A Highly Dispersible Carbon Nanotube Conductive Slurry and Its Preparation Method

Abstract

This invention discloses a highly dispersible carbon nanotube conductive slurry and its preparation method. The conductive slurry is composed of a first polar aprotic solvent, multi-walled carbon nanotubes, a conjugated electron acceptor type intercalation inducing agent, and a cold-state low-viscosity polymeric adhesive. The cold-state adhesive contains fluorinated polymers such as polyvinylidene fluoride (PVDF). During preparation, the solvent, carbon nanotubes, and inducing agent are first heated and held at a constant temperature to achieve charge transfer complexation and pre-loosening; then, the pressure is reduced to allow the solvent to undergo micro-boiling flash evaporation to expand the inter-tube gaps; next, under pressure holding conditions, the cold-state adhesive is injected using a pressure difference, and the local negative pressure generated by condensation and contraction introduces the polymer into the carbon nanotubes to complete electrostatic anchoring; finally, the pressure is restored to normal and homogenized for degassing. This invention achieves non-destructive deep dispersion of carbon nanotubes through the synergistic effect of chemical pre-loosening and hydrodynamic pumping, significantly reducing the apparent viscosity of the slurry and effectively preventing carbon nanotube framework breakage and secondary agglomeration.

Description

Technical Field

[0001] This invention relates to the field of carbon nanomaterial application technology, specifically to a highly dispersed carbon nanotube conductive slurry and its preparation method. Background Technology

[0002] Carbon nanotubes, due to their excellent electrical conductivity and large aspect ratio, are often dispersed in polar solvents to form conductive slurries, which are widely used in new energy batteries, conductive coatings, and other fields to construct electron transport networks within substrates. To obtain stable and uniform slurries, the industry typically requires mixing and dispersing carbon nanotube powder with polymer resins used as dispersants or binders in a solvent.

[0003] However, carbon nanotubes have an extremely large specific surface area, and there are strong van der Waals forces between them, often forming dense bundles or entangled agglomerates in the dry powder state. Current conductive paste preparation processes mostly rely on high-intensity mechanical shearing equipment to forcibly break down these agglomerates. This purely physical processing method can usually only peel off the carbon nanotubes on the periphery of the agglomerates, making it difficult to penetrate deep into the bundles to completely overcome van der Waals forces and achieve deep dispersion. Simultaneously, prolonged high mechanical shear stress easily causes the covalent bond backbone of the carbon nanotubes to break down, reducing the original aspect ratio and thus affecting the connectivity of the long-range conductive network in the final coating. Furthermore, existing physical blending processes allow polymer macromolecular chains to adhere only to the periphery of the carbon nanotubes through weak physical entanglement, making it difficult to form a strong interfacial encapsulation. This results in a large amount of unadsorbed polymer remaining free in the solvent phase, with molecular chains intertwining to form a physical cross-linked network, directly causing a higher apparent viscosity of the paste and increasing the fluid resistance of subsequent coating processes. Under long-term static conditions, these polymers that rely solely on physical adsorption are prone to desorption. The carbon nanotubes, having lost their steric protection, will re-approach each other and undergo secondary aggregation and sedimentation, making it difficult to meet the stability requirements for long-term storage of conductive pastes. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a highly dispersible carbon nanotube conductive slurry and its preparation method, which solves the problems that traditional mechanical dispersion and physical blending cannot completely overcome the van der Waals forces between carbon nanotube bundles, easily leading to carbon nanotube skeleton breakage, high apparent viscosity of the slurry, and secondary agglomeration under long-term standing.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a highly dispersible carbon nanotube conductive slurry, comprising the following raw materials in parts by weight: 67.84-95.50 parts of a first polar aprotic solvent, 2.0-8.0 parts of multi-walled carbon nanotubes, 0.002-0.16 parts of a conjugated electron acceptor type intercalation inducing agent, and 2.5-24.0 parts of a cold-state polymeric low-viscosity adhesive. The cold-state polymeric low-viscosity adhesive is prepared by completely dissolving the polymer in a second polar aprotic solvent; the polymer is polyvinylidene fluoride or a polyvinylidene fluoride-hexafluoropropylene copolymer. The conjugated electron acceptor type intercalation inducing agent is a compound rich in electron-deficient conjugated systems.

[0006] By employing the above technical solution, a chemical dispersion system based on charge transfer complexation and electrostatic anchoring was constructed, exhibiting two continuous microscopic stages: pre-loosening and electrostatic anchoring. When a conjugated electron acceptor type intercalation inducer is introduced into the multi-walled carbon nanotube dispersion system, the inducer molecular framework, due to the presence of numerous electron-withdrawing groups, possesses a strong electron affinity.

[0007] In a solvent environment, inducing molecules spontaneously diffuse into the interstices of carbon nanotube bundles, extracting delocalized π electrons from the surface of the carbon nanotubes. This process alters the hybrid electron cloud distribution of carbon atoms, resulting in a locally electron-deficient micro-positive charge state on the surface of multi-walled carbon nanotubes.

[0008] The surfaces of adjacent carbon nanotubes, carrying the same charge, generate electrostatic repulsion. This repulsion cancels out the original inter-tube van der Waals forces, causing the densely wrapped carbon nanotube bundle structure to loosen physically and generate micropores.

[0009] In this pre-loosening process, the actual reaction system evolves into: multi-walled carbon nanotubes react with conjugated electron acceptor type intercalation inducing agents to generate a multi-walled carbon nanotube surface structure with local positive charge and an inducing agent anion free radical system with local negative charge.

[0010] To stabilize this loose state, polyvinylidene fluoride (PVDF) or PVDF-hexafluoropropylene copolymer is introduced into the system. The polymer chains contain electronegative fluorine atoms. When the extended polymer chains enter the intercellular spaces of the carbon nanotubes, the electronegative fluorine atoms are electrostatically attracted by the locally positively charged surface of the carbon nanotubes. A portion of the fluorine atom's outer electron cloud shifts towards the electron-deficient carbon nanotube surface, resulting in electron cloud sharing and dipole-charge interactions at the interface between the polymer chain and the carbon backbone.

[0011] At this point, the chemical reaction occurring within the system manifests as electrostatic attraction and electron cloud sharing between the surface of multi-walled carbon nanotubes with locally positive charges and polymer chains with highly electronegative fluorine atoms in fluorinated polymers, generating a carbon nanotube-polymer dipole anchoring system.

[0012] Through the above, the long polymer chains overcome the spatial diffusion barriers in traditional physical mixing, forming a coating and anchoring on the carbon nanotube surface, thereby effectively reducing the concentration of free polymers in the slurry system, eliminating the high yield stress caused by the hydrodynamic level, and achieving a reduction in slurry viscosity.

[0013] The polymer layer anchored to the surface of carbon nanotubes provides steric hindrance, blocking the path for the exposed surface of carbon nanotubes to re-contact, thus improving the suspension stability of the slurry.

