Silicon-carbon composite, preparation method therefor, and anode and lithium secondary battery comprising same

Abstract

The present invention relates to a silicon-carbon composite, a preparation method therefor, and an anode and a lithium secondary battery comprising same, the silicon-carbon composite comprising: porous activated carbon having a Span value of 5 or less; and silicon nanoparticles present on the outer surface of the inside of pores and / or the surface of particles of the porous activated carbon, wherein the average particle diameter (D50) of the porous activated carbon according to volume cumulative distribution measured using a laser diffraction particle size analyzer is 3-10 μm, the average pore size of the porous activated carbon, measured through BET analysis, is 1.5-2.5 nm, and the BET specific surface area of the porous activated carbon is 1,000 m2 / g to 2,500 m2 / g.

Description

Silicon-carbon composite, method for manufacturing the same, and a negative electrode and a lithium secondary battery including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0037281 filed on March 24, 2025, and all contents disclosed in the document of said Korean Patent Application are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present invention relates to a silicon-carbon composite, a method for manufacturing the same, a negative electrode comprising the same, and a lithium secondary battery.

[0005]

[0006] Recently, as the application areas of lithium-ion batteries have rapidly expanded to include not only power supply for electronic devices such as electrical, electronic, telecommunications, and computers, but also power storage for large-area devices such as automobiles and power storage systems, there is a growing demand for lithium-ion batteries that are high-capacity, high-output, and highly stable.

[0007] A lithium secondary battery is generally manufactured by applying a negative electrode active material capable of absorbing and releasing lithium ions or a positive electrode active material capable of inserting and extracting lithium ions, and optionally a material mixed with a binder and a conductive material, to a negative electrode current collector and a positive electrode current collector, respectively, to produce a negative electrode and a positive electrode, stacking these on both sides of a separator to form an electrode current collector of a predetermined shape, and then inserting this electrode current collector and a non-aqueous electrolyte into a battery case.

[0008] While carbon-based anode active materials are generally used, research is continuing to use materials with higher capacity as the demand for high-capacity and high-output lithium-ion batteries increases, and among these, research on silicon-based anode active materials is actively underway. Silicon-based anode active materials have a lithium capacity more than 10 times greater than that of carbon, and are emerging as next-generation anode active materials.

[0009] However, the aforementioned silicon-based negative electrode active materials have the problem of being difficult to use universally due to volume expansion during charging and discharging, resulting cracking or damage to active material particles, and consequently, degradation of lifespan characteristics. In particular, among the silicon-based negative electrode active materials, silicon oxide (SiOx) has good lifespan characteristics and possesses a higher charge / discharge capacity compared to carbon-based negative electrode active materials; however, it has the problem of poor initial efficiency due to the formation of an irreversible phase of lithium-silicon oxide during the lithium charging and discharging process.

[0010] Accordingly, silicon-carbon composites that do not form irreversible phases during the charging and discharging process of lithium are attracting attention as next-generation anode materials. However, although anode active materials containing silicon-carbon composites synthesized by combining silicon particles with carbon materials such as graphite and coke have improved lifespan characteristics and increased electrical conductivity compared to conventional silicon, they remain difficult to apply in technological fields requiring long lifespan characteristics, such as electric vehicles and energy storage systems (ESS).

[0011] Therefore, there is a need to develop next-generation cathode materials that possess excellent initial capacity and lifetime characteristics, making them suitable for general use even in cases where long lifespan characteristics are required.

[0012]

[0013] The present invention aims to provide a silicon-carbon composite having high charge / discharge capacity and long lifespan characteristics by using porous activated carbon having a uniform particle size.

[0014] In addition, the present invention aims to provide a method for manufacturing the silicon-carbon composite.

[0015] In addition, the present invention aims to provide a negative electrode and a lithium secondary battery comprising the silicon-carbon composite.

[0016]

[0017] 1. The present invention comprises a porous activated carbon having a Span value of 5 or less calculated by the following Formula 1; and silicon nanoparticles present on at least one of the pore interior and particle surface of the porous activated carbon, and the average particle size (D) of the porous activated carbon according to the volume cumulative distribution measured using a laser diffraction particle size analyzer. 50 ) is 3 μm or more and 10 μm or less, the average pore size of the porous activated carbon measured by BET analysis is 1.5 nm or more and 2.5 nm or less, and the BET specific surface area of ​​the porous activated carbon is 1,000 m² 2 / g or more, 2,500 m 2 Provides a silicon-carbon composite having a g or less.

[0018] [Equation 1]

[0019] Span=(D 90 -D 10 ) / D 50

[0020] In the above Equation 1,

[0021] D 90 is the particle size at the 90% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and

[0022] D 10 is the particle size at the 10% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and

[0023] D 50 is the particle size at the 50% point of the volume cumulative distribution according to the particle size of the porous activated carbon particles.

[0024] 2. The present invention provides a silicon-carbon composite according to 1. above, wherein the silicon is included in an amount of 30% or more and 70% or less with respect to the total content of the silicon-carbon composite.

[0025] 3. The present invention provides a silicon-carbon composite according to 1. or 2. above, wherein the average particle size of the silicon nanoparticles is 0.5 nm or more and 2.5 nm or less.

[0026] 4. The present invention provides a silicon-carbon composite in any one of 1 to 3 above, wherein the porous activated carbon has a Span value of 1 or more and 5 or less.

[0027] 5. In any one of 1 to 4 above, the present invention is characterized in that the average particle size (D) of the porous activated carbon 50 ) provides a silicon-carbon composite having a thickness of 5 μm or more and 10 μm or less.

[0028] 6. The present invention provides a silicon-carbon composite in any one of 1 to 5 above, wherein the porous activated carbon has an average pore size of 1.5 nm or more and 2.1 nm or less as measured by BET analysis.

[0029] 7. In any one of 1 to 6 above, the present invention is such that the porous activated carbon has a BET specific surface area of ​​1,500 m² 2 / g or more, 2,200 m 2 Provides a silicon-carbon composite having a g or less.

[0030] 8. The present invention provides a method for manufacturing a silicon-carbon composite according to any one of 1 to 7 above, comprising the step of depositing silicon on at least one of the pore interior and particle surface of porous activated carbon.

[0031] 9. The present invention provides a method for manufacturing a silicon-carbon composite according to 8. above, wherein the silicon is deposited using a chemical vapor deposition process.

[0032] 10. The present invention provides a method for manufacturing a silicon-carbon composite according to 8. or 9. above, wherein the silicon is deposited at a temperature of 350 ℃ to 550 ℃.

[0033] 11. The present invention provides a cathode comprising a silicon-carbon composite according to any one of 1 to 7 above.

[0034] 12. The present invention provides a lithium secondary battery comprising a negative electrode according to 11. above.

