KR20210025331A - Method for manufacturing york-shell structure - Google Patents

Abstract

The present application relates to a method of manufacturing a yolk-shell structure, comprising the steps of: forming a graphene layer on the surface of silicon particles; and inducing vapor-phase etching of the outer surface of the silicon particles present in the graphene. A lithium secondary battery including the yolk-shell structure may have improved stability.

Description

Method for manufacturing a yoke-shell structure {METHOD FOR MANUFACTURING YORK-SHELL STRUCTURE}

The present application relates to a method of manufacturing a yoke-shell structure.

With the development of the semiconductor industry, the use of small electronic devices such as notebook computers, mobile phones, and portable electronic devices is increasing in the general society. Since these small electronic devices receive energy from an energy storage device such as a lithium secondary battery, research on a high-performance energy storage device is being conducted.

A lithium secondary battery, which is a representative energy storage device, refers to a battery in which lithium ions of a positive electrode move to a negative electrode during a discharge process. Lithium ions transferred to the negative electrode can be re-used because they can be moved back to the positive electrode through the charging process, and are used in various electronic devices due to their high energy density, no memory effect, and low degree of self-discharge. I can. In order to improve the performance of a lithium secondary battery, there are changes in the anode or anode material, improvement in coating technology, improvement in packing technology, and improvement in the Li-ion capacity of the negative electrode through structure improvement. In this case, it is known that the conventional technology has already reached its limit and is not easy to improve.

In addition, conventional lithium secondary batteries use a carbon material as a negative electrode material, but secondary batteries using graphite-based carbon materials only have high energy density per unit volume and require further improvement due to slow charging and discharging speeds. A secondary battery using a carbon material has a disadvantage of low energy density per multi-level volume.

In order to overcome this problem, Si-Sn-based metal materials, porous materials, Li metals, Ti-based oxides, nitrides Li _x M _y N ₂ , and yoke-shell structures have been considered as negative electrodes of lithium secondary batteries. These materials expand upon reaction with lithium, or have various disadvantages such as lower energy density per unit volume and battery voltage, complicated process, and low yield compared to carbon materials, and thus need to be improved.

Korean Laid-Open Patent Publication No. 10-2019-0037683, which is the technology behind the present application, relates to a particle having a yoke-shell structure, a method of manufacturing the same, and a lithium secondary battery including the same. The disclosed patent discloses a yoke-shell structure particle including a carbon shell and a silicon core provided inside the carbon shell, and the surface of the silicon core is partially etched SiO ₂ , but a yoke not including _{SiO 2} -It does not disclose the shell structure.

The present application is to solve the problems of the prior art described above, and an object of the present invention to provide a method of manufacturing a yoke-shell structure.

In addition, it is an object to provide a yoke-shell structure manufactured by the above manufacturing method.

In addition, it is an object to provide a negative electrode for a lithium secondary battery including the yoke-shell structure.

However, the technical problem to be achieved by the embodiments of the present application is not limited to the technical problems as described above, and other technical problems may exist.

As a technical means for achieving the above technical problem, the first aspect of the present application, forming a graphene layer on the surface of the silicon particle; And it provides a method of manufacturing a yoke-shell structure comprising the step of vapor-phase etching the outer surface of the silicon particles present inside the graphene.

According to the exemplary embodiment of the present disclosure, the silicon particles form a core, the graphene layer forms a shell, and a void may be formed between the core and the shell, but is not limited thereto.

According to the exemplary embodiment of the present disclosure, the pores may enable volume expansion of 450% or less of the core without deformation of the shell structure, but are not limited thereto.

According to one embodiment of the present application, the outer surface of the silicon particles may be etched by a gas selected from the group consisting _{of HCl, HF, SF 6} , HBr, CF ₄ , C ₄ H _{8, and combinations thereof,} It is not limited thereto.

According to the exemplary embodiment of the present disclosure, the step of forming the graphene layer may be performed under the supply of a gas containing carbon, but is not limited thereto.

