Method for preparing single-walled carbon nanotube paste, single-walled carbon nanotube paste, and use thereof
By combining low-temperature plasma oxidation and mechanical shearing synergistic mechanism with fluorinated surfactants and pH-responsive polyelectrolytes, the problem of single-walled carbon nanotubes being difficult to disperse in solvents was solved, achieving efficient unbundling, low-defect and large-scale production of single-walled carbon nanotube slurries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI HUZHENG IND CO LTD
- Filing Date
- 2025-10-21
- Publication Date
- 2026-05-12
AI Technical Summary
Single-walled carbon nanotubes are difficult to disperse in solvents, forming bundles with diameters of hundreds of nanometers, resulting in low efficiency in building conductive networks. Traditional methods are prone to introducing defects or residual surfactants, making it difficult to achieve large-scale processing.
By employing a synergistic mechanism of low-temperature plasma oxidation and mechanical shearing, combined with fluorinated surfactants and pH-responsive polyelectrolytes, oxygen-containing functional groups are introduced onto the surface of carbon nanotubes through low-temperature plasma, weakening van der Waals forces. Efficient unbundling and stable dispersion are achieved through the synergistic effect of mechanical shearing and polyelectrolytes.
It achieves efficient unbundling and long-term stable dispersion of single-walled carbon nanotubes, reduces defects and residues, is suitable for ton-scale production, and improves conductivity and dispersion stability.
Abstract
Description
Technical Field
[0001] This application relates to the field of nanomaterials technology, and in particular to a method for preparing a single-walled carbon nanotube slurry, the single-walled carbon nanotube slurry, and its applications. Background Technology
[0002] Single-walled carbon nanotubes (SUVs) possess excellent electrical, mechanical, and thermal properties, making them ideal candidates for next-generation conductive additives. However, the strong van der Waals forces and π–π interactions between SUV molecules readily form bundles with diameters of hundreds of nanometers, making them difficult to disperse in solvents and severely limiting the efficiency of their conductive network construction.
[0003] Currently, high-energy ultrasonication, ball milling, or the addition of large amounts of surfactants are mainly used to physically debundle single-walled carbon nanotubes. However, high-energy mechanical action easily introduces irreversible defects into the lattice of single-walled carbon nanotubes, reducing Ig. G / I D This can impair conductivity. Excessive surfactant residue can remain in the final electrode, increasing interfacial resistance. Furthermore, traditional shear flow fields are difficult to implement for industrial-scale continuous processing.
[0004] Therefore, there is an urgent need to develop a single-walled carbon nanotube slurry that combines efficient unbundling, low defects, low residue, and scalability to overcome the aforementioned technical bottlenecks. Summary of the Invention
[0005] In order to obtain a single-walled carbon nanotube slurry that balances efficient unbundling, low defects, low residue, and scalability, this application provides a method for preparing single-walled carbon nanotube slurry, the single-walled carbon nanotube slurry, and its application. The preparation method is based on a low-temperature plasma oxidation-mechanical shearing synergistic mechanism, which achieves efficient unbundling, long-term stable dispersion, and batch consistency of single-walled carbon nanotubes without introducing metal impurities and significant structural defects.
[0006] In a first aspect, this application provides a method for preparing a single-walled carbon nanotube slurry, employing the following technical solution:
[0007] A method for preparing a single-walled carbon nanotube slurry includes the following steps:
[0008] S1, for tube bundle diameter ≤100nm, I G / I D Single-walled carbon nanotubes with a diameter of ≥50 were subjected to low-temperature plasma oxidation treatment and mechanical shearing. The unbundled single / small bundles of carbon nanotubes were dispersed in deionized water with a mass of ten times that of single-walled carbon nanotubes to obtain a primary dispersion with a unbundling index of ≥0.80.
[0009] S2. The primary dispersion, fluorinated surfactant, amphiphilic ionic liquid and deionized water are mixed in a mass ratio of (5.5–55):(0.1–2):(0.05–0.5):(42.5–94.35), homogenized under high pressure and then ultrasonically treated to obtain a secondary dispersion.
