Silicon-carbon composite, negative electrode active material, negative electrode composition, negative electrode and secondary lithium battery

Description

1 / 31 “SILICON-CARBON COMPOSITE, NEGATIVE ELECTRODE ACTIVE MATERIAL, NEGATIVE ELECTRODE COMPOSITION, NEGATIVE ELECTRODE AND LITHIUM SECONDARY BATTERY” TECHNICAL FIELD

[001] This application claims priority and benefit of Korean Patent Application No. 10-2023-0136853, filed on October 13, 2023, the descriptions of which are incorporated herein by reference in their entirety.

[002] The present application relates to a silicon-carbon composite, a negative electrode active material, a negative electrode composition, a negative electrode and a lithium secondary battery. BACKGROUND OF THE TECHNIQUE

[003] Recently, with the rapid spread of electronic devices that use batteries, such as cell phones, laptops, electric vehicles, power tools, and electric cleaners, the demand for small, lightweight secondary batteries with relatively high capacity and / or high performance is rapidly increasing. In particular, lithium secondary batteries stand out as a power source for electronic devices due to their light weight and high energy density. Consequently, research and development efforts to improve the performance of lithium secondary batteries are being actively conducted.

[004] Generally, a secondary lithium battery includes a positive electrode, a negative electrode, a separator interposed between the positive and negative electrodes, an electrolyte, an organic solvent, and the like. In addition, the positive and negative electrodes may be formed into current collectors with layers of active material, each including a positive electrode active material and a negative electrode active material. In general, for the positive electrode, a lithium-containing metal oxide, such as LiCoO2 and LiMn2O4, is used as the positive electrode active material, and for the negative electrode, a carbon-based active material or a silicon-based active material that does not contain lithium is used as the negative electrode active material. Petition 870250084307, dated 09 / 18 / 2025, page 11 / 51 2 / 31

[005] Batteries that use graphite as an active material for the negative electrode can have a high discharge voltage of 3.6 V, but there is a limit to the increase in energy density due to the low capacity.

[006] On the other hand, silicon-based active materials exhibit high capacity and efficiency and, consequently, are attracting attention as next-generation negative electrode active materials. Therefore, there is a demand for the development of silicon-based active materials with high capacity or efficiency characteristics. SUMMARY OF THE INVENTION Technical Problem

[007] An exemplary embodiment of the present disclosure has been prepared with the aim of providing a silicon-carbon composite that can be used as the active material of the negative electrode with excellent capacitance and / or efficiency characteristics.

[008] An exemplary embodiment of the present disclosure has been prepared with the aim of providing a silicon-carbon composite that can be used as a negative electrode active material with excellent water-based processability and reduced gas generation.

[009] An exemplary embodiment of the present disclosure has been prepared with the aim of providing a silicon-carbon composite that can be used as the active material of the negative electrode with excellent service life characteristics.

[010] An exemplary embodiment of the present disclosure has been prepared with the aim of providing an active negative electrode material, a negative electrode composition, a negative electrode and a secondary lithium battery, including the silicon-carbon composite. Technical Solution

[011] One example of implementing the present disclosure provides Petition 870250084307, dated 09 / 18 / 2025, page 12 / 51 3 / 31 a silicon-carbon composite that satisfies a condition of 1.3 < ((B + C) / A) < 4, wherein A is the intensity of an A peak having a chemical shift value in the range of 20 ppm to -15 ppm in a 29Si-MAS NMR spectrum, B is the intensity of a B peak having a chemical shift value in the range of -20 ppm to -100 ppm in the 29Si-MAS NMR spectrum; and C is the intensity of a C peak having a chemical shift value in the range of -110 ppm to -140 ppm in the 29Si-MAS NMR spectrum.

[012] In an exemplary embodiment of the present disclosure, the silicon-carbon composite may comprise carbon in an amount of 38 parts by weight to 50 parts by weight, based on 100 parts by weight of the silicon-carbon composite.

[013] In one embodiment of an example of the present disclosure, the silicon-carbon composite may be a particle comprising a porous silicon-carbon based particle disposed in at least a portion of an inner part and a surface of the porous silicon based particle.

[014] In an exemplary embodiment of the present disclosure, the silicon-carbon composite may further comprise a carbon layer formed on a surface of the silicon-carbon composite, and the total weight of the carbon layer may be from 5% by weight to 40% by weight, based on 100% by weight of the silicon-carbon composite.

[015] In an exemplary embodiment of the present disclosure, the silicon-carbon composite may have a specific surface area of ​​BET of 0.5 to 10 m2 / g.

[016] In one embodiment of the present disclosure, the silicon-carbon composite may have a pore volume of 0.005 to 0.03 cm3 / g.

[017] In one embodiment of an example of the present disclosure, the silicon-carbon composite may have a pore size of 10 nm to 20 nm.

[018] In one embodiment of an example of the present disclosure, the Petition 870250084307, dated 09 / 18 / 2025, page 13 / 51 4 / 31 silicon-carbon composite can have a particle diameter D90 of 5 to 15 gm, a particle diameter D50 of 1 to 10 gm, a Dmin of 1 to 3 gm and a Dmax of 17 to 23 gm.

[019] An exemplary embodiment of the present disclosure provides an active negative electrode material including the silicon-carbon composite according to the exemplary embodiment described above.

[020] In an exemplary embodiment of the present disclosure, the active material of the negative electrode may comprise silicon-carbon composite in an amount of 0.1 parts by weight to 14 parts by weight based on 100 parts by weight of the active material of the negative electrode.

[021] In an exemplary embodiment of the present disclosure, the active material of the negative electrode may additionally include a carbon-based active material, and the carbon-based active material may be included in an amount of 86 parts by weight or more and 99.9 parts by weight or less based on 100 parts by weight of the active material of the negative electrode.

[022] An exemplary embodiment of the present disclosure provides a negative electrode composition including the negative electrode active material, according to the exemplary embodiment described above; a binder; and a conductive material.

[023] In an exemplary embodiment of the present disclosure, the active material of the negative electrode included in the negative electrode composition may further comprise a carbon-based active material.

[024] An exemplary embodiment of the present disclosure provides a negative electrode including the negative electrode composition according to the exemplary embodiment described above.

[025] An exemplary embodiment of the present disclosure provides a lithium secondary battery including the negative electrode according to the exemplary embodiment described above, a positive electrode and a separator.

[026] One embodiment of an example of the present disclosure provides Petition 870250084307, dated 09 / 18 / 2025, page 14 / 51 5 / 31 a battery module including the secondary lithium battery according to the example embodiment described above.

[027] An exemplary embodiment of the present disclosure provides a battery pack including the lithium secondary battery according to the exemplary embodiment described above.

[028] An exemplary embodiment of the present disclosure provides a battery pack including the battery module according to the exemplary embodiment described above.