[0014] Preferably, the multi-walled carbon nanotubes have an outer diameter ranging from 5 nm to 50 nm, a length ranging from 1 μm to 20 μm, and a carbon mass fraction greater than or equal to 98.0%. The conjugated electron acceptor type intercalation inducing agent is 1,4-benzoquinone, 1,4-naphthoquinone, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, or 7,7,8,8-tetracyano-p-diquinone dimethylethane. The first polar aprotic solvent and the second polar aprotic solvent are each independently N-methylpyrrolidone, N,N-dimethylformamide, or N,N-dimethylacetamide.

[0015] By adopting the above technical solution, the limited size and purity parameters of multi-walled carbon nanotubes can better meet the requirements of connectivity and contact resistance of the conductive network after film formation.

[0016] Based on this, the listed conjugated electron acceptor intercalation inducers possess matching electron-withdrawing potential energies, providing charge transfer driving force for the entire system. Polar aprotic solvents act as the basic carriers, providing a dielectric constant environment that maintains the electron transfer complex state and the solvation and unfolding of polymer molecules.

[0017] Preferably, the mass fraction of the polymer in the cold-state low-viscosity polymeric adhesive is 4.0%-5.0%. When the polymer is polyvinylidene fluoride, its weight-average molecular weight ranges from 800,000 to 1,200,000; when the polymer is a polyvinylidene fluoride-hexafluoropropylene copolymer, its hexafluoropropylene structural unit mass fraction is 5.0%-15.0%, and its weight-average molecular weight ranges from 400,000 to 600,000.

[0018] By adopting the above technical solution, controlling the polymer solution to be in a low mass fraction range and matching the corresponding weight-average molecular weight is mainly to enable the polymer chains to maintain an unentangled coil conformation in polar aprotic solvents, thereby reducing the intrinsic viscosity of the solution and reducing the fluid resistance when the polymer enters the tube bundle pores.

[0019] Furthermore, the hexafluoropropylene structural units introduced into the copolymer disrupt the crystallinity regularity of the polymer chain, enhancing its flexibility and interfacial wetting ability in the solvent phase, which is highly beneficial for improving the integrity of electrostatic anchoring.

[0020] This invention provides a method for preparing a highly dispersed carbon nanotube conductive slurry, comprising the following steps: (1) The first polar aprotic solvent, multi-walled carbon nanotubes and conjugated electron acceptor type intercalation inducer are put into the main reactor with a vacuum system, heated and stirred at a constant temperature. (2) Before the end of the heat preservation in step (1), the temperature inside the main reactor is kept constant, and the pressure inside the main reactor is reduced so that the first polar aprotic solvent remaining in the system undergoes local micro-boiling flash evaporation. (3) Maintain the reduced pressure in the main reactor and keep the pressure, and draw the cold polymer low viscosity liquid into the liquid surface below the main reactor; (4) Restore normal pressure, perform high shear homogenization treatment, and then perform vacuum degassing to obtain highly dispersed carbon nanotube conductive slurry.

[0021] By adopting the above technical solution, and by using process steps that couple thermodynamic changes with fluid dynamic pressure difference, and in conjunction with a chemical pre-loosening mechanism, the deep transport of polymer into the interior of carbon nanotubes is achieved.

[0022] The specific physicochemical synergistic process is as follows: Initially, during the heating and heat preservation process, the inducing agent completes charge extraction, causing the tube bundle structure to loosen initially. Once the system enters a depressurization state, the solvent retained in the system undergoes micro-boiling flash evaporation due to reaching the boiling point under a specific pressure. Liquid phase vaporization produces volume expansion, generating outward hydrodynamic pressure inside the micropores of carbon nanotubes, physically opening up the dense tube bundle dominated by van der Waals forces, forming internal channels.

[0023] Once the channels are expanded, a negative pressure is maintained, and a cold, low-viscosity polymeric liquid is introduced into the hot system. Residual solvent vapor inside the tube bundle condenses upon cooling, causing a rapid volume contraction. This alternating heating and cooling process directly creates a hydrodynamic negative pressure pumping effect locally within the nanopores. Under the dual fluid traction of the macroscopic pressure difference in the reactor and the microscopic negative pressure in the channels, the polymer chains smoothly enter the expanded carbon nanotube bundle. Finally, after reaching temperature and pressure equilibrium inside the bundle, the polymer chains adhere to the locally positively charged carbon nanotube surface and complete electrostatic anchoring. This method fundamentally avoids the mechanical damage to the covalent bonds of the carbon framework caused by sand milling equipment, achieving lossless liquid-phase dispersion of carbon nanotubes.

[0024] Preferably, in step (1), the main reactor is stirred at a speed of 200-500 rpm, and the system inside the main reactor is heated to 80-100℃. The mixture is then kept at this constant temperature for 30-60 minutes under normal pressure. The specific implementation method of step (2) is as follows: 10-20 minutes before the end of the heat preservation in step (1), start the high vacuum unit to reduce the pressure of the main reactor and control the absolute pressure inside the main reactor at 0.5-1.5 kPa. Maintain this absolute pressure and slight boiling state for 10-20 minutes.

[0025] By employing the above technical solution, the temperature of 80-100℃ set in the process provides the activation energy required to overcome the interfacial energy, which not only increases the frequency of molecular Brownian motion but also effectively promotes charge transfer reactions. Controlling the absolute pressure within the range of 0.5-1.5 kPa corresponds precisely to the saturated vapor pressure of the polar aprotic solvent at the system temperature, keeping the fluid in a state of localized micro-boiling. This continuous bubble expansion force gently expands the tube bundle channels, effectively preventing unnecessary losses caused by fluid boiling and splashing or solvent removal under vacuum.

[0026] Preferably, in step (3), the cold polymer low-viscosity adhesive is prepared into a homogeneous adhesive in a separate mixing tank, and then cooled and kept at a constant temperature of 15-20℃ for later use. The specific implementation method of step (3) is as follows: maintain the absolute pressure in the main reactor at 0.5-1.5kPa and close the evacuation valve to maintain pressure, open the submersible feed valve at the bottom of the main reactor, and use the pressure difference to draw the cold polymer low-viscosity adhesive to below the liquid surface of the main reactor within 1-3 minutes.

[0027] By employing the above technical solution, the temperature of the adhesive solution is controlled at 15-20℃, thus creating a temperature difference of over 60℃ with the high-temperature environment inside the main reactor. This temperature difference induces the condensation and collapse of solvent vapor inside the tube bundle, thereby generating a localized negative pressure effect at the microscopic level. Simultaneously, rapid differential pressure feeding over 1-3 minutes ensures that the cold adhesive solution, before absorbing heat from the system and heating up, can penetrate into the nanochannels in a low-viscosity state, completing the deep transport of the polymer.

[0028] Preferably, in step (4), the pressure relief valve of the main reactor is opened to introduce dry nitrogen until the pressure is restored to normal; then the speed of the high shear dispersion emulsifier is set to 2000-4000 rpm, and high shear homogenization is performed at 20-30℃ for 30-60 minutes; finally, vacuum degassing is performed at an absolute pressure of 5-10 kPa for 10-20 minutes.

