KR-102963782-B1 - NEGATIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY, METHOD FOR MANUFACTURING THE SAME, AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

KR102963782B1KR 102963782 B1KR102963782 B1KR 102963782B1KR-102963782-B1

Abstract

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, wherein the negative electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same can be provided, comprising: carbon-based particles having pores inside and/or on the surface; and a coating layer including a silicon-based material located on the pores and/or non-pore-free surface of the carbon-based particles, wherein the content of fine particles having a particle size of less than 1 μm among the total particles is 1 volume% or less.

Inventors

이지희
김준섭
김남형
이윤광
이태용
조재필

Assignees

에스케이온 주식회사
울산과학기술원

Dates

Publication Date: 20260513
Application Date: 20190716

Claims (17)

Carbon-based particles containing pores on the interior and/or surface; and A coating layer comprising a silicon-based material located on the pores and/or non-pore surface of the carbon-based particles; comprising, The content of fine powder having a particle size of less than 1㎛ among the total particles is 1 volume% or less, and A negative electrode active material for a lithium secondary battery satisfying the following Formula 1. [Equation 1] (D v 90 - D v 10) / D v 50 < 1.6 (In the above Equation 1, D v 90 represents the particle diameter (μm) at which the cumulative volume from the smallest particle size reaches 90% in the particle size distribution measurement by laser scattering for the cathode active material, D v 50 represents the particle diameter (μm) at which the cumulative volume from the smallest particle size reaches 50% in the particle size distribution measurement by laser scattering for the cathode active material, and D v 10 represents the particle diameter (μm) at which the cumulative volume from the smallest particle size reaches 10% in the particle size distribution measurement by laser scattering for the cathode active material.)
In Paragraph 1, A negative electrode active material for a lithium secondary battery having a fine particle content of 0.5 volume% or less of a particle size of less than 1㎛ among the total particles.
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In Paragraph 1, The above negative electrode active material for a lithium secondary battery is a negative electrode active material for a lithium secondary battery in which the increase rate of D v 50 after forming the coating layer compared to before forming the coating layer on the carbon-based particles is 50% or less. (The above D v 50 refers to the particle diameter at which the cumulative volume reaches 50% from the smallest particle size in the particle size distribution measurement of the above cathode active material by the laser scattering method.)
In Paragraph 4, The above negative electrode active material for a lithium secondary battery is a negative electrode active material for a lithium secondary battery in which the increase rate of D v 50 after forming the coating layer compared to before forming the coating layer on the carbon-based particles is 20% or less. (The above D v 50 refers to the particle diameter at which the cumulative volume reaches 50% from the smallest particle size in the particle size distribution measurement of the above cathode active material by the laser scattering method.)
In Paragraph 1, Negative electrode active material for a lithium secondary battery having a tab density of 0.700 g/cm³ or less .
In Paragraph 1, The above carbon-based particles are negative electrode active materials for lithium secondary batteries containing pores inside and on the surface.
In Paragraph 1, A negative electrode active material for a lithium secondary battery having an average pore diameter of the carbon-based particles of the above-mentioned carbon-based particles of 30 nm or more and 900 nm or less.
In Paragraph 1, A negative electrode active material for a lithium secondary battery, wherein the coating layer containing the above silicon-based material is formed by chemical vapor deposition (CVD).
In Paragraph 1, A negative electrode active material for a lithium secondary battery further comprising a carbon coating layer located on a coating layer comprising the above silicon-based material.
(a) a step of introducing carbonaceous material and pore-forming ceramic particles into a stirrer; (b) a step of preparing a precursor in which ceramic particles for forming pores are dispersed within the matrix of the carbon-based material by dry stirring in the above-mentioned stirrer; (c) a step of calcining the above precursor; (d) mixing a pore-forming ceramic particle etching solution with the above-described calcined precursor to obtain porous carbon-based particles having pores inside and/or on the surface; and (e) a step of forming a coating layer containing a silicon-based material on the porous carbon-based particles; comprising, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein grinding is not performed in the entire process described above.
In Paragraph 11, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the above-mentioned stirrer is a blade mixer having a gap between the blade and the stirring cylinder.
In Paragraph 11, The above step (e) is a method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the coating layer containing a silicon-based material is formed by chemical vapor deposition under an inert atmosphere.
In Paragraph 11, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the average particle size of the pore-forming ceramic particles is 30 nm or more and 900 nm or less.
In Paragraph 11, A method for manufacturing a negative electrode active material for a lithium secondary battery, wherein the calcination temperature of step (c) above is 600°C or higher and 1000°C or lower.
In Paragraph 11, A method for manufacturing a negative electrode active material for a lithium secondary battery, comprising, after step (e) above, a step (f) of mixing and stirring a carbon-based material and then calcining.
A lithium secondary battery comprising the negative electrode active material of claim 1.

