Silicon-carbon-containing electrode material, method for preparing same, and lithium secondary battery comprising same

Abstract

A silicon-carbon-containing electrode material according to an embodiment of the present invention comprises: a porous carbon structure comprising pores; and a silicon-containing coating layer formed on the porous carbon structure, and the silicon-containing electrode material has a peak intensity percentage of a Raman spectrum defined by a predetermined formula of 3% to 18%. Therefore, the life characteristics and capacity characteristics of the lithium secondary battery can be improved.

Description

Technical Field

[0001] This invention relates to a silicon-carbon electrode material, its preparation method, and a lithium secondary battery comprising the electrode material. More specifically, this invention relates to a silicon-carbon electrode material comprising porous carbon material and a lithium secondary battery comprising the electrode material. Background Technology

[0002] Rechargeable batteries are batteries that can be repeatedly charged and discharged. With the development of the information communication and display industries, rechargeable batteries are widely used as power sources for portable electronic communication devices such as portable cameras, mobile phones, and laptops. Battery packs, including rechargeable batteries, are also used as power sources for environmentally friendly vehicles such as electric cars.

[0003] Secondary batteries can be categorized into, for example, lithium secondary batteries, nickel-cadmium batteries, and nickel-metal hydride batteries. Among them, lithium secondary batteries have high operating voltage and energy density per unit weight, and are advantageous for charging speed and lightweight design.

[0004] For example, a lithium secondary battery may include: an electrode assembly comprising a positive electrode, a negative electrode, and a separator; and an electrolyte impregnating the electrode assembly. The lithium secondary battery may also include an outer packaging material, such as a pouch-type packaging material, to house the electrode assembly and the electrolyte.

[0005] To manufacture lithium-ion batteries with higher capacity and power, silicon and carbon can be combined and used as anode materials. For example, silicon can improve the battery's capacity characteristics, while carbon can act as a support for silicon. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] One technical problem of the present invention is to provide a silicon-carbon electrode material with improved lifetime and capacity characteristics.

[0008] One technical problem of the present invention is to provide a method for preparing the silicon-carbon electrode material.

[0009] One technical problem of the present invention is to provide a lithium secondary battery with improved lifespan and capacity characteristics.

[0010] (II) Technical Solution

[0011] A silicon-carbon electrode material according to an exemplary embodiment comprises: a porous carbon structure including pores; and a silicon-containing coating formed on the porous carbon structure. The peak intensity percentage of the Raman spectrum of the silicon-carbon electrode material as defined by Formula 1 can be from 3% to 18%.

[0012] [Formula 1]

[0013] Peak intensity percentage = (I B / I A ) 100

[0014] In Equation 1, I A It can be based on the 2300 cm⁻¹ of the Raman spectrum. -1 Up to 3120cm -1 The wavenumber range is 2500cm at the baseline. -1 Up to 3000cm -1 The maximum peak intensity at I B It can be used for Raman spectra at 1850 cm⁻¹ -1 Up to 2200cm -1 Wavenumber range is 2080cm at baseline. -1 Up to 2120cm -1 The maximum value of the peak intensity at that location.

[0015] In some implementations, the percentage of peak intensity of the Raman spectrum measured from the electrode material can be from 4% to 15%.

[0016] In some embodiments, the percentage of peak intensity of the Raman spectrum measured from the electrode material can be from 4.73% to 13.85%.

[0017] In some embodiments, the silicon content in the total weight of the silicon-carbon electrode material can be from 38% to 60% by weight.

[0018] In some embodiments, the silicon content in the total weight of the silicon-carbon electrode material can be from 45% to 55% by weight.

[0019] In some embodiments, the silicon content in the total weight of the silicon-carbon electrode material can be from 35.9% to 49.3% by weight.

[0020] In a method for preparing a silicon-carbon electrode material according to an exemplary embodiment, a porous carbon structure containing pores can be prepared. A silicon source gas can be supplied to the porous carbon structure within a reactor to form a silicon-containing coating on the porous carbon structure. The pressure inside the reactor can be reduced to a range of 10 Torr to 150 Torr to obtain the silicon-carbon electrode material.

[0021] In some implementations, the percentage of peak intensity of the Raman spectrum measured from the silicon-carbon electrode material, as defined by Formula 1, can be from 3% to 18%.

[0022] [Formula 1]

[0023] Peak intensity percentage = (I B / I A ) 100

[0024] In Equation 1, I A It can be based on the 2300 cm⁻¹ of the Raman spectrum. -1 Up to 3120cm -1 Wavenumber range is 2500cm at baseline. -1 Up to 3000cm -1 The maximum peak intensity at I B It can be used for Raman spectra at 1850 cm⁻¹ -1 Up to 2200cm -1 Wavenumber range is 2080cm at baseline. -1 Up to 2120cm -1 The maximum value of the peak intensity at that location.

[0025] In some implementations, the silicon source gas can be supplied at a temperature of 300°C to 600°C.

[0026] In some implementations, the supply of the silicon source gas can be carried out for 2 to 8 hours.

[0027] In some embodiments, the silicon source gas may be a mixture of silane gas and non-reactive gas.

[0028] In some implementations, the decompression can be performed at a temperature between 200°C and 600°C.

[0029] In some implementations, the decompression can be performed for 0.5 hours to 3.5 hours.

[0030] In some implementations, the decompression can be performed in a non-reactive gas atmosphere.

[0031] A lithium secondary battery according to an exemplary embodiment may include: a negative electrode comprising a silicon-carbon electrode material according to the above embodiment; and a positive electrode disposed opposite to the negative electrode.

[0032] (III) Beneficial Effects

[0033] According to an exemplary embodiment, the silicon-carbon electrode material may comprise: a porous carbon structure; and a silicon-containing coating formed on the porous carbon structure.

[0034] The percentage of peak intensity in the Raman spectrum measured from the silicon-carbon electrode material, as defined by the prescribed formula, can be from 3% to 18%. Therefore, the porous carbon structure can contain an appropriate amount of unreacted silane (SiH4) gas.x It can also improve the lifespan and power characteristics of lithium secondary batteries.

[0035] The electrode material can be widely used in green technology fields such as electric vehicles, battery charging stations, and other battery-powered solar and wind power generation. Furthermore, the lithium secondary battery can be used in eco-friendly electric vehicles and hybrid vehicles to prevent climate change by suppressing air pollution and greenhouse gas emissions. Attached Figure Description

[0036] Figure 1 and Figure 2 These are schematic plan views and schematic cross-sectional views of a lithium secondary battery according to an exemplary embodiment.

