Anode material using spheroidized natural graphite and method for manufacturing same

Abstract

One aspect of the present invention provides a more economical anode material using spheroidized natural graphite and a method for manufacturing same, wherein spheroidized natural graphite fine powder in a classification step is used as the anode material and thus a production yield of the spheroidized natural graphite is increased.

Description

Negative electrode material using spherical natural graphite and its manufacturing method

[0001] The present invention relates to an anode material for a lithium secondary battery and a method for manufacturing the same. More specifically, the present invention relates to an anode material for a lithium secondary battery using spherical natural graphite and a method for manufacturing the same.

[0002] Currently, most spheroidized natural graphite is produced in China. This existing Chinese spheroidization process requires equipment tailored to the size of the natural graphite, requiring a series of ACM (Air Classified Mill) units, such as the ACM-60, ACM-50, and ACM-30. The sequential numbers listed on the ACM indicate the loading volume of the unit. Because the final classification yield of this serial spheroidization process is only around 35% to 40%, more than 60% of the natural graphite raw material used in the process is wasted. Furthermore, since the existing spheroidization process simultaneously crushes and collects fine particles in each ACM unit, the loss of fine particles during the spheroidization process is inevitable.

[0003] The present invention aims to provide a negative electrode material using spherical natural graphite and a method for manufacturing the same.

[0004] More specifically, the present invention aims to provide a negative electrode material and a manufacturing method thereof utilizing spherical natural graphite powder inevitably generated during a classification process.

[0005] The subject matter of the present invention is not limited to the above-described contents.

[0006] One aspect of the present invention provides an anode material comprising first spherical natural graphite and composite graphite particles, wherein the composite graphite particles comprise second spherical natural graphite and amorphous carbon, wherein the center particle size (D50) of the first spherical natural graphite has a target particle size, and the center particle size (D50) of the second spherical natural graphite has a particle size smaller than the target particle size.

[0007] The target particle size mentioned above is 15㎛ or more and 18㎛ or less, and the particle size smaller than the target particle size mentioned above may be 6㎛ or more and 13㎛ or less.

[0008] The center particle size (D50) of the aforementioned composite graphite particles may be 8 ㎛ or more and 14 ㎛ or less.

[0009] The aforementioned composite graphite particles may be included in an amount of 15 wt% or more and 30 wt% or less based on the total weight of the negative electrode material.

[0010] The aforementioned amorphous carbon may be included in an amount of 10 to 30 wt% based on the total weight of the aforementioned second spherical natural graphite.

[0011] Another aspect of the present invention provides a method for manufacturing an anode material, comprising: a step of spheroidizing natural graphite; a step of classifying the natural graphite to obtain first spheroidized natural graphite having a center particle size (D50) of a target particle size and second spheroidized natural graphite having a center particle size (D50) smaller than the target particle size; a step of mixing the second spheroidized natural graphite with pitch to obtain a mixture; a step of heat-treating the mixture to obtain composite graphite particles; and a step of mixing the composite graphite particles with the first spheroidized natural graphite.

[0012] The aforementioned target particle size may be 15 ㎛ or more and 18 ㎛ or less, and a particle size smaller than the aforementioned target particle size may be 6 ㎛ or more and 13 ㎛ or less.

[0013] The above-mentioned classification can be performed using a classifier that separates particle sizes by using the principle that the distance traveled by the powder changes depending on the weight by blowing the powder with an air jet. As a non-limiting example, the above-mentioned classifier can be an Elbow Jet Air Classifier.

[0014] In addition, the aforementioned classification can be performed using a classifier that classifies particle sizes by rotation of the rotor based on a balance between the centrifugal force of the rotor and the centrifugal force of the air flow, and the aforementioned classifier can be a 50 ATP air classifier.

[0015] The center particle size (D50) of the aforementioned composite graphite particles may be 8 ㎛ or more and 14 ㎛ or less.

[0016] The aforementioned composite graphite particles may be included in an amount of 15 wt% or more and 30 wt% or less based on the total weight of the negative electrode material.

[0017] The aforementioned pitch can be mixed in an amount of 10 to 30 wt% based on the total weight of the aforementioned second spherical natural graphite.

[0018] The present invention utilizes spheroidized natural graphite fines from the classification stage as a cathode material, thereby improving the production yield of spheroidized natural graphite. Accordingly, the present invention can provide a more economical cathode material utilizing spheroidized natural graphite and a method for manufacturing the same.

