KR102687502B1 - 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 SiOC for sodium ion batteries, a manufacturing method thereof, and a negative electrode material for sodium ion batteries using the same. According to the present invention, a mixture preparation step of mixing silicone oil and silsesquioxane to prepare a mixture; A sealing step of sealing the mixture by placing it in the inner container of a two-layer sealed container; A heating step of producing silicon oxycarbide (SiOC) by applying heat to the sealed container, allowing the mixture to vaporize and move to the external container through a small gap in the inner container while causing thermal decomposition, and cooling the sealed container. It is possible to provide a SiOC manufacturing method for sodium ion batteries that includes a collection step to secure silicon oxycarbide (SiOC).
In addition, silicon oxycarbide (SiOC) manufactured through a SiOC manufacturing method for sodium ion batteries and a negative electrode material for sodium ion batteries using the same can be provided.

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 of manufacturing the same, and a negative electrode material for sodium ion batteries using the same. More specifically, it relates to vaporization and evaporation of a mixture of silicone oil and silsesquioxane using a two-layer sealed container. This relates to SiOC for sodium ion batteries that can have a spherical shape and uniform size by producing silicon oxycarbide (SiOC) through thermal decomposition, a method for manufacturing the same, and a negative electrode material for sodium ion batteries using the same.

Recently, interest in energy storage technology has been increasing. For example, research and development of electrochemical devices is increasing as the application areas expand to mobile phones, laptops, and even electric vehicles. In particular, interest in the development of secondary batteries among electrochemical devices is increasing.

Among secondary batteries currently in use, sodium-ion batteries are attracting attention as next-generation energy storage devices due to their abundance of sodium while having similar operating voltage and high energy density to conventional lithium-ion batteries.

Meanwhile, with the expansion of new and renewable energy such as solar and wind power, the demand for large-capacity power storage devices is rapidly increasing, leading to a demand for high-capacity sodium ion batteries.

According to these requirements, the ideal capacity of graphite, which is used as a cathode material that determines the capacity of sodium ion batteries, is less than 400 mAh/g, while the ideal capacity of phosphorus (P) is over 3000 mAh/g, making it a material that replaces hard carbon. Research on phosphorus (P) is actively underway. Additionally, research is being actively conducted on silicon, which has a high storage capacity for lithium ions.

However, during the charge/discharge cycle, phosphorus (P) and silicon (Si) have the disadvantage that they can no longer be charged because the volume is miniaturized through repeated expansion and contraction due to repeated changes in P, Si, PxNay, and SixNay.

In addition, hard carbon used in sodium-ion batteries requires large pores, but has the disadvantages of low storage capacity and high irreversibility due to uneven pore size.

In addition, hard carbon has a wide variety of sizes and shapes, and has many angled parts in a shredded form, so it has the disadvantage of concentrating the electric field when forming electrodes, making SEI formation difficult.

Therefore, there is a need to develop a material that is formed in a gentle shape and has a uniform size, so that it can be used as a negative electrode material for sodium ion batteries and exhibit stable charge and discharge performance.

Korean Patent No. 10-0814540 Sodium ion battery (registration date, March 11, 2008)

In order to solve the above problems, the present invention manufactures silicon oxycarbide (SiOC) through vaporization and thermal decomposition of a mixture of silicone oil and silsesquioxane using a two-layer sealed container, thereby producing spherical and uniform size. The purpose of the present invention is to provide SiOC for sodium ion batteries, a manufacturing method thereof, and a negative electrode material for sodium ion batteries using the SiOC.

In order to solve the above problems, the SiOC manufacturing method for sodium ion batteries according to an embodiment of the present invention includes a mixture preparation step of mixing silicone oil and silsesquioxane to prepare a mixture; A sealing step of sealing the mixture by placing it in the inner container of a two-layer sealed container; A heating step of producing silicon oxycarbide (SiOC) by applying heat to the sealed container, allowing the mixture to vaporize and move to the external container through a small gap in the inner container while causing thermal decomposition, and cooling the sealed container. It is possible to provide a SiOC manufacturing method for sodium ion batteries that includes a collection step to secure silicon oxycarbide (SiOC).

Additionally, the silicone oil is characterized as having a viscosity of 10 to 10,000 cps.

In addition, the mixture preparation step is characterized by mixing the silicone oil and silsesquioxane at a weight ratio of 6 to 8:0.1 to 3.

Additionally, the heating step is characterized by applying heat to 600 to 1200°C.

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

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

SiOC for sodium ion batteries and its manufacturing method according to the embodiment of the present invention as described above, and the anode material for sodium ion batteries using the same are vaporized and mixed with a mixture of silicone oil and silsesquioxane using a two-layer sealed container. By producing silicon oxycarbide (SiOC) through vaporization and thermal decomposition of a mixture of silicone oil and silsesquioxane using a two-layer sealed container through thermal decomposition, it can have a spherical shape and uniform size.

Accordingly, the storage capacity is large, the irreversibility is small, and the electric field is not concentrated, so SEI formation can be easy.

