Lithium silicon oxide, anode containing the same, and lithium secondary battery containing the anode

Abstract

The present invention relates to a lithium silicon oxide that suppresses gas generation when an aqueous slurry is applied, an anode including the same, and a lithium secondary battery including the anode. The present invention also provides a lithium silicon oxide that has peaks at 2θ positions of 23.8±0.5°, 24.3±0.5°, and 24.7±0.5° in an XRD pattern measured using non-monochromated CuKα radiation and satisfies Mathematical Formula 1, an anode including the same, and a lithium secondary battery including the anode.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0075096, filed June 12, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a lithium silicon oxide that suppresses gas generation when an aqueous slurry is applied, a negative electrode containing the same, and a lithium secondary battery that includes the negative electrode. [Background technology]

[0003] Recently, the application areas of lithium secondary batteries have rapidly expanded from power supply for electronic devices such as electrical, electronic, communication, and computer equipment to power storage and supply for large-area devices such as automobiles and power storage devices, resulting in an increasing need for high-capacity, high-power, and highly stable lithium secondary batteries.

[0004] Lithium secondary batteries are generally manufactured by coating a positive electrode current collector and a negative electrode current collector, respectively, with a slurry of a positive electrode material capable of inserting and desorbing lithium ions or a negative electrode material capable of occluding and releasing lithium ions, optionally mixed with a binder and a conductive material, and then removing the solvent by heat or the like to produce a positive electrode and a negative electrode. These are then laminated on both sides of a separator to form an electrode current collector of a predetermined shape, and then this electrode current collector and a non-aqueous electrolyte are inserted into a battery case.

[0005] Graphite-based anode materials, which are typical anode materials, have excellent structural stability during lithium insertion and extraction, and exhibit stable capacity retention characteristics even over long cycles. However, their low theoretical capacity (350mAh / g for LiC6) makes them unsuitable as high-capacity, high-output materials, which are currently required. Therefore, silicon-based anode materials, such as silicon and silicon oxide, have a low reduction potential with lithium, abundant reserves, and a theoretical capacity approximately 10 times higher than that of graphite (2700-4200mAh / g for LiC6). 4.4Silicon-based anode materials are attracting attention as anode materials for next-generation lithium secondary batteries. However, despite these advantages, silicon-based anode materials consume three times more lithium than graphite-based anode materials, and when lithium secondary batteries that use them are charged and discharged, a large amount of the lithium inserted into the anode during the initial charge cannot be returned to the cathode due to volume expansion and surface side reactions, resulting in a large initial irreversible capacity.

[0006] In addition, silicon oxide (SiO x In the case of silicon oxide particles, various methods have been attempted to improve initial efficiency by doping them with Mg or prelithiating silicon oxide particles with Li to solve the problem of initial efficiency caused by irreversible reactions of Li ions. However, when anode material slurry is produced using an aqueous process using this method, lithium oxide formed inside the prelithiated silicon oxide particles reacts with HO to produce LiOH by-products, which reduces the viscosity of the slurry and generates hydrogen, deteriorating the coating properties of the slurry. As a result, problems still remain, such as a decrease in adhesion between the anode material layer and the current collector and volume expansion.

[0007] Therefore, there is a need to develop an anode material that has excellent initial capacity and capacity retention, does not change viscosity significantly during production of the anode material slurry using an aqueous process, suppresses hydrogen generation, and suppresses volume expansion during charge and discharge in the anode using this material. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] KR10-2014-0091388A Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been devised to solve the above-mentioned problems of the conventional art, and aims to provide a lithium silicon oxide useful as a negative electrode material, which has excellent initial capacity and capacity retention, undergoes almost no change in viscosity during production of a slurry by an aqueous process, and suppresses hydrogen generation.

[0010] Another object of the present invention is to provide a negative electrode containing the lithium silicon oxide.

[0011] It is another object of the present invention to provide a lithium secondary battery including the above negative electrode. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides a lithium silicon oxide, a negative electrode containing the same, and a lithium secondary battery.

[0013] (1) The present invention provides a lithium silicon oxide having peaks at 2θ positions of 23.8±0.5°, 24.3±0.5°, and 24.7±0.5° in an XRD pattern measured using non-monochromated CuKα radiation, and satisfying the following mathematical formula 1: [Mathematical formula 1] y sio2,max ≦0.4·y si,111 In the above mathematical formula 1, y sio2,max is the height of the highest peak among the SiO2 peaks at 2θ = 20.7 ± 0.5°, 21.6 ± 0.5°, and 26.5 ± 0.5° in the XRD pattern measured using non-monochromated CuKα radiation, and y si,111 is the height of the Si peak corresponding to the position of 2θ=28.5±0.5° in the XRD pattern.

[0014] (2) The present invention provides a lithium silicon oxide according to the above (1), which satisfies the following mathematical formula 2: [Mathematical formula 2] I q,100 +I c,111 +I q,011 ≦0.3 Isi,111 In the mathematical formula 2, I q,100 、I c,111 and I q,011 are the integrated intensities of the SiO2 peaks corresponding to the positions of 2θ = 20.7 ± 0.5°, 21.6 ± 0.5°, and 26.5 ± 0.5° respectively in the XRD pattern measured using the non-monochromated CuKα line, and I si,111 is the integrated intensity of the Si peak corresponding to the position of 2θ = 28.5 ± 0.5° in the XRD pattern.

[0015] (3) The present invention provides a lithium silicon oxide satisfying the following mathematical formula 3 in the above (1) or (2). [Mathematical formula 3] 0 ≦ y o3,111 ≦ 0.1·y backgroud In the mathematical formula 3, y o3,111 is the height of the peak of Li2SiO3 corresponding to the position of 2θ = 27.0 ± 0.2° in the XRD pattern measured using the non-monochromated CuKα line, and y backgroud is the height of the background peak other than the peak of Li2SiO3 at the position of 2θ = 27.0 ± 0.2° in the XRD pattern.