[029] An exemplary embodiment of the present disclosure provides a method for preparing a silicon-carbon composite, the method comprising: carrying out a disproportionation reaction by heat treatment of a silicon oxide powder; etching the heat-treated silicon oxide powder with an etching agent; and obtaining a porous silicon-based particle by pulverizing the etched silicon oxide powder; and form a silicon-carbon composite by reacting the silicon-based porous particle with a carbon source to form a carbon layer on the surface of the silicon-based porous particle, wherein the silicon-carbon composite satisfies the condition 1.3 < ((B + C) / A) < 4, wherein A is the intensity of an A peak having a chemical shift value in the range of 20 ppm to -15 ppm in a 29Si-MAS NMR spectrum, B is the intensity of a B peak having a chemical shift value in the range of -20 ppm to -100 ppm in the 29Si-MAS NMR spectrum;and C is the intensity of a C peak having a chemical shift value in the range of -110 ppm to -140 ppm in the 29SiMAS NMR spectrum. Technical effect

[030] According to the exemplary embodiments of the present disclosure, it is possible to provide a secondary lithium battery with improved capacity and / or efficiency(ies), satisfying the condition that the intensities of a plurality of chemical shift values ​​within a specific range in Petition 870250084307, dated 09 / 18 / 2025, page 15 / 51 6 / 31 29Si-MAS-NMR spectrum are within a specific ratio range. Specifically, the lifetime characteristics and / or water-based processability can be improved by satisfying the condition that the intensity ratio between peaks within a specific range is within a specific range. Within the intensity ratio range, according to the example embodiments of the present disclosure, the higher the intensity, the greater the advantages in capacity and efficiency, the change in phase stability (viscosity) in the negative electrode paste, including a binder such as carboxymethylcellulose (CMC), is reduced, and the generation of gases such as H2 is reduced, resulting in improved water-based processability. BRIEF DESCRIPTION OF THE DRAWINGS

[031] FIG. 1 is a graph showing the results of the NMR analysis of silicon-carbon composites prepared in Example 1.

[032] FIG. 2 is a graph showing the results of the NMR analysis of the silicon-carbon composites prepared in Example 2.

[033] FIG. 3 is a graph showing the results of the NMR analysis of the silicon-carbon composites prepared in Example 3.

[034] FIG. 4 is a graph showing the results of the NMR analysis of the silicon-carbon composites prepared in Example 4.

[035] FIG. 5 is a graph showing the results of the NMR analysis of the silicon-carbon composites prepared in Comparative Examples 1, 2 and 5.

[036] FIG. 6 is a graph showing the results of the NMR analysis of the silicon-carbon composites prepared in Comparative Example 6.

[037] FIG. 7 shows a waveform analysis result based on the NMR analysis result of the silicon-carbon composite from Example 2. DETAILED DESCRIPTION

[038] The present disclosure will be described in more detail below for a better understanding of the present disclosure. The present disclosure may be Petition 870250084307, dated 09 / 18 / 2025, p. 16 / 51 7 / 31 implemented in several different forms and is not limited to the example embodiments described in this document. The terms or words used throughout the descriptive report and claims should not be interpreted as being limited to their common or dictionary meanings, but rather as having meanings and concepts consistent with the technical idea of ​​the present disclosure, based on the principle that an inventor can adequately define the concepts of words or terms to better explain the invention.

[039] It should be understood that terms such as “include”, “comprise” or “have” are intended to indicate the presence of a feature, number, stage, component or combination thereof described in this descriptive report and do not exclude the possibility of the presence or addition of one or more other features or numbers, stages, components or combinations thereof.

[040] Additionally, it should be understood that when an element, such as a layer, is referred to as being “on” another element, it may be “directly on” the other element or an intervening element may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. Additionally, when an element is referred to as being “above” or “on” a reference portion, the element is positioned above or below the reference portion, and this does not necessarily mean that the element is positioned “above” or “on” in a direction opposite to gravity.

[041] It should be understood that the terms or words used throughout the descriptive report should not be interpreted as being limited to their common or dictionary meanings, but rather as having meanings and concepts consistent with the technical idea of ​​the present disclosure, based on the principle that an inventor can adequately define the concepts of words or terms to better explain the invention.

[042] As used in this document, the singular forms “a(an), Petition 870250084307, dated 09 / 18 / 2025, p. 17 / 51 8 / 31 “uma(um)” and “o(a)” should also include plural forms, unless the context clearly indicates otherwise.

[043] The preferred embodiments of this disclosure will be described in detail below. However, it should be understood that the example embodiments of this disclosure may be modified in various ways and the scope of this disclosure is not limited to the example embodiments described below.

[044] A silicon-carbon composite, according to an exemplary embodiment of the present disclosure, has the characteristic that the ratio between the sum of the intensities of a peak B and a peak C and the intensity of a peak A, ((B + C) / A), is 1.3 or greater and less than 4, where A is the intensity of peak A having a chemical shift value in the range of 20 ppm to -15 ppm in a 29Si-MAS NMR spectrum; B is the intensity of peak B having a chemical shift value in the range of -20 ppm to -100 ppm in the 29Si-MAS NMR spectrum; and C is the intensity of peak C having a chemical shift value in the range of -110 ppm to -140 ppm in the 29Si-MAS NMR spectrum. The ratio may be, for example, 1.3 or greater and 3.5 or less. In this document, if peak A, peak B, or peak C includes two or more peaks, when calculating the ratio, the intensity of the corresponding peak is calculated as the sum of the intensities of the two or more peaks.For example, in the case where there are two B peaks, when calculating the ratio, the intensity of peak B is calculated as the sum of the intensities of the two B peaks.

[045] In this descriptive report, the 29Si-MAS NMR spectrum is a spectrum measured by a 400 MHz WB solid-hole (wide hole) NMR system and can be measured under the following conditions. MAS rate (magic angle rotation): 14 kHz Spectral frequency (sfo1): 79.51 MHz (29Si) Temperature: room temperature Chemical shift reference of 29Si: TMS (l) at 0 ppm Petition 870250084307, dated 09 / 18 / 2025, p. 18 / 51 9 / 31 Pulse program: Hahn echo 1D Spectral width (sw): 100 kHz Acquisition time: 40 ms Carrier frequency (o1p) at -40 ppm Pulse length (p1): 3 μs Recycling delay (d1): 60 s Number of scans: 1K to 5k

[046] The “Gaussian / Lorentzian” fitting model was selected to analyze a waveform measured using the method above. The parameters used for analysis consist of peak amplitude, peak position, total peak width at half maximum, and Gaussian / Lorentzian fraction (xG / (1-x)L). After defining the appropriate initial values, the fitting was performed. At this point, xG / (1-x)L was set at 0.3 (xG / (1-x)L = 0.3). The fitting conditions used were nParVar = 15, Step = 1, and Threshold = 0.001, and the fitting was performed repeatedly until an appropriate convergence value was reached.

