Preparation method of high-dispersion nano carbon black slurry
By employing ozone oxidation pretreatment and high-shear dispersion methods, the problem of difficult dispersion of nano-carbon black in the matrix was solved, achieving efficient, stable, and environmentally friendly nano-carbon black dispersion and improving the performance of composite materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-04-07
AI Technical Summary
Existing methods for dispersing nano-carbon black suffer from low efficiency, poor stability, environmental unfriendliness, high cost, limited applicability, and equipment limitations, making it difficult to uniformly disperse in the matrix and affecting the performance of composite materials.
An ozone oxidation pretreatment combined with high-shear dispersion method is adopted. Polar functional groups are introduced on the surface of nano-carbon black through an ozone contact reactor, followed by strong crushing and dispersion in a high-shear disperser. Combined with closed-loop ozone circulation decomposition technology, acid treatment process is avoided.
It significantly improves the dispersion efficiency and stability of nano carbon black, reduces energy consumption, reduces the use of chemicals, enhances conductivity, has wider applicability, and is suitable for large-scale production.
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Figure CN121801388A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of nanomaterials technology, and in particular to a method for preparing highly dispersed nano-carbon black slurry. Background Technology
[0002] Nano-carbon black is widely used in rubber, plastics, inks, coatings, battery electrodes, and conductive composite materials due to its excellent conductivity, high specific surface area, reinforcing properties, and UV shielding capabilities. However, nano-carbon black particles have a huge specific surface area and extremely high surface energy. Strong van der Waals forces and π-π stacking interactions exist between particles, making them highly susceptible to irreversible agglomeration, forming hard agglomerates that are difficult to break down. This agglomeration severely hinders the uniform dispersion of nano-carbon black in the matrix, preventing the full utilization of its unique nanoscale advantages and significantly degrading the performance of the final product, such as reducing the strength, conductivity, thermal conductivity, and colorability of the composite material.
[0003] Currently, commonly used industrial dispersion methods for nano-carbon black mainly include: 1. Mechanical dispersion methods, such as ball milling / grinding, high-speed stirring, and ultrasonic dispersion. 2. Chemical dispersion methods (surface modification methods), such as surfactant adsorption, acid oxidation treatment (e.g., concentrated H2SO4 / HNO3), and coupling agent modification. However, these dispersion methods have the following drawbacks: 1. Balancing effectiveness and efficiency: Mechanical dispersion methods are difficult to efficiently break down hard agglomerates; purely chemical methods rely on large amounts of auxiliaries and may produce residues or pollution. 2. Poor environmental friendliness: Acid oxidation methods cause severe pollution; the large-scale use of surfactants also brings environmental burden and post-processing problems. 3. High cost: High energy consumption (long-term ball milling, ultrasonication), and large chemical consumption (acids, surfactants). 4. Poor dispersion stability: Simple mechanical shearing easily leads to re-agglomeration; chemical modification methods are prone to failure in complex environments. 5. Limited applicability: Some high-performance applications (such as conductive materials) require as few impurities as possible, limiting the use of surfactants; complex post-processing also increases the difficulty of the process. 6. Equipment limitations: Existing high-shear dispersers suffer from reduced efficiency and severe heat generation in high-concentration, high-viscosity systems, and lack integrated pretreatment steps and precise temperature control design.
[0004] Therefore, there is an urgent need to develop a new method and supporting equipment for dispersing nano-carbon black that is more efficient, stable, environmentally friendly, cost-effective, simple in process, and scalable, so as to break through the bottleneck of carbon black nano-application. Summary of the Invention
[0005] One of the objectives of this invention is to provide a method for preparing highly dispersed nano-carbon black slurry. This method is simple and easy to implement, and can be used to mass-produce highly dispersed nano-carbon black slurry, thus solving the problems of difficult dispersion and poor stability of existing nano-carbon black slurries.