[0037] Figure 3 This is a flowchart illustrating a method for preparing a silicon-carbon electrode material according to an exemplary embodiment.

[0038] Figures 4a to 4d These are Raman spectra of silicon-carbon electrode materials according to Examples 2, 3, Comparative Example 1, and Comparative Example 2, respectively.

[0039] Figure 5a The diagram shows the Raman spectra of the silicon-carbon electrode materials according to Examples 2, 3, Comparative Example 1 and Comparative Example 2.

[0040] Figure 5b It is a magnified view of a specific area, simultaneously showing the Raman spectra of silicon-carbon electrode materials according to Examples 2, 3, Comparative Example 1 and Comparative Example 2.

[0041] Explanation of reference numerals in the attached figures:

[0042] 100: Positive electrode; 105: Positive electrode current collector

[0043] 107: Positive electrode lead; 110: Positive electrode active material layer

[0044] 120: Negative electrode active material layer; 125: Negative electrode current collector

[0045] 127: Negative lead; 130: Negative electrode

[0046] 140: Diaphragm; 150: Electrode assembly

[0047] 160: Casing Detailed Implementation

[0048] Embodiments of the present invention provide a silicon-carbon electrode material comprising: a porous carbon structure; and a silicon-containing coating formed on the porous carbon structure. Embodiments of the present invention can provide a negative electrode for a lithium secondary battery and a lithium secondary battery comprising the electrode material.

[0049] According to an exemplary embodiment, the electrode material can be used as a negative electrode material for a lithium secondary battery. The application of the electrode material is not limited to that of a negative electrode material; it can be used as a material with conductivity or charge storage properties in various electrical devices, electronic devices, and electrochemical devices.

[0050] The embodiments of the present invention will now be described in detail. However, these are merely exemplary embodiments, and the present invention is not limited to the specific embodiments described herein.

[0051] <Silicon-Carbon Electrode Materials>

[0052] According to an exemplary embodiment, the silicon-carbon electrode material may comprise: a porous carbon structure; and a silicon-containing coating formed on the porous carbon structure.

[0053] In some embodiments, the porous carbon structure may comprise a carbonized polymer, for example, the porous carbon structure may comprise at least one selected from activated carbon, carbon nanotubes (CNTs), carbon nanowires, graphene, carbon fiber, carbon black, graphite, porous carbon (microporous carbon / mesoporous carbon / macroporous carbon), pyrolytic cryogel, pyrolytic xerogel, and pyrolytic aerogel.

[0054] For example, the cross-section of a porous carbon structure can be circular or can be randomly varied from said circle.

[0055] According to an exemplary embodiment, the silicon-containing coating may be partially formed in the internal pores and on the surface of the porous carbon structure. Alternatively, the silicon-containing coating may be formed simultaneously in the internal pores and on the surface of the porous carbon structure.

[0056] In some embodiments, the pores of the porous carbon structure described above can be at least partially filled by the silicon-containing coating. For example, the pores can be completely filled by the silicon-containing coating, or they can be partially filled by the silicon-containing coating.

[0057] When the pores are partially filled by the silicon-containing coating, the interior space of the pores may further include the remaining space in addition to the portion filled by the silicon-containing coating.

[0058] In some embodiments, the silicon-containing coating can be formed by a deposition process, such as chemical vapor deposition (CVD) or thermal evaporation.

[0059] In some embodiments, a silicon precursor, such as silane gas (SiH4), can be supplied to the porous carbon structure to form the pores. Silicon particles separated from the silicon precursor can be deposited on the porous carbon structure to form the silicon-containing coating.

[0060] In some implementations, the resulting silicon-containing coating may contain unreacted materials (e.g., SiH). x For example, when silane gas is not completely decomposed, the unreacted products of the silane gas (SiH) x The unreacted material can be formed on the porous carbon structure. When the amount of unreacted material increases excessively, the instability of the negative electrode active material during repeated charging / discharging increases, potentially leading to a decrease in lifetime characteristics due to gas generation. Furthermore, side reactions may be initiated during the lithium intercalation reaction. However, the presence of an appropriate amount of unreacted material can improve the electronic conductivity and reactivity with Li of the silicon-containing coating.

[0061] In some embodiments, the silicon content in the total weight of the silicon-carbon electrode material can be from 38% to 60% by weight. In some embodiments, the silicon content in the total weight of the silicon-carbon electrode material can be from 45% to 55% by weight, 45% to 50% by weight, 48% to 55% by weight, 49% to 53% by weight, or 35.9% to 49.3% by weight.

[0062] Within the aforementioned range, the electrolyte will not penetrate into the pores of the porous carbon structure, while the porous carbon structure can contain sufficient pores to suppress the volume expansion of silicon. Therefore, the lifespan characteristics of lithium-ion batteries can be improved.

[0063] According to an exemplary implementation, the percentage of peak intensity of the Raman spectrum measured from the electrode material, as defined by Formula 1, can be from 3% to 18%.

[0064] [Formula 1]

[0065] Peak intensity percentage = (I B / I A ) 100

[0066] In Equation 1, I A For Raman spectra at 2300 cm⁻¹ -1 Up to 3120cm -1 Wavenumber range is 2500cm at baseline. -1 Up to 3000cm -1 The maximum peak intensity at I B For Raman spectra at 1850 cm⁻¹ -1 Up to 2200cm -1 Wavenumber range is 2080cm at baseline. -1 Up to 2120cm -1 The maximum value of the peak intensity at that location.

[0067] For example, in Equation 1, I A I can be the maximum peak intensity at the 2D spectral band of carbon contained in the porous carbon structure. B It can be the unreacted product of the above-mentioned silane gas (SiH). x The maximum value of the peak intensity related to the Si-H bond, wherein the peak intensity percentage can represent the degree of formation of the unreacted substance.

[0068] For example, when the peak intensity percentage of the Raman spectrum exceeds 18%, the amount of unreacted material on the porous carbon structure increases excessively, and side reactions may be initiated due to the Si-H bonds of the unreacted material during lithium ion insertion at the negative electrode. Therefore, the lifespan characteristics of the lithium secondary battery may be reduced.