[0016] (4) The present invention provides a lithium silicon oxide in which no peak exists at 27.0 ± 0.2° in the XRD pattern measured using the non-monochromated CuKα line in any one of the above (1) to (3).

[0017] (5) The present invention provides a lithium silicon oxide containing Si, SiO x (0 < x ≦ 2) and a lithium-containing compound in any one of the above (1) to (4).

[0018] (6) The present invention provides a lithium silicon oxide in which the above Si and SiO (0 < x ≦ 2) in the above (5) contain a carbon coating layer on the surface. x (0 < x ≦ 2) contains a carbon coating layer on the surface in the above (5).

[0019] (7) The present invention provides a lithium silicon oxide according to the above (5), wherein the lithium-containing compound includes at least one of lithium disilicate and lithium silicide.

[0020] (8) The present invention provides a negative electrode comprising a conductive metal current collector and a negative electrode material layer provided on at least one surface of the current collector, the negative electrode material layer comprising any one of the lithium silicon oxides described in (1) to (7).

[0021] (9) The present invention provides a lithium secondary battery comprising the negative electrode according to (8) above, a positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. [Effects of the Invention]

[0022] The lithium silicon oxide of the present invention has excellent initial capacity and capacity retention because, even when the anode material is produced using an aqueous anode material slurry, the viscosity decrease of the slurry and the generation of hydrogen due to the LiOH by-product are suppressed. Compared to aqueous anode material slurries containing ordinary silicon particles or silicon oxide particles, the change in viscosity is small and the generation of hydrogen is reduced, so that poor coating of the slurry and a decrease in adhesive strength due to the decrease in viscosity of the slurry can be suppressed, resulting in excellent storage stability.

[0023] Furthermore, the negative electrode according to the present invention includes a negative electrode material layer containing lithium silicon oxide as a negative electrode material, and therefore has excellent initial efficiency and suppresses volume expansion of the negative electrode, resulting in excellent capacity retention. [Brief explanation of the drawings]

[0024] The following drawings attached to this specification illustrate specific embodiments of the present invention and serve to further understand the technical concept of the present invention together with the above-mentioned content of the invention, and the present invention should not be interpreted as being limited only to the matters shown in such drawings.

[0025] [Figure 1]1 shows XRD patterns of lithium silicon oxides prepared in Examples and Comparative Examples, measured using non-monochromated CuKα radiation. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will now be described in more detail to aid in understanding the present invention.

[0027] The terms and words used in the description of the present invention and the claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define the concepts of terms in order to best describe their inventions.

[0028] Measurement method In this specification, XRD patterns were measured using a D8 Endeavor powder X-ray diffractometer (manufactured by Bruker) using CuKα radiation without using a separate monochromator, at a voltage of 40 kV, a current of 40 mA, a 2θ (Bragg angle) of 20° to 80°, a step size of 0.02°, and a time / step of 0.30 sec.

[0029] In this specification, the height of a peak in an XRD pattern is measured using the "Net Height" indicated in the create area of ​​the Bruker DIFFRAC.EVA program. Specifically, using each peak as a reference, a range of at least twice the full width at half maximum (FWHM) is taken using the create area, and then both ends of the range are dragged to adjust the range so that the net height is the highest, and the net height peak at this time is taken as the height.

[0030] In this specification, the integrated intensity of peaks in XRD patterns was evaluated using single peak fitting in the Bruker DIFFRAC.TOPAS program. The LP factor correction factor was unchecked, and a Chebyshev first-order polynomial was used for the background. PV (pseudo-Voigt) peaks were used, and fitting was performed in two intervals: 2θ = 20.0 to 23.0° and 2θ = 25.8 to 32.0°. After assigning PV peaks to all peaks observed within the interval, fitting was performed, and the calculated "Area" was used as the integrated intensity.

[0031] Lithium Silicon Oxide The present invention provides a lithium silicon oxide useful as a negative electrode material, which has excellent initial capacity and capacity retention, and in which the viscosity hardly changes during production of a slurry by an aqueous process and hydrogen generation is suppressed.

[0032] The lithium silicon oxide according to an embodiment of the present invention is characterized in that an XRD pattern measured using non-monochromated CuKα radiation has peaks at 2θ positions of 23.8±0.5°, 24.3±0.5°, and 24.7±0.5°, and satisfies the following mathematical formula 1:

[0033] [Mathematical formula 1] y sio2,max ≦0.4·y si,111

[0034] In the above mathematical formula 1, y sio2,max is the height of the highest peak among the SiO2 peaks at 2θ = 20.7 ± 0.5°, 21.6 ± 0.5°, and 26.5 ± 0.5° in the XRD pattern measured using non-monochromated CuKα radiation, and y si,111 is the height of the Si peak corresponding to the position of 2θ=28.5±0.5° in the XRD pattern.

[0035] Graphite-based anode materials are known as anode materials. Graphite-based anode materials have excellent structural stability during lithium insertion and extraction, and exhibit stable capacity retention characteristics even over long cycles. However, due to their low theoretical capacity (350mAh / g for LiC6), they are not suitable as high-capacity, high-output materials, which are currently required. Therefore, graphite-based anode materials have a theoretical capacity about 10 times higher than that of graphite (up to 4200mAh / g for LiC6). 4.4 Silicon and silicon oxides containing SiO2 (Si) have attracted attention. However, silicon-based anode materials consume three times more lithium than graphite-based anode materials, resulting in high irreversible capacity. To address the initial efficiency issue caused by the irreversible reaction of lithium ions, attempts have been made to improve initial efficiency by prelithiation of Li. Prelithiated silicon-based anode materials have the advantages of excellent charge / discharge efficiency and cycle characteristics, but they suffer from capacity loss and gas generation during processing. In particular, prelithiated silicon-based anode materials contain crystalline lithium silicate and crystalline silica (SiO2). Crystalline lithium silicate is easily soluble in water. When this prelithiated silicon-based anode material is used to prepare aqueous anode slurry, the silicon oxidizes upon contact with water and the water is reduced, generating hydrogen gas. This changes the slurry viscosity, degrading the coating properties of the slurry and causing serious problems with the slurry coating. This can result in fatal problems, such as a sudden capacity loss due to an electrical short circuit with the current collector. In addition, crystalline silica (SiO2) has the problem of reducing the initial capacity of the battery by forming crystalline lithium silicate, an irreversible phase, during the charging process, which consumes lithium.

