Method for manufacturing negative electrode material of secondary battery and negative electrode material manufactured thereby

Abstract

This method for manufacturing a negative electrode material comprises: a first step for providing a mixed powder in which a silicon powder and a graphite powder are mixed; and a second step for applying thermal shock to the mixed powder to produce a silicon carbide powder from the mixed powder, wherein some of the silicon powder and the graphite powder remain when the silicon carbide is produced in the second step, and the range of at least one of a temperature condition or a time condition for the thermal shock may be set on the basis of the production ratio of the silicon carbide powder produced from the mixed powder.

Description

Method for manufacturing a negative electrode material for a secondary battery and a negative electrode material manufactured thereby

[0001] The present invention relates to a method for manufacturing a negative electrode material for a secondary battery and a negative electrode material manufactured thereby, and more specifically, to a method for manufacturing a negative electrode material for a secondary battery with improved secondary battery life and charging speed performance and a negative electrode material manufactured thereby.

[0002] Generally, lithium-ion rechargeable batteries are widely used as a primary energy source for portable electronic devices, hybrid vehicles, and the like due to their characteristics such as high capacity, high energy density, and excellent thermal stability.

[0003] Currently, the most widely used commercial cathode material is carbon. Carbon materials such as graphite and graphite have a layered structure that allows lithium ions to move smoothly between layers, resulting in a long cycle life and high stability.

[0004] However, while carbon-based cathode materials can reach a Coulomb efficiency of 99.9% in a short period of time, they have the disadvantage of low capacitance. To overcome the aforementioned disadvantages of carbon, silicon-based cathode materials that exhibit high capacitance are gaining attention.

[0005] The physical structure of the silicon in the above silicon-based anode material may collapse as the secondary battery undergoes repeated charging and discharging. Therefore, secondary batteries using the above silicon-based anode material have low lifespan and stability.

[0006] The present invention provides a method for manufacturing a negative electrode material for a secondary battery capable of increasing the lifespan and stability of the secondary battery, and a negative electrode material manufactured thereby.

[0007] A method for manufacturing a cathode material according to the present invention comprises a first step of providing a mixed powder in which silicon powder and graphite powder are mixed, and a second step of applying a thermal shock to the mixed powder so that silicon carbide powder is produced through the mixed powder, wherein the silicon powder and the graphite powder remain when the silicon carbide is produced in the second step, and at least one of the temperature condition and time condition for the thermal shock may be set to a range based on the production ratio of the silicon carbide powder produced in the mixed powder.

[0008] According to one embodiment of the present invention, as the production ratio of the silicon carbide powder increases, the temperature condition for the thermal shock may increase, and the time condition for the thermal shock may increase.

[0009] According to one embodiment of the present invention, the production ratio of the silicon carbide powder is 1 to 20 weight%, and the temperature condition for the thermal shock may be 1400°C to 1600°C, at which the silicon powder can be melted or micronized.

[0010] According to one embodiment of the present invention, the production ratio of the silicon carbide powder is 1 to 20 weight%, and the time condition for the thermal shock may be 10 to 180 seconds so that the thermal shock can be sufficiently transmitted to the silicon powder.

[0011] According to one embodiment of the present invention, the ratio of the silicon powder and the graphite powder in the mixed powder may be set within a range based on the production ratio of the silicon carbide powder produced in the mixed powder.

[0012] According to one embodiment of the present invention, as the production ratio of the silicon carbide powder increases, the ratio of the silicon powder in the mixed powder may decrease, and the ratio of the graphite powder may increase.

[0013] According to one embodiment of the present invention, the production ratio of the silicon carbide powder may be 1 to 20 weight%, and the ratio of the silicon powder in the mixed powder may be 50 weight% to 95 weight%.

[0014] According to one embodiment of the present invention, the sizes of the silicon powder and the graphite powder in the mixed powder may be set within a range based on the production ratio of the silicon carbide powder produced in the mixed powder.

[0015] According to one embodiment of the present invention, the higher the production ratio of the silicon carbide powder, the smaller the size of the silicon powder and the graphite powder may be.