[0006] To achieve the above objectives, the present invention employs the following technical solution: a method for preparing highly dispersed nano-carbon black slurry, comprising the following steps: S1. Add the nano carbon black to be dispersed into the dispersion medium and stir to prepare a uniform carbon black slurry with a solid content of 5wt%-40wt%. S2. Feed the carbon black slurry into the ozone contact reactor, maintain the temperature at 5℃-50℃, introduce ozone-containing gas, and react for 5-60 minutes to obtain the carbon black slurry pretreated by ozone oxidation. S3. Using a shear disperser, at a rotor speed of 1000-15000 rpm, 10 4 - 10 6 The carbon black slurry after ozone oxidation pretreatment was subjected to strong crushing and dispersion at a shear rate of s⁻¹, and then subjected to single or multiple high-cycle shear dispersion treatments, followed by post-treatment to obtain highly dispersed nano carbon black slurry.
[0007] Further improvements to the preparation method of highly dispersed nano-carbon black slurry: Preferably, the particle size of the nano-carbon black to be dispersed in step S1 is 10nm-500nm, specifically one of pigment or conductive nano-carbon black.
[0008] Preferably, the dispersion medium in step S1 includes a solvent, and one or more of an active material, an additive, and a resin solution, wherein the solvent is one or more of an inorganic solvent (including water) and an organic solvent.
[0009] Preferably, the carbon black slurry is placed in an ozone contact reactor at a temperature maintained at 10-30°C, and ozone-containing gas is introduced, and the reaction is carried out for 15-30 minutes.
[0010] Preferably, in step S2, ozone gas is uniformly introduced from the bottom of the carbon black slurry through a gas distribution device, and the carbon black slurry is stirred during the introduction process. The gas distribution device is a sintered metal or ceramic plate, and the stirring is magnetic stirring or mechanical stirring.
[0011] Preferably, the excess ozone-containing exhaust gas from step S2 ozone oxidation is treated by a connected reflux condenser and an ozone decomposition device (UV or catalytic decomposition) before being discharged.
[0012] Preferably, the rotor speed in step S3 is 3000 - 8000 rpm.
[0013] Preferably, the high-shear disperser described in step S3 has a built-in high-efficiency circulating cooling system to control the temperature of the disperser cavity to 10-60℃, preferably 20-45℃.
[0014] Preferably, the shearing process is performed 3-5 times in step S3, or the total shearing time is set to 1-30 minutes.
[0015] Preferably, the post-processing in step S3 involves adjusting the concentration, adjusting the pH, or adding a stabilizer.
[0016] The advantages of this invention compared to the prior art are as follows: (1) This invention provides a dispersion method for nano-carbon black with the synergistic effect of "ozone oxidation pretreatment - high shear and high efficiency dispersion". This method ingeniously combines mild and efficient ozone oxidation chemical pretreatment with strong physical high shear dispersion, giving full play to the advantages and avoiding the disadvantages, and significantly improving dispersion efficiency and stability.
[0017] First, the nano-carbon black to be dispersed is added to a dispersion medium and stirred for initial wetting and pre-dispersion. Then, the carbon black slurry is fed into an ozone contact reactor, and ozone-containing gas is introduced. This process mainly introduces oxygen-containing polar functional groups (-COOH, -OH, etc.) onto the carbon black surface, increasing its hydrophilicity and surface charge density, improving the surface properties of the carbon black itself and the carbon black / graphite interface, thereby improving its dispersion effect in complex systems (NMP systems). Preferably, ozone gas is evenly distributed from the bottom of the slurry through a gas distribution device (such as a sintered metal / ceramic plate) and contacts the carbon black particles for surface oxidation modification. Stirring (such as magnetic stirring or mechanical stirring) ensures sufficient gas-liquid-solid contact. The exhaust gas (containing unreacted ozone) is treated and discharged through a connected reflux condenser / ozone decomposition device (UV or catalytic decomposition).
