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KR-102963887-B1 - NEGATIVE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY AND METHOD OF MANUFACTURING

KR102963887B1KR 102963887 B1KR102963887 B1KR 102963887B1KR-102963887-B1

Abstract

The present invention comprises a core portion comprising silicon oxide, a negative electrode active material for a lithium secondary battery, and a shell portion disposed on at least a portion of the core portion and comprising a carbon-based material, wherein the content of the carbon-based material in the shell portion is 1.0 to 3.0 weight% based on 100 weight% of the total negative electrode active material, and the thickness of the shell portion is 20 to 100 nm.

Inventors

  • 박종현
  • 정지권
  • 이동규
  • 소비홍

Assignees

  • (주)포스코퓨처엠

Dates

Publication Date
20260512
Application Date
20230926
Priority Date
20230831

Claims (15)

  1. A core portion comprising silicon oxide; and It includes a shell portion disposed in at least a portion of the core portion and comprising a carbon-based material, and The above shell portion has a carbon-based material content of 1.0 to 3.0 weight% based on 100 weight% of the total negative electrode active material, and The thickness of the shell portion is 20 to 100 nm, and A negative electrode active material for a lithium secondary battery satisfying the following Equation 1 in terms of XRD peak values. <Equation 1> 1.0 < I A /I B < 2.0 (In Equation 1 above, I A represents the peak value at 18.5 to 21.5°, and I B represents the peak value at 27.5 to 30.0°)
  2. delete
  3. In Article 1, A negative electrode active material for a lithium secondary battery having an average particle size (D50) of 1.0 to 8.0 μm.
  4. In Article 1, The above carbon-based material is a negative electrode active material for a lithium secondary battery, which is low-crystallinity carbon.
  5. In Article 1, Negative electrode active material for a lithium secondary battery having a specific surface area of 1.3 to 4.0 m² /g.
  6. A step of grinding a raw material containing silicon oxide; A step of adding 1.0 to 3.0 weight percent of a carbon-based material, based on weight percent, to crushed silicon oxide particles and mixing in a solid state; and A method for manufacturing a negative electrode active material for a lithium secondary battery according to claim 1, comprising the step of heat-treating a mixed mixture.
  7. In Article 6, A method for manufacturing a cathode active material in which the step of mixing the above raw material and the above carbon-based material in a solid state is performed in the range of 20.0 to 300.0 J.
  8. In Article 6, A method for manufacturing a cathode active material in which the step of mixing the above raw material and the above carbon-based material in a solid state is performed at 400 to 800 rpm.
  9. In Article 6, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the step of mixing the above raw material and the above carbon-based material in a solid state is performed by at least one of a V-mixer, Nauta mixer, High Speed Mixer, Kneader mixer, Banbury mixer, High-shear mixer, and a general Planetary mixer.
  10. In paragraph 6, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the step of heat-treating the above-mentioned mixed mixture is performed at 900 to 1100 ℃.
  11. In Article 6, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the step of heat-treating the above-mentioned mixed mixture is performed at a heating rate of 3.5 to 8.5 ℃/min.
  12. In Article 6, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the step of heat-treating the above-mentioned mixed mixture is performed for 2 to 4 hours.
  13. In Article 6, The above raw material is a method for manufacturing a negative electrode active material for a lithium secondary battery having an average particle size of 1 to 8 μm.
  14. In paragraph 6, A method for manufacturing a negative electrode active material for a lithium secondary battery, comprising at least one grinding step for grinding the above raw material.
  15. In Article 14, The step of grinding the raw material comprises a coarse grinding step of grinding the average particle size (D50) of the raw material to 1.0 to 5.0 mm; A medium grinding step for grinding the average particle size (D50) of the ground material obtained from the above coarse grinding step to 50.0 to 400.0 μm; and A method for manufacturing a negative electrode active material for a lithium secondary battery, comprising a fine grinding step in which the average particle size (D50) of the ground material obtained through the above medium grinding step is ground to 1.0 μm to 80 μm.

Description

Negative active material for lithium secondary battery and method of manufacturing the same The present invention relates to a lithium secondary battery, and more specifically, to a negative electrode active material for a lithium secondary battery and a method for manufacturing the same. 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. Recently, due to the rapid rise of electric vehicles (EVs), expectations for the aforementioned lithium-ion batteries are growing, and there is an increasing demand for improvements in rapid charging characteristics while preserving existing capacity. For the improvement of such rapid charging, the role of the negative electrode active material, which is responsible for storing lithium ions during charging, is becoming increasingly important. Materials such as metallic lithium negative electrode active materials, carbon-based negative electrode active materials, or silicon oxide (SiOx) are used as the above negative electrode active materials. The carbon-based negative electrode active materials exhibit excellent capacity retention characteristics and efficiency. Since carbon-based negative electrode active materials used as negative electrodes in lithium secondary batteries have a potential close to that of lithium metal, changes in the crystal structure are small during the insertion and extraction processes of ionic lithium. Furthermore, the carbon-based negative electrode active materials enable continuous and repetitive oxidation and reduction reactions at the electrode, allowing the lithium secondary battery to exhibit high capacity and excellent lifespan. Among the aforementioned negative electrode active materials, silicon oxide offers the advantage of high capacity and excellent electrical characteristics when utilized in batteries. Specifically, a carbon-based material is coated onto the silicon oxide raw material for use. While CVD coating is generally used to coat the silicon oxide raw material with the carbon-based material, there are safety concerns due to the use of harmful gases, such as methane, during the CVD coating process. FIG. 1 illustrates a negative electrode active material for a lithium secondary battery according to one embodiment of the present invention. FIG. 2a is a TEM image of the negative electrode active material of the present invention, and FIG. 2b to 2e are SEM images of the negative electrode active material of the present invention. Figure 3 is a TEM image of the shell portion of the cathode active material of the present invention. FIGS. 4a to 4c illustrate the content of Si, O, and C elements of the present invention. FIG. 5a shows a graph of a discharge HPPC according to an example and a comparative example, and FIG. 5b shows a graph of a charge HPPC according to an example and a comparative example. Figures 6a and 6b respectively show a graph of the discharge rate limit characteristic and a discharge curve graph, and Figures 6c and 6d respectively show a graph of the charge rate limit characteristic and a charge curve graph. Figur