[0019] Figure 1 is a graph showing the particle sizes of invention samples 1 and 2 and the reference sample.

[0020] Figure 2 is a schematic diagram showing a simplified manufacturing method of Invention Example 1.

[0021] Figure 3 is a graph showing the particle size distribution of Invention Example 1.

[0022] Figure 4 is a graph showing the particle size distribution of Invention Example 2.

[0023] Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0024] In this specification, the term "including" is used to indicate that other components may be included rather than excluding other components unless specifically stated to the contrary.

[0025] Additionally, unless otherwise specifically provided in the specification of the present invention, the % unit means weight%.

[0026]

[0027] The classification process for spheroidized natural graphite inevitably generates fine particles of spheroidized natural graphite. Therefore, the ability to reuse these fine particles, like the carbon ash used to control the carbon concentration of pig iron during the steelmaking process, significantly impacts the economic viability of the product.

[0028] The inventors of the present invention have found that when the above spherical natural graphite powder is used as a negative electrode material, the production yield of spherical natural graphite can be improved, and have thus derived the present invention.

[0029] In this respect, the negative electrode material according to one embodiment of the present invention may include first spherical natural graphite and composite graphite particles, and the composite graphite particles may include second spherical natural graphite and amorphous carbon. In this case, the center particle size (D50) of the first spherical natural graphite may have a target particle size, and the center particle size (D50) of the second spherical natural graphite may have a particle size smaller than the target particle size. Each configuration is described in detail below.

[0030] First, the negative electrode material according to one embodiment of the present invention may include first spherical natural graphite and composite graphite particles.

[0031] At this time, the center particle size (D50) of the first spherical natural graphite may have a target particle size. Throughout the specification of the present invention, the target particle size is defined as the center particle size targeted in the classification step after sphericalization of the natural graphite raw material.

[0032] More specifically, in one embodiment of the present invention, the target particle size may be 15 μm or more and 18 μm or less. When the target particle size is 15 μm or more and 18 μm or less, the energy density of the electrode including the spheroidized natural graphite can be secured high. In another embodiment, the target particle size may be 16 μm or more and 17.5 μm or less, and in another embodiment, it may be 16.5 μm or more and 17.0 μm or less. However, considering that the target particle size may vary depending on the use and purpose of the invention, it is not necessarily limited to the above-described range.

[0033] Meanwhile, the negative electrode material according to one embodiment of the present invention may include composite graphite particles.

[0034] For example, the center particle size of the composite graphite particles may be 8 μm or more in order to prevent excessive generation of SEI (Solid Electrolyte Interphase) and a decrease in electrode efficiency. In another embodiment, the center particle size of the composite graphite particles may be 9 μm or more, and in another embodiment, 10 μm or more. On the other hand, when the center particle size of the composite graphite particles exceeds 14 μm, the charge / discharge speed may decrease as the particles become excessively large, and therefore, the upper limit of the center particle size of the composite graphite particles in the present invention may be 14 μm. In another embodiment, the center particle size of the composite graphite particles may be 12 μm or less, and in another embodiment, 11 μm or less.

[0035] In addition, as described below, the composite graphite particles have the advantage of superior cycle characteristics compared to the first spherical natural graphite by combining the second spherical natural graphite having a relatively small center particle size with amorphous carbon. Therefore, the present invention can improve the cycle characteristics of the negative electrode material itself by including the composite graphite particles in an amount of 15 wt% or more with respect to the total weight of the negative electrode material. In this case, the density of the electrode can also be increased by appropriately mixing the first spherical natural graphite and the composite graphite particles having different center particle sizes. In another embodiment, the composite graphite particles may be included in an amount of 20 wt% or more, and in another embodiment, it may be included in an amount of 25 wt% or more. On the other hand, when the composite graphite particles are included in an amount exceeding 30 wt%, a problem may arise in that the capacity as the negative electrode material is reduced as the proportion of amorphous carbon having a relatively small capacity increases in the negative electrode material. Therefore, the present invention can include the composite graphite particles in an amount of 30 wt% or less. In another embodiment, the composite graphite particles may be included in an amount of 25 wt% or less, and in another embodiment, may be included in an amount of 20 wt% or less.