[0035] 13. The present invention relates to a porous activated carbon having a Span value of 5 or less calculated by the following Equation 1, wherein the average particle size (D) of the porous activated carbon according to the cumulative volume distribution measured using a laser diffraction particle size analyzer 50 ) is 3 μm or more and 10 μm or less, the average pore size of the porous activated carbon measured by BET analysis is 1.5 nm or more and 2.5 nm or less, and the BET specific surface area of ​​the porous activated carbon is 1,000 m² 2 / g or more, 2,500 m 2 Provides porous activated carbon with a content of / g or less.

[0036] [Equation 1]

[0037] Span=(D 90 -D 10 ) / D 50

[0038] In the above Equation 1,

[0039] D 90 is the particle size at the 90% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and

[0040] D 10 is the particle size at the 10% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and

[0041] D 50 is the particle size at the 50% point of the volume cumulative distribution according to the particle size of the porous activated carbon particles.

[0042] 14. The present invention provides a porous activated carbon according to 13. above, wherein the Span value is 1 or more and 5 or less.

[0043] 15. The present invention, in accordance with 13 or 14 above, wherein the average particle size (D) of the porous activated carbon 50 ) provides porous activated carbon having a size of 5 μm or more and 10 μm or less.

[0044] 16. The present invention provides a porous activated carbon in which, in any one of 13 to 15 above, the average pore size of the porous activated carbon measured by BET analysis is 1.5 nm or more and 2.1 nm or less.

[0045] 17. The present invention, in any one of 13 to 16 above, wherein the BET specific surface area is 1,500 m² 2 / g or more, 2,200 m 2 Provides porous activated carbon with a content of / g or less.

[0046]

[0047] The silicon-carbon composite of the present invention comprises porous activated carbon with uniform particle size and silicon deposited thereon, thereby depositing silicon within the pores of the porous activated carbon having a high specific surface area, which can improve the initial capacity and lifespan characteristics of a lithium secondary battery.

[0048] In addition, the method for manufacturing a silicon-carbon composite of the present invention can produce a silicon-carbon composite having a uniform particle size without a separate activation process or classification process.

[0049] In addition, the lithium secondary battery of the present invention includes a negative electrode comprising a silicon-carbon composite according to the present invention, thereby having excellent initial capacity and lifespan characteristics.

[0050]

[0051] Hereinafter, the present invention will be described in more detail to aid in understanding the invention.

[0052] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0053]

[0054] silicon-carbon composite

[0055] The present invention comprises a porous activated carbon having a Span value of 5 or less calculated by the following Formula 1; and silicon nanoparticles present on at least one of the pore interior and particle surface of the porous activated carbon, and an average particle size (D) of the porous activated carbon according to the cumulative volume distribution measured using a laser diffraction particle size analyzer. 50 ) is 3 μm or more and 10 μm or less, the average pore size of the porous activated carbon measured by BET analysis is 1.5 nm or more and 2.5 nm or less, and the BET specific surface area of ​​the porous activated carbon is 1,000 m² 2 / g or more, 2,500 m 2 Provides a silicon-carbon composite having a g or less.

[0056] [Equation 1]

[0057] Span=(D 90 -D 10 ) / D 50

[0058] In the above Equation 1,

[0059] D 90 is the particle size at the 90% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and

[0060] D 10 is the particle size at the 10% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and

[0061] D 50is the particle size at the 50% point of the volume cumulative distribution according to the particle size of the porous activated carbon particles.

[0062] According to conventional methods for manufacturing silicon-carbon composites, a classification process is required to remove fine particles and large carbon bodies generated during the grinding process of porous activated carbon. If porous activated carbon with non-uniform particle size is used without undergoing this classification process, the amount of silicon deposited on at least one of the pores and the outer surface of the particles may differ, and the silicon-carbon composite manufactured in this way is not advantageous for battery performance. However, if the particle size of the porous activated carbon is uniform from the beginning, the grinding and classification processes mentioned above do not need to be performed, which can help reduce costs and improve battery performance.

[0063] To solve the above problem, the present invention synthesizes a polymer with uniform particle size, then manufactures porous activated carbon through carbonization and activation processes, and manufactures a silicon-carbon composite by depositing silicon on the manufactured porous activated carbon with uniform particle size.

[0064] According to one embodiment of the present invention, the Span value corresponding to the particle size uniformity of the porous activated carbon calculated by Equation 1 is 5 or less, and more specifically, the Span value of the porous activated carbon is 5.0 or less, 4.9 or less, 4.8 or less, 4.7 or less, 4.6 or less, 4.5 or less, 4.4 or less, 4.3 or less, 4.2 or less, 4.1 or less, 4.0 or less, 3.9 or less, 3.8 or less, 3.7 or less, 3.6 or less, 3.5 or less, 3.4 or less, 3.3 or less, 3.2 or less, 3.1 or less, 3.0 or less, 2.9 or less, 2.8 or less, 2.7 or less, 2.6 or less, 2.5 or less, 2.4 or less, 2.3 or less, 2.2 or less, 2.1 or less, 2.0 or less, 1.9 or less, 1.8 or less. It may be 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, or 1.1 or less, and additionally, the lower limit is not specifically restricted but may be 0.0 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, or 1.0 or more. If the Span value is greater than 5, the particle size distribution widens, resulting in non-uniform particle size of the porous activated carbon. When using porous activated carbon with such non-uniform particle size, the surface area and pore structure vary depending on the particle size, so silicon is not uniformly deposited on the activated carbon for each particle. Consequently, the movement paths and reaction surface areas of lithium ions within the electrode become inconsistent, causing variations in applied voltage and resistance. This leads to reduced efficiency during the charging and discharging process, and decreases the battery's capacity, initial efficiency, and lifespan characteristics. Furthermore, if the Span value exceeds 5, fine particles and large particles must be removed through grinding and classification processes, which leads to increased complexity of the manufacturing process and higher costs.

[0065] According to one embodiment of the present invention, the average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer of the porous activated carbon is 50 ) is 3 μm or more and 10 μm or less. More specifically, the average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer of the porous activated carbon 50 ) may be 3.0 μm or more, 3.5 μm or more, 4.0 μm or more, 4.5 μm or more, 5.0 μm or more, 5.5 μm or more, 6.0 μm or more, 6.5 μm or more, 7.0 μm or more, or 7.5 μm or more, and may also be 10.0 μm or less, 9.5 μm or less, 9.0 μm or less, 8.5 μm or less, or 8.0 μm or less. The average particle size (D) of the porous activated carbon is 50 If ) is less than 5 μm, particles may aggregate, reducing dispersibility, and a problem arises where silicon is deposited only on the surface of the porous activated carbon and not inside the pores because sufficient pores are not secured. Conversely, the average particle size (D) of the porous activated carbon 50 If ) exceeds 10 μm, silicon cannot be deposited up to the center of the porous activated carbon, resulting in non-uniform battery performance of the silicon-carbon composite. In the present invention, 'particle size Dn' refers to the particle size at the n% point of the cumulative volume distribution according to particle size. That is, D 50 is the particle size at the 50% point of the cumulative volume distribution according to particle size, corresponding to the average particle size, and D 90 The particle size at the 90% point of the cumulative volume distribution according to particle size is D 10Dn is the particle size at the 10% point of the cumulative volume distribution according to particle size. The above Dn can be measured using the laser diffraction method. Specifically, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) to calculate the particle size distribution by measuring the difference in diffraction patterns according to particle size as the particles pass through the laser beam. By calculating the particle diameters at the points corresponding to 10%, 50%, and 90% of the cumulative volume distribution according to particle size in the measuring device, D 10 , D 50 and D 90 It can measure.

