KR20230115401A - SiOC for sodium ion battery and its manufacturing method, Anode material for sodium ion battery using this - Google Patents

Abstract

The present invention relates to a SiOC for a sodium ion battery, a manufacturing method thereof, and a negative electrode material for a sodium ion battery using the same. According to the present invention, a mixture preparation step of preparing a mixture by mixing silicon oil and silsesquioxane; A sealing step of putting the mixture into an inner container of a two-layered sealed container and sealing it; Heat is applied to the sealed container so that the mixture moves to the outer container through a small gap in the inner container by vaporization, but thermal decomposition is performed to produce silicon oxycarbide (SiOC) Heating step and cooling the sealed container It is possible to provide a SiOC manufacturing method for a sodium ion battery comprising a collection step of preparing and securing silicon oxycarbide (SiOC).
In addition, it is possible to provide silicon oxycarbide (SiOC) manufactured through the SiOC manufacturing method for sodium ion batteries and an anode material for sodium ion batteries using the same.

Description

SiOC for sodium ion battery and its manufacturing method, anode material for sodium ion battery using the same {SiOC for sodium ion battery and its manufacturing method, Anode material for sodium ion battery using this}

The present invention relates to SiOC for sodium ion batteries, a method for manufacturing the same, and an anode material for sodium ion batteries using the same, and more specifically, vaporization and It relates to SiOC for sodium ion batteries, which can have a spherical shape and uniform size by producing silicon oxycarbide (SiOC) through thermal decomposition, a manufacturing method thereof, and an anode material for sodium ion batteries using the same.

In recent years, interest in energy storage technology has been increasing. For example, research and development of electrochemical devices are gradually increasing as the application fields are expanded to cell phones, laptop computers, and even electric vehicle energy. In particular, interest in the development of secondary batteries among electrochemical devices is increasing.

Among the secondary batteries currently used, sodium ion batteries are in the limelight as next-generation energy storage devices due to their abundance of sodium while having operating voltages and high energy densities similar to those of conventional lithium ion batteries.

On the other hand, with the expansion of renewable energy such as solar and wind power, demand for large-capacity power storage devices is rapidly increasing, resulting in a demand for high-capacity sodium ion batteries.

According to these demands, the ideal capacity of graphite used as an anode material that determines the capacity of a sodium ion battery is 400mAh/g or less, whereas phosphorus (P) has a very high capacity of 3000mAh/g or more, making it a material that replaces hard carbon. As such, research on phosphorus (P) is being actively conducted. Also, in the case of silicon with high lithium ion storage, research is being actively conducted.

However, during charge and discharge cycles, phosphorus (P) and silicon (Si) have a disadvantage in that the volume due to repeated changes in P, Si, PxNay, and SixNay is refined due to repeated expansion and contraction, so that they can no longer be charged.

In addition, hard carbon used in sodium ion batteries should have large pores, but due to the non-uniform pore size, the storage capacity is small and the irreversibility is large.

In addition, hard carbon has a variety of sizes and shapes, and has many angular parts in a crushed form, which makes it difficult to form an SEI due to concentration of electric field during electrode configuration.

Therefore, it is necessary to develop a material that is formed in a gentle shape and has a uniform size and can be used as an anode material for a sodium ion battery to exhibit stable charge and discharge performance.

Korean Patent Registration No. 10-0814540 Sodium ion battery (registration date, 2008.03.11)

In order to solve the above problems, the present invention prepares silicon oxycarbide (SiOC) through vaporization and thermal decomposition of a mixture of silicone oil and silsesquioxane using a two-layer airtight container, thereby producing a spherical and uniform size It is an object of the present invention to provide a SiOC for sodium ion batteries that can have, a manufacturing method thereof, and an anode material for sodium ion batteries using the same.