[047] In this descriptive report, a peak in the 29SiMAS NMR spectrum refers to a peak with an intensity of 10% or greater of the peak maximum intensity, and those with an intensity less than 10% of the peak maximum intensity are not included in the peak.

[048] Peak A, having a chemical shift value in the range of 20 ppm to -15 ppm in the 29Si-MAS NMR spectrum, refers to a silicon carbide (Si-C) peak, in which silicon and carbon are covalently bonded, and peak B, having a chemical shift value in the range of -20 ppm to -100 ppm, may refer to a peak of the element Si itself or of silicon oxide. A component represented by peak B may be represented as SiOx (x is 0 or greater and less than 2). For example, Si itself is a material that exhibits a peak at or near -79 ppm; therefore, when peak B appears at or near -89 ppm, it may be determined to be Si or SiOx. Petition 870250084307, dated 09 / 18 / 2025, page 19 / 51 10 / 31

[049] The silicon-carbon composite additionally has a C peak, having a chemical shift value in the range of -110 ppm to -140 ppm in the 29Si-MAS NMR spectrum. The C peak indicates the presence of SiO2. The C peak has technical importance, as the battery capacity characteristics can be improved by ensuring that the (B + C) / A ratio described above has a specific value.

[050] The present inventors have found that peak B and peak C are advantageous in expressing the capacity of a battery, and peak A has an effect on improving water-based processability. Furthermore, the present inventors have found that when the ratio of these intensities is within a certain range, both the battery capacity and water-based processability can be improved. According to an example, the ratio ((B + C) / A) of the sum of the intensities of peak B and peak C to the intensity of peak A is 1.3 or greater and less than 4. Within the above range, the battery exhibits excellent capacity and efficiency characteristics, and can exhibit excellent discharge capability as an excellent silicon-based active material.Furthermore, within the above range, gas generation during a water-based process can be reduced, and the decomposition of components, such as a cellulose-based binder used in the water-based process, can be avoided, thus maintaining phase stability and preventing a decrease in paste viscosity.

[051] According to an exemplary embodiment, the silicon-carbon composite can be represented by an active Si / C-based material. In the present descriptive report, the silicon-carbon composite is a composite of Si and C, and is distinguished from silicon carbide itself, referred to as SiC. Silicon carbide does not react electrochemically with lithium, therefore, all performance, including service life, can be measured as 0.

[052] In this descriptive report, the silicon-carbon composite is a composite of Si and C, where Si and C (e.g., graphite) are present, respectively. For example, a peak of each of Si and C can be observed by Petition 870250084307, dated 09 / 18 / 2025, page 20 / 51 11 / 31 an elemental analysis method, such as XRD or NMR. In this descriptive report, the silicon-carbon composite may be referred to as Si / C. The silicon-carbon composite may contain an additional component as needed. For example, the silicon-carbon composite may include silicon carbide, referred to as SiC. When the silicon-carbon composite includes silicon carbide, its content is 3% by weight or less. The silicon-carbon composite may be present in a crystalline state, an amorphous state, or a mixed state. As an example, the C in the silicon-carbon composite may be present in an amorphous state.

[053] According to one embodiment of example, the silicon-carbon composite may comprise carbon in an amount of 38 parts by weight to 50 parts by weight, based on 100 parts by weight of the silicon-carbon composite. Specifically, the silicon-carbon composite may comprise carbon in an amount of 38 parts by weight to 50 parts by weight, 38 parts by weight to 45 parts by weight, or 38 parts by weight to 43 parts by weight, based on 100 parts by weight of the silicon-carbon composite.

[054] If the amount of carbon is below the range above, the exposure of silicon on the surface of the silicon-carbon composite increases, increasing the possibility of side reactions with water, thus deteriorating aqueous processability. If the carbon exceeds the range above, the weight of silicon becomes relatively low, making it difficult to achieve the desired capacity.

[055] According to one embodiment of example, the silicon-carbon composite may be a particle that includes a porous silicon-carbon-based particle provided in at least a portion of an inner part and a surface of the porous silicon-based particle.

[056] If necessary, a carbon layer can be additionally formed on the surface of the silicon-carbon composite. Conductivity is conferred by the carbon layer and improves the initial efficiency, lifespan characteristics, and capacity of the secondary battery. The total weight of the carbon layer Petition 870250084307, dated 09 / 18 / 2025, p. 21 / 51 12 / 31 can vary from 5% by weight to 40% by weight, based on a total of 100% by weight of silicon-carbon composite particles. The carbon layer may include at least one amorphous carbon and one crystalline carbon.

[057] According to one exemplary embodiment, the silicon-carbon composite can be manufactured by a method comprising: carrying out a disproportionation reaction by heat treatment of a silicon oxide powder; and etching the heat-treated silicon oxide powder with an etching agent; obtaining a silicon-based porous particle by spraying the etched silicon oxide powder; and forming a silicon-carbon composite by reacting the silicon-based porous particle with a carbon source to form a carbon layer on the surface of the silicon-based porous particle.

[058] According to one embodiment of an example, the silicon-carbon composite may be a particle that includes a porous silicon-carbon-based particle provided in at least a portion of the inner part and surface of the porous silicon-based particle. This may be formed by etching silicon oxide to form porous silicon-based particles, such as a Si matrix, and then coating it with carbon. The description of the carbon layer described above may be applied to carbon.

[059] According to one example, porous silicon-based particles can be manufactured by separating silicon oxide phases (e.g., SiO) into Si and silicon dioxide (SiO2) by heat treatment and then etching with an etching agent such as HF. During the heat treatment of silicon oxide, the Si grain size corresponding to peak B can be controlled by a disproportionation reaction (900 to 1400 °C). This makes it possible to adjust the ratio between peaks A, B, and C described above.

[060] According to one exemplary embodiment, the silicon-carbon composite may have a specific surface area of ​​0.5 to 10 m2 / g, measured by the BET method, and a pore volume of 0.005 to 0.03 cm3 / g, and a pore size Petition 870250084307, dated 09 / 18 / 2025, page 22 / 51 13 / 31 from 10 to 20 nm, measured by the BET method. The silicon-carbon composite may have a pore volume of 0.005 to 0.03 cm3 / g, measured by the mercury penetration method (Hg porosimeter).

[061] According to an example embodiment, the silicon-carbon composite may have a particle diameter D90 of 5 to 15 gm, a particle diameter D50 of 1 to 10 gm, a Dmin of 1 to 3 gm, and a Dmax of 17 to 23 gm. In this descriptive report, the average particle diameter (D50) may be defined as a particle diameter corresponding to 50% of the cumulative volume in the particle diameter distribution curve. The average particle diameter (D50) may be measured using, for example, a laser diffraction method. In the laser diffraction method, in general, particle diameters ranging from a submicrometer region to several millimeters may be measured, and results with high reproducibility and high resolution may be obtained.