[0018] The pre-treated carbon black slurry after ozone oxidation is then fed into the inlet of a high-shear disperser, which is then started, driving the rotor to rotate at high speed. A strong shear zone is formed between the high-speed rotating rotor and the stationary stator (both having a multi-layered precision-fit structure, such as primary coarse crushing teeth + secondary medium-fine dispersing teeth + tertiary fine dispersing teeth). Under the action of strong centrifugal force, the slurry is rapidly drawn into the gap between the rotor and stator (the gap width is typically 0.1-2 mm). In this extremely confined space, the slurry is subjected to a combination of extremely high shear rates, intense turbulence, high-frequency impacts, and moderate cavitation effects. This process powerfully breaks down and disperses nano-carbon black agglomerates (especially hard agglomerates weakened by ozone activation), aiming to obtain a uniform dispersion approaching the primary particle size. During dispersion, the slurry temperature rises due to frictional shear. The high-shear disperser of this invention incorporates a high-efficiency circulating cooling system (such as a cooling jacket / channel surrounding the dispersion chamber, or connected to an external circulating cooling unit). A cooling medium (usually cooling water or heat transfer oil) continuously flows through the cooling system, promptly removing the heat generated by shearing and precisely controlling the temperature of the dispersion chamber within the range of 10℃ to 60℃ (optimal 20-45℃) to ensure the stability of heat-sensitive components. Depending on the slurry state and processing objectives, the material can be processed in the high-shear disperser in single or multiple cycles to optimize the dispersion effect. The high-shear disperser can be optionally equipped with online viscometers, pH meters, and other sensors to monitor the slurry state in real time or in stages.
[0019] Post-processing of the carbon black slurry after high shear dispersion can be performed, such as diluting it by adding a dispersion medium or concentrating it under vacuum / centrifugation to adjust the concentration; adding acid or alkali to fine-tune the pH; adding a very small amount of high-efficiency polymer dispersant or pH adjuster as a stabilizer to improve long-term stability (not essential); or obtaining well-dispersed carbon black powder through centrifugation, filtration, spray drying, etc.
[0020] (2) This invention combines ozone oxidation to soften the chemical bonds on the surface of carbon black with high-shear cavitation fragmentation, resulting in smaller dispersed carbon black particles, higher dispersion stability, and superior electrical conductivity. This dispersion method simultaneously completes chemical modification and mechanical dispersion, avoiding segmented energy consumption and significantly reducing energy consumption. The use of closed-loop ozone cycle decomposition technology to replace acid treatment is green and environmentally friendly. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0023] Carbon black slurry is a dispersion system composed of carbon black, dispersant, solvent (or water), etc., and is widely used in lithium-ion batteries, coatings, inks, conductive adhesives, and other fields. Its performance directly affects the quality of the end product; therefore, key indicators need to be evaluated through systematic testing methods. The following examples use the following testing methods to test the carbon black slurry: 1. Solid content Drying method: Take a certain mass of slurry according to GB / T 1725-2007, dry it in an oven at 105-120℃ to constant weight (the difference between two weighings ≤0.001g), and calculate the proportion of the remaining solid mass to the total mass.
[0024] Formula: Solid content (%) = (mass after drying / initial mass of sample) × 100.
[0025] 2. Particle size and particle size distribution
[0026] Referring to ISO 13320-1:2009, the dynamic light scattering method (DLS) was used to calculate the particle size (Z-average particle size) by means of the scattered light fluctuations caused by the Brownian motion of the particles.
[0027] 3. Viscosity
[0028] According to ASTM D2196-15, the viscosity of the slurry at 25°C was tested using a Brookfield viscometer.
[0029] 4. Dispersion
[0030] According to ASTM D1210-05 (2019), the dispersion state of carbon black particles is directly observed by transmission electron microscopy (TEM) or scanning electron microscopy (SEM), and the number and size of agglomerates are counted. Using a scraper fineness gauge (e.g., 0-100μm), the slurry is dropped into the groove, and after being scraped flat, the maximum particle size of the undispersed particles is observed (reflecting the uniformity of dispersion).
[0031] 5. pH value
[0032] According to ISO 4316:1997, dilute the slurry to a concentration of 5%-10% (to avoid particle interference with the electrode), measure directly with a calibrated pH meter (accuracy ±0.01), and record stable readings.
[0033] 6. Electrical conductivity
[0034] Referring to ASTM D4496-13, the slurry is coated onto an insulating substrate (such as PET). After drying, the film resistance is measured using a four-probe tester (such as RTS-9). The volume resistivity is calculated in combination with the thickness (ρ=R×S / L, where S is the area and L is the thickness); conductivity: the reciprocal of resistivity (σ=1 / ρ).