According to one embodiment of the present application, the step of forming the graphene layer may be performed by a process selected from the group consisting of tube-type CVD, LPCVD, APCVD, PECVD, ALCVD, and combinations thereof, but is limited thereto. It is not.

According to one embodiment of the present application, the gas containing carbon is CH ₄ , C ₂ H ₆ , C ₃ H ₈ , C ₄ H ₁₀ , C ₅ H ₁₂ , C ₆ H ₁₄ , C ₇ H ₁₆ , C ₂ H ₄ , C ₂ H ₂ , C ₃ H ₆ , C ₃ H ₄ , C ₄ H ₈ , C ₄ H ₆ , C ₅ H ₁₀ , C ₅ H ₈ , C ₆ H ₁₂ , C ₆ H ₁₀ , C ₇ It may include a material selected from the group consisting of H ₁₄ , C ₇ H _{12, and combinations thereof, but is not limited thereto.}

In addition, the second aspect of the present application is prepared by the first aspect of the present application, and a void exists between the graphene and the silicon particles, providing a yoke-shell structure.

In addition, a third aspect of the present application provides a negative electrode for a lithium secondary battery including a negative active material and a water-soluble polymer including a yoke-shell structure according to the second aspect of the present application.

According to the exemplary embodiment of the present disclosure, the yoke-shell structure may be coated with the water-soluble polymer, but is not limited thereto.

According to one embodiment of the present application, the negative electrode for a lithium secondary battery is a carbon-based selected from the group consisting of Super-P, Ketjen Black, Denka Black, acetylene black, carbon black, and combinations thereof. It may further include a conductive material, but is not limited thereto.

According to one embodiment of the present application, the water-soluble polymer is carboxymethyl cellulose, carboxymethyl cellulose sodium salt, carboxymethyl cellulose ammonium salt, methyl cellulose, hydroxy methyl cellulose, hydroxy propyl cellulose, ethyl cellulose, polyvinyl alcohol, polyacrylic acid, Polyacrylic acid substituted with alkali cation or ammonium ion, poly(alkylene-maleic anhydride) copolymer substituted with alkali cation or ammonium ion, poly(alkylene-maleic acid) copolymer substituted with alkali cation or ammonium ion, polyethylene It may include a material selected from the group consisting of oxide, alginic acid, sodium alginate, and combinations thereof, but is not limited thereto.

The above-described problem solving means are merely exemplary and should not be construed as limiting the present application. In addition to the above-described exemplary embodiments, additional embodiments may exist in the drawings and detailed description of the invention.

According to the above-described problem solving means of the present application, the method of manufacturing a yoke-shell structure according to the present application does not include the step of oxidizing the _{surface of the silicon (Si) particles of the core to silica (SiO 2 ).} Accordingly, the method of manufacturing a yoke-shell structure according to the present application has a simple process compared to the conventional method of manufacturing a graphene/Si yoke-shell structure, thereby saving cost.

In addition, the conventional graphene/Si yoke-shell structure was prepared by wet etching the surface-oxidized silica. However, since the method of manufacturing the yoke-shell structure according to the present application includes a gas phase etching process, the yield may be improved compared to the conventional method of manufacturing a graphene/Si yoke-shell structure using a wet etching process.

In addition, when the silicon core of the yoke-shell structure according to the present application reacts with lithium, expansion of the volume may be suppressed. Specifically, since the space in which the silicon core is to be expanded exists as a void of the yoke-shell structure, stability of a lithium secondary battery including the yoke-shell structure may be improved.

However, the effect obtainable in the present application is not limited to the above-described effects, and other effects may exist.

1 is a flow chart showing a method of manufacturing a yoke-shell structure according to an embodiment of the present application.
2 is a schematic diagram showing a method of manufacturing a yoke-shell structure according to an embodiment of the present application.
3 is a schematic diagram showing a manufacturing process of a graphene layer according to an embodiment of the present application.
4 is a diagram showing a change in a structure according to a comparative example of the present application.
5 is a diagram showing a change in a yoke-shell structure according to an embodiment of the present application.

Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art may easily implement the present application.

However, the present application may be implemented in various different forms and is not limited to the embodiments described herein. In addition, in the drawings, parts irrelevant to the description are omitted in order to clearly describe the present application, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the present specification, when a part is said to be "connected" with another part, this includes not only the case that it is "directly connected", but also the case that it is "electrically connected" with another element interposed therebetween. do.

Throughout the present specification, when a member is positioned "on", "upper", "upper", "under", "lower", and "lower" of another member, this means that a member is located on another member. This includes not only the case where they are in contact but also the case where another member exists between the two members.

In the entire specification of the present application, when a certain part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

As used herein, the terms "about", "substantially" and the like are used in or close to the numerical value when manufacturing and material tolerances specific to the stated meaning are presented, and to aid understanding of the present application. In order to avoid unreasonable use by unscrupulous infringers of the stated disclosures, either exact or absolute figures are used. In addition, throughout the specification of the present application, "step to" or "step of" does not mean "step for".

In the entire specification of the present application, the term "combination of these" included in the expression of the Makushi format refers to one or more mixtures or combinations selected from the group consisting of components described in the expression of the Makushi format, and the constituent elements It means to include one or more selected from the group consisting of.

Throughout this specification, the description of "A and/or B" means "A or B, or A and B".

Hereinafter, a method of manufacturing a yoke-shell structure of the present application will be described in detail with reference to embodiments and examples and drawings. However, the present application is not limited to these embodiments and examples and drawings.

As a technical means for achieving the above technical problem, the first aspect of the present application, forming a graphene layer on the surface of the silicon particle; And it provides a method of manufacturing a yoke-shell structure comprising the step of vapor-phase etching the outer surface of the silicon particles present inside the graphene.

The yoke-shell structure is also referred to as an egg yolk structure, and refers to a material having a structure including a core (yoke), a shell surrounding the core, and an empty space between the yoke and the shell.

As will be described later, since the negative electrode material of the lithium secondary battery may include the yoke-shell structure, the core may receive and store lithium ions released from the positive electrode of the lithium secondary battery, but is not limited thereto.

As the core, the silicon particles have a high theoretical capacity of 4200 mAh/g, a low potential difference with lithium, and a rich reserve. However, when the silicon particles react with lithium, the volume expands by 400% or more, so that the structure of the electrode is easily damaged, thereby deteriorating the stability of the lithium secondary battery.

1 is a flow chart illustrating a method of manufacturing a yoke-shell structure according to an embodiment of the present application, and FIG. 2 is a schematic diagram illustrating a method of manufacturing a yoke-shell structure according to an embodiment of the present application.

Referring to FIG. 2, the method of manufacturing a yoke-shell structure according to the present disclosure includes forming the graphene layer on the surface of the silicon particle, and etching the surface of the silicon particle to obtain the silicon particle, the pore, and It may include forming a yoke-shell structure including the graphene layer.

For the manufacture of the yoke-shell structure according to the present application, first, a graphene layer is formed on the surface of the silicon particles (S100).

According to the exemplary embodiment of the present disclosure, the silicon particles may form a core, and the graphene layer may form a shell, but is not limited thereto.

As will be described later, the silicon particles are for accommodating the lithium ions, and the graphene layer can serve as a protective layer for controlling the activity and selectivity of the silicon particles, and protecting the silicon particles from the external environment. have.

According to the exemplary embodiment of the present disclosure, the silicon particles may have a size of 30 nm to 120 nm, but are not limited thereto. For example, the size of the silicon particles is about 30 nm to about 120 nm, about 40 nm to about 120 nm, about 50 nm to about 120 nm, about 60 nm to about 120 nm, about 70 nm to about 120 nm, About 80 nm to about 120 nm, about 90 nm to about 120 nm, about 100 nm to about 120 nm, about 110 nm to about 120 nm, about 30 nm to about 110 nm, about 30 nm to about 100 nm, about 30 nm To about 90 nm, about 30 nm to about 80 nm, about 30 nm to about 70 nm, about 30 nm to about 60 nm, about 30 nm to about 50 nm, about 30 nm to about 40 nm, about 40 mn to about 110 nm, about 50 nm to about 100 nm, about 60 nm to about 90 nm, or about 70 nm to about 80 nm, but is not limited thereto.

