Anode active material for lithium secondary batteries, method for manufacturing the same, and lithium secondary battery containing the same

Abstract

To provide a negative electrode active material for a lithium secondary battery that can prevent collapse of a structure due to volume expansion of silicon during charging / discharging of an active material made of silicon particles, and prevent a problem of shortening a lifespan due to collapse of an outer shell layer, which causes all silicon to be exposed to an electrolyte.SOLUTION: A negative electrode active material for a lithium secondary battery according to the present invention includes a composite including a core and a first shell layer surrounding the core, a plurality of composites and a second shell layer surrounding the plurality of composites, and the composites include metal particles and carbon, and an adjacent distance between the composites is 80 nm to 300 nm.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a negative electrode active material for a lithium secondary battery, a method for producing the same, and a lithium secondary battery including the same.

Background Art

[0002] A "battery" is an element that switches chemical energy into electrical energy. A "secondary battery", unlike a primary battery, means a battery that can be recharged and used again after being discharged. Among them, a "lithium secondary battery" produces electricity through a chemical reaction in which lithium ions move from the negative electrode to the positive electrode during discharge.

[0003] Recently, the market demand for lithium secondary batteries has been rapidly increasing. Therefore, while its applications are diversifying, the required performance is also being adjusted upward, and there are demands for high capacity and long life of lithium secondary batteries. Currently, the widely used negative electrode active material is graphite. However, its theoretical capacity is 372 mAh / g, which has insufficient performance in terms of the high capacity required in the market. For the high capacity of the battery, new substances represented as materials for the negative electrode active material include silicon (Si) or its compounds.

[0004] However, there are limitations to immediately applying all silicon as the negative electrode active material. Specifically, during the charge / discharge process, the structure of the active material collapses with a 300 - 400% volume expansion, which causes an electrical short circuit of the particles in the electrode plate, increasing the resistance. Also, the direct contact with the electrolyte through the damaged part causes an oxidation reaction of silicon, rapidly reducing the battery life.

[0005] Methods for compensating for the disadvantages of such silicon materials have been publicly disclosed. For example, a method of pulverizing silicon primary particles to the nanometer (nm) level. However, there is a disadvantage that as the size of the silicon primary particles decreases, the degree of oxidation increases, and the initial efficiency decreases when evaluating battery performance.

[0006] Another method involves forming a coating layer on the outer casing of the silicon particle core to suppress expansion. However, this method has the problem that if the coating layer is damaged by repeated charging and discharging, all the silicon particles forming the core will be exposed to the electrolyte simultaneously, drastically shortening the battery's lifespan. [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention aims to provide a negative electrode active material for lithium secondary batteries that can prevent structural collapse due to the volume expansion of silicon during charging / discharging of an active material made of silicon particles, while also preventing the problem of shortened lifespan due to the collapse of the outer shell layer exposing all silicon to the electrolyte.

[0008] However, the problems that this invention aims to solve are not limited to those mentioned above, and further problems not mentioned can be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0009] According to one embodiment of the present invention, a negative electrode active material for a lithium secondary battery is provided, comprising a composite including a core and a first shell layer surrounding the core, and a plurality of composites and a second shell layer surrounding the plurality of composites, wherein the composites include metal particles and carbon, and the adjacent distance between the composites is 80 nm to 300 nm.

[0010] According to another embodiment of the present invention, a lithium secondary battery is provided that includes a negative electrode active material for a lithium secondary battery according to one embodiment of the present invention.

[0011] A further embodiment of the present invention provides a method for producing a negative electrode active material for a lithium secondary battery, comprising the steps of: grinding a silicon-containing mixture (S1); spray-drying the mixture to produce a silicon precursor (S2); a primary compounding step (S3) to produce a composite with silicon precursor powder, amorphous carbon precursor, and crystalline carbon; and a secondary compounding step (S4) to produce a negative electrode active material with the composite and carbon precursor. [Effects of the Invention]

[0012] The negative electrode active material for lithium secondary batteries of the present invention has a structure that includes multiple shells surrounding a core, and by having optimized spacing between the composites, it is possible to prevent structural collapse due to volume expansion of the negative electrode active material and a sharp decline in battery performance, thereby enabling the manufacture of lithium secondary batteries with a long lifespan.