[0035] 7. Storage stability
[0036] Referring to GB / T 6753.3-1986, after sealing the slurry, allow it to stand at 25℃ (room temperature) or 40℃ (accelerated conditions) for 7-30 days, periodically observe for stratification and sedimentation, and test the viscosity change rate (Δη= (η 后 - η 初 ) / η 初 (×100%) and particle size distribution changes.
[0037] Example 1
[0038] This embodiment provides a method for preparing highly dispersed nano-carbon black slurry, such as... Figure 1 As shown, the specific steps are as follows: S1. Pre-dispersion of the mixed system: Weigh 300g of nano carbon black (conductive grade N330 carbon black, DBP absorption value of about 100ml / 100g, original particle size of 10~30nm) and add it to 4.7 kg of deionized water. Stir at 200 rpm for 15 minutes to obtain a carbon black slurry with a solid content of about 6wt%. S2. Ozone Oxidation Pretreatment: The carbon black slurry is fed into an ozone contact reactor (20L, with a cooling jacket and magnetic stirring). The circulating cooling water is turned on (jacket water temperature ~15℃), and the magnetic stirring is started (300 rpm). Ozone-containing gas (ozone-oxygen mixture with an ozone concentration of 40±5 mg / L) is introduced into the reactor through a bottom microporous titanium plate (pore size ~5μm) at a flow rate of 2 L / min. Excess tail gas is treated by a connected reflux condenser (controlled at 15℃) and an ozone decomposition device (UV decomposition device) before being discharged. The reaction is continued for 25 minutes. After the reaction, the carbon black slurry after ozone oxidation pretreatment is obtained. S3. High-shear dispersion treatment: The carbon black slurry pretreated by ozone oxidation is fed into the inlet of a high-shear disperser (FLUKO FSH multi-stage high-shear dispersion pump) via a feed pump. The high-shear disperser motor is started, and the rotor speed is set to 6500 rpm. The cooling system is turned on (jacket water flow rate 20 L / min, water temperature ~10℃). The internal temperature control upper limit is set to 45℃ via PLC. The slurry is circulated in the disperser for 15 minutes (about 4-5 cycles). Throughout the process, the chamber temperature is monitored in real time and maintained at 42±1℃. The high-shear dispersed slurry is then introduced into a concentration tank and vacuum concentrated to a solid content of 20wt% (target solid content) at 50℃ and -0.09MPa to obtain highly dispersed nano carbon black slurry 1.
[0039] Performance testing: (1) The carbon black slurry after ozone oxidation pretreatment in step S2 of Example 1 was tested. The test results showed that the slurry surface was obviously hydrophilic (no floating dry powder), and it was easy to settle but could be resuspended after standing. A small amount of sample was tested, and the oxygen-containing functional groups on its surface (by XPS or titration) increased significantly, and the negative value of the Zeta potential increased (absolute value of about -40 mV vs initial ~-20 mV).
[0040] (2) The well-dispersed carbon black powder 1 prepared in Example 1 was tested. The test results showed that the particle size distribution (DLS / NTA) D50 particle size was reduced to about 90 nm (the original slurry D50 before pretreatment was > 1000 nm).
[0041] (3) The dispersion stability test was performed on the well dispersed carbon black powder 1 prepared in Example 1: 20wt% concentrated slurry was left to stand at room temperature for 1 month. There were no obvious hard lumps, only a small amount of redispersible soft sediment at the bottom, and the suspended part remained translucent gray-black.
[0042] (4) Using a Brookfield viscometer, the viscosity of the well-dispersed carbon black powder 1 prepared in Example 1 was tested. The viscosity of the 20wt% slurry was stable at ~300 mPa·s.
[0043] (5) Conductivity application verification: The well-dispersed carbon black powder 1 obtained in Example 1 was coated on PET as a conductive paste. The dry film thickness was 10 μm, and the resistance was tested to be < 200 Ω / sq.