[0016] According to one embodiment of the present invention, the production ratio of the silicon carbide powder may be 1 to 20 weight%, the size of the silicon powder may be 600 nm to 5000 nm, and the size of the graphite powder may be 1000 nm to 20000 nm.

[0017] According to one embodiment of the present invention, the thermal shock may be achieved by applying microwaves.

[0018] According to one embodiment of the present invention, the thermal shock may be applied by a rotary kiln type microwave device having a rotary kiln shape and generating microwaves to irradiate into the interior.

[0019] According to one embodiment of the present invention, in the second step, the carbon powder is heated by the thermal shock, and the heated carbon powder transfers heat to the silicon powder so that the silicon powder is melted or atomized, and the melted or atomized silicon powder reacts with the carbon powder to produce the silicon carbide powder.

[0020] According to one embodiment of the present invention, the first and second steps may be performed in a nitrogen atmosphere to prevent oxidation of the silicon powder.

[0021] A method for manufacturing a cathode material according to the present invention comprises a first step of providing a mixed powder in which silicon powder and graphite powder are mixed, and a second step of applying a thermal shock to the mixed powder so that silicon carbide powder is produced through the mixed powder, wherein in the second step, the silicon powder and the graphite powder remain when the silicon carbide is produced, and the ratio of the silicon powder and the graphite powder in the mixed powder may be set to a range based on the production ratio of the silicon carbide powder produced in the mixed powder.

[0022] According to one embodiment of the present invention, as the production ratio of the silicon carbide powder increases, the ratio of the silicon powder in the mixed powder may decrease, and the ratio of the graphite powder may increase.

[0023] According to one embodiment of the present invention, the production ratio of the silicon carbide powder may be 1 to 20 weight%, and the ratio of the silicon powder in the mixed powder may be 50 weight% to 95 weight%.

[0024] According to the present invention, the method for manufacturing a cathode material comprises a first step of providing a mixed powder in which silicon powder and graphite powder are mixed, and a second step of applying a thermal shock to the mixed powder so that silicon carbide powder is produced through the mixed powder, wherein the silicon powder and the graphite powder remain when the silicon carbide is produced in the second step, and the size of the silicon powder and the graphite powder in the mixed powder may be set within a range based on the production ratio of the silicon carbide powder produced in the mixed powder.

[0025] According to one embodiment of the present invention, as the production ratio of the silicon carbide powder increases, the size of the silicon powder and the graphite powder may decrease.

[0026] According to one embodiment of the present invention, the production ratio of the silicon carbide powder may be 1 to 20 weight%, the size of the silicon powder may be 600 nm to 5000 nm, and the size of the graphite powder may be 1000 nm to 20000 nm.

[0027] The cathode material according to the present invention can be manufactured by any one of the methods for manufacturing the cathode material.

[0028] According to the present invention, a negative electrode material composed of silicon carbide powder, residual silicon powder, and residual graphite powder can be manufactured by applying thermal shock to the mixed powder to produce silicon carbide powder. Accordingly, a negative electrode material capable of increasing the lifespan and stability of a secondary battery can be manufactured.

[0029] FIG. 1 is a flowchart illustrating a method for manufacturing a cathode material according to one embodiment of the present invention.

[0030] The present invention will be described in detail below with reference to the attached drawings. Since the present invention is susceptible to various modifications and may take various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed forms, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention. Similar reference numerals have been used for similar components in the description of each drawing. In the attached drawings, the dimensions of the structures are shown enlarged compared to the actual dimensions for clarity of the present invention.

[0031] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component.

[0032] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0033] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0034]

[0035] FIG. 1 is a flowchart illustrating a method for manufacturing a cathode material according to one embodiment of the present invention.

[0036] Referring to FIG. 1, the method for manufacturing the cathode material may include a first step (S110) in which a mixed powder comprising silicon powder and graphite powder is provided, and a second step (S230) in which a thermal shock is applied to the mixed powder so as to produce silicon carbide powder through the mixed powder.

[0037] In the first step above, the silicon powder and the graphite powder may be mixed in a separate space to form the mixed powder and then provided. Alternatively, in the first step above, the silicon powder and the graphite powder may be provided separately and then mixed to form the mixed powder.

