JP-2026514233-A - Negative electrode active material for lithium secondary batteries, method for manufacturing the same, and lithium secondary battery containing the same

Abstract

This invention relates to a negative electrode active material for lithium secondary batteries, comprising natural graphite, wherein the natural graphite satisfies formula 1.

Inventors

• イ、 キュンムク
• ジュン、 ジクォン
• イ、 ガウル
• カン、 ス ヒ
• ジュン、 ス ヨン
• イ、 ホン ヤン
• シン、 ミュンス
• イ、 セ ヒュン
• クォン、 ヘジュン
• アン、 キホン
• キム、 スミン

Assignees

• ポスコヒューチャーエム株式会社

Dates

Publication Date

20260507

Application Date

20240523

Priority Date

20230531

Claims (17)

1. Contains natural graphite, The aforementioned natural graphite is a negative electrode active material for lithium secondary batteries that satisfies the following formula 1. [Formula 1] 0.04g/cm 3 ≦D press -D tap ≦0.085g/cm 3 In the above equation 1, D press is the compressive density of natural graphite at an applied pressure of 5.5 kgf/ cm² , and D tap is the tap density of natural graphite.
2. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the pH of the natural graphite is 7.0 or higher.
3. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the natural graphite surface does not contain a low-crystallinity carbon material-containing coating layer.
4. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the BET specific surface area of the natural graphite is 4.8 m² /g or more.
5. The oil absorption capacity of the natural graphite is 50.0 mL/100 g or more, as described in claim 1, for the negative electrode active material for a lithium secondary battery.
6. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the average particle size D50 of the natural graphite is 16.0 to 21.0 μm.
7. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the tap density of the natural graphite is 0.95 g/ cm³ or less.
8. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the degree of spheroidization of the natural graphite is 0.85 or higher.
9. The negative electrode active material for a lithium secondary battery according to claim 1, further comprising a silicon-based active material.
10. The silicon-based active material is silicon, a silicon-carbon composite, a silicon oxide, or a combination thereof, as described in claim 9, for a negative electrode active material for a lithium secondary battery.
11. The process includes the steps of preparing natural graphite powder and heat-treating the natural graphite powder at a temperature of 500 to 650°C in an inert gas atmosphere. A method for producing a negative electrode active material for lithium secondary batteries.
12. The method for producing a negative electrode active material for a lithium secondary battery according to claim 11, wherein the inert gas is nitrogen.
13. The method for producing a negative electrode active material for a lithium secondary battery according to claim 11, wherein the heat treatment is performed for 1 to 12 hours.
14. After the heat treatment step, A method for producing a negative electrode active material for a lithium secondary battery according to claim 11, further comprising the step of mixing a silicon-based active material.
15. The method for producing a negative electrode active material for a lithium secondary battery according to claim 11, wherein the silicon-based active material is silicon, a silicon-carbon composite, a silicon oxide, or a combination thereof.
16. A negative electrode for a lithium secondary battery, comprising the negative electrode active material described in any one of claims 1 to 10.
17. A lithium secondary battery comprising the negative electrode for a lithium secondary battery as described in claim 16.

Description

This invention relates to a negative electrode active material for lithium secondary batteries, a method for producing the same, and a lithium secondary battery containing the same. As technological development and demand for mobile devices increase, the demand for rechargeable, miniaturized, and high-capacity secondary batteries is rapidly growing. Recently, the use of secondary batteries as power sources for hybrid electric vehicles (HEVs) and electric vehicles (EVs) has become a reality. As a result, much research is being conducted on secondary batteries that can meet diverse requirements, and in particular, there is a growing demand for lithium secondary batteries with high energy density, high discharge voltage, and high output. Furthermore, lithium secondary batteries used in electric vehicles and other applications must not only possess high energy density and the ability to deliver high output in a short time, but also be used for more than 10 years under harsh conditions involving repeated high-current charging and discharging in short periods. Therefore, they inevitably require significantly superior output characteristics and long-life characteristics compared to existing small lithium secondary batteries. In particular, with the increasing demand for high-density energy batteries, research is actively progressing 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 more than 10 times the capacity of graphite-based materials. However, while high-capacity silicon-based materials have superior capacity characteristics compared to existing graphite, they suffer from a problem where their volume rapidly expands during the charging process, disrupting the conductive path, degrading battery performance, and consequently worsening the battery's lifespan. Therefore, research is needed on mixed negative electrode active materials of graphite and silicon-based materials that can appropriately ensure both battery capacity and lifespan characteristics. The terms "first," "second," and "third," etc., are used to describe various parts, components, regions, layers, and/or sections, but are not limited to these. These terms are used solely to distinguish one part, component, region, layer, or section from other parts, components, regions, layers, or sections. Therefore, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section, within the scope of the present invention. The technical terms used herein are solely for the purpose of referring to specific embodiments and are not intended to limit the invention. The singular forms used herein also include plural forms unless the text explicitly indicates otherwise. The meaning of "includes" as used in this specification does not mean to embody a particular characteristic, area, integer, step, operation, element, and/or component, thereby excluding the presence or addition of other characteristics, areas, integers, steps, operations, elements, and/or components. When one part is described as being "on top of" another part, it means either directly on top of the other part or with the other part in between. In contrast, when one part is described as being "directly on top of" another part, there is no other part in between. While not defined differently, all terms used herein, including technical and scientific terms, have the same meaning as those generally understood by a person of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries are additionally interpreted as having the meaning consistent with the relevant technical literature and the present disclosure, and are not interpreted in their ideal or highly formal sense unless otherwise defined. Furthermore, unless otherwise specified, % refers to weight percentage, and 1 ppm is equal to 0.0001 weight percentage. In this specification, the term “these combinations” as used in maxi-form expressions means one or more mixtures or combinations selected from the group of components described in the maxi-form expressions, and includes one or more of the components selected from the group of said components. The embodiments of the present invention will be described in detail below so that they can be easily implemented by a person with ordinary skill in the art to which the invention pertains. However, the present invention can be realized in various different forms and is not limited to the embodiments described herein. 1. Anode Active Materials Recently, as the development of lithium-ion secondary batteries for electric vehicles accelerates, the demand for high energy density is increasing. Therefore, research is actively underway on methods to increase capacity by mixing silicon-based active materials such as Si, Si-C composites, and SiOx, which have a capacity more than 10 times g