[0044] Example 2
[0045] This embodiment provides a method for preparing highly dispersed nano-carbon black slurry, such as... Figure 1 As shown, the specific steps are as follows: S1. Pre-dispersion of the mixed system: 50 parts by mass of active material (silicon-carbon composite material), 2 parts by mass of conductive agent (nano carbon black Super P), and 2 parts by mass of binder (CMC+SBR) are added to 46 parts by mass of solvent (N-methylpyrrolidone NMP). The mixture is mixed at a low speed of 500 rpm for 30 min to obtain a carbon black slurry with a solid content of about 5-40 wt%. S2. Ozone Oxidation Pretreatment: The carbon black slurry is fed into an ozone contact reactor (20L, with a cooling jacket and magnetic stirring, made of NMP-resistant material). The circulating cooling water is turned on (jacket water temperature ~15℃), and the magnetic stirring is started (300 rpm). Ozone-containing gas (ozone-oxygen mixture with an ozone concentration of 40 mg / L) is introduced into the reactor at a flow rate of 2L / min through a bottom microporous titanium plate (pore size ~5μm). Excess tail gas is treated by a connected reflux condenser (controlled at 15℃) and an ozone decomposition device (UV decomposition device) before being discharged. The reaction is continued for 30 minutes. After the reaction, the carbon black slurry is obtained after ozone oxidation pretreatment. S3. High-shear dispersion treatment: The ozone-treated slurry is pumped into an NMP-resistant high-shear disperser (Silverson L5MA) via a peristaltic pump, set to 8000 rpm. The high-efficiency cooling jacket (coolant - 10℃ ethylene glycol aqueous solution) is turned on. The process is repeated 3 times (approximately 5 minutes), with the temperature strictly controlled below 50℃.
[0046] Performance testing: (1) The well-dispersed carbon black powder 1 prepared in Example 2 was tested. The test results showed that the particle size distribution (DLS / NTA) D50 particle size was reduced to about 85 nm (the original slurry D50 before pretreatment was > 1000 nm).
[0047] (2) The dispersion stability test was performed on the well dispersed carbon black powder 2 prepared in Example 2: 20wt% concentrated slurry was left to stand at room temperature for 1 month. There were no obvious hard lumps, only a small amount of redispersible soft sediment at the bottom, and the suspended part remained translucent gray-black.
[0048] (3) Using a Brookfield viscometer, the viscosity of the well-dispersed carbon black powder 2 prepared in Example 2 was tested. The viscosity of the 20wt% slurry was stable at ~320 mPa·s.
[0049] (4) Conductivity application verification: The well-dispersed carbon black powder 3 obtained in Example 2 was coated on PET as a conductive paste. The dry film thickness was 10 μm, and the resistance was tested to be < 208 Ω / sq.
[0050] (5) Electrode performance: After coating and rolling, the electrode surface is smooth, dense and free of pinholes. Battery tests show that the cycle performance (capacity retention rate improved by about 5% after 100 cycles) and rate performance are significantly better than those of the slurry in Comparative Example 4, which only uses traditional planetary stirring and a small amount of surfactant.
[0051] Example 3
[0052] This embodiment provides a method for preparing highly dispersed nano-carbon black slurry, such as... Figure 1 As shown, the specific steps are as follows: S1. Pre-dispersion of the mixed system: Slowly add 100g of high-pigment channel black (PBk7 grade) to a mixture of 400g of acrylic resin liquid (50% solid content), 100g of ethylene glycol ethyl ether acetate (solvent) and 200g of deionized water, and stir evenly in the hopper of a vertical sand mill to obtain a carbon black slurry with a solid content of 5-40 wt%. S2. Ozone Oxidation Pretreatment: The carbon black slurry is fed into an ozone contact reactor (20L, with a cooling jacket and magnetic stirring). The circulating cooling water is turned on (jacket water temperature ~15℃), and the magnetic stirring is started (300 rpm). Ozone-containing gas (ozone-oxygen mixture with an ozone concentration of 50 mg / L) is introduced into the reactor at a flow rate of 2 L / min through a bottom microporous titanium plate (pore size ~5μm). Excess tail gas is treated by a connected reflux condenser (controlled at 15℃) and an ozone decomposition device (UV decomposition device) before being discharged. The reaction is continued for 20 minutes. After the reaction, the carbon black slurry after ozone oxidation pretreatment is obtained. S3. High-shear dispersion treatment: The carbon black slurry pretreated by ozone oxidation is fed into the feed port of the high-shear disperser (IKA T50 homogenizer with ultrafine dispersion module) via a feed pump. The motor of the high-shear disperser is started, and the rotor speed is set to 12,000 rpm high speed. The cooling system is turned on (jacket water flow rate 20 L / min, water temperature ~10℃). The internal temperature control upper limit is set to 45℃ via PLC, and the slurry is circulated in the disperser for 8 minutes. Throughout the process, the chamber temperature is monitored in real time and maintained at 42±1℃. The slurry after high-shear dispersion is introduced into a concentration tank and vacuum concentrated to a solid content of 20wt% (target solid content) at 50℃ and -0.09MPa to obtain highly dispersed nano carbon black slurry 3.