[0029] By employing the above technical solution, the action of restoring atmospheric pressure aims to eliminate the expansion state of the fluid within the pores, allowing the anchored carbon nanotube structure to stabilize. The subsequent high-shear homogenization treatment at 2000-4000 rpm is targeted at fluids that have already undergone pre-loosening and polymer injection, primarily used for macroscopic depolymerization to peel off loose soft aggregates.

[0030] To ensure the performance of the final product, the end-stage vacuum degassing eliminates microbubbles entangled in the fluid mixing process, improves the density of the liquid conductive slurry, and eliminates defects that may cause pinholes in the coating during subsequent coating applications.

[0031] This invention provides a highly dispersed carbon nanotube conductive slurry and its preparation method. It has the following beneficial effects: 1. This invention establishes a chemical dispersion mechanism based on charge transfer complexation and electrostatic anchoring by combining a conjugated electron acceptor type intercalation inducer with a fluoropolymer. The inducer extracts delocalized electrons from the surface of carbon nanotubes, giving them a localized positive charge. The electrostatic repulsion between the nanotubes weakens the van der Waals forces, achieving initial loosening. Subsequently, electronegative fluorine atoms on the polymer chain share electron clouds with the positively charged carbon nanotube surface, completing the anchoring process. This mechanism reduces free polymer molecules in the system, breaks down the physical cross-linking network that easily leads to high viscosity in the slurry, and reduces the apparent viscosity of the conductive slurry. At the same time, the polymer layer attached to the carbon nanotube surface provides steric hindrance, preventing secondary aggregation of carbon nanotubes under long-term static conditions.

[0032] 2. The preparation process of this invention employs reduced-pressure micro-boiling flash evaporation technology to expand the gaps between carbon nanotubes. It utilizes the vaporization and expansion force of the solvent retained within the dense carbon nanotube bundle under a specific vacuum level to physically expand the bundle from the inside. This inside-out fluid expansion method replaces traditional physical grinding methods such as high-energy sand milling, avoiding mechanical breakage and damage to the covalent bond framework of the carbon nanotubes caused by external mechanical forces. This preserves the original length and structural integrity of the carbon nanotubes during liquid-phase dispersion, which is beneficial for constructing a more interconnected long-range conductive network and reducing contact resistance in subsequent coating and film-forming applications.

[0033] 3. This invention utilizes the temperature difference between the hot system and the cold, low-viscosity adhesive within the reactor to achieve deep transport of polymer macromolecules into the interior of carbon nanotubes. When the lower-temperature adhesive is drawn into the slightly boiling reaction system under pressure, the solvent vapor within the microchannels of the carbon nanotubes condenses and shrinks, creating a localized negative pressure pumping effect within the microchannels. Under the dual fluid traction of the macroscopic pressure difference in the reactor and the microscopic negative pressure in the channels, the extended polymer chains overcome the original spatial diffusion resistance and are drawn into the expanded interior of the carbon nanotubes, completing the interfacial encapsulation and structural shaping of the carbon nanotubes by the polymer macromolecules. Attached Figure Description

[0034] Figure 1 This is a magnified view of the Raman spectrum of some intermediate samples of the present invention; Figure 2The following are the interface energy spectrum and thermogravimetric analysis test diagrams of the dry powder sample after washing according to the present invention, wherein: (a) is the high-resolution characteristic peak diagram of F1s of the X-ray photoelectron energy spectrum of the sample, and (b) is the thermogravimetric analysis curve of the same batch of samples. Figure 3 Rheological curves showing the apparent viscosity of the conductive pastes prepared in the embodiments and comparative examples of the present invention as a function of shear rate. Figure 4 This is a scatter plot of the multi-point distribution of the volume conductivity of the conductive dry film in the embodiments and comparative examples of the present invention. Figure 5 The graph shows the variation of the multiple light scattering stability index over time for some embodiments and comparative conductive pastes of the present invention. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This invention provides a highly dispersed carbon nanotube conductive slurry and its preparation method. The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products: Multi-walled carbon nanotubes with an outer diameter ranging from 5 nm to 50 nm, a length ranging from 1 μm to 20 μm, and a carbon mass fraction greater than or equal to 98.0%.

[0037] Polar aprotic solvents include N-methylpyrrolidone (CAS No. 872-50-4), N,N-dimethylformamide (CAS No. 68-12-2), and N,N-dimethylacetamide (CAS No. 127-19-5).

[0038] Conjugated electron acceptor type intercalation inducers include 1,4-benzoquinone (CAS No. 106-51-4), 1,4-naphthoquinone (CAS No. 130-15-4), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (CAS No. 84-58-2), and 7,7,8,8-tetracyano-p-diquinone dimethyl ether (CAS No. 1518-16-7).

[0039] Polyvinylidene fluoride, CAS number 24937-79-9, has a weight-average molecular weight range of 800,000-1,200,000.

[0040] Polyvinylidene fluoride-hexafluoropropylene copolymer, CAS number 9011-17-0, with a mass fraction of hexafluoropropylene structural units of 5.0%-15.0% and a weight-average molecular weight range of 400,000-600,000.

[0041] Preparation Example 1: This preparation example provides a method for preparing a cold-state low-viscosity polymeric adhesive, including the following steps: In a separate mixing tank, 4.5 kg of polyvinylidene fluoride was completely dissolved in 95.5 kg of N-methylpyrrolidone and continuously stirred to prepare a homogeneous adhesive solution with a polymer mass fraction of 4.5%. The homogeneous adhesive solution was then cooled by a chilled water jacket and kept at a constant temperature of 18°C ​​for later use.

[0042] Preparation Example 2: This preparation example provides a method for preparing a cold-state low-viscosity polymeric adhesive, including the following steps: In a separate mixing tank, 4.0 kg of polyvinylidene fluoride was completely dissolved in 96.0 kg of N,N-dimethylformamide, and the mixture was continuously stirred to prepare a homogeneous adhesive solution with a polymer mass fraction of 4.0%. The homogeneous adhesive solution was then cooled by a chilled water jacket and kept at a constant temperature of 15°C for later use.

[0043] Preparation Example 3: This preparation example provides a method for preparing a cold-state low-viscosity polymeric adhesive, including the following steps: In a separate mixing tank, 5.0 kg of polyvinylidene fluoride-hexafluoropropylene copolymer was completely dissolved in 95.0 kg of N-methylpyrrolidone and continuously stirred to prepare a homogeneous adhesive solution with a polymer mass fraction of 5.0%. The homogeneous adhesive solution was then cooled by a chilled water jacket and kept at a constant temperature of 20°C for later use.

[0044] Preparation Example 4: This preparation example provides a method for preparing a cold-state low-viscosity polymeric adhesive, including the following steps: In a separate mixing tank, 4.5 kg of polyvinylidene fluoride was completely dissolved in 95.5 kg of N,N-dimethylacetamide and continuously stirred to prepare a homogeneous adhesive solution with a polymer mass fraction of 4.5%. The homogeneous adhesive solution was then cooled by a chilled water jacket and kept at a constant temperature of 18°C ​​for later use.

