KR-20260064647-A - negative electrode active material for lithium secondary battery, method of preparing the same and lithium secondary battery including the same

KR20260064647AKR 20260064647 AKR20260064647 AKR 20260064647AKR-20260064647-A

Abstract

The present invention provides a negative electrode active material for a lithium secondary battery comprising: a plurality of silicon-based primary particles and silicon-based secondary particles aggregated with amorphous carbon; a metal fluoride distributed in the pores and/or surface of the silicon-based secondary particles; and a coating layer containing carbon nanotubes (CNT) surrounding at least a portion of the surface of the secondary particles.

Inventors

이총민
서유경
채태성
전민영
이동욱

Assignees

주식회사 에코프로비엠

Dates

Publication Date: 20260507
Application Date: 20251031
Priority Date: 20241031

Claims (17)

Multiple silicon-based primary particles and silicon-based secondary particles aggregated with amorphous carbon; Metal fluoride distributed in the pores and/or surface of the above silicon-based secondary particles; and A negative electrode active material for a lithium secondary battery, comprising a coating layer containing carbon nanotubes (CNT) that surrounds at least a portion of the surface of the secondary particle.
In paragraph 1, The above silicon-based secondary particles have an average particle size (D50) of 5 to 20 μm and a spherical shape with a degree of sphericity of 0.80 or higher, and are negative electrode active materials for a lithium secondary battery.
In paragraph 1, The above silicon-based secondary particles are, The above silicon-based primary particles (C1) and amorphous carbon (C2) are included in a weight ratio (C1:C2) of 65:35 to 95:5, A negative electrode active material for a lithium secondary battery comprising the above silicon-based primary particle (C1) and metal fluoride (C3) in a weight ratio (C1:C3) of 99:1 to 70:30.
In paragraph 1, The above-mentioned fluoride metal comprises an alkali metal fluoride or an alkaline earth metal fluoride, and is a negative electrode active material for a lithium secondary battery.
In paragraph 1, The carbon nanotubes (CNT) included in the above coating layer have an average aspect ratio of 100 or more, and The average aspect ratio of the carbon nanotubes (CNT) above refers to the ratio of the average length (L) to the average particle diameter (D) (L/D) based on at least 100 carbon nanotubes (CNT), a negative electrode active material for a lithium secondary battery.
In paragraph 1, A negative electrode active material for a lithium secondary battery, wherein carbon nanotubes (CNTs) included in the coating layer are grown using the fluoride metal as a catalyst, such that one end of the carbon nanotubes (CNTs) is located on the surface of the silicon-based secondary particle and the other end of the carbon nanotubes (CNTs) is located outside the surface of the particle.
In paragraph 1, A negative electrode active material for a lithium secondary battery having a peak intensity ratio (ID/IG) of 0.8 to 1.15 based on Raman spectrum analysis. (The above peak intensity IG refers to the peak intensity (IG) near 1580 cm⁻¹ in the Raman spectrum analysis, and peak intensity ID refers to the peak intensity near 1360 cm⁻¹ .)
In paragraph 1, The silicon-based secondary particles having the above coating layer formed thereon have a BET specific surface area (S2) of 0.1 to 2.0 m² /g, and are negative electrode active materials for lithium secondary batteries.
In paragraph 1, The above coating layer is a negative electrode active material for a lithium secondary battery, wherein the plurality of carbon nanotubes (CNTs) are formed in a mesh structure and/or a three-dimensional network structure and surround the surface of the silicon-based secondary particle.
In paragraph 1, The above negative electrode active material is a negative electrode active material for a lithium secondary battery, wherein, according to SEM-EDS analysis, the silicon (Si) atomic concentration on the surface portion of the negative electrode active material particles is 5 to 65 at% and the carbon (C) atomic concentration is 35 to 95 at%.
In paragraph 1, The above negative electrode active material is a negative electrode active material for a lithium secondary battery having an electrical conductivity (S/cm) of the order of 10⁰ to the order of 10¹ .
A spheroidization step for manufacturing silicon-based secondary particles aggregated from a plurality of silicon-based primary particles, metal fluoride, and amorphous carbon; A step of calcining at a temperature above the melting point of the above-mentioned fluoride metal; and A method for manufacturing a negative electrode active material for a lithium secondary battery, comprising: a step of forming a coating layer comprising carbon nanotubes (CNTs) grown using the fluoride metal as a catalyst on at least a portion of the surface of the silicon-based secondary particles.
In Paragraph 12, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the above spheroidizing step is performed by spheroidizing using a mechano fusion method so that the average particle size (D50) of the silicon-based secondary particles is 13 to 22 μm.
In Paragraph 12, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the above calcination step is heat-treated at 900 to 1,500°C in an inert gas atmosphere for 1 to 20 hours, so that the fluoride metal is melted and distributed in the pores and/or surface of the silicon-based secondary particles.
In Paragraph 12, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the step of forming the coating layer involves growing carbon nanotubes (CNT) on at least a portion of the surface of the silicon-based secondary particles by a chemical vapor deposition (CVD) method.
A negative electrode for a lithium secondary battery comprising a negative electrode active material according to claim 1.
A lithium secondary battery comprising a negative electrode according to paragraph 16.