[0066] According to one embodiment of the present invention, the average pore size measured by BET analysis of the porous activated carbon is 1.5 nm or more and 2.5 nm or less. More specifically, the average pore size measured by BET analysis of the porous activated carbon may be 1.5 nm or more, 1.6 nm or more, or 1.7 nm or more, and may also be 2.5 nm or less, 2.4 nm or less, 2.3 nm or less, 2.2 nm or less, 2.1 nm or less, 2.0 nm or less, 1.9 nm or less, or 1.8 nm or less. If the average pore size of the porous activated carbon is less than 1.5 nm, the amount of silicon that can be deposited is limited, and the silicon deposition efficiency is reduced because the pores are prone to clogging. Conversely, if the average pore size of the porous activated carbon exceeds 2.5 nm, it has negative effects such as a relative decrease in the specific surface area of ​​the porous activated carbon and weakened structural stability of the support.

[0067] The above BET analysis is an experimental technique for measuring the surface area and pore structure of a substance, primarily using an inert gas such as nitrogen (N2) to calculate the surface area through the adsorption and desorption of the gas. First, the sample is placed in the analysis equipment, and the gas is adsorbed at a low temperature. Then, the amount of adsorbed gas is measured at various pressures while adjusting the gas pressure. The measured data is plotted as a function of the gas pressure to create an adsorption isotherm, and then the surface area, pore volume, and pore size distribution of the sample are calculated using the BET equation regarding the relationship between the amount of adsorbed gas and the gas pressure. In particular, the specific surface area of ​​the substance can be calculated using the unit area of ​​gas molecules and the amount of single-layer adsorption.

[0068] According to one embodiment of the present invention, the BET specific surface area of ​​the porous activated carbon can be measured through BET (Brunauer-Emmett-Teller) analysis, and 1,000 m² 2 / g or more, 2,500 m 2 It is less than / g. More specifically, the BET specific surface area of ​​the carbon porous body is 1,000 m² 2 / g or more, 1,100 m 2 / g or more, 1,200 m 2 / g or more, 1,300 m 2 / g or more, 1,400 m 2 / g or more, 1,500 m 2 / g or more, 1,600 m 2 / g or more, 1,700 m 2 / g or more, 1,800 m 2 / g or more, or 1,900 m 2 It can be more than / g, and also, 2,500 m 2 / g or less, 2,400 m 2 / g or less, 2,300 m 2 / g or less, 2,200 m 2 / g or less, 2,100 m 2 / g or less, or 2,000 m 2It may be / g or less. The BET specific surface area of ​​the porous activated carbon is 1,000 m² 2 If it falls below / g, the silicon deposition efficiency decreases, and electrochemical performance deteriorates, such as a reduction in the battery's specific capacity due to a decrease in the contact area of ​​the porous activated carbon with the electrolyte. Conversely, the BET specific surface area of ​​the porous activated carbon is 2,500 m² 2 If it exceeds / g, the density of porous activated carbon decreases, leading to a reduction in energy density and a problem where cycle characteristics deteriorate.

[0069] According to one embodiment of the present invention, the silicon may be present on at least one of the inner pores and the outer surface of the particle of the porous activated carbon. Silicon deposition on the surface of the porous activated carbon can increase the charge / discharge efficiency of the electrode and improve electrical conductivity, while silicon deposition inside the pores of the porous activated carbon can shorten the ion diffusion path and improve electrochemical performance. Furthermore, in terms of thermal conductivity, silicon deposition on the surface of the porous activated carbon can improve thermal management performance, and silicon deposition inside the pores can contribute to increasing thermal stability.

[0070] According to one embodiment of the present invention, the silicon may be included in an amount of 30% or more and 70% or less with respect to the total content of the silicon-carbon composite. More specifically, the silicon may be 30% or more, 35% or more, 40% or more, 45% or more, or 50% or more with respect to the total content of the silicon-carbon composite, and may also be 70% or less, 65% or less, 60% or less, or 55% or less. When the content of silicon deposited on at least one of the pore interior and particle surface of the porous activated carbon satisfies the above range, the silicon-carbon composite can secure a sufficient specific capacity while maintaining high electrical conductivity, thereby having higher energy density and excellent lifespan characteristics.

[0071] According to one embodiment of the present invention, the average particle size of the silicon nanoparticles may be 0.5 nm or more and 2.5 nm or less. More specifically, the average particle size of the silicon nanoparticles may be 0.5 nm or more, 0.6 nm or more, 0.7 nm or more, 0.8 nm or more, 0.9 nm or more, 1.0 nm or more, 1.1 nm or more, 1.2 nm or more, 1.3 nm or more, 1.4 nm or more, or 1.5 nm or more, and may also be 2.5 nm or less, 2.4 nm or less, 2.3 nm or less, 2.2 nm or less, 2.1 nm or less, 2.0 nm or less, 1.9 nm or less, 1.8 nm or less, 1.7 nm or less, or 1.6 nm or less. When the average particle size of the silicon nanoparticles satisfies the above range, the performance and stability of the battery can be secured through surface protection and volume expansion mitigation while maintaining the electrical conductivity of the electrode.

[0072]

[0073] Method for manufacturing silicon-carbon composites

[0074] The present invention provides a method for manufacturing a silicon-carbon composite for manufacturing the silicon-carbon composite.

[0075] The above method for manufacturing a silicon-carbon composite may include the step of depositing silicon on at least one of the pore interior and particle surface of the porous activated carbon.

[0076] The present invention is characterized by manufacturing a silicon-carbon composite using porous activated carbon having a uniform particle size distribution, thereby eliminating the need for separate grinding and classification processes.

[0077] The porous activated carbon may be manufactured through a manufacturing method comprising: (S1) a step of preparing a polymer by reacting phenol and formaldehyde; (S2) a step of stabilizing the polymer at a temperature of 150°C to 350°C for 1 hour to 3 hours; (S3) a step of carbonizing the stabilized polymer at a temperature of 500°C to 800°C for 1 hour to 3 hours; and (S4) a step of activating the carbonized polymer using an activation reagent at a temperature of 600°C to 900°C for 1 hour to 3 hours.

