Preparation method of multi-walled carbon nanotube conductive agent for lithium ion battery
High-purity multi-walled carbon nanotube conductive agents were prepared through acidification purification, calcination, surface functionalization, and dispersion treatment. This solved the problems of agglomeration, impurities, and interfacial compatibility, and enabled the construction of efficient conductive networks and improved battery performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGXI ZHONGKE JINGHE NEW ENERGY TECH CO LTD
- Filing Date
- 2026-05-07
- Publication Date
- 2026-06-19
AI Technical Summary
Existing multi-walled carbon nanotube conductive agents in lithium-ion batteries suffer from problems such as agglomeration, high impurity content, poor interfacial compatibility, and insufficient stability of conductive networks, resulting in poor dispersibility, complex processes, and difficulties in large-scale production.
A high-purity, well-dispersible multi-walled carbon nanotube conductive agent was prepared by using acidification purification, calcination treatment, surface functionalization, dispersion treatment and composite construction. The carboxylated multi-walled carbon nanotubes react with the catalyst to form stable amide bonds, and then combined with ultrasonic and shear dispersion.
It significantly improves conductivity, dispersibility, and interfacial bonding strength, constructs a continuous and dense three-dimensional conductive network, enhances the rate performance, energy density, and cycle stability of the battery, and reduces the amount of conductive agent required.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery materials technology, and in particular to a method for preparing a multi-walled carbon nanotube conductive agent for lithium-ion batteries. Background Technology
[0002] Lithium-ion batteries are widely used in power batteries and energy storage systems due to their high energy density, long cycle life, and good safety performance. The electron transport capability in the electrode system is one of the key factors determining the battery's rate performance and cycle stability; therefore, conductive agents are usually added to construct the electron transport network.
[0003] Traditional conductive agents are mainly carbon black materials. Their conductivity mechanism relies on the point contact between particles to form a conductive path. However, due to their low specific surface area and zero-dimensional particle structure, they often require a high addition amount (usually 2-5 wt%) to form an effective conductive network, thereby reducing the content of electrode active materials and affecting the battery energy density.
[0004] In recent years, multi-walled carbon nanotubes (MWCNTs) have been considered an ideal class of highly efficient conductive agents due to their high aspect ratio, one-dimensional conductive structure, and excellent electronic conductivity. Studies have shown that carbon nanotubes can form a continuous three-dimensional conductive network at low addition levels, thereby significantly reducing electrode internal resistance and improving rate performance.
[0005] However, in practical applications, multi-walled carbon nanotube conductive agents still face several key technical bottlenecks: (1) Serious family reunification issues The strong van der Waals forces between carbon nanotubes make them prone to forming bundles or agglomerates, which makes dispersion difficult and affects the uniformity of the conductive network.
[0006] (2) High impurity content Carbon nanotubes prepared by existing chemical vapor deposition (CVD) methods often contain residual metal catalysts (such as Fe, Ni, Co, etc.), which can adversely affect battery safety and electrochemical performance.
[0007] (3) Poor interface compatibility Untreated carbon nanotubes have a strong inert surface and weak interfacial bonding with positive and negative electrode active materials, making it difficult to form a stable conductive network.
[0008] To address the above problems, existing technologies have proposed several improvement solutions. For example: Patent CN112038637A discloses a conductive agent composed of carbon nanotubes and carbon black, which improves the conductive network structure through compounding. However, this method still does not effectively solve the problem of carbon nanotube aggregation and has limited dispersion stability.
[0009] In patent CN101243566B, carbon nanotubes are introduced into the binder system to improve conductivity. However, this method mainly relies on system dispersion and has insufficient control over the structure and surface state of the carbon nanotubes themselves.
[0010] Furthermore, relevant research and industrialization progress indicate that the application of carbon nanotubes in lithium-ion batteries still faces problems such as "poor dispersibility, complex processes, and high costs," and there is an urgent need to develop scalable and highly stable preparation technologies.
[0011] In summary, although existing technologies have improved the performance of carbon nanotube conductive agents to some extent through compositing or system optimization, they still have the following shortcomings: 1) Failed to systematically address the aggregation problem based on the intrinsic structure of the material; 2) Lack of synergistic regulation between impurity removal and surface functionalization; 3) The conductive network construction lacks stability, making it difficult to balance low addition levels with high performance; 4) The process is complex or not conducive to large-scale production.