[0010] S3. Add a pH-responsive polyelectrolyte to the secondary dispersion to adjust the pH of the system to 6.5–8.0. After microfluidic homogenization, a single-walled carbon nanotube slurry with a single-tube content ≥70%, a viscosity of 500–5000 cP, and a D50 ≤3 μm is obtained. The mass percentage of the pH-responsive polyelectrolyte in the single-walled carbon nanotube slurry is 0.02%–0.05%.
[0011] Among them, single-bundle / small-bundle carbon nanotubes refer to single-walled carbon nanotubes with a diameter ≤100nm. The unbundling index refers to the proportion of single-bundle and small-bundle carbon nanotubes in the primary dispersion. That is, an unbundling index ≥0.80 indicates that at least 80% of the single-walled carbon nanotubes in the primary dispersion exist in the form of single bundles or small bundles.
[0012] Specifically, the unbundling index is obtained through the following measurement method:
[0013] The diameter distribution of the tube bundle was observed by transmission electron microscopy (TEM), and the ratio of single bundles to small bundles after unbundling was statistically analyzed.
[0014] By employing the above technical solutions, low-temperature plasma introduces oxygen-containing functional groups onto the surface of single-walled carbon nanotubes, generating local Coulomb repulsion and significantly weakening the van der Waals forces between the tube bundles, while avoiding lattice damage caused by high-temperature oxidation. Mechanical shearing and low-temperature plasma oxidation are carried out simultaneously, unbundling the tubes while oxidizing, with unbundling efficiency 2-4 times higher than that of traditional single shearing. Fluorinated surfactants and amphiphilic ionic liquids work synergistically to reduce the interfacial tension between single-walled carbon nanotubes and the solvent, inhibiting the re-agglomeration of single-walled carbon nanotubes. The pH-responsive polyelectrolyte automatically extends under the pH environment of the electrode slurry, generating steric hindrance. The entire process can be carried out continuously at room temperature and pressure, and is easily scaled up to ton-scale. Thus, a single-walled carbon nanotube slurry that combines efficient unbundling, low defects, low residue, and scalability can be prepared.
[0015] Optionally, in step S1, the single-walled carbon nanotubes are treated with a power of 20-100W for 30-300s in a low-temperature plasma atmosphere with an oxygen volume fraction of 5-15%, while being subjected to mechanical shearing at 5000-15000rpm.
[0016] Specifically, in step S1, single-walled carbon nanotubes are placed in a sealed low-temperature plasma reaction chamber. The reaction chamber is purged with an inert gas containing 5–15% oxygen by volume through an atmosphere control system. Then, a plasma generator is activated to generate low-temperature plasma. The active oxygen substances in the plasma are adsorbed onto the surface of the single-walled carbon nanotubes. Through oxidation reactions, oxygen-containing functional groups such as hydroxyl and carboxyl groups are introduced, generating local Coulomb repulsion forces. This weakens the van der Waals forces and π-π interactions between the tube bundles, creating a condition for unbundling.
[0017] Simultaneously with plasma oxidation, a high-speed shearing component is activated within the reaction chamber, creating a shear flow field. The shearing component applies mechanical shearing force to the single-walled carbon nanotube bundles whose oxidation-weakened forces have broken them down into smaller bundles or single-bundle structures.
[0018] Specifically, the high-speed shearing assembly is a high-speed rotor-stator shearing assembly, with the rotor made of polytetrafluoroethylene or high-purity ceramic, and the stator sealed to the inner wall of the reaction chamber.
[0019] Optionally, in step S2, the primary dispersion, fluorinated surfactant, amphiphilic ionic liquid, and deionized water are mixed and first homogenized under high pressure at 50–150 MPa 1–5 times, and then homogenized at 20–40 kHz and a power density of 50–200 W·L. -1 Under the condition of sonication for 2–10 min, a secondary dispersion is obtained.
[0020] Optionally, the sample may be treated 1–3 times using a microfluidic homogenizer at 80–150 MPa.