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

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

Since the present invention can be subject to various changes and 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 disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

The 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 “have” are intended to designate the existence of a combination of features, numbers, steps, components, etc. described in the specification, but are not limited to one or more other features or numbers, It should be understood that the existence or addition possibility of combinations of steps, components, etc. is not excluded in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless clearly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

Here, repeated descriptions, known functions that may unnecessarily obscure the gist 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, a two-layer sealed container is used to vaporize and thermally decompose a mixture of silicone oil and silsesquioxane to produce sodium ions having a spherical shape and uniform size. The purpose is to provide SiOC for batteries and its manufacturing method.

In addition, by applying SiOC for sodium ion batteries as a negative electrode material, we aim to secure a sodium ion battery with stable charge and discharge efficiency and excellent reversible capacity.

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

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

Referring to Figure 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), the mixture (M) can be prepared by mixing silicone oil and silsesquioxane.

The silicone oil used here is a siloxane-based material and may be selected from the group consisting of polydimethysioxane (PDMS), polyhexamethylsiloxane (PHMS), etc., alone or in a mixed form thereof.

In addition, the silicone oil may preferably have a viscosity of 10 to 10,000 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 produce SiOC in the desired spherical shape. This is because, if it exceeds 10000cps, it is difficult to escape from the inner container (10) to the outer container (11).

Silsesquioxane is also an organosilicon compound with the formula [RSiO _3/2 ] _n (R = H, alkyl, aryl, or alkoxyl), which has a cage-like or polymer structure with Si-O-Si bonds and tetrahedral Si vertices. It is a colorless substance made of. These silsesquioxanes feature an inorganic silicate core and an organic exterior, with the inorganic silicate core being rigid and thermally stable.

This 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 the silicone oil, thereby releasing sodium ions. It can help with smooth movement. In other words, when SiOC manufactured in a sodium ion battery is applied, high output characteristics and stable charge/discharge performance can be achieved. Furthermore, the reversible capacity can be maximized by increasing the -O-C structure.

More preferably, the silsesquioxane may be polyoctahedral silsesquioxane (POSS), which is a preceramic polymer precursor for ceramic materials and nanocomposites, and has various substituents (R). It can be attached to the Si center.

In step S100, a mixture (M) can be prepared by mixing the silicone oil and silsesquioxane as described above at a weight ratio of 6 to 8:0.1 to 3.

At this time, if the silsesquioxane is less than 0.1 by weight of silicone oil, the sodium ion transfer efficiency may be reduced, and if it is more than 3, problems with SiOC formation may occur.

In the sealing step (S200), as shown in FIG. 2, the mixture (M) can be sealed by putting the mixture (M) in the inner container (10) of the double-layer sealed container (1). At this time, the inner container 10 is composed of an inner container and an inner lid and has a fine small gap, and the outer container 11 is also composed of an outer container and an outer lid, but the outer container can be sealed by closing the outer lid. In other words, it can be said that sealing is achieved by the external container 11.

Here, there is a fine gap in the inner container (10) of the two-layer sealed container (1), and when it is heated by the heating furnace (2) and the mixture (M) in the inner container (10) is vaporized, the inner container (10) so that it can be moved from to the external container (11).

Referring to FIG. 2, the heating step (S300) involves putting the sealed container (1) containing the mixture (M) in the inner container (10) into the heating furnace (2) and heating it, so that heat is applied to the mixture (M). You can.

Through step S300, the mixture (M) is vaporized and moves to the outer container (11) through a small gap in the inner container (10), and the vaporized state moved in the space between the inner container (10) and the outer container (11) By causing thermal decomposition of the mixture (M), silicon oxycarbide (SiOC) can be produced.

Since the outer container 11 is in direct contact with the heat source 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 achieved.

As the vaporized mixture (M) is gradually moved to the external container 11 through the small gap and thermal decomposition occurs, spherical and uniformly sized SiOC can be obtained.

In step S300, heat can be applied to the mixture (M) by heating the sealed container (1) to 600 to 1,200°C.

In the S300 step, if the heating temperature is less than 600℃, the vaporization of the mixture (M) does not occur completely, so some silicone oil may remain after the reaction. If the heating temperature exceeds 1200℃, the vaporized mixture (M) is rapidly thermally decomposed to form very small particles. form of SiOC can be obtained.

In addition, step S300 may lower the pressure of the sealed container (1) to a vacuum so that the mixture (M) can be more easily vaporized, but is not limited to this.

Meanwhile, in steps S200 and S300, as shown in FIG. 3, the mixture tank 3 storing the mixture M prepared in step S100 is connected to the internal container 10, so that the mixture M is stored in the internal container ( 10) can be supplied continuously, but is not limited to this.

In the collection step (S400), solid silicon oxycarbide (SiOC) can be collected and secured by cooling the sealed container (1) to room temperature after step S300 and allowing it to sublime.

In other words, this is the step of changing gaseous SiOC into solid SiOC through cooling and collecting the crystallized SiOC.