[0036] However, the lithium silicon oxide of the present invention has a peak in a specific position range in the XRD pattern and has the property of satisfying Equation 1. Therefore, even when prepared using an aqueous anode material slurry, it is not dissolved in water, preventing poor coating of the slurry and a decrease in adhesive strength due to hydrogen generation. This allows the anode to have excellent integrity and capacity retention, as well as excellent initial capacity characteristics.

[0037] The lithium silicon oxide according to the present invention will be specifically described below.

[0038] The lithium silicon oxide according to an embodiment of the present invention is useful as an anode material, particularly as an anode material for aqueous slurries. In an XRD pattern measured using non-monochromated CuKα radiation, peaks are present at 2θ positions of 23.8±0.5°, 24.3±0.5°, and 24.7±0.5°, and the pattern satisfies the following mathematical formula 1:

[0039] [Mathematical formula 1] y sio2,max ≦0.4·y si,111

[0040] In the above mathematical formula 1, y sio2,max is the height of the highest peak among the SiO2 peaks at 2θ = 20.7 ± 0.5°, 21.6 ± 0.5°, and 26.5 ± 0.5° in the XRD pattern measured using non-monochromated CuKα radiation, and y si,111 is the height of the Si peak corresponding to the position of 2θ=28.5±0.5° in the XRD pattern.

[0041] In addition, the lithium silicon oxide may satisfy the following mathematical formula 1-1.

[0042] [Mathematical formula 1-1] 0.005 y si,111 ≦y sio2,max ≦0.4·y si,111

[0043] In the above mathematical formula 1-1, y sio2,max is the height of the highest peak among the SiO2 peaks at 2θ = 20.7 ± 0.5°, 21.6 ± 0.5°, and 26.5 ± 0.5° in the XRD pattern measured using non-monochromated CuKα radiation, and y si,111 is the height of the Si peak corresponding to the position of 2θ=28.5±0.5° in the XRD pattern.

[0044] If the crystalline SiO2 (quartz, cristobalite), which is a phase in which lithium cannot be inserted / extracted and satisfies the mathematical formula 1-1 of the lithium silicon oxide, is limited within an appropriate range, the capacity and efficiency of the lithium secondary battery containing the same are not adversely affected, and structural stability is ensured, and gas generation can be more effectively suppressed.

[0045] In addition, the lithium silicon oxide according to an embodiment of the present invention satisfies the following mathematical formula 2:

[0046] [Mathematical formula 2] I q,100 +I c,111 +I q,011 ≦0.3 I si,111

[0047] In the above mathematical formula 2, I q,100 , I c,111 and I q,011 are the integrated intensities of the SiO2 peaks at 2θ = 20.7 ± 0.5°, 21.6 ± 0.5°, and 26.5 ± 0.5° in the XRD pattern measured using unmonochromated CuKα radiation, respectively, and I si,111 is the integrated intensity of the Si peak at 2θ=28.5±0.5° in the XRD pattern.

[0048] In addition, the lithium silicon oxide may satisfy the following mathematical formula 2-1.

[0049] [Mathematical formula 2-1] 0.002 I si,111 ≦I q,100 +I c,111 +I q,011 ≦0.3 I si,111

[0050] In the above mathematical formula 2-1, I q,100 , I c,111 and I q,011are the integrated intensities of the SiO2 peaks at 2θ = 20.7 ± 0.5°, 21.6 ± 0.5°, and 26.5 ± 0.5° in the XRD pattern measured using unmonochromated CuKα radiation, respectively, and I si,111 is the integrated intensity of the Si peak at 2θ=28.5±0.5° in the XRD pattern.

[0051] When the lithium silicon oxide satisfies the above mathematical formula 2-1, the crystalline SiO2 (quartz, cristobalite), which is a phase in which lithium cannot be inserted / extracted, is limited within an appropriate range. This ensures structural stability and superior gas generation suppression without adversely affecting the capacity and efficiency of a lithium secondary battery containing the lithium silicon oxide.

[0052] In addition, the lithium silicon oxide may satisfy the following mathematical formula 3.

[0053] [Mathematical formula 3] 0≦y o3,111 ≦0.1·y backgroud

[0054] In the above mathematical formula 3, y o3,111 is the height of the Li2SiO3 peak at 2θ = 27.0 ± 0.2° in the XRD pattern measured using unmonochromated CuKα radiation, and y backgroud is the height of the background peak other than the Li2SiO3 peak at 2θ=27.0±0.2° in the XRD pattern.

[0055] As yet another example, the lithium silicon oxide may have no peak at 27.0±0.2° in an XRD pattern measured using non-monochromated CuKα radiation.

[0056] As yet another example, the lithium silicon oxide has a peak in a specific position range in the XRD pattern, satisfies Equation 1, and satisfies Equation 2.

[0057] As another example, the lithium silicon oxide satisfies the presence or absence of peaks within a specific position range in the XRD pattern, satisfies Mathematical Formula 1, and satisfies Mathematical Formula 2 and Mathematical Formula 3.

[0058] In the present invention, the lithium silicon oxide is produced by prelithiation of a silicon-based compound, for example, silicon and / or silicon oxide with Li.

[0059] On the other hand, when prelithiating a silicon-based compound, generally, crystalline lithium silicate (Li2SiO3) and lithium disilicate (Li2Si2O5) are produced by the prelithiation. However, the lithium silicate is easily soluble in water, and when using this to produce an aqueous slurry, there are problems of reduction in process and efficiency due to the generation of hydrogen gas.

