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KR-20260063269-A - METHOD OF MANUFACTURING ANODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY

KR20260063269AKR 20260063269 AKR20260063269 AKR 20260063269AKR-20260063269-A

Abstract

The present invention relates to a method for manufacturing a negative electrode active material for a lithium secondary battery, comprising the steps of pre-treating a graphite material, mixing and aggregating the pre-treated graphite material and pitch, and graphitizing the aggregated material produced in the mixing and aggregating step, wherein the mixing and aggregating step is performed through a continuous aggregator, and the mixing and aggregating step is performed at a continuous input temperature of 300 to 600 ℃ and for an aggregation time of 6 to 9 hours.

Inventors

  • 김대식
  • 김가은
  • 강수희
  • 안수현
  • 최태선
  • 장영훈
  • 최현기

Assignees

  • (주)포스코퓨처엠

Dates

Publication Date
20260507
Application Date
20241030

Claims (18)

  1. Step of pre-treating graphite material; A step of mixing and assembling the pretreated graphite material and pitch; and The method includes a step of graphitizing the aggregate material generated in the above mixing and assembling step, and The above mixing and assembling steps are performed through a continuous assembly machine, and A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the mixing and assembling steps are performed at a continuous input temperature of 300 to 600 ℃ and an assembling time of 6 to 9 hours.
  2. In Article 1, The above mixing and assembling step is a method for manufacturing a negative electrode active material for a lithium secondary battery, which includes a heating section, a constant temperature section, and a cooling section in sequence.
  3. In Article 2, The above-mentioned heating section is a method for manufacturing a negative electrode active material for a lithium secondary battery, comprising a multi-stage heating step.
  4. In Paragraph 3, A method for manufacturing a negative electrode active material for a lithium secondary battery, comprising the above multi-stage heating step, a first heating step, and a second heating step of raising the temperature of the continuous assembly machine to a temperature higher than the first heating step.
  5. In Paragraph 4, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the heating rate of the first heating step is 2.0 to 3.0 ℃/min.
  6. In Paragraph 4, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the heating rate of the second heating step is 1.5 to 5.0 ℃/min.
  7. In Paragraph 4, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the heating time of the second heating step is performed for 50 to 150 minutes.
  8. In Paragraph 4, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the intermediate temperature, which is the maximum temperature of the first heating step, is 400 to 500 ℃.
  9. In Paragraph 4, The above first constant temperature step is included between the first heating step and the second heating step, and After the above second heating step, a second constant temperature step is included, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the holding time of the first constant temperature step is greater than the holding time of the second constant temperature step.
  10. In Article 1, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the maximum temperature of the above-mentioned continuous assembly machine is 700 ℃ or less.
  11. In Article 1, The step of pre-treating the graphite material is, A method for manufacturing a negative electrode active material for a lithium secondary battery, comprising the step of grinding the graphite material.
  12. In Article 11, The step of grinding the graphite material above comprises a coarse grinding step; and A method for manufacturing a negative electrode active material for a lithium secondary battery, comprising a fine grinding step for grinding the graphite material to a particle size range lower than the above coarse grinding step.
  13. In Article 12, The above coarse grinding step is a method for manufacturing a negative electrode active material for a lithium secondary battery, which grinds the graphite material to 1 mm or less.
  14. In Article 12, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the fine grinding step comprises grinding the graphite material that has undergone the coarse grinding step to a size of 20 μm or less.
  15. In Article 1, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the content of the pitch is mixed in an amount of 5 to 25 parts by weight based on 100 parts by weight of the graphite material.
  16. In Article 1, The above mixing and assembling step is a method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the graphite material and the pitch are assembled for 5 to 10 hours.
  17. In Article 1, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the above mixing and assembling steps are performed in an inert gas atmosphere.
  18. In Article 1, A method for manufacturing a negative electrode active material for a lithium secondary battery, comprising the step of coating the graphitized graphitized product after the graphitization step.

Description

Method of manufacturing anode active material for lithium secondary battery The present embodiments relate to a lithium secondary battery, and more specifically, to a method for manufacturing a negative electrode active material for a lithium secondary battery. A lithium secondary battery generally consists of a positive electrode containing a positive active material, a negative electrode containing a negative active material, a separator, and an electrolyte, and charging and discharging are performed through the intercalation and decalation of lithium ions. Since the lithium secondary battery possesses the advantages of high energy density, high electromotive force, and the ability to exhibit high capacity, it is being applied in various fields. Furthermore, improving high-temperature performance, such as high-temperature storage and cycling characteristics, in lithium secondary batteries is a critical challenge. For example, there is a significant problem where the high-temperature performance of the anode is likely to deteriorate if the total internal pore volume is high after the anode active material is coated onto a current collector and rolled. Therefore, it is necessary to improve high-temperature characteristics when developing anode active materials for lithium secondary batteries, such as rapid-charge batteries, by minimizing changes in electrode structure and total internal pore volume that occur during electrode rolling. Furthermore, as technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly rising. Among secondary batteries, lithium secondary batteries, which exhibit high energy density and operating potential, long cycle life, and low self-discharge rate, have been commercialized and are widely used. Furthermore, as interest in environmental issues grows, there is increasing interest in electric vehicles and hybrid electric vehicles that can replace fossil fuel-using vehicles, such as gasoline and diesel vehicles, which are one of the major causes of air pollution; consequently, research is actively underway to use lithium-ion batteries as a power source for the aforementioned electric vehicles and hybrid electric vehicles. As expectations for lithium secondary batteries grow, the role of the negative electrode active material responsible for storing lithium ions in the lithium secondary battery is becoming increasingly important. Materials such as metallic lithium negative electrode active materials, carbon-based negative electrode active materials, or silicon oxide (SiO₂ x₆ ) are used as the negative electrode active materials. The carbon-based negative electrode active materials exhibit excellent capacity retention characteristics and efficiency. Since the carbon-based negative electrode active material used as the negative electrode of a lithium secondary battery has a potential close to that of lithium metal, the change in crystal structure is small during the insertion and extraction processes of ionic lithium. Furthermore, the carbon-based negative electrode active material enables continuous and repetitive oxidation and reduction reactions at the electrode, allowing the lithium secondary battery to exhibit high capacity and excellent lifespan. Various types of materials are used as the carbon-based negative electrode active materials, such as crystalline carbon-based materials like natural graphite and artificial graphite, or amorphous carbon-based materials like hard carbon and soft carbon. Among the carbon-based negative electrode active materials, graphite-based negative electrode active materials are the most widely used because they have excellent reversibility and can improve the lifespan characteristics of lithium secondary batteries. Since the discharge voltage of the graphite-based negative electrode active material is low at -0.2 V compared to lithium, a battery using the graphite-based active material can exhibit a high discharge voltage of 3.6 V, which has an excellent advantage in terms of energy density of lithium secondary batteries. The artificial graphite, which is a crystalline carbon-based material, has a more stable crystal structure than the natural graphite because it is formed by applying high thermal energy of 2,700°C or higher. Since the change in the crystal structure is small even with repeated charging and discharging of lithium ions, the artificial graphite has the advantage of having a lifespan that is 2 to 3 times longer than that of the natural graphite, so there is growing interest in the method of producing artificial graphite. In the manufacturing process of the above artificial graphite, the process may include a step of assembling the artificial graphite and pitch by heat-treating a mixture of the artificial graphite and pitch in a kiln to secondary particleize the artificial graphite. The step of assembling the artificial graphite and pitch is generally carried out in a batc