KR101965195B1 - Layered inorganic nanosheet-graphene composite, and preparing method of the same - Google Patents

Abstract

A method for producing a layered inorganic nanosheet-graphene composite and a method for producing the layered inorganic nanosheet-graphene composite formed by re-layering with a cation-containing solution, the method comprising: peeling a first inorganic nanosheet and a second inorganic nanosheet ; Mixing the peeled first inorganic nanosheet, the peeled second inorganic nanosheet, and graphene; And adding a cation-containing solution to the mixture to obtain the layered inorganic nanosheet-graphene composite on which the peeled first inorganic nanosheet, the peeled second inorganic nanosheet, and the graphene are re-laminated .

Description

[0001] LAYERED INORGANIC NANOSHEET-GRAPHENE COMPOSITE, AND PREPARING METHOD OF THE SAME [0002]

The present invention relates to a layered inorganic nanosheet-graphene composite formed by repositioning with a cation-containing solution, and a method for producing the layered inorganic nanosheet-graphene composite.

While the development of new and renewable energy and the reduction of carbon dioxide are essential, it is essential to develop a secondary battery capable of storing electric power in order to efficiently use the produced energy.

Among these secondary batteries, researches on sodium secondary batteries having the advantage of being able to manufacture a large-capacity battery with a simple structure compared with a lithium ion battery have excellent competitiveness in terms of material water ac- curacy and manufacturing cost by using abundant sodium on the earth It is progressing.

In the case of the conventional non-aqueous sodium secondary battery, a highly explosive organic acid solution is used as a non-aqueous electrolyte, and thus there is a danger of explosion in case of fire. The organic liquid electrolyte has a limitation in accumulating active materials due to the limit of ionic conductivity. In addition, expensive equipment is necessary to constitute an environment for manufacturing a nonaqueous sodium secondary battery, and the manufacturing cost is high because the cost of the sodium salt, organic solution, and separation membrane used is high.

On the other hand, the aqueous electrolyte can solve the problem of safety and high manufacturing cost caused by using the non-aqueous electrolyte. First, since the aqueous electrolyte is water-free, it is safe because it is non-flammable and non-toxic and has no risk of fire or explosion, and its ionic conductivity is 100 times higher than that of the organic electrolyte. Therefore, many active materials can be accumulated, · There is an advantage of discharging.

In addition, the water-soluble sodium salt and water are abundant and inexpensive, and the separation membrane to be used is also inexpensive. Moreover, since the reactivity with water is not considered, the process is simplified and the cost is low.

In recent years, stratified materials have been attracting attention as electrode materials for sodium secondary batteries. The layered material can be peeled off into nanosheets having 1 to several nanometers in thickness. In addition, graphene as an electrode material has been known to have an effect of improving the ionic conductivity and electrical conductivity of an electrode material, and a study on the application of an electrode of a material in which graphene and a layered inorganic nanosheet are hybridized is carried out by many researchers . However, in most cases, using such a method as hydrothermal synthesis, it is difficult to mix two or more sheet materials [Chem. Asian J. 2014, 9, 1611-1617].

The present application is to provide a layered inorganic nanosheet-graphene composite formed by repositioning with a cation-containing solution and a process for producing the layered inorganic nanosheet-graphene composite.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

The first aspect of the present invention provides a layered inorganic nanosheet-graphene composite comprising a first inorganic nanosheet, a second inorganic nanosheet, and a layered structure formed by re-layering graphene.

According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: peeling a first inorganic nanosheet and a second inorganic nanosheet; Mixing the peeled first inorganic nanosheet, the peeled second inorganic nanosheet, and the graphen sheet; And adding a cation-containing solution to the mixture to obtain the layered inorganic nanosheet-graphene composite on which the peeled first inorganic nanosheet, the peeled second inorganic nanosheet, and the graphene are re-laminated Graphene nanocrystalline graphene nanoparticle-graphene composite.

A third aspect of the invention provides a sodium ion cell comprising a layered inorganic nanosheet-graphene composite according to the first aspect of the present application.

In one embodiment of the invention, there is provided a method of synthesizing a layered inorganic nano-sheet-graphene composite through a simple method of re-depositing inorganic nanosheets and graphenes using cations at room temperature. Specifically, a method for producing the layered inorganic nano-sheet-graphene composite includes mixing a small amount of metal oxide nanosheets in a process of adding a cation-containing solution to a mixture of a metal chalcogenide nanosheet and graphene, The layered inorganic nano-sheet-graphene composite can be produced.

According to an embodiment of the present invention, since the metal chalcogenide nanosheets, the metal oxide nanosheets, and the graphenes are both negatively charged, they can be uniformly mixed with each other, and by the cation of the added cation-containing solution It can be easily re-laminated at room temperature to hybridize.

Also, according to one embodiment of the present invention, when a composite in which a small amount of the metal oxide nanosheets are added is used as an electrode material, battery performance can be improved, and compared with the case where only a metal chalcogenide nanosheet and graphene are mixed And can provide improved capacity and improved cycle stability. In addition, the addition of the metal oxide nanosheets can prevent the graphenes from being reallocated in the battery charge / discharge process.