[0036] The above composite graphite particles may include second spherical natural graphite. In addition, but not necessarily limited thereto, the second spherical natural graphite may be fine particles inevitably generated during the classification step after sphericalization of the natural graphite raw material.

[0037] According to one embodiment of the present invention, the second spherical natural graphite may have a center particle size smaller than the target particle size. More specifically, according to one embodiment of the present invention, the center particle size smaller than the target particle size may be 6 μm or more and 13 μm or less. However, the present invention is not necessarily limited thereto. In another embodiment, the center particle size may be 9 μm or more and 12 μm or less, and in another embodiment, the center particle size may be 10 μm or more and 11.5 μm or less.

[0038] When only the second spherical graphite, which is the natural graphite fine powder that is inevitably generated in the classification stage after the existing spherical graphite, is used as the negative electrode material, there is a problem in that the specific surface area of ​​the negative electrode material increases and SEI (Solid Electrolyte Interphase) is excessively formed, which deteriorates the cycle characteristics of the negative electrode material or makes it impossible to secure the desired level of capacity and efficiency.

[0039] To address this, the composite graphite particles according to one embodiment of the present invention may include amorphous carbon together with second spherical graphite.

[0040] The amorphous carbon described above can bind the second spherical natural graphites and simultaneously suppress the volume expansion of the anode material that occurs during charge and discharge, thereby improving the cycle characteristics of the anode material. Furthermore, the amorphous carbon can induce rapid charge and discharge rates of lithium, thereby contributing to the provision of an anode material suitable for high-speed charge and discharge applications.

[0041] For the purpose described above, the amorphous carbon may be included in an amount of 10% or more based on the total weight of the second spherical natural graphite. In another embodiment, the amorphous carbon may be included in an amount of 15% or more based on the total weight of the second spherical natural graphite, and in another embodiment, the amorphous carbon may be included in an amount of 20% or more based on the total weight of the second spherical natural graphite. On the other hand, when the amorphous carbon is included in an amount exceeding 30% by weight based on the total weight of the second spherical natural graphite, the capacity of the negative electrode material may decrease as the carbon derived from the pitch increases. Therefore, the present invention provides that the amorphous carbon may be included in an amount of 30% or less based on the total weight of the second spherical natural graphite. In another embodiment, the amorphous carbon may be included in an amount of 25% or less based on the total weight of the second spherical natural graphite, and in another embodiment, the amorphous carbon may be included in an amount of 20% or less based on the total weight of the second spherical natural graphite.

[0042]

[0043] The above amorphous carbon may be derived from pitch, and derived from pitch may mean that the pitch has been carbonized through heat treatment.

[0044] As described above, the negative electrode material of the present invention can have a superior charge / discharge rate than a negative electrode material that includes only the first spherical natural graphite having a target particle size by including composite graphite particles including the second spherical natural graphite and amorphous carbon.

[0045] Furthermore, if the second spherical natural graphite is a fine particle inevitably generated during the classification process of spherical natural graphite, the present invention can manufacture an anode material by utilizing the fine particle described above, thereby improving the production yield of spherical natural graphite. Furthermore, in the above case, the present invention is economical because it can save time and cost in manufacturing the anode material.

[0046] Below, the manufacturing method of the above-described negative electrode material is described in detail.

[0047] A method for manufacturing a negative electrode material according to one embodiment of the present invention may include the steps of: spheroidizing natural graphite; classifying the spheroidized natural graphite to obtain first spheroidized natural graphite having a center particle size (D50) of a target particle size and second spheroidized natural graphite having a center particle size (D50) smaller than the target particle size; mixing the second spheroidized natural graphite with pitch to obtain a mixture; heat-treating the mixture to obtain composite graphite particles; and mixing the composite graphite particles with the first spheroidized natural graphite.

[0048] First, according to the method for manufacturing a cathode material according to one embodiment of the present invention, natural graphite raw material can be spheroidized. Here, the spheroidization process may refer to a process for making natural graphite have a shape close to a spherical shape.

[0049] Thereafter, the spheroidized natural graphite is classified to obtain first spheroidized natural graphite having a center particle size (D50) of the target particle size and second spheroidized natural graphite having a center particle size (D50) smaller than the target particle size.