[0021] Optionally, the fluorinated surfactant is sodium perfluorooctyl sulfonate, lithium perfluorodecanoate, or a mixture thereof, and the HLB value of the fluorinated surfactant is 8–12.
[0022] Optionally, the amphiphilic ionic liquid is 1-butyl-3-methylimidazolium tetrafluoroborate, 1-dodecyl-3-methylimidazolium bromide, or a mixture thereof.
[0023] Optionally, the pH-responsive polyelectrolyte is a polyacrylic acid-polyethylene glycol block copolymer or a poly(2-vinylpyridine)-b-polyoxyethylene block copolymer, and the number-average molecular weight of the pH-responsive polyelectrolyte is 5–30 kg·mol⁻¹. -1 .
[0024] Secondly, this application provides a single-walled carbon nanotube slurry, which adopts the following technical solution:
[0025] A single-walled carbon nanotube slurry is prepared by any of the methods described above for preparing single-walled carbon nanotube slurries.
[0026] Optionally, the absolute value of the Zeta potential of a single bundle of single-walled carbon nanotubes is ≥40 mV, and the conductivity is ≥1000 S·m. -1 .
[0027] Thirdly, this application provides an application of a single-walled carbon nanotube slurry, employing the following technical solution:
[0028] The above-mentioned single-walled carbon nanotube slurry is used as a conductive agent for the positive or negative electrode of lithium-ion batteries, a flexible transparent conductive film, or a thermally conductive interface material.
[0029] In summary, this application includes at least one of the following beneficial technical effects:
[0030] 1. Low-temperature plasma introduces oxygen-containing functional groups on the surface of single-walled carbon nanotubes, generating local Coulomb repulsion, which significantly weakens the van der Waals forces between the tube bundles, while avoiding lattice damage caused by high-temperature oxidation.
[0031] 2. Mechanical shearing and low-temperature plasma oxidation are carried out simultaneously, and the unbundling is performed at the same time as oxidation, which improves the unbundling efficiency by 2-4 times compared with traditional single shearing;
[0032] 3. Fluorinated surfactants and amphiphilic ionic liquids work synergistically to reduce the interfacial tension between single-walled carbon nanotubes and solvents, thereby inhibiting the re-aggregation of single-walled carbon nanotubes.
[0033] 4. The pH-responsive polyelectrolyte automatically expands in the pH environment of the electrode slurry, generating steric hindrance. The entire process can be carried out continuously at room temperature and pressure, and it is easy to scale up to the ton scale. Detailed Implementation
[0034] Example
[0035] This application discloses a single-walled carbon nanotube slurry.
[0036] Example 1
[0037] A single-walled carbon nanotube slurry is prepared by the following steps:
[0038] S1, 2gI G / I D =65. Single-walled carbon nanotubes with a tube diameter of 80nm were added to a low-temperature plasma reaction chamber with an oxygen volume fraction of 10% and treated at a power of 50W for 120s. At the same time, a high-speed shearing component in the reaction chamber was started at a rate of 10000rpm to perform mechanical shearing. The unbundled single / small bundles of carbon nanotubes were dispersed in 20g of deionized water to obtain a primary dispersion.
[0039] S2. Add 0.3 g of HLB=12 sodium perfluorooctyl sulfonate, 0.1 g of 1-butyl-3-methylimidazolium tetrafluoroborate, and 77.6 g of deionized water to the primary dispersion, homogenize three times under high pressure at 100 MPa, and then homogenize at a frequency of 30 kHz and a power density of 100 W·L. -1 Under the condition of sonication for 5 minutes, a secondary dispersion was obtained;
[0040] S3. Add 0.02 g of a product with a number-average molecular weight of 10 kg·mol⁻¹ to the secondary dispersion. -1 The polyacrylic acid-polyethylene glycol block copolymer was subjected to a pH adjustment of 7.0 using 0.5 mol / L dilute ammonia and 0.1 mol / L dilute hydrochloric acid, and then homogenized twice using a microfluidic homogenizer at 120 MPa to obtain a single-walled carbon nanotube slurry.