[0012] Therefore, there is an urgent need to provide a method for preparing multi-walled carbon nanotube conductive agents that can simultaneously achieve high purification, high dispersion, strong interfacial bonding, and stable conductive network construction to meet the development needs of high-performance lithium-ion batteries. Summary of the Invention
[0013] Based on the problems raised in the background art mentioned above, this invention proposes a method for preparing multi-walled carbon nanotube conductive agents for lithium-ion batteries.
[0014] The technical solution is as follows: A method for preparing a multi-walled carbon nanotube conductive agent for lithium-ion batteries includes the following steps: (1) Acidification purification step: 120 parts of multi-walled carbon nanotubes were added to a mixed acid system, which consisted of concentrated sulfuric acid and concentrated nitric acid, wherein the concentrated sulfuric acid was 200-240 parts and the concentrated nitric acid was 90-120 parts, and the mixture was refluxed at 80-95°C for 4-6 hours. (2) Water washing and neutralization steps: The reaction product was washed with deionized water until the pH was 6-7, filtered, and dried at 70-90℃ for 6-10 hours. (3) Calcination process: The dried multi-walled carbon nanotubes were calcined under an inert atmosphere, either argon or nitrogen, with the process parameters set as follows: Heating rate: 3–8 °C / min; Firing temperature: 500~650℃; Insulation time: 1–3 hours; (4) Surface functionalization steps: 100-120 parts of calcined multi-walled carbon nanotubes were added to 1200-1500 parts of polar solvent, along with 1-4 parts of boron trifluoride diethyl ether catalyst, 0.15-0.45 parts of 1-propylaminoo-carborane (CAS: 190777-94-7), and 0.3-0.9 parts of ferrocene methylamine. The mixture was reacted at 70-80℃ for 100-140 minutes, filtered, and dried to obtain the functionalized product. (5) Dispersion processing steps: Add 100 parts of the functionalized product to 1200-1400 parts of dispersion medium, and add 5-10 parts of dispersant. Sonicate for 20-40 min, and disperse at a shear rate of 3000-6000 rpm for 10-20 min. (6) Composite construction steps: Add 50-150 parts of conductive carbon black or 20-60 parts of graphene to the dispersion system, and control the mass ratio of multi-walled carbon nanotubes to carbon black to be 1:1-1:3. (7) Drying and pulverizing steps: The obtained slurry was dried at 80–120°C for 8–12 hours and then pulverized to obtain a multi-walled carbon nanotube conductive agent.
[0015] In some embodiments, the multi-walled carbon nanotubes have a purity of ≥95%, a specific surface area of 200–400 m² / g, and a length of 5–20 μm.
[0016] In some embodiments, the dispersion medium is water or N-methylpyrrolidone.
[0017] In some embodiments, the polar solvent is N,N-dimethylformamide or N-methylpyrrolidone.
[0018] In some embodiments, the dispersant is polyvinylpyrrolidone or sodium dodecyl sulfate.
[0019] In some embodiments, the ultrasonic processing power is 300-600W, and an intermittent mode is used, i.e., 2s on / 2s off.
[0020] In some embodiments, the conductive carbon black is acetylene black or Ketjen black.
[0021] In some embodiments, the graphene is few-layer graphene with a specific surface area of 300–800 m² / g.
[0022] In some embodiments, the drying step is performed using vacuum drying or nitrogen atmosphere drying.
[0023] Reaction Mechanism: Under the catalysis of boron trifluoride diethyl ether, the surface-active carboxyl groups of carboxylated multi-walled carbon nanotubes undergo amidation reactions with the amino groups in 1-propylaminoo-carborane and ferrocene methylamine molecules. Stable amide bonds are formed through dehydration of the carboxyl and amino groups, and the boron-containing rigid cage structure and the ferrocene coordination structure are covalently grafted onto the surface of the carbon nanotubes, achieving site-specific functionalization modification of the carbon nanotubes. The reaction process involves only small-molecule site bonding, with no polymerization side reactions, and can stably impart interfacial compatibility and impurity adsorption capacity to the material.
[0024] Compared with the prior art, the present invention has the following advantages: 1. Improved conductivity: Constructs a more continuous and dense three-dimensional conductive network, strengthens the fast electron transport channel, and significantly improves the battery's rate charge and discharge performance and conductivity stability.