[0050] As described above, the target particle size refers to the central particle size targeted in the classification step. For example, this target particle size may be 15 μm or more and 18 μm or less, and a particle size smaller than the target particle size may be 6 μm or more and 13 μm or less. Since this is the same as described above with respect to the negative electrode material of the present invention, a detailed description thereof will be omitted.

[0051] In addition, the above classification can be performed using a classifier that separates particle sizes by using the principle that the distance traveled by the air jet changes depending on the weight of the powder. A non-limiting example of such a classifier may be an Elbow Jet Air Classifier.

[0052] The above Elbow Jet Air Classifier is a classifier that separates particle sizes by using the principle that the flying distance varies depending on the weight in a zone defined by a Classification Edge by blowing powder with an air jet. At this time, the spherical natural graphite can be classified into three types of zones: F (fine), M (middle), and G (giant), and at this time, the second spherical natural graphite can be the spherical natural graphite captured in the F zone.

[0053] In addition, the above classification can be performed using a classifier that classifies particle sizes by rotation of a rotor based on a balance between the centrifugal force of the rotor and the centrifugal force of the air flow. As a non-limiting example, there may be an ATP air classifier.

[0054] In this way, after producing the first spherical natural graphite and the second spherical natural graphite, the second spherical natural graphite can be mixed with pitch to produce a mixture, and the mixture can be heat-treated to produce composite graphite particles.

[0055] At this time, the center particle size (D50) of the composite graphite particles may be 8 ㎛ or more and 14 ㎛ or less.

[0056] Additionally, although not necessarily required, the present invention may sieve or classify the composite graphite particles described above, and both may be performed.

[0057] After manufacturing the composite graphite particles, the manufactured composite graphite particles can be mixed with the first spherical natural graphite.

[0058] At this time, as described above, the composite graphite particles may be included in an amount of 15 wt% or more and 30 wt% or less based on the total weight of the negative electrode material.

[0059] According to the above-described method for manufacturing a cathode material, the present invention can utilize spheroidized natural graphite fine powder inevitably generated during the classification step as a cathode material, thereby improving the production yield of spheroidized natural graphite.

[0060] In addition, since the above-described manufacturing method manufactures a negative electrode material by applying pitch to the spherical natural graphite powder and performing heat treatment, it is possible to produce a negative electrode material with excellent performance even without additionally crushing or spherizing the spherical natural graphite powder.

[0061] (Example)

[0062] (1) Manufacturing of cathode material

[0063] First, a natural graphite raw material having a center particle size of 18㎛ was prepared. Thereafter, the natural graphite raw material was spheroidized using an NHS-3 type. The linear speed at this time was 60 m / s, and the spheroidization time was 10 minutes. Thereafter, the raw material was classified using a classifier shown in Table 1. As a result, first spheroidized natural graphite having a center particle size of 15.40㎛, which is the target particle size, and second spheroidized natural graphite, which was inevitably obtained during the classification process, were obtained, inventive samples 1 and 2. In addition, the particle size distributions of the inventive samples 1 and 2 are shown in Table 1 below, along with the particle size distribution of the reference sample. In this case, the reference sample is a commercial natural graphite anode material having a center particle size of 11.04㎛. In addition, this is shown graphically in Fig. 1. In Table 1 below, span can be derived by the following equation, and in the equation below, D90, D50, and D10 mean particle sizes corresponding to 90%, 50%, and 10% of the volume accumulation of the particle size distribution, respectively.

[0064] Span = (D90-D10) / D50

[0065] Classification particle size (㎛) classifier D10 D50 D90 Span invention sample 13.458.1714.641.37 Elbow Jet Air Classifier invention sample 23.236.3710.831.1950 ATP air classifier standard sample 7.7511.0415.810.73-