3 is a schematic diagram showing a manufacturing process of a graphene layer according to an embodiment of the present application.

According to the exemplary embodiment of the present disclosure, the step of forming the graphene layer may be performed under the supply of a gas containing carbon, but is not limited thereto.

According to one embodiment of the present application, the step of forming the graphene layer may be performed by a process selected from the group consisting of tube-type CVD, LPCVD, APCVD, PECVD, ALCVD, and combinations thereof, but is limited thereto. It is not.

According to one embodiment of the present application, the gas containing carbon is CH ₄ , C ₂ H ₆ , C ₃ H ₈ , C ₄ H ₁₀ , C ₅ H ₁₂ , C ₆ H ₁₄ , C ₇ H ₁₆ , C ₂ H ₄ , C ₂ H ₂ , C ₃ H ₆ , C ₃ H ₄ , C ₄ H ₈ , C ₄ H ₆ , C ₅ H ₁₀ , C ₅ H ₈ , C ₆ H ₁₂ , C ₆ H ₁₀ , C ₇ It may include a material selected from the group consisting of H ₁₄ , C ₇ H _{12, and combinations thereof, but is not limited thereto.} For example, the gas containing carbon may be CH ₄ , but is not limited thereto.

Referring to FIG. 3, the graphene layer may be formed by a tube-type CVD process using _{CH 4 gas.}

The graphene according to the present application refers to a material in which a carbon atom has a hexagonal structure, and may include graphene, graphene oxide, and reduced graphene oxide.

According to the exemplary embodiment of the present application, the graphene may be synthesized at 800° C. to 1200° C., but is not limited thereto.

In this regard, the graphene may be synthesized in a state in which it is in contact with the outer surface of the silicon particles, and the structure in the state may be referred to as an intermediate.

Subsequently, gas phase etching of the outer surface of the silicon particles present in the graphene is performed (S200).

According to the exemplary embodiment of the present disclosure, a hole may be formed between the core and the shell, but is not limited thereto.

According to the exemplary embodiment of the present disclosure, the pores may enable volume expansion of 450% or less of the core without deformation of the shell structure, but are not limited thereto.

According to the exemplary embodiment of the present disclosure, with respect to 100 parts by volume of the yoke-shell structure, the pores may be 70 parts by volume to 90 parts by volume, but are not limited thereto. For example, for 100 parts by volume of the yoke-shell structure, the pores are about 70 parts by volume to about 90 parts by volume, about 70 parts by volume to about 85 parts by volume, about 70 parts by volume to about 80 parts by volume, about 70 parts by volume. It may be a volume part to about 75 part by volume, about 75 part by volume to about 90 part by volume, about 75 part by volume to about 85 part by volume, or about 75 part by volume to about 80 part by volume, but is not limited thereto.

As described above, when the silicon particles receive and store or release the lithium ions, the volume may expand to about 450%. If the silicon particles are not etched, the structure of the intermediate may be damaged by the volume expansion.

However, in the case of the yoke-shell structure in which the pores exist between the core (silicon particles) and the shell (graphene layer), the volume expands even when the silicon particles react with the lithium ions (pores). Since this is secured, even if the silicon particles react with the lithium ions, the structure of the yoke-shell structure is not damaged, so that stability can be improved.

According to the exemplary embodiment of the present disclosure, before performing the gas phase etching of the outer surface of the silicon particle, _{the step of forming silica (SiO 2} ) on the surface of the silicon particle by oxidizing the silicon particle may not be included. However, it is not limited thereto.