Figures 1 (a) to 1 (c) illustrate an embodiment of the present invention wherein X-ray diffraction of SnS ₂ , SnS ₂ / graphene, and SnS ₂ / graphene / TiO ₂ , Fig.
2 (a) - (c) illustrate the scanning electron microscope images of SnS ₂ , SnS ₂ / graphene, and SnS ₂ / graphene / TiO _{2 re-} deposited after exfoliation, to be.
3 (a) to 3 (c) show transmission electron microscope images of SnS ₂ , SnS ₂ / graphene, and SnS ₂ / graphene / TiO _{2 re-} deposited after peeling, respectively, in one embodiment of the invention to be.
Figures 4A-4C illustrate, in one embodiment of the present invention, the re-deposited SnS ₂ , SnS ₂ / graphene, and SnS ₂ / graphene / TiO ₂ (Red: 1 cycle, blue: 2 cycles, green: 3 cycles) according to charge / discharge capacity. 0.01 to 2.5 V, measured at 200 mA / g.
FIG. 5 is a schematic view showing a process of synthesizing Na-SnS ₂ -rG-O-titanate (NSGT) nanocomposite in one embodiment of the present invention.
Figure 6 shows, in one embodiment, a powder XRD pattern: (a) bulk SnS ₂ , (b) reconstituted Na-rG-O, (c) Na-SnS ₂ nanocomposite, laminated Na-SnS ₂ -rG-O- titanate nanocomposite (d) NSGT0, (e) NSGT1, (f) NSGT2.5, and (g) NSGT5.
Figure 7, in one embodiment of the present application, (a) the registered floor Na-SnS ₂ nanocomposite layer and registered with Na- SnS ₂ -rG-O- titanate nanocomposite (b) NSGT0, (c) NSGT1 (Fig. 7A), HR-TEM image (Fig. 7B, Fig. 7C) and EF-TEM-element map (Fig. 7D) of NSGT2.5 and NSGT5.
Figure 8 is, in one embodiment of the present application, the registered floor Na-SnS ₂ -rG-O- titanate nanocomposite (a) NSGT0, (b) NSGT1, (c) NSGT2.5, and (d) NSGT5 Field scanning electron microscope (FE-SEM) image and energy dispersive spectrometer (EDS) -element map.
Figure 9 shows Sn K-edge XANES spectra (Figure 8A) and Ti K-edge XANES spectra (Figure 8B) in one embodiment of the present invention: (a) SnS / (C) Na-SnS ₂ / anatase TiO ₂ , reconstituted (d) Na-SnS ₂ of NSGTO / rutile TiO ₂ , (b) initial SnS ₂ / trititanate-type layered titanate (e) NSGT1, (f) NSGT2.5, and (g) NSGT5.
Figure 10 is, in one embodiment of the present application, micro-Raman spectrum (Fig. 10A) and 1,200 ~ 1750 cm ^- shows an enlarged view of the ^first wavelength region: (a) initial _{SnS 2, (b) rG-} 0, (c) a layer enrolled _{Na-SnS 2, Na-SnS} 2 -rG-O- titanate nanocomposite (d) NSGT0, (e) NSGT1, (f) NSGT2.5, and (g) NSGT5.
Figure 11 is, in one embodiment of the present application, N ₂ adsorption-desorption same temperature line (Figure 11A) and the cavity size distribution shows a curve (Fig. 11B): The enrolled layer _{Na-SnS 2, Na-SnS} 2 -rG (A) NSGT0, (b) NSGT1, (c) NSGT2.5, and (d) NSGT5-O-titanate nanocomposite.
Figure 12 shows a graph of potential at a current density of 100 mAg < ^-1 > in one embodiment of the present application: (a) reconstituted Na-SnS ₂ Nanocomposite layer and reloading the Na-SnS ₂ -rG-O- titanate nanocomposite (b) NSGT0, (c) NSGT1, (d) NSGT2.5, and (e) NSGT5.
13 is a graph showing the relationship between the discharge capacity and coulon efficiency vs. current density at a current density of 100 mAg < ^-1 > 13A) and a velocity capacity graph (Fig. 13B): (a) reconstituted Na-SnS ₂ nanocomposite (hexagonal) and reconstituted Na-SnS ₂ -rG-O- titanate (B) NSGT0 (o), (c) NSGT1 (△), (d) NSGT2.5 (), and (d) NSGT5 (◇).
Figure 14 shows an example of an embodiment of the present invention using an equivalent circuit (illustration) for the manufactured cell of NSGT0 (O), NSGT1 (), NSGT2.5 (), and NSGT5 (FIG. 14A) and an expanded EIS spectrum (FIG. 14B) at high-medium frequencies (circles and solid lines represent experimental data and calculated data, respectively).
Figure 15 shows, in one embodiment, a powder XRD pattern of an electrochemically-cycled nanocomposite: (a) NSGT0, (b) NSGT1, (c) NSGT2.5, and (d) NSGT5.
Figure 16 is, in one embodiment of the present application, FE-SEM image (Fig. 16A), EDS- element map (Fig. 16B), the powder XRD pattern (Fig. 16C), and a current capacity of 100 mAg discharge capacity at ^-1 vs . Shows the number of cycles a graph (FIG. 16D) of: (a) a Na-MoS ₂ layer enrolled nanocomposite and Na-MoS ₂ -rGO- titanate nanocomposite (b) NMGT0 (○), (c) NMGT1 (△ ), (d) NMGT 2.5 (□), and (e) NMGT 5 (◇).
17 is a graph showing the relationship between discharge capacity vs. current density at a current density of 100 mA in one embodiment of the present invention. It shows a graph of the number of _{cycles: (a) Na-SnS 2} -rG-O nanocomposite (○), (b) Na- SnS 2 -rG-O- titanate (□) (c) Na- SnS 2 - rG-O-RuO ₂ (◇), and (d) Na-SnS ₂ -rG-O-MnO ₂ (Δ), and the content of metal oxide nanosheets is 2.5 wt% with respect to all nanocomposites.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be understood, however, that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the same reference numbers are used throughout the specification to refer to the same or like parts.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected" but also includes the case where it is "electrically connected" do.

Throughout this specification, when a member is " on " another member, it includes not only when the member is in contact with the other member, but also when there is another member between the two members.

Throughout this specification, when an element is referred to as " including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise. The terms " about ", " substantially ", etc. used to the extent that they are used throughout the specification are intended to be taken to mean the approximation of the manufacturing and material tolerances inherent in the stated sense, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure. The word " step (or step) " or " step " used to the extent that it is used throughout the specification does not mean " step for.

Throughout this specification, the term " combination (s) thereof " included in the expression of the machine form means a mixture or combination of one or more elements selected from the group consisting of the constituents described in the expression of the form of a marker, Quot; means at least one selected from the group consisting of the above-mentioned elements.

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

Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these embodiments and examples and drawings.

The first aspect of the present invention provides a layered inorganic nanosheet-graphene composite comprising a first inorganic nanosheet, a second inorganic nanosheet, and a layered structure formed by re-layering graphene.

In one embodiment of the present invention, there is provided a layered inorganic nanosheet-graphene composite produced by a simple method of re-layering inorganic nanosheets and graphenes using cations at room temperature. Specifically, since the first inorganic nanosheet, the second inorganic nanosheet, and the graphene are all negatively charged, they can be uniformly mixed with each other, and the cation of the added cation- .

In one embodiment herein, the re-deposited layered inorganic nanosheet-graphene composite may comprise cations, for example, the first inorganic nanosheet, the second inorganic nanosheet, And may include the cation between the fins.

In one embodiment of the invention, the first inorganic nanosheets and the graphenes may optionally be mixed in a layered structure, and a small amount of the second inorganic nanosheets may be present between the layers of the layered structure have.

In one embodiment, the first inorganic nanosheet is selected from the group consisting of Zn, Mo, Sn, Cd, W, Pb, Bi, Zr, Nb, Ge, Ga, In, But may be, but not limited to, a metal decalcogenide nanosheet. For example, the first inorganic nano-sheet _{SnS 2, MoS 2, WS 2} , TiS 2, ZnS 2, GaS 2, SnSe 2, MoSe 2, or however be to include Bi ₂ Se _3, without limitation, .

In one embodiment of the present application, the second inorganic nanosheet comprises an oxide nanosheet of a metal selected from the group consisting of Ti, Ru, Co, Cu, Zn, Mn, Mo, V, Ni, But is not limited thereto. For example, the second inorganic nanosheet may include, but is not limited to, TiO ₂ , MnO ₂ , MoO ₂ , RuO ₂ , CoO ₂ , or V ₂ O ₅ .