[0060] However, the lithium silicon oxide according to the present invention is produced by a prelithiation process described later using a specific concentration of LiBP (lithium biphenyl), and can contain only crystalline lithium disilicate that does not contain crystalline lithium silicate and is insoluble in water. As a result, peaks exist at positions where 2θ is 23.8 ± 0.5°, 24.3 ± 0.5°, and 24.7 ± 0.5° in the XRD pattern, and there is no peak at 27.0 ± 0.2°. At the same time, it can satisfy Mathematical Formula 1 and / or Mathematical Formula 2.

[0061] By satisfying the above properties, the lithium silicon oxide according to the present invention can prevent the generation of hydrogen during the production of the slurry by an aqueous process, have no coating defects and reduction in adhesive strength, and be excellent in initial capacity characteristics and capacity retention rate.

[0062] In addition, the lithium silicon oxide can contain Si (silicon particles), SiO x (0 < x ≤ 2) (silicon oxide particles) and a lithium-containing compound.

[0063] The Si and SiO x Each of the Si particles can have an amorphous structure, and the Si particles have an average particle size (D 50 ) with the SiO x is the average particle size (D 50 ) can be included.

[0064] Furthermore, the Si or SiO x may include a carbon coating layer on the surface, and the thickness of the carbon coating layer may be 1 nm to 1 μm, or 100 nm to 1 μm.

[0065] The carbon coating layer may include a carbon-based material, and the carbon-based material may include at least one of amorphous carbon and crystalline carbon.

[0066] The crystalline carbon may further improve the conductivity of the anode material, and may be, for example, at least one selected from the group consisting of fluorene, carbon nanotubes, and graphene.

[0067] The amorphous carbon appropriately maintains the strength of the carbon coating layer and may be, for example, a carbon-based material formed by using at least one carbide selected from the group consisting of tar, pitch, and other organic substances, or a hydrocarbon as a source in a chemical vapor deposition process. The carbide of the other organic substance may be a carbide of sucrose, glucose, galactose, fructose, lactose, mannose, ribose, aldohexose, or ketohexose, or a combination thereof.

[0068] Further, the hydrocarbon can be a substituted or unsubstituted aliphatic or alicyclic hydrocarbon, or a substituted or unsubstituted aromatic hydrocarbon. Exemplarily, it can be methane, ethane, ethylene, acetylene, propane, butane, butene, pentane, isobutane or hexane, benzene, toluene, xylene, styrene, ethylbenzene, diphenylmethane, naphthalene, phenol, cresol, nitrobenzene, chlorobenzene, indene, coumarone, pyridine, anthracene or phenanthrene, etc.

[0069] The lithium-containing compound contains Si and / or SiO x which is prelithiated, and lithium metal is doped into Si and / or SiO x to form a compound. Specifically, it can contain any one or more of lithium disilicate and lithium silicide.

[0070] The lithium silicide can contain Li y Si (2 < y < 5). Exemplarily, it can be one or more selected from the group consisting of Li 4.4 Si, Li 3.75 Si, Li 3.25 Si and Li 2.33 Si.

[0071] Lithium silicon oxide manufacturing method The present invention provides a method for manufacturing the lithium silicon oxide.

[0072] The method for manufacturing the lithium silicon oxide according to an embodiment of the present invention includes a step (S1) of adding Si or SiO x (0 < x ≤ 2) particles to a lithium compound-containing solution and stirring in an inert atmosphere, and a step (S2) of separating the generated particles and then drying and firing them. The concentration of the lithium compound-containing solution can be more than 0.5M and less than 1.0M.

[0073] According to one embodiment of the present invention, a method for manufacturing lithium silicon oxide is to add a silicon-based negative electrode material to a lithium compound-containing solution with a concentration of more than 0.5 M and less than 1.0 M in which the lithium compound in an organic solvent is dissolved, and perform stirring and heat treatment. By doing so, Li is inserted and diffused inside the silicon-based negative electrode, and an appropriate redox process is carried out. Thereby, lithium silicon oxide having the above-described physical properties can be manufactured.

[0074] Hereinafter, the method for manufacturing a lithium silicon oxide composite according to one embodiment of the present invention will be described in more detail by dividing it step by step.

[0075] (S1) Step The step (S1) is a step in which Si or SiO x (0 < x ≤ 2) is prelithiated to generate lithium silicon oxide particles. Under an inert gas atmosphere, Si or SiO x (0 ≤ x ≤ 2) particles are added and stirred. The lithium compound-containing solution can have a concentration of more than 0.5 M and less than 1.0 M.

[0076] Here, the fact that the lithium compound-containing solution has a concentration of more than 0.5 M and less than 1.0 M means that the lithium compound per 1 L of the solution is dissolved in an amount of more than 0.5 mol and less than 1.0 mol.

[0077] In one embodiment of the present invention, the Si and SiO x (0 < x ≤ 2) can each have an amorphous structure. The silicon (Si) has an average particle size (D 50 ) of 1 μm to 20 μm, and the silicon oxide (SiO x (0 < x ≤ 2)) can have an average particle size (D 50 ) of 5 nm to 1 μm.

[0078] Further, the silicon and the silicon oxide can include a carbon coating layer on the surface. Here, the thickness of the carbon coating layer can be 1 nm to 1 μm, or 100 nm to 1 μm.

[0079] The carbon coating layer may include a carbon-based material, and the carbon-based material may include at least one of amorphous carbon and crystalline carbon.

[0080] The crystalline carbon may further improve the conductivity of the anode material, and may be, for example, at least one selected from the group consisting of fluorene, carbon nanotubes, and graphene.

[0081] The amorphous carbon appropriately maintains the strength of the carbon coating layer and may be, for example, a carbon-based material formed by using at least one carbide selected from the group consisting of tar, pitch, and other organic substances, or a hydrocarbon as a source in a chemical vapor deposition process. The carbide of the other organic substance may be a carbide of sucrose, glucose, galactose, fructose, lactose, mannose, ribose, aldohexose, or ketohexose, or a combination thereof.

