KR-20260064144-A - Mass production method for high concentration slurry of non-oxidation carbon nanotube and non-oxidation carbon nanotube conductive agent produced thereby

Abstract

The present invention relates to a method for mass-producing a high-concentration, high-performance conductive material optimized for an electrode manufacturing process by solvent-dispersing carbon nanotubes having a hydrophobic surface and a bundle shape without acid treatment, for the purpose of manufacturing a slurry containing an active material, a binder, and a conductive material essential for manufacturing a secondary battery electrode plate, comprising: a first step of kneading carbon nanotube powder in alcohol to homogeneously mix carbon nanotubes having a hydrophobic surface with a hydrophilic solvent; and a second step of mixing the carbon nanotubes from the first step with a binder and penetrating them through shear force; A third step comprising preparing a homogeneously dispersed carbon nanotube dispersion by effectively penetrating a binder between carbon nanotube bundles using mechanical impregnation methods such as a kneading method, a shear-induced mixing method, and a sonication method, thereby inducing homogeneous dispersion in a hydrophilic solvent, and preparing a carbon nanotube dispersion solution without acid treatment by effectively penetrating a binder between carbon nanotube bundles; a fourth step in which the dispersion solution formed through the third step is prepared in the form of a high-concentration slurry by adding an acidic solution to adjust the pH to prepare the binder in a gel form, thereby separating the dispersed carbon nanotubes from the solvent; and a fifth step of a purification process in which the fourth step is centrifuged to remove excess binder and impurities. The technical gist of the invention is a method for manufacturing an intermediate material for a secondary battery conductive material that allows for easy control of composition in the electrode manufacturing process by using a conductive material with solid content and viscosity characteristics that can satisfy user requirements, through a 6th step in which a basic solution is added to redisperse the acidic gel-type paste of the 5th step to maintain a stable dispersion state in the form of a slurry in which solid content and viscosity can be controlled, thereby enabling the manufacture of an electrode plate using a conductive material with minimized solvent during the slurry process for electrode plate composition.

Inventors

• 정승열
• 김병국
• 정수연
• 이혜정
• 양선혜
• 김정모
• 이건웅
• 김익준

Assignees

• 한국전기연구원

Dates

Publication Date

20260507

Application Date

20241031

Claims (2)

1. A step of preparing a carbon nanotube dough having a hydrophilic surface in which the surface of each carbon nanotube forming the bundle becomes wet by kneading the bundle-shaped carbon nanotubes by adding them to alcohol and applying shear force while kneading; A step of preparing a carbon nanotube-binder mixture in which the binder is penetrated between each carbon nanotube forming the bundle by means of the hydrophilic surface of each carbon nanotube by mixing the carbon nanotube paste with a binder and applying a shear force; A step of preparing a carbon nanotube dispersion solution in which each carbon nanotube is debundled and dispersed by ultrasonically treating the carbon nanotube-binder mixture; A step of preparing a carbon nanotube-binder gel by adjusting the pH of the carbon nanotube dispersion solution to acidic to gel the binder; A step of separating a high-concentration carbon nanotube slurry in the form of a precipitate by centrifuging the carbon nanotube-binder gel; and A method for mass production of a non-oxidized carbon nanotube high-concentration slurry, characterized by comprising the step of mixing a basic solution into the carbon nanotube high-concentration slurry to redisperse while controlling the solid content and viscosity.
2. A non-oxidized carbon nanotube high-concentration slurry characterized by being manufactured by the method of claim 1.

Description

Mass production method for high concentration slurry of non-oxidation carbon nanotubes and high concentration slurry of carbon nanotubes produced thereby The present invention relates to a method for mass-producing a non-oxidized carbon nanotube high-concentration slurry and a carbon nanotube high-concentration slurry produced therefrom. As the adoption of silicon in high-nickel cathode and anode materials is essential to meet the development requirements of high-performance secondary batteries, such as increased energy density and reduced charging time, technological development is proceeding with a focus on resolving the technical challenges involved in applying new next-generation materials—including carbon nanotubes (CNT), graphene, and carbon nanofibers—to improve electrical conductivity and address issues related to silicon expansion, efficiency, and reduced lifespan. Furthermore, electrode materials are distinguished according to the application field of secondary batteries, and the application of high-performance conductive materials is essential to overcome cell performance degradation caused by the surface characteristics and size diversity of electrode materials. Conventional carbon black has a large volume and limits the improvement of conductivity (~1 S/cm); furthermore, because it exists in a particulate form, a large amount of binder must be used to ensure mechanical stability. On the other hand, when carbon nanomaterials such as CNTs or graphene are composited, improved electrical conductivity can be achieved with a small amount, and structural stability can be ensured because the mechanical properties are superior compared to carbon black, which exists in an aggregated form. This is because it facilitates the formation of a continuous network within the electrode. For example, as an additive for lithium-ion batteries, CNT conductive material exhibits superior performance compared to conventional carbon black, and the amount of conductive material used can be reduced to one-fifth of the conventional level, allowing for an increase in the active material composition and the realization of high-capacity electrode technology. In this regard, linear conductive materials such as carbon nanotubes (CNTs) have begun to be applied to electrode processes in some secondary battery sectors, specifically for small IT products, rather than carbon black-based particulate conductive materials. Furthermore, research is being conducted with carbon nanoparticle manufacturers to develop shape control technologies for carbon nanoparticles, including CNTs, to enhance cell performance. In particular, silicon-based active materials are emerging as a key application for high-capacity anodes. Since most anode manufacturing processes are water-based, water-based dispersion technologies for hydrophobic carbon nanomaterials (such as CNTs and graphene) are required. Currently, only a small number of CNT products in the form of organic dispersion solutions are commercially available, with an electrical conductivity of approximately 100 S/cm. These carbon nanotubes are classified into single-walled carbon nanotubes (1–3 nm), double-walled carbon nanotubes (3–4 nm), thin multi-walled carbon nanotubes (4–20 nm), and multi-walled carbon nanotubes (20–50 nm) depending on the number of layers synthesized, and can be distinguished by diameter. In particular, single-walled carbon nanotubes have a very small diameter and a very large aspect ratio, so they are manufactured in the form of bundles due to van der Waals forces between tubes during synthesis. At this time, the diameter of the bundle is in the form of flakes of about several millimeters. To realize the excellent performance of carbon nanotubes, they must be manufactured into an intermediate form through debundling and dispersion in an appropriate solvent, which is a very important factor for application in products. Existing methods proposed for the debundling and dispersion of carbon nanotubes are broadly divided into two categories. First, there is a chemical method that uses strong acids to introduce oxygen functional groups into carbon nanotubes and then debundles and disperses them; and second, there is a method utilizing carbon nanotubes with a dispersant or binder. The first method, the oxidized carbon nanotube preparation method, involves debundling and dispersing carbon nanotubes using strong acids or oxidizing agents. This method is effective for ensuring dispersibility, minimizes bundle size to improve carbon nanotube properties, and facilitates dispersion. However, it has disadvantages, such as degradation of electrical properties due to defect formation during strong acid treatment, the need for an additional reduction process to remove oxygen functional groups, and issues regarding the treatment of acid wastewater resulting from the use of strong acids. The second method, the non-oxidized carbon nanotube preparation method, involves debundling and dispersio