[0053] Performance testing: (1) The well-dispersed carbon black powder 3 prepared in Example 3 was tested. The test results showed that the particle size distribution (DLS / NTA) D50 particle size was reduced to about 93 nm (the original slurry D50 before pretreatment was > 1000 nm).
[0054] (2) The dispersion stability test was performed on the well dispersed carbon black powder 3 prepared in Example 3: 20wt% concentrated slurry was left to stand at room temperature for 1 month. There were no obvious hard lumps, only a small amount of redispersible soft sediment at the bottom, and the suspended part remained translucent gray-black.
[0055] (3) Using a Brookfield viscometer, the viscosity of the well-dispersed carbon black powder 3 prepared in Example 3 was tested. The viscosity of the 20wt% slurry was stable at ~285 mPa·s.
[0056] (4) Conductivity application verification: The well-dispersed carbon black powder 3 obtained in Example 3 was used as a conductive paste and coated on PET. The dry film thickness was 10 μm, and the sheet resistance was tested to be < 230 Ω / sq.
[0057] (5) Dispersion efficiency and energy consumption: The processing time (~8 min HSD + ozone 20 min) is significantly shorter than that of pure mechanical grinding (several hours), and the energy consumption is significantly reduced.
[0058] (6) Environmental friendliness: Compared with the pigment formulation containing a large amount of wetting and dispersing agent in Comparative Example 5, the dispersion method in Example 3 can reduce the amount of dispersing agent by 30-50%.
[0059] Comparative Example 1
[0060] This comparative example provides a common dispersion method for nano-carbon black. The specific steps are the same as in Example 1, except that the carbon black slurry in step S1 is not subjected to ozone treatment as in step S2, and directly enters step S3 for high-shear dispersion treatment. The final product is a common nano-carbon black slurry 1.
[0061] Performance testing: (1) The ordinary nano carbon black slurry 1 prepared in Comparative Example 1 was tested. The test results showed that the particle size distribution (DLS / NTA) D50 particle size was reduced to about 320 nm (the original slurry D50 before pretreatment was > 1000 nm).
[0062] (2) The dispersion stability test of the ordinary nano carbon black slurry 1 prepared in Comparative Example 1 was carried out: 20wt% concentrated slurry was left to stand at room temperature for 1 month, and there were obvious hard lumps of sediment, soft sediments that could not be further dispersed at the bottom, and the suspended part was transparent.
[0063] (3) Using a Brookfield viscometer, the viscosity of the ordinary nano carbon black slurry 1 prepared in Comparative Example 1 was tested. The viscosity of the 20wt% slurry was stable at ~180 mPa·s.
[0064] (4) Conductivity application verification: The ordinary nano carbon black slurry 1 prepared in Example 1 was coated on PET as a conductive slurry with a dry film thickness of 10 μm and a sheet resistance of < 300 Ω / sq.
[0065] Comparative Example 2
[0066] This comparative example provides a common dispersion method for nano-carbon black, with specific steps referring to Example 1, except that in step S2, the carbon black slurry undergoes acidification pretreatment: the carbon black slurry is transferred to a reactor (20L, with a cooling jacket and magnetic stirring). Circulating cooling water is turned on (jacket water temperature ~15℃), magnetic stirring is started (300 rpm), and 10% sulfuric acid or nitric acid is added at a ratio of slurry:sulfuric acid = 10:1. The mixture is stirred for 30 minutes to obtain the acidified carbon black slurry; then, the acidified carbon black slurry is subjected to high-shear dispersion treatment in step S3. Finally, ordinary nano-carbon black slurry 2 is obtained.