[0069] For example, when the peak intensity percentage of the Raman spectrum is less than 3%, the amount of unreacted material on the porous carbon structure is excessively reduced, which may lead to a decrease in the electronic conductivity of the electrode material. Therefore, the lifetime characteristics of the lithium secondary battery may be reduced.

[0070] In some embodiments, the peak intensity percentage of the Raman spectrum can be 4% to 15%. In some embodiments, the peak intensity percentage of the Raman spectrum can be 4% to 14%, 5% to 14%, or 6% to 10%. In some embodiments, the peak intensity percentage of the Raman spectrum can be 4.73% to 13.85%.

[0071] Within the aforementioned range, a suitable amount of the unreacted material can be formed on the porous carbon structure, which can improve the lifespan characteristics of lithium secondary batteries.

[0072] The Raman spectroscopy analysis can be performed using Raman spectrometers of a type known in the art (e.g., the inVia Raman Microscope from Renishaw). For example, the laser wavelength of the Raman spectrometer can be, for example, from about 532 nm to about 785 nm, the laser power can be from about 0.01 mW to about 0.5 mW, the laser exposure time can be from about 5 seconds to about 20 seconds, and the number of scans can be from 5 to 20. For example, the detector of the Raman spectrometer can be a CCD (e.g., a 1024 StreamLine CCD array detector).

[0073] For example, the Raman spectroscopy analysis can be performed at 1800 cm⁻¹. -1 Up to 3200cm -1 Within the range, 20 to 50 selected points are magnified at 50x magnification.

[0074] Figure 3 This is a flowchart illustrating a method for preparing a silicon-carbon electrode material according to an exemplary embodiment.

[0075] Reference Figure 3 Porous carbon structures containing pores can be prepared (e.g., step S10).

[0076] In some embodiments, the porous carbon structure can be prepared from a resol oligomer, a hydroxyl-containing aromatic compound and an aldehyde compound.

[0077] For example, the hydroxyl-containing aromatic compound may be phenol, and the aldehyde compound may be formaldehyde. For example, the prepared methyl phenolic resin oligomer may include divinylbenzene.

[0078] According to an exemplary embodiment, the porous carbon structure can be activated. Through this activation, the activity of the pore structure of the porous carbon structure can be controlled.

[0079] For example, the activation can be carried out by a physical activation method, in which a reactive gas (water vapor, carbon dioxide gas, inert gas or a mixture thereof) is injected and heat-treated at a temperature of 700°C to 1000°C.

[0080] For example, the activation can be carried out by a chemical activation method, in which acidic chemicals such as KOH, Na2CO3, NaOH, and H3PO4, as well as alkaline chemicals, are used as activators, and the activation is carried out at a lower temperature than that of physical activation methods.

[0081] According to an exemplary implementation, the activation can be performed for more than 2 hours. For example, the activation can be performed for more than 2 hours but less than 5 hours.

[0082] According to an exemplary embodiment, the pore size of the porous carbon structure prepared by the activation can be less than 20 nm or from 1 nm to 20 nm.

[0083] According to an exemplary embodiment, the specific surface area of ​​the porous carbon structure prepared by the activation can be 100 m². 2 / g to 2000m 2 / g or 1000m 2 / g to 2000m 2 / g.

[0084] Corresponding to the above specific surface area range, silicon and additional elements can be formed on the surface of the porous carbon structure in a controlled manner.

[0085] According to an exemplary implementation, a silicon-containing coating can be formed on the porous carbon structure (e.g., step S20).

[0086] For example, a silicon source gas can be supplied to the porous carbon structure within a reactor to form a silicon-containing coating on the porous carbon structure. The silicon-containing coating can be formed, for example, by chemical vapor deposition (CVD) or physical vapor deposition (PVD).

[0087] In some embodiments, the silicon source gas may be a mixture of silane gas and non-reactive gas; for example, the silicon source gas may contain silane gas.

[0088] In some embodiments, the non-reactive gas may include at least one selected from helium, nitrogen, neon, argon, krypton, and xenon. For example, the non-reactive gas may be nitrogen.

[0089] In some embodiments, the silicon source gas can be supplied at a temperature of 300°C to 600°C. In some embodiments, the silicon source gas can be supplied within a temperature range of 350°C to 580°C, 380°C to 570°C, or 400°C to 550°C.

[0090] In some embodiments, the silicon source gas can be supplied at a pressure range of 600 to 760 Torr. In some embodiments, the silicon source gas can be supplied at a pressure range of 650 to 760 Torr or 740 to 760 Torr.

[0091] Within the aforementioned temperature and pressure range of the silicon source gas supply, the silicon content in the total weight of the electrode material can be easily adjusted to the aforementioned range.

[0092] In some embodiments, the silicon source gas can be supplied for 2 to 8 hours. In some embodiments, the silicon source gas can be supplied for 2.5 to 7.5 hours, 3 to 5.5 hours, or 3 to 4 hours. Within the above ranges, the electrode material can contain an appropriate amount of silicon, which can improve the battery's lifespan and capacity characteristics.

[0093] According to an exemplary implementation, the pressure inside the reactor can be reduced (e.g., step S30).

[0094] For example, the pressure inside the reactor can be reduced to a range of 1 to 250 Torr or 10 to 150 Torr to obtain silicon-carbon electrode materials. For example, during the aforementioned pressure reduction, unreacted silane gas (SiH...) x It can be volatilized, and the peak intensity percentage within the above range can be easily ensured.

[0095] In some embodiments, the pressure inside the reactor can be reduced to a range of 30 to 140 Torr, 50 to 130 Torr, or 80 to 120 Torr. Within these ranges, the unreacted silane gas (SiH) can be easily adjusted. x The amount of ).

[0096] In some embodiments, the decompression can be performed at a temperature between 200°C and 600°C. In some embodiments, the decompression can be performed within a temperature range of 220°C to 500°C, 250°C to 400°C, or 250°C to 350°C.

[0097] In some embodiments, the depressurization can be performed under a non-reactive gas atmosphere. For example, the porous carbon structure with the silicon-containing coating can be placed inside a reactor, and a non-reactive gas can be injected into the reactor to displace the gas atmosphere.

[0098] In some embodiments, the non-reactive gas may include at least one selected from helium, nitrogen, neon, argon, krypton, and xenon. For example, the non-reactive gas may be nitrogen.

[0099] In some embodiments, during the aforementioned depressurization, the reactor may be substantially free of hydrogen and / or silane gas injection. Therefore, unreacted materials can be discharged, thereby enabling the peak intensity percentages within the aforementioned range to be achieved.