[0025] 2. Reduced addition amount: Low percolation threshold, reduced amount of conductive agent, and increased energy density.
[0026] 3. Improved dispersibility: Significantly improves the dispersion of carbon nanotubes in the slurry system, reduces agglomeration, enhances the overall uniformity of the electrode, and effectively reduces interfacial contact resistance.
[0027] 4. Improved cycle stability: Enhances interparticle connections and mitigates contact loss caused by volume changes.
[0028] 5. Enhanced safety: Improves the interfacial bonding strength between the conductive agent and the electrode active material, alleviates structural relaxation during charge and discharge, and enhances the long-term cycle reliability of the battery. Detailed Implementation
[0029] The features of the present invention are further illustrated below through embodiments, but the scope of protection of this patent is not limited to the embodiments.
[0030] Example 1 (1) Acidification purification step 120g of multi-walled carbon nanotubes were added to a mixed acid system, which consisted of concentrated sulfuric acid and concentrated nitric acid, with 200g of concentrated sulfuric acid and 90g of concentrated nitric acid. The mixture was refluxed at 80°C for 4 hours. The multi-walled carbon nanotubes have a purity of ≥95%, a specific surface area of 200 m² / g, and a length of 5 μm.
[0031] (2) Water washing and neutralization steps The reaction product was washed with deionized water until the pH reached 6, filtered, and dried at 70°C for 6 hours. The drying step employs vacuum drying.
[0032] (3) Calcination process The acidified and dried multi-walled carbon nanotubes were calcined under an inert atmosphere of argon, with the following process parameters set: Heating rate: 3℃ / min; Firing temperature: 500℃; Incubation time: 1 hour.
[0033] (4) Surface functionalization steps 100g of calcined multi-walled carbon nanotubes were added to 1200g of polar solvent, along with 1g of boron trifluoride diethyl ether catalyst, 0.15g of 1-propylaminoo-carborane (CAS:190777-94-7), and 0.3g of ferrocene methylamine. The mixture was reacted at 70℃ for 100 minutes, filtered, and dried to obtain the functionalized product. The polar solvent is N,N-dimethylformamide.
[0034] (5) Dispersed processing steps 100g of the functionalized product was added to 1200g of dispersion medium, along with 5g of dispersant. The mixture was ultrasonically treated for 20min and then dispersed at a shear rate of 3000rpm for 10min. The dispersion medium is water; the dispersant is polyvinylpyrrolidone; the ultrasonic treatment power is 300W, and the intermittent mode is used, i.e., 2s on / 2s off.
[0035] (6) Composite construction steps Add 50g of conductive carbon black to the dispersion system and control the mass ratio of multi-walled carbon nanotubes to carbon black to be 1:1. The conductive carbon black is acetylene black.
[0036] (7) Drying and pulverizing steps The obtained slurry was dried at 80℃ for 8 hours and then pulverized to obtain a multi-walled carbon nanotube conductive agent. The drying step employs vacuum drying.
[0037] Example 2 (1) Acidification purification step 120g of multi-walled carbon nanotubes were added to a mixed acid system, which consisted of concentrated sulfuric acid and concentrated nitric acid, with 215g of concentrated sulfuric acid and 100g of concentrated nitric acid. The mixture was refluxed at 86°C for 4.5h. The multi-walled carbon nanotubes have a purity of ≥95%, a specific surface area of 270 m² / g, and a length of 10 μm.
[0038] (2) Water washing and neutralization steps The reaction product was washed with deionized water until the pH reached 6.3, filtered, and dried at 78°C for 7.5 h. The drying step is performed using a nitrogen atmosphere.
[0039] (3) Calcination process The acidified and dried multi-walled carbon nanotubes were calcined under an inert atmosphere (nitrogen atmosphere) with the following process parameters set: Heating rate: 5℃ / min; Firing temperature: 560℃; Insulation time: 1.8h.
[0040] (4) Surface functionalization steps 105g of calcined multi-walled carbon nanotubes were added to 1300g of polar solvent, along with 2g of boron trifluoride diethyl ether catalyst, 0.25g of 1-propylaminoo-carborane (CAS:190777-94-7), and 0.5g of ferrocene methylamine. The mixture was reacted at 73℃ for 115 minutes, filtered, and dried to obtain the functionalized product. The polar solvent is N-methylpyrrolidone.