[0067] Performance testing: (1) The ordinary nano carbon black slurry 2 prepared in Comparative Example 1 was tested. The test results showed that the particle size distribution (DLS / NTA) D50 particle size was reduced to about 380 nm (the original slurry D50 before pretreatment was > 1000 nm).
[0068] (2) The dispersion stability test of the ordinary nano carbon black slurry 2 prepared in Comparative Example 1 was carried out: 20wt% concentrated slurry was left to stand at room temperature for 1 month, and there were obvious hard lumps of sediment, a large amount of non-dispersible soft sediment at the bottom, and the suspended part still showed a transparent color.
[0069] (3) Using a Brookfield viscometer, the viscosity of the ordinary nano carbon black slurry 2 prepared in Comparative Example 1 was tested. The viscosity of the 20wt% slurry was stable at ~150 mPa·s.
[0070] (4) Conductivity application verification: The ordinary nano carbon black slurry 2 prepared in Example 1 was coated on PET as a conductive slurry with a dry film thickness of 10 μm and a sheet resistance of < 350 Ω / sq.
[0071] Comparative Example 3
[0072] This comparative example provides a common dispersion method for nano-carbon black, with specific steps referring to Example 1, except that in step S2, the carbon black slurry is ball-milled: the pre-dispersed slurry is transferred to a ball mill (P-7 premium manufactured by Fritsch GmbH, Germany). The circulating cooling water is turned on (jacket water temperature ~15℃). Zirconia beads are added, with a zirconium oxide to slurry mass ratio of 10:1. The switch is started, and ball milling is performed for 90 minutes to obtain the ball-milled carbon black slurry; the ball-milled carbon black slurry is then subjected to high-shear dispersion treatment in step S3. Finally, ordinary nano-carbon black slurry 3 is obtained.
[0073] Performance testing: (1) The ordinary nano carbon black slurry 3 prepared in Comparative Example 3 was tested. The test results showed that the particle size distribution (DLS / NTA) D50 particle size was reduced to about 320 nm (the original slurry D50 before pretreatment was > 1000 nm).
[0074] (2) The dispersion stability test of the ordinary nano carbon black slurry 3 prepared in Comparative Example 3 was carried out: 20wt% concentrated slurry was left to stand at room temperature for 1 month, and there were obvious hard lumps of sediment, a large amount of non-dispersible soft sediment at the bottom, and the suspended part still showed a transparent color.
[0075] (3) Using a Brookfield viscometer, the viscosity of the ordinary nano carbon black slurry 3 prepared in Comparative Example 3 was tested. The viscosity of the 20wt% slurry was stable at ~160 mPa·s.
[0076] (4) Conductivity application verification: The ordinary nano carbon black slurry 3 prepared in Comparative Example 3 was coated on PET as a conductive slurry. The dry film thickness was 10 μm and the resistance was < 350 Ω / sq.
[0077] Comparative Example 4
[0078] This comparative example provides a common dispersion method for nano-carbon black. The specific steps are the same as in Example 2, except that the carbon black slurry in step S1 is not subjected to the ozone treatment in step S2, and a small amount of surfactant (0.5%-2wt%) is directly added. The high-speed shear dispersion treatment in step S3 is changed to planetary stirring dispersion, dispersed at 1000-2000 rpm for 30-100 min. Finally, a common nano-carbon black slurry 4 is obtained.
[0079] Performance testing: (1) The ordinary nano carbon black slurry 4 prepared in Comparative Example 4 was tested. The test results showed that the particle size distribution (DLS / NTA) D50 particle size was reduced to about 450 nm (the original slurry D50 before pretreatment was > 1000 nm).
[0080] (2) The dispersion stability test of the ordinary nano carbon black slurry 4 prepared in Comparative Example 4 was carried out: 20wt% concentrated slurry was left to stand at room temperature for 1 month, and there were obvious hard lumps of sediment, soft sediments that could not be further dispersed at the bottom, and the suspended part was transparent.
[0081] (3) Using a Brookfield viscometer, the viscosity of the ordinary nano carbon black slurry 4 prepared in Comparative Example 4 was tested. The viscosity of the 20wt% slurry was stable at ~160 mPa·s.
[0082] (4) Electrode performance: After coating and rolling, the electrode surface is smooth with a small number of pinholes. Battery testing shows poor cycle performance.
