KR-102963862-B1 - NEGATIVE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY AND METHOD OF MANUFACTURING

Abstract

The present invention relates to a negative electrode active material for a lithium secondary battery and a method for manufacturing the same, wherein the negative electrode active material for a lithium secondary battery comprises a graphite-based core portion; a carbonaceous layer disposed on at least a portion of the graphite-based core portion, and in the volume cumulative particle size distribution by laser diffraction, the ratio of Dmin to Dmax is 0.005 to 0.40.

Inventors

• 김가은
• 장영훈
• 최현기
• 김대식
• 권성상
• 송현준
• 정명선
• 김종찬
• 이승은
• 연선영

Assignees

• (주)포스코퓨처엠

Dates

Publication Date

20260511

Application Date

20230926

Claims (16)

1. A graphite-based core portion derived from coke having a Hardgrove Grindability Index (HGI) of 42 to 120; It includes a carbonaceous layer disposed on at least a portion of the graphite-based core portion, and A negative electrode active material for a lithium secondary battery having a ratio of Dmin to Dmax of 0.005 to 0.40 in a volume cumulative particle size distribution by laser diffraction. (The above Dmin and Dmax represent the particle sizes corresponding to the minimum and maximum values of the cumulative volume of the negative electrode active material, respectively, measured using the Laser Diffraction Method.)
2. delete
3. In Article 1, A negative electrode active material for a lithium secondary battery satisfying Formula 1 below. <Equation 1> 0.65 ≤ ([SOC 50 %] - [SOC 10 %])/[SOC 30 %] ≤ 2.00 (In Equation 1 above, [SOC 10%], [SOC 30%], and [SOC 50%] represent the average voltage values when the SOC is 10%, 20%, and 50%, respectively.)
4. In Article 1, Negative electrode active material for a lithium secondary battery having a voltage value of -0.180 V or less at SOC 50%.
5. In Article 1, The above Dmax is a negative electrode active material for a lithium secondary battery, with a value of 40.0 to 65.0 μm.
6. In Article 1, The above Dmin is a negative electrode active material for a lithium secondary battery having a value of 2.0 to 12.5 μm.
7. In Article 1, A negative electrode active material for a lithium secondary battery in which the orientation degree (I 002 /I 110 ) in the XRD peak value satisfies the following Equation 2. <Equation 2> 1.5 ≤ I 002 /I 110 ≤ 3.0 (In Equation 2 above, I 002 represents the peak intensity value on plane 002, and I 110 represents the peak intensity value on plane 110.)
8. In Article 1, A negative electrode active material for a lithium secondary battery having a tap density of 0.85 g/cm³ or higher.
9. A step of grinding coke having a Hardgrove Grindability Index (HGI) of 42 to 120; Step of assembling crushed particles and carbonaceous material; and It includes a step of graphitizing crushed particles, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the negative electrode active material manufactured through the above-mentioned graphitization step has a ratio of Dmin to Dmax of 0.005 to 0.40 in the volume cumulative particle size distribution by laser diffraction. (The above Dmin and Dmax represent the particle sizes corresponding to the minimum and maximum values of the cumulative volume of the negative electrode active material, respectively, measured using the Laser Diffraction Method.)
10. In Article 9, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the grindability index of the above coke is 67 to 100.
11. In Article 9, The above coke is a method for manufacturing a negative electrode active material for a lithium secondary battery having an ash content of 0.05 to 0.15%.
12. In Article 9, A method for manufacturing a negative electrode active material for a lithium secondary battery, comprising a preliminary carbonization step of calcining at a lower temperature than the graphitization step prior to the graphitization step of the above-mentioned crushed particles.
13. In Article 12, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the above preliminary carbonization step is performed in the range of 800 to 1,500 ℃.
14. In Article 9, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the above coke comprises at least one of petroleum-based general green coke, petroleum-based general calcined coke, and coal-based needle green coke.
15. In Article 9, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the volatile content of the above coke is 0.2 to 10.0%.
16. In Article 9, The step of crushing the above coke comprises: a step of coarsely crushing the above coke so that the average particle size (D50) of the above coke is 1 mm or less; and A method for manufacturing a negative electrode active material for a lithium secondary battery, comprising a step of finely grinding the coke that has undergone a coarse grinding step so that the average particle size (D50) of the coke is 5 to 20 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. As the above-mentioned negative electrode active material, materials such as metallic lithium negative electrode active material, carbon-based negative electrode active material, or silicon oxide (SiO x ) are used. The above-mentioned carbon-based negative electrode active material exhibits 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 the electrode potential of lithium metal, the change in crystal structure is small during the insertion and extraction processes of ionic lithium. In addition, the above-mentioned carbon-based negative electrode active material enables continuous and repetitive oxidation and reduction reactions at the electrode, thereby 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 creates a graphite crystal structure by applying high thermal energy of 2,700°C or higher, and the change in the crystal structure is small even with repeated charging and discharging of lithium ions, so the artificial graphite has the advantage of having a lifespan that is 2 to 3 times longer than that of the natural graphite. Accordingly, research is underway to utilize the aforementioned artific