[0041] (5) Dispersed processing steps 100g of the functionalized product was added to 1280g of dispersion medium, along with 7g of dispersant. The mixture was ultrasonically treated for 28min and then dispersed at a shear rate of 4000rpm for 14min. The dispersion medium is N-methylpyrrolidone; the dispersant is sodium dodecyl sulfate; the ultrasonic treatment power is 400W, and the intermittent mode is used, i.e., 2s on / 2s off.
[0042] (6) Composite construction steps Add 80g of conductive carbon black to the dispersion system, and control the mass ratio of multi-walled carbon nanotubes to carbon black to be 1:1.8; The conductive carbon black is Ketjen black.
[0043] (7) Drying and pulverizing steps The obtained slurry was dried at 95℃ for 9.5 hours and then pulverized to obtain a multi-walled carbon nanotube conductive agent. The drying step is performed using a nitrogen atmosphere.
[0044] Example 3 (1) Acidification purification step 120g of multi-walled carbon nanotubes were added to a mixed acid system, which consisted of concentrated sulfuric acid and concentrated nitric acid, with 225g of concentrated sulfuric acid and 110g of concentrated nitric acid. The mixture was refluxed at 90°C for 5.5h. The multi-walled carbon nanotubes have a purity of ≥95%, a specific surface area of 330 m² / g, and a length of 15 μm.
[0045] (2) Water washing and neutralization steps The reaction product was washed with deionized water until the pH reached 6.7, filtered, and dried at 85°C for 9 hours. The drying step employs vacuum drying.
[0046] (3) Calcination process The acidified and dried multi-walled carbon nanotubes were calcined under an inert atmosphere of argon, with the following process parameters set: Heating rate: 7℃ / min; Firing temperature: 600℃; Insulation time: 2.5h.
[0047] (4) Surface functionalization steps 115g of calcined multi-walled carbon nanotubes were added to 1420g of polar solvent, along with 3.5g of boron trifluoride diethyl ether catalyst, 0.4g of 1-propylaminoo-carborane (CAS:190777-94-7), and 0.8g of ferrocene methylamine. The mixture was reacted at 78℃ for 130 minutes, filtered, and dried to obtain the functionalized product. The polar solvent is N,N-dimethylformamide.
[0048] (5) Dispersed processing steps 100g of the functionalized product was added to 1350g of dispersion medium, along with 9g of dispersant. The mixture was ultrasonically treated for 35min and then dispersed at a shear rate of 5500rpm for 18min. The dispersion medium is water; the dispersant is polyvinylpyrrolidone; the ultrasonic treatment power is 550W, and the intermittent mode is used, i.e., 2s on / 2s off.
[0049] (6) Composite construction steps Add 45g of graphene to the dispersion system and control the mass ratio of multi-walled carbon nanotubes to carbon black to be 1:2.5; The graphene is few-layer graphene with a specific surface area of 600 m² / g.
[0050] (7) Drying and pulverizing steps The obtained slurry was dried at 110℃ for 11 hours and then pulverized to obtain a multi-walled carbon nanotube conductive agent. The drying step employs vacuum drying.
[0051] Example 4 (1) Acidification purification step 120g of multi-walled carbon nanotubes were added to a mixed acid system, which consisted of concentrated sulfuric acid and concentrated nitric acid, with 240g of concentrated sulfuric acid and 120g of concentrated nitric acid. The mixture was refluxed at 95°C for 6 hours. The multi-walled carbon nanotubes have a purity of ≥95%, a specific surface area of 400 m² / g, and a length of 20 μm.
[0052] (2) Water washing and neutralization steps The reaction product was washed with deionized water until the pH reached 7, filtered, and dried at 90°C for 10 hours. The drying step is performed using a nitrogen atmosphere.
[0053] (3) Calcination process The acidified and dried multi-walled carbon nanotubes were calcined under an inert atmosphere (nitrogen atmosphere) with the following process parameters set: Heating rate: 8℃ / min; Firing temperature: 650℃; Insulation time: 3 hours.