[0082] The hydrocarbon may be a substituted or unsubstituted aliphatic or alicyclic hydrocarbon, or a substituted or unsubstituted aromatic hydrocarbon, and examples thereof include methane, ethane, ethylene, acetylene, propane, butane, butene, pentane, isobutane, hexane, benzene, toluene, xylene, styrene, ethylbenzene, diphenylmethane, naphthalene, phenol, cresol, nitrobenzene, chlorobenzene, indene, coumarone, pyridine, anthracene, and phenanthrene.

[0083] In one embodiment of the present invention, the silicon or silicon oxide can be added in an amount of more than 0.131 parts by weight and less than 0.142 parts by weight based on 100 parts by weight of the lithium compound-containing solution.

[0084] Here, the lithium compound-containing solution can be prepared by adding a polycyclic aromatic compound or a linear polyphenylene compound to an organic solvent, stirring the mixture to prepare a polycyclic aromatic compound solution or a linear polyphenylene compound solution, and then adding lithium particles to the polycyclic aromatic compound solution or the linear polyphenylene compound solution to cause a reaction.

[0085] The lithium particles react with the polycyclic aromatic compound or the linear polyphenylene compound in the polycyclic aromatic compound solution or the linear polyphenylene compound solution in a 1:1 molar ratio.

[0086] The polycyclic aromatic compound may be one or more selected from the group consisting of naphthalene, anthracene, phenanthrene, naphthacene, pentacene, pyrene, picene, triphenylene, coronene, chrysene, fluorene, and 9,9-dimethylfluorene, and the linear polyphenylene compound may be one or more selected from the group consisting of biphenyl, terphenyl, and 4,4-dimethylbiphenyl. Specifically, the polycyclic aromatic compound may be any one selected from naphthalene, fluorene, and 9,9-dimethylfluorene, and the linear polyphenylene compound may be biphenyl or 4,4-dimethylbiphenyl.

[0087] The organic solvent may be an ether solvent, a ketone solvent, an ester solvent, an alcohol solvent, an amine solvent, or a mixture thereof. Exemplary ether solvents include diethyl ether, tert-butyl methyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, or a mixture thereof. Among these, tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, and 1,2-dimethoxyethane are preferred.

[0088] The ketone solvent may be acetone, acetophenone, or the like, and the ester solvent may be methyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, or a mixture thereof.

[0089] As the alcohol solvent, methanol, ethanol, propanol, isopropyl alcohol, or a mixture thereof can be used, and as the amine solvent, methylamine, ethylamine, ethylenediamine, or a mixture thereof can be used.

[0090] The reaction to obtain the lithium compound-containing solution can be carried out at a temperature in the range of 20°C to 90°C for 0.5 to 6.0 hours with stirring. By stirring at the temperature for the period, the lithium compound can be formed more effectively.

[0091] In the step (S1), in consideration of adjusting the lithium ion diffusion rate and appropriate prelithiation, the stirring is performed by primary stirring at a temperature range of 30°C to 90°C for 1 hour or more, and then secondary stirring is performed while cooling to room temperature, and the primary stirring and secondary stirring may be performed for the same time.

[0092] (S2) Step The step (S2) is a step for producing lithium silicon oxide by separating, drying, and calcining the lithium silicon oxide particles produced in the step (S1). The step (S2) can be performed by separating the particles produced in the step (S1), drying, and calcining them.

[0093] The resulting particles can be separated from the solution by any means conventional in the art, for example, by centrifuging the solution to separate the supernatant and precipitated particles.

[0094] The drying can be carried out by a method commonly used in the art, for example, by leaving the mixture to stand at a temperature in the range of 70°C to 90°C or 75°C to 85°C for 2 hours or more.

[0095] The firing can be carried out by heat treatment in an inert gas atmosphere at a temperature range of 850° C. to 900° C. for 1 to 2 hours.

[0096] Meanwhile, in the method for preparing lithium silicon oxide according to an embodiment of the present invention, the inert gas may be argon, nitrogen, or a combination thereof.

[0097] negative electrode The present invention provides a negative electrode comprising the lithium silicon oxide.

[0098] The negative electrode according to one embodiment of the present invention includes a conductive metal current collector and a negative electrode material layer provided on at least one surface of the current collector, the negative electrode material layer including the lithium silicon oxide.

[0099] The negative electrode according to the present invention includes a negative electrode material layer containing lithium silicon oxide, and therefore has excellent initial efficiency, suppresses volume expansion of the negative electrode, and provides excellent capacity retention and long-term stability.

[0100] The conductive metal current collector includes a highly conductive metal, and is not particularly limited as long as it is non-reactive within the voltage range of the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. The current collector may have a thickness of 3 μm to 500 μm.

[0101] The negative electrode may be fabricated by mixing an aqueous solvent, the lithium silicon oxide, a binder, and a conductive material to prepare a negative electrode material slurry, and then coating the negative electrode material slurry on at least one surface of a conductive metal current collector and drying the coated negative electrode material slurry. Here, the aqueous solvent may be water.

[0102] Furthermore, the conductive material may include any material that does not undergo chemical changes and has electronic conductivity, without any particular limitation. Specific examples of the conductive material include graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive tubes such as carbon nanotubes; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives. These may be used alone or in combination.

[0103] The binder is typically added in an amount of 0.1 to 10% by weight based on the total weight of the negative electrode layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0104] Lithium secondary battery The present invention provides a lithium secondary battery including the negative electrode.

[0105] According to an embodiment of the present invention, the lithium secondary battery may include the negative electrode, the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. The lithium secondary battery may also optionally include a battery container that houses the electrode assembly including the negative electrode, the positive electrode, and the separator, and a sealing member that seals the battery container.

[0106] According to one embodiment of the present invention, the positive electrode may include a positive electrode current collector and a positive electrode material layer located on the positive electrode current collector.

[0107] According to one embodiment of the present invention, the positive electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, aluminum-cadmium alloy, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 3 μm to 500 μm, and may have fine irregularities on its surface to enhance the bonding strength of the positive electrode material. For example, the positive electrode current collector may be used in various forms, such as a film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0108] According to an embodiment of the present invention, the positive electrode layer may optionally include a binder and a conductive material in addition to the positive electrode material.

