KR-20260066680-A - ANODE ACTIVE MATERIAL, METHOD OF MANUFACTURING THE SAME AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

Abstract

One aspect of the present invention is to provide a negative electrode active material. The negative electrode active material comprises natural graphite and silicon-based particles, and the negative electrode active material may satisfy Formula 1 below. [Equation 1] 0.04g/㎤ ≤ D press - D tap ≤ 0.085g/㎤ (In Equation 1 above, D press is the compressive density of the negative electrode active material at an applied pressure of 5.5 kgf/㎠, and D tap is the tap density of the negative electrode active material.)

Inventors

• 강수희
• 정수연
• 이경묵
• 신명수
• 이세현
• 권해준
• 안기홍
• 김수민
• 최호선

Assignees

• (주)포스코퓨처엠

Dates

Publication Date

20260512

Application Date

20260413

Claims (18)

1. As a negative electrode active material, Natural graphite; and Contains silicon-based particles, The above cathode active material is a cathode active material satisfying the following Equation 1. [Equation 1] 0.04g/㎤ ≤ D press - D tap ≤ 0.085g/㎤ (In Equation 1 above, D press is the compressive density of the negative electrode active material at an applied pressure of 5.5 kgf/㎠, and D tap is the tap density of the negative electrode active material.)
2. In Article 1, The above natural graphite has a pH of 7.0 or higher and is a negative electrode active material.
3. In Article 1, The above silicon-based particles are a negative electrode active material comprising one or more selected from the group consisting of silicon, silicon-carbon composites, and silicon oxide.
4. In Article 1, A negative electrode active material that does not include a coating layer containing low-crystallinity carbon material on the surface of the above negative electrode active material.
5. In Article 1, A cathode active material having a BET specific surface area of 4.8 m²/g or more.
6. In Article 1, The above-mentioned cathode active material has an oil absorption capacity of 50.0 mL/100 g or more.
7. In Article 1, The above negative electrode active material has an average particle size (D50) of 16.0 to 21.0 μm.
8. In Article 1, The above negative electrode active material has a tap density of 0.95 g/cm³ or less.
9. In Article 1, A cathode active material having a degree of sphericity of 0.85 or higher.
10. In Article 1, The above-mentioned negative electrode active material is a negative electrode active material containing 2 to 5 weight percent of silicon-based particles based on the total weight of the negative electrode active material.
11. Step of preparing natural graphite powder; A step of heat-treating the above natural graphite powder at a temperature of 500 to 650°C under an inert gas atmosphere; and A method for manufacturing a cathode active material, comprising the step of mixing the heat-treated natural graphite powder and silicon-based powder to obtain a cathode active material.
12. In Article 11, A method for manufacturing a cathode active material in which the above inert gas is nitrogen.
13. In Article 11, A method for manufacturing a cathode active material in which the heat treatment step is performed for 1 to 12 hours.
14. In Article 11, A method for manufacturing a negative electrode active material comprising one or more selected from the group consisting of silicon, silicon-carbon composites, and silicon oxides, wherein the above silicon-based powder.
15. In Article 11, A method for manufacturing a negative electrode active material, wherein, in the step of obtaining the negative electrode active material, the silicon-based powder is mixed in an amount of 2 to 5 weight percent based on the total weight of the negative electrode active material.
16. In Article 11, A method for manufacturing a cathode active material, wherein, in the step of obtaining the cathode active material, the cathode active material does not include a coating layer containing a low-crystallinity carbon material on the surface of the cathode active material.
17. A negative electrode for a lithium secondary battery comprising a negative electrode active material according to any one of claims 1 to 10.
18. A lithium secondary battery comprising a negative electrode for a lithium secondary battery according to claim 16.

Description

Anode active material, method of manufacturing the same, and lithium secondary battery comprising the same The present invention relates to a negative electrode active material, a method for manufacturing the same, and a lithium secondary battery including the same. With the increasing technological development and demand for mobile devices, the demand for rechargeable, miniaturized, and high-capacity secondary batteries is rapidly rising. Recently, the use of secondary batteries as a power source for hybrid electric vehicles (HEVs) and electric vehicles (EVs) is becoming a reality. Accordingly, much research is being conducted on secondary batteries capable of meeting various demands, and in particular, there is a rising demand for lithium secondary batteries with high energy density, discharge voltage, and output. In addition, secondary batteries used in electric vehicles and the like must be able to have high energy density and high power output in a short period of time, and must be able to be used for a long period of time under conditions where charging and discharging with high current is repeated in a short period of time, so superior power characteristics and long life characteristics are required compared to conventional secondary batteries. As such, as the demand for high-energy-density batteries increases, research is actively being conducted on methods to increase capacity by using silicon-based materials such as Si, Si-C composites, and SiOx as negative electrode active materials, which have a capacity more than 10 times greater than that of graphite-based materials. However, while silicon-based materials exhibit superior capacity characteristics compared to graphite, they undergo rapid volume expansion during the charging process, which disrupts conductive pathways and degrades battery performance, leading to a problem where battery lifespan characteristics deteriorate. Accordingly, there is a need for research on mixed negative electrode active materials of graphite and silicon-based materials that can secure both battery capacity and lifespan characteristics. Preferred embodiments of the present invention are described below. However, embodiments of the present invention may be modified in various other forms, and the terms used herein are for describing the present invention and are not intended to limit the present invention. Additionally, singular forms used herein include plural forms unless the relevant definitions expressly indicate otherwise. In this specification, the term “includes” is used to indicate that other components may be included, rather than excluding other components, unless specifically stated otherwise. In addition, unless otherwise specifically defined in the specification of the present invention, the % unit means weight %. In addition, in this specification, “Dn” refers to the particle size distribution and may refer to the particle size at the n% point of the cumulative distribution of the number of particles according to particle size. For example, D50 is the particle size (average particle size) at the 50% point of the cumulative distribution of the number of particles according to particle size, D90 is the particle size at the 90% point of the cumulative distribution of the number of particles according to particle size, and D10 is the particle size at the 10% point of the cumulative distribution of the number of particles according to particle size. Meanwhile, the particle size distribution can be measured using the laser diffraction method. Specifically, the particle size distribution can be calculated by dispersing the powder to be measured in a dispersion medium, introducing it into a laser diffraction particle size measuring device, and measuring the difference in diffraction patterns according to particle size as the particles pass through the laser beam. Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms defined in advance are interpreted to have meanings consistent with relevant technical literature and the presently disclosed content. Recently, as the applications of lithium secondary batteries have diversified, the demand for high energy density has increased. Accordingly, research is actively being conducted on methods to increase capacity by using silicon-based active materials, such as Si, Si-C composites or SiOx, which have a capacity more than 10 times greater than that of natural graphite-based active materials, as negative electrode active materials. However, in the case of silicon-based active materials, although the capacity characteristics are excellent, there was a problem in that the lifespan characteristics deteriorated because the volume expanded rapidly during repeated charging and discharging processes, thereby severing the conductive path. Meanwhile, in general, natural graphi