[062] One exemplary embodiment provides an active negative electrode material including the silicon-carbon composite according to the exemplary embodiments described above.

[063] One exemplary embodiment provides a negative electrode composition including the negative electrode active material, according to the exemplary embodiment described above, a binder and a conductive material.

[064] According to one embodiment of example, the silicon-carbon composite may be included in an amount of 0.1 parts by weight to 14 parts by weight, for example, 0.1 parts by weight to 12 parts by weight, or 1 part by weight to 10 parts by weight, based on 100 parts by weight of the active material of the negative electrode.

[065] According to one exemplary embodiment, the active material of the negative electrode may additionally include a carbon-based active material. The carbon-based active material may be included in an amount of 86 parts by weight or more and 99.9 parts by weight or less, 88 parts by weight or more and 99.9 Petition 870250084307, dated 09 / 18 / 2025, page 23 / 51 14 / 31 parts by weight or less, for example, 90 parts by weight to 99 parts by weight, based on a total of 100 parts by weight of the negative electrode active material included in the negative electrode composition. The carbon-based active material may include at least one part natural graphite and one part artificial graphite. When the carbon-based active material includes both natural and artificial graphite, the weight ratio of artificial graphite to natural graphite may be 1:99 to 99:1, for example, 1:9 to 9:1, or it may be 3:7 to 7:3. For example, based on 100 parts by weight of the carbon-based active material, the natural graphite content may be 10 to 70 parts by weight, and the artificial graphite content may be 30 to 90 parts by weight.

[066] Natural graphite refers to graphite that occurs naturally, and examples of this include flaked graphite, graphite with scales, or soil graphite. Natural graphite has the advantages of being abundant, having a low price, high theoretical capacity and compaction density, and being able to generate high yields.

[067] According to one example, spheroidized natural graphite can be used as natural graphite, and the degree of spheroidization can be 0.9 or more. According to one example, natural graphite can be spheroidized natural graphite and have an apparent density of 0.9 g / cm3 or more.

[068] In this descriptive report, the degree of spheroidization can be, when a particle is projected, a value obtained by dividing the circumference of a circle having the same area as the projected image by the circumferential length of the projected image. The degree of spheroidization can be obtained from a SEM image or, alternatively, it can be measured using a particle shape analyzer, such as the Sysmex FPIA3000, available from Malvern. In addition, the crystal size can be confirmed by XRD analysis.

[069] According to an exemplary embodiment of the present description, the composition of the negative electrode may additionally include a ligand and a conductive material, and the ligand may be an aqueous ligand.

[070] The linker may include at least one selected from the group consisting Petition 870250084307, dated 09 / 18 / 2025, page 24 / 51 15 / 31 in copolymer of polyvinylidene fluoride-hexafluoropropylene (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluorinated rubber, polyacrylic acid and the above-mentioned materials in which a hydrogen is replaced by Li, Na, Ca, etc., and may also include various copolymers thereof.

[071] The conductive material is not particularly limited, provided it has conductivity without causing chemical transformation 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 and thermal black; a conductive fiber, such as a carbon fiber and a metal fiber; a conductive tube, such as a carbon nanotube; fluorocarbon powder, metal powder, such as aluminum powder and nickel powder; a conductive filament, such as zinc oxide and potassium titanate; a conductive metal oxide, such as titanium oxide; a conductive material, such as a polyphenylene derivative, and the like may be used.

[072] According to one embodiment of example, the aqueous binder is included in an amount of 1 to 5% by weight, for example, about 3 to 4% by weight based on the solids content of the negative electrode composition, and the conductive material is included in an amount of 0.1 to 2% by weight, for example, about 1% by weight based on the solids content of the negative electrode composition.

[073] An exemplary embodiment of the present disclosure provides a negative electrode including the negative electrode composition according to the exemplary embodiments described above.

[074] Specifically, the negative electrode may include a negative electrode current collector and a layer of negative electrode active material arranged on at least one surface of the negative electrode current collector. The layer Petition 870250084307, dated 09 / 18 / 2025, page 25 / 51 16 / 31 of the negative electrode active material includes the negative electrode composition according to the example embodiments described above.

[075] The active material layer of the negative electrode can be formed by applying a negative electrode paste including the negative electrode composition described above to at least one surface of a negative electrode current collector, and drying and pressing it with a roller.

[076] The current collector of the negative electrode is not particularly limited, provided it has conductivity without causing chemical transformation in the battery. For example, for the current collector, copper, stainless steel, aluminum, nickel, titanium, burnt carbon, aluminum or stainless steel can be used, each surface treated with carbon, nickel, titanium, silver or similar. Specifically, transition metals that adsorb carbon well, such as copper and nickel, can be used for the current collector. The thickness of the current collector can be from 6 μm to 20 μm. However, the thickness of the current collector is not limited to this.

[077] The negative electrode paste may include a solvent for the formation of the negative electrode paste. Specifically, the solvent for the formation of the negative electrode paste may include at least one selected from the group consisting of distilled water, ethanol, methanol and isopropyl alcohol and, specifically, distilled water, in terms of facilitating the dispersion of the components.

[078] An exemplary embodiment of the present disclosure provides a lithium secondary battery including the negative electrode, according to the exemplary embodiment described above, a positive electrode and a separator.

[079] The positive electrode may include a positive electrode current collector and a layer of positive electrode active material formed over the positive electrode current collector and including the positive electrode active material.

[080] At the positive electrode, the current collector of the positive electrode is not particularly limited, provided it has conductivity without causing transformation. Petition 870250084307, dated 09 / 18 / 2025, page 26 / 51 17 / 31 chemistry in the battery. For example, stainless steel, aluminum, nickel, titanium, burnt carbon, aluminum or stainless steel, with each surface treated with carbon, nickel, titanium, silver or similar, can be used. Furthermore, the current collector of the positive electrode can have a typical thickness of 3 to 500 gm, and a current collector surface can be formed with microscopic irregularities to enhance the adhesion strength of the active material of the positive electrode. For example, the current collector of the positive electrode can be used in various forms, such as film, foil, metal foil, mesh, porous body, foamed body and non-woven fabric body.