[0038] In the second step above, when the silicon carbide is produced, the silicon powder and the graphite powder are not all reacted, and the silicon powder and the graphite powder may remain.

[0039] The above thermal shock can be achieved by applying microwaves.

[0040] The above thermal shock can be applied by a rotary kiln type microwave device that has a rotary kiln shape and generates microwaves to irradiate the interior.

[0041] For example, the rotary kiln-type microwave device may include a housing that is elongated in the horizontal direction and has an inlet for introducing a drying object and an outlet for discharging a dried object; microwave generating units spaced apart from each other along the outer circumference of the housing and irradiating microwaves into the interior of the housing to heat the object; and a rotary driving unit provided to support the housing and rotate the housing equipped with the microwave generating units.

[0042] As another example, the rotary kiln-type microwave device may include a dielectric tube formed long in a horizontal direction and having a first end into which a target object is introduced and a second end into which a heated target object is discharged; a housing provided to surround the dielectric tube between the first end and the second end; microwave generating units provided along the outer circumference of the housing and heating the target object by irradiating microwaves to pass through the dielectric tube through openings formed in the housing; a rotating tube that surrounds and fixes the dielectric tube exposed by the housing and is provided to be rotatable with respect to the housing together with the dielectric tube; and a rotary driving unit that supports the rotating tube and rotates the dielectric tube and the rotating tube so that the microwaves uniformly heat the target object in the dielectric tube.

[0043] In the second step above, when a thermal shock is applied to the mixed powder, the carbon powder is heated by the thermal shock, and the heated carbon powder transfers heat to the silicon powder. When the silicon powder is instantaneously heated above the melting temperature by the heat, the silicon powder is melted or atomized by the heat, and the melted or atomized silicon powder can react with the carbon powder to produce the silicon carbide powder.

[0044] The first step and the second step (S110 and S120) above may be performed in a nitrogen atmosphere to prevent oxidation of the silicon powder.

[0045] At least one of the temperature and time conditions for the above thermal shock may be set to a range based on the production ratio of the silicon carbide powder produced in the mixed powder.

[0046] Specifically, as the production ratio of the silicon carbide powder increases, the temperature condition for the thermal shock increases, and the time condition for the thermal shock can be extended.

[0047] The production ratio of the silicon carbide powder above may be 1 to 20 weight%, and preferably 1 to 5 weight%.

[0048] If the production ratio of the silicon carbide powder is less than 1 weight%, the proportion of the silicon carbide powder is low, making it difficult to prevent damage to silicon that may occur during the charging and discharging process of the secondary battery. Consequently, the lifespan of the secondary battery may be reduced.

[0049] If the production ratio of the silicon carbide powder exceeds 20 weight percent, the proportion of the silicon carbide powder is large, and the capacity of the secondary battery may be reduced.

[0050] For example, when the production ratio of the silicon carbide powder is 1 to 20 weight%, the temperature condition for the thermal shock may be 1400°C to 1600°C, at which the silicon powder can be melted or micronized.

[0051] If the temperature condition for the above thermal shock is less than 1400 ℃, the low thermal shock temperature makes it difficult for the silicon powder to melt or be micronized, or even if the silicon powder is melted or micronized, the silicon carbide powder may be produced at a rate of less than 1 weight percent.

[0052] If the temperature condition for the above thermal shock exceeds 1600 ℃, the thermal shock temperature is high, so the silicon carbide powder is produced at a rate exceeding 20 weight%, or the container containing the mixed powder may be damaged or broken by the thermal shock.

[0053] Accordingly, as the production ratio of the silicon carbide powder increases from 1 weight% to 20 weight%, the temperature condition for the thermal shock can also be increased from 1400 ℃ to 1600 ℃.

[0054]

[0055] As another example, when the production ratio of the silicon carbide powder is 1 to 20 weight%, the time condition for the thermal shock may be 10 to 180 seconds, preferably 30 to 90 seconds, so that the thermal shock can be sufficiently transferred to the silicon powder.

[0056] If the time condition for the above thermal shock is less than 10 seconds, the thermal shock time is short, making it difficult for the silicon powder to melt or be micronized, or even if the silicon powder is melted or micronized, the silicon carbide powder may be produced at a rate of less than 1 weight percent.