[0045] Example 1: This embodiment provides a method for preparing a highly dispersed carbon nanotube conductive paste, comprising the following steps: 83.84 kg of N-methylpyrrolidone, 5.0 kg of multi-walled carbon nanotubes, and 0.05 kg of 1,4-benzoquinone were sequentially added to the main reactor equipped with a jacketed temperature control and vacuum system. Turn on the main reactor stirring, set the speed to 300 rpm, heat the system in the main reactor to 90°C, and keep it at a constant temperature of 90°C and atmospheric pressure for 45 minutes. Fifteen minutes before the end of the heat preservation, the temperature inside the main reactor is kept constant at 90°C. The high vacuum unit is started to reduce the pressure inside the main reactor and control the absolute pressure inside the main reactor at 1.0 kPa. This causes the N-methylpyrrolidone retained in the system to undergo local micro-boiling flash evaporation. This absolute pressure and micro-boiling state are maintained for 15 minutes. Then, the absolute pressure inside the main reactor was maintained at 1.0 kPa and the evacuation valve was closed to maintain the pressure. The submersible feed valve at the bottom of the main reactor was opened, and 11.11 kg of the cold polymer low viscosity liquid (temperature 18°C) prepared in Preparation Example 1 was drawn into the liquid surface of the main reactor within 2 minutes using the pressure difference. After the drawing was completed, the feed valve was closed. Open the pressure relief valve of the main reactor and introduce dry nitrogen until the pressure returns to normal. Start the high-shear dispersion emulsifier, set the speed to 3000 rpm, and perform high-shear homogenization at 25°C for 45 minutes. Then stop the high-shear homogenization, start stirring, and perform vacuum degassing at an absolute pressure of 8 kPa for 15 minutes. The highly dispersed carbon nanotube conductive slurry is obtained by discharging through a filter screen.

[0046] Example 2: This embodiment provides a method for preparing a highly dispersed carbon nanotube conductive paste, comprising the following steps: 95.498 kg of N,N-dimethylformamide, 2.0 kg of multi-walled carbon nanotubes, and 0.002 kg of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone were sequentially added to the main reactor equipped with a jacketed temperature control and vacuum system. Turn on the main reactor stirring, set the speed to 200 rpm, raise the temperature of the system in the main reactor to 80°C, and keep it at a constant temperature of 80°C and atmospheric pressure for 30 minutes. Ten minutes before the end of the heat preservation, the temperature inside the main reactor is kept constant at 80°C. The high vacuum unit is started to reduce the pressure inside the main reactor and control the absolute pressure inside the main reactor at 1.5 kPa. This causes the N,N-dimethylformamide remaining in the system to undergo local micro-boiling flash evaporation. This absolute pressure and micro-boiling state are maintained for 10 minutes. Then, maintain the absolute pressure in the main reactor at 1.5 kPa and close the evacuation valve to maintain pressure. Open the submersible feed valve at the bottom of the main reactor and use the pressure difference to draw 2.5 kg of the cold polymer low viscosity liquid (temperature 15°C) prepared in Preparation Example 2 into the liquid surface of the main reactor within 1 minute. After the drawing is completed, close the feed valve. Open the pressure relief valve of the main reactor and introduce dry nitrogen until the pressure returns to normal. Start the high-shear dispersion emulsifier, set the speed to 2000 rpm, and perform high-shear homogenization treatment at 20°C for 30 minutes. Then stop the high-shear homogenization treatment, start stirring, and perform vacuum degassing at an absolute pressure of 10 kPa for 10 minutes. The highly dispersed carbon nanotube conductive slurry is obtained by discharging through a filter screen.

[0047] Example 3: This embodiment provides a method for preparing a highly dispersed carbon nanotube conductive paste, comprising the following steps: 67.84 kg of N-methylpyrrolidone, 8.0 kg of multi-walled carbon nanotubes, and 0.16 kg of 1,4-naphthoquinone were sequentially added into the main reactor equipped with a jacketed temperature control and vacuum system. Turn on the main reactor stirring, set the speed to 500 rpm, heat the system in the main reactor to 100°C, and keep it at a constant temperature of 100°C and atmospheric pressure for 60 minutes. 20 minutes before the end of the heat preservation, the temperature inside the main reactor is kept constant at 100℃. The high vacuum unit is started to reduce the pressure inside the main reactor and control the absolute pressure inside the main reactor at 0.5kPa. This causes the N-methylpyrrolidone retained in the system to undergo local micro-boiling flash evaporation. This absolute pressure and micro-boiling state are maintained for 20 minutes. Then, the absolute pressure inside the main reactor was maintained at 0.5 kPa and the evacuation valve was closed to maintain the pressure. The submersible feed valve at the bottom of the main reactor was opened, and 24.0 kg of the cold polymer low viscosity liquid (temperature 20°C) prepared in Preparation Example 3 was drawn into the liquid surface of the main reactor within 3 minutes using the pressure difference. After the drawing was completed, the feed valve was closed. Open the pressure relief valve of the main reactor and introduce dry nitrogen until the pressure returns to normal. Start the high-shear dispersion emulsifier, set the speed to 4000 rpm, and perform high-shear homogenization treatment at 30°C for 60 minutes. Then stop the high-shear homogenization treatment, start stirring, and perform vacuum degassing at an absolute pressure of 5 kPa for 20 minutes. The highly dispersed carbon nanotube conductive slurry is obtained by discharging through a filter screen.

[0048] Example 4: This embodiment provides a method for preparing a highly dispersed carbon nanotube conductive paste, comprising the following steps: 85.27 kg of N,N-dimethylacetamide, 4.0 kg of multi-walled carbon nanotubes, and 0.06 kg of 7,7,8,8-tetracyano-p-diquinone dimethane were sequentially added to the main reactor equipped with a jacketed temperature control and vacuum system. Turn on the main reactor stirring and set the speed to 400 rpm. Heat the system in the main reactor to 85°C and keep it at a constant temperature of 85°C and atmospheric pressure for 40 minutes. Fifteen minutes before the end of the heat preservation, the temperature inside the main reactor is kept constant at 85°C. The high vacuum unit is started to reduce the pressure inside the main reactor and control the absolute pressure inside the main reactor at 0.8 kPa. This causes the N,N-dimethylacetamide retained in the system to undergo local micro-boiling flash evaporation. This absolute pressure and micro-boiling state are maintained for 15 minutes. Then, the absolute pressure inside the main reactor was maintained at 0.8 kPa and the evacuation valve was closed to maintain the pressure. The submersible feed valve at the bottom of the main reactor was opened, and 10.67 kg of the cold polymer low viscosity liquid (temperature 18°C) prepared in Preparation Example 4 was drawn into the liquid surface of the main reactor within 2 minutes using the pressure difference. After the drawing was completed, the feed valve was closed. Open the pressure relief valve of the main reactor and introduce dry nitrogen until the pressure returns to normal. Start the high-shear dispersion emulsifier, set the speed to 2500 rpm, and perform high-shear homogenization at 25°C for 40 minutes. Then stop the high-shear homogenization, start stirring, and perform vacuum degassing at an absolute pressure of 8 kPa for 15 minutes. The highly dispersed carbon nanotube conductive slurry is obtained by discharging through a filter screen.