In one embodiment of the invention, the cation-containing solution may be one containing ^{Na +, H +, Li +} , Mg 2 +, Ca ^{2 +,} or a cation. For example, the cation-containing solution, but may be to include HCl, HNO _3, LiCl, LiNO _3, NaCl, NaCO _3, NaNO _3, MgCl _2, or CaCl _2, it may not be limited thereto.

In one embodiment of the invention, the first inorganic nanosheet and the graphene may be mixed in a ratio of about 5: 1.

In one embodiment of the present invention, about 0.5 part by weight to about 5 parts by weight of the second inorganic nanosheet may be included with respect to about 100 parts by weight of the graphene. For example, about 0.5 part by weight to about 5 parts by weight, from about 0.5 to about 4 parts by weight, from about 0.5 to about 3 parts by weight of the second inorganic nanosheet, relative to about 100 parts by weight of the graphene, About 0.5 parts to about 2 parts, about 0.5 parts to about 1 part, about 1 part to about 5 parts, about 2 parts to about 5 parts, about 3 parts to about 5 parts, , Or from about 4 parts by weight to about 5 parts by weight.

In one embodiment of the present invention, when a composite in which a small amount of the metal oxide nanosheets are added is used as an electrode material, the battery performance can be improved, and it is possible to improve the cell performance Capacity and improved cycle stability. In addition, the addition of the metal oxide nanosheets can prevent the graphenes from being reallocated in the battery charge / discharge process.

According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: peeling a first inorganic nanosheet and a second inorganic nanosheet; Mixing the peeled first inorganic nanosheet, the peeled second inorganic nanosheet, and the graphen sheet; And adding a cation-containing solution to the mixture to obtain the layered inorganic nanosheet-graphene composite on which the peeled first inorganic nanosheet, the peeled second inorganic nanosheet, and the graphene are re-laminated Graphene nanocrystalline graphene nanoparticle-graphene composite.

In one embodiment of the invention, the layered inorganic nanosheet-graphene composite is formed by the reaction of a positive charge of the first inorganic nanosheet, the second inorganic nanosheet, and the graphene negative and cation- But may not be limited thereto.

In one embodiment herein, the re-deposited layered inorganic nanosheet-graphene composite may comprise cations, for example, the first inorganic nanosheet, the second inorganic nanosheet, And may include the cation between the fins.

In one embodiment of the invention, the first inorganic nanosheets and the graphenes may optionally be mixed in a layered structure, and a small amount of the second inorganic nanosheets may be present between the layers of the layered structure have.

In one embodiment of the invention, the reaction may be performed at ambient temperature, but is not limited thereto.

In one embodiment, the first inorganic nanosheet is selected from the group consisting of Zn, Mo, Sn, Cd, W, Pb, Bi, Zr, Nb, Ge, Ga, In, But may be, but not limited to, a metal decalcogenide nanosheet. For example, the first inorganic nano-sheet _{SnS 2, MoS 2, WS 2} , TiS 2, ZnS 2, GaS 2, SnSe 2, MoSe 2, or however be to include Bi ₂ Se _3, without limitation, .

In one embodiment of the present application, the second inorganic nanosheet comprises an oxide nanosheet of a metal selected from the group consisting of Ti, Ru, Co, Cu, Zn, Mn, Mo, V, Ni, But is not limited thereto. For example, the second inorganic nanosheet may include, but is not limited to, TiO ₂ , MnO ₂ , MoO ₂ , RuO ₂ , CoO ₂ , or V ₂ O ₅ .

In one embodiment of the invention, the cation-containing solution may be one containing ^{Na +, H +, Li +} , Mg 2 +, Ca ^{2 +,} or a cation. For example, the cation-containing solution, but may be to include HCl, HNO _3, LiCl, LiNO _3, NaCl, NaCO _3, NaNO _3, MgCl _2, or CaCl _2, it may not be limited thereto.

In one embodiment of the invention, the first inorganic nanosheet and the graphene may be mixed in a ratio of about 5: 1.

In one embodiment of the present invention, about 0.5 part by weight to about 5 parts by weight of the second inorganic nanosheet may be included with respect to about 100 parts by weight of the graphene. For example, about 0.5 part by weight to about 5 parts by weight, from about 0.5 to about 4 parts by weight, from about 0.5 to about 3 parts by weight of the second inorganic nanosheet, relative to about 100 parts by weight of the graphene, About 0.5 parts to about 2 parts, about 0.5 parts to about 1 part, about 1 part to about 5 parts, about 2 parts to about 5 parts, about 3 parts to about 5 parts, , Or from about 4 parts by weight to about 5 parts by weight.

A third aspect of the invention provides a sodium ion cell comprising a layered inorganic nanosheet-graphene composite according to the first aspect of the present application.

Although the description of the third aspect of the present invention is omitted from the description of the first aspect of the present invention, the description of the first aspect of the present invention may be applied equally to the third aspect.

In one embodiment of the present invention, a layered inorganic nano-sheet-graphene composite can be prepared as a negative electrode material for a sodium ion battery by a simple method of re-depositing inorganic nanosheets and graphenes using cations at room temperature. Specifically, in the layered inorganic nano-sheet-graphene composite as the negative electrode material for a sodium ion battery, a cation-containing solution is added to a mixture of a metal chalcogenide nano-sheet and graphene, And a sheet can be mixed.

According to an embodiment of the present invention, since the metal chalcogenide nanosheets, the metal oxide nanosheets, and the graphenes are both negatively charged, they can be uniformly mixed with each other, and by the cation of the added cation-containing solution It can be easily re-laminated at room temperature to hybridize.

Also, according to one embodiment of the present invention, when a composite in which a small amount of the metal oxide nanosheets are added is used as the electrode material for the sodium ion battery, the battery performance can be improved, and the metal chalcogenide nano- And can provide improved capacity and improved cycle stability over one case. In addition, the addition of the metal oxide nanosheets can prevent the graphenes from being reallocated in the battery charge / discharge process.

In one embodiment of the present invention, the sodium ion cell may include, but is not limited to, the layered inorganic nanosheet-graphene composite as a cathode.

In one embodiment of the invention, the layered inorganic nanosheet-graphene composite comprised in the sodium ion cell comprises Na + cations in a mixture of the first inorganic nanosheet, the second inorganic nanosheet, and graphene Containing solution to be used in the present invention, but the present invention is not limited thereto.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto.