[0057] If the time condition for the above thermal shock exceeds 180 seconds, the thermal shock time is long, so the silicon carbide powder may be produced at a rate exceeding 20% ​​by weight, or the container containing the mixed powder may be damaged or broken by the thermal shock.

[0058] Accordingly, as the production ratio of the silicon carbide powder increases from 1 weight% to 20 weight%, the time condition for the thermal shock can also be increased from 10 seconds to 180 seconds.

[0059] Meanwhile, conversely to the above, the production ratio of the silicon carbide powder generated from the mixed powder can be set according to at least one range of the temperature and time conditions for the thermal shock.

[0060] Specifically, the production rate of the silicon carbide powder may increase as the temperature condition for the thermal shock increases or as the time condition for the thermal shock increases.

[0061]

[0062] In addition, the ratio of the silicon powder and the graphite powder in the above mixed powder can be set within a range based on the production ratio of the silicon carbide powder produced in the above mixed powder.

[0063] Specifically, as the production ratio of the silicon carbide powder increases, the proportion of the silicon powder in the mixed powder decreases, and the proportion of the graphite powder increases.

[0064] The production ratio of the silicon carbide powder above may be 1 to 20 weight%, and preferably 1 to 5 weight%.

[0065] If the production ratio of the silicon carbide powder is less than 1 weight percent, the proportion of the silicon carbide powder is low, making it difficult to prevent damage to silicon that may occur during the charging and discharging process of the secondary battery. Consequently, the lifespan of the secondary battery may be reduced.

[0066] If the production ratio of the silicon carbide powder exceeds 20 weight percent, the proportion of the silicon carbide powder is large, and the capacity of the secondary battery may be reduced.

[0067] For example, when the production ratio of the silicon carbide powder is 1 to 20 weight%, the ratio of the silicon powder in the mixed powder is 50 weight% to 95 weight%, and preferably 50 weight% to 80 weight%.

[0068] When the proportion of the silicon powder in the above mixed powder is less than 50% by weight, the proportion of the graphite powder exceeds 50% by weight, so the proportion of the graphite powder is high and the silicon carbide powder can be produced at a ratio exceeding 20% ​​by weight.

[0069] When the proportion of the silicon powder in the above mixed powder exceeds 95 weight%, the proportion of the graphite powder is less than 5 weight%, so the proportion of the graphite powder is low and the silicon carbide powder can be produced at a ratio of less than 1 weight%.

[0070] Accordingly, as the production ratio of the silicon carbide powder increases from 1 weight% to 20 weight%, the ratio of the silicon powder in the mixed powder decreases from 95 weight% to 50 weight%, and the ratio of the graphite powder can increase from 5 weight% to 50 weight%.

[0071] Meanwhile, conversely to the above, the production ratio of the silicon carbide powder produced in the mixed powder can be set according to the ratio range of the silicon powder and the graphite powder in the mixed powder.

[0072] Specifically, the lower the proportion of the silicon powder and the higher the proportion of the graphite powder in the above mixed powder, the higher the production ratio of the silicon carbide powder may be.

[0073]

[0074] In addition, the sizes of the silicon powder and the graphite powder in the above mixed powder can be set within a range based on the production ratio of the silicon carbide powder produced in the above mixed powder.

[0075] Specifically, the higher the production ratio of the silicon carbide powder, the smaller the size of the silicon powder and the graphite powder may be.

[0076] The production ratio of the silicon carbide powder above may be 1 to 20 weight%, and preferably 1 to 5 weight%.

[0077] If the production ratio of the silicon carbide powder is less than 1 weight percent, the proportion of the silicon carbide powder is low, making it difficult to prevent damage to silicon that may occur during the charging and discharging process of the secondary battery. Consequently, the lifespan of the secondary battery may be reduced.

[0078] If the production ratio of the silicon carbide powder exceeds 20 weight percent, the proportion of the silicon carbide powder is large, and the capacity of the secondary battery may be reduced.

[0079] For example, when the production ratio of the silicon carbide powder is 1 to 20 weight%, the size of the silicon powder may be 600 nm to 5000 nm, or the size of the graphite powder may be 1000 nm to 20000 nm.