[0049] Comparative Example 1: Compared with Example 1, the difference is that 1,4-benzoquinone is not added, and the heating, vacuum micro-flash evaporation and negative pressure temperature difference injection steps are not performed. Instead, all raw materials are directly mixed at room temperature and pressure, and then high-intensity mechanical shear dispersion treatment is performed using a traditional sand mill. All other aspects are the same.

[0050] Comparative Example 2: Compared to Example 1, the difference is that 1,4-benzoquinone is not added to the formulation (it is replaced by an equal mass of N-methylpyrrolidone), otherwise the same.

[0051] Comparative Example 3: Compared with Example 1, the difference is that the extreme vacuum micro-flash evaporation treatment of polar aprotic solvent is not performed in the steps, and the entire process is kept at atmospheric pressure and 90°C. Then, the polymer low viscosity adhesive of Example 1 is added directly at atmospheric pressure. All other steps are the same.

[0052] Comparative Example 4: Compared with Example 1, the difference is that after the main reactor is devastated and restored to normal pressure and cooled to room temperature (25°C), the polyvinylidene fluoride solution described in Preparation Example 1, which has been restored to room temperature (25°C) beforehand, is added by conventional dripping method. All other aspects are the same.

[0053] Test Example 1: This test case primarily verifies the charge-transfer complexation pre-loosening mechanism between the intercalation inducer and multi-walled carbon nanotubes. The specific experimental steps are as follows: 1. In the preparation process of Examples 1 to 4 and Comparative Example 2, 50 mL of intermediate suspension in a hot mixed state was extracted through the sampling valve as the test sample after the main reactor heat preservation stage ended and before the cold polymer low viscosity adhesive was injected.

[0054] 2. Transfer the obtained suspension samples to centrifuge tubes and centrifuge at 10,000 rpm for 15 minutes. Pour off the supernatant to remove the main solvent. Then add anhydrous ethanol to the bottom precipitate, sonicate to resuspend, and centrifuge again. Repeat this washing operation three times to thoroughly wash away the uncomplexed free small molecule inducers and residual solvent.

[0055] 3. The washed precipitate was placed in a vacuum drying oven and dried continuously at 60°C and 1 kPa absolute pressure for 12 hours to obtain a dark black solid powder sample. Additionally, the original multi-walled carbon nanotube powder from the raw material portion was used directly as a reference control sample.

[0056] 4. Raman spectroscopy was used to test the above-mentioned solid powder samples. The excitation wavelength was set to 532 nm, and the scanning range was controlled within 1000 cm⁻¹. -1 Up to 2000cm -1 Between these steps, the positions of the characteristic G-band peaks representing the in-plane vibrations of carbon nanotubes in the spectra of each sample were recorded, and their peak shifts relative to the original multi-walled carbon nanotubes were calculated.

[0057] Table 1. Raman spectrum G-band characteristic peak positions and shift data of intermediate samples in each embodiment and comparative example:

[0058] Based on the data in Table 1 and the appendix Figure 1 The G-band Raman shift of the original multi-walled carbon nanotube is located at 1581.34 cm⁻¹. -1 This is also a typical benchmark value for the sp2 hybridization network characteristics of carbon atoms when unaffected by external chemical environments. In routine dispersion studies in the laboratory, researchers often find that it is difficult to substantially change the electron cloud distribution of the tube wall simply by relying on the penetration of polar solvents. The data from Comparative Example 2 indeed confirms this observation; after prolonged heating and holding with only N-methylpyrrolidone, its G band peak position changed by only 0.07 cm⁻¹. -1 The tiny drift, which is almost negligible, indicates that the purely physical solvent environment failed to break the inherent interaction state between carbon nanotubes, and the van der Waals forces inside the bundle still maintain a tight aggregated structure.

[0059] When a conjugated electron acceptor is introduced into the system, the physicochemical properties of the interface undergo a clear directional change. In Example 1, the addition of 1,4-benzoquinone shifted the G band peak position by 7.38 cm⁻¹ towards higher wavenumbers.-1 The pronounced blue shift is a typical characteristic of charge-transfer complexation. Benzoquinone molecules are rich in electron-deficient conjugated systems. When these systems gradually infiltrate the external gaps of carbon nanotube bundles under heating and mechanical stirring, they spontaneously extract free π electrons from the carbon nanotube surface. The carbon nanotube surface, having lost some electrons, exhibits a localized electron-deficient state. Adjacent carbon nanotubes, carrying the same positive charge, experience electrostatic repulsion. This repulsion weakens the original van der Waals attraction at the mesoscale, causing the tightly wound bundle structure to loosen. A horizontal comparison within the table shows a stepwise difference in the induction ability of different electron acceptors. The 2,3-dichloro-5,6-dicyano-1,4-benzoquinone used in Example 2, due to the strong electron-withdrawing cyano and chlorine atoms on its molecular backbone, has a much higher potential energy for extracting π electrons than ordinary benzoquinone, resulting in a π electron extraction energy as high as 11.81 cm⁻¹ in the test sample. -1 Blue shift.

[0060] In contrast, the 1,4-naphthoquinone in Example 3 exhibited relatively weak complexing ability due to the increased steric hindrance and dispersed electron density at the acceptor site caused by its large naphthalene ring structure, producing only 3.62 cm⁻¹. -1 The offset. These data level differences confirm that small chemical molecules do indeed intervene in the dispersion process of carbon nanotubes at the microscopic level.

[0061] Test Example 2: This test case mainly verifies the targeted dipole-charge electrostatic anchoring mechanism of long polymer chains on the surface of carbon nanotubes, and the effect of negative pressure temperature difference physical adsorption process on anchoring efficiency. The specific experimental steps are as follows: 1. Take 100g of each of the highly dispersed carbon nanotube conductive slurries prepared in Example 1, Example 2, Comparative Example 2 and Comparative Example 4 as the reference samples to be tested, and take pure polyvinylidene fluoride powder as the reference object.

[0062] 2. Add each slurry sample to a wide-mouthed beaker containing 1000 mL of high-purity N-methylpyrrolidone. Stir continuously at 600 rpm for 2 hours at room temperature using a magnetic stirrer to fully dissolve and dilute the free polymer in a large amount of solvent.

[0063] 3. Transfer the diluted mixture to a high-speed centrifuge and centrifuge at 15,000 rpm for 30 minutes. Discard the supernatant containing free polymers. Add fresh N-methylpyrrolidone solvent to the black precipitate at the bottom, sonicate for 15 minutes, and centrifuge again. Repeat this washing and centrifugation process 6 times to remove polymers that are only attached by weak van der Waals forces or are free on the periphery of the tube bundle, while retaining polymer chains that are truly strongly anchored at the interface.