In order to solve the above problems, a method for preparing SiOC for a sodium ion battery according to an embodiment of the present invention includes a mixture preparation step of preparing a mixture by mixing silicon oil and silsesquioxane; A sealing step of putting the mixture into an inner container of a two-layered sealed container and sealing it; Heat is applied to the sealed container so that the mixture moves to the outer container through a small gap in the inner container by vaporization, but thermal decomposition is performed to produce silicon oxycarbide (SiOC) Heating step and cooling the sealed container It is possible to provide a SiOC manufacturing method for a sodium ion battery comprising a collection step of preparing and securing silicon oxycarbide (SiOC).

In addition, the silicone oil is characterized in that it has a viscosity of 10 to 10000 cps.

In the mixture preparation step, the silicone oil and silsesquioxane are mixed in a weight ratio of 6 to 8: 0.1 to 3.

In addition, the heating step is characterized in that the heat is applied to 600 to 1200 ℃.

In addition, silicon oxycarbide (SiOC) manufactured through the SiOC manufacturing method for a sodium ion battery according to an embodiment of the present invention can be provided.

In addition, it is possible to provide an anode material for a sodium ion battery using silicon oxycarbide (SiOC) according to an embodiment of the present invention.

SiOC for a sodium ion battery and its manufacturing method according to an embodiment of the present invention as described above, and a negative electrode material for a sodium ion battery using the same, vaporize a mixture of silicone oil and silsesquioxane using a two-layer airtight container and It can have a spherical shape and a uniform size by preparing silicon oxycarbide (SiOC) through vaporization and thermal decomposition of a mixture of silicon oil and silsesquioxane using a two-layer airtight container through thermal decomposition.

Accordingly, since the storage capacity is large, the irreversibility is small, and the electric field is not concentrated, SEI formation may be facilitated.

Accordingly, stable charge and discharge efficiency and excellent reversible capacity of the sodium ion battery can be confirmed.

1 is a flowchart schematically illustrating a method for manufacturing SiOC for a sodium ion battery according to an embodiment of the present invention.
2 is a schematic diagram for explaining steps S200 and S300 of FIG. 1;
3 is a schematic diagram showing a structure in which a mixture is supplied in steps S200 and S300 of FIG. 2;
Figure 4 is an image observed in Example 1 with a scanning microscope.
Figure 5 is an image observed in Example 2 with a scanning microscope.
6 is an EDX analysis result of SiOC observed in FIG. 4;
7 is an EDX analysis result of SiOC observed in FIG. 5;
8 is a graph showing the results of charge and discharge cycles of a sodium ion battery to which Example 3 is applied.
9 is a graph showing the results of charge and discharge cycles of a sodium ion battery to which Example 4 is applied.

Since the present invention can be applied with various changes and can have various forms, specific embodiments will be described in detail in the text. However, this is not intended to limit the present invention to a specific form disclosed, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "comprise" or "having" are intended to designate that a combination of features, numbers, steps, components, etc. described in the specification exist, but one or more other features or numbers, It should be understood that the presence or addition of combinations of steps, components, etc. is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in this application, it should not be interpreted in an ideal or excessively formal meaning. don't

Here, repeated descriptions, well-known functions that may unnecessarily obscure the subject matter of the present invention, and detailed descriptions of configurations are omitted. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

In the present invention, in manufacturing SiOC for sodium ion batteries, vaporization and thermal decomposition of a mixture of silicone oil and silsesquioxane are performed using a two-layer airtight container, thereby forming sodium ions having a spherical shape and uniform size. It is intended to provide a SiOC for a battery and a manufacturing method thereof.

In addition, by applying SiOC for a sodium ion battery as an anode material, it is intended to secure a sodium ion battery having stable charge and discharge efficiency and excellent reversible capacity.

Hereinafter, it will be described in detail with reference to FIGS. 1 to 9 for explaining an embodiment of the present invention.

1 is a flowchart schematically showing a method for manufacturing SiOC for a sodium ion battery according to an embodiment of the present invention, FIG. 2 is a schematic diagram for explaining steps S200 and S300 of FIG. 1, and FIG. 3 is step S200 of FIG. And a schematic diagram showing the structure in which the mixture is supplied in step S300.

Referring to FIG. 1, the SiOC manufacturing method for a sodium ion battery according to an embodiment of the present invention may include a mixture preparation step (S100), a sealing step (S200), a heating step (S300), and a collection step (S400). .