According to the exemplary embodiment of the present disclosure, the etched silicon particles may have a size of 20 nm to 60 nm, but are not limited thereto. For example, the size of the etched silicon particles is about 20 nm to about 60 nm, about 20 nm to about 50 nm, about 20 nm to about 40 nm, about 20 nm to about 30 nm, about 30 nm to about 60 nm, about 40 nm to about 60 nm, about 50 nm to about 60 nm, about 30 nm to about 50 nm, or about 40 nm, but is not limited thereto.

In the case of a conventional method for manufacturing a yoke-shell structure including graphene/silicon particles, forming silica by oxidizing silicon particles, forming graphene on the surface of the silica, and wet etching the silica It includes the step of.

Wet etching has the advantage of having a high selectivity since it can only etch a specific material because it etch a material through a chemical reaction. However, the wet etching has a high tendency to be etched in all directions (isotropic), and there are many chemical wastes generated after the etching reaction, and the etched material may be contaminated. There are disadvantages such as an increase in the number.

Since the method of manufacturing a yoke-shell structure according to the present application does not include the step of oxidizing the silica surface, but includes a gas phase etching process of directly etching the surface of the silicon particles, compared to the conventional method of manufacturing a yoke-shell structure The yield can be improved.

Specifically, since the gas phase etching process according to the present application etching materials through physical and chemical methods, the selectivity ratio is low, but the accuracy is high, and there are few wastes generated after the etching reaction. For the above reasons, the gas phase etching process does not require a post-treatment process such as a waste or impurity treatment process compared to the wet etching process, and thus a yoke-shell structure can be more efficiently manufactured.

Therefore, compared to the conventional method for manufacturing a yoke-shell structure, the method for manufacturing a yoke-shell structure according to the present invention has an advantage in that it has a simple process and does not cause a decrease in yield due to wet etching.

According to the exemplary embodiment of the present disclosure, the outer surface of the silicon particles may be etched by a gas selected from the group consisting _{of HCl, HF, SF 6} , HBr, CF ₄ , C ₄ H _{8, and combinations thereof,} It is not limited thereto.

According to the exemplary embodiment of the present disclosure, the step of etching the outer surface of the silicon particles may be performed at 800° C. to 1200° C., but is not limited thereto.

In addition, the second aspect of the present application is prepared by the first aspect of the present application, and a void exists between the graphene and the silicon particles, providing a yoke-shell structure.

With respect to the yoke-shell structure according to the second aspect of the present application, detailed descriptions of parts overlapping with the first aspect of the present application have been omitted, but even if the description is omitted, the content described in the first aspect of the present application is the second aspect of the present application. The same can be applied to the side

In addition, a third aspect of the present application provides a negative electrode for a lithium secondary battery including a negative active material and a water-soluble polymer including a yoke-shell structure according to the second aspect of the present application.

With respect to the negative electrode for a lithium secondary battery according to the third aspect of the present application, detailed descriptions of portions overlapping with the first aspect of the present application have been omitted, but even if the description is omitted, the content described in the first aspect of the present application is the third aspect of the present application. The same can be applied to the side

The lithium secondary battery according to the present application refers to an energy storage device that is discharged or charged by the movement of lithium ions. In this regard, when the lithium secondary battery is being charged, the lithium ions move from the negative electrode to the positive electrode, and when discharged, the lithium ions located in the positive electrode move to the negative electrode.

Specifically, when the lithium secondary battery is connected to a circuit and charged, the negative active material included in the negative electrode is oxidized to emit lithium ions and electrons. The released lithium ions and electrons may move to the positive electrode active material on the positive electrode through a wire of a circuit or an electrolyte in the lithium secondary battery. In this case, the positive active material may store the lithium ions.

Conversely, when the lithium secondary battery is discharged, the positive electrode active material releases the lithium ions stored in the discharge process. The released lithium ions may move to the negative active material and be stored.

In the charging/discharging process, when the positive active material and the negative active material react with lithium ions several times, the structure of the active materials may be damaged. If the structure of the active material is damaged, the charging/discharging efficiency may decrease, and thus there is a need to solve this problem.

The potential difference between the negative electrode and the positive electrode according to the present application may mean a battery voltage that is a potential difference that can be utilized when using the lithium secondary battery. Accordingly, the potential difference between the negative electrode and the positive electrode may be an index indicating the energy output of the lithium secondary battery.