[081] The active material of the positive electrode may be a typically used active material of the positive electrode. Specifically, the active material of the positive electrode may be a layered compound, such as a lithium-cobalt oxide (LiCoO2) and a lithium-nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; an iron-lithium oxide, such as LiFe3O; a lithium-manganese oxide, such as the chemical formula Lii+CiMn2-CiO4(O^c1<0.33), LiMnOa, LiMn2O3 and LiMnO2; a copper-lithium oxide (Li2CuO2); a vanadium oxide, such as LiVaOs, V2O5 and Cu2V2O7; a lithium-nickel oxide of the nickel-site type represented by the chemical formula LiNii-c2Mc2O2 (where M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B and Ga, and satisfies 0.01 <c2<0,3);a lithium-manganese composite oxide represented by the chemical formula LiMn2-c3Mc3O2 (where M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn and Ta, and satisfies 0.01 <c3<0,1) ou Li2Mn3MOs (onde M é pelo menos um selecionado do grupo que consiste em Fe, Co, Ni, Cu e Zn); LiMn2O4 em que uma parte do Li da fórmula química é substituída com um íon de metal alcalino terroso, ou semelhante, mas não se limita a isso. O eletrodo positivo pode ser metal Li.;

[082] The active material layer of the positive electrode may include a conductive material of the positive electrode and a positive electrode binder, together with the Petition 870250084307, dated 09 / 18 / 2025, page 27 / 51 18 / 31 active material of the positive electrode described above.

[083] In this case, the conductive material of the positive electrode is used to impart conductivity to the electrode and may be used without specific limitation, provided that the conductive material of the positive electrode has electronic conductivity without causing a chemical transformation in the battery to be constructed. Specific examples may include graphite, such as natural graphite and artificial graphite; a carbon-based material, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black and carbon fiber; metal powders or metal fibers, such as copper, nickel, aluminum and silver; a conductive filament, such as zinc oxide and potassium titanate; a conductive metal oxide, such as titanium oxide; or a conductive polymer, such as a polyphenylene derivative or similar, and any one of the same or a mixture of two or more of the same may be used.

[084] In addition, the positive electrode binder serves to improve the bond between the particles of the active material of the positive electrode and the adhesion force between the active material of the positive electrode and the current collector of the positive electrode. Specific examples may include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluorinated rubber or various copolymers thereof, and the like, any one of them or a mixture of two or more of them may be used.

[085] The separator serves to separate the negative electrode from the positive electrode and to provide a path for lithium ion migration, in which any separator can be used as a separator, without specific limitation, provided it is typically used in a secondary battery. In particular, a separator having high Petition 870250084307, dated 09 / 18 / 2025, page 28 / 51 19 / 31 moisture retention capacity for an electrolytic solution, as well as low resistance to the movement of electrolytic ions, may preferably be used. Specifically, a porous polymer film, for example, a porous polymer film made from a polyolefin-based polymer, such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer and an ethylene / methacrylate copolymer, or a laminated structure having two or more layers thereof, may be used. In addition, a common porous nonwoven fabric, for example, a nonwoven fabric formed from high-melting-point glass fibers, polyethylene terephthalate fibers or the like, may be used.Furthermore, a coated separator including a ceramic component or polymeric material can be used to ensure heat resistance or mechanical strength, and a separator having a single-layer or multi-layer structure can be used selectively.

[086] The secondary lithium battery may additionally include an electrolyte. Examples of electrolytes may include an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, or a molten-type inorganic electrolyte, which may be used in the manufacture of the secondary lithium battery, but are not limited to these.

[087] Specifically, the electrolyte may include a non-aqueous organic solvent and a metal salt.

[088] As a non-aqueous organic solvent, an aprotic organic solvent may be used, for example, such as N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, acid triester Petition 870250084307, dated 09 / 18 / 2025, page 29 / 51 20 / 31 phosphoric, trimethoxyethane, dioxolane derivative, sulfolan, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate or ethyl propionate.

[089] In particular, among carbonate-based organic solvents, ethylene carbonate and propylene carbonate, which are cyclic carbonates, are high-viscosity organic solvents and may be preferentially used because they exhibit high permittivity for dissociating a lithium salt well. When the cyclic carbonate is mixed with a low-viscosity, low-permittivity linear carbonate, such as dimethyl carbonate and diethyl carbonate, in a suitable ratio and used, an electrolyte having high electrical conductivity can be prepared and, therefore, such combined use may be more preferable.

[090] A lithium salt can be used as a metal salt, and the lithium salt is a readily soluble material in non-aqueous electrolytic solution, in which, for example, one or more of those selected from the group consisting of F-, Cl-, I-, NO3-, N(CN)2-, BF< ClO4-, PF6-, (CF3)2PF4-, (CF3)3PF3-, (CF3)4PF2-, (CF^PF-, (CF3)6P-, CF3SO3-, CF3CF2SO3-, (CF3SO2)2N-, (FSO2)2N-, CF3CF2(CF3)2CO-, (CF3SO2)2CH-, (SF5)3C-, (CF3SO2)3C-, CF3(CF2)7SO3-, CF3CO2-, CH3CO2-, SCN- and (CF3CF2SO2)2N- can be used as a lithium salt anion.

[091] One or more additives, for example, a haloalkylene carbonate-based compound, such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexamethyl phosphoric triamide, a nitrobenzene derivative, sulfur, a quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, an ammonium salt, pyrrole, 2-methoxyethanol or aluminum trichloride, may be additionally included in the electrolyte for the purpose of improving battery life characteristics, suppressing a decrease in battery capacity, improving battery discharge capacity and the like, in addition to the electrolyte components described above. Petition 870250084307, dated 09 / 18 / 2025, page 30 / 51 21 / 31

[092] Another embodiment of the present disclosure provides a battery module including the secondary battery as a unit cell and a battery pack including the same. As the battery module and battery pack include the secondary battery having high capacity, high capacity rate and high cycle characteristics, the battery module and battery pack can be used as a power source for a medium to large-sized device selected from the group consisting of an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle and an energy storage system. Method of carrying out the invention

[093] The Examples described herein will be described in detail to specifically describe the present descriptive report. However, the Examples in accordance with the present descriptive report may be modified in other ways, and the scope of the present application is not limited to the following Examples. The Examples in the present application are provided to explain the present descriptive report more fully to a person skilled in the art. Example 1 (1) Preparation of Carbon and Silicon Composite

[094] A disproportionation reaction of SiO was caused by the heat treatment of 20 g of SiOx powder (x = 0.9 to 1) at 1,200 °C in an inert argon gas atmosphere.

[095] After 10 g of the treated SiOx powder (x = 0.9 to 1) had been dispersed in distilled water, 10 ml of a 30% by weight aqueous HF solution were slowly added while stirring the dispersion solution at a speed of 500 RPM. The SiO powder obtained by the above process was stored for 2 hours. The pH of the powder was neutralized by filtration or washing after the above preparation process. The resulting powder was subjected to a drying process at 130 °C for 6 hours under vacuum, to prepare porous silicon. Then, pulverization was carried out with a pestle and mortar, so that the size of Petition 870250084307, dated 09 / 18 / 2025, page 31 / 51 22 / 31 particle size was D50 from 4 to 6 gm. Then, a silicon-carbon composite including a carbon layer was prepared by reacting porous silicon with acetylene (C2H2) at 1 L / min at 10-1 torr (133.32 kPa) and 720 °C for about 5 hours under an inert gas, Ar atmosphere using a CVD apparatus to form a carbon layer on the surface of the porous silicon. The result of the NMR analysis is shown in FIG. 1. According to FIG. 1, peaks corresponding to peaks A, B and C appeared, and the ratio (B + C) / A was measured as 3.3. (2) Preparation of the Negative Electrode

[096] A negative electrode paste was prepared by mixing an active negative electrode material, including the prepared silicon-carbon composite and graphite, in a weight ratio of 9:91; a conductive material, including carbon black and SWCNT; and a binder, including carboxymethylcellulose (CMC) and styrene-butadiene rubber (SBR), in a weight ratio of 95.3:1:3.6, adding an appropriate amount of distilled water, so that the total solids content was about 46% by weight.