[0083] Comparative Example 5
[0084] This comparative example provides a common dispersion method for nano-carbon black. The specific steps are the same as in Example 3, except that the carbon black slurry in step S1 is not subjected to ozone treatment as in step S2. Instead, a large amount of wetting and dispersing agent (5%-20wt%) (BYK-903W) is directly added, and high-shear dispersion treatment is performed according to step S3. A common nano-carbon black slurry 5 is finally obtained.
[0085] Performance testing: (1) The ordinary nano carbon black slurry 5 prepared in Comparative Example 5 was tested. The test results showed that the particle size distribution (DLS / NTA) D50 particle size was reduced to about 450 nm (the original slurry D50 before pretreatment was > 1000 nm).
[0086] (2) The dispersion stability test of the ordinary nano carbon black slurry 5 prepared by Comparative Example 5 was carried out: 20wt% concentrated slurry was left to stand at room temperature for 1 month, and there were obvious hard lumps of sediment, soft sediments that could not be further dispersed at the bottom, and the suspended part was transparent.
[0087] (3) Using a Brookfield viscometer, the viscosity of the ordinary nano carbon black slurry 5 prepared in Comparative Example 4 was tested. The viscosity of the 20wt% slurry was stable at ~160 mPa·s.
[0088] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.
Claims
1. A method for preparing a highly dispersed nano-carbon black slurry, characterized in that, Includes the following steps: S1. Add the nano carbon black to be dispersed into the dispersion medium and stir to prepare a uniform carbon black slurry with a solid content of 5wt%-40wt%. S2. Feed the carbon black slurry into the ozone contact reactor, maintain the temperature at 5℃-50℃, introduce ozone-containing gas, and react for 5-60 minutes to obtain the carbon black slurry pretreated by ozone oxidation. S3. Using a shear disperser, at a rotor speed of 1000-15000 rpm, 10 4 - 10 6 The carbon black slurry after ozone oxidation pretreatment was subjected to strong crushing and dispersion at a shear rate of s⁻¹, and then subjected to single or multiple high-cycle shear dispersion treatments, followed by post-treatment to obtain highly dispersed nano carbon black slurry.
2. The method for preparing highly dispersed nano-carbon black slurry according to claim 1, characterized in that, The particle size of the nano-carbon black to be dispersed in step S1 is 10nm - 500nm.
3. The method for preparing highly dispersed nano-carbon black slurry according to claim 1, characterized in that, The dispersion medium described in step S1 includes a solvent, and one or more of an active material, an additive, and a resin solution.
4. The method for preparing highly dispersed nano-carbon black slurry according to claim 1, characterized in that, The carbon black slurry is placed in an ozone contact reactor at a temperature maintained at 10-30℃, and ozone-containing gas is introduced, and the reaction is carried out for 15-30 minutes.
5. The method for preparing highly dispersed nano-carbon black slurry according to claim 1 or 4, characterized in that, In step S2, ozone gas is uniformly introduced from the bottom of the carbon black slurry through a gas distribution device. During the introduction process, the carbon black slurry is stirred. The gas distribution device is a sintered metal or ceramic plate, and the stirring is magnetic stirring or mechanical stirring.
6. The method for preparing highly dispersed nano-carbon black slurry according to claim 1, characterized in that, In step S2, excess ozone-containing exhaust gas from ozone oxidation is treated by a connected reflux condenser and ozone decomposition device before being discharged.
7. The method for preparing highly dispersed nano-carbon black slurry according to claim 1, characterized in that, In step S3, the rotor speed is 3000 - 8000 rpm.
8. The method for preparing highly dispersed nano-carbon black slurry according to claim 1, characterized in that, The high-shear disperser described in step S3 has a built-in high-efficiency circulating cooling system to control the temperature of the disperser cavity to 10-60℃.
9. The method for preparing highly dispersed nano-carbon black slurry according to claim 1, characterized in that, In step S3, the shearing process is repeated 3-5 times, or the total shearing time is set to 1-30 minutes.
10. The method for preparing highly dispersed nano-carbon black slurry according to claim 1, characterized in that, The post-processing described in step S3 involves adjusting the concentration, adjusting the pH, or adding a stabilizer.