[ Example ]

< Example  1: Layered Weapon Nanosheet - Grapina  Preparation and Characterization of Composites>

Peeled SnS ₂ Nanosheet  Produce

SnS ₂ 1 g (MK Nano) was placed in 20 mL of 1.6 M n-butyllithium (Sigma-Aldrich) and reacted at room temperature for 5 days in an inert atmosphere. The n-butyllithium which had not reacted with excess hexane (JUNSEI) was then washed and dried. 0.1 g of the dried sample was dispersed in 100 mL of distilled water and stripped with ultrasound (Branson 5510) for 10 hours.

Reduced oxidation Grapina ( reduced graphene oxide , rGO ) Synthesis of

46 mL of 98% H ₂ SO ₄ (tertiary reagent) was added to 2 g of graphite powder (Graphit Kropfmuhl AG) and 6 g of KMnO ₄ (Sigma-Aldrich) was slowly mixed. The mixture was stirred in an ice bath to prevent the temperature from rising sharply. Thereafter, the mixed material was stirred at 35 DEG C for 2 hours. Then, add 92 mL of excess distilled water, react for 10 minutes, add 280 mL of distilled water, and mix 5 mL of 30% H ₂ O ₂ solution (tertiary reagent). The obtained material was washed with an HCl solution (tertiary reagent) and excess water to remove impurities. Then, after drying at 50 DEG C, the dried powder obtained was dispersed in water at a concentration of 0.1 wt% through ultrasonic waves (Branson 5510). 100 mL of the obtained oxidized graphene colloid and 100 mL of distilled water were mixed and then 100 μL of 34.5% hydrazine and 700 μL of 36.5% NH ₄ OH (tertiary amine reagent) Lt; / RTI &gt; Then, to remove excess hydrazine and NH ₄ OH remaining in the obtained graphene sheet colloid, dialyzed with distilled water.

Peeled TiO ₂ Nanosheet  Produce

Cs ₂ CO ₃ (Sigma-Aldrich) and TiO ₂ (Sigma-Aldrich) were mixed at a molar ratio of 1: 5.3 and heat-treated at 800 ° C. After the heat treatment, acid treatment with 1 M HCl (tertiary amine reagent) solution was carried out. Thereafter, a solution of tetrabutylammonium hydroxide (Sigma-Aldrich) was added and stripped for 10 days.

SnS ₂ / Grapina / TiO ₂ Synthesis of complex

The peeled SnS ₂ obtained in the above example The colloid, graphene sheet colloid, and exfoliated TiO ₂ colloid were mixed. The exfoliated SnS ₂ colloid and the graphene sheet colloid were mixed at a mass ratio of 5: 1, and the TiO ₂ nanosheets were mixed with 0.5 wt% to 5 wt% of the graphene sheet. To the mixture was slowly dropped 0.5 M sodium chloride solution to obtain a precipitated complex. The resultant composite was washed with water and freeze-dried to obtain a synthesized SnS ₂ / graphene / TiO ₂ composite.

Of sodium ion battery  Produce

The mixture of SnS ₂ / Graphene / TiO ₂ composite, Super P, CMC (carboxymethyl cellulose) and PAA [poly (acrylic acid)] prepared in the above example was mixed at a ratio of 80: 10: 5: 5 Thereafter, a mixed solution of anhydrous alcohol and distilled water at a ratio of 2: 3 (volume ratio) was mixed and loaded on an Al foil, followed by drying in an oven at 120 ° C for 10 hours. After drying, a 2032-type coin cell was fabricated and stabilized for a day after fabrication, and the charge and discharge test was performed using a maccor equipment.

<Analysis result>

(A) to (c) of Figure 1, each of the material prepared in Example SnS ₂ man enrolled layer a material, SnS ₂ and So a hybridization the pin material, and SnS ₂ / Yes hybridizing pin / TiO ₂ And a powder X-ray diffraction pattern (Rigaku D / Max-2000 / PC) of a material. As shown in FIGS. 1 (a) to 1 (c), all the peaks of all the materials showed a similar pattern, and it was confirmed that the material was a layered structure through the 001 peak (FIG. In addition, it was found that even if graphene sheets were mixed with SnS ₂ and a graphene sheet, they still had a structure similar to that of layered SnS ₂ (FIG. 1 (b)), and SnS ₂ and graphene hybrid As a result of measurement of the material synthesized by adding a small amount of TiO _{2, it} was found that a small amount of the layered metal oxide nanosheets were uniformly distributed between the graphene sheets through the absence of peaks of the TiO ₂ nanosheets (FIG. 1 (c) ].

(A) to (c) of Figure 2, each of the material prepared in Example SnS ₂ man enrolled layer a material, SnS ₂ and So a hybridization the pin material, and SnS ₂ / Yes hybridizing pin / TiO ₂ (FE-SEM, JEOL JSM-6700F) image of one material. As shown in FIGS. 2 (a) to 2 (c), it was confirmed that all the materials had a porous nanosheet shape.

(A) to (c) of Figure 3, each of the material prepared in Example SnS ₂ man enrolled layer a material, SnS ₂ and So a hybridization the pin material, and SnS ₂ / Yes hybridizing pin / TiO ₂ As a transmission electron microscope (FE-TEM, JEOL JEM-2100F) image of one material, it was found that all of the nanosheets were the same as in the FE-SEM image of FIG. 2. The graphene sheet and the SnS ₂ nanosheet It is confirmed that they are well mixed.

Figures 4a to 4c, each of the above embodiments of SnS ₂ man enrolled layer a material, SnS ₂ and So is a test result of sodium ion half-cell of a hybridize the pin material in the material prepared in: the left side of charge and discharge capacity graph and (Red: 1 cycle, blue: 2 cycles, and green: 3 cycles). The voltage range was from 0.01 V to 2.5 V, and the current density was measured at 200 mAh / g. The results of FIGS. 4A to 4C are summarized in Table 1 below.

[Table 1]

As shown in Table 1 and FIGS. 4A to 4C, it can be seen that the charge / discharge capacity can be improved by hybridizing with the graphene among the synthesized materials, and it is also possible to improve the charge / discharge capacity by adding a small amount of TiO ₂ as the layered metal oxide nanosheet (About 470 mAh / g improvement). &Lt; tb &gt;&lt; TABLE &gt;

< Example  2: Na - SnS ₂ - rG -O- Titanate ( NSGT ) Preparation and Characterization of Nanocomposites>

Preparation of Precursor Colloidal Suspension (Dispersion)

A colloidal suspension of reduced graphene oxide (rG-O) nanosheets was synthesized by the modified Hummers method. RG-O was synthesized using GO (graphene oxide) suspension (200 mL, 0.5 gL ^{- 1} ). Ammonia solution (1,400 L, 28 wt%) and hydrazine solution (200 L, 35 wt%) were added to the GO suspension. The resulting suspension was heated at 85 占 폚 for 1 hour and then cooled to room temperature. After the reaction, the resulting rG-O suspension was dialyzed with distilled water to remove excess hydrazine and ammonium ions. Synthesis of the exfoliated layered titanate nanosheets was carried out by HCl treatment on the Cs _0.67 Ti _1.83 O ₄ material of the original lepidocrocite structure followed by intercalation of tetrabutylammonium (TBA) Lt; / RTI &gt; Another precursor of SnS ₂ nanosheets was prepared by dissolving LiSi ₂ (1 g) in bulk SnS ₂ (1 g) in n-BuLi (30 mL, 1.6 M) for 5 days in an aqueous solution of the colloidal suspension by reaction with distilled water (150 mL) . To remove lithium ions, the suspension of the obtained exfoliated SnS ₂ nanosheets was dialyzed with distilled water. The concentration of the colloidal suspension of SnS ₂ nanosheets was 4 g L ^-1 .