Description

Negative electrode active material for lithium secondary battery, method of preparing the same and lithium secondary battery including the same The present invention relates 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. With the recent increase in demand for electronic devices, including mobile phones, technological development for these devices is expanding. Consequently, the demand for lithium-ion batteries, such as lithium batteries, lithium-ion batteries, and lithium-ion polymer batteries, is rising significantly as power sources for these electronic devices. Furthermore, driven by the global trend of tightening regulations on vehicle fuel efficiency and exhaust emissions, the growth of the electric vehicle (EV) market is accelerating. Along with this, demand for medium- and large-sized secondary batteries, such as those for EVs and Energy Storage Systems (ESS), is expected to surge. Meanwhile, as the demand for higher capacity in secondary batteries, such as medium and large-sized batteries, has recently increased, silicon-based anode materials with excellent theoretical capacity are being researched as anode materials for secondary batteries. However, silicon-based anode materials cause significant volume changes during lithium insertion and extraction, leading to electrical delamination due to silicon particle pulverization and reversible capacity loss under repeated cycles. Conventionally, to solve this problem, methods have been attempted to use additional conductive materials or various conductive materials such as carbon nanotubes (CNT). The method of using additional conductive materials presents a problem where aggregation occurs between the materials as the content increases. When using carbon nanotubes (CNTs) in combination with carbon-based materials as the negative electrode active material, this serves as an alternative to solve the problem due to the excellent conductivity and mechanical properties of CNTs; however, since CNTs are distributed across the entire electrode rather than existing only on the silicon, there was a problem where the efficiency of electrical conductivity improvement was reduced. Figure 1 is a surface SEM image of the negative electrode active material (CNT-coated silicon-based secondary particle) prepared in Comparative Example 1 and Examples 1 to 3. Figure 2 shows the results of particle cross-section SEM-EDS mapping analysis for (a) before firing (assemblage spherical precursor of the spheroidization stage) and (b) after firing (assemblage spherical silicon-based secondary particles) in the firing stage of Example 1. Figure 3 shows the surface SEM-EDS analysis results of the negative electrode active materials (CNT-coated silicon-based secondary particles) prepared in Comparative Example 1 and Examples 1 to 3. Figure 4 shows the results of Raman spectrum analysis of the cathode active materials (CNT-coated silicon-based secondary particles) prepared in Comparative Example 1 and Examples 1 to 3. The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning that is commonly understood by those skilled in the art to which the present invention belongs. When a part of a specification is described as "including" a certain component, unless specifically stated otherwise, this means that it does not exclude other components but may include additional components. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. In this specification, "A to B" means "A or more and B or less" unless specifically defined otherwise. Additionally, "A and/or B" means at least one selected from the group consisting of A and B, unless specifically defined otherwise. Additionally, when a part such as a layer, film, region, plate, etc. is described in this specification as being “on” or “on” another part, this includes not only cases where it is “immediately on” another part, but also cases where there is another part in between. One embodiment of the present invention provides a negative electrode active material for a lithium secondary battery, comprising: a plurality of silicon-based primary particles and silicon-based secondary particles aggregated with amorphous carbon