[0080] If the size of the silicon powder is less than 600 nm or the size of the graphite powder is less than 1000 nm, the size of the silicon powder may be smaller, so the size of the silicon powder that is melted or micronized may be even smaller, and the size of the graphite powder may also be smaller. Accordingly, the silicon powder that is melted or micronized may react significantly with the carbon powder, and the silicon carbide powder may be produced at a rate exceeding 20% ​​by weight.

[0081] When the size of the silicon powder exceeds 5000 nm and the size of the graphite powder exceeds 20000 nm, since the size of the silicon powder is large, the size of the silicon powder that is melted or micronized may also be large, and the size of the graphite powder may also be large. Accordingly, the silicon powder that is melted or micronized reacts less with the carbon powder, so that the silicon carbide powder may be produced at a rate of less than 1 weight percent.

[0082] Accordingly, as the production ratio of the silicon carbide powder increases from 1 weight% to 20 weight%, the size of the silicon powder may decrease from 600 nm to 5000 nm, or the size of the graphite powder may decrease from 1000 nm to 20000 nm.

[0083] Meanwhile, conversely to the above, the production ratio of the silicon carbide powder generated in the mixed powder can be set according to the size range of the silicon powder and the graphite powder in the mixed powder.

[0084] Specifically, the smaller the size of the silicon powder and the graphite powder, the higher the production ratio of the silicon carbide powder can be.

[0085]

[0086] In addition, the size of the silicon carbide powder can be determined by the size of the graphite powder. That is, the larger the size of the graphite powder, the larger the size of the silicon carbide powder can be. Therefore, the size of the silicon carbide powder can be controlled by adjusting the size of the graphite powder.

[0087]

[0088] After forming the cathode material composed of the silicon carbide powder, the residual silicon powder, and the residual graphite powder through the above first step and the above second step, the cathode material can be cooled, assembled into a spheroid, and then pitch coated.

[0089] The above assembly spheroidization can be achieved by rotating the cathode material at high speed in an assembly spheroidization device.

[0090] The assembly spheroidizing device above operates with a rotational force of 3,000 rpm to 8,000 rpm, preferably 4,500 rpm to 6,000 rpm, and the operating time is 100 seconds to 600 seconds, preferably 150 seconds to 400 seconds. If the rotational force and operating time are outside the range, the assembly spheroidizing efficiency of the cathode material decreases.

[0091] The above pitch coating may be achieved by coating the surface of the cathode material using petroleum or coal-based pitch, and then carbonizing the pitch components coated on the surface through heat treatment at a temperature of 800 to 2000°C, but is not limited thereto.

[0092]

[0093] The cathode material can be manufactured by the above method for manufacturing the cathode material.

[0094] A cathode material composed of silicon carbide powder, residual silicon powder, and residual graphite powder can be manufactured by the method for manufacturing a cathode material according to the present invention. By using the cathode material, the lifespan and stability of a secondary battery can be improved.

[0095] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

1. A first step in which a mixed powder comprising silicon powder and graphite powder is provided; and A second step in which a thermal shock is applied to the mixed powder so as to generate silicon carbide powder through the mixed powder; comprising In the second step above, when the silicon carbide is produced, the silicon powder and the graphite powder remain, At least one of the temperature and time conditions for the above thermal shock is, A method for manufacturing a cathode material characterized by setting a range based on the production ratio of the silicon carbide powder produced from the above-mentioned mixed powder.

2. In Paragraph 1, A method for manufacturing a cathode material characterized in that as the production ratio of the silicon carbide powder increases, the temperature condition for the thermal shock increases and the time condition for the thermal shock increases.

3. In Paragraph 2, The production ratio of the above silicon carbide powder is 1 to 20 weight%, and A method for manufacturing a cathode material, characterized in that the temperature condition for the above thermal shock is 1400 ℃ to 1600 ℃, at which the silicon powder can be melted or micronized.

4. In Paragraph 2, The production ratio of the above silicon carbide powder is 1 to 20 weight%, and A method for manufacturing a cathode material, characterized in that the time condition for the above thermal shock is 10 to 180 seconds so that the thermal shock can be sufficiently transferred to the silicon powder.