[0013] The effects of the present invention are not limited to those described above, but should be understood to include all effects that can be inferred from the detailed description of the present invention or the configuration of the invention as described in the claims. [Brief explanation of the drawing]

[0014] [Figure 1] This figure shows a cross-section of a negative electrode active material for a lithium secondary battery according to one embodiment of the present invention. [Figure 2] The capacity retention rate (retention) results for a lithium secondary battery according to another embodiment of the present invention are shown. [Modes for carrying out the invention]

[0015] The embodiments will be described in detail below with reference to the attached drawings. However, various modifications may be made to the embodiments, and the scope of the patent application will not be limited or restricted by such embodiments. All modifications, equivalents, or substitutes to the embodiments should be understood to be included within the scope of the patent.

[0016] The terms used in the embodiments are for illustrative purposes only and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “includes” or “having” indicate the presence of features, figures, steps, actions, components, parts, or combinations thereof described in the specification, and should not be understood as preemptively excluding the possibility of the presence or addition of one or more other features, figures, steps, actions, components, parts, or combinations thereof.

[0017] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as those generally understood by a person of ordinary skill in the art to which this embodiment belongs. Commonly used, predefined terms should be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not as ideal or overly formal unless expressly defined herein.

[0018] Furthermore, when explaining with reference to the attached drawings, the same reference numerals will be used for the same components regardless of the reference numerals in the drawings, and redundant explanations will be omitted. In the description of embodiments, if it is determined that a specific explanation of related prior art would unnecessarily obscure the gist of the embodiment, such detailed explanation will be omitted.

[0019] Furthermore, when describing the components of the embodiments, terms such as first, second, A, B, (a), (b), etc., may be used. Such terms are merely for distinguishing a component from other components, and do not limit the essence, order, or sequence of the component.

[0020] Components included in any one embodiment and components having a common function shall be described using the same name in other embodiments. Unless otherwise stated, the descriptions provided in any one embodiment can be applied to other embodiments, and specific descriptions within overlapping ranges shall be omitted.

[0021] Throughout the specification, when any part states that a component "includes" something, this does not exclude other components and means that other components may further be included.

[0022] Throughout the specification, the "adjacent distance between complexes" means the shortest distance from the outermost contour of one complex to the outermost contour of another complex.

[0023] According to one embodiment of the present invention, a negative electrode active material for a lithium secondary battery can be provided, which includes a complex including a core and a first shell layer surrounding the core, and a plurality of complexes and a second shell layer surrounding the plurality of complexes. Here, the complex includes metal particles and carbon, and the adjacent distance between the complexes may be 80 nm to 300 nm, preferably 100 nm to 150 nm. If the adjacent distance between the complexes is less than 80 nm, the structure of the complex may collapse during the expansion of the silicon volume. On the other hand, when manufacturing the negative electrode active material, if a substance for forming a shell layer is added to such an extent that the adjacent distance between the complexes exceeds 300 nm, the amount of petroleum pitch, which is a precursor of amorphous carbon, increases, resulting in the phenomenon that the negative electrode active materials agglomerate. It is difficult to control the form and size of the negative electrode active material. When a current collector plate is manufactured using such a negative electrode active material, there is a high probability of defects occurring during the process of manufacturing the current collector plate, making it difficult to evaluate the battery.

[0024] The adjacent distance between the complexes may be uniform within the above-described range. If the adjacent distance between the complexes is not uniform and exceeds the above-described range to be diverse, the structure of the complex will collapse due to the expansion of the silicon volume in the part where the distance between the complexes is close, which may cause the collapse of the overall structure of the negative electrode active material, thus shortening the lifespan of the lithium secondary battery.

[0025] In one embodiment of the present invention, the second shell layer may include one or more selected from the group consisting of crystalline and amorphous carbon. The second shell layer not only protects the structure of the composite but also serves to electrically connect the composite.

[0026] As an example, the crystalline carbon may include graphite-based carbon. The graphite-based carbon may be natural graphite that is naturally produced and mined, or artificial graphite (artificial, synthetic, pyrolytic graphite) produced by heat-treating petroleum-based and coal-based pitches, etc.