[0064] 4. After the final centrifugation, the precipitate was washed twice with anhydrous ethanol, placed in a vacuum drying oven, and dried for 24 hours at 80°C and 0.5 kPa absolute pressure. The precipitate was then ground to obtain a dry powder sample for spectroscopic and thermal testing.

[0065] 5. X-ray photoelectron spectroscopy was used to test the obtained dry powder samples and pure polyvinylidene fluoride powder. The C1s peak (284.8 eV) was used as the charge correction reference, and the F1s orbital binding energy range was scanned with high resolution.

[0066] 6. Each dry powder sample was tested using a thermogravimetric analyzer. Under the protection of continuous high-purity nitrogen gas (flow rate 50 mL / min), the sample was heated from room temperature to 800℃ at a heating rate of 10℃ / min. The weight loss percentage of the sample in the range of 400℃ to 550℃ (the main thermal decomposition range of polyvinylidene fluoride skeleton) was recorded to quantify the mass fraction of anchoring polymer remaining on the surface of carbon nanotubes.

[0067] Table 2. Energy dispersive spectroscopy and thermogravimetric analysis data of samples after deep washing in each example and comparative example:

[0068] Based on the data in Table 2 and the appendix Figure 2 Conventional physical blending struggles to establish a lasting interfacial relationship between carbon materials and polymers. In the reference pure polyvinylidene fluoride (PVDF), the F1s orbital binding energy of fluorine atoms remains stable at 688.06 eV, reflecting a normal charge distribution within the polymer chain. In Comparative Example 2, due to the lack of conjugated electron acceptors, the carbon nanotube surface remains electrically neutral, and the polymer chains are only attached to the agglomerates through physical entanglement or weak van der Waals forces. This interfacial fragility was exposed after multiple rounds of vigorous solvent washing. Thermogravimetric analysis showed that the residual solids after washing experienced only a 1.28% weight loss within the decomposition temperature range, and the energy dispersive spectroscopy peak position shifted only slightly by 0.07 eV, demonstrating that the vast majority of polymers are easily desorbed and lost, failing to truly anchor to the carbon nanotubes. Our long-term slurry stability studies in the laboratory have revealed that this lack of strong anchoring in the coating state is often the root cause of the reverse migration of binders during electrode drying, leading to increased internal resistance.

[0069] In contrast, the system incorporating chemical pre-loosening and negative pressure heat shrinkage convection processes exhibited a significantly different interfacial affinity. In Example 1, the inducing agent locally imparted a micro-positive charge to the carbon nanotube surface. At this point, the highly electronegative fluorine atoms on the polyvinylidene fluoride (PVDF) chain were strongly attracted by electrostatic forces, causing a portion of the electron cloud of the fluorine atoms to shift towards the electron-deficient carbon nanotube surface. This cross-interfacial electron cloud sharing directly led to a decrease in the electron density outside the fluorine atom nucleus, manifested in a significant shift of 1.37 eV in the F1s binding energy direction during energy dispersive spectroscopy. Combined with this microscopic dipole-charge attraction, a high thermogravimetric retention rate of 8.15% macroscopically confirmed the high retention of the polymer chain on the carbon nanotube surface. Even under multiple rounds of strong elution by polar solvents, the macromolecules remained firmly locked within the inter-tube gaps. Comparative Example 4 retained the inducing agent but removed the ultimate vacuum flash evaporation and cold injection conditions. Although the F1s peak position showed a moderate shift of 0.83 eV, indicating that electrostatic interaction still existed, the thermogravimetric residual rate was sharply reduced to 2.51%.

[0070] This indicates that without the forced expansion of capillary channels due to solvent micro-boiling and the negative pressure pumping effect generated by the temperature drop of the low-viscosity adhesive, large-volume polymer chains are unable to penetrate deep into the nanotube bundles due to steric hindrance, and can only achieve a small amount of anchoring on the outer surface. This physical operation, which integrates thermodynamic expansion with targeted fluid dynamics delivery, effectively overcomes the interfacial diffusion barrier caused by traditional mixing methods.

[0071] Test Example 3: This test case mainly focuses on the macroscopic quantitative evaluation of the rheological characteristics and apparent viscosity of conductive pastes under different preparation processes. The specific experimental steps are as follows: 1. Take 50 mL of each of the highly dispersed carbon nanotube conductive slurries prepared in Examples 1 to 4 and Comparative Examples 1 to 4 as test objects, and place them in a constant temperature bath at 25°C for 2 hours to eliminate the fluid shear history brought about by the sampling process.

[0072] 2. The test was conducted using a rotational rheometer equipped with a parallel plate measurement system with a diameter of 40 mm. The slurry sample after being kept at constant temperature was carefully transferred to the center of the lower test plate using a wide-mouth pipette. The upper test plate was slowly lowered until the test gap was 1.0 mm, and the excess slurry overflowing from the edge was scraped off.

[0073] 3. 10 seconds before the test begins -1 The sample was pre-sheared at a constant shear rate for 60 seconds, and then left to stand for 120 seconds to allow the internal structure to reach equilibrium.

[0074] 4. Set the test mode to steady-state shear scan, and set the shear rate from 0.1 s⁻¹ on a logarithmic coordinate system. -1 Gradually increase the scan time to 1000 seconds. -1Record the apparent viscosity data of the slurry fluid at different shear rates, focusing on extracting the viscosity at low shear rates (1s). -1 ) and high shear rate (100s) -1 The specific viscosity value under ( ).

[0075] Table 3. Apparent viscosity test data of conductive pastes in each embodiment and comparative example:

[0076] Based on the data in Table 3 and the appendix Figure 3 The macroscopic differences in fluid internal resistance essentially reflect changes in the distribution morphology of polymers at the microscopic interface. In actual engineering operations of electrode coating, the high yield stress caused by free polymers often leads to defects such as edge tailing or uneven thickness. In Comparative Example 4, a conventional mixing method using room temperature dropwise addition was employed. Due to the lack of hydrodynamic negative pressure pumping effect caused by temperature difference, most of the polyvinylidene fluoride long chains failed to penetrate the tube bundle gaps and instead remained free in the N-methylpyrrolidone main solvent. These extended macromolecular chains entangled with each other, constructing a vast physical cross-linked network in the solvent, directly resulting in its high yield stress at low shear rates (1 s⁻¹). -1 The apparent viscosity of the sample surged to 7894.5 mPa·s. Data from Comparative Examples 2 and 3 indicate that, in the absence of in-situ pore enlargement or electrostatic anchoring failure, the slurry system exhibited typical gel-like high-viscosity retardation characteristics. Although Comparative Example 1 employed a high-mechanical-shear grinding method, which to some extent broke the long-chain structure of the polymer, the brutal physical fragmentation still could not solve the problem of macromolecular free flow; its high shear viscosity (442.8 mPa·s) remained significantly high, indicating the presence of numerous microscopic flocculated structures binding the solvent within the fluid.