[097] The negative electrode paste was applied to a thin Cu metal film approximately 20 gm thick, which was then dried at a circulating air temperature of 60 °C. The thin film was then roller-pressed, dried in a vacuum oven at 130 °C for about a day, and punched into a circular shape of 1.4875 cm2 to prepare a negative electrode. (3) Preparation of the Secondary Battery

[098] A thin film of perforated Li metal with 1.7671 cm2 was used as a positive electrode. A lithium coin-type half-cell was prepared by interposing a porous polyethylene separator between the positive and negative electrodes and injecting an electrolyte solution in which 1 M LiPF6 was dissolved in a mixed solution prepared by mixing EMC (methyl ethyl carbonate) and EC (ethylene carbonate) in a 7:3 ratio, and an additive was included. Example 2 Petition 870250084307, dated 09 / 18 / 2025, page 32 / 51 23 / 31

[099] A silicon-carbon composite was prepared in the same manner as in Example 1, except that the temperature of the disproportionation reaction was adjusted to 1150 °C and the carbon layer was prepared by reacting porous silicon with acetylene (C2H2) at 700 °C. A result of the NMR analysis of the active material prepared by the method of Example 2 is shown in FIG. 2. According to FIG. 2, peaks corresponding to peaks A, B and C appeared, and the ratio (B + C) / A was measured to be 3.5.

[0100] Using the prepared silicon-carbon composite, a negative electrode and a secondary battery were prepared in the same manner as in Example 1.

[0101] FIG. 7 shows the waveform analysis result from the NMR analysis result of FIG. 2. The silicon-carbon composite of Example 2 presents peaks (1) to (6), of which peak (1) corresponds to peak A, peaks (2), (4), (5) and (6) correspond to peak B, and peak (3) corresponds to peak C. When calculating the ratio (B + C) / A, B was calculated as the sum of the intensities of peaks (2), (4), (5) and (6). Example 3

[0102] A silicon-carbon composite was prepared in the same manner as in Example 1, except that the disproportionation reaction temperature was set to 1000 °C and the carbon layer was prepared by reacting porous silicon with acetylene (C2H2) at 750 °C. A result of the NMR analysis of the active material prepared by the method of Example 3 is shown in FIG. 3. According to FIG. 3, peaks corresponding to peaks A, B, and C appeared, no peak appeared from -205 ppm to -300 ppm, and the ratio (B + C) / A was measured to be 2.1.

[0103] Using the prepared silicon-carbon composite, a negative electrode and a secondary battery were prepared in the same manner as in Example 1. Example 4

[0104] A silicon-carbon composite was prepared in the same way as Petition 870250084307, dated 09 / 18 / 2025, page 33 / 51 24 / 31 in Example 1, except that the disproportionation reaction temperature was adjusted to 900 °C and the carbon layer was prepared by reacting porous silicon with acetylene (C2H2) at 770 °C. As a result of the NMR analysis of the active material prepared by the method of Example 4, according to FIG. 4, peaks corresponding to peaks A, B and C appeared, and the ratio (B + C) / A was measured to be 1.4.

[0105] Using the prepared silicon-carbon composite, a negative electrode and a secondary battery were prepared in the same manner as in Example 1. Comparative Example 1 (1) Method for Preparing Magnesium-Containing Silicon Oxide

[0106] Si and SiO2 were mixed in a 1:1 molar ratio in crucible no. 1 and heated to a sublimation temperature of 1400 °C. In crucible no. 2, magnesium metal was heated separately to 600–1000 °C and evaporated. All crucibles were depressurized to 0.1 torr (13.33 kPa). The vaporous mixture containing Mg obtained from crucibles no. 1 and no. 2 was reacted for 6 hours and then condensed to a solid phase in a vacuum region of 800 °C. The silicon-based active material prepared by the above method was pulverized for 3–4 hours using a ball mill apparatus to prepare particles with a D50 of approximately 6 μm. Next, a magnesium-containing silicon oxide was prepared by reacting the particles with methane (CH4) at 1 L / min at 10-1 torr (133.32 kPa) for about 5 hours under an inert Ar gas atmosphere, using a CVD apparatus to form a carbon layer on a surface of the silicon-based active material.The Mg content in the powder was analyzed by ICP-MS and measured to be 8% by weight.

[0107] As a result of the NMR analysis of the silicon oxide prepared by the method, according to FIG. 5, the peaks corresponding to peaks B and C appeared, peak A did not appear and the ratio (B + C) / A was not measurable because there was no peak A.

[0108] Using the prepared silicon-carbon composite, an active material of Petition 870250084307, dated 09 / 18 / 2025, page 34 / 51 A 25 / 31 negative electrode was prepared to include the prepared silicon-carbon composite and graphite in a mass ratio of 15:85, and a negative electrode and a secondary battery were prepared in the same manner as in Example 1. Comparative Example 2

[0109] A silicon oxide was prepared by the same method as in Comparative Example 1, except that the active material was prepared without the magnesium metal in crucible no. 2 of Comparative Example 1. As a result of the NMR analysis of the silicon oxide prepared by the method, according to FIG. 5, peaks corresponding to peaks B and C appeared, peak A did not appear, and the ratio (B + C) / A was not measurable because there was no peak A.

[0110] Using the prepared silicon-carbon composite, a negative electrode active material was prepared to include the prepared silicon-carbon composite and graphite in a mass ratio of 12:88, and a negative electrode and a secondary battery were prepared in the same manner as in Example 1. Comparative Example 3

[0111] The same method as in Example 1 was performed, except that the temperature of the CVD carbon coating process, which was performed for porous silicon using acetylene (C2H2) in Example 1, was adjusted to 900 °C. As a result of the NMR analysis of the silicon-carbon composite prepared in this way, peaks corresponding to peaks A, B, and C appeared, and the ratio (B + C) / A was measured to be 0.8.

[0112] Using the prepared silicon-carbon composite, a negative electrode and a secondary battery were prepared in the same manner as in Example 1. Comparative Example 4

[0113] A gaseous mixture of 1 L / min of silane, 3 L / min of acetylene, and 1 L / min of argon was introduced into a deposition chamber of a fluidized bed reactor at a temperature of 700 °C and a pressure of 1 atm. A silicon composite Petition 870250084307, dated 09 / 18 / 2025, page 35 / 51 26 / 31 carbon was obtained in the collection chamber of the fluidized bed reactor. As a result of the NMR analysis of the silicon-carbon composite prepared in this way, peaks corresponding to peaks A, B and C appeared, and the ratio (B + C) / A was measured to be 2.8.

