KR-102962455-B1 - High-capacity silicon-based anode material derived from meltable polyacrylonitrile and manufacturing method thereof

KR102962455B1KR 102962455 B1KR102962455 B1KR 102962455B1KR-102962455-B1

Abstract

The present invention relates to a silicon-carbon composite cathode material and a method for manufacturing the same. A method for manufacturing a silicon-carbon composite cathode material according to the present invention comprises: S1) a step of preparing a meltable acrylonitrile-based polymer by mixing an initiator, a chain transfer agent, and a solvent with a monomer mixture in which an acrylonitrile monomer and a comonomer are mixed; S2) a step of obtaining a composite particle by coating the meltable acrylonitrile-based polymer onto a silicon-based particle; S3) a step of stabilizing the composite particle; and S4) a step of carbonizing the stabilized composite particle.

Inventors

임창하
길현식
최선호
오경애
김홍민
이대우
천단비
김우정

Assignees

주식회사 씨피에스

Dates

Publication Date: 20260508
Application Date: 20231228

Claims (9)

S1) A step of preparing a meltable acrylonitrile-based polymer by mixing an initiator, a chain transfer agent, and a solvent into a monomer mixture in which an acrylonitrile monomer and a comonomer are mixed; S2) A step of obtaining composite particles by coating the meltable acrylonitrile-based polymer onto silicon-based particles; S3) A step of stabilizing the above composite particles; and S4) A step of carbonizing the stabilized composite particles; comprising a method for manufacturing a silicon-carbon composite cathode material.
In paragraph 1, A method for manufacturing a silicon-carbon composite cathode material, wherein, in step S1) above, the comonomer is one or more compounds selected from the group consisting of methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, and itaconic acid.
In paragraph 1, The above comonomers are methyl acrylate and itaconic acid, and A method for manufacturing a silicon-carbon composite cathode material, wherein in step S1) above, the monomer mixture has a molar ratio of acrylonitrile monomer : methyl acrylate : itaconic acid of 90~95 : 4.5~9.0 : 0.3~1.0.
In paragraph 1, A method for manufacturing a silicon-carbon composite cathode material, wherein the meltable acrylonitrile-based polymer has a weight average molecular weight of 100,000 g/mol to 300,000 g/mol.
In paragraph 1, A method for manufacturing a silicon-carbon composite cathode material, wherein in step S2) above, the coating is performed by mixing 50 to 200 parts by weight of the meltable acrylonitrile-based polymer with 100 parts by weight of the silicon-based particles.
In paragraph 1, The stabilization of the above S3) step is, A method for manufacturing a silicon-carbon composite cathode material, wherein the heating is increased at at least one heating rate and the process is carried out at a temperature of less than 500°C.
In paragraph 6, The stabilization of the above S3) step is, S3-a) A first heating step in which the temperature is increased at a heating rate of 5 to 15℃/min; and S3-b) A second heating step in which the temperature is raised at a heating rate of less than 5℃/min; comprising a method for manufacturing a silicon-carbon composite cathode material.
In paragraph 1, The carbonization in step S4) above is A method for manufacturing a silicon-carbon composite cathode material, performed under temperature conditions of 1000℃ or lower.
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Description

High-capacity silicon-based anode material derived from meltable polyacrylonitrile and manufacturing method thereof The present invention relates to a silicon-carbon composite cathode material and a method for manufacturing the same. Rechargeable batteries are batteries capable of repeated charging and discharging, and demand for them as power sources for mobile devices or electric vehicles has recently increased significantly. While rechargeable batteries include lithium, nickel-cadmium, and nickel-hydrogen batteries, lithium-ion batteries—such as lithium batteries, lithium-ion batteries, and lithium-ion polymer batteries—are attracting attention due to their advantages, such as high operating voltage, high energy density per unit weight, charging speed, and lightweight design. Specifically, a lithium-ion secondary battery is a battery that can be recharged and reused by generating electricity through a chemical reaction in which lithium ions move between a positive electrode and a negative electrode. The four core technologies of a lithium-ion secondary battery consist of a positive electrode material, a negative electrode material, an electrolyte that acts as a pathway for lithium ions to move between the positive and negative electrodes, and a separator that does not participate in the electrochemical reaction but prevents physical contact between the positive and negative electrodes. Among these, active research is being conducted on silicon-based anode materials, which possess high energy density per unit volume and fast charging speeds. However, silicon-based anode materials expand and contract in volume during the charging and discharging process of secondary batteries, which can lead to electrical detachment from the current collector and result in a loss of reversible capacity. Consequently, despite the advantages of high charge capacity, silicon-based anode materials and secondary batteries containing them exhibit low cycle life characteristics and low capacity retention rates, which act as barriers to practical application. As a result, research on silicon-based composite cathode materials is actively underway, such as by combining silicon with carbon-based materials like carbon matrices, as disclosed in Korean Patent Publication No. 10-2022-0137528. However, in these conventional composite cathode materials, the carbon matrix is easily damaged due to volume changes of silicon particles embedded in the carbon matrix. Furthermore, the composite cathode material cannot contain a high amount of silicon because it is difficult to uniformly disperse the silicon particles. Accordingly, there is a need to develop anode material technology that contains a large amount of silicon, mitigates the volume expansion of silicon caused by charging and discharging of secondary batteries, and possesses excellent cycle characteristics and high capacity. Figure 1 is a graph of the charge-discharge cycle of a battery using a negative electrode material according to one embodiment of the present invention. Unless otherwise defined, technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art to which this invention pertains, and descriptions of known functions and configurations that could unnecessarily obscure the essence of the invention are omitted in the following description and accompanying drawings. Additionally, the singular form used in this specification may be intended to include the plural form unless specifically indicated otherwise in the context. Additionally, units used herein without special reference are based on weight, and, for example, units of % or ratio mean weight % or mass ratio, and weight % means the weight % of any one component of the total composition within the composition unless otherwise defined. Additionally, numerical ranges used herein include lower and upper limits and all values within the range, increments logically derived from the form and width of the defined range, all of which are limited values, and all possible combinations of upper and lower limits of numerical ranges defined in different forms. Unless otherwise specifically defined in this specification, values outside the numerical range that may occur due to experimental error or rounding are also included in the defined numerical range. The term "comprising" in this specification is an open description having an equivalent meaning to expressions such as "comprising," "containing," "having," or "characterizing," and does not exclude elements, materials, or processes not additionally listed. In this specification and the appended claims, when a part such as a film (layer), region, or component is described as being above or on another part, it includes not only cases where it is directly above in contact with the other part, but also cases where another film (layer), other region, or other component is interposed therein. A method for manufacturing a silico