[0054] (4) Surface functionalization steps 120g of calcined multi-walled carbon nanotubes were added to 1500g of polar solvent, along with 4g of boron trifluoride diethyl ether catalyst, 0.45g of 1-propylaminoo-carborane (CAS:190777-94-7), and 0.9g of ferrocene methylamine. The mixture was reacted at 80℃ for 140 minutes, filtered, and dried to obtain the functionalized product. The polar solvent is N-methylpyrrolidone.
[0055] (5) Dispersed processing steps 100g of the functionalized product was added to 1400g of dispersion medium, along with 10g of dispersant. The mixture was ultrasonically treated for 40min and then dispersed at a shear rate of 6000rpm for 20min. The dispersion medium is N-methylpyrrolidone; the dispersant is sodium dodecyl sulfate; the ultrasonic treatment power is 600W, and the intermittent mode is used, i.e., 2s on / 2s off.
[0056] (6) Composite construction steps Add 60g of graphene to the dispersion system and control the mass ratio of multi-walled carbon nanotubes to carbon black to be 1:3; The graphene is few-layer graphene with a specific surface area of 800 m² / g.
[0057] (7) Drying and pulverizing steps The obtained slurry was dried at 120℃ for 12 hours and then pulverized to obtain a multi-walled carbon nanotube conductive agent. The drying step is performed using a nitrogen atmosphere.
[0058] Comparative Example 1 (1) Acidification purification step 120g of multi-walled carbon nanotubes were added to a mixed acid system, which consisted of concentrated sulfuric acid and concentrated nitric acid, with 200g of concentrated sulfuric acid and 90g of concentrated nitric acid. The mixture was refluxed at 80°C for 4 hours. The multi-walled carbon nanotubes have a purity of ≥95%, a specific surface area of 200 m² / g, and a length of 5 μm.
[0059] (2) Water washing and neutralization steps The reaction product was washed with deionized water until the pH reached 6, filtered, and dried at 70°C for 6 hours. The drying step employs vacuum drying.
[0060] (3) Calcination process The acidified and dried multi-walled carbon nanotubes were calcined under an inert atmosphere of argon, with the following process parameters set: Heating rate: 3℃ / min; Firing temperature: 500℃; Incubation time: 1 hour.
[0061] (4) Surface functionalization steps 100g of calcined multi-walled carbon nanotubes were added to 1200g of polar solvent, 1g of ethylenediamine was added, and the mixture was reacted at 70℃ for 100 minutes. After filtration and drying, the functionalized product was obtained. The polar solvent is N,N-dimethylformamide.
[0062] (5) Dispersed processing steps 100g of the functionalized product was added to 1200g of dispersion medium, along with 5g of dispersant. The mixture was ultrasonically treated for 20min and then dispersed at a shear rate of 3000rpm for 10min. The dispersion medium is water; the dispersant is polyvinylpyrrolidone; the ultrasonic treatment power is 300W, and the intermittent mode is used, i.e., 2s on / 2s off.
[0063] (6) Composite construction steps Add 50g of conductive carbon black to the dispersion system and control the mass ratio of multi-walled carbon nanotubes to carbon black to be 1:1. The conductive carbon black is acetylene black.
[0064] (7) Drying and pulverizing steps The obtained slurry was dried at 80℃ for 8 hours and then pulverized to obtain a multi-walled carbon nanotube conductive agent. The drying step employs vacuum drying.
[0065] Comparative Example 2 (1) Acidification purification step 120g of multi-walled carbon nanotubes were added to a mixed acid system, which consisted of concentrated sulfuric acid and concentrated nitric acid, with 200g of concentrated sulfuric acid and 90g of concentrated nitric acid. The mixture was refluxed at 80°C for 4 hours. The multi-walled carbon nanotubes have a purity of ≥95%, a specific surface area of 200 m² / g, and a length of 5 μm.
[0066] (2) Water washing and neutralization steps The reaction product was washed with deionized water until the pH reached 6, filtered, and dried at 70°C for 6 hours. The drying step employs vacuum drying.
[0067] (3) Calcination process The acidified and dried multi-walled carbon nanotubes were calcined under an inert atmosphere of argon, with the following process parameters set: Heating rate: 3℃ / min; Firing temperature: 500℃; Incubation time: 1 hour.