Description

Negative electrode active material for lithium secondary battery, method for manufacturing the same, and lithium secondary battery comprising 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, a method for manufacturing the same, and a 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, as regulations regarding fuel efficiency and exhaust emissions become stricter globally, 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, carbon-based anode materials with excellent cycle characteristics and a theoretical capacity of 372 mAh/g have been generally used as anode materials for secondary batteries. However, as the demand for higher capacity in secondary batteries, such as medium and large-sized secondary batteries, increases, inorganic anode materials such as silicon (Si), germanium (Ge), tin (Sn), or antimony (Sb), which have a capacity of 500 mAh/g or more and can replace the theoretical capacity of carbon-based anode materials, are attracting attention. Among these inorganic cathode materials, silicon-based cathode materials exhibit a very large lithium binding capacity. However, silicon-based cathode materials can undergo pulverization due to significant volume changes during lithium insertion/extraction, i.e., battery charging and discharging. As a result, pulverized particles may aggregate, causing the cathode active material to electrically detach from the current collector, which can lead to a loss of reversible capacity over long cycles. For this reason, despite the advantages of high charge capacity, silicon-based cathode materials and secondary batteries containing them face barriers to practical application due to disadvantages such as low cycle life characteristics and capacity retention rates. To address the problems associated with silicon-based anode materials, research on silicon-based composite anode materials, such as carbon/silicon composites, is actively underway. However, these composite anode materials also exhibit increasingly severe volume expansion during the charging and discharging of secondary batteries as the silicon content increases. Consequently, new silicon surfaces within the composite anode material are continuously exposed to the electrolyte, constantly generating a solid electrolyte interface (SEI) layer to form a thick by-reaction layer, leading to electrolyte depletion and increased battery resistance. Furthermore, this thick by-reaction layer affects not only silicon but also graphite, causing electrical short circuits (peel-off) between anode active material particles or from the current collector, which drastically degrades the performance of the secondary battery, including cycle life characteristics. In addition, in the case of silicon/carbon composite materials, if the amount of fine particles in the corresponding cathode material is high and the particle size distribution is uneven, particle aggregation centered on fine or coarse particles may occur. If such aggregation occurs, a problem may arise where silicon detaches from carbon and is exposed to the electrolyte during the battery's charging and discharging process. Consequently, excessive side reactions with the electrolyte may occur, leading to lithium depletion and increased electrical resistance, which can result in a decrease in battery lifespan. FIG. 1 is a schematic diagram of a blade mixer used to manufacture a cathode active material of one embodiment of the present invention. Figure 2 is a scanning electron microscope image of carbon-based particles prepared in Example 1 of the present invention. Figure 3 is a scanning electron microscope image of carbon-based particles prepared in Comparative Example 1 of the present invention. Figure 4 is a scanning electron microscope image of a cross-section of the negative electrode active material prepared in Example 1 of the present invention after 100 charge-discharge cycles. Figure 5 is a scanning electron microscope image of a cross-section of the negative electrode active material prepared in Comparative Example 1 of the present invention after 100 charge-discharge cycles. 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 pertains. Additionally, the singular form i