First, in the mixture preparation step (S100), a mixture (M) may be prepared by mixing silicone oil and silsesquioxane.

The silicone oil used herein is a siloxane-based material, and may be selected from the group consisting of polydimethysioxane (PDMS) and polyhexamethylsiloxane (PHMS), or a mixture thereof.

In addition, silicone oil may preferably have a viscosity of 10 to 10000 cps. If it is less than 10 cps, it volatilizes even at a relatively low temperature and quickly escapes from the inner container 10 to the outer container 11, making it difficult to make SiOC in a desired spherical shape. , This is because it is difficult to escape from the inner container 10 to the outer container 11 when it exceeds 10000cps.

In addition, silsesquioxane is an organosilicon compound having the formula [RSiO _3/2 ] _n (R = H, alkyl, aryl or alkoxyl), which has a cage-type or polymer structure with Si-O-Si bonds and tetrahedral Si vertices. It is a colorless substance made of These silsesquioxanes are characterized by an inorganic silicate core and an organic exterior, and the inorganic silicate core has rigidity and thermal stability.

Such silsesquioxane may have a ladder structure, a hexahedral structure, an octahedral structure, etc. By adding such silsesquioxane to silicone oil, pores are formed after the cross-linking process of silicone oil to form sodium ions. can help the smooth movement of In other words, when the manufactured SiOC is applied to a sodium ion battery, high power characteristics and stable charge/discharge performance can be obtained. Furthermore, the -O-C structure can be increased to maximize the reversible capacity.

More preferably, the silsesquioxane may be octahedral silsesquioxane (POSS), which is a preceramic polymer precursor of ceramic materials and nanocomposites, wherein various substituents (R) are can be attached to the Si center.

Step S100 may prepare a mixture (M) by mixing the silicone oil and silsesquioxane as described above in a weight ratio of 6 to 8: 0.1 to 3.

At this time, when the amount of silsesquioxane is less than 0.1 relative to the weight of silicone oil, sodium ion transfer efficiency may decrease, and when it exceeds 3, problems may occur in forming SiOC.

In the sealing step (S200), as shown in FIG. 2, the mixture (M) may be put into the inner container 10 of the double-layered sealed container 1 to be sealed. At this time, the inner container 10 is composed of an inner cylinder and an inner lid with a fine small gap, and the outer container 11 is also composed of an outer cylinder and an outer lid, but the outer cylinder may be sealed by closing the outer lid. That is, it can be said that sealing is achieved by the outer container (11).

Here, the inner container 10 of the two-layer airtight container 1 has a fine gap, and when the mixture M in the inner container 10 is vaporized by heating by the heating furnace 2, the inner container 10 to be moved to the outer container (11).

Referring to FIG. 2, in the heating step (S300), the airtight container 1 containing the mixture M in the inner container 10 is put into the heating furnace 2 and heated so that heat is applied to the mixture M. can

The mixture M is vaporized through step S300 and moves to the outer container 11 through a small gap of the inner container 10, and the vaporized state moved in the space between the inner container 10 and the outer container 11 Silicon oxycarbide (SiOC) may be produced by thermal decomposition of the mixture M.

Since the outer container 11 is in direct contact with the heat source rather than the inner container 10, the mixture M is vaporized in the inner container 10, and the vaporized mixture M is thermally decomposed in the outer container 11. can be done.

As the vaporized mixture M is gradually moved to the external container 11 through the small gap and thermally decomposed, SiOC having a spherical shape and a uniform size can be obtained.

Step S300 may apply heat to the mixture (M) by heating the sealed container (1) to 600 to 1200 ℃.

In step S300, when the heating temperature is less than 600 ° C, the mixture (M) is not completely vaporized, so some silicone oil may remain after the reaction. SiOC in the form can be obtained.

In addition, step S300 may lower the pressure of the airtight container 1 to vacuum so that the mixture M is more easily vaporized, but is not limited thereto.