Na-SnS ₂ Synthesis of -rG-O-titanate (NSGT) nanocomposite

The anionic nanosheets of rG-O, SnS ₂ , and layered titanate were re-assembled at the same time as Na ⁺ cations by electrostatic attraction to synthesize re-laminated NSGT nanocomposites. The NSGT nanocomposite was synthesized by adding NaCl solution (200 mL, 0.5 M) to a colloidal mixture of three component nanosheets (100 mL). The electrostatically induced aggregates of these anionic nanosheets occurred using Na ⁺ ions. The resulting precipitate was separated by centrifugation, sufficiently washed with distilled water, and freeze-dried. The supernatant was kept clear and all component nanosheets were thoroughly mixed with the NSGT nanocomposite. The mass ratio of the SnS ₂ : rG-O: titanate component was NSGT 0 for 5: 1: 0, NSGT 1 for 5: 1: 0.01, NSGT 2.5 for 5: 1: 0.025, NSGT2. A reference sample of Na-SnS ₂ nanocomposite was synthesized by adding NaCl solution (200 mL, 0.5 M) to the colloidal suspension of SnS ₂ nanosheet (100 mL).

Characteristic Analyzer

The surface charge of the precursor colloidal suspension of the peeled rG-O, SnS ₂ , and layered titanate nanosheets and the zeta potential of their mixtures were measured. The powder XRD pattern of the nanocomposite material of this Example 2 was measured with a Philips diffractometer using monochromatic Cu K? Radiation at room temperature. The crystal form and complex structure of the nanocomposite of Example 2 were investigated through FE-SEM, HR-TEM, and EFTEM analysis. EDS-element mapping analysis was performed to determine the elemental composition and spatial distribution of the nanocomposites. Sn K-edge and Ti K-edge XANES spectra were collected at beamline 10C of the Pohang Accelerator Laboratory (PAL). The XANES experiments were performed in transmission mode at room temperature. All XANES spectra were energy-calibrated simultaneously with the reference spectral measurements of Sn or Ti metals. Data analysis of the XANES spectrum was made by previously reported procedures. Micro Raman spectra of NSGT nanocomposites were collected using Horiba Jobin-Yvon Rabram Aramis spectrometer and Ar ion laser (λ = 633 nm) was used as the excitation source. N ₂ adsorption-desorption isotherms were measured at 77 K to determine the surface area of the nanocomposites. Prior to the measurement, the sample was degassed under vacuum at 120 캜 for 3 hours.

Electrochemical measurement

The Na ion battery (NIB) electrode activity of the nanocomposite of this Example 2 was measured by a constant current charge / discharge cycle test. Electrochemical measurements were performed on a 1 M NaClO ₄ / composite electrode in Na / ethylene carbonate (EC): diethyl carbonate (DEC) (50:50 vol%) (95 vol%) and fluoroethylene carbonate (FEC) 2032 coin type cell. A glass fiber GF / D filter was used as the separator. The composite electrode was prepared by mixing the active material (80 wt%), super P conductor (10 wt%), and sodium carboxymethyl cellulose (CMC): polyacrylic acid (PAA) (50: 50 wt% - anhydrous alcohol mixture (60: 40vol%), the composite slurry was applied to an Al metal foil and vacuum dried at 120 ° C for 10 hours. Electrochemical cycling tests were performed in constant current mode using Maccor multichannel galvanostat / potentiostat. A constant potential range of 0.01 to 2.5 V was used at a variable current density. The EIS data of the NSGT nanocomposites were recorded with an IVIUM impedance analyzer in the frequency range of 100 kHz to 10 mHz at the open circuit potential.

Synthesis and Characterization of Precursor Colloidal Suspension

Three precursor nanosheets of rG-O, SnS ₂ , and layered titanate were prepared in the form of an aqueous colloidal suspension by a soft-chemical stripping process of the initial material. All of these precursor nanosheets are uniformly mixed with one another to form a uniform stable colloid mixture. This is due to the general negative charge surface charge of all precursor nanosheets with similar 2D sheet-like morphology as evidenced by zeta potential measurements. As shown in FIG. 5, these anionic nanosheets can be reassembled simultaneously with Na ⁺ cations by electrostatic attraction to form re-laminated NSGT nanocomposites. For reference, reassembled Na-SnS ₂ Nanocomposites are also prepared by re-deposition of Na ⁺ ions in the exfoliated SnS ₂ nanosheets.

Powder XRD, FE-SEM, and TEM analysis

The crystal structure of the NSGT and Na-SnS ₂ nanocomposite of Example 2 is investigated through powder X-ray diffraction (XRD) analysis. As shown in FIG. 6, bulk SnS ₂ is a layered SnS ₂ Lt; / RTI &gt; (JCPDS # 23-677). The re-deposited Na-SnS ₂ nanocomposites showed almost the same positions of the ( 001 ) peak and the bulk SnS ₂ , indicating that Na ⁺ ions were not inserted into the SnS ₂ layer. In addition, observations of clear ( 001 ) reflections on re-deposited Na-rG-O nanocomposites do not strongly suggest the formation of a well-aligned intercalation structure of Na ions into the rG-O layer. All NSGT nanocomposites of this Example 2 exhibit very broad diffraction characteristics corresponding to disordered filings of 2D nanosheets. The XRD peaks of rG-O and titanate nanosheets do not strongly suggest a homogeneous dispersion of SnS ₂ nanosheets in the hybrid matrix of rG-O and titanate nanosheets.

7A shows a field emission scanning electron microscope (FE-SEM) image of NSGT and Na-SnS ₂ nanocomposites. All of the above nanocomposites show a mesoporous house-of-cards-type laminate structure of sheet-like microcrystals showing the formation of mesopores upon formation of a composite.