[0027] The amorphous carbon may be produced, for example, from substances such as sucrose, phenol, naphthalene, polyvinyl alcohol resin, furfuryl alcohol resin, polyacrylonitrile resin, styrene resin, polyimide resin, epoxy, vinyl chloride resin, coal-based pitch, petroleum-based pitch, polyvinyl chloride, mesophase pitch, and tar.

[0028] However, it is not limited to the described examples.

[0029] In one embodiment of the present invention, the strength of the second shell layer may be greater than that of the first shell layer. When manufacturing the second shell layer, if a carbon precursor with a higher softening point than the carbon precursor added during the manufacture of the first shell layer is added, problems caused by easy softening due to heat and stress generated during the composite process can be prevented. Subsequently, less volatile matter is removed during the heat treatment process, and a second shell layer with greater strength than the first shell layer can be formed. For example, the softening point of the carbon precursor added when manufacturing the first shell layer may be 100°C or more and less than 200°C, while the softening point of the carbon precursor added when manufacturing the second shell layer may be 200°C to 300°C. The high strength of the second shell layer can help maintain the structure of the negative electrode active material despite the expansion of the composite.

[0030] In one embodiment of the present invention, the core may include carbon bonding portions between metal particles. The carbon bonding portions may include one or more selected from the group consisting of crystalline and amorphous carbon. Examples of crystalline and amorphous carbon are the same as those described above.

[0031] The carbon bonding reduces the contact resistance between particles when electrons move, resulting in improved electrical conductivity and enabling the acquisition of good output characteristics and charging speed. Furthermore, the bonding between silicon particles is strengthened, allowing the electrical conduction paths of the metal particles to be maintained and stable electrochemical reactions to occur even during continuous charging / discharging of the lithium secondary battery, resulting in improved lifespan characteristics (long life).

[0032] In one embodiment of the present invention, the core may be porous. The pores within the core can provide space for a single silicon particle to expand during charging / discharging. For example, the porosity of the core may be 20-30%. If the porosity is less than 20%, structural collapse of the first shell layer occurs when the active material expands in volume, which can worsen the lifespan characteristics of the secondary battery containing it. On the other hand, if the porosity exceeds 30%, a core with weak durability is formed, and such a core's structure is destroyed by stress during the composite formation process, resulting in the formation of a negative electrode active material with an unclear boundary between the core and the shell. Furthermore, the electrical conductivity of the active material decreases, leading to a problem of reduced initial efficiency.

[0033] In one embodiment of the present invention, the diameter of the core may be 800 nm to 1200 nm.

[0034] In one embodiment of the present invention, the metal particles may include at least one selected from the group consisting of silicon, magnesium, aluminum, calcium, iron, manganese, cobalt, nickel, zinc, germanium, tin, lead, oxides thereof, and alloys thereof. For example, the metal particles may be flaky silicon. Silicon has the advantage of having an energy density about 10 times higher than graphite and a fast charge / discharge rate.

[0035] In one embodiment of the present invention, the diameter of the metal particles may be 20 nm to 120 nm. For example, if the metal has a flaky structure with a major axis and a minor axis, the major axis and minor axis may be 80 nm to 120 nm and 20 nm to 60 nm, respectively. However, it is not limited thereto.

[0036] In one embodiment of the present invention, the first shell layer may include one or more selected from the group consisting of crystalline and amorphous carbon. Examples of crystalline and amorphous carbon are the same as those described above.

[0037] In one embodiment of the present invention, the thickness of the first shell layer may be 100 nm to 150 nm. If the thickness of the first shell layer is less than 100 nm, the shell becomes more prone to collapse, and the battery life characteristics deteriorate. On the other hand, if a material is introduced to form the shell layer such that the thickness of the first shell layer exceeds 150 nm, a single shell layer surrounding multiple cores is formed, making it impossible to manufacture a negative electrode active material having the structure targeted by the present invention. Such a structure has the problem that it is difficult to maintain the performance of the battery for a long time compared to a negative electrode active material containing multiple shells.