[0078] Step (S1) above is a process of preparing a polymer by reacting phenol and formaldehyde, with the primary purpose being to synthesize phenol resin. This reaction is generally carried out at a temperature between 150°C and 200°C, and the reaction time can be controlled from 1 hour to 24 hours. Additionally, a catalyst may be used to accelerate the reaction, and if a basic catalyst such as sodium hydroxide is used, the reaction between phenol and formaldehyde proceeds more rapidly. During the reaction, phenol and formaldehyde polymerize under heated conditions and gradually transform into a resin. As the reaction time increases, the molecular weight of the resulting resin increases, and its physical properties change. Once the reaction is complete, the reaction mixture is cooled to solidify the resin, which can then be processed into porous activated carbon through stabilization, carbonization, and activation processes in subsequent steps.

[0079] Step (S2) above is a process for stabilizing the polymer synthesized in Step (S1), and aims to stabilize the structure of the polymer before carbonization. This stabilization step strengthens the chemical structure of the polymer to help prevent the polymer from decomposing or shrinking excessively during the subsequent carbonization step. In this process, the polymer may be heated at a temperature of 150°C to 350°C for 1 to 3 hours. When stabilization is performed within the above temperature range, the polymer chains may oxidize or cross-links may be formed, making the polymer structure more robust and thermally stable. Additionally, when stabilization is performed for 1 to 3 hours, changes proceed uniformly throughout the interior of the polymer, allowing it to maintain a homogeneous structure during the subsequent carbonization step. During this stabilization process, the polymer is gradually dehydrated, some volatile substances are removed, and structural stability increases as oxidation reactions occur internally. The stabilized polymer then becomes the material for the subsequent carbonization step.

[0080] Step (S3) above is a process of carbonizing the polymer stabilized in Step (S2), with the aim of converting the polymer into a carbon compound by heating it. During this process, elements such as hydrogen, oxygen, and nitrogen in the polymer are released as volatile compounds, and a carbon framework is formed. Since carbonization temperature and time conditions have a significant influence on the efficiency of the carbonization process and the characteristics of the final carbon material, the carbonization process of the present invention may be carried out at a temperature of 500°C to 800°C for 1 to 3 hours. Specifically, when carbonization is carried out within the above temperature range, a carbon framework is stably formed, and high carbon content and thermal stability can be secured. In addition, when the above time range is satisfied, carbonization can be uniformly performed even inside the polymer. This provides a foundation for the polymer to form a desired pore structure in the subsequent activation step.

[0081] Step (S4) above is a process of activating the polymer carbonized in Step (S3) to form a pore structure, and aims to form fine pores on the surface of the polymer using an activation reagent. The activation process of the present invention may be carried out at a temperature of 600°C to 900°C for 1 to 3 hours, and if the above temperature range is satisfied, a large specific surface area of ​​the porous activated carbon can be secured. In addition, if the above time range is satisfied, a uniform pore structure is formed, and the specific surface area of ​​the porous activated carbon can be maximized. In conclusion, through the above steps (S1) to (S4), a porous activated carbon having excellent adsorption performance can be finally manufactured.

[0082] In the above step (S4), the activating agent is not particularly limited as long as it reacts with the polymer carbonized at high temperature to create pores and remove unnecessary carbon components. According to one embodiment of the present invention, the activating agent may be one or more selected from the group consisting of potassium hydroxide, phosphoric acid, zinc chloride, potassium carbonate, and sodium hydroxide.

[0083] According to one embodiment of the present invention, in step (S4), the weight ratio of the carbonized polymer to the activating reagent may be 1:2 to 1:6. More specifically, in step (S4), the weight ratio of the carbonized polymer to the activating reagent may be 1:2.0 or higher, 1:2.5 or higher, 1:3.0 or higher, 1:3.5 or higher, or 1:4.0 or higher, and may also be 1:6.0 or lower, 1:5.5 or lower, 1:5.0 or lower, or 1:4.5 or lower. When the weight ratio of the carbonized polymer to the activating reagent satisfies the above range, the size and distribution of the pores formed can be optimized to maximize the specific surface area of ​​the porous activated carbon.

[0084] According to the present invention, the method comprises the step of depositing silicon on at least one of the pore interior and particle surface of a porous activated carbon; wherein the silicon can be deposited on a carbon porous body using a chemical vapor deposition process, a physical vapor deposition process, a thermochemical deposition process, a chemical precipitation process, a sol-gel deposition process, an electron beam deposition process, etc., and preferably can be deposited on a carbon porous body using a chemical vapor deposition process.

[0085] The chemical vapor deposition process described above includes a process of exposing a gaseous silicon precursor, such as silane (SiH4) or dichlorosilane (SiH2Cl2), to the surface of a carbon porous body at a high temperature, and allowing the silicon precursor gas to penetrate into the pores of the carbon porous body to form solid silicon through a chemical reaction. The chemical vapor deposition process has the advantage of being able to form a silicon layer of high purity and uniformity on the surface or inside the pores of the carbon porous body, and enabling more precise thickness control.

[0086] According to one embodiment of the present invention, the silicon may be deposited at a temperature of 350°C to 550°C, and more specifically, the silicon may be at a temperature of 350°C or higher, 360°C or higher, 370°C or higher, 380°C or higher, 390°C or higher, 400°C or higher, 410°C or higher, 420°C or higher, 430°C or higher, 440°C or higher, or 450°C or higher, and may also be at a temperature of 550°C or lower, 540°C or lower, 530°C or lower, 520°C or lower, 510°C or lower, 500°C or lower, 490°C or lower, 480°C or lower, 470°C or lower, or 460°C or lower. When the above silicon is deposited inside or on the surface of the pores of porous activated carbon at an appropriate temperature, the pore walls are reinforced while maintaining the porosity of the pores of the porous activated carbon, thereby further increasing structural stability while minimizing the reduction in specific surface area.

[0087] According to one embodiment of the present invention, the step of depositing silicon may be carried out for 1 to 3 hours, and when the above time range is satisfied, an appropriate amount of silane is deposited inside the pores, and there is an advantage in being able to manufacture a silicon-carbon composite with excellent initial efficiency and capacity retention rate.

[0088]

[0089] cathode

[0090] The present invention provides a cathode comprising the silicon-carbon composite.

[0091] The above may include a negative current collector and a negative active material layer formed on the above negative current collector, and the negative active material layer may include the silicon-carbon composite.

[0092] The above-mentioned negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used. In addition, the above-mentioned negative electrode current collector may typically have a thickness of 3 μm to 500 μm, and fine irregularities may be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0093] The above-mentioned cathode active material layer may, together with the cathode active material, optionally include a conductive material and a binder as needed.

[0094] The conductive material described above is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10% by weight or less, preferably 5% by weight or less, based on the total weight of the negative electrode active material layer. Such conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon; metal powders such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives may be used.

[0095] The above binder is a component that assists in the bonding between the conductive material, the active material, and the current collector, and is typically added in an amount of 0.1% to 10% by weight based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0096] The above cathode may be manufactured by applying and drying a composition for forming a cathode active material layer, prepared by dissolving or dispersing a cathode active material and optionally a binder and a conductive material in a solvent, onto a cathode current collector, or by casting the composition for forming a cathode active material layer onto a separate support and then laminating the film obtained by peeling from the support onto a cathode current collector.