A transmission electron microscope (TEM) image of the reconstituted Na-SnS ₂ nanocomposite as well as the NSGT nanocomposite is shown in FIG. 7B. The laminate structure of nanosheets was commonly confirmed in all nanocomposites. As shown in FIG. 7C, high resolution transmission electron microscopy (HR-TEM) analysis showed the presence of lattice stripes corresponding to the {010} plane of graphene, the {100} plane of SnS ₂ , and {130} Clearly demonstrate. A layered titanate for the nanocomposite of NSGT0 and NSGT2.5, emphasizes uniform hybridization of SnS _2, rG-O and the layered titanate in these materials. 7D, the energy-filtered transmission electron microscope (EF-TEM) -element map of the NSGT2.5 nanocomposite showed a homogeneous distribution of Na, Sn, S, C and Ti, and SnS ₂ , rG-O , And layered titanate nanosheets. Homogeneous complex formation was further confirmed by energy dispersive spectrometry (EDS) -element mapping analysis for all NSGT nanocomposites (FIG. 8). In the EDS analysis, the molar ratio of Na: SnS ₂ was 1: 1 for all NSGT nanocomposites, corresponding to a Na content of 5 wt%.

X-ray absorption edge  The nearby microstructure (X- ray absorption near edge structure , XANES), micro-Raman, and N ₂ Adsorption-desorption isotherm analysis

The chemical bond properties of NSGT nanocomposites were investigated by XANES and micro Raman spectroscopy. 9A shows Sn K-edge XANES spectra of NSGT nanocomposites, re-deposited Na-SnS ₂ nanocomposites, and various reference samples. Regardless of the presence of rG-O and titanate nanosheets, all nanocomposites exhibit nearly the same edge energy as SnS ₂ , a reference sample material that exhibits the tetravalent oxidation state of Sn ⁴⁺ ions in these materials. All of the nanocomposites show a major-edge peak A corresponding to the 1s → 5p transition allowed for the dipole. The main edge spectral characteristics of the nanocomposite is almost equal to the reference sample of SnS _2, clearly it shows the successful combination of the stacked SnS _2.

Figure 9B shows the Ti K-edge XANES spectra of NSGT nanocomposites and some reference samples. The edge energy of the NSGT nanocomposite is approximately equal to the edge energy of the anatase TiO ₂ , rutile TiO ₂ , and lepidocrocite- and titanate-type layered titanates, indicating the ^quaternary Ti ^{4 +} valence state in these materials . There are several pre-edge peaks P1, P2, and P3 corresponding to dipole-forbidden transitions from the 1s orbit to the 4p orbit, and their spectral characteristics include the local atomic arrangement of titanium ions Reflect sensitively. Observation of similar pre-edge spectral properties for the layered titanate having the structure of the NSGT nanocomposite and the reversed cocite and trititanate type strongly suggests incorporation of the layered titanate nanosheets into this material. Several major-edge peaks A, B, and C associated with the 1s → 4p transition where the dipole is allowed are shown for all materials. The main-edge spectral characteristics of the NSGT nanocomposites are closer to those of the tri-titanate type, which is a combination of rG-O and SnS ₂ nanosheets, Lt; / RTI &gt; The XANES results provide strong evidence for the binding of SnS ₂ and titanate nanosheets in the NSGT nanocomposite of this Example 2, although the distinct XRD peaks of SnS ₂ and titanate are not discernable.

Figure 10A shows the reference samples of the micro Raman spectra and rG-O and initial SnS ₂ of NSGT and Na-SnS ₂ nanocomposites. As with rG-O, all NSGT nanocomposites, regardless of titanate addition, generally exhibit two intense Raman peaks D and G above 1,000 cm ^-1 , demonstrating the presence of graphene nanosheets in the material. The D and D 'peaks are related to the process of resonant scattering due to graphene defects such as sp ³ - defects or vacancy-like defects. Observation of the D 'peak shows that there is a public-type defect rather than sp ³ - defect. The G peak corresponds to the Raman active mode of the graphene species. The NSGT nanocomposites exhibit a higher D / G ratio than the reference sample rG-O, indicating improved structural failure of the graphene nanosheets during complex formation (FIG. 10B). The increase in titanate content means that the ratio of D / G peak is reduced, so that the incorporation of titanate nanosheets reduces the structural strain of graphene. Since the decrease in the D / G peak ratio is due to the increase in the distance between the defects, the spectral change due to the increase in the titanate content is caused by the shielding of the resonance scattering and the rG- O &lt; / RTI &gt; defects. In the low wavenumber region below 500 cm ^-1 , both the initial SnS ₂ and Na-SnS ₂ nanocomposites show typical phonon lines on layered SnS ₂ . As shown in FIG. 10A, these SnS ₂ -related Raman features appear for titanate-free NSGT 0 nanocomposites, whereas titanate nanosheet-incorporated NSGT nanocomposites exhibit near-complete depression of SnS ₂ -related phonon lines. Since XANES results indicate the incorporation of SnS ₂ nanosheets into the NSGT nanocomposites, observation of the SnS ₂ -related Raman peaks for the titanate-containing nanocomposites was confirmed by the addition of titanate nanosheets to rG-O Leading to complete shielding of SnS2-related Raman scattering by the electron cloud of adjacent graphene nanosheets, not due to the enhanced interaction with nanosheets. Given the fact that the titanate-free NSGT0 nanocomposite displays SnS ₂ -related Raman peaks, this observation can be interpreted as a strong evidence for an improved mixing of SnS ₂ and rG-O upon incorporation of titanate nanosheets.

The pore structure and surface area of the NSGT nanocomposites are shown by N ₂ adsorption-desorption isotherms analysis (FIG. 11). Surface area calculations based on the Brunauer-Emmett-Teller (BET) equation show that the surface area of the NSGT nanocomposite is 24 m ² g ^-1 for NSGT ⁰ , 25 m ² g ^-1 for NSGT ¹ , 30 m ² g ^{-1 for} NSGT 2.5 , And NSGT5 were calculated to be 39 m ² g ^-1 and surface area increased by the interposition of the layered titanate nanosheets. The pupil size distribution of the hybrid nanocomposite is calculated by the Barrett-Joyner-Halenda (BJH) equation (FIG. 11). All nanocomposites exhibit an average pupil size of ~ 3.2 to 3.7 nm and represent the formation of a mesopore with a house-of-cards laminate structure. As shown in FIG. 11B, the incorporation of the layered titanate nanosheets improves the mesopore-related peaks indicating an increase in the pupil. This result can be interpreted as a strong evidence for a decrease in the tendency of the graphene nanosheets to be laminated due to the intervention of the hard metal oxide nanosheets without? Electrons.