[0077] Ideally, the coating fluid should minimize the reference viscosity while maintaining the solids content. In Examples 1 to 4, due to the deep coupling between the pre-vacuum flash evaporation pore-expansion step and the instantaneous cold adhesive infusion step, the long polymer chains are forcibly drawn to the surface of the carbon nanotubes and electrostatically locked. The polymers that should have been free in the solvent are largely consumed and tightly adhered to the tube wall, resulting in a sharp decrease in the overall concentration of free polymers in the solvent phase. This purification of the liquid phase environment is macroscopically manifested as a precipitous drop in viscosity; Example 1 shows a 1-second decrease in viscosity. -1 The viscosity at this point is only 3587.4 mPa·s, less than half that of the comparative example. This extremely low fluid resistance not only endows the slurry with excellent static leveling properties, allowing it to maintain its level within 100 seconds... -1Under high-shear coating flow, it can quickly unwind and slide in the shear direction, reducing viscosity to 186.2 mPa·s. This optimized shear-thinning behavior allows the carbon nanotube framework to maintain good dispersion independence in the wet film state, preventing secondary agglomeration due to the elastic recoil of free polymers. From a hydrodynamic perspective, this completely eliminates the engineering paradox of mutual constraint between dispersant dosage and slurry processing performance in traditional processes.

[0078] Test Example 4: This test case aims to eliminate interference from electrode active materials and directly quantify the integrity and conductivity of the macroscopic long-range conductive network after the conductive paste is coated into a film. The specific experimental steps are as follows: 1. Take 30g of each of the highly dispersed carbon nanotube conductive slurry prepared in Examples 1 to 4 and Comparative Example 1 (sand milling method), and process them at 1500rpm for 5 minutes at 25°C using a planetary vacuum degassing machine to completely eliminate the micro air bubbles entrained during sampling and transfer.

[0079] 2. Prepare an insulating polyester (PET) film with a size of 20cm×30cm as the substrate. Lay it flat on the coating machine platform equipped with a vacuum adsorption system. Use a precision wire bar coater with a gap set of 100μm to evenly coat each slurry sample onto the surface of the substrate.

[0080] 3. Immediately transfer the coated wet film along with the substrate to an explosion-proof drying oven, set the temperature to 120℃, and bake for 120 minutes to fully evaporate the polar aprotic solvent in the system. Then, allow it to cool naturally at room temperature to obtain a dry film of pure carbon nanotube conductive network attached to the substrate.

[0081] 4. Using a micrometer combined with a high-precision laser profilometer, randomly select 10 non-overlapping measurement points in the center and edge areas of each dry film, and record the coating thickness at those points.

[0082] 5. A powder resistivity tester equipped with a linearly arranged four-probe test head is used to directly press the dry film surface, apply a constant current and read the surface resistance value of each measurement point. Finally, the volume conductivity of the point is calculated by combining the corresponding thickness data, and the average value and data fluctuation are recorded.

[0083] Table 4. Macroscopic conductivity test data of pure conductive coatings in each embodiment and comparative example:

[0084] Based on the data in Table 4 and the appendix Figure 4 In Comparative Example 1, the purely conductive dry film, under the objective condition of having a basically uniform thickness, has a macroscopic volumetric conductivity of only 15.25 S / cm, and Figure 4The scatter distribution in the sample indicates severe spatial fluctuation polarization.

[0085] This phenomenon has been frequently observed in the past development of slurry production. In pursuit of extreme macroscopic dispersion, traditional industries have over-relyed on the strong mechanical shearing force of high-energy sand mills. While this high-intensity collision can indeed tear apart the macroscopic aggregates of carbon nanotubes, it inevitably severs the covalent bonds of the carbon nanotube skeleton. The large number of shredded short tubes causes a precipitous drop in the aspect ratio of the material, and the long-range conductive network inside the coating breaks into isolated micro-regions. Electrons have to undergo more inter-tube jumps during transmission, and the contact resistance rises sharply. Even adding more conductive agents cannot compensate for the electrical losses caused by the physical severance.

[0086] The electrical conductivity of Examples 1 to 4 remained consistently high, ranging from 60 S / cm to 70 S / cm. This significant leap in purely electrical data directly demonstrates that the purely hydrodynamic thermal shrinkage dispersion scheme of this invention avoids the engineering challenge of mechanical damage. Charge transfer complexation pre-loosening, combined with solvent flash evaporation and micro-boiling under specific pressure, slowly and gently expands the originally dense tube bundle dominated by van der Waals forces from the inside. Throughout the process, the carbon nanotubes were not subjected to any abrasive damage from rigid media, preserving their initial micron-scale ultralong intrinsic structure.

[0087] After electrostatic anchoring and curing, the conductive network, once dried and formed into a film, consists of complete carbon nanotubes, some tens of micrometers or even longer, interwoven and overlapping to form high-density, long-connected high-speed electron channels. Electrons can conduct unimpeded over micrometer-scale distances along the continuous graphene tube walls, reducing tunneling impedance across the insulating polymer matrix. The lateral stability of the data from the various embodiments in the table also demonstrates that the in-situ pore-expansion combined with negative pressure targeted adsorption process achieves a microscopically uniform distribution that surpasses high-energy grinding while preserving the material's intrinsic physical properties.

[0088] Test Example 5: This test case mainly uses multiple light scattering technology to quantitatively track the macroscopic dispersion stability and anti-agglomeration ability of conductive paste under long-term static conditions. The specific experimental steps are as follows: 1. Take the highly dispersed carbon nanotube conductive slurry prepared in Examples 1 to 4, Comparative Example 2 and Comparative Example 3 respectively. After vacuum degassing, quickly use a clean pipette to draw 20 mL of slurry sample and slowly inject it into a standard cylindrical flat-bottomed glass measuring cell. Seal the tube opening to prevent solvent evaporation.

[0089] 2. Place the glass measuring cell containing the slurry sample vertically into the detection chamber of the multiple light scattering stability analyzer, and set the constant temperature control parameter of the instrument's internal environment to 25℃ to eliminate the interference of ambient temperature fluctuations on the Brownian motion of the fluid.

[0090] 3. Start the test program. The instrument emits a near-infrared light source with a wavelength of 880nm. The test probe scans the transmitted light and backscattered light intensity along the entire height direction of the sample cell from bottom to top. The scanning frequency is set to once every 2 hours, and continuous scanning and monitoring are performed for 7 days (168 hours).

[0091] 4. Export the original light intensity distribution spectrum at each time point, and use the built-in statistical algorithm of the instrument to perform integral calculation on the change in backscattered light intensity within the entire sample height range. Calculate and extract the stability index (TSI) of each sample at 24 hours, 72 hours and 168 hours to evaluate the severity of particle phase separation and secondary aggregation within the system.