[0038] According to another embodiment of the present invention, a lithium secondary battery containing the negative electrode active material for a lithium secondary battery can be provided.

[0039] A lithium secondary battery includes a positive electrode, a negative electrode, an electrolyte, and a separator membrane.

[0040] The positive electrode, as a source of lithium ions, comprises a substrate, a positive electrode active material, a conductive material, and a binder, and a compound such as lithium oxide may be used as the positive electrode active material.

[0041] On the other hand, the negative electrode includes a base material, a negative electrode active material, a conductive material, and a binder, and the negative electrode active material stores or releases lithium ions from the positive electrode to allow current to flow.

[0042] The separation membrane functions to block physical contact between the positive and negative electrodes, contains micropores, and is permeable to lithium ions. The electrolyte may be a non-aqueous electrolyte, a solid electrolyte, or the like, as a medium that enables the movement of lithium ions.

[0043] In a further embodiment of the present invention, a method for producing a negative electrode active material for a lithium secondary battery according to one embodiment of the present invention can be provided. The method for producing a negative electrode active material for a lithium secondary battery includes the steps of: grinding a silicon-containing mixture (S1); spray-drying the mixture to produce a silicon precursor (S2); a primary compounding step (S3) to produce a composite with silicon precursor powder, amorphous carbon precursor, and crystalline carbon; and a secondary compounding step (S4) to produce a negative electrode active material with the composite and carbon precursor. Each step will be described in detail below.

[0044] In step (S1), a mixture containing silicon, alcohol, and additives is added to a bead mill to produce a solution that is ground to an intermediate particle size (D(50)) of 80 nm to 120 nm.

[0045] In step (S2), the solution is spray-dried at a discharge temperature of 50°C to 60°C to produce a silicon precursor powder with an intermediate particle size of 1 μm.

[0046] In step (S3), the silicon precursor powder, amorphous carbon precursor, and crystalline carbon are compounded in a 1:1:1 ratio for 10 minutes to produce a material having a core-shale structure. As the amorphous carbon precursor, pitch-type carbon with a softening point of 100°C or higher and less than 200°C may be used, and graphite may be used as the crystalline carbon. Subsequently, the material having the core-shale structure can be heat-treated at 800 to 1000°C to form a composite.

[0047] In step (S4), the composite and the carbon precursor are mixed in a weight ratio greater than 1:0.4 and less than 1:0.7, compounding is performed for 10 minutes, and then the negative electrode active material is produced by heat treatment at 800 to 1000°C. When the composite and the carbon precursor are mixed in the above weight ratio, a negative electrode active material can be produced with a uniform adjacent distance of 80 nm to 300 nm, preferably 100 nm to 150 nm. Here, the carbon precursor may be crystalline carbon or amorphous carbon precursor, and the softening point of the carbon precursor used in step (S4) may be higher than the softening point of the carbon precursor used in step (S3). Therefore, a second shell with higher strength than the first shell can be formed.

[0048] The embodiments will be described in detail below with reference to the attached drawings. However, various modifications have been made to the embodiments, and the scope of the patent application will not be limited or restricted by such embodiments. All modifications, equivalents, or substitutes to the embodiments should be understood as being included within the scope of the patent.

[0049] Test Example 1: Manufacturing of negative electrode active material for lithium secondary batteries Negative electrode active materials for lithium secondary batteries were manufactured according to Embodiment 1 and Comparative Examples 1-5. Here, the distance between composites was determined by cutting the cross-section of the composite using a focused ion beam (FIB) and then analyzing it with a scanning electron microscope (SEM).

[0050] Embodiment 1 A negative electrode active material for lithium secondary batteries, having a core, first and second shell layers, and with an adjacent distance between composites of 100 nm to 150 nm, was manufactured by the following method.

[0051] High-purity silicon (99.5% or higher), isopropyl alcohol, and additives, ground to an intermediate particle size (D(50)) of 8 μm, were placed in a bead mill in a weight ratio of 1:15:0.5 and ground to a D(50) of 90 nm. The ground solution was then spray-dried to produce a silicon precursor powder with a D(50) of 1 μm.