[0109] According to one embodiment of the present invention, the positive electrode material is LiCoO2, LiCoPO4, LiNiO2, Li x Ni a Co b M 1 c M 2 d O2(M 1 and M 2are each independently one element selected from the group consisting of Al, Mn, Cu, Fe, V, Cr, Mo, Ga, B, W, Mo, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, and Y, and 0.9≦x≦1.1, 0 <a<1.0、0<b<1.0、0≦c<0.5、0≦d<0.5、a+b+c+d=1である。)、LiMnO2、LiMnO3、LiMn2O3、LiMn2O4、LiMn 2-e M 3 e O2(M 3 is one or more elements selected from the group consisting of Co, Ni, Fe, Cr, Zn and Ta, and 0.01≦e≦0.1.) Li2Mn3M 4 O8(M 4 is one or more selected from the group consisting of Ci, Ni, Fe, Cu and Zn.) It can be one selected from the group consisting of LiFePO4, Li2CuO2, LiV3O8, V2O5, Cu2V2O7 and lithium metal.

[0110] According to one embodiment of the present invention, the binder is a component that helps bind the conductive material, positive electrode material, and current collector, and is typically added in an amount of 0.1 to 10 wt % based on the total weight of the positive electrode material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0111] According to one embodiment of the present invention, the conductive material of the positive electrode layer is a component for further improving the conductivity of the positive electrode material and may be added in an amount of 10 wt % or less, preferably 5 wt % or less, based on the total weight of the positive electrode layer. The conductive material is not particularly limited as long as it does not cause chemical changes in the battery and is conductive. Examples of the conductive material include graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; carbon fluoride; metal powder such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0112] According to one embodiment of the present invention, the positive electrode may be manufactured by coating a positive electrode layer forming slurry, which is prepared by dissolving or dispersing a positive electrode material, and optionally a binder and a conductive material, in a solvent, on the positive electrode current collector and drying the coating. Alternatively, the positive electrode may be manufactured by casting the positive electrode layer forming slurry on a separate support, peeling it off from the support, and laminating the resulting film on the positive electrode current collector.

[0113] According to one embodiment of the present invention, the separator separates the negative electrode and the positive electrode and provides a path for lithium ions to move. Any separator typically used in lithium secondary batteries can be used without particular limitation. In particular, a separator with low resistance to electrolyte ion movement and excellent electrolyte impregnation ability is preferred. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer, or a laminate structure of two or more layers thereof can be used. Conventional porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, can also be used. Separators coated with ceramic components or polymeric materials to ensure heat resistance or mechanical strength can also be used, and they can be selectively used in a single-layer or multi-layer structure.

[0114] According to an embodiment of the present invention, the electrolyte may be, but is not limited to, an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc., which can be used in manufacturing a lithium secondary battery. For example, the electrolyte may include an organic solvent and a lithium salt.

[0115] According to an embodiment of the present invention, the organic solvent may be any solvent capable of acting as a medium through which ions involved in the electrochemical reaction of the battery can migrate. Specifically, examples of the organic solvent include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether and tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate. Examples of solvents that can be used include carbonate-based solvents such as ethylene carbonate (PC), alcohol-based solvents such as ethyl alcohol and isopropyl alcohol, nitriles such as R-CN (where R is a hydrocarbon group having 2 to 20 carbon atoms and having a linear, branched, or cyclic structure, and may contain a double-bonded aromatic ring or an ether bond), amides such as dimethylformamide, dioxolanes such as 1,3-dioxolane, and sulfolanes. Among these, carbonate-based solvents are preferred, and mixtures of cyclic carbonates (e.g., ethylene carbonate or propylene carbonate) with high ionic conductivity and a high dielectric constant, which can improve the charge / discharge performance of batteries, and low-viscosity linear carbonate compounds (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) are more preferred.

[0116] According to one embodiment of the present invention, the lithium salt may be any compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the anion of the lithium salt may be F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - or (CF3CF2SO2)2N - The lithium salt may be at least one selected from the group consisting of: LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. The concentration of the lithium salt is preferably in the range of 0.1M to 2.0M. When the lithium salt concentration is within this range, the electrolyte has appropriate conductivity and viscosity, thereby exhibiting excellent electrolyte performance and allowing lithium ions to migrate effectively.

[0117] According to one embodiment of the present invention, in addition to the electrolyte components, the electrolyte may contain, for example, vinylene carbonate (VC), vinyl ethylene carbonate (VEC), fluoro ethylene carbonate (FEC), propane sultone (PS), 1,3-propane sultone (PRS), ethylene sulfate (Esa), succinonitrile (SN), adiponitrile (AN), hexane tricarbonitrile (HTCN), γ-butyrolactone, biphenyl (BP), cyclohexyl benzene (CHB), t-amyl benzene (tert-amyl The electrolyte may further contain one or more additives selected from the group consisting of difluoroethylene carbonate, haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinoneimine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, and aluminum trichloride. The additives may be contained in an amount of 0.1 wt % to 5 wt % based on the total weight of the electrolyte.

[0118] A lithium secondary battery including the anode according to the present invention stably exhibits excellent capacity characteristics, output characteristics, and life characteristics, and is therefore useful in portable devices such as mobile phones, notebook computers, and digital cameras, as well as in the field of electric vehicles such as hybrid electric vehicles (HEVs) and electric vehicles (EVs).

[0119] The shape of the lithium secondary battery of the present invention is not particularly limited, but may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

[0120] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for a small device, but also as a unit battery for a medium- to large-sized battery module including a large number of battery cells.

[0121] Therefore, according to one embodiment of the present invention, there is provided a battery module including the lithium secondary battery as a unit cell, and a battery pack including the same.

[0122] According to one embodiment of the present invention, the battery module or battery pack may be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and an electric vehicle (PHEV), including a plug-in hybrid electric vehicle; or a power storage system.