[0100] In some embodiments, the decompression can be performed for 0.5 hours to 3.5 hours. In some embodiments, the decompression can be performed for 1 hour to 3.5 hours, 0.5 hours to 3 hours, 1 hour to 3 hours, 1 hour to 2 hours, or 1.5 hours to 2.5 hours.

[0101] Within the aforementioned decompression time range, unreacted silane gas (SiH) can be released. x The amount of [amount] can be adjusted to an appropriate range, and the peak intensity percentage within the aforementioned range can be easily ensured. Therefore, the lifespan and power characteristics of lithium-ion batteries can be improved.

[0102] In some embodiments, a carbon coating may be further formed on the silicon-containing coating. The carbon coating may be formed by deposition using gases such as methane or by solution coating using monomer / polymer solutions.

[0103] In one embodiment, the carbon coating may comprise polymers with improved elastic properties, such as acrylonitrile-based polymers, and may also comprise conductive polymers such as polypyrrole, polyaniline, polythiophene, and poly 3,4-ethylenedioxythiophene.

[0104] In one embodiment, the hydrocarbon precursor may be decomposed or polymerized at high temperature in an inert gas or anaerobic atmosphere to form a carbon coating. The hydrocarbon precursor is an alkane such as methane, ethane, or propane, an alkene such as ethylene or propylene, or an alkyne such as acetylene.

[0105] The properties (e.g., Raman characteristics) of the electrode material according to embodiments of the present invention do not necessarily depend on the above-described preparation methods and conditions. For example, the percentage values ​​of the peak intensity of the above-described Raman spectra may also vary depending on other factors, including the type and physical properties of the porous carbon structure and silicon source gas, silicon deposition conditions, etc.

[0106] <Lithium secondary batteries>

[0107] Figure 1 and Figure 2 These are schematic plan views and schematic cross-sectional views of a lithium secondary battery according to an exemplary embodiment. Figure 2 It is along Figure 1 A cross-sectional view taken from the I-I' line.

[0108] Reference Figure 1 and Figure 2 The lithium secondary battery may include an electrode assembly comprising a positive electrode 100 and a negative electrode 130. The electrode assembly 150 may further include a separator 140 between the positive electrode 100 and the negative electrode 130. The electrode assembly 150 may be housed in a housing 160 and immersed in an electrolyte containing an electrolyte.

[0109] The positive electrode 100 may include a positive electrode current collector 105 and a positive electrode active material layer 110, wherein the positive electrode active material layer 110 is disposed on at least one side of the positive electrode current collector 105.

[0110] For example, the positive electrode current collector 105 may include stainless steel, nickel, aluminum, titanium, or alloys thereof. The positive electrode current collector may also include aluminum or stainless steel surface-treated with carbon, nickel, titanium, or silver. The thickness of the positive electrode current collector is not limited thereto, but for example, the thickness may be from 10 μm to 50 μm.

[0111] For example, the positive electrode active material may contain compounds that enable reversible insertion and extraction of lithium ions.

[0112] For example, the positive electrode active material may contain lithium metal oxides containing metal elements such as nickel, cobalt, manganese, and aluminum.

[0113] According to an exemplary embodiment, the positive electrode active material may comprise a lithium-nickel metal oxide. The lithium-nickel metal oxide may further comprise at least one of cobalt (Co), manganese (Mn), and aluminum (Al).

[0114] In some embodiments, the positive electrode active material or the lithium-nickel metal oxide may include a layered structure or a crystal structure represented by the following chemical formula 1.

[0115] [Chemical Formula 1]

[0116] Li x Ni a M b O 2+z

[0117] In chemical formula 1, the values ​​can be 0.9≤x≤1.2, 0.6≤a≤0.99, 0.01≤b≤0.4, and -0.5≤z≤0.1. As mentioned above, M can contain Co, Mn, and / or Al.

[0118] The chemical structure represented by Formula 1 indicates the bonding relationships contained in the layered or crystalline structure of the positive electrode active material, and does not exclude other additional elements. For example, M may contain Co and / or Mn, and Co and Mn may be provided together with Ni as the main active element of the positive electrode active material. Formula 1 is provided to represent the bonding relationships of the main active elements, and it should be understood that Formula 1 includes the introduction and substitution of additional elements.

[0119] In one embodiment, in addition to the primary active element, auxiliary elements may be further included to enhance the chemical stability of the positive electrode active material or the layered / crystal structure. These auxiliary elements may be incorporated into the layered / crystal structure and form bonds; this should be understood to also include the chemical structures represented by Formula 1.

[0120] The auxiliary element may include at least one of, for example, Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Al, Ga, C, Si, Sn, Sr, Ba, Ra, P, or Zr. The auxiliary element may function as an auxiliary active element, together with Co or Mn, to contribute to the capacity / power activity of the positive electrode active material; for example, Al.

[0121] For example, the positive electrode active material or the lithium-nickel metal oxide may include a layered structure or a crystal structure represented by the following chemical formula 1-1.

[0122] [Chemical Formula 1-1]

[0123] Li x Ni a M1 b1 M2 b2 O 2+z

[0124] In chemical formula 1-1, M1 may contain Co, Mn, and / or Al. M2 may contain the aforementioned auxiliary elements. In chemical formula 1-1, the following conditions may be met: 0.9≤x≤1.2, 0.6≤a≤0.99, 0.01≤b1+b2≤0.4, -0.5≤z≤0.1.

[0125] The positive electrode active material may further include coating elements or doping elements. For example, elements that are substantially the same as or similar to the auxiliary elements described above can be used as coating elements or doping elements. For example, one or more combinations of the elements described above can be used as coating elements or doping elements.

[0126] The coating element or doping element may exist on the surface of the lithium-nickel metal oxide particles, or may penetrate through the surface of the lithium-nickel metal oxide particles and be contained in the bonding structure represented by chemical formula 1 or chemical formula 1-1.

[0127] The positive electrode active material may contain nickel-cobalt-manganese (NCM)-based lithium oxide. In this case, NCM-based lithium oxide with increased nickel content can be used.

[0128] Nickel can be provided as a transition metal related to the power and capacity of lithium secondary batteries. Therefore, as described above, by using a high-content (High-Ni) composition for the positive electrode active material, a high-capacity positive electrode and a high-capacity lithium secondary battery can be provided.