5. In Paragraph 1, The ratio of the silicon powder to the graphite powder in the above mixed powder is, A method for manufacturing a cathode material characterized by setting a range based on the production ratio of the silicon carbide powder produced from the above-mentioned mixed powder.

6. In Paragraph 5, A method for manufacturing a cathode material characterized in that as the production ratio of the silicon carbide powder increases, the ratio of the silicon powder in the mixed powder decreases and the ratio of the graphite powder increases.

7. In Paragraph 6, The production ratio of the above silicon carbide powder is 1 to 20 weight%, and A method for manufacturing a cathode material characterized in that the ratio of the silicon powder in the above-mentioned mixed powder is 50% to 95% by weight.

8. In Paragraph 1, The sizes of the silicon powder and the graphite powder in the above mixed powder are, A method for manufacturing a cathode material characterized by setting a range based on the production ratio of the silicon carbide powder produced from the above-mentioned mixed powder.

9. In Paragraph 8, A method for manufacturing a cathode material characterized in that the higher the production ratio of the silicon carbide powder, the smaller the size of the silicon powder and the graphite powder.

10. In Paragraph 9, The production ratio of the above silicon carbide powder is 1 to 20 weight%, and A method for manufacturing a cathode material characterized in that the size of the silicon powder is 600 nm to 5000 nm and the size of the graphite powder is 1000 nm to 20000 nm.

11. In Paragraph 1, A method for manufacturing a cathode material characterized by the above thermal shock being performed by applying microwaves.

12. In Paragraph 1, A method for manufacturing a metallurgical material, characterized in that the above thermal shock is applied by a rotary kiln-type microwave device having a rotary kiln shape and generating microwaves to irradiate the interior.

13. In Paragraph 1, A method for manufacturing a cathode material, characterized in that, in the second step above, the carbon powder is heated by the thermal shock, the heated carbon powder transfers heat to the silicon powder so that the silicon powder is melted or atomized, and the melted or atomized silicon powder reacts with the carbon powder to produce the silicon carbide powder.

14. In Paragraph 1, The above first step and the above second step are, A method for manufacturing a cathode material characterized by being carried out in a nitrogen atmosphere to prevent oxidation of the above silicon powder.

15. A first step of providing a mixed powder in which silicon powder and graphite powder are mixed; and A second step in which a thermal shock is applied to the mixed powder so as to generate silicon carbide powder through the mixed powder; comprising In the second step above, when the silicon carbide is produced, the silicon powder and the graphite powder remain, The ratio of the silicon powder to the graphite powder in the above mixed powder is, A method for manufacturing a cathode material characterized by setting a range based on the production ratio of the silicon carbide powder produced from the above-mentioned mixed powder.

16. In Paragraph 15, A method for manufacturing a cathode material characterized in that as the production ratio of the silicon carbide powder increases, the ratio of the silicon powder in the mixed powder decreases and the ratio of the graphite powder increases.

17. In Paragraph 16, The production ratio of the above silicon carbide powder is 1 to 20 weight%, and A method for manufacturing a cathode material characterized in that the ratio of the silicon powder in the above-mentioned mixed powder is 50% to 95% by weight.

18. A first step in which a mixed powder comprising silicon powder and graphite powder is provided; and A second step in which a thermal shock is applied to the mixed powder so as to generate silicon carbide powder through the mixed powder; comprising In the second step above, when the silicon carbide is produced, the silicon powder and the graphite powder remain, The sizes of the silicon powder and the graphite powder in the above mixed powder are, A method for manufacturing a cathode material characterized by setting a range based on the production ratio of the silicon carbide powder produced from the above-mentioned mixed powder.

19. In Paragraph 18, A method for manufacturing a cathode material characterized in that the higher the production ratio of the silicon carbide powder, the smaller the size of the silicon powder and the graphite powder.

20. In Paragraph 19, The production ratio of the above silicon carbide powder is 1 to 20 weight%, and A method for manufacturing a cathode material characterized in that the size of the silicon powder is 600 nm to 5000 nm and the size of the graphite powder is 1000 nm to 20000 nm.

21. A cathode material characterized by being manufactured by the method of any one of claims 1 to 20.

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