[0066] The classification yield (%) of the above invention sample 1 was 35.1%. This classification yield of invention sample 1 represents the weight ratio of invention sample 1 obtained after classification based on the total weight of spheroidized natural graphite fed into the classifier. Next, the manufactured invention sample 1 was mixed with pitch having the weight % shown in Table 2 with respect to the total weight of invention sample 1 to prepare a mixture. At this time, invention examples 1 and 2 in Table 2 below represent cases where the pitch content was 20 wt% and 30 wt% with respect to the total weight of invention sample 1, respectively. Thereafter, the mixture was heat-treated and classified as shown in Table 2. At this time, the particle size distributions of the composite graphite particles that went through classification steps 1 to 3 of Table 2 are respectively shown in Table 2. In addition, FIGS. 3 and 4 show this as a graph. Specifically, in Invention Examples 1 and 2, the composite graphite particles that were heat-treated after pitch injection were sieved through a 325 mesh screen (Step 1), classified with an ATP air classifier from Hosokawa Micron (Step 2), and then sieved again through a 500 mesh screen (Step 3). The yield (%) of each step in Table 2 above represents the weight ratio of the composite graphite particles obtained after the corresponding step based on the total weight of the raw material injected into the corresponding step. In addition, the final classification yield represents the weight ratio of the composite graphite particles manufactured through Steps 1 to 3 with respect to the total weight of the natural graphite raw material injected before the spheroidization step. The final fine powder utilization rate is, in consideration of the weight ratio of the pitch injected during the manufacturing process, a value obtained by multiplying the final classification yield by 0.8 in the case of Invention Example 1, and a value obtained by multiplying the final classification yield by 0.7 in the case of Invention Example 2.

[0067] Classification Note Pitch content (weight %) Yield (%) Particle size (㎛) Final classification yield (%) Final fine powder utilization rate (%) D10 D50 D90 Span Invention example 1st stage 1325mesh 208 5.15.39 10.21 18.11.24 19.0 15. Step 2 2325mesh-ATP4 7 0.07.12 11.7 120.7 1.16 Step 3 325mesh-ATP4-500mesh 9 1.07.01 11.38 18.13 0.98 Invention example 2nd stage 1325mesh3073.86.4212.0223.441.4211.27.84step2325mesh-ATP475.58.0913.4927.11.41step3325mesh-ATP4-500mesh57.37.8212.4819.870.97

[0068] As described above, after manufacturing the composite graphite particles through steps 1 to 3, they were mixed with the first spherical natural graphite obtained through classification immediately after spheroidization. At this time, the weight ratio of the mixed composite graphite particles corresponded to 23.4 wt% and 15.3 wt%, respectively, in Invention Examples 1 and 2 with respect to the total weight of the negative electrode material. A schematic diagram showing the manufacturing method of Invention Example 1 is shown in Fig. 2.

[0069] As a result of the experiment, invention examples 1 and 2 were able to utilize the spherical natural graphite fine powder inevitably generated during the classification step as a cathode material.

[0070] Specifically, in the case of invention example 1, 15.2 wt% of spheroidized natural graphite fine powder could be utilized as a negative electrode material based on the total weight of spheroidized natural graphite introduced in the classification step after spheroidization, and in the case of invention example 2, 7.84 wt% of spheroidized natural graphite fine powder could be utilized as a negative electrode material.

[0071] As described above, when using the present invention, the production yield of spheroidized natural graphite can be improved by manufacturing a negative electrode material using spheroidized natural graphite powder.

[0072] (2) Manufacturing of cathode

[0073] A slurry of the negative electrode material was prepared by mixing 96.1 wt% of the negative electrode material of Invention Examples 1 and 2 manufactured according to the above-described procedure, 2.9 wt% of a binder including carboxymethyl cellulose and styrene butadiene rubber, and 1 wt% of a Super P conductive material in a distilled water solvent.

[0074] The above-mentioned negative electrode slurry was applied to a copper (Cu) current collector, dried at 100°C for 10 minutes, and pressed using a roll press. Thereafter, the negative electrode was manufactured by vacuum drying in a 100°C vacuum oven for 12 hours. After vacuum drying, the electrode density of the negative electrode was set to 1.5 to 1.7 g / cc.

[0075] (3) Electrochemical evaluation

[0076] To evaluate the electrochemical characteristics, a lithium secondary battery was manufactured. Specifically, a half coin cell of the 2032 coin cell type was manufactured according to a conventional manufacturing method using an anode manufactured by the above method, a counter electrode of lithium metal (Li-metal), and an electrolyte solution containing 1 mol of LiPF6 solution dissolved in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7. Thereafter, the electrochemical characteristics of Invention Examples 1 and 2 were measured and are shown in Table 3 below.

[0077] In addition, the electrochemical characteristics of a lithium secondary battery manufactured according to the same procedure as Invention Examples 1 and 2, except that a negative electrode material consisting only of the reference sample of Table 1 was used, were measured together and are shown in Table 3.