[0052] Subsequently, the silicon precursor powder, petroleum-based pitch with a softening point of 150°C, and graphite (purity of 99.9% or higher, particle size of 200 mesh or higher) were added to a compounding device (manufactured by Hansol Chemical Co., Ltd.) in a weight ratio of 1:1:1, and primary compounding was performed for 10 minutes. After that, the composite was produced by heat treatment at 900°C.

[0053] Next, the composite material and petroleum-based pitch with a softening point of 250°C were placed in a compounding apparatus in a weight ratio of 1:0.55 and secondary compounding was performed for 10 minutes, after which the negative electrode active material was produced by heat treatment at 900°C.

[0054] Comparative Example 1 The same method as in Embodiment 1 was used, with the exception that the composite and petroleum-based pitch at 250°C were added in a weight ratio of 1:0.4 during secondary composite formation. This resulted in the production of a negative electrode active material having a core, first and second shell layers, with an adjacent distance between composites of less than 80 nm.

[0055] Comparative Example 2 The procedure was carried out in the same manner as in Embodiment 1, with the exception that the composite and petroleum-based pitch with a softening point of 250°C were added in a weight ratio of 1:0.2 during secondary composite formation. This resulted in the production of a negative electrode active material having only a core and a first shell layer.

[0056] Comparative Example 3 The same method as in Embodiment 1 was used, with the exception that the composite and petroleum-based pitch with a softening point of 250°C were added in a weight ratio of 1:0.7 during secondary composite formation. This resulted in the production of a negative electrode active material having a core, first and second shell layers, with adjacent distances between composites exceeding 300 nm.

[0057] Comparative Example 4 The same method as in Embodiment 1 was used, with the exception that the composite material and petroleum-based pitch with a softening point of 250°C were added in a 1:1 weight ratio during the secondary composite formation. This resulted in the production of negative electrode active materials having a random, non-spherical shape and varying sizes. However, since the negative electrode active materials did not exist independently but were formed in random clumps, it was difficult to measure the adjacent distances between the composite materials.

[0058] Comparative Example 5 The procedure was carried out in the same manner as in Embodiment 1, except that primary composite formation was omitted. This resulted in the production of a negative electrode active material having a core and a second shell layer, with an adjacent distance between composites of 100 nm to 150 nm.

[0059] Test Example 2: Manufacturing of Lithium-ion Rechargeable Batteries For electrochemical evaluation, the negative electrode of the lithium secondary battery was manufactured in the following steps. First, a negative electrode active material slurry was prepared by mixing the negative electrode active material (93.5% by weight relative to the total weight of the slurry), carbon conductive material (3% by weight relative to the total weight of the slurry), carboxymethylcellulose (1.5% by weight relative to the total weight of the slurry), and styrene-butadiene binder (2% by weight relative to the total weight of the slurry) prepared according to Embodiment 1 and Comparative Examples 1-5 above. Subsequently, the negative electrode was manufactured by coating this slurry onto a copper wheel (Cu foil) current collector, drying it, and rolling it at a composite density of 1.55 g / cc.

[0060] The positive electrode was manufactured by the following method: NCM (LiNiMnCoO2) positive electrode active material (96% by weight of the total weight of the mixture), acetylene black conductive material (2% by weight of the total weight of the mixture), and polyvinylidene fluoride binder (2% by weight of the total weight of the mixture) were mixed in an N-methylpyrrolidone solvent to produce the mixture.

[0061] During the full cell evaluation, a full cell was manufactured using the NCM active material cathode as the counter electrode, with a volume ratio of 1:1 between the NCM active material cathode and the manufactured anode. A mixed solution of ethylene carbonate and diethyl carbonate in a volume ratio of 3:7 was used as the electrolyte.

[0062] Test Example 3: Electrochemical Characterization of Lithium-ion Secondary Batteries 2032 coin cells were used to evaluate electrochemical properties, and expansion rate and lifetime characteristics were evaluated in full cells.

[0063] expansion rate Charging and discharging were performed under 1C conditions using a full cell manufactured with the aforementioned negative electrode active material. The battery thickness was measured and automatically recorded in real time during the charging and discharging steps via a directly manufactured device. The expansion rate was calculated using the following formula.