[0114] Using the prepared silicon-carbon composite, a negative electrode active material was prepared, including the prepared silicon-carbon composite and graphite in a mass ratio of 11:89, and a negative electrode and a secondary battery were prepared in the same manner as in Example 1. Comparative Example 5

[0115] 1 kg of silicon powder and 1 kg of silica powder were placed in a vacuum reactor, and a vacuum was initially formed at 0.1 torr (13.33 kPa) or less. The materials were then heated to 1400 °C, converting them to vapor. Simultaneously, a benzene solution was slowly passed through, causing the benzene to vaporize rapidly. After the benzene vapor was completely mixed with the vapor of the silicon / silica mixture, the mixed vapor was cooled and deposited onto a water-cooled substrate. The resulting material was ground to obtain silicon oxide, into which carbon atoms were uniformly inserted at the atomic level. The ground material was then coated with carbon, and 1 kg of the material was placed in a rotary kiln, heated to 1000 °C under an atmosphere of argon shielding gas.A mixed gas of argon and equal amounts of propylene and methane was introduced in a 1:1 volume ratio into the vapor coating, with the propylene to methane volume ratio being 2:3. After maintaining the temperature for 1 hour and cutting off the organic gas supply, the material was cooled to obtain silicon oxide. As a result of the NMR analysis of the silicon-carbon composite prepared in this way, according to FIG. 5, peaks corresponding to peaks B and C appeared, peak A did not appear, and the ratio (B + C) / A was not measurable because there was no peak A. Petition 870250084307, dated 09 / 18 / 2025, pp. 36 / 51 27 / 31

[0116] Using the prepared silicon-carbon composite, an active negative electrode material was prepared, including the prepared silicon-carbon composite and graphite in a mass ratio of 12:88, and a negative electrode and a secondary battery were prepared in the same manner as in Example 1. Comparative Example 6

[0117] The same method as in Example 1 was performed, except that the temperature of the disproportionation reaction was set to 1250 °C and the temperature of the CVD carbon coating process, which is performed for porous silicon using acetylene (C2H2) in Example 1, was set to 650 °C. A result of the NMR analysis of the active material prepared by the method of Comparative Example 6 is shown in FIG. 6. According to FIG. 6, peaks corresponding to peaks A, B, and C appeared, and the ratio (B + C) / A was measured to be 1.1.

[0118] Using the prepared silicon-carbon composite, a negative electrode active material was prepared to include the prepared silicon-carbon composite and graphite in a 15:85 weight ratio, and a negative electrode and a secondary battery were prepared in the same manner as in Example 1.

[0119] The peak ratios specified by NMR analysis of silicon-based active materials prepared in the Examples and Comparative Examples are shown in Table 1 below.

[0120] In addition, the C, O and Si contents of each sample and comparative sample were measured using a carbon-sulfur analyzer (CS Analyzer) and an oxygen-nitrogen-hydrogen analyzer (ONH Analyzer), and the results of the same and the weight ratio of the silicon-carbon composite to the graphite included in the active material of the negative electrode are shown in Table 2 below. [Battery Performance Assessment]

[0121] The prepared batteries were charged and discharged to evaluate discharge capacity, initial efficiency, and capacity retention rate, and Petition 870250084307, dated 09 / 18 / 2025, page 37 / 51 28 / 31 The evaluation results are shown in Table 1 below.

[0122] Charging and discharging were performed at 0.1 °C in the first and second cycles, and charging and discharging were performed at 0.5 °C from the third to the 49th cycle. In the 50th cycle, charging and discharging were terminated in the charged state (with lithium contained in the negative electrode).

[0123] Load conditions: DC (constant current) / CV (constant voltage) (current cutoff of 5 mV / 0.005 °C)

[0124] Discharge conditions: DC (constant current) condition 1.5 V

[0125] The discharge capacity (mAh / g) and initial efficiency (%) were derived from the result after the first charge and discharge. Specifically, the initial efficiency (%) was derived by the following calculation: Initial efficiency (%) = (first discharge capacity / first load capacity) x 100%

[0126] The capacity retention rate was derived by the following calculation.

[0127] Capacity retention rate (%) = (discharge capacity on the 49th time / discharge capacity on the first time) x 100% [Water-Based Processability Assessment] 1) Evaluation of Processability Characteristics (shear viscosity)

[0128] As part of the processability assessment, the amounts of variation in shear viscosity at a shear rate = 1 Hz of a paste prepared in the Examples and Comparative Examples are shown in Table 2 below. Specifically, the amount of variation (%) in shear viscosity was derived by the following calculation formula. Percentage change in shear viscosity = ((shear viscosity of the paste after 48 h - shear viscosity of the paste immediately after mixing) / shear viscosity of the paste immediately after mixing) x 100% Petition 870250084307, dated 09 / 18 / 2025, pp. 38 / 51 29 / 31 2) Gas Generation Moment

[0129] After 20 g of paste were placed in a 10 x 15 cm aluminum bag and vacuum sealed, a volume change was measured using Archimedes' principle, and a moment when a volume change of 2 mL or more occurred at 60 °C was defined as a gas generation moment. [Table 1] NMR Battery Ratio of (B + C) / A Discharge Capacity (mAh / g) Initial Efficiency (%) Capacity Retention Rate (%) 100 Cycles Amount of Change (%) in Shear Viscosity 0 Gas Generation Momentum (day) Example 1 3.3 494 90 90 0 8 Example 2 3.5 489 89 92 0 8 Example 3 2.1 476 89 89 0 8 Example 4 1.4 465 88 87 0 8 Comparative Example 1 445 86 85 2 7 Comparative Example 2 455 85 82 2 7 Comparative Example 3 0.8 300 80 50 0 Comparative Example 4 2.8 513 89 82 40 2 Comparative Example 5 - 463 87 81 2 7 Petition 870250084307, dated 09 / 18 / 2025, pp. 39 / 51 30 / 31 NMR Battery ratio of (B + C) / A Discharge capacity (mAh / g) Initial efficiency (%) Capacity retention rate (%) 100 cycles Amount of variation (%) in shear viscosity 0 Gas generation moment (day) Example Comparative 6 1.1 535 89 50 45 2 [Table 2] Carbon content (%) based on silicon-carbon composite Oxygen content (%) based on silicon-carbon composite Silicon content (%) based on silicon-carbon composite Weight ratio of silicon-carbon composite to graphite Example 1 38.6 1.2 60.2 9:91 Example 2 43 0.4 56.6 9:91 Example 3 40 1 59 9:91 Example 4 40 1.7 58.3 9:91 Comparative Example 1 (Mg content: 8%) 3.5 30.9 57.6 15:85 Comparative Example 2 3.5 34.0 62.5 12:88 Comparative Example 3 40 1 59 9:91 Comparative Example 4 55 1 44 11:89 Comparative Example 5 0.9 35.5 63.6 12:88 Petition 870250084307, dated 09 / 18 / 2025, pages 40 / 51 31 / 31 Comparative Example 6 40 1.1 58.9 15:85

[0130] In Examples 1 to 4, materials with peaks corresponding to peaks A, B, and C and satisfying the peak ratio covered by the scope of this disclosure were applied to the battery. As shown in Table 1, although certain or more effects were achieved in terms of discharge capacity, initial efficiency, and capacity retention rate, the variation in viscosity and gas generation remained below a certain level.