[0129] However, with increasing Ni content, the long-term storage stability and lifetime stability of the cathode or secondary battery may relatively decrease, and side reactions with the electrolyte may also increase. However, according to an exemplary embodiment, conductivity can be maintained by including Co, while lifetime stability and capacity retention characteristics can be improved by including Mn.

[0130] The Ni content in the NCM-based lithium oxide (e.g., the mole fraction of nickel in the total moles of nickel, cobalt, and manganese) can be 0.6 or more, 0.7 or more, or 0.8 or more. In some embodiments, the Ni content can be 0.8 to 0.95, 0.82 to 0.95, 0.83 to 0.95, 0.84 to 0.95, 0.85 to 0.95, or 0.88 to 0.95.

[0131] In some embodiments, the positive electrode active material may further comprise lithium cobalt oxide-based active material, lithium manganese oxide-based active material, lithium nickel oxide-based active material, or lithium iron phosphate (LFP)-based active material (e.g., LiFePO4).

[0132] In some embodiments, the positive electrode active material may comprise, for example, a manganese-rich (Mn-rich) based active material, a lithium-rich layered oxide (LLO) / over lithiated oxide (OLO) based active material, or a cobalt-less based active material having a chemical structure or crystal structure represented by the following chemical formula 2.

[0133] [Chemical Formula 2]

[0134] p[Li₂MnO₃]·(1-p)[Li q JO2]

[0135] In Chemical Formula 2, 0 < p < 1, 0.9 ≤ q ≤ 1.2, and J may include at least one element selected from Mn, Ni, Co, Fe, Cr, V, Cu, Zn, Ti, Al, Mg, and B.

[0136] For example, the positive electrode active material may be dispersed in a solvent to prepare a positive electrode mixture. The positive electrode mixture may be coated on the positive electrode current collector 105 and then dried and calendered to fabricate the positive electrode 100. The coating process may be performed by methods such as gravure coating, slot die coating, multi-layer simultaneous die coating, imprinting, doctor blade coating, dip coating, bar coating, casting, etc., and is not limited thereto. The positive electrode mixture may further include a binder, and may optionally further include a conductive material, a thickener, etc.

[0137] Non-limiting examples of the solvent used for preparing the positive electrode mixture may include N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, N,N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran, etc.

[0138] The binder may include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (Poly(vinylidene fluoride-co-hexafluoropropylene)), polyacrylonitrile, polymethyl methacrylate, nitrile rubber (NBR), polybutadiene rubber (BR), styrene-butadiene rubber (SBR), etc. In one embodiment, a PVDF-based binder may be used as the positive electrode binder.

[0139] The conductive material may be added to enhance the conductivity of the positive electrode active material layer and / or the mobility of lithium ions or electrons. For example, the conductive material may include carbon-based conductive materials such as graphite, carbon black, acetylene black, Ketjen black, graphene, carbon nanotubes, vapor-grown carbon fiber (VGCF), carbon fiber, etc. and / or metal-based conductive materials including perovskite materials such as tin, tin oxide, titanium oxide, LaSrCoO3, LaSrMnO3, etc.

[0140] As the thickener, for example, carboxymethyl cellulose (CMC) may be used.

[0141] The negative electrode 130 may include a negative electrode current collector 125 and a negative electrode active material layer 120 on the negative electrode current collector 125.

[0142] For example, the negative electrode active material layer 120 may contain a negative electrode active material and a negative electrode binder, and may further contain a conductive material.

[0143] For example, the negative electrode 130 can be manufactured as follows: the negative electrode active material, the negative electrode binder and the conductive material are mixed in a solvent and stirred to prepare a negative electrode slurry, and then the negative electrode slurry is coated on the negative electrode current collector 125 and dried and calendered to manufacture the negative electrode 130.

[0144] The coating process can be carried out by methods such as gravure coating, slot extrusion coating, multi-layer simultaneous die coating, embossing, doctor blade coating, dip coating, rod coating, and casting, and is not limited to these methods.

[0145] For example, the negative electrode current collector 125 may include gold, stainless steel, nickel, aluminum, titanium, copper, or alloys thereof. As an example, the negative electrode current collector 125 may include copper or a copper alloy. The thickness of the negative electrode current collector is not limited thereto, but for example, the thickness of the negative electrode current collector may be from 10 μm to 50 μm.

[0146] For example, the negative electrode active material layer 120 may comprise a silicon-carbon electrode material according to the exemplary embodiments described above as the negative electrode active material. In some embodiments, the negative electrode active material may further comprise a graphite-based active material such as artificial graphite or natural graphite.

[0147] In some embodiments, the content of silicon-carbon electrode material in the total weight of the negative electrode active material contained in the negative electrode active material layer 120 may be 5% to 40% by weight, 10% to 30% by weight, 10% to 20% by weight, or 15% to 20% by weight according to the above exemplary embodiments.

[0148] In some embodiments, the content of the graphite-based active material in the total weight of the negative electrode active material contained in the negative electrode active material layer 120 may be 60% to 95% by weight, 65% to 90% by weight, 70% to 85% by weight, or 75% by weight or 80% by weight.

[0149] In one embodiment, the negative electrode active material included in the negative electrode active material layer 120 may also be composed of a silicon-carbon electrode material according to the exemplary embodiments described above. Therefore, the initial efficiency, capacity characteristics, and lifetime characteristics of the lithium secondary battery can be improved.

[0150] For example, relative to the total weight of the negative electrode active material layer 120, the content of the negative electrode active material contained in the negative electrode active material layer 120 can be from 60% to 99% by weight, for example, from 70% to 98% by weight or from 80% to 98% by weight.

[0151] Non-limiting examples of solvents used for negative electrode mixtures include water, pure water, deionized water, distilled water, ethanol, isopropanol, methanol, acetone, n-propanol, tert-butanol, etc.

[0152] The negative electrode adhesive and conductive material may be substances substantially the same as or similar to the positive electrode adhesive and conductive material described above.

[0153] For example, the negative electrode adhesive can be a styrene-butadiene rubber (SBR) based adhesive, a polyacrylic acid based adhesive, a poly(3,4-ethylenedioxythiophene) (PEDOT) based adhesive, etc., and can be used with a thickener such as carboxymethyl cellulose (CMC).

[0154] In one embodiment, a separator 140 may be disposed between the positive electrode 100 and the negative electrode 130. The separator prevents short circuits between the positive and negative electrodes and maintains ion flow. According to the embodiment, the thickness of the separator may be from 10 μm to 20 μm, but the invention is not limited thereto.