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

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

The coating step may coat carbon on the surface of the collected SiOC. This is to coat the surface of SiOC with carbon to ensure smoother electron transfer when used as a negative electrode material for a sodium ion battery.

In the coating step, carbon coating can be performed by flowing methane and argon through SiOC. Methane at a rate of 0.3 to 0.7 L/min and argon at a rate of 0.8 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 to this and can be easily changed.

However, if the supply rate of methane exceeds 0.7 L/min or if only methane is supplied without argon, the carbon coating layer may become so thick that there is no difference from the graphite material.

Additionally, if the methane supply rate is less than 0.3 L/min, carbon coating may not be performed optimally.

Silicon oxycarbide (SiOC) for sodium ion batteries manufactured through the above manufacturing method can be provided.

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 anode materials for sodium-ion batteries, it suppresses the Na consumed during SEI formation due to its uniform electric field value due to its uniform spherical shape, and the bonding of Na and Si occurs, increasing the possibility of energy storage. You can have it.

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

As described above, SiOC for sodium ion batteries and its manufacturing method according to an embodiment of the present invention, and the anode material for sodium ion batteries using the same, are a mixture of silicone oil and silsesquioxane using a two-layer sealed container. By manufacturing silicon oxycarbide (SiOC) through vaporization and thermal decomposition of a mixture of silicon oil and silsesquioxane (M) using a two-layer sealed container, spherical and uniform It can have any size.

Accordingly, the storage capacity is large, the irreversibility is small, and the electric field is not concentrated, so SEI formation can be easy.

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

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

However, the following examples only 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 can be implemented with various substitutions, modifications, and changes without departing from the technical spirit of the present invention, and these implementations are within the scope of the technical field to which the present invention belongs from the description of the embodiments described above. Any expert can easily implement it.

[Example]

[Example 1]

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

[Example 2]

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

[Example 3]

The SiOC powder prepared in Example 1 was placed in a preheated horizontal chemical vapor deposition reactor, and carbon coating was performed by flowing 0.5 L/min of methane and 1 L/min of argon at 1000°C for 20 minutes. It was prepared in the same way.

[Example 4]

The SiOC powder prepared in Example 4 was placed in a pre-heated horizontal chemical vapor deposition reactor, and carbon coating was performed by flowing 0.5 L/min of methane and 1 L/min of argon at 1000°C for 20 minutes. It was prepared in the same way.

[Experimental Example 1] SiOC analysis

In order to confirm the characteristics of 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 Figures 4 to 7.

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

Figure 6 is the EDX analysis result of SiOC observed in Figure 4, and Figure 7 is the EDX analysis result of SiOC observed in Figure 5.

As can be seen from Figures 4 to 7, it was confirmed that in both Examples 1 and 2, SiOC 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 was applied, a negative electrode was manufactured in Examples 3 and 4, and then the electrochemical properties of the sodium ion battery to which the manufactured 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 prepared in Examples 3 and 4 with a solvent to prepare a negative electrode slurry, which was then applied to the copper foil current collector. It was manufactured by coating, and sodium metal was used as the anode.

As an electrolyte, 1M NaOClO ₄ was used by mixing ethylene carbonate/diethyl carbonate/propylene carbonate solution with a volume ratio (vol%) of 1:1:1.

The charge/discharge cycle of the sodium ion battery manufactured as above was measured, and the results are shown in Figures 8 and 9.

FIG. 8 is a graph showing the charge/discharge cycle results of a sodium ion battery using Example 3, and FIG. 9 is a graph showing the charge/discharge cycle results of a sodium ion battery using Example 4.

As can be seen in Figures 8 and 9, both Examples 3 and 4 have high initial charging and discharging capacities, excellent initial efficiency, and the capacity is maintained at the initial 60% after 100 cycles, showing excellent reversible capacity. I was able to confirm.

Above, specific parts of the content of the present invention have been described in detail, and for those skilled in the art, it is clear that these specific techniques are merely preferred embodiments and do not limit the scope of the present invention. It will be obvious. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

M: mixture
1: Airtight container
10: Inner container
11: External container
2: Heating furnace
3: Mixture tank

Claims (5)

A mixture preparation step of mixing silicone oil and silsesquioxane to prepare a mixture;
A sealing step of sealing the mixture by placing it in the inner container of a two-layer sealed container;
A heating step of producing silicon oxycarbide (SiOC) by applying heat to the sealed container so that the mixture moves to the outer container through a small gap in the inner container by vaporization and undergoes thermal decomposition; and
A SiOC manufacturing method for a sodium ion battery comprising a collection step of cooling the sealed container and securing silicon oxycarbide (SiOC).
According to paragraph 1,
The silicone oil is,
A method for producing SiOC for a sodium ion battery, characterized in that it has a viscosity of 10 to 10000 cps.
According to paragraph 1,
The heating step is,
A method for manufacturing SiOC for sodium ion batteries, characterized by applying heat to 600 to 1200°C.
Silicon oxycarbide (SiOC) manufactured through the production method according to any one of claims 1 to 3.
A negative electrode material for a sodium ion battery using the silicon oxycarbide (SiOC) of claim 4.