[0097]

[0098] lithium secondary battery

[0099] The present invention provides a lithium secondary battery comprising a cathode comprising the above-mentioned cathode.

[0100] The above lithium secondary battery may comprise the negative electrode; the positive electrode; a separator interposed between the negative electrode and the positive electrode; and an electrolyte. Additionally, the above lithium secondary battery may optionally further comprise a battery container housing an electrode assembly of the negative electrode, the positive electrode, and the separator, and a sealing member sealing the battery container.

[0101] The above positive electrode may include a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector.

[0102] The above positive current collector may include a highly conductive metal, and is not particularly limited as long as it facilitates the adhesion of the positive active material layer and is non-reactive within the voltage range of the battery. The above positive current collector may be, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. Additionally, the above positive current collector may typically have a thickness of 3 μm to 500 μm, and may form fine irregularities on the surface of the current collector to increase the adhesion of the positive active material. It may be used in various forms, such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.

[0103] The above positive active material layer may, together with the positive active material, optionally include a conductive material and a binder as needed. The above positive active material is LiCoO2, LiCoPO4, LiNiO2, Li x Ni a Co b M 1 c M 2 d O2(M 1 and M 2 Each is independently selected from the group consisting of Al, Mn, Cu, Fe, V, Cr, Mo, Ga, B, W, Mo, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, and Y, and 0.9≤x≤1.1, 0 <a<1.0, 0<b<1.0, 0≤c<0.5, 0≤ d<0.5, a+b+c+d=1이다.), LiMnO2, LiMnO3, LiMn2O3, LiMn2O4, LiMn 2-e M 3 e O2(M 3 ...is one or more selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, and 0.01≤e≤0.1), Li2Mn3M 4 O8(M 4is one or more selected from the group consisting of Ci, Ni, Fe, Cu and Zn), and may be one selected from the group consisting of LiFePO4, Li2CuO2, LiV3O8, V2O5, Cu2V2O7 and lithium metal.

[0104] The binder in the above positive active material layer serves to improve adhesion between positive active material particles and adhesion between the positive active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, polyacrylic acid, and polymers in which hydrogens thereof are substituted with Li, Na, or Ca, or various copolymers thereof, and one of these alone or a mixture of two or more may be used. The above binder may be included in an amount of 0.1% to 15% by weight relative to the total weight of the positive active material layer.

[0105] The conductive material of the positive electrode active material layer is used to impart conductivity to the electrode, and in the battery being constructed, any material that possesses electronic conductivity without causing chemical changes can be used without any special limitations. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fibers; metal powder or metal fibers such as copper, nickel, aluminum, and silver; conductive tubes such as carbon nanotubes; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more may be used. The conductive material may be included in an amount of 0.1% to 15% by weight relative to the total weight of the positive electrode active material layer.

[0106] The above-mentioned anode may be manufactured according to a conventional anode manufacturing method. Specifically, the above-mentioned anode may be manufactured by applying a composition for forming an anode active material layer, prepared by dissolving or dispersing the above-mentioned anode active material and, optionally, a binder, a conductive material, and a dispersant in a solvent, onto an anode current collector, followed by drying and rolling, or by casting the composition for forming an anode active material layer onto a separate support and then laminating a film obtained by peeling from the support onto an anode current collector.

[0107] The above solvent may be a solvent generally used in the relevant technical field, and may include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, or water, and one of these alone or a mixture of two or more may be used. The amount of the above solvent used is sufficient if it is sufficient to dissolve or disperse the anode active material, conductive material, binder, and dispersant, taking into account the coating thickness of the slurry and the manufacturing yield, and to have a viscosity that can exhibit excellent thickness uniformity when coated for anode manufacturing thereafter.

[0108] The above separator separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions. It can be used without special restrictions as long as it is typically used as a separator in a lithium secondary battery, and it is particularly desirable that it has low resistance to the movement of electrolyte ions and excellent electrolyte wettability. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fiber or polyethylene terephthalate fiber, may be used. Furthermore, a coated separator containing ceramic components or polymer materials may be used to ensure heat resistance or mechanical strength, and it may optionally be used in a single-layer or multi-layer structure.

[0109] Examples of the above electrolytes include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., which can be used in the manufacture of lithium secondary batteries, but are not limited to these. As a specific example, the above electrolyte may include an organic solvent and a lithium salt.

[0110] The above organic solvent may be used without special restrictions as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the above organic solvent may include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; and aromatic hydrocarbon-based solvents such as benzene and fluorobenzene. Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, a directional ring, or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, a carbonate-based solvent is preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) is more preferred.

[0111] The above lithium salt may be used without special restrictions as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the anion of the above lithium salt is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - The lithium salt may be at least one selected from the group consisting of LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. It is preferable to use the lithium salt within the range of 0.1 M to 2.0 M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and lithium ions can move effectively.

[0112] In addition to the above electrolyte components, the above electrolyte may further include one or more additives for the purpose of improving the lifespan characteristics of the battery, suppressing the decrease in battery capacity, and improving the discharge capacity of the battery, such as, for example, a haloalkylene carbonate-based compound such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, triamide hexaphosphate, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride. In this case, the above additives may be included in an amount of 0.1% to 5% by weight based on the total weight of the electrolyte.

[0113] The external shape of the lithium secondary battery of the present invention is not particularly limited, but can be a cylindrical shape using a can, a prismatic shape, a pouch shape, or a coin shape.

[0114] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for a small device, but can also preferably be used as a unit cell in a medium-to-large battery module comprising a plurality of battery cells.

[0115] Accordingly, a battery module including the above-mentioned lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0116] The above battery module or battery pack can be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0117]

[0118] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0119]

[0120] porous activated carbon

[0121] The present invention relates to a porous activated carbon having a Span value of 5 or less calculated by the following Formula 1, wherein

[0122] Average particle size (D) of the porous activated carbon according to the cumulative volume distribution measured using a laser diffraction particle size analyzer 50 ) is 3 μm or more and 10 μm or less, the average pore size of the porous activated carbon measured by BET analysis is 1.5 nm or more and 2.5 nm or less, and the BET specific surface area of ​​the porous activated carbon is 1,000 m² 2 / g or more, 2,500 m 2 Provides porous activated carbon with a content of / g or less.

[0123] [Equation 1]

[0124] Span=(D 90 -D 10 ) / D 50

[0125] In the above Equation 1,

[0126] D 90 is the particle size at the 90% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and

[0127] D 10 is the particle size at the 10% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and

[0128] D 50 is the particle size at the 50% point of the volume cumulative distribution according to the particle size of the porous activated carbon particles.

[0129] According to conventional methods for manufacturing silicon-carbon composites, a classification process is required to remove fine particles and large carbon bodies generated during the grinding process of porous activated carbon. If porous activated carbon with non-uniform particle size is used without undergoing this classification process, the amount of silicon deposited on at least one of the pores and the outer surface of the particles may differ, and the silicon-carbon composite manufactured in this way is not advantageous for battery performance. However, if the particle size of the porous activated carbon is uniform from the beginning, the grinding and classification processes mentioned above do not need to be performed, which can help reduce costs and improve battery performance.