[0155] For example, the membrane 140 may comprise a porous polymer membrane made of polyolefin-based polymers such as ethylene polymers, propylene polymers, ethylene / butene copolymers, ethylene / hexene copolymers, and ethylene / methacrylate copolymers.

[0156] For example, the diaphragm 140 may include a nonwoven fabric formed of high-melting-point glass fibers, polyethylene terephthalate fibers, etc.

[0157] For example, a battery cell can be formed by including a positive electrode 100, a negative electrode 130, and a separator 140. Furthermore, multiple battery cells can be stacked to form an electrode assembly 150. For example, the electrode assembly 150 can be formed by winding, stacking, z-folding, or stack-folding of the separator 140.

[0158] The electrode assembly 150 can be housed together with the electrolyte in the housing 160, thereby defining a lithium secondary battery. According to an exemplary embodiment, the electrolyte can be a non-aqueous electrolyte.

[0159] Non-aqueous electrolytes may contain lithium salts and organic solvents, wherein the lithium salts may be, for example, derived from Li. + X - This indicates that the anion (X) of the lithium salt is... - ), can be exemplified by F - Cl - ,Br - I - NO3 - N(CN)2 - BF4 - ClO4 - PF6 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (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 - wait.

[0160] The organic solvent may include an organic compound that has sufficient solubility for the lithium salt and additives and is non-reactive in the battery. The organic solvent may include at least one of, for example, carbonate-based solvents, ester-based solvents, ether-based solvents, ketone-based solvents, alcohol-based solvents, and aprotic solvents.

[0161] The organic solvent may be, for example, propylene carbonate (PC), ethylene carbonate (EC), butene carbonate, diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, vinylene carbonate, methyl acetate (MA), ethyl acetate (EA), n-propylacetate (n-PA), 1,1-dimethylethyl acetate (DMEA), methyl propionate (MP), ethyl propionate (EP), ethyl fluoroacetate (FEA), ethyl difluoroacetate (DFEA), ethyl trifluoroacetate (TFEA), dibutyl ether, tetraethylene glycol dimethyl ether (TEGDME), and diethylene glycol dimethyl ether. These include ether (DEGDME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, ethyl alcohol, isopropyl alcohol, dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, sulfolane, γ-butyrolactone, and propylene sulfite, etc. These can be used alone or in combination of two or more.

[0162] The non-aqueous electrolyte may further comprise additives. These additives may include, for example, cyclic carbonate compounds, fluorinated carbonate compounds, sulopentalide compounds, cyclic sulfate compounds, cyclic sulfite compounds, phosphate compounds, and borate compounds.

[0163] The cyclic carbonate-based compound may include vinylene carbonate (VC), vinyl ethylene carbonate (VEC), etc.

[0164] The fluorinated carbonate compounds may include fluoroethylene carbonate (FEC), etc.

[0165] The sulcinolone compounds may include 1,3-propane sultone, 1,3-propene sultone, 1,4-butane sultone, etc.

[0166] The cyclic sulfate-based compounds may include 1,2-ethylene sulfate, 1,2-propylene sulfate, etc.

[0167] The cyclic sulfite-based compound may include ethylene sulfite, butylene sulfite, etc.

[0168] The phosphate-based compounds may include lithium difluorobis-oxalato phosphate, lithium difluorophosphate, etc.

[0169] The borate-based compounds may include lithium bis(oxalate) borate, etc.

[0170] like Figure 1 As shown, the tabs (positive or negative) can protrude from the positive current collector 105 and negative current collector 125 belonging to each cell and extend to one side of the housing 160. The tabs can be fused together and connected to the electrode leads (positive lead 107 or negative lead 127) extending to the outside of the housing 160.

[0171] For example, the lithium secondary battery can be made into, for example, cylindrical, prismatic, pouch, or coin shapes using a can.

[0172] The embodiments of the present invention will be further described below with reference to specific experimental examples. The embodiments and comparative examples included in the experimental examples are only for illustrating the present invention and are not intended to limit the scope of the claims. Various changes and modifications can be made to the embodiments within the scope of the present invention and its technical concept, which is obvious to those skilled in the art, and such variations and modifications naturally fall within the scope of the claims.

[0173] Example 1

[0174] (1) Preparation of silicon-carbon electrode materials

[0175] Preparation of porous carbon structures

[0176] Phenol and formaldehyde were mixed at a molar ratio of 1:2, and 1.5% by weight of triethylamine was added. The mixture was reacted at 85°C and 160 rpm (stirring) for 4 hours to synthesize a primary phenolic resin oligomer. A dispersion of 1 g of polyvinyl alcohol (PVA) in an aqueous dispersion medium was added to the primary phenolic resin oligomer to stabilize it in suspension.

[0177] Subsequently, 3g of hexamethylenetetramine (HMTA) was added as a curing agent, and the mixture was reacted at 98°C and 400 rpm (stirring) for 12 hours to cure the methyl phenolic resin oligomer. The cured methyl phenolic resin oligomer was graded using a sieve and then washed with water (H2O). Unreacted monomers and oligomers in the washed methyl phenolic resin oligomer were removed using ethanol and then dried.

[0178] Porous carbon structure particles were prepared by calcining dried methyl phenolic resin oligomers at 800°C for 3 hours under a nitrogen atmosphere. Water vapor was then injected to activate the porous carbon structure particles. The average pore size of the prepared porous carbon structures was adjusted to 1 nm to 20 nm, and the specific surface area was adjusted to 1000 m². 2 / g to 2000m 2 / g.

[0179] Formation of silicon-containing coatings

[0180] The prepared porous carbon structure was placed inside the CVD chamber, and a mixture of silane gas (SiH4) and nitrogen gas (N2) was injected at a flow rate of 2 L / min for 4 hours under the conditions of 550 °C and 760 Torr. This resulted in the formation of a silicon-containing coating.

[0181] Pressure reduction process

[0182] Nitrogen gas (N2) was injected into the porous carbon structure with deposited silicon to replace the interior of the CVD chamber with a nitrogen atmosphere. The atmosphere was maintained at 300°C and 100 Torr for 1 hour to prepare silicon-carbon electrode materials.