[0078] Spherical natural graphite of the first category (weight%) Composite graphite particles (weight%) Specific surface area (m 2 / g)Initial efficiency (%)Capacity (mAh)Cycle retention (%, 1C@100th)Invention example 176.623.45.493348.297Invention example 284.715.34.992354.196Reference sample--8.191360.094

[0079] Invention examples 1 and 2 were able to provide a negative electrode material having excellent cycle characteristics by partially including composite graphite particles including second spherical natural graphite and amorphous carbon.

[0080] This is because the amorphous carbon contained in the composite graphite particles can suppress the volume expansion of the negative electrode material that occurs during charging and discharging.

[0081] In addition, since the amorphous carbon can improve the charge / discharge speed of lithium, invention examples 1 and 2 can provide a negative electrode material that is particularly advantageous for high-speed charge / discharge applications.

[0082] Lastly, since the negative electrode materials of the above invention examples 1 and 2 were manufactured by mixing first spherical natural graphite and composite graphite particles having different particle sizes, an excellent electrode density can also be secured.

[0083] On the other hand, in the battery manufactured using only the reference sample, as the specific surface area of ​​the negative electrode material increased, an excessive amount of SEI (Solid Electrolyte Interphase) was formed, and as a result, the cycle characteristics and efficiency of the negative electrode material were relatively lowered compared to the batteries of Invention Examples 1 and 2.

Claims

1. Contains first spherical natural graphite and composite graphite particles, The above composite graphite particles include second spherical natural graphite and amorphous carbon, A negative electrode material in which the center particle size (D50) of the first spherical natural graphite has a target particle size, and the center particle size (D50) of the second spherical natural graphite has a particle size smaller than the target particle size.

2. In paragraph 1, The above target particle size is a cathode material having a particle size of 15㎛ or more and 18㎛ or less.

3. In paragraph 1, A cathode material having a particle size smaller than the above target particle size of 6㎛ or more and 13㎛ or less.

4. In paragraph 1, A negative electrode material having a center particle size (D50) of the above composite graphite particles of 8㎛ or more and 14㎛ or less.

5. In paragraph 1, A negative electrode material in which the above composite graphite particles are included in an amount of 15% by weight or more and 30% by weight or less based on the total weight of the negative electrode material.

6. In paragraph 1, The amorphous carbon is a negative electrode material comprised of 10 to 30 wt% of the total weight of the second spherical natural graphite.

7. Step of spheroidizing natural graphite; A step of classifying the above natural graphite to obtain first spherical natural graphite having a center particle size (D50) of the target particle size and second spherical natural graphite having a center particle size (D50) smaller than the target particle size; A step of mixing the second spherical natural graphite with pitch to obtain a mixture; A step of heat-treating the above mixture to obtain composite graphite particles; and A method for manufacturing a negative electrode material, comprising a step of mixing the above composite graphite particles with the first spherical natural graphite.

8. In paragraph 7, A method for manufacturing a cathode material having a target particle size of 15㎛ or more and 18㎛ or less.

9. In paragraph 7, A method for manufacturing a cathode material having a particle size smaller than the above target particle size of 6㎛ or more and 13㎛ or less.

10. In paragraph 7, The above classification is a method for manufacturing a cathode material using a classifier that separates particle sizes by using the principle that the distance traveled by the powder changes depending on the weight by blowing the powder with an air jet.

11. In paragraph 10, The above classification is a method for manufacturing a cathode material using an Elbow Jet Air Classifier.

12. In paragraph 7, The above classification is a method for manufacturing a cathode material using a classifier that classifies particle sizes by classifying rotation based on a balance between the centrifugal force of a rotor and the centrifugal force of airflow.

13. In paragraph 12, The above classification is a method for manufacturing a cathode material using a 50 ATP air classifier.

14. In paragraph 7, A method for manufacturing a negative electrode material, wherein the center particle size (D50) of the above composite graphite particles is 8㎛ or more and 14㎛ or less.

15. In paragraph 7, A method for manufacturing a negative electrode material, wherein the above composite graphite particles are included in an amount of 15% by weight or more and 30% by weight or less based on the total weight of the negative electrode material.

16. In paragraph 7, A method for manufacturing a negative electrode material, wherein the pitch is mixed in an amount of 10 to 30 wt% based on the total weight of the second spherical natural graphite.

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