion liquid was left to stand for 30 days, the ultraviolet absorbance was 2.270, which was reduced by 15.8% compared with the ultraviolet absorbance of the dispersion liquid before standing.

[0049] Example 4:

[0050] 1) impurity removal: carbon nanomaterials (graphene, carbon nanotube, conductive carbon black, wherein, the graphene has a size of 80μm, a layer number of <10, a thickness of 1-3nm, and a purity of >95%; the carbon nanotube is a single-walled, double-walled or multi-walled carbon nanotube without functional groups, with a length of 0.5μm, a diameter of 60nm, and a purity of >95%; the conductive carbon black has a particle size of 30-40nm) were respectively cleaned to neutral by centrifugation with anhydrous ethanol, with a centrifugal rate of 7000r / min -1 and dried in a vacuum oven (temperature 90°C), the obtained carbon nanomaterial powders were respectively placed in Ar inert atmosphere and annealed at 500°C for 2h;

[0051] 2) dispersion: the carbon nanomaterials were respectively placed in deionized water at a concentration of 1 g / 8000 ml, and were subjected to first-stage ultrasonic dispersion treatment at a power of 300 W and a solution temperature of 25°C, with intermittent mechanical stirring, for 12 min, and the intermittent mechanical stirring interval was 2 min, then the carbon nanomaterials were mixed according to a mass ratio of graphene / carbon nanotube / conductive carbon black of 3:1:4, and were subjected to second-stage ultrasonic dispersion treatment, with intermittent mechanical stirring, for 50 min, and the intermittent mechanical stirring interval was 8 min;

[0052] 3) drying: the obtained dispersion was placed in a water bath at a temperature of 80°C, and was heated with magnetic stirring at a speed of 1000 r / min until it became a paste, then it was placed in a vacuum oven, and the initial temperature was the same as the final temperature of the water bath, until the solution was dried, and the oven temperature was reduced by 8°C for every 1 h of drying, then the obtained compound was ground into powder and was stored in a vacuum-sealed manner;

[0053] 4) use: the compound was mixed in anhydrous ethanol solvent at a concentration of 1 g / 4000 ml and was subjected to ultrasonic dispersion (ultrasonic power of 300 W, ultrasonic time of 15 min) to obtain a dispersion, and the ultraviolet absorbance of the dispersion was 2.967 at 0 days. After the obtained dispersion was left to stand for 30 days, the ultraviolet absorbance was 2.564, which was reduced by 13.6% compared with the ultraviolet absorbance of the dispersion before standing.

[0054] Example 5:

[0055] 1) impurity removal: the carbon nanomaterials (graphene, carbon nanotube, and conductive carbon black, wherein the graphene had a size of 100 μm, a layer number of <10 layers, a thickness of 1-3 nm, and a purity of >95%; the carbon nanotube was a single-walled, double-walled or multi-walled carbon nanotube without functional groups, had a length of 0.5 μm, a diameter of 100 nm, and a purity of >95%; the conductive carbon black had a particle size of 30-40 nm) were respectively cleaned to neutral by centrifugal washing with anhydrous ethanol at a centrifugal rate of 8000 r / min -1 , and were dried in a vacuum oven (at a temperature of 100°C), and the obtained carbon nanomaterial powders were respectively subjected to annealing treatment in an Ar inert atmosphere at a temperature of 600°C for 2 h;

[0056] 2) dispersion: the carbon nanomaterials were respectively placed in deionized water at a concentration of 1 g / 10000 ml, and were subjected to first-stage ultrasonic dispersion treatment at a power of 200 W and a solution temperature of 20°C, with intermittent mechanical stirring, for 15 min, and the intermittent mechanical stirring interval was 2 min, then the carbon nanomaterials were mixed according to a mass ratio of graphene / carbon nanotube / conductive carbon black of 2:1:3, and were subjected to second-stage ultrasonic dispersion treatment, with intermittent mechanical stirring, for 35 min, and the intermittent mechanical stirring interval was 10 min.