[0183] (2) Manufacturing of the negative electrode

[0184] A negative electrode active material slurry is obtained by mixing 95.5% by weight of a negative electrode active material (a mixture of 15% by weight of the silicon-carbon electrode material prepared as described above and 80.5% by weight of artificial graphite), 0.5% by weight of flake-type conductive material CNT as a conductive material, 2.5% by weight of styrene-butadiene rubber (SBR) as a binder, and 1.5% by weight of carboxymethyl cellulose (CMC) as a thickener. The negative electrode active material slurry is then coated onto a copper substrate and dried and calendered to manufacture the negative electrode.

[0185] (3) Manufacturing of lithium secondary batteries

[0186] The positive electrode active material (Li[Ni) 0.88 Co 0.06 Mn 0.06 A positive electrode slurry is prepared by mixing and dispersing O2, carbon black conductive material and polyvinylidene fluoride (PVDF) binder in N-methyl-2-pyrrolidone (NMP) at a weight ratio of 92:5:3.

[0187] The positive electrode slurry is uniformly coated on the area of ​​an aluminum foil (15 μm thick) with a protrusion (positive electrode tab) on one side, excluding the protrusion, and then dried and rolled to manufacture the positive electrode.

[0188] A polyethylene diaphragm (13 μm thick) is placed between the negative electrode and the positive electrode manufactured as described above to form an electrode assembly. Next, the positive electrode lead and the negative electrode lead are soldered to the positive electrode tab and the negative electrode tab, respectively.

[0189] The electrode assembly is housed inside a soft package (shell) such that portions of the positive and negative leads are exposed to the outside, while the other three sides, except for the electrolyte injection side, are sealed.

[0190] 1M LiPF6 was dissolved in a mixed solvent of EC / EMC (3:7; volume ratio), and then 2% by volume of fluoroethylene carbonate (FEC) relative to the total volume of the electrolyte was added to obtain an electrolyte. The electrolyte was injected and the injection site was sealed, and then immersed for 12 hours to produce a lithium secondary battery sample.

[0191] Example 2

[0192] The silicon-carbon electrode material and the lithium secondary battery were manufactured using the same method as in Example 1, except that the holding time in the reduced pressure process was changed from 1 hour to 2 hours.

[0193] Example 3

[0194] The silicon-carbon electrode material and the lithium secondary battery were manufactured using the same method as in Example 1, except that the holding time in the reduced pressure process was changed from 1 hour to 3 hours.

[0195] Example 4

[0196] The silicon-carbon electrode material and the lithium secondary battery were manufactured using the same method as in Example 1, except that the deposition time was changed from 4 hours to 1 hour during the formation of the silicon-containing coating, and the holding time in the depressurization process was changed to 2 hours.

[0197] Comparative Example 1

[0198] The lithium secondary battery was manufactured using the same method as in Example 1, except that the reduced pressure process was not performed, and a silicon-carbon electrode material with a silicon-containing coating formed on a porous carbon structure was used.

[0199] Comparative Example 2

[0200] The silicon-carbon electrode material and the lithium secondary battery were manufactured using the same method as in Example 1, except that the holding time in the reduced pressure process was changed from 1 hour to 6 hours.

[0201] Comparative Example 3

[0202] The silicon-carbon electrode material and the lithium secondary battery were manufactured using the same method as in Example 1, except that the holding time in the reduced pressure process was changed to 2 hours and the pressure was changed to 750 Torr.

[0203] Comparative Example 4

[0204] The silicon-carbon electrode material and the lithium secondary battery were manufactured using the same method as in Example 1, except that the holding time in the reduced pressure process was changed to 2 hours and the pressure was changed to 380 Torr.

[0205] The physical properties of the silicon-carbon electrode materials prepared according to the examples and comparative examples were measured / evaluated as follows.

[0206] (4) Measurement of silicon content in silicon-carbon electrode materials

[0207] Add the silicon-carbon electrode material according to the examples or comparative examples, nitric acid, and a small amount of hydrofluoric acid to a polypropylene (PP) tube, and seal the tube by screwing on the cap. Shake the PP tube thoroughly and then allow it to dissolve at room temperature. After the silicon-carbon electrode material has dissolved, refrigerate the PP tube to cool the silicon-carbon electrode material. Add saturated boric acid solution to the cooled silicon-carbon electrode material to neutralize the hydrofluoric acid, and then dilute with ultrapure water. Remove any residual carbon components from the silicon-carbon electrode material using a 0.45 μm syringe filter to obtain the added solution.

[0208] The obtained addition solution was added to an ICP analyzer (NexION 350S, PerkinElmer) to measure the weight of silicon and additional elements.

[0209] Specifically, a high-temperature (~10000K) Ar plasma is generated using an induced magnetic field (radio frequency), injected into the aerosol sample, and the generated cations are separated according to their mass / charge ratio, with the signal intensity of each ratio being detected. The conditions of the ICP analysis apparatus are as follows:

[0210] - RF Generator: 40MHz free-running ICP source / Quadruple-stage vacuum system / Detector: Quadruple ion detector

[0211] (5) Measurement of peak intensity percentage in Raman spectra

[0212] For the silicon-carbon electrode materials according to the above embodiments and comparative examples, measurements at 1800 cm⁻¹ were performed using a 532 nm laser Raman analyzer (laser Raman spectroscopy). -1 Up to 3200cm -1 Raman spectra within the range.

[0213] In the obtained Raman spectrum, at a wavenumber of 2300 cm⁻¹ -1 Up to 3120cm -1 When the area is used as the baseline, measure 2500cm. -1 Up to 3000cm -1 The maximum peak intensity in the region (I) A ), at a wavenumber of 1850cm -1 Up to 2200cm -1When the area is used as the baseline, measure 2080cm. -1 Up to 2120cm -1 The maximum peak intensity in the region (I) B Substitute the measured peak intensity into Equation 1 to calculate the percentage of peak intensity in the Raman spectrum.

[0214] [Formula 1]

[0215] Peak intensity percentage = (I B / I A ) 100

[0216] The specific measurement conditions for Raman spectroscopy are as follows.

[0217] i) Equipment: Renishaw in Via Raman microscope

[0218] ii) Wavelength and intensity: 532nm, 0.01-0.5mW

[0219] iii) Exposure time and number of scans: 5-20 seconds, 5-20 scans

[0220] iv) Grating: 1800 L / mm

[0221] v) Detector: 1024 StreamLine CCD array detector

[0222] vi) Objective lens: x50

[0223] The data processing conditions for Raman spectroscopy measurements are as follows.