[0130] To solve the above problem, using the porous activated carbon of the present invention has the advantage of enabling the production of a high-quality silicon-carbon composite.

[0131] According to one embodiment of the present invention, the Span value corresponding to the particle size uniformity of the porous activated carbon is 5 or less, and more specifically, the Span value of the porous activated carbon is 5.0 or less, 4.9 or less, 4.8 or less, 4.7 or less, 4.6 or less, 4.5 or less, 4.4 or less, 4.3 or less, 4.2 or less, 4.1 or less, 4.0 or less, 3.9 or less, 3.8 or less, 3.7 or less, 3.6 or less, 3.5 or less, 3.4 or less, 3.3 or less, 3.2 or less, 3.1 or less, 3.0 or less, 2.9 or less, 2.8 or less, 2.7 or less, 2.6 or less, 2.5 or less, 2.4 or less, 2.3 or less, 2.2 or less, 2.1 or less, 2.0 or less, 1.9 or less, 1.8 or less, 1.7 or less, It may be 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, or 1.1 or less, and the lower limit is not specifically limited but may be 0.0 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, or 1.0 or more. If the Span value is greater than 5, the particle size distribution widens, and the particle size of the porous activated carbon becomes non-uniform. When using porous activated carbon with such non-uniform particle size, the surface area and pore structure vary depending on the particle size, so silicon is not uniformly deposited on the activated carbon for each particle. Consequently, the movement path of lithium ions and the reaction surface area within the electrode become inconsistent, causing deviations in the applied voltage and resistance, which reduces efficiency during the charging and discharging process, and decreases the capacity, initial efficiency, and lifespan characteristics of the battery. Furthermore, if the Span value exceeds 5, fine particles and large particles must be removed through grinding and classification processes, which leads to problems of increased complexity and cost in the manufacturing process.

[0132] According to one embodiment of the present invention, the average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer of the porous activated carbon is50 ) is 3 μm or more and 10 μm or less. More specifically, the average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer of the porous activated carbon 50 ) may be 3.0 μm or more, 3.5 μm or more, 4.0 μm or more, 4.5 μm or more, 5.0 μm or more, 5.5 μm or more, 6.0 μm or more, 6.5 μm or more, 7.0 μm or more, or 7.5 μm or more, and may also be 10.0 μm or less, 9.5 μm or less, 9.0 μm or less, 8.5 μm or less, or 8.0 μm or less. The average particle size (D) of the porous activated carbon is 50 If ) is less than 5 μm, particles may aggregate, reducing dispersibility, and a problem arises where silicon is deposited only on the surface of the porous activated carbon and not inside the pores because sufficient pores are not secured. Conversely, the average particle size (D) of the porous activated carbon 50 If ) exceeds 10 μm, silicon cannot be deposited up to the center of the porous activated carbon, resulting in non-uniform battery performance of the silicon-carbon composite. In the present invention, 'particle size Dn' refers to the particle size at the n% point of the cumulative volume distribution according to particle size. That is, D 50 is the particle size at the 50% point of the cumulative volume distribution according to particle size, corresponding to the average particle size, and D 90 The particle size at the 90% point of the cumulative volume distribution according to particle size is D 10Dn is the particle size at the 10% point of the cumulative volume distribution according to particle size. The above Dn can be measured using the laser diffraction method. Specifically, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) to calculate the particle size distribution by measuring the difference in diffraction patterns according to particle size as the particles pass through the laser beam. By calculating the particle diameters at the points corresponding to 10%, 50%, and 90% of the cumulative volume distribution according to particle size in the measuring device, D 10 , D 50 and D 90 It can measure.

[0133] According to one embodiment of the present invention, the average pore size measured by BET analysis of the porous activated carbon is 1.5 nm or more and 2.5 nm or less. More specifically, the average pore size measured by BET analysis of the porous activated carbon may be 1.5 nm or more, 1.6 nm or more, or 1.7 nm or more, and may also be 2.5 nm or less, 2.4 nm or less, 2.3 nm or less, 2.2 nm or less, 2.1 nm or less, 2.0 nm or less, 1.9 nm or less, or 1.8 nm or less. If the average pore size of the porous activated carbon is less than 1.5 nm, the amount of silicon that can be deposited is limited, and the silicon deposition efficiency is reduced because the pores are prone to clogging. Conversely, if the average pore size of the porous activated carbon exceeds 2.5 nm, it has negative effects such as a relative decrease in the specific surface area of ​​the porous activated carbon and weakened structural stability of the support.

[0134] The above BET analysis is an experimental technique for measuring the surface area and pore structure of a substance, primarily using an inert gas such as nitrogen (N2) to calculate the surface area through the adsorption and desorption of the gas. First, the sample is placed in the analysis equipment, and the gas is adsorbed at a low temperature. Then, the amount of adsorbed gas is measured at various pressures while adjusting the gas pressure. The measured data is plotted as a function of the gas pressure to create an adsorption isotherm, and then the surface area, pore volume, and pore size distribution of the sample are calculated using the BET equation regarding the relationship between the amount of adsorbed gas and the gas pressure. In particular, the specific surface area of ​​the substance can be calculated using the unit area of ​​gas molecules and the amount of single-layer adsorption.

[0135] According to one embodiment of the present invention, the BET specific surface area of ​​the porous activated carbon can be measured through BET (Brunauer-Emmett-Teller) analysis, and 1,000 m² 2 / g or more, 2,500 m 2 It is less than / g. More specifically, the BET specific surface area of ​​the carbon porous body is 1,000 m² 2 / g or more, 1,100 m 2 / g or more, 1,200 m 2 / g or more, 1,300 m 2 / g or more, 1,400 m 2 / g or more, 1,500 m 2 / g or more, 1,600 m 2 / g or more, 1,700 m 2 / g or more, 1,800 m 2 / g or more, or 1,900 m 2 It can be more than / g, and also, 2,500 m 2 / g or less, 2,400 m 2 / g or less, 2,300 m 2 / g or less, 2,200 m 2 / g or less, 2,100 m 2 / g or less, or 2,000 m 2It may be / g or less. The BET specific surface area of ​​the porous activated carbon is 1,000 m² 2 If it falls below / g, the silicon deposition efficiency decreases, and electrochemical performance deteriorates, such as a reduction in the battery's specific capacity due to a decrease in the contact area of ​​the porous activated carbon with the electrolyte. Conversely, the BET specific surface area of ​​the porous activated carbon is 2,500 m² 2 If it exceeds / g, the density of porous activated carbon decreases, leading to a reduction in energy density and a problem where cycle characteristics deteriorate.