[0057] 3) Drying: The obtained dispersion was heated in a water bath at 90°C with magnetic stirring at 500 r / min until it became a paste, then it was dried in a vacuum oven with an initial temperature identical to the final temperature of the water bath until the solution was dried, and the temperature of the oven was reduced by 10°C for every 1 h of drying, then the obtained compound was ground into powder and stored in a vacuum-sealed container;

[0058] 4) Use: The compound was mixed in an aqueous solution of melamine (concentration of 0.2 g / 5000 ml) at a concentration of 1 g / 5000 ml and ultrasonically dispersed (ultrasonic power of 200 W, ultrasonic time of 10 min) to obtain a dispersion, and the ultraviolet absorbance of the dispersion was 3.136 at 0 day. After the obtained dispersion was left to stand for 30 days, the ultraviolet absorbance was 2.521, which was 19.6% lower than that of the dispersion before standing.

Claims

1. A method for preparing a carbon nanomaterial composite with high dispersion stability, characterized in that, The method comprises the following steps: 1) impurity removal: carbon nanomaterials graphene, carbon nanotube and conductive carbon black are respectively cleaned with deionized water by centrifugation until neutral, centrifuged and dried in a vacuum oven, and the obtained carbon nanomaterial powders are annealed in an inert atmosphere; 2) dispersion: the carbon nanomaterials graphene, carbon nanotube and conductive carbon black are respectively placed in a certain solvent for first-stage ultrasonic dispersion, and intermittent mechanical stirring is performed to obtain graphene, carbon nanotube and conductive carbon black dispersion liquid; then, the graphene dispersion liquid, carbon nanotube dispersion liquid and conductive carbon black dispersion liquid are mixed according to a mass ratio of graphene / carbon nanotube / conductive carbon black of (1-15):1:(0-5), and second-stage ultrasonic dispersion treatment is performed, and intermittent mechanical stirring is performed; 3) drying: the obtained dispersion liquid is heated in a water bath at a certain temperature, and magnetic stirring is performed until a paste is formed, and then the paste is dried in a vacuum oven, the obtained composite is ground into powder, and vacuum sealed storage is performed; 4) use: the composite is ultrasonically dispersed in a target solvent at a certain concentration to obtain a carbon nanomaterial system with high dispersion stability.

2. The method of claim 1, wherein, In step 1), the size of graphene is 6-100 μm, the number of layers is less than 10, the thickness is 1-3 nm, and the purity is greater than 95%; the carbon nanotube is a single-walled, double-walled or multi-walled carbon nanotube without functional groups, the length is 0.5-10 μm, the diameter is 4-100 nm, and the purity is greater than 95%; and the conductive carbon black has a particle size of 30-40 nm.

3. The method of claim 1, wherein, Step 1) In the process of removing impurities, the centrifugal rate is 4000-8000 r / min -1 , and the drying temperature is 60-100 ℃.

4. The method of claim 1, wherein, In step 1), the annealing atmosphere during the impurity removal process is N2 or Ar, the annealing temperature is 300-600 ℃, and the annealing treatment time is 2-4 h.

5. The method of claim 1, wherein, In step 2), the solvent used in the dispersion process is deionized water or ethanol, the concentration of the carbon nanomaterial in the solvent is 1 g / (2000-10000) ml, the ultrasonic power for ultrasonic dispersion treatment is 200-600 W, the solution temperature is controlled at 20-30 ℃, the first-stage ultrasonic time is 5-15 min, the time interval for intermittent mechanical stirring is 2-5 min, the second-stage ultrasonic time is 35-100 min, and the time interval for intermittent mechanical stirring is 5-10 min.

6. The method of claim 1, wherein, In step 3), the temperature t of the water bath is 60-100 ℃, the magnetic stirring speed v ranges from 2500 to 500 r / min, and during the process, the water bath temperature is set according to the evaporation degree of the solution, and the relationship between the magnetic stirring speed and the water bath temperature is v=-50t+5000.

7. The method of claim 1, wherein, In step 3), the initial temperature of the vacuum oven is consistent with the final temperature of the water bath, and the oven temperature is reduced by 5-10 ℃ for every 1 h of drying process.

8. The method of claim 1, wherein, In the step 4), the solvent is selected from deionized water, one or more of alcohol, ketone, ester and amine, or contains a solute; the concentration of the carbon nanomaterial composite in the solvent is 1 g / (1000-5000) ml, the ultrasonic power for the carbon nanomaterial composite is 200-600 W, and the ultrasonic time is 10-30 min; the ultraviolet absorbance of the obtained dispersion liquid after standing for 30 days is reduced by not more than 20% compared with that of the dispersion liquid before standing.

9. The carbon nanomaterial composite with high dispersion stability prepared by the method according to any one of claims 1-8.

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