[0123] Example While the present invention may be embodied in various different forms, it is to be understood that the invention is not limited to the specific embodiments set forth herein, and that the invention may be embodied in various different forms without departing from the spirit or scope of the present invention.

[0124] Example 1 2.78 g of biphenyl was added to 30 ml of 2-methyltetrahydrofuran and stirred for 10 minutes. When the solution turned transparent, 0.125 g of Li powder was added thereto and stirred for 6 hours to produce a dark green 0.6 M LiBP solution.

[0125] To the LiBP solution, 4 g of SiO 50 / c (0 < x ≤ 2) powder having a carbon coating layer on the surface with an average particle diameter (D x ) of 5 μm was added and stirred at 80°C for 1 hour. The volatilized solvent was collected by a reflux condenser to maintain a constant concentration. Next, it was further stirred for 1 hour while cooling to room temperature (25°C). Here, all processes were carried out under an argon atmosphere.

[0126] Next, the solution was centrifuged to separate only the powder particles, and the separated particles were dried at 80°C for 6 hours, heated to 900°C, and heat-treated under an argon atmosphere for 2 hours to produce lithium silicon oxide.

[0127] Example 2 In Example 1 above, 0.8 M LiBP solution was produced using 3.7 g of biphenyl and 0.166 g of Li powder, and lithium silicon oxide was produced in the same manner as in Example 1 except for using this solution.

[0128] Comparative Example 1 In Example 1 above, 0.5 M LiBP solution was produced using 2.31 g of biphenyl and 0.104 g of Li powder, and lithium silicon oxide was produced in the same manner as in Example 1 except for using this solution.

[0129] Comparative Example 2 In Example 1 above, 1.0 M LiBP solution was produced using 4.62 g of biphenyl and 0.21 g of Li powder, and lithium silicon oxide was produced in the same manner as in Example 1 except for using this solution.

[0130] Experimental Example 1 The lithium silicon oxides prepared in the examples and comparative examples were subjected to XRD analysis to compare their properties. The results are shown in FIG.

[0131] XRD patterns were measured using a D8 Endeavor powder X-ray diffractometer (Bruker) using CuKα radiation without a separate monochromator. Measurements were performed at a voltage of 40 kV, a current of 40 mA, 2θ (Bragg angle) of 20° to 80°, a step size of 0.02°, and a time / step of 0.30 sec. The XRD patterns were observed for peaks at 2θ = 23.8 ± 0.5° (Peak 1), 24.3 ± 0.5° (Peak 2), and 24.7 ± 0.5° (Peak 3).

[0132] In addition, in the XRD pattern, the height of the highest SiO2 peak (y sio2,max ) and the height of the Si peak (y si,111 ) was evaluated to confirm whether the following mathematical formula 1 was satisfied. Here, the height of each peak in the XRD pattern was measured using the "Net Height" indicated in the create area of ​​the Bruker DIFFRAC.EVA program. Specifically, using each peak as a reference, a range of at least twice the full width at half maximum (FWHM) was taken using the create area, and then both ends of the range were dragged to adjust the range so that the net height was the highest, and the net height at this time was taken as the peak height.

[0133] [Mathematical formula 1] y sio2,max ≦0.4y si,111

[0134] In the above mathematical formula 1, y sio2,maxis the height of the highest peak among the SiO2 peaks at 2θ=20.7±0.5°, 21.6±0.5°, and 26.5±0.5° in the XRD pattern measured using non-monochromated CuKα radiation, and y si,111 is the height of the Si peak corresponding to the position of 2θ=28.5±0.5° in the XRD pattern.

[0135] The integrated intensity of the peaks in the XRD pattern was also evaluated to confirm whether it satisfied the following mathematical formula 2. The integrated peak intensity was measured using single peak fitting in the Bruker DIFFRAC.TOPAS program. The LP factor correction factor was unchecked, and a Chebyshev first-order polynomial was used for the background. The peak type used was pseudo-Voigt (PV), and fitting was performed in two intervals: 2θ = 20.0 to 23.0° and 2θ = 25.8 to 32.0°. All peaks observed within the interval were assigned as PV peaks, and fitting was performed. The calculated "Area" was used as the integrated intensity.

[0136] [Mathematical formula 2] I q,100 +I c,111 +I q,011 ≦0.3 I si,111

[0137] In the above mathematical formula 2, I q,100 , I c,111 and I q,011 are the integrated intensities of the SiO2 peaks at 2θ = 20.7 ± 0.5°, 21.6 ± 0.5°, and 26.5 ± 0.5° in the XRD pattern measured using unmonochromated CuKα radiation, respectively, and I si,111 is the integrated intensity of the Si peak at 2θ=28.5±0.5° in the XRD pattern.

[0138] In addition, the height of the Li2SiO3 peak (y o3,111) and background height (y backgroud ) was evaluated to confirm whether the following mathematical formula 3 was satisfied. Here, the height of each peak in the XRD pattern was measured using the Bruker DIFFRAC.EVA program. First, noise was removed using the smooth function (smooth factor = 0.15), and then the "Net Height" indicated by the create area was measured. Specifically, using each peak as a reference, a range of at least twice the full width at half maximum (FWHM) was taken using the create area, and then both ends of the range were dragged to adjust the range so that the Net Height was the highest. The Net Height at this time was calculated as the peak height (y o3,111 The difference between the Gross Int. and Net Height was calculated as the background peak height (y backgroud ) was decided.

[0139] [Mathematical formula 3] 0≦y o3,111 ≦0.1·y backgroud

[0140] In the above mathematical formula 3, y o3,111 is the height of the Li2SiO3 peak at 2θ = 27.0 ± 0.2° in the XRD pattern measured using unmonochromated CuKα radiation, and y backgroud is the height of the background peak other than the Li2SiO3 peak at 2θ=27.0±0.2° in the XRD pattern.