[0136]

[0137] Example 1

[0138] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.72 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 0.48 g of phenol was added to the solution and stirred, followed by the addition of 1.25 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 2 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 700 °C for 2 hours. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0139]

[0140] Example 2

[0141] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.72 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 0.48 g of phenol was added to the solution and stirred, followed by the addition of 1.25 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 2 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 700 °C for 1 hour. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0142]

[0143] Example 3

[0144] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.72 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 1.44 g of phenol was added to the solution and stirred, followed by the addition of 3.75 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 2 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 700 °C for 2 hours. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0145]

[0146] Example 4

[0147] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.72 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 1.44 g of phenol was added to the solution and stirred, followed by the addition of 3.75 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 2 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 700 °C for 1 hour. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0148]

[0149] Example 5

[0150] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.72 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 1.44 g of phenol was added to the solution and stirred, followed by the addition of 3.75 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 2 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 900 °C for 2 hours. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0151]

[0152] Comparative Example 1

[0153] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.36 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 0.48 g of phenol was added to the solution and stirred, followed by the addition of 1.25 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 2 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 600 °C for 2 hours. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0154]

[0155] Comparative Example 2

[0156] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.36 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 0.48 g of phenol was added to the solution and stirred, followed by the addition of 1.25 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 2 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 700 °C for 2 hours. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0157]

[0158] Comparative Example 3

[0159] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 1.44 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 0.48 g of phenol was added to the solution and stirred, followed by the addition of 1.25 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 2 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 700 °C for 2 hours. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0160]

[0161] Comparative Example 4

[0162] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.36 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 1.44 g of phenol was added to the solution and stirred, followed by the addition of 3.75 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 2 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 700 °C for 2 hours. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0163]

[0164] Comparative Example 5

[0165] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.72 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 0.48 g of phenol was added to the solution and stirred, followed by the addition of 1.25 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 1 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 700 °C for 4 hours. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0166]

[0167] Comparative Example 6

[0168] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.72 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 0.48 g of phenol was added to the solution and stirred, followed by the addition of 1.25 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 4 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 700 °C for 1 hour. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0169]

[0170] Comparative Example 7

[0171] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.72 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 0.48 g of phenol was added to the solution and stirred, followed by the addition of 1.25 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 2 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 500 °C for 2 hours. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0172]

[0173] Comparative Example 8

[0174] 28.6 mL of water and 11.4 mL of ethanol were added to a 100 mL beaker and stirred, then 0.72 mL of 25 wt% ammonia solution was added and stirred. Subsequently, 0.48 g of phenol was added to the solution and stirred, followed by the addition of 1.25 mL of 37 wt% formalin and stirring. The final solution was placed in a Teflon autoclave, heated to 170 °C, and maintained for 6 hours. Afterward, the resulting polymer was washed with distilled water and ethanol, dried at 80 °C for 12 hours, stabilized at 200 °C for 2 hours under an Ar atmosphere, and then carbonized at 600 °C for 2 hours. Next, 0.5 g of the carbonized polymer, 2 g of KOH, and 50 mL of distilled water were added to a 500 mL round-bottom flask and mixed, then dried for 2 hours using a rotary evaporator. Afterward, the dried mixture was stabilized at 200 °C for 2 hours under an Ar atmosphere, and then activated at 900 °C for 2 hours. The activated polymer was washed with distilled water to obtain porous activated carbon, and 10 g of the porous activated carbon was subjected to chemical vapor deposition at 450 °C for 2 hours under a monosilane atmosphere to prepare a silicon-carbon composite.

[0175]

[0176] Experimental Example 1: Observation of Volume Cumulative Distribution of Porous Activated Carbon According to Particle Size

[0177] For the porous activated carbon prepared in the examples and comparative examples, using a particle size analyzer (PSD, Microtrac, S3500), D 10 , D 50 , and D 90 The values ​​were measured and shown in Table 1 below, and the Span according to Equation 1 below was calculated and shown together in Table 1 below.

[0178] [Equation 1]

[0179] Span=(D 90 -D 10 ) / D50

[0180] In the above Equation 1,

[0181] D 90 is the particle size at the 90% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and

[0182] D 10 is the particle size at the 10% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and

[0183] D 50 is the particle size at the 50% point of the volume cumulative distribution according to the particle size of the porous activated carbon particles.

[0184]

[0185] Classification D 10 (㎛)D 50 (㎛)D 90 (㎛)Span Example 1 15 12.00 Example 2 16 13 2.00 Example 3 37 16.5 1.93 Example 4 68 18 1.50 Example 5 27 15 1.86 Comparative Example 1 35 31 5.60 Comparative Example 2 14 22 5.25 Comparative Example 3 12.5 6 2.00 Comparative Example 4 3 13 47 3.38 Comparative Example 5 14 9 2.00 Comparative Example 6 15 11 2.00 Comparative Example 7 16 15 2.33 Comparative Example 8 13 7 2.00

[0186] Through Table 1 above, the porous activated carbon prepared in Examples 1 to 5 has a Span value of 5 or less calculated by Equation 1 described in this specification, and the average particle size (D) of the porous activated carbon according to the volume cumulative distribution measured using a laser diffraction particle size analyzer 50 It was confirmed that ) is 3 μm or more and 10 μm or less. In contrast, it was confirmed that the porous activated carbon prepared in Comparative Examples 1 and 2 has a Span value greater than 5, calculated by Equation 1 described in this specification. Furthermore, for the porous activated carbon prepared in Comparative Examples 3 and 4, the average particle size (D) of the porous activated carbon according to the volume cumulative distribution measured using a laser diffraction particle size analyzer 50 It was confirmed that ) is less than 3 µm or greater than 10 µm.

[0187]

[0188] Experimental Example 2: Measurement of Specific Surface Area

[0189] For the porous activated carbon prepared in the above examples and comparative examples, the average pore size and specific surface area were measured using Belsorp-Max equipment, and the results are shown in Table 2 below.

[0190] Classification Average pore size (nm) Specific surface area (m²) 2 / g) Example 1 1.72,000 Example 2 1.51,500 Example 3 1.81,800 Example 4 1.71,600 Example 5 2.12,200 Comparative Example 11.51,600 Comparative Example 22.02,400 Comparative Example 32.02,050 Comparative Example 42.11,700 Comparative Example 51.02,000 Comparative Example 62.62,000 Comparative Example 71.0800 Comparative Example 82.32,550

[0191] As shown in Table 2 above, the porous activated carbons prepared in Examples 1 to 5 have an average pore size of 1.5 nm or more and 2.5 nm or less as measured by BET analysis, and a BET specific surface area of ​​1,000 m² 2 / g or more, 2,500 m 2 It was confirmed that it was / g or less. In contrast, it was confirmed that the average pore size of the porous activated carbon prepared in Comparative Examples 5 to 7, measured by BET analysis, was less than 1.5 nm or greater than 2.5 nm, and the porous activated carbon prepared in Comparative Examples 7 and 8 had a BET specific surface area of ​​1,000 m² 2 Less than / g or 2,500 m 2 It was confirmed that it exceeded / g.