According to the exemplary embodiment of the present disclosure, the yoke-shell structure may be coated with the water-soluble polymer, but is not limited thereto.

With respect to 100 parts by weight of the negative electrode for a lithium secondary battery, the water-soluble polymer may be 5 parts by weight to 15 parts by weight. When the water-soluble polymer has a part by weight within the above range, the lithium secondary battery may protect defects on the yoke-shell composite, and increase initial efficiency and reversible capacity.

The electrolyte of the lithium secondary battery may enter the yoke-shell structure. However, since the voltage applied to the lithium secondary battery is applied only to the shell of the yoke-shell structure, reduction of the electrolyte occurs only on the surface of the shell. Accordingly, the lithium secondary battery including the yoke-shell structure can be suppressed from deterioration in performance compared to the conventional lithium secondary battery.

According to one embodiment of the present application, the water-soluble polymer is carboxymethyl cellulose, carboxymethyl cellulose sodium salt, carboxymethyl cellulose ammonium salt, methyl cellulose, hydroxy methyl cellulose, hydroxy propyl cellulose, ethyl cellulose, polyvinyl alcohol, polyacrylic acid, Polyacrylic acid substituted with alkali cation or ammonium ion, poly(alkylene-maleic anhydride) copolymer substituted with alkali cation or ammonium ion, poly(alkylene-maleic acid) copolymer substituted with alkali cation or ammonium ion, polyethylene It may include a material selected from the group consisting of oxide, alginic acid, sodium alginate, and combinations thereof, but is not limited thereto.

According to one embodiment of the present application, the negative electrode for a lithium secondary battery is selected from the group consisting of Super-P carbon black, Ketjen Black, Denka Black, acetylene black, carbon black, and combinations thereof. It may further include a carbon-based conductive material, but is not limited thereto.

Since the carbon-based conductive material has high conductivity, it may be used to improve the reaction speed of the lithium secondary battery.

The present invention is to be described in more detail through the following examples, but the following examples are for illustrative purposes only and are not intended to limit the scope of the present application.

[Example 1]

On the surface of commercially available silicon nanoparticles, graphene was synthesized by an LPCVD process. _{At this time, in order to synthesize graphene, H 2} was first supplied at a flow rate of 100 sccm for 1 hour so that the temperature inside the CVD chamber was 1000° C. (heating conditions: 100 mtorr and 16° C./m). _{Subsequently, CH 4} was supplied to the CVD chamber heated to 1000° C. at a flow rate of 25 sccm for 1 hour, and graphene was synthesized under a pressure condition of 5 torr.

Subsequently, after sufficiently removing the gas in the chamber, HCl was supplied at 1000° C. at a flow rate of 10 sccm for 2 hours, and the surface of the silicon nanoparticles was etched under a pressure condition of 100 mtorr to prepare a negative active material. In this case, the negative active material means a yoke-shell structure of graphene/pore/Si.

Subsequently, a slurry prepared by dispersing 80 wt% of the active material, 10 wt% of super-P carbon black, and 10 wt% of sodium alginate in deionized water was applied to copper, and then left in a vacuum at 90° C. for about 12 hours to prepare an electrode. As an electrolyte, a mixture of 3: 7 ethylene carbonate/dimethyl carbonate and 1.3 M LiPF ₆ to which 2 v% of fluoroethylene carbonate was added was used.

[Comparative Example]

Although an electrode was manufactured in the same process as in Example, since the process of supplying HCl was not performed, the silicon nanoparticles on the yoke-shell structure were not etched, so the electrode includes a graphene/Si structure.

[Experimental Example 1]

A coin cell 2032 was manufactured in a glove box to contain the material prepared through the process of the above example, and a cell test was conducted.

The battery experiment was charged and discharged at 0.1 C, 0.001 V to 1.5 V, and in the second cycle, the battery had a capacity of 1522 mAh/g, and the capacity was maintained for 20 cycles or more.