[0064]

number

[0065] [Table 1] Life characteristics Charging and discharging were performed under 1C conditions using a full cell manufactured with the aforementioned negative electrode active material. The capacity retention rate of the lithium secondary battery after 500 charge / discharge cycles is shown in Figure 2 and Table 2 below.

[0066] [Table 2] Based on the above test examples, it is predicted that by using the negative electrode active material for lithium secondary batteries described in the claims of the present invention, the charge / discharge performance of silicon can be maintained for a longer period through the structure of the negative electrode active material having multiple shell layers, and structural collapse due to the volume expansion of silicon can be prevented by optimizing and homogenizing the spacing between composites within the negative electrode active material, thereby enabling the manufacture of lithium secondary batteries with excellent efficiency and long lifespan characteristics.

[0067] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is not limited to the embodiments described above, and a person with ordinary skill in the art can apply various technical modifications and variations based on the above. For example, the described techniques may be performed in a different order than described, and / or the described systems, structures, devices, circuits, and other components may be combined or assembled in a different manner than described, or substituted or replaced by other components or equivalents, and still achieve appropriate results.

[0068] Therefore, other realizations, other embodiments, and those equivalent to the claims described below also fall within the scope of the claims. [Explanation of Symbols]

[0069] 1: Negative electrode active material for lithium secondary batteries 10: Core 20: First shell layer 30: Second shell layer 40: Adjacent distance between complexes

Claims

1. A plurality of composites, each formed to include a core and a first shell layer surrounding the core, The plurality of composites are dispersed inside, and a second shell layer surrounds the plurality of composites so as to separate them from each other. A negative electrode active material for lithium secondary batteries, comprising: The core includes metal particles and carbon bonding portions between the metal particles, The aforementioned core is porous, The composite comprises metal particles and carbon. A negative electrode active material for a lithium secondary battery, wherein the distance between adjacent composites separated by the second shell layer is 80 nm to 300 nm.

2. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the distance between adjacent composites is 100 nm to 150 nm.

3. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the second shell layer comprises one or more selected from the group consisting of crystalline and amorphous carbon.

4. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the strength of the second shell layer is greater than the strength of the first shell layer.

5. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the carbon linkage portion comprises one or more selected from the group consisting of crystalline and amorphous carbon.

6. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the diameter of the core is 800 nm to 1200 nm.

7. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the metal particles include at least one selected from the group consisting of silicon, magnesium, aluminum, calcium, iron, manganese, cobalt, nickel, zinc, germanium, tin, lead, oxides thereof, and alloys thereof.

8. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the metal particles include flaky silicon.

9. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the diameter of the metal particles is 20 nm to 120 nm.

10. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the first shell layer comprises one or more selected from the group consisting of crystalline and amorphous carbon.

11. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the thickness of the first shell layer is 100 nm to 150 nm.

12. The negative electrode active material for a lithium secondary battery according to any one of claims 3, 5, and 10, wherein the crystalline carbon includes graphite-based carbon.

13. The amorphous carbon is produced from one or more selected from the group consisting of sucrose, phenol, naphthalene, polyvinyl alcohol resin, furfuryl alcohol resin, polyacrylonitrile resin, styrene resin, polyimide resin, epoxy, vinyl chloride resin, coal-based pitch, petroleum-based pitch, polyvinyl chloride, mesophase pitch, and tar, as a negative electrode active material for a lithium secondary battery according to any one of claims 3, 5, and 10.

14. A lithium secondary battery comprising the negative electrode active material for a lithium secondary battery described in claim 1.

15. Step (S1) of grinding a mixture containing silicon, Step (S2) involves spray-drying the mixture to produce a silicon precursor, A primary compounding step (S3) is performed to produce a composite with silicon precursor powder, amorphous carbon precursor, and crystalline carbon, A secondary compounding step (S4) is performed to produce a negative electrode active material using the aforementioned composite and carbon precursor, A method for producing a negative electrode active material for a lithium secondary battery according to claim 1, including the method described in claim 1.

16. The method for producing a negative electrode active material for a lithium secondary battery according to claim 15, wherein in step S4, the weight ratio of the composite and the carbon precursor is greater than 1:0.4 and less than 1:0.7.

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