Electrochemical cycling test

The incorporation of titanate nanosheets on the Na ion battery (NIB) electrode activity of the re-deposited Na-SnS ₂ -rG-O nanocomposite was tested as an anode material of the NIB using the NSGT nanocomposite of Example 2 . 12 is a Na-SnS ₂ This graph shows a constant current charge / discharge potential graph of the NSGT nanocomposite as well as the nanocomposite. All nanocomposites show a sloped plateau of about 1.0 to 1.6 at the first discharge profile corresponding to the insertion of Na ⁺ ions into the lattice {001} plane on the SnS ₂ layer. Another sloping plateau at ~ 0.7 V corresponds to irreversible conversion and alloying reactions of SnS ₂ , as well as to the formation of a solid-electrolyte-interface (SEI) layer. The conversion reaction in the potential region is preferably performed in such a manner that SnS ₂ is Sn and Na ₂ S or Na ₂ S ₂ (SnS ₂ + 8Na ⁺ + 8e ^- ? 3Sn + 4Na ₂ S or SnS ₂ + 2Na ⁺ + 2e ^- ? Sn + 2Na ₂ S ₂ ). The alloying reaction between Sn and Na ⁺ cycles is less pronounced at the first tilted plateau at higher potentials than that occurring in the first cycle, and the disappearance of the amorphous layer into the layered SnS ₂ lattice promoting the reaction rate . In the charge curve, all materials show a plateau at 1.0-1.2 V, corresponding to the extraction of Na ⁺ ions from the Na-S phase and the modification of SnS ₂ . The low content of titanate nanosheets in the NSGT nanocomposite prevents experimentally observing the redox properties of the additive species in the potential graph. Compared to the re-deposited Na-SnS ₂ nanocomposite, the titanate-free Na-SnS ₂ -rG-O (NSGT 0) nanocomposites exhibit much greater charge and discharge capacities, which improves the electrode activity of the SnS ₂ material Emphasize the advantages of conjugation with rG-O. As can be clearly seen in FIG. 12, even with a small amount of titanate, the addition of titanate nanosheets additionally increases the charge / discharge capacity of the NSGT0 nanocomposite without significant change in the overall potential graph. This result highlights the remarkable effect of interconnection between SnS ₂ , rG-O, and layered titanate nanosheets in electrode activity. As the electrochemical cycling progresses from 2 cycles to 100 cycles, all NSGT nanocomposites generally do not show a significant change in the potential graphs, indicating high electrochemical stability.

Discharge capacity and coulomb efficiency vs. NSGT nanocomposite of Example 2 The cycle number graph shows that the re-assembled Na-SnS ₂ 13A in comparison with the nanocomposite. All NSGT nanocomposites demonstrate much better electrode performance than rG-O / titanate-free Na-SnS ₂ nanocomposites, emphasizing the benefits of co-hybridization with rG-O and layered titanate nanosheets. In the first cycle, all nanocomposites exhibit significant capacity loss due to the formation of the SEI layer. After the first cycle, the titanate bound nanocomposites of NSGT1, NSGT2.5, and NSGT5 exhibit 450, 485, and 420 mAhg ^-1 , respectively, and the titanate-free NSGT0 and re-deposited Na-SnS ₂ nanocomposite Respectively. After the initial several cycles, all materials exhibit high coulombic efficiency of> 95% and exhibit high electrochemical stability with highly reversible insertion / extraction of Na ⁺ ions. Addition of the layered titanate nanosheets significantly improves the discharge capacity of the Na-SnS ₂ -rG-O nanocomposite even at a low content (? 2.5 wt%) of the titanate nanosheets, Nate emphasized the merits of nanosheets. Above an optimum content of 2.5 wt%, further addition of titanate nanosheets causes a slight drop in discharge capacity, which is due to a decrease in the electrochemically most active SnS ₂ content and an increase in the broad bandgap semiconductor titanate additive . All of the above materials exhibit remarkably good circulation characteristics and exhibit high electrochemical stability: discharge capacity of the 100th cycle is NSGT0 ~ 390 mAhg- ¹ , NSGT1 ~ 405 mAh- ¹ , NSGT2.5 ~ 465 mAh ^-1 , and NSGT5 is ~ 405 mAh ^-1 .

In addition, the evolution of the rate characteristics upon incorporation of the layered titanate nanosheets was observed at various current densities (Figure 13B). At higher current densities, larger discharge capacities were generated for the titanate-containing nanocomposites of NSGT1, NSGT2.5, and NSGT5 than for the titanate-free NSGT0 analogs, resulting in a metal dicalcogenide graphene nano- Emphasize the advantages of titanate nanosheets as additives to improve composite speed performance. Summarizing the results of the electrochemical measurements, the addition of titanate nanosheets provides an effective way to optimize the discharge capacity and rate characteristics of metal chalcogenide-graphene nanocomposites.

The effect of titanate addition on the charge transfer rate of the Na-SnS ₂ -rG-O nanocomposite at the interface between the electrode and the electrolyte was studied using electrochemical impedance spectroscopy (EIS). 14A shows an EIS spectrum of an electrochemically cyclized NSGT nanocomposite. As shown in FIG. 14B, a similar EIS curve consisting of sloping lines in the semicircle and low-frequency regions in the high-medium frequency region occurs commonly for all materials of the second embodiment. In order to obtain quantitative information on the charge transfer rate, an equivalent circuit includes an electrolyte resistance R _s , a polarization resistance R _f , a surface film capacitance C _f , a charge transfer resistance R _ct , A double layer capacitance (C _dl ), and Warburg impedance (W _o ) (see FIG. 14).

The parameters obtained are listed in Table 2 below. The NSGT 2.5 and NSGT 5 nanocomposite incorporating titanate exhibited a smaller charge transfer resistance (R _ct ) of 155.3 and 215.4 Ω, respectively, compared to NSGT 0 (229.5 Ω) without titanate, and the addition of titanate nanosheets Emphasizes the improvement of the charge transfer speed. The observed improvement in charge transfer rate at the interface between the electrode and electrolyte upon incorporation of the titanate nanosheets is associated with increased porosity through degradation of the severe self-stacking of the rG-O nanosheets. The NSGT 2.5 nanocomposite with the best NIB electrode performance among the materials of this Example 2 exhibits the lowest charge transfer resistance. This indicates that the enhancement of the charge transfer rate at the interface contributes further to the improvement of the electrode performance upon incorporation of titanate nanosheets.

[Table 2]

Powder XRD analysis on electrochemically cyclized material

The evolution of the crystal structure of the nanocomposite to electrochemical cycling was confirmed by powder XRD analysis of the cyclized material. 15 shows a powder XRD pattern of an electrochemically cyclized NSGT nanocomposite. All nanocomposite materials generally exhibit weak Bragg reflection of Sn metals as well as intense peaks of Al substrates. The incorporation of the layered titanate nanosheets inhibits the XRD peak of the Sn metal to prevent agglomeration of the electrode material during electrochemical cycling. This result shows an enhanced dispersion of the SnS ₂ material in the hybrid matrix of the layered titanate and rG-O nanosheets, and is also advantageous for improving the electrode performance of SnS ₂ .