[0041] The single-walled carbon nanotube slurry obtained in Example 1 had a single-bundle content of 78%, a viscosity of 2200 cP, a D50 of 1.8 μm, a zeta potential of -45 mV, and an electrical conductivity of 1400 S·m. -1 After standing at 25℃ for 30 days, the single-beam retention rate was 92%, and the viscosity changed by 3%.
[0042] Example 2
[0043] A single-walled carbon nanotube slurry is prepared by the following steps:
[0044] S1, 1.5gI G / I D =55. Single-walled carbon nanotubes with a tube diameter of 60nm were added to a low-temperature plasma reaction chamber with an oxygen volume fraction of 8% and treated at a power of 30W for 200s. At the same time, a high-speed shearing component in the reaction chamber was started at a rate of 8000rpm for mechanical shearing. The unbundled single / small bundles of carbon nanotubes were dispersed in 15g of deionized water to obtain a primary dispersion.
[0045] S2. Add 0.5 g of HLB=10 lithium perfluorodecanoate, 0.08 g of 1-dodecyl-3-methylimidazolium bromide, and 83.42 g of deionized water to the primary dispersion, homogenize twice under high pressure at 80 MPa, and then homogenize at a frequency of 25 kHz and a power density of 80 W·L. -1 Under the condition of sonication for 5 minutes, a secondary dispersion was obtained;
[0046] S3. Add 0.03 g of a product with a number-average molecular weight of 15 kg·mol⁻¹ to the secondary dispersion. -1 The poly(2-vinylpyridine)-b-polyoxyethylene block copolymer was subjected to a pH adjustment of 7.5 with 0.5 mol / L dilute ammonia and 0.1 mol / L dilute hydrochloric acid, and then homogenized twice with a microfluidic homogenizer at 100 MPa to obtain a single-walled carbon nanotube slurry.
[0047] Testing showed that the single-walled carbon nanotube slurry obtained in Example 2 had a single-bundle content of 72%, a viscosity of 1800 cP, a D50 of 2.2 μm, a zeta potential of -42 mV, and an electrical conductivity of 1250 S·m. -1 After standing at 25℃ for 30 days, the single-beam retention rate was 89%, and the viscosity changed by 5%.
[0048] Example 3
[0049] A single-walled carbon nanotube slurry is prepared by the following steps:
[0050] S1, 4gI G / I D =70, single-walled carbon nanotubes with a bundle diameter of 90nm were added to a low-temperature plasma reaction chamber with an oxygen volume fraction of 12% and treated at 80W power for 60s. At the same time, a high-speed shearing component in the reaction chamber was started at a rate of 12000rpm for mechanical shearing. The unbundled single / small bundles of carbon nanotubes were dispersed in 40g of deionized water to obtain a primary dispersion.
[0051] S2. Add 1.5 g of a 1:1 mixture of sodium perfluorooctyl sulfonate and lithium perfluorodecanoate (HLB=9), 0.4 g of a 1:1 mixture of 1-butyl-3-methylimidazolium tetrafluoroborate and 1-dodecyl-3-methylimidazolium bromide, and 54.1 g of deionized water to the primary dispersion. Homogenize four times at 140 MPa, then at a frequency of 35 kHz and a power density of 150 W·L. -1 Under the condition of sonication for 4 minutes, a secondary dispersion was obtained;
[0052] S3. Add 0.05 g of a product with a number-average molecular weight of 25 kg·mol⁻¹ to the secondary dispersion. -1 The polyacrylic acid-polyethylene glycol block copolymer was subjected to a pH adjustment of 6.8 using 0.5 mol / L dilute ammonia and 0.1 mol / L dilute hydrochloric acid, and then homogenized three times using a microfluidic homogenizer at 140 MPa to obtain a single-walled carbon nanotube slurry.