[0092] Table 5. Multiple light scattering stability index (TSI) data of conductive pastes of each embodiment and comparative example at different standing times:

[0093] Based on the data in Table 5 and the appendix Figure 5 The dynamic changes in the multiple light scattering stability index (TSI) directly reflect the macroscopic evolution of particle migration and flocculation within the slurry system. A faster increase in the TSI value indicates more severe sedimentation or phase separation within the system. This engineering challenge has been encountered in previous pilot-scale and storage tests. Carbon nanotube slurries prepared by conventional dispersion methods often exhibit a significant clear liquid precipitate layer after three to five days of standing, forcing the production line to add a high-energy-consuming secondary reflux stirring process before coating. The data from Comparative Examples 2 and 3 accurately reflect the thermodynamic instability of this traditional suspension system, with TSI values ​​reaching 6.28 and 4.85 after 168 hours, respectively. When the formulation lacks pre-loosening of conjugated small molecules due to charge transfer, or when the process fails to open the micropores through ultimate vacuum micro-flash evaporation, the long chains of polyvinylidene fluoride (PVDF) remain only at the outer edge of the tube bundle aggregates. This shallow, weak physical entanglement is highly susceptible to desorption under the long-term influence of Brownian motion and gravitational field of solvent molecules, exposing the surface of free carbon nanotubes not coated by the polymer. Due to their extremely high surface energy, the exposed nanomaterials irreversibly re-engage and undergo secondary flocculation driven by van der Waals forces, leading to the collapse of the overall network structure and a non-linearly accelerating settling velocity over time.

[0094] Faced with this near-spontaneous aggregation trend at the microscopic level, simply increasing solvent viscosity is clearly insufficient to fundamentally suppress particle sedimentation. Achieving deep locking of polymers at the carbon nanotube interface is key to maintaining long-term homogeneity. Examples 1 to 4 provide clear data feedback, with TSI values ​​all suppressed below 0.7 after 7 days, and no substantial light intensity shift observed in the optical scanning profile of the entire slurry. This anti-agglomeration capability stems from the strong anchoring interface established by the negative pressure thermal shrinkage mechanism in the preceding process. Polymers in a solvated and expanded state are forcibly propelled into the pre-expanded nanotube gaps by an instantaneous pressure difference, and tightly wrapped around the carbon skeleton with induced positive charges during the dramatic volume contraction caused by localized temperature drops. Targeted anchoring significantly consumes free macromolecules, avoiding the risk of depletion flocculation, while simultaneously constructing a dense and non-desorbable steric hindrance layer around each individual carbon nanotube. Even during a week-long static test, the adjacent tube bundles could not break through the repulsion barrier of this rigid anchoring polymer, maintaining a uniform colloidal suspension state on a macroscopic level, which met the process requirements for slurry storage period in large-scale electrode coating.

[0095] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A highly dispersed carbon nanotube conductive paste, characterized in that, Made from the following ingredients in parts by weight: The first polar aprotic solvent is 67.84-95.50 parts; Multi-walled carbon nanotubes, 2.0-8.0 parts; 0.002-0.16 parts of a conjugated electron acceptor type intercalation inducer, wherein the conjugated electron acceptor type intercalation inducer is 1,4-benzoquinone, 1,4-naphthoquinone, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone or 7,7,8,8-tetracyano-p-diquinone dimethane; 2.5-24.0 parts of cold-state high-molecular-weight low-viscosity adhesive; The cold-state high-molecular-weight low-viscosity adhesive is made by completely dissolving a polymer in a second polar aprotic solvent. The polymer is polyvinylidene fluoride or polyvinylidene fluoride-hexafluoropropylene copolymer. The first polar aprotic solvent and the second polar aprotic solvent are each independently N-methylpyrrolidone, N,N-dimethylformamide or N,N-dimethylacetamide. The conjugated electron acceptor type intercalation inducer is a compound rich in electron-deficient conjugated systems.

2. The highly dispersed carbon nanotube conductive paste according to claim 1, characterized in that, The multi-walled carbon nanotubes have an outer diameter ranging from 5 nm to 50 nm, a length ranging from 1 μm to 20 μm, and a carbon mass fraction greater than or equal to 98.0%.

3. The highly dispersed carbon nanotube conductive paste according to claim 1, characterized in that, The mass fraction of the polymer in the cold-state low-viscosity polymeric adhesive is 4.0%-5.0%; When the polymer is polyvinylidene fluoride, its weight-average molecular weight ranges from 800,000 to 1,200,000. When the polymer is a polyvinylidene fluoride-hexafluoropropylene copolymer, the mass fraction of its hexafluoropropylene structural units is 5.0%-15.0%, and the weight-average molecular weight ranges from 400,000 to 600,000.

4. A method for preparing a highly dispersed carbon nanotube conductive paste, used to prepare the highly dispersed carbon nanotube conductive paste according to any one of claims 1-3, characterized in that, Includes the following steps: (1) The first polar aprotic solvent, multi-walled carbon nanotubes and conjugated electron acceptor type intercalation inducer are put into the main reactor with a vacuum system, heated and stirred at a constant temperature. (2) Before the end of the heat preservation in step (1), the temperature inside the main reactor is kept constant, and the pressure inside the main reactor is reduced so that the first polar aprotic solvent remaining in the system undergoes local micro-boiling flash evaporation. (3) Maintain the reduced pressure in the main reactor and keep the pressure, and draw the cold polymer low viscosity liquid into the liquid surface below the main reactor; (4) Restore normal pressure, perform high shear homogenization treatment, and then perform vacuum degassing to obtain the highly dispersed carbon nanotube conductive slurry.

5. The method for preparing a highly dispersed carbon nanotube conductive paste according to claim 4, characterized in that, In step (1), start the main reactor stirring, set the speed to 200-500 rpm, heat the system in the main reactor to 80-100℃, and keep it at a constant temperature for 30-60 minutes under normal pressure.

6. The method for preparing a highly dispersed carbon nanotube conductive paste according to claim 4, characterized in that, The specific implementation method of step (2) is as follows: 10-20 minutes before the end of the heat preservation in step (1), start the high vacuum unit to reduce the pressure of the main reactor and control the absolute pressure inside the main reactor at 0.5-1.5 kPa. Maintain this absolute pressure and slight boiling state for 10-20 minutes.

7. The method for preparing a highly dispersed carbon nanotube conductive paste according to claim 4, characterized in that, In step (3), the cold polymer low viscosity adhesive is prepared into a homogeneous adhesive in a separate mixing tank, and then cooled and kept at a constant temperature of 15-20℃ for later use.

8. The method for preparing a highly dispersed carbon nanotube conductive paste according to claim 4, characterized in that, The specific implementation method of step (3) is as follows: maintain the absolute pressure in the main reactor at 0.5-1.5 kPa and close the evacuation valve to maintain pressure, open the liquid feed valve at the bottom of the main reactor, and use the pressure difference to draw the cold polymer low viscosity adhesive liquid into the liquid surface of the main reactor within 1-3 minutes.

9. The method for preparing a highly dispersed carbon nanotube conductive paste according to claim 4, characterized in that, In step (4), the pressure relief valve of the main reactor is opened to introduce dry nitrogen gas until the pressure is restored to normal. Then, the speed of the high-shear dispersion emulsifier was set to 2000-4000 rpm, and high-shear homogenization was carried out at 20-30℃ for 30-60 minutes. Finally, vacuum degassing was performed for 10-20 minutes at an absolute pressure of 5-10 kPa.

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