[0131] On the other hand, Comparative Examples 1, 2, and 5, which do not satisfy the peak ratio mentioned above, resulted in inferior effects on both capacity and aqueous processability. Specifically, in Comparative Examples 1, 2, and 5, an adequate amount of SiC was not generated, so peak A did not appear in the NMR analysis. Consequently, aqueous processability was poor due to reactions with the electrolyte. In Comparative Example 3, the temperature was too high during carbon layer formation, leading to the generation of an excessive amount of SiC, which did not contribute to capacity, thus degrading cell performance.

[0132] Although Comparative Example 4 met the peak ratio of this disclosure, the carbon content in the silicon-carbon composite was too high, causing exposure of the surface silicon and resulting in side reactions with water, which led to inferior aqueous processability.

[0133] In the case of Comparative Example 6, although it did not meet the peak ratio of this disclosure, the excessive inclusion of silicon-carbon composite in the active material of the negative electrode resulted in lower cycle performance and aqueous processability. Petition 870250084307, dated 09 / 18 / 2025, pages 41 / 51

Claims

1 / 4 CLAIMS 1. Silicon-carbon composite, CHARACTERIZED in that it satisfies a condition of 1.3 < ((B + C) / A) < 4, wherein A is an intensity of peak A having a chemical shift value in the range of 20 ppm to -15 ppm in a 29Si-MAS NMR spectrum, B is an intensity of peak B having a chemical shift value in the range of -20 ppm to -100 ppm in the 29Si-MAS NMR spectrum; and C is an intensity of peak C having a chemical shift value in the range of -110 ppm to -140 ppm in the 29Si-MAS NMR spectrum.

2. Silicon-carbon composite according to claim 1, CHARACTERIZED in that the silicon-carbon composite comprises carbon in an amount of 38 parts by weight to 50 parts by weight, based on 100 parts by weight of the silicon-carbon composite.

3. Silicon-carbon composite according to claim 1, CHARACTERIZED in that the silicon-carbon composite is a particle comprising a porous silicon-carbon based particle arranged in at least a portion of an internal part and a surface of the porous silicon-based particle.

4. Silicon-carbon composite according to claim 1, the silicon-carbon composite CHARACTERIZED in that it further comprises a carbon layer formed on a surface of the silicon-carbon composite, wherein the total weight of the carbon layer is from 5% by weight to 40% by weight, based on 100% by weight of the silicon-carbon composite.

5. Silicon-carbon composite according to claim 1, the silicon-carbon composite CHARACTERIZED in that it has a specific surface area of ​​BET of 0.5 to 10 m2 / g.

6. Silicon-carbon composite according to claim 1, the silicon-carbon composite Petition 870250084307, dated 09 / 18 / 2025, page 42 / 51 2 / 4 CHARACTERIZED in that it has a pore volume of 0.005 to 0.03 cm3 / g.

7. Silicon-carbon composite according to claim 1, the silicon-carbon composite CHARACTERIZED in that it has a pore size of 10 nm to 20 nm.

8. Silicon-carbon composite according to claim 1, the silicon-carbon composite CHARACTERIZED in that it has a particle diameter D90 of 5 to 15 gm, a particle diameter D50 of 1 to 10 gm, a Dmin of 1 to 3 gm and a Dmax of 17 to 23 gm.

9. Active material of the negative electrode, CHARACTERIZED in that it comprises the silicon-carbon composite as defined in any one of claims 1 to 8.

10. Active material of the negative electrode according to claim 9, CHARACTERIZED in that the active material of the negative electrode comprises a silicon-carbon composite in an amount of 0.1 parts by weight to 14 parts by weight, based on 100 parts by weight of the active material of the negative electrode.

11. Negative electrode active material according to claim 9, the negative electrode active material CHARACTERIZED in that it additionally includes a carbon-based active material, and wherein the carbon-based active material is included in an amount of 86 parts by weight or more and 99.9 parts by weight or less based on 100 parts by weight of the negative electrode active material.

12. Negative electrode composition, CHARACTERIZED in that it comprises: the active material of the negative electrode as defined in claim 9; a binder; and a conductive material.

13. Negative electrode composition according to claim 12, Petition 870250084307, dated 09 / 18 / 2025, page 43 / 51 3 / 4 CHARACTERIZED in that the active material of the negative electrode additionally comprises a carbon-based active material.

14. Negative electrode, CHARACTERIZED in that it comprises the negative electrode composition as defined in claim 12.

15. Secondary lithium battery, CHARACTERIZED in that it comprises: the negative electrode as defined in claim 14; a positive electrode; and a separator.

16. Battery module, CHARACTERIZED in that it comprises the secondary lithium battery as defined in claim 15.

17. Battery pack, CHARACTERIZED in that it comprises the secondary lithium battery as defined in claim 15.

18. Battery pack, CHARACTERIZED in that it comprises the battery module as defined in claim 16.

19. Method for preparing a silicon-carbon composite, the method CHARACTERIZED in that it comprises: carrying out a disproportionation reaction by heat treatment of a silicon oxide powder; etching the heat-treated silicon oxide powder with an etching agent; and obtaining a silicon-based porous particle by pulverizing the etched silicon oxide powder; and forming a silicon-carbon composite by reacting the silicon-based porous particle with a carbon source to form a carbon layer on the surface of the silicon-based porous particle, wherein the silicon-carbon composite satisfies a condition of 1.3 < ((B + C) / A) < 4, Petition 870250084307, dated 09 / 18 / 2025, p.44 / 51 4 / 4 where A is the intensity of a peak A having a chemical shift value in the range of 20 ppm to -15 ppm in a 29Si-MAS NMR spectrum, B is the intensity of a peak B having a chemical shift value in the range of -20 ppm to -100 ppm in the 29Si-MAS NMR spectrum; and C is the intensity of a peak C having a chemical shift value in the range of -110 ppm to -140 ppm in the 29Si-MAS NMR spectrum. Petition 870250084307, dated 09 / 18 / 2025, p. 45 / 51.

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