On the basis of all the above-mentioned experimental results, it was found that the addition of the titanate nanosheet significantly improves the NIB electrode activity of the Na-SnS ₂ -rG-O nanocomposite has the following effects: (1) The mixed titanate nanosheet Na ⁺ ion extension of the surface area generated by providing more reaction sites for the storage of, (2) active intimate bonding to the conductive rG-O nanosheet that SnS facilitate the electrochemical insertion of the Na ⁺ ions for the _two materials (3) improvement of the charge transfer rate at the interface between the electrode and the electrolyte in relation to the optimization of the pore structure, and (4) hybrid matrix of re-laminated nanosheets which prevents agglomeration of the electrode material Improved dispersion of SnS ₂ microcrystals in.

< Example  3: Na - MoS ₂ - rG -O- Titanate ( NMGT ) Preparation and Characterization of Nanocomposites>

The universal validity of stripped metal oxide nanosheets as an additive to optimize the electrode performance of metal chalcogenide-graphene nanocomposites has been demonstrated using MoS ₂ , another metal chalcogenide.

For the synthesis of the Na-MoS ₂ -rG-O-titanate (NMGT) nanocomposite, in the NSGT nanocomposite preparation method of Example 2, SnS ₂ The same method as that of the NSGT nanocomposite was used except that the nanosheet was replaced with an MoS ₂ nanosheet. Na-MoS ₂ -rGO-titanate nanocomposites with titanate / rG-O ratios of 0, 0.01, 0.025, and 0.05 were prepared and designated NMGT0, NMGT1, NMGT2.5, and NMGT5, respectively. Note that the implicit floor Na -MoS ₂ nanocomposites also MoS ₂ exfoliated with Na ⁺ ions It is synthesized by reclamation of nanosheets.

Repackaging of MoS ₂ , rG-O, and layered titanate nanosheets with formation of the porous laminate structure was confirmed by FE-SEM analysis (Fig. 16A). Figure 16B in EDS- elemental map of a homogeneous distribution of Na, Mo, S, C, and Ti provides clear evidence for the MoS _2, rG-O, and the layered titanate uniform hybrid nano sheeted. As shown in FIG. 16C, powder XRD analysis clearly demonstrates the incorporation of MoS ₂ nanosheets in all nanocomposites of this Example 3. As shown in FIG. 16D, electrochemical measurements indicate a significant improvement in Na ion electrode functionality of the Na-MoS ₂ -rG-O nanocomposite upon incorporation of the layered titanate nanosheets.

To verify the universal merits of the stripped metal oxide nanosheets, other Na-SnS ₂ -rG-O-metal oxide nanocomposites were synthesized using MnO ₂ and RuO ₂ nanosheets as additives. This material was used as a Na ion electrode to analyze the effect of these metal oxide nanosheets on NIB electrode performance (FIG. 17). Like the incorporation of titanate nanosheets, the MnO ₂ and RuO ₂ nanosheets significantly improve the NIB electrode activity of the Na-SnS ₂ -rG-O nanocomposite and provide various metal oxides The general usefulness of nanosheets was confirmed.

<Conclusion>

The present invention provides an efficient method for producing high performance NIB electrode materials through co-hybridization of metal chalcogenide nanosheets with exfoliated titanates and rG-O nanosheets. The incorporation of small amounts of layered titanate nanosheets is highly effective in significantly improving the Na ion storage capacity and cycle characteristics of the Na-SnS ₂ -rG-O nanocomposite. Improved electrode performance of such titanate nanosheet-incorporated NSGT nanocomposites is believed to result in more reaction sites for Na ⁺ ions, improved charge transfer rates at the interface between the electrodes and the electrolyte, Lt; _{RTI ID = 0.0} &gt; SnS2 &lt; / RTI &gt; The universal advantage of the synthetic process according to the invention is evident by the remarkable improvement of the electrode performance of the re-deposited MoS ₂ -grained nano-composite in the addition of titanate nanosheets. Co-hybridization of the exfoliated metal oxide and rG-O nanosheet is very useful for optimizing various functions of metal chalcogenide such as electrocatalyst, photocatalyst, redox catalyst and the like. The synthetic method according to the present application can be applied to various combinations of metal chalcogenide and metal oxide nanosheets to produce new high performance energy-functional nanocomposite materials.

It will be understood by those of ordinary skill in the art that the foregoing description of the embodiments is for illustrative purposes and that those skilled in the art can easily modify the invention without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (10)

A first inorganic nano-sheet, a second inorganic nano-sheet, and a layered structure formed by re-
As a layered inorganic nanosheet-graphene composite,
The first inorganic nano-sheet may include a dicalcogenide nanosheet of a metal selected from the group consisting of Zn, Mo, Sn, Cd, W, Pb, Bi, Zr, Nb, Ge, Ga, In, And the second inorganic nanosheet comprises an oxide nanosheet of a metal selected from the group consisting of Ti, Ru, Co, Cu, Zn, Mn, Mo, V, Ni, , Layered inorganic nanosheet-graphene composites.
delete The method according to claim 1,
Wherein the second inorganic nanosheet is contained in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the graphene.
Peeling the first inorganic nanosheet and the second inorganic nanosheet;
Mixing the peeled first inorganic nanosheet, the peeled second inorganic nanosheet, and graphene; And
Obtaining a layered inorganic nano-sheet-graphene composite on which the peeled first inorganic nanosheet, the peeled second inorganic nanosheet, and the graphene are re-laminated by adding a cation-containing solution to the mixture;
Grafted nanosheet-graphene composite, comprising the steps of:
The first inorganic nano-sheet may include a dicalcogenide nanosheet of a metal selected from the group consisting of Zn, Mo, Sn, Cd, W, Pb, Bi, Zr, Nb, Ge, Ga, In, And the second inorganic nanosheet comprises an oxide nanosheet of a metal selected from the group consisting of Ti, Ru, Co, Cu, Zn, Mn, Mo, V, Ni, , A method for producing a layered inorganic nanosheet-graphene composite.
5. The method of claim 4,
Wherein the layered inorganic nano-sheet-graphene composite is re-laminated by the reaction of a positive charge of the first inorganic nanosheet, the second inorganic nanosheet, and a negative charge and a cation-containing solution of the graphene, / RTI &gt; A method of making a sheet-graphene composite.
6. The method of claim 5,
Wherein the reaction is carried out at room temperature.
delete 5. The method of claim 4,
It said cation-containing solution is a ^{Na +, H +, Li +} , Mg 2 +, Ca ^{2 +,} or the layered inorganic nano-sheets comprises a cation-method of manufacturing a graphene composite.
5. The method of claim 4,
Wherein the second inorganic nanosheet is contained in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the layered inorganic nano-sheet-graphene composite.
A sodium ion battery comprising a layered inorganic nanosheet-graphene composite according to any one of claims 1 to 3.

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