KR-20260065591-A - ANODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY, MANUFACTURING METHOD OF THE SAME AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

Abstract

The present embodiments relate to a negative electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same. A negative electrode active material for a lithium secondary battery according to one embodiment comprises a first graphite and a second graphite having an average particle size (D50) smaller than that of the first graphite, and the pore volume calculated by analyzing the nitrogen adsorption-desorption isotherm graph by the BJH method may be in the range of 0.001 to 0.030 cm³ /g.

Inventors

• 권해준
• 이경묵

Assignees

• (주)포스코퓨처엠

Dates

Publication Date

20260508

Application Date

20260331

Claims (10)

1. It includes a first graphite and a second graphite having an average particle size (D50) smaller than that of the first graphite, The pore volume calculated by interpreting the nitrogen adsorption-desorption isotherm graph using the BJH (Barrett-Joyner-Halenda) method is 0.001 to 0.030 cm³/g, and The tap density is 1.17 g/cm³ or less, and A negative electrode active material for a lithium secondary battery satisfying Formula 1 below: [Equation 1] 3.5 ≤ [D90]/[D10] ≤ 5.0 (In Equation 1 above, [D10] and [D90] represent the particle sizes corresponding to 10% and 90% of the cumulative volume of the cathode active material measured using the Laser Diffraction Method).
2. In paragraph 1, The average particle size (D50) of the first graphite is in the range of 13 μm to 17 μm, and A negative electrode active material for a lithium secondary battery, wherein the average particle size (D50) of the second graphite is in the range of 1 μm to 4 μm.
3. In paragraph 1, A negative electrode active material for a lithium secondary battery, wherein the content of the second graphite is 30 weight% or less based on the total negative electrode active material.
4. In paragraph 1, A negative electrode active material for a lithium secondary battery, wherein the BET (Brunauer-Emmett-Teller) specific surface area of the above negative electrode active material is 2.2 m²/g or more.
5. In paragraph 1, A negative electrode active material for a lithium secondary battery, wherein the degree of sphericity of the first graphite is 0.9 or higher.
6. In paragraph 1, The above-mentioned negative electrode active material further comprises amorphous carbon, and A negative electrode active material for a lithium secondary battery, wherein the content of the amorphous carbon is 1 to 15 weight% based on the total negative electrode active material.
7. A negative electrode for a lithium secondary battery comprising a negative electrode active material according to any one of claims 1 to 6.
8. A lithium secondary battery comprising a negative electrode for a lithium secondary battery according to claim 7.
9. Step of spheroidizing the first graphite; A step of preparing a mixture by mixing the spherical first graphite, a second graphite having an average particle size (D50) smaller than that of the first graphite, and a carbon precursor; A step of pressurizing the above mixture at a pressure of 120 to 330 MPa using a cold isostatic press; A step of heat-treating the above-mentioned pressurized mixture; and A step of grinding the above heat-treated mixture; A method for manufacturing a negative electrode active material for a lithium secondary battery, comprising
10. In Paragraph 9, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the pressure of the above-mentioned pressurizing step is 140 to 310 MPa.

Description

Anode active material for lithium secondary battery, manufacturing method of the same, and lithium secondary battery comprising the same The present embodiments relate to a negative electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same. Due to technological development and increasing demand for mobile devices, as well as the rapid rise of electric vehicles (EVs), the demand for lithium-ion batteries as an energy source for these devices is increasing rapidly. As the negative electrode active material for such lithium-ion secondary batteries, graphite-based materials such as synthetic graphite and natural graphite are generally used. These materials reversibly accept or supply lithium ions while maintaining structural and electrical properties, and possess chemical potential characteristics nearly similar to metallic lithium during lithium ion insertion and extraction. Artificial graphite has a higher charge-to-discharge efficiency than natural graphite and exhibits excellent lifespan characteristics due to less swelling during charging and discharging. However, it has a lower reversible capacity compared to natural graphite, and its hard grains make rolling difficult during electrode manufacturing. Additionally, it has the problem of poor orientation due to minimal shape change. In particular, it has the disadvantage of high manufacturing costs as it requires graphitization heat treatment at around 3,000°C. In contrast, natural graphite is widely used as a negative electrode active material because it is cheaper than synthetic graphite, has a high reversible capacity, and exhibits similar electrochemical properties. However, since natural graphite generally has a plate-like shape, it has a large surface area and exposed edges. Consequently, the penetration or decomposition of electrolytes causes the edges to peel off or break, leading to significant irreversible reactions and an increased expansion rate, which degrades long-term lifespan characteristics. To address this, a method using spherical natural graphite has been proposed; however, in this case, the increase in internal pores leads to longer lithium diffusion distances and larger particle sizes, resulting in a problem of reduced output characteristics when applied to batteries. Therefore, there is an urgent need to develop technology capable of realizing lithium secondary batteries with excellent long-term lifespan and output characteristics while using natural graphite. Figure 1 shows a graph of the capacity retention rate (50 cycles) of a half-cell manufactured using the negative active material prepared according to Example 1 and Comparative Example 1. Figure 2 shows a graph of the Coulomb efficiency (350 cycles) of a full cell manufactured using the negative electrode active material prepared according to Example 1 and Comparative Example 1. Figure 3 is an SEM image of the negative electrode active material prepared according to Example 1, magnified 1,000 times. Figure 4 is an SEM image of the negative electrode active material prepared according to Example 1, magnified 5,000 times. Figure 5 is an SEM image of the negative electrode active material prepared according to Example 1, magnified 10,000 times. Figure 6 is an SEM image of the negative electrode active material prepared according to Example 1, magnified 10,000 times. Figure 7 is an SEM image of the negative electrode active material prepared according to Comparative Example 1, magnified 10,000 times. Terms such as first, second, and third are used to describe various parts, components, regions, layers, and/or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the present invention. The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and/or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and/or components. When it is stated that one part is "above" or "on" another part, it may be directly above or on the other part, or other parts may be involved in between. In contrast, when it is stated that one part is "directly above" another part, no other parts are interposed in between. Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as gene