[0192]

[0193] Experimental Example 3: Evaluation of Life Characteristics

[0194] A cathode slurry was prepared by mixing the silicon-carbon composite, PAA binder, and super C conductive material prepared in the above examples and comparative examples in a weight ratio of 8:1:1. The cathode slurry was coated onto a copper foil with a thickness of 20 μm with a uniform thickness using a blade-type coating machine, a Matisse coater. The cathode was prepared by drying at 80°C.

[0195] An electrode assembly was manufactured by using the above-mentioned negative electrode as a working electrode and lithium metal as a counter electrode, interposing a porous polyethylene separator between the negative electrode and the counter electrode, placing the electrode assembly inside a case, and then injecting an electrolyte into the case to manufacture a secondary battery. At this time, the electrolyte was prepared by dissolving a small amount of fluoroethylene carbonate in a solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 1:1.

[0196] For the secondary battery manufactured as described above, CC / CV mode charging was performed at 25°C with a constant current of 0.1C to 0.05V (termination current 0.05C), and CC mode discharging was performed until it reached 1.5V. The charging capacity and discharging capacity were measured and are shown in Table 3 below. At this time, 1C was set to 2000mA / g. The percentage of discharge capacity relative to charging capacity was used as the initial efficiency (%) and is shown in Table 3 below. Additionally, the percentage of the discharge capacity of the 50th cycle relative to the discharge capacity of the 1st cycle was used as the capacity retention rate (%) and is also shown in Table 3 below.

[0197]

[0198] Classification Charging Capacity (mAh / g) Discharging Capacity (mAh / g) Initial Efficiency (%) Capacity Retention Rate (%) @50 thcycle Example 1 2,250 2,000 88.9 90.0 Example 2 2,034 1,800 88.5 89.0 Example 3 3 1,231,900 89.5 89.0 Example 4 4 ​​1,829 1,650 90.2 88.6 Example 5 2,196 1,950 88.8 88.0 Comparative Example 1 2,252 1,950 86.6 85.0 Comparative Example 2 2 1,800 1,600 88.9 80.0 Comparative Example 3 3 1,953 1,650 84.5 83.0 Comparative Example 4 4 ​​1,618 1,400 86.5 86.0 Comparative Example 5 1,557 1,300 83.5 84.0 Comparative Example 62,375 2,000 84.28 3.0 Comparative Example 71,273 1,100 86.48 6.0 Comparative Example 82,375 2,000 84.28 0.0

[0199] Through Table 3 above, it was confirmed that the batteries containing the silicon-carbon composites prepared in Examples 1 to 5 had an initial efficiency of 88.8% or higher and a capacity retention rate of 88.0% or higher. In contrast, the batteries containing the silicon-carbon composites prepared in Comparative Examples 1 and 3 to 8 had an initial efficiency of less than 88.8% and a capacity retention rate of less than 88.0%, indicating that the initial efficiency and capacity retention rate were inferior. Furthermore, it was confirmed that the battery containing the silicon-carbon composite prepared in Comparative Example 2 had an equivalent initial efficiency but a capacity retention rate of less than 88.0%, indicating that the capacity retention rate was inferior.

Claims

1. Porous activated carbon having a Span value of 5 or less calculated by the following Formula 1; and It comprises silicon nanoparticles present on at least one of the pore interior and particle surface of the above-mentioned porous activated carbon, and Average particle size (D) of the porous activated carbon according to the volume cumulative distribution measured using a laser diffraction particle size analyzer 50 ) is 3 µm or more and 10 µm or less, and The average pore size of the porous activated carbon measured by BET analysis is 1.5 nm or more and 2.5 nm or less, and The BET specific surface area of ​​the above porous activated carbon is 1,000 m² 2 / g or more, 2,500 m 2 Silicon-carbon composites with a content of / g or less: [Equation 1] Span=(D 90 -D 10 ) / D 50 In the above Equation 1, D 90 is the particle size at the 90% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and D 10 is the particle size at the 10% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and D 50 is the particle size at the 50% point of the volume cumulative distribution according to the particle size of the porous activated carbon particles.

2. In Paragraph 1, The silicon-carbon composite is a silicon-carbon composite in which the silicon is included in an amount of 30% or more and 70% or less with respect to the total content of the silicon-carbon composite.

3. In Paragraph 1, A silicon-carbon composite having an average particle size of the silicon nanoparticles of 0.5 nm or more and 2.5 nm or less.

4. In Paragraph 1, The above porous activated carbon is a silicon-carbon composite having a Span value of 1 or more and 5 or less.

5. In Paragraph 1, Average particle size (D) of the above porous activated carbon 50 ) is a silicon-carbon composite having a size of 5 μm or more and 10 μm or less.

6. In Paragraph 1, The above porous activated carbon is a silicon-carbon composite having an average pore size of 1.5 nm or more and 2.1 nm or less as measured by BET analysis.

7. In Paragraph 1, The above porous activated carbon has a BET specific surface area of ​​1,500 m² 2 / g or more, 2,200 m 2 Silicon-carbon composite having a g or less.

8. A step of depositing silicon on at least one of the pore interior and particle surface of porous activated carbon; comprising a method for manufacturing a silicon-carbon composite of claim 1.

9. In Paragraph 8, A method for manufacturing a silicon-carbon composite in which the silicon is deposited using a chemical vapor deposition process.

10. In Paragraph 8, A method for manufacturing a silicon-carbon composite in which the silicon is deposited at a temperature of 350°C to 550°C.

11. A cathode comprising a silicon-carbon composite according to any one of claims 1 to 7.

12. A lithium secondary battery comprising a negative electrode according to paragraph 11.

13. A porous activated carbon having a Span value of 5 or less calculated by the following Equation 1, Average particle size (D) of the porous activated carbon according to the volume cumulative distribution measured using a laser diffraction particle size analyzer 50 ) is 3 µm or more and 10 µm or less, and The average pore size of the porous activated carbon measured by BET analysis is 1.5 nm or more and 2.5 nm or less, and The BET specific surface area of ​​the above porous activated carbon is 1,000 m² 2 / g or more, 2,500 m 2 Porous activated carbon with a content of / g or less: [Equation 1] Span=(D 90 -D 10 ) / D 50 In the above Equation 1, D 90 is the particle size at the 90% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and D 10 is the particle size at the 10% point of the cumulative volume distribution according to the particle size of the porous activated carbon particles, and D 50 is the particle size at the 50% point of the volume cumulative distribution according to the particle size of the porous activated carbon particles.

14. In Paragraph 13, Porous activated carbon having a Span value of 1 or more and 5 or less.

15. In Paragraph 13, Average particle size (D) of the above porous activated carbon 50 ) is a porous activated carbon with a particle size of 5 µm or more and 10 µm or less.

16. In Paragraph 13, A porous activated carbon having an average pore size of 1.5 nm or more and 2.1 nm or less, as measured by the above BET analysis.

17. In Paragraph 13, The above BET specific surface area is 1,500 m² 2 / g or more, 2,200 m 2 Porous activated carbon with a content of / g or less.