On the other hand, in steps S200 and S300, as shown in FIG. 3, the mixture tank 3 in which the mixture M prepared in step S100 is stored is connected to the inner container 10, so that the mixture M is the inner container ( 10) may be continuously supplied, but is not limited thereto.

In the collection step (S400), after the step S300, the airtight container (1) is cooled to room temperature to sublimate to collect and secure solid silicon oxycarbide (SiOC).

That is, this is a step of changing gaseous SiOC into solid SiOC through cooling and collecting the crystallized SiOC.

The SiOC collected here has a spherical shape and may have a uniform size.

In addition, the SiOC manufacturing method for a sodium ion battery according to an embodiment of the present invention may further include a coating step (not shown).

The coating step may coat the surface of the collected SiOC with carbon. This is to coat the surface of SiOC with carbon so that when it is used as an anode material for a sodium ion battery, electron migration is more smoothly performed.

In the coating step, carbon coating may be performed by flowing methane and argon into SiOC. Methane is applied to SiOC at a rate of 0.3 to 0.7 L/min and argon at a rate of 15 to 15 to 1.2 L/min at 900 to 1100 ° C. Carbon coating can be performed by supplying for 25 minutes. However, the coating method and conditions are not limited thereto and can be easily changed.

However, in the case where the supply rate of methane exceeds 0.7 L/min or only methane is supplied without argon, the carbon coating layer becomes too thick, and thus there may be no difference from the graphite material.

Also, when the supply rate of methane is less than 0.3 L/min, carbon coating may not be preferably performed.

It is possible to provide silicon oxycarbide (SiOC) for a sodium ion battery manufactured through the above manufacturing method.

Silicon oxycarbide (SiOC) for sodium ion batteries according to an embodiment of the present invention has a spherical shape and may have a uniform size.

Accordingly, when silicon oxycarbide (SiOC) is applied to an anode material for a sodium ion battery, it suppresses Na consumed during SEI formation due to a uniform electric field value due to its uniform spherical shape, resulting in a combination of Na and Si, which increases the possibility of energy storage. can have

Therefore, the anode material for a sodium ion battery to which silicon oxycarbide (SiOC) of the present invention is applied may have high initial charge capacity and discharge capacity, excellent initial efficiency, and excellent reversible capacity.

As described above, the SiOC for sodium ion batteries according to an embodiment of the present invention, the manufacturing method thereof, and the anode material for sodium ion batteries using the same are a mixture of silicone oil and silsesquioxane using a two-layer airtight container. Through vaporization and thermal decomposition of (M), silicon oxycarbide (SiOC) is produced through vaporization and thermal decomposition of a mixture (M) in which silicon oil and silsesquioxane are mixed using a two-layer airtight container, thereby producing a spherical and uniform shape. can have a size.

Accordingly, since the storage capacity is large, the irreversibility is small, and the electric field is not concentrated, SEI formation may be facilitated.

Accordingly, stable charge and discharge efficiency and excellent reversible capacity of the sodium ion battery can be confirmed.

Hereinafter, the present invention will be described in more detail by examples.

However, the following examples are only to illustrate the present invention, and the content of the present invention is not limited by the following examples.

In addition, the embodiments of the present invention described below may be implemented by various substitutions, modifications, and changes without departing from the technical spirit of the present invention, and such implementations are of the technical field to which the present invention belongs from the description of the above-described embodiments. If you are an expert, it is easy to implement.

[Example]

[Example 1]

30 g of silicone oil having a viscosity of 1000 cps and 5 g of silsesquioxane were mixed, put into an inner container, closed, and then put into an outer container to seal the inner container. Then, the airtight container was placed in a heating furnace heated to 700° C., waited for about 20 minutes, and then cooled to room temperature. It was prepared by opening the sealed container and collecting the SiOC formed in the outer container.

[Example 2]

30 g of silicone oil having a viscosity of 1000 cps and 5 g of silsesquioxane were mixed, put into an inner container, closed, and then put into an outer container to seal the inner container. Then, the airtight container was placed in a heating furnace heated to 1000° C., waited for about 20 minutes, and then cooled to room temperature. It was prepared by opening the sealed container and collecting the SiOC formed in the outer container.