[0141] [Table 1]

[0142] As can be seen from Table 1 and Figure 1, the lithium silicon oxides of Examples 1 and 2 have peaks 1, 2, and 3 at 2θ=23.8±0.5°, 24.3±0.5°, and 24.7±0.5° in the XRD patterns, and satisfy Equations 1 to 3. On the other hand, the lithium silicon oxides of Comparative Examples 1 and 2 do not satisfy Equations 1 and 2, or do not satisfy Equation 3.

[0143] Experimental Example 2 Aqueous slurries of negative electrode materials were prepared using the lithium silicon oxides prepared in the examples and comparative examples, and the amounts of gas generated were measured. The results are shown in Table 2 below.

[0144] Anode material aqueous slurry was prepared by mixing lithium silicon oxide, graphite, Super-C65 as a conductive material, carboxymethyl cellulose as a binder, and styrene-butadiene rubber binder in a weight ratio of 77:19.2:1:1.1:1.6 with water as a solvent. Five grams of the anode material aqueous slurry was then sealed in an aluminum pouch and stored in an oven at 60°C. The gas generation rate was measured using a hydrometer.

[0145] [Table 2]

[0146] As can be seen from Table 2, the negative electrode material slurries containing lithium silicon oxide of Examples 1 and 2 exhibited reduced gas generation amounts compared to Comparative Examples 1 and 2. In particular, the gas generation amount was significantly reduced to 1 / 8 of that of Comparative Example 2, which does not satisfy Equation 3 in Table 1, after long-term storage.

[0147] Experimental Example 3 Half cells were produced using the lithium silicon oxides of the examples and comparative examples, and the battery characteristics were measured. The results are shown in Table 3 below.

[0148] Each lithium silicon oxide was mixed with the conductive material Super-C65 and the binder li-PAA in a weight ratio of 70:15:15 to prepare anode slurry, which was then applied to copper foil and dried, rolled, and punched to prepare the anode.

[0149] A lithium metal counter electrode was used, and a porous polyethylene separator was placed between the negative electrode and the lithium metal. An electrolyte solution containing 1M LiPF6, 1.5 wt% VC, and 0.5 wt% PS dissolved in a solvent containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 30:70 was injected to fabricate a coin half cell.

[0150] The coin half-cell was left for 24 hours, and then charged to 0.005 V at a constant current (CC) of 0.1 C in the 0.005-1.5 V vs. Li / Li+ range, then charged at a constant voltage (V) until the charging current reached 0.02 C, and discharged at a constant current (CC) of 0.1 C. The charge / discharge capacity and initial efficiency of the first cycle were measured.

[0151] [Table 3]

[0152] As can be seen from Table 3, Examples 1 and 2 are superior to Comparative Examples 1 and 2 in initial efficiency.

[0153] From the results of Tables 1 to 3, it was confirmed that the lithium silicon oxide according to the present invention has a peak in a specific position range in the XRD pattern but does not have a peak in another specific position range, and thus has a property that satisfies Equation 1. Therefore, even when prepared using an aqueous anode material slurry, the lithium silicon oxide is not dissolved in water, and gas generation can be significantly reduced. As a result, the anode has excellent stability (integrity), excellent storage stability, and excellent initial capacity and capacity retention.

Claims

1. A lithium silicon oxide having peaks at 23.8±0.5°, 24.3±0.5°, and 24.7±0.5° 2θ in an XRD pattern measured using non-monochromated CuKα radiation, and satisfying the following mathematical formula 1: [Mathematical formula 1] y ｓｉｏ２，ｍａｘ ≦0.4・y ｓｉ，１１１ In the above mathematical formula 1, y ｓｉｏ２，ｍａｘ indicates SiO2 corresponding to positions of 2θ=20.7±0.5°, 21.6±0.5°, and 26.5±0.5° in an XRD pattern measured using unmonochromated CuKα radiation. ２ is the height of the highest peak among the peaks, and y ｓｉ，１１１ is the height of the Si peak corresponding to the position of 2θ=28.5±0.5° in the XRD pattern.

2. The lithium silicon oxide of claim 1 , which satisfies the following mathematical formula 2: [Mathematical formula 2] I ｑ，１００ +I ｃ，１１１ +I ｑ，０１１ ≦0.3・I ｓｉ，１１１ In the above mathematical formula 2, I ｑ，１００ , I ｃ，１１１ and I ｑ，０１１ are SiO2 corresponding to positions of 2θ=20.7±0.5°, 21.6±0.5°, and 26.5±0.5°, respectively, in the XRD pattern measured using unmonochromated CuKα radiation. ２ is the integrated intensity of the peak, and I ｓｉ，１１１ is the integrated intensity of the Si peak at 2θ=28.5±0.5° in the XRD pattern.

3. The lithium silicon oxide of claim 1 , which satisfies the following mathematical formula 3: [Mathematical formula 3] 0≦y ｏ３，１１１ ≦0.1・y ｂａｃｋｇｒｏｕｄ In the above mathematical formula 3, y ｏ３，１１１ indicates Li at the position of 2θ=27.0±0.2° in the XRD pattern measured using unmonochromated CuKα radiation. ２ SiO ３ is the height of the peak of y ｂａｃｋｇｒｏｕｄ is Li at 2θ=27.0±0.2° in the XRD pattern. ２ SiO ３ is the height of the background peaks other than the peaks of interest.

4. 2. The lithium silicon oxide of claim 1, wherein the XRD pattern measured using unmonochromated CuKα radiation does not have a peak at 27.0±0.2°.

5. Si, SiO ｘ 2. The lithium silicon oxide of claim 1, comprising: (0<x≦2) and a lithium-containing compound.

6. The Si and SiO ｘ The lithium silicon oxide of claim 5, wherein (0<x≦2) comprises a carbon coating layer on the surface.

7. The lithium silicon oxide of claim 5 , wherein the lithium-containing compound includes at least one of lithium disilicate and lithium silicide.

8. a conductive metal current collector; a negative electrode material layer provided on at least one surface of the current collector, The negative electrode, wherein the negative electrode material layer comprises the lithium silicon oxide according to claim 1 .

9. A lithium secondary battery comprising: the negative electrode according to claim 8; a positive electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte.

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