[0224] i) Data processing software: Resolutions Pro.

[0225] ii) Baseline setting area used to measure peak intensity percentage

[0226] 2500cm -1 Up to 3000cm -1 Peak within the wavenumber range: baseline at 2300 cm⁻¹ -1 Up to 3120cm -1

[0227] 2080cm -1 Up to 2120cm -1 Peak within the wavenumber range: baseline at 1850 cm⁻¹ -1 Up to 2200cm -1

[0228] At this point, the measurement is taken under the following conditions: 2500cm -1Up to 3000cm -1 Peak intensity above 500 in the wavenumber range, 2080 cm⁻¹ -1 Up to 2120cm -1 The peak intensity is above 50 within the wavenumber range.

[0229] Figures 4a to 4d The figures show the Raman spectra of the silicon-carbon electrode materials of Examples 2, 3, Comparative Example 1 and Comparative Example 2, measured according to the above method.

[0230] To facilitate comparison of peak intensities, Figure 5a The figure shows the Raman spectra of silicon-carbon electrode materials according to Examples 2, 3, Comparative Example 1 and Comparative Example 2. Figure 5b The text shows the... Figure 5a The image shown is a magnified view of a specific area.

[0231] The preparation conditions and physical property evaluation results of the silicon-carbon electrode materials prepared according to the examples and comparative examples are recorded in Table 1 below.

[0232] [Table 1]

[0233]

[0234] Experimental Example

[0235] The performance of lithium secondary batteries using silicon-carbon electrode materials prepared according to the examples and comparative examples was measured / evaluated as follows.

[0236] (1) Measurement of capacity retention (lifetime characteristics) during repeated charging / discharging

[0237] For each lithium secondary battery in the examples and comparative examples, 0.3C rate CC / CV charging (4.2V, 0.1C cut-off) and 0.5C rate CC discharging (2.7V cut-off) were performed at 45°C for 400 cycles. Capacity retention was evaluated as the percentage of the discharge capacity of the 400th cycle divided by the discharge capacity of the 1st cycle.

[0238] The evaluation results are recorded in Table 2 below.

[0239] [Table 2]

[0240]

[0241] 1) 45℃, under 400 cycles.

[0242] Referring to Tables 1 and 2, the percentage of peak intensity using the above Raman spectra ((I) B / IA ) In Examples 1 to 4, where silicon-carbon electrode materials in the range of 3% to 18% were used, the lifespan characteristics of the secondary battery were improved.

[0243] In Example 4, where the silicon content in the total weight of the electrode material is relatively low, the capacity retention rate of the secondary battery is relatively reduced.

[0244] In comparative examples manufactured using silicon-carbon electrode materials with a Raman spectrum peak intensity percentage of less than 3% or more than 18%, the lifetime characteristics of the secondary battery were reduced.

Claims

1. A silicon-carbon electrode material, wherein, The silicon-carbon electrode material comprises: Porous carbon structures containing pores; and A silicon-containing coating is formed on the porous carbon structure. The peak intensity percentage of the Raman spectrum of the silicon-carbon electrode material, as defined by Equation 1, is between 3% and 18%. [Formula 1] Peak intensity percentage = (I B / I A ) 100 In Equation 1, I A For Raman spectra at 2300 cm⁻¹ -1 Up to 3120cm -1 Wavenumber range is 2500cm at baseline. -1 Up to 3000cm -1 The maximum peak intensity at I B The Raman spectrum at 1850 cm⁻¹ -1 Up to 2200cm -1 Wavenumber range is 2080cm at baseline. -1 Up to 2120cm -1 The maximum value of the peak intensity at that location.

2. The silicon-carbon electrode material according to claim 1, wherein, The peak intensity percentage is 4% to 15%.

3. The silicon-carbon electrode material according to claim 1, wherein, The peak intensity percentage ranges from 4.73% to 13.85%.

4. The silicon-carbon electrode material according to claim 1, wherein, The silicon content in the total weight of the silicon-carbon electrode material is 38% to 60% by weight.

5. The silicon-carbon electrode material according to claim 1, wherein, The silicon content in the total weight of the silicon-carbon electrode material is 45% to 55% by weight.

6. The silicon-carbon electrode material according to claim 1, wherein, The silicon content in the total weight of the silicon-carbon electrode material is from 35.9% to 49.3% by weight.

7. A method for preparing a silicon-carbon electrode material, wherein, The preparation method includes the following steps: Prepare porous carbon structures containing pores; A silicon source gas is supplied to the porous carbon structure within the reactor to form a silicon-containing coating on the porous carbon structure; and The pressure inside the reactor is reduced to the range of 1 Torr to 250 Torr to obtain silicon-carbon electrode materials.

8. The method for preparing the silicon-carbon electrode material according to claim 7, wherein, The percentage of peak intensity in the Raman spectrum measured from the silicon-carbon electrode material, as defined by Equation 1, is 3% to 18%. [Formula 1] Peak intensity percentage = (I B / I A ) 100 In Equation 1, I A For Raman spectra at 2300 cm⁻¹ -1 Up to 3120cm -1 Wavenumber range is 2500cm at baseline. -1 Up to 3000cm -1 The maximum peak intensity at I B For Raman spectra at 1850 cm⁻¹ -1 Up to 2200cm -1 Wavenumber range is 2080cm at baseline. -1 Up to 2120cm -1 The maximum value of the peak intensity at that location.

9. The method for preparing the silicon-carbon electrode material according to claim 7, wherein, The silicon source gas is supplied at a temperature ranging from 300°C to 600°C.

10. The method for preparing the silicon-carbon electrode material according to claim 7, wherein, The supply of silicon source gas lasts for 2 to 8 hours.

11. The method for preparing the silicon-carbon electrode material according to claim 7, wherein, The silicon source gas is a mixture of silane gas and non-reactive gas.

12. The method for preparing the silicon-carbon electrode material according to claim 7, wherein, The decompression is performed at a temperature between 200°C and 600°C.

13. The method for preparing the silicon-carbon electrode material according to claim 7, wherein, The decompression is performed for 0.5 to 3.5 hours.

14. The method for preparing the silicon-carbon electrode material according to claim 7, wherein, The decompression is performed in a non-reactive gas atmosphere.

15. A lithium secondary battery, wherein, The lithium secondary battery includes: The negative electrode comprises the silicon-carbon electrode material of claim 1; and The positive electrode is positioned opposite the negative electrode.

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