[Example 3]

The SiOC powder prepared in Example 1 was put into a preheated horizontal chemical vapor deposition reactor and flowed at 1000 ° C. with 0.5 L / min of methane and 1 L / min of argon for 20 minutes to perform carbon coating. prepared in the same way.

[Example 4]

The SiOC powder prepared in Example 4 was put into a preheated horizontal chemical vapor deposition reactor and flowed at 1000 ° C. with 0.5 L / min of methane and 1 L / min of argon for 20 minutes to perform carbon coating. prepared in the same way.

[Experimental Example 1] SiOC analysis

In order to confirm the characteristics of the SiOC of the present invention, Examples 1 and 2 were observed with a scanning microscope (SEM), and EDX analysis was performed. The results are shown in FIGS. 4 to 7 .

4 is an image of Example 1 observed with a scanning microscope, and FIG. 5 is an image of Example 2 observed with a scanning microscope.

6 is an EDX analysis result of SiOC observed in FIG. 4, and FIG. 7 is an EDX analysis result of SiOC observed in FIG.

As can be seen from FIGS. 4 to 7, it was confirmed that the SiOC of Examples 1 and 2 had a spherical shape and was formed in a uniform size.

[Experimental Example 2] Sodium ion battery performance evaluation

In order to evaluate the performance of the sodium ion battery to which the SiOC of the present invention is applied, after preparing negative electrodes in Examples 3 and 4, the electrochemical characteristics of the sodium ion battery to which the prepared negative electrode was applied were measured.

Here, the negative electrode of the sodium ion battery was prepared by mixing 80% by weight of SiOC, 10% by weight of acetylene black, and 10% by weight of polyacrylic acid binder in a solvent to prepare a negative electrode slurry prepared in Examples 3 and 4, and then It was prepared by coating, and sodium metal was used as the anode.

As an electrolyte, 1M NaOClO ₄ was mixed with a solution in which the volume ratio (vol %) of the ethylene carbonate/diethyl carbonate/propylene carbonate solution was 1:1:1.

The charge and discharge cycles of the sodium ion battery prepared as described above were measured, and the results are shown in FIGS. 8 and 9.

8 is a graph showing the results of charge and discharge cycles of the sodium ion battery to which Example 3 is applied, and FIG. 9 is a graph showing the results of charge and discharge cycles to the sodium ion battery to which Example 4 is applied.

As can be seen in FIGS. 8 and 9, both Examples 3 and 4 have high initial charge and discharge capacities, excellent initial efficiency, and excellent reversible capacity as the capacity is maintained at the initial level of 60% after 100 cycles. I was able to confirm.

As above, specific parts of the contents of the present invention have been described in detail, and for those skilled in the art, these specific descriptions are only preferred embodiments, and the scope of the present invention is not limited thereby. It will be clear. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

M: mixture
1: sealed container
10: Inner container
11: outer container
2: heating furnace
3: mixture tank

Claims (5)

A mixture preparation step of preparing a mixture by mixing silicone oil and silsesquioxane;
A sealing step of putting the mixture into an inner container of a two-layered sealed container and sealing it;
A heating step of producing silicon oxycarbide (SiOC) by applying heat to the airtight container so that the mixture moves to an outer container through a small gap in the inner container by vaporization and is thermally decomposed; and
SiOC manufacturing method for a sodium ion battery comprising a collection step of cooling the sealed container and securing silicon oxycarbide (SiOC).
According to claim 1,
The silicone oil,
SiOC manufacturing method for sodium ion batteries, characterized in that it has a viscosity of 10 to 10000 cps.
According to claim 1,
In the heating step,
SiOC manufacturing method for a sodium ion battery, characterized in that by applying heat to 600 to 1200 ℃.
Silicon oxycarbide (SiOC) manufactured through the manufacturing method of any one of claims 1 to 3.
An anode material for a sodium ion battery using the silicon oxycarbide (SiOC) of claim 4.