[Experimental Example 2]

4 is a diagram showing a change in a structure according to the comparative example, and FIG. 5 is a diagram showing a change in a yoke-shell structure according to the above embodiment.

Referring to FIG. 4, in the structure, the graphene is formed on the surface of the silicon nanoparticles. Accordingly, in the lithium secondary battery including the structure, the structure is damaged by the reaction of the silicon nanoparticles and lithium ions during the charging process.

However, referring to FIG. 5, it can be seen that the yoke-shell structure has sufficient space for expansion even when the silicon nanoparticles react with lithium, so that there is no fear of damage to the structure during charging and discharging. .

The foregoing description of the present application is for illustrative purposes only, and those of ordinary skill in the art to which the present application pertains will be able to understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, it should be understood that the embodiments described above are illustrative and non-limiting in all respects. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as being distributed may also be implemented in a combined form.

The scope of the present application is indicated by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present application.

Claims (12)

Forming a graphene layer on the surface of the silicon particles; And
Vapor phase etching the outer surface of the silicon particles present inside the graphene;
Containing,
Method of manufacturing a yoke-shell structure.
The method of claim 1,
The silicon particles form a core, the graphene layer forms a shell, and a void is formed between the core and the shell, a method of manufacturing a yoke-shell structure.
The method of claim 2,
The pores are to allow volume expansion of 450% or less of the core without deformation of the shell structure, the yoke-shell structure manufacturing method.
The method of claim 1,
The outer surface of the silicon particles is HCl, HF, SF ₆ , HBr, CF ₄ , C ₄ H ₈ , and a method of manufacturing a yoke-shell structure that is etched by a gas selected from the group consisting of combinations thereof.
The method of claim 1,
The step of forming the graphene layer is performed under the supply of a gas containing carbon, a method for producing a yoke-shell structure.
The method of claim 5,
The step of forming the graphene layer is performed by a process selected from the group consisting of tube-type CVD, LPCVD, APCVD, PECVD, ALCVD, and combinations thereof.
The method of claim 5,
The carbon-containing gas is CH ₄ , C ₂ H ₆ , C ₃ H ₈ , C ₄ H ₁₀ , C ₅ H ₁₂ , C ₆ H ₁₄ , C ₇ H ₁₆ , C ₂ H ₄ , C ₂ H ₂ , C ₃ H ₆ , C ₃ H ₄ , C ₄ H ₈ , C ₄ H ₆ , C ₅ H ₁₀ , C ₅ H ₈ , C ₆ H ₁₂ , C ₆ H ₁₀ , C ₇ H ₁₄ , C ₇ H ₁₂ , And a material selected from the group consisting of combinations thereof.
A yoke-shell structure manufactured by the manufacturing method according to any one of claims 1 to 7, wherein voids exist between the graphene and the silicon particles.
A negative electrode for a lithium secondary battery comprising a negative active material and a water-soluble polymer including the yoke-shell structure according to claim 8.
The method of claim 9,
The yoke-shell structure is coated by the water-soluble polymer, the negative electrode for a lithium secondary battery.
The method of claim 9,
The negative electrode for a lithium secondary battery further comprises a carbon-based conductive material selected from the group consisting of Super-P, Ketjen Black, Denka Black, acetylene black, carbon black, and combinations thereof. , A negative electrode for a lithium secondary battery.
The method of claim 9,
The water-soluble polymer is carboxymethyl cellulose, carboxymethyl cellulose sodium salt, carboxymethyl cellulose ammonium salt, methyl cellulose, hydroxy methyl cellulose, hydroxy propyl cellulose, ethyl cellulose, polyvinyl alcohol, polyacrylic acid, alkali cations or ammonium ions substituted Polyacrylic acid, poly(alkylene-maleic anhydride) copolymer substituted with an alkali cation or ammonium ion, poly(alkylene-maleic acid) copolymer substituted with an alkali cation or ammonium ion, polyethylene oxide, alginic acid, sodium alginate, And a material selected from the group consisting of combinations thereof.

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