[0068] (4) Surface functionalization steps 100g of calcined multi-walled carbon nanotubes were added to 1200g of polar solvent, along with 1g of boron trifluoride diethyl ether catalyst and 0.3g of ferrocene methylamine. The mixture was reacted at 70℃ for 100 minutes, filtered, and dried to obtain the functionalized product. The polar solvent is N,N-dimethylformamide.
[0069] (5) Dispersed processing steps 100g of the functionalized product was added to 1200g of dispersion medium, along with 5g of dispersant. The mixture was ultrasonically treated for 20min and then dispersed at a shear rate of 3000rpm for 10min. The dispersion medium is water; the dispersant is polyvinylpyrrolidone; the ultrasonic treatment power is 300W, and the intermittent mode is used, i.e., 2s on / 2s off.
[0070] (6) Composite construction steps Add 50g of conductive carbon black to the dispersion system and control the mass ratio of multi-walled carbon nanotubes to carbon black to be 1:1. The conductive carbon black is acetylene black.
[0071] (7) Drying and pulverizing steps The obtained slurry was dried at 80℃ for 8 hours and then pulverized to obtain a multi-walled carbon nanotube conductive agent. The drying step employs vacuum drying.
[0072] Comparative Example 3 (1) Acidification purification step 120g of multi-walled carbon nanotubes were added to a mixed acid system, which consisted of concentrated sulfuric acid and concentrated nitric acid, with 200g of concentrated sulfuric acid and 90g of concentrated nitric acid. The mixture was refluxed at 80°C for 4 hours. The multi-walled carbon nanotubes have a purity of ≥95%, a specific surface area of 200 m² / g, and a length of 5 μm.
[0073] (2) Water washing and neutralization steps The reaction product was washed with deionized water until the pH reached 6, filtered, and dried at 70°C for 6 hours. The drying step employs vacuum drying.
[0074] (3) Calcination process The acidified and dried multi-walled carbon nanotubes were calcined under an inert atmosphere of argon, with the following process parameters set: Heating rate: 3℃ / min; Firing temperature: 500℃; Incubation time: 1 hour.
[0075] (4) Surface functionalization steps 100g of calcined multi-walled carbon nanotubes were added to 1200g of polar solvent, along with 1g of boron trifluoride diethyl ether catalyst and 0.15g of 1-propylaminoo-carborane (CAS:190777-94-7). The mixture was reacted at 70℃ for 100 minutes, filtered, and dried to obtain the functionalized product. The polar solvent is N,N-dimethylformamide.
[0076] (5) Dispersed processing steps 100g of the functionalized product was added to 1200g of dispersion medium, along with 5g of dispersant. The mixture was ultrasonically treated for 20min and then dispersed at a shear rate of 3000rpm for 10min. The dispersion medium is water; the dispersant is polyvinylpyrrolidone; the ultrasonic treatment power is 300W, and the intermittent mode is used, i.e., 2s on / 2s off.
[0077] (6) Composite construction steps Add 50g of conductive carbon black to the dispersion system and control the mass ratio of multi-walled carbon nanotubes to carbon black to be 1:1. The conductive carbon black is acetylene black.
[0078] (7) Drying and pulverizing steps The obtained slurry was dried at 80℃ for 8 hours and then pulverized to obtain a multi-walled carbon nanotube conductive agent. The drying step employs vacuum drying.
[0079] Test method: (1) Conductivity test After the conductive agent sample was vacuum dried at 100℃ for 4 hours, it was pressed into a disc with a diameter of 12 mm and a thickness of about 1 mm. It was then pressed under a pressure of 20 MPa for 3 minutes and the conductivity was measured using a four-probe conductivity meter. Ten points were tested for each sample and the average value was taken.
[0080] (2) Electrode resistance test Electrode slurry was prepared by preparing conductive agent in a certain proportion, coated on aluminum foil, dried and rolled to form electrode sheets, and tested using an electrode resistance tester.