[0053] Testing showed that the single-walled carbon nanotube slurry obtained in Example 2 had a single-bundle content of 85%, a viscosity of 3500 cP, a D50 of 1.5 μm, a zeta potential of -48 mV, and an electrical conductivity of 1600 S·m. -1 After standing at 25℃ for 30 days, the single-beam retention rate was 95%, and the viscosity changed by 2%.
[0054] Comparative Example
[0055] Comparative Example 1
[0056] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, the low-temperature plasma and mechanical shearing in step S1 are omitted.
[0057] Testing showed that the single-bundle content of the single-walled carbon nanotube slurry obtained in Comparative Example 1 was 35%, I G / I D The temperature dropped to 40, and sediment appeared after standing for 7 days.
[0058] Comparative Example 2
[0059] The difference between Comparative Example 2 and Example 1 is that in step S1, air oxidation at 400 °C for 30 min is used instead of low-temperature plasma treatment.
[0060] Tests showed that Comparative Example 2 increased the oxygen content of single-walled carbon nanotubes to 15%. G / I D When the conductivity was reduced to 25, the conductivity of the single-walled carbon nanotube slurry obtained in Comparative Example 2 decreased by 60%.
[0061] As can be seen from Example 1 and Comparative Examples 1-2, the low-temperature plasma oxidation-mechanical shearing synergistic mechanism provided in this application can achieve efficient unbundling and long-term stable dispersion while maintaining the structural integrity of single-walled carbon nanotubes, and has significant advantages in industrial applications.
[0062] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A method for preparing a single-walled carbon nanotube slurry, characterized in that, Includes the following steps: S1, tube bundle diameter ≤100nm, I G / I D Single-walled carbon nanotubes with a diameter of ≥50 were treated with a power of 20-100W for 30-300s in a low-temperature plasma atmosphere with an oxygen volume fraction of 5-15% while being mechanically sheared at 5000-15000rpm. The unbundled single / small bundles of carbon nanotubes were dispersed in deionized water to obtain a primary dispersion. S2. Mix the primary dispersion, fluorinated surfactant, amphiphilic ionic liquid, and deionized water at a mass ratio of (5.5–55):(0.1–2):(0.05–0.5):(42.5–94.35), first homogenize under high pressure at 50–150 MPa 1–5 times, and then homogenize at 20–40 kHz and a power density of 50–200 W·L. -1 Under the condition of sonication for 2–10 min, a secondary dispersion was obtained; S3. Add pH-responsive polyelectrolyte to the secondary dispersion, adjust the pH of the system to 6.5–8.0, and treat it 1–3 times with a microfluidic homogenizer at 80–150 MPa to obtain a single-walled carbon nanotube slurry with a single bundle content ≥70%, a viscosity of 500–5000 cP, and a D50 ≤3 μm. The fluorinated surfactant is sodium perfluorooctyl sulfonate, lithium perfluorodecanoate, or a mixture thereof, and the HLB value of the fluorinated surfactant is 8–12. The amphiphilic ionic liquid is 1-butyl-3-methylimidazolium tetrafluoroborate, 1-dodecyl-3-methylimidazolium bromide, or a mixture thereof; The pH-responsive polyelectrolyte is a polyacrylic acid-polyethylene glycol block copolymer or a poly(2-vinylpyridine)-b-polyoxyethylene block copolymer, and the number-average molecular weight of the pH-responsive polyelectrolyte is 5–30 kg·mol⁻¹. -1 The pH-responsive polyelectrolyte is present in the slurry at a mass percentage of 0.02%–0.05%.
2. A single-walled carbon nanotube slurry, characterized in that: It is prepared by the method for preparing single-walled carbon nanotube slurry according to claim 1.
3. The single-walled carbon nanotube slurry according to claim 2, characterized in that: The absolute value of the Zeta potential of a single bundle of single-walled carbon nanotubes is ≥40 mV, and the conductivity is ≥1000 S·m. -1 .
4. The application of the single-walled carbon nanotube slurry according to any one of claims 2-3 in the conductive agent of the positive or negative electrode of lithium-ion batteries, flexible transparent conductive film or thermally conductive interface material.