[0081] (3) Electrochemical performance testing Assemble the CR2032 button cell: Cathode: LiFePO4 (90wt%) Conductive agent: 2 wt% of the material used in this invention Adhesive: PVDF (8wt%) Electrolyte: 1 mol / L LiPF6 (EC:DMC:DEC = 1:1:1) Negative electrode: Lithium metal Cyclic testing was conducted at 25°C. Charge / discharge rates: 0.1C, 1C, 5C Number of cycles: 100 Table 1 Test Results
[0082] The performance test data show that the sample modified by amidation with 1-propylaminoo-carborane and ferrocene methylamine bismonomers is significantly better than the conventionally modified comparative sample in terms of conductivity, electrode impedance, discharge capacity and cycle retention. This fully demonstrates that the novel functionalized system can synergistically improve the material's dispersibility, conductivity and interfacial bonding, effectively solve the problems of high impedance and insufficient cycle stability of traditional carbon nanotube conductive agents, and significantly improve the overall electrochemical performance.
[0083] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0084] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. A method for preparing a multi-walled carbon nanotube conductive agent for lithium-ion batteries, characterized in that, Includes the following steps, measured in parts by weight: (1) Acidification purification step: 120 parts of multi-walled carbon nanotubes were added to a mixed acid system, which consisted of concentrated sulfuric acid and concentrated nitric acid, wherein the concentrated sulfuric acid was 200-240 parts and the concentrated nitric acid was 90-120 parts, and the mixture was refluxed at 80-95°C for 4-6 hours. (2) Water washing and neutralization steps: The reaction product was washed with deionized water until the pH was 6-7, filtered, and dried at 70-90℃ for 6-10 hours. (3) Calcination process: The dried multi-walled carbon nanotubes were calcined under an inert atmosphere, either argon or nitrogen, with the process parameters set as follows: Heating rate: 3–8 °C / min; Firing temperature: 500~650℃; Insulation time: 1–3 hours; (4) Surface functionalization steps: 100-120 parts of calcined multi-walled carbon nanotubes were added to 1200-1500 parts of polar solvent, along with 1-4 parts of boron trifluoride diethyl ether catalyst, 0.15-0.45 parts of 1-propylaminoo-carborane, and 0.3-0.9 parts of ferrocene methylamine. The mixture was reacted at 70-80°C for 100-140 minutes, filtered, and dried to obtain the functionalized product. (5) Dispersion processing steps: Add 100 parts of the functionalized product to 200-300 parts of the dispersion medium, and add 5-10 parts of the dispersant. Sonicate for 20-40 minutes, and disperse at a shear rate of 3000-6000 rpm for 10-20 minutes. (6) Composite construction steps: Add 50-150 parts of conductive carbon black or 20-60 parts of graphene to the dispersion system, and control the mass ratio of multi-walled carbon nanotubes to carbon black to be 1:1-1:
3. (7) Drying and pulverizing steps: The obtained slurry was dried at 80–120°C for 8–12 hours and then pulverized to obtain a multi-walled carbon nanotube conductive agent.
2. The method for preparing a multi-walled carbon nanotube conductive agent for lithium-ion batteries according to claim 1, characterized in that: The multi-walled carbon nanotubes have a purity of ≥95%, a specific surface area of 200–400 m² / g, and a length of 5–20 μm.
3. The method for preparing a multi-walled carbon nanotube conductive agent for lithium-ion batteries according to claim 1, characterized in that: The dispersion medium is water or N-methylpyrrolidone.
4. The method for preparing a multi-walled carbon nanotube conductive agent for lithium-ion batteries according to claim 1, characterized in that: The polar solvent is N,N-dimethylformamide or N-methylpyrrolidone.
5. The method for preparing a multi-walled carbon nanotube conductive agent for lithium-ion batteries according to claim 1, characterized in that: The dispersant is polyvinylpyrrolidone or sodium dodecyl sulfate.
6. The method for preparing a multi-walled carbon nanotube conductive agent for lithium-ion batteries according to claim 1, characterized in that: The ultrasonic processing power is 300-600W, and it adopts an intermittent mode, i.e., 2s on / 2s off.
7. The method for preparing a multi-walled carbon nanotube conductive agent for lithium-ion batteries according to claim 1, characterized in that: The conductive carbon black is acetylene black or Ketjen black.
8. The method for preparing a multi-walled carbon nanotube conductive agent for lithium-ion batteries according to claim 1, characterized in that: The graphene is few-layer graphene with a specific surface area of 300–800 m² / g.
9. The method for preparing a multi-walled carbon nanotube conductive agent for lithium-ion batteries according to claim 1, characterized in that: The drying step employs vacuum drying or nitrogen atmosphere drying.